A fuel cell membrane electrode with a vein biomimetic structure catalytic layer and a preparation method thereof

Abstract

The application discloses a fuel cell membrane electrode with a vein biomimetic structure catalytic layer and a preparation method thereof, and the method comprises the following steps: coating a catalyst slurry on a transfer substrate with a vein biomimetic structure and performing drying treatment to obtain a transfer substrate with a catalytic layer; sticking two transfer substrates with catalytic layers on both sides of a proton exchange membrane, transferring the catalytic layer to the proton exchange membrane through hot pressing, removing the transfer substrate, and obtaining a CCM; cutting, edge sealing and sticking gas diffusion layers on both sides of the obtained CCM to obtain a membrane electrode with a vein biomimetic structure catalytic layer. The scheme provided by the application can solve the problems of incomplete transfer, structural defects, low mass transfer efficiency and unstable interface combination, and a high-performance fuel cell membrane electrode with a vein biomimetic structure catalytic layer is obtained, thereby providing technical support for the large-scale preparation of the fuel cell membrane electrode.

Description

Technical Field

[0001] This invention belongs to the field of battery membrane electrode technology, and specifically relates to a fuel cell membrane electrode with a leaf vein biomimetic catalytic layer and its preparation method. Background Technology

[0002] The fuel cell membrane electrode transfer method is a technique for preparing a catalyst coating membrane (CCM) by transferring a catalyst layer from a temporary support onto a proton exchange membrane. The core principle of this method is to first coat a catalyst slurry onto a transfer substrate, dry it to form a catalyst layer, then transfer the catalyst layer onto the proton exchange membrane using hot pressing, and finally remove the transfer substrate to complete the CCM preparation. The advantages of this method are that the proton exchange membrane does not come into contact with the solvent during preparation, effectively avoiding the membrane's "swelling" problem and improving the dimensional accuracy and process stability of the membrane electrode. Due to its strong process controllability, uniform catalyst layer thickness, and ability to achieve precision preparation, the transfer method is applied to the large-scale production of membrane electrodes. However, existing transfer methods for preparing the catalyst layer and assembling the membrane electrode suffer from problems such as incomplete transfer, easy generation of structural defects, unstable interface between the catalyst layer and the proton exchange membrane / gas diffusion layer, low mass transfer efficiency, difficulties in water management, and uneven distribution of reaction sites. These issues prevent the catalyst layer from fully realizing its performance, thus hindering the large-scale application and performance improvement of the membrane electrode. Summary of the Invention

[0003] Objective: In order to overcome the shortcomings of the existing technology, the present invention provides a solution.

[0004] Technical solution: To solve the above technical problems, the technical solution adopted by the present invention is as follows: In a first aspect, a method for preparing a fuel cell membrane electrode with a leaf vein-inspired biomimetic catalytic layer is provided, comprising: The catalyst slurry was coated onto a transfer substrate with a leaf vein biomimetic structure and dried to obtain a transfer substrate with a catalyst layer. Two transfer substrates with catalytic layers are bonded together with the catalytic layer side facing both sides of the proton exchange membrane. The catalytic layer is transferred to the proton exchange membrane by hot pressing. The transfer substrate is then removed to obtain the CCM. The obtained CCM is cut, sealed, and a gas diffusion layer is attached to both sides to obtain a membrane electrode with a leaf vein biomimetic catalytic layer.

[0005] The fuel cell membrane electrode preparation method provided by this invention is simple and easy to implement, and the designed leaf vein biomimetic structure can provide active sites, guide liquid to avoid water flooding, and improve mass transfer efficiency.

[0006] In some embodiments, the method for preparing the catalyst slurry includes: The catalyst was mixed with ultrapure water and ultrasonically dispersed to obtain dispersion one. Carbon-based materials, perfluorosulfonic acid resin and organic solvent are mixed and sheared to obtain dispersion II; Dispersion 2 was added dropwise to dispersion 1, followed by the addition of an organic solvent. The catalyst slurry was obtained by ultrasonic shearing dispersion and high-pressure homogenization.

