Fuel cell catalyst, preparation method thereof and membrane electrode

Abstract

The invention discloses a fuel cell catalyst, a preparation method thereof and a membrane electrode. The catalyst comprises platinum or platinum alloy nanoparticles and a carbon carrier formed by plasma in-situ carbonization, the platinum alloy is an alloy formed by platinum and at least one of cobalt and nickel; the preparation method comprises the following steps: vacuumizing, introducing carrier gas, and applying an electric field to a reaction cavity; and conveying a carbon source gas and a platinum-containing precursor to the high-temperature plasma region for reaction, cooling a gas-solid mixture generated after the reaction, separating and collecting a solid product to obtain the fuel cell catalyst. Through the mode, the catalyst has high activity and high durability, and the preparation method realizes atomic-scale tough compounding of the platinum nanoparticles and the carbon carrier, so that long-life stability and high catalytic activity which are far better than those of a traditional catalyst are synchronously obtained; due to the efficient and continuous production process, the production efficiency is greatly improved, and the energy consumption and the time cost are reduced.

Description

Technical Field

[0001] This invention relates to the field of new energy materials, and in particular to a highly active and stable catalyst for proton exchange membrane fuel cells, a method for preparing the catalyst, and a membrane electrode assembled from the catalyst. Background Technology

[0002] Hydrogen is a clean and efficient energy carrier. Proton exchange membrane fuel cells (PEMFCs) are the core devices that directly convert the chemical energy of hydrogen into electrical energy, offering significant advantages such as high energy conversion efficiency, rapid start-up, and zero emissions. However, the oxygen reduction reaction kinetics at the cathode in fuel cells are slow, requiring the extensive use of platinum-based catalysts to reduce the reaction overpotential. This directly leads to the high cost of fuel cells, hindering their large-scale commercial application.

[0003] Currently, the most commonly used commercial fuel cell catalyst is the Pt / C catalyst, which consists of platinum nanoparticles supported on a carrier such as carbon black. The mainstream preparation method is the wet chemical method, for example, mixing a platinum precursor solution such as chloroplatinic acid with a carbon support, and then using a reducing agent in water or an organic solvent to reduce platinum ions to metallic platinum nanoparticles, which are then deposited on the surface of the carbon support.

[0004] However, in terms of durability, the Pt / C catalyst prepared by this traditional wet chemical method suffers from weak bonding between Pt nanoparticles and the carbon support. Under harsh operating conditions such as frequent start-stop cycles and high potential fluctuations in fuel cells, Pt nanoparticles are prone to migration, detachment, and aggregation, leading to rapid decay of the electrochemical active surface area and a rapid decline in battery performance. Although subsequent heat treatment can enhance the bonding to some extent, the effect is limited and may even cause Pt particles to grow, resulting in a decrease in initial activity. In terms of the preparation process, the wet chemical method is lengthy, typically involving multiple steps such as solution mixing, stirring, reduction, precipitation, filtration, washing, drying, and heat treatment. This process is complex, has low production efficiency, and is difficult to scale up for continuous production. Regarding environmental impact, mass production requires the use of large amounts of water or organic solvents and generates wastewater containing metal ions, resulting in additional environmental treatment costs. Summary of the Invention

[0005] The main technical problem solved by this invention is to provide a highly active and stable catalyst for proton exchange membrane fuel cells that overcomes the shortcomings of existing fuel cell catalysts, such as insufficient durability, complex preparation process, and lack of environmental friendliness, as well as a simple, efficient, and environmentally friendly preparation method.

[0006] To solve the above-mentioned technical problems, one technical solution adopted by the present invention is to provide a fuel cell catalyst, wherein the catalyst comprises platinum or platinum alloy nanoparticles and a carbon support formed by in-situ plasma carbonization; wherein the platinum alloy is an alloy formed by platinum (Pt) and at least one metal selected from cobalt (Co) and nickel (Ni), and the carbon support is amorphous carbon.

