Bismuth-based core-shell structure catalyst as well as preparation method and application thereof

Abstract

The invention provides a bismuth-based core-shell structure catalyst and a preparation method and application thereof, and belongs to the technical field of electric energy catalytic conversion. The bismuth-based core-shell structure catalyst comprises Bi nanoparticles and a shell layer coating the Bi nanoparticles, the shell layer is of a mesoporous structure, and the material of the shell layer comprises a nitrogen-doped carbon material. According to the technical scheme, the bismuth-based core-shell structure catalyst is provided, the catalyst takes Bi nanoparticles as a core and a nitrogen-doped carbon material with a mesoporous structure as a shell, highly concentrated and small-size pore size distribution is shown, the adsorption performance on carbon dioxide is improved based on the space confinement effect, and the catalyst not only has relatively high catalytic activity, but also has a good application prospect. And the catalyst has extremely high formic acid production selectivity, can realize efficient electro-catalysis of reduction of carbon dioxide to produce formic acid, also has good stability, and shows good application prospects.

Description

Technical Field

[0001] This invention relates to the field of electrocatalytic conversion technology, specifically to a bismuth-based core-shell catalyst, its preparation method, and its application. Background Technology

[0002] The excessive extraction and utilization of traditional fossil fuels has led to excessive CO2 emissions, causing serious environmental and climate problems. While the development and utilization of clean energy technologies have enabled the conversion of solar, wind, tidal, and geothermal energy into electricity, limitations imposed by geographical location and climate have resulted in intermittent and mismatched power supply. However, by simulating photoelectrochemical synthesis processes, CO2 can be converted into stably stored intermediate industrial products or fuels under mild conditions, effectively solving the problem of storing electricity converted from renewable energy sources and alleviating the energy crisis. Therefore, there is an urgent need for a well-designed catalyst to achieve efficient and highly selective electrocatalytic CO2 reduction.

[0003] Formic acid (HCOOH) can be used directly as fuel, and it is also an important raw material and intermediate in chemical production, possessing significant economic and practical value. Bismuth-based catalysts exhibit a certain selectivity for formic acid, and the main byproducts are gaseous CO and H2, which facilitates product collection and separation. However, existing bismuth-based catalysts have limited selectivity for formic acid. Summary of the Invention

[0004] In view of the technical problems existing in the background art, this application provides a bismuth-based core-shell structure catalyst, its preparation method and application, aiming to provide a bismuth-based core-shell structure catalyst with high formic acid selectivity.

[0005] In a first aspect, embodiments of this application provide a bismuth-based core-shell structure catalyst, the bismuth-based core-shell structure catalyst comprising Bi nanoparticles and a shell layer coated on the Bi nanoparticles, the shell layer being a mesoporous structure and the material of the shell layer comprising nitrogen-doped carbon material.

[0006] Optionally, in some embodiments of this application, the bismuth-based core-shell catalyst has an average pore size of 3-5 nm.

[0007] Secondly, embodiments of this application provide a method for preparing the bismuth-based core-shell structured catalyst described above, comprising the following steps: Bi nanoparticles and hexadecyltrimethylammonium bromide were dispersed in a mixed solvent and ultrasonicated to obtain a first mixed solution, wherein the mixed solvent included ethanol and deionized water; Adjust the pH of the first mixed solution to 8-10, then add tetraethoxysilane and stir to obtain the second mixed solution; The second mixed solution was mixed with anhydrous ethanol, and the reaction yielded the first precursor. The first precursor was dispersed in an aqueous solution of glucose and then freeze-dried to obtain the second precursor. The second precursor was calcined in a mixed atmosphere of argon and ammonia to obtain a bismuth-based core-shell catalyst.

[0008] Optionally, in some embodiments of this application, the mass ratio of the Bi nanoparticles to hexadecyltrimethylammonium bromide is 1:1 to 10.

