A platinum-based alloy catalyst, a preparation method and application thereof

Abstract

The application provides a platinum-based alloy catalyst and a preparation method and application thereof, and the preparation method comprises the following steps: mixing a platinum salt, an M metal salt, an organic matter, a carbon carrier and a solvent to obtain a hydrogel; wherein the M comprises a metal other than Pt; the hydrogel is subjected to freeze-drying to obtain an aerogel; the aerogel is subjected to annealing and post-processing to obtain the platinum-based alloy catalyst; the platinum-based alloy catalyst obtained by the preparation method is a binary or more alloy catalyst, has an ordered structure, can solve the problem that a non-noble metal of a conventional alloy catalyst is prone to being dissolved, meanwhile, the preparation method can effectively control the particle size of the catalyst and can make the atoms in the metal alloy be arranged in an order, therefore, the obtained catalyst has excellent electrochemical performance and high stability.

Description

Technical Field

[0001] This invention belongs to the field of fuel cell technology, and relates to a platinum-based alloy catalyst, its preparation method, and its application. Background Technology

[0002] Currently, among different types of fuel cells, proton exchange membrane fuel cells (PEMFCs) using hydrogen fuel are considered the best candidate for application in automobiles due to their low operating temperature, short preheating time, and high power density. However, the slow kinetics of the oxygen reduction reaction (ORR) is a major bottleneck in the development of PEMFCs. Platinum has high ORR catalytic activity and can improve ORR activity. Although platinum (Pt) is generally considered to have the highest ORR catalytic activity among pure metals, CN 115101767A discloses a hydrogen fuel cell catalyst, including a support, which is a fullerene, with a PtAu alloy supported on the fullerene surface, and Pt supported on the PtAu alloy surface; that is, it uses fullerene as a support and Pt and Au as active components, loads noble metals through polyol reduction, then alloys them through high-temperature calcination, and finally loads Pt on the alloy surface by hydrogen reduction to obtain an alloy catalyst.

[0003] However, the scarcity and high cost of Pt greatly limit its large-scale application. Due to the electronic and / or strain effects between non-noble metal transition metals and Pt, alloying Pt with transition metals (Fe, Co, Ni, Cu, etc.) has proven to be an effective method to improve catalytic activity and thus reduce Pt usage. However, in acidic ORR environments, the non-noble metals in Pt alloys will be continuously leached, leading to deactivation during long-term electrocatalysis. Therefore, conventional disordered Pt alloys have poor resistance to dissolution, resulting in decreased ORR activity and stability.

[0004] Based on the above research, there is a need to provide a method for preparing platinum-based alloy catalysts. Compared with conventional alloy catalysts, the platinum-based alloy catalysts obtained by the preparation method have an ordered structure, higher resistance to dissolution, and significantly improved ORR activity and stability. Summary of the Invention

[0005] The purpose of this invention is to provide a platinum-based alloy catalyst, its preparation method, and its application. The platinum-based alloy catalyst obtained by the preparation method is a binary or higher alloy catalyst with an ordered structure. It can solve the problem of easy dissolution of non-precious metals in conventional alloy catalysts, effectively control the particle size of the catalyst, and enable the atoms in the metal alloy to be arranged in an orderly manner. Therefore, the obtained catalyst has excellent electrochemical performance and high stability.

[0006] To achieve this objective, the present invention employs the following technical solution:

[0007] In a first aspect, the present invention provides a method for preparing a platinum-based alloy catalyst, the method comprising the following steps:

[0008] (1) A hydrogel is obtained by mixing a platinum salt, a metal salt of M, an organic substance, a carbon support, and a solvent; wherein, M includes metals other than Pt.

[0009] (2) Freeze-dry the hydrogel obtained in step (1) to obtain an aerogel;

[0010] (3) Anneal and post-treat the aerogel obtained in step (2) to obtain the platinum-based alloy catalyst.

[0011] This invention uses a freeze-drying gel method to synthesize structurally ordered multi-metal intermetallic compound catalysts. By mixing multiple precursors in step (1), the uneven loading of different metal salt solutions on the support is avoided, the dispersibility of metal precursors on the support is improved, thereby reducing the temperature required for the formation of the intermetallic compound structure, effectively controlling the particle size of the intermetallic compound, and improving the crystallinity of the alloy material, so that the obtained catalyst particles have an ordered structure. Therefore, compared with conventional catalysts, the non-precious metals in the catalyst obtained by this invention are not easily dissolved, and it has higher ORR activity and stability.

