Graphene nanoparticle composite aerogel microsphere and preparation method thereof
The preparation of nitrogen-sulphur co-doped graphene aerogel microspheres by airflow-assisted electrostatic spraying method was solved, and the problems of uneven dispersion and poor stability of DMFCs catalysts were achieved, and the efficient loading and catalytic performance of Pt nanoparticles were improved.
Patent Information
- Application Number
- CN202510656812.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-05-21
- Publication Date
- 2025-08-22
AI Technical Summary
The existing anode catalysts of direct methanol fuel cells (DMFCs) have problems with low catalytic activity and easy to poison, and the inter-layer stacking of graphene results in a degradation of catalytic performance, making it difficult to achieve uniform dispersion and stability of precious metal nanoparticles.
Nitrosulfide co-doped graphene aerogel microspheres were prepared by airflow-assisted electrostatic spraying method. Regularly shaped microspheres were prepared by compounding with small-molecular compounds containing sulfur and nitrogen groups, and used to support Pt nanoparticles to improve the dispersion and stability of the catalyst.
The uniform dispersion and efficient loading of Pt nanoparticles are achieved, and the stability and catalytic performance of the catalyst are improved, especially in the methanol oxidation reaction, which shows a high current density.
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Figure CN120515348A_ABST
Abstract
Description
Technical Field
[0001] The present invention belongs to the field of three-dimensional graphene catalyst carriers, and particularly relates to nitrogen-sulfur co-doped graphene aerogel microspheres and a preparation method and application thereof. Technical Background
[0002] In the search for sustainable clean energy solutions, direct methanol fuel cells (DMFCs) have attracted considerable interest among various types of fuel cells due to their many advantages, including high power density, low emissions, easy recharging, simple structure, and rapid start-up at low temperatures. Despite their significant advantages, DMFCs still face many challenges, such as low catalytic activity and susceptibility to poisoning. Currently, commercial anode catalysts for DMFCs are primarily based on platinum / carbon black (Pt / C) materials. Due to the inherent microporous properties of carbon black and the lack of surface growth sites, it is difficult to ensure uniform dispersion of platinum particles and suppress their size, resulting in a short service life of the Pt catalyst. Therefore, selecting a suitable support to reduce catalyst agglomeration and utilizing the synergistic effect between the catalyst and the support to improve catalyst performance is an effective approach.
[0003] Graphene has been widely studied for its large surface area and excellent electrical conductivity. Due to the van der Waals forces and π–π bonds between graphene layers, graphene layers often easily stack to form graphite powder. This severely limits the surface utilization of 2D graphene nanosheets and reduces their inherent excellent performance. For example, when graphene is used as a catalyst support material, the stacking of layers leads to a decrease in the activity of electrochemical reaction sites and a reduction in the efficiency of electrolyte ion conduction within the electrode material, which severely affects the performance of the catalyst. Porous three-dimensional (3D) graphene aerogels have been widely reported as a new type of support material. They maximize the advantages of graphene and aerogels, such as high surface area, high porosity, and high electrical conductivity. They facilitate the uniform dispersion of precious metal nanoparticles and effectively avoid the problem of catalytic performance degradation caused by the stacking of graphene sheets. Compared with bulk aerogels, graphene aerogel microspheres not only share the characteristics of graphene aerogels but also have the advantage of flexible and controllable size. Therefore, they are considered to be a highly promising support material.
[0004] Doping or further functionalization can effectively activate the graphene surface, which is crucial for fully realizing its excellent properties. Numerous studies have shown that doping graphene with heteroatoms such as N, B, S, and P can introduce a large number of defects, which serve as active sites to anchor catalytic particles with enhanced dispersibility and finer size. When nitrogen-sulfur co-doped graphene aerogel microspheres are used as supports, the porous structure of the graphene microspheres and the numerous defects present in their layers enhance their interaction with Pt NPs, effectively improving the dispersion of the supported metal and immobilizing the active metal particles, preventing metal migration and agglomeration, and enhancing catalyst stability.
