Carbon-loaded small-size spherical platinum-based alloy catalyst as well as preparation method and application thereof

Abstract

The invention provides a carbon-loaded small-size spherical platinum-based alloy catalyst as well as a preparation method and application thereof, and belongs to the field of fuel cells. The carbon-loaded small-size spherical platinum-based alloy catalyst is synthesized by a one-step solvothermal reduction method. In the synthesis process of the platinum-copper alloy catalyst, the synthesis of spherical nanoparticles is realized by introducing gallium and gold and utilizing the induction effect of the gallium, and under the synergistic effect of the gallium and the gold, the agglomeration of platinum-based nanoparticles is inhibited, and the formation of small-size platinum-based alloy nanoparticles is realized; meanwhile, the introduction of gallium and gold leads to further decline of the d-band center of platinum, so that the electron structure of platinum is regulated and controlled to optimize the adsorption and desorption capability of platinum on the oxygen-containing intermediate. Under the combined action of size effect, morphology regulation and control and electronic structure optimization, the electro-catalytic oxygen reduction reaction performance of the catalyst is improved. The invention provides a method for regulating and controlling the size and morphology of the catalyst, and the catalyst is simple in preparation method and suitable for batch production and application.

Description

Technical Field

[0001] The present invention relates to a carbon-supported small-size spherical platinum-based alloy catalyst, a preparation method thereof and application thereof in oxygen reduction reactions in hydrogen fuel cells and methanol fuel cells, belonging to the fields of new energy catalytic materials, advanced precious metal materials and application technologies. Background Art

[0002] Fuel cells are gradually being regarded as viable green energy conversion devices to replace traditional fossil energy due to their clean and pollution-free characteristics, as well as their advantages such as low operating temperature, fast start and stop, high energy conversion efficiency and low noise, and therefore have received extensive attention. In fuel cell systems, platinum-based catalysts are key core components, and their performance and life play an important role in the cost and power generation efficiency of proton exchange membrane fuel cells (PEMFCs). At present, platinum-carbon catalysts are the most commonly used commercial fuel cell catalysts, but their catalytic performance still has a lot of room for improvement, and the high cost of platinum-carbon catalysts restricts the commercialization of the hydrogen fuel cell market. In order to improve the utilization rate of platinum and reduce the cost of catalysts, alloying platinum (Pt) with transition metals (M) to prepare low-platinum alloy catalysts is a feasible way.

[0003] Compared with platinum-carbon catalysts, the introduction of transition metals can easily lead to the agglomeration of platinum-based nanoparticles, the size of the synthesized platinum-based nanoparticles is too large, and the electrochemical active area is reduced. Moreover, the alloy particles formed by platinum and transition metals are irregular and uneven in size, resulting in the inability to fully express the advantages of alloying. Compared with low-platinum alloy catalysts, there is currently a lack of simple and effective methods for size and morphology control. Therefore, the synthesis of small-sized platinum-based alloy catalysts with regular morphology is an urgent problem to be solved for low-platinum catalysts. Summary of the invention

[0004] In view of the problems that the alloy catalysts are easy to agglomerate during the synthesis process, resulting in the disappearance of alloying advantages and the decline of catalytic performance, and the lack of simple and feasible morphology control means, the present invention provides a carbon-supported small-sized spherical platinum-based alloy catalyst and its preparation method and application. The present invention adopts a one-step solvent thermal reduction method to achieve the deposition of platinum-based alloy on a carbon black carrier. At the same time, gallium and gold are introduced in the synthesis process of the platinum-copper alloy catalyst. Gallium, as a morphology control agent, guides the formation of spherical platinum-based nanoparticles. The synergistic effect of gallium and gold inhibits the agglomeration of nanoparticles. Moreover, the simultaneous introduction of gallium and gold adjusts the electronic structure of platinum, induces a positive shift in the binding energy of platinum, and a decrease in the d-band center of platinum, thereby optimizing the adsorption and desorption performance of platinum for oxygen-containing intermediates. The method provided by the present invention achieves the size and morphology control of the platinum-based alloy, and significantly improves the electrocatalytic oxygen reduction reaction performance of the platinum-based alloy catalyst.

