Preparation method of silver and nitrogen-doped cellulose-based carbon aerogel membrane for fuel cells

Abstract

The present invention discloses a method for preparing a silver- and nitrogen-doped cellulose-based carbon aerogel membrane for fuel cells. The method comprises preparing a mixed solution of sodium hydroxide and urea, placing cotton linters in the mixed solution, stirring at a low speed to swell the mixture, freezing the mixture, and then stirring at a high speed to obtain a cellulose solution. Nanosilver-loaded nanocellulose and the cellulose solution are then rotatably mixed, and the mixed cellulose solution is transferred to a film-making mold. After rapid freezing in liquid nitrogen, the cellulose aerogel membrane is dried using a freeze dryer to obtain a cellulose aerogel membrane. The cellulose aerogel membrane is placed in an acid solution until neutralized, and freeze-dried again using the above conditions to obtain a cellulose aerogel membrane. Finally, the cellulose aerogel membrane is placed in a tubular furnace and carbonized under a nitrogen atmosphere, followed by natural cooling to obtain a finished product. The silver- and nitrogen-doped cellulose-based carbon aerogel membrane prepared by the present invention can form uniformly distributed pores and has the advantages of a large specific surface area and low horizontal resistivity.

Description

Technical Field

[0001] The present invention relates to the field of fuel cell material preparation, and in particular to a method for preparing a silver- and nitrogen-doped cellulose-based carbon aerogel membrane for fuel cells. Background Art

[0002] Hydrogen fuel cells use hydrogen as fuel and generate electricity through hydrogen oxidation. They offer advantages such as high energy conversion efficiency, zero pollution, and stable and reliable operation. Among various hydrogen fuel cells, the proton exchange membrane fuel cell (PEMFC) is considered to have the greatest potential for near-term industrialization and application, with broad application prospects in areas such as civilian vehicles, spacecraft, and unmanned underwater vehicles.

[0003] PEMFCs continuously convert the energy present in fuel hydrogen into electricity through electrochemical reactions with an oxidant (air), achieving an energy conversion rate exceeding 50%. The membrane electrode (MEA) is the core site of the electrochemical reactions in PEMFCs and is primarily composed of a gas diffusion layer (GDL), a catalyst layer, and a proton exchange membrane (PEM). Currently, the GDL primarily utilizes carbon paper as its substrate. Research has shown that carbon paper plays five important roles in PEMFCs: gas transport and distribution, electron conduction, improved water management, support for the catalyst layer, and heat dissipation. Therefore, it must possess excellent electrical and thermal conductivity, good strength and surface flatness, high permeability, uniform pore size distribution, and high stability. However, the carbon paper preparation process faces bottlenecks such as difficulty dispersing carbon fibers in water, difficulty controlling the uniformity of the base paper, poor interfacial bonding between the resin and the base paper, high graphitization temperature, and the interplay between electrical conductivity, porosity, and strength. Therefore, the development of tunable, high-performance GDLs is a key research priority in this field. Summary of the Invention

[0004] The present invention aims to provide a method for preparing a silver- and nitrogen-doped cellulose-based carbon aerogel membrane for fuel cells. The silver- and nitrogen-doped cellulose-based carbon aerogel membrane prepared by the present invention can form uniformly distributed pores, and has the advantages of a large specific surface area and low horizontal resistivity.

[0005] To solve the above technical problems, the present invention provides a technical solution as follows: a method for preparing a silver and nitrogen-doped cellulose-based carbon aerogel membrane for a fuel cell, comprising the following steps:

[0006] Step 1, preparing a mixed solution of sodium hydroxide and urea, wherein the mass concentrations of sodium hydroxide and urea in the mixed solution are 5-8% and 3-8%, respectively;

[0007] Step 2: taking 100 parts by volume of the mixed solution, adding 0.1-1.2 parts by mass of cotton linters to the mixed solution, stirring at a low speed to swell for 13-18 minutes, then freezing at -15--20°C for 20-28 hours, and then stirring at a high speed to obtain a cellulose solution;

[0008] Step 3, taking 0.2-4% of the mass of cellulose and loading nanocellulose with nanosilver, mixing with the cellulose solution in step 2, and rotating and mixing for 0.5-2h;

[0009] Step 4: Transfer the mixed cellulose solution to a film-making mold, quickly freeze it in liquid nitrogen, and then use a freeze dryer to dry it at a temperature of -45--80°C and a vacuum degree of 0.05-0.08 MPa to obtain a cellulose aerogel film; place the cellulose aerogel film in an acid solution until it becomes neutral, and then freeze-dry it again under the above conditions to obtain a cellulose aerogel film;

[0010] Step 5: Place the cellulose aerogel membrane in a tubular furnace and perform carbonization treatment under a nitrogen atmosphere, and then cool it naturally to obtain a finished product.

