Materials, panels and uses thereof

Abstract

The present disclosure relates to a catalytic panel comprising at least one catalytic material and at least one substrate, wherein the at least one catalytic material is directly associated with the substrate, to particulate matter comprising a catalytic material, uses thereof and method of using them.

Description

[0001] MATERIALS, PANELS AND USES THEREOF

[0002] TECHNOLOGICAL FIELD

[0003] The present disclosure relates to materials, panels uses thereof and method making use thereof.

[0004] BACKGROUND ART

[0005] References considered to be relevant as background to the presently disclosed subject matter are listed below:

[0006] Photocatalysis is an attractive enabler of the efficient execution of different important environmental (e.g., production of hydrogen and C-based fuels) and organic reactions utilizing solar energy [l]-[5].

[0007] Acknowledgement of the above references herein is not to be inferred as meaning that these are in any way relevant to the patentability of the presently disclosed subject matter.

[0008] BACKGROUND

[0009] [1] X. Lang, X. Chen, J. Zhao, Chem. Soc. Rev. 2014, 43, 473-486.

[0010] [2] Y. Bai, L. Wilbraham, B. J. Slater, M. A. Zwijnenburg, R. S. Sprick, A. I. Cooper, J. Am. Chem. Soc. 2019, 141, 9063-9071.

[0011] [3] A. Savateev, I. Ghosh, B. Konig, M. Antonietti, Angew. Chem. Int. Ed. 2018, 57, 15936-15947.

[0012] [4] J. Xiao, X. Liu, L. Pan, C. Shi, X. Zhang, J.-J. Zou, ACS Catal. 2020, 10, 12256-12283.

[0013] [5] K. S. Lakhi, D.-H. Park, K. Al-Bahily, W. Cha, B. Viswanathan, J.-H. Choy, A. Vinu, Chem. Soc. Rev. 2017, 46, 72-101. GENERAL DESCRIPTION

[0014] In accordance with some aspects, the present disclosure provides a catalytic panel comprising at least one catalytic material and at least one substrate, wherein the at least one catalytic material is directly associated with the substrate.

[0015] In accordance with some other aspects, the present disclosure provides a catalytic panel comprising at least one catalytic material and at least one substrate, wherein the at least one catalytic material is polymeric carbon nitride (CN) or modified CN (C-to-N ratio, heteroatom incorporation, functional groups modification, or metal incorporation), and the substrate is glass and wherein the CN is directly attached on at least one surface of the glass.

[0016] In accordance with some other aspects, the present disclosure provides a catalytic panel comprising at least one catalytic material and at least one substrate, wherein the at least one catalytic material is polymeric carbon nitride (CN) or modified CN, and the substrate is glass and wherein the CN is directly attached on at least one surface of the glass.

[0017] In accordance with some further aspects, the present disclosure provides a catalytic panel comprising at least one catalytic material and at least one substrate, wherein the at least one catalytic material is WO3and the substrate is glass and wherein said WO3is directly attached on at least one surface of the glass.

[0018] In accordance with yet some aspects, the present disclosure provides a catalytic panel comprising at least one catalytic material and at least one substrate, wherein the at least one catalytic material is polymeric CN and the substrate is a thermoplastic polymer and wherein the CN is at least partially embedded within the thermoplastic polymer.

[0019] In accordance with yet some other aspects, the present disclosure provides a catalytic panel comprising at least one catalytic material and at least one substrate, wherein the at least one catalytic material is WO3and the substrate is a thermoplastic polymer and wherein the WO3is at least partially embedded within the thermoplastic polymer.

[0020] In accordance with yet some other aspects, the present disclosure provides a catalytic panel as described herein for use in a photocatalytic reaction or electrocatalytic reaction. In accordance with yet some other aspects, the present disclosure provides a catalytic panel as described herein for use in a method of production of hydrogen peroxide

[0021] In accordance with yet some other aspects, the present disclosure provides a catalytic panel as described herein for use in a method of oxidizing at least one organic compound.

[0022] In accordance with yet some other aspects, the present disclosure provides a catalytic panel as described herein for use in a method of oxidizing at least one biomass derived product.

[0023] In accordance with yet some other aspects, the present disclosure provides a catalytic panel as described herein for use in a method of degrading a water pollutant.

[0024] In accordance with yet some other aspects, the present disclosure provides a catalytic panel as described herein for use in a method of oxidizing a hydroxyl-containing compound.

[0025] In accordance with yet some other aspects, the present disclosure provides a catalytic panel as described herein for use in a method of oxidizing a hydroxyl-containing compound and of reducing oxygen.

[0026] In accordance with yet some other aspects, the present disclosure provides a catalytic panel as described herein for use as an electrode.

[0027] In accordance with yet some other aspects, the present disclosure provides an electrode comprising a catalytic panel, wherein the catalytic panel comprises at least one catalytic material and at least one substrate, wherein the substrate is a conductive substrate and wherein the at least one catalytic material is directly associated with the substrate.

[0028] In accordance with yet some other aspects, the present disclosure provides a particulate matter for use in a method of producing hydrogen, the particulate matter comprises at least one catalytic material.

[0029] In accordance with yet some other aspects, the present disclosure provides a photoreactor comprises at least one photocatalytic panel or particulate matter as described herein. In accordance with yet some other aspects, the present disclosure provides a method for producing hydrogen peroxide, the method comprising exposing a panel to a light source, wherein the panel comprises at least one catalytic material and at least one substrate, and wherein the catalytic material is directly associated to the substrate, to thereby produce hydrogen peroxide.

[0030] In accordance with yet some other aspects, the present disclosure provides a method for producing hydrogen peroxide, the method comprising exposing a panel to a light source, wherein the panel comprises at least one catalytic material and at least one substrate, wherein the at least one substrate is at least one polymer and wherein the catalytic material is at least partially embedded within the polymer, to thereby produce hydrogen peroxide.

[0031] In accordance with yet some other aspects, the present disclosure provides a method for producing hydrogen peroxide, the method comprising exposing a powder to a light source, wherein the powder comprises at least one catalytic material, wherein the catalytic material is configured to oxidize a hydroxyl-containing compound and reduce oxygen to thereby produce hydrogen peroxide.

[0032] In accordance with yet some other aspects, the present disclosure provides a method for oxidizing at least one biomass-derived product, the method comprising exposing a panel to a light source, wherein the panel comprises at least one catalytic material and at least one substrate, and wherein the catalytic material is directly associated to the substrate, to thereby oxidizing at least one biomass-derived product.

[0033] In accordance with yet some other aspects, the present disclosure provides a method for water purification, the method comprises exposing a panel to a light source, wherein the panel comprises at least one catalytic material and at least one substrate, and wherein the catalytic material is directly associated to the substrate, to thereby allow water purification

[0034] In accordance with yet some other aspects, the present disclosure provides a method for producing hydrogen, the method comprises exposing a panel to a light source, wherein the panel comprises at least one catalytic material and at least one substrate, and wherein the catalytic material is directly associated to the substrate, to thereby produce hydrogen. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In order to better understand the subject matter that is disclosed herein and to exemplify how it may be carried out in practice, embodiments will now be described, by way of non-limiting examples only, with reference to the accompanying drawings, in which:

[0036] Figures 1A-1B are schematic synthesis processes of binder-free carbon nitride (CN) panels showing Figure 1A “sandwich” method using melamine-cyanuric acid (MCA) supramolecular aggregates powder as the precursor, Figure IB doctor-blade assisted “sandwich” method.

[0037] Figure 2 is digital image of the obtained 10 x 10 cm2CNMCApanel.

[0038] Figures 3A-3G are digital images of the obtained 6.7 x 6.7 cm2CN and modified CN films over various substrates; Figure 3A-3E on glass substrate: Figure 3A - CND, Figure 3B - CNMe1-CA, Figure 3C -CNMCAB(0.05), Figure 3D - CNMCAB(O.O5)-500, and Figure 3E - CNMCAB(O.D; Figures 3F-3G on Aluminum (Al) foil: Figure 3F - CNMCA, and Figure 3G - CNM, D dicyanamide precursor, Mel melem.

[0039] Figures 4A-4C relate to structural and optical characterization of CN panels on different substrates showing Figure 4A FTIR spectra of CN panels on glass, Figure 4B on Al foil (all spectra are vertically offset for clarity), and Figure 4C UV-vis absorbance (as 100% - %transmittance - %reflectance) spectra of CN panels.

[0040] Figures 5A-5I relate to thickness characterization of CN panels, Figures 5A-5D cross-sectional SEM images of Figure 5A - clean glass (MCA-0), Figure 5B glass with 1 layer of MCA (MCA-1), Figure SC glass with 2 layers of MCA (MCA-2), Figure 5D glass with 3 layers of MCA (MCA-3), Figure 5E is a schematic synthesis process of binder-free CN panels, where the grey lines represent the doctor-bladed precursor layer and after calcination the resulting CN is shown in thick orange line, the thin yellow line represents thin CN from the powder sublimation only, Figures 5F-5I are cross-sectional SEM images of Figure 5F- CNMCA, Figure 5G - CNMCA-DI, Figure 5H - CNMCA-D, and Figure 51 - CNMCA-D3.

[0041] Figures 6A-6E are digital photos of 6.7 x 6.7 cm-2CN panels on glass substrate; Figure 6A clean glass, Figure 6B-6D CN panels prepared by “sandwich” method and Figure 6B - CNMCA; Figure 6C - CNMCA(1:I.5), Figure 6D CNM melamine as a precursor, Figure 6E CNMCA-D-

[0042] Figures 7A-7H relate to morphological and structural analyses of CN panels, Figures 7A-7B are top-view scanning electron microscopy (SEM) images of CNMCAand CNMCA-D, respectively, Figures 7C-7D cross-sectional SEM images of CNMCAand CNMCA-D, respectively, Figure 7E-7F top-view SEM images of CNM, and CNMCA(1:1.5), respectively, Figure 7G X-ray diffraction (XRD) of all CN panels over glass and a clean glass substrate as reference, and Figure 7H Fourier-transform infrared (FTIR) spectra of all CN panels; the XRD patterns and FTIR spectra are vertically offset for clarity.

[0043] Figures 8A-8E are FTIR spectra of CN powders (MCA), CN panels (CNMCA), and a bare glass substrate showing the interaction between the synthesized CN and the glass. Figure 8A CNMCApowder which is CN powder synthesized under identical conditions (precursor, temperature and heat profile, environment) but without being first deposited on a glass substrate and CNMCApanel which is the analog panel (CN grown on glass using the described method) where a cyano group appears ca. 2200 cm-1; inset shows the digital images of the powder and the panel, Figure 8B magnification of the spectra at wavenumbers ca. 810 cm-1, Figure 8C-8E glass, glass after scratching CNMCA, and CNMCApowder alone as a reference at three different IR regions.

[0044] Figures 9A-9B are structural and morphological characterization of a CNMCA-Dpanel showing Figure 9A FTIR spectra of a CNMCA-Dpanel, scratched powder, outer layer (i.e., outside the doctor-bladed area, deposition on glass), and bottom layer (i.e., the part of the panel from which the top layer was scratched off), Figure 9B top- view SEM image of CNMCA-Dpanel at the interface between the CNMCA-Dlayer (left side of the SEM image, obtained from doctor-bladed side of MCA precursor) and the outer layer (right side of the SEM image, where no doctor-blading took place).

[0045] Figure 10 is X-ray photoelectron spectroscopy (XPS) survey scan of all CN panels showing that the CNMCAand CNMCA(1:1.5) panels also exhibit Na A (Na Auger line) and Na Is peaks, which correspond to sodium from the glass since a lower thickness of CN films covers the glass substrate relative to the doctor-bladed sample or the CNM where 2 g melamine powder were used in the ‘sandwich’. Figures 11A-11B are high-resolution XPS deconvoluted spectra of CNMCAand CNMCA-Dshowing Figure 11A C Is signals and Figure 11B N Is signals; red circles represent the experimental measurement data points; the fitted curve is shown as a thin black line; the colored filled peaks represent the deconvoluted fits of individual chemical species indicated in the legend.

[0046] Figures 12A-12B are high-resolution XPS deconvoluted spectra of CNM and CNMCA(1:1.5)showing Figure 12A C Is signal and Figure 12B N Is signal; red circles represent the experimental measurement; thin black line is the fitted curve; colored filled peaks represent the deconvoluted fits of individual chemical species indicated in the legend.

[0047] Figures 13A-13C relate to optical characterization of different CN panels showing Figure 13A UV-vis diffuse reflectance spectra of CN panels, Figure 13B UV- vis absorption spectra (shown in units of absorbance percent), and Figure 13C Tauc plots of CN panels assuming a direct band gap for the estimation of the optical band gap, Eg, utilizing the Kubelka-Munk function, F(R).

[0048] Figures 14A-14D relate to charge separation and valence band energy characterizations of CNMCAand CNMCA-Dpanels showing Figure 14A photoluminescence (PL) spectra of CNMCA-Dand CNMCA(excitation wavelength: / Lx = 380 nm), Figures 14B-14C ultraviolet photoelectron spectroscopy (UPS) of CNMCA-Dand CNMCA, respectively, showing extrapolated values of 19.8 and 4.55 eV for CNMCA-Dand 19.8 and 4.36 eV for CNMCA- Figure 14D band energy diagram based on an optical band gap estimation; y-axis shown presented using the normal hydrogen electrode (NHE) scale.

[0049] Figures 15A-15D relate to WO3panels, Figure 15A is a digital image of the obtained WO3panels, Figure 15B is a XPS survey scan spectra, Figure 15C is a high- resolution W 4f, Figure 15D is a high-resolution O 1s spectra of WO3-D obtained after 5 min sonication of pristine WO3-D.

[0050] Figure 16 is a schematic diagram of the experimental setup: the reactant solution is continuously pumped from a solvent reservoir (1) using a peristaltic pump through the inlet (2) and, after flowing in the photoreactor over the photocatalyst panel (yellow), flows out through the outlet (3) back into the solvent reservoir (4). The solvent reservoir is equipped with a rubber septum (5) for gas purging and liquid sampling. The films perform reduction (via electrons, e~) and oxidation (via holes, / z+) reactions. As examples 5- (hydroxymethyl)furfural (HMF) oxidation to 2,5-diformylfuran (DFF), water reduction to hydrogen (hydrogen evolution reaction, HER), and oxygen reduction to hydrogen peroxide (H2O2; pxygen reduction reaction, ORR).

[0051] Figures 17A-17B relate to a fabrication of the flow reactor, Figure 17A is a schematic diagram of the fabrication of the flow reactor; the CN panel (2) is placed on a base (1), followed by covering with the middle part (3); on the right, a magnified view of

[0052] (3) shows the inner volume (approximately ~25 mL) with solution inlet and outlet; a glass

[0053] (4) is placed on (3), and covered using the top part (5); the final reactor assembly step is closing and tightening using screws, Figure 17B shows continuous-flow photoreactor setup used for H2O2production.

[0054] Figures 18A-18D relate to production of H2O2using different CN panels, Figure 18A shows performance comparison between different CN panels in photoreactor at 2 and 4 h; reaction conditions: 6.7 x 6.7 cm2CN panel, 80 mL of 20% vol. EtOH in H2O, 100 W LED light irradiation (2680 W m-2), flow rate ~1 mL min-1, Figure 18B shows comparison of H2O2formation rate over CNMCA-Das a panel (flow) and as a powder (batch), Figure 18C shows comparison of H2O2activity with the recent state-of-the-art metal-free g-C3N4(graphitic C3N4) based photocatalysts (see also Table 2), and Figure 18D shows control experiments.

[0055] Figures 19A-19B relate to LED spectrum, Figure 19A shows white LED spectrum (measured at the illuminated panel’s distance), and Figure 19B shows normalized absorbance of CNMCA-D(left y-axis) and the normalized irradiation spectra (right y-axis) of the illumination source — the white LED.

[0056] Figure 20 is UV-vis spectral evolution of salicylic acid during H2O2production experiment.

[0057] Figures 21A-21B are SEM images of CNMCA-Dpanel after performing H2O2production reaction for 4 h, Figure 21A 40 μm scale bar and Figure 21B 4 μm scale bar; the insets show the digital images of the CNMCA-Dpanel after a 4 h reaction.

[0058] Figures 22A-22B relate to structural and optical characterization of the fresh CNMCA-Dpanel and after 4 h of H2O2production showing Figure 22A is a FTIR spectra and Figure 22B is an UV-vis spectra. Figures 23A-23E relate to H2O2production using CNMCA-DXpanels of different thicknesses showing Figure 23A shows a schematic representation of CN panels with varying thickness (CNMCA-DX, where x = 1, 2, or 3): the total CN film thickness increases from 29 μm for one precursor doctor-bladed layer (CNMCA-DI), to 37 pM of two layers (labelled as CNMCA-D), to 68 μm of three layers (CNMCA-D3); Figure 23B shows produced H2O2concentration vs. thickness of the CN panels; Figure 23C shows UV-vis diffuse reflectance spectra, Figure 23D shows transmittance spectra, and Figure 23E shows UV-vis absorption spectra — calculated as 100% - %transmittance - %reflectance — of all CN panels.

[0059] Figure 24 shows depiction of suggested H2O2formation mechanism in the presence of ethanol.

[0060] Figure 25 is UV-vis spectra recorded during H2O2production reaction probing for 1,5-dihydroxynaphthalene (1,5-DHN), which reacts with singlet oxygen to form Juglone.

[0061] Figures 26A-26C relate to HMF photocatalytic oxidation, Figure 26A is a general scheme for photocatalytic HMF oxidation using a CNMCA-Dpanel, Figure 26B shows HMF photooxidation at different times; reaction conditions: 6.7 x 6.7 cm2CNMCA- D panel, 80 mL of 5 mM HMF in H2O, 100 W LED light irradiation (2680 W m-2, as shown above), flow rate ~1 mL min-1, Figure 26C shows comparison of HMF conversion rate with the recent state-of-the-art photocatalysts.

[0062] Figure 27 shows H2O2production in parallel with HMF oxidation over time.

[0063] Figures 28A-28B are high-performance liquid chromatography diode-array detection (HPLC-DAD) profiles of continuous-flow HMF photooxidation reaction using CNMCA-Dpanel measured at regular intervals; monitoring at λ = 288 nm (Figure 28 A) and λ = 210 nm (Figure 28B), detected substances include unreacted HMF and the products DFF, Maleic acid, formic acid (HCOOH) and 2,5-furandicarboxylic acid (also known as 5 -formylfuroic acid, FFCA).

[0064] Figures 29A-29B are HPLC-DAD profiles of DFF photooxidation in presence of H2O2(aq) using CNMCA-Dpowder measured after 4 h reaction at λ = 210 nm (Figure 29 A) and λ = 288 nm (Figure 29B); reaction conditions: 5 mg CNMCA-Dpowder, 5 mL of 1 mM DFF in H2O, 100 μL of aqueous H2O2solution (30% wt.), 100 W LED light irradiation (2680 W m-2).

[0065] Figures 30A-30B are SEM images of a CNMCA-Dpanel after 24 h of HMF oxidation reaction, a scale bar of 40 μm (Figure 30A) and a scale bar of 20 μm (Figure 30B).

[0066] Figures 31A-31C relate to characterization of a CNMCA-Dpanel before and after 24 h of HMF oxidation reaction; Figure 31A is XRD patterns, Figure 31B is FTIR, and Figure 31C is UV-vis spectra; the XRD patterns and FTIR spectra are vertically offset for clarity.

[0067] Figures 32A-32D relate to HMF photooxidation, Figures 32A and 32B are HPLC-DAD profiles of HMF photooxidation in presence and absence of NaN3and 1,4- benzoquinone (ρ-BQ) CNMCA-Dpowder measured after 2 h at λ = 288 nm (Figure 32A) and at λ = 210 nm (Figure 32B); reaction conditions: 5 mg CNMCA-Dpowder, 5 mL of 1 mM DFF in H2O, 10 mM NaN3or p-BQ (30% wt.), 100 W LED light irradiation (2680 W m-2), Figure 32C is a UV-vis spectra recorded during HMF photooxidation reaction probing for 1,5-DHN; reaction conditions: 5 mg CNMCA-Dpowder, 5 mL of 1 mM DFF in H2O, 1 mM DHN, 100 W LED light irradiation (2680 W m-2), Figure 32D is a photograph showing diluted aliquots (1 mL), taken at regular 15 min intervals, for UV- vis absorbance measurement and H2O2test papers measuring the corresponding solutions during HMF photooxidation reaction probing for 1,5-DHN.

[0068] Figure 33 shows proposed mechanism for HMF photooxidation over CNMCA-D.

[0069] Figures 34A-34D relate to the analysis of 9-(2-carboxyphenyl)-6-(diethylamino)- N,N-diethyl-3H-xanthen-3-iminium chloride, abbreviated as rhodamine B (RhB) degradation, Figure 34A is a schematic diagram of a continuous-flow RhB degradation experiment continuously measuring absorbance via UV-vis spectrometry; the RhB solution is continuously pumped out from the solvent reservoir using a peristaltic pump through the photoreactor, the monitored UV cuvette, and back to the reservoir, Figure 34B is an in-line UV-vis spectral change of the RhB dye reactant during the photodegradation experiment; reaction conditions: 6.7 x 6.7 cm2CN panel, 80 mL of 1 M RhB(aq) solution, 100 W LED light irradiation, flow rate ~1 mL min-1, Figure 34C shows RhB degradation over time, and Figure 34D shows pseudo-first-order kinetics approximation for RhB degradation over a CNMCA-Dpanel; kexp= 7.9 x 10-3min-1.

[0070] Figures 35A-35C relate to H2 production, Figure 35A shows a reaction setup for H2 production; reaction conditions: 6.7 x 6.7 cm2CNMCApanel, 25 mL of 20% vol. of EtOH in DI water; 100 W white LED irradiation, 20 pL of 8% wt. of chloroplatinic acid (elemental composition estimation using EDS shows -3.7% wt. of Pt on the panel after initial photodeposition). Figure 35B is a digital photo of a CNMCApanel after H2 production reaction, and Figure 35C is a SEM image of a CNMCApanel after H2 production reaction.

[0071] Figure 36 is a schematic diagram of the proposed H2O2-mediated co-catalyst free H2 and HCOOH production over CNMCAphotocatalyst powders or panels in comparison with the traditional approach where a Pt co-catalyst is deposited before the reaction takes place.

[0072] Figures 37A-37B relate to CN powders, Figure 37A is a XRD spectra and Figure 37B is a FTIR spectra of CN powders.