[0005] In order to avoid the stacking of graphene oxide sheets and improve the stability of the graphene aerogel structure, we proposed a new method to composite graphene oxide with small molecule compounds containing sulfur and nitrogen groups to prepare three-dimensional S, N co-doped reduced graphene aerogel microspheres (Pt / NS-GAMs) carriers for anchoring PtNPs as anode catalysts for methanol oxidation reaction. Summary of the Invention
[0006] To address the problems of low loading rate and poor dispersion effect of Pt nanoparticles loaded on graphene aerogel microspheres, the present invention aims to provide a process for preparing graphene aerogel microspheres by airflow-assisted electrostatic spraying using graphite oxide and small molecule compounds containing sulfur and nitrogen groups as raw materials.
[0007] The technical solution adopted by the present invention to achieve the above-mentioned purpose is:
[0008] The present invention first discloses a method for preparing nitrogen-sulfur co-doped graphene aerogel microspheres, comprising the following steps:
[0009] (1) Preparation of small molecule compound composite aqueous dispersion:
[0010] First, 0.01 to 3.6 g of a small molecule compound containing sulfur and nitrogen groups is added to 100 mL of deionized water and magnetically stirred for 0.5 to 1 hour. After it is fully dissolved, a small molecule compound dispersion is obtained; then 0.4 to 1.2 g of graphene oxide is added to the above small molecule compound dispersion and mechanically stirred at a speed of 500 to 800 r / min for 8 to 10 hours. Finally, the above mixture is transferred to a 40KHz ultrasonic cleaning machine and ultrasonically stirred for 0.5 to 2 hours to obtain a small molecule compound composite aqueous dispersion.
[0011] (2) Preparation of graphene oxide / small molecule compounds containing sulfur and nitrogen groups composite aerogel microspheres:
[0012] The small molecule compound is composited into a syringe, a coaxial needle is installed on the syringe, and the syringe is loaded onto an electrostatic spray device, and a voltage of 12 to 18 kV and an air pressure of 0.2 to 0.6 MPa are applied; a receiving bath is located below the syringe; the receiving bath is a receiving tank filled with n-hexane, and the receiving tank is placed in an ethyl acetate Dewar tank cooled with liquid nitrogen, or the Dewar tank filled with liquid nitrogen is directly used as a receiving bath; after airflow-assisted electrostatic spraying, the ice microspheres and n-hexane or liquid nitrogen are separated using a 400 to 800 mesh sieve, and the ice microspheres are then freeze-dried at -50°C and 30 Pa for 48 hours to obtain graphene oxide / small molecule compound composite aerogel microspheres containing sulfur and nitrogen groups.
[0013] (3) Preparation of graphene aerogel microspheres:
[0014] The graphene oxide / small molecule compound containing sulfur and nitrogen groups composite aerogel microspheres are prepared in a high-purity nitrogen or argon atmosphere, heated to 600-1000°C at a heating rate of 2-5°C / min, kept at a constant temperature for 1-4 hours, and cooled to room temperature to obtain graphene aerogel microspheres.
[0015] Furthermore, the graphene oxide has 1 to 2 layers, a sheet diameter of 0.2 to 10 μm, a sheet thickness of 1 to 2 μm, a carbon content of <48%, and an oxygen content of >47%.
[0016] Furthermore, the small molecule compound containing sulfur and nitrogen groups is a water-soluble compound, including:
[0017] One or more of L-cysteine, L-cystine, L-methionine, 3-mercaptopropionic acid, 2,5-diamino-1,3,4-thiadiazole, 6-thioguanine, 2-mercaptopyrimidine, (4-acetylphenyl)thiourea, and thiourea.
[0018] Furthermore, the nitrogen-sulfur co-doped graphene aerogel microspheres have a particle size of 10 to 80 μm and a specific surface area of 150 to 450 g·m 2 .