[0012] Preferably, the organic compound in step (1) includes any one or a combination of at least two of polyvinyl alcohol (PVA), polyacryl alcohol (PPG), polyethylene glycol (PEG), or citric acid, with PVA being the most preferred.

[0013] This invention uses PVA and other substances that easily form gels and do not introduce other impurities into the catalyst as organic materials for forming hydrogels. Furthermore, the specific organic materials of this invention are easily soluble in water. At the same time, PVA contains a large number of hydroxyl groups, which can promote the formation of hydrogels through hydrogen bonding interactions. This hydrogel can effectively prevent the aggregation of metal salts and carbon supports and promote their dispersion.

[0014] Preferably, the mixing in step (1) includes first dissolving platinum salt and M metal salt in a solution containing organic matter to obtain mixture A, then mixing carbon support and solvent to obtain mixture B, then mixing mixture A and mixture B to obtain mixture C, and finally ultrasonically dispersing mixture C to obtain the hydrogel.

[0015] The organic-containing solution described in this invention is an aqueous solution containing organic matter.

[0016] Preferably, the concentration of organic matter in the mixture C is 0.8-3.5 mg·mL. -1 For example, it could be 0.8 mg / mL -1 1.0 mg·mL -11.25 mg / mL -1 1.5 mg / mL -1 1.75 mg / mL -1 2.0 mg·mL -1 2.25 mg·mL -1 2.5 mg / mL -1 2.75 mg·mL -1 3.0 mg·mL -1 3.25 mg·mL -1 Or 3.5 mg / mL -1 However, this does not limit the listed values; other unlisted values ​​within the range are also applicable.

[0017] The concentration of the organic matter described in this invention will affect the dispersibility of metal salts and platinum salts. If the concentration of the organic matter is too high, it cannot be completely dissolved in the solvent water, and the resulting solution viscosity is too high, which is not conducive to mixing with the carbon support. Furthermore, the subsequent freeze-drying takes too long. If the concentration of the organic matter is too low, the hydrogel cannot be effectively generated, which will also affect the subsequent generation of intermetallic compounds.

[0018] Preferably, the M metal salt in step (1) comprises a combination of at least two metal salts other than platinum.

[0019] Preferably, the M metal salt in step (1) includes a combination of M1 metal salt and M2 metal salt, wherein M1 and M2 are different types of metals.

[0020] The M metal salt used in this invention is a combination of at least two metal salts, and preferably a combination of two different types of metal salts, so that the resulting catalyst is a ternary alloy catalyst. Since ternary catalysts have better performance than binary catalysts, and are easier to disperse evenly and synthesize than quaternary and pentagonal catalysts, they are more suitable for the gelation method of this invention and are more likely to form structurally ordered intermetallic compounds.

[0021] Preferably, the molar ratio of M1 metal salt, M2 metal salt and platinum salt is (0.2-0.6):(0.02-0.08):(0.6-0.85), for example, it can be 0.25:0.05:0.75, 0.3:0.03:0.85, 0.2:0.08:0.6 or 0.6:0.02:0.85, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0022] The adjustment of the ratio of M1 metal salt, M2 metal salt and platinum salt described in this invention can regulate the electronic structure of the formed PtM1M2 ternary intermetallic compound and the catalytic activity of the strain-modulated catalyst. Within the above-mentioned specific range, a catalyst with excellent comprehensive performance can be obtained.

[0023] Preferably, M1 and M2 are each independently selected from any one or at least a combination of two of Fe, Co, Ni, Cu, Mn, Cr, Pd, Ir, Ru, La, Ce, Gd or Ti.

[0024] Preferably, step (1) includes chloroplatinic acid.

[0025] Preferably, the carbon support in step (1) includes any one or a combination of at least two of Ketjen black, acetylene black, graphene, or carbon nanotubes.

[0026] Preferably, the solvent in step (1) includes water.

