Multi-layer core-shell palladium-platinum-nickel fuel cell catalyst as well as preparation method and application thereof

Abstract

The invention provides a multilayer core-shell palladium-platinum-nickel fuel cell catalyst as well as a preparation method and application thereof. The preparation method comprises the following steps: dispersing nickel salt and a carbon carrier in water, fully dispersing to form uniform slurry, adding a first reducing agent solution, heating to 60-70 DEG C, stirring for 1-3 hours, and forming a Ni core on the carrier; adding platinum salt into the slurry, heating to 90-95 DEG C, adding a second reducing agent, and reacting for 3-8 hours to integrally form a PtNi core; cooling to 75-85 DEG C, adding palladium salt and a third reducing agent solution, and reacting for 8-48 hours to form a PdPt outer layer; and collecting the precipitate of the reacted solution, repeatedly washing the precipitate with deionized water, and drying the washed precipitate to obtain the multilayer core-shell palladium platinum nickel carbon catalyst. According to the catalyst, the durability is remarkably improved while the high activity is maintained, and the service life and the reliability of the fuel cell are greatly improved while the efficient energy conversion of the catalyst is maintained.

Description

Technical Field

[0001] The present invention relates to the technical field of catalyst materials, and in particular to a multilayer core-shell palladium-platinum-nickel fuel cell catalyst and a preparation method and application thereof. Background Art

[0002] Fuel cells, as a clean energy conversion technology, are significantly impacted by the performance of their catalysts for commercialization. Currently, platinum-based catalysts are widely used in fuel cells due to their high activity, particularly platinum-nickel catalysts, which offer advantages over pure platinum catalysts in terms of increased activity and lower costs. However, existing platinum-nickel catalysts still face challenges with the durability of fuel cells during long-term operation. This is primarily due to structural changes and loss of active sites during the reaction, leading to degradation in cell performance.

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

[0004] The present invention aims to overcome the shortcomings of the prior art by providing a multilayer core-shell palladium-platinum-nickel fuel cell catalyst, its preparation method, and its application. Compared with the platinum-nickel catalysts currently used on the market, the catalyst of the present invention significantly improves durability while maintaining high activity, resolving the problem of alloy catalyst failure in the prior art. While maintaining efficient energy conversion, the catalyst significantly improves the lifespan and reliability of the fuel cell. Furthermore, the preparation method of the present 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 embodiment of the present invention is: In a first aspect, an embodiment of the present invention provides a method for preparing a multilayer core-shell palladium platinum nickel fuel cell catalyst, comprising the following steps: (1) Ni nucleation: Disperse an appropriate amount of nickel salt and carbon support in water, fully disperse at 30-40°C to form a uniform slurry, add a first reducing agent solution with a concentration of 0.4-1 mol / L, and the molar ratio of the first reducing agent to Ni in the solution is 2-5. Heat to 60-70°C and stir for 1-3 hours to form Ni nuclei on the support; (2) Preparation of PtNi intermediate layer: add an appropriate amount of platinum salt to the 60-70°C slurry of step (1), heat it to 90-95°C, add a second reducing agent, the molar ratio of the second reducing agent to Pt is 60-1200, react for 3-8h, and use the temperature increase to reduce the reduction potential of platinum ions 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 the PdPt outer layer: cooling to 75-85°C, adding a palladium salt and a third reducing agent solution with a concentration of 0.05-0.3 mol / L that can control the reaction rate, wherein the molar ratio of the third reducing agent to Pd in ​​the solution is 1-3, and reacting for 8-48 hours to reduce the palladium ions and the platinum ions that were not completely reduced in step (2) to form a PdPt outer layer; (4) Washing and drying: Collect the precipitate from the solution after the reaction in step (3), repeatedly wash the precipitate with deionized water, and dry the washed precipitate in a vacuum oven at 60-80°C for 6-12 hours to obtain a multilayer core-shell palladium platinum nickel carbon catalyst.

[0006] Furthermore, 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 a mesoporous carbon support, a 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 diammine dichloroplatinum, potassium chloroplatinate and platinum sulfate tetrahydrate; The second reducing agent is one or more of 1,2-propylene glycol, ethanol and ascorbic acid.

[0009] Furthermore, in step (3), the temperature is lowered to 77-83°C, and a palladium salt and a third reducing agent solution with a concentration of 0.05-0.3 mol / 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 12-24 hours.

[0010] Furthermore, in step (3), the palladium salt is one or more of potassium tetrachloropalladate, dichlorodiamminepalladium and palladium acetylacetonate; The third reducing agent is one or more of cetyltrimethylammonium bromide, glucose and polyvinylpyrrolidone.

[0011] In the second aspect, an embodiment of the present invention provides a multi-layer core-shell palladium-platinum-nickel fuel cell catalyst, which is prepared by the preparation method described in the first aspect. The mass proportion of palladium in the multi-layer core-shell palladium-platinum-nickel carbon fuel cell catalyst is 5-7%, the mass proportion of platinum in the catalyst is 9-11%, and the mass proportion of nickel in the catalyst is 6-9%.