[0007] In some embodiments, the catalyst is a platinum-carbon catalyst with a platinum content of 20wt% to 50wt%; The carbon-based materials include carbon nanofibers and carbon nanotubes; The organic solvent is selected from at least one of ethanol, isopropanol, or ethylene glycol; The mass ratio of the organic solvent to ultrapure water is 0.4~3.1; The perfluorosulfonic acid resin accounts for 5% to 30% of the mass of the catalyst slurry.

[0008] In some embodiments, the method for preparing the fuel cell membrane electrode with a leaf vein-inspired biomimetic catalytic layer further includes: A catalyst slurry is then coated onto the obtained transfer substrate with the catalyst layer. The mass percentage of perfluorosulfonic acid resin is higher than that of the catalyst slurry coated on the transfer substrate with the leaf vein biomimetic structure. After drying, a gradient catalyst layer is formed. The first slurry layer is coated first, followed by the second slurry layer, ensuring that the mass percentage of perfluorosulfonic acid resin in the first slurry layer is lower than that in the second slurry layer. This creates two regions with different mass concentrations of perfluorosulfonic acid resin in the catalyst layer after drying, thus generating a gradient, promoting mass transfer efficiency, and improving the interfacial bonding strength between the catalyst layer and the proton exchange membrane.

[0009] In some embodiments, the method for preparing the transfer substrate includes: Select at least one of the following methods to prepare leaf vein biomimetic structures on the transfer substrate: mechanical polishing, ion irradiation etching, plasma physical etching, laser etching, and chemical treatment; The surface of the transfer substrate with a leaf vein biomimetic structure is modified by laser etching to obtain a transfer substrate with a leaf vein biomimetic structure.

[0010] In some embodiments, the parameters of the laser etching include: The processing power is 8~20W, and the scanning speed is 200~1500mm / s; In some embodiments, the surface energy of the surface-modified transfer substrate needs to be controlled at 30~40mN / m, and the roughness needs to be controlled at 0.5~2μm; In some embodiments, the material of the transfer substrate is selected from polytetrafluoroethylene (PTFE) film.

[0011] In a second aspect, a fuel cell membrane electrode with a leaf vein-inspired biomimetic catalytic layer, prepared by the method for preparing a fuel cell membrane electrode with a leaf vein-inspired biomimetic catalytic layer according to any one of the first aspects, is provided, comprising: The catalyst layer, comprising a cathode catalyst layer and an anode catalyst layer, both feature leaf vein-inspired structures; The proton exchange membrane has a cathode catalytic layer and an anode catalytic layer attached to both sides, respectively; The gas diffusion layer is bonded to the cathode catalyst layer and the anode catalyst layer respectively.

[0012] In some embodiments, the leaf vein biomimetic structure adopts a hierarchical fractal structure, including 2 to 4 levels; When the leaf vein biomimetic structure adopts a two-level fractal structure, it includes the main vein and the first-level lateral veins; When the leaf vein biomimetic structure adopts a three-level fractal structure, it includes the main vein, the primary lateral vein, and the secondary lateral vein; When the leaf vein biomimetic structure adopts a 4-level fractal structure, it includes the main vein, primary lateral veins, secondary lateral veins, and veinlets; The main vein is used for long-distance gas / water transport, while the smaller veins are used for localized infiltration and supply to reaction sites.

[0013] In some embodiments, the angle between each level of leaf vein in the leaf vein biomimetic structure and the branch of the next level leaf vein is 30°~60°, and the spacing is 200~800μm; The coverage rate of the leaf vein biomimetic structure is 30%~70%; The aspect ratio of the microchannels in the leaf vein biomimetic structure is 0.2~1.2; the edges of the leaf vein biomimetic structure are designed with rounded corners, and the rounded corner radius is ≥5μm.