[0073] Figures 38A-38C relates to surface characterization of CNMCA, Figure 38A is a XPS survey scan, Figure 38B is a high-resolution C Is, and Figure 38C is a high- resolution N Is spectra of CN.

[0074] Figures 39A-39B relate to optical characterization of CNMCAphotocatalyst powders, Figure 39A shows diffuse reflectance ultraviolet-visible spectrum DR-UV-vis and Figure 39B is a Tauc plot of CN.

[0075] Figure 40 is a XRD spectrum of bulk WO3.

[0076] Figures 41A-41B relate to bulk WO3, Figure 41A is a DR-UV-vis spectrum of Bulk WChand Figure 41B shows Tauc plot of Bulk WO3.

[0077] Figure 42 is a XRD spectrum of WO3NPs.

[0078] Figures 43A-43C relate to WO3NPs, Figure 43A is a XPS survey scan of WO3NPs, Figure 43B is a high-resolution W4f of WO3NPs, and Figure 43C is a high- resolution Ols spectra of WO3NPs.

[0079] Figures 44A-44B relate to WO3NPs, Figure 44A is a DR-UV-vis of WO3NPs and Figure 44B is a Tauc plot of WO3NPs. Figure 45 relates to visible-light driven co-catalyst free H2 production over CN and WO3photocatalysts showing the comparison of H2(g) production rate after 4 h under different conditions and the inset shows the H2 production after 24 h; reaction conditions: 20 mg of the catalyst, 5 mL of solution (described in the figure legend; best Pt-free CN after 4 hours in 20 vol% MeOH in 0.1 M NaOH(aq), static air, 40 °C, 100 W LED light irradiation (2680 W m-2).

[0080] Figure 46 is UV-vis spectra showing the formation of H2O2; reaction conditions: 20 mg of WO3NPs photocatalyst, 5 mL of 20 vol.% EtOH, 40 °C, static air, 100 W LED light irradiation (2680 W m-2).

[0081] Figures 47A-47B relate to WO3NPs, Figure 47A shows gas chromatography (GC) spectra of the gaseous products measured at different times using CN photocatalyst and Figure 47B shows WO3NPs as the photocatalyst.

[0082] Figures 48 shows control experiments in the dark; reaction conditions: 200 pL of HCHO (37% vol.) and 200 pL of H2O2(30% wt.), 4.6 mL of water / 0.1 M NaOH, static air. 1 mL of HCHO (37% wt.); for water 25 °C is used, for 0.1 M NaOH reactions at two temperatures are shown: 25 °C and 40 °C.

[0083] Figures 49A-49H relate to spectroscopic analysis of the chemical reaction during H2O2and HCHO formation and the ensuing chemical reaction between H2O2and HCHO in neutral and basic environments showing Figures 49A-49B UV-vis absorption spectral change of individual HCHO and H2O2in pure water, Figures 49C-49D UV-vis absorption spectral change of HCHO and H2O2, respectively, in 0.1 M NaOH for 1 h, Figures 49E-49F UV-vis absorption spectral change of H2O2and HCHO mixture in pure water and 0.1 M NaOH for 1 h, Figure 49G the FTIR spectra of HCHO in pure water and Figure 49H the FTIR spectra of mixture of H2O2and HCHO in pure water.

[0084] Figures 50A-50B relate to H2 production Figure 50A shows a proposed mechanistic path for H2O2-mediated H2 production from MeOH oxidation over WO3and Figure 50B shows comparison of H2 yields obtained under different conditions; reaction conditions: 20 mg of CN photocatalyst, 1 mL of MeOH or HCHO (37% vol. in water) or HCOOH (98% purity), 4 mL of 0.1 M NaOH, 20 mg CN, static air, 100 W LED light irradiation (2680 W m-2). Figures 51A-51B are UV-vis absorption spectra of reaction mixture treated with Nash reagent showing the formation of HCHO, Figure 51A CN photocatalyst and Figure 51B WO3NPs as the photocatalysts; reaction conditions: 20 mg of photocatalyst, 5 mL of 20 vol.% MeOH in pure water, 40 °C, static air, 100 W LED light irradiation (2680 W m-2).

[0085] Figure 52 is HPLC-PDA spectrum at λ = 210 nm, showing reference formate retention time (detecting formic acid).

[0086] Figure 53 is HPLC-PDA spectra at λ = 210 nm showing the synthesis of formic acid after 0 and 4 h.

[0087] Figure 54 shows comparison of H2 yields obtained under different conditions after 24 h.

[0088] Figures 55A-55B relate to scaling experiment Figure 55A shows scaling experiment; reaction conditions: 200 mg of the catalyst, 100 mL of 0.1 M NaOH (20 vol% of MeOH), static air, 100 W LED light irradiation (2680 W m-2) and Figure 55B cycle experiments; reaction conditions: 20 mg of catalyst, 5 mL of 0.1 M NaOH (20 vol% of MeOH), static air.

[0089] Figure 56 shows schematic representation of a plastic panel preparation process; an high-density polyethylene (HDPE) source (here, in the form of beads) is melted at 220 °C in an alumina template (demonstrated, size of 6.7 x 6.7 cm2), then the photocatalyst powder (as a representative example, CN) is spread and lightly pressed into the molten HDPE, and left to cool down to room temperature under ambient conditions; inset: scanning electron microscopy (SEM) image of the CN / HDPE panel (CN is artificially highlighted with a light-yellow hue).

[0090] Figures 57A-57B show HER batch reactor setups: digital photos of Figure 57A ‘standard’ photocatalytic experiment with CN powder in a reaction vessel of deionized water (DI) + 10% vol. EtOH as a hole scavenger illuminated through a water jacket for temperature control, and constantly stirred for continuous dispersion of the power photocatalyst, Figure 57B showing the plastic photocatalyst panel implementation: HDPE plastic waste as the source material is melted and covered with CN powder using the demonstrated method to get the CN photocatalyst panel, which is applied for photocatalysis as a panel in the reaction vessel similarly to the powder photocatalyst analog without requiring stirring.

[0091] Figures 58A-58D are digital photographs of different photocatalytic HDPE panels; Figure 58A Bi2O3 / HDPE, Figure 58B WO3 / HDPE, Figure 58C TiO2 / HDPE, and Figure 58D ZnO / HDPE.

[0092] Figures 59A-59D. Digital photographs of CN photocatalyst on different plastic supports, Figure 59A Polypropylene (PP), melted at 200 °C, Figure 59B Ethylene vinyl- acetate (EVA), melted using a commercial hot glue gun (-100 °C), Figure 59C Poly(methyl methacrylate) (PMMA), melted at 180 °C, Figure 59D Low-density Polyethylene (LDPE), melted at 180 °C.

[0093] Figures 60A-60J are SEM images of Figures 60A-60D HDPE after melting and cooling down, Figures 60E-60H CN / HDPE panel, and Figures 60I-60J cross-sectional view of CN / HDPE panel.

[0094] Figures 61A-61D relate to CN / HDPE panel, Figure 61A is a focused ion beam (FIB)-assisted cross-section SEM image. Figures 61B-61C are energy-dispersive X-ray spectroscopy (EDS) mapping of the cross-sectional CN / HDPE panel image, Figure 61B carbon, and Figure 61C nitrogen, Figure 61D is a SEM image of the area from which the FIB cross-section was taken, highlighted in orange.

[0095] Figure 62A-62C relate to CN / HDPE panel, Figure 62A a top-view SEM image of the panel, Figure 62B carbon EDS elemental map, Figure 62C nitrogen EDS elemental map.

[0096] Figures 63A-63D relate to structural and optical characterization of CN-2-C1- mlm photocatalyst showing Figure 63A FTIR spectra of CN-2-Cl-mlm powder, the prepared HDPE panel (after heat treatment, before photocatalyst deposition), and CN-2- Cl-mlm / HDPE panel; Figure 63B XRD pattern of HDPE and CN-2-Cl-mlm / HDPE panel, Figure 63C diffuse reflectance UV-vis (proportional to absorption) spectra of CN- 2-Cl-mlm powder and CN-2-Cl-mlm / HDPE panel; Figure 63D photocatalytic ORR (H2O2production) action spectrum with CN-2-Cl-mlm / HDPE panel: left y-axis is the DR-UV-vis while the right y-axis is the photocatalytically produced H2O2.

[0097] Figures 64A-64E are high-resolution X-ray photoelectron spectroscopy (XPS) spectra showing Figure 64A C Is of pure HDPE after melting and natural cooling down back to room temperature, Figure 64B C Is of CN-2-Cl-mlm / HDPE panel, Figure 64C N Is of CN-2-Cl-mlm / HDPE panel, Figure 64D C Is of CN-2-Cl-mlm powder, and Figure 64E N Is of CN-2-Cl-mlm powder.

[0098] Figures 65A-65B show schematic representation of flow and batch photocatalytic processes; Figure 65A oxygen reduction reaction (ORR) in a flow reactor configuration, 25 cm2panel with a 100 mL reservoir of O2saturated 10% EtOH in DI, at a flow rate of 1 mL min-1, Figure 65B hydrogen evolution reaction (HER) in a batch configuration, 4.0 cm2panel (with Pt nanoparticles photo-deposited prior to reaction) with 10 mL of 10% EtOH in DI and 18.5 mL headspace washed with 99.999% argon gas.

[0099] Figures 66A-66E relate to oxygen reduction reaction (ORR) and H2 production, Figure 66A is a schematic representation of energy diagram of oxygen reduction reaction (ORR) over a CN photocatalyst, Figure 66B 3 subsequent cycles of ORR — each of a 6- hour duration — performing ORR over a CN-2-Cl-mlm / HDPE panel; the first 4 h cycle is performed in pure DI, followed by three subsequent 6 h cycles in the presence of 10% v / v EtOH (in DI), serving as the hole scavenger, Figure 66C is a schematic representation of energy diagram of photocatalytic HER in a batch reaction over a Pt@CN-2-Cl- mlm / HDPE panel, Figure 66D shows stability test for HER with 3 cycles of 4 hours each — a total 12 hours of photocatalytic reaction: a preliminary 4 h cycle is performed in pure DI, followed by three subsequent 4 h cycles in the presence of 10% vol. EtOH (in DI), serving as the hole scavenger, with detected and quantified produced H2, Figure 66E shows the long term (7 days) photocatalytic H2 production using a 4 x 1 cm2CN-2-C1- mlm / HDPE panel (2.5% wt. Pt as co-catalyst) in a batch reactor with a 20 mL of 10% EtOH in DI.

[0100] Figure 67 shows long-term H2O2production (ORR) using a 5 x 5 cm2CN-2-C1- mlm / HDPE panel, in a flow reactor configuration with a 100 mL of 1 M D-Glucose in DI reservoir, and a 25 cm2cell, under 100 W white LED illumination and oxygen atmosphere.

[0101] Figure 68 shows H2O2production (ORR) using a 5 x 5 cm2CN-2-Cl-mlm / HDPE panel, in a flow reactor configuration with a 100 mL of 0.36 M of 4-methoxy benzyl alcohol in DI reservoir, and a 25 cm2cell, under 100 W white LED illumination and oxygen atmosphere. Figures 69A-69D relate to H2 production, Figure 69A shows a batch reaction setup for the use of a CN film over glass: a CNMCA-D panel, Figure 69B shows CN / HDPE panel Figure 69C shows a batch reaction setup used for large-scale H2 production from 20 vol% MeOH in 100 mL of 0.1 M NaOH using a CN / HDPE photocatalyst panel, Figure 69D shows CN / HDPE panel after 24 h reaction.

[0102] Figures 70A-70B relate to CN panel electrode, Figure 70A shows CNMCA-Dpanel over fluorine-doped tin oxide coated glass substrate (FTO), Figure 70B shows schematic of the experimental setup used for electrochemical (EC) (panel is anode) and photoelectrochemical (PEC) (panel is photoanode) methanol oxidation experiments.

[0103] Figures 71A-71F relate to CN panel electrode, Figure 71A is a LSV curve of CNMCA-Dpanel electrode in presence of 30 vol.% MeOH aqueous solution, Figure 71B is a chronoamperometry curve of CNMCA-Dpanel electrode recorded at 1.23 V vs. RHE in presence of 30 vol.% MeOH aqueous solution for 1 h, Figure 71C is a UV-vis absorption spectra of electrochemically produced HCHO with Nash reagent, Figure 71D is a photocurrent response and Figure 71E is a chronoamperometry curve of CNMCA-Dpanel electrode recorded at 1.23 V vs. RHE in presence of 30 vol.% MeOH aqueous solution and Figure 71F UV-vis absorption spectra of photoelectrochemically produced HCHO with Nash reagent.

[0104] DETAILED DESCRIPTION OF EMBODIMENTS

[0105] The present disclosure is directed to catalytic materials and catalytic panels with tunable structural and physical properties that can be used in a wide range of applications, including sustainable energy production and environmental remediation.

[0106] A key aspect of this disclosure is a universal approach of binder-free catalyst panels, which exhibit enhanced stability and performance in various catalytic reactions.

[0107] The novel binder-free panel enable the association of various catalytic materials, including inter alia, polymeric carbon nitrides, metal oxides and metal sulfides onto and / or within different supports, including, such as glass, doped glass, metals, metal oxides, doped metal oxides or different plastic materials.

[0108] As demonstrated below, these binder- free catalytic panels have been successfully integrated into photoreactors, such as continuous-flow reactors, for a variety of applications. These applications include hydrogen peroxide and hydrogen production, water purification, decontamination, and organic transformations. Specifically, the catalytic panels have been proven highly effective in the production of hydrogen and hydrogen peroxide, oxidation of biomass-derived compounds (for example 5- hydroxymethylfurfural), and water purification.

[0109] An additional key aspect of this disclosure pertains to catalytic materials in the form of particulate matter, such as powders. These materials were unexpectedly successful in indirectly producing hydrogen gas. As demonstrated below, the unique activity of these catalytic materials is attributed to their ability to couple hydrogen peroxide (H2O2) production with the oxidation of a hydroxyl-containing compound. The produced H2O2spontaneously reacts with the oxidation product of the hydroxyl- containing compound to generate hydrogen (H2). Notably, these materials can be used either in powder form or integrated into the panels, as described herein.

[0110] This indirect method of hydrogen production is particularly significant for materials that are unable to directly reduce water to hydrogen gas as it offers a novel pathway for hydrogen generation. This property enhances the versatility and potential impact of such materials in energy production and other industrial processes, where efficient and scalable hydrogen generation is critical.

[0111] Taken together, the panels and materials described herein offer a versatile platform for various catalytic processes.

[0112] Hence, in accordance with some aspects, the present disclosure is directed to a binder free catalytic panel that comprises a catalytic material and a substrate material. In other words, the disclosure is directed to catalytic panel that comprises a catalytic material and a substrate material, wherein the catalytic panel is binder free.

[0113] In the following text, when referring to the catalytic panel it is to be understood as also referring to a catalytic material, a catalytic composite material, a catalytic particulate matter, a catalytic powder, uses, methods, and processes, disclosed herein. Thus, whenever providing a feature with reference to the catalytic panel, it is to be understood as defining the same feature with respect to the catalytic material, a catalytic composite material, a catalytic particulate matter, a catalytic powder, uses, methods, and processes, mutatis mutandis. As shown herein, the catalytic material can be used as is (for example, in powder form) or can be attached / deposited / associated or formed on or within a substrate. In cases where the catalytic material is associated with the substrate as described herein, this association occurs without the use of binding agents (binders), meaning that the association is achieved without addition of a binder. Typically, these binders are used to hold the catalytic material together or affix it to a substrate.

[0114] It was suggested that the absence of binders may enhance catalytic activity by increasing the number of active sites available for reactions and improving the overall stability of the panel, as well as enhancing light management, thereby allowing for more efficient energy use in processes like photocatalysis. Additionally, it was proposed that when the catalytic material is held by physical interactions within the substrate (for example, when the substrate is a polymer), the absence of binders reduces unwanted chemical reactions during the catalytic process (e.g. photocatalytic reactions), compared to situations where a binder is present at the catalytic sites. Furthermore, it was suggested that the lack of binders prolongs the attachment of the catalytic material and diminishes or prevents the leaching of the photocatalytic material.

[0115] Binder as used herein refers to a substance that is generally used to hold together or attach catalytic materials to a substrate, ensuring stability and uniformity as well as maintaining mechanical strength, improving adhesion, or maintaining the integrity of the material during catalytic reactions.

[0116] Non-limiting examples of binders include binders comprising ferfluoro groups, for example, Nafion or SiO2binders.

[0117] In some examples, the panel is binder-free.

[0118] In some examples, the panel is essentially free of a binder.

[0119] In the configuration described herein, i.e., in the binder-free panel, the catalytic material is in direct contact with the substrate (e.g., directly integrated) without the use of any binders or adhesives. Thus, the panel, in accordance with the present disclosure, is self-supporting, meaning there is no need for any binder to provide support, such as structural support and / or mechanical support. Hence, in accordance with some aspects, the present disclosure provides a panel comprising at least one catalytic material and at least one substrate, wherein the catalytic material is directly associated to the substrate.

[0120] The term panel as used herein refers to a flat or slightly curved, typically thin material or structure used as a platform in various applications.

[0121] In some examples, the panel is a catalytic panel.

[0122] The term catalytic panel as used herein refers to a panel that facilitates reactions by providing an active surface for the reactions to occur, often accelerating the rate of reactions without being consumed in the process.

[0123] In some examples, the panel is a photocatalytic panel. In some other examples, the panel is an electrophotocatalytic panel.

[0124] The term associated (or association) as used herein refers to the presence or connection of the catalytic material on at least part of the substrate or within at least part of the substrate.

[0125] The term directly associated, as used herein, indicates that the catalytic material is in direct contact with the substrate, without the need for intermediary layers such as adhesives, binders, or other agents. In this configuration, the catalytic material adheres or integrates with the substrate either through a physical process (e.g., partial melting, deposition / attachment) or a chemical interaction, forming a stable interaction that enhances the material's performance. It was suggested that this direct attachment can improve the efficiency of the catalytic reactions by maximizing the exposure of the active catalytic surface to reactants. Furthermore, since there is no binder present that could be prone to chemical attack, the overall stability of the system is improved, leading to longer lasting and more reliable catalytic performance.

[0126] The association may be in some examples by a process in which the catalytic material is applied onto the substrate or within the substrate.

[0127] The method may be for example a process described herein, for example, a process that is schematically shown in Figure 1 A and denoted herein as “sandwich” or as schematically shown in Figure IB and denoted herein as "doctor-blade assisted “sandwich” or alternatively as the process that is schematically shown in Figure 56. It should be noted that the process schematically shown in Figure 56 may be applicable to substrate material that is or comprises a polymer as further described herein.

[0128] In some examples, the association between the catalytic material and the substrate is by chemical bond. In some examples, the chemical bond may be Van der Waals forces or covalent bonding. In some examples, the association between the catalytic material and the substrate is by physical embedding.

[0129] As described herein the substrate material is characterized by having at least one surface on which the catalytic material is attached to or embedded within. The surface may be described in accordance with some examples as an outer layer of the substrate, e.g. an outermost part of the substrate where the catalytic material is either attached (on the surface) or embedded (within the substrate).

[0130] In some examples, the at least one catalytic material is at least partially associated on the substrate material. It should be noted that in this configuration, the catalytic material is attached to the surface of the substrate without significant penetration or incorporation into the substrate's internal structure.

[0131] In some examples, the at least one catalytic material is at least partially (minimum) embedded within the substrate material. It should be noted that in this configuration, the catalytic material is integrated within the substrate, often involving partial or complete enclosure by the substrate material. In other words, the catalytic material may have exposed regions for interaction.

[0132] The association between the catalytic material and the substrate may include various forms of association.

[0133] In some examples, the at least one catalytic material is homogeneously associated with the substrate material. The term homogeneously associated should be noted as if the catalytic material is uniformly distributed across the surface of the substrate, ensuring that all regions of the substrate have an equal amount of the catalyst.

[0134] In some examples, the at least one catalytic material is heterogeneously associated with the substrate material. The term heterogeneously associated should be noted as if the catalytic material is not uniformly distributed across the substrate. In such cases, the non- uniformity can be due to varying thicknesses, localized clusters, or regions with different concentrations of the catalytic material. In some examples, the at least one catalytic material is associated with the substrate material in layers. The term layered associated should be noted as if multiple layers of catalytic material (identical or different materials) are applied to the substrate, either in a stacked or stratified manner.

[0135] In some examples, the at least one catalytic material is associated with the substrate material in a patterned association. The term patterned associated should be understood as an association that involves selective association of the catalytic material in specific shapes or designs on the substrate.

[0136] In some examples, the at least one catalytic material is associated with the substrate material in a gradient association. The term gradient associated should be understood as if the concentration or composition of the catalytic material changes gradually across the substrate. This association may form a gradient of reactivity, with certain areas more active than others.

[0137] In some examples, the at least one catalytic material is associated with the substrate material in a porous association. The term porous associated should be understood as if the catalytic material forms a porous layer on the substrate, allowing for increased surface area and enhanced interaction with reactants. As noted herein, the pores can be on the nanoscale or microscale, depending on the desired application.

[0138] In some examples, the at least one catalytic material is associated with the substrate material in a multiphase association. The term multiphase associated should be understood as if the catalytic material consists of more than one phase (e.g., solid-solid or solid- liquid), which may include particles embedded in the substrate or different catalytic materials distributed in various phases.

[0139] The thickness of the catalytic material can be defined as uniform, variable, multilayered, or porous, depending on the application.

[0140] In some examples, the catalytic material may have a thickness of at least about 0.3 μm, at times at least about 0.5 μm, at times at least about 0.7 μm, at times at least about 1. μm, at times at least about 2 μm, at times at least about 3 μm, at times at least about 4 μm, at times at least about 5 μm, at times at least about 7 μm, at times at least about 10 μm, at times at least about 30 μm, at times at least about 50 μm, at times at least about 70 μm, at times at least about 100 μm, at times at least about 150 μm, at times at least about 200 μm, at times at least about 250 μm, at times at least about 300 μm, at times at least about 350 μm, at times at least about 400 μm, at times at least about 450 μm, at times at least about 480 μm.

