Metal gas diffusion electrode, manufacturing method, and working electrode

Abstract

The present application provides a metal gas diffusion electrode and a manufacturing method therefor. The metal gas diffusion electrode comprises a substrate layer, a bifunctional copolymer layer, and a metal layer which are successively stacked, wherein the bifunctional copolymer layer is tightly connected to the substrate layer and the metal layer by means of chemical bonds, respectively. Since chemical bonding can overcome the problems of poor conductivity due to physical adhesion, active site coverage, easy peeling during testing, and a complex electrode manufacturing process, the electrode stability can be remarkably improved. In addition, by optimizing the hydrophobic and gas-permeable properties of the substrate layer and regulating the degree of polymerization / thickness of the bifunctional copolymer layer, the microenvironment near the catalyst surface can be remarkably improved, effectively improving the electrocatalytic CO2 reduction reaction activity and the multicarbon product selectivity. Furthermore, by incorporating a widely applicable metal layer growth strategy, the activity and selectivity of single products, especially multicarbon products, can be regulated through the selective optimization of different types of single metals or multi-component alloys.

Description

Metal vapor diffusion electrode, preparation method and working electrode Technical Field

[0001] The present application relates to the technical field of electrocatalytic CO2 reduction reaction, and in particular to a metal vapor diffusion electrode, a preparation method and a working electrode. Background Art

[0002] Using renewable green electricity to catalyze the reduction of CO2 into high-value-added fuels or bulk chemicals is an important means to achieve the "resource" utilization of CO2, contribute to the country's "dual carbon" strategic goals, and solve the "energy crisis". However, due to the extremely high thermodynamic stability of CO2 molecules, the reaction activity is very low; secondly, the reduction of CO2 involves multiple proton / electron transfer processes, resulting in poor selectivity for single products, especially high-value, high-energy-density C 2+ In addition, the inevitable competitive reaction of hydrogen evolution and the extremely high energy consumption of product separation further limit the large-scale application of electrocatalytic CO2 reduction in industrial production. Therefore, the design and preparation of high-performance electrocatalysts has become the key to solving the bottleneck of electrocatalytic CO2 reduction.

[0003] From the perspective of catalysts, current research has achieved fruitful results, but C 2+ The activity and selectivity of the product, the long-term stability of the catalyst, the overall current density of the system and the high cost of electrode preparation are still difficult to meet people's actual production needs. At present, the electrocatalytic CO2 reduction electrode is usually based on conductive carbon paper. The mixture of catalyst and binder is coated on the surface of carbon paper by spraying, spin coating, blade coating and other means. After drying to form a film, it is used as a working electrode for ECR performance evaluation. However, the use of binders can easily cause the conductivity of the material to decrease and the active sites to be covered, resulting in the attenuation of the overall current density of the system; at the same time, the physically bonded catalyst is easy to peel off under the test environment, affecting the long-term operation stability of the electrode; in addition, the carbon paper itself is expensive and brittle, and it is easy to break and cause "flooding".

[0004] Based on the defects in the current preparation of coated electrodes, it is necessary to make innovative improvements to its preparation process.

[0005] Summary of the Invention

[0006] In view of this, it is necessary to provide a metal vapor diffusion electrode, a preparation method and a working electrode that can significantly improve the stability of the electrode in order to address the technical defects of the existing technology.

[0007] To solve the above problems, this application adopts the following technical solutions:

[0008] One of the purposes of the present application is to provide a metal vapor diffusion electrode, comprising a base layer, a bifunctional copolymer layer and a metal layer stacked in sequence, wherein the bifunctional copolymer layer is tightly connected to the base layer and the metal layer respectively through chemical bonds.

[0009] In some embodiments, the base layer includes a hydrophobic breathable film, which includes but is not limited to polytetrafluoroethylene film, polyurethane film, polyethyleneimine, and polyethylene terephthalate.

[0010] In some embodiments, the hydrophobic breathable membrane is a PTFE membrane that has been subjected to a single-side hydrophilic treatment.

