Bismuth catalyst for electrocatalytic conversion of carbon dioxide and preparation method thereof
By using flocculent porous bismuth catalyst in CO2RR, the problem of low efficiency of the existing Bi-based catalyst is solved, and the effect of efficient and selective formation of formic acid or formate is achieved, and the activity and production efficiency of the catalyst are improved.
Patent Information
- Application Number
- CN202411580836.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-11-07
- Publication Date
- 2025-02-14
AI Technical Summary
The existing Bi-based catalysts have low efficiency and limited activity in selective formation of formic acid or formate during CO2RR.
A saturated organic precursor solution containing Bi3+ was arranged using a bismuth salt and an organic solvent, and a flocculent porous bismuth catalyst was formed by electrodeposition through constant current, and a catalyst with a particle size less than 100 μm was obtained by post-treatment.
The Faraday efficiency of the bismuth catalyst selectively forms formic acid or formate during the CO2RR process is achieved by more than 90%, which improves the activity and production efficiency of the catalyst and has significant commercial feasibility.
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Abstract
Description
Technical Field
[0001] The present invention belongs to the technical field of electrocatalysis, and in particular relates to a bismuth catalyst for electrocatalytic conversion of carbon dioxide and a preparation method thereof. Background Art
[0002] Using electrocatalytic CO2 reduction reaction (CO2RR) to convert CO2 into carbon-containing chemicals is an effective way to achieve carbon neutrality. For example, carbon-containing chemicals can be C1 products such as carbon monoxide CO, formic acid HCOOH, methanol, methane, etc.; C2 products such as ethylene, ethanol, acetate, ethylene glycol, etc.; C 2+ Products include propanol, propionaldehyde, etc.
[0003] Among the C1 products obtained by CO2RR, formic acid or formates have many advantages and have attracted much attention as hydrogen carriers for fuel cells and as chemical raw materials.
[0004] Among the p-block metals, Sn, In and Bi are oxygen-philic. Among them, Bi is considered to be a strong candidate for the production of formic acid via CO2RR due to its low toxicity, low cost and ability to selectively form formic acid or formates during the CO2RR process. However, the Faradaic efficiency of Bi-based catalysts for the selective formation of formic acid or formates during the CO2RR process needs to be improved and their activity is limited. Summary of the invention
[0005] In view of this, some embodiments disclose a method for preparing a bismuth catalyst for electrocatalytic conversion of carbon dioxide, comprising:
[0006] The bismuth salt and the organic solvent are prepared to contain Bi 3+ A saturated organic precursor solution; wherein the bismuth salt is BiCl3, Bi(NO3)3·5H2O, Bi2(SO4)3, Bi(CH3COO)3 or Bi(C6H5O7); the organic solvent is a combination of one or more of ethylene glycol, glycerol, acetone and ether;
[0007] Contains Bi 3+ The saturated organic precursor solution is used as the electrolyte to form an electrolysis system with two platinum electrodes;
[0008] The electrolytic system performs constant current electrodeposition under stirring conditions; wherein the cathode is used as the working electrode and the cathode current density is 10 to 500 mA / cm 2 , the deposition time is 30 to 200 minutes;
[0009] During the constant current electrodeposition process, Bi in the saturated organic precursor solution 3+ Reduction to form metallic Bi particles, and particle deposition to obtain a flocculent porous bismuth catalyst.
[0010] In the method for preparing a bismuth catalyst for electrocatalytic conversion of carbon dioxide disclosed in some embodiments, the area of the platinum sheet electrode used as the cathode is less than or equal to the area of the platinum sheet electrode used as the anode.
[0011] In the preparation method of the bismuth catalyst for electrocatalytic conversion of carbon dioxide disclosed in some embodiments, the stirring speed is 50 to 200 rpm.
[0012] Some embodiments disclose a method for preparing a bismuth catalyst for electrocatalytic conversion of carbon dioxide, wherein the cathode current density is 20 to 100 mA / cm 2 .
