Membrane electrode assembly based on three-dimensional nitrogen-doped graphene aerogel carrier and preparation method thereof, hydrogen fuel cell

Abstract

This invention discloses a membrane electrode assembly based on a three-dimensional nitrogen-doped graphene aerogel support and its preparation method, as well as a hydrogen fuel cell. The assembly includes a composite proton exchange membrane, an anode catalyst layer and a cathode catalyst layer coated on both sides of the composite proton exchange membrane, an anode gas diffusion layer located outside the anode catalyst layer, and a cathode gas diffusion layer located outside the cathode catalyst layer. Both the anode and cathode catalyst layers contain catalysts, and the catalyst support is a three-dimensional nitrogen-doped graphene aerogel. The composite proton exchange membrane is a perfluorosulfonic acid resin-based composite membrane containing sulfonated graphene oxide. This application uses a three-dimensional nitrogen-doped graphene aerogel as the catalyst support, and the resulting macroscopic three-dimensional network effectively prevents the stacking of graphene sheets. The composite proton exchange membrane has abundant sulfonic acid groups, which significantly improves the durability in accelerated aging tests and enhances the operational stability in low-humidity environments while maintaining high power density in the hydrogen fuel cell.

Description

Technical Field

[0001] This invention belongs to the field of fuel cell technology, and particularly relates to a membrane electrode assembly based on a three-dimensional nitrogen-doped graphene aerogel carrier, its preparation method, and a hydrogen fuel cell. Background Technology

[0002] Hydrogen fuel cells, as a highly efficient and clean energy conversion device, have broad application prospects in transportation and stationary power plants. The membrane electrode assembly (MEA) is the core component of a hydrogen fuel cell (PEMFC), and its performance directly determines the cell's power and lifespan. However, current commercially available MEAs face significant challenges: First, the catalyst support is unstable. Currently widely used carbon black supports such as Vulcan XC-72 are prone to electrochemical corrosion (carbon oxidation reaction) under battery start-up, shutdown and high-potential conditions, which leads to the shedding and aggregation of the supported platinum (Pt) particles, resulting in a sharp decrease in the electrochemical active surface area (ECSA).

[0003] Second, the performance of proton exchange membranes is limited. Traditional Nafion membranes rely on hydration to conduct protons, and their conductivity drops significantly under high temperature and low humidity conditions. In addition, Nafion membranes have insufficient mechanical strength and suffer from gas crossover, which not only reduces battery efficiency but also accelerates the chemical degradation of the membrane.

[0004] Graphene, as a two-dimensional carbon material, possesses extremely high electrical conductivity, specific surface area, and chemical stability. However, ordinary two-dimensional graphene sheets exhibit strong van der Waals forces, making them prone to irreversible stacking, leading to a loss of effective specific surface area and hindering the transport of reactant gases and water. Therefore, how to construct anti-stacking three-dimensional graphene structures and effectively apply them as key materials in fuel cells is a pressing technical problem that needs to be solved in this field. Summary of the Invention

[0005] The purpose of this invention is to provide a membrane electrode assembly based on a three-dimensional nitrogen-doped graphene aerogel carrier and its preparation method, as well as a hydrogen fuel cell, aiming to improve the durability and output performance of hydrogen fuel cells under harsh operating conditions.

[0006] To solve the above-mentioned technical problems, the present invention is mainly achieved through the following technical solutions: In a first aspect, the present invention provides a membrane electrode assembly based on a three-dimensional nitrogen-doped graphene aerogel support, comprising a composite proton exchange membrane, an anode catalyst layer and a cathode catalyst layer respectively coated on both sides of the composite proton exchange membrane, an anode gas diffusion layer located outside the anode catalyst layer, and a cathode gas diffusion layer located outside the cathode catalyst layer; both the anode catalyst layer and the cathode catalyst layer contain a catalyst, and the catalyst support is a three-dimensional nitrogen-doped graphene aerogel; the composite proton exchange membrane is a perfluorosulfonic acid resin-based composite membrane containing sulfonated graphene oxide. The membrane electrode assembly of the present invention eliminates traditional carbon black in the anode and cathode catalyst layers, employing a three-dimensional nitrogen-doped graphene aerogel as the catalyst support. The three-dimensional nitrogen-doped graphene aerogel forms a macroscopic three-dimensional network through precursor self-assembly, effectively preventing the stacking of graphene sheets and providing abundant pore structures for mass transfer; by introducing nitrogen atoms as anchoring sites, strong interactions are formed with the catalyst, significantly enhancing the catalyst's dispersion and anti-agglomeration ability. Simultaneously, nitrogen doping also improves the electronic structure of the three-dimensional nitrogen-doped graphene aerogel, which is beneficial for enhancing catalytic activity.

