Method for preparing copper-based catalyst by electrodeposition on conductive gas diffusion layer and its application

Abstract

The present invention discloses a method for preparing a copper-based catalyst by electrodeposition on a conductive gas diffusion layer and its application, belonging to the field of electrodeposition technology. The method comprises the following steps: preparing a copper electroplating solution and a catalyst electroplating solution, wherein the catalyst electroplating solution is a bismuth electroplating solution and / or a tin electroplating solution; using the gas diffusion layer as a carrier, using the copper electroplating solution to prepare a copper bonding layer on the carrier by electrodeposition; and using the catalyst electroplating solution to prepare a catalyst layer on the copper bonding layer by electrodeposition, thereby obtaining a copper-based catalyst. The process of preparing the copper-based catalyst by electrodeposition is simple to operate and has highly controllable conditions. Bismuth and tin catalysts can be directly prepared on the gas diffusion layer. The obtained copper-based catalyst is evenly dispersed and more firmly bonded to the substrate. The process for preparing the copper-based catalyst by electrodeposition is simple, and has the potential for industrial large-scale production.

Description

Technical Field

[0001] The present invention belongs to the technical field of electrodeposition, and in particular relates to a method for preparing a copper-based catalyst by electrodeposition on a conductive gas diffusion layer and its application. Background Art

[0002] The electrocatalytic reduction of carbon dioxide (CO2) by electrocatalytic CO2 reduction (ERR) driven by renewable energy can convert CO2 into high-value chemical feedstocks or fuels. Among the various chemicals produced by ERR, formates hold a significant position in industrial production. Tin, indium, bismuth, and lead are p-block late transition metals with a wide range of oxidation states and high versatility in forming p-block compounds of varying valences. They exhibit exceptional performance in formate production. Among these metals, bismuth and tin have attracted considerable attention due to their low toxicity and high selectivity for formate production. Furthermore, tin's market price is comparable to that of copper, making it suitable for industrial-scale application.

[0003] To achieve efficient carbon dioxide electroreduction to formic acid, various research teams have developed different types of catalysts and continuously optimized their structures. Ko et al. published their research results in Nat. Commun., titled "Exploring dopant effects in stannic oxide nanoparticles for CO2 electro-reduction to formate." They synthesized a fluorine-doped tin oxide (FTO) nanocatalyst that exhibited a high electrochemical performance at 330 mA cm -2 The Faradaic efficiency of formate at some current densities reached 90% and remained basically stable during a 7-day stability test. Luo et al. reported a three-dimensional porous indium catalyst for the electroreduction of CO2 to formate in their research work published in J. Mater. Chem. A. titled "3D hierarchical porous indium catalyst for highly efficient electroreduction of CO2". The highly porous hierarchical structure promoted the formation of formate, with a capacity of 1.14 mmol cm-2 within 24 hours. -2 h -1 The formic acid production rate.

[0004] Adjusting the morphology of the catalyst is a simple and effective method to achieve good performance in carbon dioxide reduction, which can provide more exposed active surfaces and active sites. Currently, people have developed bismuth and tin-based electrocatalysts with various morphological characteristics through methods such as hydrothermal method, chemical reduction method or electroreduction method and electrodeposition method. However, since metallic bismuth and tin are easy to fall off on the gas diffusion layer, there are few reports on the preparation of bismuth and tin-based electrocatalysts by electrodeposition method on the gas diffusion layer. Most bismuth and tin-based electrocatalysts are prepared by first synthesizing catalyst ink using solvent thermal method or other methods, and then dropping it on the gas diffusion layer. These methods have the problems of cumbersome operation steps and uneven catalyst distribution, which affects their catalytic performance. Summary of the Invention

[0005] The purpose of the present invention is to provide a method and application for preparing a copper-based catalyst by electrodeposition on a conductive gas diffusion layer, so as to solve the problems of existing bismuth and tin-based electrocatalysts such as complicated preparation steps, uneven distribution, and easy falling off on the gas diffusion layer.

[0006] In order to achieve the above object, the technical solution of the present invention is as follows:

[0007] The present invention relates to a method for preparing a copper-based catalyst by electrodeposition on a conductive gas diffusion layer. The method comprises the following steps: preparing a copper electroplating solution and a catalyst electroplating solution, wherein the catalyst electroplating solution is a bismuth electroplating solution and / or a tin electroplating solution; using the gas diffusion layer as a carrier, preparing a copper bonding layer on the carrier by electrodeposition using the copper electroplating solution; and preparing a catalyst layer on the copper bonding layer by electrodeposition using the catalyst electroplating solution, thereby obtaining a copper-based catalyst.

[0008] Preferably, it comprises the following steps:

[0009] S1. Prepare a copper plating solution and a catalyst plating solution, wherein the catalyst plating solution is a bismuth plating solution or a tin plating solution;

[0010] S2. Using the gas diffusion layer as the cathode and the copper wire as the anode, copper electrodeposition is performed in a copper electroplating solution to obtain a copper bonding layer on the surface of the gas diffusion layer;

[0011] S3. Using a gas diffusion layer having a copper bonding layer on its surface as a cathode and a platinum mesh electrode as an anode, electroplating is performed in a catalyst electroplating solution to obtain a catalyst layer, thereby obtaining a copper-based catalyst.

[0012] Preferably, it comprises the following steps:

[0013] S1. Prepare copper plating solution, bismuth plating solution and tin plating solution;

[0014] S2. Using the gas diffusion layer as the cathode and the copper wire as the anode, copper electrodeposition is performed in a copper electroplating solution to obtain a copper bonding layer on the surface of the gas diffusion layer;

[0015] S3. Using a gas diffusion layer containing a copper bonding layer as the cathode and a platinum mesh electrode as the anode, bismuth is electrodeposited in a bismuth electroplating solution to obtain a copper-bismuth catalyst; then, tin is electrodeposited in a tin electroplating solution to obtain a copper-bismuth-tin catalyst.