[0011] In some embodiments, the bifunctional copolymer layer is copolymerized from at least one of alkenyl siloxane and alkenyl quaternary ammonium base.

[0012] In some embodiments, the bifunctional copolymer layer is copolymerized from 3-(methacryloyloxy)propyltrimethoxysilane and 2-(methacryloyloxy)ethyltrimethylammonium chloride monomers.

[0013] In some embodiments, the metal layer includes at least one of Ni, Cu, Ag, Bi, and Sn.

[0014] In some embodiments, the metal layer is Cu.

[0015] The second object of this application is to provide a method for preparing a metal vapor diffusion electrode, comprising the following steps:

[0016] performing a single-side hydrophilic treatment on the substrate to form a substrate layer;

[0017] A silanization reaction is performed on the hydrophilic treated side to form a silicon-oxygen bond;

[0018] performing copolymerization on one side of the silicon-oxygen bond to form a bifunctional copolymer layer;

[0019] The bifunctional copolymer layer is subjected to an electrostatic adsorption treatment and then metal is deposited to form a metal layer.

[0020] In some embodiments, the base layer includes a hydrophobic breathable film, which includes but is not limited to polytetrafluoroethylene film, polyurethane film, polyethyleneimine, and polyethylene terephthalate.

[0021] In some embodiments, the hydrophobic breathable membrane is a PTFE membrane that has been subjected to a single-side hydrophilic treatment.

[0022] In some embodiments, the bifunctional copolymer layer is copolymerized from at least one of alkenyl siloxane and alkenyl quaternary ammonium base.

[0023] In some embodiments, the bifunctional copolymer layer is copolymerized from 3-(methacryloyloxy)propyltrimethoxysilane and 2-(methacryloyloxy)ethyltrimethylammonium chloride monomers.

[0024] In some embodiments, the metal layer includes at least one of Ni, Cu, Ag, Bi, and Sn.

[0025] In some embodiments, the metal layer is Cu.

[0026] The third object of the present application is to provide a working electrode, comprising the metal vapor diffusion electrode, wherein the metal vapor diffusion electrode is connected to the negative electrode of an external power supply unit.

[0027] This application adopts the above technical solution, and its beneficial effects are as follows:

[0028] The metal vapor diffusion electrode and its preparation method provided in the present application include a base layer, a bifunctional copolymer layer and a metal layer stacked in sequence, and the bifunctional copolymer layer is tightly connected to the base layer and the metal layer respectively through chemical bonds. Since the chemical bond connection can overcome the difficulties of poor conductivity of physical adhesion, active site coverage, easy peeling during the test process and complex electrode preparation process, the electrode stability can be significantly improved; in addition, by optimizing the hydrophobic and breathable properties of the base layer and regulating the polymerization degree / thickness of the bifunctional copolymer layer, the microenvironment near the catalyst surface can be significantly improved, and the activity of the electrocatalytic CO2 reduction reaction and the selectivity of multi-carbon products can be effectively improved; at the same time, coupled with a universal metal layer growth strategy, the activity and selectivity of single products, especially multi-carbon products, can be controllably adjusted through the selective optimization of different types of single metals or multi-element alloys. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following briefly introduces the drawings required for use in the embodiments of the present application or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0030] FIG1 is a schematic structural diagram of a metal vapor diffusion electrode provided in one embodiment of the present invention.

[0031] FIG2 is a schematic diagram showing the preparation principle of a metal vapor diffusion electrode provided in one embodiment of the present invention.

[0032] FIG3 is a schematic diagram showing a comparison of the ECR reaction before and after the coating electrode and the metal vapor diffusion electrode provided in one embodiment of the present invention.

[0033] FIG4 is a phase structure diagram of a PTFE membrane, a single-sided hydrophilic PTFE-Na membrane, and an integrated Cu (Cu@PTFE) electrode used for electrocatalytic CO2 reduction in one embodiment of the present invention.

[0034] FIG5 is a microscopic morphology of a PTFE membrane, a single-sided hydrophilic PTFE-Na membrane, and a Cu@PTFE electrode used for electrocatalytic CO2 reduction in one embodiment of the present invention.