[0007] Platinum or platinum alloy nanoparticles serve as catalytic active centers, responsible for the efficient oxygen reduction reaction. Optimizing the electronic structure of platinum through alloying can further enhance the initial mass-to-specific activity of the catalyst.

[0008] The carbon support formed by in-situ plasma carbonization exhibits extremely strong bonding forces with active particles, thus achieving high durability. The support forms instantaneously at high temperatures, resulting in a stable structure. The amorphous carbon support is a natural result of the rapid pyrolysis and carbonization of the carbon source gas in plasma, possessing abundant defects that facilitate charge transport and metal anchoring.

[0009] In a preferred embodiment of the present invention, the average particle size of the platinum or platinum alloy nanoparticles is preferably 2-6 nanometers. This preferred range ensures a high specific surface area and abundant active sites for the catalyst. The nanoscale particle size allows for sufficient exposure of platinum atoms, ensuring a high electrochemical active area and high specific activity. Simultaneously, the uniform particle size distribution contributes to achieving consistent catalytic performance.

[0010] Another technical solution adopted by the present invention is: providing a method for preparing the fuel cell catalyst, comprising the following steps:

[0011] S1. Evacuate the plasma reaction chamber, then introduce carrier gas into the chamber and apply an electric field to the reaction chamber to generate high-temperature plasma.

[0012] S2. The carbon source gas and platinum-containing precursor are transported to the high-temperature plasma region, and the reaction is carried out in the high-temperature region of the plasma by controlling the power of the plasma, the pressure in the reaction chamber, and the feeding parameters of the carbon source gas and platinum-containing precursor, so that the carbon carrier formed by the decomposition of the carbon source gas and the platinum or platinum alloy nanoparticles formed by the platinum-containing precursor can achieve in-situ composite.

[0013] S3. Cool the gas-solid mixture produced after the reaction, separate and collect the solid products to obtain the fuel cell catalyst.

[0014] In a preferred embodiment of the present invention, the carrier gas is argon (Ar); the carbon source gas is at least one of methane (CH4) or acetylene (C2H2), which is easily cracked and carbonized at high plasma temperatures.

[0015] In a preferred embodiment of the present invention, the platinum-containing precursor includes platinum powder, a mixed metal powder of platinum and cobalt or nickel, a platinum compound solution, or a mixed solution containing platinum compounds. Metal powder is suitable for dry feeding, simplifying the process. Compound solutions are suitable for applications requiring smaller particle sizes and higher dispersion, yielding extremely small particles of 2-3 nanometers.

[0016] In a preferred embodiment of the present invention, the platinum compound solution includes one of chloroplatinic acid solution or dinitrosodiammine platinum solution, and the mixed solution includes a nickel compound or a cobalt compound.

[0017] In a preferred embodiment of the present invention, when the platinum-containing precursor is a solution, it is atomized and sent into the plasma reaction zone, and hydrogen (H2) is simultaneously introduced into the reaction chamber as a reducing gas.

[0018] In a preferred embodiment of the present invention, the power of the plasma is controlled between 5 kW and 60 kW; the pressure within the reaction chamber is controlled between 10,000 Pa and 50,000 Pa. Power directly affects the temperature and energy of the plasma, determining the degree of evaporation, ionization, and reaction of the precursors. Pressure affects the gas flow rate, reactant residence time, and the shape of the plasma torch.

[0019] In a preferred embodiment of the present invention, the volumetric flow rate ratio of the plasma carrier gas to the carbon source gas is controlled between 5:1 and 15:1. This ratio is crucial for controlling the amount and properties of the carbon support generated. A ratio that is too small may lead to excessive carbon coating, masking active sites; a ratio that is too large will result in insufficient support. The preferred range ensures that the carbon source can be effectively pyrolyzed to form an appropriate amount and shape of carbon support, achieving optimized composite with metal particles.

