A tuned copper catalyst for the electroreduction of carbon oxide to ethylene

Abstract

The present disclosure relates to a catalyst for electroreduction of CO, CO2 or a mixture thereof into carbon products comprising ethylene, wherein the catalyst comprises: - a copper-based nanostructure having a surface comprising copper atoms, and being a two-dimensional copper-oxide nanosheet, and - an organic compound being an electron acceptor and having at least one functional group comprising a dicyanomethylene group; wherein the organic compound is ionically bonded to the copper atoms as determined by ex-situ Raman spectroscopy.

Description

A TUNED COPPER CATALYST FOR THE ELECTROREDUCTION OF CARBON OXIDE TO ETHYLENETECHNICAL FIELD

[0001] The present invention generally relates to the carbon monoxide and / or carbon dioxide electroreduction into carbon products including ethylene, and more particularly to a tune copper catalyst favoring carbon monoxide and / or carbon dioxide electroreduction into ethylene.BACKGROUND

[0002] The reduction of carbon dioxide (CO2RR) to chemicals such as ethylene (C2H4) using renewable electricity could - if efficiently accomplished - contribute to industrial decarbonization. Carbonate formation in neutral to alkaline CO2RR leads to inefficient CO2utilization, motivating increased interest in CO electroreduction (CORR). CORR to ethylene is a promising carbonate-free approach to mitigate the carbon footprint but requires further progress in selectivity and energy efficiency.

[0003] Hence, there is still a need for techniques that would overcome the lack of selectivity towards ethylene and the lack of energy efficiency known in the field (energy efficiency of CO-to-C2H4 electrosynthesis best value known in the art is 28%).SUMMARY

[0004] The present techniques respond to the above-mentioned need by providing a copper-based catalyst and a method for the preparation of said catalyst. A process for carbon oxides (CO and / or CO2) electroreduction into carbon products comprising ethylene, using said catalyst is provided. Aspects of a related electroreduction system is further provided. More particularly, aspects of the present techniques are as follows.

[0005] In a first aspect, there is provided a catalyst for electroreduction of CO, CO2or a mixture thereof into carbon products comprising ethylene. The catalyst includes: a copper-based nanostructure having a surface comprising copper atoms, and an organic compound being an electron acceptor and having at least one functional group comprising a nitrogen atom;wherein the organic compound is ionically bonded to the copper atoms as determined by ex-situ Raman spectroscopy.

[0006] In particular, there is provided a catalyst for electroreduction of CO, CO2or a mixture thereof into carbon products comprising ethylene. The catalyst includes: a copper-based nanostructure having a surface comprising copper atoms, and being a two- dimensional copper-oxide nanosheet; and an organic compound being an electron acceptor and having at least one functional group comprising a dicyanomethylene group; wherein the organic compound is ionically bonded to the copper atoms as determined by ex-situ Raman spectroscopy.

[0007] The catalyst can have an atomic percentage of nitrogen atoms ranging between 2 at.% and 10 at.% based on the total atomic content of the catalyst, as determined by X-ray Photoelectron Spectroscopy measurements; optionally, between 2 at.% and 4 at.%.

[0008] In yet another aspect, there is provided a catalyst for electroreduction of CO, CO2or a mixture thereof into carbon products comprising ethylene, wherein the catalyst comprises: a copper-based nanostructure comprising copper atoms, and an organic compound being an electron acceptor and having at least one functional group comprising a nitrogen atom; wherein the organic compound is ionically bonded to the copper atoms at an interface of the copper- based nanostructure upon transferring electrons therebetween; and wherein an atomic percentage of nitrogen atoms in the catalyst is in the range of about 2 at. % to about 10 at.%, optionally, between 2 at.% and 4 at.%., as determined by X-ray Photoelectron Spectroscopy (XPS) measurements.

[0009] In yet another particular aspect, there is provided a catalyst for electroreduction of CO, CO2or a mixture thereof into carbon products comprising ethylene, wherein the catalyst comprises: a copper-based nanostructure comprising copper atoms being a two-dimensional copper- oxide nanosheet, and an organic compound being an electron acceptor and having at least one functional group comprising a dicyanomethylene group;wherein the organic compound is ionically bonded to the copper atoms at an interface of the copper- based nanostructure upon transferring electrons therebetween; and wherein an atomic percentage of nitrogen atoms in the catalyst is in the range of about 2 at. % to about 10 at.%, optionally, between 2 at.% and 4 at.%., as determined by X-ray Photoelectron Spectroscopy (XPS) measurements.

[0010]

[0011] In yet another aspect, there is provided a catalyst for electroreduction of CO, CO2or a mixture thereof into a carbon product, wherein the catalyst comprises: a copper-based nanostructure comprising copper atoms, and 7,7,8,8-tetracyanoquinodimethane (TCNQ); wherein the TCNQ is ionically bonded to the copper atoms at an interface of the copper-based nanostructure upon transferring electrons therebetween.

[0012] For example, an atomic percentage of nitrogen atoms in the catalyst can be in the range of about 2 at. % to about 10 at. %, as determined by X-ray Photoelectron Spectroscopy (XPS) measurements.

[0013] The copper-based nanostructure can be a nanosheet. In some implementations, the copper- based nanostructure is a two-dimensional copper-oxide (CuO) nanosheet. In some implementations, the copper-based nanostructure is a copper nanosheet..

[0014] The copper atoms can show a face centered cubic crystal structure with at least one of (111), (200), or (220) facets.

[0015] The copper-based nanostructure can comprise electron-deficient active metal sites, preferably with unfilled d orbitals.

[0016] The at least one functional group comprising the nitrogen atom can be a cyano group; optionally, the at least one functional group comprising the nitrogen atom is a dicyanomethylene group.

[0017] The organic compound can be selected from 7,7,8,8-tetracyanoquinodimethane (TCNQ), tetracyanoethylene (TCNE), 2,3,5,6-Tetrafluoro-7,7,8,8-tetracyanoquinodimethane (F4TCNQ), perylene diimide and a mixture thereof;

[0018] With preference, the organic compound can be selected from 7, 7,8,8- tetracyanoquinodimethane (TCNQ), tetracyanoethylene (TCNE), 2,3,5,6-Tetrafluoro-7,7,8,8- tetracyanoquinodimethane (F4TCNQ), and a mixture thereof.

[0019] Optionally, the organic compound is 7,7,8,8-tetracyanoquinodimethane (TCNQ).

[0020] In another aspect, there is provided a method for the preparation of a catalyst for electroreducing CO, CO2or a mixture thereof into carbon products comprising ethylene. The method includes: a) providing a copper-based nanostructure in the form of a powder; b) forming a dispersion by dispersing the powder provided at step (a) in one or more polar protic solvents; c) providing an organic compound which is an electron acceptor and has at least one functional group comprising a nitrogen atom; d) forming a solution by dissolving the organic compound provided at step (c) in an organic solvent; e) forming a mixture by adding the solution of step (d) to the dispersion of step (b) under ultrasonication, wherein a ratio of a volume of the first solution to a volume of the dispersion is from about 0.02 to about 0.3; f) forming an ink by adding a binder to the mixture of (e) under ultrasonication; g) providing a porous support; h) spray-coating the ink formed at step (f) onto the porous support provided at step (g) to form a catalytic layer with a loading amount of at least 1 mg. cm-2; and i) applying a reduction current to the catalytic layer to obtain in-situ the catalyst comprising the organic compound being ionically bonded to the copper atoms of the surface of the copper- based nanostructures upon transferring electrons therebetween.

[0021] In particular, there is provided a method for the preparation of a catalyst for electroreducing CO, CO2or a mixture thereof into carbon products comprising ethylene. The method includes: a) providing a copper-based nanostructure being a two-dimensional copper-oxide nanosheet in the form of a powder; b) forming a dispersion by dispersing the powder provided at step (a) in one or more polar protic solvents; c) providing an organic compound which is an electron acceptor and has at least one functional group comprising a dicyanomethylene group;d) forming a solution by dissolving the organic compound provided at step (c) in an organic solvent; e) forming a mixture by adding the solution of step (d) to the dispersion of step (b) under ultrasonication, wherein a ratio of a volume of the first solution to a volume of the dispersion is from about 0.02 to about 0.3; f) forming an ink by adding a binder to the mixture of (e) under ultrasonication; g) providing a porous support; h) spray-coating the ink formed at step (f) onto the porous support provided at step (g) to form a catalytic layer with a loading amount of at least 1 mg. cm-2; and i) applying a reduction current to the catalytic layer to obtain in-situ the catalyst comprising the organic compound being ionically bonded to the copper atoms of the surface of the copper- based nanostructures as determined by ex-situ Raman spectroscopy upon transferring electrons therebetween.

[0022] For example, the concentration of the copper-based nanostructure within the dispersion formed at step (b) can be ranging from 1 mg / mL to 50 mg / mL; optionally, from 2 mg / mL to 30 mg / mL. For example, the concentration of the organic compound in the solution formed at step (d) can be ranging from 1 mM to 50 mM; optionally, from 2 mM to 30 mM.

[0023] For example, the one or more polar protic solvents can be one or more compounds with at least one hydroxylic group; optionally, the one or more polar protic solvents are selected from methanol, ethanol, propanol and isopropanol or any mixture thereof.

[0024] For example, the organic solvent of step (d) can be one or more polar aprotic solvents; optionally, said one or more polar aprotic solvents are selected from acetonitrile, tetrahydrofuran, dichloromethane, chloroform or any mixture thereof.

[0025] For example, a ratio of a volume of the solution to a volume of the dispersion can be from 0.01 to 0.2, optionally from 0.05 to 0.10.

[0026] For example, the binder can include one or more perfluorinated sulfonic acid ionomers being selected from 1 ,1 ,2,2-tetrafluoroethene and 1 ,1 ,2,2-tetrafluoro-2-[1 ,1 ,1 ,2,3,3-hexafluoro-3-(1 ,2,2- trifluoroethenoxy)propan-2-yl]oxyethanesulfonic acid.