[0009] Optionally, in some embodiments of this application, the mass ratio of the Bi nanoparticles to tetraethoxysilane is 1:0.1~20.

[0010] Optionally, in some embodiments of this application, the mass ratio of glucose in the aqueous solution of glucose to the first precursor is 0.05 to 0.2:1.

[0011] Optionally, in some embodiments of this application, ammonia is used to adjust the pH of the first mixed solution to 8-10.

[0012] Optionally, in some embodiments of this application, in the step of mixing the second mixed solution with anhydrous ethanol to obtain the first precursor, the reaction temperature is 50~100℃ and the reaction time is 18~24h.

[0013] Optionally, in some embodiments of this application, the calcination temperature is 600~1000℃, and the calcination time is 1~4h.

[0014] Optionally, in some embodiments of this application, before the step of dispersing Bi nanoparticles and hexadecyltrimethylammonium bromide in a mixed solvent and ultrasonicating to obtain a first mixed solution, the following step is further included: Ethylene glycol and nitric acid are mixed to obtain a mixture; Bismuth nitrate and polyvinylpyrrolidone were added to the mixture, and the mixture was ultrasonically stirred to obtain a third mixed solution; The third mixed solution was reacted at 120~240℃ for 12~48h to obtain Bi nanospheres.

[0015] Optionally, in some embodiments of this application, the molar ratio of bismuth nitrate to polyvinylpyrrolidone is 1:0.05~0.2.

[0016] Thirdly, this application also proposes the application of the bismuth-based core-shell structure catalyst described above in electrocatalytic CO2 reduction.

[0017] The technical solution proposed in this application has the following beneficial effects: This application proposes a bismuth-based core-shell catalyst. The catalyst uses Bi nanoparticles as the core and nitrogen-doped carbon material with a mesoporous structure as the shell, exhibiting a highly concentrated and small pore size distribution. Based on the spatial confinement effect, it improves the adsorption performance of carbon dioxide. This catalyst not only has high catalytic activity but also extremely high formic acid production selectivity, enabling efficient electrocatalytic reduction of carbon dioxide to formic acid. In addition, the catalyst also has good stability, showing good application prospects.

[0018] The above description is only an overview of the technical solution of this application. In order to better understand the technical means of this application and to implement it in accordance with the contents of the specification, and to make the above and other objects, features and advantages of this application more obvious and understandable, the following are specific embodiments of this application. Attached Figure Description

[0019] To more clearly illustrate the technical solution of this application, the accompanying drawings used in this application will be briefly described below. Obviously, the drawings described below are merely some embodiments of this application. For those skilled in the art, other drawings can be obtained from these drawings without any creative effort.

[0020] Figure 1 A schematic flowchart illustrating a method for preparing a bismuth-based core-shell catalyst according to an embodiment of this application; Figure 2 The pore size distribution diagrams are shown for the Bi@mNC material prepared in Example 1 and the Bi nanoparticles prepared in Comparative Example 1. Figure 3 The Faraday efficiency (FE) of the Bi@mNC materials prepared in Examples 1, 4, and 5 and the Bi nanoparticles prepared in Comparative Example 1 for the electrocatalytic reduction of CO2 to HCOOH is shown. HCOOH Comparison chart; Figure 4 The partial current density of the Bi@mNC materials prepared in Examples 1, 4, and 5 and the Bi nanoparticles prepared in Comparative Example 1 for the electrocatalytic reduction of CO2 to HCOOH ( J HCOOH Comparison chart; Figure 5 The Faraday efficiency (FE) of the Bi@mNC materials prepared in Examples 1, 4, and 5 and the Bi nanoparticles prepared in Comparative Example 1 for the electrocatalytic reduction of CO2 to CO is shown. CO Comparison chart; Figure 6The Faraday efficiency (FE) of the Bi@mNC materials prepared in Examples 1, 4, and 5 and the Bi nanoparticles prepared in Comparative Example 1 for the electrocatalytic reduction of CO2 to H2 is shown. H2 Comparison chart; Figure 7 The image shows a SEM image of the Bi nanoparticles prepared in Comparative Example 1. Detailed Implementation

[0021] The embodiments of the technical solution of this application will now be described in detail with reference to the accompanying drawings. These embodiments are only used to more clearly illustrate the technical solution of this application and are therefore merely examples, and should not be used to limit the scope of protection of this application.

