A gas diffusion electrode applied to carbon dioxide electro-reduction

Abstract

This invention discloses a gas diffusion electrode for the electroreduction of carbon dioxide, relating to the field of carbon dioxide electrochemical reduction, including a catalyst C-Cu2O@Cu-Cu. V @Cu D With naphthol. This invention utilizes a pure chemical reduction method to directly prepare C-Cu2O@Cu-Cu. V Core-shell electrode catalytic materials were developed, and C-Cu2O@Cu-Cu were directly prepared by blade coating or spray coating methods with the participation of naphthol binder and template agent. V Electrode, wherein Cu2O@Cu-Cu V A core-shell catalyst was developed; and copper salts were mixed with stabilizers and subjected to constant voltage conditions in the C-Cu2O@Cu-Cu catalyst. V Electrodeposition of Cu on the surface of the catalyst layer D Cu2O@Cu-Cu was prepared V @Cu D Ordered "core-shell" catalysts. Utilizing internally stable Cu₂O@Cu-Cu V Structure and external defects of Cu (Cu D The combination of these elements results in a catalyst surface with more active area and defect sites, which lowers the adsorption energy barrier of intermediate CO* on the catalyst surface, making the catalyst surface more conducive to C-C bonding and improving the selectivity and activity of C2+ products.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of electrochemical reduction of carbon dioxide, in particular to a gas diffusion electrode applied to electrochemical reduction of carbon dioxide. BACKGROUND

[0002] In recent years, due to the extensive use of fossil fuels, the global CO2 emission gradually increases, leading to global warming, and frequent extreme weather. Converting CO2 into energy materials or other chemicals is a problem to be solved at present, and is one of the main strategies to achieve the "double carbon" goal of China. Among them, electrochemical reduction of CO2 is one of the effective ways to convert CO2 into useful energy materials or high value-added chemicals.

[0003] However, the carbon dioxide molecule is relatively stable at room temperature, and a large electric potential needs to be applied to make it react; in addition, the electrocatalytic CO2 reduction reaction (CO2ER) involves a multi-electron reaction process, and it is difficult to control the single target product. When the electro-reduction reaction occurs in a carbon dioxide saturated aqueous solution, the hydrogen evolution reaction (side reaction, competitive reaction) is inevitable, which leads to a decrease in the faradic efficiency of the target product, especially when preparing hydrocarbon products, the potential is relatively negative, which leads to a more serious hydrogen evolution side reaction. At present, the catalysts used in the catalytic reduction of CO2 are mostly metals, which are easily corroded and consumed in the reaction process, so the stability of the catalytic material becomes a problem that needs to be considered in the reaction process. The conventional electrocatalysts have the following several obvious shortcomings: 1. The electrocatalytic CO2 reduction (CO2ER) reaction has a high potential and high energy consumption; 2. The target product is difficult to control, and there are many by-products and poor selectivity; 3. The metal catalytic material has poor stability and is easily deactivated during the reaction. Therefore, a high-quality catalyst generally has the following characteristics: multiple active catalytic sites, high selectivity, high stability, high efficient electron transfer rate, etc. Metal catalysts with low overpotential or high selectivity for electrochemical CO2 reduction, such as Au, Ag, Pb, Hg, etc., often have high cost or high toxicity, or both; and Cu is the only metal that can efficiently electrochemically reduce CO2 to hydrocarbons. On the surface of a single-metal Cu-based catalyst, CO2 can be reduced to CO, CH4, C2H6, C2H4, and oxygen-containing hydrocarbons (ethanol, formic acid) and other different products, which is mainly related to the morphology, structure, crystal type and surface active site type of the Cu metal catalyst. And studies have shown that a small amount of metal oxide is beneficial to the generation of C2+ products, and the metal generated by the reduction of the oxide has a higher low-coordination number active site. For example, Academician Han Buxing of the Chinese Academy of Sciences and others prepared a three-dimensional dendritic Cu-Cu2O composite material by in-situ reduction electrodeposition of copper complexes, and the catalyst has high C2+ selectivity. However, the current use of Cu catalysts still has problems such as low product selectivity, low catalytic activity and poor stability, and its performance still does not meet the requirements of industrialization.

[0004] The present application aims at the problems existing in the process of electrocatalytic CO2 reduction reaction, and a Cu2O@Cu-CuV@Cu D electrocatalyst with core-shell structure is invented by chemical reduction method combined with electrodeposition method. Secondly, by adjusting the special morphology of the defect Cu and the crystal type of the single crystal Cu outside the core-shell, different types of active sites on the surface are obtained, the electrochemical reaction active specific surface area is expanded, and new reaction active sites are constructed, so as to improve the selectivity and activity of hydrocarbons (CH4, C2H4). And in the preparation process, different regular Cu2O@Cu-Cu V @CuD Core-shell structure.

[0005] Therefore, it is necessary to invent a gas diffusion electrode applied to carbon dioxide electro-reduction to solve the above problems. SUMMARY

[0006] The purpose of the present application is to provide a gas diffusion electrode applied to carbon dioxide electro-reduction to solve the problems raised in the background art.

[0007] To achieve the above purpose, the present application provides the following technical solution: a gas diffusion electrode applied to carbon dioxide electro-reduction, the gas diffusion electrode comprising a catalyst C-Cu2O@Cu-Cu V @Cu D and naphthol, and the composition ratio of the catalyst and naphthol is 3:1-1:4, the catalyst C-Cu2O@Cu-Cu V @Cu D is a core-shell structure, wherein Cu D is a shell, Cu2O@Cu-Cu V is a core, C is a substrate, the catalyst C-Cu2O@Cu-Cu V @Cu D is composed of: Cu D , the content of Cu is 50-87wt%, the content of Cu-Cu V is 10-25wt%, and the content of Cu2O is 3-25wt%.

