Platinum-cerium alloy catalyst as well as preparation method and application thereof

Abstract

The invention discloses a preparation method of a platinum-cerium alloy catalyst. The preparation method comprises the following steps: dissolving platinum precursor salt and cerium precursor salt in deionized water to obtain a solution A; dispersing carbon powder in ethylene glycol or an ethylene glycol aqueous solution to obtain a solution B; the solution A and the solution B are mixed and stirred for 1-3 h, the pH is adjusted to be alkaline through alkali liquor, stirring is conducted for 0.5-2 h, a surfactant is added, stirring is conducted for 2-4 h, and a mixed solution C is obtained; and placing the mixed solution C in a microwave reactor, and carrying out microwave start / stop for 5-10 cycles to obtain the platinum-cerium alloy catalyst. The alloy catalyst is prepared by adopting co-precipitation and microwave-assisted reaction, the production process is simplified, the production cycle and cost are greatly reduced, meanwhile, compared with an existing alloy catalyst product, the alloy catalyst has the advantages of small particle size, narrow distribution range, uniform dispersion of metal components in particles and the like, the performance of the catalyst can be better exerted, and the service life of the catalyst is prolonged. The method is suitable for industrial batch production.

Description

Technical Field

[0001] The present invention relates to the technical field of catalysts, and in particular to a platinum-cerium alloy catalyst and a preparation method and application thereof. Background Art

[0002] A hydrogen fuel cell is a highly efficient and clean power generation device that only requires hydrogen and air to undergo oxidation and reduction reactions respectively to produce water to generate electricity. It has the advantages of low noise, no pollution, and high energy conversion efficiency, and is widely used.

[0003] Fuel cell catalysts are the site of the hydrogen and oxygen reaction. Hydrogen is introduced into the anode for oxidation, while oxygen is introduced into the cathode for reduction. During the oxygen reduction process on the cathode side, the intrinsic properties of the catalyst often lead to the production of free radical intermediates. These free radicals, combined with metal ions, can corrode and decompose the perfluorosulfonic acid proton membrane and catalyst support, ultimately impacting the lifespan of the catalyst and membrane electrode.

[0004] At present, in order to improve the performance of catalysts, researchers have tried to manufacture platinum-based transition metal alloy catalysts (such as platinum-cobalt alloys, platinum-nickel alloys, etc.). However, the transition metal ions and free radicals therein will aggravate the corrosion and decomposition of the proton membrane and catalyst carrier, resulting in poor durability of the catalyst and membrane electrode. Researchers have also introduced cerium elements into platinum-carbon catalysts, which not only improves the performance of the catalyst, but also quenches the generated free radicals, reduces the impact of free radicals, and improves the durability of the catalyst and membrane electrode. Among them, the preparation process of alloy catalysts mostly adopts a step-by-step loading process, and the catalyst is prepared by high-temperature alloying treatment. This process is relatively complicated, the prepared catalyst has uneven particle size distribution, poor product consistency, and is not conducive to scale-up production.

[0005] Therefore, a simple and easy method for manufacturing fuel cell alloy catalysts is needed to achieve the goal of mass production of alloy catalysts. Summary of the Invention

[0006] In response to the deficiencies in the prior art, the present invention provides a method for preparing a platinum-cerium alloy catalyst. The alloy catalyst is prepared by co-precipitation and microwave-assisted reaction, and the high-temperature alloying treatment process is abandoned, thereby simplifying the production process and greatly reducing the production cycle and cost. At the same time, compared with existing alloy catalyst products, the method has the advantages of a narrow particle size distribution range and uniform dispersion of the metal components in the particles, which can better exert the catalyst performance and is suitable for industrial mass production.