[0016] Preferably, the copper electroplating solution in S1 is prepared by dissolving CuSO4 and H2SO4 in water, respectively, controlling the concentration of CuSO4 to be 0.05M to 0.2M and the concentration of H2SO4 to be 0.1M to 0.55M, and stirring until the solution becomes clear and transparent to obtain a copper electroplating solution;

[0017] The catalyst electroplating solution in S1 is a bismuth electroplating solution and / or a tin electroplating solution:

[0018] The bismuth electroplating solution is prepared by dissolving Bi(NO3)3 and HNO3 in water, controlling the concentration of Bi(NO3)3 to be 0.05M to 0.2M and the concentration of HNO3 to be 0.1M to 0.45M, and ultrasonicating for 10 minutes until the solution becomes clear and transparent to obtain the bismuth electroplating solution.

[0019] The tin electroplating solution is prepared by dissolving SnCl2, HCl, and a surfactant, Triton X-100, in water, respectively, controlling the concentration of SnCl2 to be 0.05M to 0.25M, the concentration of HCl to be 0.1M to 0.7M, and the concentration of Triton X-100 to be 0.05M to 0.15M, and stirring until the solution is homogeneous and stable to obtain the tin electroplating solution.

[0020] The copper electroplating solution and the catalyst electroplating solution are both prepared at room temperature.

[0021] The Triton X-100 is a surfactant, which refers to polyethylene glycol octylphenyl ether.

[0022] Preferably, the gas diffusion layer used in S2 is a carbon fiber gas diffusion layer with a hydrophobic carbon black microporous layer. Before use, the gas diffusion layer is also pretreated. The specific steps are: rinse the carbon black and carbon fiber surfaces of the gas diffusion layer with pure water, cover the carbon fiber side with tape, leaving only the carbon black microporous layer side exposed, and naturally dry the treated gas diffusion layer.

[0023] Preferably, the copper electrodeposition in S2 is carried out at room temperature, and the electrodeposition temperature is 5.5 to 7.5 C cm at a deposition potential of -0.25 V to -0.35 V (vs. Ag / AgCl). -2 The copper with the charged amount is then bonded to the surface of the gas diffusion layer to form a copper bonding layer;

[0024] Preferably, the catalyst layer electrodeposition in S3 is performed at room temperature;

[0025] When the catalyst plating solution is a bismuth plating solution, the bismuth charge of 4 to 16 C is deposited at a deposition potential of -0.05 V to -0.2 V (vs. Ag / AgCl), corresponding to 0.8 to 3.2 mg cm -2 Bismuth loading;

[0026] When the catalyst plating solution is a tin plating solution, the charge of tin deposited at a deposition potential of -0.1V to -0.2V (vs. Ag / AgCl) is 8 to 12C, corresponding to 1.4 to 2.1 mg cm -2 of tin loading.

[0027] Preferably, after the S2 copper is electroplated to obtain a copper bonding layer, the gas diffusion layer containing the copper bonding layer on its surface is removed from the copper electroplating solution, washed with pure water, and then dried in an air environment at room temperature; after the S3 catalyst layer is electroplated, the copper-based catalyst is removed from the electroplating solution, washed with pure water, and then dried in an air environment at room temperature.

[0028] Preferably, after the copper, bismuth, and tin catalyst is obtained in S3, 5 to 55 wt% of a polytetrafluoroethylene aqueous dispersion is added dropwise to the surface of the bismuth-tin catalyst layer, and then dried at 300° C. for 2 hours to obtain a hydrophobically modified copper-based catalyst; the mass fraction of the polytetrafluoroethylene aqueous dispersion represents the mass fraction of polytetrafluoroethylene in the total mass of copper, bismuth, and tin deposited on the gas diffusion layer.

[0029] The prepared copper-based catalyst is used as a catalyst for reducing carbon dioxide to produce formic acid.

[0030] Compared with the prior art, the technical solution provided by the present invention has the following beneficial effects:

[0031] 1. The present invention relates to a method for preparing a copper-based catalyst by electrodeposition on a conductive gas diffusion layer. The method uses a gas diffusion layer as a carrier, and uses a copper electroplating solution to prepare a copper bonding layer on the carrier by electrodeposition. Then, the method uses a catalyst electroplating solution to prepare a catalyst layer on the copper bonding layer by electrodeposition. The catalyst preparation process is simple to operate and has highly controllable conditions. A uniformly dispersed bismuth and / or tin catalyst can be prepared directly on the gas diffusion layer. The copper deposited first serves as an adhesive layer and a conductive layer, which can increase the deposition coverage of bismuth and tin on the substrate, solving the problem of bismuth and tin easily falling off when directly deposited on the gas diffusion layer. In addition, the process for preparing the copper, bismuth, and tin catalyst by electrodeposition is simple, and has the potential for industrial large-scale production.

[0032] 2. The present invention dissolves CuSO4 and H2SO4 in water, controls the concentration of CuSO4 to be 0.05M-0.2M, the concentration of H2SO4 to be 0.1M-0.55M, and stirs until the solution is clear and transparent to obtain a copper electroplating solution; dissolves Bi(NO3)3 and HNO3 in water, controls the concentration of Bi(NO3)3 to be 0.05M-0.2M, the concentration of HNO3 to be 0.1M-0.45M, and ultrasonicates for 10 minutes until the solution is clear and transparent to obtain a bismuth electroplating solution; dissolves SnCl2, HCl and Triton X-100 in water, controls the concentration of SnCl2 to be 0.05M-0.25M, the concentration of HCl to be 0.1M-0.7M, and the concentration of Triton X-100 to be 0.05M-0.15M, and stirs until the solution is uniform and stable to obtain a tin electroplating solution, and a Triton The addition of X-100 can keep the tin plating solution stable for a long time, increase the current density during the tin deposition process, and improve the electrodeposition synthesis rate, providing a guarantee for the copper bismuth tin catalyst prepared by electrodeposition to be suitable for different catalytic reaction requirements.