[0141] In some examples, the catalytic material may have a thickness of about 0.3 μm, at times about 0.5 μm, at times about 0.7 μm, at times about 1 μm, at times about 2 μm, at times about 3 μm, at times about 4 μm, at times about 5 μm, at times about 6 μm, at times about 7 μm, at times about 8 μm, at times about 9 μm, at times about 10 μm, at times about 15 μm, at times about 20 μm, at times about 25 μm, at times about 30 μm, at times about 35 μm, at times about 40 μm, at times about 45 μm, at times about 50 μm, at times about 60 μm, at times about 70 μm, at times about 80 μm, at times about 90 μm, at times about 100 μm, at times about 120 μm, at times about 150 μm, at times about 170 μm, at times about 200 μm, at times about 230μm, at times about 250 μm, at times about 270 pm, at times about 300 μm, at times about 320 μm, at times about 350 μm, at times about 370 μm, at times about 400 μm, at times about 420 μm, at times about 450μm, at times about 480 μm.

[0142] In some examples, the catalytic material may have a thickness of between about 0.3 μm to about 500 μm, at times between about 0.3 μm to about 450 μm, at times between about 0.3 μm to about 400 μm, at times between about 0.3 μm to about 350 μm, at times between about 0.3 μm to about 300 μm, at times between about 0.3 μm to about 250 μm, at times between about 0.3 μm to about 200 μm, at times between about 0.3 μm to about 150 μm, at times between about 0.3 μm to about 100 μm, at times between about 0.3 μm to about 70 μm, at times between about 0.3 μm to about 60 μm, at times between about 0.3 μm to about 50 μm, at times between about 0.3 μm to about 40 μm, at times between about 0.3 μm to about 20 μm, at times between about 0.3 μm to about 10 μm, at times between about 0.3 μm to about 2 μm.

[0143] In some examples, the catalytic material may have a thickness of between about 0.7 μm to about 500 μm, at times between about 1 μm to about 500 μm, at times between about 5 μm to about 500 μm, at times between about 10 μm to about 500 μm, at times between about 20 μm to about 500 μm, at times between about 50 μm to about 500 μm, at times between about 70 μm to about 500 μm, at times between about 100 μm to about 500 μm, at times between about 120 μm to about 500 μm, at times between about 150 μm to about 500 μm, at times between about 170 μm to about 500 μm, at times between about 200 μm to about 500 μm, at times between about 250 μm to about 500 μm, at times between about 300 μm to about 500 μm.

[0144] In some examples, the catalytic material may have a thickness of between about 0.3 μm to about 100 μm, at times between about 0.7 μm to about 80 μm, at times between about 1 μm to about 70 μm, at times between about 1 μm to about 50 μm, at times between about 1 μm to about 40 μm.

[0145] It was suggested that the thickness of the catalytic material ensures sufficient light absorption, charge transport, and reactivity while maintaining mechanical stability.

[0146] The catalytic material as used herein refers to a substance that facilitates or accelerates a chemical reaction.

[0147] The present disclosure is not limited to a specific catalytic material and, as demonstrated in the examples below, may encompass various materials.

[0148] In some examples, the catalytic material is a photocatalytic material and / or a photo-electrocatalytic material.

[0149] The term photocatalytic material refers to a substance that facilitates a reaction upon exposure to light (absorption of light), usually from visible or ultraviolet light sources. In general, when photocatalytic material absorbs photons, it generates electron- hole pairs, which can participate in redox reactions.

[0150] The term photo-electrocatalytic material refers to a substance that utilizes light and electrical current to facilitate chemical reactions. In general, these materials have the ability to absorb photons (light) and use the resulting excited electrons and holes to participate in redox reactions. Simultaneously, an applied electrical bias helps drive the reaction forward, either by enhancing charge separation or by directly participating in electron transfer processes.

[0151] In some examples, the catalytic material is a semiconductor material.

[0152] The catalytic material is characterized in accordance with some examples by an optical bandgap (Eg) of at least about 0.8 eV, at times at least about 1.8 eV, with certain embodiments having a bandgap ranging from 0.8 to 5 eV. The bandgap is an important factor in determining the material’s ability to absorb light and drive catalytic reactions. Materials with a bandgap in this range are well suited for visible light-driven applications as further described herein below.

[0153] In some examples, the catalytic material is at least one of a carbon-based material, a metal and / or metal-containing material, a SiC, a covalent organic framework material (COFs), a metal-organic framework material (MOFs), a polyoxometalate material (POMs), a nanoparticle, or any combination thereof.

[0154] In some examples, the catalytic material is a carbon-based material.

[0155] In some examples, the carbon-based material is one or more of a polymeric CN, a modified CN, graphene, graphene oxide, reduced graphene oxide, graphite, carbon or inorganic nanotube, a carbon dot, a nitrogen-doped carbon or any combination thereof.

[0156] In some examples, the catalytic material is a polymeric CN (CxNy), which may contain a variable amount of H and O atoms.

[0157] The term polymeric CN as used herein refers to a class of polymeric materials composed primarily of carbon (C) and nitrogen (N) atoms arranged in a covalently bonded network.

[0158] The polymeric CN may form various structures.

[0159] In some examples, the polymeric CN is characterized by a stoichiometric ratio CxNybetween x / y = 0.5 to 2 with a varying amount of O and H elements (that is CxHyOρHq).

[0160] In some examples, the polymeric CN is characterized by having one or more of a melon structure, a graphitic structure, a C3N4structure, a potassium poly(heptazine imide) (PHI) structure, triazine-based CN (TGCN) structure, polytriazine imide (PTI) structure, heptazine-based CN (HPCN) melem oligomers, C3N5 structure, an amorphous structure, a porous structure, a heteroatom-doped (one or more of O, S, B, S, P, Cl, Br, I) structure, a metal-doped (one or more of Ti, Ni, Co, Mn, Cu, Bi, Sb, Sn, Fe, Zn, V, W, Mo, As, In, Ce, Y, Eu, La, Cr, Zr, Al, alkaline and alkaline-earth elements) structure, or any combination thereof.

[0161] In some examples, the polymeric CN is CN incorporated with salts.

[0162] In some examples, the polymeric CN comprises triazine rings (C3N3), heptazine units (C6N7) or any combination thereof. In some examples, the polymeric CN is triazine-based polymeric CN (TGCN). It should be noted that TGCN is characterized by being highly crystalline.

[0163] In some other examples, the polymeric CN is heptazine-based polymeric CN (HPCN).

[0164] In some examples, the polymeric CN is characterized by a melon structure. The term melon structure refers to a structure consisting of repeating units of nitrogen-rich heterocyclic rings (i.e. heptazine units) linked by nitrogen atoms.

[0165] In some examples, the polymeric CN is characterized by having a graphitic CN (g-C3N4) structure. The term g-CsN4 structure refers to a structure having layered material where carbon and nitrogen atoms form planar sheets similar to graphite, which are composed of heptazine or triazine units that are stacked through weak van der Waals interactions, leading to a graphitic-like structure.

[0166] In some examples, the polymeric CN is characterized by having an amorphous structure. The term amorphous structure refers to a structure consisting of randomly distributed carbon and nitrogen atoms, forming a disordered network. In other words, amorphous structure lacks long-range order found in crystalline forms.

[0167] In some examples, the polymeric CN is characterized by having a porous structure. The term porous structure refers to a structure having pores (at times introduced during the synthesis process) which may be mesoporous (2-50 nm) or microporous (<2 nm) size range. It should be notes that the porous structure may increase the specific surface area.

[0168] In some examples, the catalytic material is a modified CN.

[0169] In some examples, the modified CN is doped CN.

[0170] The term doped CN refers to CN in which heteroatoms or metal atoms are introduced into the polymeric CN framework.

[0171] In some examples, the modified CN is doped with one or more heteroatoms. In some examples, the heteroatom is one or more of sulfur (S), phosphorus (P), boron (B), oxygen (O), or halides (Cl, Br, I). In some examples, the modified CN is doped with one or more metals. In some examples, the metal is Ti, Ni, Co, Mn, Cu, Bi, Sb, Sn, Fe, Zn, V, W, Mo, As, In, Ce, Y, Eu, La, Cr, Zr, Al, alkaline and alkaline-earth elements. In some examples, the modified CN is a CN with one or more of the following functional groups: NO2, NH2, CN, COOH, OCH3, CO, CONH2, C6H6.

[0172] In some examples, the carbon-based material is one or more of graphene, graphene oxide, reduced graphene oxide, graphite.

[0173] In some examples, the carbon-based material is one or more of carbon or inorganic nanotubes.

[0174] In some examples, the carbon-based material is a carbon dot.

[0175] In some examples, the carbon-based material is a nitrogen-doped carbon.

[0176] In some examples, the catalytic material is a metal and / or metal-containing material.

[0177] In some examples, the metal and / or metal-containing material is one or more of a metal halide perovskite, an oxide perovskite, a metal sulfide, a metal nitride, a metal oxynitride, a metal selenide, a metal telluride, a metal phosphide, a metal boride, metal hydroxide, metal dichalcogenide, a pure metal, a partially oxidized metal or a metal alloy, an inorganic metal oxide, a double metal hydroxide, a metal oxyhydroxide, or any combination thereof.

[0178] In some examples, the catalytic material is an inorganic metal oxide, metal sulfide, metal selenide, metal telluride, metal nitride, metal boride, metal phosphide, metal hydroxide, metal oxyhydroxide, metal double hydroxide, metal dichalcogenide, metal oxynitride, or a combination thereof with multiple metallic elements or multiple non- metallic elements in a single material.

[0179] In some examples, the metal-containing material is a metal halide perovskite.

[0180] In some examples, the metal-containing material is an oxide perovskite.

[0181] In some examples, the metal-containing material is a metal sulfide. In some examples, the metal sulfide is MoSx, CdS, ZnS, SnxS. PbS, EuS, NiS, CuxS, InS3, Bi2S3, Sb2S3, CoxSy. FexSy. AgS, WSx. VSx. TaSx. WSx. TiSx, ZrSx, TaSxor a combination thereof.

[0182] In some examples, the metal-containing material is a metal nitride. In some examples, the metal nitride is TiN, MoxN, VN, WXN, NbN, GaN, CrN. In some examples, the metal-containing material is a metal oxynitride. In some examples, the metal oxynitride is TaOχNγ, LaTaON2, SrΧNbyOρNqCaTayOρNq, TiΧOγN-

[0183] In some examples, the metal-containing material is a metal selenide.

[0184] In some examples, the metal-containing material is a metal telluride.

[0185] In some examples, the metal-containing material is a metal phosphide.

[0186] In some examples, the metal-containing material is a metal boride.

[0187] In some examples, the metal-containing material is a metal carbide.

[0188] In some examples, the metal-containing material is a pure metal. In some examples, the metal is one or more of Au, Pt, Ni, Co, Mn, Mo, Zn, Sn, In, Bi, Pd, Cu, Ru, Rh or any combination thereof.

[0189] In some examples, the metal-containing material is a partially oxidized metal or a metal alloy. In some examples, the partially oxidized metal or a metal alloy is one or more of M, MO, MOOH, M1xM2yOρ,Hq, where M1 and M2 are two different metal elements.

[0190] In some examples, the metal-containing material is a metal oxide.

[0191] In some examples, the metal-containing material is a metal hydroxide.

[0192] In some examples, the metal-containing material is a metal oxyhydroxide.

[0193] In some examples, the metal oxide is at least one of bismuth oxide (Bi2O3), zinc oxide (ZnO), tungsten trioxide (WO3), titanium dioxide (TiO2), cadmium oxide (CdO), cadmium zinc oxide (CdZnO), bismuth vanadate (BiVO4), coper bismuth vanadate (CuBiVO4), barium titanate (BaTiOy). cerium oxide (CeO2), iridium oxide (IrO2), ruthenium oxide (RUO2), iron oxides (FexOy), zinc iron oxides (ZnFe2O4-x), tantalum oxide (TaOx), tantalum oxynitride (TaOxNy), indium oxide (ImO3), tin oxide (SnO2), fluorine-doped tin oxide (FTO), aluminum-doped zinc oxide (AZO), tin-doped indium oxide (ITO) or any combinations thereof.

[0194] In some examples, the catalytic material is WO3. In some examples, the catalytic material is Bi2O3. In some examples, the catalytic material is ZnO. In some examples, the catalytic material is TiO2. In some examples, the catalytic material is a covalent organic framework material (COFs).

[0195] In some examples, the catalytic material is a metal-organic framework material (MOFs).

[0196] In some examples, the catalytic material is a poly oxometalate material (POMs).

[0197] In some examples, the catalytic material is a nanoparticle. In some examples, the nanoparticle is a light active nanoparticle.

[0198] In some examples, the catalytic material is one or more of polymeric CN, a modified CN, CN incorporated with a salt, a metal halide perovskite, an oxide perovskite, a metal sulfide, a metal nitride, a metal oxynitride, a metal selenide, a metal telluride, a metal phosphide, a metal boride, a metal oxynitride, a metal carbide, a SiC, a covalent organic framework, a metal organic framework, a polyoxometalate, a carbon or inorganic nanotube, a graphene, a carbon dot, a graphene oxide, a reduced graphene oxide, a graphite, a nitrogen-doped carbon, a light active nanoparticle, a pure metal, a partially oxidized metal or metal alloy, a metal oxide, a metal double hydroxide, a metal hydroxide, a metal oxyhydroxide, or any combination thereof.

[0199] In some examples, the catalytic material may comprise one or more catalytic materials in a single material. In some examples, the single material may be an alloy and / or a multielement semiconductor.

[0200] In some examples, the catalytic material may comprise one or more catalytic materials in a hybrid nanostructure. In some examples, the hybrid nanostructure comprises two domains with partial or full contact. In some examples, the hybrid nanostructure has a core-shell, Janus, decorated, yolk-shell, match-stick or any combination thereof.

[0201] As described herein the panel comprises a substrate material.

[0202] The substrate material as used herein refers to a surface on which a catalytic material is deposited (attached / associated), embedded, or supported.

[0203] The substrate may provide mechanical support, ensuring the catalytic material maintains its structure and stability during reactions and in addition, it may have an active role in facilitating the catalytic process by influencing heat distribution, electronic or ionic conductivity, adsorption of reactants or intermediates, stabilization of molecules, or surface interactions.

[0204] The present disclosure is not limited to a specific substrate material. The substrate material in accordance with some examples, serves as a layer that supports the catalytic activity and which may also contribute to the overall performance and durability of the catalytic panel.

[0205] The substrates material may be made from various materials, depending on the specific application and the operating conditions, such as temperature, pressure, or chemical environment.

[0206] In some examples, the substrate material is or comprises at least one of glass, metal, metal oxide, doped-metal oxide ceramics, a polymer or any combination thereof.

[0207] In some examples, the substrate material is or comprises a glass material.

[0208] In some examples, the substrate material is or comprises a doped glass material.

[0209] In some examples, the substrate material is a conductive substrate.

[0210] In some examples, the substrate is fluorine-doped tin oxide coated glass substrate (FTO).

[0211] In some examples, the substrate material is or comprises a metal material.

[0212] In some examples, the substrate material is or comprises a metal-oxide over a metal material.

[0213] In some examples, the metal material is or comprises one or more of aluminum, zinc, copper, nickel, cobalt, silver, chromium, zirconium, iron cobalt nickel alloy, titanium, molybdenum, copper molybdenum alloy, copper tungsten, tungsten, gold, platinum, iridium, aluminum, or stainless steel.

[0214] In some examples, the substrate material is or comprises a ceramic material. In some examples, the ceramic material comprises silicon carbide, tantalum oxynitride, tungsten carbide, alumina, silicon nitride, zirconia, sapphire, aluminium oxide, aluminium nitride, aluminium titanate, ferrite, yttria, mullite, forsterite, porcelain, cordierite., silica, alumosilicate, nickel boride, magnesia or a combination thereof.

[0215] In some examples, the substrate material is or comprises a polymer. In some examples, the polymer is or comprises a thermoplastic polymer.

[0216] A thermoplastic polymer, as used herein, refers to a class of materials, some of them are polymers, that become soft and malleable when heated to a certain temperature and harden upon cooling.

[0217] In some examples, the thermoplastic polymer is or comprises at least one of polyethylene (PE), polypropylene (PP), Polystyrene (PS), Polyvinyl Chloride (PVC), Polyethylene Terephthalate (PET), Polyethylene Terephthalate Glycol (PETG), Poly (methyl methacrylate) (PMMA), Acrylonitrile Butadiene Styrene (ABS), polyvinyl alcohol (PVA), poly lactic acid (PL A), polycarbonate (PC), poly ether ester ketone (PEEK), poly etherimide (ULTEM), poly ether sulfone (PES), thermoplastic elastomers (TPE), or any combination thereof.

[0218] In some examples, the thermoplastic polymer is or comprises PE.

[0219] In some examples, the thermoplastic polymer is or comprises high-density polyethylene (HDPE), medium-density polyethylene (MDPE), low-density polyethylene (LDPE) or a combination thereof.

[0220] In some examples, the thermoplastic polymer is or comprises HDPE.

[0221] Regardless of the catalytic material and the substrate, the association / deposition / attachment of at least one catalytic material on the substrate or within the substrate may be homogeneous, heterogeneous, layered, patterned, gradient, porous, or multiphase. It should be noted that the association may depend on the functional requirements of the catalytic panel.

[0222] In accordance with some aspects, the present disclosure provides a panel comprising a glass and a polymeric CN.

[0223] In some examples, the panel comprising glass and polymeric CN is characterized by comprising melon-type CN or a combination of melon-type and graphitic C3N4. As shown in Example 1A, the crystallinity of the polymeric CN material may be characterized by XRD peaks, including a peak at about 27.4° 27.

[0224] In accordance with some aspects, the present disclosure provides a panel comprising a metal and a polymeric CN. In accordance with some aspects, the present disclosure provides a panel comprising a metal and a modified polymeric CN. In accordance with some aspects, the present disclosure provides a panel comprising aluminum and a polymeric CN. In accordance with some aspects, the present disclosure provides a panel comprising aluminum and a modified polymeric CN.

[0225] In accordance with some aspects, the present disclosure provides a panel comprising a glass and a modified polymeric CN.

[0226] In accordance with some aspects, the present disclosure provides a panel comprising a glass and a metal oxide.

[0227] In some examples, the panel comprising glass and WO3.

[0228] In accordance with some aspects, the present disclosure provides a panel comprising at least one catalytic material and at least one polymer.

[0229] As discussed herein and shown in Example 8, in panels comprising a polymer material as a support (for example HDPE), the catalytic material (for example CN) is at least partially embedded within the polymer material.

[0230] As further shown in Example 8, the present disclosure may be applicable to a variety of catalytic materials.

[0231] In some examples, the panel comprises polymeric CN and at least one polymer.

[0232] In some examples, the panel comprises a metal oxide and at least one polymer.

[0233] In some examples, the panel comprises Bi2O3and at least one polymer.

[0234] In some examples, the panel comprises WO3and at least one polymer.

[0235] In some examples, the panel comprises TiO2and at least one polymer.

[0236] In some examples, the panel comprises ZnO and at least one polymer.

[0237] The polymer may be any polymer that in some examples is a thermoplastic polymer as described herein.

[0238] In some examples, the panel comprises polymeric CN and HDPE.

[0239] In some examples, the panel comprises a metal oxide and HDPE.

[0240] In some examples, the panel comprises Bi2O3and HDPE.

[0241] In some examples, the panel comprises WO3and HDPE. In some examples, the panel comprises T1O2and HDPE.

[0242] In some examples, the panel comprises ZnO and HDPE.

[0243] The catalytic panels described herein can be employed in a variety of photocatalytic, photo-electrocatalytic, and electrocatalytic reactions.

[0244] Hence, in accordance with some aspects, the panel is for use in photocatalytic reactions, photo-electrocatalytic reactions, or electrocatalytic reactions, wherein the panel comprising at least one catalytic material and at least one substrate, wherein the catalytic material is directly associated to the substrate

[0245] As shown in the Examples below, the panel was characterized by being stable during the catalytic reactions.

[0246] In accordance with some aspects, the panel is for use in at least one of (i) hydrogen peroxide (H2O2) production, (ii) oxidizing at least one organic compound, (iii) activating a C-H bond of an organic compound, (iv) water purification, (v) hydrogen H2(g) production, wherein the panel comprising at least one catalytic material and at least one substrate, wherein the catalytic material is directly associated to the substrate.

[0247] As shown in Example 3 and Example 9, the panel described herein was successfully used in hydrogen peroxide (H2O2) production.

[0248] As shown in Example 3, the panels were stable during H2O2generation as demonstrated by UV-vis and FTIR spectra as well as by the fact that the panels did not decompose at least during 2 h of operation suggesting the stability of the panels during operation and hydrogen peroxide production. As also shown in this example, hydrogen peroxide was produced in the presence of oxygen but not in the presence of argon.

[0249] As shown in Example 9, the panels showed long-term stability under operational conditions for continuous-three-week operation.

[0250] In accordance with some aspects, the present disclosure provides a panel for use in a method of production of hydrogen peroxide (H2O2), wherein the panel comprises at least one catalytic material and at least one substrate, and wherein the catalytic material is directly associated to the substrate.

[0251] The present disclosure is also directed to a method for hydrogen peroxide production. The method comprises exposing a panel to a light source, wherein the panel comprises at least one catalytic material and at least one substrate, and wherein the catalytic material is directly associated to the substrate, to thereby produce hydrogen peroxide.

[0252] The panel for use and the method in connection with hydrogen peroxide production may include at least one catalytic material and at least one substrate as described herein above. In other words, any combination of catalytic material and substate as described herein may be applicable.

[0253] In accordance with some examples in which the panel is for use in a method of hydrogen peroxide production, the at least one catalytic material may be polymeric CN.

[0254] In accordance with some examples, the polymeric CN is characterized by a melon structure.

[0255] In accordance with some examples in which the panel is for use in a method of hydrogen peroxide production, the at least one catalytic material may be modified polymeric CN.

[0256] In accordance with some examples in which the panel is for hydrogen peroxide production, the substrate may be glass.

[0257] In accordance with some examples in which the panel is for hydrogen peroxide production, at least one catalytic material may be polymeric CN, and the substrate may be glass.

[0258] In accordance with some examples in which the panel is for hydrogen peroxide production, at least one catalytic material may be modified polymeric CN, and the substrate may be glass.

[0259] In accordance with some examples in which the panel is for hydrogen peroxide production, at least one catalytic material may be CN, and the substrate may metal oxide or doped-metal oxide over glass.

[0260] In accordance with some examples in which the panel is for hydrogen peroxide production, the substrate may be at least one polymer.

[0261] In accordance with some examples in which the panel is for hydrogen peroxide production, at least one catalytic material may be CN (polymeric or modified), and the substrate may be at least one polymer. In accordance with some examples in which the panel is for hydrogen peroxide production, at least one catalytic material may be CN, and the substrate is HDPE.