[0007] In order to solve the above technical problems, the first aspect of the present invention provides a method for preparing a platinum-cerium alloy catalyst, comprising the following steps:

[0008] S1. dissolving a platinum precursor salt and a cerium precursor salt in deionized water to obtain a solution A;

[0009] S2. dispersing carbon powder in ethylene glycol or ethylene glycol aqueous solution to obtain solution B;

[0010] S3. At room temperature, the solution A and the solution B were mixed and stirred for 1-3 hours, the pH was adjusted to alkaline with alkali solution and stirred for 0.5-2 hours, a surfactant was added and stirred for 2-4 hours to obtain a mixed solution C;

[0011] S4, placing the mixed solution C in a microwave reactor, and subjecting the microwave to 5-10 cycles of start / stop at room temperature to obtain a platinum-cerium alloy catalyst;

[0012] The total mass fraction of platinum and cerium in the catalyst is 30-60wt%.

[0013] The present invention adopts metal ion co-deposition and microwave-assisted method to prepare platinum-cerium alloy catalyst, which has simple process and low cost. By controlling the amount of reducing agent and carbon source and the ratio of platinum-cerium metal to change the crystal structure and particle size of the alloy catalyst, the catalyst performance and life are improved. Specifically, the metal precursor is first mixed in deionized water and carbon powder is added to the ethylene glycol aqueous solution. The two dispersions are then mixed so that the reducing agent ethylene glycol, carbon powder, and precursor salt are fully mixed to ensure that the components of the reaction system are uniform. Secondly, alkaline sodium hydroxide is added to allow the metal salts in the solution to co-precipitate onto the carbon support to form mixed hydroxides. The prepared alloy particles obtain a relatively uniform alloy structure and particle size distribution. Furthermore, a surfactant is added. The high molecular weight and high stability of the surfactant are utilized to adsorb the surfactant on the carbon support, coating the metal particles and playing a fixing role. At the same time, the viscosity of the reaction system and the reduction strength of the system are adjusted by changing the concentration of the reducing agent to ensure that the system remains uniform and fully reduced during the reaction. Finally, the reaction temperature is controlled as much as possible under the conditions of ensuring full reduction to prevent excessive temperature from causing catalyst particles to agglomerate.

[0014] Furthermore, in S1, the platinum precursor salt is selected from one or more of chloroplatinic acid, platinum tetrachloride, dichlorodiammineplatinum, acetylacetonate platinum, and tetraammineplatinum; the cerium precursor salt is selected from one or more of cerium trichloride, cerium nitrate, cerium acetylacetonate, and cerium sulfate.

[0015] Furthermore, in S1, the molar ratio of platinum to cerium in the platinum precursor salt and the cerium precursor salt is 1:(0.3-0.5); the concentration of the platinum precursor salt in solution A is 15.8-19.9 g / L; and the concentration of the cerium precursor salt in solution A is 2.8-4.2 g / L.

[0016] Furthermore, in S2, the concentration of the carbon powder in solution B is 10-18.5 g / L.

[0017] Furthermore, in S2, the mixture is stirred and dispersed at 80-90° C., and cooled to room temperature for later use.

[0018] Furthermore, in S2, the concentration of ethylene glycol in the ethylene glycol aqueous solution is above 10 wt%.

[0019] Furthermore, in S3, the surfactant is selected from one or more of fatty alcohol polyoxyethylene ether, polyvinyl pyrrolidone, P123, and N,N-dihydroxyethyl fatty amide.

[0020] Furthermore, in S3, the alkali solution is a sodium hydroxide aqueous solution with a pH of 8.5-10. Furthermore, the concentration of the sodium hydroxide aqueous solution is 0.05-1 mol / L.

[0021] Furthermore, in S4, the parameters of the microwave are: frequency 2200-2600 MHz, power 500-700 W, single start time 55-65 s, and single stop time 40-50 s.

[0022] Furthermore, after S4, the steps of washing and filtering with deionized water until the conductivity of the filtrate is less than 10 μS / cm, and drying at 110-130° C. are also included.

[0023] The second aspect of the present invention provides a platinum-cerium alloy catalyst prepared by the preparation method described in the first aspect.

[0024] The third aspect of the present invention provides use of the platinum-cerium alloy catalyst described in the second aspect in a fuel cell.