[0035] FIG6 is a graph showing the LSV curves of a PTFE membrane, a PTFE-Na membrane, and a Cu@PTFE electrode used for electrocatalytic CO2 reduction in CO2 and Ar gas environments in one embodiment of the present invention.

[0036] FIG7 is a graph showing the catalytic CO2 reduction performance of a PTFE membrane, a PTFE-Na membrane, and a Cu@PTFE electrode used for electrocatalytic CO2 reduction in one embodiment of the present invention.

[0037] FIG8 is a graph showing the long-cycle stability of the Cu@PTFE electrode for electrocatalytic CO2 reduction at industrial current density in one embodiment of the present invention. DETAILED DESCRIPTION

[0038] The following describes in detail embodiments of the present application, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present application, and should not be construed as limiting the present application.

[0039] In the description of this application, it should be understood that the terms "upper", "lower", "horizontal", "inside", "outside", etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on this application.

[0040] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of the technical features being referred to. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. Throughout the description of this application, "plurality" means two or more, unless otherwise specifically defined.

[0041] In order to make the purpose, technical solutions and advantages of this application more clear, this application is further described in detail below with reference to the accompanying drawings and embodiments.

[0042] Referring to Figure 1 , a schematic diagram of the structure of a metal vapor diffusion electrode provided in an embodiment of the present application includes: a base layer 110, a bifunctional copolymer layer 120, and a metal layer 130 stacked in sequence, with the bifunctional copolymer layer 120 being tightly connected to the base layer 110 and the metal layer 130 via chemical bonds. The specific implementation of each component is described in detail below.

[0043] In this embodiment, the base layer 110 includes a hydrophobic breathable film, which includes but is not limited to a polytetrafluoroethylene film, a polyurethane film, polyethyleneimine, and polyethylene terephthalate.

[0044] It is understandable that the base layer 110 can be made of a polymer film with good hydrophobicity, good flexibility and low price instead of traditional carbon paper, which can reduce the preparation cost and adapt to more expanded application scenarios.

[0045] Preferably, the base layer 110 is a single-sided hydrophilic treated PTFE membrane, which can maintain the hydrophobicity of the entire electrode to inhibit "water flooding" and improve the selectivity and stability of the ECR reaction.

[0046] Furthermore, the single-side hydrophilic treated PTFE membrane can be prepared by single-side treatment of the PTFE membrane with plasma, high-energy radiation or sodium reagent, wherein sodium reagent treatment is preferred.

[0047] In this embodiment, the bifunctional copolymer layer 120 is copolymerized from at least one of alkenyl siloxane and alkenyl quaternary ammonium base.

[0048] Preferably, the bifunctional copolymer layer 120 is a copolymer of 3-(methacryloyloxy)propyltrimethoxysilane and 2-(methacryloyloxy)ethyltrimethylammonium chloride monomers.

[0049] It can be understood that the chemical bonding of the bifunctional copolymer layer 120 can overcome the difficulties of poor physical adhesion conductivity, active site coverage, easy peeling during testing and complex electrode preparation process, thereby significantly improving electrode stability.

[0050] In this embodiment, the metal layer 130 includes at least one of Ni, Cu, Ag, Bi, and Sn.

[0051] Preferably, the metal layer is Cu.

[0052] It is understood that Cu is currently the only element that can produce high-value multi-carbon products in large quantities, so Cu metal (alloy) is preferred.

[0053] The metal vapor diffusion electrode provided in this application can be directly connected to the negative electrode of the power supply unit as a working electrode to perform electrocatalytic CO2 reduction performance testing through voltage / current control. Preferably, an electrochemical workstation is used as the power supply unit, and ECR performance evaluation is performed in constant current mode. In the ECR performance test, the gas phase components are detected online by gas chromatography, and the liquid phase products are detected and analyzed by liquid nuclear magnetic resonance.

