Method for preparing high-dispersion platinum / Ketjen black catalyst based on weak reducing agent liquid phase method and application of high-dispersion platinum / Ketjen black catalyst in fuel cell

Abstract

The invention belongs to the technical field of fuel cell catalyst preparation, and relates to a method for preparing a high-dispersion platinum / Ketjen black catalyst based on a weak reducing agent liquid phase method and application of the high-dispersion platinum / Ketjen black catalyst in a fuel cell. The surface defect of KB subjected to high-temperature treatment is combined with the slow-release reduction characteristic of a weak reducing agent, so that the non-uniform particle size distribution caused by the weak reducing agent is avoided, and the platinum dispersity is remarkably improved. Through the synergistic effect of high-temperature treatment and a weak reducing agent, the technical bottleneck of uniform loading of small-particle-size platinum (2-6nm) is broken through. The process is green and mild and is suitable for large-scale production. The catalysts exhibit high activity (0.68 V, 2 A / cm < 2 >) and high durability (5.1 mV, 30 k cycles) in fuel cells.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of fuel cell catalyst preparation, and relates to a method for preparing a highly dispersed platinum / Ketjen black catalyst based on a weak reducing agent liquid phase method and application thereof in a fuel cell, in particular to a method for preparing a highly dispersed and small particle size platinum / Ketjen black (Pt / KB) catalyst by high temperature pretreatment of a carbon carrier combined with liquid phase reduction of chloroplatinic acid with a weak reducing agent, and application thereof in a proton exchange membrane fuel cell (PEMFC) membrane electrode. BACKGROUND

[0002] Proton exchange membrane fuel cells (PEMFC) are widely considered as one of the most potential power sources for future clean energy and new energy vehicles due to their high energy conversion efficiency, low noise, zero emission and other advantages. Among them, the slow kinetics of the cathode oxygen reduction reaction (ORR) is a key factor restricting the overall performance, durability and commercialization cost of PEMFC.

[0003] At present, carbon-supported platinum (Pt / C) based catalysts are still the most effective and irreplaceable catalyst materials for driving ORR reactions. Commercial Pt / C catalysts are usually prepared on a large scale by liquid phase reduction method using strong reducing agents (such as sodium borohydride, formaldehyde, hydrazine hydrate, etc.). The use of sodium borohydride has significant drawbacks: a large amount of reduction cores generated instantaneously by strong reducing agents will cause the rapid reduction of platinum precursors (such as chloroplatinic acid), resulting in uncontrollable agglomeration of platinum nanoparticles, and ultimately forming platinum particles with large particle size and uneven distribution. Larger particle size and wider size distribution seriously reduce the utilization rate of platinum and the high-value electrochemical active surface area (ECSA), directly affecting the initial activity of the catalyst and the output performance of the fuel cell.

[0004] On the other hand, the durability of the catalyst also faces severe challenges. Under harsh working conditions such as frequent start-stop and high potential cycling of fuel cells, the traditional carbon carrier (such as Vulcan XC-72) is prone to electrochemical corrosion, which causes platinum nanoparticles to fall off, migrate and agglomerate due to the failure of the carrier, further exacerbating the degradation of catalyst performance.

[0005] To overcome the aforementioned problems, researchers have explored various improvement strategies. Using highly graphitized and stable carbon supports (such as Ketjen Black, KB) is one effective way to improve durability. Ketjen Black possesses a higher specific surface area and a well-developed mesoporous network, which is beneficial for reaction mass transfer and high dispersion loading. However, achieving high dispersion, small particle size, and uniform distribution of platinum nanoparticles on its surface remains a technical challenge. While existing technologies have included mild methods such as polyols and organosols for preparing small-particle Pt catalysts, these methods are often complex, costly, and involve the use of environmentally unfriendly organic protective agents or supercritical fluids that are difficult to mass-produce. Post-processing is cumbersome, and residual protective agents may cover active sites, affecting the catalyst's conductivity and intrinsic activity. Summary of the Invention

[0006] To address the aforementioned problems, developing a simple, mild, cost-effective, and scalable method for preparing high-performance, high-durability Pt / KB catalysts is crucial for advancing the commercialization of proton exchange membrane fuel cells. The purpose of this invention is precisely to overcome the deficiencies and shortcomings of the existing technologies.