[0025] Beneficial effects of the present invention:

[0026] (1) The present invention prepares the alloy catalyst by co-deposition of platinum and cerium metals and microwave-assisted reaction, and regulates the crystal structure and particle size of the alloy catalyst by controlling the content of each component, thereby improving the catalyst performance and life.

[0027] (2) The present invention uses an intermittent microwave reaction method during the microwave-assisted reaction stage. By starting and stopping the microwaves, the reduction of the metal components in the catalyst is ensured, and the crystallinity of the catalyst alloy particles is improved. At the same time, the agglomeration of metal particles caused by excessive temperature is reduced, and a good particle size distribution is maintained.

[0028] (3) The experimental conditions required by the present invention are relatively mild, and no high-temperature alloying process is required. The obtained alloy catalyst particles have a narrow particle size distribution and good product consistency. At the same time, the process of this method is simple and can be industrialized. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the technical solution of the present invention, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are merely embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0030] Figure 1 is the voltammetric cycle curve of the catalyst of Example 3 of the present invention;

[0031] Figure 2 is the oxygen reduction polarization curve of the catalyst of Example 3 of the present invention;

[0032] Figure 3 This is the polarization curve of the membrane electrode prepared using the catalyst of Example 3 of the present invention. DETAILED DESCRIPTION

[0033] The following will provide a clear and complete description of the technical solutions of the present invention in conjunction with specific embodiments of the present invention. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0034] This embodiment relates to a method for preparing a platinum-cerium alloy catalyst, comprising the following steps:

[0035] S1. dissolving a platinum precursor salt and a cerium precursor salt in deionized water to obtain a solution A;

[0036] S2. dispersing carbon powder in ethylene glycol or ethylene glycol aqueous solution to obtain solution B;

[0037] S3. At room temperature, the solution A and the solution B were mixed and stirred for 1-3 hours, the pH was adjusted to alkaline with alkali solution and stirred for 0.5-2 hours, a surfactant was added and stirred for 2-4 hours to obtain a mixed solution C;

[0038] S4, placing the mixed solution C in a microwave reactor, and subjecting the microwave to 5-10 cycles of start / stop at room temperature to obtain a platinum-cerium alloy catalyst;

[0039] The total mass fraction of platinum and cerium in the catalyst is 30-60wt%.

[0040] This embodiment uses metal ion co-deposition and microwave-assisted methods to prepare a platinum-cerium alloy catalyst, which has a simple process and low cost. The crystal structure and particle size of the alloy catalyst are changed by controlling the amount of reducing agent and carbon source and the ratio of platinum to cerium metal. The viscosity of the reaction system and the reduction strength of the system are adjusted by changing the concentration of the reducing agent to ensure that the system remains uniform during the reaction and is fully reduced. The resulting catalyst particles have a narrow particle size distribution, good product consistency, and excellent catalyst performance and life.

[0041] In this embodiment, a metal precursor is mixed in deionized water and carbon powder is added to an aqueous solution of ethylene glycol, and then the two dispersions are mixed so that the reducing agent ethylene glycol, carbon powder, and precursor salt are fully mixed to ensure that the components of the reaction system are uniform. By adding alkaline sodium hydroxide, the metal salts in the solution are co-precipitated onto the carbon support to form a mixed hydroxide, and the prepared alloy particles obtain a relatively uniform alloy structure and particle size distribution. Furthermore, a surfactant is added, and the high molecular weight and high stability of the surfactant are utilized to adsorb the surfactant on the carbon support, coating the metal particles and playing a fixing role. By cyclic microwave treatment, the reduction of each metal component in the catalyst is ensured, the crystallinity of the catalyst alloy particles is improved, and at the same time, the catalyst particles are prevented from agglomerating due to excessive temperature.