[0027] Preferably, the freeze-drying time in step (2) is 18-30 hours, for example, 18 hours, 20 hours, 25 hours or 30 hours, but not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0028] Preferably, the annealing in step (3) includes first holding at a temperature of 600-800℃, for example, 600℃, 700℃ or 800℃, and then cooling down to 250-350℃ at a rate of 0.5-1.5℃ / min, for example, 0.5℃ / min, 1.0℃ or 1.5℃ / min, but not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0029] The annealing rate and temperature of the annealing step in this invention affect the formation of intermetallic compounds. A specific cooling rate and temperature are required to allow Pt, M1, and M2 to form intermetallic compounds. If the cooling rate is too fast, it will not be conducive to the rearrangement of metal atoms and the structure of intermetallic compounds cannot be formed. If the cooling rate is too slow, the metal particles will grow larger during the heat treatment process.

[0030] Preferably, the heat preservation time is 1-3 hours, for example, it can be 1 hour, 2 hours or 3 hours, but it is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0031] Preferably, the temperature is lowered to 250-350°C and then naturally cooled to room temperature.

[0032] Preferably, the annealing atmosphere comprises a mixture of inert and reducing gases.

[0033] Preferably, the volume ratio of the inert gas to the reducing gas is (5-20):1, for example, it can be 20:1, 10:1 or 5:1, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0034] Preferably, the inert gas includes any one or a combination of at least two of argon, helium, or krypton, and the reducing gas includes hydrogen.

[0035] Preferably, the post-processing in step (3) includes pickling, solid-liquid separation, water washing and drying performed sequentially.

[0036] Preferably, the concentration of the pickling solution used in the pickling is 0.5-1.5 mol / L, for example, it can be 0.5 mol / L, 1.0 mol / L or 1.5 mol / L, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0037] The post-treatment of this invention uses dilute acid for washing, which can remove the M metal on the catalyst surface while maintaining the PtM1M2 alloy structure inside. This results in a core-shell structure with a Pt outer shell and a PtM1M2 alloy core. The protection of the outer noble metal Pt shell further prevents the dissolution of non-noble metals, thus improving the electrochemical performance and stability of the catalyst.

[0038] Preferably, the pickling solution used in the pickling includes nitric acid and / or sulfuric acid.

[0039] As a preferred embodiment of the preparation method of the present invention, the preparation method includes the following steps:

[0040] (1) Dissolve platinum salt, M1 metal salt and M2 metal salt in a solution containing organic matter to obtain mixture A. Then mix carbon support and solvent to obtain mixture B. Then mix mixture A and mixture B to obtain mixture C. After ultrasonic dispersion of mixture C, hydrogel is obtained.

[0041] In the mixture C, the concentration of organic matter is 0.8-3.5 mg·mL. -1 The molar ratio of M1 metal salt, M2 metal salt, and platinum salt is (0.2-0.6):(0.02-0.08):(0.6-0.85).

[0042] (2) Freeze-dry the hydrogel obtained in step (1) for 18-30 hours to obtain aerogel;

[0043] (3) The aerogel described in step (2) is kept at a temperature of 600-800℃ for 1-3 hours in a mixed atmosphere of inert gas and reducing gas, then cooled to 250-350℃ at a rate of 0.5-1.5℃ / min, and then naturally cooled to room temperature. Finally, acid washing, solid-liquid separation, water washing and drying are performed in sequence to obtain the platinum-based alloy catalyst.

[0044] The concentration of the pickling solution used in pickling is 0.5-1.5 mol / L.

[0045] In a second aspect, the present invention provides a platinum-based alloy catalyst, which is obtained by the preparation method described in the first aspect.

[0046] Preferably, the platinum-based alloy catalyst comprises PtM1M2@Pt particles, wherein the PtM1M2@Pt particles have a core-shell structure, wherein the outer shell comprises Pt and the core comprises an alloy of Pt, M1 and M2.

[0047] Preferably, the particle size distribution range of the PtM1M2@Pt particles is 2-6 nm, and the thickness of the outer shell is 2-5 Pt atomic layers, preferably 0.8-1.2 nm.

[0048] Thirdly, the present invention provides an application of the platinum-based catalyst as described in the second aspect, the application including its use in fuel cells.