[0019] The present invention also discloses graphene aerogel microspheres prepared according to any of the above preparation methods.
[0020] The present invention also discloses an application of preparing nitrogen-sulfur co-doped graphene aerogel microsphere catalysts based on the graphene aerogel microspheres, comprising:
[0021] Graphene aerogel microspheres and platinum precursors were added to an ethylene glycol solution, magnetically stirred for 12 hours, then loaded into a high-pressure reactor and placed in an oven at a constant temperature of 140-180°C for 12 hours. After the reactor was cooled to room temperature, it was filtered and then freeze-dried at -50°C and 30 Pa for 16-24 hours to obtain a graphene aerogel microsphere catalyst.
[0022] Compared with the prior art, the present invention has the following beneficial effects:
[0023] 1. This invention uses the airflow-assisted electrostatic spraying method for the first time to prepare nitrogen-sulfur co-doped graphene aerogel microspheres.
[0024] 2. The preparation method of the present invention combines pressure spraying and electrostatic spraying for the first time, solving the problems of poor sphericity of aerogel microspheres prepared by pressure spraying and low efficiency of aerogel microspheres prepared by electrostatic spraying, and can be used for mass production of aerogel microspheres.
[0025] 3. The nitrogen-sulfur co-doped graphene aerogel microspheres obtained for the first time by the preparation method described in the present invention have regular shapes, small volumes and are distributed in the range of 10 to 80 μm. This is the first time that the characteristics of small size, functionalization and efficient preparation are combined in the preparation of arbitrary graphene oxide composite microspheres. BRIEF DESCRIPTION OF THE DRAWINGS
[0026] Figure 1 This is a diagram of the process of preparing graphene aerogel composite microspheres in Example 2 of the present invention.
[0027] Figure 2 This is a scanning electron microscope image of graphene aerogel composite microspheres prepared in Example 2 of the present invention.
[0028] Figure 3 This is a scanning electron microscope image of graphene oxide aerogel microspheres prepared in Comparative Example 2 of the present invention.
[0029] Figure 4 These are transmission electron micrographs of Pt / GAMs prepared in Example 2 of the present invention and a statistical diagram of the particle size of platinum nanoparticles loaded thereon, wherein the left one is a transmission electron micrograph of Pt / GAMs; the right one is a statistical diagram of the particle size of platinum nanoparticles loaded thereon by Pt / GAMs.
[0030] Figure 5 This is a transmission electron microscope photo of Pt / rGO prepared in comparative example 1 of the present invention and a statistical diagram of the particle size of platinum nanoparticles loaded thereon, wherein the left one is a transmission electron microscope photo of Pt / rGO; the right one is a statistical diagram of the particle size of platinum nanoparticles loaded thereon by Pt / rGO.
[0031] Figure 6 Cyclic voltammetry curves of Pt / NS-GAMs and comparative samples Pt / rGO and Pt / GAMs prepared in a mixed solution of 0.5 M H2SO4 and 1.0 M CH3OH (scan rate: 50 mV·s) in Example 2 of the present invention and Comparative Examples 1 and 2. -1 ). DETAILED DESCRIPTION
[0032] In order to make the objectives, technical solutions and advantages of the present disclosure more clearly understood, the present disclosure is further described in detail below in conjunction with specific embodiments and with reference to the accompanying drawings.
[0033] Example 1
[0034] A nitrogen-sulfur co-doped graphene aerogel microsphere loaded with PtNPs as a catalyst comprises the following steps:
[0035] (1) Preparation of graphene oxide / L-cysteine dispersion
[0036] 0.03 g of L-cysteine was added to 100 mL of deionized water and magnetically stirred for 0.5 h until the L-cysteine was fully dissolved to obtain an L-cysteine aqueous solution.
