A multilayer core-shell palladium-platinum-nickel fuel cell catalyst and a preparation method and application thereof

Abstract

The application provides a multilayer core-shell palladium-platinum-nickel fuel cell catalyst and a preparation method and application thereof, and the preparation method comprises the following steps: dispersing a nickel salt and a carbon carrier in water, sufficiently dispersing to form a uniform slurry, adding a first reducing agent solution, stirring at 60-70 DEG C for 1-3 hours, and forming a Ni core on the carrier; adding a platinum salt to the slurry, adding a second reducing agent after heating to 90-95 DEG C, and reacting for 3-8 hours to form a PtNi core; cooling to 75-85 DEG C, adding a palladium salt and a third reducing agent solution, and reacting for 8-48 hours to form a PdPt outer layer; collecting the precipitate of the reacted solution, repeatedly washing the precipitate with deionized water, drying the washed precipitate, and obtaining a multilayer core-shell palladium-platinum-nickel carbon catalyst. The catalyst of the application significantly improves the durability while maintaining high activity, greatly improves the service life and reliability of the fuel cell while the catalyst maintains high energy conversion efficiency.

Description

Technical Field

[0001] This invention relates to the field of catalyst materials technology, specifically to a multilayer core-shell palladium-platinum-nickel fuel cell catalyst, its preparation method, and its application. Background Technology

[0002] As a clean energy conversion technology, the commercialization of fuel cells is greatly influenced by catalyst performance. Currently, platinum-based catalysts are widely used in fuel cells due to their high activity, especially platinum-nickel catalysts, which have shown certain advantages over pure platinum catalysts in terms of improving activity and reducing costs. However, existing platinum-nickel catalysts still face the problem of insufficient durability during long-term operation of fuel cells. This is mainly due to structural changes and loss of active sites during the reaction process, leading to performance degradation.

[0003] To address this challenge, our research has developed a method for preparing multilayer core-shell palladium-platinum-nickel fuel cell catalysts. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of existing technologies and provide a multilayer core-shell palladium-platinum-nickel fuel cell catalyst, its preparation method, and its application. Compared with platinum-nickel catalysts currently used in the market, the catalyst of this invention maintains high activity while significantly improving durability, thus solving the problem of durability failure in existing alloy catalysts. While maintaining efficient energy conversion, the catalyst also greatly improves the lifespan and reliability of the fuel cell. Furthermore, the preparation method of this invention is more environmentally friendly and economical, providing a new technical path and commercial potential for the widespread application of fuel cells.

[0005] To achieve the above technical objectives, the technical solution adopted in the embodiments of the present invention is as follows: In a first aspect, embodiments of the present invention provide a method for preparing a multilayer core-shell palladium-platinum-nickel fuel cell catalyst, comprising the following steps: (1) Ni core formation: Disperse an appropriate amount of nickel salt and carbon support in water, and fully disperse them at 30-40℃ to form a uniform slurry. Add a first reducing agent solution with a concentration of 0.4-1 mol / L. The molar ratio of the first reducing agent to Ni in the solution is 2-5. Heat to 60-70℃ and stir for 1-3 hours to form Ni cores on the support. (2) Preparation of PtNi intermediate layer: Add an appropriate amount of platinum salt to the slurry at 60-70℃ in step (1), and add a second reducing agent after heating to 90-95℃. The molar ratio of the second reducing agent to Pt is 60-1200. React for 3-8 hours. By increasing the temperature, the reduction potential of platinum ions is reduced, so that they are selectively deposited on the Ni surface to form a Pt intermediate layer. The Pt layer is relative to the Ni core, and the whole forms a PtNi core. (3) Formation of PdPt outer layer: Cool down to 75-85℃, add palladium salt and a third reducing agent solution with a concentration of 0.05-0.3mol / L that can control the reaction rate. The molar ratio of the third reducing agent to Pd in ​​the solution is 1-3. React for 8-48h to reduce palladium ions and platinum ions that were not completely reduced in step (2) to form PdPt outer layer; (4) Washing and drying: Collect the precipitate from the solution after the reaction in step (3), wash the precipitate repeatedly with deionized water, and dry the washed precipitate in a vacuum oven at 60-80℃ for 6-12h to obtain a multilayer core-shell palladium-platinum-nickel-carbon catalyst.

