A method for solid-phase synthesis of bismuth catalyst and application of the catalyst in preparation of formic acid by reduction of carbon dioxide

Abstract

The application discloses a method for synthesizing a bismuth catalyst in solid phase and application of the catalyst in preparation of formic acid from carbon dioxide reduction, and adopts the following steps: first, bismuth salt, a surfactant and a binder are added into a solution to obtain catalyst precursor slurry; second, the catalyst precursor slurry is sprayed onto a gas diffusion electrode, and a bismuth-based catalyst supported by the gas diffusion electrode is obtained through drying and sintering. The solid-phase synthesis strategy has the advantages of simple method, small solvent consumption, small pollution and easy scaling. The synthesized bismuth catalyst has the advantages of high activity, high formic acid selectivity, high Faraday efficiency and good stability when applied to electrocatalytic reduction of carbon dioxide to prepare formic acid, and lays a foundation for large-scale electro-reduction of carbon dioxide to prepare formic acid.

Description

Technical Field

[0001] This invention belongs to the field of electrocatalyst preparation technology, specifically relating to a method for solid-phase synthesis of bismuth catalysts and the application of the catalyst in the reduction of carbon dioxide to formic acid. Background Technology

[0002] Effectively utilizing renewable energy to promote the capture and reuse of carbon dioxide (CO2) is an important way to solve current energy and environmental problems. CO2 conversion technologies mainly include photochemical, thermochemical, and electrochemical methods. Among them, electrochemical CO2 conversion technology, which uses electricity generated from renewable energy sources to reduce CO2 into high-value gaseous or liquid products, has attracted widespread attention. Electrocatalytic CO2 reduction technology can effectively concentrate the application of widely distributed and low-density clean energy sources. By driving the catalytic reduction process with electricity, CO2 can be converted into economically valuable, high-quality carbon-based chemicals or fuels, while reducing the negative environmental impact of CO2, and has broad application prospects.

[0003] Electrocatalysts play a crucial role in electrocatalytic CO2 reduction technology. In recent years, bismuth catalysts have become a focus of research in CO2 reduction technology due to their high Faradaic efficiency in the reduction of CO2 to formic acid. However, existing preparation methods are mostly hydrothermal or solution-based, which, while achieving some success in laboratory conditions, suffer from drawbacks such as long reaction cycles, complex equipment, high operational difficulty, and unsuitability for large-scale production. Therefore, developing a simple, efficient, low-cost, and scalable method for preparing bismuth catalysts is essential for promoting the practical application and industrial production of electrocatalytic CO2 reduction technology. Summary of the Invention

[0004] This invention is proposed to overcome the shortcomings of the prior art, and its purpose is to provide a method for solid-phase synthesis of bismuth catalysts and the application of the catalysts in the reduction of carbon dioxide to prepare formic acid.

[0005] This invention is achieved through the following technical solution:

[0006] A method for solid-phase synthesis of bismuth catalysts includes the following steps:

[0007] (I) Bismuth salt, surfactant and binder are added to the solution and dispersed by ultrasonication to obtain catalyst precursor slurry;

[0008] (II) The catalyst precursor slurry obtained in step (I) is sprayed onto the gas diffusion electrode, dried, and then sintered in a muffle furnace to obtain the bismuth-based catalyst supported on the gas diffusion electrode.

[0009] In the above technical solution, the bismuth salt is bismuth nitrate, bismuth chloride, or a mixture of bismuth nitrate and bismuth chloride.

[0010] In the above technical solution, the surfactant is any one or more of hexadecyltrimethylammonium bromide, hexadecyltrimethylammonium chloride, or tetrabutylammonium iodide.

[0011] In the above technical solution, the adhesive is any one or more of polyvinylidene fluoride, polytetrafluoroethylene, or fluorinated ethylene propylene copolymer.

[0012] In the above technical solution, the solution is anhydrous ethanol.

[0013] In the above technical solution, the molar ratio of bismuth salt to surfactant in step (I) is 1:(0.9~1.2).

[0014] In the above technical solution, the molar ratio of bismuth salt to binder is 10:1.