[0037] (2) 0.6 g of graphene oxide was added to the above L-cysteine aqueous solution, and mechanically stirred at a speed of 600 r / min for 8 h, and then ultrasonically stirred in an ice-water bath for 0.5 h to obtain a graphene oxide / L-cysteine dispersion.
[0038] (3) The graphene oxide / L-cysteine dispersion obtained above was loaded into a syringe and loaded onto an electrostatic spray device, with an applied voltage of 15 kV and an applied air pressure of 0.4 MPa. A receiving bath was located below the syringe. The receiving bath was a receiving tank filled with n-hexane, and the receiving tank was placed in a Dewar tank filled with ethyl acetate cooled with liquid nitrogen. After airflow-assisted electrostatic spraying, the ice microspheres and n-hexane were separated, and the ice microspheres were then freeze-dried at -50°C and 30 Pa for 48 hours to obtain graphene oxide / small molecule compounds containing sulfur and nitrogen groups composite aerogel microspheres.
[0039] (4) The graphene oxide / small molecule compound containing sulfur and nitrogen groups composite aerogel microspheres were prepared in a high-purity nitrogen atmosphere by heating to 800°C at a heating rate of 5°C / min and then keeping the temperature constant for 2h. The nitrogen-sulfur co-doped graphene aerogel microspheres were obtained by cooling to room temperature.
[0040] (5) 15 mg of nitrogen-sulfur co-doped graphene aerogel microspheres and 10 mg of chloroplatinic acid hexahydrate were added to 54 mL of ethylene glycol solution, slowly magnetically stirred for 12 h, and then loaded into a high-pressure reactor. The mixture was placed in an oven at 160 ° C and kept constant for 12 h. After the reactor was cooled to room temperature, it was filtered and then freeze-dried at -50 ° C and 30 Pa for 24 h to obtain nitrogen-sulfur co-doped graphene aerogel microsphere platinum-based catalyst.
[0041] (6) Ag / AgCl was used as the reference electrode, platinum wire as the counter electrode, Pt / NS-GAMs-coated glassy carbon electrode as the working electrode, and a mixed solution of 0.5 M H2SO4 and 1.0 M CH3OH as the electrolyte to characterize the electrochemical oxidation performance of Pt / NS-GAMs.
[0042] Example 2
[0043] A nitrogen-sulfur co-doped graphene aerogel microsphere loaded with PtNPs as a catalyst comprises the following steps:
[0044] (1) Preparation of graphene oxide / L-cysteine dispersion
[0045] 0.06 g of L-cysteine was added to 100 mL of deionized water and magnetically stirred for 0.5 h until the L-cysteine was fully dissolved to obtain an L-cysteine aqueous solution.
[0046] (2) 0.6 g of graphene oxide was added to the above L-cysteine aqueous solution, and mechanical stirring was performed at a speed of 600 r / min for 8 h. Ultrasonic mechanical stirring was continued for 0.5 h in an ice-water bath to obtain a graphene oxide / L-cysteine dispersion.
[0047] (3) The graphene oxide / L-cysteine dispersion obtained above was loaded into a syringe and loaded onto an electrostatic spray device, with an applied voltage of 15 kV and an applied air pressure of 0.3 MPa. A receiving bath was located below the syringe. The receiving bath was a receiving tank filled with n-hexane, and the receiving tank was placed in a Dewar tank filled with ethyl acetate cooled with liquid nitrogen. After airflow-assisted electrostatic spraying, the ice microspheres and n-hexane were separated, and the ice microspheres were then freeze-dried at -50°C and 30 Pa for 48 hours to obtain graphene oxide / small molecule compounds containing sulfur and nitrogen groups composite aerogel microspheres.
[0048] (4) The graphene oxide / small molecule compound containing sulfur and nitrogen groups composite aerogel microspheres were prepared in a high-purity nitrogen atmosphere by heating to 800°C at a heating rate of 5°C / min and then keeping the temperature constant for 2h. The nitrogen-sulfur co-doped graphene aerogel microspheres were obtained by cooling to room temperature.