[0027] For example, the ratio of a volume of the binder to a volume of the mixture formed at step (e) can be from 0.01 to 0.05, optionally from 0.02 to 0.04.

[0028] In further implementations, the catalyst formed by the method can include at least one other feature as defined herein.

[0029] In yet another aspect, there is provided a gas diffusion electrode for the electroreduction of CO, CO2or a mixture thereof into carbon products comprising ethylene. The gas diffusion electrode includes: a porous support; the catalyst as defined herein or as prepared according to the method as defined herein, being deposited on the porous support.

[0030] For example, the porous support can be polytetrafluoroethylene (PTFE), or porous carbon paper.

[0031] In yet another aspect, there is provided a system for electroreduction of CO, CO2or a mixture thereof into carbon products comprising ethylene. The system includes: a cathodic compartment comprising: a reactant inlet that is configured to supply a gaseous stream comprising CO, CO2or the mixture thereof in the cathodic compartment, a cathode being the gas diffusion electrode as defined herein; a product outlet configured to release a gas-liquid mixture comprising the carbon products from the cathodic compartment; an anodic compartment comprising: an anodic inlet that is configured to supply an anolyte in the anodic compartment, an anode, and an anodic outlet that is configured to release used anolyte from the anodic compartment; an ionic exchange membrane that is positioned between the cathodic compartment and the anodic compartment; anda voltage source that is operatively connected to the anode and the cathode to provide a current density that allows the gaseous stream, when supplied, to contact the catalyst to be electrochemically converted into the carbon products.

[0032] For example, the anode can be or comprise NiFe-B or lrO2.

[0033] For example, the system can be a flow cell and the cathodic compartment can further comprise a catholyte inlet that is configured to be supplied with a catholyte. In another example, the system can be a zero-gap electrolyzer, optionally a membrane electrode assembly.

[0034] In yet another aspect, there is provided a process for electroreduction of CO, CO2or a mixture thereof into carbon products comprising ethylene. The process includes: a) providing the system as defined herein; b) supplying the anolyte to the anodic compartment of the system provided at step (a); c) supplying the gaseous stream comprising CO and / or CO2to the reactant inlet of the cathodic compartment of the system provided at step (a) for contacting the catalyst; and d) generating a reduction current via the voltage source through the system to cause electroreduction of CO and / or CO2into the carbon products; and e) recovering the gas-liquid mixture comprising the carbon products from the product outlet of the cathodic compartment.

[0035] For example, the anolyte can be an alkaline electrolyte; optionally, the alkaline electrolyte is LiOH. For example, the anolyte can be a neutral or near-neutral electrolyte. Optionally, the electrolyte can be K2SO4, KHCO3, I^COs or any mixtures thereof.

[0036] For example, the system can be a flow cell and the cathodic compartment can further comprise a catholyte inlet that is configured to be supplied with a catholyte. For example, the catholyte can be an alkaline electrolyte; optionally, the alkaline electrolyte is LiOH. In another example, the catholyte can be a neutral or near-neutral electrolyte; optionally, the catholyte can be a mixture of K2SO4and KHCO3.

[0037] For example, step (d) can include applying a current density between 100 mA.cm-2and 800 mA.cm'2, preferably between 100 mA.cm-2and 600 mA. cm-2.

[0038] For example, step (c) can be performed at an inlet flowrate between 1.6 seem and 50 seem, preferably between 15 seem and 25 seem.

[0039] While the invention will be described in conjunction with example embodiments, it will be understood that it is not intended to limit the scope of the invention to such embodiments. On the contrary, it is intended to cover all alternatives, modifications and equivalents as may be included as defined by the present description. The objects, advantages and other features of the present invention will become more apparent and be better understood upon reading of the following non- restrictive description of the invention, given with reference to the accompanying drawings.BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 relates to the influence of water dissociation on the product distribution in CORR. The graphs (a) and (b) show the faradaic efficiency for C2H4(C2D4) over commercial 25 nm Cu nanoparticles under the different applied current densities (a), the ratio of C2H4(C2D4) to liquid products (b) in D2O-, 50% D2O + 50% H2O-, and H2O-1 M LiOH electrolyte, respectively. Scheme (c) shows the hypothesis about the effect of water dissociation on product distribution in CORR.

[0041] Figure 2 shows the characterization of Cu-100TCNQ catalyst. Scheme (a) is a schematic illustration of Cu with TCNQ modification during CORR. Graph (b) is a high-resolution N 1s XPS spectra of Cu-100TCNQ and TCNQ molecule. Image (c) is a SEM image of Cu-100TCNQ. Images (d) are a STEM image and corresponding EDS mapping images (Cu and N) of Cu-100TCNQ.

[0042] Figure 3 represents CORR Performance over TCNQ-modified Cu electrode. Graph (a) shows faradaic efficiencies of all products under different applied current densities over bare Cu (patterned) and Cu-WOTCNQ (solid filled) in a flow cell. The error bar in graph (a) represents the standard deviation of three independent experiments. Graph (b) shows the ratio of C2H4to oxygenated liquid products over Cu, Cu-100TCNQ in flow cell. Graph (c) shows the optimized full-cell EE, and partial current density for C2H4over Cu-100TCNQ catalyst under different applied potentials. Graph (d) shows the FE for C2H4and H2in function of the flow rate. Graph (e) shows the EE for C2H4and H2and corresponding SPCE for C2H4over Cu-100TCNQ with the decreasing of flow rate. Graph (f) shows the stability of the Cu-100TCNQ at a constant applied current density of 500 mA cm-2and the corresponding FE for C2H4and H2. Graph (g) shows the influence of EE and single pass carbon efficiency (SPCE) on the energy cost for electrosynthesis of C2H4.

[0043] Figure 4 is related to the mmechanism study of TCNQ modification on Cu for C2H4formation. Graph (a) shows LSV curves of Cu-100TCNQ and Cu under Ar atmosphere. Graph (b) shows H2O adsorption energy over Cu(111)-TCNQ and Cu(111) surface. Graph (c) shows H2O dissociation energy barrier over Cu(111)-TCNQ and Cu(111) surface. Scheme (d) is a representation of the mechanism depicting the influence of C-O bind strength in *CHCOH on the selectivity of C2H4andEtOH. Image (e) shows charge density difference of *CHCOH on Cu(111)-TCNQ and Cu(111) surface. Black and white contours represent the iso-surfaces of electronic charge accumulation and depletion, respectively, with an iso-surface value of 0.01 e A-3implemented. Graph (f) shows the reaction free energy difference between *CCH and *CHCHOH on Ou, Ou with *H2O and Ou with *OH surface, respectively.

[0044] Figure 5 is a SEM image of commercial 25 nm Ou nanoparticles.

[0045] Figure 6 is a schematic diagram of the flow cell.

[0046] Figure 7 represents the CORR performance over 25 nm Cu electrode in 1 M LiOH electrolytes with different ratios of H2O and D2O. Graphs (a), (b) and (c) show the faradaic efficiency (FE) distribution of H2and C2H4in (a) H2O-1 M LiOH electrolyte; (b) 50% H2O + 50% D2O - 1 M LiOH electrolyte; (c) D2O-1M LiOH electrolyte, respectively. Graph (d) shows the applied current density (J (mA cm-2)) and corresponding voltage (E (V vs Ag / AgCI)) in the above three electrolytes. The error bars for FE uncertainty represent one standard deviation based on three independent experiments.

[0047] Figure 8 represents the mechanism study of the role of water in CORR over 25 nm Cu electrode. Graph (a) shows the Tafel slope of 25 nm Cu electrode measured in D2O-, 50% H2O + 50% D2O-, and H2O-1M LiOH electrolytes. Graph (b) shows the kinetic isotope effect (KIE) of H / D at an applied potential range from -0.36 V to -0.53 V (V vs RHE). 25 nm Cu exhibited a similar Tafel slope of ~118 mV / dec in the three electrolytes, suggesting that their reaction kinetics were limited by the one-electron transfer process without proton involved in the RDS. Besides, the KIE of H / D is defined as the ratio of ethylene formation rates in H2O and D2O, which was 1.6-1.9 over 25 nm Cu. The KIE value near 2 over 25 nm Cu indicated that H2O was involved in the rate-determined step (RDS) of CORR. Hence water dissociation was involved in the RDS of CO-to-C2H4pathway directly.

[0048] Figure 9 represents the characterization of CuO nanosheets. Respectively, images (a) and (b) are SEM and TEM images of pristine CuO nanosheets. Image (c) is a HRTEM image of CuO nanosheets, which demonstrates that the CuO nanosheets are well crystallized with a periodic fringe of 0.28 nm, according well to the d-spacing value of the (110) plane for monoclinic CuO. Scheme (d) is a XRD pattern of CuO nanosheets. The pattern of CuO (PDF#45-0937) was used as a reference.

[0049] Figure 10 represents the high-resolution XPS of CuO nanosheets. Spectrum (a) corresponds to Cu 2p. Spectrum (b) corresponds to Cu LMM. The spectra illustrated that the peak position of Cu 2p3 / 2 appears at 933.8 eV with a characteristic satellite peak. Combining with the Cu LMM spectrum, the oxidation state of Cu in CuO nanosheets was +2.

[0050] Figure 11 represents the high-resolution Cu XPS spectra of Cu-100TCNQ. Spectrum (a) corresponds to Cu 2p. Spectrum (b) corresponds to Cu LMM. Two major peaks without satellite peaks indicated the absence of Cu2+in the sample. Subsequent Cu Auger LMM spectra were recorded to determine the oxidation state of Cu. The Cu-100TCNQ exhibited two characteristic peaks of Cu° and Cu+at 568.2 eV and 570.0 eV, respectively. The peak indicated by black arrows represents the different transition state. The existence of Cu+on Cu-100TCNQ was attributed to the charge transfer from Cu surface to anionic TCNQ2-.

