Coated substrates, processes for their preparing and uses thereof

Abstract

The present disclosure provides a coated article comprising a substrate selected from a metal, a metal atom-containing material, or a ceramic material, wherein the substrate is at least partially coated with a polymeric carbon nitride (CN) layer. The coated article may comprise a metal chalcogenide, a chalcogen-doped metal oxide, or a chalcogen-containing ceramic material. The present disclosure also provides processes for the preparation of the coated articles and uses thereof.

Description

[0001] COATED SUBSTRATES, PROCESSES FOR THEIR PREPARING AND USES THEREOF

[0002] TECHNOLOGICAL FIELD

[0003] The invention generally concerns coated substrates, processes for their preparation and uses thereof

[0004] BACKGROUND ART

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

[0006] [1] Y. Zeng, Z. Pei, D. Luan, X. W. D. Lou, J. Am. Chem. Soc. 2023, 145, 12333.

[0007] [2] Q. Cao, Y. Gao, J. Pu, A. M. Elshahawy, C. Guan, SmartMat 2024, 5, el 194. 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] The rapidly accelerating development of electric vehicles, mobile technology ,and both off-grid and grid-scale storage solutions, coupled with growing concerns about fossil fuel depletion and environmental degradation, has created an urgent demand for developing high-performance electrochemical energy storage devices that are sustainable, efficient, reliable, and economically viable. [1, 2]

[0010] GENERAL DESCRIPTION In accordance with some aspects, the present disclosure provides a coated article comprising a substrate selected from a metal, a metal atom- containing material, or a ceramic material, wherein the substrate is at least partially coated with a polymeric carbon nitride (CN) layer. In accordance with some other aspects, the present disclosure provides a coated article comprising a substrate, an intermediate layer and an outer layer, wherein the substrate is selected from a metal, a metal atom-containing material, or a ceramic material, wherein the intermediate layer comprises a metal chalcogenide, a chalcogen-doped metal oxide, or a chalcogen-containing ceramic material, wherein the outer layer comprises a polymeric CN, and wherein the intermediate layer is disposed between the substrate and the polymeric CN layer.

[0011] In accordance with some further aspects, the present disclosure provides a process for forming a coated article, the process comprising heating a substrate selected from a metal, a metal atom-containing material, or a ceramic material, wherein the substrate is at least partially coated with a precursor compound comprising at least one carbon atom and at least one nitrogen atom, and wherein the heating converts the precursor into a polymeric CN layer deposited on the substrate.

[0012] In accordance with some further aspects, the present disclosure provides a process for forming a coated article, comprising heating a substrate selected from a metal, a metal atom-containing material, or a ceramic material, wherein the substrate is at least partially coated with a precursor compound comprising at least one carbon atom, at least one nitrogen atom and at least one chalcogenide-containing group, and wherein the heating converts the precursor into (i) a chalcogenide layer disposed on the substrate and (ii) a polymeric CN layer disposed on the intermediate layer.

[0013] In accordance with some further aspects, the present disclosure provides an electrode comprising the coated metal article as described herein.

[0014] In accordance with some further aspects, the present disclosure provides an electrochemical cell comprising an electrode assembly, wherein at least one electrode in the electrode assembly is as described herein.

[0015] BRIEF DESCRIPTION OF THE DRAWINGS

[0016] 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 example only, with reference to the accompanying drawings, in which: Figures 1A-1G show structural analysis of pZnvelectrodes, Figure 1A is a schematic illustration of the synthesized protective layer on a zinc electrode surface in accordance with some examples, Figure IB shows X-ray diffraction (XRD) patterns of the thiourea precursor powder (TU), the resulting coated Zn sheets (Zn-TUso) before heat treatment, pZnso (coated Zn sheets (Zn-TUso) after heat treated, "protected")), and a bare zinc (bZn) sheet, 50 indicates the number of spray cycles on each side of the Zn foil; Figure 1C shows high-angle annular dark field (HAADF) scanning transmission electron microscopy (STEM) and energy dispersive X-ray spectroscopy (EDS) elemental mappings of pZnso Figures 1D-1G are X-ray photoelectron spectroscopy (XPS) spectra of pZnso, Figure ID C is, Figure IE N Is, Figure IF Zn 2p, and Figure 1G S 2p.

[0017] Figures 2A-2D are top-view scanning electron microscopy (SEM) images of electrodes, Figure 2A pZmo electrodes, Figure 2B pZ o electrodes, Figure 2C pZnso electrodes, and Figure 2D pZnso electrodes, 20, 40, 50 or 80 indicates the number of spray cycles on each side of the Zn foil.

[0018] Figures 3A-3D are tilted-view SEM images of electrodes, Figure 3A pZmo electrodes, Figure 3B pZ o electrodes, Figure 3C pZnso electrodes, and Figure 3D pZnso electrodes.

[0019] Figure 4 is an XRD patterns of pZmo, pZn_io, pZnso, and pZnso electrodes.

[0020] Figure 5 is a Fourier-transform infrared spectroscopy (FTIR) spectra of pZmo, pZn_io, pZnso and pZnso electrodes.

[0021] Figures 6A-6C show cross-sectional STEM-EDS analysis of pZnso: Figure 6A shows a line-scan profile of the elements, Figure 6B shows elemental mapping with the line-scan direction indicated by the arrow, Figure 6C shows layer thickness measurement at the area where the elemental analysis (Figure 6A-6B) was measured.

[0022] Figure 7 is a schematic illustration of a coating process of a zinc electrode using melamine vapors in accordance with some examples.

[0023] Figure 8 is a schematic illustration of a coating process of a zinc electrode using thiourea (TU) and melamine (Mel) (Zn-TU-Mel 350 °C) in accordance with some examples. Figures 9A-9C show characterization of Zn-TU-Mel, Figures 9A and 9B are FTIR spectra of Zn-TU before calcination and Zn-TU-Mel at 350 °C, respectively, Figure 9C is a SEM image top view of Zn-TU-Mel 350 °C (after pyrolysis).

[0024] Figure 10 shows XRD patterns of the precursor powders, melamine (Mel) and thiourea (TU), the resulting coated Zn sheets (Zn-TU), Zn-TU-Mel 350 °C, and a bare Zn sheet.

[0025] Figures 11 A and 11B are S 2p and Zn 2p XPS spectra and fitting of coated Zn (Zn- TU-Mel 350 °C), respectively.

[0026] Figures 12A-12D show characterization of Melem (Mlm)-2,4,6-triaminopyrimidine (TAP) / Ni electrode, Figures 12A and 12B are top-view SEM images of Figure 12A shows Mlm-TAP / Ni (inset: digital photograph of the Mlm-TAP / Ni electrode) and Figure 12B shows CN20 / N1 (inset: digital photograph of the CN20 / N1 electrode), Figure 12C is an XRD patterns of Mlm-TAP / Ni (orange) and CNio / Ni electrodes collected from both the coating (red) and Ni (gray) sides, compared to bare Ni foil (black), Figure 12D is a FTIR spectra of the Mlm-TAP / Ni (orange) and CN2o / Ni (in red) electrodes.

[0027] Figures 13A-13D are rate profiles for Zn||Zn symmetric cells at a current density of 5-30 mA cm-2with a capacity of 5 mAh cm-2with different layers of coating (pZnv): Figure 13A 20 layers, Figure 13B 40 layers, Figure 13C 50 layers, and Figure 13D 80 layers.

[0028] Figures 14A-14D show electrochemical evaluation of various Zn electrodes, Figure 14A voltage profiles of pZnvelectrodes with varying number of TU coating layers (x = 20, 40, 50, and 80) at current densities ranging from 5 to 30 mA cm-2, with a fixed areal capacity of 5 mAh cm-2. Comparative studies of non-heated bare Zn (bZn), heated bare Zn (hZn), and pZnso electrodes: Figure 14B rate performance comparison under current densities of 5-30 mA cm-2at a constant capacity of 5 mAh cm-2, Figure 14C hysteresis voltage vs applied current density, and Figure 14D long-term cycling performance of Zn plating / stripping at a high current density of 30 mA cm-2with a fixed areal capacity of 30 mAh cm-2in symmetric Zn||Zn cells. Figure 15 shows the long-term cycling performance of pZnso plating / stripping at a current density of 2 mA cm-2with a fixed areal capacity of 10 mAh cm-2in symmetric Zn||Zn cells.

[0029] Figure 16 long-term cycling performance of melamine-based CN coating of Zn, in a plating / stripping experiment at a current density of 1 mA cm-2with a fixed areal capacity of 1 mAh cm-2in a symmetric Zn||Zn cell.

[0030] Figures 17A and 17B show performance of a complete battery operated in a cyclic manner at a constant capacity of 9 mAh cm-2, with different anodes, Figure 17A the anode is a bare Zn, Figure 17B the anode is a Zn-TU-Mel 350 °C (Zn-TU 60 layers + 1.0 g Mel after 350 °C pyrolysis), Electrolyte: 6 M KOH + 0.2 M Zn(OAc)2, the cathode side - air cathode using NiioPy as a bifunctional air cathode catalyst. Current density: 2 mA cm-2.

[0031] Figure 18 shows a stability profile at 1 mA cm-2cycling measurement of a coated Zn electrode Zn-TU-Mel 350 °C (Zn-TU 60 layers + 1.0 g Mel after 350 °C pyrolysis).

[0032] Figure 19 shows a rate profile of Zn-TU-Mel 350 °C (Zn-TU 60 layers + 1.0 g Mel after 350 °C pyrolysis). This is a symmetrical measurement of two identical Zn electrodes in a symmetric cell. The measurement was conducted at a fixed capacity of 5 mAh cm-2with different current densities in a 6 M KOH + 0.2 M Zn(OAc)2 electrolyte solution.

[0033] Figures 20A-20L show parasitic reaction analysis and Zn-air battery performance, Figure 20A shows quantification of hydrogen gas evolution over time in the anodic compartment (where the electrochemical reaction takes place over a Zn-based electrode) for bZn, hZn, and pZnso electrodes; the linear fit corresponds to a constant (0thorder reaction kinetics) hydrogen production rate, Figures 20B-20G are top-view SEM images of bZn, hZn, and pZnso surfaces before and after 100 h of cycling test, Figures 20H-20J shows comparative XPS spectra of bZn, hZn, and pZnso electrodes before and after 100 h of cycling test, Figure 20K ZnO / Zn or ZnO / ZnS area ratio extracted from the Zn 2ps / 2 region in panels 20H-20J, Figure 20L shows cycling performance of a two-electrode Zn- peroxide battery employing Ni2oPy as a bifunctional air cathode catalyst and pZmo (or bZn) as the anode, tested at a fixed areal capacity of 9 mAh cm-2and current density of 2 mA cm -2. Figure 21 is an exemplary schematic representation of a reversible Zn-air battery illustrating charging and discharging processes, showing as one example a coated Zn electrode (denoted as the anode during discharge).

[0034] Figures 22A-22F are top view SEM images, Figure 22A shows Mlm coated over fluorine-doped tin oxide (FTO) using doctor-blading from paste in ethylene glycol (EG) before Joule heating, Figure 22B shows CN-Mlm electrode (that is the substrateprecursors shown in Figure22A, after a Joule heating procedure), Figure 22C shows CN- Mlm+melamine-TAP (MT) electrode after joule heating, Figure 22D shows bismuthiol- melamine (BM) before Joule heating, Figure 22E shows CN-BM after Joule heating, Figure 22F shows CN-BM+MT electrode after Joule heating, upper-left inset in each panel is a digital image; upper-right inset is either magnified top view or cross-sectional SEM image.

[0035] Figures 23A-23D show characterization of CN electrodes over FTO which underwent thermal polymerization using Joule heating, Figure 23A shows XRD patterns of BM and BM-based CN electrodes over FTO, Figure 23B shows XRD patterns of Mlm and Mlm-based CN electrodes over FTO, Figure 23C shows FTIR spectra of BM and BM- based CN electrodes, Figure 23D shows FTIR spectra of Mlm and Mlm-based CN electrodes, patterns and spectra are vertically offset.

[0036] Figures 24A-24C show characterization of CN electrodes prepared using the doctorblade technique followed by thermal polymerization using Joule heating method, Figure 24 A shows chronoamperometry at 1.23 V vs RHE with CN-Mlm and CN-Mlm+MT as the photoanodes under cycling on / off 1 sun illumination, Figure 24B shows chronoamperometry at 1.23 V vs RHE with CN-BM and CN-BM+MT as the photoanodes under cycling on / off 1 sun illumination, Figure 24C shows UV-vis absorption spectra of the four photoelectrodes before electrochemical activity.

[0037] Figure 25 shows rate profiles for Zn||Zn symmetric cells at a current density of 2-8 mA cm-2with a capacity of 10 mAh cm-2, both electrodes are Zn substrates coated with CN using the Joule heating method. Figure 26 is a scheme of the first step of CN-based electrode preparation using ultrasonically spray-coating a seeding layer or a thin film of precursors on a substrate, followed by doctor-blading a (similar or different) precursor paste.

[0038] Figure 27 is a scheme of a multistep synthetic procedure depositing two distinct CN layers over FTO, initially, a precursor(s) layer is deposited (similar to Figure 26), after a JH step, a yellowish CN layer, which is well-attached to the substrate is formed, subsequently, a second stage is applied where ultrasonic spray gives a seeding layer, on which doctor-bladed precursors paste is deposited, a second JH step yields the final multicomponent electrode, such as a homojunction between two kinds of polymeric carbon nitrides: substrate / CNi / CN2.

[0039] Figures 28A-28C are top view SEM images of Figure 28A CN-melem-melamine (3: 1 molar ratio melem: melamine supramolecular assembly) electrode, Figure 28B a seeding using thiourea (TU) 10 cycles was used before the doctor-blading step with a melem-melamine supramolecular assembly: CN-TUio / melem-melamine electrode, Figure 28C a seeding using urea (U) 10 cycles was used before the doctor-blading step with a melem-melamine supramolecular assembly: CN-Uio / melem-melamine electrode (insets: the corresponding cross-sectional SEM images).

[0040] Figures 29A and 29B show characteristics: Figure 29A XRD patterns of CN-melem (mlm)-melamine over an FTO substrate (top, blue pattern), mlm-melamine powder (middle, red pattern), and a clean FTO substrate (bottom, black pattern), Figure 29B FTIR spectra of mlm-melamine powder (top), and CN-mlm-melamine over a substrate (bottom).

[0041] Figure 30 shows a top-view SEM image of a multistep CN coating, CN-Uioo / mlm- melamine|Uio / mlm-melamine over FTO electrode, inset shows the corresponding cross- sectional SEM image.

[0042] Figures 31A-31D show characterization of substrates, Figure 31A is a digital photographs of Ni foil, glass, and FTO substrates coated with Mlm-TAP (white film) before (left) and after (right) the Joule heating (JH) process transforming into CN-Mlm- TAP, Figure 31B is XRD patterns of Mlm-TAP precursor electrodes prepared on various substrates, Figure 31C is XRD patterns and Figure 31D is FTIR spectra of CNio / Ni (top), CNw / glass (middle), and CNso / FTO (bottom) electrodes. DETAILED DESCRIPTION OF EMBODIMENTS

[0043] The present disclosure is based on findings that engineered protective coatings comprising at least a polymeric carbon nitride (CN) layer that provides enhanced stability to multiple substrates, including, inter alia, a metal, a metal atom- containing material, and ceramic material, under electrochemical conditions. Such coatings (may be denoted as "protective coatings") suppress parasitic side reactions, mitigate dendrite formation, and reduce surface passivation, thereby improving electrode reversibility and extending operational lifetime.

[0044] It was suggested that these CN coated substates may act as catalysts for an oxidation or reduction reaction. In addition, it was suggested that these CN coatings may absorb light and convert it into mobile charge carriers in a photocatalytic, photo-electrocatalytic, or electrocatalytic device.

[0045] Hence, in accordance with some aspects, there is provided a coated article comprising a substrate selected from a metal, a metal atom-containing material, or a ceramic material, wherein the substrate is at least partially coated with a polymeric carbon nitride (CN) layer.

[0046] In some examples, the coated article further comprising a metal chalcogenide, a chalcogen-doped metal oxide, or a chalcogen-containing ceramic material. In some examples, the metal chalcogenide, the chalcogen-doped metal oxide, or the chalcogen- containing ceramic material forms an intermediate layer between the substrate and the polymeric CN layer.

[0047] In some examples, the coated article further comprises an intermediate layer disposed between the substrate and the polymeric CN layer. In some examples, the intermediate layer comprises a metal chalcogenide, a chalcogen-doped metal oxide, or a chalcogen- containing ceramic material.

[0048] In accordance with some aspects, there is provided a coated article comprising a substrate selected from a metal, a metal atom-containing material, or a ceramic material, wherein the substrate is at least partially coated with (i) a metal chalcogenide, a chalcogen- doped metal oxide, or a chalcogen-containing ceramic material and (ii) a polymeric carbon nitride (CN) layer. It should be noted that, when a metal chalcogenide, a chalcogen-doped metal oxide, or a chalcogen-containing ceramic material (at times denoted herein as an intermediate layer) is present, the polymeric CN layer may not be in direct contact with the underlying substrate. Rather, the intermediate layer, such as a metal chalcogenide, a chalcogen-doped metal oxide, or a chalcogen-containing ceramic material, may serve as an interfacial region (at least partially) between the substrate and the CN coating. As shown below, this configuration was observed, for example, in coated zinc substrates, where the CN layer was deposited over a ZnS intermediate layer formed in situ during thermal treatment of a sulfur-containing precursor.

[0049] In accordance with some further aspects, it is provided a coated article comprising a substrate, an intermediate layer and an outer layer, wherein the substrate is selected from a metal, a metal atom-containing material, a ceramic material or any combination thereof, wherein the intermediate layer comprises a metal chalcogenide, a chalcogen-doped metal oxide, or a chalcogen-containing ceramic material, wherein the outer layer comprises a polymeric CN, and wherein the intermediate layer is disposed between the substrate and the polymeric CN layer.

[0050] In the following text, when referring to the coated article it is to be understood as also referring to a coated electrode, panels, cells, battery, process and uses, disclosed herein. Thus, whenever providing a feature with reference to the coated article, it is to be understood as defining the same feature with respect to the coated electrodes, panels, cells, battery, process and uses, mutatis mutandis.

[0051] In some examples, the coated article exhibits a binder-free architecture. As used herein, “ binder-free” or “essentially free of a binder” means that the coating contains less than about 1 wt%, preferably less than about 0.5 wt%, of organic binder. In the configurations described herein, the intermediate metal chalcogenide layer (if present) and the polymeric CN outer layer are directly integrated with the substrate without added binders or adhesives. This binder-free architecture exhibits high stability and performance under electrochemical conditions. Advantages of the binder-free architecture include lower interfacial resistance, unhindered cation (e.g., Zn2+) transport, reduced gas trapping and bubble adhesion, improved thermal / chemi cal stability in concentrated alkaline electrolyte, diminished risk of delamination during cycling, and absence of binder degradation products that can catalyze parasitic reactions.

[0052] The substrate may be in different shapes and forms.

[0053] In some examples, the substrate is a flat substrate, a curved substrate, a nanostructured substrate, a porous substrate or any combination thereof.

[0054] In some examples, the substrate is in form of one or more of a slab, a sheet, a foil, a leaf, a plate, a rod, a cylinder, a wire, a powder, a granule, a mesh, a porous structure, or a foam.

[0055] The substrate may be partially or fully coated by the layers described herein, on one or both sides for flat substrates, or on substantially all exposed surfaces for three- dimensional, porous, mesh, foam, particulate, or wire substrates.

[0056] In some examples, the layers together fully encapsulate the metal substrate.

[0057] As shown in the Examples below, specifically, as estimated from image analysis of SEM or XPS, the intermediate layer (when present) and the CN polymeric layer coat (cover) about 30%, at times about 40%, at times about 50%, at times about 60%, at times about 70%, at times about 80%, at times >90% of the substrate surface, providing uniform surface protection.

[0058] In some examples, the metal chalcogenide, the chalcogen-doped metal oxide, or the chalcogen-containing ceramic material and / or the polymeric CN layer is disposed on at least one exposed surface of the substrate.