[0049] Compared with the prior art, the present invention has the following beneficial effects:

[0050] This invention synthesizes a multi-element intermetallic compound catalyst with an ordered core-shell structure through a freeze-drying gelation method, combined with a precursor salt mixing step and a subsequent annealing step. This not only avoids the problem of easy dissolution of non-precious metals and effectively controls the catalyst particle size, but also improves the dispersibility of the metal precursor on the support, thereby reducing the temperature required for the formation of the intermetallic compound structure, effectively controlling the particle size of the intermetallic compound, and improving the crystallinity of the alloy material. The resulting catalyst has an ordered particle structure, high ORR activity, and high stability. Detailed Implementation

[0051] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention in any way.

[0052] Example 1

[0053] This embodiment provides a method for preparing a platinum-based alloy catalyst, the method comprising the following steps:

[0054] (1) Dissolve 0.075 mM platinum salt, 0.025 mM M1 metal salt and 0.005 mM M2 metal salt in a solution containing organic matter to obtain mixture A. Mix the carbon support and solvent to obtain mixture B. Then mix mixture A and mixture B to obtain mixture C. After ultrasonic dispersion of mixture C, a hydrogel is obtained.

[0055] In the mixture C, the concentration of organic matter is 2.2 mg·mL. -1 In mixture B, the carbon support content is 16 mg / mL.-1 The molar ratio of M1 metal salt, M2 metal salt, and platinum salt is 0.25:0.05:0.75.

[0056] The platinum salt is chloroplatinic acid, the M1 metal salt is cobalt nitrate, the M2 metal salt is nickel nitrate, the solution containing organic matter is a PVA solution, the carbon support is Ketjen black, and the solvent is water.

[0057] (2) Freeze-dry the hydrogel obtained in step (1) for 24 hours to obtain aerogel;

[0058] (3) The aerogel described in step (2) is kept at 700°C for 2 hours in a mixed atmosphere of argon and hydrogen with a volume ratio of 20:1, then cooled to 300°C at a rate of 1°C / min, and then naturally cooled to room temperature. Finally, it is subjected to acid washing, filtration, water washing and drying to obtain the platinum-based alloy catalyst. The platinum-based alloy catalyst includes PtM1M2@Pt particles, wherein Pt is the outer shell and PtM1M2 is the core.

[0059] The pickling solution used is nitric acid with a concentration of 1 mol / L.

[0060] Example 2

[0061] This embodiment provides a method for preparing a platinum-based alloy catalyst, the method comprising the following steps:

[0062] (1) Dissolve 0.085 mM platinum salt, 0.02 mM M1 metal salt and 0.008 mM M2 metal salt in a solution containing organic matter to obtain mixture A. Mix the carbon support and solvent to obtain mixture B. Then mix mixture A and mixture B to obtain mixture C. After ultrasonic dispersion of mixture C, the hydrogel is obtained.

[0063] In the mixture C, the concentration of organic matter is 0.8 mg·mL. -1 In mixture B, the carbon support content is 16 mg / mL. -1 The molar ratio of M1 metal salt, M2 metal salt, and platinum salt is 0.2:0.08:0.85.

[0064] The platinum salt is chloroplatinic acid, the M1 metal salt is cobalt nitrate, the M2 metal salt is nickel nitrate, the solution containing organic matter is a PVA solution, the carbon support is Ketjen black, and the solvent is water.

[0065] (2) Freeze-dry the hydrogel obtained in step (1) for 18 hours to obtain aerogel;

[0066] (3) The aerogel obtained in step (2) is kept at 800°C for 1 hour in a mixed atmosphere of argon and hydrogen with a volume ratio of 8:1, then cooled to 350°C at a rate of 0.5°C / min, and then naturally cooled to room temperature. Finally, it is subjected to acid washing, filtration, water washing and drying in sequence to obtain the platinum-based alloy catalyst. The platinum-based alloy catalyst includes PtM1M2@Pt particles, wherein Pt is the outer shell and PtM1M2 is the core.

[0067] The pickling solution used is sulfuric acid with a concentration of 0.5 mol / L.

[0068] Example 3

[0069] This embodiment provides a method for preparing a platinum-based alloy catalyst, the method comprising the following steps:

[0070] (1) Dissolve 0.06 mM platinum salt, 0.06 mM M1 metal salt and 0.002 mM M2 metal salt in a solution containing organic matter to obtain mixture A. Mix the carbon support and solvent to obtain mixture B. Then mix mixture A and mixture B to obtain mixture C. After ultrasonic dispersion of mixture C, the hydrogel is obtained.