[0008] A preparation method of a gas diffusion electrode applied to carbon dioxide electro-reduction is used to prepare a gas diffusion electrode applied to carbon dioxide electro-reduction, and specifically comprises the following steps:

[0009] S1: mix copper salt with water and alcohol solution, add dilute sulfuric acid to adjust the pH value of the copper salt solution, then water bath, under magnetic stirring, dropwise add sodium hydroxide, after reaction form Cu(OH) X , then add a reducing agent to reduce part of the oxides to prepare a Cu2O@Cu-Cu V core-shell structure catalyst material colloid solution, then centrifuge, wash, dry the colloid solution, and store in vacuum for standby;

[0010] S2: bake the carbon paper substrate at 350-600℃ for 1-12h, then ultrasonically wash the baked carbon substrate with water and ethanol, and dry for standby;

[0011] S3: prepare the Cu2O@Cu-Cu VThe material is added to the alcohol solution mixed with 5wt% naphthol solution, and after being uniformly dispersed, a C-Cu2O@Cu-Cu is prepared on a carbon paper substrate by using a doctor blade or a spray coating method. V catalytic layer.

[0012] S4: mixing the copper salt with the stabilizer, magnetic stirring for 20-60 min to form a precursor copper salt solution, under inert gas protection, at room temperature, and under constant voltage conditions on a C-Cu2O@Cu-Cu V catalytic layer surface electrodeposition of Cu D After being soaked in dilute sulfuric acid, washed, and vacuum dried, a core-shell structure C-Cu2O@Cu-Cu with controllable morphology is prepared V @Cu D gas diffusion electrode of the catalyst.

[0013] Preferably, the precursor copper salt solution is CuCl2·2H2O, Cu(NO3)2·3H2O, or CuSO4·5H2O, wherein the concentration of copper ions is 0.05M-1.2M, and the pH of the copper salt solution is 3.0.

[0014] Preferably, the alcohol solution is any one or more of methanol, ethanol, and ethylene glycol, and the volume ratio of the alcohol solution to water is 10:1-1:10.

[0015] Preferably, the concentration of the sodium hydroxide solution is 2-6M, the water bath temperature is 40-80℃, and the water bath time is 10-60 min.

[0016] Preferably, the reducing agent is one or both of glucose and ascorbic acid, and the concentration of the reducing agent is 0.5-1.5M.

[0017] Preferably, the stabilizer is one or both of octylphenyl polyoxyethylene ether, Tween 20, polyethylene glycol, and OP (alkyl phenol polyoxyethylene ether), and the concentration is 0.02-0.18M.

[0018] Preferably, the constant voltage is -0.3V to -2.0V (vs. Ag / AgCl), and preferably the potential is -0.7V to -1.5V (vs. Ag / AgCl).

[0019] Preferably, the time for the reducing agent to reduce part of the oxides is 800-2000s.

[0020] Preferably, the gas diffusion electrode is used as a cathode for the electrochemical reduction reaction of carbon dioxide

[0021] Technical effects and advantages of the present application:

[0022] 1. Directly prepare Cu2O@Cu-Cu core-shell electrode catalytic material by pure chemical reduction method V and directly prepare C-Cu2O@Cu-Cu core-shell electrode by using scraping coating method or spraying method in the participation of naphthol binder and template agent V .

[0023] 2. Cu2O@Cu-Cu core-shell electrode catalytic material has ordered structure V @Cu D . V The combination of internal stable Cu2O@Cu-Cu core-shell structure and external defect Cu(Cu D ) makes the catalyst surface have more active area and defect sites, reduces the adsorption energy barrier of intermediate CO* on the catalyst surface, makes the catalyst surface more conducive to the bonding of C-C, and improves the selectivity and activity of C2+ product

[0024] 3. The Cu D shell layer and Cu + interact with metals, limit CO2 electro-reduction in the "functional domain", reduce the reduction of Cu+ component, avoid catalyst loss in the CO2 reduction process, and improve the stability of the catalyst

[0025] 4. In the process of depositing Cu D , the stabilizer can ensure the stability of the electroplating solution and can be used as a template to control the morphology of the surface Cu by generating ordered structure Cu deposition layer, thereby improving the specific surface area of the catalyst

[0026] 5. By adjusting the preparation conditions of the catalyst, Cu2O@Cu-Cu core-shell structure with different morphologies can be obtained V @Cu D electrocatalytic material; the preparation process is simple and easy to control. BRIEF DESCRIPTION OF DRAWINGS

[0027] Figure 1 is the reduction product distribution diagram of the electrode in Example 1 of the present application in CO2-saturated KCl;

[0028] Figure 2 is the reduction product distribution diagram of the electrode in Example 2 of the present application in CO2-saturated KCl;

[0029] Figure 3 is the reduction product distribution diagram of the electrode in Comparative Example 1 of the present application in CO2-saturated KCl;

[0030] Figure 4 is the reduction product distribution diagram of the electrode in Comparative Example 2 of the present application in CO2-saturated KCl. DETAILED DESCRIPTION

[0031] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative efforts fall within the scope of the present application.

[0032] It should be noted that, in this document, the terms "comprises", "comprising", or any other variation thereof, are intended to cover a non-exclusive inclusion, so that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but can include other elements not expressly listed or inherent to such process, method, article, or apparatus.

[0033] The present application provides a gas diffusion electrode applied to carbon dioxide electro-reduction, the gas diffusion electrode comprising a catalyst C-Cu2O@Cu-Cu V @Cu D and naphthol, and the composition ratio of the catalyst and naphthol is 3:1-1:4, the catalyst C-Cu2O@Cu-Cu V @Cu D is a core-shell structure, wherein Cu D is a shell, Cu2O@Cu-Cu V is a core, C is a substrate, the composition of the catalyst C-Cu2O@Cu-Cu V @Cu D is: Cu D The content of Cu-Cu V is 10-25wt%, and the content of Cu2O is 3-25wt%.