[0022] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the application; the terms “comprising” and “having”, and any variations thereof, in the specification, claims, and foregoing description of the drawings are intended to cover non-exclusive inclusion.

[0023] Various embodiments of this application may exist in the form of a range; it should be understood that the description in the form of a range is merely for convenience and brevity and should not be construed as a hard limitation on the scope of this application; therefore, it should be considered that the range description has specifically disclosed all possible sub-ranges and single numerical values ​​within that range. For example, it should be considered that the range description from 1 to 6 has specifically disclosed sub-ranges such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., and single numbers within the range, such as 1, 2, 3, 4, 5, and 6, regardless of the range. Furthermore, whenever a numerical range is referred to herein, it means including any referenced number (fraction or integer) within the referred range.

[0024] In the description of the embodiments of this application, technical terms such as "first" and "second" are used only to distinguish different objects and should not be construed as indicating or implying relative importance or implicitly specifying the number, specific order, or primary and secondary relationship of the indicated technical features. In the description of the embodiments of this application, "multiple" means two or more, unless otherwise explicitly defined.

[0025] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0026] In the description of the embodiments in this application, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone. Additionally, the character " / " in this document generally indicates that the preceding and following related objects have an "or" relationship.

[0027] In the description of the embodiments of this application, the term "at least one" refers to one or more, "more than one" refers to two or more (including two), similarly, "multiple sets" refers to two or more (including two sets), and "multiple pieces" refers to two or more (including two pieces). "At least one," "at least one of the following," or similar expressions refer to any combination of these items, including any combination of single or multiple items. For example, "at least one of a, b, or c," or "at least one of a, b, and c," can all represent: a, b, c, ab (i.e., a and b), ac, bc, or abc, where a, b, and c can be single or multiple.

[0028] In a first aspect, embodiments of this application provide a bismuth-based core-shell structure catalyst, the bismuth-based core-shell structure catalyst comprising Bi nanoparticles and a shell layer coated on the Bi nanoparticles, the shell layer being a mesoporous structure and the material of the shell layer comprising nitrogen-doped carbon material.

[0029] This application proposes a bismuth-based core-shell catalyst. The catalyst uses Bi nanoparticles as the core and nitrogen-doped carbon material with a mesoporous structure as the shell. Through a uniform and ordered mesoporous structure, it exhibits a highly concentrated and small-sized pore distribution. Due to the spatial confinement effect, the smaller pore size facilitates carbon dioxide adsorption and mass transfer, thus effectively improving the catalyst's adsorption performance for carbon dioxide, increasing the local CO2 concentration, and promoting its reduction. Simultaneously, the nitrogen-doped carbon coating layer optimizes the electron configuration on the surface of the Bi nanoparticles, effectively improving conductivity. Therefore, this catalyst exhibits high catalytic activity, formic acid selectivity, and stability (in some embodiments, the catalyst can achieve a formic acid selectivity of up to 98% at -0.9 V vs. RHE potential, with a partial current density reaching -55.8 mA·cm⁻¹). -2 Furthermore, the selectivity of formic acid can still be maintained above 90% after 60 hours, which can realize the efficient electrocatalytic reduction of carbon dioxide to formic acid and has good application prospects.

[0030] In some embodiments of this application, the bismuth-based core-shell catalyst has an average pore size of 3-5 nm. The smaller pore size is beneficial for carbon dioxide adsorption.