[0007] In some embodiments of this application, the nitrogen doping amount in the three-dimensional nitrogen-doped graphene aerogel is 3.0% to 8.0% of atomic percentage. For example, 3.0%, 4.0%, 5.0%, 6.0%, 7.0%, or 8.0%.

[0008] In some embodiments of this application, the specific surface area of ​​the three-dimensional nitrogen-doped graphene aerogel is greater than 500 m². 2 / g.

[0009] In some embodiments of this application, the catalyst is supported on platinum or platinum alloy nanoparticles. In this invention, the catalyst is supported on platinum or platinum alloy nanoparticles. Platinum possesses good chemical stability and corrosion resistance, and exhibits very high catalytic activity for the formation of hydroxide ions. Platinum alloys enhance the durability of the catalyst and further improve its specific activity. By loading platinum or platinum alloy nanoparticles onto three-dimensional nitrogen-doped graphene aerogel, electron conduction and the construction of the catalytic layer structure are facilitated.

[0010] In some embodiments of this application, the loading amount of the platinum or platinum alloy nanoparticles on the three-dimensional nitrogen-doped graphene aerogel support is 40wt% to 60wt%. For example, 40wt%, 45wt%, 50wt%, 55wt%, or 60wt%.

[0011] In some embodiments of this application, the average particle size of the platinum or platinum alloy nanoparticles is 2.5~4.5 nm. In this invention, by fabricating platinum or platinum alloy nanoparticles and highly dispersing them on a three-dimensional nitrogen-doped graphene aerogel, the electrochemically active surface area can be greatly increased, allowing for more complete participation in catalytic reactions.

[0012] In some embodiments of this application, the sulfonated graphene oxide added to the composite proton exchange membrane is 0.1 wt% to 1.5 wt% of the perfluorosulfonic acid resin matrix. For example, 0.1 wt%, 0.5 wt%, 1.0 wt%, 1.2 wt%, or 1.5 wt%.

[0013] In some embodiments of this application, the thickness of the composite proton exchange membrane is 10~25 μm. For example, 10 μm, 15 μm, 20 μm, or 25 μm.

[0014] In a second aspect, the present invention provides a method for preparing a membrane electrode assembly based on a three-dimensional nitrogen-doped graphene aerogel carrier as described in any one of the embodiments of the first aspect above. The preparation method includes the following steps: (1) preparing a three-dimensional nitrogen-doped graphene aerogel carrier by a combination of hydrothermal method and freeze-drying; (2) loading platinum nanoparticles onto the carrier by a polyol reduction method; (3) preparing an SGO / Nafion composite membrane by a solution blending casting method; and (4) assembling the membrane electrode by a spraying and hot-pressing process.

[0015] This invention utilizes sulfonated graphene oxide as a reinforcing filler introduced into the Nafion matrix. The sulfonated graphene oxide sheets have abundant sulfonic acid groups (-SO3H), which can provide additional proton transport hopping sites in low-humidity environments, improving the water retention capacity and proton conductivity of the membrane. At the same time, the two-dimensional sulfonated graphene oxide sheets construct a "maze effect" within the membrane, effectively blocking the direct permeation of hydrogen and oxygen, and enhancing the mechanical strength of the composite membrane.

[0016] In a third aspect, the present invention provides a hydrogen fuel cell comprising the membrane electrode assembly based on a three-dimensional nitrogen-doped graphene aerogel support as described in any one of the embodiments of the first aspect. Through dual modification of the catalyst support and the proton exchange membrane, the present invention significantly improves the durability in accelerated aging tests and enhances operational stability in low-humidity environments while maintaining high power density.