[0071] In the mixture C, the concentration of organic matter is 3.5 mg·mL. -1 In mixture B, the carbon support content is 16 mg / mL. -1 The molar ratio of M1 metal salt, M2 metal salt, and platinum salt is 0.6:0.02:0.6.

[0072] The platinum salt is chloroplatinic acid, the M1 metal salt is palladium nitrate, the M2 metal salt is copper nitrate, the solution containing organic matter is PVA solution, the carbon support is acetylene black, and the solvent is water.

[0073] (2) Freeze-dry the hydrogel obtained in step (1) for 30 hours to obtain an aerogel;

[0074] (3) The aerogel obtained in step (2) is kept at 600°C for 1-3 hours in a mixed atmosphere of argon and hydrogen with a volume ratio of 5:1, then cooled to 250°C at a rate of 1.5°C / min, and then naturally cooled to room temperature. Finally, it is subjected to acid washing, filtration, water washing and drying in sequence to obtain the platinum-based alloy catalyst. The platinum-based alloy catalyst includes PtM1M2@Pt particles, wherein Pt is the outer shell and PtM1M2 is the core.

[0075] The pickling solution used is nitric acid with a concentration of 1.5 mol / L.

[0076] Example 4

[0077] This embodiment provides a method for preparing a platinum-based alloy catalyst, wherein, except for step (1), the concentration of organic matter in mixture C is 0.3 mg·mL. -1 Except for the above, everything else is the same as in Example 1.

[0078] Example 5

[0079] This embodiment provides a method for preparing a platinum-based alloy catalyst, wherein, except for step (1), the concentration of organic matter in mixture C is 5 mg·mL⁻¹. -1 Except for the above, everything else is the same as in Example 1.

[0080] Example 6

[0081] This embodiment provides a method for preparing a platinum-based alloy catalyst. Except for step (1), in which 0.075 mM platinum salt, 0.025 mM M1 metal salt, 0.005 mM M2 metal salt, carbon support and solvent are directly ultrasonically dispersed to obtain hydrogel, the preparation method is the same as in Example 1.

[0082] Example 7

[0083] This embodiment provides a method for preparing a platinum-based alloy catalyst. Except for the molar ratio of M1 metal salt, M2 metal salt and platinum salt in step (1) being 0.1:0.005:0.95, and the amount of M1 metal salt, M2 metal salt and platinum salt being adjusted adaptively, the preparation method is the same as in Example 1.

[0084] Example 8

[0085] This embodiment provides a method for preparing a platinum-based alloy catalyst. Except for the molar ratio of M1 metal salt, M2 metal salt and platinum salt in step (1) being 0.65:0.1:0.45, and the amount of M1 metal salt, M2 metal salt and platinum salt being adjusted adaptively, the preparation method is the same as in Example 1.

[0086] Example 9

[0087] This embodiment provides a method for preparing a platinum-based alloy catalyst. Except for step (3), which involves cooling at a rate of 0.1 °C / min, the preparation method is the same as in Example 1.

[0088] Example 10

[0089] This embodiment provides a method for preparing a platinum-based alloy catalyst. Except for step (3), which involves cooling at a rate of 3°C / min, the preparation method is the same as in Example 1.

[0090] Example 11

[0091] This embodiment provides a method for preparing a platinum-based alloy catalyst. Except for step (3), in which the temperature is reduced to 450°C at a rate of 1°C / min, the preparation method is the same as in Example 1.

[0092] Example 12

[0093] This embodiment provides a method for preparing a platinum-based alloy catalyst. Except for step (3), in which the temperature is reduced to 150°C at a rate of 1°C / min, the preparation method is the same as in Example 1.

[0094] Example 13

[0095] This embodiment provides a method for preparing a platinum-based alloy catalyst. The preparation method is the same as that in Example 1, except that step (3) does not involve acid washing.

[0096] Example 14

[0097] This embodiment provides a method for preparing a platinum-based alloy catalyst. Except for step (3), where the pickling solution is nitric acid with a concentration of 4 mol / L, the preparation method is the same as in Example 1.

[0098] Example 15

[0099] This embodiment provides a method for preparing a platinum-based alloy catalyst. Except for step (1), where the organic compound is polyethylene glycol, the preparation method is the same as in Example 1.