[0006] Further, in step (1), the nickel salt is one or more of triethylenediamine nickel sulfate, nickel ammonium sulfate hexahydrate, and hexaammine nickel chloride.

[0007] Furthermore, in step (1), the carbon support is one or more of mesoporous carbon support, polymer composite porous carbon, and acetylene black; The first reducing agent is one or more of sodium hypophosphite, sodium bisulfite, and potassium borohydride.

[0008] Furthermore, in step (2), the platinum salt is one or more of diammineplatinum dichloro, potassium chloroplatinate, and platinum sulfate tetrahydrate; The second reducing agent is one or more of 1,2-propanediol, ethanol, and ascorbic acid.

[0009] Further, in step (3), the temperature is lowered to 77-83℃, and palladium salt and a third reducing agent solution with a concentration of 0.05-0.3mol / L that can control the reaction rate are added. The molar ratio of the third reducing agent to Pd in ​​the solution is 1-3, and the reaction is carried out for 12-24h.

[0010] Further, in step (3), the palladium salt is one or more of potassium tetrachloropalladium, dichlorodiaminopalladium, and palladium acetylacetonate; The third reducing agent is one or more of hexadecyltrimethylammonium bromide, glucose, and polyvinylpyrrolidone.

[0011] In a second aspect, embodiments of the present invention provide a multilayer core-shell palladium-platinum-nickel fuel cell catalyst, which is prepared by the preparation method described in the first aspect. In the multilayer core-shell palladium-platinum-nickel carbon fuel cell catalyst, palladium accounts for 5-7% of the mass of the catalyst, platinum accounts for 9-11% of the mass of the catalyst, and nickel accounts for 6-9% of the mass of the catalyst.

[0012] Thirdly, embodiments of the present invention provide the application of the multilayer core-shell palladium-platinum-nickel fuel cell catalyst described in the second aspect, wherein the multilayer core-shell palladium-platinum-nickel carbon catalyst is used in the anode of the fuel cell.

[0013] The beneficial effects of the technical solution provided by the embodiments of the present invention are as follows: 1. The multilayer core-shell palladium-platinum-nickel fuel cell catalyst of the present invention can enhance the oxidation resistance of platinum, reduce the oxidation and corrosion of platinum during fuel cell operation, thereby improving the overall stability of the catalyst.

[0014] 2. By constructing a multi-layered core-shell structure, this invention effectively improves the durability of the catalyst, enabling it to maintain high activity and stability during long-term use and extending its service life.

[0015] 3. The multilayer core-shell structured palladium-platinum-nickel catalyst of the present invention has high catalytic activity. Under the same conditions, the conversion rate of the catalyst to the reactants and the selectivity of the products are improved.

[0016] 4. The multi-layered core-shell structure of the palladium-platinum-nickel fuel cell catalyst of this invention helps to improve the anti-poisoning performance of the alloy catalyst, enabling it to maintain high catalytic performance even when facing complex reaction environments.

[0017] 5. The catalyst prepared by this invention has a more uniform microstructure and a higher specific surface area, which is beneficial to increasing the contact area between the catalyst and the reactants, thereby improving the catalytic efficiency.

[0018] 6. By precisely controlling the multi-layered core and shell, this invention avoids the excessive use of precious metals, reduces the production cost of the catalyst, and facilitates the large-scale industrial application of the catalyst.

[0019] 7. The preparation method of the present invention can improve the durability and activity of the catalyst, help reduce the frequency of catalyst replacement, reduce the pressure of catalyst waste treatment, and play a positive role in environmental protection.