[0015] In the above technical solution, the concentration range of bismuth salt in the catalyst precursor slurry in step (I) is 3 to 7 mg / ml.

[0016] In the above technical solution, the gas diffusion electrode is any one or more of YLS-30T, Sigracet 28BC and Sigracet39BB;

[0017] The catalyst precursor slurry spraying amount is 0.8–1 mg / cm³. 2 .

[0018] In the above technical solution, the drying conditions are as follows: the gas diffusion electrode is sprayed on a heating plate at 60-80°C.

[0019] In the above technical solution, the sintering conditions are: heating to 200℃~400℃ at a heating rate of 5℃ / min~10℃ / min, and holding for 0.5h~2.5h. The sintering temperature has a significant impact on the electrocatalytic activity. Using the optimized sintering temperature can produce an electrocatalyst with superior performance for the efficient reduction of carbon dioxide to formic acid, and can effectively suppress the occurrence of the cathode hydrogen evolution reaction.

[0020] An application of the bismuth catalyst prepared by the aforementioned method in the electrocatalytic reduction of carbon dioxide to formic acid involves assembling the bismuth catalyst supported on a gas diffusion electrode as a cathode in an electrochemical reactor, where carbon dioxide is reduced to formic acid upon energization.

[0021] The beneficial effects of this invention are:

[0022] This invention provides a method for solid-phase synthesis of bismuth catalysts and their application in the reduction of carbon dioxide to formic acid. The solid-phase synthesis strategy offers advantages such as simplicity, low solvent consumption, minimal pollution, and ease of scalability. The bismuth catalyst obtained by this method, when applied to the electrocatalytic reduction of carbon dioxide to formic acid, exhibits high activity, high formic acid selectivity and Faradaic efficiency, and good stability, laying the foundation for large-scale electroreduction of carbon dioxide to formic acid. Attached Figure Description

[0023] Figure 1 These are XRD patterns of the bismuth catalysts synthesized in Examples 1, 2, and 3 of this invention;

[0024] Figure 2 SEM image of the bismuth oxychloride catalyst in Example 1 provided by the present invention;

[0025] Figure 3 SEM image of the bismuth oxyiodide catalyst in Example 2 of this invention;

[0026] Figure 4 The image shows a SEM image of the bismuth oxybromocatalyst in Example 3 of this invention.

[0027] For those skilled in the art, other related figures can be obtained from the above figures without any creative effort. Detailed Implementation

[0028] To enable those skilled in the art to better understand the technical solution of the present invention, the technical solution of the present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0029] Example 1

[0030] 1 mol of bismuth nitrate and 1 mol of hexadecyltrimethylammonium chloride were accurately weighed and added to 50 ml of anhydrous ethanol. A small amount of polytetrafluoroethylene solution was added, and the mixture was dispersed by stirring and ultrasonication for 30 min to obtain a catalyst precursor slurry. The precursor slurry was uniformly sprayed onto a gas diffusion electrode, and then the sprayed gas diffusion electrode was transferred to a muffle furnace and heated to 300 °C in an air atmosphere at a heating rate of 5–10 °C / min for 2 h to obtain bismuth oxychloride nanosheet catalyst.

[0031] The XRD pattern of the prepared catalyst is shown in the figure. Figure 1 Its SEM is shown Figure 2 As can be seen, the catalyst exhibits a nanosheet structure.

[0032] Using the bismuth oxychloride catalyst prepared in Example 1 as the cathode material, the highest Faraday efficiency of electrocatalytic reduction of CO2 to formic acid was approximately 83.6%.

[0033] Example 2

[0034] 1 mol of bismuth nitrate and 1 mol of tetrabutylammonium iodide were accurately weighed and added to 50 ml of anhydrous ethanol. A small amount of polytetrafluoroethylene solution was added, and the mixture was dispersed by stirring and ultrasonication for 30 min to obtain a catalyst precursor slurry. The precursor slurry was uniformly sprayed onto a gas diffusion electrode, and then the sprayed gas diffusion electrode was transferred to a muffle furnace and heated to 300 °C in an air atmosphere at a heating rate of 5–10 °C / min for 2 h to obtain bismuth iodide nanosheet catalyst.