[0031] Secondly, embodiments of this application provide a method for preparing the bismuth-based core-shell structured catalyst described above, such as... Figure 1 As shown, the preparation method includes the following steps: S10, Bi nanoparticles and hexadecyltrimethylammonium bromide (CTAB) are dispersed in a mixed solvent and sonicated to obtain a first mixed solution, wherein the mixed solvent includes ethanol and deionized water.

[0032] S20, adjust the pH of the first mixed solution to 8-10, then add tetraethoxysilane (TEOS) and stir to obtain the second mixed solution.

[0033] S30, the second mixed solution is mixed with anhydrous ethanol to react and obtain the first precursor Bi@mSiO2.

[0034] S40, the first precursor is dispersed in an aqueous solution of glucose and freeze-dried to obtain the second precursor Bi@mSiO2@C.

[0035] S50, the second precursor is calcined in a mixed atmosphere of argon and ammonia to obtain a bismuth-based core-shell catalyst Bi@mNC.

[0036] In the technical solution provided in this application, the surfactant CTAB is used as a mesoporous template and TEOS is used as a SiO2 precursor. These are hydrolyzed under an alkaline environment to generate mesoporous SiO2 (mSiO2). A uniform mesoporous SiO2 (mSiO2) layer is then coated onto Bi nanoparticles using a sol-gel method, serving as a template for subsequent mesoporous NC materials. Subsequently, the obtained material is immersed in a glucose solution, which permeates into the mesoporous SiO2 layer and acts as a carbon source. Finally, NH3 is used as a nitrogen source, and the material undergoes high-temperature carbonization under an Ar / NH3 atmosphere to obtain a Bi@mNC material with a core-shell structure coated with mesoporous NC material (mNC). The method of this application is simple, easy to control, and can successfully prepare Bi@mNC materials.

[0037] In step S10, the Bi nanoparticles can be commercially available or prepared in-house. For example, in some embodiments, the following steps for preparing Bi nanoparticles may be included before step S10: S11, ethylene glycol and nitric acid are mixed to obtain a mixture.

[0038] S12, bismuth nitrate and polyvinylpyrrolidone (PVP) are added to the mixture and ultrasonically stirred to obtain a third mixed solution.

[0039] S13, the third mixed solution is reacted at 120~240℃ for 12~48h to obtain Bi nanospheres.

[0040] Bi nanospheres can be synthesized via a solvothermal method, which is a simple process with readily available raw materials.

[0041] The bismuth nitrate can be Bi(NO3)3·5H2O, and the molar ratio of bismuth nitrate to polyvinylpyrrolidone (PVP) is 1:0.05~0.2. The nitric acid can be a 1 mol / L nitric acid solution, and the volume ratio of ethylene glycol to nitric acid solution in the mixture can be 9~1:1. When adding bismuth nitrate and PVP to the mixture, the amount of mixture used can refer to the following conditions: the molar ratio of bismuth nitrate to nitric acid is 0.1~0.05:1.

[0042] In step S10, the mass ratio of Bi nanoparticles to hexadecyltrimethylammonium bromide can be 1:1 to 10.

[0043] In step S20, ammonia can be used to adjust the pH of the first mixed solution to 8-10.

[0044] In step S20, the amount of tetraethoxysilane can be adjusted according to the following conditions: the mass ratio of Bi nanoparticles to tetraethoxysilane is 1:0.1~20.

[0045] In step S40, the amount of glucose used satisfies the following condition: the mass ratio of glucose in the glucose aqueous solution to the first precursor is 0.05~0.2:1. In specific implementation, a glucose aqueous solution with a mass concentration of 20wt% can be used, and the glucose aqueous solution to the first precursor can be added according to a mass ratio of 0.25~1.

[0046] In step S30, the reaction temperature can be 50~100℃, and the reaction time can be 18~24h.

[0047] In step S40, the volume concentration of NH3 in the Ar / NH3 mixed atmosphere can be 5 vol%. The freeze-drying temperature can be -40℃ to -50℃, and the drying etching can be 36h to 48h.