[0033] 3. The copper-based catalyst disclosed herein exhibits high formic acid production activity, selectivity, and stability. The copper-first deposition process utilizes copper as a binder, increasing the coverage of bismuth and / or tin on the substrate and the number of active sites involved in the reaction. Plating bath additives and a suitable deposition potential increase the catalyst's deposition rate and electrochemically active area, promoting its directional catalytic effect on the electroreduction of carbon dioxide to formic acid. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 Flowchart of the copper bismuth tin catalyst prepared in Example 1-2;

[0035] Figure 2 Flowchart of the copper-bismuth catalyst prepared in Example 3;

[0036] Figure 3 Flowchart of the copper-tin catalyst prepared in Example 4;

[0037] Figure 4 This is a SEM test image of the copper bismuth tin catalyst prepared in Example 1-2;

[0038] Figure 5 This is a SEM test image of the copper-bismuth catalyst prepared in Example 3;

[0039] Figure 6 This is a SEM test image of the copper-tin catalyst prepared in Example 4;

[0040] Figure 7 This is the XRD test pattern of the copper bismuth tin catalyst prepared in Example 1-2;

[0041] Figure 8 This is the XRD test pattern of the copper-bismuth catalyst prepared in Example 3;

[0042] Figure 9 This is the XRD test pattern of the copper-tin catalyst prepared in Example 4;

[0043] Figure 10 CV test graphs of the carbon dioxide electrocatalytic reduction performance test of the copper-containing bonding layer prepared in Examples 1 to 4;

[0044] Figure 11 This is a SEM test image of the bismuth catalyst prepared in Comparative Example 1;

[0045] Figure 12 This is a SEM test image of the hydrophobically modified copper bismuth tin catalyst prepared in Example 5;

[0046] Figure 13 Graphs of formic acid Faraday efficiency and partial current density for the carbon dioxide electrocatalytic reduction performance test of the hydrophobically modified copper bismuth tin catalyst prepared in Example 5. DETAILED DESCRIPTION

[0047] In order to further understand the content of the present invention, the present invention is described in detail with reference to the examples. The following examples are used to illustrate the present invention but are not used to limit the scope of the present invention.

[0048] Example 1 Preparation of Copper Bismuth Tin Catalyst

[0049] Refer to the attached Figure 1 As shown, the present invention relates to a method for preparing a copper-based catalyst by electrodeposition on a conductive gas diffusion layer. The copper-based catalyst in this embodiment is a copper-bismuth-tin catalyst. The preparation method includes the following steps: preparing a copper electroplating solution, a bismuth electroplating solution, and a tin electroplating solution; using the gas diffusion layer as a carrier, and preparing the copper-bismuth-tin catalyst on the carrier by electrodeposition using the copper electroplating solution, the bismuth electroplating solution, and the tin electroplating solution. The specific steps are:

[0050] S1. Prepare copper plating solution, bismuth plating solution and tin plating solution

[0051] The copper electroplating solution was prepared by dissolving CuSO4 and H2SO4 in 80 ml of water, respectively, controlling the concentration of CuSO4 to 0.1 M and the concentration of H2SO4 to 0.45 M, and stirring until the solution became clear and transparent to obtain the copper electroplating solution.

[0052] The bismuth electroplating solution was prepared by dissolving Bi(NO3)3 and HNO3 in 80 ml of water, respectively, controlling the concentration of Bi(NO3)3 to 0.05 M and the concentration of HNO3 to 0.35 M, and ultrasonicating for 10 minutes until the solution became clear and transparent, thereby obtaining the bismuth electroplating solution.

[0053] The tin electroplating solution is prepared by dissolving SnCl2, HCl and Triton X-100 in water respectively, controlling the concentration of SnCl2 to be 0.05M, the concentration of HCl to be 0.5M, and the concentration of Triton X-100 to be 0.05M, and stirring until the solution is homogeneous and stable to obtain the tin electroplating solution;

[0054] The copper electroplating solution, bismuth electroplating solution and tin electroplating solution are all prepared at room temperature.

[0055] S2. Using the gas diffusion layer as the cathode and the copper wire as the anode, copper electrodeposition is performed in a copper electroplating solution to obtain a copper bonding layer on the surface of the gas diffusion layer. The gas diffusion layer is a carbon fiber gas diffusion layer with a hydrophobic carbon black microporous layer. Before use, the gas diffusion layer is pretreated by rinsing the carbon black and carbon fiber surfaces of the gas diffusion layer with pure water, covering the carbon fiber side with 3M tape, leaving only the carbon black microporous layer side exposed, and allowing the treated gas diffusion layer to dry naturally. The copper electrodeposition is performed at room temperature, and 5.5 C cm is deposited at a deposition potential of -0.25 V (vs. Ag / AgCl). -2 The copper with the charged amount is formed, and a copper bonding layer is obtained on the surface of the gas diffusion layer. The gas diffusion layer with the copper bonding layer on the surface is then taken out from the copper electroplating solution, washed with pure water and dried in an air environment at room temperature.

[0056] S3. A gas diffusion layer containing a copper bonding layer on its surface is used as a cathode and a platinum mesh electrode is used as an anode. Bismuth is first electrodeposited in a bismuth electroplating solution; then tin is electrodeposited in a tin electroplating solution to form a bismuth-tin catalyst layer, thereby obtaining a copper-bismuth-tin catalyst.

[0057] Bismuth electrodeposition was carried out at room temperature. Bismuth with a charge of 4C was deposited at a deposition potential of -0.05 V (vs. Ag / AgCl), corresponding to 0.8 mg cm -2 The bismuth loading was 1.41 mg cm-1 under the condition of 8 C charge of tin at a deposition potential of -0.1 V (vs. Ag / AgCl). -2 The tin loading amount is 200 nm, and a copper-bismuth-tin catalyst is obtained by bismuth electrodeposition and tin electrodeposition. The gas diffusion layer containing the copper-bismuth-tin catalyst on the surface is then taken out from the plating solution, washed with pure water, and dried in an air environment at room temperature.