[0014] In some embodiments, the platinum loading of the cathode catalyst layer is 0.2~0.5 mg / cm³. 2 The platinum loading of the anode catalyst layer is 0.05~0.15 mg / cm³. 2 ; In some embodiments, when the catalyst layer is a gradient catalyst layer, the thickness of the catalyst layer is 15~35μm, the thickness of the leaf vein biomimetic structure region is 10~20μm, and the thickness of the substrate region is 5~10μm; the leaf vein biomimetic structure region is the catalyst layer region formed after the catalyst slurry coated on the transfer substrate with the leaf vein biomimetic structure is dried, and the substrate region is the catalyst layer region formed after the catalyst slurry coated on the transfer substrate with the catalyst layer is dried.

[0015] Beneficial effects: The fuel cell membrane electrode with a leaf vein biomimetic catalytic layer and its preparation method provided by the present invention have the following advantages: The leaf vein-inspired structure facilitates the distribution and guidance of water vapor within the membrane electrode, effectively improving the mass transfer efficiency of the catalytic layer and providing more reaction sites, thereby enhancing the performance of the catalytic layer. Surface modification of the transfer substrate ensures complete structural transfer and prevents membrane electrode assembly interface detachment and deformation. At the same time, the gradient catalytic layer improves the interfacial stability between the catalytic layer and the proton exchange membrane / gas diffusion layer. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the structure of a fuel cell membrane electrode with a leaf vein biomimetic catalytic layer according to an embodiment of the present invention; Figure 2 Comparison of voltage-current density curves and power-current density curves of single cells assembled from membrane electrodes prepared in the embodiments and comparative examples of the present invention. Figure 3 This is a comparison of the electrochemical impedance spectroscopy of single cells assembled from the membrane electrodes prepared in the embodiments and comparative examples of the present invention. Detailed Implementation

[0017] The technical solutions 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. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of the present invention.

[0018] The present invention will be further described below with reference to specific embodiments.

[0019] Example 1: This example provides a fuel cell membrane electrode with a leaf vein biomimetic catalytic layer and its preparation method.

[0020] S1: Mix 50wt% platinum-carbon catalyst with ultrapure water, wherein the mass ratio of catalyst to water is 1:8, and disperse by ultrasonication to obtain dispersion one; S2: Carbon nanofibers, carbon nanotubes, perfluorosulfonic acid resin, and a portion of ethanol are mixed and sheared and dispersed for 30-50 minutes to obtain dispersion II. The mass ratio of carbon nanofibers and carbon nanotubes to the catalyst is 8%.

[0021] S3: Add two drops of dispersion to one of dispersion, add the remaining ethanol, disperse by ultrasonic shearing, and homogenize under high pressure to obtain catalyst slurry. The mass ratio of perfluorosulfonic acid resin in the slurry is 20%.

[0022] S4: PTFE film was selected as the transfer substrate. The leaf vein biomimetic structure was prepared by mechanical polishing and ion irradiation etching. The substrate was modified by laser etching with a processing power of 10W and a scanning speed of 500mm / s. The surface energy of the modified carrier was controlled at 30mN / m and the roughness was controlled at 0.5μm.

[0023] S5: The catalyst slurry was coated onto the laser-etched PTFE substrate using a slot coating method and dried in an oven at 70°C. The platinum loading of the cathode catalyst layer was 0.35 mg / cm³. 2 The platinum loading of the anode catalyst layer is 0.1 mg / cm³. 2 .

[0024] The obtained biomimetic structure of the catalytic layer leaf vein adopts a two-level fractal structure, including the main vein and the first-level lateral vein. The angle between the main vein and the first-level lateral vein is controlled at 35°, the spacing is 400μm, and the structure coverage is controlled at 50%.

