Preparation method of Pt alloy nanoparticle / rod-shaped mesoporous carbon carrier catalyst

Abstract

A method for preparing a Pt alloy nanoparticle / rod-shaped mesoporous carbon carrier catalyst comprises the following steps: 1: mixing a cobalt- or nickel-containing compound with a perfluorosulfonic acid resin solution, an organic reagent, and a nonionic surfactant to obtain a clear and uniform spinning liquid; 2: performing electrostatic spinning using the uniformly mixed slurry, with a receiving substrate being a polytetrafluoroethylene membrane; 3: performing pre-oxidation and graphitization on the spinning layer; 4: surface-modifying the graphitized mesoporous carbon fibers using an oxidizing gas under a high-temperature environment; 5: performing a shearing treatment; and 6: using a colloid method to utilize Co or Ni in the carbon fibers to prepare a PtCo or PtNi alloy nanoparticle / sulfur-doped rod-shaped mesoporous novel catalyst. The method has a simple preparation process, controlled mesoporous carbon morphology, and while increasing the activity and gas transport capacity of the proton exchange membrane fuel cell catalyst, it more strongly anchors the metal Pt alloy nanoparticles in the mesopores of the carbon carrier, thereby enhancing the electrochemical activity, durability, and stability of the fuel cell electrocatalyst.

Description

Technical Field

[0001] The invention belongs to the technical field of fuel cells, and in particular relates to a method for preparing a Pt alloy nanoparticle / rod-shaped mesoporous carbon carrier catalyst. Background Art

[0002] Proton exchange membrane fuel cells are a key technology for the development and utilization of hydrogen energy. Platinum-based catalysts are the core materials of fuel cells. Their design, preparation technology and industrialization capabilities play a decisive role in the performance, life and cost of fuel cells. Platinum-based catalysts are generally used in practice in the form of spherical nanoparticles supported on high-surface-area carbon carriers. Among the catalyst carriers, solid carbon materials such as Ketjen-black and Vulcan are usually used. The specific application is that the catalyst with metal particles such as platinum supported on the surface of the carrier is mixed with perfluorosulfonic acid polymers in a certain proportion to form a catalytic layer. Hydrogenation reaction occurs at the anode and oxygen reduction reaction occurs at the cathode. The core of reducing the cost of mass-produced fuel cells is to reduce the amount of precious metal catalysts used in the cathode. In the research on low-platinum catalysts since 2010, researchers have found that when the Pt loading is less than 0.1 mg cm -2 Under certain circumstances, an unexpected power density loss was observed in fuel cells at high currents. This was attributed to resistance to oxygen flow through the ionomer / gas interface and the Pt / ionomer interface, which inhibited oxygen transport near the Pt surface. Particularly after 2015, it was further discovered that a dense ionomer layer less than 0.5 nm thick forms near the Pt surface, severely hindering oxygen permeability. However, subsequent research brought good news: mesoporous carbon supports can reduce ionomer-related oxygen transport resistance and the catalyst poisoning effect of ionomers. Mesoporous carbon refers to porous carbon with pore sizes between 2 nm and 50 nm. Since 1992, when Mobil scientists first used nanostructured self-assembly technology to prepare mesoporous silica MCM-41 with uniform pores and adjustable pore size, mesoporous materials have quickly become a hot topic in the field of porous materials research. Currently, the mesoporous carbon commonly used in laboratories mainly includes ordered mesoporous carbon and disordered mesoporous carbon.

[0003] There are two main experimental synthesis methods for mesoporous carbon: the hard template method and the soft template method. The hard template method uses porous silicon as a template and organic matter as a carbon source, and then removes the template to prepare a mesoporous material. The advantage of using the hard template method to synthesize mesoporous materials is its strong universality, and the synthesized mesoporous material can completely inherit the structure of the hard template. The soft template method uses a surfactant as a template and an organic matter that has a strong interaction with the surfactant as a carbon source to prepare a composite with an ordered structure, and then carbonizes the polymer to obtain an ordered mesoporous carbon material. Chinese Patent No. 201410732134.2 discloses a method for preparing a mesoporous carbon material, comprising first mixing calcium carbonate with ethanol, then adding distilled water, a sugar, and silica sol, mixing the mixture, ultrasonically treating the mixture, drying the mixture, and then subjecting the mixture to high-temperature treatment in a nitrogen atmosphere. Finally, the mixture is reacted with an acid solution and an alkaline solution, washed, and dried to obtain the carbon material. Chinese Patent No. 201710133816.5 discloses a graphene quantum dot / mesoporous carbon composite material comprising mesoporous carbon and graphene quantum dots filling the mesopores of the mesoporous carbon. Chinese Patent No. 201610071940.9 discloses a method for preparing an ordered mesoporous carbon material, comprising assembling a surfactant and a polymer source to form an ordered structured composite, reducing the solubility of the composite in solution with a salt solution or solid salt to cause precipitation, and heating the resulting precipitate in air and then heat-treating it at high temperature in nitrogen or argon to obtain the ordered mesoporous carbon material.