[0058] Reference Figure 4 As shown, the copper, bismuth and tin catalyst prepared in this embodiment has a flaky structure as a whole, and the flaky bismuth and tin are evenly dispersed on the copper particles. The copper particles have a particle size of about 5 μm and a large specific surface area. Figure 7 The catalyst prepared in this example is composed of copper, bismuth and tin.

[0059] Example 2 Preparation of Copper Bismuth Tin Catalyst

[0060] Refer to the attached Figure 1 As shown, the present invention relates to a method for preparing a copper-based catalyst by electrodeposition on a conductive gas diffusion layer. The copper-based catalyst in this embodiment is a copper-bismuth-tin catalyst. The preparation method includes the following steps: preparing a copper electroplating solution, a bismuth electroplating solution, and a tin electroplating solution; using the gas diffusion layer as a carrier, and preparing the copper-bismuth-tin catalyst on the carrier by electrodeposition using the copper electroplating solution, the bismuth electroplating solution, and the tin electroplating solution. The specific steps are:

[0061] S1. Prepare copper plating solution, bismuth plating solution and tin plating solution

[0062] The copper electroplating solution was prepared by dissolving CuSO4 and H2SO4 in 80 ml of water, respectively, controlling the concentration of CuSO4 to 0.15 M and the concentration of H2SO4 to 0.5 M, and stirring until the solution became clear and transparent to obtain the copper electroplating solution.

[0063] The bismuth electroplating solution was prepared by dissolving Bi(NO3)3 and HNO3 in 80 ml of water, respectively, controlling the concentration of Bi(NO3)3 to 0.1 M and the concentration of HNO3 to 0.4 M, and ultrasonicating for 10 minutes until the solution became clear and transparent, thereby obtaining the bismuth electroplating solution.

[0064] The tin electroplating solution is prepared by dissolving SnCl2, HCl and Triton X-100 in water respectively, controlling the concentration of SnCl2 to be 0.1M, the concentration of HCl to be 0.6M, and the concentration of Triton X-100 to be 0.1M, and stirring until the solution is homogeneous and stable to obtain the tin electroplating solution;

[0065] The copper electroplating solution, bismuth electroplating solution and tin electroplating solution are all prepared at room temperature.

[0066] S2. Using the gas diffusion layer as the cathode and the copper wire as the anode, copper electrodeposition is performed in a copper electroplating solution to obtain a copper bonding layer on the surface of the gas diffusion layer. The gas diffusion layer is a carbon fiber gas diffusion layer with a hydrophobic carbon black microporous layer. Before use, the gas diffusion layer is pretreated by rinsing the carbon black and carbon fiber surfaces of the gas diffusion layer with pure water, covering the carbon fiber side with 3M tape, leaving only the carbon black microporous layer side exposed, and allowing the treated gas diffusion layer to dry naturally. The copper electrodeposition is performed at room temperature, and 6.0 C cm is deposited at a deposition potential of -0.30 V (vs. Ag / AgCl). -2 The copper with the charged amount is formed, and a copper bonding layer is obtained on the surface of the gas diffusion layer. The gas diffusion layer with the copper bonding layer on the surface is then taken out from the copper electroplating solution, washed with pure water and dried in an air environment at room temperature.

[0067] S3. A gas diffusion layer having a copper bonding layer on its surface is used as a cathode and a platinum mesh electrode is used as an anode. Bismuth is first electrodeposited in a bismuth electroplating solution and then tin is electrodeposited in a tin electroplating solution to form a bismuth-tin catalyst layer, thereby obtaining a copper-bismuth-tin catalyst.

[0068] Bismuth electrodeposition was carried out at room temperature. At a deposition potential of -0.10 V (vs. Ag / AgCl), a charge of 10 C of bismuth was deposited, corresponding to 2.1 mg cm -2 The bismuth loading was 1.6 mg cm-1 under the conditions of room temperature and 10 C charge of tin was deposited at a deposition potential of -0.15 V (vs. Ag / AgCl). -2 The tin loading amount is 200 nm, and a copper-bismuth-tin catalyst is obtained by bismuth electrodeposition and tin electrodeposition. The gas diffusion layer containing the copper-bismuth-tin catalyst on the surface is then taken out from the plating solution, washed with pure water, and dried in an air environment at room temperature.

[0069] Reference Figure 4 As shown, the copper, bismuth and tin catalyst prepared in this embodiment has a flaky structure as a whole, and the flaky bismuth and tin are evenly dispersed on the copper particles. The copper particles have a particle size of about 5 μm and a large specific surface area. Figure 7 The catalyst prepared in this example is composed of copper, bismuth and tin.

[0070] Example 3 Preparation of Copper-Bismuth Catalyst

[0071] Refer to the attached Figure 2 As shown, the present invention relates to a method for preparing a copper-based catalyst by electrodeposition on a conductive gas diffusion layer. The copper-based catalyst in this embodiment is a copper-bismuth catalyst. The preparation method includes the following steps: preparing a copper electroplating solution and a bismuth electroplating solution; using the gas diffusion layer as a carrier, preparing the copper-bismuth catalyst on the carrier by electrodeposition using the copper electroplating solution and the bismuth electroplating solution. The specific steps are:

[0072] S1. Preparation of copper and bismuth electroplating solutions

[0073] The copper electroplating solution was prepared by dissolving CuSO4 and H2SO4 in 80 ml of water, respectively, controlling the concentration of CuSO4 to 0.15 M and the concentration of H2SO4 to 0.4 M, and stirring until the solution became clear and transparent to obtain the copper electroplating solution.

[0074] The bismuth electroplating solution was prepared by dissolving Bi(NO3)3 and HNO3 in 80 ml of water, respectively, controlling the concentration of Bi(NO3)3 to 0.15 M and the concentration of HNO3 to 0.4 M, and ultrasonicating for 10 minutes until the solution became clear and transparent, thereby obtaining the bismuth electroplating solution.