[0059] In some examples, the metal chalcogenide layer and / or the polymeric CN layer is disposed on substantially all exposed surfaces of the substrate.

[0060] In some examples, the metal chalcogenide, the chalcogen-doped metal oxide, or the chalcogen-containing ceramic material and / or the polymeric CN layer is disposed on a single major surface of the substrate or on both major surfaces, optionally extending over peripheral edges. In some examples, the metal chalcogenide, the chalcogen-doped metal oxide, or the chai cogen-containing ceramic material and / or the polymeric CN layer together fully encapsulate the substrate.

[0061] The metal chalcogenide, the chalcogen-doped metal oxide, or the chalcogen- containing ceramic material (if present) and the polymeric CN layer are at times referred herein as "coating".

[0062] In some examples, the coating is disposed on substantially all exposed internal and external surfaces of a porous, mesh, or foam substrate.

[0063] In some examples, the coating is conformal on a flat or three-dimensional substrate, with an average thickness variation of <50% across the coated surface.

[0064] In some examples as described herein, the substrate may be a metal substrate.

[0065] As used herein, the term “metal substrate ” refers to an article comprising at least one metallic element, in any crystallographic or structural form.

[0066] The metal substrate may be a uniform, compact, dense, or porous material, or a combination of a dense material with voids, holes, or pores, with a thickness ranging from micrometers to millimeters, depending on the form and geometry (e.g., foil, mesh, sheet, pelt, foam, film, rod, wire, or plate).

[0067] The metal substrate may be composed of pure metal, a metal alloy, or a composite material comprising a metallic phase in combination with additional elements.

[0068] In some examples, the metal substrate is or comprises a pure metal.

[0069] As used herein, the term "pure metal" refers to a metal consisting essentially of a single metallic element, optionally containing incidental impurities, dopants, or residual additives typically present in commercially available grades of the metal. Such impurities or additives do not substantially affect the structural, chemical, or electrochemical properties of the metal substrate. In some examples, the pure metal substrate has a metal content of at least 95%, 98%, 99%, or 99.9% by weight of the principal element. In some examples, the metal is one or more of a transition metal, a post-transition metal, an alkaline earth metal, an alkali metal, a rare-earth element, or any combination or alloy thereof.

[0070] In some examples, the metal is selected from Nickel (Ni), Zinc (Zn), Copper (Cu), Iron (Fe), Platinum (Pt), Rhenium (Re), Palladium (Pd), Manganese (Mn), Aluminum (Al), Magnesium (Mg), Calcium (Ca), Titanium (Ti), Cobalt (Co), Silver (Ag), Gold (Au), Iridium (Ir), Cadmium (Cd), Indium (In), Tin (Sn), Tungsten (W), Molybdenum (Mo), Vanadium (V), Lead (Pb), Tantalum (Ta), Zirconium (Zr), Antimony (Sb), Chromium (Cr), or Bismuth (Bi).

[0071] In some examples, the metal is Ni.

[0072] Hence, in accordance with some aspects, it is provided a coated article comprising a substrate, wherein the substrate is or comprises Ni and wherein said Ni substrate is at least partially coated with a polymeric CN layer. In some examples in which the substrate is Ni, the coated article further comprises Ni chalcogenide.

[0073] In accordance with some further aspects, it is provided a coated article comprising a substrate, an intermediate layer and an outer layer, wherein the substrate is or comprises Ni, wherein the intermediate layer comprises a Ni chalcogenide, wherein the outer layer comprises a polymeric CN, and wherein the intermediate Ni chalcogenide layer is disposed between the Ni substrate and the polymeric CN layer.

[0074] In some examples, the metal is selected from Zn, Al, Fe, or Mg.

[0075] In some examples, the metal is Zn.

[0076] In some embodiments, the metal is or comprises Zn. In some embodiments, the metal substrate is a Zn foil.

[0077] Hence, in accordance with some aspects, it is provided a coated article comprising a substrate, wherein the substrate is or comprises Zn and wherein said Zn substrate is at least partially coated with a polymeric CN layer. In some examples in which the substrate is Zn, the coated article further comprises Zn chalcogenide.

[0078] In accordance with some further aspects, it is provided a coated article comprising a substrate, an intermediate layer and an outer layer, wherein the substrate is or comprises Zn, wherein the intermediate layer comprises a Zn chalcogenide, wherein the outer layer comprises a polymeric CN, and wherein the intermediate Zn chalcogenide layer is disposed between the Zn substrate and the polymeric CN layer

[0079] In some examples, the substrate is or comprises a metal atom-containing material.

[0080] As used herein, the term “metal atom-containing material” refers to a material that comprises one or more metal elements in elemental, ionic, or compound form. In some examples, the metal atom-containing material is or comprises one or more of metal alloy, metal oxides, metal hydroxides, metal oxyhydroxides, metal sulfides, metal selenides, metal tellurides, metal nitrides, metal carbides, metal borides, metal phosphides, metal halides, transition-metal perovskites, doped metal oxides, alloys, and combinations thereof.

[0081] In some examples, the metal atom-containing material is a metal alloy.

[0082] In some examples, the metal atom-containing material is a metal composite.

[0083] When two or more metals are present in combination, the substrate is referred to as an alloy (if homogeneous) or a metal composite (if heterogeneous).

[0084] In some examples, the metal is or comprises an alloy metal.

[0085] An alloy metal as used herein refers to a substance made by combining two or more elements, where the primary element is a metal.

[0086] It should be noted that alloys may include non-metallic elements.

[0087] In some examples, the alloys may be steel, carbon steel, stainless steel, copper nickel, iron nickel, molybdenum nickel, tungsten nickel, cobalt nickel phosphide, zinc copper, zinc nickel, zinc bismuth, platinum cobalt, platinum nickel, platinum iron, platinum ruthenium, brass, bronze, multielement alloys (high entropy alloys), and their combinations.

[0088] The alloy may be homogeneous or inhomogeneous and may include one or more non-metallic elements that may modify its physical, chemical, or electrochemical properties. Unless otherwise indicated, the term encompasses solid solutions, intermetallic compounds, and composite metallic materials.

[0089] In some examples, the metal alloy is a homogeneous metal alloy. As used herein, a homogeneous metal alloy refers to an alloy in which the constituent elements are uniformly distributed, forming a single metallic phase or a continuous solid solution without macroscopic segregation.

[0090] In some examples, the metal alloy is an inhomogeneous metal alloy. As used herein, an inhomogeneous metal alloy refers to an alloy comprising two or more distinct metallic phases or compositional regions, which may differ in elemental content, crystalline structure, or physical properties.

[0091] In some examples, the metal atom-containing material is a metal oxide or doped metal oxide.

[0092] Hence, in accordance with some aspects, it is provided a coated article comprising a substrate, wherein the substrate is or comprises a metal oxide or doped metal oxide, and wherein said substrate is at least partially coated with a polymeric CN layer.

[0093] In accordance with some further aspects, it is provided a coated article comprising a substrate, an intermediate layer and an outer layer, wherein the substrate is or comprises a metal oxide or doped metal oxide, wherein the intermediate layer comprises a chalcogenide element, wherein the outer layer comprises a polymeric CN, and wherein the intermediate chalcogenide layer is disposed between the a metal oxide or the doped metal oxide substrate and the polymeric CN layer.

[0094] In some examples, the metal oxide or doped metal oxide is selected from zinc oxide (ZnO), titanium oxide (TiCh), tin oxide (SnCh), indium oxide (ImOi), barium tin oxide (BaSnCh), InGaZnO4, fluorine-doped tin oxide (FTO), indium tin oxide (ITO), aluminum- doped zinc oxide (AZO), cadmium oxide (CdO), gallium oxide (GaiOs), copper-based delafossites (as CuGaOi), zinc-based ferrites (as NiZnFe2O_i) or any combination thereof.

[0095] In some examples, the doped metal oxide is FTO.

[0096] Hence, in accordance with some aspects, it is provided a coated article comprising a substrate, wherein the substrate is or comprises FTO, and wherein said substrate is at least partially coated with a polymeric CN layer.

[0097] In accordance with some further aspects, it is provided a coated article comprising a substrate, an intermediate layer and an outer layer, wherein the substrate is or comprises FTO, wherein the intermediate layer comprises a chalcogenide element, wherein the outer layer comprises a polymeric CN, and wherein the intermediate chalcogenide layer is disposed between the FTO substrate and the polymeric CN layer.

[0098] In some examples, the substrate is or comprises a ceramic material.

[0099] Hence, in accordance with some aspects, it is provided a coated article comprising a substrate, wherein the substrate is or comprises a ceramic material, and wherein said substrate is at least partially coated with a polymeric CN layer.

[0100] In accordance with some further aspects, it is provided a coated article comprising a substrate, an intermediate layer and an outer layer, wherein the substrate is or comprises ceramic material, wherein the intermediate layer comprises a chalcogenide element, wherein the outer layer comprises a polymeric CN, and wherein the intermediate chalcogenide layer is disposed between the ceramic material substrate and the polymeric CN layer.

[0101] As used herein, the term “ceramic material” refers to an inorganic, non-metallic solid material that may be crystalline, polycrystalline, or amorphous. In some examples, the ceramic material is selected from oxides, carbides, nitrides, borides, silicates, and amorphous ceramics such as glass.

[0102] In some examples, the ceramic material is selected from glass, alumina, silica, or zirconia. In some examples, the ceramic material is glass.

[0103] Hence, in accordance with some aspects, it is provided a coated article comprising a substrate, wherein the substrate is or comprises glass, and wherein said substrate is at least partially coated with a polymeric CN layer.

[0104] In accordance with some further aspects, it is provided a coated article comprising a substrate, an intermediate layer and an outer layer, wherein the substrate is or comprises glass, wherein the intermediate layer comprises a chalcogenide element, wherein the outer layer comprises a polymeric CN, and wherein the intermediate chalcogenide layer is disposed between the glass substrate and the polymeric CN layer.

[0105] As described herein, in some examples, the coated article comprises a chalcogenide material / element. As further described herein, in some examples, the chalcogenide material / element forms an intermediate layer in the coated article. In other words, in some examples, the coated article comprises an intermediate layer comprising a chalcogenide material / element.

[0106] As used herein, the term "intermediate layer" refers to a layer disposed between the substrate and the polymeric carbon nitride (CN) layer. It should be noted that, in some examples, the intermediate layer may at least partially overlap or intermix with the outer polymeric CN layer. As used herein, the term “partially overlap or intermix ” refers to a condition in which the intermediate layer and the outer polymeric CN layer are not completely distinct or sharply separated, but instead share a transitional interfacial region in which chemical species, structural features, or both are present from each layer. Such overlap or intermixing may result from (i) diffusion of elements or compounds (for example, sulfur, nitrogen, or carbon species) from one layer into the other during thermal treatment, (ii) partial co-deposition during coating or condensation, or (iii) chemical bonding or physical interpenetration at the interface. In some examples, the overlap or intermixing region forms a gradient or composite zone having combined features of both the intermediate layer (e.g., ZnS) and the outer CN layer, typically extending over a thickness of several tens to hundreds of nanometers.

[0107] In some examples, the intermediate layer has a thickness of between about 0.1 pm and about 800 pm, at times between about 0.1 pm and about 250 pm, at times between about 0.1 pm and about 150 pm, at times between about 0.1 pm and about 75 pm, at times between about 0.1 pm and about 50 pm, at times between about 0.1 pm and about 30 pm, at times between about 0.1 pm and about 10 pm, at times between about 0.1 pm and about 5 pm.

[0108] In some examples, the intermediate layer has a thickness of between about 0.1 pm and about 3 pm. In some examples, the intermediate layer has a thickness of between about 0.2 pm and about 3 pm. In some examples, the intermediate layer has a thickness of between about 0.2 pm and about 1 pm. In some examples, the intermediate layer has a thickness of between about 0.45 pm and about 0.5 pm.

[0109] In some examples, the intermediate layer is or comprises a metal chalcogenide, a chalcogen-doped metal oxide, or a chalcogen-containing ceramic material. At times, the intermediate layer is referred herein as comprising a chalcogenide material / element and should be understood as encompassing a metal chalcogenide, a chalcogen-doped metal oxide, or a chalcogen-containing ceramic material.

[0110] In some examples, the intermediate layer when present, is or comprises a metal chalcogenide.

[0111] In accordance with some aspects, it is provided a coated article comprising a substrate, an intermediate layer and an outer layer, wherein the substrate is selected from a metal, a metal oxide, a ceramic material, or their combination, wherein the intermediate layer comprises a metal chalcogenide, wherein the outer layer comprises a polymeric CN, and wherein the intermediate layer is disposed between the substrate and the polymeric CN layer.

[0112] In accordance with some aspects, it is provided a coated article comprising a substrate, an intermediate layer and an outer layer, wherein the substrate is selected from a metal, wherein the intermediate layer comprises a metal chalcogenide, wherein the outer layer comprises a polymeric CN, and wherein the intermediate layer is disposed between the substrate and the polymeric CN layer.

[0113] As used herein, the term “metal chalcogenide” refers to a compound comprising at least one metal element and at least one chalcogen element. The metal chalcogenide may be represented by MaEt, wherein M is a metal and E is a chalcogenide element / material. In some examples, the ratio between M and E (a:t) is between about 0.01 and about 3.

[0114] In some examples, the metal chalcogenide may be a crystalline material or a combination of crystalline and amorphous materials.

[0115] In some examples, the metal chalcogenide may be stoichiometric or non- stoichiometric, crystalline, amorphous, or mixed-phase, and may coexist with minor amounts of oxides, hydroxides, oxyhydroxides, nitrides, phosphides, borides, or carbides.

[0116] The metal chalcogenide may be stoichiometric or non-stoichiometric, crystalline or amorphous, and may exist as a mixed-phase composite with other oxides or nitrides.

[0117] In some examples, the metal chalcogenide comprises a binary, ternary, quaternary, or doped-metal chalcogenide. A “binary metal chalcogenide” comprises one metal and one chalcogen.

[0118] A “ternary metal chalcogenide” comprises three elements, that is two different metals and one chalcogen or one metal and two chalcogens.

[0119] A “quaternary metal chalcogenide” comprises four different elements, that is one to three different metals and one or more chalcogens.

[0120] A “doped metal chalcogenide” refers to a binary, ternary, or quaternary metal chalcogenide that further comprises a dopant element introduced to modify its properties, such as conductivity, bandgap, catalytic activity, binding energy to chemical adsorbents, or stability.

[0121] The thickness of the metal chalcogenide intermediate layer may vary depending on various factors. In some examples, the intermediate layer has a thickness of between about 0.05 pm and about 500 pm.

[0122] In some examples, the chalcogen element (also denoted herein as chalcogenide) is one or more of oxygen (O), sulfur (S), selenium (Se), tellurium (Te), or any combination thereof.

[0123] In some examples, the metal chalcogenide is one or more of a metal oxide, metal sulfide, a metal selenide, a metal telluride or any combination thereof.

[0124] In some examples, the metal chalcogenide is one or more of a metal sulfide, a metal selenide, a metal telluride or any combination thereof.

[0125] In accordance with some aspects, it is provided a coated article comprising a substrate, a metal sulfide, a metal selenide, a metal telluride or any combination thereof and polymeric CN, wherein the substrate is or comprises a metal.

[0126] In accordance with some aspects, it is provided a coated article comprising a substrate, metal sulfide, a metal selenide, a metal telluride or any combination thereof and polymeric CN, wherein the metal sulfide, a metal selenide, a metal telluride or any combination thereof and the polymeric CN are coating the substrate and wherein the substrate is or comprises a metal. In accordance with some aspects, it is provided a coated article comprising a substrate, an intermediate layer and an outer layer, wherein the substrate is or comprises a metal, wherein the intermediate layer comprises a metal sulfide, a metal selenide, a metal telluride or any combination thereof, wherein the outer layer comprises a polymeric CN, and wherein the intermediate sulfide layer is disposed between the metal substrate and the polymeric CN layer.

[0127] In some examples, the metal is one or more of Ni, Zn, Cu, Fe, Pt, Re, Pd, Mn, Al, Mg, Ca, Ti, Co, Ag, Au, Ir, Cd, In, Sn, W, Mo, V, Pb, Ta, Zr, Sb, Cr, Bi, or any combination thereof.

[0128] In some examples, the metal chalcogenide is a metal sulfide. In some examples, the metal sulfide is of the general formula MVS , wherein M is a metal selected from Ni, Zn, Cu, Fe, Pt, Re, Pd, Mn, Al, Mg, Ca, Ti, Co, Ag, Au, Ir, Cd, In, Sn, W, Mo, V, Pb, Ta, Zr, Sb, Cr or Bi.

[0129] In some examples, the metal sulfide is one or more of ZnS, NiS, NiS2, NisSi, NisS4, NI7S6, N17S10, NI9S8, ZnS, FeS, FeS2, Fei- S, CoS, C0S2, C03S4, MoS2, WS2, TIS2, CmS, PbS, SnS2, InS, I Ss, Sb2S3, Sb2S5, Bi2Ss, Al2Ss, &2S3, MgS, CaS, or any combination thereof.

[0130] In some examples, the metal chalcogenide is a metal selenide. In some examples, the metal selenide is of the general formula MxSey, wherein M is a metal selected from Ni, Zn, Cu, Fe, Pt, Re, Pd, Mn, Al, Mg, Ca, Ti, Co, Ag, Au, Ir, Cd, In, Sn, W, Mo, V, Pb, Ta, Zr, Sb, Cr or Bi.

[0131] In some examples, the metal selenide is ZnSe, NiSe, CoSe, CuSe, FeSe, Fe2Se3, FeSe2Fe3Se4, MoSe2, WSe2, PbSe, SnSe, I Ses, Bi2Se2, AFSes, Cr2Se3, MgSe or any combination thereof.

[0132] In some examples, the metal chalcogenide is a metal telluride. In some examples, the metal telluride is of the general formula M Te , wherein M is a metal selected from Ni, Zn, Cu, Fe, Pt, Re, Pd, Mn, Al, Mg, Ca, Ti, Co, Ag, Au, Ir, Cd, In, Sn, W, Mo, V, Pb, Ta, Zr, Sb, Cr or Bi. In some examples, the metal telluride is ZnTe, CdTe, NiTe, NiTe2, CoTe, FeTe, FeTe2, MoTe2, WTe2, Bi2Te3, Sb2Te3, SnTe, AFTes, MgTe, or any combination thereof.

[0133] In some examples, the metal chalcogenide is zinc sulfide (ZnS). In some examples, the metal chalcogenide is zinc sulfide (ZnS) formed in situ on a zinc metal substrate.

[0134] In accordance with some aspects, it is provided a coated article comprising a substrate, zinc sulfide and polymeric CN, wherein the substrate is or comprises zinc.

[0135] In accordance with some aspects, it is provided a coated article comprising a substrate, zinc sulfide and polymeric CN, wherein the zinc sulfide and the polymeric CN are coating the substrate and wherein the substrate is or comprises zinc.

[0136] In accordance with some aspects, it is provided a coated article comprising a substrate, an intermediate layer and an outer layer, wherein the substrate is or comprises zinc, wherein the intermediate layer comprises zinc sulfide, wherein the outer layer comprises a polymeric CN, and wherein the intermediate zinc sulfide layer is disposed between the zinc substrate and the polymeric CN layer.

[0137] In some examples, the metal chalcogenide is nickel sulfide (NiS).

[0138] In accordance with some aspects, it is provided a coated article comprising a substrate, nickel sulfide and polymeric CN, wherein the substrate is or comprises nickel.

[0139] In accordance with some aspects, it is provided a coated article comprising a substrate, nickel sulfide and polymeric CN, wherein the nickel sulfide and the polymeric CN are coating the substrate and wherein the substrate is or comprises nickel.

[0140] In accordance with some aspects, it is provided a coated article comprising a substrate, nickel sulfide and an outer layer, wherein the substrate is or comprises nickel, and wherein the outer layer comprises a polymeric CN.