[0020] 8. The preparation method of the present invention is not only applicable to palladium-platinum-nickel catalysts, but can also provide a reference for the preparation of other multi-component catalysts, and has good application value. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the structure of the multilayer core-shell palladium-platinum-nickel-carbon catalyst prepared in Example 1 of the present invention.

[0022] Figure 2 These are the X-ray powder diffraction patterns of the catalyst in Comparative Example 1 and the multilayer core-shell palladium-platinum-nickel-carbon catalyst prepared in Example 5 of this invention.

[0023] Figure 3 This is a comparison of linear voltammetric scan curves of the particle durability test after 30,000 square wave cycles in the three-electrode system of the multilayer core-shell palladium-platinum-nickel-carbon catalyst prepared in Example 3 of this invention. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0025] Example 1 A method for preparing a multilayer core-shell palladium-platinum-nickel-carbon catalyst includes the following steps: (1) Ni core formation: 0.57 g of triethylenediamine nickel sulfate and 0.8 g of BTR BMC-9 mesoporous carbon material were dispersed in 80 mL of water and fully dispersed at 40 °C to form a uniform slurry. 3.1 mL of sodium hypophosphite solution with a concentration of 1 mol / L was added and the temperature was raised to 70 °C and stirred for 3 h. (2) Preparation of PtNi intermediate layer: 0.14 g dichlorodiammineplatinum was added to the slurry after stirring in step (1), and after heating to 95℃, 39 mL of ascorbic acid solution with a concentration of 1.2 mol / L was added and the reaction was carried out for 3 h. (3) Formation of PdPt outer layer: Cool down to 85℃, add 0.084g potassium tetrachloropalladium and stir evenly, then add 5.1mL of hexadecyltrimethylammonium bromide solution with a concentration of 0.05mol / L that can control the reaction rate, and stir for 24h. (4) Washing and drying: After the reaction is complete, the precipitate from the solution after the reaction in step (3) is collected, and the precipitate is repeatedly washed with deionized water. The washed precipitate is then dried in a vacuum oven at 80°C for 6 hours to obtain a multilayer core-shell palladium-platinum-nickel-carbon catalyst, such as... Figure 1 As shown.

[0026] Electrochemical performance testing conditions: Three-electrode system, electrolyte is oxygen-saturated 0.1M HClO4; rotation speed: 1600 rpm; scan rate: 10 mVs -1 The 30,000-cycle durability degradation condition involves a square wave test at 0.6V and 0.95V vs. RHE, with each voltage held for 3 seconds. One test cycle is completed in 6 seconds. The test is repeated for 10,000, 20,000, and 30,000 cycles at a sweep rate of 20mV / s for CV, and the mass activity is calculated. The test continues until 30,000 cycles are completed, using a constant temperature water bath at 25℃.

[0027] Example 2 A method for preparing a multilayer core-shell palladium-platinum-nickel-carbon catalyst includes the following steps: (1) Ni core generation: 0.12 g nickel ammonium sulfate hexahydrate and 0.76 g BTR BMC-5 mesoporous carbon support were dispersed in 76 mL of water and fully dispersed at 30 °C to form a uniform slurry. 3.8 mL of sodium bisulfite solution with a concentration of 0.4 mol / L was added and the temperature was raised to 70 °C and stirred for 1 h. (2) Preparation of PtNi intermediate layer: 0.19 g of platinum sulfate tetrahydrate was added to the slurry after stirring in step (1), and 39.5 ml of ethanol was added after heating to 95 °C. The reaction was carried out for 8 h. (3) Formation of PdPt outer layer: Cool down to 75℃, add 0.2g of palladium acetylacetone, stir evenly, then add 10.1mL of glucose solution with a concentration of 0.3mol / L that can control the reaction rate, and stir the reaction for 24h. (4) Washing and drying: After the reaction is completed, the precipitate is collected from the solution after the reaction in step (3), and the precipitate is repeatedly washed with deionized water. The washed precipitate is dried in a vacuum oven at 80°C for 6 hours to obtain a multilayer core-shell palladium-platinum-nickel-carbon catalyst.