[0013] Some embodiments disclose a method for preparing a bismuth catalyst for electrocatalytic conversion of carbon dioxide. During constant current electrodeposition, a bismuth salt is added to a saturated organic precursor solution in small amounts multiple times to allow the reaction to proceed continuously.
[0014] Some embodiments disclose a method for preparing a bismuth catalyst for electrocatalytic conversion of carbon dioxide. During a constant current electrodeposition process, a bismuth salt is added to a saturated organic precursor solution by spraying.
[0015] The method for preparing a bismuth catalyst for electrocatalytic conversion of carbon dioxide disclosed in some embodiments also includes post-processing the prepared flocculent porous bismuth catalyst to obtain a bismuth catalyst with a particle size of less than 100 μm.
[0016] Some embodiments disclose a method for preparing a bismuth catalyst for electrocatalytic conversion of carbon dioxide, wherein the post-processing specifically comprises:
[0017] The flocculent porous bismuth catalyst is taken out from the saturated organic precursor solution;
[0018] The flocculent and porous bismuth catalyst was washed several times with anhydrous alcohol;
[0019] Drying the washed flocculent porous bismuth catalyst at a drying temperature of less than 80° C.
[0020] The dried bismuth catalyst is sieved to obtain a bismuth catalyst with a particle size of less than 100 μm.
[0021] Some embodiments disclose a bismuth catalyst for electrocatalytic conversion of carbon dioxide, which is obtained by the above-mentioned preparation method of the bismuth catalyst for electrocatalytic conversion of carbon dioxide.
[0022] Some embodiments disclose a bismuth catalyst for electrocatalytic conversion of carbon dioxide, wherein the bismuth catalyst has a Faraday efficiency of more than 90% for selectively forming formic acid or formate during the electrocatalytic conversion of carbon dioxide.
[0023] The bismuth catalyst for the electrocatalytic conversion of carbon dioxide disclosed in the embodiment of the present invention has good hydrophobic properties, which is beneficial to increase the carbon dioxide concentration on the surface of the electrocatalyst in the electrocatalytic carbon dioxide reduction reaction; it has a loose and porous structure, can provide abundant active sites, can effectively promote electron transfer and CO2 mass transfer, so that in the process of electrocatalytic carbon dioxide reduction, CO2 molecules can be efficiently adsorbed and activated to generate OCOH intermediates, thereby realizing efficient catalytic carbon dioxide reduction to formic acid or formates. The preparation method of the bismuth catalyst for the electrocatalytic conversion of carbon dioxide disclosed in the embodiment of the present invention can realize the large-scale preparation of bismuth catalysts in a short time and improve production efficiency; in addition, since the bismuth catalyst has high selectivity for the reduction of formic acid or formates, it has significant commercial feasibility and commercial value in terms of market demand, material cost, manufacturing and separation costs, etc. BRIEF DESCRIPTION OF THE DRAWINGS
[0024] Figure 1 Example 1 is a physical picture of a bismuth catalyst for electrocatalytic conversion of carbon dioxide;
[0025] Figure 2 Example 1 SEM image of bismuth catalyst for electrocatalytic conversion of carbon dioxide;
[0026] Figure 3 Example 1 SEM elemental scan of a bismuth catalyst for electrocatalytic conversion of carbon dioxide;
[0027] Figure 4 Example 1 EDS image of a bismuth catalyst for electrocatalytic conversion of carbon dioxide;
[0028] Figure 5 Example 1 XRD pattern of bismuth catalyst for electrocatalytic conversion of carbon dioxide;
[0029] Figure 6 Example 1 Comparison of LSV curves of CO2 reduction test performed on bismuth catalytic electrode for electrocatalytic conversion of carbon dioxide;
[0030] Figure 7 Example 1: Faraday efficiency diagram of H2, CO and HCOOH in the electrolyte at different potentials when the bismuth catalytic electrode was tested for CO2 reduction;
[0031] Figure 8 Example 1: Current density diagram of H2, CO and HCOOH in the electrolyte at different potentials when the bismuth catalytic electrode is subjected to CO2 reduction test. DETAILED DESCRIPTION
[0032] The word "embodiment" used here as an "exemplary" does not necessarily mean that any embodiment described is superior to or better than other embodiments. Unless otherwise specified, the performance index tests in the embodiments of this application are performed using conventional test methods in the art. It should be understood that the terms described in this application are only used to describe specific implementation methods and are not used to limit the content disclosed in this application.