[0051] Figure 12 shows Raman spectra of TCNQ molecule and Cu-100TCNQ. Ex-situ Raman spectroscopy confirmed the presence of the anionic TCNQ2-form in Cu-100TCNQ, with a significant shift to lower wavenumber in the C-CN wing stretching mode at 1455 cm-1and C-N stretching mode at 2229 cm-1for neutral TCNQ to 1392 and 2219 cm-1for Cu-100TCNQ.

[0052] Figure 13 shows TEM images of catalyst particles. Image (a) corresponds to Cu. Image (b) corresponds to Cu-100TCNQ.

[0053] Figure 14 shows XRD patterns. Scheme (a) is the XRD pattern of H23C3 carbon paper. Scheme (b) is the XRD patterns of Cu-100TCNQ and Cu. XRD pattern of Cu (PDF#04-0836) was used as the reference. Except for the characteristic peaks for H23C3 carbon paper, the new peaks located at 43.3°, 50.4°, and 74.1° were indexed to the (111), (200), and (220) facets of cubic Cu, respectively.

[0054] Figure 15 is the characterization of the cross-section of Cu-100TCNQ loading on H23C3 carbon paper. Image (a) is a SEM image. Images (b) and (c) are corresponding EDS mapping (Cu (b) and N (c)) images. The thickness of catalysts on carbon paper was about 8.9 pm.

[0055] Figure 16 shows the structure characterization of Cu-500TCNQ. Images (a) are STEM image and corresponding EDS mapping (Cu and N) images. Spectra (b), (c) and (d), are the high-resolution XPS of respectively N 1 s, Cu 2p, and Cu LMM.

[0056] Figure 17 represents the influence of TCNQ content on the distribution of products in CORR. Graph (a) shows CORR performance over Cu-500TCNQ in flow cell. Graph (b) shows the comparison of FE of gas products (H2and C2H4) over Cu, Cu-100TCNQ, and Cu-500TCNQ.

[0057] Figure 18 is a schematic diagram of the membrane-electrode assembly (MEA) system. The alkaline solution was used to humidify CO and remove residual trace CO2.

[0058] Figure 19 is a graph representing the full-cell voltage and corresponding current densities over Cu-WOTCNQ using NiFe-B and commercial lrO2 in the MEA, respectively.

[0059] Figure 20 is a graph showing faradaic efficiencies of all products under different applied current densities over bare Cu (patterned) and Cu-100TCNQ (solid filled) using commercial lrO2as the anode catalyst in the MEA.

[0060] Figure 21 is showing the difference in1H NMR spectra of liquid products collected from the anode side and cathode side using different anode catalysts in MEA. Spectra (a) and (b) correspond to commercial lrO2. Spectra (c) and (d) correspond to NiFe-B. A new triple peak at 0.9 ppm emerged on the anode side, which was absent on the cathode side. The new product was assigned to propanoic acid, which was oxidized from n-propanol.

[0061] Figure 22 is a graph representing the liquid product distribution over Cu-100TCNQ using NiFe-B as anode catalysts in the MEA. The FE for AcO' over NiFe-B was increased compared with that over lrO2. The FE for propionic acid was lower than 5 %.

[0062] Figure 23 is the high-resolution N 1s XPS of Cu-100TCNQ after stability test.

[0063] Figure 24 is a flow diagram of the techno-economic analysis (TEA) model used for the cascade CO2-CO-C2H4conversion process.

[0064] Figure 25 is a graph of the calculation of energy cost over Cu-100TCNQ and benchmark Cu based on the cascade CO2RR system. The calculation over Cu-100TCNQ was based on the CORR performance at a full-cell voltage of 2.39 V with a CO flow rate of 2.8 seem.

[0065] Figure 26 is a linear sweep voltammetry (LSV) of Cu and Cu-100TCNQ under CO atmosphere.

[0066] Figure 27 represents Operando Raman spectroscopic measurements at the range of applied potentials from -0.4 V to -0.7 V (vs RHE). Spectra (a) corresponds to Cu. Spectra (b) corresponds to Cu-WOTCNQ. The peak at 2180 cm-1was assigned to the vibration band of C = N in Cu-100TCNQ. Spectra (c) represents the fitting of operando Raman spectra of Cu and Cu-WOTCNQ at -0.5 V (vs RHE). The ratio of LFB-CO to HFB-CO over Cu-WOTCNQ and Cu was 7.2 and 0.9, respectively.

[0067] Figure 28 represents optimized unit cells used in this work. Image (a) corresponds to Cu(111).Image (b) corresponds to Cu(111)-TCNQ.

[0068] Figure 29 represents optimized geometries of adsorbed H2O molecule on (a) Cu(111) and (b) Cu(111)-TCNQ surfaces, respectively.

[0069] Figure 30 represents H2O dissociation processes. Images (a), (b) and (c) correspond to the initial-state (IS), transition-state (TS), and final-state (FS) geometries of H2O dissociation on Cu(111) and Cu(111)-TCNQ. Images (d), (e) and (f) correspond to the initial-state (IS), transition-state (TS), and final-state (FS) geometries of H2O dissociation on Cu(111) and Cu(111)-TCNQ.

[0070] Figure 31 represents Operando Raman spectroscopic measurements at the range of applied potentials from -0.4 V to -0.7 V (vs RHE). Spectra (a) correspond to Cu. Spectra (b) correspond to Cu-WOTCNQ. The presence of *CO was demonstrated by the Raman peaks located at around 281 cm-1, 300-400 cm-1, corresponding to the restricted rotation of *CO (Pi), Cu-CO stretching (P2), respectively. The vibration bands between 490 and 600 cm-1were assigned to adsorbed OH on Cu (Cu-OH). Graph (c) shows normalized Cu-OH intensity at the range of applied potentials from -0.4 V to -0.7 V (vs RHE). The Pi and P2band, reflecting the interaction between reaction intermediates and the Cu surface, changed with the applied potential in a and b. The intensity ratio of P2to Pi was assigned to the *CO coverage. The Cu-OH intensity was normalized by the intensity ratio of P2to Pi, which demonstrated the normalized Cu-OH intensity over Cu-100TCNQ was higher than that over Cu.

[0071] Figure 32 represents the effect of TCNQ modification on the *OH adsorption. Graph (a) shows the adsorption free energies. Images (b), are optimized geometries of adsorbed *OH at fee and hep sites of Cu(111) and Cu(111)-TCNQ.

[0072] Figure 33 represents the effect of *OH on interfacial H2O structure. Graph (a) shows the averaged distance of H2O molecules to catalyst surface on Cu(111)-TCNQ surface with and without *OH. Scheme (b) shows anchored H2O molecules and its increased O-H bond.

[0073] Figure 34 represents the path of *CHCOH to *CCH or *CHCHOH. Schemes (a), (b) and (c) are optimized geometries of adsorbed reaction intermediates: (a) *CHCOH, (b) *CCH, and (c) *CHCHOH on pure Cu(111) surface. Schemes (d), (e) and (f) are optimized geometries of adsorbed reaction intermediates: (d) *CHCOH, (e) *CCH, and (f) *CHCHOH on H2O-bound Cu(111) surface. Schemes (g), (h) and (i) are optimized geometries of adsorbed reaction intermediates: (g) *CHCOH, (h) *CCH, and (i) *CHCHOH on H2O(OH)-bound Cu(111) surface.

[0074] Figure 35 is a graph of Faradaic Efficiency (FE) and Single-pass conversion (SPC) in % for several electroreduction products with respect to current density in mA cm-2after electroreduction ofCO2in near-neutral electrolyte (0.1 M K2SO4and 0.5 M KHCO3) showing a maximum FE (C2H4) of 53%.

[0075] Figure 36 is a graph of potential of reversible hydrogen electrode E (vs. RHE) according to time (h) in the same conditions as per graph of Figure 35.DETAILED DESCRIPTION

[0076] Unlike other multi-carbon products of carbon oxide reduction (COR) (such as ethanol, acetate, and propanol), the generation of ethylene (C2H4) requires complete removal of oxygen atoms in carbon oxide (CO).

[0077] A major avenue to increase the production of multi-carbon (C2+) products has been to focus on the alkaline electrolyte, the goal to slow competing HER. HER kinetics decrease by orders of magnitude in alkaline electrolyte compared to acid electrolyte, linked to the high activation barrier of the alkaline Volmer step (H2O + e' — > *H + OH') reliant on the cleavage of a H-OH bond, viz. water dissociation. The present techniques provide another way to enhance water dissociation and favors the generation of carbon products, such as ethylene, in alkaline or neutral / near-neutral conditions.

[0078] A catalyst is proposed herein comprising a copper-based nanostructure comprising metallic copper atoms, and an organic compound being an electron acceptor and having at least one functional group comprising a nitrogen atom. The copper-based nanostructure is modified by the organic compound upon electronic transfer between copper atoms and nitrogen atoms. The at least one functional group comprising the nitrogen atom can be a cyano group, such as a dicyanomethylene group. For example, the organic compound can be 7, 7,8,8- tetracyanoquinodimethane (TCNQ). Optionally, an atomic percentage of nitrogen atoms in the catalyst is in the range of 2 at. % to 10 at. %, as determined by X-ray Photoelectron Spectroscopy (XPS) measurements.

[0079] The catalyst according to the present disclosure is a catalyst for electroreduction of CO, CO2or a mixture thereof into carbon products comprising ethylene. The catalyst includes: a copper-based nanostructure having a surface comprising copper atoms, and being a two- dimensional copper-oxide nanosheet; and an organic compound being an electron acceptor and having at least one functional group comprising a dicyanomethylene group;wherein the organic compound is ionically bonded to the copper atoms as determined by ex-situ Raman spectroscopy.

[0080] The proposed catalyst was developed by studying the competition for hydrogen between water dissociation, looking at CORR-to-C2H4vs. HER during electroreduction of CO in 1 M LiOH electrolyte. Using a conventional copper catalyst (as exemplified in Figure 5) operating in a flow cell (as exemplified in Figure 6). Water dissociation was tuned by altering the ratio of H2O to D2O in a 1 M LiOH electrolyte. The FE for H2(D2) decreased when the D2O ratio increased. The D2FE was inferior to 1 % in pure D2O (Figure 7). This result can be assigned to the sluggish dissociation of D2O. The C2+FE was also seen to increase with the decrease in H2 / D2FE.