[0141] In accordance with some aspects, it is provided a coated article comprising a substrate, an intermediate layer and an outer layer, wherein the substrate is or comprises nickel, wherein the intermediate layer comprises nickel sulfide, wherein the outer layer comprises a polymeric CN, and wherein the intermediate nickel sulfide layer is disposed between the nickel substrate and the polymeric CN layer. In some examples, the coated article comprises a metal chalcogenide, a chalcogen- doped metal oxide, or a chalcogen-containing ceramic material.

[0142] In some examples, the intermediate layer is or comprises a metal chalcogenide, a chalcogen-doped metal oxide, or a chalcogen-containing ceramic material.

[0143] In some examples, the coated article comprises a chalcogen-doped metal oxide.

[0144] In some examples, the intermediate layer when present, is or comprises a chalcogen- doped metal oxide.

[0145] As used herein, the term “chalcogen-doped metal oxide” refers to a metal oxide in which one or more oxygen atoms in the oxide lattice are partially substituted or supplemented by a different chalcogen element.

[0146] In some examples, the coated article comprises a chalcogen-containing ceramic material.

[0147] In some examples, the intermediate layer when present, is or comprises a chalcogen- containing ceramic material.

[0148] As used herein, the term “chalcogen-containing ceramic material” refers to an inorganic, non-metallic, ceramic substrate or layer that includes one or more chalcogen elements within its structure, either as part of the ceramic composition or as a surface- modified component.

[0149] As described herein, the coated metal article comprises polymeric CN material.

[0150] As used herein, the term “polymeric CN material'1'’ refers to a class of nitrogen-rich carbonaceous materials composed predominantly of carbon and nitrogen atoms. The polymeric CN material may be arranged in polymeric networks containing heteroaromatic ring structures.

[0151] In some examples, the CN polymeric layer has C-to-N ratio x / y of between about 0.33 and about 3.0.

[0152] As further described herein, the polymeric CN material is formed in situ from thermal decomposition of a nitrogen- and carbon-containing precursor compound or multiple precursor compounds. The polymeric CN may be semiconducting, with a bandgap of between about 2.0 and about 4.2 eV, at times between about 2.5 and about 2.9 eV, enabling partial electronic conduction while maintaining ion selectivity.

[0153] The polymeric CN layer may comprise linked tri-.s-triazine units, triazine units, poly(heptazine imides), graphitic C3N4, melon 2D polymer (connected tri-.s-triazine units), their mixture, or variations as a result of heteroatom incorporation (P, O, S, Se, Te), structural defects, or incomplete condensation of the polymer.

[0154] In some examples, the polymeric CN layer exhibits a porous or mesoporous structure with an average pore size between about 0.5 and 500 nm (e.g., 2-50 nm for mesopores), or a specific surface area >10 m2g1as measured by nitrogen sorption isotherms.

[0155] In some examples, the polymeric CN material may be in a form of at least partially condensed networks containing one or more of amorphous and crystalline domains.

[0156] In some examples, the polymeric CN material is amorphous, crystalline, porous, dense, or any combination thereof.

[0157] In some examples, the polymeric CN comprises a nitrogen-containing functional group.

[0158] As used herein, the term “nitrogen-containing functional groups” refers to moieties incorporated within the polymeric CN material that contain one or more nitrogen atoms in covalent bonding arrangements.

[0159] In some examples, the nitrogen-containing functional group is one or more of an amino group (-NH2, -NHR, -NIC), an imine group (=NH, C=NR), a cyano group (-C=N), an amidine group (-C(=NH)-NH2), or a tertiary amine (-N-(C)s).

[0160] In some examples, the polymeric CN further comprises at least one heteroatom dopant (X) and / or at least one metal dopant (Md). In some examples, nitrogen in the polymeric CN is incorporated in heteroaromatic ring structures, such as .s-triazine units or heptazine (tri-.s-triazine) units.

[0161] In some examples, the polymeric CN material may be represented by the general formulas CxNyHpOq, CxNyHpOqEr, or CxNyHpOqErXs:Md, E is a chalcogenide atom (e.g. E = S, Se, Te), x, y, p, q, r, s are atomic indices (which may be zero unless otherwise stated), X is a heteroatom dopant and Ma is a metal dopant. For clarity, these empirical compositions refer to the polymeric CN outer layer. The chalcogenide index r denotes a sulfur or selenium or tellurium atom covalently incorporated into the CN network (e.g., residual / doped sulfur originating from the precursor compound) and is independent of the separate metal chalcogenide intermediate layer.

[0162] In some examples, the heteroatom dopant X is selected from B, P, F, Cl, Br, I, O, S, Se, Te, Sb, Si, Bi.

[0163] In some examples, the metal dopant Md is selected from Zn, Mg, Ca, K, Na, Fe, Co, Ni, Cu, Mn, Mo, W, V, Pt, Y, Zr, Sn, In, Cd, Al.

[0164] In some examples, the polymeric CN material represented by CxNYHpOq, CxNyHpOqEr, or CxNyHpOqErXs:Md is characterized by a C:N atomic ratio (x / y) of about 0.3 to about 3.0. In some examples, q > 0 (the CN comprises oxygen) and / or p > 0 (the CN comprises hydrogen).

[0165] In some examples, the polymeric CN layer increases electrode wettability, exhibiting a contact angle < 60° with an alkaline electrolyte.

[0166] The thickness of the polymeric CN outer layer may vary depending on various factors.

[0167] In some examples, the polymeric CN layer has a thickness of between about 0.05 pm and about 500 pm. In some examples, the outer layer has a thickness of between about 0.1 pm and about 400 pm, at times between about 0.1 pm and about 250 pm, at times between about 0.1 pm and about 150 pm, at times between about 0.1 pm and about 75 pm, at times between about 0.1 pm and about 50 pm, at times between about 0.1 pm and about 30 pm, at times between about 0.1 pm and about 10 pm, at times between about 0.1 pm and about 5 pm. In some examples, the outer layer has a thickness of between about 0.2 pm and about 1.5 pm. In some examples, the outer layer has a thickness of between about 0.75 pm and about 2.0 pm. In some examples, the outer layer has a thickness of between about 0.75 pm and about 1.0 pm

[0168] In some examples, the CN layer comprises two or more stacked sub-layers, optionally of differing composition or porosity. In accordance with another aspect, the present disclosure provides a process for forming a coated metal article.

[0169] The process generally comprises heating a substrate that has been at least partially coated with a precursor compound comprising at least one carbon atom and at least one nitrogen atom. During the heating step, the precursor compound undergoes thermal decomposition, thereby generating reactive intermediates that form at least the polymeric CN outer layer disposed above the substrate layer.

[0170] Hence, in accordance with some aspects, the present disclosure provides a process for forming a coated article, the process comprising heating a substrate selected from a metal, a metal atom-containing material, or a ceramic material, wherein the substrate is at least partially coated with a precursor compound comprising at least one carbon atom and at least one nitrogen atom, and wherein the heating converts the precursor compound into a polymeric CN layer deposited on the substrate.

[0171] In some examples in which the precursor compound comprises at least one carbon atom and at least one nitrogen atom and at least one chalcogenide element, the heating converts the precursor compound into a chalcogenide layer and the polymeric CN layer, wherein the chalcogenide layer is an intermediate layer disposed between the substrate and the polymeric CN layer.

[0172] Hence, in accordance with some aspects, the present disclosure provides a process for forming a coated article, comprising heating a substrate selected from a metal, a metal atom-containing material, or a ceramic material, wherein the substrate is at least partially coated with a precursor compound comprising at least one carbon atom, at least one nitrogen atom and at least one chalcogenide-containing group, and wherein said heating converts the precursor into (i) a metal chalcogenide layer disposed on the substrate and / or (ii) a polymeric CN layer disposed on the intermediate layer. In some examples, the heating converts simultaneously the precursor into (i) a metal chalcogenide layer disposed on the substrate and / or (ii) a polymeric CN layer disposed on the intermediate layer

[0173] As described herein, the intermediate layer (when present) and the outer layer may be formed by heating the substrate such that these layers are derived / produced / results from the precursor compound. In other words, the selection of the precursor compound may affect the characteristics (composition, width, etc.) of the layers coating the substrate.

[0174] It should be noted that in accordance with some examples, the process allows the simultaneous formation of the intermediate layer and the CN layer. It should be further noted that the simultaneous formation of the layers is in a binder-free manner.

[0175] In some examples, and as described herein, the metal chalcogenide intermediate layer (when present) may be formed on a metal substrate by a chemical conversion process. In some examples, the chemical conversion process is one or more of oxidation, sulfidation, selenization, or tellurization.

[0176] As described herein, the metal chalcogenide is formed in situ on the metal substrate. Hence, the metal chalcogenide is chemically bonded to the metal substrate surface, forming a binder-free in situ passivation layer that is continuous with the bulk metal.

[0177] In some embodiments, prior to the heating step, the process comprises applying the precursor compound onto the substrate. In some embodiments, prior to the heating step, the process comprises applying the precursor compound onto the substrate to thereby obtain the substrate being at least partially coated with a precursor compound.

[0178] Hence, in accordance with some aspects, the present disclosure provides a process for forming a coated article, the process comprises applying a precursor compound comprising at least one carbon atom and at least one nitrogen atom onto a substrate to obtain at least a coated substrate and heating the coated substrate. As noted above, during the heating step, the precursor undergoes thermal decomposition.

[0179] In some examples, in which the precursor compound comprising one carbon atom and at least one nitrogen atom, the heating allows formation / generation of a polymeric CN layer disposed onto the substrate forming an outer CN layer.

[0180] In some other examples, in which the precursor compound comprising at least one carbon atom and at least one nitrogen atom and at least one chalcogenide-containing group, the forms / heating generates (i) a chalcogenide intermediate layer disposed on the surface of the substrate, and / or (ii) a polymeric CN outer layer disposed above the intermediate layer. In some aspects, it is provided a process for forming a coated article, the process comprising applying a precursor compound onto a substrate and heating the substrate, wherein the precursor compound comprises at least one carbon atom and at least one nitrogen atom, optionally further comprising at least one chalcogen-containing group and wherein the heating converts the precursor into (i) a metal chalcogenide layer and / or (ii) a polymeric carbon nitride (CN) layer.

[0181] Hence, in accordance with some aspects, the present disclosure provides a process for forming a coated article, the process comprises applying a precursor compound comprising at least one carbon atom, at least one nitrogen atom and at least one chalcogenide-containing group onto a substrate to obtain a coated substrate and heating the coated substrate. As noted above, during the heating step, the precursor undergoes thermal decomposition to form / generate the intermediate layer and the outer CN polymeric layer.

[0182] As noted herein, reference to "a coated substrate" encompasses partially or fully coated substrate.

[0183] In some examples, the substrate implemented by the process is or comprises a metal. In some examples the metal employed by the process is selected from Nickel (Ni), Zinc (Zn), Copper (Cu), Iron (Fe), Platinum (Pt), Rhenium (Re), Palladium (Pd), Manganese (Mn), Aluminum (Al), Magnesium (Mg), Calcium (Ca), Titanium (Ti), Cobalt (Co), Silver (Ag), Gold (Au), Iridium (Ir), Cadmium (Cd), Indium (In), Tin (Sn), Tungsten (W), Molybdenum (Mo), Vanadium (V), Lead (Pb), Tantalum (Ta), Zirconium (Zr), Antimony (Sb), Chromium (Cr), or Bismuth (Bi).

[0184] In some examples, the substrate implemented by the process is or comprises zinc (Zn) .

[0185] In some examples, the substrate implemented by the process is or comprises Ni.

[0186] In some examples, the substrate implemented by the process is or comprises a metalcontaining material. In some examples the metal- containing material implemented by the process is a metal oxide. In some examples, the metal oxide is selected from zinc oxide (ZnO), titanium oxide (TiO2), tin oxide (SnCL), indium oxide (In2O3), barium tin oxide (BaSnO3), InGaZnO4, fluorine-doped tin oxide (FTO), indium tin oxide (ITO), aluminum- doped zinc oxide (AZO), cadmium oxide (CdO), gallium oxide (Ga2O3), copper-based delafossites (as CuGaO2), zinc-based ferrites (as NiZnFe2O4) or any combination thereof .

[0187] In some examples, the metal oxide implemented by the process is FTO

[0188] In some examples, the substrate implemented by the process is or comprises a ceramic material. In some examples, the substrate implemented by the process is or comprises a glass.

[0189] As used herein, the step of “applying a precursor compound" refers to depositing, coating, or otherwise placing a layer of a precursor material in contact with at least a portion of the surface of the substrate.

[0190] The precursor compound may be applied in a solution, dispersion, slurry, melt, or solid form, depending on the specific deposition technique. In some examples, the precursor compound is dissolved or suspended in a solvent system (e.g., water, alcohol, organic solvent, or their mixture) to facilitate uniform spreading on the metal surface. The precursor compound medium or the substrate on which deposition occurs may be heated.

[0191] The application of the precursor compound comprises a single step or multiple sequential steps. In other words, the precursor may be applied / deposited onto the substrate either (i) in one continuous operation until a target areal loading is reached (single step), or (ii) in two or more discrete steps. In case of two or more discrete steps, each step may be separated by intermediate drying or intermediate heating procedure.

[0192] Regardless of whether the precursor is applied in a single step or in multiple sequential steps, the application is configured to achieve a suitable coating thickness on the metal substrate. As used herein, a “suitable coating thickness” is a thickness that provides a protective coating (e.g., a continuous chalcogenide intermediate layer directly bonded to the substrate and an ion-permeable polymeric CN outer layer or an ion-permeable polymeric CN outer layer) that suppresses parasitic reactions (e.g., HER, corrosion, ZnO passivation) and mitigates dendrite formation without unduly impeding metal-ion transport.

[0193] In some examples, the precursor compound or any solution comprising the compound may be continuously applied across the substrate until the desired dry precursor mass loading is attained, followed by the thermal treatment as described herein. The single- step approach may be used to obtain a thin, continuous film suitable for forming an intermediate chalcogenide layer and a partially condensed CN outer layer upon heating.

[0194] In some other examples, the precursor compound is applied in multiple sequential steps. In some examples, the precursor compound is applied in at least a single cycle, at times between 2 and 100 cycles, at times between 2 and 80 cycles, at times between 30 and 60 cycles. In some examples, each application step may be followed by a drying step.

[0195] The applied precursor layer may adhere to the substrate by physical adsorption, hydrogen bonding, van der Waals forces, electrostatic interactions, or coordination with surface metal cations.

[0196] The precursor compound may be applied by various deposition or shaping methods, depending on the substrate type and desired coating thickness and may be carried out by any suitable technique.

[0197] In some examples, the process comprises applying the precursor compound by one or more of (i) cold press (pelletilization), (ii) hot press, (iii) doctor-blading, (iv) spin coating, (v) dip coating, (vi) spray coating, (vii) ultrasonic spray coating, (viii) immersion in a hot saturated solution, or (ix) any combination thereof.

[0198] In some examples, the process comprises applying the precursor compound by cold press. Cold press (pelletization) involves compressing the precursor powder at room temperature under mechanical pressure to form a compacted layer or free-standing pellet without thermal input.

[0199] In some examples, the process comprises applying the precursor compound by hot press. Hot press involves applying mechanical pressure at elevated temperature, thereby improving particle fusion, film density, and adhesion to the substrate.

[0200] In some examples, the process comprises applying the precursor compound by doctor-blading. In some examples, the process comprises applying the precursor compound by doctor-blading a paste of the precursor in a hydrogen-bonding solvent. Doctor-blading involves spreading a slurry or paste of the precursor compound across the substrate surface using a blade, rod, wire-wound rod, bar, or spiral bar to achieve a controlled film thickness. In some examples, the process comprises applying the precursor compound by spin coating. Spin coating involves depositing a liquid precursor solution onto the substrate and rotating it at high speed to distribute the coating uniformly by centrifugal force.

[0201] In some examples, the process comprises applying the precursor compound by dip coating. Dip coating involves immersing the substrate into a precursor solution or dispersion and withdrawing it at a controlled rate, forming a uniform layer through solvent evaporation.

[0202] In some examples, the process comprises applying the precursor compound by spray coating. Spray coating involves atomizing the precursor solution into fine droplets that are directed onto the substrate surface to form a continuous layer upon solvent evaporation.

[0203] In some examples, the process comprises applying the precursor compound by ultrasonic spray coating. Ultrasonic spray coating employs an ultrasonic nozzle to generate micrometer-scale droplets from the precursor solution, allowing highly uniform thin-film deposition with precise thickness control.

[0204] In some examples, the process comprises applying the precursor compound by immersion in a hot saturated solution. Immersion in a hot saturated solution involves submerging the substrate in a heated solution of the precursor compound, enabling crystallization or in situ precipitation of the coating material on the substrate surface.

[0205] In accordance with some aspects, the present disclosure provides a process for forming a coated article, the process comprises applying a precursor compound comprising at least one carbon atom and at least one nitrogen atom and optionally and at least one chalcogenide-containing group onto a substrate to obtain at least a coated substrate and heating the coated substrate, wherein the step of applying the precursor compound is by one or more of (i) cold press (pelletilization), (ii) hot press, (iii) doctor-blading, (iv) spin coating, (v) dip coating, (vi) spray coating, (vii) ultrasonic spray coating, (viii) immersion in a hot saturated solution, or (ix) any combination thereof.

[0206] In some examples, the process comprises applying the precursor compound by ultrasonic spraying. In some examples, the process comprises applying the precursor compound by doctor blading.

[0207] It was suggested that the application (casting) step is implemented to create uniform precursor films of variable thickness. Alternatively, it was suggested that the precursor may be applied in a form of a solution. If the solution contains at least one precursor, forming small domains would improve adhesion and may allow deposition on the surface of the sought precursor(s).

[0208] The solution may contain a variable concentration according to the temperature and pressure of choice, possibly achieving saturation or supersaturation. The purpose of the applying / seeding step is to crystallize crystallites / islands / thin film / thick film / conformal coating / partial coating of the precursors, directly before the heating or as an additional step to improve adhesion / growth / crystallization of precursors. The substrate may be dipped / immersed in the solution (manual or automatic ‘dip-coating’ machine) or by placing the substrate under solvothermal and hydrothermal processes (e.g., in an autoclave of increased pressure and elevated temperature to minimize solvent evaporation), enabling the controlled growth of crystalline structures by incorporating essential elements into the precursor materials under specific temperature and pressure conditions.

[0209] The precursor compound comprises at least one carbon atom and at least one nitrogen atom, and may optionally comprise additional elements such as hydrogen, oxygen, sulfur, selenium, or tellurium, fluorine, chlorine, bromine, iodide, phosphorous, boron.

[0210] The precursor compound deposited, mixed, soaked or otherwise participating in the reaction (with the substrate) may be a single molecule, a combination of molecules, a salt, a supramolecular assembly from at least two molecules (serving as the precursor powder), a molecular crystal formed by crystallization of precipitation of at least two molecules. These precursors may be mixed with some “carrier” such a hydrogen-bonding solvent (e.g., alcohols, ethylene glycol) to allow casting or mixing.

[0211] In some examples, the precursor compound is or comprises one or more of guanidine isothiocyanate, thiourea, bismuthiol, urea, ammonium thiocyanate, guanidine thiocyante, triazoles, imidazoles, thioimidazoles, melamine, cyanamide, dicyandiamide, cyanuric acid, melem, oxalic acid, ammonium oxalate, uric acid, barbituric acid, caffeine, phenanthroline, cysteine, homocysteine, taurine, methionine, / V-formylmethionine, diphenyl disulfide, dibenzothiophene, sulfanilamide, penicillin, lipoic acid, trithiocyanuric acid, acetoguanamine, benzoguanamine, thymine, luciferin, diaminopyridine, 2,4,6- triaminopyrimidine (TAP), theobromine, theophylline, 5-propyl-2-thiouracil, uracil, dihydrobenzoic acid, benzenetricarboxylic acid, nicotinic acid, phloroglucinol, trimesic acid, terephthalic acid, L-arginine, glucose, succinimide, sulfur, red phosphorous, boron, phenyl boronic acid, thiophenes, furans, pyrroles, bipyridines, A-sulfenylsuccinimides.