[0042] As a preferred embodiment, in S1, the platinum precursor salt is selected from one or more of chloroplatinic acid, platinum tetrachloride, diammine dichloroplatinum, platinum acetylacetonate, and tetraammine platinum; the cerium precursor salt is selected from one or more of cerium trichloride, cerium nitrate, cerium acetylacetonate, and cerium sulfate. The molar ratio of platinum to cerium in the platinum precursor salt and the cerium precursor salt is 1:(0.3-0.5); the concentration of the platinum precursor salt in solution A is 15.8-19.9 g / L; the concentration of the cerium precursor salt in solution A is 2.8-4.2 g / L.

[0043] As a preferred embodiment, in S2, the mixture is stirred and dispersed at 80-90°C and cooled to room temperature for standby use. The concentration of the carbon powder in solution B is 10-18.5 g / L. The concentration of ethylene glycol in the ethylene glycol aqueous solution is above 10 wt%.

[0044] As a preferred embodiment, in S3, the surfactant is selected from one or more of fatty alcohol polyoxyethylene ether, polyvinyl pyrrolidone, P123, and N,N-dihydroxyethyl fatty amide; the alkali solution is a sodium hydroxide aqueous solution with a pH of 8.5-10, and further, the concentration of the sodium hydroxide aqueous solution is 0.05-1 mol / L.

[0045] In a preferred embodiment, in S4, the microwave parameters are: frequency 2200-2600 MHz, power 500-700 W, single start time 55-65 seconds, and single stop time 40-50 seconds. S4 also includes the steps of washing and filtering with deionized water until the filtrate has a conductivity of less than 10 μS / cm, and drying at 110-130°C.

[0046] Another embodiment relates to a platinum-cerium alloy catalyst prepared by the preparation method described in the above embodiment.

[0047] Another embodiment relates to the use of the platinum-cerium alloy catalyst described in the above embodiment in a fuel cell.

[0048] Example 1

[0049] This embodiment relates to a method for preparing a platinum-cerium alloy catalyst, comprising the following steps:

[0050] (1) Add 53.6 g of chloroplatinic acid hexahydrate and 8.5 g of cerium trichloride to 3000 g of deionized water and stir until completely dissolved to prepare solution A.

[0051] (2) 25 g of carbon powder was added to 2000 g of ethylene glycol aqueous solution (ethylene glycol mass fraction 15 wt%), and stirred at 90° C. for 3 h to prepare mixed solution B.

[0052] (3) After the mixed solution B cools to room temperature, solution A is added to the mixed solution B and stirred for 2 h.

[0053] (4) Slowly add 0.07 mol / L sodium hydroxide solution to the mixture until the pH reaches 8.5, and stir at room temperature for 1 h.

[0054] (5) Then, 17.5 g of polyvinyl pyrrolidone was added and stirred at room temperature for 3 h to obtain a mixed solution C.

[0055] (6) The mixed solution C was placed in a microwave reactor and stirred continuously. The microwave parameters were set as follows: 2450 MHz, 600 W, 60 s start, 45 s stop, and the reaction cycle was repeated 7 times to prepare the alloy catalyst and obtain a catalyst sample.

[0056] (7) The catalyst sample was washed and filtered with deionized water until the conductivity of the filtrate was less than 10 μS / cm.

[0057] (8) The washed catalyst sample was dried in a vacuum drying oven at 120° C. for 48 h to obtain a platinum-cerium alloy catalyst, wherein the molar ratio of platinum to cerium was 3:1.

[0058] Example 2

[0059] The difference between this embodiment and embodiment 1 is that the mass fraction of ethylene glycol in the ethylene glycol aqueous solution is adjusted to 45%, specifically:

[0060] (1) Add 53.6 g of chloroplatinic acid hexahydrate and 8.5 g of cerium trichloride to 3000 g of deionized water and stir until completely dissolved to prepare solution A.

[0061] (2) 25 g of carbon powder was added to 2000 g of ethylene glycol aqueous solution (ethylene glycol mass fraction 45 wt%), and stirred at 90° C. for 3 h to prepare mixed solution B.

[0062] (3) After the mixed solution B cools to room temperature, solution A is added to the mixed solution B and stirred for 2 h.