[0020] Another technical solution adopted in this invention is to provide a membrane electrode assembly (MEA) whose catalytic layer comprises the aforementioned fuel cell catalyst. Applying the prepared high-performance catalyst to the MEA enables the fuel cell to directly utilize its high activity and ultra-long durability, ultimately achieving low-voltage operation at high current density and a long service life, thus solving a core pain point in the commercialization of fuel cells.

[0021] The beneficial effects of this invention are as follows: By instantaneously ionizing the carbon source gas and the metal precursor at high temperature, this invention achieves atomic-level robust composite formation of platinum nanoparticles and a carbon support, thereby simultaneously obtaining a long lifespan stability and high catalytic activity far exceeding that of traditional catalysts. Through high-frequency plasma in-situ synthesis technology, it overcomes the inherent defects of poor catalyst durability, complex processes, and high pollution in traditional wet synthesis, producing a catalyst with both high activity and high durability. This invention transforms lengthy batch production into a highly efficient continuous process, greatly improving production efficiency, reducing energy consumption and time costs, and laying a solid foundation for large-scale commercial applications. Attached Figure Description

[0022] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort, wherein:

[0023] Figure 1 This is a schematic diagram of the process flow for preparing the fuel cell catalyst according to the present invention. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0025] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0026] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0027] In the description of this invention, it should be noted that the terms "front," "rear," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship in which the product of the invention is conventionally placed during use. These terms are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first," "second," etc., are used only to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0028] In the description of this invention, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set" and "connection" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0029] In this invention, unless otherwise expressly specified and limited, "above or below" a first feature may include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on" the first feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the first feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0030] like Figure 1 As shown, the carrier gas and reactants are fed into the plasma reaction chamber, where they react at high temperature to generate catalyst powder, which is then collected.

[0031] This invention includes:

[0032] Example 1: A method for preparing a fuel cell catalyst, comprising the following steps:

[0033] S1. Evacuate the high-frequency plasma equipment's reaction chamber to below 100 Pa. Introduce argon as the carrier gas and methane as the carbon source gas into the chamber at a volumetric flow rate ratio of 15:1, with a total flow rate of 60 L / min. Apply an electric field to the reaction chamber to generate plasma, setting the power to 5 kW. Maintain the reaction pressure at 50,000 Pa.

[0034] S2. Platinum (Pt) powder with a particle size of 1 μm is transported to the high-temperature plasma region via argon carrier gas (flow rate 5 L / min) at a feed rate of 1 g / min. Methane, the carbon source gas, is mixed with the carrier gas and introduced. Under these conditions, the methane is cracked and carbonized to form a carbon support, while the platinum powder is evaporated, ionized, and forms platinum nanoparticles. The two then undergo in-situ recombination within the high-temperature plasma region.

[0035] S3. Cool the gas-solid mixture produced after the reaction, separate and collect the solid product.

[0036] Characterization revealed that the product prepared using platinum powder as a precursor was a platinum-supported Pt / C catalyst on amorphous carbon, with an average Pt nanoparticle size of approximately 4 nm.

[0037] Example 2: A method for preparing a fuel cell catalyst, comprising the following steps:

[0038] S1. After evacuating the reaction chamber of the high-frequency plasma equipment, argon as the carrier gas and acetylene as the carbon source gas are introduced into the chamber at a volumetric flow rate ratio of 5:1, with a total flow rate of 120 L / min. The plasma is then excited at a power of 30 kW. The reaction pressure is 30000 Pa.

[0039] S2. A mixture of Pt and Co powder with a particle size of 1 μm (Pt:Co molar ratio = 1:3) is transported to the plasma region by argon carrier gas (flow rate 10 L / min) at a feeding rate of 4 g / min. Acetylene recombines with the in-situ formed Pt and Co particles.

[0040] S3. Cool, separate and collect the solid products.

[0041] Characterization revealed that the product prepared using mixed metal powder as a precursor was a PtCo alloy / C catalyst with an average particle size of approximately 5 nm.