[0007] To achieve the above objectives, the present invention adopts the following technical solution:

[0008] The first aspect of this invention discloses a method for preparing highly dispersed platinum / Ketjen black catalysts based on a weak reducing agent liquid-phase method, comprising the following steps:

[0009] S1: High defect density carrier is obtained by high-temperature treatment of Ketjen black carbon carrier under an inert atmosphere.

[0010] S2: The high defect density carrier of S1 is dispersed in deionized water, and H2PtCl6 solution is added. After ultrasonic treatment, a mixed solution is obtained.

[0011] S3: The mixed solution obtained in S2 was subjected to oil bath treatment using a weak reducing agent under high temperature conditions to obtain a highly dispersed platinum / Ketjen black catalyst.

[0012] The Ketjen black carbon carrier is selected from KB-EC-300J, KB-EC-600J, KB-O (oxidation treatment), KB-N (N-treatment) or KB-ECP600JD.

[0013] The reason for using Ketjen black as a carbon support in this invention is that ordinary carbon supports cannot achieve the preparation of high-performance catalysts through the above-mentioned processes.

[0014] Preferably, in S1, the high-temperature treatment conditions are 800-1200℃, the treatment time is 1-5h, and it is carried out in an Ar / H2 mixed atmosphere.

[0015] Preferably, the high-temperature treatment condition is 1200°C.

[0016] In S3, the weak reducing agent is selected from sodium sulfite, sodium bisulfite, sodium thiosulfate, vitamin C, or sodium citrate.

[0017] Preferably, the concentration of the weak reducing agent is 0.05-0.25 mol / L, and the pH is 4-10.

[0018] In S3, the oil bath treatment is carried out at a temperature of 60-100℃ for 1-5 hours.

[0019] The second aspect of this invention discloses a highly dispersed platinum / Ketjenblack catalyst, prepared by the method described above.

[0020] Preferably, the platinum particle size in the platinum / Ketjenblack catalyst is 2.0-6.0 nm.

[0021] The third aspect of this invention discloses the application of the above-mentioned platinum / Ketjenblack catalyst in the membrane electrode of a proton exchange membrane fuel cell.

[0022] Commercially available Pt / C catalysts in the prior art are typically prepared on a large scale using strong reducing agents (such as sodium borohydride, formaldehyde, hydrazine hydrate, etc.) via liquid-phase reduction. Strong reducing agents can be prepared in conventional reactors, while weak reducing agents may require microwave or supercritical equipment. At the same time, weak reducing agents are often accompanied by complex side reactions (such as the formation of carboxylate salts covering the Pt surface), requiring additional post-processing steps (such as high-temperature calcination to remove organic residues), which increases the complexity of the process.

[0023] Compared with the prior art, the beneficial effects of this invention are as follows:

[0024] The synergistic effect of high-temperature pretreatment of KB carrier combined with liquid-phase reduction by weak reducing agent, the combination of surface defects of KB after high-temperature treatment and the slow-release reduction characteristics of weak reducing agent, avoids the uneven particle size distribution caused by weak reducing agent and significantly improves platinum dispersibility.

[0025] Among them, the high-temperature pretreated KB carrier is treated with high temperature in an inert atmosphere (800-1200℃) to regulate the surface defects and oxygen-containing functional groups of the carrier, thereby enhancing the platinum anchoring ability.

[0026] For liquid-phase reduction using weak reducing agents, sodium citrate and other weak reducing agents are selected to slowly reduce H2PtCl6 under mild conditions (60-100℃) to achieve uniform nucleation and growth of platinum nanoparticles (2-6nm). Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the method for preparing highly dispersed platinum / Ketjen black catalyst according to the present invention;

[0028] Figure 2 The image shows a scanning electron microscope (SEM) image of the catalyst prepared in Example 1.

[0029] Figure 3 SEM image of the catalyst prepared in Example 2;

[0030] Figure 4 SEM image of the catalyst prepared in Example 3;

[0031] Figure 5 SEM image of the catalyst prepared in Example 4;

[0032] Figure 6 This is a SEM image of the catalyst prepared in Example 5. Detailed Implementation

[0033] The technical solution of the present invention will be described in detail below with reference to the accompanying drawings and embodiments, but this does not limit the present invention to the scope of the described embodiments. Process parameters not specified in the embodiments of this application can be performed according to conventional methods, and all raw materials used can be obtained through commercial channels.