[0005] The purpose of the present invention is to provide a means for controlling the size and morphology of a platinum-based alloy catalyst. Gallium and gold are introduced during the synthesis process, gallium induces the formation of spherical alloy nanoparticles, and the synergistic effect of gallium and gold effectively inhibits the agglomeration of platinum-based alloy nanoparticles, thereby realizing the synthesis of small-sized spherical platinum-based alloy catalysts.

[0006] The carbon-supported small-sized spherical platinum-based alloy catalyst provided by the present invention exhibits high catalytic performance in the electrocatalytic oxygen reduction reaction. The catalyst is synthesized by a one-step method, has a simple preparation method, uses low-cost reagents, has low requirements on production equipment, and is suitable for large-scale batch production.

[0007] To achieve the above object, the present invention provides a method for preparing a carbon-supported small-sized spherical platinum-based alloy catalyst, comprising the following steps:

[0008] S1. treating the carbon black carrier at high temperature under an inert atmosphere to improve its graphitization degree, then performing an oxidation treatment to promote its surface functionalization, and obtaining a treated carbon black carrier after filtering, washing with deionized water and drying;

[0009] S2. After dispersing the treated carbon black carrier in a solvent and uniformly dispersing it by ultrasonic, a platinum precursor, a transition metal precursor and a gallium precursor are dissolved in a solvent and added to the above system, sodium hydroxide is added to adjust the pH of the solution system to alkaline, and then a gold precursor is dissolved in a solvent and added to the above system. After uniformly dispersing it by ultrasonic, it is placed in a reactor with mechanical stirring. After a certain period of high-temperature reaction, solid-liquid separation is achieved by a vacuum filter. After filtering, washing and drying, a carbon-supported small-sized spherical platinum-based alloy catalyst is obtained.

[0010] Furthermore, in step S2, the mass ratio of the platinum precursor, transition metal precursor, gallium precursor, gold precursor and treated carbon black carrier is (70-100): (5.4-23.2): (5-28.3): (0.6-9.7): (20.2-370.1).

[0011] Furthermore, in step S2, the solvent is one of ethylene glycol, propylene glycol, butylene glycol, ethylene glycol / water, propylene glycol / water, and butylene glycol / water, and the reaction temperature is 150-230°C.

[0012] Further, in step S2, the gallium precursor is one of gallium chloride, gallium nitrate, gallium sulfate, and gallium acetate; the gold precursor is one of chloroauric acid, potassium chloroaurate, sodium chloroaurate, and ammonium tetrachloroaurate.

[0013] Furthermore, in step S2, the platinum precursor is one of chloroplatinic acid, tetraammineplatinum nitrate, and ammonium chloroplatinite.

[0014] Furthermore, in step S2, the transition metal precursor is one of cupric chloride, cuprous chloride, cupric nitrate, cuprous nitrate, and cupric acetate.

[0015] Furthermore, in step S1, the carbon black carrier is one of commercial XC-72R conductive carbon black, acetylene black, Ketjen black, mesoporous carbon and BP-2000 porous carbon; the high temperature treatment temperature of the carbon black carrier is 2000-3000°C, and the treatment time is 1-5h.

[0016] Furthermore, in step S1, the oxidant is one of hydrogen peroxide, nitric acid and concentrated sulfuric acid; and the solid-liquid ratio of the carbon black carrier to the oxidant is 1 g: (20-200) ml.

[0017] The present invention also provides a carbon-supported small-sized spherical platinum-based alloy catalyst, which is prepared by the above-mentioned preparation method. The Pt content in the carbon-supported small-sized spherical platinum-based alloy catalyst is 10-40wt%, and the atomic ratio of Pt, transition metal, Ga, and Au is 3: (1-3): (0.5-2): (0.01-0.12); the average particle size of the nanoparticles in the catalyst is less than 3nm.

[0018] The aforementioned carbon-supported small-sized spherical platinum-based alloy catalyst is used in the oxygen reduction reaction of hydrogen fuel cells and methanol fuel cells.

