Preparation method of flow-through gas diffusion electrode for electrochemical CO2 reduction

Abstract

The invention discloses a preparation method of a circulation type gas diffusion electrode for electrochemical CO2 reduction, and belongs to the technical field of electrochemical CO2 reduction. The circulation type gas diffusion electrode directly conveys carbon dioxide to the surface of a cathode in the electrochemical CO2 reduction process; the specific preparation method comprises the following steps: adding N-methyl-2-pyrrolidone into polyethyleneimine, and carrying out ultrasonic treatment; the preparation method comprises the following steps: adding copper powder into a transparent and uniform mixed solution of N-methyl-2-pyrrolidone and polyethyleneimine, and carrying out magnetic stirring; and calcining the uniform mixture of N-methyl-2-pyrrolidone, polyethyleneimine and copper powder and the hollow fiber of polyethyleneimine and copper powder in a smelting furnace to obtain the FTGDE electrode. By adopting the preparation method of the circulation type gas diffusion electrode for electrochemical CO2 reduction, disclosed by the invention, efficient transmission and utilization of carbon dioxide are ensured, and the electrochemical reduction reaction efficiency is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of electrochemical carbon dioxide reduction, and in particular to a method for preparing a flow-through gas diffusion electrode for electrochemical CO2 reduction. Background Art

[0002] Electrochemical CO2 reduction has become an important sustainable route to produce valuable chemicals and fuels, and is essential for closing the carbon cycle. In recent years, research has focused on developing advanced materials and optimizing electrocatalytic processes to improve the efficiency of this technology. To achieve high selectivity and high reaction rates, the electrode must have the characteristics of low cost, high activity and strong stability.

[0003] In a typical electrochemical carbon dioxide reduction (eCO2R) process, carbon dioxide usually enters the electrolyte through the cathode bubble to form a carbon dioxide saturated solution. Carbon dioxide needs to pass through the electrolyte to reach the surface of the electrocatalyst to participate in the reduction reaction. In a planar gas diffusion electrode (GDE), the efficiency of the reduction reaction depends largely on the concentration of dissolved carbon dioxide in the electrolyte. However, at room temperature (25°C) and standard atmospheric pressure (1atm), the solubility of carbon dioxide in water is only 34.5mmol·L -1 , the solubility is relatively low. Therefore, not enough carbon dioxide can reach the electrode surface, resulting in insufficient local carbon dioxide concentration. This deficiency reduces the reaction efficiency, which in turn affects the catalytic activity and product selectivity. At the same time, the competition for the hydrogen evolution reaction (HER) further reduces the performance of the system. The complex structure of GDE, the need for specialized equipment, and the high operating cost remain important issues. Summary of the invention

[0004] The purpose of the present invention is to provide a method for preparing a flow-through gas diffusion electrode for electrochemical CO2 reduction. The flow-through gas diffusion electrode (FTGDE) prepared by this method can directly transport carbon dioxide to the electrode surface to solve the above-mentioned problem that not enough carbon dioxide reaches the electrode surface, resulting in insufficient local carbon dioxide concentration.

[0005] To achieve the above object, the present invention provides a method for preparing a flow-through gas diffusion electrode for electrochemical CO2 reduction. The flow-through gas diffusion electrode directly transports carbon dioxide to the cathode surface during the electrochemical carbon dioxide reduction process, thereby improving the electrochemical carbon dioxide reduction efficiency. The specific preparation method of the flow-through gas diffusion electrode is as follows:

[0006] Step 1, weigh a certain amount of N-methyl-2-pyrrolidone and add it to a container containing polyacetimide; this process needs to be carried out in an environment with controlled temperature and humidity to ensure the stability of the material; ultrasonic treatment can effectively promote the mixing between the two substances, ensuring that NMP can fully penetrate into the molecular structure of PAI to form a transparent and uniform mixed solution a;

[0007] Step 2, adding the pre-prepared copper powder to the mixed solution a obtained in step 1; stirring for a long time with a magnetic stirrer to evenly disperse the copper powder in the mixed solution to form a mixture b;

[0008] Step three, calcining and hydrogenating the mixture b and the hollow fibers made of polyimide and copper powder in a furnace, gradually raising the temperature to a preset high temperature to remove the organic solvent and part of the polymer components while keeping the structure of the copper unchanged; hydrogenation is carried out in a hydrogen atmosphere, which helps to improve the conductivity and active surface area of ​​the copper, thereby obtaining a flow-through gas diffusion electrode.