[0075] The copper electroplating solution and the bismuth electroplating solution are both prepared at room temperature.

[0076] S2. Using the gas diffusion layer as the cathode and the copper wire as the anode, copper electrodeposition is performed in a copper electroplating solution to form a copper bonding layer on the surface of the gas diffusion layer. The gas diffusion layer is a carbon fiber gas diffusion layer with a hydrophobic carbon black microporous layer. Before use, the gas diffusion layer is pretreated by rinsing the carbon black and carbon fiber surfaces of the gas diffusion layer with pure water, covering the carbon fiber side with 3M tape, leaving only the carbon black microporous layer side exposed, and allowing the treated gas diffusion layer to dry naturally. The copper electrodeposition is performed at room temperature, and 7 C cm is deposited at a deposition potential of -0.3 V (vs. Ag / AgCl). -2 The copper with the charged amount is formed, and a copper bonding layer is obtained on the surface of the gas diffusion layer. The gas diffusion layer with the copper bonding layer on the surface is then taken out from the copper electroplating solution, washed with pure water and dried in an air environment at room temperature.

[0077] S3. The surface of the gas diffusion layer containing a copper bonding layer is used as the cathode, the platinum mesh electrode is used as the anode, and bismuth is electrodeposited in a bismuth electroplating solution to form a bismuth catalyst layer to obtain a copper-bismuth catalyst;

[0078] Bismuth electrodeposition was carried out at room temperature. Bismuth with a charge of 12C was deposited at a deposition potential of -0.15 V (vs. Ag / AgCl), corresponding to 3.0 mg cm -2 The bismuth loading amount is 200 nm, and a copper-bismuth catalyst is obtained by bismuth electrodeposition. The gas diffusion layer containing the copper-bismuth catalyst on the surface is then removed from the plating solution, washed with pure water, and dried in an air environment at room temperature.

[0079] Reference Figure 5 As shown in FIG, the copper-bismuth catalyst prepared in this embodiment has a block structure as a whole, and the block bismuth is evenly dispersed on the copper particles. The copper particles have a particle size of about 5 μm and a large specific surface area. Figure 8 As shown, the catalyst prepared in this example is composed of copper and bismuth.

[0080] Example 4 Preparation of copper-tin catalyst

[0081] Refer to the attached Figure 3 As shown, the present invention relates to a method for preparing a copper-based catalyst by electrodeposition on a conductive gas diffusion layer. The copper-based catalyst in this embodiment is a copper-tin catalyst. The preparation method includes the following steps: preparing a copper electroplating solution and a tin electroplating solution; using the gas diffusion layer as a carrier, preparing the copper-tin catalyst on the carrier by electrodeposition using the copper electroplating solution and the tin electroplating solution. The specific steps are:

[0082] S1. Preparation of copper plating solution and tin plating solution

[0083] The copper electroplating solution is prepared by dissolving CuSO4 and H2SO4 in water, respectively, controlling the concentration of CuSO4 to be 0.2M and the concentration of H2SO4 to be 0.55M, and stirring until the solution becomes clear and transparent to obtain the copper electroplating solution.

[0084] The tin electroplating solution is prepared by dissolving SnCl2, HCl and Triton X-100 in water respectively, controlling the concentration of SnCl2 to be 0.25M, the concentration of HCl to be 0.7M, and the concentration of Triton X-100 to be 0.15M, and stirring until the solution is homogeneous and stable to obtain the tin electroplating solution;

[0085] The copper electroplating solution and the tin electroplating solution are prepared at room temperature.

[0086] S2. Using the gas diffusion layer as the cathode and the copper wire as the anode, copper electrodeposition is performed in a copper electroplating solution to form a copper bonding layer on the surface of the gas diffusion layer. The gas diffusion layer is a carbon fiber gas diffusion layer with a hydrophobic carbon black microporous layer. Before use, the gas diffusion layer is pretreated by rinsing the carbon black and carbon fiber surfaces of the gas diffusion layer with pure water, covering the carbon fiber side with 3M tape, leaving only the carbon black microporous layer side exposed, and allowing the treated gas diffusion layer to dry naturally. The copper electrodeposition is performed at room temperature, and 7 C cm is deposited at a deposition potential of -0.3 V (vs. Ag / AgCl). -2 The copper with the charged amount is formed, and a copper bonding layer is obtained on the surface of the gas diffusion layer. The gas diffusion layer with the copper bonding layer on the surface is then taken out from the copper electroplating solution, washed with pure water and dried in an air environment at room temperature.

[0087] S3. A copper-tin catalyst is obtained by electrodepositing tin in a tin plating solution using a gas diffusion layer containing a copper bonding layer as a cathode and a platinum mesh electrode as an anode;

[0088] Tin electrodeposition was carried out at room temperature. At a deposition potential of -0.2 V (vs. Ag / AgCl), 12C of tin was deposited, corresponding to 2.1 mg cm -2 The tin loading amount is set to 500 nm, and a copper-tin catalyst is obtained by tin electrodeposition. The gas diffusion layer containing the copper-tin catalyst on the surface is then taken out from the plating solution, washed with pure water, and dried in an air environment at room temperature.

[0089] Reference Figure 6 As shown, the copper-tin catalyst prepared in this embodiment has a layered structure as a whole, and the layered tin is evenly dispersed on the copper particles. The copper particles have a particle size of about 5 μm and a large specific surface area. Figure 9 The catalyst prepared in this example is composed of copper and tin.

[0090] Test example:

[0091] The copper bismuth tin / copper bismuth / copper tin catalyst prepared in Examples 1, 2, 3, and 4 was used as the working electrode with an area of ​​1 cm 2 , in 1M KOH solution, the linear sweep polarization curve test was carried out at a sweep rate of 60 to 140 mV / s. The test results are as follows Figure 10 The current density-scan rate linear fit of each group was very good. Further calculations were performed to obtain the electrochemically active area of ​​each catalyst. It was found that when the bismuth deposition potential was -0.15 V (vs. Ag / AgCl), corresponding to the curve shown in Example 3, the prepared catalyst had the largest electrochemically active area. Moreover, the electrochemically active areas of several groups of catalysts were uniformly much higher than those of commercial bismuth foil, indicating that the performance of the catalyst prepared by the method of the present invention was significantly improved compared with that of commercial bismuth foil.