[0019] The beneficial effects of the present invention are:

[0020] (1) The present invention provides a method for preparing a carbon-supported small-sized spherical platinum-based alloy catalyst. Small-sized spherical platinum-based alloy nanoparticles are prepared by a one-step solvent thermal reduction method without the need for post-treatment, thereby greatly improving the preparation efficiency of the catalyst.

[0021] (2) In the process of synthesizing the platinum-copper catalyst, the present invention achieves the regulation of the size and morphology of platinum-based alloy nanoparticles by introducing gallium and gold. The introduction of gallium can induce the formation of spherical nanoparticles. The synergistic effect of gallium and gold effectively inhibits the agglomeration of platinum-based alloy nanoparticles. In addition, the introduction of gallium and gold regulates the electronic structure of platinum, causes the d-band center of platinum to decrease, and optimizes the adsorption and desorption behavior of platinum on oxygen-containing intermediates.

[0022] (3) The present invention provides a carbon-supported small-sized spherical platinum-based alloy catalyst, in which platinum-based alloy nanoparticles are evenly distributed on the carbon support, and the size and morphology are controllable, and the catalyst has high catalytic performance in the electrocatalytic oxygen reduction reaction. At the same time, the catalyst preparation steps and production equipment are simple, and the chemical reagents used are cheap and readily available, which is suitable for large-scale batch production. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 N of the catalyst prepared in Example 1 of the present invention2 -CV curve.

[0024] Figure 2 N is the catalyst prepared in Comparative Example 1 2 -CV curve.

[0025] Figure 3 N is the catalyst prepared in Comparative Example 2 2 -CV curve.

[0026] Figure 4 N of the catalyst prepared in Comparative Example 3 2 -CV curve.

[0027] Figure 5 LSV polarization curves of the catalyst prepared in Example 1 of the present invention, the catalysts prepared in Comparative Examples 1-3, and the JM commercial platinum-carbon catalyst.

[0028] Figure 6 The XPS spectra of the catalysts prepared in Example 1 and Comparative Example 1 of the present invention are shown.

[0029] Figure 7 This is a TEM image of the catalyst prepared in Example 1 of the present invention.

[0030] Figure 8 This is the TEM image of the catalyst prepared in Comparative Example 1.

[0031] Fig. 9 This is the TEM image of the catalyst prepared in Comparative Example 2.

[0032] Fig.10 This is the TEM image of the catalyst prepared in Comparative Example 3. DETAILED DESCRIPTION

[0033] In order to make the purpose, technical solutions and advantages of the present invention more clear, the present invention is described in detail below with reference to the accompanying drawings and specific embodiments.

[0034] It should also be noted that, in order to avoid obscuring the present invention due to unnecessary details, only structures and / or processing steps closely related to the scheme of the present invention are shown in the drawings, while other details that are not closely related to the present invention are omitted.

[0035] In addition, it should be noted that the terms "comprises", "includes" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or apparatus that includes a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or apparatus.

[0036] At present, alloy catalysts are prone to agglomeration during the synthesis process, resulting in the disappearance of alloying advantages and a decrease in catalytic performance.

[0037] The present invention provides a method for preparing a carbon-supported small-sized spherical platinum-based alloy catalyst, comprising the following steps:

[0038] S1. treating the carbon black carrier at high temperature under an inert atmosphere to improve its graphitization degree, then performing an oxidation treatment to promote its surface functionalization, and obtaining a treated carbon black carrier after filtering, washing with deionized water and drying;

[0039] The carbon black carrier is one of commercial XC-72R conductive carbon black, acetylene black, Ketjen black, mesoporous carbon and BP-2000 porous carbon, preferably one of XC-72R, Ketjen black and mesoporous carbon.

[0040] The high temperature treatment temperature of the carbon black carrier is 2000-3000°C, and the treatment time is 1-5 hours, preferably 2600-2800°C, and the treatment time is preferably 1-3 hours.

[0041] The inert atmosphere is one of nitrogen, argon and helium, preferably argon.

[0042] The oxidant is one of hydrogen peroxide, nitric acid and concentrated sulfuric acid. The solid-liquid ratio of the carbon black carrier to the oxidant is 1g: (20-200)ml, preferably 1g: (30-100)ml.