[0081] It was also noted that the C2H4FE decreased with high D2O content under the same current (Figure 1a). The ratio of C2H4to oxygenate liquid products increased with voltage and current, i.e. , ethylene was favored at high overpotential. This ratio also increased with water content in the mixed electrolyte and reached 1.5 in H2O-1 M LiOH electrolyte at 300 mA cm-2(Figure 1 b). The Tafel slope (~118 mV / dec) and kinetic isotope effect (KIE) (1.6 - 1.9) for C2H4in all three electrolytes implicate water in the rate-determined step (RDS) of the CO-to-C2H4pathway (Figure 8). H2formation exhibited a similar trend to selectivity to C2H4: accelerating water dissociation promotes C2H4(Figure 1c).

[0082] The present catalyst was thus developed to favor water dissociation kinetics in Hydrogen Evolution Reaction (HER) by constructing electron-deficient active metal sites (in the copper-based nanostructure) with the unfilled d orbitals to immobilize the oxygen atom in water by the stronger electrostatic affinity. Molecular means, and more particularly an organic compound being used as a strong electron acceptor, are proposed to create electron-deficient active copper sites, thereby enhancing water dissociation at the heterogeneous catalyst surface.

[0083] A series of experiments which are further detailed below were performed by using 7, 7,8,8- tetracyanoquinodimethane (TCNQ) as the organic compound being an electron acceptor to form the proposed catalyst. TCNQ, one of the strongest organic electron acceptors, has been regarded as a prime candidate amongst organic / metal charge-transfer compounds. It is noted that neutral, planar TCNQ accepts two electrons from copper atoms to aromatize the central hexagonal ring and reduce both dicyanomethylene groups to the anionic form, TCNQ2-(see Figure 2a).

[0084] The strong electronic interaction between the organic electron acceptor and the copper atoms of the copper-based nano structure originating from charge transfer thus modifies a structure of the acceptor / metal interface, such as the TCNQ / Cu interface, which was shown to optimize theadsorption energy of intermediates, promoting the carbon-carbon (C-C) coupling to ethylene in CORR (as seen in Figure 2a).

[0085] Referring to the copper-based nanostructure of the catalyst, it is noted that a nanostructure refers herein to a nanosized structure. Although not limited to the listed structures, the nanostructure can be a nanosheet, a nanorod, a nanotube or a nanoparticle. The copper-based nature of the nanostructure can be understood as comprising copper atoms. For example, the nanostructure can include or consist of metallic copper (Cu). For example, the nanostructure can include or consist of copper oxide (CuO). For example, the nanostructure can be a copper nanoparticle or nanosheet. For example, the nanostructure can be a copper oxide nanosheet.

[0086] It is noted that when the copper-based nanostructure of the catalyst comprises or consists of copper oxide, the application of reduction conditions during electroreduction of CO2 / CO to carbon products using the catalyst will lead to a reduction of the CuO into Cu at the acceptor / metal interface.

[0087] In some implementations, the copper-based nanostructure is a two-dimensional (2D) copper oxide (CuO) nanosheet. The CuO nanosheet can be synthesized via a hydrothermal method (see the Methods section for details; Figures 9-10). The organic electron acceptor (organic compound) is TCNQ. When electroreduced, in-situ, the mixture of CuO and TCNQ yields to electronic transfer at the metal / organic compound interface which forms the catalyst. The formed catalyst can be referred to for example in the Figures as Cu-TCNQ (for Cu-TCNQ catalyst or related electrode), Cu-100TCNQ when including 100 pL of 10 mM TCNQ solution and Cu-500TCNQ when including 500 pL of 10 mM TCNQ solution.

[0088] High-resolution X-ray photoelectron spectroscopy (XPS) of N and Cu in Cu-100TCNQ shows the transfer of electrons from copper to anionic TCNQ2-(Figure 2b and Figure 11), consistent with the ex-situ Raman spectroscopy (Figure 12 and Table 1). Cu-100TCNQ exhibited no significant changes in morphology or crystalline reconstruction compared to bare Cu electrodes (SEM and TEM, Figure 2c and Figure 13, and X-ray diffraction (XRD), Figure 14). Cu and N elements were uniformly distributed in Cu-100TCNQ (STEM-EDS mapping, Figure 2d and Figure 15). Anionic TCNQ2-bonds the copper atoms by nitrogen in the cyano group.

[0089] Table 1. Peak assignments of TCNQ and Cu-100TCNQ in Raman spectroscopy.SampleAssignments -TCNQ Cu-IOOTCNQVC-N (cm4) 2229 2219 vc-c (crrr') 1603 16078C-CN (cm’1) 1455 1392AOCH (cm-1) 1207 1207

[0090] It is thus showed that an anionic form of the electron acceptor bonds the copper atoms by the nitrogen atom of nitrogen-containing functional groups, thereby forming an electron-deficient copper surface in the copper-based nanostructure. The metal active sites or electron-deficient metal surface is said to be produced in situ, i.e., upon application of an electrical current when the catalyst is implemented in an electroreduction system thereby triggering the electronic transfer at the acceptor / metal interface of the catalyst.

[0091] Thus, the organic electron acceptor is characterized by having nitrogen-containing functional groups to ionically bond with the copper atoms. More particularly, the organic compound being an electron acceptor has at least one functional group comprising a nitrogen atom. For example, the at least one functional group comprising the nitrogen atom is a cyano group. For example, the cyano group can be a dicyanomethylene group.

[0092] In some implementations, the organic electron acceptor being able to achieve charge-transfer with the metal can be perylene diimide. In some implementations, the electron acceptor can be 7,7,8,8-tetracyanoquinodimethane (TCNQ), tetracyanoethylene (TCNE), 2,3,5,6-Tetrafluoro-7,7,8,8- tetracyanoquinodimethane (F4TCNQ), perylene diimide or any combinations thereof.

[0093] Referring to Figure 3a, the CORR product distribution (C2H4, EtOH, n-PrOH, AcO; and H2) includes at least 90% C2+, with C2H4being the dominant CORR product. The Faradaic Efficiency (FE) for C2H4increased with an applied current density, while the FE towards EtOH and n-PrOH decreased. The organic compound TCNQ modification led to a peak FE for C2H4to 75% at 500 mA cm-2, compared to an FE for C2H4of 60% for bare copper catalyst. When the TCNQ concentration was further increased, the peak FE for C2H4was seen to decline (Figures 16 and 17 and Table 2). An optimized ratio of TCNQ (and thus nitrogen) in the catalyst was shown to achieve a ratio of C2H4to oxygenated liquid products being 2.3 times higher than for a bare Cu catalyst (Figure 3b).

[0094] Table 2. The average atomic ratio of N atoms in tested Cu-100TCNQ and Cu-500TCNQ. The results were determined by three independent XPS measurements.Samples N l.s (At. %)aCu-IOOTCNQ 3.5Cu-5OOTCNQ 8.8Atomic percentage.

[0095] There is further provided an electroreduction system for electroreducing CO, CO2or a combination thereof, and including the catalyst as described herein when implemented in a gas diffusion electrode (GDE) being used as a cathode. Additionally, there is provided a gas diffusion electrode for the electroreduction of CO, CO2or a mixture thereof into carbon products comprising ethylene, the gas diffusion electrode comprising a porous support and the catalyst as defined herein is deposited on the porous support.

[0096] It is noted that the catalyst can be implemented in the electroreduction system being a two- gap, one-gap, or zero-gap system. More particularly, the system includes a cathodic compartment comprising a reactant inlet that is configured to supply a gaseous stream comprising CO, CO2or the mixture thereof in the cathodic compartment, a cathode being the electrode as defined herein; and a product outlet configured to release a gas-liquid mixture comprising the carbon products from the cathodic compartment. The system further includes an anodic compartment comprising an anodic inlet that is configured to supply an anolyte in the anodic compartment, an anode, and an anodic outlet that is configured to release used anolyte from the anodic compartment. An ionic exchange membrane is further positioned between the cathodic compartment and the anodic compartment. The system further includes a voltage source that is operatively connected to the anode and the cathode to provide a current density that allows the gaseous stream, when supplied, to contact the catalyst to be electrochemically converted into the carbon products.

[0097] In some implementations, the system can be a zero-gap membrane electrode assembly (MEA) electrolyzer to minimize full cell voltage (Figure 18). Nickel-iron-boron (NiFe-B) catalyst was used to substitute commercial lrO2for oxygen evolution and obtained a full cell voltage of 2.39 V at 500 mA / cm2(Figure 19). The gas product distribution was similar when using different anode catalysts, except that partial EtOH and n-PrOH were further oxidized to AcO' and propanoic acid on the NiFe-B anode side, respectively (Figures 20-22, Table 3 and Table 4). The energy efficiency (EE) for C2H4reached a peak value of 32% with a C2H4partial current density of 442 mA cm-2(Figure 3c). The optimized single pass carbon efficiency (SPCE) for C2H4was 80% when the flow rate decreased to 1.6 seem (Figure 3d). In comparison with reported CO2RR / CORR catalysts, Cu-100TCNQ exhibited superior performance interms of faradaic efficiency and energy efficiency for C2H4(Figure 3e and Table 5). In stability studies, the catalyst retained FEC2H4 greater than 70% for >100 hours at 500 mA / cm2(Figure 3f). TCNQ remained on the Cu catalyst following this period of operation under CORR (Figure 23). A techno- economic analysis (TEA) was performed to assess the economic feasibility of C2H4electrosynthesis using the cascade CO2RR model (Figure 24 and Note 1 , see Materials and Methods section). An energy cost of 154 GJ / ton was estimated in the electrified production of C2H4(Figure 3g, Figure 25, Table 6 and Note 2, see Materials and Methods section).

