A method for preparing a small-size, carbon-coated platinum-based alloy catalyst

Abstract

The application discloses a preparation method of a small-size carbon-coated platinum-based alloy catalyst. The method comprises the following steps: (1) adding carbon powder, solid organic matter and metal precursors into an organic solvent to obtain a mixed solution; (2) oil-bathing the mixed solution at 120-220 DEG C for 0.5-24 hours to obtain a platinum-based catalyst reaction solution; (3) centrifuging, cleaning and drying the platinum-based catalyst reaction solution to obtain catalyst powder; and (4) placing the catalyst powder into a heating tube of a high-pressure furnace, annealing the catalyst powder at 400-900 DEG C under a pressure of 0.2-50 MPa for 0.5-24 hours to obtain the small-size carbon-coated platinum-based alloy catalyst. The obtained catalyst has high electrochemical active area and mass activity, and the electrochemical active area and the mass activity do not obviously decrease after 30000 cycles of test.

Description

Technical Field

[0001] This invention relates to the field of preparation technology of platinum-based catalysts for proton exchange membrane fuel cells, and specifically to a method for preparing a small-sized, carbon-coated platinum-based alloy catalyst. Background Technology

[0002] With the rapid development of the global economy, the consumption of fossil fuels such as coal, oil, and natural gas, which are the main energy sources, has increased dramatically. As traditional fossil fuels become increasingly scarce and environmental pollution intensifies, the need for new clean energy sources continues to grow. Hydrogen energy technology is one of the key technologies for achieving carbon peaking and carbon neutrality, and it is also an important carrier for achieving green and low-carbon transformation at the energy end. Proton exchange membrane fuel cell technology, as the core technology of the hydrogen energy industry, has advantages such as cleanliness, high efficiency, and high power density, and has become a research hotspot in recent years. However, current fuel cell catalysts are still mainly composed of the precious metal platinum, which is costly. To further reduce catalyst costs and the amount of precious metal used, transition metals are usually added as a second metal element to Pt-based catalysts. By utilizing ligand effects and stress effects, the activity and stability of the catalyst can be improved while reducing the amount of platinum used.

[0003] Currently, most widely reported platinum-based alloy catalysts involve directly loading nanoparticles onto carbon supports. During the reaction, the dissolution of transition metals easily occurs, leading to a decrease in catalytic activity and stability, severely hindering the development of proton exchange membrane fuel cells. A more efficient method is to use carbon coating to protect the alloy particles. In published patents, for example, patent CN 112242530 A proposes a method for preparing a high-stability, low-loading carbon-coated platinum catalyst. This involves ultrasonically mixing synthesized oleylamine-coated platinum nanoparticles with Ketjen black, evaporating the mixture, and then performing ligand pre-crosslinking, carbonization, and high-temperature activation to complete the preparation of the carbon-coated platinum catalyst. However, the organic materials used are expensive, and multiple heat treatments are required in subsequent steps, making the process complex. Summary of the Invention

[0004] The purpose of this invention is to address the limitations of current technologies by providing a method for preparing small-sized, carbon-coated platinum-based alloy catalysts. This method introduces a high-pressure process during thermal annealing. In this high-pressure environment, atomic migration and movement on the particle surface are slowed down, successfully preparing a small-sized, carbon-coated platinum-based alloy catalyst. The catalyst prepared by this method has a small particle size, which facilitates the exposure of more active sites, and the sites are uniformly distributed. It also exhibits a high degree of alloying, and the carbon shell on the particle surface inhibits the dissolution of transition metals, further improving the catalyst's activity and stability.

[0005] The technical solution of this invention is as follows:

[0006] A method for preparing a small-sized, carbon-coated platinum-based alloy catalyst, the method comprising the following steps:

[0007] (1) Add carbon powder, solid organic matter and metal precursor to an organic solvent to obtain a mixed solution.

[0008] The metal precursor is a platinum salt and a transition metal salt; the transition metal salt includes one or more soluble salts of Fe, Co, Ni, Cu, and Zn.