[0012] In a third aspect, an embodiment of the present invention provides an application of the multi-layer core-shell palladium platinum nickel fuel cell catalyst described in the second aspect, wherein the multi-layer core-shell palladium platinum nickel carbon catalyst is applied to the anode of a fuel cell.

[0013] The technical solution provided by the embodiment of the present invention has the following beneficial effects: 1. The multilayer core-shell palladium platinum nickel fuel cell catalyst of the present invention can enhance the antioxidant capacity of platinum, reduce the oxidation and corrosion of platinum during the operation of the fuel cell, and thus improve the overall stability of the catalyst.

[0014] 2. The present invention effectively improves the durability of the catalyst by constructing a multi-layer core-shell structure, so that the catalyst can still maintain high activity and stability during long-term use, thereby extending the service life of the catalyst.

[0015] 3. The multi-layer 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-layer core-shell structure of the palladium-platinum-nickel fuel cell catalyst of the present invention helps to improve the anti-poisoning performance of the alloy catalyst, so that it can still maintain a high catalytic performance when facing a complex reaction environment.

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

[0018] 6. The present invention avoids excessive use of precious metals by precisely controlling the multi-layer core-shell, reduces the production cost of the catalyst, and is conducive to 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 have a positive effect on environmental protection.

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

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

[0022] Figure 2 It is the X-ray powder diffraction pattern of the catalyst of comparative example 1 of the present invention and the multilayer core-shell palladium platinum nickel carbon catalyst prepared in Example 5.

[0023] Figure 3 This is a comparison chart of linear voltammetric scanning curves of the particle durability test after 30,000 square wave cycles of the multi-layer core-shell palladium platinum nickel carbon catalyst prepared in Example 3 of the present invention under the three-electrode system. DETAILED DESCRIPTION

[0024] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present 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 only used to explain the present invention and are not intended to limit the present invention.

[0025] Example 1 A method for preparing a multilayer core-shell palladium platinum nickel carbon catalyst comprises the following steps: (1) Ni nucleation: 0.57 g of nickel triethylenediamine sulfate and 0.8 g of BMC-9 mesoporous carbon material were dispersed in 80 mL of water, fully dispersed at 40 °C to form a uniform slurry, 3.1 mL of 1 mol / L sodium hypophosphite solution was added, and the mixture was heated to 70 °C and stirred for 3 h. (2) Preparation of PtNi intermediate layer: 0.14 g of dichlorodiammineplatinum was added to the stirred slurry of step (1), and after heating to 95°C, 39 mL of 1.2 mol / L ascorbic acid solution was added and the mixture was reacted for 3 h. (3) Formation of the PdPt outer layer: Cool to 85°C, add 0.084 g of potassium tetrachloropalladate and stir evenly, then add 5.1 mL of 0.05 mol / L hexadecyltrimethylammonium bromide solution to control the reaction rate, and stir for 24 h. (4) Washing and drying: After the reaction is completed, the solution after the reaction in step (3) is collected and precipitated, 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, such as Figure 1 shown.

[0026] Electrochemical performance test conditions: three-electrode system, electrolyte is oxygen-saturated 0.1M HClO4; rotation speed: 1600 rpm; scan rate: 10 mVs -1 The 30,000 endurance attenuation condition is to conduct a square wave test at 0.6 V and 0.95 V vs. RHE, respectively. The two test voltages are kept for 3 seconds, and a test cycle is completed in 6 seconds. The 10,000, 20,000, and 30,000 cycles are scanned with a CV scan rate of 20 mV / s, and the mass activity is calculated until 30,000 cycles. The temperature is kept in a constant water bath at 25°C.

[0027] Example 2 A method for preparing a multilayer core-shell palladium platinum nickel carbon catalyst comprises the following steps: (1) Ni nucleation: 0.12 g of nickel ammonium sulfate hexahydrate and 0.76 g of 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 0.4 mol / L sodium bisulfite solution was added and the mixture was heated 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 stirred slurry of step (1), and the temperature was raised to 95°C, followed by addition of 39.5 ml of ethanol and the reaction was continued for 8 h. (3) Formation of the PdPt outer layer: Cool to 75°C, add 0.2 g of palladium acetylacetonate, stir evenly, then add 10.1 mL of 0.3 mol / L glucose solution that can control the reaction rate, and stir for 24 h. (4) Washing and drying: After the reaction is completed, the solution after the reaction in step (3) is collected and precipitated, 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 test conditions were the same as those in Example 1.

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

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

[0031] Example 5 A method for preparing a multilayer core-shell palladium platinum nickel-carbon catalyst is different from that of 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 polyvinyl pyrrolidone. Other conditions and proportions are the same as those in Example 1.