[0034] A preparation method of a gas diffusion electrode applied to carbon dioxide electro-reduction, for preparing the gas diffusion electrode applied to carbon dioxide electro-reduction, specifically comprising the following steps:

[0035] S1: mixing copper salt with water and alcohol solution, adding dilute sulfuric acid to adjust the pH value of the copper salt solution, then water bath, under magnetic stirring, adding sodium hydroxide drop by drop, after reaction, forming Cu(OH) X , then adding a reducing agent to reduce part of the oxides, preparing a colloid solution of the catalyst material with a Cu2O@Cu-Cu V core-shell structure, then centrifuging, washing, drying the colloid solution, and vacuum preserving for standby use;

[0036] S2: carbon paper substrate is baked at 350-600℃ for 1-12h, then the baked carbon substrate is washed with water, ethanol by ultrasonic, and dried for use;

[0037] S3: the prepared Cu2O@Cu-Cu V The material is added into the alcohol solution mixed with 5wt% naphthol solution, and after being uniformly dispersed, C-Cu2O@Cu-Cu V catalytic layer is prepared on the carbon paper substrate by using the scraping or spraying method.

[0038] S4: the copper salt is mixed with the stabilizer to form a precursor copper salt solution by magnetic stirring for 20-60min, and under the protection of inert gas, the Cu V is electrodeposited on the surface of the C-Cu2O@Cu-Cu D catalytic layer at room temperature under constant voltage conditions. V @Cu D gas diffusion electrode.

[0039] The precursor copper salt solution is CuCl2·2H2O, Cu(NO3)2·3H2O, or CuSO4·5H2O, wherein the concentration of copper ions is 0.05M-1.2M, preferably the concentration is 0.1-0.3M, and the pH of the copper salt solution is 3.0.

[0040] The alcohol solution is any one or more of methanol, ethanol, and ethylene glycol, and the volume ratio of the alcohol solution to water is 10:1-1:10, preferably the volume ratio is 4:1-1:4.

[0041] The concentration of the sodium hydroxide solution is 2-6M, preferably the concentration is 3-6M, the water bath temperature is 40-80℃, preferably the temperature is 58-70℃, and the water bath time is 10-60min, preferably the time is 30-40min.

[0042] The reducing agent is one or both of glucose and ascorbic acid, and the concentration of the reducing agent is 0.5-1.5M, preferably the concentration is 0.9-1.1M.

[0043] The stabilizer is one or both of octylphenyl polyoxyethylene ether, Tween 20, polyethylene glycol, and OP (alkyl phenol polyoxyethylene ether), and the concentration is 0.02-0.18M.

[0044] The constant voltage is -0.3V~-2.0V (vs. Ag / AgCl), preferably the potential is -0.7V~-1.5V (vs. Ag / AgCl).

[0045] The reducing agent reduces part of the oxides for 800-2000s, preferably for 1200-1800s.

[0046] The gas diffusion electrode applied to the carbon dioxide electro-reduction is used as a cathode of the carbon dioxide electrochemical reduction reaction.

[0047] Example 1

[0048] 10 mL of 0.2M CuCl2·2H2O solution was measured, 20 mL of ethylene glycol and 10 mL of ultrapure water were added to the above solution, H2SO4 was used to adjust the pH of the solution to 3.0, and the solution was stirred uniformly, the water bath was heated to 60℃, and after 10 min of magnetic stirring, 10 mL of 5M NaOH solution was added, and after 5 min of reaction, 10 mL of 1M glucose was added within 30 s for reduction, the 60℃ water bath temperature was maintained, and the reaction was continued for 30 min to prepare Cu2O@Cu-Cu V The colloidal solution of the core-shell structure catalytic material was then centrifuged, washed with ultrapure water, and vacuum dried, and the prepared Cu2O@Cu-Cu V The core-shell electrode catalytic material was dissolved in 0.5 mL of methanol and 5 μL of 5wt% naphthol (Nafion) solution was added, and a C-Cu2O@Cu-Cu V electrode was prepared by scraping on the previously prepared carbon substrate using the scraping method. Then, 10 mL of 0.2M CuCl2·2H2O solution was mixed with 30 mL of 0.06M octylphenyl polyoxyethylene ether solution, and the mixed solution was used as an electrolyte. Under the protection of N2 and under the condition of a constant voltage of -0.3V (vs. Ag / AgCl), C-Cu2O@Cu-Cu V @Cu D electrode was prepared by scraping on the previously prepared carbon substrate using the scraping method. Then, 10 mL of 0.2M CuCl2·2H2O solution was mixed with 30 mL of 0.06M octylphenyl polyoxyethylene ether solution, and the mixed solution was used as an electrolyte. Under the protection of N2 and under the condition of a constant voltage of -0.3V (vs. Ag / AgCl), C-Cu2O@Cu-Cu

[0049] Example 2

[0050] 10 mL of 0.2M CuCl2·2H2O solution was measured, 20 mL of ethylene glycol and 10 mL of ultrapure water were added to the above solution, H2SO4 was used to adjust the pH of the solution to 3.0, and the solution was stirred uniformly, the water bath was heated to 60℃, and after 10 min of magnetic stirring, 10 mL of 5M NaOH solution was added, and after 5 min of reaction, 10 mL of 1M ascorbic acid was added within 30 s for reduction, the 60℃ water bath temperature was maintained, and the reaction was continued for 30 min to prepare Cu2O@Cu-Cu VThe colloidal solution of the core-shell structure catalytic material is then centrifuged, washed with ultrapure water, vacuum dried, and Cu2O@Cu-Cu V The core-shell electrode catalytic material is dissolved in 0.5 mL of methanol and 5 μL of a 5 wt% naphthol (Nafion) solution is added, and a carbon substrate prepared in advance is scraped using a scraping method to obtain a C-Cu2O@Cu-Cu V The electrode, and then 10 mL of a 0.2 M CuCl2·2H2O solution is mixed with 30 mL of a 0.06 M octylphenyl polyoxyethylene ether solution, and the mixed solution is used as an electrolyte, and a C-Cu2O@Cu-Cu is obtained by electrodeposition under N2 protection at a constant voltage of -0.3 V (vs. Ag / AgCl) for 1200 s V @Cu D The electrode, and finally the prepared electrode is soaked in dilute sulfuric acid, washed, and then dried in a vacuum oven to obtain a gas diffusion electrode.