[0009] The platinum salt is one of platinum acetylacetonate, chloroplatinic acid, and chloroplatinic acid amine; the mass ratio of platinum salt to transition metal salt is 1:0.1 to 1:3; the mass ratio of carbon powder to solid organic matter is 1:5 to 1:15; 1 to 3 mg of platinum salt is added per 1 mL of organic solvent;

[0010] The toner is one of Ketjen Black ECP600JD, Ketjen Black EC-600J, Ketjen Black EC-300J, BP2000, or XC-72R; the solid organic matter is potassium diformate or benzoic acid; and the organic solvent is one of benzyl alcohol, phenylethanol, phenylpropanol, N,N dimethylformamide, ethylene glycol, or glycerol.

[0011] (2) Disperse the mixed solution by ultrasonication for 30-60 min, and then in an oil bath at 120-220℃ for 0.5-24 h to obtain the platinum-based catalyst reaction solution.

[0012] (3) Centrifuge, wash and dry the platinum-based catalyst reaction solution to obtain catalyst powder.

[0013] The centrifuge operates at a speed of 8000–10000 r / min, for 5–10 min, 2–3 cycles.

[0014] (4) The catalyst powder is placed in the heating tube of a high-pressure furnace and annealed at 400-900℃ and 0.2MPa-50MPa for 0.5-24h to obtain a small-sized, carbon-coated platinum-based alloy catalyst.

[0015] The annealing atmosphere is one of argon, nitrogen, a mixture of hydrogen and argon, or a mixture of hydrogen and nitrogen.

[0016] The particle size of the platinum-based alloy nanoparticles is 1–5 nm;

[0017] In the platinum-based alloy catalyst, the noble metal platinum accounts for 10% to 70% of the catalyst loading;

[0018] The small-sized, carbon-coated platinum-based alloy catalyst is used as the cathode oxygen reduction catalyst in a proton exchange membrane fuel cell.

[0019] The essential features of this invention are:

[0020] This invention employs a solvothermal method combined with a high-pressure, high-temperature annealing process to prepare platinum-based alloy catalysts. Unlike traditional solvothermal methods, which can cause Ostwald ripening and particle agglomeration during heat treatment, the high-pressure annealing process used in this preparation method slows down atomic migration and movement on the particle surface, successfully producing small-sized, carbon-coated platinum-based alloy catalysts with high alloying degree, uniform particle dispersion, and small size. This facilitates the exposure of active sites, increasing the electrochemical active area. Furthermore, the carbon shell coating inhibits the dissolution of transition metals, thus improving the catalyst's activity and stability.

[0021] The beneficial effects of this invention are as follows:

[0022] (1) This invention discloses a method for preparing a small-sized, carbon-coated platinum-based alloy catalyst. This method has the advantages of simple operation and low production cost, and can be widely used in proton exchange membrane fuel cells.

[0023] (2) The present invention introduces a high-pressure process in the final heat treatment process. The high-pressure environment slows down the atomic migration and atomic movement on the particle surface, successfully inhibits the agglomeration and growth of particles during the heat treatment process, which is conducive to the exposure of active sites and greatly improves the activity of the catalyst.

[0024] (3) Under high pressure conditions, the organic matter of the catalyst prepared by the present invention decomposes to form a carbon shell, which inhibits the agglomeration and growth of particles. Thus, during the electrochemical test, the dissolution of transition metals can be suppressed, the catalytic performance of the catalyst can be better maintained, and the service life of the catalyst can be extended.

[0025] (4) The small-sized, carbon-coated platinum-based alloy catalyst prepared by the present invention has carbon-coated nanoparticles uniformly dispersed on a carbon support, with a particle size of 1 to 5 nm.

[0026] (5) The catalyst of the present invention has high electrochemical active area and mass activity. After 30,000 cycles, the electrochemical active area and mass activity did not decrease significantly. Attached Figure Description

[0027] Figure 1 The image shows the transmission electron microscope (TEM) spectrum of the platinum-based alloy catalyst prepared in Example 2.