[0011] In the above-mentioned method for preparing silver- and nitrogen-doped cellulose-based carbon aerogel membrane for fuel cells, in step 1, the mass concentration of sodium hydroxide in the mixed solution is 6%, and the mass concentration of urea is 4%.

[0012] In the aforementioned method for preparing silver and nitrogen-doped cellulose-based carbon aerogel membrane for fuel cells, in step 2, the mass portion of cotton linters is 1 part, the low-speed stirring swelling time is 15 minutes, the freezing temperature is -18°C, and the freezing time is 24 hours.

[0013] In the aforementioned method for preparing silver- and nitrogen-doped cellulose-based carbon aerogel membrane for fuel cells, in step 3, silver-loaded nanocellulose is mixed with the cellulose solution at a rate of 1% by mass of the cellulose, and the rotation mixing time is 1 hour.

[0014] In the aforementioned method for preparing silver- and nitrogen-doped cellulose-based carbon aerogel membranes for fuel cells, in step 3, the preparation of the nanosilver-loaded nanocellulose is to add a surface-positive nanosilver solution having a mass concentration of 1% to a nanocellulose solution prepared by the Tempo oxidation method having a mass concentration of 1% at a volume ratio of 1-4:1, and thoroughly mix them to load the nanosilver particles on the surface of the nanocellulose.

[0015] In the aforementioned method for preparing silver- and nitrogen-doped cellulose-based carbon aerogel membrane for fuel cells, the volume ratio of the surface positively charged nanosilver solution to the nanocellulose solution prepared by the Tempo oxidation method is 3:1.

[0016] In the aforementioned method for preparing silver- and nitrogen-doped cellulose-based carbon aerogel membrane for fuel cells, in step 6, the freeze-drying temperature of the freeze-dryer is -50°C and the vacuum degree is 0.06 MPa.

[0017] The carbonization treatment comprises heating the temperature to 450-550°C at a heating rate of 3-8°C / min and keeping the temperature for 1-3 hours, then heating the temperature to 950-1100°C at a heating rate of 1-3°C / min and keeping the temperature for 1-3 hours, then cooling the temperature to 150-250°C at a rate of 3-8°C / min, and then cooling naturally.

[0018] The carbonization treatment of the aforementioned method for preparing silver- and nitrogen-doped cellulose-based carbon aerogel membrane for fuel cells is carried out by heating the temperature to 500°C at a heating rate of 5°C / min and keeping it warm for 2 hours, then heating the temperature to 1000°C at a heating rate of 2°C / min and keeping it warm for 2 hours, then cooling the temperature to 200°C at a rate of 2°C / min, and then cooling naturally.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] 1. The present invention adopts an alkaline urea system to dissolve cellulose, and in situ dopes the nitrogen element of urea in the dissolving system into the carbon aerogel, which can improve the conductive properties of the carbon aerogel film.

[0021] 2. The present invention can achieve the regulation of aerogel pore structure by adding cellulose concentration and nanocellulose, which is beneficial to the subsequent regulation of carbon aerogel resistivity and permeability and improves the performance of the gas diffusion layer.

[0022] 3. The addition of silver nanoparticles in the present invention, combined with nanocellulose, is beneficial to improving the distribution uniformity of silver nanoparticles at the nano and molecular levels, thereby enhancing the conductive properties of cellulose-based carbon aerogels. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 is a microscopic image of the silver and nitrogen-doped cellulose-based carbon aerogel film in Example 1;

[0024] Figure 2 is a microscopic image of the silver and nitrogen-doped cellulose-based carbon aerogel film in Example 2;

[0025] Figure 3 is a microscopic image of the silver and nitrogen-doped cellulose-based carbon aerogel film in Example 3;

[0026] Figure 4 is a microscopic image of the silver and nitrogen doped cellulose-based carbon aerogel film in Example 4. DETAILED DESCRIPTION

[0027] The present invention will be further described below with reference to the accompanying drawings and examples, but they are not intended to limit the present invention.