[0042] Example 3: A method for preparing a fuel cell catalyst, comprising the following steps:

[0043] S1. After evacuating the reaction chamber of the high-frequency plasma equipment, introduce argon as the carrier gas, methane as the carbon source gas, and acetylene as the carbon source gas, with a volumetric flow rate ratio of 14:1:1 and a total flow rate of 60 L / min. Excite the plasma with a power of 60 kW. The reaction pressure is 10000 Pa.

[0044] S2. A mixture of Pt powder and Ni powder with a particle size of 1 μm (Pt:Ni molar ratio = 1:2) is conveyed by a carrier gas (flow rate 10 L / min) at a feeding rate of 6 g / min.

[0045] S3. Cool, separate and collect the solid products.

[0046] Characterization revealed that the product prepared by using mixed metal powder as a precursor and mixed carbon source was a PtNi alloy / C catalyst with an average particle size of approximately 6 nm.

[0047] Example 4: A method for preparing a fuel cell catalyst, comprising the following steps:

[0048] S1. After evacuating the reaction chamber of the high-frequency plasma equipment, introduce argon as the carrier gas, methane as the carbon source gas, and hydrogen as the reducing gas into the chamber at a volumetric flow rate ratio of 10:1:1, with a total flow rate of 120 L / min. Excite the plasma with a power of 10 kW. The reaction pressure is 20000 Pa.

[0049] S2. A 1 mol / L aqueous solution of chloroplatinic acid is ultrasonically atomized and then delivered to the plasma region via a carrier gas (flow rate of 20 L / min) at a supply rate of 100 mL / min. Hydrogen gas reduces platinum compounds to metallic platinum.

[0050] S3. Cool, separate and collect the solid products.

[0051] Characterization revealed that the product prepared using chloroplatinic acid solution as a precursor was a Pt / C catalyst with an average particle size of approximately 2 nm.

[0052] Example 5: A method for preparing a fuel cell catalyst, comprising the following steps:

[0053] S1. After evacuating the reaction chamber of the high-frequency plasma equipment, introduce argon as the carrier gas, acetylene as the carbon source gas, and hydrogen as the reducing gas, with a volumetric flow rate ratio of 10:1:1 and a total flow rate of 120 L / min. Excite the plasma with a power of 20 kW. The reaction pressure is 30000 Pa.

[0054] S2. A 1 mol / L solution of dinitrosodiammineplatinum is atomized and delivered to the plasma region at a supply rate of 200 mL / min.

[0055] S3. Cool, separate and collect the solid products.

[0056] Characterization revealed that the product prepared using dinitrosodiammine platinum solution as a precursor was a Pt / C catalyst with an average particle size of approximately 3 nm.

[0057] Example 6: A method for preparing a fuel cell catalyst, comprising the following steps:

[0058] S1. Same as Example 4.

[0059] S2. A mixed aqueous solution containing 1 mol / L chloroplatinic acid and 3 mol / L cobalt nitrate is atomized and delivered to the plasma region at a supply rate of 300 mL / min.

[0060] S3. Cool, separate and collect the solid products.

[0061] Characterization revealed that the product prepared using the mixed solution as a precursor was a PtCo / C catalyst with an average particle size of approximately 4 nm.

[0062] Example 7: A method for preparing a fuel cell catalyst, comprising the following steps:

[0063] S1. After evacuating the reaction chamber of the high-frequency plasma equipment, introduce argon as the carrier gas, acetylene as the carbon source gas, and hydrogen as the reducing gas, with a volumetric flow rate ratio of 5:1:1 and a total flow rate of 120 L / min. Excite the plasma with a power of 30 kW and a reaction pressure of 30000 Pa.

[0064] S2. Atomize and deliver a mixed aqueous solution containing 1 mol / L chloroplatinic acid and 2 mol / L nickel nitrate at a supply rate of 500 mL / min.

[0065] S3. Cool, separate and collect the solid products.

[0066] Characterization revealed that the product prepared using the mixed solution as a precursor was a PtNi / C catalyst with an average particle size of approximately 3 nm.