[0049] (5) 15 mg of nitrogen-sulfur co-doped graphene aerogel microspheres and 10 mg of chloroplatinic acid hexahydrate were added to 54 mL of ethylene glycol solution, slowly magnetically stirred for 12 h, and then loaded into a high-pressure reactor. The mixture was placed in an oven at 160 ° C and kept constant for 12 h. After the reactor was cooled to room temperature, it was filtered and then freeze-dried at -50 ° C and 30 Pa for 24 h to obtain nitrogen-sulfur co-doped graphene aerogel microsphere platinum-based catalyst.
[0050] (6) Ag / AgCl was used as the reference electrode, platinum wire as the counter electrode, Pt / NS-GAMs-coated glassy carbon electrode as the working electrode, and a mixed solution of 0.5 M H2SO4 and 1.0 M CH3OH as the electrolyte to characterize the electrochemical oxidation performance of Pt / NS-GAMs.
[0051] according to Figure 2 and Figure 4 The results show that the nitrogen-sulfur co-doped graphene aerogel microspheres platinum-based catalyst prepared by airflow-assisted electrostatic spraying method has a high sphericity, and the platinum nanoparticles loaded on the aerogel microspheres are uniformly dispersed and have a small particle size of only 2.58 nm.
[0052] Example 3
[0053] A nitrogen-sulfur co-doped graphene aerogel microsphere loaded with PtNPs as a catalyst comprises the following steps:
[0054] (1) Preparation of graphene oxide / L-cysteine dispersion
[0055] 0.09 g of L-cysteine was added to 100 mL of deionized water and magnetically stirred for 0.5 h until the L-cysteine was fully dissolved to obtain an L-cysteine aqueous solution.
[0056] (2) 0.6 g of graphene oxide was added to the above L-cysteine aqueous solution, and mechanical stirring was performed at a speed of 600 r / min for 8 h. Ultrasonic mechanical stirring was continued for 0.5 h in an ice-water bath to obtain a graphene oxide / L-cysteine dispersion.
[0057] (3) The graphene oxide / L-cysteine dispersion obtained above was loaded into a syringe and loaded onto an electrostatic spray device, with an applied voltage of 15 kV and an applied air pressure of 0.4 MPa. A receiving bath was located below the syringe. The receiving bath was a receiving tank filled with n-hexane, and the receiving tank was placed in a Dewar tank filled with ethyl acetate cooled with liquid nitrogen. After airflow-assisted electrostatic spraying, the ice microspheres and n-hexane were separated, and the ice microspheres were then freeze-dried at -50°C and 30 Pa for 48 hours to obtain graphene oxide / small molecule compounds containing sulfur and nitrogen groups composite aerogel microspheres.
[0058] (4) The graphene oxide / small molecule compound containing sulfur and nitrogen groups composite aerogel microspheres were prepared in a high-purity nitrogen atmosphere by heating to 800°C at a heating rate of 5°C / min and then keeping the temperature constant for 2h. The nitrogen-sulfur co-doped graphene aerogel microspheres were obtained by cooling to room temperature.
[0059] (5) 15 mg of nitrogen-sulfur co-doped graphene aerogel microspheres and 10 mg of chloroplatinic acid hexahydrate were added to 54 mL of ethylene glycol solution, slowly magnetically stirred for 12 h, and then loaded into a high-pressure reactor. The mixture was placed in an oven at 160 ° C and kept constant for 12 h. After the reactor was cooled to room temperature, it was filtered and then freeze-dried at -50 ° C and 30 Pa for 24 h to obtain nitrogen-sulfur co-doped graphene aerogel microsphere platinum-based catalyst.
[0060] (6) Ag / AgCl was used as the reference electrode, platinum wire as the counter electrode, Pt / NS-GAMs-coated glassy carbon electrode as the working electrode, and a mixed solution of 0.5 M H2SO4 and 1.0 M CH3OH as the electrolyte to characterize the electrochemical oxidation performance of Pt / NS-GAMs.