[0043] S2. After dispersing the treated carbon black carrier in a solvent and uniformly dispersing it by ultrasonic, a platinum precursor, a transition metal precursor and a gallium precursor are dissolved in a solvent and added to the above system, sodium hydroxide is added to adjust the pH of the solution system to alkaline, and then a gold precursor is dissolved in a solvent and added to the above system. After uniformly dispersing it by ultrasonic, it is placed in a reactor with mechanical stirring. After a certain period of high-temperature reaction, solid-liquid separation is achieved by a vacuum filter. After filtering, washing and drying, a carbon-supported small-sized spherical platinum-based alloy catalyst is obtained.

[0044] Among them, the mass ratio of platinum precursor, transition metal precursor, gallium precursor, gold precursor and treated carbon black carrier is (70-100): (5.4-23.2): (5-28.3): (0.6-9.7): (20.2-370.1).

[0045] Specifically, the solvent is preferably one of ethylene glycol, propylene glycol, butanediol, ethylene glycol / water, propylene glycol / water, and butanediol / water. Ethylene glycol / water means that the system is mainly ethylene glycol, but also has a portion of water. For example, in Example 1, the carbon black carrier is dispersed in ethylene glycol, the platinum precursor and the copper precursor are dissolved in ethylene glycol, and the gallium precursor and the gold precursor are dissolved in water; the same is true for propylene glycol / water and butanediol / water, which will not be repeated here.

[0046] The reaction temperature is 150-230° C., preferably 170-220° C.; the reaction time of the high temperature reaction is 2-8 h, preferably 3-7 h.

[0047] The platinum precursor is one of chloroplatinic acid, tetraammineplatinum nitrate, and ammonium chloroplatinite, preferably one of chloroplatinic acid and ammonium chloroplatinite.

[0048] The transition metal precursor is one of cupric chloride, cuprous chloride, cupric nitrate, cuprous nitrate and cupric acetate, preferably one of cupric chloride, cupric nitrate and cupric acetate.

[0049] The gallium precursor is one of gallium chloride, gallium nitrate, gallium sulfate and gallium acetate, preferably one of gallium chloride and gallium acetate.

[0050] The gold precursor is one of chloroauric acid, potassium chloroaurate, sodium chloroaurate and ammonium tetrachloroaurate, preferably one of chloroauric acid and potassium chloroaurate.

[0051] The drying temperature is preferably 50 to 80° C., and the drying time is preferably 5 to 12 hours.

[0052] In the embodiments of the present application, in the process of synthesizing platinum-copper catalysts, the size and morphology of platinum-based alloy nanoparticles are regulated by introducing gallium and gold. The introduction of gallium can induce the formation of spherical nanoparticles. The synergistic effect of gallium and gold effectively inhibits the agglomeration of platinum-based alloy nanoparticles, and realizes the synthesis of small-sized spherical platinum-based alloy catalysts. In addition, the introduction of gallium and gold regulates the electronic structure of platinum, causes the d-band center of platinum to decrease, and optimizes the adsorption and desorption behavior of platinum on oxygen-containing intermediates. The size and morphology of platinum-based alloys are regulated, and the electrocatalytic oxygen reduction reaction performance of platinum-based alloy catalysts is significantly improved.

[0053] The present invention also provides a carbon-supported small-sized spherical platinum-based alloy catalyst, which is prepared by the above-mentioned preparation method. The Pt content in the carbon-supported small-sized spherical platinum-based alloy catalyst is 10-40wt%, and the atomic ratio of Pt, transition metal, Ga, and Au is 3: (1-3): (0.5-2): (0.01-0.12); the average particle size of the nanoparticles in the catalyst is less than 3nm.

[0054] The aforementioned carbon-supported small-sized spherical platinum-based alloy catalyst is used in the oxygen reduction reaction of hydrogen fuel cells and methanol fuel cells.

[0055] The preparation method of the carbon-supported small-sized spherical platinum-based alloy catalyst provided by the present invention is described below in conjunction with specific examples. Unless otherwise specified, the raw materials and reagents in the examples of the present application are purchased through commercial channels.