[0100] Comparative Example 1

[0101] This comparative example provides a method for preparing a platinum-based alloy catalyst, which is the same as that in Example 1 except that no organic matter is added in step (1).

[0102] Comparative Example 2

[0103] This comparative example provides a method for preparing a platinum-based alloy catalyst. The preparation method is the same as in Example 1, except that step (2) is not freeze-dried but heated and dried at 100°C.

[0104] The particle size distribution range and Pt shell thickness of the supported alloy particles in the platinum-based alloy catalysts obtained in the above examples and comparative examples are shown in Table 1. Meanwhile, the platinum-based alloy catalysts obtained in the above examples and comparative examples were uniformly dispersed in ethanol, water, and Nafion solution to obtain a dispersion. The dispersion was drop-coated onto a rotating disk electrode to form a working electrode, which was then air-dried and used for the ORR reaction. The electrolyte solution was 0.1 mol / L HClO4, and the test voltage range was 0.1 V-1.1 V (vs RHE). The obtained ORR half-wave potential is shown in Table 1. The stability of the platinum-based alloy catalyst was then tested. After 20,000 cycles in O2-saturated 0.1 mol / L HClO4 within a voltage range of 0.6-1.0 V, the ORR half-wave potential of the catalyst was measured.

[0105] Table 1

[0106]

[0107]

[0108] As can be seen from the table above:

[0109] (1) The platinum-based alloy catalyst obtained by this invention has an ordered structure, uniform particle size distribution of the supported alloy particles, and a Pt shell of a specific thickness on the surface. Therefore, the obtained catalyst has excellent electrochemical performance and high stability. As can be seen from Example 1 and Comparative Examples 1-2, the gel method of this invention for preparing intermetallic compounds can obtain ternary alloy catalysts with ordered structure, uniform particle size distribution, excellent electrochemical performance, and high stability. As can be seen from Example 1 and Examples 4-5, the concentration of organic matter in mixture C affects the formation of hydrogel and the dispersibility of metal salts.

[0110] (2) As can be seen from Examples 1 and 6, the mixing method of the raw materials of the present invention will affect the dispersibility and the performance of the obtained alloy catalyst; As can be seen from Examples 1 and 7-8, the molar ratio of M1 metal salt, M2 metal salt and platinum salt will affect the composition of the ternary intermetallic compound, thereby affecting the electrochemical performance of the product; As can be seen from Examples 1 and 9-12, the annealing conditions will affect the formation of the alloy catalyst; As can be seen from Examples 1 and 13-14, acid washing with dilute acid can wash away M1 and M2 on the surface of the alloy catalyst particles, so that the catalyst particles form a core-shell structure, while a high concentration of acid washing solution will affect the stability of the catalyst particles, dissolve the non-precious metals inside the alloy, affect the formation of a reasonable core-shell structure, and thus affect the performance of the product; As can be seen from Examples 1 and 15, PVA has the advantage of promoting the dispersion of metal salts.

[0111] In summary, this invention provides a platinum-based alloy catalyst, its preparation method, and its application. The platinum-based alloy catalyst obtained by the preparation method has an ordered structure, which can solve the problem of easy dissolution of non-precious metals in conventional alloy catalysts, effectively control the catalyst particle size, and enable the atoms in the metal alloy to be arranged in an orderly manner. Therefore, the obtained catalyst has excellent electrochemical performance and high stability.

[0112] The above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A method for preparing a platinum-based alloy catalyst, characterized in that, The preparation method includes the following steps: (1) A hydrogel is obtained by mixing a platinum salt, a metal salt of M, an organic substance, a carbon support, and a solvent; wherein M includes metals other than Pt. The mixing in step (1) includes first dissolving platinum salt and M metal salt in a solution containing organic matter to obtain mixture A, then mixing carbon support and solvent to obtain mixture B, then mixing mixture A and mixture B to obtain mixture C, and then ultrasonically dispersing mixture C to obtain the hydrogel. (2) Freeze-dry the hydrogel obtained in step (1) to obtain an aerogel; (3) Anneal and post-treat the aerogel obtained in step (2) to obtain the platinum-based alloy catalyst; The annealing in step (3) includes first holding at a temperature of 600-800℃, and then cooling down to 250-350℃ at a rate of 0.5-1.5℃ / min; The organic compound in step (1) includes any one or a combination of at least two of PVA, PPG, PEG or citric acid; In the mixture C, the concentration of organic matter is 0.8-3.5 mg·mL. -1 ; The M metal salt in step (1) includes a combination of at least two metal salts other than platinum; The M metal salt in step (1) includes a combination of M1 metal salt and M2 metal salt, wherein M1 and M2 are different types of metals; The molar ratio of M1 metal salt, M2 metal salt and platinum salt is (0.2-0.6):(0.02-0.08):(0.6-0.85).