[0098] Table 3. Gas product FEs for different electrodes under different applied current densities in the MEA. Error bars represent the standard deviation of three independent samples.Jtotal FEC2H4 FEH2Samples(mA cm’2) (%) (%)100 58.2±0.1 8.2±1.4200 63.H0.6 7.7±0.1300 66.4±1.6 7.0±0.6Cu-IOOTCNQ _400 69.7±0.7 6.5±0.3500 72.4±0.3 5.9±0.4600 73.7±0.1 6.5±0.3100 46.9±0.7 5.3±0.4200 55.2±1.5 7.5±0.6300 54.2±1.6 6.4±0.5Cu .400 57.H1.5 5.9±0.8500 61.3±0.5 6.0±0.4600 60.H1.3 6.7±0.1

[0099] Table 4. Liquid product distribution over Cu-100TCNQ under different applied current densities in MEA when using lrO2and NiFe-B anode catalysts. Error bars represent the standard deviation of three independent samples.Jtotal FEprOH FEpropanoic acid FEEIOH FEACO-Anode (mA cm’2) (%) (%) (%) (%)100 17.8±0.3 0 7.9±2.5 2.8±1.1200 14.H0.7 0 8.0±0.1 4.4±1.6300 7.9±0.6 0 11.9±2.4 5.0±1.9IrO2.400 10.2±1.3 0 8.4±1.5 3.6±0.9500 7.0±1.0 0 8.5±1.2 4.9±1.6600 6.H1.4 0 8.7±1.0 3.8±2.1100 13.8±1.5 5.H0.1 5.7±1.8 4.4±2.5200 10.6±0.9 4.3±1.0 5.9±1.8 6.3±3.0300 5.9±0.5 2.9±1.3 8.9±2.8 7.3±1.8NiFe-B .400 7.9±1.5 3.2±1.6 6.2±2.1 5.8±2.4500 6.H0.7 1.0±0.1 6.9±1.1 7.2±4.1600 4.5±0.9 2.4±1.2 6.H0.8 6.6±2.4

[0100] Table 5. Comparison of the maximum faradaic efficiencies and energy efficiencies for C2H4 over Cu-WOTCNQ and the start-of-the-art CO2 / CO catalysts. NA: not available.FEC2H4 Energy efficiencyCatalysts Feed gas Cell (%) for C2H4 (%)CO MEA 72.4 32Cu-100TCNQCQ flow cdl 75 NACu / Cu2O-S CO flow cell 46 NACuO-PS CO flow cell 53 NACu-Ppy CO flow cell 69 NACu:py:SSC CO MEA 65 28Cu-GDE CO MEA 40 17Cu3N CO MEA 40 11C / HKUST-CO2MEA 52 14.21 / Cu / PTFECu / Fe-N-C CO2MEA 63.5 16.9DVL-Cu CO2MEA 71 23.7CTPI CO2MEA 66 21

[0101] Table 6. Electrolyzer energy distribution comparison over Cu and Cu-100TCNQ in cascade systems.Catalyst Cu Cu-IOOTCNQFlow rate (seem) 20 5.5 2.8 1.6Cell voltage (V) 2.8 2.39 2.39 2.39Faradaic efficiency (%) 61.30 76.16 75.42 68.80Current density (mA cm' 500 500 500 5002)Single-pass carbon 9.25 31.98 62.82 97.65 efficiency (%)Energy consumptionCO input (GJ / ton) 83.30 63.75 64.39 62.70CORR electricity (GJ / ton) 125.92 86.51 87.36 95.76Cathode separation 16.52 4.53 2.15 1.48(GJ / ton)Overall Energy (GJ / ton) 225.74 154.79 153.91 159.94

[0102] Operando Raman measurements were used to investigate adsorbed CO (*CO) in each catalyst, for*CO is an intermediate to C2+ products. Linear sweep voltammetry (LSV) curves measured in operando Raman cell indicated the modification of TCNQ accelerated the C-C coupling over Cu in CORR (Figure 26). Raman features 1900-2200 cm-1correspond to C-O stretching (Figure 27). This includes two CO adsorption configurations, the low-frequency linear band CO (LFB-CO) 2060 cm-1and the HFB-CO band at 2095 cm-1. The LFB-CO peak exhibited dynamic shifting with applied potential, i.e. Stark tuning, while the inert HFB-CO remained constant. The LFB-CO to HFB-CO ratio was 8x higher for TCNQ compared to bare Cu. The higher ratio of LFB-CO suggests a weakened C=O bond, expected to facilitate C-C coupling, consistent with the LSV result.

[0103] These observations provide an account of high C2+ formation rate; attributes that are specific to C2H4production were then investigated. The D2O control experiments highlighted the influence of water dissociation on C2H4selectivity. LSV under Ar revealed higher HER activity in Cu- 100TCNQ than in Cu (Figure 4a), which indicated the water dissociation was enhanced in Cu- 100TCNQ. Density functional theory (DFT) calculations showed that the binding energy of H2O on Cu(111)-TCNQ (-0.7 eV) is lower than that on Cu(111) (-0.4 eV), i.e., H2O adsorbs on Cu(111)-TCNQ (Figure 4b, Figure 28 and Figure 29). From DFT, TCNQ lowers the water dissociation barrier (AEB) (1.12 eV) compared to Cu(111) (1.68 eV) (Figure 4c and Figure 30). Raman also showed enhanced water dissociation in CORR based on adsorbed OH (*OH) on Cu (Cu-OH), 490 - 600 cm-1, during water dissociation (H-OH cleavage) process (Figure 31), corresponding to DFT results (Figure 32). In molecular dynamics (MD) simulations, *OH exerts a strong attracting force to the H2O layer, bringing H2O closer to the surface and activating H2O as seen in a lengthened O-H bond (Figure 33).

[0104] Also, the effect of water dissociation on post hydrogenation of the *CHCOH intermediate was investigated with DFT - the key post C-C coupling intermediate to C2H4or EtOH - in CORR (Figure 4d). From the electronic configuration of *CHCOH on Cu(111)-TCNQ vs bare Cu, the charge density of the C-O bond decreased when the *CHCOH was adsorbed on the Cu(111)- TCNQ surface, i.e. the C-O bond was weakened after TCNQ modification (Figure 4e). With accelerated water dissociation kinetics by TCNQ molecule, the reaction pathway of *CHCOH to *CCH for C2H4, involving the breaking of the C-O bond, exhibits a more favourable Gibbs free energy compared to the *CHCOH to *CHCHOH pathway for EtOH (Figure 4f and Figure 34). It was concluded that the TCNQ modification enhanced water dissociation, further promoted the hydrogenation of *CHCOH to *CCH via breaking of the C-O bond, thus improved the C2H4selectivity in CORR.

[0105] In another aspect, there is provided a process for electroreduction of CO, CO2or a mixture thereof into carbon products comprising ethylene. The process is implemented in theelectroreduction system as defined herein. The process includes supplying the anolyte to the anodic compartment of the electroreduction system; supplying the gaseous stream comprising CO and / or CO2to the reactant inlet of the cathodic compartment of the electroreduction system for contacting the catalyst; and generating a reduction current via the voltage source through the electroreduction system to cause electroreduction of CO and / or CO2into the carbon products. The gas-liquid mixture comprising the carbon products is recovered from the product outlet of the cathodic compartment.

[0106] In some implementations, the process for electroreducing CO, CO2or a mixture thereof is performed using alkaline electrolyte(s), such as LiOH. In some implementations, the process for electroreducing CO, CO2or a mixture thereof is performed using neutral or near-neutral electrolyte(s), such as K2SO4, KHCO3, K2CO3 or a mixture thereof. The generating of the reduction current can include applying a current density between 100 mA. cm-2and 800 mA.cnr2. Optionally, the gaseous stream comprising CO2and / or CO can be supplied at an inlet flowrate between 1 .6 seem and 50 seem, further optionally between 15 seem and 25 seem.

[0107] Advantageously, the proposed catalyst design principle, which is based on activating water dissociation to promote the CO-to-C2H4pathway, results in C2H4FE of 75% at 500 mA cm-2in a flow cell (1.3 times improved compared with unmodified Cu controls). Moreover, a MEA system showed EE of 32% to C2H4corresponding to an energy cost of 154 GJ / ton for C2H4electrosynthesis.

[0108] In another aspect, there is provided a method for the preparation of the catalyst as defined herein. The method includes providing a plurality of the copper-based nanostructure in the form of a powder; forming a first solution by dissolving the organic compound in an organic solvent at a concentration from about 1 mM to about 50 mM, optionally from 2 mM to 30 mM; forming a dispersion by dispersing the powder in alcohol at a concentration from about 1 mg / mL to about 50 mg / mL, optionally, from 2 mg / mL to 30 mg / mL; and forming a mixture by adding the first solution to the dispersion under ultrasonication, wherein a ratio of a volume of the first solution to a volume of the dispersion is from about 0.02 to about 0.3, optionally from 0.01 to 0.2, and further optionally from 0.05 to 0.10 . The method further includes forming an ink by adding a binder such as Nation® to the mixture under ultrasonication, wherein the ratio of a volume of Nation® to a volume of the mixture is from about 0.01 to about 0.05, optionally from 0.02 to 0.04; and spray-coating the ink onto a porous support to form a catalytic layer with a loading amount of at least 1 mg. cm-2. The catalyst is finalized in situ by applying a reduction current to the catalytic layer to obtain the catalyst comprising the organic compound being ionically bonded to the copper atoms at the interface of the copper-based nanostructures upon transferring electrons therebetween. A method implementation is exemplified in the materials and methods section below.MATERIALS AND METHODS

[0109] Further details regarding materials and methods that were used to gather experimental results described or shown in the present description and accompanying Figures are provided below.Materials