[0054] The metal vapor diffusion electrode of the present application, one side of the bifunctional copolymer layer is connected to the base layer by a chemical bond, and one side is connected to the metal layer by a chemical bond. This structure can avoid the use of a binder in the preparation of the coated electrode, thereby improving the current density and stability of the electrode as a whole; it can also break through the limitation of poor long-cycle stability caused by the peeling of the catalyst layer under the test conditions. In addition, by optimizing the hydrophobic and breathable properties of the base layer and regulating the degree of polymerization / thickness of the bifunctional copolymer layer, the microenvironment near the catalyst surface (such as CO2 / H2O, pH, etc.) can be significantly improved, effectively improving the electrocatalytic CO2 reduction reaction (ECR) activity and multi-carbon product selectivity. Coupled with the universal metal layer growth strategy, the activity and selectivity of single products, especially multi-carbon products, can be controllably regulated by optimizing the selectivity of different types of single metals or multi-element alloys.

[0055] Please refer to FIG2 , which is a schematic diagram of a preparation method of a metal vapor diffusion electrode provided in an embodiment of the present application, which specifically includes the following steps:

[0056] Step S110 : performing a single-side hydrophilic treatment on the substrate to form a substrate layer.

[0057] In this embodiment, the base layer 110 includes a hydrophobic breathable film, which includes but is not limited to a polytetrafluoroethylene film, a polyurethane film, polyethyleneimine, and polyethylene terephthalate.

[0058] It is understandable that the base layer 110 can be made of a polymer film with good hydrophobicity, good flexibility and low price instead of traditional carbon paper, which can reduce the preparation cost and adapt to more expanded application scenarios.

[0059] Preferably, the base layer 110 is a single-sided hydrophilic treated PTFE membrane, which can maintain the hydrophobicity of the entire electrode to inhibit "water flooding" and improve the selectivity and stability of the ECR reaction.

[0060] Furthermore, the single-side hydrophilic treated PTFE membrane can be prepared by single-side treatment of the PTFE membrane with plasma, high-energy radiation or sodium reagent, wherein sodium reagent treatment is preferred.

[0061] Step S120: performing a silanization reaction on the hydrophilic treated surface to form a silicon-oxygen bond.

[0062] Step S130 : performing a copolymerization reaction on one side of the silicon-oxygen bond to form a bifunctional copolymer layer.

[0063] In this embodiment, the bifunctional copolymer layer 120 is copolymerized from at least one of alkenyl siloxane and alkenyl quaternary ammonium base.

[0064] Preferably, the bifunctional copolymer layer 120 is a copolymer of 3-(methacryloyloxy)propyltrimethoxysilane and 2-(methacryloyloxy)ethyltrimethylammonium chloride monomers.

[0065] It can be understood that the chemical bonding of the bifunctional copolymer layer 120 can overcome the difficulties of poor physical adhesion conductivity, active site coverage, easy peeling during testing and complex electrode preparation process, thereby significantly improving electrode stability.

[0066] Step S140 : performing an electrostatic adsorption process on the bifunctional copolymer layer and then depositing metal to form a metal layer.

[0067] In this embodiment, the metal layer 130 includes at least one of Ni, Cu, Ag, Bi, and Sn.

[0068] Preferably, the metal layer is Cu.

[0069] It is understood that Cu is currently the only element that can produce high-value multi-carbon products in large quantities, so Cu metal (alloy) is preferred.

[0070] The metal vapor diffusion electrode provided in this application can be directly connected to the negative electrode of the power supply unit as a working electrode to perform electrocatalytic CO2 reduction performance testing through voltage / current control. Preferably, an electrochemical workstation is used as the power supply unit, and ECR performance evaluation is performed in constant current mode. In the ECR performance test, the gas phase components are detected online by gas chromatography, and the liquid phase products are detected and analyzed by liquid nuclear magnetic resonance.