[0017] Compared with the prior art, the present invention has the following beneficial technical effects: (1) The membrane electrode assembly of the present invention abandons the traditional carbon black in the anode catalyst layer and the cathode catalyst layer, and uses three-dimensional nitrogen-doped graphene aerogel as catalyst support. The three-dimensional nitrogen-doped graphene aerogel forms a macroscopic three-dimensional network through precursor self-assembly, which can effectively prevent the stacking of graphene sheets and provide a rich pore structure for mass transfer. By introducing nitrogen atoms as anchoring points, it forms a strong interaction with the catalyst, which can significantly enhance the dispersion and anti-agglomeration ability of the catalyst. At the same time, nitrogen doping also improves the electronic structure of the three-dimensional nitrogen-doped graphene aerogel, which is beneficial to enhancing catalytic activity.

[0018] (2) In this invention, sulfonated graphene oxide is introduced into the Nafion matrix as a reinforcing filler. The sulfonated graphene oxide sheets have abundant sulfonic acid groups (-SO3H), which can provide additional proton transport hopping sites in low humidity environments, thereby improving the water retention capacity and proton conductivity of the membrane. At the same time, the two-dimensional sulfonated graphene oxide sheets construct a "maze effect" in the membrane, which effectively blocks the direct permeation of hydrogen and oxygen and enhances the mechanical strength of the composite membrane. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 A schematic diagram of the cross-sectional structure of the membrane electrode assembly based on a three-dimensional nitrogen-doped graphene aerogel carrier for a hydrogen fuel cell provided by the present invention. Figure 2 Fourier transform infrared (FT-IR) comparison of graphene oxide (GO) and sulfonated graphene oxide (SGO) provided by this invention; Figure 3 This is a comparison of the polarization curves of the hydrogen fuel cell of Example 1 and the hydrogen fuel cell of Comparative Example 1 before and after undergoing 30,000 voltage cycle accelerated aging tests. The horizontal axis represents current density (A / cm²), and the vertical axis represents battery voltage (V); solid lines represent before the test, and dashed lines represent after the test; black lines represent the hydrogen fuel cell of Comparative Example 1, and red lines represent the hydrogen fuel cell of Example 1 of this invention.

[0021] Explanation of reference numerals in the attached figures: 1. Composite proton exchange membrane; 2. Cathode catalyst layer; 3. Anode catalyst layer; 4. Cathode gas diffusion layer; 5. Anode gas diffusion layer. Detailed Implementation

[0022] The technical solution of the present invention will be clearly and completely described below with reference to specific embodiments. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the 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 scope of protection of the present invention.

[0023] In a first aspect, embodiments of this disclosure provide a membrane electrode assembly based on a three-dimensional nitrogen-doped graphene aerogel carrier, comprising a composite proton exchange membrane, an anode catalyst layer and a cathode catalyst layer respectively coated on both sides of the composite proton exchange membrane, an anode gas diffusion layer located outside the anode catalyst layer, and a cathode gas diffusion layer located outside the cathode catalyst layer; both the anode catalyst layer and the cathode catalyst layer contain a catalyst, and the catalyst carrier is a three-dimensional nitrogen-doped graphene aerogel; the composite proton exchange membrane is a perfluorosulfonic acid resin-based composite membrane containing sulfonated graphene oxide.

[0024] In some embodiments of this application, the nitrogen doping amount in the three-dimensional nitrogen-doped graphene aerogel is 3.0% to 8.0% of atomic percentage.

[0025] In some embodiments of this application, the specific surface area of ​​the three-dimensional nitrogen-doped graphene aerogel is greater than 500 m². 2 / g.

[0026] In some embodiments of this application, the catalyst is supported on platinum or platinum alloy nanoparticles.

[0027] In some embodiments of this application, the loading amount of the platinum or platinum alloy nanoparticles on the three-dimensional nitrogen-doped graphene aerogel support is 40wt%~60wt%.

[0028] In some embodiments of this application, the average particle size of the platinum or platinum alloy nanoparticles is 2.5 to 4.5 nm.

[0029] In some embodiments of this application, the sulfonated graphene oxide added to the composite proton exchange membrane is 0.1 wt% to 1.5 wt% of the perfluorosulfonic acid resin matrix.