[0034] Example 1

[0035] (1) High-temperature pretreatment of Ketjen black carrier: KB-EC-300J toner was placed in a tube furnace and heated to 800℃ at 5℃ / min under Ar / N2 atmosphere, held for 1h, and then cooled to obtain a high defect density carrier (KB-HT-1).

[0036] (2) Liquid-phase reduction of chloroplatinic acid with weak reducing agent: KB-HT-1 was dispersed in deionized water, H2PtCl6 solution (platinum loading 60wt%) was added, and ultrasonic treatment was performed for 30 min; weak reducing agent solution, sodium citrate (0.05mol / L, pH=7) was added dropwise; the reaction was carried out in an oil bath at 60℃ for 5 h, and after centrifugation, washing and drying, Pt / KB-HT-1 catalyst was obtained.

[0037] (3) Membrane electrode preparation and performance testing: The Pt / KB-HT-1 catalyst was mixed with Nafion solution and coated onto a proton exchange membrane. A single fuel cell was assembled, and its polarization curves and durability were tested. The scanning electron microscope (SEM) images of the Pt / KB-HT-1 catalyst are shown below. Figure 2 As shown.

[0038] Example 2

[0039] (1) High-temperature pretreatment of Ketjen black carrier: KB-EC-600J toner was placed in a tube furnace and heated to 900℃ at 5℃ / min under Ar / N2 atmosphere, held for 2h, and then cooled to obtain a high defect density carrier (KB-HT-2).

[0040] (2) Liquid-phase reduction of chloroplatinic acid with weak reducing agent: KB-HT-2 was dispersed in deionized water, H2PtCl6 solution (platinum loading 60wt%) was added, and ultrasonic treatment was performed for 30 min; weak reducing agent solution, sodium citrate (0.10 mol / L, pH=10) was added dropwise; the reaction was carried out in an oil bath at 70℃ for 4 h, and after centrifugation, washing and drying, Pt / KB-HT-2 catalyst was obtained.

[0041] (3) Membrane electrode preparation and performance testing: The Pt / KB-HT-2 catalyst was mixed with Nafion solution and coated onto a proton exchange membrane. A single fuel cell was assembled, and its polarization curves and durability were tested. Scanning electron microscopy (SEM) images of the Pt / KB-HT-2 catalyst are shown below. Figure 3 As shown.

[0042] Example 3

[0043] (1) High-temperature pretreatment of Ketjen black carrier: KB-O (oxidation treatment) toner was placed in a tube furnace and heated to 1000℃ at 5℃ / min under Ar / N2 atmosphere, held for 3h, and then cooled to obtain a high defect density carrier (KB-HT-3).

[0044] (2) Liquid-phase reduction of chloroplatinic acid with weak reducing agent: KB-HT-3 was dispersed in deionized water, H2PtCl6 solution (platinum loading 60wt%) was added, and ultrasonic treatment was performed for 30 min; weak reducing agent solution, sodium citrate (0.15mol / L, pH=6) was added dropwise; the reaction was carried out in an oil bath at 80℃ for 3 h, and after centrifugation, washing and drying, Pt / KB-HT-3 catalyst was obtained.

[0045] (3) Membrane electrode preparation and performance testing: The Pt / KB-HT-3 catalyst was mixed with Nafion solution and coated onto a proton exchange membrane. A single fuel cell was assembled, and its polarization curves and durability were tested. Scanning electron microscopy (SEM) images of the Pt / KB-HT-3 catalyst are shown below. Figure 4 As shown.

[0046] Example 4

[0047] (1) High-temperature pretreatment of Ketjen black carrier: KB-N (N-treated) toner was placed in a tube furnace and heated to 1100℃ at 5℃ / min under Ar / N2 atmosphere, held for 4h, and then cooled to obtain a high defect density carrier (KB-HT-4).

[0048] (2) Liquid-phase reduction of chloroplatinic acid with weak reducing agent: KB-HT-4 was dispersed in deionized water, H2PtCl6 solution (platinum loading 60wt%) was added, and ultrasonic treatment was performed for 30 min; weak reducing agent solution, sodium citrate (0.20 mol / L, pH=4) was added dropwise; the reaction was carried out in an oil bath at 90℃ for 2 h, and after centrifugation, washing and drying, Pt / KB-HT-4 catalyst was obtained.