[0051] Example 3

[0052] 10 mL of a 0.2 M CuCl2·2H2O solution is measured, and 20 mL of ethylene glycol and 10 mL of ultrapure water are added to the solution, H2SO4 is used to adjust the pH of the solution to 3.0, and the solution is stirred uniformly, and then the solution is heated to 60°C in a water bath and magnetically stirred for 10 min, and then 10 mL of a 5 M NaOH solution is added, and the solution is reacted for 5 min, and then 10 mL of a 1 M glucose solution is added within 30 s for reduction, and the water bath temperature is maintained at 60°C, and the reaction is continued for 30 min to obtain a Cu2O@Cu-Cu V The colloidal solution of the core-shell structure catalytic material is then centrifuged, washed with ultrapure water, vacuum dried, and Cu2O@Cu-Cu V The core-shell electrode catalytic material is dissolved in 0.5 mL of methanol and 5 μL of a 5 wt% naphthol (Nafion) solution is added, and a carbon substrate prepared in advance is scraped using a scraping method to obtain a C-Cu2O@Cu-Cu V The electrode, and then 10 mL of a 0.2 M CuCl2·2H2O solution is mixed with 30 mL of a 0.06 M OP (alkyl phenol polyoxyethylene ether) solution, and the mixed solution is used as an electrolyte, and a C-Cu2O@Cu-Cu is obtained by electrodeposition under N2 protection at a constant voltage of -0.3 V (vs. Ag / AgCl) for 1200 s V @Cu D The electrode, and finally the prepared electrode is soaked in dilute sulfuric acid, washed, and then dried in a vacuum oven to obtain a gas diffusion electrode.

[0053] Example 4

[0054] Take 10 mL of 0.2 M CuCl2·2H2O solution, then add 20 mL of ethylene glycol and 10 mL of ultrapure water to the above solution, adjust the pH of the solution to 3.0 with H2SO4, stir uniformly, heat the water bath to 60℃, and magnetically stir for 10 min, then add 10 mL of 5 M NaOH solution, react for 5 min, then add 10 mL of 1 M glucose for reduction within 30 s, maintain the 60℃ water bath temperature, and continue to react for 30 min to prepare Cu2O@Cu-Cu V core-shell structure catalytic material colloid solution, then centrifuge the colloid solution, wash with ultrapure water, vacuum dry, and then prepare Cu2O@Cu-Cu V core-shell electrode catalytic material, dissolve 0.5 mL of methanol and add 5 μL of 5 wt% naphthol (Nafion) solution, use the scraping method to scrape on the previously prepared carbon substrate to prepare C-Cu2O@Cu-Cu V electrode, then mix 10 mL of 0.2 M CuCl2·2H2O solution with 30 mL of 0.06 M Tween 20 solution, use the mixed solution as the electrolyte, under the protection of N2, and under the condition of a constant voltage of -0.3 V (vs. Ag / AgCl), electrodeposition for 1200 s to obtain C-Cu2O@Cu-Cu V @Cu D electrode, and finally soak and wash the prepared electrode with dilute sulfuric acid and then place it in a vacuum oven for drying to obtain a gas diffusion electrode.

[0055] Example 5

[0056] Take 10 mL of 0.2 M CuSO4·5H2O solution, then add 20 mL of ethylene glycol and 10 mL of ultrapure water to the above solution, adjust the pH of the solution to 3.0 with H2SO4, stir uniformly, heat the water bath to 60℃, and magnetically stir for 10 min, then add 10 mL of 5 M NaOH solution, react for 5 min, then add 10 mL of 1 M glucose for reduction within 30 s, maintain the 60℃ water bath temperature, and continue to react for 60 min to prepare Cu2O@Cu-Cu V core-shell structure catalytic material colloid solution, then centrifuge the colloid solution, wash with ultrapure water, vacuum dry, and then prepare Cu2O@Cu-Cu V core-shell electrode catalytic material, dissolve 0.5 mL of methanol and add 5 μL of 5 wt% naphthol (Nafion) solution, use the scraping method to scrape on the previously prepared carbon substrate to prepare C-Cu2O@Cu-Cu VElectrode, 10 mL of 0.2 M CuSO4·5H2O solution was mixed with 30 mL of 0.06 M octaethylene glycol solution, the mixed solution was used as electrolyte, under the protection of N2, and under the condition of constant voltage of -0.3 V (vs. Ag / AgCl), C-Cu2O@Cu-Cu was obtained by electrodeposition for 1200 s V @Cu D Electrode, finally the prepared electrode was soaked in dilute sulfuric acid, washed and then placed in a vacuum oven for drying, to obtain a gas diffusion electrode.

[0057] Example 6

[0058] 10 mL of 0.2 M Cu(NO3)2·3H2O solution was measured, then 20 mL of ethylene glycol and 10 mL of ultrapure water were added to the above solution, H2SO4 was used to adjust the pH of the solution to 3.0, and the solution was stirred uniformly, the water bath was heated to 60°C, and magnetic stirring was carried out for 10 min, then 10 mL of 5 M NaOH solution was added, and after 5 min of reaction, 10 mL of 1 M glucose was added within 30 s for reduction, the water bath temperature was maintained at 60°C, and the reaction was continued for 30 min, to prepare Cu2O@Cu-Cu V Colloidal solution of core-shell structure catalytic material, then the colloidal solution was centrifuged, washed with ultrapure water and vacuum dried, and then the prepared Cu2O@Cu-Cu V Core-shell electrode catalytic material, 0.5 mL of methanol was dissolved and 5 μL of 5 wt% naphthol (Nafion) solution was added, and the carbon substrate prepared in advance was scraped and coated by scraping coating to prepare C-Cu2O@Cu-Cu V Electrode, 10 mL of 0.2 M Cu(NO3)2·3H2O solution was mixed with 30 mL of 0.06 M polyethylene glycol solution, the mixed solution was used as electrolyte, under the protection of N2, and under the condition of constant voltage of -0.3 V (vs. Ag / AgCl), C-Cu2O@Cu-Cu was obtained by electrodeposition for 1200 s V @Cu D Electrode, finally the prepared electrode was soaked in dilute sulfuric acid, washed and then placed in a vacuum oven for drying, to obtain a gas diffusion electrode.