[0030] In some embodiments of this application, the thickness of the composite proton exchange membrane is 10~25 μm.

[0031] In a second aspect, the present disclosure provides a method for preparing a membrane electrode assembly based on a three-dimensional nitrogen-doped graphene aerogel carrier as described in any one of the embodiments of the first aspect above. The preparation method includes the following steps: (1) preparing a three-dimensional nitrogen-doped graphene aerogel carrier by a combination of hydrothermal method and freeze-drying; (2) loading platinum nanoparticles onto the carrier by a polyol reduction method; (3) preparing an SGO / Nafion composite membrane by a solution blending casting method; and (4) assembling the membrane electrode by a spraying and hot-pressing process.

[0032] In a third aspect, embodiments of this disclosure provide a hydrogen fuel cell including the membrane electrode assembly based on a three-dimensional nitrogen-doped graphene aerogel carrier, as described in any one of the embodiments of the first aspect above.

[0033] Example 1: Key Material Preparation and Battery Assembly (1) Preparation of three-dimensional nitrogen-doped graphene aerogel support (3DN-GA) A modified Hummers method was used to prepare an aqueous dispersion of graphene oxide (GO) (concentration 3 mg / mL). 100 mL of the dispersion was mixed with 0.6 g of urea as both a nitrogen source and a reducing agent, and then ultrasonically mixed until homogeneous. The mixture was transferred to a hydrothermal reactor and reacted at 180 °C for 12 h to obtain a nitrogen-doped graphene hydrogel. After dialysis with deionized water until neutral, the gel was freeze-dried at -60 °C for 48 h to obtain a black, sponge-like 3D N-GA support. The nitrogen content was measured to be 5.5 at%, and the specific surface area was 620 m² / g.

[0034] (2) Preparation of Pt / 3DN-GA catalyst Using the ethylene glycol reduction method, 100 mg of the prepared 3DN-GA support was dispersed in an ethylene glycol / water mixed solvent, and a calculated amount of chloroplatinic acid solution was added to adjust the pH to 11. Under nitrogen protection, the mixture was refluxed at 130 °C for 3 h to reduce Pt and deposit it onto the support. After filtration, washing, and vacuum drying, a catalyst powder with a Pt loading of 50 wt% was obtained.

[0035] (3) Preparation of sulfonated graphene oxide (SGO) / Nafion composite proton exchange membrane Composite membranes were prepared by solution casting, which included the functionalization synthesis of SGO filler, the preparation of casting solution, and the heat treatment and activation after film formation.

[0036] ① Synthesis of sulfonated graphene oxide (SGO) Graphene oxide (GO) was surface modified by diazotization. 500 mg of graphene oxide powder was dispersed in 500 mL of deionized water and sonicated for 1 h to obtain a homogeneous dispersion. Under ice bath conditions (0–5 °C), 4.0 g of sulfanilic acid and 1.5 g of sodium nitrite were added sequentially, followed by dropwise addition of 10 mL of hydrochloric acid (1 mol / L) while stirring, initiating an in-situ diazotization reaction.

[0037] The reaction system was stirred in an ice bath for 2 hours, then heated to 60°C and reacted for another 24 hours, allowing benzenesulfonic acid groups to be covalently grafted onto the graphene lattice. The reaction product was subjected to multiple centrifugations, washing with water, and dialysis (to remove unreacted ions), and finally freeze-dried to obtain SGO powder.

[0038] Infrared characterization: Fourier transform infrared spectroscopy (FT-IR) was performed on graphene oxide (GO) and sulfonated graphene oxide (SGO). The results are shown in [Figure number missing]. Figure 2 .

[0039] Figure 2 In the diagram, curve a represents the GO precursor at 3400 cm⁻¹. -1 A broad -OH stretching vibration peak is displayed at this location.

[0040] Curve b represents SGO packing. Compared to GO, SGO has a lower concentration in the 1000–1250 cm³ range. -1 A new characteristic absorption peak appeared in the region. Specifically, at 1035 cm⁻¹. -1 The absorption peak at 1180 cm⁻¹ corresponds to the symmetric stretching vibration of the S=O bond in the sulfonic acid group. -1 The absorption peaks at these locations correspond to the asymmetric stretching vibrations of the S=O bond. The appearance of these new peaks confirms that p-aminobenzenesulfonic acid has been successfully grafted onto the surface of graphene oxide via chemical bonds, completing the sulfonation modification.