[0061] Comparative Example 1
[0062] A method for reducing graphene oxide to load PtNPs as a catalyst comprises the following steps:
[0063] (1) Graphene oxide is prepared in a high-purity nitrogen atmosphere by heating to 800°C at a heating rate of 5°C / min and then keeping the temperature constant for 2 h. Reduced graphene oxide (rGO) is then obtained by cooling to room temperature.
[0064] (2) 15 mg of rGO and 10 mg of chloroplatinic acid hexahydrate were added to 54 mL of ethylene glycol solution, slowly stirred with magnetic stirring for 12 h, then loaded into a high-pressure reactor and placed in an oven at 160 °C for 12 h. After the reactor was cooled to room temperature, it was filtered and then freeze-dried at -50 °C and 30 Pa for 24 h to obtain nitrogen-sulfur co-doped graphene aerogel microspheres platinum-based catalyst.
[0065] (3) Ag / AgCl was used as the reference electrode, platinum wire as the counter electrode, Pt / NS-GAMs-coated glassy carbon electrode as the working electrode, and a mixed solution of 0.5 M H2SO4 and 1.0 M CH3OH as the electrolyte to characterize the electrochemical oxidation performance of Pt / NS-GAMs.
[0066] according to Figure 5 The results show that the platinum nanoparticles loaded on the reduced graphene oxide sheets are obviously aggregated and have a larger particle size.
[0067] Comparative Example 2
[0068] A method for reducing graphene oxide aerogel microspheres loaded with PtNPs as a catalyst comprises the following steps:
[0069] (1) Preparation of graphene oxide dispersion
[0070] 0.6 g of graphene oxide was added to 100 mL of deionized water, and the mixture was magnetically stirred for 0.5 h, mechanically stirred at a speed of 600 r / min for 8 h, and then ultrasonically stirred in an ice-water bath for 0.5 h to obtain a graphene oxide dispersion.
[0071] (2) The graphene oxide dispersion obtained above was loaded into a syringe and loaded onto an electrostatic spray device, with an applied voltage of 15 kV and an applied air pressure of 0.3 MPa. A receiving bath was located below the syringe. The receiving bath was a receiving tank filled with n-hexane, and the receiving tank was placed in a Dewar tank filled with ethyl acetate cooled with liquid nitrogen. After airflow-assisted electrostatic spraying, the ice microspheres and n-hexane were separated, and then the ice microspheres were freeze-dried at -50°C and 30 Pa for 48 hours to produce graphene oxide aerogel microspheres.
[0072] (3) Graphene oxide aerogel microspheres are prepared in a high-purity nitrogen atmosphere by heating to 800°C at a heating rate of 5°C / min and then maintaining the temperature for 2 h. Reduced graphene oxide aerogel microspheres are obtained by cooling to room temperature.
[0073] (4) 15 mg of reduced graphene oxide aerogel microspheres and 10 mg of chloroplatinic acid hexahydrate were added to 54 mL of ethylene glycol solution, slowly magnetically stirred for 12 h, and then loaded into a high-pressure reactor. The mixture was placed in an oven at 160 ° C and kept constant for 12 h. After the reactor was cooled to room temperature, it was filtered and then freeze-dried at -50 ° C and 30 Pa for 24 h to obtain nitrogen-sulfur co-doped graphene aerogel microsphere platinum-based catalyst.
[0074] (5) Ag / AgCl was used as the reference electrode, platinum wire as the counter electrode, Pt / GAMs-coated glassy carbon electrode as the working electrode, and a mixed solution of 0.5 M H2SO4 and 1.0 M CH3OH as the electrolyte to characterize the electrochemical oxidation performance of Pt / GAMs.