[0212] The various precursor powders and salts either containing metallic elements or only non-metallic elements) may be mixed amongst themselves and treated, dissolved, or exfoliated in the presence of solvents as water, alcohols, ethylene glycol and so forth. The precursor compound may be treated with organic and inorganic bases or acids. Acids may be protic or aprotic: e.g., sulfuric acid (H2SO4), sulfonic acids (e.g., methanesulfonic acid), phosphoric acid (H3PO4), boric acid, ammonia water, HC1, HBr, HI, nitric acid, perchloric acid, oxalic acid, formic acid, acetic acid, propanoic acid. Metal salts or organic compounds may be dissolved in the treating solution, which might include additional chemicals such as sodium or potassium hypochlorite, sodium or potassium pyrophosphate, glutathione, sodium borohydride, hydrazine, sodium or potassium imidazolates, sodium or potassium thioimidazolates, ammonia-borane complex, methylamine, acetonitrile, dimethylsulfoxide (DMSO), formamide, methanol, ethanol, isopropanol, butanol, thiobenzene, dimethylformamide (DMF), furosemide, ethylene glycol, poly(ethylene glycol), propylene glycol, propylene carbonate, 4-aminobenzoic acid (PABA), ammonium dihydrogen phosphate, polyacrylic amide, benzoic acid, benzyl amine, benzyl alcohol, benzene dithiol, dimethylamine, hexamethylenetetramine (HMTA), triethanolamine, moroxydine, diethanolamine, piperidine, pyridine, tetrahydrofuran (THF), A-methyl-2-pyrrolidone (NMP), acetone, H2O2, or any other precursors, as were previously discussed.

[0213] In some examples, the precursor compound is or comprises one or more of thiourea, urea, melamine, cyanamide, dicyandiamide, selenourea, ammonium thiocyanate, guanidine thiocyanate, triazoles, imidazoles, amino acids (e.g., cysteine, taurine, methionine), or mixtures thereof. In some examples, the precursor compound is or comprises one or more of thiourea, bismuthiol, urea, selenourea, isoselenocyanate, ammonium thiocyanate, guanidine thiocyante, triazoles, imidazoles, thioimidazoles, melamine, cyanamide, dicyandiamide, cyanuric acid, melem, oxalic acid, ammonium oxalate, uric acid, barbituric acid, caffeine, phenanthroline, cysteine, homocysteine, selenocysteine, taurine, methionine, N- formylmethionine, diphenyl disulfide, dibenzothiophene, sulfanilamide, penicillin, lipoic acid, trithiocyanuric acid, acetoguanamine, benzoguanamine, thymine, luciferin, diaminopyridine, 2,4,6-triaminopyrimidine (TAP), theobromine, theophylline, guanidineisothiocyanate, 5-propyl-2-thiouracil, uracil, dihydrobenzoic acid, benzenetricarboxylic acid, nicotinic acid, phloroglucinol, trimesic acid, terephthalic acid, L-arginine, glucose.

[0214] In some examples, the precursor compound is selected from thiourea, melamine, melem, 2,4,6-triaminopyrimidine (TAP), bismuthiol, urea, or a supramolecular assembly thereof.

[0215] In some examples, the precursor compound is selected from thiourea, melamine, melem, bismuthiol, or urea.

[0216] In some examples, the precursor compound is or comprises thiourea. In some examples, the precursor compound is or comprises melamine. In some examples, the precursor compound is or comprises thiourea and melamine. In some examples, the precursor compound is a supramolecular assembly.

[0217] As used herein, a supramolecular assembly means a non-covalent aggregate of two or more distinct precursor molecules that associate via one or more reversible interactions. The interactions may be hydrogen bonding, electrostatic interactions / ionic pairing (acidbase salts), it- it stacking, coordination to ions, halogen or chalcogen bonding, host-guest inclusion, or combinations thereof. The assembly may be present in solution or solid state (e.g., co-crystal, adduct, inclusion complex, or salt) and is configured to undergo thermal conversion to yield the polymeric carbon nitride (CN) layer and / or to supply chalcogen species for in-situ formation of a metal chalcogenide intermediate layer. The molar ratio between the reactants of the supramolecular assembly range between about 1:10 (one to ten) and about 10:1 (ten to one) , at times between about 1 : 3 (one to three) and about 3 : 1 (three to one) when two precursor molecules are used; various ratios can be used for more than two components (from 1% to 99%).

[0218] In some examples, the supramolecular assembly is one or more of cyanuric acid- melamine, cyanuric acid-melamine-barbituric acid, cyanuric acid-melamine-caffeine, cyanuric acid-melamine-thymine, cyanuric acid-melamine-benzoguanamine, cyanuric acid-melamine-urea, cyanuric acid-melamine-thiourea, cyanuric acid-melamine-TAP, melamine-TAP, thiour ea-melamine, bismuthiol-melamine, melamine-melem, melem- TAP.

[0219] In some examples, the supramolecular assembly is selected from melamine-TAP (MT), melem-TAP (Mlm-TAP), bismuthiol-melamine (BM), or melem-melamine (Mlm- Mel).

[0220] In some examples, the supramolecular assembly is selected from melamine-TAP, bismuthiol-melamine, or melem-melamine.

[0221] In some examples, the precursor compound is melem-melamine (Mlm-Mel).

[0222] In some examples, the precursor compound is melem-TAP (Mlm-TAP).

[0223] In some examples, the precursor compound is melamine-TAP (MT).

[0224] In some examples, the precursor compound is bismuthiol-melamine (BM).

[0225] The supramolecular assembly can be (i) pre-formed off-substrate by precipitation, solvent evaporation, crystallization, or solvothermal treatment (0-220 °C; 5 min-48 h) in the presence of acids, bases, salts, or hydrogen-bond forming solvents; and / or (ii) formed on the substrate during deposition and heating (including vapor-assisted conversion such as thermal / chemical vapor delivery in proximity to the substrate).

[0226] These precursors serve as sources of nitrogen- and carbon-rich fragments, and one or more of boron, phosphorous, oxygen, sulfur, selenium, or tellurium, during subsequent thermal decomposition, enabling the in situ formation of a metal chalcogenide layer on the substrate and a polymeric carbon nitride outer layer.

[0227] In some examples, the thickness of the applied precursor layer is controlled by adjusting parameters such as precursor concentration, number of deposition cycles, solvent composition, and drying conditions. The precursor may be applied to one or both sides of the substrate, and may fully or partially cover the surface.

[0228] In some examples, the process comprises applying melamine onto a metal and / or a atom-containing material and / or a ceramic substrate.

[0229] In some examples, the process comprises applying thiourea onto a metal and / or a atom-containing material substrate and / or a ceramic substrate.

[0230] In some examples, the process comprises applying melamine and thiourea onto a metal and / or a atom- containing material substrate and / or a ceramic substrate.

[0231] In some examples, the process comprises applying melamine onto a metal substrate. In some examples, the process comprises applying melamine onto a metal substrate by ultrasonic spray coating, spray coating, dip coating.

[0232] In some examples, the process comprises applying melamine onto a zinc substrate. In some examples, the process comprises applying melamine onto a zinc substrate by ultrasonic spray coating, spray coating, dip coating, or by exposure of the substrate to melamine vapor during heating .

[0233] In some examples, the process comprises applying thiourea onto a metal substrate. In some examples, the process comprises applying thiourea onto a metal substrate by ultrasonic spray coating.

[0234] In some examples, the process comprises applying thiourea onto a zinc substrate. In some examples, the process comprises applying thiourea onto a zinc substrate by ultrasonic spray coating .

[0235] In some examples, the process comprises applying thiourea and melamine onto a zinc substrate . In some examples, the process comprises spraying thiourea onto a zinc substrate and placing melamine powder separately in the furnace, such that melamine vapor interacts with the thiourea-derived coating during heating.

[0236] In some examples, the process comprises applying a supramolecular assembly onto a metal substrate. In some examples, the process comprises applying melem-TAP onto a nickel (Ni) substrate . In some examples, the process comprises applying melem-TAP onto a nickel substrate by doctor-blading, spin coating, dip coating, spray coating, or ultrasonic spray coating.

[0237] In some examples, the process comprises applying a pre-formed melem-TAP mixture onto a nickel (Ni) substrate. In some examples, the process comprises applying a pre-formed melem-TAP mixture onto a nickel substrate by doctor-blading, spin coating, dip coating, spray coating, or ultrasonic spray coating.

[0238] In some examples, the process comprises applying a supramolecular assembly onto a metal and / or a atom-containing material substrate and / or a ceramic substrate.

[0239] In some examples, the process comprises applying a melem dispersion onto a FTO substrate. In some examples, the process comprises applying a melem dispersion onto an FTO substrate by doctor-balding, spin coating, dip coating, spray coating, or ultrasonic spray coating .

[0240] In some examples, the process comprises applying a melem-melamine (Mlm-Mel) supramolecular assembly onto an FTO substrate. In some examples, the process comprises applying a melem-melamine (Mlm-Mel) supramolecular assembly onto an FTO substrate by doctor-balding, spin coating, dip coating, spray coating, or ultrasonic spray coating .

[0241] In some examples, the process comprises applying a melamine-TAP (MT) supramolecular assembly onto an FTO substrate. In some examples, the process comprises applying a melamine-TAP (MT) supramolecular assembly onto an FTO substrate and additional deposition of melem (mlm) powder.

[0242] In some examples, the process comprises applying a bismuthiol-melamine (BM) precursor mixture onto an FTO substrate. In some examples, the process comprises applying a bismuthiol-melamine (BM) precursor mixture onto an FTO substrate by spray coating, dip coating, or doctor-blading .

[0243] In some examples, the process comprises applying a bismuthiol-melamine (BM) supramolecular assembly onto an FTO substrate and additional deposition of melaminethiourea (MT) powder. In some examples, the process comprises applying melem-TAP onto a glass substrate. In some examples, the process comprises applying melem-TAP onto a glass substrate by doctor blading, spin coating, or dip coating .

[0244] In some examples, the process comprises applying a melem-melamine supramolecular assembly onto a glass substrate by dip coating or spray coating .

[0245] In some examples, the process comprises applying a powder precursor onto a glass substrate by cold-press or hot-press pelletization.

[0246] As noted above, the process comprises a step of heating.

[0247] Upon heating, the precursor decomposes to release in some examples, chalcogen- bearing species (e.g., H2S from thiourea) that react at the interface to form the metal chalcogenide layer chemically bonded to the substrate; concurrently, carbon-nitrogen fragments condense to a polymeric CN layer that bonds to the intermediate layer.

[0248] The heating protocol transforms the precursors over a substrate or the precursors with the substrate that acts as a reactant into the final material or composite. The achieved activity or performance may stem from the type of material, the morphology, the surface properties, the combination of materials and structure, and the possible achieved phases via the chosen synthetic route. If the material / composite is a semiconductor or contains a semiconductor, it may be a photoactive material. The prepared surfaces or self-standing films / electrodes may improve adsorption / permeability of certain chemical species. Any chemical reaction that one of the constituent materials can perform might be performed using surfaces prepared using the reported method. Such reactions include but are not limited to oxidation and reduction reactions such as water oxidation, alcohol oxidation, amine oxidation, organic aromatic substances oxidation, oxygen reduction to water, oxygen reduction to peroxide (H2O2 or HCh” in alkaline environment), water reduction to hydrogen, oxonium (H3O+) reduction to hydrogen, and other forms of water-splitting and organic transformations.

[0249] The heating may be carried out by any method known in the art. In some examples, the heating is conventional thermal heating in a furnace or oven under inert atmosphere (e.g., tube furnace, muffle furnace). In some examples, the heating is a rapid heating utilizing electrical-current induced Joule heating (JH). In further examples, the heating may comprise microwave-assisted heating, plasma-enhanced heating, rapid light-induced heating, flash heating, or laser-induced heating.

[0250] In cases in which the heat is generated by passing an electric current through a conductive path (such as a carbon cloth strip), generating localized heat due to the inherent electrical resistance of the conductive material. The resulting thermal energy facilitates chemical reactions and phase transformations, allowing for the formation of the sought materials over a substrate.

[0251] It is important to note that the conductive material strip may be put beneath the precursors, above them, both under and above (i.e., ‘sandwich’), with either a direct contact with the precursors or via some sort of separator such as a thin glass slide. The choice of substrate, the placement of the conductive strips, and the selected precursors that react under the influence of the heating treatment are all chosen to achieve the sought product material(s) and configuration. The controlled parameters are: inert or reactive atmosphere (e.g., air, He, CO2, CH4, C2H4, O2, N2, Ar, NH3, H2 in Ar, or H2 in N2) as static atmosphere or under constant flow, pressure (elevated or vacuum), applied current in the conductive strips, conductive strip material identity and morphology, its geometry and thickness, how it is applied — one or both sides of the precursors, touching the precursors or in the presence of an intermediate layer such as a thin glass slide — and the geometric parameters of the precursors to produce the desired material composition and crystalline phases.

[0252] The heating step is conducted within a substrate-dependent thermal window bounded below by the onset of precursor decomposition (for example >180 °C) and bounded above by the lower of (i) 680 °C or (ii) the metal substrate solidus minus 5-150 °C.

[0253] Upon heating, and in examples in which the precursor compound comprises a chalcogenide element, the precursor compound undergoes thermal decomposition, releasing reactive species (e.g., hydrogen sulfide from thiourea) that chemically react with the metal substrate to form a metal chalcogenide intermediate layer directly bonded to the substrate surface. At the same time, carbon-nitrogen fragments condense into a polymeric carbon nitride outer layer, which binds to the intermediate chalcogenide layer. The heating temperature depends on substrate melting / softening temperature, precursor chemistry, and reaction time. In some examples, the heating step is conducted in a single continuous heating operation. In other examples, the heating step is performed as a multi-step heating sequence. In some examples, the heating is performed from room temperature to the desired target temperature. In some examples, the heating sequence involves ramping to the target temperature in stages. In some examples, the target temperature is at least about 350 °C, at times at least about 400 °C, at times at least about 500 °C, and at times at least about 550 °C, at times at least about 650 °C. The heating may be carried out under an inert atmosphere such as nitrogen or argon, or under a controlled reactive atmosphere to tailor the resulting coating composition.

[0254] In some examples, the heating sequence involves heating from room temperature to about 60 °C, followed by further heating to between about 60 °C and about 120 °C and further followed by further heating to between about 350 °C and about 680 °C.

[0255] In some examples, the heating sequence involves heating from room temperature to about 200 °C, followed by further heating to between about 350 °C and about 680 °C.

[0256] In some examples, the heating sequence involves heating from room temperature to about 350 °C.

[0257] In some examples, the heating sequence involves heating from room temperature to about 400 °C. In some examples, the heating sequence involves heating from room temperature to about 500 °C. In some examples, the heating sequence involves heating from room temperature to about 600 °C.

[0258] In some examples, in which the metal substrate is Zn, the heating temperature is about 350 °C in N2 to yield an in situ ZnS interlayer and a partially condensed CN outer layer.

[0259] In some embodiments, the heating step may be performed in the presence of a second precursor compound. The second precursor may undergo melting, evaporation, or sublimation during the heating, thereby contributing additional elements or dopants into the coating. In some examples, the second precursor compound is melamine. Through selection of precursor, deposition technique, and heating profile, the process enables controlled formation of a binder-free ZnS / CN coating or analogous metal chalcogenide / polymeric carbon nitride (possibly with heteroatoms) bilayer on the surface of a metallic substrate.

[0260] In accordance with some aspects, the present disclosure provides a process for forming a coated article, the process comprising heating a substrate selected from a metal, a metal atom-containing material, or a ceramic material, wherein the substrate is at least partially coated with thiourea, and wherein the heating converts thiourea into ZnS layer and a polymeric CN layer.

[0261] In accordance with some other aspects, the present disclosure provides a process for forming a coated article, comprising heating a substrate selected from a metal, a metal atom-containing material, or a ceramic material, wherein the substrate is at least partially coated with thiourea, and wherein said heating converts thiourea into (i) a ZnS layer disposed on the substrate and / or (ii) a polymeric CN layer disposed on the ZnS layer.

[0262] In accordance with some other aspects, the present disclosure provides a process for forming a coated article, comprising heating a Zn substrate, wherein the substrate is at least partially coated with thiourea, and wherein said heating converts thiourea into (i) a ZnS layer disposed on the Zn substrate and / or (ii) a polymeric CN layer disposed on the ZnS layer.

[0263] In accordance with some aspects, the present disclosure provides a process for forming a coated article, the process comprises applying thiourea onto a substrate to obtain at least a coated substrate and heating the coated substrate.

[0264] Hence, in accordance with some aspects, the present disclosure provides a process for forming a coated article, the process comprising heating a substrate selected from a metal, a metal atom-containing material, or a ceramic material, wherein the substrate is at least partially coated with melamine, and wherein the heating converts melamine into a polymeric CN layer deposited on the substrate. In accordance with some aspects, the present disclosure provides a process for forming a coated article, the process comprises applying melamine onto a substrate to obtain at least a coated substrate and heating the coated substrate.

[0265] In some examples, the precursor compound is or comprises thiourea and melamine.

[0266] Hence, in accordance with some aspects, the present disclosure provides a process for forming a coated article, the process comprising heating a substrate selected from a metal, a metal atom-containing material, or a ceramic material, wherein the substrate is at least partially coated with thiourea and melamine.

[0267] In accordance with some aspects, the present disclosure provides a process for forming a coated article, the process comprises applying thiourea and melamine onto a substrate to obtain at least a coated substrate and heating the coated substrate.

[0268] Hence, in accordance with some aspects, the present disclosure provides a process for forming a coated article, the process comprising heating a substrate selected from a metal, a metal atom-containing material, or a ceramic material, wherein the substrate is at least partially coated with at least one supramolecular assembly.

[0269] In accordance with some aspects, the present disclosure provides a process for forming a coated article, the process comprises applying at least one supramolecular assembly onto a substrate to obtain at least a coated substrate and heating the coated substrate.

[0270] In some examples, the at least one supramolecular assembly is selected from melamine-TAP (MT), melem-TAP (Mlm-TAP), bismuthiol-melamine (BM), or melem- melamine (Mlm-Mel). In some examples, the supramolecular assembly is selected from melamine-TAP, bismuthiol-melamine, or melem-melamine. In some examples, the precursor compound is melem-melamine (Mlm-Mel). In some examples, the precursor compound is melem-TAP (Mlm-TAP). In some examples, the precursor compound is melamine-TAP (MT). In some examples, the precursor compound is bismuthiol-melamine (BM).

[0271] In some examples, the substrate is or comprises zinc (Zn). In some examples, the process comprises applying melamine onto a zinc substrate. In some examples, the process comprises applying melamine onto a zinc substrate by ultrasonic spray coating, spray coating, dip coating, or by exposure of the substrate to melamine vapor during heating. In some examples, the process comprises thermal heating a Zn substrate that is at least partially coated with melamine. In some examples, the process comprises applying melamine onto a zinc substrate by ultrasonic spray coating, spray coating, dip coating, and thermal heating the Zn substrate that is at least partially coated with melamine. In some examples, the heating converts the melamine into a polymeric carbon nitride (CN) layer deposited on the Zn substrate.

[0272] In some examples, the process comprises applying thiourea onto a zinc substrate. In some examples, the process comprises applying thiourea onto a zinc substrate by ultrasonic spray coating. In some examples, the process comprises thermal heating a Zn substrate that is at least partially coated with thiourea. In some examples, the heating of the Zn substrate is thermal heating. In some examples, the process comprises applying thiourea onto a zinc substrate by ultrasonic spray coating, and thermal heating the Zn substrate that is at least partially coated with thiourea. In some examples, the thermal heating of the Zn substrate that is at least partially coated with thiourea is in a tube furnace under nitrogen atmosphere at 350 °C for about two hours, resulting in ZnS formation and partial polymerization of carbon nitride. In some examples, the heating converts the thiourea into (i) a ZnS intermediate layer disposed on the Zn substrate and (ii) a polymeric CN layer disposed above the ZnS layer. As noted herein, the heating simultaneously forms the ZnS intermediate layer and the polymeric CN layer.