[0025] Two dried transfer substrates are placed on both sides of the proton exchange membrane, with the catalytic layers facing the proton exchange membrane. The anion and anodic catalytic layers are then transferred onto the proton exchange membrane by hot pressing or rolling. The transfer substrates on the anion and anodic sides are then removed sequentially to obtain the CCM.

[0026] S6: Cut and seal the prepared CCM and attach a gas diffusion layer to both sides to obtain the desired fuel cell membrane electrode with a leaf vein biomimetic catalytic layer.

[0027] Example 2: This example provides a fuel cell membrane electrode with a leaf vein biomimetic catalytic layer and its preparation method. The preparation method is the same as in Example 1, except that two catalyst slurries are prepared in this example, including slurry 1 and slurry 2; wherein, the mass percentage of perfluorosulfonic acid resin in slurry 1 is 25%, and the mass percentage of perfluorosulfonic acid resin in slurry 2 is 10%; in step S5, slurry 2 is first coated onto a laser-etched PTFE substrate and dried in a 70°C oven to form the leaf vein biomimetic structure region of the catalytic layer; then slurry 1 is coated onto the leaf vein biomimetic structure region and dried in a 70°C oven to form the matrix region, resulting in a ladder-like structure. A gradient catalyst layer with a thickness of 15 μm, a leaf vein-inspired biomimetic structure region with a thickness of 10 μm, and a substrate region with a thickness of 5 μm are prepared. Following the remaining steps in S5 and S6, a fuel cell membrane electrode with a leaf vein-inspired biomimetic catalyst layer is obtained. This includes a catalyst layer comprising a cathode catalyst layer and an anode catalyst layer, both with leaf vein-inspired biomimetic structures; a proton exchange membrane with the cathode and anode catalyst layers attached to both sides; and a gas diffusion layer bonded to both the cathode and anode catalyst layers. The catalyst layer is a gradient catalyst layer, as shown in the image. Figure 1 As shown.

[0028] Example 3: This example provides a fuel cell membrane electrode with a leaf vein biomimetic structure catalyst layer and its preparation method. The preparation method is the same as in Example 2, except that the leaf vein biomimetic structure adopts a three-level fractal structure, including a main vein, a primary lateral vein, and a secondary lateral vein, to obtain a fuel cell membrane electrode with a leaf vein biomimetic structure catalyst layer.

[0029] Comparative Example 1: This comparative example provides a fuel cell membrane electrode and its preparation method. The preparation method is the same as in Example 1, except that no leaf vein biomimetic structure is prepared on the PTFE substrate, nor is the surface of the PTFE substrate modified. Instead, a catalyst slurry is directly coated on the substrate to prepare the membrane electrode.

[0030] The membrane electrodes prepared in Examples 1-3 and Comparative Example 1 were all assembled into single cells for testing. The polarization curve testing conditions were: cell temperature 85℃, anode and cathode dew point temperature 70℃, and anode and cathode outlet back pressure 150kPa. The AC impedance test point was 1.8A / cm. 2 .

[0031] Table 1: Comparison of current density and total impedance of the assembled batteries in Examples 1-3 and Comparative Example 1

[0032] According to Table 1, Figure 2 and Figure 3 It can be seen that when the current density is greater than 1000 mA / cm² 2 In this case, the single-cell performance of Example 1 was higher than that of Comparative Example 1, indicating that the leaf vein biomimetic structure improves the performance of the membrane electrode. The single-cell performance of the membrane electrode in Example 2 was significantly higher than that in Example 1. Combined with... Figure 3 The impedance spectra in Example 2 also show that the impedance is lower than that of Comparative Example 1 and Example 1, indicating that the gradient catalytic layer improves the interfacial bonding strength between the catalytic layer and the proton exchange membrane, reducing mass transfer resistance. The superior performance of Example 3 demonstrates that the multi-level network of the leaf vein biomimetic structure is more conducive to the distribution of water vapor within the membrane electrode, avoiding flooding.

[0033] Example 4: This example provides a fuel cell membrane electrode with a leaf vein biomimetic catalytic layer and its preparation method.