[0059] Example 7

[0060] Take 10 mL of 0.2 M CuCl2·2H2O solution, then add 20 mL of methanol and 10 mL of ultrapure water to the above solution, adjust the pH of the solution to 3.0 with H2SO4, stir uniformly, water bath to 60℃, magnetic stirring for 10 min, then add 10 mL of 5M NaOH solution, react for 5 min, then add 10 mL of 1M glucose within 30s for reduction, keep the water bath temperature at 60℃, continue to react for 30 min, prepare Cu2O@Cu-Cu V core-shell structure of the colloidal solution of the catalytic material, then centrifugal separation of the colloidal solution, ultrapure water washing, vacuum drying, the prepared Cu2O@Cu-Cu V core-shell electrode catalytic material, 0.5 mL of methanol is dissolved and 5 μL of 5 wt% naphthol (Nafion) solution is added, and the carbon substrate prepared in advance is scraped by scraping method to prepare C-Cu2O@Cu-Cu V electrode, 10 mL of 0.2 M CuCl2·2H2O solution is mixed with 30 mL of 0.06 M OP (alkyl phenol polyoxyethylene ether) solution, the mixed solution is used as electrolyte, and C-Cu2O@Cu-Cu is obtained by electrodeposition under the protection of N2 and at a constant voltage of-0.3 V (vs. Ag / AgCl) for 1200 s V @Cu D electrode, finally the prepared electrode is soaked in dilute sulfuric acid, washed and then dried in a vacuum oven to obtain a gas diffusion electrode.

[0061] Example 8

[0062] Take 10 mL of 0.2 M CuCl2·2H2O solution, then add 20 mL of methanol and 10 mL of ultrapure water to the above solution, adjust the pH of the solution to 3.0 with H2SO4, stir uniformly, water bath to 60℃, magnetic stirring for 10 min, then add 10 mL of 5M NaOH solution, react for 5 min, then add 10 mL of 1M glucose within 30s for reduction, keep the water bath temperature at 60℃, continue to react for 30 min, prepare Cu2O@Cu-Cu V core-shell structure of the colloidal solution of the catalytic material, then centrifugal separation of the colloidal solution, ultrapure water washing, vacuum drying, the prepared Cu2O@Cu-Cu V core-shell electrode catalytic material, 0.5 mL of methanol is dissolved and 5 μL of 5 wt% naphthol (Nafion) solution is added, and the carbon substrate prepared in advance is scraped by scraping method to prepare C-Cu2O@Cu-Cu VElectrode, 10 mL of 0.2 M CuCl2·2H2O solution was mixed with 30 mL of 0.06 M OP (alkyl phenol polyoxyethylene ether) solution, the mixed solution was used as electrolyte, under the protection of N2, constant voltage was-0.3 V (vs. Ag / AgCl), electrodeposition was carried out for 800 s, and C-Cu2O@Cu-Cu was obtained V @Cu D Electrode, the prepared electrode was soaked and washed with dilute sulfuric acid, and then dried in a vacuum oven to obtain a gas diffusion electrode.

[0063] Comparative Example 1

[0064] 10 mL of 0.2 M CuCl2·2H2O solution was measured, and then 20 mL of ethylene glycol and 10 mL of ultrapure water were added to the above solution. H2SO4 was used to adjust the pH of the solution to 3.0, and the solution was stirred uniformly. The water bath was heated to 60°C, and magnetic stirring was carried out for 10 min. Then 10 mL of 5 M NaOH solution was added, and the reaction was carried out for 5 min. 10 mL of 1 M glucose was added within 30 s for reduction. The water bath temperature was maintained at 60°C, and the reaction was continued for 30 min. Cu2O@Cu-Cu V The colloidal solution of the core-shell structure catalytic material was centrifuged, washed with ultrapure water, and vacuum dried. The prepared Cu2O@Cu-Cu V The core-shell electrode catalytic material was dissolved in 0.5 mL of methanol and 5 μL of 5 wt% naphthol (Nafion) solution was added. A carbon substrate prepared in advance was scraped and coated by using a scraping method to prepare C-Cu2O@Cu-Cu. V Electrode, the prepared electrode was soaked and washed with dilute sulfuric acid, and then dried in a vacuum oven to obtain a gas diffusion electrode.

[0065] Comparative Example 2

[0066] 10 mL of 0.2 M CuCl2·2H2O solution was measured, and then 20 mL of ethylene glycol and 10 mL of ultrapure water were added to the above solution. H2SO4 was used to adjust the pH of the solution to 3.0, and the solution was stirred uniformly. The water bath was heated to 60°C, and magnetic stirring was carried out for 10 min. Then 10 mL of 5 M NaOH solution was added, and the reaction was carried out for 5 min. 10 mL of 1 M ascorbic acid was added within 30 s for reduction. The water bath temperature was maintained at 60°C, and the reaction was continued for 30 min. Cu2O@Cu-Cu V The colloidal solution of the core-shell structure catalytic material was centrifuged, washed with ultrapure water, and vacuum dried. The prepared Cu2O@Cu-Cu VCore-shell electrode catalytic material, 0.5 mL of methanol was dissolved and 5 μL of 5 wt% naphthol (Nafion) solution was added, and the carbon substrate prepared in advance was scraped by scraping method to prepare C-Cu2O@Cu-Cu V Electrode, 10 mL of 0.2 M CuCl2·2H2O solution was mixed with 30 mL of 0.06 M octylphenyl polyoxyethylene ether solution as electrolyte, under the protection of N2, the constant current was-30 mA, and the electrodeposition time was 1200 s to obtain C-Cu2O@Cu-Cu V @Cu D Electrode, the prepared electrode was soaked and washed with dilute sulfuric acid, and then dried in a vacuum oven to obtain a gas diffusion electrode.