[0033] Unless otherwise specified, the technical and scientific terms used in this document have the same meanings as commonly understood by ordinary technicians in the technical field to which this application belongs; other experimental methods and technical means not specifically specified in this application refer to experimental methods and technical means commonly used by ordinary technicians in this field.
[0034] The terms "substantially" and "approximately" used herein are used to describe small fluctuations. For example, they can refer to less than or equal to ±5%, such as less than or equal to ±2%, such as less than or equal to ±1%, such as less than or equal to ±0.5%, such as less than or equal to ±0.2%, such as less than or equal to ±0.1%, such as less than or equal to ±0.05%. The numerical data represented or presented in the range format herein are used only for convenience and brevity, and should therefore be flexibly interpreted as including not only the values clearly listed as the limits of the range, but also all independent values or sub-ranges contained in the range. For example, the numerical range of "1-5%" should be interpreted as including not only the clearly listed values of 1% to 5%, but also the independent values and sub-ranges within the range shown. Therefore, independent values such as 2%, 3.5% and 4% and sub-ranges such as 1%-3%, 2%-4% and 3%-5% are included in this numerical range. This principle also applies to the range of only one numerical value. In addition, such an interpretation applies regardless of the width of the range or the characteristics described.
[0035] In this document, including in the claims, transitional words such as "comprises," "includes," "with," "having," "containing," "involving," "accommodating," etc. are understood to be open-ended, i.e., meaning "including but not limited to." Only the transitional words "consisting of" and "composed of" are closed transitional words.
[0036] In order to better illustrate the content of the present application, numerous specific details are provided in the specific examples below. It should be understood by those skilled in the art that the present application can also be implemented without certain specific details. In the embodiments, some methods, means, instruments, equipment, etc. well known to those skilled in the art are not described in detail in order to highlight the main purpose of the present application.
[0037] Under the premise of no conflict, the technical features disclosed in the embodiments of the present application can be arbitrarily combined, and the obtained technical solutions belong to the contents disclosed in the embodiments of the present application. It should be noted that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like mentioned in the present application indicate the orientation or position relationship based on the orientation or position relationship shown in the accompanying drawings, which is only for the convenience of describing the technical features 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 cannot be understood as a limitation of the present invention, unless it conflicts with the context. In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance, unless it conflicts with the context.
[0038] In some embodiments, a method for preparing a bismuth catalyst for electrocatalytic conversion of carbon dioxide comprises:
[0039] The bismuth salt and the organic solvent are prepared to contain Bi 3+ A saturated organic precursor solution is prepared so that bismuth salt can be added to the solution according to the consumption of bismuth salt precipitation; wherein the bismuth salt is BiCl3, Bi(NO3)3·5H2O, Bi2(SO4)3, Bi(CH3COO)3 or Bi(C6H5O7); the organic solvent is a combination of one or more of ethylene glycol, glycerol, acetone and ether; generally, the amount of bismuth salt added is related to its solubility in the organic solvent, and the types of bismuth salt and organic solvent will affect Bi 3+ In terms of solubility, mobility, deposition kinetics and lattice matching in organic solvents, it will have a significant impact on the morphology, yield and chemical state of the bismuth catalyst; for example, when the bismuth salt is BiCl3, the Cl- radius is small and the coordination ability is strong. 3+ It will form a coordination structure with Cl- in preference to ethylene glycol molecules. This coordination structure is relatively stable and will limit Bi 3+ Movement in the solvent will also reduce Bi 3+ So the solubility of bismuth salt should be selected as the solvent with stronger coordination ability; when the bismuth salt is Bi(NO3)3·5H2O, NO3- has a larger spatial structure and weaker coordination ability. In the glycerol solvent, Bi 3 + The interaction between Bi and glycerol molecules is less disturbed by NO3-, making Bi 3+ The solubility in glycerol is relatively high, and the mobility is also relatively large, which can make Bi 3+ A dense Bi metal layer is formed during the deposition process. Therefore, the amount of bismuth salt added needs to be appropriately adjusted considering the subsequent application requirements.