[0028] The electrochemical testing conditions were kept the same as in Example 1.

[0029] Example 3 A method for preparing a multilayer core-shell palladium-platinum-nickel-carbon catalyst differs from Example 2 in that the reducing agent used in step (3) is a 0.3 mol / L hexadecyltrimethylammonium bromide solution, while other conditions and proportions are the same as in Example 2.

[0030] Example 4 A method for preparing a multilayer core-shell palladium-platinum-nickel-carbon catalyst differs from Example 1 in that the nickel salt used in step (1) is nickel ammonium sulfate hexahydrate, and the reducing agent used in step (2) is 1,2-propanediol. Other conditions and proportions are the same as in Example 1.

[0031] Example 5 A method for preparing a multilayer core-shell palladium-platinum-nickel-carbon catalyst differs from Example 1 in that the nickel salt used in step (1) is nickel ammonium sulfate hexahydrate, the reducing agent used in step (2) is ethanol, and the reducing agent used in step (3) is polyvinylpyrrolidone. Other conditions and proportions are the same as in Example 1.

[0032] Comparative Example 1 A method for preparing a palladium-platinum-nickel-carbon catalyst includes the following steps: (1) 0.57g of triethylenediamine nickel sulfate, 0.14g of dichlorodiammonium platinum, and 0.084g of potassium tetrachloropalladium were stirred evenly and dispersed with 0.8g of BTR BMC-9 mesoporous carbon material in 80mL of water. The mixture was fully dispersed at 30℃ to form a uniform slurry. 39mL of 1.2mol / L ascorbic acid solution and 5.1mL of 0.05mol / L hexadecyltrimethylammonium bromide solution were added. The mixture was heated to 80℃ and stirred for 20h. (2) After the reaction is completed, the precipitate is collected from the solution after the reaction in step (1), and the precipitate is repeatedly washed with deionized water. The washed precipitate is dried in a vacuum oven at 80°C for 6 hours to obtain the catalyst.

[0033] from Figure 2 It can be seen that the characteristic diffraction peaks (111), (200), and (220) of platinum and palladium in Example 5 are all shifted to the right, indicating that a multi-layered core-shell palladium-platinum-nickel catalyst structure was prepared after the reaction. However, the characteristic peaks in Comparative Example 1 did not shift, indicating that the reaction did not form a multi-layered core-shell palladium-platinum-nickel catalyst.

[0034] Figure 3 This is a comparison of linear voltammetric scan curves of the particle durability test after 30,000 square wave cycles in the three-electrode system of the multilayer core-shell palladium-platinum-nickel-carbon catalyst prepared in Example 3 of this invention.

[0035] Electrochemical performance testing conditions: Three-electrode system, electrolyte is oxygen-saturated 0.1M HClO4; rotation speed: 1600 rpm; scan rate: 10 mVs -1 The 30,000-cycle durability degradation condition involves square wave testing at 0.6V and 0.95V vs. RHE, with each voltage held for 3 seconds. A test cycle is completed in 6 seconds, and the test is performed for 10,000, 20,000, and 30,000 cycles. The CV is measured at a scan rate of 20mV / s, and the electrochemical active area is calculated. The test is continued until 30,000 cycles are completed, using a constant temperature water bath at 25℃.

[0036] from Figure 3 It can be seen that the initial electrochemical active area is 102.1 m². 2 / g, after 30,000 durability cycles, the electrochemical active surface area of ​​the catalyst is 100.4m. 2 The catalyst exhibits a low degradation rate of only 1.67% per gram, with minimal decay. The multi-layered core-shell distribution of palladium, platinum, and nickel significantly enhances the electrochemical active area of ​​the catalyst. Furthermore, after 30,000 durability cycles, the electrochemical active area shows almost no degradation, making it highly suitable for use in fuel cells and facilitating the rapid commercialization of fuel cells.