[0028] Figure 2 The image shows the transmission electron microscope (TEM) spectrum of the platinum-based alloy catalyst prepared in Example 3.

[0029] Figure 3 This is a transmission electron microscope (TEM) image of the platinum-based alloy catalyst prepared in Example 4.

[0030] Figure 4This is a high-resolution transmission electron microscope image of the platinum-based alloy catalyst prepared in Example 4.

[0031] Figure 5 The oxygen reduction polarization (ORR) curves for Example 4 and the commercial Pt / C catalyst are shown.

[0032] Figure 6 The cyclic voltammetry (CV) curves and oxygen reduction polarization (ORR) curves of the platinum-based alloy catalyst prepared in Example 4 before and after the 30,000-cycle accelerated durability test (ADT). Detailed Implementation

[0033] The following embodiments further illustrate the content of the present invention, but should not be construed as limiting the present invention. Any modifications and substitutions made to the methods, steps, or conditions of the present invention without departing from the spirit and essence of the present invention are within the scope of the present invention.

[0034] Unless otherwise specified, the technical means used in the embodiments are conventional means well known to those skilled in the art.

[0035] Example 1

[0036] (1) Using a four-position electronic balance with the level adjusted, weigh 10.0 mg of Ketjen Black ECP600JD, 120.0 mg of potassium diformate, 20.0 mg of chloroplatinic acid (containing 7.6 mg of platinum), and 9.0 mg of ferric chloride hexahydrate and put them into a glass bottle. Then, use a 5.0 mL pipette to add 10.0 mL of benzyl alcohol in two portions and mix them evenly.

[0037] (2) Place the glass bottle in an ultrasonic machine and sonicate for 30 minutes until the drug is completely dissolved. While waiting for the ultrasonication, turn on the oil bath heating device, set the bottom plate temperature to 240℃ and the target temperature to 190℃, and start heating. Place the drug that has been sonicated for 30 minutes into a silicone oil bath and react for 2 hours.

[0038] (3) After the reaction is complete, remove the glass bottle from the oil bath and allow it to cool to room temperature in the air. Then, take 5.0 mL of the reaction product and place it into two centrifuge tubes, adding anhydrous ethanol until the contents reach 8.0 mL. First, sonicate to homogenize, then wash repeatedly three times using a centrifuge (10000 r / min, 5 min), dry, and scrape off to obtain catalyst powder.

[0039] (4) The catalyst powder was loaded into a crucible, then wrapped with copper foil, and placed in the heating tube of a high-pressure furnace. The heating rate was set to 5℃ / min, and the furnace was treated at 0.2MPa, 500℃, and 2h in a N2 atmosphere. Finally, a small-sized, carbon-coated platinum-based alloy catalyst was obtained (the noble metal platinum accounted for 38% of the catalyst loading in the prepared platinum-based alloy catalyst).

[0040] Example 2

[0041] (1) Using a four-position electronic balance with the level adjusted, weigh 10.0 mg of Ketjen Black ECP600JD, 120.0 mg of benzoic acid, 20.0 mg of acetylacetone platinum (containing 10.0 mg of metallic platinum), and 9.0 mg of cobalt acetate and put them into a glass bottle. Then, use a 5.0 mL pipette to add 10.0 mL of NN dimethylformamide in two portions and mix them evenly.

[0042] (2) Place the glass bottle in an ultrasonic machine and sonicate for 30 minutes until the drug is completely dissolved. While waiting for the ultrasonication, turn on the oil bath heating device, set the bottom plate temperature to 240℃ and the target temperature to 190℃, and start heating. Place the drug that has been sonicated for 30 minutes into a silicone oil bath and react for 2 hours.