[0075] according to Figure 6 The results show that compared with Pt / rGO and Pt / GAMs catalysts, Pt / NS-GAMs has higher methanol electrocatalytic oxidation activity, with a peak current density of up to 1459.74 mA·mg -1 Pt .
[0076] The above description is merely a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any person skilled in the art may make various equivalent modifications or substitutions within the technical scope of the present invention, which shall be covered by the scope of protection of the present invention. Therefore, the scope of protection of the present invention shall be subject to the scope of protection of the claims.
Claims
1. A method for preparing graphene nanoparticle composite aerogel microspheres, comprising the following steps: (1) Preparation of small molecule compound composite aqueous dispersion: 0.01 to 3.6 g of a small molecule compound containing sulfur or nitrogen groups is added to 100 mL of deionized water and magnetically stirred for 0.5 to 1 hour to obtain a first intermediate liquid; 0.4 to 1.2 g of graphene oxide is added to the first intermediate liquid and mechanically stirred to obtain a second intermediate liquid; and finally the second intermediate liquid is subjected to ultrasonic mechanical stirring to obtain a small molecule compound composite aqueous dispersion; (2) Preparation of graphene nanoparticle composite aerogel microspheres: The composite aqueous dispersion of small molecule compounds is loaded into a syringe, and voltage and air pressure are applied to the electrostatic spray equipment. After airflow-assisted electrostatic spraying, ice microspheres are separated. The ice microspheres are then freeze-dried and high-temperature annealed in sequence, and cooled to room temperature to obtain graphene nanoparticle composite aerogel microspheres.
2. The preparation method according to claim 1, wherein: The small molecule compound containing sulfur and nitrogen groups in step (1) is selected from: One or more of L-cysteine, L-cystine, L-methionine, 3-mercaptopropionic acid, 2,5-diamino-1,3,4-thiadiazole, 6-thioguanine, 2-mercaptopyrimidine, (4-acetylphenyl)thiourea, and thiourea.
3. The preparation method according to claim 1, wherein: The mechanical stirring conditions in step (1) are: 500-800 r / min rotation speed, stirring for 8-10 hours; The ultrasonic mechanical stirring condition is: ultrasonic mechanical stirring in a 40-KHz ultrasonic cleaning machine for 0.5 to 2 hours.
4. The preparation method according to claim 1, wherein: The graphene oxide in step (1) has 1 to 2 layers, a sheet diameter of 0.2 to 10 μm, a sheet thickness of 1 to 2 μm, a carbon content of <48%, and an oxygen content of >47%.
5. The preparation method according to claim 1, wherein: In step (2), the applied voltage is 12 to 18 kV, and the applied gas pressure is 0.2 to 0.6 MPa.
6. The preparation method according to claim 1, wherein: The freeze-drying conditions in step (2) are: Freeze-dry at -50°C and 30 Pa for 48 hours.
7. The preparation method according to claim 1, wherein: The high temperature annealing treatment conditions in step (2) are: The process is carried out in a high-purity nitrogen or argon atmosphere, with the temperature being increased to 600-1000°C at a heating rate of 2-5°C / min and then maintained at a constant temperature for 1-4 hours.
8. A graphene nanoparticle composite aerogel microsphere prepared according to the preparation method according to any one of claims 1 to 7, wherein: The graphene aerogel microspheres have a particle size of 10 to 80 μm and a specific surface area of 150 to 450 g·m 2 .
9. Use of the graphene nanoparticle composite aerogel microspheres according to claim 8 in preparing nitrogen-sulfur co-doped graphene aerogel microsphere catalysts, comprising: Graphene aerogel microspheres and platinum precursors were added to an ethylene glycol solution, magnetically stirred for 12 hours, then loaded into a high-pressure reactor and placed in an oven at a constant temperature of 140-180°C for 12 hours. After the reactor was cooled to room temperature, it was filtered and then freeze-dried at -50°C and 30 Pa for 16-24 hours to obtain a nitrogen-sulfur co-doped graphene aerogel microsphere catalyst.