[0028] Example 1: A method for preparing a silver and nitrogen-doped cellulose-based carbon aerogel membrane for a fuel cell, comprising the following steps:

[0029] Step 1, cellulose dissolution: prepare 100 ml of a mixed solution of sodium hydroxide and urea, controlling the concentrations of sodium hydroxide and urea to be 6% and 4% respectively;

[0030] Step 2: Weigh 1 g of cotton linters and place them in the solution. Swell the mixture at low speed for 15 minutes using a blender, freeze the mixture at -16°C for 24 hours, and then stir the mixture at high speed to obtain a cellulose solution.

[0031] Step 3, preparation of cellulose aerogel: taking 1% of the mass of cellulose nanosilver loaded nanocellulose and mixing it with the cellulose solution in step 2, and rotating and mixing for 0.5-2h;

[0032] Step 4: Transfer the mixed cellulose solution to a film-making mold, quickly freeze it in liquid nitrogen, and then use a freeze dryer to dry it at a temperature of -50°C and a vacuum degree of 0.06 MPa to obtain a cellulose aerogel film; place the cellulose aerogel film in an acid solution until it becomes neutral, and then freeze-dry it again using the above conditions to obtain a cellulose aerogel film.

[0033] Step 5, carbonization: Place the cellulose aerogel membrane in a tubular furnace, and in a nitrogen atmosphere, heat it to 500°C at a heating rate of 5°C / min and keep it warm for 2 hours, then heat it to 1000°C at a heating rate of 2°C / min and keep it warm for 2 hours, then cool it to 200°C at a rate of 5°C / min, and then cool it naturally to obtain a cellulose-based carbon aerogel membrane.

[0034] Example 2: A method for preparing a silver- and nitrogen-doped cellulose-based carbon aerogel membrane for a fuel cell, comprising the following steps:

[0035] Step 1, cellulose dissolution: prepare 100 ml of a mixed solution of sodium hydroxide and urea, controlling the concentrations of sodium hydroxide and urea to be 6% and 4% respectively;

[0036] Step 2, weighing 1 g of cotton linters and placing them in the solution, swelling them with a blender at low speed for 15 minutes, freezing them at -16°C for 24 hours, and then stirring them at high speed to obtain a cellulose solution;

[0037] Step 3: adding 1% surface positively charged nanosilver solution by weight to 1% nanocellulose solution prepared by Tempo oxidation method at a volume ratio of 1:1, and mixing thoroughly to load the nanosilver particles on the surface of the nanocellulose; then mixing the nanosilver-loaded nanocellulose with the cellulose solution at a volume ratio of 1% by weight of the cellulose, and rotating the mixture for 1 hour;

[0038] Step 4: The mixed cellulose solution is transferred to a film-making mold, and after rapid freezing in liquid nitrogen, it is dried in a freeze dryer at a temperature of -50°C and a vacuum degree of 0.06 MPa to obtain a cellulose aerogel film; the cellulose aerogel film is placed in an acid solution until it becomes neutral, and then freeze-dried again using the above conditions to obtain a cellulose aerogel film;

[0039] Step 5, carbonization: Place the cellulose aerogel membrane in a tubular furnace, and in a nitrogen atmosphere, heat it to 500°C at a heating rate of 5°C / min and keep it warm for 2 hours, then heat it to 1000°C at a heating rate of 2°C / min and keep it warm for 2 hours, then cool it to 200°C at a rate of 5°C / min, and then cool it naturally to obtain a cellulose-based carbon aerogel membrane.