[0071] The preparation method of the metal vapor diffusion electrode of the present application, one side of the bifunctional copolymer layer is connected to the base layer by a chemical bond, and one side is connected to the metal layer by a chemical bond. This structure can avoid the use of a binder in the preparation of the coated electrode, thereby improving the current density and stability of the electrode as a whole; it can also break through the limitation of poor long-cycle stability caused by the peeling of the catalyst layer under the test conditions. In addition, by optimizing the hydrophobic permeability of the base layer and regulating the degree of polymerization / thickness of the bifunctional copolymer layer, the microenvironment near the catalyst surface (such as CO2 / H2O, pH, etc.) can be significantly improved, effectively improving the electrocatalytic CO2 reduction reaction (ECR) activity and multi-carbon product selectivity. Coupled with the universal metal layer growth strategy, the activity and selectivity of a single product, especially a multi-carbon product, can be controllably regulated by optimizing the selectivity of different types of single metals or multi-element alloys.

[0072] The above technical solutions of the present application are described in detail below with reference to specific embodiments.

[0073] Example 1: Preparation of Metal Vapor Diffusion Electrodes of Copolymers with Different Monomer Ratios and Their Application in ECR Reactions

[0074] (1) Metal Vapor Diffusion Electrode: A commercial PTFE membrane (10 cm*10 cm) was thoroughly cleaned and dried with deionized water and ethanol, respectively. The membrane was then treated with sodium reagent immersion to make it hydrophilic on one side for 5 min, and then dried in a 60°C oven. A bifunctional copolymer (2 mmol, prepared by polymerizing 3-(methacryloyloxy)propyltrimethoxysilane and 2-(methacryloyloxy)ethyltrimethylammonium chloride monomers in a molar ratio of 4:1) was then bonded to the hydrophilic-treated side of the PTFE via a silanization reaction. The other side of the copolymer was subjected to electrostatic attraction by strongly alkaline quaternary ammonium ions to adsorb chloropalladate ions for 5 to 30 min, and then transferred to a Cu ion plating solution for 20 min to prepare an integrated metal electrode (labeled as Cu@PTFE). Finally, the electrode was applied to the ECR reaction.

[0075] (2) The above-mentioned metal vapor diffusion electrode was connected to the three-electrode system of the electrochemical workstation as the working electrode, the reference electrode was a Hg / HgO electrode, the counter electrode was a Ni foil, and the electrolyte was a 1 M KOH solution. The electrode ECR performance test was carried out at 80 mA, 160 mA, 240 mA, 320 mA, 400 mA, and 480 mA in constant current mode, and the gas phase components were quantitatively analyzed by online gas chromatography, and the liquid phase components were quantitatively analyzed by liquid nuclear magnetic resonance.

[0076] Please refer to Figure 3, which is a schematic diagram comparing the ECR reaction of the coated electrode and the metal vapor diffusion electrode before and after. It can be seen from Figure 3 that the metal vapor diffusion electrode provided in this embodiment can break through the limitation of poor long-cycle stability caused by catalyst layer peeling under test conditions.

[0077] As shown in FIG4 , the metal vapor diffusion electrode (Cu electrode) was successfully prepared, and the Cu electrode corresponds to the physical structure of PDF#04-0836;

[0078] As shown in FIG5 , the Cu electrode of the metal vapor diffusion electrode is a nanosphere structure of sub-nano particles, and the size of the nanosphere is about 30 nm.

[0079] As shown in Figure 6, the current density of the Cu electrode of the metal vapor diffusion electrode is significantly higher than that of the PTFE membrane and the PTFE-Na membrane. The comparison under Ar gas and CO2 atmospheres shows that the integrated Cu electrode has superior ECR reaction activity.

[0080] As shown in Figure 7, the metal vapor diffusion electrode Cu electrode has a much lower competition for hydrogen evolution than the PTFE membrane and PTFE-Na membrane. The selectivity of the high-value ethylene in the products of CO2 reduction catalyzed by the Cu electrode can reach about 60%, and the selectivity of multi-carbon products is >70%.

[0081] As shown in FIG8 , the metal vapor diffusion electrode Cu electrode has very excellent long-term cycle stability. Under industrial current density, the selectivity of ethylene is always >50% after 30 hours of cycling, and the voltage does not change significantly during the test.