[0004] Existing mesoporous carbon materials are primarily developed for applications in adsorption, separation, lithium-ion batteries, and energy storage. However, the preparation technology for mesoporous carbon materials used as fuel cell catalyst supports still has several drawbacks that need to be overcome. For example, 1) the shape of the prepared mesoporous materials is uncontrollable, with the main forms being granular, bulk, and beaded. Efficient water-gas mass transfer in fuel cell catalyst layers requires mesoporous carbon with a regular morphology. 2) Silicon sphere templates and soft templates easily agglomerate, making particle size difficult to calibrate. This results in uneven size and large particle size deviation in the prepared mesoporous materials, impacting the consistent performance of the fuel cell catalyst layer. Therefore, there is an urgent need to develop mesoporous carbon materials with regular morphology for use as fuel cell catalyst supports and to prepare Pt-based nanoparticles / rod-shaped mesoporous carbon catalysts. 3) Currently, mesoporous carbon materials cannot realistically produce Pt alloy nanoparticles within the pores. Due to the lack of anchoring for the Pt alloy nanoparticles within the mesopores, the majority of the Pt alloy nanoparticles remain attached to the outside of the mesopores. Developing rod-shaped mesoporous carbon materials with Pt alloy nanoparticles anchored within the mesopores is of great practical significance for improving the overall performance of fuel cells. Summary of the Invention

[0005] To address the problems of the mesoporous carbon materials prepared by the above-mentioned mesoporous carbon material preparation methods, such as the lack of Pt alloy nanoparticle anchoring sites within the mesopores, the irregular morphology and inconsistent size of the mesoporous carbon materials, and their inability to meet the requirements of fuel cell electrocatalysis for efficient multiphase transport, consistency, and durability, the present invention has developed a special method for preparing rod-shaped mesoporous carbon materials for fuel cells, and further prepared Pt-based nanoparticles / rod-shaped mesoporous carbon catalysts. Co- or Ni-doped S-ionomer nanofibers are prepared by electrospinning. The S-doped ionomers can bind cobalt ions or nickel ions to form cobalt- or nickel-containing ion clusters, which are the large amount of Co or Ni atoms required to prepare PtCo or PtNi alloys. The Co- or Ni-doped S-ionomer nanofibers are then graphitized to form strong anchoring sites doped with S in the mesopores. Surface modification is then performed to increase the micropores and small-scale mesoporous structures to increase the specific surface area. The surface-modified graphitized mesoporous carbon fibers are ball-milled or sheared to produce rod-shaped mesoporous carbon materials with a reasonable aspect ratio. Pt alloy particles are then prepared within the aforementioned mesoporous carbon using a colloidal method to form Pt alloy nanoparticles / rod-shaped mesoporous carbon catalysts. The catalyst carrier differs from traditional granular, bulk, or beaded mesoporous carbons in that the mesoporous carbon has a regular morphology and consistent size due to its consistent diameter and length. Furthermore, the sulfur-doped material forms a strong anchoring structure with the Pt alloy, enabling the controlled preparation of catalytic particles within the mesopores of the mesoporous carbon and enhancing its stability. Rod-shaped mesoporous carbon materials, used as fuel cell catalyst carriers and loaded with catalytic particles, can further improve the electrocatalytic three-phase interface and the transport of oxygen, protons, and electrons, thereby enhancing the performance and life of fuel cells.

