Preparation method of noble metal modified Pt fuel cell cathode catalyst
By modifying the precious metal palladium or rhodium on the surface of the cathode catalyst of the Pt fuel cell, the problem of catalysts being easily corroded and transition metal dissolution under high potential conditions is solved, and the durability and performance of the catalyst are significantly improved.
Patent Information
- Application Number
- CN202510276464.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-03-10
- Publication Date
- 2025-06-06
AI Technical Summary
The existing Pt-based fuel cell cathode catalysts are prone to corrosion under high potential conditions, and the dissolution of transition metals such as Co accelerates under operating conditions, resulting in a decrease in catalytic activity and a decrease in proton conductivity, affecting the durability and performance of fuel cells.
The surface of the Pt fuel cell cathode catalyst is uniformly modified by precious metal palladium or rhodium. Through three steps of platinum carbon precursor preparation, transition metal doping and precious metal modification, a stable precious metal modification Pt catalyst is formed.
It significantly improves the durability and performance of the catalyst, inhibits the dissolution and defect diffusion of transition metals, improves the energy barrier of surface platinum atoms, and ensures the stability of the catalyst under long-term conditions.
Smart Images
Figure CN120109211A_ABST
Abstract
Description
Technical Field
[0001] The invention belongs to the technical field of fuel cells, and in particular relates to a method for preparing a noble metal-modified Pt fuel cell cathode catalyst. Background Art
[0002] The high efficiency and environmental protection of proton exchange membrane fuel cells (PEMFC) have attracted great interest from academia and industry, and therefore play an important role in sustainable future energy systems. It is worth noting that the slow kinetics of the cathode oxygen reduction reaction (ORR) leads to an increase in the use of platinum-based catalysts, and the harsh operating conditions aggravate the corrosion of the catalyst in the high potential range of the battery. Therefore, the development of efficient and stable platinum-based catalysts is crucial for practical applications.
[0003] In recent years, alloying Pt with 3d transition metals such as Co has been shown to be an effective way to improve the activity of cathode catalysts and reduce the cost of Pt, mainly due to the ligand effect and strain effect. However, transition metals such as Co are more soluble under PEMFC operating conditions due to their low dissolution potential. The leaching of non-Pt elements can weaken or eliminate the ligand and strain effects, resulting in a decrease in the catalytic activity of the catalyst. Specifically, the presence of Co on the alloy surface accelerates the oxidation behavior of Pt at high potentials, thereby accelerating the decay of the catalyst. In addition, the leaching of cations can reduce the proton conductivity by exchanging protons with ionic polymers in the proton exchange membrane and the catalyst layer. This contamination significantly increases the proton conduction resistance and seriously affects the performance of the fuel cell. Therefore, it becomes challenging to prevent the reduction of the number of non-Pt components in the alloy with the increase of the number of electrochemical cycles. In current research, various approaches have been adopted, such as the use of ordered or high entropy alloys, coating strategies, multi-component doping, and surface doping. Unfortunately, nanocrystalline materials are prone to defects in the bulk phase and diffusion to the surface, which leads to the accelerated dissolution of transition metal atoms. Therefore, the challenge of designing a Pt alloy catalyst that can suppress defect diffusion and transition metal dissolution while improving catalyst durability remains. Summary of the invention
[0004] The purpose of the present invention is to overcome the shortcomings of the prior art and provide a method for preparing a noble metal-modified Pt fuel cell cathode catalyst. The catalyst prepared by the present invention uses noble metal palladium or rhodium to uniformly modify the catalyst surface, so that the durability of the catalyst is greatly improved, and the performance and durability of the catalyst are significantly improved when used in a fuel cell.