[0049] (3) Membrane electrode preparation and performance testing: The Pt / KB-HT-4 catalyst was mixed with Nafion solution and coated onto a proton exchange membrane. A single fuel cell was assembled, and its polarization curves and durability were tested. Scanning electron microscopy (SEM) images of the Pt / KB-HT-4 catalyst are shown below. Figure 5 As shown.

[0050] Example 5

[0051] (1) High-temperature pretreatment of Ketjen black carrier: KB-ECP600JD toner was placed in a tube furnace and heated to 1200℃ at 5℃ / min under Ar / N2 atmosphere, held for 5h, and then cooled to obtain a high defect density carrier (KB-HT-5).

[0052] (2) Liquid-phase reduction of chloroplatinic acid with weak reducing agent: KB-HT-5 was dispersed in deionized water, H2PtCl6 solution (platinum loading 60wt%) was added, and ultrasonic treatment was performed for 30 min; weak reducing agent solution, sodium citrate (0.25mol / L, pH=9) was added dropwise; the reaction was carried out in an oil bath at 100℃ for 1 h, and after centrifugation, washing and drying, Pt / KB-HT-5 catalyst was obtained.

[0053] (3) Membrane electrode preparation and performance testing: The Pt / KB-HT-5 catalyst was mixed with Nafion solution and coated onto a proton exchange membrane. A single fuel cell was assembled, and its polarization curves and durability were tested. Scanning electron microscopy (SEM) images of the Pt / KB-HT-5 catalyst are shown below. Figure 6 As shown.

[0054] Comparative Example 1

[0055] The preparation method is the same as that in Example 5, except that the temperature conditions in step (1) are: 700℃, and the temperature is maintained for 0.5h.

[0056] Comparative Example 2

[0057] The preparation method is the same as in Example 5, except that the weak reducing agent conditions in step (2) are: sodium citrate (0.35 mol / L, pH=10).

[0058] Comparative Example 3

[0059] The preparation method is the same as that in Example 5, except that the oil bath conditions in step (2) are: reaction at 110°C for 0.5 h.

[0060] Comparative Example 4

[0061] The preparation method is the same as that in Example 5, except that step (1) is removed and KB-ECP600JD is used directly for reduction treatment in step (2).

[0062] The catalysts obtained in Examples 1-5 and Comparative Examples 1-4 were used to prepare fuel cell membrane electrodes and their initial performance was analyzed, as shown in Table 1.

[0063] Table 1

[0064]

[0065] The data in Table 1 shows the performance of different fuel cell membrane electrodes at different current densities:

[0066] Commercial membrane electrodes: Performance benchmarks of commercially available standard products used to compare the advantages and disadvantages of the experimental group (Examples 1-5) and the control group (Comparative Examples 1-4) of this invention.

[0067] Example 5 (0.75V@1A / cm) 2 It performs best at various current densities.

[0068] The catalysts obtained in Examples 1-5 and Comparative Examples 1-4 were used to prepare fuel cell membrane electrodes and their stability was analyzed, as shown in Table 2.

[0069] Table 2

[0070]

[0071] According to the data in Tables 1 and 2, the fuel cell membrane electrode of Example 5 of the present invention benefits from the unique pore structure and high specific surface area of ​​the KB-ECP600JD carbon support, which is advantageous for reaction mass transfer and the loading of highly dispersed Pt. Specifically:

[0072] 1. High specific surface area and mesoporous structure (high catalyst dispersion and utilization). Huge specific surface area (>1200 m²). 2 The platinum nanoparticles ( / g) provide numerous nucleation and anchoring sites, effectively preventing migration and aggregation during preparation and use. This enables extremely high metal dispersion, resulting in platinum catalysts with small particle sizes and narrow distributions. This means that less platinum is needed to expose more active sites, significantly improving platinum utilization and directly reducing catalyst costs.

[0073] 2. Developed three-dimensional conductive network (low electronic impedance and high power density). The fuel cell electrode is a three-phase reaction interface where electron conduction is crucial. The branched structure of the KB-ECP600JD forms a highly efficient electronic pathway within the electrode, ensuring that electrons generated by each platinum particle are rapidly collected and conducted to the current collector. This significantly reduces ohmic polarization losses in the electrode, especially at high current densities, enabling higher current output and thus increasing the power density of the fuel cell.