[0067] Comparative example 3

[0068] 10 mL of 0.2 M CuCl2·2H2O solution was measured, and then 20 mL of ethylene glycol and 10 mL of ultrapure water were added to the above solution. H2SO4 was used to adjust the pH of the solution to 3.0, and then stirred uniformly. The water bath was heated to 60°C, and then 10 mL of 5M NaOH solution was added after 10 min of magnetic stirring. After 5 min of reaction, 10 mL of 1M glucose was added within 30 s for reduction. The water bath temperature was maintained at 60°C, and the reaction was continued for 30 min to prepare Cu2O@Cu-Cu V Colloidal solution of core-shell structure catalytic material, then the colloidal solution was centrifuged, washed with ultrapure water and vacuum dried. The prepared Cu2O@Cu-Cu V Core-shell electrode catalytic material, 0.5 mL of methanol was dissolved and 5 μL of 5 wt% naphthol (Nafion) solution was added, and the carbon substrate prepared in advance was scraped by scraping method to prepare C-Cu2O@Cu-Cu V Electrode. 10 mL of 0.2 M CuCl2·2H2O solution was mixed with 30 mL of 0.06 M octylphenyl polyoxyethylene ether solution as electrolyte, under the protection of N2, the constant current was-30 mA, and the electrodeposition time was 1200 s to obtain C-Cu2O@Cu-Cu V @Cu D Electrode, the prepared electrode was soaked and washed with dilute sulfuric acid, and then dried in a vacuum oven to obtain a gas diffusion electrode.

[0069] Comparative example 4

[0070] Take 10 mL of 0.2 M CuCl2·2H2O solution, then add 20 mL of ethylene glycol and 10 mL of ultrapure water to the above solution, adjust the pH of the solution to 3.0 with H2SO4, stir uniformly, and heat the water bath to 100°C. After 10 minutes of magnetic stirring, add 10 mL of 5 M NaOH solution, react for 5 minutes, then add 10 mL of 1 M glucose for reduction within 30 seconds. Maintain the 100°C water bath temperature and continue to react for 30 minutes to prepare Cu2O@Cu-Cu V core-shell structured catalytic material colloid solution, then centrifuge the colloid solution, wash with ultrapure water, and vacuum dry to obtain Cu2O@Cu-Cu V core-shell electrode catalytic material, dissolve 0.5 mL of methanol and add 5 μL of 5 wt% naphthol (Nafion) solution, and use the scraping method to scrape the carbon substrate prepared in advance to obtain C-Cu2O@Cu-Cu V electrode, mix 10 mL of 0.2 M CuCl2·2H2O solution with 30 mL of 0.06 M octylphenyl polyoxyethylene ether solution as an electrolyte, and electrodeposition at a constant voltage of -0.3 V (vs. Ag / AgCl) under N2 protection for 1200 s to obtain C-Cu2O@Cu-Cu V @Cu D electrode, soak and wash the prepared electrode with dilute sulfuric acid, and then dry it in a vacuum oven to obtain a gas diffusion electrode.

[0071] Comparative Example 5

[0072] Take 10 mL of 0.2 M CuCl2·2H2O solution, then add 20 mL of ethylene glycol and 10 mL of ultrapure water to the above solution, adjust the pH of the solution to 3.0 with H2SO4, stir uniformly, and heat the water bath to 60°C. After 10 minutes of magnetic stirring, add 10 mL of 5 M NaOH solution, react for 5 minutes, then add 10 mL of 1 M glucose for reduction within 30 seconds. Maintain the 60°C water bath temperature and continue to react for 10 minutes to prepare Cu2O@Cu-Cu V core-shell structured catalytic material colloid solution, then centrifuge the colloid solution, wash with ultrapure water, and vacuum dry to obtain Cu2O@Cu-Cu V core-shell electrode catalytic material, dissolve 0.5 mL of methanol and add 5 μL of 5 wt% naphthol (Nafion) solution, and use the scraping method to scrape the carbon substrate prepared in advance to obtain C-Cu2O@Cu-Cu VElectrode, 10 mL of 0.2 M CuCl2·2H2O solution was mixed with 30 mL of 0.06 M octylphenyl polyoxyethylene ether solution as electrolyte, under the protection of N2, constant voltage of-0.3 V (vs. Ag / AgCl) was used for electrodeposition for 1200 s, to obtain C-Cu2O@Cu-Cu V @Cu D Electrode, the prepared electrode was soaked in dilute sulfuric acid, washed and then placed in a vacuum oven for drying to obtain a gas diffusion electrode.