[0092] Comparative Example 1:

[0093] Comparative Example In view of the characteristics of improved deposition coverage of the catalyst prepared in the present application, a method for preparing a bismuth catalyst by electrodeposition on a conductive gas diffusion layer without a copper deposition process is provided, comprising the following steps: preparing a bismuth electroplating solution; using the gas diffusion layer as a carrier, and preparing a bismuth catalyst on the carrier by electrodeposition using the bismuth electroplating solution, the specific steps being:

[0094] S1. Preparation of Bismuth Electroplating Solution

[0095] The bismuth electroplating solution was prepared by dissolving Bi(NO3)3 and HNO3 in 80 ml of water, respectively, controlling the concentration of Bi(NO3)3 to 0.2 M and the concentration of HNO3 to 0.45 M, and ultrasonicating for 10 minutes until the solution became clear and transparent, thereby obtaining the bismuth electroplating solution.

[0096] The bismuth electroplating solution is prepared at room temperature.

[0097] S2. Using the gas diffusion layer as the cathode and the platinum mesh electrode as the anode, bismuth is electrodeposited in a bismuth electroplating solution to obtain a bismuth catalyst;

[0098] Bismuth electrodeposition was carried out at room temperature. Bismuth with a charge of 12C was deposited at a deposition potential of -0.15 V (vs. Ag / AgCl), corresponding to 3.0 mg cm -2 The bismuth loading amount is bismuth; a bismuth catalyst is obtained by bismuth electrodeposition, and then the gas diffusion layer containing the bismuth catalyst on the surface is removed from the plating solution, washed with pure water, and dried in an air environment at room temperature.

[0099] Reference Figure 11As shown, the coverage of the bismuth catalyst prepared in this comparative example on the gas diffusion layer is very low, and the morphology is significantly different from that of the catalysts prepared in Examples 1 to 4; the catalysts in this comparative example and Example 4 were subjected to EDS testing, and the comparison of the mass fractions of the bismuth element on the substrate surface is shown in Table 1 below, indicating that the first deposition of copper as a binder in this method significantly improves the surface coverage of the subsequent bismuth deposition.

[0100] Table 1

[0101] Group Bismuth element mass fraction (wt%) Comparative Example 1 20.5 Example 4 81.2

[0102] Comparative Example 2:

[0103] In this comparative example, a tin plating solution without Triton X-100 is used for tin electrodeposition, and a copper-bismuth-tin catalyst is prepared by electrodeposition on a conductive gas diffusion layer, based on the characteristics of the tin plating solution being stable, having a high deposition current density, and having a fast electrodeposition speed. The method comprises the following steps: preparing a copper electroplating solution, a bismuth electroplating solution, and a tin electroplating solution; and using the gas diffusion layer as a carrier, preparing the copper-bismuth-tin catalyst on the carrier by electrodeposition using the copper electroplating solution, the bismuth electroplating solution, and the tin electroplating solution. The specific steps are as follows:

[0104] S1. Prepare copper plating solution, bismuth plating solution and tin plating solution

[0105] The copper electroplating solution was prepared by dissolving CuSO4 and H2SO4 in 80 ml of water, respectively, controlling the concentration of CuSO4 to 0.2 M and the concentration of H2SO4 to 0.55 M, and stirring until the solution became clear and transparent to obtain a copper electroplating solution.

[0106] The bismuth electroplating solution was prepared by dissolving Bi(NO3)3 and HNO3 in 80 ml of water, respectively, controlling the concentration of Bi(NO3)3 to 0.2 M and the concentration of HNO3 to 0.45 M, and ultrasonicating for 10 minutes until the solution became clear and transparent, thereby obtaining the bismuth electroplating solution.

[0107] The tin electroplating solution is prepared by dissolving SnCl2 and HCl in water, respectively, controlling the concentration of SnCl2 to be 0.2M and the concentration of HCl to be 0.7M, and stirring until the solution is uniform and stable to obtain the tin electroplating solution;

[0108] The copper electroplating solution, bismuth electroplating solution and tin electroplating solution are all prepared at room temperature.

[0109] S2. Using the gas diffusion layer as the cathode and the copper wire as the anode, copper electrodeposition is performed in a copper electroplating solution to obtain a copper bonding layer on the surface of the gas diffusion layer. The gas diffusion layer is a carbon fiber gas diffusion layer with a hydrophobic carbon black microporous layer. Before use, the gas diffusion layer is pretreated by rinsing the carbon black and carbon fiber surfaces of the gas diffusion layer with pure water, covering the carbon fiber side with 3M tape, leaving only the carbon black microporous layer side exposed, and allowing the treated gas diffusion layer to dry naturally. The copper electrodeposition is performed at room temperature, and 7.5 C cm is deposited at a deposition potential of -0.35 V (vs. Ag / AgCl). -2 The copper with the charged amount is formed, and a copper bonding layer is obtained on the surface of the gas diffusion layer. The gas diffusion layer with the copper bonding layer on the surface is then taken out from the copper electroplating solution, washed with pure water and dried in an air environment at room temperature.