[0032] Comparative Example 1 A method for preparing a palladium-platinum-nickel-carbon catalyst comprises the following steps: (1) 0.57 g of triethylenediamine nickel sulfate, 0.14 g of dichlorodiammineplatinum, and 0.084 g of potassium tetrachloropalladate were uniformly dispersed with 0.8 g of BMC-9 mesoporous carbon material in 80 mL of water, and fully dispersed at 30 ° C to form a uniform slurry. 39 mL of 1.2 mol / L ascorbic acid solution and 5.1 mL of 0.05 mol / L hexadecyltrimethylammonium bromide solution were added, and the mixture was heated to 80 ° C and stirred for 20 h. (2) After the reaction is completed, the solution after the reaction in step (1) is collected to obtain a precipitate, and the precipitate is repeatedly washed with deionized water. The washed precipitate is dried in a vacuum oven at 80° C. for 6 h to obtain a 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-layer core-shell palladium-platinum-nickel catalyst structure is prepared after the reaction. However, the characteristic peaks in Comparative Example 1 do not shift, indicating that the reaction does not form a multi-layer core-shell palladium-platinum-nickel catalyst.

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

[0035] Electrochemical performance test conditions: three-electrode system, electrolyte is oxygen-saturated 0.1M HClO4; rotation speed: 1600 rpm; scan rate: 10 mVs -1 The 30,000 endurance attenuation condition is to conduct a square wave test at 0.6 V and 0.95 V vs. RHE, respectively. The two test voltages are kept for 3 seconds, and a test cycle is completed in 6 seconds. The CV scan rate is 20 mV / s for 10,000, 20,000, and 30,000 cycles, and the electrochemical active area is calculated until 30,000 cycles. The temperature is kept in a constant water bath at 25°C.

[0036] from Figure 3 It can be seen that the initial electrochemical active area is 102.1m 2 / g, after 30,000 cycles of endurance cycling, the electrochemical active area of ​​the catalyst is 100.4 m 2 / g, with a decay rate of only 1.67%, which is very small. The distribution of palladium, platinum and nickel elements in the multi-layer core-shell significantly increases the electrochemical active area of ​​the catalyst. After 30,000 cycles of endurance cycling, the electrochemical active area has almost no decay, making it very suitable for application in fuel cells and conducive to the rapid promotion of fuel cell commercialization.

[0037] Finally, it should be noted that the above specific implementation methods are only used to illustrate the technical solutions of the present invention and are not limiting. Although the present invention has been described in detail with reference to examples, those skilled in the art should understand that the technical solutions of the present invention can be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in 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: The following steps are involved: (1) Ni nucleation: Disperse an appropriate amount of nickel salt and carbon support in water, fully disperse at 30-40°C to form a uniform slurry, add a first reducing agent solution with a concentration of 0.4-1 mol / L, and the molar ratio of the first reducing agent to Ni in the solution is 2-5. Heat to 60-70°C and stir for 1-3 hours to form Ni nuclei on the support; (2) Preparation of PtNi intermediate layer: add an appropriate amount of platinum salt to the 60-70°C slurry of step (1), heat it to 90-95°C, add a second reducing agent, the molar ratio of the second reducing agent to Pt is 60-1200, react for 3-8h, and use the temperature increase to reduce the reduction potential of platinum ions 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 the PdPt outer layer: cooling to 75-85°C, adding a palladium salt and a third reducing agent solution with a concentration of 0.05-0.3 mol / L that can control the reaction rate, wherein the molar ratio of the third reducing agent to Pd in ​​the solution is 1-3, and reacting for 8-48 hours to reduce the palladium ions and the platinum ions that were not completely reduced in step (2) to form a PdPt outer layer; (4) Washing and drying: Collect the precipitate from the solution after the reaction in step (3), repeatedly wash the precipitate with deionized water, and dry the washed precipitate in a vacuum oven at 60-80°C for 6-12 hours to obtain a multilayer core-shell palladium platinum nickel carbon catalyst.

2. The method for preparing a 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 a multilayer core-shell palladium platinum nickel fuel cell catalyst according to claim 1, wherein: In step (1), the carbon support is one or more of a mesoporous carbon support, a 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 a 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 diammine dichloroplatinum, potassium chloroplatinate and platinum sulfate tetrahydrate; The second reducing agent is one or more of 1,2-propylene glycol, ethanol and ascorbic acid.

5. The method for preparing a 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°C, and a palladium salt and a third reducing agent solution with a concentration of 0.05-0.3 mol / 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 12-24 hours.

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 tetrachloropalladate, dichlorodiamminepalladium and acetylacetonate palladium; The third reducing agent is one or more of cetyltrimethylammonium 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-carbon fuel cell catalyst is prepared by the preparation method according to any one of claims 1 to 6, wherein the mass proportion of palladium in the catalyst is 5-7%, the mass proportion of platinum in the catalyst is 9-11%, and the mass proportion of nickel in the catalyst is 6-9%.

8. The use 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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