[0043] (3) After the reaction is complete, remove the glass bottle from the oil bath and allow it to cool to room temperature in the air. Then, take 5.0 mL of the reaction product and place it into two centrifuge tubes, adding anhydrous ethanol until the contents reach 8.0 mL. First, sonicate to homogenize, then wash repeatedly three times using a centrifuge (10000 r / min, 5 min), dry, and scrape off to obtain catalyst powder.

[0044] (4) The catalyst powder was loaded into a crucible, then wrapped with copper foil, and placed in the heating tube of a high-pressure furnace. The heating rate was set to 5℃ / min, and the furnace was treated at 0.5MPa, 600℃, and 5h in an Ar atmosphere. Finally, a small-sized, carbon-coated platinum-based alloy catalyst was obtained (the noble metal platinum accounted for 43% of the catalyst loading in the prepared platinum-based alloy catalyst).

[0045] A layer of filter paper was placed in a petri dish, and a copper mesh was placed on the filter paper. Then, a small amount of carbon powder was dissolved in anhydrous ethanol to obtain a slightly translucent catalyst solution. The solution was drawn up with a pipette and dropped onto the copper mesh. The solution was then dried under an infrared lamp. The morphology of the prepared sample was characterized under a transmission electron microscope to obtain a transmission electron microscope (TEM) spectrum.

[0046] from Figure 1 As can be seen from the data, the prepared small-sized, carbon-coated platinum-based alloy catalyst has the characteristics of small particles, uniform dispersion, and no obvious agglomeration.

[0047] Example 3

[0048] (1) Using a four-position electronic balance with the level adjusted, weigh 10.0 mg of BP2000 toner, 120.0 mg of benzoic acid, 20.0 mg of chloroplatinic acid (containing 8.8 mg of platinum), and 9.0 mg of cobalt acetate and put them into a glass bottle. Then, use a 5.0 mL pipette to add 10.0 mL of ethylene glycol in two portions and mix them evenly.

[0049] (2) Place the glass bottle in an ultrasonic machine and sonicate for 30 minutes until the drug is completely dissolved. While waiting for the sonication, turn on the oil bath heating device, set the bottom plate temperature to 240℃ and the target temperature to 200℃, and start heating. Place the drug that has been sonicated for 30 minutes into a silicone oil bath and react for 2 hours.

[0050] (3) After the reaction is complete, remove the glass bottle from the oil bath and allow it to cool to room temperature in the air. Then, take 5.0 mL of the reaction product and place it into two centrifuge tubes, adding anhydrous ethanol until the contents reach 8.0 mL. First, sonicate to homogenize, then wash repeatedly three times using a centrifuge (10000 r / min, 5 min), dry, and scrape off to obtain catalyst powder.

[0051] (4) The catalyst powder was loaded into a crucible, then wrapped with copper foil, and placed in the heating tube of a high-pressure furnace. The heating rate was set to 5℃ / min, and the mixture was treated at 1MPa, 700℃, and 7h in a hydrogen-argon mixed atmosphere. Finally, a small-sized, carbon-coated platinum-based alloy catalyst was obtained (the noble metal platinum accounted for 40% of the catalyst loading in the prepared platinum-based alloy catalyst).

[0052] The morphological characterization method is the same as in Example 2, and the results correspond to Figure 2 .

[0053] from Figure 2 As can be seen, the prepared small-sized, carbon-coated platinum-based alloy catalyst has the characteristics of small particle size, uniform dispersion, and no obvious agglomeration, with an average particle size of only 1-5 nm.

[0054] Example 4

[0055] (1) Using a four-position electronic balance with the level adjusted, weigh 10.0 mg of Ketjen Black ECP600JD, 120.0 mg of benzoic acid, 20.0 mg of platinum acetylacetonate (containing 10.0 mg of metallic platinum), and 9.0 mg of cobalt acetate into a glass bottle. Then, use a 5.0 mL pipette to add 10.0 mL of benzyl alcohol in two portions and mix them thoroughly.