[0009] Preferably, in the above-mentioned method for preparing a flow-through gas diffusion electrode for electrochemical CO2 reduction, the ultrasonic treatment time in step 1 is 2 hours.

[0010] Preferably, in the above-mentioned method for preparing a flow-through gas diffusion electrode for electrochemical CO2 reduction, the magnetic stirring condition in step 2 is stirring at 60°C for 24 hours.

[0011] Preferably, in the above-mentioned method for preparing a flow-through gas diffusion electrode for electrochemical CO2 reduction, the calcination conditions in step 3 are sintering at 650°C for 2 hours, and the heating and cooling rates are 5°C min -1 .

[0012] Preferably, in the above-mentioned method for preparing a flow-through gas diffusion electrode for electrochemical CO2 reduction, the hydrogenation condition in step 3 is hydrogenation at 500°C for 1 hour.

[0013] Preferably, in the above-mentioned method for preparing a flow-through gas diffusion electrode for electrochemical CO2 reduction, the flow-through gas diffusion electrode is based on a hollow fiber structure to form an internal hollow structure.

[0014] Therefore, the present invention adopts the preparation method of the flow-through gas diffusion electrode for electrochemical CO2 reduction of the above structure, and the carbon dioxide is directly delivered to the electrode surface through the flow-through gas diffusion electrode (FTGDE). The unique geometric design of the electrode ensures the efficient transmission and utilization of carbon dioxide, improves the reaction kinetics, and thus improves the overall system performance. The porous structure of FTGDE promotes direct contact between gas (carbon dioxide), liquid (potassium bicarbonate) and solid (copper), forming an optimized three-phase interface. This improved interface significantly enhances the reduction reaction, improves selectivity and efficiency, and ultimately helps to improve the stability and long-term performance of the system. In the gas diffusion configuration, FTGDE increases the reaction efficiency by forcing CO2 to pass through the electrode wall, forming internal pressure, and increasing the three-phase interface. The resulting turbulence promotes the interaction between CO2 and the active sites, enhancing the reduction reaction. The circulation mechanism of FTGDE improves the transport of CO2, especially at high current density, which is crucial to ensure effective electrochemical CO2 reduction reaction (eCO2R) performance. Higher CO2 concentrations also suppress competition with the hydrogen evolution reaction (HER), which interferes with product generation in traditional systems. The hollow and compact structure of FTGDE increases the surface area required for the key reduction reaction without increasing the overall size of the battery. In addition, FTGDE is manufactured using an economical phase transfer and calcination process, avoiding the need for large and complex equipment.

[0015] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 A preparation flow chart of an embodiment of a method for preparing a flow-through gas diffusion electrode for electrochemical CO2 reduction according to the present invention;

[0017] Figure 2 A scanning electron microscope image of a Cu flow-through gas diffusion electrode according to an embodiment of the method for preparing a flow-through gas diffusion electrode for electrochemical CO2 reduction of the present invention;

[0018] Figure 3 This is a demonstration diagram of the transfer of carbon dioxide to the cathode surface, the reaction mechanism and product formation in the gas diffusion device and the non-gas diffusion device in the embodiment of the method for preparing a flow-through gas diffusion electrode for electrochemical CO2 reduction of the present invention. DETAILED DESCRIPTION

[0019] In order to better understand the above technical solution, the above technical solution will be described in detail below in conjunction with the accompanying drawings and specific implementation methods. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0020] The terms used in the embodiments of the present invention are only for the purpose of describing specific embodiments, and are not intended to limit the present invention. The singular forms "a", "said" and "the" used in the embodiments of the present invention and the appended claims are also intended to include plural forms, unless the context clearly indicates other meanings, and "multiple" generally includes at least two.

[0021] It should also be noted that the term "includes", "comprising" or any other variation thereof is intended to cover non-exclusive inclusion, so that a commodity or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such commodity or device. In the absence of more restrictions, the elements defined by the sentence "comprising a ..." do not exclude the existence of other identical elements in the commodity or device including the elements.