[0040] Example 3: A method for preparing a silver and nitrogen-doped cellulose-based carbon aerogel membrane for a fuel cell, comprising the following steps:

[0041] Step 1, cellulose dissolution: prepare 100 ml of a mixed solution of sodium hydroxide and urea, controlling the concentrations of sodium hydroxide and urea to be 6% and 4% respectively;

[0042] Step 2, weighing 1 g of cotton linters and placing them in the solution, swelling them with a blender at low speed for 15 minutes, freezing them at -16°C for 24 hours, and then stirring them at high speed to obtain a cellulose solution;

[0043] Step 3: adding 1% surface positively charged nanosilver solution by weight to 1% nanocellulose solution prepared by Tempo oxidation at a volume ratio of 2:1, and mixing thoroughly to load the nanosilver particles onto the surface of the nanocellulose; then mixing the nanosilver-loaded nanocellulose with the cellulose solution at a volume ratio of 1% by weight of the cellulose, and rotating the mixture for 1 hour;

[0044] Step 4: The mixed cellulose solution is transferred to a film-forming mold, rapidly frozen in liquid nitrogen, and then dried in a freeze dryer at -50°C and a vacuum of 0.06 MPa to obtain a cellulose aerogel film. The cellulose aerogel film is then placed in an acid solution until neutralized and freeze-dried again using the above conditions to obtain a cellulose aerogel film.

[0045] Step 5, carbonization: Place the cellulose aerogel membrane in a tubular furnace, and in a nitrogen atmosphere, heat it to 500°C at a heating rate of 5°C / min and keep it warm for 2 hours, then heat it to 1000°C at a heating rate of 2°C / min and keep it warm for 2 hours, then cool it to 200°C at a rate of 5°C / min, and then cool it naturally to obtain a cellulose-based carbon aerogel membrane.

[0046] Example 4: A method for preparing a silver and nitrogen-doped cellulose-based carbon aerogel membrane for a fuel cell, comprising the following steps:

[0047] Step 1, cellulose dissolution: prepare 100 ml of a mixed solution of sodium hydroxide and urea, controlling the concentrations of sodium hydroxide and urea to be 6% and 4% respectively;

[0048] Step 2, weighing 1 g of cotton linters and placing them in the solution, swelling them with a blender at low speed for 15 minutes, freezing them at -16°C for 24 hours, and then stirring them at high speed to obtain a cellulose solution;

[0049] Step 3: Add 1% surface positively charged nanosilver solution by mass to 1% nanocellulose solution prepared by Tempo oxidation method at a volume ratio of 3:1, mix thoroughly and evenly, so that the nanosilver particles are loaded on the surface of the nanocellulose; then mix the nanosilver-loaded nanocellulose with the cellulose solution at a volume ratio of 1% by mass of cellulose, and rotate and mix for 1 hour.

[0050] Step 4: Transfer the mixed cellulose solution to a film-making mold, quickly freeze it in liquid nitrogen, and then use a freeze dryer to dry it at a temperature of -50°C and a vacuum degree of 0.06 MPa to obtain a cellulose aerogel film; place the cellulose aerogel film in an acid solution until it becomes neutral, and then freeze-dry it again using the above conditions to obtain a cellulose aerogel film.

[0051] Step 5, carbonization: Place the cellulose aerogel membrane in a tubular furnace, and in a nitrogen atmosphere, heat it to 500°C at a heating rate of 5°C / min and keep it warm for 2 hours, then heat it to 1000°C at a heating rate of 2°C / min and keep it warm for 2 hours, then cool it to 200°C at a rate of 5°C / min, and then cool it naturally to obtain a cellulose-based carbon aerogel membrane.

[0052] Example 5: A method for preparing a silver and nitrogen-doped cellulose-based carbon aerogel membrane for a fuel cell, comprising the following steps:

[0053] Step 1, cellulose dissolution: prepare 100 ml of a mixed solution of sodium hydroxide and urea, controlling the concentrations of sodium hydroxide and urea to be 7% and 5% respectively;

[0054] Step 2, weighing 1 g of cotton linters and placing them in the solution, swelling them with a blender at low speed for 18 minutes, freezing them at -20°C for 25 hours, and then stirring them at high speed to obtain a cellulose solution;

[0055] Step 3: Add 1% surface positively charged nanosilver solution by mass to 1% nanocellulose solution prepared by Tempo oxidation method at a volume ratio of 4:1, mix thoroughly to load the nanosilver particles on the surface of the nanocellulose; then mix the nanosilver-loaded nanocellulose with the cellulose solution at a volume ratio of 1% by mass of cellulose and rotate and mix for 1.5 hours.

[0056] Step 4: Transfer the mixed cellulose solution to a film-making mold, quickly freeze it in liquid nitrogen, and then use a freeze dryer to dry it at a temperature of -70°C and a vacuum degree of 0.07 MPa to obtain a cellulose aerogel film; place the cellulose aerogel film in an acid solution until it becomes neutral, and then freeze-dry it again using the above conditions to obtain a cellulose aerogel film.