[0262] In accordance with some aspects, the present disclosure provides a panel for use in a method of producing hydrogen peroxide, wherein the panel comprises at least one catalytic material and at least one substrate, wherein at least one substrate is at least one polymer and wherein the catalytic material is at least partially embedded within the polymer.

[0263] The present disclosure is also directed to a method for producing hydrogen peroxide. The method comprises exposing a panel to a light source, wherein the panel comprises at least one catalytic material and at least one substrate, wherein the at least one substrate is at least one polymer and wherein the catalytic material is at least partially embedded within the polymer, to thereby produce hydrogen peroxide

[0264] In accordance with some examples, the method of producing hydrogen peroxide comprises exposing the panel to a light source.

[0265] In some examples, the method of producing hydrogen peroxide comprises exposing the panel to a light source in the presence of oxygen.

[0266] In some examples, the method of producing hydrogen peroxide comprises contacting the panel with oxygen.

[0267] In some examples, the method of producing hydrogen peroxide comprises exposing the panel to a light source in the presence of water.

[0268] In some examples, the method of producing hydrogen peroxide comprises exposing the panel to a light source in the presence of at least one hydroxyl-group containing compound.

[0269] In some examples, the method of producing hydrogen peroxide comprises contacting the panel with oxygen, water and at least one hydroxyl-group containing compound.

[0270] In some examples, the method of producing hydrogen peroxide comprises exposing the panel to a light source and contacting the panel with oxygen, water and at least one hydroxyl-group containing compound. In some examples, the method of producing hydrogen peroxide comprises exposing the panel to a light source in the presence of oxygen, water and at least one hydroxyl-group containing compound.

[0271] A hydroxyl-group containing compound as used herein refers to a chemical substance that includes one or more hydroxyl groups (-OH) in its structure.

[0272] In some examples, the hydroxyl-group containing compound may be at least one of an alcohol, a phenol, a carbohydrate, a carboxylic acid or a combination thereof.

[0273] In some examples, the hydroxyl-group containing compound may be at least one of an alcohol, a phenol, a carboxylic acid or a combination thereof.

[0274] In some examples, the hydroxyl-group containing compound may be at least one of methanol, ethanol, glycerol, phenol, glucose or any combination thereof.

[0275] In some examples, the hydroxyl-group containing compound may be ethanol.

[0276] In some examples, the hydroxyl-group containing compound may be glucose.

[0277] Without being bound by theory, it was suggested that the mechanism by which panel described herein produces H2O2is as shown in Figure 24. Accordingly, it was suggested that in panel in which the catalytic material is polymeric CN, upon absorption of two photons by CN, holes are created that predominantly reside at N2 and N6 atoms, while the corresponding electrons are found on Cl and N4 atoms. The holes oxidize ethanol, which results in the hydrogenation of N2 and N6. Subsequently, an electron from Cl or N4 reduces molecular oxygen (O2) to form a superoxo radical. Immediately, this superoxo radical is further reduced by another electron to form a 1 ,4-endoperoxide species on the triazine ring of CN. Finally, the successive protonation of the formed 1 ,4- endoperoxide species yields H2O2to complete the catalytic cycle.

[0278] As shown in Example 4, the panel described herein was successfully used in oxidizing organic compounds such as biomass-derived products. Specifically, as shown in Example 4, the panel described herein was successfully used in oxidizing 5- hydroxymethyfurfural (HMF).

[0279] In accordance with some aspects, the present disclosure provides a panel for use in a method of oxidizing at least one organic compound, wherein the panel comprises at least one catalytic material and at least one substrate, and wherein the catalytic material is directly associated to the substrate.

[0280] The present disclosure is also directed to a method for oxidizing an organic compound. The method comprises exposing a panel to a light source, wherein the panel comprises at least one catalytic material and at least one substrate, and wherein the catalytic material is directly associated to the substrate, to thereby oxidizing at least one organic compound.

[0281] The panel for use and the method in connection with oxidizing an organic compound may include at least one catalytic material and at least one substrate as described herein above. In other words, any combination of catalytic material and substate as described herein may be applicable.

[0282] The present disclosure is not limited to a specific organic compound and is applicable for a variety of organic compounds. As appreciated, biorefineries or biomass are considered as candidates to replace ever-growing demand for crude oil and to substitute chemical molecules deriving from petroleum based refineries.

[0283] In accordance with some aspects, the present disclosure provides a panel for use in a method of oxidizing at least one biomass-derived product, wherein the panel comprises at least one catalytic material and at least one substrate, and wherein the catalytic material is directly associated to the substrate.

[0284] The present disclosure is also directed to a method for oxidizing biomass-derived product. The method comprises exposing a panel to a light source, wherein the panel comprises at least one catalytic material and at least one substrate, and wherein the catalytic material is directly associated to the substrate, to thereby oxidizing at least one biomass-derived product.

[0285] In some examples, the organic compound is a biomass-derived compound.

[0286] In some examples, the organic compound is a hydroxyl-containing compound.

[0287] Biomass consists predominantly biopolymers such as cellulose, hemi-cellulose, and lignocelluloses and these polymers can be depolymerized into Ce monosaccharides such as fructose, glucose and polysaccharides such as starch and cellulose. In some examples, the biomass-derived compound is derived from cellulose, hemi-cellulose, and lignocelluloses.

[0288] As appreciated, the ability of the panel described herein to oxidize organic compounds, including biomass-derived compounds is important for several key reasons, particularly in the fields of sustainable energy, chemical production, and environmental impact reduction.

[0289] In some examples, the biomass product compound is derived from cellulose.

[0290] In some examples, the biomass product compound is derived from at least one sugar.

[0291] In some examples, the biomass product compound is derived from glucose or fructose.

[0292] In some examples, the biomass product compound is 5 -hydroxymethylfurfur al (HMF).

[0293] In accordance with some examples in which the panel is for use in a method of oxidizing HMF, the at least one catalytic material may be polymeric CN. In accordance with some examples, the polymeric CN is characterized by a melon structure. In accordance with some examples in which the panel is for oxidizing HMF, the substrate may be glass. In accordance with some examples in which the panel is for hydrogen peroxide production, at least one catalytic material may be polymeric CN, and the substrate may be glass.

[0294] In some examples, HMF is oxidized to 2,5-Furandicarboxylic Acid (FDCA).

[0295] In some examples, HMF is oxidized to 5-Hydroxymethyl-2-furancarboxylic Acid (HMFA).

[0296] In accordance with some examples, the method of oxidizing HMF comprises exposing the panel to a light source.

[0297] In some examples, the method of oxidizing HMF comprises exposing the panel to a light source in the presence of oxygen.

[0298] In some examples, the method of oxidizing HMF comprises contacting the panel with oxygen. In some examples, the method of oxidizing HMF comprises contacting the panel with oxygen and water.

[0299] In some examples, the method of oxidizing HMF comprises exposing the panel to a light source and contacting the panel with oxygen and water.

[0300] In some examples, the method of oxidizing HMF comprises exposing the panel to a light source in the presence of oxygen and water.

[0301] Without being bound by theory, it was suggested that the mechanism by which panel described herein oxidizes HMF is as shown in Figure 33. Accordingly, it was suggested that in panel in which the catalytic material is polymeric CN, upon illumination, the electrons in the CN are excited to a singlet state and form singlet excitons, which quickly converts to triplet excitons by an intersystem crossing process. Then, triplet excitons react with O2to produce1O2- The1O2then oxidizes HMF to DFF along with H2O2generation. The generated H2O2further oxidizes the DFF to various aliphatic intermediates before complete mineralization.

[0302] In some examples, the catalytic panel is for use in activating a C-H bond of an organic compound. The term activating a C-H bond in an organic compound as used herein refers to a process in which a typically inert carbon-hydrogen (C-H) bond is transformed into a more reactive site, enabling subsequent chemical reactions. This activation allows the carbon atom to become reactive.

[0303] The present disclosure is not limited to a specific organic compound and is applicable toa variety of organic compounds (carbohydrates).

[0304] It should also be noted that the organic compound may not include a hydroxyl group.

[0305] In some examples, the organic compound is one or more of cyclohexane, toluene, xylene, CH4 or any combination thereof.

[0306] In some examples, the activation of a CH bond is as a result of bond oxidation.

[0307] In some examples, the CH bond is activated directly by photogenerated holes of the photocatalyst.

[0308] In some examples, the CH bond is activated by the generated H2O2in an ORR reaction. In some examples, the activation of a CH bond is as a result of bond oxidation. In some examples, the CH bond is activated (i) directly by photogenerated holes of the photocatalyst (ii) by the generated H2O2in the ORR reaction or (iii) a combination thereof.

[0309] As shown in Example 5, the panel described herein was successfully used in degrading water contaminants and hence is considered suitable for water purification.

[0310] In accordance with some aspects, the present disclosure provides a panel for use in a method of water purification, wherein the panel comprises at least one catalytic material and at least one substrate, and wherein the catalytic material is directly associated to the substrate.

[0311] The present disclosure is also directed to a method for water purification. The method comprises exposing a panel to a light source, wherein the panel comprises at least one catalytic material and at least one substrate, and wherein the catalytic material is directly associated to the substrate, to thereby allow water purification.

[0312] The panel for use and the method in connection with water purification may include at least one catalytic material and at least one substrate as described herein above. In other words, any combination of catalytic material and substate as described herein may be applicable.

[0313] The term water purification refers to reducing (degrading) water contamination.

[0314] In some examples, the panel is for use in a method of degrading water contamination.

[0315] The present disclosure is not limited to a specific contaminant and may be applicable to various contaminants.

[0316] In some examples, the water contaminant is an organic contaminant.

[0317] In some examples, the water contaminant is 9-(2-carboxyphenyl)-6- (diethylamino)-A,A-diethyl-3H-xanthen-3-iminium chloride, (rhodamine B, RhB).

[0318] In accordance with some examples in which the panel is for use in a method of water purification, the at least one catalytic material may be polymeric CN. In accordance with some examples, the polymeric CN is characterized by a melon structure.

[0319] In accordance with some examples in which the panel is for use in a method of water purification, the at least one catalytic material may be a modified CN.

[0320] In accordance with some examples in which the panel is for water purification, the substrate may be glass.

[0321] In accordance with some examples in which the panel is for water purification, the at least one catalytic material may be polymeric CN and the substrate may be glass.

[0322] In accordance with some examples, the method of water purification comprises exposing the panel to a light source.

[0323] In some examples, the method of water purification comprises exposing the panel to a light source in the presence of oxygen.

[0324] In some examples, the method of water purification comprises contacting the panel with oxygen.

[0325] In some examples, the method of water purification comprises contacting the panel with oxygen and water.

[0326] In some examples, the method of water purification comprises exposing the panel to a light source and contacting the panel with oxygen and water.

[0327] In some examples, the method of water purification comprises exposing the panel to a light source in the presence of oxygen and water.

[0328] As shown in Example 6 and Example 10 and Example 11, the panel described herein was successfully used in hydrogen H2(g) production.

[0329] As shown in Example 6 and Example 10, for H2(g) production from water, a cocatalyst such as pt was applied on the binder-free panels. In addition, as shown in Example 6, SEM image of the panel after the HER experiment, confirmed that the panel was stable.

[0330] In accordance with some aspects, the present disclosure provides a panel for use in a method of producing hydrogen (H2), (hydrogen evolution reaction (HER)) wherein the panel comprises at least one catalytic material and at least one substrate, and wherein the catalytic material is directly associated to the substrate.

[0331] The present disclosure is also directed to a method for producing hydrogen. The method comprises exposing a panel to a light source, wherein the panel comprises at least one catalytic material and at least one substrate, and wherein the catalytic material is directly associated to the substrate, to thereby produce hydrogen.

[0332] The panel for use and the method in connection with producing hydrogen may include at least one catalytic material and at least one substrate as described herein above. In other words, any combination of catalytic material and substate as described herein may be applicable.

[0333] In some examples, in which the catalytic panel is for use in a method of hydrogen evolution reaction (HER), i.e. hydrogen production, and the method comprises addition of a cocatalyst for the HER, the HER catalysis may be associated with the panel. In some examples, the cocatalyst may be deposited on the panel. In some examples, the cocatalyst may be deposited on the panel, wherein the panel is polymeric CN or a modified CN or a composite film containing the CN or the modified CN. In some examples, the cocatalyst is deposited on the catalytic material.

[0334] It should be noted that in such aspects and / or examples, the use or method are not limited to a specific HER cocatalyst. In some examples, the catalyst may be at least one metal, for example Pt, Au, Ni, Co, Cu, Ru, Ag, Pd, and their alloys, and combinations on the nanoscale as core-shell and decoration, phase- segregated particles, and their oxides.

[0335] In accordance with some examples in which the panel is for use in a method of producing hydrogen, the at least one catalytic material may be polymeric CN.

[0336] In accordance with some examples, the polymeric CN is characterized by a melon structure.

[0337] In accordance with some examples in which the panel is for use in a method of producing hydrogen, the at least one catalytic material may be modified CN.

[0338] In accordance with some examples in which the panel is for producing hydrogen, the substrate may be glass. In accordance with some examples in which the panel is for hydrogen production, the at least one catalytic material may be polymeric CN and the substrate may be glass.

[0339] In accordance with some examples in which the panel is for hydrogen production, the substrate may be at least one polymer.

[0340] In accordance with some examples in which the panel is for hydrogen production, the at least one catalytic material may be CN and the substrate may be at least one polymer. In accordance with some examples in which the panel is for hydrogen production, the at least one catalytic material may be polymeric CN and the substrate is thermoplastic polymer.

[0341] In accordance with some aspects, the present disclosure provides a panel for use in a method of producing hydrogen (H2), wherein the panel comprises at least one catalytic material and at least one substrate, wherein the at least one substrate is at least one polymer and wherein the catalytic material is at least partially embedded within the polymer.

[0342] The present disclosure is also directed to a method for producing hydrogen. The method comprises exposing a panel to a light source, wherein the panel comprises at least one catalytic material and at least one substrate, wherein the at least one substrate is at least one polymer and wherein the catalytic material is at least partially embedded within the polymer, to thereby produce hydrogen.

[0343] In accordance with some examples, the method of producing hydrogen comprises exposing the panel to a light source.

[0344] As shown in Example 12, panels were used for electrochemical (EC) and photoelectrochemical (PEC). Specifically, as shown in Example 12, panels in which the substrate was a transparent conductive oxide, such as, fluorine-doped tin oxide coated glass substrate (FTO) were used for electrochemical (EC) and photoelectrochemical (PEC) methanol oxidation to formaldehyde. In this example, the panel served as an electrode for MeOH electrochemical oxidation to HCHO.

[0345] In accordance with some aspects, the present disclosure provides a panel for use as an electrode, wherein the panel comprises at least one catalytic material and at least one substrate, wherein the substrate is a conductive substrate and wherein the catalytic material is directly associated to the substrate. In some examples, the conductive substrate is at least one of fluorine-doped tin oxide coated glass substrate (FTO), transparent conductive oxide (TCO), Indium Tin Oxide (ITO), Aluminum-doped Zinc Oxide (AZD), Gallium-doped Zinc Oxide (GZO), Antimony-doped Tin Oxide (ATO), Antimony-doped Indium Oxide (AIO) or any combination thereof.

[0346] An exemplary set up is shown in Figure 70A in which the panel serves as an anode.

[0347] As shown in Example 12, the electrode was used for methanol (MeOH) electrochemical oxidation to formaldehyde (HCHO).

[0348] As described herein in Example 7, the present disclosure relates to a novel oxygen reduction reaction (ORR)-active photocatalyst, that is even hydrogen evolution reaction (HER)-inactive. Specifically, as shown herein, a powder was shown to produce hydrogen peroxide (H2O2) coupled with the selective oxidation of a hydroxyl-containing compound (e.g., methanol (MeOH). The powder allowed spontaneous reaction of H2O2with HCHO to produce hydrogen (H2) and formic acid (HCOOH), eliminating the need for separation units, thereby improving sustainability and industrial scalability. The powder is suitable in allowing these reactions independently of the specific catalyst used, whether it is CN or WO3, demonstrating broad applicability across different catalytic systems.

[0349] In accordance with some aspects, it is provided a composite material for use in a method of producing hydrogen, the composite material comprising at least one catalytic material.

[0350] In accordance with some aspects, it is provided a particulate matter for use in a method of producing hydrogen, the particulate matter comprising at least one catalytic material.

[0351] In some examples, the particulate matter is in the form of particles, pellets, granules, powder or any other form of solid discrete elements. In some examples, the particulate matter is in the form of a powder.

[0352] These solid elements may be homogenous or non-homogenous is shape and dimension. In some embodiments, the elements are in the size range of microns to few millimeters. In accordance with some aspects, it is provided a powder comprising at least one catalytic material for use in a method of producing hydrogen.

[0353] In accordance with some aspects, it is provided a powder comprising at least one catalytic material for use in a method of reducing oxygen to hydrogen peroxide. In some aspects, it is provided a powder comprising at least one catalytic material for use in a method of oxidizing a compound containing a hydroxy group to an aldehyde or a carboxylic acid.

[0354] In some examples, the catalytic material is characterized by having a Valence Band Maximum (VBM) and the Conduction Band Minimum (CBM) that allows the oxidization of a compound containing a hydroxy group to the respective aldehyde or carboxylic acid and in parallel the reduction of oxygen to hydrogen peroxide.

[0355] In some examples, the catalytic material is characterized by having a VBM that is sufficiently positive to allow oxidization of a compound containing a hydroxy group to the respective aldehyde or carboxylic acid and a CBM is sufficiently negative to allow reduction of oxygen to hydrogen peroxide or facilitate hydrogen evolution from water by reduction of protons or water.

[0356] In some examples, the catalytic material is WO3. In some examples, the catalytic material is polymeric CN. In some examples, the catalytic material is a modified CN.

[0357] In some examples, the catalytic material is not configured to reduce hydrogen from water that is the hydrogen evolution reaction.

[0358] It should be noted that the present disclosure encompasses uses of the powder as is and also encompasses uses of the powder in panels described herein.

[0359] As described in Example 2 below, the panel described herein may be incorporated into a photoreactor.

[0360] Hence, the present disclosure provides in accordance with some aspects, a photoreactor comprises at least one panel as described herein.

[0361] In accordance with some aspects, it is provided a photoreactor comprises a particulate matter as described herein.

[0362] It should be noted that in cases in which the photoreactor comprises two or more panels, the two or more panels may be the same or may be different. The present disclosure is applicable for various types of photoreactor.

[0363] In some examples, the photoreactor is a continuous flow photoreactor.

[0364] In some examples, the photoreactor is a batch photoreactor.

[0365] These reactors may be used for scalable applications of the catalytic panels described herein, for example, in energy production, pollutant degradation, and chemical synthesis.

[0366] The present disclosure is also directed to processes of preparation of the panels described herein.

[0367] Figure 1A, Figure IB and Figure 56 show schematic representations of exemplary processes for the preparation of the panels described herein.

[0368] The process schematically represented in Figure 1A is denoted as “sandwich process” and the process schematically represented in Figure IB is denoted as “blade assisted sandwich process”. As described herein, in cases in which the substrate is a polymer material, the process may be schematically represented in Figure 56.

[0369] The present disclosure provides in accordance with some aspects, a process for preparing a panel. The process comprising applying conditions for polymerizing a CN precursor over a substrate.

[0370] In some examples, the process comprising prior to polymerizing, applying the CN precursor in a paste form or powder form onto a substrate.

[0371] In some examples, applying the CN precursor comprises spreading the CN precursor homogenously onto the substrate.

[0372] In some examples, applying the CN precursor comprises spreading the CN precursor as paste onto the substrate.

[0373] In some examples, applying the CN precursor comprises spreading the CN precursor as powder onto the substrate.

[0374] In some examples, spreading the CN precursor comprises (i) spreading the CN precursor as paste onto the substrate and (ii) spreading the CN precursor as powder onto the substrate. In some examples, the process comprising prior to polymerizing and after applying the CN precursor in a paste form or powder form onto the substrate, applying a second substrate onto the CN precursor, to thereby form a sandwich structure.

[0375] In some examples, the CN precursor comprises one or more of melamine, cyanuric acid, or cyanuric acid and melamine complex: MCA.

[0376] In some examples, applying conditions for polymerizing the CN precursor comprises heating the CN precursor to allow polymerization. In some examples, heating the CN precursor is at a temperature of at least 150 °C and a maximum of 700 °C.

[0377] In some examples, polymerizing the CN precursor provides polymeric CN.

[0378] In some examples, the substrate is glass.

[0379] The present disclosure provides in accordance with some aspects, a process for preparing a panel. The process comprising applying conditions for integrating a catalytic material in a substrate, wherein the substrate is in a molten state.

[0380] The molten state of the substrate as used herein refers to the condition in which the substrate material has been preheated to a temperature sufficient to melt it into a liquid form.

[0381] It should be noted that in this state, the substrate is able to flow and allow for the catalytic material to be integrated or embedded. Upon cooling, the substrate solidifies, securing the catalytic material within its structure.

[0382] In some examples, the substrate is a polymer.

[0383] In some examples, the substrate is a thermoplastic polymer.

[0384] In some examples, the substrate is HDPE.

[0385] In some examples, the catalytic material is polymeric CN, modified CN or a metal oxide.

[0386] In some examples, the metal oxide is at least one of Bi2O3, ZnO, WO3, TiO2, or any combination thereof.

[0387] The term "about" as used herein indicates values that may deviate up to 1%, more specifically 5%, more specifically 10%, more specifically 15%, and in some cases up to 20% higher or lower than the value referred to, the deviation range including integer values, and, if applicable, non-integer values as well, constituting a continuous range. As used herein the term "about" refers to ± 10 %.

[0388] It should be noted that various embodiments of this invention may be presented in a range format. The description of a range should be considered to have specifically disclosed all the possible sub ranges as well as individual numerical values within that range inclusive the end points values. For example, description of a range such as from 1 to 6 or between 1 and 6 should be considered to have specifically disclosed sub ranges such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6 etc., as well as individual numbers within that range, for example, 1, 2, 3, 4, 5, and 6.

[0389] It should be noted that the term “at least one” refers to one or more of the following and encompasses any one of 1, 2, 3, or more of the specified information.

[0390] It is to be understood that the terminology used herein is used for the purpose of describing particular embodiments only and not intended to be limiting since the scope of the present invention will be limited only by the appended claims and equivalents thereof.

[0391] Throughout this specification and the Examples and claims which follow, unless the context requires otherwise, the word “comprise”, and variations such as “comprises” and “comprising”, will be understood to imply the inclusion of a stated integer or step or group of integers or steps but not the exclusion of any other integer or step or group of integers or steps.