[0006] Specifically, the preparation method of a Pt alloy nanoparticle / rod-shaped mesoporous carbon support catalyst of the present invention comprises the following steps:

[0007] S1: mixing a cobalt- or nickel-containing compound with a perfluorosulfonic acid resin solution, an organic reagent, and a nonionic surfactant to obtain a uniform spinning liquid;

[0008] S2: Using the above-mentioned uniformly mixed slurry for electrospinning, the receiving substrate is a polytetrafluoroethylene membrane, and the spinning diameter is controlled between 150nm and 600nm. After the spinning is completed, the receiving substrate is removed from the rotating drum receiver, and the spinning layer is peeled off for subsequent operations;

[0009] S3: The spinning layer is placed in a muffle furnace for heating and pre-oxidation treatment; then, the spinning layer is placed in an atmosphere tube furnace for graphitization under inert gas protection to obtain a product containing Co or Ni-doped S-graphitized mesoporous carbon fiber;

[0010] S4: Surface modification of the Co- or Ni-doped S-graphitized mesoporous carbon fibers is performed using an oxidizing gas at a high temperature of 600 to 1000° C. to form highly porous mesoporous carbon fibers, thereby opening up disconnected mesopores, increasing the number of pores, and forming a connected structure, thereby increasing the specific surface area and a large number of micropores and small-sized mesoporous structures.

[0011] S5: Shearing the surface-modified Co- or Ni-doped S-graphitized mesoporous carbon fibers to control their length to be in the range of 200-1000 nm;

[0012] S6: Preparation of Pt alloy nanoparticles / sulfur-doped rod-shaped mesoporous catalyst by colloid method: Ultrasonic mixing of the above-mentioned Co- or Ni-doped S rod-shaped mesoporous carbon, ethylene glycol aqueous solution, alkali, and chloroplatinic acid in a certain proportion, with the pH range controlled at 10-13.

[0013] In the present invention, a micro-channel reactor is used for reaction, and the temperature is controlled at 110-160°C.

[0014] Preferably, after the reaction is completed, acid is added to adjust the pH of the reaction solution to 1-3 so as to demulsify the colloidal system after the reaction solution, and the solution is filtered and washed to neutrality.

[0015] Preferably, the filter cake is placed in a vacuum drying oven at 80° C. and dried for 8 to 12 hours, and then ground to obtain a solid powder.

[0016] In the present invention, preferably, in step S1, the cobalt-containing or nickel-containing compound includes cobalt chloride, cobalt nitrate, cobalt sulfate, cobalt acetate, cobalt acetylacetonate, nickel chloride, nickel nitrate, nickel sulfate, nickel acetate, nickel bromide or nickel acetylacetonate.

[0017] Preferably, in step S1, the perfluorosulfonic acid resin solution includes Nafion D520 solution, Nafion D2020 solution, Aquivion D79-25BS solution, or Aquivion DFPSA-2079 / 2179 / 2072 / 2172 / 2150 solution. The perfluorosulfonic acid resin solution contains sulfonic acid groups that can bind to cobalt ions or nickel ions to form cobalt- or nickel-containing ion clusters, providing the large amount of Co or Ni atoms required for the preparation of PtCo or PtNi alloys and providing in-situ sulfur doping.

[0018] Preferably, in step S1, the organic reagent includes: N,N-dimethylformamide (DMF), polyethylene glycol, polyvinyl pyrrolidone, polyacrylic acid, polyvinyl alcohol, polystyrene, polyacrylonitrile, polyimide or cellulose.

[0019] Preferably, in step S1, the nonionic surfactant includes polyoxyethylene-polyoxypropylene copolymer (eg F127), fatty alcohol polyoxyethylene ether (AEO), alkylphenol polyoxyethylene ether, fatty acid polyoxyethylene ester or alkylolamide polyoxyethylene ether.

[0020] Preferably, in step S1, the slurry is mixed with an angle mixer and is operated in a defoaming mode to achieve uniform dispersion.

[0021] Preferably, in step S3, the spinning layer is heated in the muffle furnace at a temperature ranging from 120°C to 350°C, with a holding time of 1-10 hours and a heating rate of 1-5°C / min.

[0022] Preferably, in step S3, the spinning layer is graphitized in a tubular furnace under the protection of an inert atmosphere, wherein the inert gas mainly includes nitrogen and argon.