[0040] Contains Bi 3+ The saturated organic precursor solution is used as an electrolyte to form an electrolysis system with two platinum electrodes. Generally, the area of the platinum electrode used as the cathode is less than or equal to the area of the platinum electrode used as the anode, so that a stable electric field can be formed, which is conducive to the migration and precipitation of Bi ions onto the electrodes.
[0041] The electrolytic system performs constant current electrodeposition under stirring conditions; wherein the cathode is used as the working electrode and the cathode current density is 10 to 500 mA / cm 2 , the deposition time is 30 to 200 min, and the stirring speed is 50 to 200 rpm;
[0042] During the constant current electrodeposition process, Bi in the saturated organic precursor solution 3+ Reduction to form metallic Bi particles, and particle deposition to obtain a flocculent porous bismuth catalyst.
[0043] In some embodiments, preferably, the cathode current density is 20 to 100 mA / cm 2 Generally, long-term electrodeposition will cause Bi to form a dense and stable Bi metal layer on the electrode, which makes it difficult to peel the Bi catalyst from the electrode substrate and to increase the active specific surface area of the Bi catalyst. The preparation method of the bismuth catalyst provided in the embodiment of the present invention avoids the formation of a dense Bi metal layer by regulating the precursor liquid; by regulating the appropriate current density, a flocculent porous Bi catalyst is synthesized stably and continuously; when the current density is relatively large, for example, at 100 to 500 mA / cm 2 Within the range of 3+ The reduction rate of ions on the electrode surface is accelerated, resulting in a rapid increase in the nucleation rate, which may form smaller Bi particles, and these particles are more likely to agglomerate to form a relatively dense structure. At the same time, a large current density may cause drastic changes in the local solution, such as rapid changes in pH and uneven distribution of ion concentration, which may have an adverse effect on the morphology and structure of the catalyst. When the current density is small, such as 10-20 mA / cm 2 Within the range of 3+ The reduction rate of ions is relatively slow, and the nucleation rate is also low, which is conducive to the formation of larger Bi particles. To control the formation of flocculent porous catalysts, it is necessary to select a suitable current density range of 20 to 100 mA / cm 2 Down, Bi 3+ The reduction rate of ions is moderate, which can ensure sufficient nucleation rate and avoid excessive agglomeration of particles. During the deposition process, under the action of gravity and magnetic stirring, the formed Bi particles will gradually peel off from the electrode and fall to the bottom of the solution.
[0044] In some embodiments, during the constant current electrodeposition process, a bismuth salt is added to the saturated organic precursor solution in small amounts multiple times to maintain the saturated organic precursor solution at Bi 3+ Generally, the bismuth salt is directly dissolved into the saturated organic precursor solution by spraying under stirring conditions, so that the saturated organic precursor solution maintains Bi 3+ The ion saturation state continuously provides Bi for the reaction 3+ , to achieve batch preparation of bismuth catalysts; generally, in the continuous reaction process, it is necessary to add bismuth salt to the saturated organic precursor solution so that the organic precursor solution remains in a saturated state, so that the ions in the saturated organic precursor solution after the addition of the new bismuth salt maintain stable solubility, mobility, and constant pH value; at the same time, the single addition amount of bismuth salt needs to be controlled within a certain range so that the added bismuth salt can be dissolved in time to prevent the bismuth salt from being deposited on the flocculent porous bismuth catalyst and causing contamination to the bismuth catalyst.