[0082] Examples 2-5: Preparation of Metal Vapor Diffusion Electrodes of Copolymers with Different Monomer Ratios and Their Application in ECR Reactions

[0083] (1) Preparation of metal vapor diffusion electrode: Commercial PTFE membrane (10cm*10cm) was thoroughly cleaned and dried with deionized water and ethanol respectively. Then, the PTFE membrane was treated with hydrophilic treatment on one side for 5 minutes by impregnation with sodium reagent. Then, it was dried in a 60℃ oven. Then, 2mmol of copolymer of 3-(methacryloyloxy)propyltrimethoxysilane and 2-(methacryloyloxy)ethyltrimethylammonium chloride monomers in a molar ratio of 2:1, 1:1, 1:2, and 1:4 was bonded to the hydrophilic treated side of the PTFE through silanization reaction. The other side of the copolymer was adsorbed with chloropalladate ions by electrostatic attraction of strong alkaline quaternary ammonium ions for 5-30 minutes. After that, it was transferred to Cu ion plating solution for 20 minutes to prepare an integrated metal electrode. Finally, the electrode was applied to the ECR reaction.

[0084] (2) The above-mentioned metal vapor diffusion electrode was connected to the three-electrode system of the electrochemical workstation as the working electrode, the reference electrode was a Hg / HgO electrode, the counter electrode was a Ni foil, and the electrolyte was a 1 M KOH solution. The electrode ECR performance test was carried out at 80 mA, 160 mA, 240 mA, 320 mA, 400 mA, and 480 mA in constant current mode, and the gas phase components were quantitatively analyzed by online gas chromatography, and the liquid phase components were quantitatively analyzed by liquid nuclear magnetic resonance.

[0085] Examples 6-8: Preparation of Metal Vapor Diffusion Electrodes with Different Copolymer Thicknesses and Their Application in ECR Reactions

[0086] (1) Preparation of metal vapor diffusion electrode: Commercial PTFE membrane (10cm*10cm) was thoroughly cleaned and dried with deionized water and ethanol respectively. Then, the PTFE membrane was treated with hydrophilic treatment on one side for 5 minutes by impregnation with sodium reagent. Then, it was dried in a 60℃ oven. Then, a copolymer of 3-(methacryloyloxy)propyltrimethoxysilane and 2-(methacryloyloxy)ethyltrimethylammonium chloride monomers (4mmol, 6mmol, and 8mmol, respectively) in a molar ratio of 4:1 was bonded to the hydrophilic treated side of the PTFE through silanization reaction. The other side of the copolymer was adsorbed with chloropalladate ions by electrostatic attraction of strong alkaline quaternary ammonium ions for 5-30 minutes. After that, it was transferred to Cu ion plating solution for 20 minutes to prepare an integrated metal electrode. Finally, the electrode was applied to the ECR reaction.

[0087] (2) The above-mentioned metal vapor diffusion electrode was connected to the three-electrode system of the electrochemical workstation as the working electrode, the reference electrode was a Hg / HgO electrode, the counter electrode was a Ni foil, and the electrolyte was a 1 M KOH solution. The electrode ECR performance test was carried out at 80 mA, 160 mA, 240 mA, 320 mA, 400 mA, and 480 mA in constant current mode, and the gas phase components were quantitatively analyzed by online gas chromatography, and the liquid phase components were quantitatively analyzed by liquid nuclear magnetic resonance.

[0088] Examples 9-12: Preparation of Metal Vapor Diffusion Electrodes with Different Metal Layers and Their Application in ECR Reactions

[0089] (1) Preparation of metal vapor diffusion electrode: Commercial PTFE membrane (10cm*10cm) was thoroughly cleaned and dried with deionized water and ethanol respectively. Then, the PTFE membrane was treated with hydrophilic treatment on one side for 5 minutes by impregnation with sodium reagent. Then, it was dried in a 60℃ oven. Then, 2mmol of a copolymer of 3-(methacryloyloxy)propyltrimethoxysilane and 2-(methacryloyloxy)ethyltrimethylammonium chloride monomers in a molar ratio of 4:1 was bonded to the hydrophilic treated side of the PTFE through silanization reaction. The other side of the copolymer was adsorbed with chloropalladate ions by electrostatic attraction of strong alkaline quaternary ammonium ions for 5-30 minutes. After that, it was transferred to Ni, Ag, NiCu alloy, and AgCu alloy ion plating solution for 20 minutes to prepare an integrated metal electrode. Finally, the electrode was used for ECR reaction.