[0023] Preferably, in step S3, the spinning layer is heated to 350°C-600°C in a tubular furnace at a heating rate of 3-10°C / min and maintained at this temperature for 1 hour; the spun fiber is then heated to 800°C-1000°C at a rate of 2-5°C / min and maintained at this temperature for 3 hours. By introducing Co or Ni elements, not only can the base metal elements required for the formation of platinum alloy nanoparticles be provided in the pores, but the temperature required for graphitization can also be effectively reduced (generally below 1000°C), and the degree of graphitization of the mesoporous carbon nanomaterial can be significantly improved.

[0024] Preferably, in step S4, the oxidizing gas mainly includes water vapor, oxygen and carbon dioxide.

[0025] Preferably, in step S5, the mixing treatment method comprises one or more methods selected from grinding, shearing, ultrasonication, and ball milling, and is supplemented by a chemical cutting method. Chemical cutting methods include wet cutting and dry cutting methods. Chemical methods used include, but are not limited to, the use of strong oxidants such as sulfuric acid, nitric acid, hydrogen peroxide, carboxylic acid, piranha solution, and the like, and the use of metal nanomaterials for catalytic cutting.

[0026] In summary, the preparation method of the rod-shaped mesoporous carbon material of the present invention is based on the electrospinning process, which forms an anchoring position with a strong effect of S doping containing Co or Ni elements in the mesopores, while increasing the activity and gas transport capacity of the proton exchange membrane fuel cell catalyst, and more strongly anchoring the platinum alloy nanoparticles in the mesopores of the carbon carrier to meet the purpose of improving the electrochemical activity, durability and stability of the fuel cell electrocatalyst.

[0027] The present invention can achieve positive technical effects:

[0028] 1. The present invention provides a method for preparing a platinum alloy / mesoporous carbon catalyst with a simple preparation process, controllable morphology, and strong anchoring ability for catalytic particles within the mesopores. The rod-shaped mesoporous carbon, serving as a catalyst carrier, can overlap with each other in the catalyst layer and guide the uniform distribution of ionomer polymers, forming a unique three-dimensional network structure that maximizes the three-phase interface in the catalyst layer, promoting mass and charge transport during the reaction while reducing electrochemical polarization and concentration polarization in the fuel cell. The mesopores of the rod-mounted mesoporous carbon are rich in Co or Ni elements and sulfur doping sites, which can serve as effective anchoring sites for catalytic platinum alloy nanoparticles. The in-situ doping of sulfur effectively changes the charge density of the original matrix, forming more active centers. The synergistic effect of S and Co / Ni further improves the oxygen reduction reaction catalytic efficiency of the catalytic particles.

[0029] 2. The present invention combines the mass transfer advantages of mesoporous carbon with the control of mesoporous carbon morphology, the synthesis of platinum alloys containing Co or Ni elements in the mesopores, and the effective anchoring of Pt alloy nanoparticles by sulfur doping. Sulfur doping plays an important role in increasing the activity and gas transport capacity of proton exchange membrane fuel cell catalysts while more strongly anchoring PtCo or PtNi nanoparticles in the mesopores of the carbon carrier, thereby enhancing the electrochemical activity, durability and stability of fuel cell electrocatalysts. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 SEM image of the nanofibers after pre-oxidation treatment in Example 1.

[0031] Figure 2 SEM image of mesoporous carbon fiber after high-temperature modification in Example 1.

[0032] Figure 3 XRD spectrum of the catalyst in Example 1.

[0033] Figure 4 CV performance of the catalyst of Example 1 and the comparative sample.

[0034] Figure 5 LSV performance of the catalyst of Example 1 and the comparative sample. DETAILED DESCRIPTION

[0035] The technical solution of the present disclosure is described in detail below with reference to specific embodiments.

[0036] In the embodiments, the chemical reagents used are industrial-grade products.

[0037] Example 1:

[0038] 10 g of polyacrylonitrile, 1.9 g of cobalt nitrate and 0.4 g of F127 were dissolved in 90 g of Nafion D2020, and the solution was mixed using an angle blender.