[0045] In some embodiments, during the constant current electrodeposition process, the bismuth salt is added to the saturated organic precursor solution by spraying to avoid contamination of the newly formed bismuth catalyst by the bismuth salt.
[0046] In some embodiments, the method for preparing a bismuth catalyst for electrocatalytic conversion of carbon dioxide further includes post-treating the prepared flocculent porous bismuth catalyst to obtain a bismuth catalyst with a particle size of less than 100 μm.
[0047] In some embodiments, post-processing specifically includes:
[0048] The flocculent porous bismuth catalyst is taken out from the saturated organic precursor solution; generally, the flocculent porous bismuth catalyst can be separated from the saturated organic precursor solution by centrifugal separation;
[0049] The flocculent porous bismuth catalyst is washed multiple times with anhydrous alcohol to completely remove the residual saturated organic precursor solution and other possible impurities;
[0050] The washed flocculent porous bismuth catalyst is dried at a drying temperature of less than 80° C. The flocculent porous bismuth catalyst is in a gray powder state after drying;
[0051] The dried bismuth catalyst is sieved to obtain a bismuth catalyst with a particle size of less than 100 μm.
[0052] Generally, a bismuth catalyst is prepared into a catalytic electrode for electrocatalytic reduction of carbon dioxide; wherein, the preparation method of the catalytic electrode and the electrochemical performance test method are as follows:
[0053] Take 100 mg of bismuth catalyst, 100-300 mg of carbon black, and 50-200 mg of PTFE powder, dissolve them in 20 mL of isopropanol, and ultrasonicate for 1 h to form a dispersion;
[0054] Add 1 mL of 5% Nafion to the dispersion and mix by ultrasonic for 1 h to form a uniform bismuth catalyst ink;
[0055] The bismuth catalyst ink was sprayed evenly on a 10×10 cm 2 The hydrophobic carbon cloth was naturally air-dried to obtain a bismuth catalytic electrode; the hydrophobic carbon cloth may capture gaseous reactants near the bismuth catalyst layer, thereby improving the activity and selectivity of CO2RR reduction;
[0056] The 10×10cm 2 Cut a 1×1.5cm piece from the bismuth catalytic electrode 2 The electrode was used as the working electrode and 1×1 cm 2 The area is immersed in the electrolyte solution, the platinum sheet is used as the counter electrode, the silver / silver chloride electrode is used as the reference electrode, and electrocatalytic carbon dioxide reduction is carried out in an H-type electrolytic cell. The test potential window is -0.7 to -1.4 VvsRHE; generally, the electrolyte solution can be 0.5 M, 1 M and 2 M KHCO3 solution.
[0057] In some embodiments, the bismuth catalyst for electrocatalytic conversion of carbon dioxide is obtained by the above-mentioned method for preparing the bismuth catalyst for electrocatalytic conversion of carbon dioxide.
[0058] In some embodiments, the Faradaic efficiency of the bismuth catalyst in selectively forming formic acid or formate during the electrocatalytic conversion of carbon dioxide is above 90%; at a potential of -1.1 V vs. RHE, the Faradaic efficiency of the bismuth catalyst in selectively forming formic acid during the electrocatalytic conversion of carbon dioxide is as high as 97%.
[0059] The technical details are further illustrated below in conjunction with embodiments.
[0060] Example 1
[0061] Figure 1 This is a physical picture of the bismuth catalyst for electrocatalytic conversion of carbon dioxide disclosed in Example 1; Figure 2 is a SEM image of the bismuth catalyst for electrocatalytic conversion of carbon dioxide disclosed in Example 1; Figure 3 is a SEM elemental scan of the bismuth catalyst for electrocatalytic conversion of carbon dioxide disclosed in Example 1; Figure 4 This is an EDS image of the bismuth catalyst for electrocatalytic conversion of carbon dioxide disclosed in Example 1; Figure 5 is the XRD pattern of the bismuth catalyst for electrocatalytic conversion of carbon dioxide disclosed in Example 1; Figure 6 This is a comparison diagram of the LSV curves of the CO2 reduction test performed on the bismuth catalytic electrode disclosed in Example 1; Figure 7 A Faraday efficiency diagram of H2, CO and HCOOH in the electrolyte at different potentials when the bismuth catalytic electrode disclosed in Example 1 is subjected to a CO2 reduction test; Figure 8 The graph shows the current density of H2, CO and HCOOH in the electrolyte at different potentials when the bismuth catalytic electrode disclosed in Example 1 is subjected to a CO2 reduction test.