[0056] Example 1

[0057] Example 1 provides a method for preparing a carbon-supported small-sized spherical platinum-based alloy catalyst, comprising the following steps:

[0058] S1. 100 g of commercial carbon black (XC-72R) was treated at 2800° C. for 2.5 h in an argon atmosphere in a high temperature furnace, and then 3 g of the treated carbon black was added to 150 ml of nitric acid, heated under reflux at 100° C. for 5 h, washed with deionized water, and then dried at 80° C. overnight to obtain a pretreated carbon black carrier;

[0059] S2. Weigh 53.5 mg of the treated carbon black carrier and disperse it in 90 ml of ethylene glycol, and ultrasonicate it in an ice bath until it is uniformly dispersed; add 8.7 ml of 0.0186 M chloroplatinic acid ethylene glycol solution, 1 ml of 0.1 M copper chloride ethylene glycol solution and 0.65 ml of 0.1 M gallium chloride aqueous solution in sequence and stir evenly, then add 2.49 ml of 1 M sodium hydroxide aqueous solution to adjust the system to alkalinity, then add 0.21 ml of 0.024 M chloroauric acid aqueous solution, stir for a period of time, and ultrasonicate it in an ice bath, then place the reaction system in a reactor with mechanical stirring, and react at 190 ° C for 5 hours. After the reaction is completed, solid-liquid separation is achieved by filtering, washed with deionized water, and then dried at 60 ° C overnight to obtain a carbon-supported small-sized spherical platinum-based alloy catalyst.

[0060] Comparative Example 1

[0061] Comparative Example 1 provides a method for preparing a carbon-supported small-sized spherical platinum-based alloy catalyst. Compared with Example 1, the difference is that in step S2, no gold precursor or gallium precursor is added, and the other steps are substantially the same as those in Example 1 and will not be repeated here.

[0062] Comparative Example 2

[0063] Comparative Example 2 provides a method for preparing a carbon-supported small-sized spherical platinum-based alloy catalyst. Compared with Example 1, the difference is that in step S2, no gold precursor is added, and the other steps are substantially the same as those in Example 1 and will not be repeated here.

[0064] Comparative Example 3

[0065] Comparative Example 3 provides a method for preparing a carbon-supported small-sized spherical platinum-based alloy catalyst. Compared with Example 1, the difference is that in step S2, no gallium precursor is added, and the other steps are substantially the same as those in Example 1 and will not be repeated here.

[0066] Table 1 Comparison of main parameters and performance between Example 1 and Comparative Examples 1-3

[0067]

[0068]

[0069] Figure 1-4 The N of the catalysts prepared in Example 1 and Comparative Examples 1-3 are respectively 2 -CV curve.

[0070] As can be seen from the figure, the electrochemically active areas of the catalysts prepared in Comparative Examples 2 and 3 are higher than those in Comparative Example 1, indicating that the introduction of Au or Ga alone inhibits the agglomeration of the catalysts to a certain extent. The electrochemically active area of ​​the catalyst prepared in Example 1 is significantly higher than that of the catalysts in Comparative Examples 2 and 3, indicating that the synergistic effect of Au and Ga significantly inhibits the agglomeration of platinum copper nanoparticles.

[0071] Figure 5 The LSV polarization curves of the catalysts prepared in Example 1 and Comparative Examples 1-3 and the JM commercial platinum-carbon catalyst are shown in Figure 1. It can be seen that the mass specific activity of the catalyst prepared in Comparative Example 1 is only 0.24 A / mg. Pt On this basis, after the introduction of Ga or Au, the mass specific activity of the catalysts in Comparative Example 2 and Comparative Example 3 increased to 0.46 A / mg Pt and 0.37A / mg Pt After the introduction of Au and Ga, the mass specific activity of the catalyst increased significantly to 0.91 A / mg Pt , which is significantly higher than the commercial platinum-carbon catalyst (0.12A / mg Pt ). This result shows that the synergistic effect of Au and Ga can significantly improve the catalytic performance of Pt-based alloy catalysts.

[0072] Figure 6 The XPS spectra of the catalysts prepared in Example 1 and Comparative Example 1. It can be seen that the simultaneous introduction of Au and Ga during the synthesis process increases the binding energy of Pt by 0.25 eV, indicating that the introduction of Au and Ga causes the d-band center of Pt to drop, accelerates the desorption of oxygen-containing intermediates on Pt, and thus improves the electrocatalytic oxygen reduction reaction performance of the catalyst.