[0273] In some examples, the process comprises applying thiourea and melamine onto a zinc substrate. In some examples, the process comprises spraying thiourea onto a zinc substrate and placing melamine powder separately in the furnace, such that melamine vapor interacts with the thiourea-derived coating during heating. In some examples, the process comprises thermal heating a Zn substrate that is at least partially coated with thiourea and melamine. In some examples, the heating of the Zn substrate is thermal heating. In some examples, the process comprises spraying thiourea onto a zinc substrate and placing melamine powder separately in the furnace, and thermal heating the Zn substrate that is at least partially coated with thiourea and melamine. In some examples, the thermal heating of the Zn substrate that is at least partially coated with thiourea and melamine is in a tube furnace enabling vapor-phase co-condensation of melamine and thiourea.

[0274] In some examples, the substrate is Ni.

[0275] In some examples, the process comprises applying melem-TAP onto a nickel (Ni) substrate. In some examples, the process comprises applying melem-TAP onto a nickel substrate by doctor-blading, spin coating, dip coating, spray coating, or ultrasonic spray coating. In some examples, the process comprises heating a Ni substrate at least partially coated with melem-TAP. In some examples, the heating of the Ni substrate is electrical- current-induced Joule heating (JH).

[0276] In some examples, the process comprises applying melem-TAP onto a nickel substrate by doctor blading, spin coating, dip coating, ultrasonic spray coating, or spray coating and heating the Ni substrate by electrical-current-induced Joule heating (JH). In some examples, the heating converts the melem-TAP into a polymeric CN layer deposited on the Ni substrate. In some examples, the process comprises applying a pre-formed melem-TAP mixture onto a nickel (Ni) substrate. In some examples, the process comprises applying a pre-formed melem-TAP mixture onto a nickel substrate by doctor-blading, spin coating, dip coating, spray coating, or ultrasonic spray coating. In some examples, the process comprises heating a Ni substrate at least partially coated with a melem-TAP mixture. In some examples, the heating is by Joule heating (JH).

[0277] In some examples, the process comprises applying a pre-formed melem-TAP mixture onto a nickel substrate by doctor-balding, spin coating, dip coating, spray coating, or ultrasonic spray coating and Joule heating (JH) the Ni substrate at least partially coated with a melem-TAP mixture. In some examples, the heating is by Joule heating (JH), facilitating rapid polymerization and condensation of melem-TAP into CN.

[0278] In some examples, the process comprises applying a melem-TAP mixture onto a nickel substrate by doctor-balding, spin coating, dip coating, spray coating, or ultrasonic spray coating and Joule heating (JH) the Ni substrate at least partially coated with a melem- TAP mixture. In some examples, the process comprises applying a melem dispersion onto a FTO substrate. In some examples, the process comprises applying a melem dispersion onto an FTO substrate by doctor-balding, spin coating, dip coating, spray coating, or ultrasonic spray coating. In some examples, the process comprising thermal heating an FTO substrate that is at least partially coated with melem. In some examples, the process comprises applying a melem dispersion onto an FTO substrate by doctor-balding, spin coating, dip coating, spray coating, or ultrasonic spray coating and thermal heating the FTO substrate that is at least partially coated with melem. In some examples, the heating converts the melem into a polymeric CN film deposited on the FTO substrate.

[0279] In some examples, the heating is thermal heating. In some examples, the thermal hearing is in a tube furnace under nitrogen atmosphere at 350-550 °C for about one to four hours.

[0280] In some examples, the heating is Joule heating. In some examples, the Joule heating converts the melem into a polymeric CN film deposited on the FTO substrate in less than ten minutes.

[0281] In some examples, the process comprises applying a melem-melamine (Mlm-Mel) supramolecular assembly onto an FTO substrate. In some examples, the process comprises applying a melem-melamine (Mlm-Mel) supramolecular assembly onto an FTO substrate by doctor-balding, spin coating, dip coating, spray coating, or ultrasonic spray coating. In some examples, the process comprises heating an FTO substrate that is at least partially coated with the melem-melamine assembly. In some examples, the process comprises applying a melem-melamine (Mlm-Mel) supramolecular assembly onto an FTO substrate and heating the FTO substrate that is at least partially coated with the melem-melamine assembly. In some examples, the heating converts the assembly into an ordered polymeric CN layer disposed on the FTO. In some examples, the heating the FTO substrate that is at least partially coated with the melem-melamine assembly is thermal heating. In some examples, the thermal heating in a tube furnace under nitrogen atmosphere at approximately 350 °C for two to three hours. In some examples, the heating the FTO substrate that is at least partially coated with the melem-melamine assembly is Joule heating. In some examples, the Joule heating is under an inert atmosphere for less than ten minutes.

[0282] In some examples, the process comprises applying a melamine-TAP (MT) supramolecular assembly onto an FTO substrate. In some examples, the process comprises applying a melamine-TAP (MT) supramolecular assembly onto an FTO substrate and additional deposition of melem (mlm) powder. In some examples, the process comprises applying a melamine-TAP supramolecular assembly onto an FTO substrate by doctor blading, dip coating, or spray coating. In some examples, the process comprises heating an FTO substrate that is at least partially coated with melamine-TAP.

[0283] In some examples, the process comprises applying a melamine-TAP supramolecular assembly onto an FTO substrate by doctor blading, dip coating, or spray coating and heating the FTO substrate that is at least partially coated with melamine-TAP, wherein the heating is electrical-current-induced Joule heating (JH).

[0284] In some examples, the heating converts the melamine-TAP into a polymeric CN layer deposited on the FTO substrate. In some examples, the heating is electrical-current- induced Joule heating (JH).

[0285] In some examples, the process comprises applying a bismuthiol-melamine (BM) precursor mixture onto an FTO substrate. In some examples, the process comprises applying a bismuthiol-melamine (BM) precursor mixture onto an FTO substrate by spray coating, dip coating, or doctor-blading. In some examples, the process comprises heating an FTO substrate at least partially coated with bismuthiol-melamine.

[0286] In some examples, the heating is electrical-current-induced Joule heating (JH). In some examples, the heating converts the BM precursor into a polymeric CN layer deposited on the FTO substrate. In some examples, the heating may additionally induce formation of a metal chalcogenide phase at the substrate interface.

[0287] In some examples, the process comprises applying a bismuthiol-melamine (BM) precursor mixture onto an FTO substrate by spray coating, dip coating, or doctor-blading and heating the FTO substrate at least partially coated with bismuthiol-melamine, wherein the heating is electrical-current-induced Joule heating (JH).

[0288] In some examples, the process comprises applying a bismuthiol-melamine (BM) supramolecular assembly onto an FTO substrate and additional deposition of melaminethiourea (MT) powder.

[0289] In some examples, the process comprising JH a FTO substrate, wherein the FTO substrate is at least partially coated with at least one precursor compound, wherein the at least one precursor compound is one or more of a melem-TAP, melamine-TAP (MT), bismuthiol-TAP (BM), melamine-TAP (MT), melem. The JH heating converts at least one precursor compound onto a polymeric CN layer deposited on the FTO substrate. In some examples, the process comprising applying at least one precursor compound onto a FTO substrate, wherein the at least one precursor compound is one or more of a melem-TAP, melamine-TAP (MT), bismuthiol-TAP (BM), melamine-TAP (MT) or melem.

[0290] In some examples, the process comprising applying at least one precursor compound onto a FTO substrate and JH the FTO substrate, wherein the at least one precursor compound is one or more of a melem-TAP, melamine-TAP (MT), bismuthiol-TAP (BM), melamine-TAP (MT), melem.

[0291] In some examples, the process comprises applying melem-TAP onto a glass substrate. In some examples, the process comprises applying melem-TAP onto a glass substrate by doctor blading, spin coating, or dip coating. In some examples, the process comprises Joule heating a glass substrate at least partially coated with melem-TAP.

[0292] In some examples, the process comprises applying melem-TAP onto a glass substrate by spin coating or dip coating and Joule heating the glass substrate at least partially coated with melem-TAP. In some examples, the heating converts the melem- TAP into a polymeric CN layer deposited on the glass substrate. In some examples, the heating is electrical-current-induced Joule heating (JH).

[0293] In some examples, the process comprises applying a melem-melamine supramolecular assembly onto a glass substrate by dip coating or spray coating. In some examples, the process comprises thermal heating a glass substrate at least partially coated with the melem-melamine assembly. In some examples, the process comprises applying melem-melamine onto a glass substrate by spin coating or dip coating and thermal heating the glass substrate at least partially coated with the melem-melamine assembly.

[0294] In some examples, the heating converts the assembly into a polymeric CN layer deposited on the glass.

[0295] In some examples, the heating is thermal heating in a tube furnace under nitrogen atmosphere at approximately 350 °C.

[0296] In some examples, the process comprises applying a powder precursor onto a glass substrate by cold-press or hot-press pelletization.

[0297] In some examples, the process further comprises pre-treating the metal substrate prior to applying the precursor compound. Pretreatment may include one or more of mechanical polishing, plasma cleaning, chemical cleaning with acid or acid / K-Ch, rinsing with water or organic solvents, ultrasonic cleaning, and controlled drying. Such pretreatment improves adhesion and uniformity of the subsequently formed coating.

[0298] The present disclosure provides, in accordance with some aspects, a coated metal article obtained by the process described herein.

[0299] The present disclosure provides, in accordance with some aspects, a coated metal article obtainable by the process described herein.

[0300] As shown herein, the coated metal articles were successfully used as electrodes in electrochemical cells, including symmetric Zn||Zn cells, rechargeable Zn-air and Zn- peroxide batteries, and hydrogen evolution studies.

[0301] Hence, the coated metal article described herein may be used as an electrode in an electrochemical cell. In some aspects, the present disclosure provides the coated article described herein for use as an electrode. In some other aspects, the present disclosure provides the coated article described herein for use in a method of generating hydrogen.

[0302] Accordingly, in accordance with some other aspects, the present disclosure provides an electrode comprising the coated article as described herein. As shown in the Examples below, the electrode was characterized by one or more of (i) suppresses parasitic hydrogen evolution, (ii) reduces dendrite formation and growth and (iii) reduce metal corrosion.

[0303] Further and as shown below, the electrode maintains at least 90% round-trip energy efficiency after 500 hours, at times after 1000 hours, at times after 1100 hours of cycling.

[0304] In some examples, the electrode operates for at least 1000 hours in an alkaline electrochemical cell without dendrite-induced short circuit.

[0305] These unique features suggest the ability of the novel electrode to function as an anode in an electrochemical cell.

[0306] Hence, the present disclosure provides an electrochemical cell comprising an electrode assembly, wherein at least one electrode is a coated metal article as described herein. In some examples, the coated metal article serves as the anode.

[0307] An electrochemical cell as used herein refers to a device capable of either generating electrical energy from chemical reactions occurring in it or using electrical energy supplied to it to facilitate chemical reactions. Cells that generate an electric current from chemical reactions are termed “Galvanic cells” or “Voltaic cells”, whereas cells which cause chemical reactions to occur when an electric current is passed through them are termed “electrolytic cells”. Electrochemical cells can be undivided (non-partitioned), or divided that is made up of two half-cells, each consisting of an electrode, which is dipped in an electrolyte. The same electrolyte can be used for both half cells. These half cells are connected by a salt bridge, which affords ionic contact between the two halves but prevents them from mixing with each other. An example of a salt bridge is a filter paper which is dipped in a potassium nitrate or sodium chloride solution. One of the half cells loses electrons due to an oxidation reaction at the surface of the immersed anode and the other gains electrons in a reduction process at the surface of the immersed cathode.

[0308] The tendency of a reactive electrode, which is in contact with an electrolyte, or a chemical species on an inert electrode to lose or gain electrons, is referred to as the “halfcell potential”. Values of these potentials are used for predicting the overall cell potential. Generally, all potentials are measured vs. a reference electrode (an electrode of a known potential relative to the reversible hydrogen electrode (RHE) scale).

[0309] The cell may be primary or secondary (rechargeable); aqueous or non-aqueous; and may be selected from a battery, a fuel cell, or an electrolysis cell.

[0310] In some examples, the electrochemical cell is a primary cell. A primary cell as used herein refers to electrochemical cell in which irreversible reactions occur such that once the reactants are consumed for the generation of electrical energy, the cell stops producing an electric current. In these cells, the anode will typically be negative, or oxidation reaction will occur on its surface, and the cathode will typically be positive, or reduction reaction will occur on its surface. An example of a primary cell is a galvanic cell. Primary cells are basically use-and-throw galvanic cells.

[0311] In some examples, the electrochemical cell is a secondary cell. A secondary cell as used herein refers to a “rechargeable cell”, is an electrochemical cell, featuring reversible reactions, such as electrolytic cells.

[0312] In accordance with yet some other aspects, it is provided an electrochemical cell comprising an electrode assembly comprising an anode and a cathode wherein the anode is as described herein.

[0313] In some embodiments which may be considered as aspects of the present disclosure, the electrochemical cell is a flow-cell.

[0314] A flow -cell as used herein refers to an electrochemical device that converts chemical energy into electrical energy or vice versa through an electrochemical reaction in a flow apparatus.

[0315] In some embodiments which may be considered as aspects of the present disclosure, the electrochemical cell is used as a battery device.

[0316] A battery device as used herein refers to an electrochemical device consisting of one or more electrochemical cells, that converts chemical energy contained within its active materials directly into electric energy by means of an electrochemical oxidation-reduction (redox) reaction, in which electrons are transferred from one material to another via an electric circuit. In a collection of two or more of electrochemical cells, the cells may be connected in series, parallel, or both, depending on the desired output voltage and capacity. Connecting the cathode of one cell to the anode of the next cell is connecting in series. The voltages of all cells are added together. Connecting the cathode of one cell to the cathode of the other, and the anode to the anode is connecting them in parallel. The voltage stays the same, but the currents are added together. In principle, any galvanic cell could be used as a battery. Batteries are broadly classified into two categories: primary batteries can only be used once, and when the material in the cathode or anode is consumed or no longer able to be used in the reaction, the battery is unable to produce electricity. When these batteries are completely discharged, they become useless and must be discarded. Secondary batteries, also referred to as “rechargeable batteries”, can be charged and reused for many charging-discharging cycles. The electrochemical reactions that take place inside these batteries are usually reversible in nature. When discharging, the reactants combine to form products, resulting in the flow of electricity. When charging, the flow of electrons into the battery facilitates the reverse reaction, in which the products react to form the reactants.

[0317] In some examples, the battery is a rechargeable battery.

[0318] In some examples, the battery is a metal-air battery. Hence, in accordance with some aspects, it is provided a metal-air battery. Rechargeable metal-air batteries utilize oxygen from the air as one of the reactants and is typically constructed from two electrodes, such that during discharge, one half cell, the anode, constitutes the following oxidation reaction: M — M”++ ne~, while the other half cell, the cathode, constitutes the following reduction reaction: O2 + 2H2O + 4e“ — 4OH“ and during charge, the metal cations are reduced to their metallic state (metal electrode), while in the other half-cell oxygen is generated via oxygen evolution reaction (OER) as follows: 4OH“ — 2H2O + O2 + 4e“.

[0319] In some examples, the battery is a metal-peroxide battery.

[0320] Hence, in accordance with some aspects, the present disclosure provides a rechargeable metal-peroxide battery.

[0321] The rechargeable metal-peroxide battery described herein provides a unique configuration as it comprises an anode as described herein that may exhibit reversible activity for the reduction and for the oxidation of oxygen via generation and oxidation of peroxide. In some examples, the metal-air battery is a zinc-air battery (ZAB) or a rechargeable zinc-air battery (RZAB).

[0322] The present disclosure also provides a metal-air battery comprising an electrode assembly, wherein at least one electrode in the electrode assembly is as described herein. In some examples, the coated metal article serves as the anode of the electrochemical cell.

[0323] A schematic representation of a reversible Zn-air battery illustrating charging and discharging processes with the coated Zn electrode (denoted as the anode during discharge) is shown in Figure 21.

[0324] In other examples, the electrochemical cell is a zinc-ion, zinc-sulfur, zinc-halogen, or zinc-nickel battery.

[0325] In some examples, the electrochemical cell is a metal-peroxide battery (MPB).

[0326] In some examples, the electrochemical cell is a metal-peroxide battery where oxygen is selectively reduced to HCh (peroxide) and HO2 and / or HO2 (peroxide) and HO2 is oxidized to oxygen.

[0327] Rechargeable metal-air batteries utilize oxygen from the air as one of the reactants and is typically constructed from two electrodes, such that during discharge, one half cell, the anode, constitutes the following oxidation reaction: M — M”++ ne~, while the other half cell, the cathode, constitutes the following reduction reaction: O2 + 2H2O + 4e“ — 4OH- and during charge, the metal cations are reduced to their metallic state (metal electrode), while in the other half-cell oxygen is generated via oxygen evolution reaction (OER) as follows: 40 H" 2H2O + O2 + 4e . In this overall reaction, 4 electrons are involved in the reduction of oxygen and in the transfer of charge.

[0328] It should be noted that a rechargeable metal-peroxide battery described herein may comprises a working electrode that may exhibit reversible activity for the reduction and for the oxidation of oxygen via generation and oxidation of peroxide.

[0329] In some examples, the metal-peroxide battery constitutes during discharge reduction of oxygen to H2O2 or HCh- during ORR and during charge oxidation of H2O2 or HO2- to oxygen during POR. In some examples, the reduction of oxygen to H2O2 or HO2- involves a two-electron transfer. In other examples, the electrochemical cell is a zinc-peroxide battery (ZPB).

[0330] The electrolyte may be alkaline, for example 6 M KOH optionally containing Zn2+salts (e.g., 0.2 M Zn(OAc)2), and the cell may include ion-exchange or anion-conducting membranes, porous separators, and bifunctional air cathodes (e.g., Ni-based catalysts facilitating ORR / POR). In some embodiments, the coated anode and the electrolyte are selected to provide uniform Zn2+flux, suppressed hydrogen evolution, and limited ZnO passivation during cycling.

[0331] Electrochemical cells of the present disclosure may further be characterized by one or more of the following features:

[0332] • round-trip energy efficiency of at least about 90% for more than 500 hours at times after 1000 hours, at times after 1100 hours of cycling;

[0333] • operational stability of at least about 1000 hours, at least about 2000 hours in an alkaline electrochemical cell without dendrite- induced short circuit;

[0334] • suppression of hydrogen evolution reaction (HER) relative to an uncoated metal electrode;

[0335] • suppression of irreversible ZnO passivation layer formation;

[0336] • improved electrolyte wettability, characterized by a contact angle < about 60° in alkaline electrolyte.

[0337] A method of operating an electrochemical cell is provided, comprises providing a cell in which the anode is a coated metal article as described herein and cycling the cell under galvanostatic or potentiostatic control, thereby achieving uniform metal deposition / stripping, reduced HER, and extended cycle life relative to a cell employing an uncoated metal anode.

[0338] In accordance with some other aspects, the present disclosure provides use of a coated article described herein as an electrode in an electrochemical cell or a photoelectrochemical cell. In some other aspects, it is provided use of a coated article as described herein for suppressing hydrogen evolution reaction (HER) during operation of an alkaline electrochemical cell.

[0339] In some other aspects, it is provided use of a coated article as described herein for reducing dendrite formation during metal plating and stripping. In some other aspects, it is provided use of a coated article as described herein for inhibiting irreversible ZnO passivation layer formation.

[0340] Further, it is provided use of a coated article as described herein for improving roundtrip energy efficiency in a rechargeable metal-air or metal-peroxide battery.

[0341] Additionally, it is provided use of a coated article as a photocatalytic material in a photoreactor.

[0342] 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. In some embodiments, the term "about" refers to ± 10%.

[0343] As used herein, the forms "a", "an" and "the" include singular as well as plural references unless the context clearly dictates otherwise.

[0344] It is appreciated that certain features of the invention, which are, for clarity, described in the context of separate embodiments, may also be provided in combination in a single embodiment. Conversely, various features of the invention, which are, for brevity, described in the context of a single embodiment, may also be provided separately or in any suitable sub combination or as suitable in any other described embodiment of the invention. Certain features described in the context of various embodiments are not to be considered essential features of those embodiments unless the embodiment is inoperative without those elements.