[0110] Copper (II) chloride dihydrate (CuCI2H2O, 99.95%), sodium dodecyl benzenesulfonate (CH3(CH2)nC6H4SO3Na, AR), 7,7,8,8-tetracyanoquinodimethane (TCNQ, 98%), anhydrous acetonitrile (CH3CN, 99.8%), lithium hydroxide (LiOH, 99.9%), potassium sulfate (I^SO^ 99%), potassium bicarbonate (KHCO3, 99.7%), anhydrous iron (III) chloride (FeCI3, >99.99%), nickel (II) chloride hexahydrate (NiCI26H2O, 99.9%), sodium borohydride (NaBH4, >98.0%), Nation® perfluorinated resin solution (5 wt. % in mixture of lower aliphatic alcohols and water, contains 45% water), ethanol (>99.5%), methanol (>99.5%), deuterium oxide (D2O, 99.9%) was purchased from Sigma-Aldrich. Sodium hydroxide (NaOH, GR) was purchased from Caledon Laboratory Chemical. Copper (nanopowder, 25 nm particle size) was purchased from US Research nanomaterials, Inc. Anion exchange membranes (Sustainion x37-50-grade-60) were purchased from Dioxide Materials. Anion exchange membranes (Fumasep FAB-PK-130), Pention-D18-5wt% Dispersion, and Teflon™ PTFE DISP 30 Fluoropolymer Dispersion, carbon paper-based gas diffusion layers (GDLs, Freudenberg H23C3) were purchased from Fuel Cell Store. Commercial iridium oxide (lrO2) anode (Titanium fiber felt, 200 mm- 100 mm-0.3 mm. Fibre felt coated with Ir-MMO.) was purchased from Magneto Special Anodes. Ultrapure Millipore water (resistivity 18.2 MQ cm) was used for all experiments. All chemicals were used without further purification.Synthesis of CuO nanosheets

[0111] The synthesis of CuO nanosheets was carried out using a modified hydrothermal method. 1.70 g of CuCI22H2O and 3.48 g of CH3(CH2)nC6H4SO3Na were dissolved into 25 mL of deionized water, while stirring continuously at 25°C. Subsequently, 15 mL of 4 M NaOH was slowly added to the solution. The resulting dark blue solution was then placed in a 50 mL Teflon-lined stainless autoclave and subjected to a hydrothermal reaction for 24 hours at 120 °C in an oven. After cooling to room temperature, the black precipitate was obtained and washed three times using water and ethanol, followed by centrifugation, and drying. Finally, the powder was sintered at 300 °C for 2 hours in the air to eliminate any residual organic matter.

[0112] In other embodiments, the nanosized CuO can be in the form of nanoparticles.Preparation of the Cu-x (x=0, 100, 500) TCNQ electrodes

[0113] To prepare the TCNQ / CH3CN solution, TCNQ was dissolved in CH3CN at a concentration of 10 mM. Next, 20 mg of CuO powder was dispersed in 3 mL of methanol. Subsequently, to prepare the Cu-100TCNQ electrode, 100 pL of TCNQ / CH3CN was added to the above mixture under ultrasonication for 30 minutes. Afterward, 80 pL of Nation® was added, and the mixture was ultrasonicated for another hour to prepare the ink. The resulting suspension was spray- coated onto a 3x3 cm2H23C3 carbon paper to prepare the CuO-100TCNQ electrode with a loading amount of at least 1 mg cm-2. The Cu-100TCNQ electrode was prepared by in-situ electroreducing the CuO-100TCNQ under the CORR condition. The preparation of the Cu-500TCNQ and Cu electrodes followed a similar process, except that 500 pL and 0 pL TCNQ / CH3CN solution were added to the ink, respectively.

[0114] In other implementations, the organic solvent used to dissolve TCNQ and without being limiting can be selected from aprotic polar solvents, namely from the group comprising acetonitrile, tetra hydrofuran, dichloromethane, chloroform, or any mixture thereof.

[0115] In other implementations, the CuO powder can be dispersed in one or more polar protic solvents, such as any alcohol, including methanol, ethanol, propanol, and isopropanol.Preparation of NiFe-B anode electrodes

[0116] The NiFe-B catalysts were synthesized using a previously reported method with small modification. Specifically, NiCI26H2O (332.8 mg) and anhydrous FeCI3(227.1 mg) were dissolved in 2 mL of deionized water. In a separate vial, a solution of NaBH4(2 mL, 5 M) in water was prepared. To prevent uncontrolled hydrolysis and consideration that may lead to the formation of precipitates, all solutions were cooled in an ice bath for 10 min. The Ni and Fe precursors were then added dropwise to a 2 mL NaBH4aqueous solution. The resulting black solution was washed and centrifuged with water and ethanol three times before vacuum drying.

[0117] To prepare the ink for the NiFe-B anode electrodes, 80 mg of the NiFe-B powder, 200 pL of Pention-D18-5wt% dispersion, and 640 pL of PTFE aqueous solution (dilute PTFE DISP 30 Fluoropolymer Dispersion to 10 mg / mL) were dispersed in 6 mL of methanol under ultrasonication for 1 hour. The resulting suspension was then spray coated onto the 2.5x5 cm2lrO2with a loading amount of 3 mg cm-2.Electrochemical experiments

[0118] The CORR experiments were carried out using a three-electrode flow cell electrolyzer or membrane electrode assembly (MEA), as illustrated in the detailed sketches (Figures 6 and 18).In the flow cell, the cathode consisted of a gas diffusion electrode (GDE), while the anode was made of platinum mesh. A reference electrode filled with saturated KCI solution and made of Ag / AgCI was used. To prevent product crossover, an anion exchange membrane (Fumasep FAB-PK-130) was utilized to separate the catholyte and anolyte compartments. The Autolab PGSTA204 module from Metrohm Autolab, along with a BOOSTER10A module, was used as the power supply for the experiments.

[0119] Alkaline solution with 1 M LiOH electrolyte was employed as the electrolyte at both the cathode and anode side, and the cathode and anode compartments were supplied with the electrolyte separately using two variable-speed peristaltic tubing pumps. A flow of 20 standard cubic centimeters per minute (seem) CO gas was directed towards the catholyte interface through the gas diffusion layer. Linear sweep voltammetry (LSV) data were collected by sweeping the electrode in the flow cell at a scan rate of 100 mV / s under N2and CO atmosphere, respectively.

[0120] All the applied cathode potentials in the flow cell were converted to the reversible hydrogen electrode (RHE) reference scale with a standard compensation by:E (V vs RHE) = E(V vs Ag / AgCI) + 0.197 + 0.059 x pH - 90% x i x RWhere pH was 14 for 1M LiOH electrolyte, R was the solution resistance, which was determined to be 5.2 ohm in 1 M LiOH electrolyte by Electrochemical Impedance Spectroscopy (EIS) measurement. A factor of 90% was applied in iR compensation during flow cell operation. The CORR in D2O- electrolyte was performed with similar procedures except for replacing H2O with D2O.

[0121] The MEA was composed of a cathode electrode, an lrO2(or NiFe-B) anode electrode, and an anion exchange membrane (Sustainion X37-50-grade60). The electrochemical testing cell was assembled by placing the membrane between the cathode and anode electrode, in which the catalyst layers of both electrodes were facing the membrane. The anode catalyst was protected and surrounded by a 0.02-inch-thick gasket for electrical insulation. The reaction area was regulated by the pore area in the gasket, which was set at 1 cm2. This assembly was then inserted into a fuel cell hardware from Dioxide Material, which had serpentine flow channels that were equally compressed with torque applied to the bolts. A constant rate of 15 mL min-1of 1 M LiOH anolyte flowed through the anodic channel, and a digital mass flow meter supplied the humidified CO feed gas to the cathodic channel at a constant rate of 20 seem. After the electrolyzer assembly, a galvanostatic method was used to apply the electrolyzer, and the current density was gradually increased from an initial 50 mA cm-2with increments of 50 mA cm-2. The current increments were made upon complete stabilization of the corresponding voltage. For the stability test, the MEA was operated at a constant full-cellcurrent density of 500 mA cm-2, and 1 L of 1 M LiOH electrolyte was prepared to ensure that the electrolyte composition remained constant during the long electrolysis process.

[0122] Referring to Figures 35 and 36, further experiments were conducted in a flow cell to evaluate CO2RR to ethylene in 0.1 M K2SO4+ 0.5 M KHCO3over a three-electrode flow cell electrolyzer. In the flow cell, the cathode consisted of a gas diffusion electrode (GDE), while the anode was made of lrO2. A reference electrode filled with saturated KCI solution and made of Ag / AgCI was used. To prevent product crossover, an ion exchange membrane was utilized to separate the catholyte and anolyte compartments. The Autolab PGSTA204 module from Metrohm Autolab, along with a BOOSTER10A module, was used as the power supply for the experiments. The set-up is shown in Figure 6. A 53% efficiency for ethylene was obtained, showing that the modified catalyst allowed for CORR and CO2RR in both alkaline and neutral / near-neutral conditions. It is noted that imilar maximum C2H4 FE were obtained with both anion exchange membrane and cation exchange membrane under near-neutral condition.

[0123] It should be noted that implementations of the catalyst and related processes that are exemplified in relation to alkaline conditions can be applied to neutral or near-neutral electroreduction conditions.

[0124] In other embodiments, the current density applied is between 100 mA.cnr2and 800 mA. cm-2.

[0125] The gas products were collected in 1 mL volume using gas-tight syringes (Hamilton chromatography syringe) and then injected into offline gas chromatography (GC2014, Shimadzu, Japan) for analysis. The GC used for gas product analysis had two detectors: a flame ionization detector was used to detect C2H4, while a thermal conductivity detector (TCD) was used to detect H2. The spectra obtained from the GC for each gas injection were used to calculate the FE towards the gas product of CORR. Liquid products were analyzed by1H nuclear magnetic resonance (NMR) spectroscopy (600 MHz, Aligent DD2 NMR spectrometer) with water suppression, in which 0.1 mL of the electrolyte was mixed with 0.1 mL DMSO (internal standard, diluted to 100 ppm (m / m) by D2O) and 0.4 mL D2O. In the MEA test, the liquid products from the cathode side were separated and collected by a cold trap. The FE for liquid products was calculated by collecting the products from both the anode and cathode sides during the same period.