[0005] In order to achieve the above technical objectives, the technical solution adopted by the embodiment of the present invention is: A method for preparing a noble metal-modified Pt fuel cell cathode catalyst comprises the following steps: (1) Preparation of platinum-carbon precursor: Disperse 1-20 g of carbon powder in 1-30 L of organic solvent, ultrasonicate for 20-60 min, add a platinum source of the same mass as the carbon powder, continue ultrasonicating for 20-60 min and stirring for 5-120 min to form a uniform solution, heat in an oil bath at 120-180 ° C with stirring for 4-24 h, filter the heated solution after washing, and dry at 60-90 ° C to obtain a platinum-carbon precursor; (2) Transition metal doping process: add the platinum-carbon precursor obtained in step (1) and 0.5-10 g of cobalt source into 2-30 L of water, add alkaline substance to adjust the pH of the solution to 7-11, emulsify and disperse for 15-60 min, stir at 10-30 ° C for 4-24 h, filter the stirred solution, dry at 50-90 ° C for 10-24 h to obtain a solid powder, and calcine the dried powder at 600-800 ° C for 60-120 min in a protective atmosphere to obtain a platinum-cobalt catalyst; (3) Surface modification with precious metals: the platinum-cobalt catalyst obtained in step (2) and an equal mass of a palladium source and / or a rhodium source are added to 1-30 L of ultrapure water, 0.1-4 g of a chelating agent is added, the mixture is stirred at 0-60° C. for 2-24 h, ultrasonicated for 10-30 min, 1-20 g of a reducing agent is added, the mixture is heated at 10-50° C. for 4-24 h, the heated solution is filtered and washed, and then dried at 50-90° C. to obtain a precious metal-modified Pt fuel cell cathode catalyst.
[0006] Furthermore, the organic solvent in step (1) is one or more of xylene, methanol, ethanol and formic acid, and the platinum source is one or more of platinum nitrate, chloroplatinic acid hexahydrate, platinum dichloride and dinitrosodiammineplatinum.
[0007] Furthermore, the cobalt source in step (2) is one or more of cobalt chloride, cobalt acetate, cobalt sulfate and cobalt nitrate; The alkaline substance is one or more of ammonia water, potassium hydroxide, sodium hydroxide, sodium carbonate and tris(hydroxymethyl)aminomethane; The protective atmosphere is one or more of argon, helium and nitrogen, with a purity of ≥99.99%.
[0008] Furthermore, the palladium source in step (3) is one or more of palladium nitrate, palladium chloride and palladium sulfate, with a purity of ≥98%; The rhodium source is one or more of rhodium chloride, rhodium sulfate and rhodium phosphate, and the purity is ≥98%.
[0009] Furthermore, the chelating agent in step (3) is one or more of dopamine, ethylenediaminetetraacetic acid and dimethylaminocarboxylic acid, and has a purity of ≥99%.
[0010] Furthermore, the reducing agent in step (3) is one or more of sodium borohydride, ascorbic acid, formic acid, sodium formate and hydrazine hydrate.
[0011] The technical solution provided by the embodiment of the present invention has the following beneficial effects: 1. The method for preparing the noble metal-modified Pt fuel cell cathode catalyst of the present invention has low noble metal modification cost, simple preparation process and easy scale-up production.
[0012] 2. The noble metal-modified Pt fuel cell cathode catalyst of the present invention can significantly improve the durability of the catalyst, and the actual life of the catalyst in the fuel cell is further increased.
[0013] 3. The preparation method of the present invention stably and uniformly modifies the precious metal on the surface of the nano-platinum particles, which can increase the migration energy barrier of the surface platinum atoms and inhibit the dissolution of the transition metal, thereby ensuring its stability under long-term conditions.
[0014] 4. The precious metal-modified Pt catalyst prepared by the preparation method of the present invention is used in fuel cells, which can greatly improve the durability and battery performance. BRIEF DESCRIPTION OF THE DRAWINGS
[0015] Figure 1 It is a half-cell linear voltammetric curve diagram of the noble metal modified Pt fuel cell cathode catalyst prepared in Example 1 of the present invention and the catalyst of Comparative Example 1.
[0016] Figure 2 It is a comparison diagram of the cyclic voltammetry curves of the catalysts prepared in Example 2 of the present invention and Comparative Example 1.
[0017] Figure 3 It is a comparison diagram of polarization curves of fuel cell single cells made with catalysts in Example 3 of the present invention and Comparative Example 1.
[0018] Figure 4 It is a before and after curve diagram of the half-cell durability of the catalyst prepared in Example 4 of the present invention.
[0019] Figure 5 It is a before and after curve diagram of the half-cell durability of the catalyst prepared in Comparative Example 1 of the present invention.
[0020] Figure 6 It is a comparison diagram of polarization curves of the catalyst of the fuel cell single cell carrier prepared in Example 5 of the present invention before and after the durability.
[0021] Figure 7 It is a comparison diagram of polarization curves of the catalyst of the fuel cell single cell carrier prepared in Comparative Example 1 of the present invention before and after the durability. DETAILED DESCRIPTION
[0022] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with 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 used to limit the present invention.