[0056] (2) Place the glass bottle in an ultrasonic machine and sonicate for 30 minutes until the drug is completely dissolved. While waiting for the ultrasonication, turn on the oil bath heating device, set the bottom plate temperature to 240℃ and the target temperature to 190℃, and start heating. Place the drug that has been sonicated for 30 minutes into a silicone oil bath and react for 2 hours.

[0057] (3) After the reaction is complete, remove the glass bottle from the oil bath and allow it to cool to room temperature in the air. Then, take 5.0 mL of the reaction product and place it into two centrifuge tubes, adding anhydrous ethanol until the contents reach 8.0 mL. First, sonicate to homogenize, then wash repeatedly three times using a centrifuge (10000 r / min, 5 min), dry, and scrape off to obtain catalyst powder.

[0058] (4) The catalyst powder was loaded into a crucible, then wrapped with copper foil, and placed in the heating tube of a high-pressure furnace. The heating rate was set to 5℃ / min, and the furnace was treated at 2MPa, 600℃ for 2h in a N2 atmosphere. Finally, a small-sized, carbon-coated platinum-based alloy catalyst was obtained (the noble metal platinum accounted for 43% of the catalyst loading in the prepared platinum-based alloy catalyst).

[0059] The morphological characterization method is the same as in Example 2, and the results correspond to Figure 3 .

[0060] from Figure 3 As can be seen, the prepared small-sized, carbon-coated platinum-based alloy catalyst has the characteristics of small particle size, uniform dispersion, and no obvious agglomeration, with an average particle size of only 1-5 nm.

[0061] Figure 4 The image shown is a high-resolution transmission electron microscope image of the prepared platinum-based alloy catalyst, illustrating that the platinum-based alloy catalyst prepared in this invention is coated with a uniform carbon shell on the outer layer.

[0062] Performance testing methods:

[0063] 1. (1) Weigh 2.0 mg of the platinum-based catalyst finally prepared in Example 4 and add it to a mixed solution of 1.0 mL isopropanol (625.0 μL), Nafion (20.0 μL), and deionized water (355.0 μL). After ultrasonic dispersion for 30 min, a uniformly mixed ink is obtained. (2) Use a pipette with a range of 10.0 μL to take 4.0 μL of ink and drop it evenly onto a glassy carbon rotating disk electrode, and wait for it to air dry naturally. (3) Use this as the working electrode, the platinum wire as the counter electrode, and the reversible hydrogen electrode as the reference electrode. First, scan the catalyst in an argon-saturated 0.1 mol / L perchloric acid solution from an initial potential of 0 V to 1.25 V at a scan rate of 100 mV / s for 40 cycles to achieve the purpose of activating the catalyst. Then, the cyclic voltammetry curve was obtained by scanning three times from the initial potential of 0.05V to 1.25V at a scan rate of 50mV / s and selecting the middle scan for plotting. (4) Subsequently, the oxygen reduction polarization (ORR) curve of the platinum-based catalyst was obtained by scanning 0 to 1.05V at a scan rate of 10mV / s and a rotating electrode speed of 1600rpm / min in an oxygen-saturated 0.1mol / L perchloric acid solution.

[0064] The electrochemical performance testing of commercial Pt / C followed the same procedure as described above, ultimately yielding the oxygen reduction polarization (ORR) curves for commercial Pt / C. The results are compared as follows: Figure 5 As shown.

[0065] from Figure 5As can be seen, the prepared small-sized, carbon-coated platinum-based alloy catalyst has a higher half-wave potential than commercial Pt / C, with the platinum-based alloy catalyst having a half-wave potential of 0.884 V and commercial Pt / C having a half-wave potential of 0.848 V. This indicates that the prepared small-sized, carbon-coated platinum-based alloy catalyst has better oxygen reduction activity than commercial Pt / C.

[0066] Table 1 compares the performance values ​​of Example 4 with those of commercial Pt / C.

[0067] Example 4 61.8 0.321 0.519 0.884 Commercial Pt / C 73.1 0.169 0.231 0.848

[0068] The data in Table 1 correspond to the numerical comparison of electrochemical active area, mass activity, area activity, and half-wave potential of platinum-based alloy catalysts and commercial Pt / C, respectively.