[0034] S1: Mix 20wt% platinum-carbon catalyst with ultrapure water, wherein the mass ratio of catalyst to water is 1:8, and disperse by ultrasonication to obtain dispersion one; S2: Carbon nanofibers, carbon nanotubes, perfluorosulfonic acid resin, and a portion of isopropanol are mixed and sheared and dispersed for 30-50 minutes to obtain dispersion II. The mass ratio of carbon nanofibers and carbon nanotubes to the catalyst is 25%.

[0035] S3: Add two drops of dispersion to one of dispersion, add the remaining isopropanol, disperse by ultrasonic shearing, and homogenize under high pressure to obtain catalyst slurry. The mass percentage of perfluorosulfonic acid resin in the slurry is 5%, and the mass ratio of isopropanol to ultrapure water is 0.4.

[0036] S4: PTFE film was selected as the transfer substrate. The leaf vein biomimetic structure was prepared by plasma physical etching and laser etching. The substrate was modified by laser etching. The processing power was 8W and the scanning speed was 200mm / s. The surface energy of the modified carrier was controlled at 30mN / m and the roughness was controlled at 1.2μm.

[0037] S5: The catalyst slurry was coated onto the laser-etched PTFE substrate using a slot coating method and dried in an oven at 60°C. The platinum loading of the cathode catalyst layer was 0.2 mg / cm³. 2 The platinum loading of the anode catalyst layer is 0.05 mg / cm³. 2 .

[0038] The obtained biomimetic structure of leaf veins in the catalytic layer adopts a two-level fractal structure, including a main vein and a primary lateral vein. The angle between the main vein and the primary lateral vein is controlled at 30°, the spacing is 200μm, the structure coverage is controlled at 30%, the aspect ratio of the microchannel of the leaf vein biomimetic structure is 0.2, and the edge of the leaf vein biomimetic structure is designed with a rounded corner radius of 5μm.

[0039] Two dried transfer substrates are placed on both sides of the proton exchange membrane, with the catalytic layers facing the proton exchange membrane. The anion and anodic catalytic layers are then transferred onto the proton exchange membrane by hot pressing or rolling. The transfer substrates on the anion and anodic sides are then removed sequentially to obtain the CCM.

[0040] S6: Cut and seal the prepared CCM and attach a gas diffusion layer to both sides to obtain the desired fuel cell membrane electrode with a leaf vein biomimetic catalytic layer.

[0041] Example 5: This example provides a fuel cell membrane electrode with a leaf vein biomimetic catalytic layer and its preparation method.

[0042] S1: Mix 35wt% platinum-carbon catalyst with ultrapure water, wherein the mass ratio of catalyst to water is 1:8, and disperse by ultrasonication to obtain dispersion one; S2: Carbon nanofibers, carbon nanotubes, perfluorosulfonic acid resin, and a portion of ethylene glycol are mixed and sheared and dispersed for 30-50 minutes to obtain dispersion II. The mass ratio of carbon nanofibers and carbon nanotubes to the catalyst is 16%.

[0043] S3: Add two drops of dispersion to one of dispersion, add the remaining ethylene glycol, disperse by ultrasonic shearing, and homogenize under high pressure to obtain catalyst slurry 1. The mass ratio of perfluorosulfonic acid resin in the slurry is 30%, and the mass ratio of isopropanol to ultrapure water is 3.1.

[0044] Catalyst slurry 2 was prepared according to the preparation methods of S1~S3, except that the mass percentage of perfluorosulfonic acid resin in the slurry was 15%. S4: PTFE film was selected as the transfer matrix, and a leaf vein biomimetic structure was prepared by chemical treatment. The matrix was modified by laser etching with a processing power of 20W and a scanning speed of 1500mm / s. The surface energy of the modified carrier was controlled at 40mN / m and the roughness was controlled at 2μm.