[0023] Example 1 A method for preparing a noble metal-modified Pt fuel cell cathode catalyst comprises the following steps: (1) Preparation of platinum-carbon precursor: 1 g of carbon powder (Cabot BP2000) was dispersed in 1 L of ethanol, and ultrasonicated for 20 min. 1 g of platinum nitrate was added, and ultrasonicated for 20 min and stirred for 5 min to form a uniform solution. The solution was stirred in an oil bath at 120 °C for 4 h. The heated solution was filtered and washed, and dried at 60 °C to obtain a platinum-carbon precursor. (2) Transition metal doping process: 2 g of the platinum-carbon precursor obtained in step (1) and 0.5 g of cobalt acetate were added to 2 L of water, 1 g of potassium hydroxide was added to adjust the pH of the solution to 7, emulsified and dispersed for 15 min, stirred at 10 ° C for 4 h, the stirred solution was filtered, and dried at 50 ° C for 10 h to obtain a solid powder. The dried powder was calcined at 600 ° C for 60 min in a protective atmosphere to obtain a platinum-cobalt catalyst; (3) Surface modification with precious metals: 2 g of the platinum-cobalt catalyst obtained in step (2) and 2 g of palladium nitrate were added to 1 L of ultrapure water, and 0.1 g of ethylenediaminetetraacetic acid was added. The mixture was stirred at 0°C for 2 h, and then ultrasonicated for 10 min. 1 g of sodium borohydride was added and the mixture was heated at 10°C for 4 h. The heated solution was filtered and washed, and then dried at 50°C to obtain a Pt fuel cell cathode catalyst modified with precious metal palladium.
[0024] Preparation of fuel cell single cell: accurately weigh 200 mg of the nitrogen-doped porous carbon-loaded Pt fuel cell cathode catalyst prepared above; measure 20 mL of pure water, 15 mL of isopropanol and 1.5 mL of perfluorosulfonic acid resin solution, add them to the catalyst, crush the cells for 30 minutes, form a uniform catalyst ink, and evenly coat the ink on the cut proton exchange membrane, which is recorded as the cathode; weigh the platinum carbon catalyst (Jornal Matthey, 50wt% Pt / C) in the same way, and coat it on the other side of the above membrane, which is recorded as the anode to form CCM; the gas diffusion layer uses SGL 28BC model GDL. Disassemble the balticFuelCells QCF25 quick assembly test fixture, put in the thickness limit sheet, the first GDL, CCM, and the second GDL in turn, fix them, and rotate the pneumatic button to complete the clamping. After connecting the gas pipeline, perform the air tightness test and pass it before performing the single cell test.
[0025] Single cell test conditions: single cell area 25cm 2The stoichiometric ratio of anode to cathode is 1.5:2.5, the anode dew point is set to 64°C, the cathode dew point is 64°C, the anode stack pressure is 1.1 bar, the cathode stack pressure is 1.0 bar, and the battery test temperature is 80°C.
[0026] Example 2 A method for preparing a noble metal-modified Pt fuel cell cathode catalyst comprises the following steps: (1) Preparation of platinum-carbon precursor: 20 g of carbon powder (Cabot BP2000) was dispersed in 30 L of ethanol, and ultrasonicated for 60 min. 20 g of platinum nitrate was added, and ultrasonicated for 60 min and stirred for 120 min to form a uniform solution. The solution was heated in an oil bath at 180 °C with stirring for 24 h. The heated solution was filtered and washed, and dried at 90 °C to obtain a platinum-carbon precursor. (2) Transition metal doping process: 40 g of the platinum-carbon precursor and 10 g of cobalt acetate obtained in step (1) were added to 30 L of water, 20 g of potassium hydroxide was added to adjust the pH of the solution to 11, emulsified and dispersed for 60 min, stirred at 30 ° C for 24 h, the stirred solution was filtered, and dried at 90 ° C for 24 h to obtain a solid powder. The dried powder was calcined at 800 ° C for 120 min in a protective atmosphere to obtain a platinum-cobalt catalyst; (3) Surface modification with precious metals: 40 g of the platinum-cobalt catalyst and 40 g of rhodium sulfate obtained in step (2) were added to 30 L of ultrapure water, and 4 g of ethylenediaminetetraacetic acid was added. The mixture was stirred at 60° C. for 24 h, and then ultrasonicated for 30 min. 20 g of sodium borohydride was added, and the mixture was heated at 50° C. for 24 h. The heated solution was filtered and washed, and then dried at 90° C. to obtain a Pt fuel cell cathode catalyst modified with precious metal rhodium.