[0039] Take 10 ml of the solution for spinning, control the voltage to 40 kV, and control the thickness of the filaments to be 150 to 400 nm;

[0040] The spun yarn was sent to a muffle furnace for pre-oxidation at 280 °C for 1 h with a heating rate of 5 °C / min;

[0041] The pre-oxidized sample was graphitized at 900℃ for 3h in a tube furnace under N2 protection, first heated to 350℃ at a heating rate of 3℃ / min, kept at that temperature for 1h, and then heated to 900℃ at a heating rate of 5℃ / min;

[0042] The graphitized mesoporous carbon fibers were surface modified in an oxygen atmosphere at 600°C for 1 h.

[0043] Take 1g of the surface-modified sample, treat it with a mixture of hydrogen peroxide and sulfuric acid at 90℃ for 3h, and prepare rod-shaped mesoporous carbon with a length of about 400nm;

[0044] 1g of rod-shaped mesoporous carbon was mixed uniformly with ethylene glycol, chloroplatinic acid, and sodium hydroxide in a specific ratio. Chloroplatinic acid (2 wt.% dissolved in ethylene glycol) was added in a 1:1 ratio of platinum to carbon, followed by 2 volumes of ethylene glycol. Finally, sodium hydroxide was added to adjust the solution's pH to 12. The reaction was carried out in a tubular reactor at 140°C for 30 minutes, and nitric acid was added to adjust the solution's pH to 1. The sulfur-doped rod-shaped mesoporous carbon was filtered, washed, and dried to obtain a PtCo alloy catalyst.

[0045] The SEM test of the nanofiber structure after pre-oxidation treatment in Example 1 is as follows Figure 1 As shown, the average diameter of the nanofibers is 150nm. Figure 2 As shown in FIG, the average fiber diameter increases to 230 nm and the fiber surface is smooth. Figure 3 As shown in the figure, it can be seen that relative to the characteristic peak of Pt, the characteristic peak of the catalyst has an obvious right shift, showing a more obvious characteristic peak of the PtCo alloy crystal surface, and the PtCo alloy particle size is controlled at 3-5nm.

[0046] In order to test the performance of the catalyst prepared by the present invention, the same experiment was conducted using a commercial catalyst as a control sample. The electrochemical test results of the test sample are as follows: Figure 4 and 5 As shown. Figure 4It can be seen that the electrochemical active area of the catalyst supported by nanorod-like mesoporous carbon is higher than that of the commercial catalyst, which is increased by about 20%. Figure 5 It can be seen that the mass activity (0.9 V) of the catalyst supported on nanorod-shaped mesoporous carbon is higher than that of the commercial catalyst, which is increased by 25% (the commercial platinum carbon catalyst is JM 60% Pt / C).

[0047] Example 2:

[0048] 26 g of polyvinyl alcohol, 4 g of nickel chloride and 0.7 g of alkylphenol polyoxyethylene ether were dissolved in 200 g of Aquivion DFPSA-2179, and the solution was mixed using an angle blender.

[0049] Take 20 ml of the solution for spinning, control the voltage to 35 kV, and control the thickness of the yarn to be 250 to 300 nm;

[0050] The spun yarn was sent to a muffle furnace for pre-oxidation at 350 °C for 3 h with a heating rate of 3 °C / min;

[0051] The pre-oxidized sample was graphitized at 850℃ for 3h in a tubular furnace under Ar protection, and then heated to 450℃ at a heating rate of 5℃ / min, kept at that temperature for 1h, and then heated to 850℃ at a heating rate of 3℃ / min.

[0052] The graphitized mesoporous carbon fibers were surface modified in a carbon dioxide atmosphere at 1000°C for 1 h.

[0053] 2 g of the surface-modified sample was dispersed in peroxodiol and treated in a high-speed shear disperser for 3 h to prepare rod-shaped mesoporous carbon with a length of about 800 nm.

[0054] 1.5g of rod-shaped mesoporous carbon was mixed uniformly with ethylene glycol, chloroplatinic acid, and sodium hydroxide in a certain proportion. Chloroplatinic acid (1.5wt.% in ethylene glycol) was added in a 1:1 ratio of platinum to carbon, followed by 3 volumes of ethylene glycol. Finally, sodium hydroxide was added to adjust the solution's pH to 11. The reaction was carried out in a tubular reactor at 130°C for 40 minutes, and nitric acid was added to adjust the solution's pH to 2. The catalyst was filtered, washed, and dried to obtain a PtNi alloy catalyst based on sulfur-nickel-doped rod-shaped mesoporous carbon.