[0073] Comparative Example 6

[0074] 10 mL of 0.2 M CuCl2·2H2O solution was measured, and then 20 mL of ethylene glycol and 10 mL of ultrapure water were added to the above solution. H2SO4 was used to adjust the pH of the solution to 3.0, and the solution was stirred uniformly. The water bath was heated to 60°C, and magnetic stirring was performed for 10 min. Then, 10 mL of 5 M NaOH solution was added, and the reaction was performed for 5 min. Subsequently, 10 mL of 1 M glucose was added for reduction within 30 s. The water bath temperature was maintained at 60°C, and the reaction was continued for 100 min to prepare Cu2O@Cu-Cu V core-shell structure catalytic material colloid solution, and then the colloid solution was centrifuged, washed with ultrapure water and vacuum dried. The prepared Cu2O@Cu-Cu V core-shell electrode catalytic material was dissolved in 0.5 mL of methanol and 5 μL of 5 wt% naphthol (Nafion) solution was added. The carbon substrate prepared in advance was scraped and coated by using a scraping method to prepare C-Cu2O@Cu-Cu V Electrode, 10 mL of 0.2 M CuCl2·2H2O solution was mixed with 30 mL of 0.06 M octylphenyl polyoxyethylene ether solution as electrolyte, under the protection of N2, constant voltage of-0.3 V (vs. Ag / AgCl) was used for electrodeposition for 1200 s, to obtain C-Cu2O@Cu-Cu V @Cu D Electrode, the prepared electrode was soaked in dilute sulfuric acid, washed and then placed in a vacuum oven for drying to obtain a gas diffusion electrode.

[0075] The prepared electrode was used as the cathode of the electrochemical catalytic reduction of carbon dioxide reaction system. The experiment was performed by using a three-electrode system for electrochemical test. The prepared electrode was 1 cm x 1 cm, which was used as the working electrode. Ag / AgCl electrode was used as the reference electrode, and platinum sheet electrode was used as the counter electrode. The cathode chamber and the anode chamber were both 40 mL of 0.5 M KCl solution. During the electrocatalytic reduction of CO2, the CO2 flow was set to 300 mL / min, and the catalytic reduction products were detected every 15 min.

[0076] Specifically,Figure 1 and Figure 2 Figure 2 are product distribution diagrams of the reduction products of Example 1 and Example 2, respectively. The difference between them is that the reducing agents used are different. In Example 1, when glucose is selected as the reducing agent, the highest Faraday efficiency of CH4 generated at -1.38 V (V vs RHE) is 23%, the Faraday efficiency of C2H4 is 12%, and the total Faraday efficiency reaches 35%; in Example 2, when ascorbic acid is selected as the reducing agent, the highest Faraday efficiency of CH4 generated is 18%, the Faraday efficiency of C2H4 is 12%, and the total Faraday efficiency only reaches 30%; and from the overall reduction potential trend, it can be seen that when the reducing agent is glucose or ascorbic acid, the Faraday efficiency of the reduction product first increases and then decreases with the increase of the potential, and there is a highest point, and a certain amount of C2H4 is generated, but the catalytic performance is better when the reducing agent is glucose.

[0077] Specifically, Figure 2 Figure 3 is the product distribution diagram of Comparative Example 1. Compared with Figure 2 Figure 1 , it can be concluded that the Faraday efficiency of CH4 and C2H4 in the reduction product after the C-Cu2O@Cu-Cu V electrode is used to catalytically reduce carbon dioxide, which is reduced, which shows that the step of treating the surface of the catalyst by constant-voltage electrodeposition is crucial to improve the performance of the catalyst.

[0078] Specifically, Figure 2 Figure 4 is the product distribution diagram of Comparative Example 2. Compared with Figure 2 Figure 1 , it can be concluded that the Faraday efficiency of CH4 and C2H4 in the reduction product after the electrode prepared by electrodeposition with constant current in Comparative Example 2 is reduced. This shows that compared with the traditional current deposition technology, the method of constant-voltage electrodeposition can deposit a uniform and flat catalytic layer.

[0079] In actual application, the uniform and flat distribution structure of the prepared catalytic layer has consistent crystal face characteristics, which not only can provide as many active centers as possible, but also is more conducive to improving the selectivity of a single product, and has the characteristics of smooth proton channels and product and reactant mass transfer channels, improves the utilization rate of catalytic active centers and electrochemical stability, promotes the diffusion of reaction raw materials and products, thereby improving the current density and improving the catalytic activity.

[0080]

[0081]

[0082]

[0083] Table 1 is the product distribution of the reduction of the electrode in the saturated KCl solution of CO2 in the examples and the comparative examples of the present application

[0084] Specifically, the product distribution of the comparative example 3 in Table 1, compared with the attached Figure 1 It can be concluded that the electrode prepared by directly electrodeposition without adding additives in the solution during the constant voltage electrodeposition part of the comparative example 3, the Faraday efficiency of CH4 and C2H4 in the reduction products after catalytic reduction is reduced, which shows that the addition of the additive has a great influence on the selectivity and activity of the catalyst. This is mainly because octyl phenyl polyoxyethylene ether, Tween 20, polyethylene glycol, OP (alkyl phenol polyoxyethylene ether) are physical and chemical inert polymers, which can reversibly adsorb on the copper surface, thereby increasing the nucleation rate and reducing the grain size in kinetics. In addition, the inertness of octyl phenyl polyoxyethylene ether, Tween 20, polyethylene glycol, OP (alkyl phenol polyoxyethylene ether) can also avoid the introduction of carbon contamination, improve the stability of the catalyst, and prevent the catalyst from being poisoned and deactivated.

[0085] Specifically, the product distribution of the comparative example 4 in Table 1, compared with the attached Figure 1 It can be concluded that the electrode prepared by directly electrodeposition without adding additives in the solution during the constant voltage electrodeposition part of the comparative example 3, the Faraday efficiency of CH4 and C2H4 in the reduction products after catalytic reduction is reduced, which shows that the addition of the additive has a great influence on the selectivity and activity of the catalyst. This is mainly because octyl phenyl polyoxyethylene ether, Tween 20, polyethylene glycol, OP (alkyl phenol polyoxyethylene ether) are physical and chemical inert polymers, which can reversibly adsorb on the copper surface, thereby increasing the nucleation rate and reducing the grain size in kinetics. In addition, the inertness of octyl phenyl polyoxyethylene ether, Tween 20, polyethylene glycol, OP (alkyl phenol polyoxyethylene ether) can also avoid the introduction of carbon contamination, improve the stability of the catalyst, and prevent the catalyst from being poisoned and deactivated.