[0022] Example

[0023] See attached Figure 1-3 The present application provides a method for preparing a flow-through gas diffusion electrode for electrochemical CO2 reduction. The flow-through gas diffusion electrode directly transports carbon dioxide to the cathode surface during the electrochemical carbon dioxide reduction process to improve the electrochemical carbon dioxide reduction efficiency. The specific preparation method of the flow-through gas diffusion electrode is as follows:

[0024] Step 1, weigh a certain amount of N-methyl-2-pyrrolidone and add it to a container containing polyacetimide; this process needs to be carried out in an environment with controlled temperature and humidity to ensure the stability of the material; ultrasonic treatment can effectively promote the mixing between the two substances, ensuring that NMP can fully penetrate into the molecular structure of PAI to form a transparent and uniform mixed solution a;

[0025] N-methyl-2-pyrrolidone (NMP) was chosen as the solvent because it has good solubility and stability, and can effectively promote the dissolution of polyacetimide (PAI) to form a uniform and stable solution. Polyacetimide is a high-performance polymer known for its excellent thermal stability and mechanical properties, and is suitable as a base material for gas diffusion electrodes. The copper powder was selected for its conductivity and catalytic effect in the subsequent hydrogenation process.

[0026] Step 2, adding the pre-prepared copper powder to the mixed solution a obtained in step 1; stirring for a long time with a magnetic stirrer to evenly disperse the copper powder in the mixed solution to form a mixture b;

[0027] Step three, calcining and hydrogenating the mixture b and the hollow fibers made of polyimide and copper powder in a furnace, gradually raising the temperature to a preset high temperature to remove the organic solvent and part of the polymer components while keeping the structure of the copper unchanged; hydrogenation is carried out in a hydrogen atmosphere, which helps to improve the conductivity and active surface area of ​​the copper, thereby obtaining a flow-through gas diffusion electrode.

[0028] To further optimize the above technical solution, the ultrasonic treatment time in step 1 is 2 hours.

[0029] Specifically, ultrasonic treatment is used to accelerate the dissolution process of polyacetimide in N-methyl-2-pyrrolidone and ensure that the resulting solution has a high degree of uniformity and transparency. The cavitation effect generated by ultrasound helps to destroy the agglomeration between particles and make the dispersion more delicate, which is crucial to improving the performance of the final product.

[0030] To further optimize the above technical solution, the magnetic stirring condition in step 2 is stirring at 60° C. for 24 hours.

[0031] It should be noted that the purpose of introducing copper powder and performing magnetic stirring in step 2 is to achieve uniform distribution of copper powder in the solution, thereby ensuring uniformity and efficiency of the reaction in the subsequent treatment process. At the same time, magnetic stirring also helps to remove possible bubbles and further improve the quality of the mixture.

[0032] To further optimize the above technical solution, the calcination conditions in step 3 are sintering at 650°C for 2 hours, and the heating and cooling rate is 5°C min -1 .

[0033] To further optimize the above technical solution, the hydrogenation condition in step 3 is hydrogenation at 500° C. for 1 hour.

[0034] Specifically, in step three, by placing the mixture b containing copper powder and the polyimide-copper powder hollow fiber under specific conditions for calcination and hydrogenation, this process can not only promote the cross-linking reaction of polyimide and enhance its structural strength, but also activate the surface of copper powder and promote the effective adsorption and conversion of gas molecules. Specifically, appropriate temperature and atmosphere conditions are critical for forming an ideal electrode structure. The structure formed by calcination and hydrogenation ensures that FTGDE has sufficient porosity so that CO2 can effectively penetrate the electrode wall. In addition, when it is applied to the electrochemical carbon dioxide reduction process, maintaining an appropriate CO2 flow rate (such as 20ml / min) can continuously and sufficiently provide CO2 to the catalyst surface, thereby improving the performance of the overall electrochemical CO2 reduction reaction.

[0035] To further optimize the above technical solution, the flow-through gas diffusion motor is based on a hollow fiber structure to form an internal hollow structure, thereby increasing the surface area required for the key reduction reaction.

[0036] like Figure 3 As shown, a demonstration of the transfer of carbon dioxide to the cathode surface, the reaction mechanism, and product formation in gas diffusion and non-gas diffusion configurations is compared; in the gas diffusion configuration, CO2 passes through the electrode wall, forming internal pressure and increasing the three-phase interface, thereby improving the reaction efficiency. The resulting turbulence promotes the interaction between CO2 and the active sites and enhances the reduction reaction. In contrast, in the non-gas diffusion configuration, the gas only flows on the electrode surface and does not fully contact the electrolyte. Therefore, compared with the non-gas diffusion configuration, the gas diffusion configuration has significant advantages in improving product selectivity and catalytic activity.