[0345] 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 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. The phrases “in another embodiment” or any refence made to embodiment as used herein do not necessarily refer to different embodiment, although it may. Thus, various embodiments of the invention can be combined (from the same or from different aspects) without departing from the scope of the invention.

[0346] Various embodiments and aspects of the present invention as delineated herein above and as claimed in the claims section below find experimental support in the following examples.

[0347] Disclosed and described, it is to be understood that this invention is not limited to the particular examples, coated substrate, electrodes, cell, systems, battery, disclosed herein as such coated substrate, cell, systems, battery, may vary somewhat. It is also 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.

[0348] 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.

[0349] SOME NON-LIMITING EXAMPLES

[0350] Materials

[0351] All materials were purchased from the indicated commercial manufacturers and used as received unless stated otherwise. Thiourea (thiocarbamide, TU, > 99%) from Thermo Scientific; Melamine (99%, sometimes abbreviated as Mel) from Sigma- Aldrich; potassium hydroxide pellets (KOH, AR grade) from Macron Fine Chemicals; zinc acetate dihydrate for analysis (Zn(OAc)2 2H2O, ACS grade) from Merck; Nafion (5 wt. % in lower aliphatic alcohols and water, contains 15-20% water Sigma- Aldrich); hydrogen peroxide (H2O2, 30 wt%, Sigma- Aldrich); Ethanol (EtOH, technical grade 99%) from Bio-Lab, Israel; Anionic exchange membrane (Fumasep FAS-30, Fuel cell store, USA); 2-Propanol (IP A, HPLC & spectroscopy grade) from Loba chemie, India; Carbon paper (TGP-H-60, Toray, Fuel cell store, USA); Zn foil 0.62 mm from Thermo Scientific ; Alconox detergent powder; Deionized water (DI water, 18.2 mQ cm resistivity at 25 °C, purified using a Merck Millipore Direct-Q3 system) was used for all aqueous solutions), Triethanolamine (TEO A, 99%) from G1 entham, UK, Fluorine-doped tin oxide (FTO)-coated glass (12-14 Q sq-1) - from Xop Glass. Before use, the FTO was cut into rectangular pieces (1.3 cm x 2.5 cm) and sonicated with an aqueous detergent solution (Alconox, 1% m / v), ethanol, and acetone successively, for 15 min each, then dried in an air oven at 60 °C

[0352] Characterization details

[0353] X-ray diffraction (XRD). XRD patterns were obtained using a PANalytical Empyrean diffractometer (equipped with an X'celerator position-sensitive detector) with a scanning time of ~15 min for a 26 range of 5-80 using Cu Ka radiation (A = 1.54178 A, 40 kV, 30 mA).

[0354] X-ray photoelectron spectroscopy (XPS). The chemical states of key elements were analyzed from XPS measurements conducted on 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 900 pm. Depth profiles were obtained following Ar ion gun etching for -150 s, with a sputtering rate of 0.07 nm s-1. All the binding energies in the XPS spectra were calibrated using the C is peak at 284.8, and a pass energy of 20.0 eV.

[0355] Scanning electron microscopy (SEM). The surface morphology was analyzed by SEM using an FEI Verios 460L high-resolution FEG-source microscope using through-lens (TLD) or Everhart- Thornley (ETD) detectors at Uo = 3.50 kV and probe current of 25 pA.

[0356] Gas chromatography (GC). Hydrogen evolution quantification was analyzed by gas chromatography (Agilent 7820 GC system equipped with CP-molecular sieve 5A and PoraPLOT Q columns coupled to a thermal conductivity detector, TCD). Contact angle measurement. The contact angle between bZn, hZn and the Zn-TUso electrodes with the electrolyte was measured by using contact angle system OCA (DataPhysics Instruments).

[0357] Focused ion beam (FIB). Cross-sectional sample for scanning transmission electron microscopy of the ZnS / CN coating layer was prepared in a FEI Helios G4 UC system (Thermo Fisher Scientific) using a gallium focused ion beam.

[0358] Scanning transmission electron microscopy (STEM). For STEM analysis, a Spectra 200 (Thermo Fisher Scientific) scanning transmission electron microscope (STEM) equipped with a probe Cs-corrector (S-CORR) and a cold-FEG electron source at an accelerating voltage of 200 kV was used. The images were recorded in STEM mode with high-angle annular dark field (HAADF) detector with a semi-convergence angle of 30 mrad, a probe current of typically 250 pA and a collection angle range of 57.0-200.0 mrad. The energy dispersive X-ray spectroscopy (EDS) spectra were collected utilizing a Super-X (Thermo Fisher Scientific) four-segment silicon drift detector (SDD). The images and the EDS spectra were processed with Thermo Fisher Scientific Velox software (version 3.15).

[0359] Electrochemical Methods

[0360] For Zn || Zn symmetric cells, identical pairs of electrodes (bZn, hZn, and pZnv, x = 20, 40, 50, 80 layers) were assembled into the single chamber cell. The electrolyte employed in these symmetrical configurations consisted of 6 M KOH + 0.20 M Zn(OAc)2. Electrochemical measurements utilized a two-electrode arrangement connected to either an Ivium Vertex 20V or Biologic VMP 300 potentiostat with a carbon holder as a connector to the fabricated electrodes.

[0361] The electrochemical performance of both symmetrical cells and complete battery systems was evaluated through chronopotentiometry analysis. This involved subjecting the cells to galvanostatic charge-discharge protocols versus (vs) Zn2+ / Zn across a range of current densities (5-30 mA cm-2) while recording potential variations as a function of time. This methodology provided a comprehensive assessment of cycling efficiency, rate capability, and long-term operational stability under various electrochemical conditions. Hydrogen evolution analysis was performed in an H-cell with bZn, hZn, or pZnso anodes and NiioPy catalyst air cathodes. Each half cell contained 70 mL of electrolyte (6 M KOH + 0.20 M Zn(OAc)2 anodic; 6 M KOH cathodic). Hydrogen evolution was measured at regular intervals of ~15 min during cycling (at charging process) at 2 mA cm-2and areal capacity of 5 mAh cm-2.

[0362] All experimental evaluations were conducted under controlled laboratory conditions at 25 °C.

[0363] Materials preparation

[0364] Preparation and cleaning of zinc substrates

[0365] For all zinc substrates a preliminary cleaning procedure was used. The commercial zinc foil surface preparation involved manual removal of the native oxide layer using sandpaper P320, followed by sequential cleaning in 1% m / v Alconox detergent solution (5-60 min), followed by rinsing with ethanol, followed by 30 minutes of ultrasonication in IPA.

[0366] Preparation of pZn electrodes

[0367] A thiourea precursor solution (125 g L-1) was prepared by dissolving 10 g of thiourea in 80 mL of deionized water and thoroughly mixing for 15 minutes until complete solubilization occurred. The prepared solution was then deposited onto zinc foil substrates (1.5 cm2for small electrodes and 5 cm2for large electrodes) maintained at 50 °C utilizing a Sono-Tek ExactaCoat ultrasonic spray system. The experimental parameters include varying the number of spray cycles on each side of the Zn foils (20, 40, 50, or 80), shaping air pressure of the spray (0.5 psi), dwell time between spray cycles (10 s), and distance between the spray nozzle and the Zn electrode (4.0 cm). To this end, the Zn foils with the sprayed thiourea layers is placed in a glass tube (16 mm diameter 100 mm length). The pre-thermal treatment electrodes are noted as Zn-TEh (x = 20, 40, 50, or 80). The glass tube is covered with aluminum foil and heated to 350 °C in a tube furnace under N2 atmosphere (99.999%) according to the following program:

[0368] 1. From room temperature to 60 °C (initial heating); step duration: 1 min.

[0369] 2. From 60 °C to 120 °C; step duration: 60 min (heating rate of 1 °C min-1).

[0370] 3. From 120 °C to 350 °C; step duration: 46 min (heating rate of 5 °C min-1). 4. At the target temperature of 350 °C, dwell time of 2 hours.

[0371] 5. Cool down naturally from 350 °C to room temperature

[0372] Preparation of hZn Electrodes

[0373] Following the cleaning procedure, these electrodes were directly placed in 16 mm glass tubes, capped with an aluminum foil, and processed in a tube furnace under N2 atmosphere (99.999%) using the same heating program as applied for the pZn electrodes.

[0374] Zn coating with a protective CN layer

[0375] Zn foil substrates were cut to a geometric area of 1.5 cm2, after which the surface was prepared by manually removing the native oxide layer using P320 sandpaper, rinsing with ethanol, followed by 0.5-1.0 h ultrasonication in IPA. The scheme of the procedure is depicted in Figure 1. The treated electrodes were then placed into a 16 mm glass tube, with 0.5 g melamine powder positioned at its bottom. To this end, the tube was covered with aluminum foil and heated to 350 °C in a tube furnace under a 99.999% N2 atmosphere utilizing the following heating program:

[0376] 1. From room temperature to 60 °C (initial heating); step duration: 1 min.

[0377] 2. From 60 °C to 120 °C; step duration: 60 min (heating rate of 1 °C min-1).

[0378] 3. From 120 °C to 350 °C; step duration: 46 min (heating rate of 5°C min-1).

[0379] 4. At the target temperature of 350 °C, dwell time of 2 hours.

[0380] 5. Cool down naturally from 350 °C to room temperature.

[0381] Preparation of pZnxelectrodes with thiourea in the presence of melamine

[0382] A solution of 10 g thiourea in 80 mL water is used to deposit via ultrasonic spraying a thiourea layer for polymerization and condensation at 350 °C in the presence of melamine (Mel) vapor. To this end, the Zn electrode with the sprayed thiourea layer is placed into a 16 mm glass tube, at the bottom of which melamine powder is placed. The amount of melamine powder used depends on the electrode size:

[0383] 1. For smaller electrodes (ca. 1.5 cm x 1 cm), 1.0 g of melamine powder is used.

[0384] 2. For larger electrodes (ca. 2.5 cm x 2 cm), 2.0 g of melamine powder is used. The glass tube is covered with aluminum foil and heated to 350 °C in a tube furnace under

[0385] N2 atmosphere (99.999%) according to the following program:

[0386] 6. From room temperature to 60 °C (initial heating); step duration: 1 min.

[0387] 7. From 60 °C to 120 °C; step duration: 60 min (heating rate of 1 °C min-1).

[0388] 8. From 120 °C to 350 °C; step duration: 46 min (heating rate of 5 °C min-1).

[0389] 9. At the target temperature of 350 °C, dwell time of 2 hours.

[0390] 10. Cool down naturally from 350 °C to room temperature.

[0391] Then, a cleaning procedure is used: the native oxide layer on top of the commercial Zn sheet is manually polished using P320 sandpaper. Subsequently, the electrodes are soaked in a 1% m / v ALCONOX solution for 5-60 min, followed by rinsing with water and ethanol. The electrodes are then washed with IP A, followed by 30-60 min ultrasonication in IPA.

[0392] Thiourea coating: A sulfur-containing precursor compound, thiourea, is deposited on the Zn using the following procedure:

[0393] 10 g thiourea is dissolved in 80 mL water to prepare the thiourea solution. This solution is then used as the feed to an ultrasonic spraying of a thiourea layer (e.g., utilizing 60 coating cycles), marked as Zn-TU.

[0394] Thermal polymerization in the presence of melamine:

[0395] For polymerization and condensation at 350 °C in the presence of melamine (Mel) vapor, the thiourea-coated Zn foil (Zn-TU) is placed into a 16 mm glass tube, at the bottom of which melamine powder is placed as schematically depicted in Figure 1A. The amount of melamine powder used depends on the electrode size:

[0396] 1. For the smaller 1.5 cm2electrodes, 1.0 g of melamine powder is used.

[0397] 2. For the larger 5.0 cm2electrodes, 2.0 g of melamine powder is used.

[0398] Then, the tube was covered (closed, not sealed) with an aluminum foil and heated to 350 °C in a tube furnace under a 99.999% N2 atmosphere utilizing the following heating program: 11. From room temperature to 60 °C (initial heating); step duration: 1 min.

[0399] 12. From 60 °C to 120 °C; step duration: 60 min (heating rate of 1 °C min-1).

[0400] 13. From 120 °C to 350 °C; step duration: 46 min (heating rate of 5 °C min-1).

[0401] 14. At the target temperature of 350 °C, dwell time of 2 hours.

[0402] 15. Cool down naturally from 350 °C to room temperature.

[0403] Melem synthesis'. 2,5,8-triamino-tri-s-triazine (melem, sometimes abbreviated as mlm or Mlm) was synthesized by thermal condensation of melamine at 400 °C for 12 hours in a ceramic crucible with a lid using a muffle furnace (under air), heated from room temperature to 400 °C at a heating rate of 5 °C min-1. After the reaction, the oven was allowed to naturally cool down to room temperature, the obtained bulk was then ground into fine powder using mortar and pestle.

[0404] Supramolecular assembly preparation: A melem-melamine (Mlm-Mel) supramolecular assembly with a molar ratio of 3: 1 was prepared by mixing suitable quantities of melem and melamine in 50 mL polypropylene centrifuge tubes containing 34 mL of DI water and 16 mL of ethylene glycol (EG). The mixture was then shaken for 12 h. The resulting solid was collected by centrifugation and then dried in a vacuum oven for 24 h at about 60 °C for further use. Melem-TAP, where TAP stands for 2,4,6- triaminopyrimidine, melamine-TAP (MT), and bismuthiol-melamine (BM), where bismuthiol stands for l,3,4-thiadiazole-2,5-dithiol, supramolecular assemblies were prepared in a similar procedure to the melem-melamine one, only replacing the source molecules.

[0405] Deposition: single precursor powder (e.g., melamine, melem) or supramolecular aggregate powders (e.g., Mlm-Mel, MT, or BM) in a hydrogen-bonding solvent, ethylene glycol, was mixed using a planetary centrifugal mixer (‘Thinky mixer’) to obtain a viscous paste. This paste was applied on a substrate (glass, FTO, Zn sheet, or Ni sheet) to obtain a conformal coating of CN precursors.

[0406] CN coating fabrication and characterization: thermal treatment via the JH method is applied to get the CN coating layer over the substrate. Specifically, the substrate with the coated precursors can be placed on a single sheet or strip of a conductive carbon cloth and placed under inert environment where a current is applied (4-10 A range equivalent to temperatures in the 300-750 °C range) and heats the precursors turning them into the CN. To improve this in-situ thermal polymerization or to form homojunctions another precursor powder may be placed.

[0407] Supramolecular-films preparation (“Doctor-Bladins ”)

[0408] Supramolecular films were prepared by mixing 1.0 g of Mlm-TAP with 1.0 mL of EG using a planetary centrifugal mixer ARV-310LED (‘Thinky mixer’), using a single 10 mm zirconia ball at 1500 rpm for 5 min. The resulting paste was spread over the substrates’ surface (e.g., Ni foil, FTO, and glass) using the doctor-blade coating technique (a single layer of 3M Scotch Magic Tape 810 serving as the barrier to determine the paste height during deposition). Then, the films were dried on a heating plate on a heating plate at 50 °C for 2 h.

[0409] CN-films formation via Joule heating (JH)

[0410] Mlm-TAP-coated substrates were individually positioned film-side up on a flexible carbon cloth strip. The exposed edges of the strip were then connected to a Volteq (USA) HY6020EX power supply using alligator clips. Subsequently, a constant current of 6.0-10 A was applied for 10 to 120 seconds to induce JH under an inert atmosphere. Upon turning off the electrical power, CN coating was achieved. For example, CN2o / Ni, CNw / glass, and CNso / FTO, denotes reactions of 20, 40, and 80 s, respectively, over Ni, glass, or FTO.

[0411] Hydrogen evolution quantification

[0412] The evolved FE gas in the anodic compartment was quantified at regular time intervals using a gas chromatograph (Agilent 7820 GC system) during Zn reversibility cycling process, performed at a current density of 2 mA cm-2and areal capacity of 5 mAh cm-2. The measurements were conducted in a custom-designed two-compartment cell (each compartment 100 mL; separated by an anion-exchange membrane (Fumasep FAS-30, Fuel Cell Store, USA), cut into ~3 cm2. The cathodic compartment was filled with 6 M KOH aqueous solution, while the anodic compartment contained 6 M KOH with 0.20 M Zn(OAc)2. To monitor hydrogen evolution, 200 pL gas samples were periodically extracted every ~15 minutes from the 30 mL headspace above the 70 mL electrolyte in the anodic compartment, using a Pressure-Lok precision analytical syringe (A- 2 Luer lock, Vici). Prior to each measurement, the electrolyte in the anodic compartment was purged with Ar

[0413] Rechargeable Zn— peroxide batery (RZPB) assembly and study a. Preparation of zinc anodes

[0414] The pZnso anode was prepared using the same coating method described earlier. For the bare Zn electrode, surface cleaning and mechanical polishing were carried out as previously detailed. b. Preparation of air cathodes

[0415] 70 mg of catalyst was dispersed in 2 mL of isopropanol (IP A) with 70 pL of 5 wt% Nafion solution. The mixture was ultrasonicated for 3 h to form a homogeneous ink, which was then drop-cast onto carbon paper with area of 2 x 2.5 cm2and left to dry for approximately one hour. The resulting areal catalyst loading was approximately 1 mg cm-2. The rechargeable Zn-peroxide battery was tested in home-built electrochemical cells. A two-electrode configuration was used by pairing NiioPy loaded on carbon paper as the cathode electrode (area = 5 cm2, catalyst loading 1 mg cm-2) in 6 M KOH in the first compartment and a Zn foil anode (bZn or pZnso) in 6 M KOH with 0.20 M Zn(OAc)2 dissolved in the anodic compartment. Both compartments were filled with approximately 15 mL of electrolyte and separated by a Fumasep (FAS- 30) anionic exchange membrane to facilitate ionic transport. During discharge and charge cycling, either high-purity oxygen (>99.6%) or ambient air was continuously supplied to the cathode side to ensure oxygen saturation. All materials for the battery were purchased from Fuel Cell Store (USA). c. Calculation of round-trip energy efficiency (RRTE) of rechargeable Zn-peroxide battery

[0416] The energy efficiency was calculated as RTEE =Vdlschargex 100%

[0417] ^charge Example 1: Preparation and characterization of metal-based electrodes

[0418] Example 1A: Preparation and characterization of pZn electrodes

[0419] The synthetic route of protected zinc electrodes is illustrated in Figure 1 A and was adapted from a previously developed procedure in our group for the deposition of polymeric carbon nitride over transparent conductive electrodes using ultrasonic spray coating of CN precursors. Briefly, uniform seeding layers of thiourea precursor were deposited on zinc foil substrates heated to 50 °C over a hot plate, while controlling layer thickness through altering the number of spray cycles (20, 40, 50, or 80) of an aqueous TU solution (125 g L-1). Subsequently, the precursor-coated zinc foils (Zn-TUv, where x stands for the number of spray cycles) underwent thermal treatment at 350 °C under N2 atmosphere for four hours, resulting in protected zinc electrodes (pZnv). The synthesis process involves the thermal decomposition of thiourea, with significant IBS release occurring in the range of 180-220 °C, providing sulfide intermediates, which react with Zn for ZnS formation. Thiourea is particularly suitable as a sulfur precursor due to its gradual decomposition at relatively low temperatures , which enables controlled film formation below the Zn melting point (419.5 °C). In addition to serving as a sulfur source, thiourea decomposes at 350 °C to release carbon and nitrogen species, leading to partial carbon nitride polymerization, as the reaction temperature is limited due to the Zn melting point. This yields nitrogen-rich carbonaceous structures with C-N bonds and zincophilic sites such as .s-triazine rings, - NIB, and -CN groups, referred to herein as CN. CN’s nitrogen-containing moieties serve as coordination sites to Zn2+(aq), thus regulating nucleation, suppressing parasitic reactions, and forming robust layers that protect the Zn’s surface during cycling. To verify the formation of ZnS / CN coatings and optimize the layer thickness, structural and chemical analyses were performed using scanning electron microscopy (SEM), X-ray diffraction (XRD), and Fourier-transform infrared (FTIR) spectroscopy on all coated samples (pZmo- 80).