[0035] The XRD pattern of the prepared catalyst is shown in the figure. Figure 1 Its SEM is shown Figure 3 As can be seen, the catalyst exhibits a nanosheet structure.

[0036] Using the bismuth oxyiodide catalyst prepared in Example 2 as the cathode material, the highest Faraday efficiency of electrocatalytic reduction of CO2 to formic acid was approximately 80.1%.

[0037] Example 3

[0038] 1 mol of bismuth nitrate and 1 mol of hexadecyltrimethylammonium bromide were accurately weighed and added to 50 ml of anhydrous ethanol. A small amount of polytetrafluoroethylene solution was added, and the mixture was dispersed by stirring and ultrasonication for 30 min to obtain a catalyst precursor slurry. The precursor slurry was uniformly sprayed onto a gas diffusion electrode, and then the sprayed gas diffusion electrode was transferred to a muffle furnace and heated to 300 °C in an air atmosphere at a heating rate of 5–10 °C / min for 2 h to obtain a bismuth oxybromide nanosheet catalyst.

[0039] The XRD pattern of the prepared catalyst is shown in the figure. Figure 1 Its SEM is shown Figure 4 As can be seen, the catalyst exhibits a nanosheet structure.

[0040] Using the bismuth oxybromocatalyst prepared in Example 3 as the cathode material, the highest Faraday efficiency of electrocatalytic reduction of CO2 to formic acid was approximately 91%.

[0041] The solid-phase synthesis method of this invention has the advantages of simple operation, low solvent consumption, low pollution, and easy scalability. The bismuth catalyst prepared using this method, when applied to the electrocatalytic reduction of carbon dioxide to formic acid, exhibits high catalytic activity, excellent formic acid selectivity and Faraday efficiency, as well as good stability, providing a solid foundation for the large-scale application of formic acid production by carbon dioxide electroreduction.

[0042] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other.

[0043] The applicant declares that the above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A method for solid-phase synthesis of bismuth catalysts, characterized in that: Includes the following steps: (I) Bismuth salt, surfactant and binder are added to the solution to obtain catalyst precursor slurry; (II) The catalyst precursor slurry obtained in step (I) is sprayed onto the gas diffusion electrode, and then dried and sintered to obtain the bismuth catalyst supported on the gas diffusion electrode; The bismuth salt is bismuth nitrate, bismuth chloride, or a mixture of bismuth nitrate and bismuth chloride; The surfactant is any one or more of hexadecyltrimethylammonium bromide, hexadecyltrimethylammonium chloride, or tetrabutylammonium iodide; The adhesive is any one or more of polyvinylidene fluoride, polytetrafluoroethylene, or fluorinated ethylene propylene copolymer; The solution is anhydrous ethanol.

2. The method for solid-phase synthesis of bismuth catalyst according to claim 1, characterized in that: In step (I), the molar ratio of bismuth salt to surfactant is 1:(0.9~1.2). In step (I), the molar ratio of bismuth salt to binder is 10:1; In step (I), the concentration of bismuth salt in the catalyst precursor slurry ranges from 3 mg / mL to 7 mg / mL.

3. The method for solid-phase synthesis of bismuth catalyst according to claim 1, characterized in that: The gas diffusion electrode is any one or more of YLS-30T, Sigracet 28 BC, or Sigracet 39 BB; The catalyst precursor slurry was sprayed at a rate of 0.8 mg / cm³. 2 ~1 mg / cm 2 .

4. The method for solid-phase synthesis of bismuth catalyst according to claim 1, characterized in that: The drying conditions are as follows: the gas diffusion electrode is sprayed on a heating plate at 60 ℃~80 ℃. The sintering conditions are as follows: heating to 200℃~400℃ at a heating rate of 5℃ / min~10℃ / min, and holding for 0.5h~2.5h.

5. The application of a bismuth catalyst prepared by the method according to any one of claims 1 to 4 in the electrocatalytic reduction of carbon dioxide to formic acid, characterized in that: The bismuth catalyst supported on the gas diffusion electrode is assembled into an electrochemical reactor as a cathode. After energizing, carbon dioxide is reduced at the cathode to formic acid.

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