[0086] Specifically, the product distribution of the comparative example 5 in Table 1, compared with the attached Figure 1 It can be concluded that the electrode prepared by directly electrodeposition without adding additives in the solution during the constant voltage electrodeposition part of the comparative example 3, the Faraday efficiency of CH4 and C2H4 in the reduction products after catalytic reduction is reduced, which shows that the addition of the additive has a great influence on the selectivity and activity of the catalyst. This is mainly because octyl phenyl polyoxyethylene ether, Tween 20, polyethylene glycol, OP (alkyl phenol polyoxyethylene ether) are physical and chemical inert polymers, which can reversibly adsorb on the copper surface, thereby increasing the nucleation rate and reducing the grain size in kinetics. In addition, the inertness of octyl phenyl polyoxyethylene ether, Tween 20, polyethylene glycol, OP (alkyl phenol polyoxyethylene ether) can also avoid the introduction of carbon contamination, improve the stability of the catalyst, and prevent the catalyst from being poisoned and deactivated.

[0087] Specifically, the product distribution of the comparative example 6 in Table 1, compared with the attached Figure 1 It can be concluded that the electrode prepared by directly electrodeposition without adding additives in the solution during the constant voltage electrodeposition part of the comparative example 3, the Faraday efficiency of CH4 and C2H4 in the reduction products after catalytic reduction is reduced, which shows that the addition of the additive has a great influence on the selectivity and activity of the catalyst. This is mainly because octyl phenyl polyoxyethylene ether, Tween 20, polyethylene glycol, OP (alkyl phenol polyoxyethylene ether) are physical and chemical inert polymers, which can reversibly adsorb on the copper surface, thereby increasing the nucleation rate and reducing the grain size in kinetics. In addition, the inertness of octyl phenyl polyoxyethylene ether, Tween 20, polyethylene glycol, OP (alkyl phenol polyoxyethylene ether) can also avoid the introduction of carbon contamination, improve the stability of the catalyst, and prevent the catalyst from being poisoned and deactivated. VThe core-shell structure is destroyed, resulting in reduced selectivity and activity of the catalyst.

Claims

1. A gas diffusion electrode for the electroreduction of carbon dioxide, characterized in that: The gas diffusion electrode comprises catalyst C-Cu2O@Cu-CuV@CuD and Nafion, and the composition ratio of catalyst C-Cu2O@Cu-CuV@CuD to Nafion is 3:1-1:

4. The catalyst C-Cu2O@Cu-CuV@CuD has a core-shell structure, wherein CuD is the shell, Cu2O@Cu-CuV is the core, and C is the substrate. The composition of the catalyst C-Cu2O@Cu-CuV@CuD is: CuD content is 50-87wt%, Cu-CuV content is 10-25wt%, and Cu2O content is 3-25wt%. The method for preparing the gas diffusion electrode includes the following steps: S1: Mix copper salt with water and alcohol solution, and add dilute sulfuric acid to adjust the pH value of copper salt solution. Then, in a water bath, add sodium hydroxide dropwise under magnetic stirring. After the reaction, Cu(OH)X is formed. Then, a reducing agent is added to reduce part of the oxide to prepare a colloidal solution containing Cu2O@Cu-CuV core-shell structure catalytic material. The colloidal solution is then centrifuged, washed, dried, and vacuum stored for later use. S2: Bake the carbon paper substrate at 350-600℃ for 1-12 hours, then wash the baked carbon substrate with water and ethanol using ultrasound, and dry it for later use. S3: The prepared Cu2O@Cu-CuV material was added to a mixture of alcohol solution and 5wt% Nafion solution. After being evenly dispersed, the C-Cu2O@Cu-CuV catalyst layer was prepared on a carbon paper substrate by scraping or spraying. S4: Mix copper salt with stabilizer and stir magnetically for 20-60 min to form a precursor copper salt solution. Under inert gas protection and at room temperature, electrodeposit CuD on the surface of the C-Cu2O@Cu-CuV catalyst layer under constant voltage conditions. After soaking in dilute sulfuric acid, washing, and vacuum drying, a gas diffusion electrode with a core-shell structure C-Cu2O@Cu-CuV@CuD catalyst with controllable morphology is prepared. The concentration of the sodium hydroxide solution is 2-6M, the water bath temperature is 40-80℃, and the water bath time is 10-60min; The stabilizer is one or two of octylphenyl polyoxyethylene ether, Tween 20, polyethylene glycol, and OP, with a concentration of 0.02-0.18M; The reducing agent reduces part of the oxide in 800-2000 seconds.

2. The method for preparing a gas diffusion electrode for carbon dioxide electroreduction according to claim 1, characterized in that: The copper salts in step S4 are CuCl2·2H2O, Cu(NO3)2·3H2O, and CuSO4·5H2O. The concentration of copper ions in the precursor copper salt solution is 0.05-1.2M, and the pH of the precursor copper salt solution is 3.

0.

3. The method for preparing a gas diffusion electrode for carbon dioxide electroreduction according to claim 1, characterized in that: The alcohol solution is any one or more of methanol, ethanol, and ethylene glycol, and the volume ratio of the alcohol solution to water is 10:1 to 1:

10.

4. The method for preparing a gas diffusion electrode for carbon dioxide electroreduction according to claim 1, characterized in that: The reducing agent is one or two of glucose and ascorbic acid, and the concentration of the reducing agent is 0.5-1.5M.

5. The method for preparing a gas diffusion electrode for carbon dioxide electroreduction according to claim 1, characterized in that: The constant voltage is -0.3V to -2.0V, vs. Ag / AgCl.

6. The method for preparing a gas diffusion electrode for carbon dioxide electroreduction according to claim 1, characterized in that: The gas diffusion electrode used for the electroreduction of carbon dioxide serves as the cathode for the electrochemical reduction reaction of carbon dioxide.

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