[0062] Example 1 discloses a method for preparing a bismuth catalyst for electrocatalytic conversion of carbon dioxide, comprising:
[0063] Pour 2 mol Bi(NO3)3·5H2O into 500 mL of ethylene glycol and stir to form a solution containing Bi. 3+ A saturated organic precursor solution;
[0064] Will contain Bi 3+ The saturated organic precursor solution is used as the electrolyte to form an electrolysis system with two platinum electrodes;
[0065] The electrolytic system was set to perform constant current electrodeposition under the stirring conditions of a magnetic stirrer; wherein the stirring speed was 100 rpm and the cathode current density was 20 mA / cm 2 , the deposition time is 30min;
[0066] During the constant current electrodeposition process, Bi in the saturated organic precursor solution 3+ Reduction, forming metal Bi particles; at the same time, adding 0.5 mol Bi(NO3)3·5H2O in small amounts to the saturated organic precursor solution several times to allow the reaction to continue, and obtaining Figures 1-2 The flocculent porous bismuth catalyst shown. Figure 3 , Figure 4 , element scanning was performed on the catalyst, and the Bi element on the catalyst was evenly distributed. Figure 5 The XRD pattern also proves that the synthesized catalyst is entirely Bi without other impurities.
[0067] Take 100 mg of bismuth catalyst, 100 mg of carbon black, and 150 mg of PTFE powder, dissolve them in 20 mL of isopropanol, and sonicate for 1 h to form a dispersion;
[0068] Add 1 mL of 5% Nafion to the dispersion and mix by ultrasonic for 1 h to form a uniform bismuth catalyst ink;
[0069] The bismuth catalyst ink was sprayed evenly on a 10×10 cm 2The hydrophobic carbon cloth was naturally air-dried to obtain a bismuth catalytic electrode; the hydrophobic carbon cloth may capture gaseous reactants near the bismuth catalyst layer, thereby improving the activity and selectivity of CO2RR reduction;
[0070] The 10×10cm 2 Cut a 1×1.5cm piece from the bismuth catalytic electrode 2 The electrode was used as the working electrode and 1×1 cm 2 The area was immersed in 1M KHCO3 solution, with platinum as the counter electrode and silver / silver chloride electrode as the reference electrode, and electrocatalytic carbon dioxide reduction was carried out in an H-type electrolytic cell. The test potential window was -0.7 to -1.4 V vs RHE. The test results are shown in Figures 6 to 8 As shown, the bismuth catalytic electrode as the working electrode can reach 170 mA / cm at a negative voltage of -1.4 V vs RHE. 2 The current density of formic acid is 166.2 mA / cm 2 .
[0071] The bismuth catalyst for the electrocatalytic conversion of carbon dioxide disclosed in the embodiment of the present invention has good hydrophobic properties, which is beneficial to increase the carbon dioxide concentration on the surface of the electrocatalyst in the electrocatalytic carbon dioxide reduction reaction; it has a loose and porous structure, can provide abundant active sites, can effectively promote electron transfer and CO2 mass transfer, so that in the process of electrocatalytic carbon dioxide reduction, CO2 molecules can be efficiently adsorbed and activated to generate OCOH intermediates, thereby realizing efficient catalytic carbon dioxide reduction to formic acid or formates. The preparation method of the bismuth catalyst for the electrocatalytic conversion of carbon dioxide disclosed in the embodiment of the present invention can realize the large-scale preparation of bismuth catalysts in a short time and improve production efficiency; in addition, since the bismuth catalyst has high selectivity for the reduction of formic acid or formates, it has significant commercial feasibility and commercial value in terms of market demand, material cost, manufacturing and separation costs, etc.