[0126] The full-cell energy efficiency (EE) of C2H4in the MEA was calculated by the following equation:Where EC2H4O= 0.17 V is the equilibrium potential for CO to C2H4product.3EfUn-ceii is the full-cell voltage without ohmic loss correction in the MEA system.The single pass carbon efficiency (SPCE) was calculated based on the following equation under 1 atm and 25 °C:Where / is the total current, FECis the faradaic efficiency for specific multi-carbon product, v is the flow rate of inlet CO feed gas, e is the number of electron transfers for one carbon atom in specific multi-carbon product F is the Faraday constant (96485 C / mol).Characterizations

[0127] The morphologies of samples were recorded by SEM (Hitachi FE-SEM SU5000 microscope) and TEM (Hitachi H-7650). HRTEM images and scanning transmission electron microscopy energy-dispersive spectra (STEM-EDS) elemental mapping were carried out on a Themis Z field-emission transmission electron microscope, and the accelerating voltage was 200 kV. X-ray diffraction patterns were recorded by using MiniFlex600 with Cu-Ka radiation (A = 1.54178 A). X-ray photoelectron spectroscopy (XPS) measurements were carried out on PerkinElmer model 5600 with a monochromatic aluminum X-Ray source. The binding energies were corrected for specimen charging by referencing C 1s to 284.6 eV. Ex-situ Raman spectra were conducted using a Renishaw in Via Raman Microscope with a 532 nm laser.Operando Raman measurements

[0128] Operando Raman measurements were conducted using a modified flow cell, which employed a Renishaw in Via Raman Microscope equipped with a water immersion objective (x 63) lens with a 785 nm laser at 0.1 % intensity. 0.1 M LiOH electrolyte was used to minimize the fluorescence effect on the Raman spectra. Each spectrum was recorded using the Renishaw WiRE (version 4.4) software by integrating twice, with each integration lasting 10 s. CO was continuously supplied to the gas chamber during the measurement. The potential in Raman measurements were converted to the values versus RHE.Operando XAS measurements

[0129] Operando XAS measurements were conducted at a multipole wiggler XAS beamline in a home-made flow cell. Its only difference with the flow cell used to evaluate CORR performances was the use of Kapton tape to seal the gas chamber to allow for X-Ray irradiation in and fluorescent signal out. The XAS spectra were obtained at different galvanostatic tests and processed using ATHENA and ARTEMI E software including a standard IFEFFIT package.Computational methods

[0130] Density functional theory (DFT) was applied to investigate the ethylene production mechanism on Cu and TCNQ-modified Cu surfaces. All the DFT calculations were carried out in the Vienna ab initio simulation package with a plane wave pseudo-potential implementation. The exchange-correlation function was described by the spin-polarized generalized gradient approximation of Perdew-Burker-Ernzerhof and the electron-ion interactions were described by projector augmented wave potentials. The kinetic cut-off energy of 450 eV was used for the plane- wave expansion. The 3 x 2 x 1 and 6 x 4 x 1 Monkhorst-Pack k-point meshes were used for geometry optimization and electronic structure calculation. The long-range Van de Waals interactions were described by the zero-damping DFT-D3 method of Grimme et al.

[0131] Cu(111) surface was specifically selected since the (111) surface is found to be the dominant surface in the Cu-based electrocatalyst material utilized in this work, which is proved by the XRD measurements. A 6 x 4 x 4 periodic cell of face-centered cubic Cu(111 )-TCNQ surface was initially constructed for TCNQ-modified Cu surface. The Cu(111)-TCNQ surface with the lowest energy was used for the further investigation of the reactions. To decouple the interaction between them, a 15 A of vacuum space was set among the periodic surfaces in the z-direction. To reduce the computational cost, only the metal atoms and adsorbates were allowed to relax during the structural optimization calculations, while the atoms in the two bottom-most layers were fixed.

[0132] The computational hydrogen electrode model was used to calculate the Gibbs free energy by correcting the electronic energies directly determined from DFT calculations with Zero- point energies, entropies, and heat capacities, which are calculated from harmonic oscillator approximation at 298.15 K. The climbing-image nudged elastic band method was applied to search the transition state of H2O dissociation on Cu(111) and Cu(111)-TCNQ surfaces, which were then verified by the imaginary frequency calculation.

[0133] Charge-density difference was applied to investigate the charge transfer between the *CHCOH intermediate and surface. To study the effect of TCNQ on the interfacial water layer, twelve water molecules were introduced to Cu(111)-TCNQ surfaces. To optimize the interfacial water structure, Ab initio molecular dynamics (MD) simulations were conducted in canonical ensemble (NVT) for 15 ps with the Nose-Hoover thermostat and a 1.0 fs time step at 300 K. DFT calculation were again perform for the optimized geometry from AIMD to get the final interfacial water layer structure.Note 1: Techno-economic analysis (TEA) of a cascade CO2-CO-C2H4 system.

[0134] This TEA was performed using TEA models adopted from that reported work. The model uses a process that is shown in Figure 24. The model assumes a fixed energy input for the CO2capture step and the SOEC step to produce CO2(4 GJ / ton CO2) and CO (20 GJ / ton CO), respectively. Then the model uses the performance metrics of the COR system to estimate the energy intensity of producing per ton of C2H4. These metrics include full-cell potential, single pass CO2conversion efficiency, Faradaic efficiency (towards different products) and current density. To recover C2H4from the unreacted CO and H2, a pressure swing adsorption (PSA) module is modelled to be at the cathodic downstream. The CO recovered from the cathodic stream is modelled to be recirculated back to the cathode inlet for re-utilization in CORR. An example energy cost calculation for the upstream CO2capture, SOEC, CORR, and downstream gas separation is provided in Note 2.Note 2: Example energy cost calculation for the cascade CO2-CO-C2H4 conversion.

[0135] This section provides an example calculation of the energy cost associated with upstream CO2capture, SOEC, CORR, and downstream gas separation. The calculation details are based on the performance metrics that enable the lowest energy intensity of producing C2H4. These metrics include a full-cell voltage of 2.39 V, a C2H4FE of 75.42%, a SPCE of 62.82%, and a current density of 500 mA cm-2for the CORR step.

[0136] Upstream CO2capture and SOEC energy cost. We assume CO2is captured from industrial flue gases using amine-based capture and regeneration with an energy intensity of 4 GJ / ton CO2. We then convert the CO2capture energy cost needed to per ton CO.

[0137] The energy cost to produce one ton of CO by SOEC is assumed to be 20 GJ / ton. This cost includes the electricity input to the electrolyzer as well as the sequential separation step to obtain > 99% CO. The unreacted CO2is then recirculated back to the inlet of the electrolyzer for reaction, so no additional CO2is needed to be captured. Together with the upstream CO2cost (6.29 GJ / ton CO), the total cost to produce one ton of CO is calculated to be 26.29 GJ / ton.

[0138] We consider the total amount of CO input to all products (C2H4, ethanol, acetate, and n-propanol) and normalize it to per ton of C2H4produced. Therefore, CO converting to products other than C2H4is not considered recoverable. We then calculate the total energy cost for the input CO of the CORR system. Here we provide the calculation by using the lowest energy case as an example with the following FE distributions: FEC2H4= 75.42%, FEethanoi = 6.80%, FEacetate = 3.40%, FEn-Propanoi = 3.36%.

[0139] We first calculate the production rate in (mol / s) of C2H4for a constant C2H4production capacity of 100 tons per day.

[0140] We calculate the current needed to produce C2H4at this production capacity with a FE of 75.42%:

[0141] Next, we can calculate the total CO requirement in mol per second by summing up the CO requirements towards each of the products.96485 - mo7l mol= 101.33 - s

[0142] The CO requirement can be converted to the CO requirement to produce 1 ton ofC2H4. toncoCO requirement ionC2H4capacity factor [tonC2fj4]86400s 28g 1 ton tonco101.33 —5 - x — x - — .day mol 1 x 106gCO requirement ionC2H4100 tonC2H4

[0143] Based on the CO requirement, the total energy cost to obtain the required CO to produce one ton of C2H4(CO2capture and SOEC energy cost) can be calculated.

[0144] CORR energy cost. Based on the total current required for a constant C2H4production capacity of 100 tons per day, we calculate the power consumption by multiplying the current with the full-cell potential of the CORR electrolyzer (2.39V).Power Consumed [1 / K] =Total current needed [X] x Cell voltage [V] = 42 309 095 A x 2.39 V = 101 119 kWWe find the total energy input to produce 100 tons of C2H4per day:

[0145] Downstream gas separation energy cost. We assumed a pressure swing adsorption (PSA) separation module to calculate the energy cost associated with the separation of C2H4, H2, CO from the cathodic downstream. hPSA operating energy x 24— — day

[0146] We estimate the flow rate of each product at the cathodic stream. Assuming operation under the ideal conditions, we estimated the flow rate of C2H4:

[0147] We then estimate the flow rates of unreacted CO at the cathodic stream. The flow rate of CO at the cathodic stream is calculated by using the SPCE. We then calculate the output unreacted CO flow rate using a SPCE of 62.82%:

[0148] We then calculate flow rate for H2:

[0149] Assuming the produced H2as an ideal gas under standard conditions, the flow rate ofH2can be calculated:

[0150] The total flow rate of the cathodic stream can then be calculated by adding the flow rates of C2H4, unreacted CO, and H2:

[0151] We then calculate the total energy required to operate the PSA separation module:

[0152] Total energy cost. The total energy cost to produce one ton of C2H4can be calculated by summing up all cost discussed above:

[0153] It should be noted that the same numerical references refer to similar elements. Furthermore, for the sake of simplicity and clarity, namely so as to not unduly burden the figures with several references numbers, not all figures contain references to all the components and features, and references to some components and features may be found in only one figure, and components and features of the present disclosure which are illustrated in other figures can be easily inferred therefrom. The embodiments, geometrical configurations, materials mentioned and / or dimensions shown in the figures are optional, and are given for exemplification purposes only. Therefore, the descriptions, examples, methods and materials presented in the claims and the specification are not to be construed as limiting but rather as illustrative only.