[0392] It must be noted that, as used in this specification and the appended claims, the singular forms “a”, “an” and “the” include plural referents unless the content clearly dictates otherwise.

[0393] The following examples are representative of techniques employed by the inventors in carrying out aspects of the present invention. It should be appreciated that while these techniques are exemplary of preferred embodiments for the practice of the invention, those of skill in the art, in light of the present disclosure, will recognize that numerous modifications can be made without departing from the spirit and intended scope of the invention.

[0394] It should be noted that the various embodiments and examples detailed herein in connection with various aspects of the invention may be applicable to one or more aspects disclosed herein. It should be further noted that any embodiment described herein, for example, related to the panel, may be applied separately or in various combinations. Various embodiments and aspects of the present invention as delineated hereinabove and as claimed in the claims section below find experimental support in the following examples. Various embodiments and examples of the invention can be combined (from the same or from different aspects) without departing from the scope of the invention.

[0395] SOME NON-LIMITING EXAMPLES

[0396] Methods:

[0397] 1. Characterization methods. a. Powder X-ray diffraction (XRD). Powder X-ray diffraction patterns (XRD) of CN and WO3recorded using a PANalytical's Empyrean diffractometer, which is equipped with a position-sensitive detector X’Celerator (scan time of ~15 min, 10 ranging from 5° to 70° using Cu Ka radiation, λ = 1.54178 A, 40 kV, 30 mA). b. X-ray photoelectron spectroscopy (XPS). X-ray photoelectron spectroscopy (XPS) data was recorded using an X-ray photoelectron spectrometer ESCALAB-Xi+ ultrahigh vacuum (4xlO-10bar) apparatus with an Al Ka X-ray source and a monochromator. The X-ray beam size was 500 μm and the survey spectra were recorded with a pass energy of 150 eV. The individual high-resolution spectra were recorded with a pass energy of 20 eV. All spectra were calibrated relative to a carbon C Is peak positioned at 284.8 eV to correct the charging effects. c. High-resolution scanning electron microscopy (HRSEM). The surface morphology of the CN and WO3was analyzed by scanning electron microscopy (SEM) using a FEI Verios 460L high-resolution FEG-source microscope using a through-lens detector (TLD) operated at Uo = 3.5 kV and I = 25 pA. The samples were sputtered with < 12 nm AuPd using a Quorum Q150T ES system to avoid charging effects during imaging. d. Energy dispersive X-ray spectroscopy (EDS). Energy dispersive X-ray spectroscopy (EDS) measurements were performed on the same FEI Verios SEM, equipped with an Oxford instruments Xmax 80 mm2EDS detector (127 eV Si drift detector) on samples without sputtering at Uo = 30 kV. e. Fourier- transform infrared (ATR-FTIR) spectroscopy. Fourier- trans form infrared spectroscopy (FTIR) was performed to analyze the functional groups of CN and WO3using a Thermo Scientific Nicolet iS5 FTIR spectrometer (KBr window; diamond iD7 attenuated total reflectance (ATR) optical base; each measurement has 16 scans with 4 cm-1resolution in the 400-4000 cm-1range). f. UV-vis spectroscopy and photoluminescence. UV-vis absorption spectroscopy in reflectance (R) mode — using a diffuse reflectance accessory (DRA) — was recorded on a Cary 100 spectrophotometer. Tauc plot analysis was conducted (using a Kubelka-Munk analysis of the reflectance spectra) to estimate the optical band gap, assuming a direct band gap for CN and WO3. UV-vis in transmittance mode complemented film analysis over transparent substrates to calculate the absorbance. Absorbance (optical density) in quartz cuvettes with 1.0 cm optical path was used to measure the concentration of various chemical species in solutions. Photoluminescence (PL, Horiba Scientific FluoroMax 4 spectrofluorometer) and UV-vis absorption spectroscopies were employed to study the optical properties of CN panels. g. White LED measurements. The spectrum of the 100 W white LED illumination source (Bridgelux BXRA-50C5300; in the visible range) was recorded using StellarNet Black-Comet-C-SR-50 spectrometer measuring the irradiance through an F600-UVVIS- SR 600 μm single-strand fiber-optic cable ending with a CR2 cosine receptor and a 2.7% aperture; all calibrated for irradiance using a NIST traceable lamp (StellarNet Inc., USA). The incident energy flux of the white LED illumination source was calculated by integrating the obtained irradiance spectra from 280 to 1000 nm to be -2680 W m-2. h. Calculation of valence band energies. The valence band energies (EVB) of the CN panels were calculated by subtracting the width of Hel-UPS spectra from the excitation energy (Eex= 21.21 eV). The conduction band energy (ECB) is therefore calculated from EVB - Eg (where Egis optical bandgap energy, calculated using the Tauc plot analysis assuming a direct Eg). The obtained EVB and ECB values were converted to electrochemical energy potential using standard reference scale (normal hydrogen electrode (NHE) at pH = 0), where 0 V vs. NHE = 4.44 eV vs. EVac- i. High Performance Liquid Chromatography (HPLC). The liquid products of HMF oxidation were analyzed using an HPLC instrument (Agilent 1260) coupled to a diode array detector (DAD) and equipped with a C-18 column. 50:50% v / v of DI water:MeCN solution was used as the mobile phase. The liquid products of MeOH oxidation were analyzed using an HPLC instrument (Agilent 1260) coupled to a diode array detector (DAD) and equipped with a Hiplex-H column. A 0.05 M H2SO4solution was used as the mobile phase. j. Gas Chromatography (GC). The generated H2(g) from the headspace of the reactor was collected using a gas-tight syringe and analyzed by gas chromatography (Agilent 7820 GC system).

[0398] Materials

[0399] All chemicals were obtained from the indicated commercial vendors and used as received without further purification.

[0400] Melamine (M, 99%), cyanuric acid (CA, 99%), 5 -hydroxymethylfurfural (HMF, 99%), 9-(2-carboxyphenyl)-6-(diethylamino)-A,A-diethyl-3H-xanthen-3-iminium chloride, abbreviated as Rhodamine B (RhB, >95%), 8% wt. chloroplatinic acid (H2PtCl6) solution, dicyandiamide (DCDA, 99%), barbituric acid (B, 99%), and sodium azide (NaN3, >99.5%) were purchased from Sigma-Aldrich. Ethylene glycol (EG, >99.5%) was purchased from Merck. Ethanol (EtOH, 99.9%, absolute) and acetone (AR grade) were purchased from Bio-Lab, Israel. Hydrogen peroxide (H2O2, 30% wt.) was purchased from JT Baker. Potassium iodide (KI, >99%) and acetonitrile (MeCN, HPLC grade 99.99%) were purchased from Fisher Chemicals. Potassium hydrogen phthalate (HPLC grade) and salicylic acid (SA, 99%) were purchased from Thermo Scientific. 2,5-Diformylfuran (DFF, 98%), 1,5-dihydroxynaphthalene (DHN, 98%), and ammonium paratungstate (99%) were purchased from Angene Chemical, UK. 2,5-Furandicarboxylic acid (FDCA, 99%) was purchased from Combi-Blocks, USA. High purity oxygen (99.99%) and argon (99.999%) gases were purchased from Maxima Ltd., Israel. 1 ,4-benzoquinone (p-BQ, >98%) was purchased from TCI.

[0401] Deionized (DI) water for all aqueous solution preparations was collected after treatment through a Millipore Direct-Q 3 water purification system (resistivity of 18 MQ cm at room temperature). Fluorine-doped tin oxide (FTO)-coated glass (12-14 Ω sq-1) was purchased from Xop Glass company, Spain. The glass substrates were cleaned by subsequent sonications of 15 min in DI water, ethanol, and acetone.

[0402] Example 1: Preparation and characterization of panels comprising catalytic materials

[0403] Example 1A: Preparation and characterization of binder-free polymeric carbon nitride (CN) photocatalytic panels.

[0404] Materials and methods

[0405] Synthesis of supramolecular assemblies as CN precursors

[0406] Finely- ground melamine (M) and cyanuric acid (CA) (1:1 mol ratio) were dissolved in 25 mL of DI water and shaken in a tube for 24 h using an automatic shaker at 300 rpm. The formed supramolecular precursor (MCA) was centrifuged at 6000 rpm (4430 ref) for 10 min, washed with DI water three times, and finally vacuum-dried at 50 °C overnight. MCA(1:1.5) is the product of the same procedure with a 50% molar excess of CA (1:1.5 M:CA molar ratio).

[0407] The same procedure was followed for Mel-CA (1:1 mol ratio of melem (Mel) and CA) and MCAB(0.05) (1:1:0.05 mol ratio of M, CA, and barbituric acid (B)) supramolecular aggregates. The MCAB(O.l) supramolecular aggregate was prepared in EtOH as the solvent.

[0408] The melem powder (Mel) was prepared by placing 10 g of melamine in a ceramic crucible covered with a lid and calcined at 400 °C in air for 12 h.

[0409] Synthesis of binder-free CN panels

[0410] Binder-free CN panels were prepared by forming a glass / precursor / glass sandwich, where the CN precursor was either melamine (M) or melamine :cyanuric acid supramolecular aggregates in a 1:1 or 1:1.5 molar ratio (MCA and MCA(1:1.5), respectively. Briefly, 2 g of precursor powder was sandwiched between two 6.7 x 6.7 cm2clean glass substrates. The glass / precursor / glass sandwich was placed in a rectangular ceramic crucible covered with a lid. Subsequently, the crucible was placed in a tube furnace at 530 °C for 4 h under a constant N2 flow, which resulted in the formation of melon-type CN thin films on the glass substrate. After removing the crucibles from the over, the two glass substrates are easily detached without application of force (with the exception of M panels, where gentle tapping is used to detach the two glass substrates). The weakly bound CN was removed either by compressed-air treatment (MCA precursors) or by sonication in water for 30 min (M precursor). The CN panels had a well- attached photocatalyst layer (both glass substrates) and were labeled as CNx, where X = M, MCA, or MCA(1:1.5). CN panels with a thicker photocatalyst coating were prepared by adapting the doctor-blade approach. Finely ground MCA powder (1 g) was dispersed in ethylene glycol (1.2 mL) and further ground using a mortar and pestle to form a paste. This MCA paste was doctor-bladed with a thickness of 2 scotch tapes on two glass sheets and dried at 85 °C for 20 min. Subsequently, these two precursor-coated glass sheets were used to sandwich 1 g of MCA powder and the whole assembly was calcined under conditions identical to those used for the CNMCApreparation. The obtained CN panel was denoted as CNMCA-D. For comparison, CNMCA-D1 and CNMCA-D3, were synthesized, where 1 and 3 represent glass sheets with doctor-bladed MCA paste with a thickness of 1 and 3 scotch tapes respectively (note: according to this naming scheme, CNMCAis actually CNMCA-D2, since it uses a thickness of 2 scotch layers during doctor-blading, but for ease of reading it is referred to simply as CNMCA).

[0411] Synthesis of other binder-free CN panels: 2.0 g of dicyandiamide (D), Mel-CA, MCAB(0.05), or MCAB(O.l) powder precursors were sandwiched between two 6.7 x 6.7 cm2clean glass substrates followed by a calcination in a tube-furnace at 530 °C for 4 h under constant N2 flow to yield CND, CNMe1-CA, CNMCAB(0.05), or CNMCAB(O.1)panels, respectively. The CNMCAB(0.05)-500and CNMCAB(0.1)-500panels were synthesized at 500°C for 4 h under a constant N2 flow. The precursor, MCA supramolecular aggregate or M, was sandwiched between two 6.7 x 6.7 cm2Al foils, followed by calcination at 530°C for 4 h under constant N2 flow to yield CNMCA-Aifoii and CNM-Aifoii panels, respectively.

[0412] Results

[0413] The synthesis of binder-free melon-type CN panels, depicted in Figure 1A, relies on the in situ thermal polymerization of precursors over a glass substrate. To achieve this, melamine (M) and cyanuric acid (CA) (1:1 mol ratio) MCA supramolecular aggregates are sandwiched between two glass substrates and then calcined to yield CNMCA. TO show the generality of this method to other precursors, pristine melamine was used as the precursor or MCA (1:1.5) supramolecular aggregates, in which the melamine-to-cyanuric acid ratio is non-stoichiometric; the resulting CN films over glass are denoted as CNM and CNMCA(1:1.5) panels, respectively.

[0414] A unique feature of the reported method is that it uses only about 23 mg precursor per square centimeter of the resulting CN panel, which is significantly less than the reported state-of-the-art CN thin films (Table 1).

[0415] Table 1 Summary of known synthetic procedures of various polymeric CN thin films on glass substrates.

[0416] * graphitic

[0417] The scalability of this method is demonstrated here by preparing a 10 x 10 cm2CNMCApanel (Figure 2); in general, the panel size can be further increases, provided that a furnace of suitable dimensions is available.

[0418] The growth of various CN films was shown using different combinations of precursors on glass and aluminum foil, further establishing the generality of the method (Figures 3A-3G). Figure 3A-3E show CN films on glass substrate: CND, D refers to dicyanamide precursor; calcined at 530 °C, Figure 3B -CNMe1-CAcalcined at 530 °C, Mel refers to melem, thus Mel-CA is the supramolecular aggregate formed between melem and cyanuric acid, and carbon-rich polymeric carbon nitride synthesized from a supramolecular assembly of melamine, cyanuric acid, and barbituric acid (B): Figure 3C CNMCAB(0.05)calcined at 530 °C, Figure 3D CNMCAB(0.05)-500(calcined at 500 °C), and Figure 3E CNMCAB(0.1) (calcined at 530 °C). The method was also shown on Aluminum foil as a substrate in Figures 3F-3G. Figure 3F CNMCA, and Figure 3G CNM.

[0419] FTIR spectra (Figure 4A) confirms formation of polymeric carbon nitride since it exhibits vibrations related to breathing modes of heptazine and triazine (804 cm-1) , in- plane stretching and bending vibrations of C-N heterocycles (1200-1650 cm-1), and stretching modes of -NH, groups about 3200-3500 cm-1. Furthermore, a cyano group vibration about 2180 cm-1demonstrates that CNMCAB has surface cyano groups similar to CNMCA(without barbituric acid in the precursor paste).

[0420] Figure 4B is FTIR analysis of CNM and CNMCAon Al foil.

[0421] These results show that changing the substrate does not significantly alter the functional groups of the polymeric carbon nitride.

[0422] The wide band in CNM around 2500-3400 cm-1stems from hydrogen bonds (e.g., -OH groups) on the surface of the Al foil with its native oxide; they are stronger in CNM since the CN film is thinner. Moreover, the incorporation of barbituric acid to the MCA precursor resulted in CN panels with extended visible light absorption (Figure 4C), which further demonstrates the scope of the synthesis procedure for a variety of CN panels.

[0423] Taken together these results showed the versatility of the precursors as well as the substrate.

[0424] For the synthesis of thicker CN panels, the method mentioned above for CNMCAfilm preparation is combined with the doctor-blade technique, as shown in Figure IB and Figure 5.

[0425] This preparation method is schematically shown in Figure IB.

[0426] Briefly, the MCA supramolecular aggregates are dispersed in a hydrogen-bonding solvent, ethylene glycol, until a viscous paste is formed, which is then doctor-bladed on two glass substrates. After drying, MCA powder is sandwiched with these precursor- coated substrates, and the resulting assembly is calcined under similar conditions to yield CNMCA-Dpanels.

[0427] The difference in thickness is shown in Figures 5A-5I. Figure 5A shows a clean glass cross-sectional SEM image. Figure 5B (MCA-1 stands for x = 1, i.e., one layer coated on glass substrate using the scotch tape layers with a thickness ~24 ), Figure 5C (MCA-2 stands for x = 2, i.e., two layers coated on glass substrate using the scotch tape layers with a thickness ~42 ), Figureμm 5D (MCA-3 stands for x = 3, i.e., three layers coated on glass substrate using the scotch tape layers with a thickness ~72 pm), all three doctor-bladed samples were prepared in the presence of additional 1 g MCA powder in the ‘sandwich’. The number of doctor-blade layers is determined by the number of scotch-tapes serving as the barrier.

[0428] Figure 5E is a schematic synthesis process of binder-free CN panels, where the grey lines represent the doctor-bladed precursor layer and after calcination the resulting CN is shown in thick orange line, the thin yellow line represents thin CN from the powder sublimation only.

[0429] The MCA powder was placed between two glass slides, which by itself results in CN film (thickness ca. 1.6 ) overμ gmlass shown in Figure 5F. When x layers (x = 1, 2, or 3) of doctor-bladed MCA powder were added (shown in Figure 5E as gray lines at the glass interface), it results in films of precursor MCA-x

[0430] These are shown in Figures 5F-5I after calciation of the corresponding polymeric carbon nitride films on glass (CNMCA-DI, CNMCA-D, and CNMCA-D3). are shown in Figure 5G-5I (final thickness about 29, 37, and 68 μm). and Figures 5F-5I cross-sectional SEM images of CNMCA, CNMCA-DI (final thickness about 29pm), CNMCA-D2 (final thickness about 37pm), and CNMCA-D3 (final thickness about 68 μm).

[0431] Augmenting the “sandwich” method with doctor-blading pastes of precursors allows the thickness of the coating to be controlled (Figures 5G-5I), which is particularly important when solar radiation harvesting is a critical bottleneck for photocatalytic and related applications.

[0432] Moreover, CN-based heterojunctions may be designed by layering pastes of different compositions and thicknesses over the glass (i.e., “sandwich” precursor and doctor-bladed paste combinations).

[0433] Digital images of the obtained 6.7 x 6.7 cm2binder-free CN panels prepared by the method described herein are shown in Figures 6A-6E.

[0434] Figure 6A is an image of a clean glass. Figure 6B-6D are images of CN panels prepared by “sandwich” method and MCA as a precursor with a molar ration of 1:1 and 1:1.5 between melamine and cyanuric acid (CNMCAand CNMCA(1:1.5)) and melamine as a precursor (CNM), respectively.

[0435] Figure 6E is a CN panel prepared by doctor-blade assisted “sandwich” method and MCA as a precursor with a molar ration of 1 : 1 between melamine and cyanuric acid (CNMCA-D).

[0436] The sandwich method with MCA as the precursor yielded a transparent uniform CNMCAfilm; adding the doctor-blade step resulted in a thicker and uniform CNMCA-Dfilm. By contrast, CNM, from pristine melamine, was formed as a non-uniform film.

[0437] Moreover, this method can be extended to other photocatalyst materials such as TiO2and WO3as shown below. Furthermore, varying the doctor-bladed paste and sandwiching powder forms a variety of heterojunction- or homojunction-containing photocatalyst panels.

[0438] Structural characterization of CN panels

[0439] Scanning electron microscopy (SEM) reveals a regular and uniform rod morphology for CNMCA, made from the simple MCA precursor sandwich (Figure 7A). The interactions between the hydroxy and amine functional groups of MCA and the glass surface (mainly S i O2) direct the CN growth in the case of the CNMCApanel, and cross- sectional analysis reveals a dense layer of CN rods with an average thickness ca. 1.6 pm (Figure 7C and Figure 5F).

[0440] On the other hand, a regular porous CN morphology is observed for CNMCA-D(Figure 7B), and the corresponding cross-sectional analysis reveals a dense porous CN layer with an average thickness of 37 μm (Figure 7D and Figure 5H). SEM images of CNM and CNMCA(1:1.5) are provided in Figures 7E-7F.

[0441] Powder X-ray diffraction (XRD) of CNMCA-D(Figure 7G) shows the characteristic diffraction signals around 10 = 27.4° and 13°, which correspond to the interlayer stacking of melon-based CN layers (002 plane) and in-plane ordering of heptazine units (100 plane), respectively. The CNMCApanels do not show noticeable diffraction signals, suggesting an amorphous nature.

[0442] Fourier-transform infrared spectroscopy (FTIR) confirms the formation of CN over the glass (Figure 7H). CNMCA-Dand CNMCAshow three groups of peaks located at 804, 1200-1650, and 3200-3500 cm-1, which correspond to breathing modes of heptazine and triazine, in-plane stretching and bending vibrations of C-N heterocycles, and stretching modes of -NH, groups, respectively. Moreover, the CNMCApanel exhibits an additional peak centered at 2180 cm-1, which were ascribed to the stretching mode of C=N groups. The appearance of C=N groups indicates the presence of incompletely condensed tri-s-triazine units in CNMCA-

[0443] To investigate the influence of the glass substrate on the polymerization process and its interaction with the obtained CN, the FTIR spectra of the exposed glass substrate after scratching the CNMCAlayer and CNMCApowder (synthesized under identical conditions without glass) were compared to a pristine CNMCApanel (Figure 8). From the additional FTIR features measured on the CN panel, it was suggested that the glass substrate influences the formation of CN (i.e., the Si-O- and Si-O-Si bonds are responsible for the strong adherence of CN, Figure 8).

[0444] To explore the role of the doctor-blade step, the FTIR spectra of the scratched CN powder, the bottom layer, and the outer layer of the CNMCA-Dpanel were analyzed, comparing them with the spectrum of the original CNMCA-Dpanel (Figure 9A).

[0445] Compared to a CNMCA-Dpanel, the scratched CNMCA-Dpowder, outer layer, and bottom layer (obtained by scratching the upper layer of the panel) all exhibit an additional cyano group vibration (shaded with gray in Figure 9A). This C=N group resembles the signal detected in a CNMCApanel that did not undergo a doctor-blading procedure. Its presence indicates the formation of two distinct CN layers when an MCA supramolecular precursor is doctor-bladed on a glass substrate (Figure 9A). The MCA precursor layers that are adjacent to the glass yield the ‘bottom layer’ of CNMCA-D, which is similar to that of a CNMCApanel (Figure 9A brown and Figure 8A blue).

[0446] On the other hand, the MCA precursor away from the surface of the glass substrate yields an ‘upper layer’ of CNMCA-D, which is similar to CNMCApowder (Figure 9A pink and Figure 8A red). The observed FTIR features confirm the formation of a homojunction composed of two different CN layers. The top- view SEM image of CNMCA- D panel at the interface between the ‘upper layer’ and the ‘outer’ part, which was not doctor-bladed (Figure 9B), shows the formation of regular CN rods on the non-doctor- bladed side (right), and regular porous CN on the doctor-bladed side (left). This analysis demonstrates the formation of a heterojunction composed of two different CN layers in the case of the CNMCA-Dpanels and further supports the conclusions drawn from the FTIR analysis.