[0048] In step S50, the calcination temperature can be 600~1000℃, and the calcination time can be 1~4h.

[0049] Thirdly, this application also proposes the application of the bismuth-based core-shell structure catalyst described above in the electrocatalytic reduction of CO2. The catalyst exhibits high catalytic activity, high formic acid selectivity, and stability, making it suitable for use as an electrocatalytic CO2 reduction catalyst.

[0050] The following are some specific embodiments. It should be noted that the embodiments described below are exemplary and are only used to explain this application, and should not be construed as limiting this application. Where specific techniques or conditions are not specified in the embodiments, they shall be performed in accordance with the techniques or conditions described in the literature in this field or according to the product instructions. Reagents or instruments whose manufacturers are not specified are all conventional products that can be obtained commercially.

[0051] Example 1 (1) According to the molar ratio of Bi(NO3)3·5H2O to PVP of 1:0.11, 0.75 mmol of Bi(NO3)3·5H2O and 0.08 mmol of PVP were added to a mixture of 50 mL of ethylene glycol and 10 mL of 1 mol / L nitric acid. After sonication for 30 min, the magnetic stirrer was set to 600 rpm and stirred for 30 min to obtain a mixed solution. The mixed solution was transferred to a 100 mL polytetrafluoroethylene-lined stainless steel autoclave and reacted at 160 °C for 12 h to obtain a reaction mixture. The reaction mixture was centrifuged, the solid product was collected, and washed three times with ethanol and water by centrifugation, respectively. Then, it was vacuum dried overnight to obtain Bi nanoparticles.

[0052] (2) Weigh 300 mg of the above Bi nanoparticles and 450 mg of cetyltrimethylammonium bromide (CTAB) and disperse them in a mixed solution of ethanol and deionized water (volume ratio of 6:4). After sonicating for 30 min, set the speed of the magnetic stirrer to 600 rpm and stir for 30 min to obtain the first mixed solution.

[0053] (3) Add an appropriate amount of ammonia to the first mixed solution to adjust the pH value of the solution to 9. Then, slowly add 240 mg of tetraethoxysilane (TEOS) and continue stirring at room temperature to obtain the second mixed solution.

[0054] (4) At 70°C, the second mixed solution was mixed with 50 mL of anhydrous ethanol and subjected to condensation and reflux reaction for 24 h to obtain Bi@mSiO2 precursor.

[0055] (5) Take the solid powder of the above Bi@mSiO2 precursor, ultrasonically disperse it in an aqueous solution of glucose (mass concentration of 20%, and control the mass ratio of glucose to Bi@mSiO2 precursor to 0.75), and freeze dry for 48 hours to obtain dry powder.

[0056] (6) In a mixed gas flow of Ar and NH3 (NH3 volume percentage is 5 vol%), the dry powder is heated to 800℃ at a rate of 2℃ / min and kept at this temperature for 1h. Then, the silicon dioxide is removed with 1 mol / L sodium hydroxide aqueous solution to obtain Bi@mNC electrocatalyst.

[0057] Example 2 The scheme in this embodiment is basically the same as that in embodiment 1, except that in step (1) of this embodiment, the hydrothermal reaction time at 160°C is changed from 12h to 24h. Other than that, all other parameters and conditions remain unchanged.

[0058] Example 3 The scheme in this embodiment is basically the same as that in embodiment 1, except that in step (1) of this embodiment, the hydrothermal reaction time at 160°C is changed from 12h to 48h. Other than that, all other parameters and conditions remain unchanged.

[0059] Example 4 The scheme in this embodiment is basically the same as that in embodiment 1, except that in step (6) of this embodiment, the calcination time at 800℃ is changed from 1h to 2h. Other than that, all other parameters and conditions remain unchanged.

[0060] Example 5 The scheme in this embodiment is basically the same as that in embodiment 1, except that in step (6) of this embodiment, the calcination time at 800°C is changed from 1 hour to 4 hours. Other than that, all other parameters and conditions remain unchanged.