[0110] S3. A gas diffusion layer having a copper bonding layer on its surface is used as a cathode and a platinum mesh electrode is used as an anode. Bismuth is first electrodeposited in a bismuth electroplating solution to obtain a copper-bismuth catalyst; then tin is electrodeposited in a tin electroplating solution to obtain a copper-bismuth-tin catalyst;

[0111] Bismuth electrodeposition was carried out at room temperature. Bismuth with a charge of 16C was deposited at a deposition potential of -0.2 V (vs. Ag / AgCl), corresponding to 3.2 mg cm -2 The bismuth loading was 2.1 mg cm-1 under the conditions of room temperature and 12 C charge of tin was deposited at a deposition potential of -0.2 V (vs. Ag / AgCl). -2 The tin loading amount is 200 nm, and a copper-bismuth-tin catalyst is obtained by bismuth electrodeposition and tin electrodeposition. The gas diffusion layer containing the copper-bismuth-tin catalyst on the surface is then taken out from the plating solution, washed with pure water, and dried in an air environment at room temperature.

[0112] The stability of the tin plating solution is represented by the number of times it can normally deposit tin, and the electrodeposition rate is represented by the deposition time at the same deposition potential and the same amount of charge transferred. The number of times the plating solution is used and the electrodeposition time of this comparative example are compared with those of Example 1. The results are shown in Table 2 below, indicating that the tin plating solution formula in this method can effectively improve the stability of the plating solution and the electrodeposition synthesis rate of the catalyst.

[0113] Table 2

[0114] Group Number of times the plating solution is used (times) Electrodeposition time (s) Comparative Example 2 3 510 Example 1 12 450

[0115] Example 5 Preparation of hydrophobically modified copper bismuth tin catalyst

[0116] This embodiment relates to a method for preparing a copper-based catalyst by electrodeposition on a conductive gas diffusion layer. The copper-based catalyst in this embodiment is a hydrophobically modified copper-bismuth-tin catalyst. The preparation method comprises the following steps: preparing a copper electroplating solution, a bismuth electroplating solution, and a tin electroplating solution; using the gas diffusion layer as a carrier, preparing the copper-bismuth-tin catalyst on the carrier by electrodeposition using the copper electroplating solution, the bismuth electroplating solution, and the tin electroplating solution. The specific steps are as follows:

[0117] S1. Prepare copper plating solution, bismuth plating solution and tin plating solution:

[0118] The copper electroplating solution was prepared by dissolving CuSO4 and H2SO4 in 80 ml of water, respectively, controlling the concentration of CuSO4 to 0.1 M and the concentration of H2SO4 to 0.45 M, and stirring until the solution became clear and transparent to obtain the copper electroplating solution.

[0119] The bismuth electroplating solution was prepared by dissolving Bi(NO3)3 and HNO3 in 80 ml of water, respectively, controlling the concentration of Bi(NO3)3 to 0.05 M and the concentration of HNO3 to 0.35 M, and ultrasonicating for 10 minutes until the solution became clear and transparent, thereby obtaining the bismuth electroplating solution.

[0120] The tin electroplating solution is prepared by dissolving SnCl2, HCl, and Triton X-100 in 80 ml of water, respectively, to control the concentration of SnCl2 to 0.05 M, the concentration of HCl to 0.5 M, and the concentration of Triton X-100 to 0.1 M, and stirring until the solution is homogeneous and stable to obtain a tin electroplating solution, wherein the Triton X-100 is a surfactant;

[0121] The copper electroplating solution, bismuth electroplating solution and tin electroplating solution are all prepared at room temperature.

[0122] S2. Using the gas diffusion layer as the cathode and the copper wire as the anode, copper electrodeposition is performed in a copper electroplating solution to obtain a copper bonding layer on the surface of the gas diffusion layer. The gas diffusion layer is a carbon fiber gas diffusion layer with a hydrophobic carbon black microporous layer. Before use, the gas diffusion layer is pretreated by rinsing the carbon black and carbon fiber surfaces of the gas diffusion layer with pure water, covering the carbon fiber side with 3M tape, leaving only the carbon black microporous layer side exposed, and allowing the treated gas diffusion layer to dry naturally. The copper electrodeposition is performed at room temperature, and 5.5 C cm is deposited at a deposition potential of -0.25 V (vs. Ag / AgCl). -2 The copper with the charged amount is formed, and a copper bonding layer is obtained on the surface of the gas diffusion layer. The gas diffusion layer with the copper bonding layer on the surface is then taken out from the copper electroplating solution, washed with pure water and dried in an air environment at room temperature.

[0123] S3. A gas diffusion layer having a copper bonding layer on its surface is used as a cathode and a platinum mesh electrode is used as an anode. Bismuth is first electrodeposited in a bismuth electroplating solution to obtain a copper-bismuth catalyst; then tin is electrodeposited in a tin electroplating solution to obtain a copper-bismuth-tin catalyst;

[0124] Bismuth electrodeposition was carried out at room temperature. Bismuth with a charge of 4C was deposited at a deposition potential of -0.05 V (vs. Ag / AgCl), corresponding to 0.8 mg cm -2 The bismuth loading was 1.41 mg cm-1 under the condition of 8 C charge of tin at a deposition potential of -0.1 V (vs. Ag / AgCl). -2 The tin loading amount is 200 wt %, and a copper-bismuth-tin catalyst is obtained by bismuth electrodeposition and tin electrodeposition. The gas diffusion layer containing the copper-bismuth-tin catalyst on the surface is then removed from the plating solution, washed with pure water, and dried in an air environment at room temperature. 45 wt % polytetrafluoroethylene is then dropped onto the surface of the copper-bismuth-tin electrode after electrodeposition, and then dried at 300° C. for 2 h to obtain a hydrophobically modified copper-bismuth-tin catalyst.

[0125] Depend on Figure 12 As shown, the catalyst prepared in this example has a flaky structure as a whole, with flaky bismuth and tin evenly dispersed on copper particles with a particle size of about 5 μm, and polytetrafluoroethylene particles evenly covering the surfaces of copper, bismuth and tin.