[0055] Example 3

[0056] 35 g of polyacrylic acid, 3.8 g of cobalt acetate, 2.5 g of nickel bromide and 1.2 g of fatty alcohol polyoxyethylene ether were dissolved in 230 g of Aquivion DFPSA-2150, and the solution was mixed using an angle blender.

[0057] Take 30 ml of the solution for spinning, control the voltage to 30 kV, and control the thickness of the yarn to be 300 to 350 nm;

[0058] The spun yarn was sent to a muffle furnace for pre-oxidation at 120 °C for 5 h with a heating rate of 2 °C / min;

[0059] The pre-oxidized sample was graphitized at 800℃ for 3h in a tube furnace under N2 protection, first heated to 500℃ at a heating rate of 4℃ / min, kept at that temperature for 1h, and then heated to 800℃ at a heating rate of 2℃ / min.

[0060] The graphitized mesoporous carbon fibers were surface modified in a water vapor atmosphere at 800°C for 1 h.

[0061] 3 g of the surface-modified sample was dispersed in nitric acid and processed in a planetary ball mill for 2 h to prepare rod-shaped mesoporous carbon with a length of about 900 nm.

[0062] 2g of rod-shaped mesoporous carbon was mixed uniformly with ethylene glycol, chloroplatinic acid, and sodium hydroxide in a certain proportion. Chloroplatinic acid (3 wt.% dissolved in ethylene glycol) was added in a 1:1 ratio of platinum to carbon, followed by 2.5 volumes of ethylene glycol. Finally, sodium hydroxide was added to adjust the solution's pH to 13. The reaction was carried out in a tubular reactor at 160°C for 20 minutes, and nitric acid was added to adjust the solution's pH to 3. The solution was filtered, washed, and dried to obtain a platinum-based catalyst based on sulfur-cobalt-nickel-doped rod-shaped mesoporous carbon.

[0063] For the platinum-based catalysts prepared in Examples 2 and 3, the performance of the catalysts was tested according to the method of Example 1, and similar excellent test results as those in Example 1 were obtained.

[0064] From the results of the above examples, it can be seen that the present invention provides a method for preparing a platinum alloy / mesoporous carbon catalyst with a simple preparation process, controllable morphology, and strong anchoring ability of catalytic particles in the mesopores. In addition, the present invention cleverly disperses the base metal elements required for preparing the platinum alloy in the fiber pores, and then synthesizes the platinum alloy catalytic particles with the platinum element, thereby achieving controllable preparation of alloy particles in the mesopores. At the same time, since the perfluorosulfonic acid resin uniformly distributed in the fiber is rich in sulfonic acid end groups, it can form ion clusters with Co or Ni ions, and the anchoring effect of sulfur doping on Pt alloy nanoparticles in the mesopores is combined, and the Pt alloy nanoparticles are strongly anchored in the mesopores of the carbon carrier to meet the purpose of improving the electrochemical activity, durability and stability of the fuel cell electrocatalyst.

[0065] Other embodiments of the present disclosure will readily occur to those skilled in the art after considering the specification and practicing the disclosure herein. This application is intended to cover any variations, uses, or adaptations of the present disclosure that follow the general principles of the present disclosure and include common knowledge or customary techniques in the art not disclosed herein. The description and examples are to be considered as exemplary only, and the true scope and spirit of the present disclosure are indicated by the claims of this application.