[0057] Step 5, carbonization: Place the cellulose aerogel membrane in a tubular furnace, and in a nitrogen atmosphere, heat it to 480°C at a heating rate of 6°C / min and keep it warm for 2.5 hours, then heat it to 1050°C at a heating rate of 3°C / min and keep it warm for 1.5 hours, then cool it to 180°C at a rate of 8°C / min, and then cool it naturally to obtain a cellulose-based carbon aerogel membrane.

[0058] Example 6: A method for preparing a silver and nitrogen-doped cellulose-based carbon aerogel membrane for a fuel cell, comprising the following steps:

[0059] Step 1, cellulose dissolution: prepare 100 ml of a mixed solution of sodium hydroxide and urea, controlling the concentrations of sodium hydroxide and urea to be 5% and 7% respectively;

[0060] Step 2, weighing 1 g of cotton linters and placing them in the solution, swelling them with a blender at low speed for 13 minutes, freezing them at -15°C for 20 hours, and then stirring them at high speed to obtain a cellulose solution;

[0061] Step 3: Add 1% surface positively charged nanosilver solution by mass to 1% nanocellulose solution prepared by Tempo oxidation method in a volume ratio of 2:1, mix thoroughly to load the nanosilver particles on the surface of the nanocellulose; then mix the nanosilver-loaded nanocellulose with the cellulose solution at a volume ratio of 4% by mass of cellulose and rotate and mix for 2 hours.

[0062] Step 4: Transfer the mixed cellulose solution to a film-making mold, quickly freeze it in liquid nitrogen, and then use a freeze dryer to dry it at a temperature of -60°C and a vacuum degree of 0.05 MPa to obtain a cellulose aerogel film; place the cellulose aerogel film in an acid solution until it becomes neutral, and then freeze-dry it again using the above conditions to obtain a cellulose aerogel film.

[0063] Step 5, carbonization: Place the cellulose aerogel membrane in a tubular furnace, and in a nitrogen atmosphere, heat it to 520°C at a heating rate of 4°C / min and keep it warm for 1 hour, then heat it to 950°C at a heating rate of 1°C / min and keep it warm for 3 hours, then cool it to 180°C at a rate of 8°C / min, and then cool it naturally to obtain a cellulose-based carbon aerogel membrane.

[0064] Comparative Example 1: The preparation of the aerogel film is as follows:

[0065] 1. Cellulose dissolution: Prepare 100 ml of sodium hydroxide solution with a sodium hydroxide concentration of 6%. Weigh 1 g of cotton linter and place it in the solution. Swell the mixture at low speed for 15 minutes using a blender, freeze it at -16°C for 24 hours, and then stir it at high speed to obtain a cellulose solution.

[0066] 2. Preparation of Cellulose Aerogel: The cellulose solution was transferred to a film-forming mold, rapidly frozen in liquid nitrogen, and then dried in a freeze dryer at -50°C and a vacuum of 0.06 MPa to produce a cellulose aerogel film. The cellulose aerogel film was then placed in an acid solution until neutralized and freeze-dried again using the above conditions to produce a cellulose aerogel film.

[0067] 3. Carbonization: Place the cellulose aerogel membrane in a tubular furnace, and in a nitrogen atmosphere, heat it to 500°C at a heating rate of 5°C / min and keep it warm for 2 hours, then heat it to 1000°C at a heating rate of 2°C / min and keep it warm for 2 hours, then cool it to 200°C at a rate of 5°C / min, and then cool it naturally to obtain a cellulose-based carbon aerogel membrane.

[0068] Comparative Example 2: The preparation of the aerogel film is as follows:

[0069] 1. Cellulose dissolution: Prepare 100 ml of sodium hydroxide / urea solution with the concentrations of sodium hydroxide and urea controlled at 6% and 4%, respectively. Weigh 1 g of cotton linter and place it in the solution. Swell the solution at low speed in a blender for 15 minutes, freeze it at -16°C for 24 hours, and then stir it at high speed to obtain a cellulose solution.