[0041] ② Preparation and defoaming of composite casting solution Weigh a certain amount of the SGO powder prepared in step ① above and add it to N,N-dimethylacetamide (DMAc) solvent. Then, treat it with a high-power ultrasonic cell disruptor for 30 minutes to form a homogeneous colloidal solution.

[0042] Subsequently, a 20% (w / w) Nafion resin solution (DuPont) was added, and the amount of SGO added was controlled to be 0.5 wt% of the Nafion resin solid content. The mixture was placed on a magnetic stirrer and stirred vigorously at 60°C for 12 h to achieve molecular-level blending.

[0043] To prevent pinholes in the film formation, the mixed solution was placed in a vacuum drying oven and allowed to stand for 2 hours at a vacuum of -0.09 MPa to remove bubbles until no visible bubbles remained in the solution.

[0044] ③ Casting and Gradient Heat Treatment Pour the degassed casting solution onto a clean, dry, horizontal glass plate, and use a doctor blade with a precision micrometer to spread the liquid film evenly.

[0045] Place the glass plate in a forced-air drying oven and perform the following gradient heating program to eliminate internal stress and induce crystallization.

[0046] 80℃ constant temperature for 12 hours: Slowly evaporate the solvent to prevent rapid solvent overflow that could cause cracking on the membrane surface; 100℃ constant temperature for 1 hour: to further remove residual high-boiling-point solvent (DMAc); 140℃ constant temperature for 30 min: Annealing is performed at a temperature close to the Nafion glass transition temperature to promote polymer chain rearrangement and enhance the mechanical strength and dimensional stability of the film.

[0047] ④ Protonation activation treatment After natural cooling, the membrane is peeled off the glass plate. To remove organic impurities and impart proton conductivity to the membrane, standard acid washing activation is required.

[0048] Boil in a 3% solution at 80°C for 1 hour (to remove organic impurities), then rinse with deionized water. Boil in 0.5 mol / L solution at 80°C for 1 h (to protonate the sulfonic acid groups); Finally, boil and rinse repeatedly with deionized water until neutral.

[0049] The final product was a semi-transparent black SGO / Nafion composite proton exchange membrane with uniform thickness (approximately 18±2 μm).

[0050] (4) Fabrication and assembly of membrane electrode assembly (MEA) The catalyst coating film (CCM) is constructed using an ultrasonic spraying process, which includes the preparation of the anodic catalyst layer, the preparation of the cathode catalyst layer, and the final hot pressing.

[0051] ① Preparation of the anode catalyst layer Weigh the Pt / 3DN-GA catalyst powder prepared in step (2) above and place it in a mixed solvent of isopropanol and deionized water (volume ratio 3:1). Then, add a 5% Nafion ionomer solution (as a binder and proton conductor) and control the mass ratio (I / C ratio) of the ionomer to the carbon support to be 0.25.

[0052] The mixture was placed in an ice bath and pre-dispersed for 15 minutes using a high-shear disperser, followed by high-frequency ultrasonic treatment for 30 minutes to obtain a uniformly dispersed anode catalyst ink without agglomeration.

[0053] The SGO / Nafion composite proton exchange membrane prepared in step (3) was fixed on a heated platform with vacuum adsorption function (platform temperature set to 80℃). An automatic ultrasonic sprayer was used to uniformly spray the anode catalyst ink onto one side of the composite membrane. By controlling the spray flow rate and the number of passes, the platinum (Pt) loading on the anode side was precisely controlled at 0.1 mg / cm². After spraying, the membrane was dried at 80℃ for 15 min to remove residual solvent.

[0054] ②Preparation of the cathode catalyst layer Considering the slow and water-prone nature of the cathode oxygen reduction reaction (ORR), the ink formulation needs to be optimized to create hydrophobic channels. Pt / 3D N-GA catalyst was weighed, and the solvent system was adjusted to n-propanol and deionized water (volume ratio 4:1), with 5% Nafion solution added to control the I / C ratio at 0.30.