[0073] Figure 7-10 The TEM images of the catalysts prepared in Example 1, Comparative Example 1, Comparative Example 2 and Comparative Example 3 are shown respectively.

[0074] It can be seen that in the catalyst prepared in Comparative Example 1, the platinum-based nanoparticles are unevenly dispersed on the carbon black carrier and there is obvious agglomeration. After the introduction of Ga, the morphology of the platinum-based nanoparticles on the catalyst prepared in Comparative Example 2 changes significantly, and it can be observed that the carbon black carrier is all spherical nanoparticles. After the introduction of Au and Ga at the same time, small-sized spherical nanoparticles can be observed on the catalyst of Example 1, which are evenly distributed on the carbon black carrier, and the average particle size of the nanoparticles is less than 3nm. Therefore, the electron microscopy results of the catalysts of Example 1, Comparative Example 1 and Comparative Example 2 can prove that the introduction of Ga in the synthesis process can guide the formation of spherical nanoparticles, and the introduction of Ga and Au can inhibit the agglomeration of nanoparticles, and the formation of small-sized spherical platinum-based nanoparticles is achieved under the synergistic effect of Ga and Au. From Comparative Example 3, it can be observed that the addition of Au alone cannot change the morphology of nanoparticles on the catalyst, and the effect of inhibiting agglomeration is limited. Therefore, the electron microscopy results of the catalyst of Comparative Example 3 can further prove that the synthesis of small-sized spherical platinum-based alloy catalysts can only be achieved under the synergistic effect of Ga and Au.

[0075] Example 2

[0076] Example 2 provides a method for preparing a carbon-supported small-sized spherical platinum-based alloy catalyst. Compared with Example 1, the difference is that the addition of 0.21 ml of 0.024M chloroauric acid aqueous solution in step S2 is replaced by the addition of 0.42 ml of 0.024M chloroauric acid aqueous solution; the rest is roughly the same as Example 1 and will not be repeated here.

[0077] Example 3

[0078] Example 3 provides a method for preparing a carbon-supported small-sized spherical platinum-based alloy catalyst. Compared with Example 1, the difference is that the copper chloride in step S2 is replaced by copper nitrate; the rest is basically the same as Example 1 and will not be repeated here.

[0079] Example 4

[0080] Example 4 provides a method for preparing a carbon-supported small-sized spherical platinum-based alloy catalyst. Compared with Example 1, the difference is that the copper chloride in step S2 is replaced by copper nitrate, and 0.65 ml of 0.1 M gallium chloride aqueous solution is replaced by 0.65 ml of 0.1 M gallium chloride ethylene glycol solution; the rest is roughly the same as Example 1 and will not be repeated here.

[0081] Experiments show that Examples 2-4 can successfully produce carbon-supported small-sized spherical platinum-based alloy catalysts.

[0082] It should be noted that the carbon black may also be one of acetylene black, Ketjen black, mesoporous carbon and BP-2000 porous carbon. The platinum precursor may also be one of tetraammine platinum nitrate and ammonium chloroplatinite. The transition metal precursor may also be one of cuprous chloride, cuprous nitrate and cupric acetate. The gallium precursor may also be one of gallium nitrate, gallium sulfate and gallium acetate; the gold precursor may be one of potassium chloroaurate, sodium chloroaurate and ammonium tetrachloroaurate.

[0083] In summary, in the preparation method of the carbon-supported small-sized spherical platinum-based alloy catalyst provided by the present invention, Ga has a structural guiding effect, and the synergistic effect of Ga and Au jointly inhibits the aggregation of platinum-based nanoparticles during the synthesis of the catalyst. Therefore, the synergistic effect of Au and Ga realizes the synthesis of small-sized spherical platinum-based alloy nanoparticles on activated carbon, which has a high electrochemical active area and exhibits high electrocatalytic performance during the oxygen reduction reaction performance test.

[0084] The above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solution of the present invention.