[0045] S5: First, slurry 2 is coated onto the laser-etched PTFE substrate and dried in an 80℃ oven to form the leaf vein-inspired biomimetic structure region of the catalyst layer; then, slurry 1 is coated onto the leaf vein-inspired biomimetic structure region and dried again in an 80℃ oven to form the matrix region, resulting in a gradient catalyst layer with a thickness of 35μm, a leaf vein-inspired biomimetic structure region thickness of 20μm, and a matrix region thickness of 10μm. The platinum loading of the cathode catalyst layer is 0.5mg / cm³. 2 The platinum loading of the anode catalyst layer is 0.15 mg / cm³. 2 .

[0046] The obtained biomimetic structure of leaf veins in the catalytic layer adopts a four-level fractal structure, including a main vein, primary lateral veins, secondary lateral veins, and veinlets. The angle between the main vein and the primary lateral veins is controlled at 60° with a spacing of 200 μm. The angle between the primary lateral veins and the secondary lateral veins is controlled at 50° with a spacing of 500 μm. The angle between the secondary lateral veins and the veinlets is controlled at 35° with a spacing of 800 μm. The structure coverage is controlled at 70%. The aspect ratio of the microchannels in the biomimetic structure of leaf veins is 1.2, and the edges of the biomimetic structure of leaf veins are designed with a rounded corner radius of 7 μm.

[0047] Two dried transfer substrates are placed on both sides of the proton exchange membrane, with the catalytic layers facing the proton exchange membrane. The anion and anodic catalytic layers are then transferred onto the proton exchange membrane by hot pressing or rolling. The transfer substrates on the anion and anodic sides are then removed sequentially to obtain the CCM.

[0048] S6: Cut and seal the prepared CCM and attach a gas diffusion layer to both sides to obtain the desired fuel cell membrane electrode with a leaf vein biomimetic catalytic layer.

[0049] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing a fuel cell membrane electrode with a leaf vein-inspired biomimetic catalytic layer, characterized in that, include: The catalyst slurry was coated onto a transfer substrate with a leaf vein biomimetic structure and dried to obtain a transfer substrate with a catalyst layer. Two transfer substrates with catalytic layers are bonded together with the catalytic layer side facing both sides of the proton exchange membrane. The catalytic layer is transferred to the proton exchange membrane by hot pressing. The transfer substrate is then removed to obtain the CCM. The obtained CCM is cut, sealed, and a gas diffusion layer is attached to both sides to obtain a membrane electrode with a leaf vein biomimetic catalytic layer.

2. The method for preparing a fuel cell membrane electrode with a leaf vein-inspired biomimetic catalytic layer according to claim 1, characterized in that, The method for preparing the catalyst slurry includes: The catalyst was mixed with ultrapure water and ultrasonically dispersed to obtain dispersion one. Carbon-based materials, perfluorosulfonic acid resin and organic solvent are mixed and sheared to obtain dispersion II; Dispersion 2 was added dropwise to dispersion 1, followed by the addition of an organic solvent. The catalyst slurry was obtained by ultrasonic shearing dispersion and high-pressure homogenization.

3. The method for preparing a fuel cell membrane electrode with a leaf vein-inspired biomimetic catalytic layer according to claim 2, characterized in that, The catalyst is a platinum-carbon catalyst with a platinum content of 20wt%~50wt%; The carbon-based materials include carbon nanofibers and carbon nanotubes; The organic solvent is selected from at least one of ethanol, isopropanol, or ethylene glycol; The mass ratio of the organic solvent to ultrapure water is 0.4~3.1; The perfluorosulfonic acid resin accounts for 5%-30% of the catalyst slurry by mass.

4. The method for preparing a fuel cell membrane electrode with a leaf vein-inspired biomimetic catalytic layer according to claim 3, characterized in that, The method for preparing the fuel cell membrane electrode with the leaf vein-inspired biomimetic catalytic layer further includes: A catalyst slurry is then coated onto the obtained transfer substrate with the catalyst layer, wherein the mass ratio of perfluorosulfonic acid resin is higher than that of the catalyst slurry coated onto the transfer substrate with the leaf vein biomimetic structure, and then dried to form a gradient catalyst layer.