[0037] Finally, it should be noted that the above specific embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to examples, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A method for preparing a multilayer core-shell palladium-platinum-nickel fuel cell catalyst, characterized in that, Includes the following steps: (1) Ni core formation: Disperse an appropriate amount of nickel salt and carbon support in water, and fully disperse them at 30-40℃ to form a uniform slurry. Add a first reducing agent solution with a concentration of 0.4-1 mol / L. The molar ratio of the first reducing agent to Ni in the solution is 2-5. Heat to 60-70℃ and stir for 1-3 hours to form Ni cores on the support. (2) Preparation of PtNi intermediate layer: Add an appropriate amount of platinum salt to the slurry at 60-70℃ in step (1), and add a second reducing agent after heating to 90-95℃. The molar ratio of the second reducing agent to Pt is 60-1200. React for 3-8 hours. By increasing the temperature, the reduction potential of platinum ions is reduced, so that they are selectively deposited on the Ni surface to form a Pt intermediate layer. The Pt layer is relative to the Ni core, and the whole forms a PtNi core. (3) Formation of PdPt outer layer: Cool down to 75-85℃, add palladium salt and a third reducing agent solution with a concentration of 0.05-0.3mol / L that can control the reaction rate. The molar ratio of the third reducing agent to Pd in ​​the solution is 1-3. React for 8-48h to reduce palladium ions and platinum ions that were not completely reduced in step (2) to form PdPt outer layer; (4) Washing and drying: Collect the precipitate from the solution after the reaction in step (3), wash the precipitate repeatedly with deionized water, and dry the washed precipitate in a vacuum oven at 60-80℃ for 6-12h to obtain a multilayer core-shell palladium-platinum-nickel-carbon catalyst.

2. The method for preparing the multilayer core-shell palladium-platinum-nickel fuel cell catalyst according to claim 1, characterized in that, In step (1), the nickel salt is one or more of triethylenediamine nickel sulfate, nickel ammonium sulfate hexahydrate, and hexaammine nickel chloride.

3. The method for preparing the multilayer core-shell palladium-platinum-nickel fuel cell catalyst according to claim 1, characterized in that, In step (1), the carbon support is one or more of mesoporous carbon support, polymer composite porous carbon, and acetylene black; The first reducing agent is one or more of sodium hypophosphite, sodium bisulfite, and potassium borohydride.

4. The method for preparing the multilayer core-shell palladium-platinum-nickel fuel cell catalyst according to claim 1, characterized in that, In step (2), the platinum salt is one or more of diammineplatinum dichloro, potassium chloroplatinate, and platinum sulfate tetrahydrate; The second reducing agent is one or more of 1,2-propanediol, ethanol, and ascorbic acid.

5. The method for preparing the multilayer core-shell palladium-platinum-nickel fuel cell catalyst according to claim 1, characterized in that, In step (3), the temperature is lowered to 77-83℃, and palladium salt and a third reducing agent solution with a concentration of 0.05-0.3mol / L that can control the reaction rate are added. The molar ratio of the third reducing agent to Pd in ​​the solution is 1-3, and the reaction is carried out for 12-24h.

6. The method for preparing a multilayer core-shell palladium-platinum-nickel fuel cell catalyst according to claim 1 or 5, characterized in that, In step (3), the palladium salt is one or more of potassium tetrachloropalladium, dichlorodiaminepalladium, and palladium acetylacetonate; The third reducing agent is one or more of hexadecyltrimethylammonium bromide, glucose, and polyvinylpyrrolidone.

7. A multilayer core-shell palladium-platinum-nickel fuel cell catalyst, characterized in that, The multilayer core-shell palladium-platinum-nickel fuel cell catalyst is prepared by any one of the preparation methods described in claims 1-6, wherein palladium accounts for 5-7% of the mass of the catalyst, platinum accounts for 9-11% of the mass of the catalyst, and nickel accounts for 6-9% of the mass of the catalyst.

8. The application of the multilayer core-shell palladium-platinum-nickel fuel cell catalyst according to claim 7, characterized in that, The multilayer core-shell palladium-platinum-nickel-carbon catalyst is used in the anode of a fuel cell.

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