[0090] (2) The above-mentioned metal vapor diffusion electrode was connected to the three-electrode system of the electrochemical workstation as the working electrode, the reference electrode was a Hg / HgO electrode, the counter electrode was a Ni foil, and the electrolyte was a 1 M KOH solution. The electrode ECR performance test was carried out at 80 mA, 160 mA, 240 mA, 320 mA, 400 mA, and 480 mA in constant current mode, and the gas phase components were quantitatively analyzed by online gas chromatography, and the liquid phase components were quantitatively analyzed by liquid nuclear magnetic resonance.

[0091] Examples 13-17: Preparation of Metal Vapor Diffusion Electrodes with Different Cu Layer Thicknesses and Their Application in ECR Reactions

[0092] (1) Preparation of metal vapor diffusion electrode: Commercial PTFE membrane (10cm*10cm) was thoroughly cleaned and dried with deionized water and ethanol respectively. Then, the PTFE membrane was treated with hydrophilic treatment on one side for 5 minutes by impregnation with sodium reagent. Then, it was dried in a 60℃ oven. Then, 2mmol of a copolymer of 3-(methacryloyloxy)propyltrimethoxysilane and 2-(methacryloyloxy)ethyltrimethylammonium chloride monomers in a molar ratio of 4:1 was bonded to the hydrophilic treated side of the PTFE through silanization reaction. The other side of the copolymer was adsorbed with chloropalladate ions by electrostatic attraction of strong alkaline quaternary ammonium ions for 5-30 minutes. After that, it was transferred to Cu ion plating solution for 5 minutes, 10 minutes, 15 minutes, 25 minutes, and 30 minutes to prepare an integrated metal electrode. Finally, the electrode was applied to the ECR reaction.

[0093] (2) The above-mentioned metal vapor diffusion electrode was connected to the three-electrode system of the electrochemical workstation as the working electrode, the reference electrode was a Hg / HgO electrode, the counter electrode was a Ni foil, and the electrolyte was a 1 M KOH solution. The electrode ECR performance test was carried out at 80 mA, 160 mA, 240 mA, 320 mA, 400 mA, and 480 mA in constant current mode, and the gas phase components were quantitatively analyzed by online gas chromatography, and the liquid phase components were quantitatively analyzed by liquid nuclear magnetic resonance.

[0094] Examples 18-20: ECR performance test of Cu@PTFE metal vapor diffusion electrode in different electrolyte solutions

[0095] (1) Preparation of metal vapor diffusion electrode: Commercial PTFE membrane (10cm*10cm) was thoroughly cleaned and dried with deionized water and ethanol respectively. Then, the PTFE membrane was treated with hydrophilic treatment on one side for 5 minutes by impregnation with sodium reagent. Then, it was dried in a 60℃ oven. Then, 2mmol of bifunctional copolymer prepared by polymerizing 3-(methacryloyloxy)propyltrimethoxysilane and 2-(methacryloyloxy)ethyltrimethylammonium chloride monomers in a molar ratio of 4:1 was bonded to the hydrophilic treated side of PTFE through silanization reaction. The other side of the copolymer was adsorbed with chloropalladate ions by electrostatic attraction of strong alkaline quaternary ammonium ions for 5-30 minutes. After that, it was transferred to Cu ion plating solution for 20 minutes to prepare an integrated metal electrode. Finally, the electrode was applied to ECR reaction.

[0096] (2) The above-mentioned metal vapor diffusion electrode was connected as a working electrode to the three-electrode system of an electrochemical workstation. The reference electrode was a Hg / HgO electrode, the counter electrode was a Ni foil, and the electrolytes were 5 M KOH, 1 M CsOH, and 1 M KHCO3 solutions, respectively. The electrode ECR performance was tested in constant current mode at 80 mA, 160 mA, 240 mA, 320 mA, 400 mA, and 480 mA, respectively. The gas phase components were quantitatively analyzed by online gas chromatography, and the liquid phase components were quantitatively analyzed by liquid nuclear magnetic resonance.