[0447] Compared to CNMCApowder (synthesized under identical conditions without glass), an additional peak is found around 2180 cm-1in the CN panel, which is attributed to C=N groups, and the intense stretching modes of -NH, groups also appear in a CN panel spectrum (Figure 8A). It shows the influence of the glass substrate during the formation of CN. In addition, a red shift of the stretching of the CN conjugated system band from 808 cm-1to 804 cm-1occurs (Figure 8B). This shift was attributed to increased CN conjugation in a CN panel compared to its powder counterpart. Moreover, the characteristic CN vibrations can still be observed even after scratching CN from the glass, along with the decrease in the intensity of the signals corresponding to Si-O-Si and Si- 0“ groups (Figure 8C-8D), supporting the strong interaction between CN and the glass substrate. In addition, the peak at 1400 cm-1for the CN powder shifted to 1411 cm-1, which further suggests the strong connection of CN with the surface of the glass substrate (Figure 8E).

[0448] X-ray photoelectron spectroscopy (XPS) analysis of the panels shows the surface chemical composition of the CN films (Figures 10-12). The XPS survey spectra confirm the presence of C, N, and O (Figure 10). The low-intensity O ls signal is attributed to adsorbed surface impurities (H2O and CO2). The high-resolution C Is spectra of both CNMCAand CNMCA-Dare decon voluted into three peaks (Figure 11A): The peak around 288.4 eV is attributed to sp2hybridized carbon of CN heptazine rings (N-C=N). The peak around 286.2 eV is attributed to C-NH, or C=N species; the intensity of this peak is slightly higher for CNMCAthan for CNMCA-D, which might result from the presence of - C=N groups, as was also indicated by FTIR analysis (Figure 9A pink). The peak at ca. 284.8 eV is attributed to graphitic carbons (C=C / C-C). The high-resolution N Is spectra of both CNMCAand CNMCA-Dare also deconvoluted into three peaks (Figure 11B). The peaks around 398.8 and 400.1 eV are ascribed to bi-coordinated and tri-coordinated nitrogens (namely, C-N=C and N-(C)3), respectively, which are present in the heptazine rings. The peak around 401.3 eV is attributed to nitrogen atoms present in -C=N or -NH, species. Overall, XPS analysis confirms the presence of heptazine units in both the CNMCAand CNMCA-Dpanels.

[0449] The C Is XPS spectra of CNM and CNMCA(1:1.5) in Figure 12A , show similar functional groups as CNMCA-Dand CNMCA(Figure 11A), confirming the successful synthesis of a polymeric carbon nitride. The most significant difference is no cyano group detected in CNM, possibly due to absence of cyanuric acid precursor. The N Is XPS spectra of CNM and CNMCA(1:1.5) in Figure 12B , show similar functional groups as CNMCA-Dand CNMCA(Figure 11B), except higher signal of N-(C)3 in the CNM case, since there are less nitrogen defects in the polymeric structure.

[0450] Optical properties of CN panels

[0451] UV-vis optical absorption spectra of CN panels (Figure 13) indicate significant absorbance into the visible region. However, the CNMCAfilm exhibits increased optical activity, especially at wavelengths higher than 450 nm (Figure 13B). This was ascribed to its rod-like morphology, which might result in multiple reflections of incident light (Figure 13A). The optical bandgaps (Eg) of CNMCAand CNMCA-Dare estimated to be 2.81 and 2.96 eV, respectively, using a Tauc plot analysis (Figure 13C). Photoluminescence (PL) spectra (Figure 14A) show that CNMCA-Dhas a lower PL intensity than CNMCA, which might indicate better charge separation.

[0452] The valence band (VB) positions of CNMCAand CNMCA-D(EVB, Figures 14B- 14C) are estimated to be 1.34 and 1.53 V, respectively. On the basis of the obtained EVB and energy gap (Eg), the conduction band energy (ECB) of CNMCA-Dand CNMCAwere calculated to be -1.43 and -1.47 V, respectively, as illustrated in the energy band diagram shown in Figure 14D. The ECB of CNMCA-Dand CNMCAare more negative than the redox couples, allowing water reduction to H2 and the two-electron oxygen reduction reaction (ORR) to H2O2. On the other hand, the EVB of CNMCA-Dis more positive than that of CNMCA, which, from a thermodynamic driving force perspective facilitates a four- electron oxidation of water to produce O2. However, for both materials, the EVB position is not positive enough for two-electron water oxidation to H2O2and water decomposition into OH*.

[0453] Example IB: Preparation and characterization of binder-free metal-oxide photocatalytic panels.

[0454] Methods:

[0455] A sandwiched 2.0 g of ammonium paratungstate was placed between two glass slides and calcined in an air oven at 500 °C for 4 h. The doctor-bladed glass with ammonium paratungstate paste (2.0 g ammonium paratungstate dispersed in 0.60 mL ethylene glycol) coated as a layer with two scotch tapes, followed by drying at 85 °C for 10 min and calcination under air for 4 h 500 °C.

[0456] Results:

[0457] As can be seen in Figure 15A, using the methods described above a thick panel was formed. Moreover, a strong sonication removes the weakly bound WO3and still shows a thick and well-attached WO3coating on glass (Figure ISA). The XPS scan spectra of WO3-D obtained after 5 mins sonication of pristine WO3- D shows peaks corresponds to only W and O, which proves the formation of WO3on glass substrate (Figure 15B).

[0458] High-resolution W 4f and O ls spectra (Figure 15C and 15D, respectively) were recorded on the surface and of etched WO3film To prove the strong interaction between formed WO3and glass surface.

[0459] The W 4f spectra and O ls spectra recorded after etching WO3surface shows an obvious peak shift compared to the spectra recorded on surface, which strongly proves the alteration of chemical environment of W and O near the glass surface, which might be due to the presence of W-O-Si bond. The linkage of W and O atoms with Si atoms of glass substrate probably induced the observed charge imbalance of W-0 bond near the glass substrate.

[0460] Taken together the results how that the technique can be applied to various catalytic materials, including polymeric CN as well as metal oxides such as WO3, TiCh-

[0461] In addition, these results show that various substrates can be used including glass, aluminum fold.

[0462] Example 2: Design of continuous flow photoreactor.

[0463] Photocatalytic activity of CN panels was tested in a continuous-flow photoreactor.

[0464] Materials and methods

[0465] The photoreactor was manufactured at the Faculty of Natural Sciences’ workshop at the Ben-Gurion University of the Negev, Beer-Sheva, Israel, according to the design shown in Figure 16 from high-performance engineering plastic, PEEK (polyether ether ketone).

[0466] Results

[0467] To demonstrate the advantage of the binder-free solar panels, their photocatalytic activity was studied in several representative reactions, namely continuous hydrogen and hydrogen peroxide formation, biomass oxidation to valuable chemicals, and water decontamination, as illustrated in Figure 17, where a schematic of the flow photoreactor assembly illustrates the possible reactions of photogenerated charges. The reactor consists of 5 different parts (Figure 17A); 1) is bottom part, 2) CN- coated panel, 3) middle part (~25 mL), 4) quartz glass window, and 5) upper part. To assemble the complete photocatalytic setup in a flow mode, first the reactor (Figure 16 A) is closed using M6 stainless steel screws and bolts. Then, the assembled reactor is connected via a peristaltic pump to a solvent reservoir (over a heating plate as the temperature control). The illumination source is placed in front of the quartz window of the assembled photoreactor. All the described system is shown in Figure 17B.

[0468] Example 3: H2O2production using CN panels in a continuous flow photoreactor.

[0469] Materials and methods

[0470] Photocatalytic H2O2 production.

[0471] The H2O2production experiments were carried out in an 5 x 5 cm2continuous- flow photoreactor developed in-house under continuous flow of the reaction mixture (~1 mL min-1) from a solvent reservoir containing 80 mL JLCkEtOH mixture (20% vol. ethanol in purified water) using a peristaltic pump. Oxygen was continuously bubbled through the solution in the solvent reservoir. The temperature of the solvent reservoir was kept constant (25 °C) during the reaction using a circulating water jacket coupled to a chiller. The produced H2O2was quantified by iodometry. The produced OH* was monitored by colorimetry using salicylic acid (SA) as a probe molecule: SA reacts with the OH* radical to produce 2,3-dihydroxybenzoic acid (2,3-DHBA), which gives a characteristic absorption at ca. 510 nm.

[0472] Results

[0473] The photocatalytic production of H2O2by the CN panel was conducted in a continuous-flow photoreactor from an aqueous solution (20% vol. ethanol) and oxygen (Figure 18A and Figure 17).

[0474] Over 2 h irradiation using a 100 W LED light (white light, z > 410 nm, Figure 19), the CNMCApanel produced 865 p mol m-2of H2O2, a higher rate than that of CNM and CNMCA(1:1.5)(Figure 18A).

[0475] To increase the photocatalyst loading relative to CNMCA, thicker CN panels (for example CNMCA-Dwith a resulting CN thickness ~37 ) were created usiμnmg the doctor- blade approach. The greater thickness and increased amount of CN are associated with higher optical absorbance and higher loading of active sites per unit area, which lead to higher production of H2O2, up to 1023 ol m-2in theμ cmase of CNMCA-Dwhere two layers of doctor-bladed MCA precursor were applied (Figure 18A).

[0476] To compare the activities of the CNMCA-Dpanel and of a heterogeneous photocatalyst counterpart, their production was measured normalized to employed CN mass. The measured mass of CNMCA-Don a 5 x 5 cm2panel is about 16.8 mg, with a H2O2production rate of 117 ol h-1μm g-1(Figure 18B left). A batch reaction under identical conditions using CNMCA-Dpowder yields a H2O2specific production rate of 91 pmol h-1g-1(Figure 18B right).

[0477] To investigate the influence of the CN panel and photocatalytic conditions on the generated H2O2, the production of OH- radicals was indirectly monitored, which would result from the decomposition of H2O2by photogenerated electrons. These measurements confirm that the generated H2O2does not decompose over CN panels during at least 2 h of continuous-flow operation (Figure 20).

[0478] The H2O2yield further increases to 1191 ol m-2(15 mμMm m-2) and 1628 pmol m-2(242 μolm g-1or 20 mM m-2) after 4 h using CNMCAand CNMCA-D, respectively (Figure 18A). Importantly, H2O2is produced at industrially relevant concentrations for water purification (> 1 mM H2O2).

[0479] The recent results of CN photocatalysts studied under nearly similar conditions to the current experimental conditions were summarized (Figure 18C and Table 2). It was noted that a precise comparison of H2O2activity of the current CN panels with state-of- the-art CN based photocatalysts is not trivial, as those studies were performed in a batch configuration and used different experimental conditions. As shown in Figure 18C, the CNMCA-Dpanel shows high activity compared to many reported CN photocatalysts. It should be noted that the CN panels remain stable after 4 h of operation under illumination (the generated H2O2is being recirculated as part of the reaction media) at relatively high flow rates (~1 mL min-1).

[0480] For simplicity, a CNMCApanel was used for control experiments to evaluate the possible mechanism for H2O2formation. All control measurements presented in Figure 18D confirm the essential role of the CN panel as a photocatalyst for H2O2production: no H2O2is produced in the absence of the photocatalyst, maximal ORR when the system is saturated with the reacting 02(g). Changing pure 02(g) to air (ca. 20% 02(g)), less H2O2production was observed. Under Ar(g) purge, very little H2O2is formed since it requires O2as the reactant. Unlike the first four described control experiments, when no illumination was done (dark), the photocatalyst could not produce photogenerated electrons and holes, thus almost no H2O2was photocatalytically produced. Figure 19A presents the spectral irradiance of the white LED light that was used for illumination. Figure 19B shows the same irradiance in a normalized manner (right y-axis) and is compared to the normalized absorbance spectrum of the CNMCA-Dpanel. The spectra demonstrate the room for improvement in light harvesting since significant part of the illuminated power is not harvested.

[0481] Table 2 Summary of known polymeric carbon nitride-based photocatalysts for H2O2production.

[0482] SEM images after 4 h confirm the physical stability of the CNMCA-Dpanels, which is attributed to the strong interaction between the glass surface and the CN films obtained by the sandwich method (Figures 21-21). In addition, the UV-vis and FTIR spectra resemble those of fresh CNMCA-D, further confirming the stability of the CN panels (Figures 22A-22B). In addition, to study the effect of CN film thickness on H2O2production, the CNMCA-DI (1 layer of MCA precursor) and CNMCA-D3 (3 layers of MCA precursor) panels (Figures 23A-23E) were tested relative to the CNMCA-Dprepared using 2 layers. CNMCA-D(2 layers of MCA precursor) showed the highest H2O2yield, i.e., the measured yield order is CNMCA-DI < CNMCA-D3< CNMCA-D(Figure 23B).

[0483] Based on our results, a possible mechanistic pathway was proposed for H2O2formation over CN panels (represented by a heptazine subunit in the scheme) in Figure 24. Upon absorption of two photons by CNMCA(shown in a), holes are created that predominantly reside at N2 and N6 atoms, while the corresponding electrons are found on Cl and N4 atoms (shown in b). The holes oxidize ethanol, which results in the hydrogenation of N2 and N6 (shown in c). Subsequently, an electron from Cl or N4 reduces molecular oxygen (O2) to form a superoxo radical (shown in d). Immediately, this superoxo radical is further reduced by another electron to form a 1 ,4-endoperoxide species on the triazine ring of CNMCA(shown in e). Finally, the successive protonation of the formed 1,4-endoperoxide species yields H2O2to complete the catalytic cycle (shown in a).

[0484] It has been shown that the aromatic endoperoxides generate singlet oxygen upon heating or photoexcitation. The generated singlet oxygen can be trapped by 1,5- dihydroxynaphthalene (1,5-DHN) to yield 5-hydroxynaphthalene- 1,4-dione (juglone).

[0485] To prove the formation of 1,4-endoperoxide species, 1,5-DHN was added to the reaction mixture (Figure 25) and monitored the formation of juglone at regular time intervals. As shown in Figure 25, the juglone concentration increases with the reaction time, indicating the formation of singlet oxygen, thus indirectly confirming the formation of 1 ,4-endoperoxide species on triazine rings during a two-electron ORR.

[0486] While hydrogen peroxide (H2O2) is a promising low-cost, carbon-free liquid fuel, the conventional anthraquinone process (AOP) for H2O2production raises environmental concerns as it involves high energy consumption and causes environmental pollution. In addition, the AOP requires external H2 to regenerate the catalyst.

[0487] Therefore, the results shown herein above provide an eco-friendly reaction using the photocatalytic activity of the reported CN panels. Example 4: Photocatalytic HMF oxidation performance.

[0488] Materials and methods

[0489] Photocatalytic HMF oxidation

[0490] The experimental conditions and basic setup for 5-hydroxymethyfurfural (HMF) oxidation were similar to H2O2experiments described above.

[0491] In this case, the solvent reservoir contained 80 mL of a 5.0 mM aqueous solution of HMF. To understand the role of reactive oxygen species (superoxide radical and singlet oxygen) on HMF photooxidation, controlled experiments were performed under batch conditions in a quartz reaction tube, where 5 mg of CNMCA-Dpowder and 1 mM of HMF / DFF in 5 mL of water were taken and magnetically stirred under 100 W LED light irradiation (2680 W m-2).

[0492] Results

[0493] Photocatalytic HMF oxidation was conducted over a CNMCA-Dpanel in pure water using a continuous-flow reactor (see reaction scheme in Figure 26A).

[0494] The reaction resulted in 75% HMF conversion with a 13% DFF yield after 24 h (estimated residence time 0 = 15.6 h) (Figure 26B). The moderate DFF selectivity was attributed to the formation of H2O2in parallel to HMF oxidation (Figure 27). However, the H2O2concentration constantly decreases with time, as it is consumed, presumably by reaction with DFF — leading to the cleavage of bonds and the formation of CO2or other aliphatic intermediates. The aliphatic intermediates formed during HMF photooxidation in water were monitored at regular intervals using high-pressure liquid chromatography (HPLC, Figures 28A-28B). The concentration of aliphatic intermediates increased with time (Figure 28B), along with DFF yield (Figure 28A). The HCOOH and MA were identified as one of the intermediates (Figure 28B). To confirm the effect of generated H2O2on DFF yield, a photocatalytic batch reaction was performed using CNMCA-Dpowder as a control experiment, where aq. H2O2was added to the reaction mixture containing DFF. After 4 h, the entire DFF was consumed, forming aliphatic intermediates, including MA and HCOOH (Figures 29A-29B). Nevertheless, it was noted that the obtained DFF yield in this study is comparable to the DFF yield obtained by conventional batch systems where water is used as a green solvent (Table 3).

[0495] Table 3 Summary of known photocatalysts for HMF oxidation.

[0496] It should be noted that using CN panels in continuous-flow conditions, high HMF conversion rate (1185 ol h-μ1m g-1) was achieved, which is among the state-of-the-art heterogeneous photocatalysts (Figure 26C and Table 3). Post-operational characterization studies emphasize the structural and chemical stability of the panel after a continuous operation for 24 h (Figures 30-31). This stability and the high HMF conversion in pure water motivate the adaptation of continuous-flow photochemistry to oxidation reactions of more challenging biomass substrates (e.g., lignin, cellulose, and glycerol).

[0497] Based on the previous reports on HMF photooxidation using carbon nitride-based photocatalysts in air / O2atmosphere and above disused H2O2generation mechanism over CN panel, it is assumed that the singlet oxygen could be the ROS species responsible for photooxidation HMF. To elucidate the mechanism, the role of1O2(singlet oxygen) was verified by two control experiments, in presence of NaN3 (singlet oxygen trapping agent) and 1,5-DHN, during the HMF oxidation experiment. The presence of NaN3 decreases the HMF conversion drastically and lowers the yield of DFF, MA, and HCOOH (Figures 32A-32D). UV-vis absorbance shows the formation of juglone during the HMF oxidation due to its reaction with 1,5-DHN (Figure 32C). Interestingly, after the complete consumption of 1,5-DHN, the yield of H2O2increases (Figure 31D), confirming the dominant role of singlet oxygen during HMF oxidation.

[0498] The HMF oxidation via superoxide radical formation was ruled out by using 1 ,4- benzoquinone (p-BQ) as superoxide trapping agent. The p-BQ leads to an increased HMF conversion and higher yield of aliphatic intermediates including MA and HCOOH compared to both control and singlet oxygen quenching experiment (Figures 32A-32B).

[0499] Therefore, based on the obtained results and published HMF photooxidation, a mechanism was suggested and shown in Figure 33.

[0500] Upon illumination, the electrons in the CN are excited to a singlet state and form singlet excitons, which quickly converts to triplet excitons by an intersystem crossing process. Then, triplet excitons react with O2to produce1O2- The1O2then oxidizes HMF to DFF along with H2O2generation. The generated H2O2further oxidizes the DFF to various aliphatic intermediates before complete mineralization.

[0501] Example 5: Water purification

[0502] Materials and methods

[0503] Photocatalytic RhB dye degradation The basic setup for photocatalytic water decontamination experiments (photodegradation of a representative organic contaminant, 9-(2-carboxyphenyl)-6- (diethylamino)- N,N-diethyl-3H-xanthen-3-iminium chloride, abbreviated as rhodamine B, RhB) was similar to that for HMF oxidation, except that an aqueous RhB solution was circulated through the system continuously, passing through a standard 10 mm quartz cuvette before reaching the solvent reservoir.

[0504] Results

[0505] The RhB concentration was continuously monitored by UV-vis absorption; scans were recorded every 10 minutes from 600 to 480 nm. (Figure 34A)

[0506] Here, the RhB degradation progress was followed by connecting the continuous- flow reactor with a simple UV-vis spectrometer (Figure 34B). The CN panel showed 58% pollutant degradation after 110 min (Figure 34C) (calculated pseudo-first order rate constant k = 0.0079 min-1(Figure 34D).

[0507] These results demonstrate the versatility of the binder-free CN panels by the continuous decontamination of organic pollutants in water. The photodegradation of Rhodamine B (RhB) was studied as a model molecule. A significant advantage of continuous-flow chemistry is continuously monitoring the reactants and products. This allows the reaction rate to be determined using various analytical instruments, unlike batch reactors, where aliquots are taken for sampling and require separating the solid catalyst before analysis.

[0508] Example 6: Direct H2 production using binder-free photocatalysts

[0509] Materials and methods

[0510] Photocatalytic H2 production

[0511] The photocatalytic H2 production experiments were carried out in the same 5 x 5 cm2continuous-flow photoreactor by connecting its outlet to an additional gas reservoir of -13.5 mL volume (Figure 35A). Typically, a volume of 25 mL of 20% vol. EtOH in water that also contained 20 μL of 8% wt. chloroplatinic acid (EtOH was used as a sacrificial electron donor and Pt as cocatalyst — photodeposited in situ during the H2 production) was fed to the flow reactor using a regular syringe by manual force. The empty gas reservoir (-13.5 mL) was purged with Ar gas for 30 min. Any gas produced during the experiment automatically feeds the reservoir, as it is connected perpendicular to the outlet of the tightly-sealed photoreactor. After illumination, a 200 pL sample was collected from the headspace of the gas reservoir using a gas-tight syringe and analyzed by gas chromatography (GC).

[0512] Results

[0513] For the H2(g) production, Pt was deposited as a reduction cocatalyst on the binder- free CN panels and used EtOH as a hole scavenger (see Figures 35A-35B for the experimental setup). The CN panel generates 5.84 ol of H2 at a ratμem of 584 ol h-1μm m-2after 4 h. The SEM image of a CN panel after the HER experiment confirms the stability of the materials as well as the successful Pt photoreduction (3.65% wt. of Pt measured by energy-dispersive X-ray spectroscopy (EDS) analysis) on CNMCA(Figure 35C).

[0514] Example 7: Co-catalyst-free peroxide-mediated H2 production using HER inactive semiconductors

[0515] Materials and methods

[0516] Materials

[0517] Melamine (M, 99%), cyanuric acid (CA, 99%), 8% wt. chloroplatinic acid (H2PtCl6) solution, formaldehyde (37% wt., ACS grade, 10-15% methoanol as stabilizer), and WO3nanoparticles were purchased from Sigma-Aldrich. Methanol (EtOH, 99.9%, absolute) was purchased from Bio-Lab, Israel. Hydrogen peroxide (H2O2, 30% wt.) was purchased from JT Baker. Formaldehyde (37% wt.). Potassium iodide (KI, >99%) was purchased from Fisher Chemicals. Potassium hydrogen phthalate (HPLC grade) and salicylic acid (SA, 99%) were purchased from Thermo Scientific. 1,5- dihydroxynaphthalene (DHN, 98%), and ammonium paratungstate (99%) were purchased from Angene Chemical, UK. High purity oxygen (99.99%) and argon (99.999%) gases were purchased from Maxima Ltd., Israel.