[0072] The technical solutions disclosed in the present invention and the technical details disclosed in the embodiments are merely illustrative of the inventive concept of the present invention and do not constitute a limitation on the technical solutions of the present invention. Any conventional changes, substitutions or combinations of the technical details disclosed in the embodiments of the present invention have the same inventive concept as the present invention and are within the protection scope of the claims of the present invention.
Claims
1. A method for preparing a bismuth catalyst for electrocatalytic conversion of carbon dioxide, characterized in that: include: The bismuth salt and the organic solvent are prepared to contain Bi 3+ A saturated organic precursor solution; wherein the bismuth salt is BiCl3, Bi(NO3)3·5H2O, Bi2(SO4)3, Bi(CH3COO)3 or Bi(C6H5O7); the organic solvent is a combination of one or more of ethylene glycol, glycerol, acetone and ether; Contains Bi 3+ The saturated organic precursor solution is used as electrolyte to form an electrolysis system with two platinum electrodes; The electrolytic system performs constant current electrodeposition under stirring conditions; wherein the cathode is used as the working electrode and the cathode current density is 10 to 500 mA / cm 2 , the deposition time is 30 to 200 minutes; During the constant current electrodeposition process, Bi in the saturated organic precursor solution 3+ Reduction to form metallic Bi particles, and particle deposition to obtain a flocculent porous bismuth catalyst.
2. The method for preparing a bismuth catalyst for electrocatalytic conversion of carbon dioxide according to claim 1, characterized in that: The area of the platinum sheet electrode used as the cathode is smaller than or equal to the area of the platinum sheet electrode used as the anode.
3. The method for preparing a bismuth catalyst for electrocatalytic conversion of carbon dioxide according to claim 1, characterized in that: The stirring speed is 50-200 rpm.
4. The method for preparing a bismuth catalyst for electrocatalytic conversion of carbon dioxide according to claim 1, characterized in that: The cathode current density is 20-100 mA / cm 2 .
5. The method for preparing a bismuth catalyst for electrocatalytic conversion of carbon dioxide according to claim 1, characterized in that: During the constant current electrodeposition process, bismuth salt is added to the saturated organic precursor solution in small amounts multiple times to allow the reaction to proceed continuously.
6. The method for preparing a bismuth catalyst for electrocatalytic conversion of carbon dioxide according to claim 5, characterized in that: The bismuth salt is added into the saturated organic precursor solution by spraying.
7. The method for preparing a bismuth catalyst for electrocatalytic conversion of carbon dioxide according to claim 1, characterized in that: The method also includes post-processing the prepared flocculent porous bismuth catalyst to obtain a bismuth catalyst with a particle size less than 100 μm.
8. The method for preparing a bismuth catalyst for electrocatalytic conversion of carbon dioxide according to claim 7, characterized in that: The post-processing specifically includes: The flocculent porous bismuth catalyst is taken out from the saturated organic precursor solution; The flocculent and porous bismuth catalyst was washed several times with anhydrous alcohol; The washed flocculent porous bismuth catalyst is dried at a temperature of less than 80° C. The dried bismuth catalyst is sieved to obtain a bismuth catalyst with a particle size of less than 100 μm.
9. A bismuth catalyst for electrocatalytic conversion of carbon dioxide, characterized in that: The bismuth catalyst is obtained by the preparation method of the bismuth catalyst for electrocatalytic conversion of carbon dioxide according to any one of claims 1 to 8.
10. The bismuth catalyst for electrocatalytic conversion of carbon dioxide according to claim 9, characterized in that: The bismuth catalyst has a Faraday efficiency of more than 90% for selectively forming formic acid or formate during the electrocatalytic conversion of carbon dioxide.
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