[0027] The preparation and testing conditions of a single cell using the noble metal-modified Pt fuel cell cathode catalyst prepared in this example are the same as those in Example 1.
[0028] Example 3 This embodiment provides a noble metal-modified Pt fuel cell cathode catalyst. The difference between this embodiment and embodiment 1 is that 10 g of potassium hydroxide is added in step (2), the pH of the solution is adjusted to 8, the emulsification dispersion is performed for 40 minutes, and the mixture is stirred at 20° C. for 20 hours. The other steps are the same as those in embodiment 1. The single cell preparation and test conditions of the noble metal-modified Pt fuel cell cathode catalyst prepared in this embodiment are the same as those in embodiment 1.
[0029] Example 4 This embodiment provides a noble metal-modified Pt fuel cell cathode catalyst. The difference between this embodiment and embodiment 2 is that the chelating agent added in step (3) is dopamine, the amount of which is 3 g, and after stirring at 40° C. for 15 h, ultrasonic treatment is performed for 20 min, 15 g of formic acid is added, and heating is performed at 40° C. for 20 h. The other steps are the same as those in embodiment 2. The single cell preparation and testing conditions of the noble metal-modified Pt fuel cell cathode catalyst prepared in this embodiment are the same as those in embodiment 1.
[0030] Example 5 This embodiment provides a noble metal-modified Pt fuel cell cathode catalyst. The difference between this embodiment and embodiment 1 is that in step (1), 15 g of carbon powder (Cabot BP2000) is dispersed in 20 L of xylene, ultrasonicated for 50 min, hexahydrated chloroplatinic acid of the same mass as the carbon powder is added, ultrasonicated for 50 min and stirred for 110 min to form a uniform solution, stirred at 170° C. in an oil bath for 22 h, the solution after heating treatment is filtered and washed, and dried at 80° C. to obtain a platinum-carbon precursor, and the other steps are the same as those in embodiment 1. The single cell preparation and test conditions of the noble metal-modified Pt fuel cell cathode catalyst prepared by this embodiment are the same as those in embodiment 1.
[0031] Comparative Example 1 This comparative example provides a platinum-carbon catalyst. The difference between this comparative example and Example 1 is that the precious metal modification step (3) is not performed, and other proportions and conditions are the same as those in Example 1.
[0032] The protective atmosphere in step (2) of Examples 1-5 and Comparative Example 1 is nitrogen with a purity of ≥99.99%, the purity of the palladium source and the rhodium source is 98%, and the purity of the chelating agent is 99%.
[0033] from Figure 1 It can be seen that the oxygen reduction half-wave potential of the catalyst prepared in Example 1 is 0.917 V, and the mass activity is 0.2420 A / mg Pt. The oxygen reduction half-wave potential of the catalyst prepared in Comparative Example 1 is 0.904 V, and the mass activity is 0.1364 A / mg Pt. The oxygen reduction half-wave potential and mass activity of Example 1 are significantly greater than those of Comparative Example 1.
[0034] from Figure 2 It can be seen that the peak area of the cyclic voltammetry curve of the catalyst prepared in Example 2 is significantly larger than that of the catalyst prepared in Comparative Example 1, and the electrochemical active areas calculated therefrom are 30.06 m 2 / g Pt and 26.78m 2 / g Pt, a larger electrochemical active area means a larger effective area for electrochemical reaction on the catalyst surface, and an increase in the effective active area is conducive to the activity.
[0035] from Figure 3 It can be seen from the polarization curve of the fuel cell single cell that the current density of the catalyst prepared in Example 3 at the same voltage is higher than that of the comparative example 1, indicating that the preparation method of the present invention modifies the surface of the Pt fuel cell cathode catalyst with precious metals to improve the performance of the catalyst single cell to a certain extent.