[0420] A thicker protective coating can enhance physical isolation between the zinc surface and the electrolyte, improving protection against corrosion and parasitic reactions. However, excessive thickness may hinder Zn2+ion transport and reduce electrochemical efficiency. In contrast, thinner coatings allow for easier ion migration but may lack sufficient surface coverage, limiting their effectiveness in suppressing side reactions and dendrite growth. Thus, identifying an appropriate coating thickness is crucial to balance ionic conductivity with interfacial stability. Top-view and tilted-view SEM analysis was conducted to examine surface morphology and coating thickness across all samples. Topview SEM images (Figures 2A-2D) revealed differences in surface features and coating coverage. The pZnso electrode formed a dense layer that may be too thick, potentially impeding Zn2+ion migration at the electrode interface. In contrast, the pZmo, pZ o, and pZnso electrodes exhibited thinner surface layers that visibly cover the zinc surface. Tilted- view images (Figures 3A-3D) provide a clear visible demonstration of the expected trend, where an increasing coating thickness results from a larger number of deposited layers (x), while providing further insight into the overall interface quality. The pZmo electrode displayed a very thin and non-uniform coating with weak adhesion to the zinc substrate, indicating insufficient coverage and limited protection. The pZnso, on the other hand, exhibits an excessively thick coating with inconsistent thickness across the interface, suggesting poor uniformity and potential interfacial instability. The pZn_io and pZnso electrodes, however, show better uniformity and continuous coatings of moderate thickness, which may provide a favorable balance between ionic conductivity and surface protection.

[0421] XRD analysis (Figure 4) reveals distinct ZnS peaks at -28.8° and -47.9°, corresponding to the (111) and (220) planes of cubic ZnS (i.e., a zinc blende phase), exclusively in the pZnso and pZnso samples, with the most intense reflections observed for pZnso. These peaks are consistent with the diffraction pattern of cubic ZnS, as reported in ICDD PDF card No. 00-065-0723. Additionally, a broad peak centered at ~27.6°, which corresponds to the interlayer stacking (002) plane, appeared only in the pZnso sample, indicating successful partial CN polymerization. Based on these distinct features, further XRD analysis was performed on pZnso to examine the structural transformation of the precursor layer. Zn-TUso exhibits identical XRD patterns (Figure IB) to bare Zn (bZn) and TU powder, indicating the successful and intact coating of thiourea before thermal treatment. Upon thermal treatment, the emergence of the previously identified ZnS and CN signals supports the transformation of the thiourea layer into a ZnS / CN composite over the Zn substrate. FTIR analysis of all coated electrodes (Figure 5) confirms this analysis by revealing bands corresponding to cyano (-CN) and amino (-NEE) groups, as well as characteristic vibrations of .s-triazine structures, indicative of at least partial condensation into a polymeric carbon nitride for all samples.

[0422] Out of all the protected electrodes, pZnso exhibited the best electrochemical performance.

[0423] As such, it was chosen for further characterization. To accurately evaluate the thickness and structure of the coated electrode, a focused ion beam (FIB) was used to prepare a cross-sectional lamella of the pZnso sample for high-resolution scanning transmission electron microscopy (STEM) and energy-dispersive X-ray spectroscopy (EDS) analysis. The STEM image with overlaid EDS mapping (Figure 1c) reveals a clear three-layer structure: metallic Zn at the bottom, an intermediate ZnS layer, and a top layer composed carbon and nitrogen, which is attributed to the polymeric CN coating. Line scan analysis (Figure 6A) confirms this structure, revealing a Zn-rich bottom layer, an intermediate region where S and Zn atoms are concentrated, and an upper layer dominated by C and N. The STEM analysis also enabled direct thickness measurements (Figure 6B), from which the individual layer thicknesses were determined. The ZnS intermediate layer measured ca. 0.45-0.50 pm, while the CN top layer was ~ 0.75-1.00 pm thick. Based on the combined morphological and chemical analysis, pZnso was determined to exhibit the optimal coating thickness, potentially offering favorable conditions for both Zn2+ion transport and interfacial protection, which are key factors in mitigating parasitic reactions and dendritic growth.

[0424] The X-ray photoelectron spectroscopy (XPS) after etching (i.e., measuring inside the coating layer and not the surface) of C Is, N Is, Zn 2p, and S 2p for pZnso is shown in Figure Id-g. The C Is spectrum displays three peaks at 284.8, 288.5, and 286.1 eV, corresponding to C=C, C-NEE, and N=C-N, respectively. The N Is spectrum includes peaks at 398.7, 399.8, and 400.7 eV, assigned to C=N-C, N-(C)a, and N-H species. The Zn 2p spectrum shows two peaks at 1022.0 and 1045.1 eV, representing Zn 2p3 / 2 and Zn 2pi / 2 of ZnS. Additionally, weak ZnO-related peaks were observed in the Zn 2p spectrum at 1022.8 and 1045.8 eV, likely originating from slight surface oxidation of the zinc substrate during thermal treatment. The S 2p peaks located at 162.2 and 163.3 eV correspond to S 2p3 / 2 and S 2pi / 2 of ZnS, respectively. These results demonstrate the development of a protective coating on the Zn surface, composed of ZnS and (partially condensed) polymeric carbon nitride layer XR.

[0425] Example IB: Zn coating with a protective CN layer

[0426] Figure 7 shows an example of a coating process of zinc electrode using melamine vapors.

[0427] Example 1C: Zn coating with a protective ZnS / CN layer using thiourea (TU) and melamine precursors

[0428] Figure 8 shows an example of a costing process of zinc electrode using thiourea and melamine (Zn-TU-Mel 350 °C).

[0429] Figures 9A-9C show characterization of Zn-TU-Mel. These figures demonstrate that the coating thiourea undergoes a change during the thermal step (pyrolysis) in the presence of melamine vapor, forming on the surface (at least partially condensed) polymeric carbon nitride as evidenced by both FTIR spectroscopy and the SEM image of the resulting Zn- TU-Mel 350°C electrode. The FTIR analysis serves as the confirmation, revealing characteristic peaks of heptazine-based structures: at 810 cm-1, the out-of-plane bending of triazine rings, at 1200-1650 cm-1the C-N stretching in heterocycles, and an N-H stretching at 3000-3150 cm-1, indicating incomplete condensation.

[0430] Figure 10 shows that a ZnS (cubic phase) forms over the Zn, in addition to a CN layer (typical diffraction of a polymeric carbon nitride ca. 27°).

[0431] The XPS measurement (Figures 11 A and 11B) confirms that at the surface of the material significant amount of ZnS is formed.

[0432] Example ID: Nickel coating with a protective CN layer

[0433] Preparation of melem (Mlm)-2,4,6-triaminopyrimidine (TAP) supramolecular complex, abbreviated as Mlm-TAP, was done by mixing the two precursors in a 3:1 molar ratio within a mixture of ethylene glycol (EG) and water. To prepare the supramolecular film on theNi foil (i.e., Mlm-TAP / Ni, serving as the precursor electrode for the JH), 1.0 g of Mlm- TAP was mixed with 1.0 mL of EG to form a doctor-blading paste, which was then spread over the surface of the Ni foil. Top-view SEM images of the resulting Mlm-TAP film reveal a uniform coating with a rod-like morphology (Figure 12A). The thickness of the precursor film was determined to be 17.8 ± 0.7 pm using a 3D laser microscope (LEXT OLS5000) by making three separate scratches on the film surface and calculating the distance between the exposed nickel surface (the lowest point of the scratch) and the average height of the film on both sides of each scratch.

[0434] In the next step, the Mlm-TAP / Ni electrode was placed on a flexible carbon cloth strip with the coated side facing up and connected to a power source. An electric current of 6.5 A was applied through the carbon strip for 20 seconds under an inert atmosphere, generating the high temperatures required for the polymerization into a CN film. The resulting yellowish color change of the film suggested the formation of a CN film, resulting in CN2o / Ni electrode. Top-view SEM images of the CNio / Ni exhibit a uniform film morphology that is more porous compared to the precursor film (Figure 12B). The film thickness was measured to be 16 ± 1 pm, which is slightly lower than that of the precursor film, likely as a result of thermal condensation and densification. The XRD pattern of CN2o / Ni, collected from the coating side, exhibits two characteristic diffraction peaks at 29 = 13.0° and 27.3°, corresponding to the (100) in-plane structural packing and the (002) interlayer stacking of aromatic units in layered polymeric CN materials, respectively (Figure 12C). The corresponding pattern collected from the Ni side shows only diffraction peaks of metallic nickel, indicating that the Ni substrate remained chemically stable and was not affected by the JH process. The FTIR spectrum of CN2o / Ni displays typical vibrational features of CN, with stretching modes of C-N heterocycles observed in the 1200-1600 cm-1range, a peak at 804 cm-1corresponding to the breathing vibration of tri- .s-triazine (heptazine) units, and a broad absorption around 3000 cm-1attributed to N-H stretching vibrations (Figure 12D).

[0435] Example 2 Electrochemical evaluation of various Zn electrodes in symmetric Zn 11 Zn half cells

[0436] To evaluate the performance of pZnvelectrodes with varying coating thicknesses (ranging from 20 to 80 deposition cycles; see the experimental section for details, Figures 13A- 13D), we conducted electrochemical studies in a symmetric cell (Zn || Zn) configuration. Zn stripping / plating (Zn reversibility) was assessed at different rates of current densities ranging from 5 to 30 mA cm-2, at an areal capacity of 5 mAh cm-2.

[0437] The pZnso electrode shows the smallest hysteresis voltage gap across various current rates among all pZnvelectrodes (Figure 14A and Figures 13A-13D).

[0438] This superior performance is consistent with the optimized structure of pZnso, characterized by full surface coverage and the formation of a distinct ZnS / CN protective layer, as discussed in the previous section. The smallest hysteresis voltage gap indicates improved Zn2+ion transport kinetics and more uniform electrodeposition, both of which are linked to longer cycling lifespan. Due to its superior stability and minimal hysteresis, pZnso was selected for further electrochemical testing.

[0439] To elucidate the effects of thermal treatment, a bZn electrode was also subjected to the same thermal conditions without TU layer coating. Figure 14B shows the comparative voltage gap profiles at different current rates for non-heated bZn, heated bare Zn (hZn), and pZnso electrodes. The bZn electrode exhibits a significantly larger hysteresis voltage gap compared to hZn and pZnso electrodes. Moreover, as the current density increases, the voltage gap of bZn rises sharply, further widening the difference compared to the other two electrodes. These differences may arise from surface morphology changes caused by thermal treatment (with or without coating), which likely improved Zn surface characteristics compared to bare Zn and enhanced electrochemical performance. The Zn surface morphology critically affects Zn stripping / plating performance. Smooth surfaces promote uniform Zn2+deposition and suppress dendrite formation by limiting nucleation at surface irregularities and reducing local electric field intensity. In contrast, rough interfaces enhance local ion flux and lead to uneven Zn growth. Additionally, reduced surface roughness mitigates side reactions such as HER, contributing to improved interfacial stability. This correlation between morphology and electrochemical performance will be further examined in the following sections through SEM analysis.

[0440] To evaluate the practical applicability and effectiveness of the coating layer under high- capacity and long-term cycling conditions, we examined the electrochemical performance of bZn, hZn, and pZnso in symmetric cells at a high current density of 30 mA cm-2and a fixed areal capacity of 30 mAh cm-2(Figure 14D). Among all tested electrodes, pZnso exhibited the best Zn2+ / Zn reversibility, with a prolonged cycling lifespan of 170 h, compared to 50 h for bZn and 120 h for hZn, and a significantly reduced voltage hysteresis of 170 mV, in contrast to 365 mV for bZn and 211 mV for hZn. Notably, the extended cycling lifespan of 170 h achieved by pZnso under these harsh conditions, together with its low voltage hysteresis, outperformed previously reported Zn anodes tested under identical parameters, including zwitterionic molecule-modified Zn (I lO h, 200 mV), and in situ poly dopamine solid electrolyte interphase (SEI)-protected Zn (78 h, 200 mV). The voltage profiles also highlight the enhanced stability of pZnso. Unlike bZn, which exhibited highly unstable profiles with fluctuating plating / stripping behavior, pZnso maintained consistent voltage hysteresis throughout cycling. Although thermal treatment alone improved the stability relative to bZn, pZnso outperformed both bZn and hZn by delivering greater reversibility, lower voltage hysteresis, and enhanced durability. These findings underscore the effectiveness of combining thermal treatment with ZnS / CN surface coating to produce stable, high-performance Zn-based electrodes. Guided by its superior performance, pZnso was selected for extended cycling tests at a current density of 2 mA cm-2at an areal capacity of 10 mAh cm-2to assess long-term durability further. As shown in Figure 15, the pZnso electrode exhibits stable cycling for 2000 hours with a consistently stable voltage gap, confirming its excellent cycling performance and durability.

[0441] Figure 16 shows long-term cycling performance of melamine-based CN coating of Zn demonstrating that the coating using melamine precursor provides protection to the Zn electrode as evidenced by cycling electrochemical testing in a Zn||Zn configuration. As can be seen in Figure 16, a stable cycling was shown for 850 hours.

[0442] Electrochemical characterization was further done. The protective qualities of Zn-TU-Mel 350 °C layer are tested in a reversible zinc peroxide battery configuration. Figures 17A and 17B show much longer operation without significant losses to energy efficiency or attained voltage.

[0443] Figure 18 presents the stability profile, and Figure 19 the rate profile.

[0444] The electrochemical analysis of the battery performance utilizing protected Zn-TU-Mel 350 °C (ZnTU 60 layers + 1.0 g Mel after 350 °C pyrolysis) anodes shows improved characteristics compared to uncoated Zn electrodes (Figures 17-19). They have significantly longer battery life compared to a battery with uncoated zinc anode (over 1000 h compared to less than 400 h).

[0445] Example 3 Parasitic chemistry studies and Zn-peroxide battery (ZPB) performance

[0446] As discussed previously, for RZABs to realize their full potential, there's a great need to address the parasitic reactions that occur during the Zn anode operation, such as dendrite formation, anode passivation through ZnO deposition, and HER. To investigate the origin of the enhanced stability provided by ZnS / CN protective layer and thermal treatment, we performed H2 gas quantification using gas chromatography (GC), along with SEM and XPS analyses on bZn, hZn, and pZnso electrodes before and after Zn reversibility tests. GC H2(g) quantification was carried out during Zn reversibility cycling process at 2 mA cm-2current density and areal capacity of 5 mAh cm-2.

[0447] Figure 20A shows that the pZnso electrode produced the lowest amount of hydrogen in the anodic compartment during the Zn reversibility test. The hZn electrode also exhibited a notable reduction in H2evolution compared to the bZn electrode, but its suppression effect was less pronounced than that of pZnso, indicating that the ZnS / CN protective coating layer contributed more effectively to HER mitigation than thermal treatment alone. The bZn electrode exhibiting a nearly five and 10-fold higher rate of 22.9 nmol h-1, compared to 4.9 nmol h-1for the hZn electrode and 2.3 nmol h-1for the pZnso electrode, respectively.

[0448] Next, the surface morphology of all electrodes was analyzed using SEM before and after a 100 h Zn2+ / Zn reversibility test (50 cycles) in symmetric cells at a fixed current density of 1 mA cm-2(corresponding to 1 mAh cm-2). Top-view SEM images (Figure 20B-20D) of bZn, hZn, and pZnso electrodes before cycling accentuate the morphological difference of the electrodes' surface. The bZn surface appears rough and uneven (Figure 20B), while the hZn (Figure 20C) displays reduced surface roughness. In contrast, the pZnso electrode (Figure 20D) features a dense, uniform coating that completely covers the Zn foil surface.

[0449] After 100 h of cycling tests, the bZn (Figure 20E) develops numerous sharp dendritic structures, resulting in a highly uneven surface. These dendrites can cause capacity degradation, internal short circuits, and severely reduced electrode lifespan. In addition, they enlarge the electrode-electrolyte interfacial area, creating abundant reactive sites that locally reduce current density, thereby accelerating unwanted side reactions such as hydrogen evolution and corrosion. In contrast, the hZn (Figure 20F) and pZnso (Figure 20G) maintain smooth, dendrite-free surfaces, indicating high Zn2+ / Zn reversibility and improved structural integrity during cycling, even under highly alkaline conditions, which are a known challenge for Zn-air batteries. The observed morphological improvements, particularly the smooth and dendrite-free surfaces of the hZn and pZnso electrodes, are closely associated with reduced HER activity, as mentioned in the previous section. The pZnso electrode demonstrated a substantially reduced hydrogen evolution reaction (HER) rate relative to both bZn and hZn electrodes. This improvement is attributed to the ZnS / CN protective layer, which effectively minimizes hydrogen bubble adhesion to the zinc surface during the HER process. The adherence of hydrogen bubbles to the electrode surface impedes proper nucleation sites, resulting in non-uniform zinc deposition and surface roughening. These morphological changes subsequently accelerate dendrite formation and growth. While thermal treatment also lowers HER in hZn relative to bZn, leading to a smoother surface, the HER suppression in pZnso is more pronounced and will maintain dendrite-free morphology over extended cycling. These findings demonstrate the superior performance of the pZnso electrode, where effective HER suppression and smooth morphology mutually reinforce each other, enhancing electrochemical stability and cycling performance (Figure 14D) in Zn-based electrochemical storage.

[0450] To further investigate the surface chemical states of the electrodes, XPS was performed on bZn, hZn, and pZnso electrodes before and after a 100 h Zn2+ / Zn reversibility test (50 cycles) conducted in symmetric cells at a fixed current density of 1 mA cm-2at an areal capacity of 1 mAh cm-2(Figure 20H-20J). Before cycling, both bZn and hZn exhibited characteristic Zn 2p3 / 2 metallic peaks at -1021.8 eV, along with noticeable ZnO signals at -1022.6 eV. The pZmo electrode displayed an additional distinct ZnS peak, consistent with the sulfur-based surface modification previously discussed in Figure 1c. After 50 cycles, the bZn electrode showed a significant increase in the ZnO peak intensity (-1022.75 eV), indicating the formation of a thick passivation layer that likely obstructs electrochemically active sites of the Zn anode (Figure 20H).

[0451] In comparison, the hZn electrode (Figure 201) also showed ZnO growth, but to a lesser extent. In contrast, pZmo (Figure 20J) demonstrated only a minimal increase in ZnO signal intensity, suggesting effective suppression of the formation of an irreversible ZnO layer during cycling. The higher contribution of ZnO in the bZn electrode is further confirmed by the ZnO / Zn or ZnO / ZnS ratio shown in Figure 10k. For bZn, this ratio increased by -200% after the cycling test, indicating substantial ZnO formation. In comparison, the hZn electrode showed a more moderate increase of -90%. Most notably, the ZnO / Zn or ZnO / ZnS ratio for the pZnso electrode increased by only -10%, which is roughly three times lower than the increase observed in bZn. This demonstrates the protective effect of the TU-derived coating on the Zn surface. It suppresses the formation of irreversible ZnO layers, maintains electrochemical activity, and extends electrode lifespan in alkaline environments. The surface wettability of the anodes was evaluated by contact angle measurements in a 6 M KOH + 0.20 M Zn(OAc)2 electrolyte.

[0452] Table 1. Contact angle values of bZn, hZn, and pZnso with 6 M KOH + 0.20 Zn(OAc)2 electrolyte.

[0453] Sample name Average bZn 79.9° ±

[0454] 1.3° hZn 84.6° ±

[0455] 4.9° pZnso 44.7° ±

[0456] 3.3°

[0457] As shown in Table 1, the contact angle values for bZn, hZn, and pZnso electrodes were 79°, 84°, and 44°, respectively. The significantly lower contact angle observed for the pZnso electrode indicates enhanced surface wettability under experimental conditions, which promotes favorable electrode-electrolyte interactions. Improved wettability is critical for achieving superior Zn2+ / Zn reversibility, as it facilitates homogeneous Zn2+ion distribution across the electrode surface, promoting uniform zinc nucleation that results in smooth plating and stripping behavior, thereby mitigating dendrite formation. Moreover, the enhanced wettability provides additional benefits by reducing hydrogen bubble adhesion on the electrode surface, which promotes stable and reversible zinc electrodeposition. It also increases electrode-electrolyte contact area, boosting ionic transport across interfacial layers and reducing charge transfer resistance, while decreasing interfacial free energy to improve ion transfer dynamics.