[0097] It can be understood that the various technical features of the above-described embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the various technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0098] The above are merely preferred embodiments of the present application and only specifically describe the technical principles of the present application. These descriptions are intended only to explain the principles of the present application and should not be construed in any way as limiting the scope of protection of the present application. Based on the explanations herein, any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present application, as well as other specific implementations of the present application that can be conceived by those skilled in the art without inventive effort, shall be included within the scope of protection of the present application.

Claims

1. A metal vapor diffusion electrode, characterized in that, it comprises a base layer, a bifunctional copolymer layer and a metal layer which are sequentially stacked, and the bifunctional copolymer layer is tightly connected to the base layer and the metal layer respectively through chemical bonds.

2. The metal vapor diffusion electrode according to claim 1, characterized in that, the base layer comprises a hydrophobic and breathable membrane, and the hydrophobic and breathable membrane includes but is not limited to polytetrafluoroethylene membrane, polyurethane membrane, polyethyleneimine, polyethylene terephthalate.

3. The metal vapor diffusion electrode according to claim 2, characterized in that, the hydrophobic and breathable membrane is a PTFE membrane subjected to single-sided hydrophilic treatment.

4. The metal vapor diffusion electrode according to claim 1, characterized in that, the bifunctional copolymer layer is copolymerized from at least one of alkenyl siloxane and alkenyl quaternary ammonium base.

5. The metal vapor diffusion electrode according to claim 4, characterized in that, the bifunctional copolymer layer is copolymerized from 3-(methacryloyloxy)propyltrimethoxysilane and 2-(methacryloyloxy)ethyltrimethylammonium chloride monomers.

6. The metal vapor diffusion electrode according to claim 1, characterized in that, the metal layer comprises at least one of Ni, Cu, Ag, Bi, Sn.

7. The metal vapor diffusion electrode according to claim 6, characterized in that, the metal layer is Cu.

8. A preparation method of a metal vapor diffusion electrode, characterized in that, it comprises the following steps: performing single-sided hydrophilic treatment on a substrate to form a base layer; performing a silanization reaction on the hydrophilic-treated side to form a silicon-oxygen bond; performing a copolymerization reaction on the side with the silicon-oxygen bond to form a bifunctional copolymer layer; performing electrostatic adsorption treatment on the bifunctional copolymer layer and then redepositing a metal to form a metal layer.

9. The preparation method of a metal vapor diffusion electrode according to claim 8, characterized in that, the base layer comprises a hydrophobic and breathable membrane, and the hydrophobic and breathable membrane includes but is not limited to polytetrafluoroethylene membrane, polyurethane membrane, polyethyleneimine, polyethylene terephthalate.

10. The preparation method of a metal vapor diffusion electrode according to claim 9, characterized in that, the hydrophobic and breathable membrane is a PTFE membrane subjected to single-sided hydrophilic treatment.

11. The preparation method of a metal vapor diffusion electrode according to claim 8, characterized in that, the bifunctional copolymer layer is copolymerized from at least one of alkenyl siloxane and alkenyl quaternary ammonium base.

12. For the preparation method of a metal vapor diffusion electrode according to claim 11, the bifunctional copolymer layer is copolymerized from 3-(methacryloyloxy)propyltrimethoxysilane and 2-(methacryloyloxy)ethyltrimethylammonium chloride monomers.

13. For the preparation method of a metal vapor diffusion electrode according to claim 8, the metal layer comprises at least one of Ni, Cu, Ag, Bi, Sn.

14. For the preparation method of a metal vapor diffusion electrode according to claim 13, the metal layer is Cu.

15. A working electrode, characterized in that, it comprises the metal vapor diffusion electrode according to claim 1, and the metal vapor diffusion electrode is connected to the negative electrode of an external power supply unit.

Images