[0074] 3. Mesopore-dominated pore system (excellent mass transfer performance). This is the core advantage of KB-ECP600JD compared to other high specific surface area carbon materials (such as activated carbon, which is mainly microporous). Gas transport: Mesopores act as a "highway" for the transport of reactant gases (O2) to the active sites of the catalyst, avoiding the diffusion limitations of micropores. Water management: Generated water needs to be drained promptly to prevent flooding of the electrodes ("flooding"). The mesopore structure provides channels for capillary flow and drainage of water, keeping the gas diffusion path unobstructed. This improves the mass transfer polarization of the fuel cell, enabling the battery to operate stably under high loads and avoiding the sharp performance degradation caused by "flooding".

[0075] 4. Certain structural stability (extended lifespan). Its unique coral-like structure possesses a certain degree of mechanical strength and toughness, making it more able to withstand stress during the manufacturing process and under operating conditions compared to some brittle carbon materials.

[0076] The particle size analysis of the catalysts prepared in Examples 1-5 and Comparative Examples 1-4 is shown in Table 3.

[0077] Table 3

[0078]

[0079] Compared with Comparative Example 2, Example 5 differs in the parameters of the weak reducing agent (Example 5: sodium citrate 0.25 mol / L, pH=9; Comparative Example 2: sodium citrate 0.35 mol / L, pH=10). The reducing agent concentration in Comparative Example 2 is higher and the alkalinity is stronger. It can be seen that the selection of parameters of the weak reducing agent has a greater impact on the catalyst performance.

[0080] As shown in Tables 1, 2, and 3, the preparation of highly dispersed platinum / Ketjenblack catalysts based on the weak reducing agent liquid-phase method has significant effects. This effect is mainly attributed to the dual strategy of "high-temperature pretreatment of the carbon support" and "weak reducing agent liquid-phase reduction":

[0081] First, high-temperature pretreatment of carbon supports increases surface defects and anchoring points, improving support stability. High-temperature treatment (usually under an inert atmosphere) removes unstable oxygen-containing functional groups (such as -COOH, -OH) from the carbon support surface, while promoting the ordering of the graphite microcrystalline structure and creating more stable edge defects and micropores on the surface. These defects can serve as preferential "anchoring points" for platinum atom reduction nucleation, effectively fixing platinum nuclei and preventing their surface migration, laying the foundation for the formation of small and uniform nanoparticles. Pretreatment eliminates disordered carbon components in the carbon support that are prone to oxidation and corrosion under fuel cell operating conditions, making the support itself more stable and providing robust support for subsequent loading and the stability of small particles.

[0082] Liquid-phase reduction with a weak reducing agent controls nucleation and growth kinetics. Unlike the "burst" reduction of strong reducing agents, weak reducing agents provide relatively mild reduction capabilities, with a slow and controllable reduction rate. This allows the chloroplatinic acid precursor to be continuously and slowly reduced, achieving separation of the "nucleation" and "growth" processes. The slow reduction process avoids the instantaneous generation of excessively high concentrations of platinum atoms in the solution. Because the reduction rate is lower than the diffusion rate of platinum atoms on the carbon support surface, platinum atoms have sufficient time to reach the preset anchoring sites and grow in an orderly manner, greatly suppressing the "Ostwald ripening" phenomenon caused by the dissolution of small particles and the growth of large particles, thereby obtaining platinum nanoparticles with uniform particle size and high dispersion.

[0083] Second, the extremely high electrochemical active surface area (ECSA). The activity of a catalyst is directly related to the number of exposed platinum atoms. Small particle size means an extremely high specific surface area, significantly increasing the number of active sites available per unit mass of platinum. The smaller the particles, the higher the proportion of platinum atoms on the surface that can be used for catalytic reactions, and the ECSA value will inevitably be significantly greater than that of catalysts with larger particle sizes prepared by conventional methods.

[0084] Excellent mass transfer capability. The Ketjenblack (KB) support itself possesses a well-developed mesoporous (2-50 nm) structure. Combined with the ultra-small, highly dispersed platinum particles prepared by this method, particle blockage of the support pores is effectively prevented, ensuring the efficient transfer of oxygen and protons (H+). + The smooth transport of water molecules reduces concentration polarization, allowing active sites to participate more fully in the reaction, thus maintaining high performance even at high current densities.