[0036] from Figure 4 It can be seen that the linear voltammetric curve of the catalyst prepared in Example 4 has almost no change after 30,000 cycles of electrochemical catalyst durability, indicating that the durability of the catalyst modified with precious metals has been greatly improved. Figure 5 The mass activity calculated from the catalyst curve prepared in Comparative Example 1 decayed from 0.1364 A / mg Pt to 0.0762 A / mg Pt, a decay of 44%. The decay amplitude is large, indicating that the half-cell durability of the catalyst prepared by the present invention is significantly better than that of the comparative sample not modified with precious metals.
[0037] from Figure 6 It can be seen that the catalyst prepared in Example 5 of the present invention has almost no attenuation in the battery performance curve after 30,000 cycles of carrier durability of a single cell, showing excellent catalyst battery durability. Figure 7 After 30,000 cycles of carrier durability in a single cell, the current density corresponding to each voltage of the catalyst prepared in Comparative Example 1 showed a significant attenuation, indicating that the catalyst prepared in the present invention has excellent single cell catalyst durability.
[0038] Finally, it should be noted that the above specific implementation methods are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to examples, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the spirit and scope of the technical solution of the present invention, which should be included in the scope of the claims of the present invention.
Claims
1. A method for preparing a noble metal-modified Pt fuel cell cathode catalyst, characterized in that: The following steps are involved: (1) Preparation of platinum-carbon precursor: Disperse 1-20 g of carbon powder in 1-30 L of organic solvent, ultrasonicate for 20-60 min, add a platinum source of the same mass as the carbon powder, continue ultrasonicating for 20-60 min and stirring for 5-120 min to form a uniform solution, heat in an oil bath at 120-180 °C with stirring for 4-24 h, filter the heated solution after washing, and dry at 60-90 °C to obtain a platinum-carbon precursor; (2) Transition metal doping process: add the platinum-carbon precursor obtained in step (1) and 0.5-10 g of cobalt source into 2-30 L of water, add alkaline substance to adjust the pH of the solution to 7-11, emulsify and disperse for 15-60 min, stir at 10-30 ° C for 4-24 h, filter the stirred solution, dry at 50-90 ° C for 10-24 h to obtain a solid powder, and calcine the dried powder at 600-800 ° C for 60-120 min in a protective atmosphere to obtain a platinum-cobalt catalyst; (3) Surface modification with precious metals: the platinum-cobalt catalyst obtained in step (2) and an equal mass of palladium source and / or rhodium source are added to 1-30 L of ultrapure water, 0.1-4 g of a chelating agent is added, and the mixture is stirred at 0-60° C. for 2-24 h, ultrasonicated for 10-30 min, 1-20 g of a reducing agent is added, and the mixture is heated at 10-50° C. for 4-24 h. The heated solution is filtered and washed, and then dried at 50-90° C. to obtain a precious metal-modified Pt fuel cell cathode catalyst.
2. The method for preparing a noble metal-modified Pt fuel cell cathode catalyst according to claim 1, characterized in that: The organic solvent described in step (1) is one or more of xylene, methanol, ethanol and formic acid, and the platinum source is one or more of platinum nitrate, chloroplatinic acid hexahydrate, platinum dichloride and dinitrosodiammineplatinum.
3. The method for preparing a noble metal-modified Pt fuel cell cathode catalyst according to claim 1, characterized in that: The cobalt source in step (2) is one or more of cobalt chloride, cobalt acetate, cobalt sulfate and cobalt nitrate; The alkaline substance is one or more of ammonia water, potassium hydroxide, sodium hydroxide, sodium carbonate and tris(hydroxymethyl)aminomethane; The protective atmosphere is one or more of argon, helium and nitrogen, with a purity of ≥99.99%.
4. The method for preparing a noble metal-modified Pt fuel cell cathode catalyst according to claim 1, characterized in that: The palladium source in step (3) is one or more of palladium nitrate, palladium chloride and palladium sulfate, with a purity of ≥98%; The rhodium source is one or more of rhodium chloride, rhodium sulfate and rhodium phosphate, and the purity is ≥98%.
5. The method for preparing a noble metal-modified Pt fuel cell cathode catalyst according to claim 1, characterized in that: The chelating agent in step (3) is one or more of dopamine, ethylenediaminetetraacetic acid and dimethylaminocarboxylic acid, with a purity of ≥99%.
6. The method for preparing a noble metal-modified Pt fuel cell cathode catalyst according to claim 1, characterized in that: The reducing agent in step (3) is one or more of sodium borohydride, ascorbic acid, formic acid, sodium formate and hydrazine hydrate.