[0037] Therefore, the present invention adopts the preparation method of the flow-through gas diffusion electrode for electrochemical CO2 reduction of the above structure, and the carbon dioxide is directly delivered to the electrode surface through the flow-through gas diffusion electrode (FTGDE). The unique geometric design of the electrode ensures the efficient transmission and utilization of carbon dioxide, improves the reaction kinetics, and thus improves the overall system performance. The porous structure of FTGDE promotes direct contact between gas (carbon dioxide), liquid (potassium bicarbonate) and solid (copper), forming an optimized three-phase interface. This improved interface significantly enhances the reduction reaction, improves selectivity and efficiency, and ultimately helps to improve the stability and long-term performance of the system. In the gas diffusion configuration, FTGDE increases the reaction efficiency by forcing CO2 to pass through the electrode wall, forming internal pressure, and increasing the three-phase interface. The resulting turbulence promotes the interaction between CO2 and the active sites, enhancing the reduction reaction. The circulation mechanism of FTGDE improves the transport of CO2, especially at high current density, which is crucial to ensure effective electrochemical CO2 reduction reaction (eCO2R) performance. Higher CO2 concentrations also suppress competition with the hydrogen evolution reaction (HER), which interferes with product generation in traditional systems. The hollow and compact structure of FTGDE increases the surface area required for the key reduction reaction without increasing the overall size of the battery. In addition, FTGDE is manufactured using an economical phase transfer and calcination process, avoiding the need for large and complex equipment.

[0038] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that they can still modify or replace the technical solution of the present invention with equivalents, and these modifications or equivalent replacements cannot cause the modified technical solution to deviate from the spirit and scope of the technical solution of the present invention.

Claims

1. A method for preparing a flow-through gas diffusion electrode for electrochemical CO2 reduction, characterized in that: The flow-through gas diffusion electrode directly transports carbon dioxide to the cathode surface during the electrochemical carbon dioxide reduction process, thereby improving the electrochemical carbon dioxide reduction efficiency. The specific preparation method of the flow-through gas diffusion electrode is as follows: Step 1, weigh a certain amount of N-methyl-2-pyrrolidone and add it to a container containing polyacetimide; this process needs to be carried out in an environment with controlled temperature and humidity to ensure the stability of the material; ultrasonic treatment can effectively promote the mixing between the two substances, ensuring that NMP can fully penetrate into the molecular structure of PAI to form a transparent and uniform mixed solution a; Step 2, adding the pre-prepared copper powder to the mixed solution a obtained in step 1; stirring for a long time with a magnetic stirrer to evenly disperse the copper powder in the mixed solution to form a mixture b; Step three, calcining and hydrogenating the mixture b and the hollow fibers made of polyimide and copper powder in a furnace, gradually raising the temperature to a preset high temperature to remove the organic solvent and part of the polymer components while keeping the structure of the copper unchanged; hydrogenating the mixture in a hydrogen atmosphere helps to improve the conductivity and active surface area of ​​the copper, thereby obtaining a flow-through gas diffusion electrode.

2. The method for preparing a flow-through gas diffusion electrode for electrochemical CO2 reduction according to claim 1, characterized in that: The ultrasonic treatment time in the step 1 is 2 hours.

3. The method for preparing a flow-through gas diffusion electrode for electrochemical CO2 reduction according to claim 2, characterized in that: The magnetic stirring condition in the step 2 is stirring at 60° C. for 24 hours.

4. The method for preparing a flow-through gas diffusion electrode for electrochemical CO2 reduction according to claim 3, characterized in that: The calcination conditions in step 3 are sintering at 650°C for 2 hours, and the heating and cooling rate is 5°C min -1 .

5. The method for preparing a flow-through gas diffusion electrode for electrochemical CO2 reduction according to claim 4, characterized in that: The hydrogenation condition in the step 3 is hydrogenation at 500° C. for 1 hour.

6. The method for preparing a flow-through gas diffusion electrode for electrochemical CO2 reduction according to claim 5, characterized in that: The flow-through gas diffusion motor is based on a hollow fiber structure to form an internal hollow structure.

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