[0518] Deionized (DI) water for all aqueous solution preparations was collected after treatment through a Millipore Direct-Q 3 water purification system (resistivity of 18.2 MΩ cm at room temperature).

[0519] Synthesis of MCA precursors Melamine (M) and cyanuric acid (CA) (1:1 mol ratio) powders were dissolved in 25 mL of DI water and shaken in a tube for overnight using an automatic shaker at 300 rpm. The obtained MCA precursor was centrifuged at 6000 r μm (4430 ref) for 15 min and washed with DI water three times, and finally vacuum-dried at 50 °C overnight.

[0520] Synthesis of CN

[0521] The obtained MCA powder was placed in a rectangular ceramic crucible and covered with a lid. Then, the crucible placed in a tube furnace and calcined at 530 °C for 4 h under constant N2 flow, which yielded melon-type CN powder.

[0522] Synthesis of bulk WO3

[0523] Bulk WO3was synthesized according to a reported procedure. Briefly, 3 g of ammonium paratungstate was placed in a ceramic crucible and calcined at 500 °C for 4 h under static air. Commercially available WO3NPs were purchased from Sigma Aldrich (Product No. 550086).

[0524] Photocatalytic H2 and HCOOH production over CN and WO3 photocatalysts

[0525] The photocatalytic experiments were carried out in a typical quartz cell under visible-light in a controlled atmosphere (static air, 02(g), or Ar(g)). Briefly, 20 mg of the photocatalyst (CN powder, bulk WO3, or WO3NPs) were dispersed in a volume of 5 mL basic (or neutral) aqueous solution containing 20% vol. MeOH (1 mL MeOH + either 4 mL 0.1 M NaOH(aq) or pure DI water). The quartz cell was sealed with a rubber septum. The quartz cell was kept in a water bath, maintained at temperature of 25 or 40 °C using a water-circulating chiller. White LED light (100 W, 2680 W m-2) used as a light source. Upon illumination, 200 μL of gas sample was collected from the headspace of the reaction utilizing a gas tight syringe for analysis of gaseous products using gas chromatography (GC). The liquid products analyzed by high-p liquid chromatography (HPLC) equipped with DAD detector using a hiplex-H column.

[0526] Results

[0527] Figure 36 is a schematic diagram of the proposed H2O2-mediated co-catalyst free H2 and HCOOH production over CNMCAphotocatalyst powders or panels in comparison with the traditional approach where a Pt co-catalyst is deposited before the reaction takes place. As schematically shown in Figure 36, the catalytic material (shown for example as CN) oxidizes a compound containing a hydroxyl group (shown for example as methanol) to the respective aldehyde and in parallel reduces oxygen to hydrogen peroxide. These two reactions products, i.e. the aldehyde and hydrogen peroxide react to form hydrogen.

[0528] This in situ H2O2-mediated approach unlocks a new way to produce H2 using the so called ‘HER-inactive’ photocatalysts. This new approach not only reduces the cost of catalytic system by ~8 times by completely avoiding the use of precious metal co- catalysts, but also produces valuable HCOOH as a valuable liquid product (as schematically shown in Figure 36).

[0529] As shown below, the photocatalytic co-catalyst free H2 and HCOOH production can be done using several semiconductors, namely CN and WO3.

[0530] Characterization of catalysts

[0531] The CN prepared by calcination of melamine-cyanuric acid supramolecular precursor. Powder X-ray diffraction (XRD) of CN (Figure 37A) presents diffraction signals around 10 = 27.4° and 13°, which are assigned to the interlayer stacking of CN layers (002 plane) and in-plane ordering of tri-s-triazine structure (100 plane), respectively. The FTIR spectra of CN (Figure 37B) presents characteristic peaks around 3200-3500 cm-1, 1200-1650 cm-1and 804 cm-1, which are assigned to -NHx groups, C- N heterocycles and heptazine / triazine moiety, respectively.

[0532] The XPS survey spectra of CN (Figure 38A-38C) confirms the presence of C and N elements. The individual high-resolution C Is and N Is spectra further confirms the nature of C and N in the CN.

[0533] The calculated absorption spectrum, using the Kubelka-Munk method (Figure 39A) and Tauc-plot (Figure 39B) reveal a band gap energy of about 2.98 eV for CNMCA.

[0534] The bulk WO3prepared according to previous literature and its basic characterization confirms the formation of bulk WO3(Figure 40-41).14The basic characterization of commercially purchased WO3NPs can be found in Figures 41-42).

[0535] Visible-light driven H2 production mediated by in situ generated H2O2 Photocatalytic H2O2generation through ORR is possible in the presence of multiple semiconductor-based photocatalysts.7Among all the reported catalysts, the polymeric CN-based photocatalysts showed high H2O2yields, promoted by water oxidation or aqueous-phase biomass oxidation.6Recently, our group has demonstrated a continuous-flow photoreactor for H2O2production over CN panels. The generated H2O2is often consumed during biomass-derived chemical oxidation — effecting the overall H2O2yield as well as the selectivity of targeted biomass oxidation product. It has been demonstrated that the H2O2rapidly reacts with HCHO to produce H2 and HCOOH without any catalyst.11Therefore, CN photocatalyst can oxidize methanol (MeOH) to HCHO along with a two-electron O2reduction (ORR) to H2O2under ambient air. Furthermore, the in situ generated H2O2and HCHO react at contact to produce H2 and HCOOH without requiring a co-catalyst.

[0536] XPS survey spectra (Figure 43 A), W 4f XPS spectra (Figure 43B), and O ls XPS spectrum (Figure 43C) of commercial WO3nanoparticles show pure WO3material was used.

[0537] The calculated absorption spectrum, with the Kubelka-Munk method (Figure 44A) and Tauc-plot (Figure 44B) depict a band-gap energy of about 2.49 eV for WO3nanoparticles.

[0538] First, the reaction parameters, such as solvent and reaction temperature were studied as shown in Figure 45. The CN produced 0.7 ol H2 at rate ofμ 9m.3 ol h-1g-1from pure water or MeOH at 25 °C temperature after 4 h and the same reaction at 40 °C produced 1.1 olμ Hm2 at rate of 14.3 ol h-1g-1.μ Cmhanging the solvent to an alkaline one (0.1 M NaOH) the CN produced more H2 (7.2 ol) at a rate oμfm 57 ol h-1g-1at 25 °C. Further increase of the reaction temperature to 40 °C, produced 8.5 ol H2 at a rate of 107 oμlm h-1g-1. The same experiment in presence of 0.05 M H2SO4produced only 0.07 μoml H2 at a rate of 0.9 ol h-1gμ-1m. Further, the ‘standard’ photocatalytic HER experiments were performed using CN powder loaded with 3% wt. Pt as the co- catalyst, has produced 9 and 30 ol H2 at aμ rmate of 115 and 345 ol h-1g-1at 25 and 40 °C respectively.

[0539] It should be noted that this new approach allows the use of any H2O2-producing photocatalyst for H2 production without additional co-catalyst(s). To demonstrate the advantage of this new H2 production process, it was chosen to test WO3— a visible-light active photocatalyst, known for 2-electron ORR — yet, inactive for photocatalytic H2 production. Surprisingly, bulk WO3has produced 1.8 ol H2 at a rate ofμ 2m2 ol h-1g-1from water / MeOH at 40 °C. The same experiment in pure MeOH produced only 0.1 pmol H2 at rate of 0.72 ol h-1gμ-m1, which suggests that the necessity of water. To verify the suggested mechanism and to show the generality of our new approach, commercial WO3NPs (50-100 nm size) were tested — prior to our MeOH photooxidation experiments, this WO3NPs was first tested for regular H2O2production in presence of 20 vol% EtOH in pure water at 40 °C and results proved the commercial WO3NPs can produce H2O2(Figure 46) — WO3NPs produced 5.3 ol H2 at a rate oμfm 67 ol h-1g-1from water / MeOH at 40 °C, which is much higher than bulk WO3and CN under similar conditions.

[0540] The control experiment in presence of argon (Ar) atmosphere showed negligible H2 production — confirming the crucial role of O2in generating H2 under these experimental conditions. After 24 h, CN and both WO3photocatalysts shows improved H2 yields (inset of Figure 45). The GC analysis of the headspace shows the consumption of O2during this reaction along with H2 production, further showcasing the ORR coupled H2 production (Figures 47A-47B). Recently, it has been demonstrated that WO3-Xnanowires could produce H2 due to shifting of their conduction band upwards as a result of quantum confinement.15Therefore, WO3NPs were also checked for regular photocatalytic HER using 3% wt. Pt as the co-catalyst — no H2 was produced under these experimental conditions (it should be noted that this experiment repeated two times). This result strongly supports our hypothesis that WO3NPs — an otherwise inactive photocatalyst for HER — can produce H2 via the reported H2O2-mediated approach.

[0541] Mechanistic investigations

[0542] To understand the reaction of in situ generated H2O2and HCHO to produce H2 and HCOOH, a direct reaction of commercial H2O2(30% wt.) and HCHO (37% wt.) were performed under identical conditions without photocatalyst in the dark (Figure 48). The direct mixture in pure water at 25 °C produced 4.73 ol h-1of H2. No Hμ2m was produced with individual HCHO even after 24 h, which indicates the role of H2O2in HCHO oxidation to H2 and HCOOH production. The same reaction in 0.1 M NaOH at 25 °C produced 85 ol h-1of H2, whμicmh also confirms the better H2 yields obtained in 0.1 M NaOH with CN photocatalyst earlier. The higher activity obtained in 0.1 M NaOH might be due to the formation hydroperoxide anion (HOO-), which is a better nucleophile than H2O2.16No H2 was produced with only HCHO even after 24 h, which further rules out the reaction of HCHO with NaOH to give H2 and strongly supports the role of H2O2under these experimental conditions. Increasing the reaction temperature to 40 °C produced higher H2 (99 ol h-1), which μ fumrther supports the higher H2 yield obtained with CN in earlier experiments. The HCHO alone produced negligible H2 (0.03 ol h-1) aμt 4m0 °C, which almost 3300 times less that of the experiment with H2O2. This not only rules out the possibility of direct HCHO oxidation to H2 but also the role of H2O2to generate H2 under these experimental conditions.

[0543] To understand the kinetics of H2O2reaction with HCHO in pure water and 0.1 M NaOH, H2O2 / HOO- UV-vis spectra in situ were monitored during the dark reaction at 25 °C for 1 h (Figures 49A-49F). Figures 49A-49D show no significant change in individual H2O2 / HOO- and HCHO UV-vis spectra for 1 h, which shows individual H2O2and HCHO is stable in both pure water and 0.1 M NaOH. After mixing H2O2and HCHO in pure water, the corresponding H2O2band slowly decreased during 1 h, which shows the H2O2is being consumed during the reaction with HCHO (Figure 49E). Surprisingly, the same mixture in 0.1 M NaOH resulted a rapid decrease in HOO- UV-vis band (Figure 49F). This fast kinetics is due to the better nucleophilicity of HOO- than H2O2.16This in situ UV-vis analysis results further supports the better H2 yield obtained in 0.1 M NaOH over CN photocatalyst previously (Figure 45). Since, H2O2reacts relatively slow with HCHO in pure water (Figure 49E), it can be possible to observe the formation of new intermediate C-O bonds that arises due to the reaction of H2O2with HCHO using FTIR spectroscopy technique. Therefore, FTIR were recorded by simply mixing commercial H2O2with HCHO in pure water (Figures 49G-49H). The Figure 49G shows no change in individual FTIR spectra of HCHO even after 7 days — no formation of C-0 bonds. The Figure 49H shows the FTIR spectra of the mixture of H2O2and HCHO. The peak at 1026 cm-1, corresponds to C-OH group of HCHO in water, gradually deceasing with the rise of a new peak at 1064 cm-1, corresponds to C-0 bonds, with time. It was ascribed that this new peak corresponds to the intermediate (HO)CHOOCH(OH). After 7 days, the C- OH group of HCHO in water completely disappeared with formation of new peaks at 1206 cm-1and 1711 cm-1which corresponds to HCOOH.

[0544] Based on literature reports4,6 1411, the possible mechanistic pathway for the photocatalytic co-catalyst free H2O2-mediated H2 production is proposed in Figure 50A.

[0545] As can be seen in Figure 50A, it was suggested that the catalytic material is characterized by an having a Valence Band Maximum (VBM) and the Conduction Band Minimum (CBM) that allows the oxidization of a compound containing a hydroxy group to the respective aldehyde and in parallel the reduction of oxygen to hydrogen peroxide. It was suggested that the VBM is sufficiently positive to allow oxidization of a compound containing a hydroxy group to the respective aldehyde and the CBM is sufficiently negative to allow reduction of oxygen to hydrogen peroxide.

[0546] Upon visible-light illumination, photogenerated holes and electrons form in the WO3. The holes oxidize MeOH to HCHO and 2 H+are released. The electrons reduce O2consuming 2 H+in the process to produce H2O2(a typical 2-electron ORR pathway). Then, H2O2oxidizes HCHO in the solution to H2 and HCOOH.

[0547] The formation of HCHO was confirmed by Nash method (Figure 51). Subsequently, the photogenerated electrons reduce O2through a two-electron reduction path to produce H2O2. The generated H2O2immediately reacts with HCHO to form a corresponding HOOCH(OH), which further reacts with another HCHO to produce (HO)CHOOCH(OH).11This (HO)CHOOCH(OH) rapidly converts to H2 and two molecules of HCOOH.

[0548] To further prove the reaction pathway for H2 and HCOOH, the amount of HCOOH obtained after 4 h using CN photocatalyst was quantified. After 4 h, the CN produced ~23 ol oμfm HCOOH (Figure 52), which is higher than theoretically expected. Under alkaline conditions at elevated temperatures, the formed HCHO can undergo Cannizzaro pathway to produce HCOOH and MeOH. Thus, a controlled experiment was performed in dark by directly taking 1 mL of HCHO (37 wt.%) in 0.1 M NaOH at 40 °C. After 4 h, only negligible amount of H2 (0.12 ol) producedμ, wmhich is ~71 times lower than that MeOH photooxidation using CN (8.5 ol). The HPLCμm analysis of HCHO dark reaction showed the formation of HCOOH (Figure 53). This strongly supports the excess HCOOH yield obtained during CN photocatalysis might be due to the side reaction of HCHO to HCOOH due to possible Cannizzaro pathway and also has no contribution in H2 generation. In addition, some control experiments were performed with CN photocatalyst with 1 mL of commercial HCHO (37 wt.%) and HCOOH (98%) instead of MeOH in 0.1 M NaOH at 40 °C to understand the H2 production mechanism (Figure SOB). In presence of HCHO (37 wt.%), the CN produced 7.3 ol of H2, which mμigmht be due photooxidation of 10-15 % MeOH present in HCHO solution as stabilizer. After 24 h, the yield increased to 13 ol onlμym, which is lesser than that of with pure MeOH experiment (Figure 54). To further verify the possibility of the direct photo-oxidation of HCHO to H2, same experiment were performed under Ar atmosphere. After 4 h, only 1.8 pmol of H2 was produced. This further confirms the majority of H2 is being produced from the reaction of photo generated H2O2and HCHO. Moreover, it can also be predicted that the formed HCHO during MeOH photooxidation directly converts to HCOOH — which subsequently decompose over CN photocatalyst with the aid holes or reaction with generated H2O2to produce H2. Therefore, another photocatalytic control experiment was performed by directly taking commercial HCOOH (98% purity) instead of MeOH under the same experimental conditions. After 4 h, the CN produced only 0.2 ol of H2, which is ~42 times lower than that the same experiment using MeOH (8.5 ol). After 24 h, the yield reached to only 0.5 ol (Figuμrme 54). This observation strongly confirms the H2 is not produced from HCOOH decomposition. Therefore, based on these controlled experiments (Figure 50B) and previously discussed dark experiments (Figure 48), it is concluded that the H2 is only generating from the reaction of in situ generated H2O2and HCHO during MeOH photooxidation.

[0549] Scalability tests

[0550] To demonstrate the scalability, batch reaction with 200 mg of CN photocatalyst was performed. The reaction yielded 18 ol of H2 afteμrm 4 h (Figures 55A). It should be noted that the CN produces H2O2and HCHO during light irradiation and the produced H2O2and HCHO reacts with each other and generates H2 and HCOOH, which is independent of light. So, after light off, an additional 8 ol of H2 after 19 hμm in dark was also observed. Overall, the H2 yield was 26 ol after 4 h lμigmht and 19 h dark reaction. Further, a cycle experiments with 20 mg of CN photocatalyst (Figure 55B) was also done. After each cycle, the reaction mixture is degassed for 5 min under sonication and sealed again with fresh air. The reaction mixture was stirred in dark for 15 min prior to light irradiation. It was noticed a small amount of H2 in each cycle after 15 min stirring in dark, which is might due to the reaction of left over H2O2with excess of HCHO formed from previous cycle. The obtained amount H2 was subtracted from each cycle when estimating the H2 after 4 h in light. Overall, the 6 cycles (24 h, 4 h each) yielded 57 ol of H2, which is higher than the direct 24 h experiment performed earlier (23 ol) in single cycle (the O2is consumed during the reaction). The increased H2 yield in the initial cycles might be due to the reaction of left over H2O2and HCHO or availability of excess of HCHO obtained in the previous cycle, which might act as a better hole scavenger instead of MeOH to promote ORR. This encouraging results in cycle experiments could enable to optimize a flow reactor system with controlled air flow — can generate H2 continuously without aid of any dedicated gas separation setup.

[0551] Furthermore, a binder-free CN panel was also prepared to demonstrate H2 production in a batch configuration over a 1 cm2panel (specifically, CNMCA). After 24 h, the CN panel produced around 1.1 ol of H2μm with rate of 460 ol h-1m-2, whicμhm further demonstrates the ability to scale this ORR-mediated H2 production approach technology using large-scale flow reactors.

[0552] Example 8: Preparation and characterization of plastic-based photocatalytic panels.

[0553] Materials and methods

[0554] Chemicals

[0555] Deionized (DI) water was purified using a Millipore Direct-Q system (18.2MQ cm resistivity). All other chemicals were purchased from the indicated commercial vendors and used as received: hydrochloric acid (HC1, 32 wt%, AR) and ethanol (EtOH, absolute 99.9%) from Bio-Lab, Israel; high-density polyethylene (HDPE) melt index 2.2 g / 10 min (190 °C / 2.16 kg), titanium (IV) oxide, anatase, nanopowder, <25 nm particle size, 99.7% trace metal basis, tungsten (VI) oxide, nanopowder, <100 nm particle size (TEM), zinc oxide, nanopowder, <100 nm particle size, bismuth (III) oxide nanopowder, 90-120 nm particle size, 99.8% trace metals basis, melamine (M, 99%), and chloroplatinic acid solution (8 wt% H2PtCl6 in H2O) from Sigma Aldrich. Synthesis

[0556] Melem and the CN photocatalysts were synthesized as follows:

[0557] Melem

[0558] Melem was synthesized via thermal condensation of melamine under a nitrogen atmosphere at 425 °C for 12 h; the target temperature of 425 °C was reached at a heating rate of 5 °C min-1and finally washed several times with hot water to get rid of smaller condensates (i.e., unreacted melamine or partially reacted species).

[0559] 2-Cl-mlm precursor

[0560] The precursors for the CN synthesis were supramolecular assemblies based on the melem-halogen (mlm-Cl) interaction; 2 stands for the molar Clmelem ratio in the starting mixture: first, 0.50 ± 0.01 g of the synthesized melem was dispersed in 25 mL of an aqueous solution containing 2.0 vol% of concentrated HC1 32 wt. %. To achieve dispersion, the mixture was subjected to a 3 min sonication followed by shaking for 24 h. The dispersion was then poured into large borosilicate-glass Petri dish and left to dry and crystallize at room temperature for three days (this is the precursor).

[0561] CN-2-Cl-mlm

[0562] The addition of the prefix “CN-” denotes the precursor has gone through thermal condensation process to give the CN photocatalyst. 0.67 ± 0.01 g of the precursor was calcined in an alumina crucible (total capacity 20 mL), with a lid in a muffle furnace (under air; heating rate of 5 °C min-1to the target temperature of 550 °C) for 4 h to obtain the CN material as the product.

[0563] Photocatalyst / HDPE panel

[0564] HDPE was melted in an alumina template with dimensions of 6.7 x 6.7 cm2, and while the HDPE was in a molten state, a photocatalyst powder (Bi2O3, ZnO, WO3, TiCL, or polymeric carbon nitride (CN)) was spread on top and lightly pressed into the molten HDPE panel. Then cooled down back to room temperature and solidified around the photocatalyst powder, physically holding a thin layer of the photocatalyst- these are the photocatalytic panels.

[0565] Results Figure 56 shows schematic representation of the panel preparation process. As can be seen, an HDPE source (here, in the form of beads) is melted at 220 °C in an alumina template (demonstrated, size of 6.7 x 6.7 cm2), then the photocatalyst powder (as a representative example, CN) is spread and lightly pressed into the molten HDPE, and left to cool down to room temperature under ambient conditions. The inset shows scanning electron microscopy (SEM) image of the CN / HDPE panel (CN highlighted with a light- yellow hue).

[0566] Figures 57A-57B show digital photos of Figure 57A HDPE plastic waste as the source material, Figure 57B dispersed CN powder in the reaction vessel; bottom: plastic waste melted, with CN powder spread on it using the demonstrated method, photocatalytic HER batch configuration, top: powder; bottom: CN / HDPE panel.

[0567] Figures 58A-58D are digital photographs of different photocatalytic HDPE panels. As can be seen, the variety of HDPE-based panel such as Bi2O3 / HDPE (Figure 58A), WO3 / HDPE (Figure 58B), TiO2 / HDPE (Figure 58C), and ZnO / HDPE (Figure 58D) can be prepared.

[0568] Figures 59A-59D illustrates the generality in picking the plastic support, as it is possible to choose any thermoplastic material with a lower melting temperature than the degradation temperature of the deposited photocatalyst.

[0569] Figures 60A-60J show SEM images of a pristine HDPE surface and CN-2-C1- mlm / HDPE panel (surface and cross-section). It is clear that the pristine HDPE has a very smooth surface while the CN deposited on its surface exhibits surface roughness as a result of the deposition of CN particles, partially immersed in the HDPE substrate acting as support. From the cross-section it is evident that the CN layer is very thin in the order of several .μm

[0570] Figures 61 and 62 show the distribution of CN on the panel in the form of clusters. FIB cross-section SEM EDS mapping illustrates a grain of CN (both C and N elements) in the HDPE platform (only carbon). This configuration stems from the solidification of the molten plastic around CN grains, physically holding them in place.