[0069] II. Electrochemical performance testing of platinum-based catalyst before cycling is the same as in (1)(2)(3)(4) above. (5) The working electrode is subjected to 30,000 cyclic voltammetric scans in an oxygen-saturated 0.1 mol / L perchloric acid solution, with a scan range of 0.6 V to 1.0 V and a scan rate of 100 mV / s. (6) The cyclic voltammetric (CV) curve and oxygen reduction polarization (ORR) curve are recorded after 30,000 cycles, and the results are compared as follows. Figure 6 ( Figure 6 a represents the cyclic volt-ampere (CV) curves before and after the cycle. Figure 6 b represents the oxygen reduction polarization (ORR) curves before and after the cycle.

[0070] from Figure 6 As can be seen, after 30,000 cycles, the hydrogen desorption peak area of ​​the prepared small-sized, carbon-coated platinum-based alloy catalyst did not change significantly, and the electrochemical active area did not decrease significantly, indicating that the catalyst did not exhibit significant agglomeration after cycling, and the catalytic activity did not decrease significantly. The polarization curves show that the half-wave potential decreased by only 0.004 V before and after cycling.

[0071] Table 2 shows the numerical comparison before and after the cycle in Example 4.

[0072] Example 4 61.8 0.321 0.519 0.884 30,000 CV cycles 55.4 0.306 0.552 0.880

[0073] The data in Table 2 correspond to the numerical comparison of electrochemical active area, mass activity, area activity and half-wave potential of platinum-based alloy catalysts before and after cycling.

[0074] Example 5

[0075] (1) Using a four-position electronic balance with the level adjusted, weigh 10.0 mg of BP2000 carbon powder, 120.0 mg of benzoic acid, 20.0 mg of chloroplatinic acid (containing 7.6 mg of platinum metal), and 9.0 mg of nickel nitrate hexahydrate and put them into a glass bottle. Then, use a 5.0 mL pipette to add 10.0 mL of benzyl alcohol in two portions and mix them evenly.

[0076] (2) Place the glass bottle in an ultrasonic machine and sonicate for 30 minutes until the drug is completely dissolved. While waiting for the ultrasonication, turn on the oil bath heating device, set the bottom plate temperature to 240℃ and the target temperature to 190℃, and start heating. Place the drug that has been sonicated for 30 minutes into a silicone oil bath and react for 2 hours.

[0077] (3) After the reaction is complete, remove the glass bottle from the oil bath and allow it to cool to room temperature in the air. Then, take 5.0 mL of the reaction product and place it into two centrifuge tubes, adding anhydrous ethanol until the contents reach 8.0 mL. First, sonicate to homogenize, then wash repeatedly three times using a centrifuge (10000 r / min, 5 min), dry, and scrape off to obtain catalyst powder.

[0078] (4) The catalyst powder was loaded into a crucible, then wrapped with copper foil, and placed in the heating tube of a high-pressure furnace. The heating rate was set to 5℃ / min, and the furnace was treated at 50MPa, 600℃ for 2h in a N2 atmosphere. Finally, a small-sized, carbon-coated platinum-based alloy catalyst was obtained (the noble metal platinum accounted for 39% of the catalyst loading in the prepared platinum-based alloy catalyst).

[0079] Example 6

[0080] (1) Using a properly leveled four-position electronic balance, weigh 10.0 mg of XC-72R carbon powder, 120.0 mg of benzoic acid, 20.0 mg of platinum acetylacetonate (containing 10.0 mg of metallic platinum), and 9.0 mg of cobalt sulfate into a glass bottle. Then, use a 5.0 mL pipette to add 10.0 mL of glycerol in two portions and mix them thoroughly.

[0081] (2) Place the glass bottle in an ultrasonic machine and sonicate for 30 minutes until the drug is completely dissolved. While waiting for the ultrasonication, turn on the oil bath heating device, set the bottom plate temperature to 240℃ and the target temperature to 190℃, and start heating. Place the drug that has been sonicated for 30 minutes into a silicone oil bath and react for 2 hours.