[0458] To evaluate the practical applicability of the pZnso electrode, we assembled a reversible high-energy-efficiency alkaline Zn-peroxide battery (ZPB) system A custom-made H-cell employed a bifunctional NiioPy catalyst as the cathode, which effectively facilitates both the 2e“ oxygen reduction reaction (ORR) to HO2 and peroxide oxidation reaction (POR); bZn (or) pZnso electrodes serve as the anode (see Supporting Information for battery assembly details). An anion-conducting membrane was used to separate the anode and cathode. ZPB cycling performance was assessed at a fixed areal capacity of 9 mAh cm-2and a current density of 2 mA cm-2. This helps to evaluate the Zn anodes purely without facing round-trip efficiency issues due to the lack of existing facile bifunctional 4e“ ORR / OER electrocatalysts.

[0459] The ZPB configured with a bare Zn anode (bZn || NiioPy) failed after approximately 380 h of operation (Figure 20L teal line). In contrast, the ZPB using pZnso anode (pZnso || NiioPy) delivered exceptional durability, operating stably for over 1100 h, which is nearly three times longer than its bZn counterpart (Figure 20L, green line). Round-trip energy efficiency (RTEE) was calculated as the ratio between the average discharge and charge voltages at a fixed capacity Based on this calculation, the pZnso-based ZPB exhibited a significantly higher and more stable RTEE of 92% ± 3%, compared to 84% ± 2% for the bZn-based system throughout the entire cycling period. These performance improvements are attributed to the TU-derived protective layer, which promotes uniform Zn deposition and effectively suppresses parasitic reactions such as hydrogen evolution. It also limits Zn corrosion and minimizes the continuous formation of irreversible ZnO during redox cycling under highly alkaline conditions. Together, the electrochemical study and ZPB performance results confirm that the TU-derived protective layer on pZnso anode delivers excellent stability, efficiency, and longevity, establishing it as a promising candidate for next-generation high-alkaline energy storage systems.

[0460] In this work, a strategy to improve Zn anode performance through the application of a thiourea (TU)-derived protective coating, deposited via ultrasonic spray and followed by thermal treatment. This method forms a ZnS / polymeric carbon nitride composite layer on the Zn foil surface. Among the tested configurations, the pZnso electrode, featuring 50 coating layers, exhibited the lowest hysteresis voltage gap across all current densities in symmetric Zn || Zn configurations and demonstrated excellent stability, operating at a fixed areal capacity of 30 mAh cm-2for 180 h in a highly alkaline 6 M KOH electrolyte. The ZnS / CN protective layer plays a critical role in regulating Zn2+ion transport, effectively suppressing dendritic growth, parasitic hydrogen evolution, zinc corrosion, and the formation of irreversible ZnO during redox cycling under high alkaline conditions. The protective coating contributes to enhanced cycling performance and long-term electrochemical stability of Zn anodes.

[0461] Furthermore, the real-world applicability of pZnso was validated in a reversible high- efficiency alkaline Zn-peroxide battery (ZPB), where it served as the anode in combination with a nickel-based (NiioPy) bifunctional cathode. The ZPB incorporating pZnso achieved a threefold increase in operational lifespan (-1100 h) compared to a bZn-based system (-380 h) while maintaining a high round- trip energy efficiency of 92% ± 3%. Overall, the Zn / ZnS / CN configuration synthesized thiourea provides a robust, scalable route for developing stable Zn anodes, positioning pZnso as a highly promising candidate for nextgeneration alkaline aqueous energy storage systems.

[0462] Example 4: CN coating fabrication and characterization using FTO

[0463] Figures 22A-22F show scanning electron microscopy (SEM) images of CN layer fabrication steps with digital images as the insets. Pastes of melamine (Mlm) as a single precursor or bismuthiol-melamine (BM) as a supramolecular assembly serving as the precursor are applied and dried, resulting in white to off-white color before heating (Figures 22A and 22D). The films transform into CN films (yellow or brown, respectively) after the JH-induced thermal polymerization (Figures 22B and 22E). If the synthesis is performed in the presence of additional melamine-TAP powder (MT) the resulting material has structural integrity, improved porosity, and higher thickness (Figures 22C and 22F — with a thickness of up to 50 pm — compared to Figures 22B and 22E).

[0464] X-ray diffraction (XRD) patterns in Figures 23A-23B clearly show how the precursor pastes BM and Mlm react and transform into CN after heating (e.g., in-plane (100) diffraction signal ca. 13.2° and interplanar stacking (002) about 27.6°). This analysis is further confirmed by Fourier-transform infrared (FTIR) spectroscopy: at -3000 cm-1stretching vibrations of the N-H of amino groups. The peaks between 1100-1700 cm-1match to the stretching modes of CN-heterocycles. The peak at 800 cm-1matches the breathing vibration of heptazine units.

[0465] These CN materials over the transparent conductive substrate were tested for photoelectrochemical applications in a standard 3-electrode cell in 0.1 M KOH as the electrolyte. The FTO / CN serves as the working electrode and photoanode, illuminated by a Xe-based solar simulator (1 sun, AM 1.5G). The counter electrode was a 1 cm2Pt sheet, serving as the cathode, and an Ag / AgCl reference electrode. The thicker electrodes gave higher photocurrents for each of the supramolecular assemblies with powders relative to the same electrodes without added powders (Figure 24A and 24B) in chronoamperometric measurements at 1.23 V on the reversible hydrogen electrode (RHE) scale.

[0466] To complement the analysis, UV-vis diffuse reflectance accessory (DRA) reflectance measurements and transmittance were measured and transformed to % absorbance (Figure 24C). It shows a red-shift of the absorbance spectra when BM was used. We speculate this stems from new levels in the material due to introduction of sulfur from the bismuthiol precursor, allowing a narrower band gap that the CN from melamine which is ca. 2.7 eV.

[0467] Applying the discussed procedure (Mlm-Mel supramolecular aggregate in ethylene glycol) on a Zn foil, followed by applying current in the JH system allowed construction of a symmetric Zn| |Zn cell as shown in Figure 25.

[0468] Solutions for ultrasonic spray preparation: a thiourea solution was prepared by mixing 80 mL DI water with 10 g of thiourea; an urea solution was prepared by mixing 40 mL DI water with 15 g of urea.

[0469] CN electrodes fabrication, characterization, and analysis using a preliminary spraycoating step: To further improve the FTO / CN interface, we used ultrasonic spray as the seeding layer before applying doctor-blading, as shown in Figure 26.

[0470] This step is versatile since it allows using different precursors as long as they are soluble in the solvating medium for the spray step. These precursors may contain C and N atoms as well as heteroatoms (X) and metals. This method paves the way for augmenting the CN properties: chemical compositions, thickness, porosity, surface groups, and adhesion to the surface. Importantly it allows a vast amount of homojunctions and heterojunctions to be prepared as demonstrated in Figure 27, when two subsequent yet distinct CN films can be deposited.

[0471] Ten ultrasonic spray cycles using thiourea (TU) or urea (U) were used to form a seeding layer for a thin doctor-blading layer. The seeding layer allows for good adhesion and allows for the formation of thin, porous layers (Figure 28B and 28C)

[0472] XRD and FTIR characterization in Figure 29 confirm the precursors transformation into the expected CN layers over FTO without the spray-coating step (SEM shown in Figure 28A).

[0473] It further demonstrates the formation of thicker CN layers via the multistep approach shown in Figure 29. First of all, increasing the number of ultrasonically sprayed layers make the first layer of precursors an important layer that can transform into its respective CN or CN-based layer, and not merely serve as a seeding layer. For example, increasing the number of urea sprayed cycles from 10 to 100 (Uioo). Furthermore, after an FTO / CN layer was formed, we performed an additional synthetic cycle with a thin urea seeding layer (Uio), doctor blading a Mlm-melamine in ethylene glycol paste, and finally, a second JH procedure. The resulting SEM image is shown in Figure 30.

[0474] Example 5: Glass and fluorine-doped tin oxide (FTO) coated glass

[0475] Glass and fluorine-doped tin oxide (FTO) coated glass were tested similar to CNio / Ni electrode as shown in Example 4 and as shown in Figure 31A. XRD patterns of the Mlm- TAP films deposited on Ni, glass, and FTO substrates exhibit consistent Mlm-TAP characteristic peaks, indicating uniform film formation across all substrates (Figure 31B). After JH under substrate-optimized conditions, the electrodes were named to reflect both the heating time and the substrate, following the format CNv / substrate.

[0476] The demonstrated examples of coating glass or FTO use a current of 9A. The XRD patterns of the CNv / substrate electrodes display the characteristic CN peaks at 29 values of 13° and 27°, along with the corresponding background signals from the substrate (Figure 31C). Moreover, CNv / substrate electrodes exhibit closely matching features in FTIR spectra (Figure 31D). These results highlight the versatility of JH in the synthesis of CN films across different substrates.

Claims

1. CLAIMS:

1. A coated article comprising a substrate selected from a metal, a metal atomcontaining material, or a ceramic material, wherein said substrate is at least partially coated with a polymeric carbon nitride (CN) layer.

2. The coated article of claim 1 , further comprising a metal chalcogenide, a chalcogen- doped metal oxide, or a chalcogen-containing ceramic material.

3. The coated article of claim 1 or 2, wherein the metal chalcogenide, the chalcogen- doped metal oxide, or the chalcogen-containing ceramic material forms an intermediate layer between the substrate and the polymeric CN layer.

4. A coated article comprising a substrate, an intermediate layer and an outer layer, wherein the substrate is selected from a metal, a metal atom-containing material, or a ceramic material, wherein said intermediate layer comprises a metal chalcogenide, a chalcogen-doped metal oxide, or a chalcogen-containing ceramic material, wherein said outer layer comprises a polymeric CN, and wherein said intermediate layer is disposed between said substrate and said polymeric CN layer.

5. The coated article of any one of claims 1 to 4, being essentially binder free.

6. The coated article of any one of claims 1 to 5, wherein said substrate is in form of a slab, a sheet, a foil, a leaf, a plate, a rod, a cylinder, a wire, a powder, a granule, a mesh, a porous structure, or a foam.

7. The coated article of any one of claims 1 to 6, wherein said metal is or comprises one or more of a pure metal, a homogeneous metal alloy, an inhomogeneous metal alloy or a comprising a metallic phase in combination with additional elements.

8. The coated article of any one of claims 1 to 7, wherein said metal is one or more of a transition metal, a post-transition metal, an alkaline earth metal, an alkali metal, a rare- earth element, or any combination or alloy thereof.

9. The coated article of any one of claims 1 to 8, wherein said metal is selected from Nickel (Ni), Zinc (Zn), Copper (Cu), Iron (Fe), Platinum (Pt), Rhenium (Re), Palladium (Pd), Manganese (Mn), Aluminum (Al), Magnesium (Mg), Calcium (Ca), Titanium (Ti), Cobalt (Co), Silver (Ag), Gold (Au), Iridium (Ir), Cadmium (Cd), Indium (In), Tin (Sn),Tungsten (W), Molybdenum (Mo), Vanadium (V), Lead (Pb), Tantalum (Ta), Zirconium (Zr), Antimony (Sb), Chromium (Cr), or Bismuth (Bi).

10. The coated article of claim 9, wherein said metal is Nickel.

11. The coated article of claim 9, wherein said metal is Zinc.

12. The coated article of claim 1 , wherein the metal atom-containing material is a metal oxide.

13. The coated article of claim 12, wherein said metal oxide is selected from zinc oxide (ZnO), titanium oxide (T1O2), tin oxide (SnCL), indium oxide (ImOi), barium tin oxide (BaSnCh), InGaZnO-i, fluorine-doped tin oxide (FTO), indium tin oxide (ITO), aluminum- doped zinc oxide (AZO), cadmium oxide (CdO), gallium oxide (GaiOs), copper-based delafossites (as CuGaOi), zinc-based ferrites (as NiZnFe2O_i) or any combination thereof.

14. The coated article of claim 13, wherein said metal oxide is FTO.

15. The coated article of claim 1, wherein said ceramic material is selected from glass, alumina, silica, or zirconia.

16. The coated article of claim 15, wherein said ceramic material is glass.

17. The coated article of any one of claims 2 to 16, wherein said chalcogenide is one or more of oxygen (O), sulfur (S), selenium (Se), tellurium (Te), or any combination thereof.

18. The coated article of any one of claims 2 to 17, wherein said metal chalcogenide is one or more of a metal sulfide, a metal selenide, a metal telluride or any combination thereof.

19. The coated article of claim 18, wherein said metal chalcogenide is or comprises zinc sulfide (ZnS).

20. The coated article of claim 18, wherein said metal chalcogenide is or comprises nickel sulfide (NiS).

21. The coated article of any one of claims 1 to 20, wherein said polymeric CN is represented by the general formulas CxNyHpOq, CxNyHpOqEr, or CxNyHpOqErXs:Md,wherein E is a chalcogenide element, x, y, p, q, r, s are atomic indices, X is a heteroatom dopant and Ma is a metal dopant.

22. The coated article of claim 21, wherein said heteroatom dopant X is selected from B, P, F, Cl, Br, I, O, S, Se, Te, Sb, Si, Bi and said metal dopant Md is selected from Zn, Mg, Ca, K, Na, Fe, Co, Ni, Cu, Mn, Mo, W, V, Pt, Y, Zr, Sn, In, Cd, Al.

23. A coated article comprising a substrate, wherein the substrate is or comprises Ni and wherein said Ni substrate is at least partially coated with a polymeric CN layer.

24. A coated article comprising a substrate, an intermediate layer and an outer layer, wherein the substrate is or comprises Ni, wherein the intermediate layer comprises a Ni chalcogenide, wherein the outer layer comprises a polymeric CN, and wherein the intermediate Ni chalcogenide layer is disposed between the Ni substrate and the polymeric CN layer.

25. A coated article comprising a substrate, wherein the substrate is or comprises Zn and wherein said Zn substrate is at least partially coated with a polymeric CN layer.

26. A coated article comprising a substrate, an intermediate layer and an outer layer, wherein the substrate is or comprises Zn, wherein the intermediate layer comprises a Zn chalcogenide, wherein the outer layer comprises a polymeric CN, and wherein the intermediate Zn chalcogenide layer is disposed between the Zn substrate and the polymeric CN layer.

27. A coated article comprising a substrate, wherein the substrate is or comprises FTO and wherein said substrate is at least partially coated with a polymeric CN layer.

28. A coated article comprising a substrate, wherein the substrate is or comprises glass and wherein said substrate is at least partially coated with a polymeric CN layer.

29. A process for forming a coated article, the process comprising heating a substrate selected from a metal, a metal atom-containing material, or a ceramic material, wherein said substrate is at least partially coated with a precursor compound comprising at least one carbon atom and at least one nitrogen atom, and wherein said heating converts the precursor into a polymeric CN layer deposited on said substrate.

30. The process of claim 29, wherein said precursor compound comprises at least one chalcogenide-containing group and wherein said heating converts the precursor compound into a chalcogenide layer and to the polymeric CN layer.

31. A process for forming a coated article, comprising heating a substrate selected from a metal, a metal atom-containing material, or a ceramic material, wherein said substrate is at least partially coated with a precursor compound comprising at least one carbon atom, at least one nitrogen atom and at least one chalcogenide-containing group, and wherein said heating converts the precursor into (i) a chalcogenide layer disposed on the substrate and (ii) a polymeric CN layer disposed on the intermediate layer.

32. The process of any one of claims 29 to 31, further comprising prior to heating, applying said precursor compound onto the substrate.

33. A process for forming a coated article, comprising applying a precursor compound onto a substrate and heating said substrate, wherein the precursor compound comprises at least one carbon atom and at least one nitrogen atom, optionally further comprising at least one chalcogen-containing group and wherein said heating converts the precursor into (i) a metal chalcogenide layer and / or (ii) a polymeric carbon nitride (CN) layer.

34. The process of claims 33, wherein the metal chalcogenide layer is disposed on the metal substrate and the polymeric CN layer is disposed on the metal chalcogenide layer.

35. The process of claim 34, wherein the applying is by one or more of (i) cold press (pelletilization), (ii) hot press, (iii) doctor-blading, (iv) spin coating, (v) dip coating, (vi) spray coating, (vii) ultrasonic spray coating, (viii) immersion in a hot saturated solution, or (ix) any combination thereof.

36. The process of claim 35, wherein the applying is by ultrasonic spraying.

37. The process of claim 35, wherein the applying is by doctor blading.

38. The process of any one of claims 29 to 37, wherein said metal is selected from Nickel (Ni), Zinc (Zn), Copper (Cu), Iron (Fe), Platinum (Pt), Rhenium (Re), Palladium (Pd), Manganese (Mn), Aluminum (Al), Magnesium (Mg), Calcium (Ca), Titanium (Ti), Cobalt (Co), Silver (Ag), Gold (Au), Iridium (Ir), Cadmium (Cd), Indium (In), Tin (Sn),Tungsten (W), Molybdenum (Mo), Vanadium (V), Lead (Pb), Tantalum (Ta), Zirconium (Zr), Antimony (Sb), Chromium (Cr), or Bismuth (Bi).

39. The process of claim 38, wherein said metal is Nickel.

40. The process of claim 38, wherein said metal is Zinc.

41. The process of any one of claims 29 to 37, wherein said metal atom-containing material is a metal oxide.

42. The process of claim 41 , wherein the metal oxide is selected from zinc oxide (ZnO), titanium oxide (TiCh), tin oxide (SnCL), indium oxide (IniCh), barium tin oxide (BaSnCh), InGaZnO-i, fluorine-doped tin oxide (FTO), indium tin oxide (ITO), aluminum-doped zinc oxide (AZO), cadmium oxide (CdO), gallium oxide (GaiOs), copper-based delafossites (as CuGaOi), zinc-based ferrites (as NiZnFe2O_i) or any combination thereof.

43. The process of claim 42, wherein the metal oxide is FTO.

44. The process of any one of claims 29 to 37, wherein said ceramics is glass.

45. The process of any one of claims 29 to 44, wherein said precursor compound is or comprises thiourea, melamine, melem, 2,4,6-triaminopyrimidine (TAP), bismuthiol, urea, or a supramolecular assembly thereof.

46. The process of claim 45, wherein the supramolecular assembly is selected from melamine-TAP, melem-TAP, bismuthiol-melamine, or melem-melamine.

47. The process of any one of claims 29 to 46, wherein heating comprises thermal heating under inert atmosphere.

48. The process of any one of claims 29 to 46, wherein heating comprises Joule heating.

49. A coated metal article obtained by the process as defined in any one of claims 29 to 48.

50. A coated metal article obtainable by the process as defined in any one of claims 29 to 48.

51. The coated article of any one of claims 1 to 29, 49 or 50 for use as an electrode.

52. The coated metal article of claim 51, for use in a method of generating hydrogen.

53. An electrode comprising the coated article as defined in any one of claims 1 to 29, 51 or 52.

54. The electrode of claim 53, characterized by one or more of (i) suppresses parasitic hydrogen evolution, (ii) reduces dendrite formation and growth and (iii) reduce metal corrosion.

55. An electrochemical cell comprising an electrode assembly, wherein at least one electrode in the electrode assembly is defined in claim 53 or 54.

56. The electrochemical cell of claim 55, wherein said electrode serves as the anode.

57. The electrochemical cell of claim 55 or 56, wherein the cell is a metal-air battery.

58. The electrochemical cell of any one of claims 55 to 57, wherein the cell is a rechargeable metal-air battery.

59. The electrochemical cell of claim 58, wherein the rechargeable metal-air battery is a rechargeable zinc-air battery (RZAB).

60. The electrochemical cell of claim 58, wherein the rechargeable metal-air battery is a zinc-peroxide battery.

61. Use of a coated article according to any one of claims 1 to 29 as an electrode in an electrochemical cell or in a photoelectrochemical cell.

62. Use of a coated article according to any one of claims 1 to 29 as a photocatalytic material in a photoreactor.

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