[0055] The cathode catalyst ink was prepared using the same ice-bath ultrasonic dispersion process. The composite film already coated on the anode side was flipped over, and multiple layers were intermittently sprayed onto the other side. Due to the thickness of the cathode catalyst layer, a cyclic process of "spraying-drying-spraying" was adopted to prevent the film from absorbing moisture and swelling. The platinum (Pt) loading on the cathode side was controlled at 0.4 mg / cm². The final product was a CCM (Catalyst Coated Membrane) with catalyst layers coated on both sides.

[0056] ③Hot pressing and post-processing Two sheets of hydrophobically treated carbon fiber paper (containing 10 wt% PTFE) with a microporous layer (MPL) were selected as the gas diffusion layer (GDL). The prepared CCM was placed between the two GDL sheets, ensuring that the microporous layer side of the GDL was in close contact with the catalytic layer side of the CCM, forming a five-layer sandwich structure of "GDL-anode-film-cathode-GDL".

[0057] The sandwich structure was placed in a precision hot press and hot-pressed for 3 minutes at 135°C and 1.5 MPa to ensure tight bonding of the layers and reduce contact resistance. After hot pressing, it was allowed to cool naturally to room temperature and removed to obtain a membrane electrode assembly (MEA) based on a three-dimensional nitrogen-doped graphene aerogel carrier, as shown in the figure. Figure 1 As shown.

[0058] Comparative Example 1: A commercially available Pt / C catalyst (Tanaka Precious Metals, Japan, 50% Pt loading) and a commercial Nafion 211 membrane were used, and the remaining assembly and testing conditions were exactly the same as in Example 1.

[0059] Performance Test 1: Single Battery Test The membrane electrode assemblies of Example 1 (MEA) and Comparative Example 1 (MEA) were assembled into a single-cell test fixture, respectively. Tests were conducted at a cell temperature of 75°C, a hydrogen / air relative humidity of 50% (low humidity condition), and a back pressure of 150 kPa.

[0060] Test results: The peak power density of the battery in Example 1 reached 1.35 W / cm², while the peak power density of the battery in Comparative Example 1 was only 0.98 W / cm² under the same low humidity conditions. This indicates that the fuel cell prepared in Example 1 of this application has a higher power density and better performance.

[0061] Performance Test 2: 30,000-cycle accelerated aging test Test results: Combined Figure 3 As shown, before the aging test, the initial performance of the hydrogen fuel cell of Example 1 was slightly higher than that of Comparative Example 1. After 30,000 voltage cycle accelerated aging tests, the polarization curve of the hydrogen fuel cell of Example 1 still maintained a high voltage in the high current density region. The voltage decay was significantly smaller than that of the hydrogen fuel cell of Comparative Example 1. In particular, Example 1 showed no voltage decay in the operating current density range of 1.5 to 2.5 A / cm², while Comparative Example 1 experienced a voltage decay of 50 mV in this range. In the high current density region (3 to 3.5 A / cm²), the voltage decay of Example 1 was 100 mV, while that of Comparative Example 1 reached 150 mV in this range. This indicates that the hydrogen fuel cell of Example 1 of the present invention has excellent durability and electrochemical stability.

[0062] After disassembly, Example 1 showed no significant changes, while Comparative Example 1 showed obvious thinning of the catalyst layer and corrosion of the carbon support.

[0063] The comparison shows that the three-dimensional nitrogen-doped graphene aerogel support used in this invention effectively improves the stability and mass transfer capacity of the catalyst, and the SGO-enhanced composite proton exchange membrane improves the proton conductivity under low humidity conditions. The synergistic effect of the two significantly improves the overall performance and service life of the hydrogen fuel cell.

[0064] Therefore, compared with the prior art, the present invention has the following beneficial technical effects: (1) The membrane electrode assembly of the present invention abandons the traditional carbon black in the anode catalyst layer and the cathode catalyst layer, and uses three-dimensional nitrogen-doped graphene aerogel as catalyst support. The three-dimensional nitrogen-doped graphene aerogel forms a macroscopic three-dimensional network through precursor self-assembly, which can effectively prevent the stacking of graphene sheets and provide a rich pore structure for mass transfer. By introducing nitrogen atoms as anchoring points, it forms a strong interaction with the catalyst, which can significantly enhance the dispersion and anti-agglomeration ability of the catalyst. At the same time, nitrogen doping also improves the electronic structure of the three-dimensional nitrogen-doped graphene aerogel, which is beneficial to enhancing catalytic activity.