[0082] (3) After the reaction is complete, remove the glass bottle from the oil bath and allow it to cool to room temperature in the air. Then, take 5 mL of the reaction product and place it into two centrifuge tubes, adding anhydrous ethanol until the contents reach 8 mL. First, sonicate to homogenize, then wash repeatedly three times using a centrifuge (10000 r / min, 5 min). After drying, scrape off the product to obtain catalyst powder.

[0083] (4) The catalyst powder was loaded into a crucible, then wrapped with copper foil, and placed in the heating tube of a high-pressure furnace. The heating rate was set to 5℃ / min, and the mixture was treated at 3MPa, 650℃, and 10h in a hydrogen-nitrogen mixed atmosphere. Finally, a small-sized, carbon-coated platinum-based alloy catalyst was obtained (the noble metal platinum accounted for 42% of the catalyst loading in the prepared platinum-based alloy catalyst).

[0084] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements should also be considered within the scope of protection of the present invention.

[0085] Matters not covered in this invention are common knowledge.

Claims

1. A method for preparing a small-sized, carbon-coated platinum-based alloy catalyst, characterized in that: The method includes the following steps: (1) Add carbon powder, solid organic matter and metal precursor to an organic solvent to obtain a mixed solution; The metal precursor is a platinum salt and a transition metal salt; the transition metal salt includes one or more soluble salts of Fe, Co, Ni, Cu, and Zn; the mass ratio of the platinum salt to the transition metal salt is 1:0.1 to 1:3; the noble metal platinum accounts for 10% to 70% of the catalyst loading; the mass ratio of carbon powder to solid organic matter is 1:5 to 1:15; 1 to 3 mg of platinum salt is added per 1 mL of organic solvent; The solid organic compound is benzoic acid; (2) Disperse the mixed solution ultrasonically for 30-60 min, and then in an oil bath at 120-220℃ for 0.5-24 h to obtain the platinum-based catalyst reaction solution; (3) Centrifuge, wash and dry the platinum-based catalyst reaction solution to obtain catalyst powder; (4) The catalyst powder is placed in the heating tube of a high-pressure furnace and annealed at 400~900℃ and 0.5 MPa~3.0 MPa for 0.5~24 h to obtain a small-sized, carbon-coated platinum-based alloy catalyst. In the prepared small-sized, carbon-coated platinum-based alloy catalyst, the carbon-coated platinum-based alloy nanoparticles are dispersed on a carbon support, and the size of the platinum-based alloy nanoparticles is 1~5 nm.

2. The method for preparing the small-sized, carbon-coated platinum-based alloy catalyst as described in claim 1, characterized in that the platinum salt is one of platinum acetylacetonate, chloroplatinic acid, and amine chloroplatinic acid.

3. The method for preparing the small-sized, carbon-coated platinum-based alloy catalyst as described in claim 1, characterized in that: The toner is Ketjen Black ECP600JD, Ketjen Black EC-600J, Ketjen Black EC-300J, BP2000, or XC-72R; the organic solvent is benzyl alcohol, phenylethanol, phenylpropanol, N,N dimethylformamide, ethylene glycol, or glycerol.

4. The method for preparing the small-sized, carbon-coated platinum-based alloy catalyst as described in claim 1, characterized in that the centrifugation is performed at 8000~10000 r / min for 5~10 min, 2~3 times.

5. The method for preparing the small-sized, carbon-coated platinum-based alloy catalyst as described in claim 1, characterized in that the annealing atmosphere is one of argon, nitrogen, a hydrogen-argon mixture, or a hydrogen-nitrogen mixture.

6. The application of the small-sized, carbon-coated platinum-based alloy catalyst prepared by the method described in claim 1 as a catalyst for the oxygen reduction reaction at the cathode of a proton exchange membrane fuel cell.

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