[0063] (4) Slowly add 0.07 mol / L sodium hydroxide solution to the mixture until the pH reaches 8.5, and stir at room temperature for 1 h.

[0064] (5) Then, 17.5 g of polyvinyl pyrrolidone was added and stirred at room temperature for 3 h to obtain a mixed solution C.

[0065] (6) The mixed solution C was placed in a microwave reactor and stirred continuously. The microwave parameters were set as follows: 2450 MHz, 600 W, 60 s start, 45 s stop, and the reaction cycle was repeated 7 times to prepare the alloy catalyst and obtain a catalyst sample.

[0066] (7) The catalyst sample was washed and filtered with deionized water until the conductivity of the filtrate was less than 10 μS / cm.

[0067] (8) The washed catalyst sample was dried in a vacuum drying oven at 120° C. for 48 h to obtain a platinum-cerium alloy catalyst, wherein the molar ratio of platinum to cerium was 3:1.

[0068] Example 3

[0069] The difference between this embodiment and embodiment 1 is that the mass fraction of ethylene glycol in the ethylene glycol aqueous solution is adjusted to 62.5%, specifically:

[0070] (1) Add 53.6 g of chloroplatinic acid hexahydrate and 8.5 g of cerium trichloride to 3000 g of deionized water and stir until completely dissolved to prepare solution A.

[0071] (2) 25 g of carbon powder was added to 2000 g of ethylene glycol aqueous solution (ethylene glycol mass fraction 62.5 wt%), and stirred at 90° C. for 3 h to prepare mixed solution B.

[0072] (3) After the mixed solution B cools to room temperature, solution A is added to the mixed solution B and stirred for 2 h.

[0073] (4) Slowly add 0.07 mol / L sodium hydroxide solution to the mixture until the pH reaches 8.5, and stir at room temperature for 1 h.

[0074] (5) Then, 17.5 g of polyvinyl pyrrolidone was added and stirred at room temperature for 3 h to obtain a mixed solution C.

[0075] (6) The mixed solution C was placed in a microwave reactor and stirred continuously. The microwave parameters were set as follows: 2450 MHz, 600 W, 60 s start, 45 s stop, and the reaction cycle was repeated 7 times to prepare the alloy catalyst and obtain a catalyst sample.

[0076] (7) The catalyst sample was washed and filtered with deionized water until the conductivity of the filtrate was less than 10 μS / cm.

[0077] (8) The washed catalyst sample was dried in a vacuum drying oven at 120° C. for 48 h to obtain a platinum-cerium alloy catalyst, wherein the molar ratio of platinum to cerium was 3:1.

[0078] Example 4

[0079] The difference between this embodiment and embodiment 1 is that the ethylene glycol aqueous solution is replaced by ethylene glycol, specifically:

[0080] (1) Add 53.6 g of chloroplatinic acid hexahydrate and 8.5 g of cerium trichloride to 3000 g of deionized water and stir until completely dissolved to prepare solution A.

[0081] (2) Add 25 g of carbon powder to 2000 g of ethylene glycol, and stir at 90° C. for 3 h to prepare mixed solution B.

[0082] (3) After the mixed solution B cools to room temperature, solution A is added to the mixed solution B and stirred for 2 h.

[0083] (4) Slowly add 0.07 mol / L sodium hydroxide solution to the mixture until the pH reaches 8.5, and stir at room temperature for 1 h.

[0084] (5) Then, 17.5 g of polyvinyl pyrrolidone was added and stirred at room temperature for 3 h to obtain a mixed solution C.

[0085] (6) The mixed solution C was placed in a microwave reactor and stirred continuously. The microwave parameters were set as follows: 2450 MHz, 600 W, 60 s start, 45 s stop, and the reaction cycle was repeated 7 times to prepare the alloy catalyst and obtain a catalyst sample.

[0086] (7) The catalyst sample was washed and filtered with deionized water until the conductivity of the filtrate was less than 10 μS / cm.