[0154] It is worth mentioning that throughout the following description when the article “a” is used to introduce an element it does not have the meaning of “only one” it rather means of “one or more”. It is to be understood that where the specification states that a component, feature, structure, or characteristic “may”, “might”, “can” or “could” be included, that particular component, feature, structure, or characteristic is not required to be included.

[0155] In the above description, the term “about” means within an acceptable error range for the particular value as determined by one of ordinary skill in the art, which will depend in part on how the value is measured or determined, i.e. , the limitations of the measurement system. It is commonly accepted that a 10% precision measure is acceptable and encompasses the term “about”.

[0156] In the above description, an embodiment is an example or implementation of the inventions. The various appearances of “one embodiment,” “an embodiment” or “some embodiments” do not necessarily all refer to the same embodiments. Although various features of the invention may be described in the context of a single embodiment, the features may also be provided separately or in any suitable combination. Conversely, although the invention may be described herein in thecontext of separate embodiments for clarity, the invention may also be implemented in a single embodiment.

[0157] It should be understood that any one of the aspects methods, CORR systems, copper- based catalyst containing electrode and use thereof may be combined with any other of the aspects thereof, unless two aspects clearly cannot be combined due to their mutually exclusivity.All publications that are identified herein are incorporated herein by reference.1. Ozden, A. et al. Cascade CO2electroreduction enables efficient carbonate-free production of ethylene. Joule 5, 706-719 (2021).2. Huang, X. et al. Copper-tetracyanoquinodimethane-derived copper electrocatalysts for highly selective carbon dioxide reduction to ethylene. Nano Res. 15, 7910-7916 (2022).3. Li, J. et al. Constraining CO coverage on copper promotes high-efficiency ethylene electroproduction. Nat. Catal. 2, 1124-1131 (2019).

Claims

CLAIMS1 . A catalyst for electroreduction of CO, CO2or a mixture thereof into carbon products comprising ethylene, wherein the catalyst comprises: a copper-based nanostructure having a surface comprising copper atoms, and being a two- dimensional copper-oxide nanosheet; and an organic compound being an electron acceptor and having at least one functional group comprising a dicyanomethylene group; wherein the organic compound is ionically bonded to the copper atoms as determined by ex-situ Raman spectroscopy.

2. The catalyst of claim 1 , wherein the catalyst has an atomic percentage of nitrogen atoms ranging between 2 at.% and 10 at.% based on the total atomic content of the catalyst, as determined by X- ray Photoelectron Spectroscopy measurements.

3. The catalyst of claim 1 or 2, wherein the catalyst has an atomic percentage of nitrogen atoms ranging between 2 at.% and 4 at.% based on the total atomic content of the catalyst, as determined by X-ray Photoelectron Spectroscopy measurements.

4. The catalyst of any one of claims 1 to 3, wherein the copper atoms show a face centered cubic crystal structure with at least one of (111), (200), or (220) facets.

5. The catalyst of any one of claims 1 to 4, wherein the organic compound is selected from 7, 7,8,8- tetracyanoquinodimethane (TCNQ), tetracyanoethylene (TCNE), 2,3,5,6-tetrafluoro-7,7,8,8- tetracyanoquinodimethane (F4TCNQ), and a mixture thereof.

6. The catalyst of any one of claims 1 to 5, wherein the organic compound is 7, 7,8,8- tetracyanoquinodimethane (TCNQ).

7. A method for the preparation of a catalyst for electroreducing CO, CO2or a mixture thereof into carbon products comprising ethylene, the method comprising: a) providing a copper-based nanostructure being a two-dimensional copper-oxide nanosheet in the form of a powder; b) forming a dispersion by dispersing the powder provided at step (a) in one or more polar protic solvents; c) providing an organic compound which is an electron acceptor and has at least one functional group comprising a dicyanomethylene group;d) forming a solution by dissolving the organic compound provided at step (c) in an organic solvent; e) forming a mixture by adding the solution of step (d) to the dispersion of step (b) under ultrasonication, wherein a ratio of a volume of the first solution to a volume of the dispersion is from 0.02 to 0.3; f) forming an ink by adding a binder to the mixture of (e) under ultrasonication; g) providing a porous support; h) spray-coating the ink formed at step (f) onto the porous support provided at step (g) to form a catalytic layer with a loading amount of at least 1 mg. cm-2; and i) applying a reduction current to the catalytic layer to obtain in-situ the catalyst comprising the organic compound being ionically bonded to the copper atoms of the surface of the copper- based nanostructures as determined by ex-situ Raman spectroscopy upon transferring electrons therebetween.

8. The method of claim 7, wherein the concentration of the copper-based nanostructure within the dispersion formed at step (b) is ranging from 1 mg / mL to 50 mg / mL.

9. The method of claim 7 or 8, wherein the concentration of the copper-based nanostructure within the dispersion formed at step (b) is ranging from 2 mg / mL to 30 mg / mL.

10. The method of any one of claims 7 to 9, wherein the concentration of the organic compound in the solution formed at step (d) is ranging from 1 mM to 50 mM.11 . The method of any one of claims 7 to 10, wherein the concentration of the organic compound in the solution formed at step (d) is ranging from 2 mM to 30 mM.

12. The method of any one of claims 7 to 11 , wherein the one or more polar protic solvents are one or more compounds with at least one hydroxylic group.

13. The method of any one of claims 7 to 12, wherein, the one or more polar protic solvents are selected from methanol, ethanol, propanol and isopropanol or any mixture thereof.

14. The method of any one of claims 7 to 13, wherein the organic solvent of step (d) are one or more polar aprotic solvents.

15. The method of claim 14, wherein said one or more polar aprotic solvents are selected from acetonitrile, tetrahydrofuran, dichloromethane, chloroform or any mixture thereof.

16. The method of any one of claims 7 to 15, wherein a ratio of a volume of the solution to a volume of the dispersion is from 0.01 to 0.2.

17. The method of any one of claims 7 to 16, wherein a ratio of a volume of the solution to a volume of the dispersion is from 0.05 to 0.10.

18. The method of any one of claims 7 to 17, wherein the binder comprises one or more perfluorinated sulfonic acid ionomers being selected from 1 ,1 ,2,2-tetrafluoroethene and 1 ,1 ,2,2-tetrafluoro-2- [1 ,1 ,1 ,2,3,3-hexafluoro-3-(1 ,2,2-trifluoroethenoxy)propan-2-yl]oxyethanesulfonic acid.

19. The method of any one of claims 7 to 18, wherein the ratio of a volume of the binder to a volume of the mixture formed at step (e) is from 0.01 to 0.05.

20. The method of any one of claims 7 to 19, wherein the ratio of a volume of the binder to a volume of the mixture formed at step (e) is from 0.02 to 0.04.21 . A gas diffusion electrode for the electroreduction of CO, CO2or a mixture thereof into carbon products comprising ethylene, the gas diffusion electrode comprising: a porous support; the catalyst as defined in any one of claims 1 to 6 being deposited on the porous support.

22. The gas diffusion electrode of claim 21 , wherein the porous support is polytetrafluoroethylene (PTFE).

23. The gas diffusion electrode of claim 21 , wherein the porous support is porous carbon paper.

24. A system for electroreduction of CO, CO2or a mixture thereof into carbon products comprising ethylene, the system comprising: a cathodic compartment comprising: a reactant inlet that is configured to supply a gaseous stream comprising CO, CO2or the mixture thereof in the cathodic compartment, a cathode being the gas diffusion electrode as defined in any one of claims 21 to 23; a product outlet configured to release a gas-liquid mixture comprising the carbon products from the cathodic compartment;an anodic compartment comprising: an anodic inlet that is configured to supply an anolyte in the anodic compartment, an anode, and an anodic outlet that is configured to release used anolyte from the anodic compartment; an ionic exchange membrane that is positioned between the cathodic compartment and the anodic compartment; and a voltage source that is operatively connected to the anode and the cathode to provide a current density that allows the gaseous stream, when supplied, to contact the catalyst to be electrochemically converted into the carbon products.

25. The system of claim 24, wherein the anode is or comprises NiFe-B.

26. The system of claim 25, wherein the anode is or comprises lrO2.

27. The system of any one of claims 24 to 26, being a flow cell and wherein the cathodic compartment further comprises a catholyte inlet being supplied with a catholyte.

28. The system of any one of claims 24 to 26, being a zero-gap electrolyzer.

29. The system of claim 28, being a membrane electrode assembly.

30. A process for electroreduction of CO, CO2 or a mixture thereof into carbon products comprising ethylene, the process comprising: a) providing the system as defined in any one of claims 24 to 29; b) supplying the anolyte to the anodic compartment of the system provided at step (a); c) supplying the gaseous stream comprising CO and / or CO2to the reactant inlet of the cathodic compartment of the system provided at step (a) for contacting the catalyst; and d) generating a reduction current via the voltage source through the system to cause electroreduction of CO and / or CO2into the carbon products; and e) recovering the gas-liquid mixture comprising the carbon products from the product outlet of the cathodic compartment.31 . The process of claim 30, wherein the anolyte is an alkaline electrolyte.

32. The process of claim 31 , wherein the alkaline electrolyte is LiOH.

33. The process of any one of claims 30 to 32, wherein the system is a flow cell and wherein the cathodic compartment further comprises a catholyte inlet that is configured to be supplied with a catholyte.

34. The process of claim 33, wherein the catholyte is an alkaline electrolyte.

35. The process of claim 34, wherein, the alkaline electrolyte is LiOH.

36. The process of claim 33, wherein the catholyte is a neutral.

37. The process of claim 36, wherein the catholyte is K2SO4, KHCO3, K2CO3or a mixture thereof.

38. The process of any one of claims 30 to 37, wherein step (d) comprises applying a current density between 100 mA.cm-2and 800 mA. cm-2.

39. The process of claim 38, wherein step (d) comprises applying a current density between 100 mA.cnr 2 and 600 mA.cnr2.

40. The process of any one of claims 30 to 39, wherein step (c) is performed at an inlet flowrate between 1 .6 seem and 50 seem.41 . The process of claim 40, wherein step (c) is performed at an inlet flowrate between 15 seem and 25 seem.

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