[0085] Third, enhanced metal-support interaction. The defect anchoring points created on the Ketjen black surface through high-temperature pretreatment form a stronger binding force with the platinum nanoparticles. This strong interaction, like a "pinning effect," firmly fixes the platinum particles to the carbon support, effectively inhibiting the migration, detachment, and aggregation of platinum particles under harsh operating conditions such as start-up, shutdown, and load cycling, thereby greatly improving the catalyst's durability.

[0086] Improved carrier stability. The pretreated carbon carrier has a higher degree of graphitization and resistance to oxidation and corrosion, providing a more robust and durable "foundation" for platinum particles and preventing platinum particle failure due to carrier corrosion and collapse.

[0087] The inherent advantages of particle size control. A smaller and more uniform particle size distribution also contributes to improved stability. Particles of uniform size have similar surface energies, reducing the thermodynamic driving force for the dissolution of small particles and the growth of large particles due to size effects, thus slowing down the aging process from the source.

[0088] This invention overcomes the technical bottleneck of uniform loading of small-particle-size platinum (2-6 nm) through the synergistic effect of high-temperature treatment and a weak reducing agent. The process is green and mild, suitable for large-scale production. The catalyst exhibits high activity in fuel cells (0.68V, 2A / cm). 2 ) and high durability (5.1mV, 30k cycles).

[0089] This invention is not limited to the above-described embodiments. Any changes in shape or structure are within the scope of protection of this invention. The scope of protection of this invention is defined by the appended claims. Those skilled in the art can make various changes, modifications, substitutions, combinations, and simplifications to these embodiments without departing from the principles and essence of this invention. All such changes and simplifications should be considered equivalent substitutions and fall within the scope of protection of this invention.

Claims

1. A method for preparing highly dispersed platinum / Ketjenblack catalysts based on a weak reducing agent liquid-phase method, characterized in that, The steps include the following: S1: High defect density carrier is obtained by high-temperature treatment of Ketjen black carbon carrier under an inert atmosphere. S2: The high defect density carrier of S1 is dispersed in deionized water, and H2PtCl6 solution is added. After ultrasonic treatment, a mixed solution is obtained. S3: The mixed solution obtained in S2 was subjected to oil bath treatment using a weak reducing agent under high temperature conditions to obtain a highly dispersed platinum / Ketjen black catalyst.

2. The method for preparing highly dispersed platinum / Ketjen black catalyst based on a weak reducing agent liquid-phase method according to claim 1, characterized in that, The Ketjen black carbon carrier is selected from KB-EC-300J, KB-EC-600J, KB-O (oxidation treatment), KB-N (N-treatment) or KB-ECP600JD.

3. The method for preparing highly dispersed platinum / Ketjen black catalyst based on a weak reducing agent liquid-phase method according to claim 1, characterized in that, In S1, the high-temperature treatment conditions are 800-1200℃, the treatment time is 1-5h, and it is carried out in an Ar / H2 mixed atmosphere.

4. The method for preparing highly dispersed platinum / Ketjen black catalyst based on a weak reducing agent liquid-phase method according to claim 3, characterized in that, The preferred temperature for the high-temperature treatment is 1200℃.

5. The method for preparing highly dispersed platinum / Ketjenblack catalyst based on a weak reducing agent liquid-phase method according to claim 1, characterized in that, In S3, the weak reducing agent is selected from sodium sulfite, sodium bisulfite, sodium thiosulfate, vitamin C, or sodium citrate.

6. The method for preparing highly dispersed platinum / Ketjenblack catalyst based on a weak reducing agent liquid-phase method according to claim 5, characterized in that, The concentration of the weak reducing agent is 0.05-0.25 mol / L, and the pH is 4-10.

7. The method for preparing highly dispersed platinum / Ketjen black catalyst based on a weak reducing agent liquid-phase method according to claim 1, characterized in that, In S3, the oil bath treatment is carried out at a temperature of 60-100℃ for 1-5 hours.

8. A highly dispersed platinum / Ketjen black catalyst, characterized in that, It is prepared by the method described in any one of claims 1-7.

9. The highly dispersed platinum / Ketjen black catalyst according to claim 8, characterized in that, The platinum particles in the platinum / Ketjenblack catalyst have a size of 2.0-6.0 nm.

10. The application of the platinum / Ketjenblack catalyst as described in claim 8 or 9 in the membrane electrode assembly of a proton exchange membrane fuel cell.

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