Claims

1. A method for preparing a carbon-supported small-sized spherical platinum-based alloy catalyst, characterized in that: The following steps are involved: S1. treating the carbon black carrier at high temperature under an inert atmosphere to improve its graphitization degree, then performing an oxidation treatment to promote its surface functionalization, and obtaining a treated carbon black carrier after filtering, washing with deionized water and drying; S2. After dispersing the treated carbon black carrier in a solvent and uniformly dispersing it by ultrasonic, a platinum precursor, a transition metal precursor and a gallium precursor are dissolved in a solvent and added to the above system, sodium hydroxide is added to adjust the pH of the solution system to alkaline, and then a gold precursor is dissolved in a solvent and added to the above system. After uniformly dispersing it by ultrasonic, it is placed in a reactor with mechanical stirring, reacted at high temperature for 2 to 8 hours, and solid-liquid separation is achieved by a vacuum filter. After filtering, washing and drying, a carbon-supported small-sized spherical platinum-based alloy catalyst is obtained.

2. The method for preparing a carbon-supported small-sized spherical platinum-based alloy catalyst according to claim 1, characterized in that: In step S2, the mass ratio of the platinum precursor, transition metal precursor, gallium precursor, gold precursor and treated carbon black carrier is (70-100): (5.4-23.2): (5-28.3): (0.6-9.7): (20.2-370.1).

3. The method for preparing a carbon-supported small-sized spherical platinum-based alloy catalyst according to claim 1, characterized in that: In step S2, the solvent is one of ethylene glycol, propylene glycol, butylene glycol, ethylene glycol / water, propylene glycol / water, and butylene glycol / water, and the reaction temperature is 150-230°C.

4. The method for preparing a carbon-supported small-sized spherical platinum-based alloy catalyst according to claim 1, characterized in that: In step S2, the gallium precursor is one of gallium chloride, gallium nitrate, gallium sulfate, and gallium acetate; the gold precursor is one of chloroauric acid, potassium chloroaurate, sodium chloroaurate, and ammonium tetrachloroaurate.

5. The method for preparing a carbon-supported small-sized spherical platinum-based alloy catalyst according to claim 1, characterized in that: In step S2, the platinum precursor is one of chloroplatinic acid, tetraammineplatinum nitrate, and ammonium chloroplatinite.

6. The method for preparing a carbon-supported small-sized spherical platinum-based alloy catalyst according to claim 1, characterized in that: In step S2, the transition metal precursor is one of cupric chloride, cuprous chloride, cupric nitrate, cuprous nitrate, and cupric acetate.

7. The method for preparing a carbon-supported small-sized spherical platinum-based alloy catalyst according to claim 1, characterized in that: In step S1, the carbon black carrier is one of commercial XC-72R conductive carbon black, acetylene black, Ketjen black, mesoporous carbon and BP-2000 porous carbon; the high temperature treatment temperature of the carbon black carrier is 2000-3000°C, and the treatment time is 1-5h.

8. The method for preparing a carbon-supported small-sized spherical platinum-based alloy catalyst according to claim 1, characterized in that: In step S1, the oxidant is one of hydrogen peroxide, nitric acid and concentrated sulfuric acid; the solid-liquid ratio of the carbon black carrier to the oxidant is 1g: (20-200)ml.

9. A carbon-supported small-sized spherical platinum-based alloy catalyst, prepared by the preparation method of the carbon-supported small-sized spherical platinum-based alloy catalyst according to any one of claims 1 to 8, characterized in that: The Pt content in the carbon-supported small-size spherical platinum-based alloy catalyst is 10-40wt%, and the atomic ratio of Pt, transition metal, Ga and Au is 3: (1-3): (0.5-2): (0.01-0.12); the average particle size of the nanoparticles in the catalyst is less than 3nm.

10. An application of a carbon-supported small-sized spherical platinum-based alloy catalyst, characterized in that: The carbon-supported small-sized spherical platinum-based alloy catalyst is prepared by the preparation method described in any one of claims 1 to 8 or is the carbon-supported small-sized spherical platinum-based alloy catalyst described in claim 9; the carbon-supported small-sized spherical platinum-based alloy catalyst is used in hydrogen fuel cells and methanol fuel cells oxygen reduction reactions.

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