[0067] Comparative Example 1 (no carbon source gas, product is pure Pt particles)

[0068] S1. After evacuating the reaction chamber of the high-frequency plasma equipment, only argon (Ar) carrier gas is introduced into the chamber at a flow rate of 60 L / min. The plasma is then excited at a power of 5 kW. The reaction pressure is 50000 Pa.

[0069] S2. Pt powder with a particle size of 1 μm is conveyed by a carrier gas (flow rate of 5 L / min) at a feeding rate of 1 g / min. Because no carbon source gas is introduced, a carbon carrier cannot be formed.

[0070] S3. Cool, separate and collect the solid products.

[0071] Pure Pt nanoparticles with an average particle size of approximately 20 nm were obtained without a carbon support.

[0072] Comparative Example 2 (no carbon source gas, solution as precursor, product is pure Pt particles)

[0073] S1. After evacuating the reaction chamber of the high-frequency plasma equipment, argon and hydrogen carrier gases are introduced into the chamber at a volumetric flow rate ratio of 10:1, with a total flow rate of 120 L / min. The plasma is then excited at a power of 10 kW. The reaction pressure is 25000 Pa.

[0074] S2. A 1 mol / L chloroplatinic acid solution was atomized and delivered at a rate of 100 mL / min. Because no carbon source gas was introduced, a carbon support could not be formed.

[0075] S3. Cool, separate and collect the solid products.

[0076] Pure Pt nanoparticles with an average particle size of approximately 12 nm were obtained without a carbon support.

[0077] 1. The physicochemical characterization of the catalyst powders prepared in Examples 1-7 and Comparative Examples 1-2 showed that:

[0078] The catalysts prepared in Examples 1-7 of this invention have uniform platinum or platinum alloy nanoparticles with an average particle size distribution between 2 and 6 nanometers. X-ray diffraction and other analyses confirmed that the carbon support in the catalyst is amorphous carbon; when cobalt and nickel are used, a platinum-based alloy is successfully formed, rather than a simple physical mixture.

[0079] Comparative Examples 1 and 2, lacking the introduction of a carbon source gas, failed to form a carbon support, resulting in pure platinum nanoparticles with a significantly increased average particle size (>10 nm). This result demonstrates, conversely, that introducing a carbon source gas is a key factor in achieving efficient dispersion of metal particles, inhibiting their agglomeration and growth, and thus obtaining fine and uniform nanostructures.

[0080] 2. Membrane electrode preparation and electrochemical performance testing: The catalysts, ionomers (D520), and solvents prepared in the examples and comparative examples were mixed and dispersed to form a catalyst layer ink, which was then further prepared into a membrane electrode. The specific steps are as follows:

[0081] Using ultrasonic spraying, catalytic layer ink is directly sprayed onto the surface of the proton exchange membrane to form thin cathode and anode catalytic layers on the membrane. Then, a diffusion layer is covered on the outside of the cathode and anode catalytic layers by hot pressing to obtain the fuel cell membrane electrode assembly. The fuel cell membrane electrode assembly is then assembled into a single cell.

[0082] The electrochemical active area was tested using cyclic voltammetry under the following conditions: scan range of 0.01V-1.15V and scan rate of 20mV / s.

[0083] Mass specific activity was tested using a rotating disk electrode under the following conditions: scan range of 0.2V-1.0V, scan speed of 5mV / s, and RDE rotation speed of 1600rpm.

[0084] The electrochemical active area, as well as the initial mass-to-volume activity and the mass-to-volume activity after 30,000 cycles, were measured. The test results are shown in the table below:

[0085]

[0086] The data in the table above shows that:

[0087] (1) The initial electrochemical active area (ECSA) of the catalysts in all examples was greater than 100 m². 2 / g, significantly better than the comparative example (≤72.3 m 2 The high specific surface area (ECSA) of the catalyst prepared in this invention (at a rate of 1 / g) is mainly due to the smaller size of its platinum-based nanoparticles. After 30,000 cycles, the ECSA retention rate of the catalyst in this example exceeded 90%, with a decay rate of less than 10%; while the ECSA retention rate of the comparative catalyst was less than 85%, with a decay rate exceeding 20%. This indicates that the catalyst prepared in this invention has a strong binding force between the platinum (alloy) nanoparticles and the carbon support, effectively inhibiting the dissolution and loss of the active component during cycling.