5. The method for preparing a fuel cell membrane electrode with a leaf vein-inspired biomimetic catalytic layer according to claim 1, characterized in that, The method for preparing the transfer substrate includes: Select at least one of the following methods to prepare leaf vein biomimetic structures on the transfer substrate: mechanical polishing, ion irradiation etching, plasma physical etching, laser etching, and chemical treatment; The surface of the transfer substrate with a leaf vein biomimetic structure is modified by laser etching to obtain a transfer substrate with a leaf vein biomimetic structure.

6. The method for preparing a fuel cell membrane electrode with a leaf vein-inspired biomimetic catalytic layer according to claim 5, characterized in that, The parameters of the laser etching include: The processing power is 8~20W, and the scanning speed is 200~1500mm / s; And / or, the surface energy of the surface-modified transfer substrate needs to be controlled at 30~40mN / m, and the roughness needs to be controlled at 0.5~2μm; And / or, the material of the transfer matrix is ​​selected from PTFE membrane.

7. A fuel cell membrane electrode with a leaf vein-inspired biomimetic catalytic layer prepared by the method for preparing a fuel cell membrane electrode with a leaf vein-inspired biomimetic catalytic layer according to any one of claims 1 to 6, characterized in that, include: The catalyst layer, comprising a cathode catalyst layer and an anode catalyst layer, both feature leaf vein-inspired structures; The proton exchange membrane has a cathode catalytic layer and an anode catalytic layer attached to both sides, respectively; The gas diffusion layer is bonded to the cathode catalyst layer and the anode catalyst layer respectively.

8. The fuel cell membrane electrode with a leaf vein-inspired biomimetic catalytic layer according to claim 7, characterized in that, The leaf vein biomimetic structure adopts a hierarchical fractal structure, including 2 to 4 levels; When the leaf vein biomimetic structure adopts a two-level fractal structure, it includes the main vein and the first-level lateral veins; When the leaf vein biomimetic structure adopts a three-level fractal structure, it includes the main vein, the primary lateral vein, and the secondary lateral vein; When the leaf vein biomimetic structure adopts a 4-level fractal structure, it includes the main vein, primary lateral veins, secondary lateral veins, and veinlets; The main vein is used for long-distance gas or liquid transport, while the veinlets are used for localized infiltration and supply to reaction sites.

9. The fuel cell membrane electrode with a leaf vein-inspired biomimetic catalytic layer according to claim 8, characterized in that, The leaf vein biomimetic structure has a leaf vein at each level with its next level branch at an angle of 30° to 60° and a spacing of 200 to 800 μm. The coverage rate of the leaf vein biomimetic structure is 30%~70%; The aspect ratio of the microchannels in the leaf vein biomimetic structure is 0.2~1.2; the edges of the leaf vein biomimetic structure are designed with rounded corners, and the rounded corner radius is ≥5μm.

10. The fuel cell membrane electrode with a leaf vein-inspired biomimetic catalytic layer according to claim 7, characterized in that, The platinum loading of the cathode catalyst layer is 0.2~0.5 mg / cm³. 2 The platinum loading of the anode catalyst layer is 0.05~0.15 mg / cm³. 2 ; And / or, when the catalyst layer is a gradient catalyst layer, the thickness of the catalyst layer is 15~35μm, the thickness of the leaf vein biomimetic structure region is 10~20μm, and the thickness of the substrate region is 5~10μm; the leaf vein biomimetic structure region is the catalyst layer region formed after the catalyst slurry coated on the transfer substrate with the leaf vein biomimetic structure is dried, and the substrate region is the catalyst layer region formed after the catalyst slurry coated on the transfer substrate with the catalyst layer is dried.

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