2. The preparation method according to claim 1, characterized in that, The organic compound mentioned in step (1) is PVA.

3. The preparation method according to claim 1, characterized in that, M1 and M2 are each independently selected from any one or at least a combination of two of Fe, Co, Ni, Cu, Mn, Cr, Pd, Ir, Ru, La, Ce, Gd or Ti.

4. The preparation method according to claim 1, characterized in that, The platinum salt in step (1) includes chloroplatinic acid.

5. The preparation method according to claim 1, characterized in that, The carbon support in step (1) includes any one or a combination of at least two of Ketjen black, acetylene black, graphene, or carbon nanotubes.

6. The preparation method according to claim 1, characterized in that, The solvent in step (1) includes water.

7. The preparation method according to claim 1, characterized in that, The freeze-drying time in step (2) is 18-30 hours.

8. The preparation method according to claim 1, characterized in that, The heat preservation time is 1-3 hours.

9. The preparation method according to claim 1, characterized in that, The temperature is lowered to 250-350℃ and then allowed to cool naturally to room temperature.

10. The preparation method according to claim 1, characterized in that, The annealing atmosphere comprises a mixture of inert and reducing gases.

11. The preparation method according to claim 1, characterized in that, The post-processing in step (3) includes pickling, solid-liquid separation, water washing and drying performed sequentially.

12. The preparation method according to claim 11, characterized in that, The concentration of the pickling solution used in the pickling process is 0.5-1.5 mol / L.

13. The preparation method according to claim 11, characterized in that, The pickling solution used in the pickling process includes nitric acid and / or sulfuric acid.

14. The preparation method according to claim 1, characterized in that, The preparation method includes the following steps: (1) Dissolve platinum salt, M1 metal salt and M2 metal salt in a solution containing organic matter to obtain mixture A, then mix carbon support and solvent to obtain mixture B, then mix mixture A and mixture B to obtain mixture C, and then ultrasonically disperse mixture C to obtain hydrogel; In the mixture C, the concentration of organic matter is 0.8-3.5 mg·mL. -1 The molar ratio of M1 metal salt, M2 metal salt, and platinum salt is (0.2-0.6):(0.02-0.08):(0.6-0.85). (2) Freeze-dry the hydrogel obtained in step (1) for 18-30 hours to obtain an aerogel; (3) The aerogel described in step (2) is kept at a temperature of 600-800℃ for 1-3 hours in a mixed atmosphere of inert gas and reducing gas, then cooled to 250-350℃ at a rate of 0.5-1.5℃ / min, and then naturally cooled to room temperature. Finally, acid washing, solid-liquid separation, water washing and drying are performed in sequence to obtain the platinum-based alloy catalyst. The concentration of the pickling solution used in pickling is 0.5-1.5 mol / L.

15. A platinum-based alloy catalyst, characterized in that, The platinum-based alloy catalyst is obtained by the preparation method described in any one of claims 1-14.

16. The platinum-based alloy catalyst according to claim 15, characterized in that, The platinum-based alloy catalyst comprises PtM1M2@Pt particles, which have a core-shell structure, wherein the outer shell comprises Pt and the core comprises Pt, M1 and M2 alloy.

17. The platinum-based alloy catalyst according to claim 16, characterized in that, The particle size distribution range of the PtM1M2@Pt particles is 2-6 nm.

18. The platinum-based alloy catalyst according to claim 16, characterized in that, The outer shell of the PtM1M2@Pt particles has a thickness of 2-5 Pt atomic layers.

19. The platinum-based alloy catalyst according to claim 16, characterized in that, The thickness of the outer shell of the PtM1M2@Pt particles is 0.8-1.2 nm.

20. The application of a platinum-based alloy catalyst as described in any one of claims 15-19, characterized in that, The applications include those for fuel cells.

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