Claims

1. A method for preparing a Pt alloy nanoparticle / rod-shaped mesoporous carbon support catalyst, comprising the following steps: S1: mixing a cobalt- or nickel-containing compound with a perfluorosulfonic acid resin solution, an organic reagent, and a nonionic surfactant to obtain a clear and uniform spinning liquid; S2: Using the above-mentioned uniformly mixed slurry for electrospinning, the receiving substrate is a polytetrafluoroethylene membrane, and the spinning diameter is controlled between 150nm and 600nm. After the spinning is completed, the receiving substrate is removed from the rotating drum receiver, and the spinning layer is peeled off for subsequent operations; S3: The spinning layer is placed in a muffle furnace for heating and pre-oxidation treatment; then, the spinning layer is placed in an atmosphere tube furnace for graphitization treatment under the protection of an inert gas to obtain a product of S-doped graphitized mesoporous carbon fiber containing Co or Ni; S4: Surface modification of the Co- or Ni-doped S-graphitized mesoporous carbon fibers is performed using an oxidizing gas at a high temperature of 600 to 1000° C. to form highly porous mesoporous carbon fibers, thereby opening up disconnected mesopores, increasing the number of pores, and forming a connected structure, thereby increasing the specific surface area and a large number of micropores and small-sized mesoporous structures. S5: Shearing the surface-modified Co- or Ni-doped S-graphitized mesoporous carbon fibers to control their length to be in the range of 200-1000 nm to obtain rod-shaped mesoporous carbon fibers; S6: Prepare PtCo or PtNi alloy nanoparticles / sulfur-doped rod-shaped mesoporous catalysts using Co or Ni in carbon fibers by a colloidal method: Ultrasonic mixing of the above-mentioned Co- or Ni-containing S-doped rod-shaped mesoporous carbon, ethylene glycol aqueous solution, alkali, and chloroplatinic acid in a certain proportion, with the pH range controlled at 10-13; react in a microchannel reactor at a temperature of 110-160°C; after the reaction, add acid to adjust the pH of the reaction solution to 1-3 to demulsify the colloidal system after the reaction solution, filter, and wash to neutrality; dry the filter cake in a vacuum drying oven at 80°C for 8-12 hours, and grind to obtain a solid powder; In step S1 , the organic reagent includes N,N-dimethylformamide (DMF), polyethylene glycol, polyvinyl pyrrolidone, polyacrylic acid, polyvinyl alcohol, polystyrene, polyacrylonitrile, polyimide or cellulose.

2. The preparation method according to claim 1, wherein in step S1, the cobalt-containing or nickel-containing compound comprises cobalt chloride, cobalt nitrate, cobalt sulfate, cobalt acetate, cobalt acetylacetonate, nickel chloride, nickel nitrate, nickel sulfate, nickel acetate, nickel bromide or nickel acetylacetonate.

3. The preparation method according to claim 1, wherein in step S1, the perfluorosulfonic acid resin solution comprises Nafion D520 solution, Nafion D2020 solution, Aquivion D79-25BS solution, or Aquivion DFPSA-2079 / 2179 / 2072 / 2172 / 2150 solution; the perfluorosulfonic acid resin solution contains sulfonic acid groups that can bind to cobalt ions or nickel ions to form cobalt- or nickel-containing ion clusters, providing a large amount of Co or Ni atoms required for in-situ doping of sulfur elements and preparation of PtCo or PtNi alloys for catalyst synthesis.

4. The preparation method according to claim 1, wherein in step S1, the nonionic surfactant comprises a polyoxyethylene-polyoxypropylene copolymer, a fatty alcohol polyoxyethylene ether, an alkylphenol polyoxyethylene ether, a fatty acid polyoxyethylene ester or an alkylolamide polyoxyethylene ether.

5. The preparation method according to claim 1, wherein in step S1, the slurry is mixed with an angle mixer and is operated in a defoaming mode to ensure uniform dispersion.

6. The preparation method according to claim 1, wherein in step S3, the spinning layer is heated in a muffle furnace at a temperature range of 120-350°C, a holding time of 1-10 hours, and a heating rate of 1-5°C / min; and the spinning layer is graphitized in a tubular furnace under an inert atmosphere of nitrogen or argon.

7. The preparation method according to claim 1, in step S3, the spinning layer is heated to 350°C-600°C in a tubular furnace at a heating rate of 3-10°C / min and kept at this temperature for 1 hour, and then the spun fiber is heated to 800°C to 1000°C at a rate of 2-5°C / min and kept at this temperature for 3 hours. 8 . The preparation method according to claim 1 , wherein in step S4 , the oxidizing gas comprises water vapor, oxygen or carbon dioxide.

9. The preparation method according to claim 1, wherein in step S5, the shearing treatment method comprises one or more methods selected from the group consisting of grinding, ultrasonication, and ball milling, and is supplemented by a chemical cutting method; the chemical cutting method comprises a wet cutting method or a dry cutting method, wherein: The chemical cutting methods used include treating the mesoporous carbon fibers with sulfuric acid, nitric acid, hydrogen peroxide, Caro's acid, or piranha solution.

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