[0571] As shown in Figure 63, the FTIR, XRD, and UN-vis absorption spectra of CN- 2-Cl-mlm / HDPE panel show either a combination of the HDPE and CN-2-Cl-mlm powder patterns, or properties similar to the CN powder, with no additional contribution from the combination. It suggests insignificant chemical interaction between the CN powder and the HDPE surface. Figure 63D shows the action spectrum of CN-2-C1- mlm / HDPE panel, where a correlation between the optical absorption of the CN semiconductor and the photocatalytic activity at specific wavelength irradiation is established.

[0572] Figures 64A-64E show the XPS data of the pristine HDPE panel, the CN powder (CN-2-Cl-mlm), and the CN / HDPE panel. The C Is spectra show that the CN / HDPE panel exhibits a combination of the CN powder and pristine HDPE features.

[0573] This is direct evidence that both surfaces are exposed, which should allow access to reactant molecules to the photocatalyst during a photocatalytic reaction on the one hand, and protection from surface agglomeration since HDPE signal indicates the CN is partially embedded within the HDPE. There is no evidence of covalent chemical bonds since no binding energy shifts are measured for neither CN nor HDPE. The N Is spectra similarly suggest no chemical modification of the CN-2-Cl-mlm powder when it is held on the HDPE panel.

[0574] Example 9: H2O2production using HDPE-based photocatalytic panels.

[0575] Materials and methods

[0576] ORR

[0577] ORR experiments were performed in a flow reactor configuration. Typically, a 5 x 5 cm2panel was placed inside a flowreactor of 25 cm2volume with 80 ± 0.5 mL reservoir of 10 vol% EtOH in DI. The reaction mixture was circulated between the reactor and reservoir with a peristaltic pump with a flow rate of ~1 mL min-1. Oxygen was continuously bubbled through the solution in the solvent reservoir. The temperature of the solvent reservoir was kept constant (25 °C) during the reaction using a circulating water jacket coupled to a chiller. The produced H2O2was quantified by iodometry.

[0578] Results

[0579] Figures 65A-65B show schematic representation of flow and batch photocatalytic processes. As can be seen in Figure 65A, the oxygen reduction reaction (ORR) occurs in the flow reactor configuration, 25 cm2panel with a 100 mL reservoir of O2saturated 10% EtOH in DI, at a flow rate of 1 mL min-1. Figure 66 shows the stability cycles of the CN-2-Cl-mlm / HDPE panel used for both in photocatalytic HER (using a Pt cocatalyst) and photocatalytic metal-free ORR. Demonstrating highly stable performance in both cases. For HER, retaining 93.3% activity after 12 hours, which is significantly more stable than the powder reaction, retaining only 80% after 10 hours. The ORR performance shows high stability retaining 92% of its initial photocatalytic reaction rate after 18 hours of reaction, while for powder reactions this reaction rarely passes 3 hours of stable photocatalytic performance. These photocatalytic experiments are performed under 100 W white LED illumination. Changing the light source to a solar simulator (100 W Xe lamp source with AM 1.5G and water filters, 100 W cm-2) results in an activity of 442 ol (H2O2) h-1m-μ2m for 3 hours. The long-term operation for a week in Figure 66E demonstrates the stability of this photocatalytic panel towards the hydrogen evolution reaction.

[0580] Figure 67 shows long-term H2O2production (ORR) using a 5 x 5 cm2CN-2-C1- mlm / HDPE panel, in a flow reactor configuration with a 100 mL of 1 M D-Glucose in DI reservoir, and a 25 cm2cell, under 100 W white LED illumination and oxygen atmosphere.

[0581] Figure 68 shows H2O2production (ORR) using a 5 x 5 cm2CN-2-Cl-mlm / HDPE panel, in a flow reactor configuration with a 100 mL of 0.36 M of 4-methoxy benzyl alcohol in DI reservoir, and a 25 cm2cell, under 100 W white LED illumination and oxygen atmosphere.

[0582] As can be seen in these figures, long-term stability under operational conditions is demonstrated using the CN / HDPE panel for continuous-three week operation: first, for two weeks, H2O2-assisted glucose oxidation was performed (Figure 67), and subsequently, the same panel was used for another week to perform 4-methoxy benzyl alcohol oxidation (Figure 68).

[0583] Figure 68 shows H2O2production with a 5 x 5 cm2CN-2-Cl-mlm / HDPE panel, in a flow reactor configuration with a 100 mL of 1 M, D-Glucose in DI reservoir, and a 25 cm2cell, under 100 W white LED illumination and oxygen atmosphere. As can be seen from Figure 68, the amount of H2O2increases over 72 h reaction time. Figure 68 shows the ORR activity towards peroxide production, and 4-methoxy benzyl alcohol oxidation, in a flow cell on the same panel where the glucose oxidation took place, back to back experiments, resulted in a -78% conversion of 4-methoxy benzyl alcohol after one week (168 h) of the photocatalytic process. This result signifies a conversion rate of -6.67 mmol h-1m-2over a full week, showing that the panel is still active for different reactions where the cell was only washed with DI in between.

[0584] Example 10: H2 production using HDPE-based photocatalytic panels.

[0585] Materials and methods

[0586] Photocatalytic performance evaluations. hydrogen evolution reaction (HER)

[0587] Photocatalytic HER reactions were carried out in a batch configuration, which means measured in a cylindrical quartz reactor with the dimensions of 1.5 cm inner diameter and height of 6.0 cm (in the cylindrical area), total volume of 29.50 ± 0.25 cm3. First, a Pt cocatalyst was photodeposited on the CN-2-Cl-mlm / HDPE panel via photodeposition technique: 10 + 0.1 mL of 10 vol% EtOH in DI, 10 pL of chloroplatinic acid and either a photocatalytic panel with the dimensions of 1 x 4 cm2or 15 mg powder were added to the reactor, which was then sealed with a rubber septum and washed with high purity Ar(g). Then the reactor was irradiated with a 100 W white LED for 30 minutes. Then the Pt deposited panel or powder (over a Whatman #1 filter paper and a Buchner funnel) were taken out and washed with DI to get rid of residual EtOH. Then the panel or 5.0 ± 0.1 mg powder were reinserted to a clean quartz reactor and 10 + 0.1 mL of 10% EtOH in DI were added, the reactors headspace was washed with high purity Ar(g) and sealed with a rubber septum, and the reactor was irradiated with the white LED for the photocatalytic reaction duration.

[0588] Results

[0589] The hydrogen evolution reaction (HER) was performed in a batch configuration (Figure 65B), 4.0 cm2panel with Pt nanoparticles photo-deposited prior to reaction) with 10 mL of 10% EtOH in DI and 18.5 mL headspace washed with 99.999% argon gas.

[0590] Figure 66C schematic representation of energy diagram of photocatalytic HER in a batch reaction over a Pt@CN-2-Cl-mlm / HDPE panel; (the first 4 h cycle is performed in pure DI, followed by three subsequent 4 h cycles in the presence of 10% v / v EtOH (in DI), serving as the hole scavenger), and the corresponding energy diagram, Figure 66D stability test for HER with 3 cycles of 4 hours each — a total 12 hours of photocatalytic reaction. Figure 66E shows the long term (7 days) photocatalytic H2 production resulted in an activity of 569 mmol m-2of H2.

[0591] In summary, a binder-free methodology was developed to deposit various photocatalysts into different plastic materials. As a case study a polymeric carbon nitride was studied as the photocatalyst and HDPE (recycled or fresh) as an example thermoset plastic serving as the support. In this configuration the CN / HDPE (photocatalyst / support) exhibited stability towards hydrogen peroxide production under visible light illumination. It was also demonstrated photocatalytic hydrogen production at a high rate of ~3 mmol h-1m-2for at least 12 hours using the same panel within situ photo-deposited Pt cocatalyst. The long term H2 production using the same panel produced 569 mmol m-2of H2 after 7 days.

[0592] Example 11: Large-scale CN panels for H2 production via ORR.

[0593] Results

[0594] A binder-free CN panel was prepared and tested it for H2 production in a batch reaction (Figure 69 A). After 24 h, the CN panel produced around 1.1 ol of H2 with rate of 460 oμlm h-1m-2, which further demonstrates the ability to scale such CN / glass panels for H2O2-mediated H2 production approach technology using large-scale photoreactors.

[0595] Furthermore, an analog system over plastic instead of glass: a CN / HDPE (6.7 x 6.7 cm2) panel was also prepared (Figure 69B). A portion of this CN / HDPE panel (6.7 x 2.5 cm2) was tested for H2 production under the identical experimental conditions (20 vol.% MeOH in 100 mL of 0.1 M NaOH, T = 40 °C) to that of CN / glass panel experiment (Figure 69C).

[0596] The CN / HDPE panel produced around 6.5 ol of H2 wiμthm rate of 158 ol h-1m-2.

[0597] The digital image of CN / HDPE panel after 24 h use further demonstrates strong interaction of CN over HDPE substrate under these experimental conditions for longer experiments, which promises to scale this H2O2-mediated H2 production approach technology using large-scale photoreactors equipped with CN / HDPE panels. Example 12: CN / FTO panels for electro / photoelectro-catalysis

[0598] Using the sandwich method schematically shown in Figure 1A, CN panels on a transparent conductive oxide were prepared, specifically, fluorine-doped tin oxide coated glass substrate (FTO) (Figure 70A) and used for electrochemical (EC) and photoelectrochemical (PEC) methanol oxidation to formaldehyde (Figure70B) as a representative oxidation model half-reaction with concurrent HER as the half-reaction on the cathode.

[0599] The CN panel electrode was used for MeOH electrochemical oxidation to HCHO (Figures 71A and 71B).

[0600] Under constant potential at 1.23 V vs. RHE for 1 h, the CN panel electrode produced HCHO, which is confirmed by the UV-vis absorption spectra of HCHO detected using a Nash reagent (Figure 71C). The peak at around 412 nm confirms the formation of HCHO. Furthermore, the CN panel was also used for photoelectrochemical (PEC) MeOH oxidation to HCHO (Figures 71D and 71E). Under a constant potential at 1.23 V vs. RHE for 4 h, the electrode was irradiated using simulated sunlight (1 sun AM 1.5G illuminating the electrode, serving as the photoanode, from the back).

[0601] This CN panel produced HCHO, confirmed by the UV-vis absorption spectra of the produce HCHO, detected colorimetrically using a Nash reagent (Figure 71F).

Claims

CLAIMS:

1. A catalytic panel comprising at least one catalytic material and at least one substrate, wherein said at least one catalytic material is directly associated with said substrate.

2. The catalytic panel according to claim 1 , being essentially free of a binder.

3. The catalytic panel according to claim 1 or 2, wherein said catalytic material is a photocatalytic material and / or a photo-electrocatalytic material.

4. The catalytic panel according to any one of claims 1 to 3, wherein said catalytic material has a thickness of at least about 0.3 pm.

5. The catalytic panel according to claim 4, wherein said catalytic material has a thickness of between about 0.3 pm and about 500 pm.

6. The catalytic panel according to claim 4, wherein said catalytic material has a thickness of between about 0.3 pm and about 50 pm.

7. The catalytic panel according to any one of claims 1 to 6, wherein said catalytic material is characterized by a bandgap (Eg) of at least about 0.8 eV.

8. The catalytic panel according to claim 7, wherein said catalytic material is characterized by a Egof between about 0.8 eV and about 5 eV.

9. The catalytic panel according to any one of claims 1 to 8, wherein said catalytic material is one or more of carbon-based material, a metal and / or metal-containing material, a covalent organic framework material (COFs), a metal-organic framework material (MOFs), a polyoxometalate material (POMs), a nanoparticle or any combination thereof.

10. The catalytic panel according to claim 9, wherein said carbon-based material is one or more of a polymeric CN, a modified CN, graphene, graphene oxide, reduced graphene oxide, graphite, carbon or inorganic nanotube, a carbon dot, a nitrogen-doped carbon or any combination thereof.

11. The catalytic panel according to claim 10, wherein said carbon-based material is polymeric CN or modified CN.

12. The catalytic panel according to claim 9, wherein said metal and / or metal- containing material is a metal oxide.

13. The catalytic panel according to claim 12, wherein said metal oxide is at least one of bismuth oxide (Bi2O3), zinc oxide (ZnO), tungsten trioxide (WO3), titanium dioxide (TiO2), cadmium oxide (CdO), cadmium zinc oxide (CdZnO), bismuth vanadate (BiVO4), copper bismuth vanadate (CuBiVO4), barium titanate (BaTiO3), cerium oxide (CeO2), iridium oxide (IrO2), ruthenium oxide (Ruth), iron oxides (FexOy), zinc iron oxide (ZnFe2O4 -x), tantalum oxide (TaOx), tantalum oxynitride (TaOxNy), indium oxide (In2O3). tin oxide (SnO2), fluorine-doped tin oxide (FTO), aluminum-doped zinc oxide (AZO), tin-doped indium oxide (ITO) or any combinations thereof14. The catalytic panel according to claim 13, wherein said metal oxide is WO3.

15. The catalytic panel according to any one of claims 1 to 14, wherein said substrate is or comprises at least one of glass, metal, metal oxide, doped-metal oxide ceramics, a polymer or any combination thereof.

16. The catalytic panel according to claim 15, wherein said substrate is or comprises a glass material.

17. The catalytic panel according to claim 15, wherein said substrate is or comprises a doped glass material.

18. The catalytic panel according to claim 17, wherein said substrate is or fluorine- doped tin oxide coated glass.

19. The catalytic panel according to claim 15, wherein said substrate is or comprises a polymer.

20. The catalytic panel according to claim 19, wherein said polymer is or comprises a thermoplastic polymer.

21. The catalytic panel according to claim 20, wherein said thermoplastic polymer is or comprises at least one of polyethylene (PE), polypropylene (PP), Polystyrene (PS), Polyvinyl Chloride (PVC), Polyethylene Terephthalate (PET), Polyethylene Terephthalate Glycol (PETG), Poly (methyl methacrylate) (PMMA), Acrylonitrile Butadiene Styrene (ABS), polyvinyl alcohol (PVA), polylactic acid (PLA), polycarbonate(PC), poly ether ester ketone (PEEK),polyetherimide (ULTEM), polyether sulfone (PES), thermoplastic elastomers (TPE), or any combination thereof.

22. The catalytic panel according to claim 21, wherein said thermoplastic polymer is or comprises HDPE.

23. A catalytic panel comprising at least one catalytic material and at least one substrate, wherein said at least one catalytic material is polymeric CN and said substrate is glass and wherein said CN is directly attached on at least one surface of said glass.

24. A catalytic panel comprising at least one catalytic material and at least one substrate, wherein said at least one catalytic material is WO3and said substrate is glass and wherein said WO3is directly attached on at least one surface of said glass.

25. A catalytic panel comprising at least one catalytic material and at least one substrate, wherein said at least one catalytic material is polymeric CN and said substrate is a thermoplastic polymer and wherein said CN is at least partially embedded within said thermoplastic polymer.

26. A catalytic panel comprising at least one catalytic material and at least one substrate, wherein said at least one catalytic material is WO3and said substrate is a thermoplastic polymer and wherein said WO3is at least partially embedded within said thermoplastic polymer.

27. The catalytic panel according to claim 25 or 26, wherein said thermoplastic polymer is HDPE.

28. The catalytic panel according to any one of claims 1 to 27 for use in a photocatalytic reaction or electrocatalytic reaction.

29. The catalytic panel according to any one of claims 1 to 28, for use in a method of production of hydrogen peroxide30. The catalytic panel according to any one of claims 1 to 28, for use in a method of oxidizing at least one organic compound.

31. The catalytic panel according to any one of claims 1 to 28, for use in a method of oxidizing at least one biomass derived product.

32. The catalytic panel according to claim 31, wherein said biomass derived product is derived from a cellulosic biomass, a lignin-rich biomass or oil-based biomass.

33. The catalytic panel according to claim 31, wherein said biomass derived product is HMF.

34. The catalytic panel according to claim 1 to 28, for use in a method of activating a C-H bond of an organic compound.

35. The catalytic panel according to claim 35, wherein said organic compound is one or more of cyclohexane, toluene, xylene, CH4 or any combination thereof.

36. The catalytic panel according to any one of claims 1 to 28, for use in a method of degrading a water pollutant.

37. The catalytic panel according to claim 36, wherein said water pollutant is Rhodamine B (RhB).

38. The catalytic panel according to any one of claims 1 to 28, for use in a method of oxidizing a hydroxyl-containing compound.

39. The catalytic panel according to claim 38, wherein said hydroxyl-containing compound is at least one of an alcohol, a phenol, a carbohydrate, a carboxylic acid or a combination thereof.

40. The catalytic panel according to any one of claims 1 to 28, for use in a method of generating hydrogen.

41. The catalytic panel according to any one of claims 1 to 28, for use in a method of oxidizing a hydroxyl-containing compound and of reducing oxygen.

42. The catalytic panel according to any one of claims 1 to 28, for use as an electrode.

43. An electrode comprising a catalytic panel, wherein said catalytic panel comprises at least one catalytic material and at least one substrate, wherein substrate is a conductive substrate and wherein said at least one catalytic material is directly associated with said substrate.

44. The electrode according to claim 43, wherein said conductive substrate is at least one of fluorine-doped tin oxide coated glass substrate (FTO), transparent conductive oxide (TCO), Indium Tin Oxide (ITO), Aluminum-doped Zinc Oxide (AZO), Gallium-doped Zinc Oxide (GZO), Antimony-doped Tin Oxide (ATO), Antimony-doped Indium Oxide (AIO) or any combination thereof.

45. The electrode according to claim 44, wherein said conductive substrate is FTO.

46. The electrode according to any one of claims 43 to 45, wherein said electrode is for use in an electrochemical oxidation.

47. A particulate matter for use in a method of producing hydrogen, said particulate matter comprises at least one catalytic material.

48. The particulate matter according to claim 47 being in a form of a powder.

49. The particulate matter according to claim 47 or 48, wherein said catalytic material is configured to oxidize a hydroxyl-containing compound and reduce oxygen.

50. The particulate matter according to claim 49, wherein said catalytic material is configured to oxidize said hydroxyl-containing compound to an aldehyde or a carboxylic acid.

51. The particulate matter according to claim 49, wherein said catalytic material is configured to reduce said oxygen to hydrogen peroxide.

52. The particulate matter according to any one of claims 47 to 51, wherein said catalytic material is characterized by having a Valence Band Maximum (VBM) and the Conduction Band Minimum (CBM) that allows the oxidization of a compound containing a hydroxy group to the respective aldehyde and in parallel the reduction of oxygen to hydrogen peroxide.

53. The particulate matter according to claim 52, wherein said catalytic material is by having a VBM that is sufficiently positive to allow oxidization of a compound containing a hydroxy group to the respective aldehyde and a CBM is sufficiently negative to allow reduction of oxygen to hydrogen peroxide.

54. The particulate matter according to any one of claims 47 to 53, wherein said catalytic material is or comprises WO3.

55. The particulate matter according to any one of claims 47 to 53, wherein said catalytic material is polymeric CN.

56. A photoreactor comprises at least one catalytic panel according to any one of claims 1 to 42, the electrode of any one of claims 43 to 46 or the particulate matter according to any one of claims 47 to 55.

57. The photoreactor according to claim 56, being a continuous flow photoreactor or a batch photoreactor.

58. A method for producing hydrogen peroxide, said method comprising exposing a panel to a light source, wherein the panel comprises at least one catalytic material and at least one substrate, and wherein the catalytic material is directly associated to the substrate, to thereby produce hydrogen peroxide.

59. The method according to claim 58, wherein said substrate is glass.

60. A method for producing hydrogen peroxide, said method comprising exposing a panel to a light source, wherein said panel comprises at least one catalytic material and at least one substrate, wherein the at least one substrate is at least one polymer and wherein the catalytic material is at least partially embedded within the polymer, to thereby produce hydrogen peroxide.

61. The method according to any one of claims 58 to 60, wherein said catalytic material is polymeric CN or a modified CN.

62. The method according to claim 60, wherein said polymer is a thermoplastic polymer.

63. The method according to any one of claims 58 to 62, comprising contacting said panel with oxygen.

64. The method according to any one of claims 58 to 63, comprising contacting said panel with at least one hydroxyl-group containing compound.

65. The method according to claim 64, wherein said hydroxyl-group containing compound is ethanol.

66. The method according to claim 64, wherein said hydroxyl-group containing compound is glucose.

67. A method for producing hydrogen peroxide, said method comprising exposing a powder to a light source or natural light, wherein said powder comprises at least onecatalytic material, wherein said catalytic material is configured to oxidize a hydroxyl- containing compound and reduce oxygen to thereby produce hydrogen peroxide.

68. The method of claim 67, wherein said catalytic material is polymeric CN, modified CN or WO3.

69. A method of oxidizing at least one biomass-derived product, said method comprising exposing a panel to a light source, wherein the panel comprises at least one catalytic material and at least one substrate, and wherein the catalytic material is directly associated to the substrate, to thereby oxidizing at least one biomass -derived product.

70. The method according to claim 68, wherein said biomass-derived compound is derived from cellulose, hemi-cellulose, and lignocelluloses.

71. The method according to claim 69, wherein said biomass-derived compound is HMF.

72. A method for water purification, said method comprises exposing a panel to a light source, wherein the panel comprises at least one catalytic material and at least one substrate, and wherein the catalytic material is directly associated to the substrate, to thereby allow water purification.

73. The method according to claim 71 , wherein said water contaminant is an organic contaminant.

74. A method for activating a C-H bond, said method comprises exposing a panel to a light source, wherein the panel comprises at least one catalytic material and at least one substrate, and wherein the catalytic material is directly associated to the substrate, to thereby allow activation of a C-H bond.

75. The method according to claim 74, wherein said organic compound is one or more of cyclohexane, toluene, xylene, CH4 or any combination thereof.

76. A method for producing hydrogen, said method comprises exposing a panel to a light source, wherein the panel comprises at least one catalytic material and at least one substrate, and wherein the catalytic material is directly associated to the substrate, to thereby produce hydrogen.

77. The method according to claim 76, comprising contacting said panel with a cocatalyst.

78. The method according to claim 77, wherein said cocatalyst is deposited on said catalytic material.

79. The method according to claim 77 or 78, wherein said cocatalyst is a HER cocatalyst.

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