[0087] (8) The washed catalyst sample was dried in a vacuum drying oven at 120° C. for 48 h to obtain a platinum-cerium alloy catalyst, wherein the molar ratio of platinum to cerium was 3:1.

[0088] Comparative Example 1

[0089] The difference between this comparative example and Example 3 is that the concentrations and ratios of chloroplatinic acid hexahydrate and cerium trichloride are adjusted as follows:

[0090] (1) Add 38.6 g of chloroplatinic acid hexahydrate and 18.4 g of cerium trichloride to 3000 g of deionized water and stir until completely dissolved to prepare solution A.

[0091] (2) 25 g of carbon powder was added to 2000 g of ethylene glycol aqueous solution (ethylene glycol mass fraction 62.5 wt%), and stirred at 90° C. for 3 h to prepare mixed solution B.

[0092] (3) After the mixed solution B cools to room temperature, solution A is added to the mixed solution B and stirred for 2 h.

[0093] (4) Slowly add 0.07 mol / L sodium hydroxide solution to the mixture until the pH reaches 8.5, and stir at room temperature for 1 h.

[0094] (5) Then, 17.5 g of polyvinyl pyrrolidone was added and stirred at room temperature for 3 h to obtain a mixed solution C.

[0095] (6) The mixed solution C was placed in a microwave reactor and stirred continuously. The microwave parameters were set as follows: 2450 MHz, 600 W, 60 s start, 45 s stop, and the reaction cycle was repeated 7 times to prepare the alloy catalyst and obtain a catalyst sample.

[0096] (7) The catalyst sample was washed and filtered with deionized water until the conductivity of the filtrate was less than 10 μS / cm.

[0097] (8) The washed catalyst sample was dried in a vacuum drying oven at 120° C. for 48 h to obtain a platinum-cerium alloy catalyst, wherein the molar ratio of platinum to cerium was 1:1.

[0098] Comparative Example 2

[0099] The difference between this comparative example and Example 3 is that the concentrations and ratios of chloroplatinic acid hexahydrate and cerium trichloride are adjusted as follows:

[0100] (1) Add 21.1 g of chloroplatinic acid hexahydrate and 30.0 g of cerium trichloride to 3000 g of deionized water and stir until completely dissolved to prepare solution A.

[0101] (2) 25 g of carbon powder was added to 2000 g of ethylene glycol aqueous solution (ethylene glycol mass fraction 62.5 wt%), and stirred at 90° C. for 3 h to prepare mixed solution B.

[0102] (3) After the mixed solution B cools to room temperature, solution A is added to the mixed solution B and stirred for 2 h.

[0103] (4) Slowly add 0.07 mol / L sodium hydroxide solution to the mixture until the pH reaches 8.5, and stir at room temperature for 1 h.

[0104] (5) Then, 17.5 g of polyvinyl pyrrolidone was added and stirred at room temperature for 3 h to obtain a mixed solution C.

[0105] (6) The mixed solution C was placed in a microwave reactor and stirred continuously. The microwave parameters were set as follows: 2450 MHz, 600 W, 60 s start, 45 s stop, and the reaction cycle was repeated 7 times to prepare the alloy catalyst and obtain a catalyst sample.

[0106] (7) The catalyst sample was washed and filtered with deionized water until the conductivity of the filtrate was less than 10 μS / cm.

[0107] (8) The washed catalyst sample was dried in a vacuum drying oven at 120° C. for 48 h to obtain a platinum-cerium alloy catalyst, wherein the molar ratio of platinum to cerium was 1:3.

[0108] Test Example 1

[0109] The average particle size of the platinum metal particles of the alloy catalysts obtained in Examples 1-4 and Comparative Examples 1-2 was calculated based on the XRD patterns, and the results are shown in Table 1.