[0061] Comparative Example 1 This comparative example is the Bi nanoparticles obtained in step (2) of Example 1.

[0062] The morphology of Bi nanoparticles was measured using scanning electron microscopy (SEM), and the results are as follows: Figure 7 As shown in the figure, the Bi nanoparticles are uniform in size, with a particle size of about 100 nm.

[0063] (a) Taking the products from Example 1 and Comparative Example 1, the pore size distribution of the materials was obtained using the BET test method and the BJH model. The results are as follows: Figure 2 As shown.

[0064] Results analysis: The Bi@mNC electrocatalyst prepared in Example 1 is mainly mesoporous with an average pore size of about 4 nm, while the Bi nanoparticles in Comparative Example 1 exhibit a non-porous structure. Obviously, the method of this application has successfully prepared Bi@mNC materials with a core-shell structure—Bi nanoparticles coated with mesoporous nitrogen-carbon materials.

[0065] (II) The Bi@mNC electrocatalysts prepared in Examples 1 to 5 were subjected to electrochemical performance testing using a three-electrode system: The sample was dispersed in a mixed solvent of 0.3 mL isopropanol and 0.7 mL ultrapure water (volume ratio 3:7). 2 μL of Nafion solution was added to the above solution and ultrasonically dispersed for 30 min to obtain an electrode dispersion. The electrode dispersion was drop-coated onto carbon cloth and dried to form an electrode. Using this electrode as the working electrode, a saturated calomel electrode as the reference electrode, and a carbon rod as the counter electrode, a CO2-saturated 0.5 mol / L KHCO3 electrolyte solution was used as the electrolyte. The electrochemical performance of the catalyst was tested in an H-type electrolytic cell. During the test, sufficient CO2 was passed through the reaction electrode, the CO2 flow rate was controlled at 13 mL / min, and the electrolysis voltage range was -0.6 V to -1.2 V (vs. RHE). The gaseous and liquid products were analyzed by gas chromatography and electrochemical chromatography, respectively. 1 Quantitative analysis was performed using 1H NMR (hydrogen NMR) spectra.

[0066] Testing revealed that the catalysts prepared in each example exhibited the highest formic acid selectivity at -0.9 V vs. RHE. The formic acid production selectivities of the catalysts prepared in Examples 1, 2, and 3 at -0.9 V vs. RHE were 87%, 92%, and 85%, respectively, and the formic acid fractional current densities of the three catalysts reached -43.2 mA·cm⁻¹. -2 -47.1mA·cm -2 -40.3mA·cm -2 This indicates that the electrocatalyst prepared by the method of this application exhibits high formic acid selectivity for electrocatalytic CO2 production.

[0067] (III) Referring to the above method, the Bi@mNC electrocatalysts prepared in Examples 1, 4, and 5, as well as the Bi nanoparticles of Comparative Example 1, were subjected to electrochemical performance tests. Specifically, gas chromatography was used for quantitative analysis when testing the selectivity for H2 and CO production; and gas chromatography was used for quantitative analysis when testing the selectivity for HCCOH production. 1 Quantitative analysis was performed using 1H NMR (hydrogen NMR) spectra. Results are as follows: Figures 3 to 6 As shown.

[0068] Comparative Example 1 exhibited the lowest HCOOH selectivity at all applied potentials, and reached the maximum FE at -1.0 V vs. RHE. HCOOH The formic acid fraction has a current density of 83% and a fractional current density of -38.2 mA·cm⁻¹. -2After coating the surface with mesoporous nitrogen-carbon material, the selectivity and activity of carbon dioxide reduction to formic acid were significantly improved. Furthermore, the catalyst prepared in Example 4 exhibited the highest selectivity and activity for carbon dioxide reduction to formic acid: at -0.9 V vs. RHE, it showed a high formic acid selectivity of 98%, and the formic acid fractional current density reached -55.8 mA·cm⁻¹. -2 , which is much higher than the control group 1.