[0088] (2) The mass-to-specific activity of the catalysts in the examples was generally higher than that in the comparative examples. Among them, the intrinsic activity of the Pt / C catalysts (Examples 1, 4, 5) was improved due to the synergistic effect of the carbon support; while the activity of the Pt alloy / C catalysts (Examples 2, 3, 6, 7) was further improved by the electronic structure regulation effect of Co and Ni.

[0089] After 30,000 cycles, the mass-specific activity decay rate of the catalysts in all examples was less than 10%, far lower than that of the comparative examples (>20%). This is attributed to the stable crystal structure formed by high-temperature plasma synthesis and the robust interaction between the metal and the support, which together ensured the structural integrity and activity stability of the catalysts during long-term operation.

[0090] In summary, this invention successfully prepared a fuel cell catalyst with both high activity and high stability through high-frequency plasma in-situ synthesis technology, effectively solving the key technical bottleneck of poor durability of traditional catalysts.

[0091] The above description is merely an embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural or procedural transformations made based on the content of the present invention specification, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. A fuel cell catalyst, characterized in that, The catalyst comprises platinum or platinum alloy nanoparticles and a carbon support formed by in-situ plasma carbonization; the platinum alloy is an alloy formed by platinum and at least one of cobalt and nickel, and the carbon support is amorphous carbon.

2. The fuel cell catalyst according to claim 1, characterized in that, The average particle size of the platinum or platinum alloy nanoparticles is 2-6 nanometers.

3. A method for preparing a fuel cell catalyst as described in any one of claims 1 to 2, characterized in that, Includes the following steps: S1. Evacuate the plasma reaction chamber, then introduce carrier gas into the chamber and apply an electric field to the reaction chamber to generate high-temperature plasma. S2. The carbon source gas and platinum-containing precursor are transported to the high-temperature plasma region, and the reaction is carried out in the high-temperature region of the plasma by controlling the power of the plasma, the pressure in the reaction chamber, and the feeding parameters of the carbon source gas and platinum-containing precursor, so that the carbon carrier formed by the decomposition of the carbon source gas and the platinum or platinum alloy nanoparticles formed by the platinum-containing precursor can achieve in-situ composite. S3. Cool the gas-solid mixture produced after the reaction, separate and collect the solid products to obtain the fuel cell catalyst.

4. The preparation method according to claim 3, characterized in that, The carrier gas is argon; the carbon source gas is at least one of methane or acetylene.

5. The preparation method according to claim 3, characterized in that, The platinum-containing precursor includes platinum powder, a mixed metal powder of platinum and cobalt or nickel, a platinum compound solution, or a mixed solution containing platinum compounds.

6. The preparation method according to claim 5, characterized in that, The platinum compound solution includes either chloroplatinic acid solution or dinitrosodiammine platinum solution, and the mixed solution includes either a nickel compound or a cobalt compound.

7. The preparation method according to claim 3, characterized in that, When the platinum-containing precursor is in solution, it is atomized and sent into the plasma reaction zone, and hydrogen gas is simultaneously introduced into the reaction chamber as a reducing gas.

8. The preparation method according to claim 3, characterized in that, The power of the plasma is controlled between 5 kW and 60 kW; the pressure inside the reaction chamber is controlled between 10,000 Pa and 50,000 Pa.

9. The preparation method according to claim 3, characterized in that, The volumetric flow ratio of the plasma carrier gas to the carbon source gas is controlled between 5:1 and 15:

1.

10. A membrane electrode, characterized in that, Its catalyst layer comprises a fuel cell catalyst as described in any one of claims 1 to 2.

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