[0065] (2) In this invention, sulfonated graphene oxide is introduced into the Nafion matrix as a reinforcing filler. The sulfonated graphene oxide sheets have abundant sulfonic acid groups (-SO3H), which can provide additional proton transport hopping sites in low humidity environments, thereby improving the water retention capacity and proton conductivity of the membrane. At the same time, the two-dimensional sulfonated graphene oxide sheets construct a "maze effect" in the membrane, which effectively blocks the direct permeation of hydrogen and oxygen and enhances the mechanical strength of the composite membrane.

[0066] In the description of the above embodiments, specific features, structures, materials, or characteristics may be combined in any suitable manner in one or more embodiments or examples.

[0067] The above are merely specific embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A membrane electrode assembly based on a three-dimensional nitrogen-doped graphene aerogel carrier, characterized in that, The membrane comprises a composite proton exchange membrane, an anode catalyst layer and a cathode catalyst layer coated on both sides of the composite proton exchange membrane, an anode gas diffusion layer located outside the anode catalyst layer, and a cathode gas diffusion layer located outside the cathode catalyst layer; both the anode catalyst layer and the cathode catalyst layer contain a catalyst, and the catalyst support is a three-dimensional nitrogen-doped graphene aerogel; the composite proton exchange membrane is a perfluorosulfonic acid resin-based composite membrane containing sulfonated graphene oxide.

2. The membrane electrode assembly based on a three-dimensional nitrogen-doped graphene aerogel carrier according to claim 1, characterized in that, The nitrogen doping amount in the three-dimensional nitrogen-doped graphene aerogel is 3.0% to 8.0% of the atomic percentage.

3. The membrane electrode assembly based on a three-dimensional nitrogen-doped graphene aerogel carrier according to claim 1, characterized in that, The specific surface area of ​​the three-dimensional nitrogen-doped graphene aerogel is greater than 500 m². 2 / g.

4. The membrane electrode assembly based on a three-dimensional nitrogen-doped graphene aerogel carrier according to claim 1, characterized in that, The catalyst is supported on platinum or platinum alloy nanoparticles.

5. The membrane electrode assembly based on a three-dimensional nitrogen-doped graphene aerogel carrier according to claim 4, characterized in that, The loading amount of the platinum or platinum alloy nanoparticles on the three-dimensional nitrogen-doped graphene aerogel support is 40wt%~60wt%.

6. The membrane electrode assembly based on a three-dimensional nitrogen-doped graphene aerogel carrier according to claim 4, characterized in that, The average particle size of the platinum or platinum alloy nanoparticles is 2.5~4.5 nm.

7. The membrane electrode assembly based on a three-dimensional nitrogen-doped graphene aerogel carrier according to claim 1, characterized in that, In the composite proton exchange membrane, the added mass fraction of sulfonated graphene oxide is 0.1wt% to 1.5wt% of the perfluorosulfonic acid resin matrix.

8. The membrane electrode assembly based on a three-dimensional nitrogen-doped graphene aerogel carrier according to claim 1, characterized in that, The thickness of the composite proton exchange membrane is 10~25μm.

9. A method for preparing a membrane electrode assembly based on a three-dimensional nitrogen-doped graphene aerogel carrier as described in any one of claims 1 to 8, characterized in that, The preparation method includes the following steps: (1) A three-dimensional nitrogen-doped graphene aerogel carrier was prepared by combining hydrothermal method with freeze drying; (2) Platinum nanoparticles were loaded onto the support using a polyol reduction method; (3) SGO / Nafion composite membrane was prepared by solution blending casting method; (4) Assemble the membrane electrode by spraying and hot pressing processes.

10. A hydrogen fuel cell, characterized in that, The membrane electrode assembly based on a three-dimensional nitrogen-doped graphene aerogel carrier, as described in any one of claims 1 to 8 above.

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