[0110] Table 1

[0111]

[0112] As shown in Table 1, the platinum particle sizes of the platinum-cerium alloy catalysts obtained in Example 3 and Comparative Examples 1 and 2 were 4.1 nm, 5.8 nm, and 7.3 nm, respectively. This indicates that varying the platinum-cerium ratio significantly affects the particle size and structure of the catalyst metal particles, further impacting catalytic activity and catalyst life. Catalysts with larger particles generally exhibit relatively poorer performance. Furthermore, Examples 1-4 demonstrate that varying the reducing agent concentration during the synthesis process affects the solution viscosity, which in turn alters the dispersibility of the carrier carbon powder and metal particles, further affecting particle size. The particle size obtained under the reducing agent concentration conditions in Example 3 was the smallest.

[0113] Test Example 2

[0114] The platinum-cerium alloy catalysts obtained in Examples 1-4 and Comparative Examples 1-2 were subjected to electrochemical tests, and the intrinsic performance of the platinum-cerium alloy catalysts was evaluated by calculating the electrochemical active area and mass activity. The results are shown in Table 2. It can be seen that there is a positive correlation between the electrochemical active area and the mass activity. The higher the electrochemical active area, the higher the mass activity and the better the catalyst performance. Among the catalysts in Examples 1-4, the catalyst performance under the conditions of Example 3 is the highest. Combined with the average particle size of the catalyst metal in Test 1, it can be seen that the catalyst performance under the synthesis conditions of Implementation 3 is the best. The test results of Comparative Examples 1-2 show that the performance of the platinum-cerium alloy catalysts has declined significantly. It is believed that the different platinum-cerium ratios of the catalysts affect the structure and metal particle size of the platinum-cerium alloy, thereby causing changes in the catalyst performance.

[0115] Table 2

[0116]

[0117] Figure 1-2 The RDE electrochemical CV curve and oxygen reduction polarization curve of the platinum-cerium alloy catalyst with a total metal loading of 50 wt% in Example 3 are shown to determine its performance. As can be seen, the peak structure in the hydrogen adsorption region of the platinum-cerium alloy catalyst differs from that of the platinum-carbon catalyst, indicating that cerium is doped into the platinum, possibly forming an alloy.

[0118] Test Example 3

[0119] The platinum-cerium alloy catalysts obtained in Examples 1-4 and Comparative Examples 1-2 were prepared by ultrasonic spraying to prepare cathode platinum with a loading of 0.2 gPt / cm 2 Membrane electrode (anode platinum loading of 0.05gPt / cm 2 , using 20wt% commercial platinum carbon catalyst), evaluate the effect of platinum-cerium alloy catalyst on membrane electrode, the results are shown in Table 3. Among them, the platinum-cerium catalyst membrane electrode preparation process conditions: 0.3g of platinum-cerium alloy catalyst is moistened with 15g of deionized water, and then 15g of isopropanol and 2.4g of 5wt% D520 resin are added. The mixed liquid is placed in a constant temperature ultrasonic machine at 20℃, and the high-speed shearing machine is subjected to high-speed shearing at 10000rpm for 2h to obtain a platinum-cerium alloy catalyst slurry. The slurry is injected into the spray syringe with a flow rate of 0.5ml / min, the adsorption heating plate temperature is set to 90℃, and the spraying area is 5×5cm 2 Place the 12μm proton membrane on the adsorption plate, start vacuum adsorption, and start the spraying process. Control the number of spraying passes to make the platinum loading of the anode platinum carbon catalyst 0.05gPt / cm 2 The platinum loading of the cathode platinum-cerium alloy catalyst is 0.2 gPt / cm 2Cut appropriate carbon paper and frames for five-in-one or seven-in-one assembly to prepare membrane electrodes.