[0069] Furthermore, the tests also revealed that the catalyst exhibits good catalytic stability, with the selectivity for formic acid remaining above 90% after 60 hours.

[0070] (iv) The Bi@mNC electrocatalysts prepared in Examples 1, 4 and 5 were used to detect the N content in the materials using X-ray photoelectron spectroscopy (XPS).

[0071] Upon testing, the N doping content in the Bi@mNC electrocatalysts prepared in Examples 1, 4, and 5 was found to be 1.2 at.%, 3.1 at.%, and 2.3 at.%, respectively.

[0072] It should be noted that this application is not limited to the above-described embodiments. The above embodiments are merely examples, and any embodiments with the same structure and effect as the technical concept within the scope of this application are included in the technical scope of this application. Furthermore, various modifications that can be conceived by those skilled in the art to the embodiments, and other ways of constructing by combining some of the constituent elements of the embodiments, without departing from the spirit of this application, are also included in the scope of this application.

Claims

1. A bismuth-based core-shell catalyst, characterized in that, The bismuth-based core-shell catalyst comprises Bi nanoparticles and a shell layer coated on the Bi nanoparticles. The shell layer has a mesoporous structure and the material of the shell layer includes nitrogen-doped carbon material.

2. The bismuth-based core-shell catalyst according to claim 1, characterized in that, The bismuth-based core-shell catalyst has an average pore size of 3-5 nm.

3. A method for preparing a bismuth-based core-shell structured catalyst according to claim 1 or 2, characterized in that, Includes the following steps: Bi nanoparticles and hexadecyltrimethylammonium bromide were dispersed in a mixed solvent and ultrasonicated to obtain a first mixed solution, wherein the mixed solvent included ethanol and deionized water; Adjust the pH of the first mixed solution to 8-10, then add tetraethoxysilane and stir to obtain the second mixed solution; The second mixed solution was mixed with anhydrous ethanol, and the reaction yielded the first precursor. The first precursor was dispersed in an aqueous solution of glucose and then freeze-dried to obtain the second precursor. The second precursor was calcined in a mixed atmosphere of argon and ammonia to obtain a bismuth-based core-shell catalyst.

4. The preparation method according to claim 3, characterized in that, The mass ratio of the Bi nanoparticles to hexadecyltrimethylammonium bromide is 1:1~10; and / or, The mass ratio of Bi nanoparticles to tetraethoxysilane is 1:0.1~20; and / or, The mass ratio of glucose to the first precursor in the aqueous solution of glucose is 0.05~0.2:

1.

5. The preparation method according to claim 3, characterized in that, In the step of mixing the second mixed solution with anhydrous ethanol to obtain the first precursor, the reaction temperature is 50~100℃ and the reaction time is 18~24h.

6. The preparation method according to claim 3, characterized in that, The calcination temperature is 600~1000℃, and the calcination time is 1~4h.

7. The preparation method according to claim 3, characterized in that, The pH of the first mixed solution was adjusted to 8-10 using ammonia.

8. The preparation method according to claim 3, characterized in that, Before the step of dispersing Bi nanoparticles and hexadecyltrimethylammonium bromide in a mixed solvent and ultrasonicating to obtain a first mixed solution, the following steps are also included: Ethylene glycol and nitric acid are mixed to obtain a mixture; Bismuth nitrate and polyvinylpyrrolidone were added to the mixture, and the mixture was ultrasonically stirred to obtain a third mixed solution; The third mixed solution was reacted at 120~240℃ for 12~48h to obtain Bi nanospheres.

9. The preparation method according to claim 8, characterized in that, The molar ratio of bismuth nitrate to polyvinylpyrrolidone is 1:0.05~0.

2.

10. The application of a bismuth-based core-shell structure catalyst as described in claim 1 or 2 in electrocatalytic CO2 reduction.

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