[0126] The catalyst prepared in Example 5 was tested for its electrocatalytic reduction of carbon dioxide using an electrochemical workstation. A standard three-electrode system was constructed using a proton exchange membrane in a GOSHIRE gas diffusion electrode electrolytic cell. Ag / AgCl electrodes and nickel mesh were used as reference electrodes and counter electrodes, respectively. A gas diffusion electrode loaded with copper, bismuth, and tin catalyst was used as the working electrode. The electrode working area was 1 cm 2 During the measurement, CO2 was continuously introduced into the cathode chamber at a constant rate of 50 sccm. 2M KCl and 2M KOH were used as cathode and anode electrolytes, respectively. The performance test of the reaction was carried out for 1 hour at different current densities using constant current (chronopotentiometry) mode. The gaseous products and liquid products were analyzed by gas chromatograph and ion chromatograph, respectively. The obtained formic acid Faraday efficiency and partial current density are shown in the figure below. Figure 13 The test results show that the catalyst maintains excellent electrochemical selectivity for formic acid at high current density. The catalyst prepared by this method has the best formic acid production performance compared with other catalysts on the market. The specific comparison results are shown in Table 3 below.

[0127] Table 3

[0128]

[0129] The present invention has been described in detail above with reference to the embodiments. However, the contents described are only preferred embodiments of the present invention and should not be considered as limiting the scope of the present invention. All equivalent changes and improvements made within the scope of the present invention should still fall within the scope of the patent coverage of the present invention.

Claims

1. A method for preparing a copper-based catalyst by electrodeposition on a conductive gas diffusion layer, characterized in that: It includes the following steps: A copper electroplating solution and a catalyst electroplating solution are prepared, wherein the catalyst electroplating solution is a bismuth electroplating solution and a tin electroplating solution; a copper bonding layer is prepared on the carrier by electrodeposition using the copper electroplating solution; and a catalyst layer is prepared on the copper bonding layer by electrodeposition using the catalyst electroplating solution, thereby obtaining a copper-based catalyst; It includes the following steps: S1. Prepare copper plating solution, bismuth plating solution and tin plating solution; S2. Copper electrodeposition is performed in a copper electroplating solution using the gas diffusion layer as the cathode and the copper wire as the anode, thereby forming a copper bonding layer on the surface of the gas diffusion layer. Copper electrodeposition is performed at room temperature and at a deposition potential of -0.05 V to -0.45 V vs. Ag / AgCl. 3.5 to 9.5 C·cm -2 After copper is electroplated to obtain a copper bonding layer, the gas diffusion layer containing the copper bonding layer on the surface is removed from the copper electroplating solution, washed with pure water, and then dried in an air environment at room temperature; S3. Using a gas diffusion layer containing a copper bonding layer as the cathode and a platinum mesh electrode as the anode, bismuth was electrodeposited in a bismuth electroplating solution to obtain a copper-bismuth catalyst. Tin was then electrodeposited in a tin electroplating solution to obtain a copper-bismuth-tin catalyst. The catalyst layer was electrodeposited at room temperature. When the catalyst electroplating solution was a bismuth electroplating solution, bismuth with a charge of 4 to 16 C was electrodeposited at a deposition potential of -0.05 V to -0.3 V vs. Ag / AgCl, corresponding to 0.8 to 3.2 mg cm -2 When the catalyst plating solution is a tin plating solution, the tin charge of 8 to 12 C is deposited at a deposition potential of -0.05 V to -0.3 V vs. Ag / AgCl, corresponding to 1.4 to 2.1 mg cm -2 After the catalyst layer is electroplated, the copper-based catalyst is removed from the electroplating solution, washed with pure water, and dried in an air environment at room temperature.

2. The method for preparing a copper-based catalyst by electrodeposition on a conductive gas diffusion layer according to claim 1, wherein: The copper electroplating solution in S1 is prepared by dissolving CuSO4 and H2SO4 in water, respectively, controlling the concentration of CuSO4 to be 0.05M to 0.2M and the concentration of H2SO4 to be 0.1M to 0.55M, and stirring until the solution becomes clear and transparent to obtain a copper electroplating solution; The bismuth electroplating solution is prepared by dissolving Bi(NO3)3 and HNO3 in water, controlling the concentration of Bi(NO3)3 to be 0.05M to 0.2M and the concentration of HNO3 to be 0.1M to 0.45M, and ultrasonicating for 10 minutes until the solution becomes clear and transparent to obtain the bismuth electroplating solution. The tin electroplating solution is prepared by dissolving SnCl2, HCl, and a surfactant, Triton X-100, in water, respectively, controlling the concentration of SnCl2 to be 0.05M to 0.25M, the concentration of HCl to be 0.1M to 0.7M, and the concentration of Triton X-100 to be 0.05M to 0.15M, and stirring until the solution is homogeneous and stable to obtain the tin electroplating solution. The copper electroplating solution and the catalyst electroplating solution are both prepared at room temperature.

3. The method for preparing a copper-based catalyst by electrodeposition on a conductive gas diffusion layer according to claim 1, wherein: The gas diffusion layer used in S2 is a carbon fiber gas diffusion layer with a hydrophobic carbon black microporous layer. Before use, the gas diffusion layer is also pretreated. The specific steps are: rinse the carbon black and carbon fiber surfaces of the gas diffusion layer with pure water, cover the carbon fiber side with tape, leaving only the carbon black microporous layer side exposed, and naturally dry the treated gas diffusion layer.

4. The method for preparing a copper-based catalyst by electrodeposition on a conductive gas diffusion layer according to claim 1, wherein: After the copper, bismuth, and tin catalyst is obtained in S3, 5 to 55 wt% of a polytetrafluoroethylene aqueous dispersion is added dropwise to the surface of the bismuth-tin catalyst layer, and then dried at 300° C. for 2 hours to obtain a hydrophobically modified copper-based catalyst; the mass fraction of the polytetrafluoroethylene aqueous dispersion represents the mass fraction of polytetrafluoroethylene in the total mass of copper, bismuth, and tin deposited on the gas diffusion layer.

5. Use of the copper-based catalyst prepared by the method for preparing a copper-based catalyst according to any one of claims 1 to 4, characterized in that: It is used as a catalyst for the reduction of carbon dioxide to produce formic acid.

Images