[0120] As can be seen from Table 3, the catalysts obtained in Examples 1-4 decayed to varying degrees after 10,000 accelerated aging tests. It is believed that the synthesis conditions affected the structure of the platinum-cerium metal components in the catalysts, resulting in different stability. The membrane electrode prepared using the catalyst obtained in Example 3 had the best stability. After 10,000 accelerated aging tests, the membrane electrode had a 2A / cm 2 The catalyst exhibited only a 1.91% decrease at a current density of 1.5 Å. Comparative Examples 1 and 2 show that increasing the cerium content in the catalyst improves membrane electrode stability but significantly reduces membrane electrode activity. Therefore, based on a comprehensive consideration of catalyst and membrane electrode activity and stability, the platinum-cerium alloy catalyst obtained in Example 3 exhibits both high activity and good stability, demonstrating excellent overall performance. Figure 3 The polarization curve of the membrane electrode prepared by the platinum-cerium alloy catalyst obtained in Example 3 reflects the good membrane electrode performance of the alloy catalyst at medium and low current densities.

[0121] Table 3

[0122]

[0123] The present invention has been described in detail above with reference to specific embodiments and exemplary examples. However, these descriptions should not be construed as limiting the present invention. Those skilled in the art will appreciate that various equivalent substitutions, modifications, or improvements may be made to the technical solutions and implementations of the present invention without departing from the spirit and scope of the present invention, all of which fall within the scope of the present invention. The scope of protection of the present invention shall be determined by the appended claims.

Claims

1. A method for preparing a platinum-cerium alloy catalyst, characterized in that: The steps include: S1. dissolving a platinum precursor salt and a cerium precursor salt in deionized water to obtain a solution A; S2. dispersing carbon powder in ethylene glycol or ethylene glycol aqueous solution to obtain solution B; S3. At room temperature, the solution A and the solution B were mixed and stirred for 1-3 hours, the pH was adjusted to alkaline with alkali solution and stirred for 0.5-2 hours, a surfactant was added and stirred for 2-4 hours to obtain a mixed solution C; S4, placing the mixed solution C in a microwave reactor, and subjecting the microwave to 5-10 cycles of start / stop at room temperature to obtain a platinum-cerium alloy catalyst; The total mass fraction of platinum and cerium in the catalyst is 30-60wt%.

2. The method for preparing a platinum-cerium alloy catalyst according to claim 1, wherein: In S1, the platinum precursor salt is selected from one or more of chloroplatinic acid, platinum tetrachloride, dichlorodiammineplatinum, acetylacetonate platinum, and tetraammineplatinum; the cerium precursor salt is selected from one or more of cerium trichloride, cerium nitrate, cerium acetylacetonate, and cerium sulfate.

3. The method for preparing the platinum-cerium alloy catalyst according to claim 1, wherein: In S1, the molar ratio of platinum to cerium in the platinum precursor salt and the cerium precursor salt is 1:(0.3-0.5); the concentration of the platinum precursor salt in solution A is 15.8-19.9 g / L; and the concentration of the cerium precursor salt in solution A is 2.8-4.2 g / L.

4. The method for preparing a platinum-cerium alloy catalyst according to claim 1, wherein: In S2, the concentration of the carbon powder in solution B is 10-18.5 g / L.

5. The method for preparing the platinum-cerium alloy catalyst according to claim 1, wherein: In S3, the surfactant is selected from one or more of fatty alcohol polyoxyethylene ether, polyvinyl pyrrolidone, P123, and N,N-dihydroxyethyl fatty amide.

6. The method for preparing a platinum-cerium alloy catalyst according to claim 1, wherein: In S3, the alkali solution is a sodium hydroxide aqueous solution with a pH of 8.5-10.

7. The method for preparing a platinum-cerium alloy catalyst according to claim 1, wherein: In S4, the parameters of the microwave are: frequency 2200-2600 MHz, power 500-700 W, single start time 55-65 s, and single stop time 40-50 s.

8. The method for preparing a platinum-cerium alloy catalyst according to claim 1, wherein: S4 also includes the steps of washing and filtering with deionized water until the conductivity of the filtrate is less than 10 μS / cm, and drying at 110-130° C.

9. A platinum-cerium alloy catalyst prepared by the preparation method according to any one of claims 1 to 8.

10. Use of the platinum-cerium alloy catalyst according to claim 9 in a fuel cell.

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