[0070] 2. Preparation of Cellulose Aerogel: The cellulose solution was transferred to a film-forming mold, rapidly frozen in liquid nitrogen, and then dried in a freeze dryer at -50°C and a vacuum of 0.06 MPa to produce a cellulose aerogel film. The cellulose aerogel film was then placed in an acid solution until neutralized and freeze-dried again using the above conditions to produce a cellulose aerogel film.

[0071] 3. Carbonization: Place the cellulose aerogel membrane in a tubular furnace, and in a nitrogen atmosphere, heat it to 500°C at a heating rate of 5°C / min and keep it warm for 2 hours, then heat it to 1000°C at a heating rate of 2°C / min and keep it warm for 2 hours, then cool it to 200°C at a rate of 5°C / min, and then cool it naturally to obtain a cellulose-based carbon aerogel membrane.

[0072] Through electron microscopic observation of the silver and nitrogen cellulose-doped carbon aerogel films prepared in Examples 1 to 4, it was found that Figures 1 to 4 It can be seen that the pore structure of the silver and nitrogen-doped cellulose-based carbon aerogel membrane prepared by the present invention is very uniform, and the aerogel pore structure is regulated by the cellulose concentration and the addition of nanocellulose.

[0073] Furthermore, the specific surface area and horizontal resistivity of the silver and nitrogen cellulose-doped carbon aerogel films prepared in Examples 1-6 and the aerogel films prepared in Comparative Examples 1-2 were measured, and the results are shown in Table 1:

[0074]

[0075]

[0076] Table 1

[0077] From the results in Table 1, it can be seen that the test results of Example 4 using the preferred process parameters show the largest specific surface area and low resistivity, which is consistent with the results in Example 4. Figure 4 The results of the micrographs are consistent with those of the other examples, and the other examples also have good specific surface areas and horizontal resistivities. However, since comparative examples 1 and 2 are not doped with nanosilver particles, although their specific surface areas have good performance, their electrical conductivity is poor. It can be seen that the present invention uses an alkaline urea system to dissolve cellulose and in-situ dopes the nitrogen element of the urea in the dissolution system into the carbon aerogel, which can improve the electrical conductivity of the carbon aerogel membrane. Furthermore, the present invention can achieve the regulation of the aerogel pore structure by adjusting the cellulose concentration and the addition of nanocellulose, which is beneficial for the subsequent regulation of the resistivity and permeability of the carbon aerogel and improving the performance of the gas diffusion layer. Furthermore, the addition of silver nanoparticles in the present invention, combined with nanocellulose, is beneficial for improving the distribution uniformity of silver nanoparticles at the nano and molecular levels, thereby improving the electrical conductivity of the cellulose-based carbon aerogel.

[0078] In summary, the silver and nitrogen-doped cellulose-based carbon aerogel membrane prepared by the present invention can form uniformly distributed pores, and has the advantages of large specific surface area and low horizontal resistivity, and has good application prospects in proton exchange membrane fuel cells.

Claims

1. A method for preparing silver- and nitrogen-doped cellulose-based carbon aerogel membranes for fuel cells, characterized in that: The steps include: Step 1, preparing a mixed solution of sodium hydroxide and urea, wherein the mass concentrations of sodium hydroxide and urea in the mixed solution are 5-8% and 3-8%, respectively; Step 2: taking 100 parts by volume of the mixed solution, adding 0.1-1.2 parts by mass of cotton linters to the mixed solution, stirring at a low speed to swell for 13-18 minutes, then freezing at -15--20°C for 20-28 hours, and then stirring at a high speed to obtain a cellulose solution; Step 3, taking 0.2-4% of the mass of cellulose and loading nanocellulose with nanosilver and mixing it with the cellulose solution in step 2, and rotating and mixing for 0.5-2h; Step 4: Transfer the mixed cellulose solution to a film-making mold, quickly freeze it in liquid nitrogen, and then use a freeze dryer to dry it at a temperature of -45--80°C and a vacuum degree of 0.05-0.08 MPa to obtain a cellulose aerogel film; place the cellulose aerogel film in an acid solution until it becomes neutral, and then freeze-dry it again under the above conditions to obtain a cellulose aerogel film; Step 5: Place the cellulose aerogel membrane in a tubular furnace and perform carbonization treatment under a nitrogen atmosphere, and then cool it naturally to obtain a finished product.

2. The method for preparing silver- and nitrogen-doped cellulose-based carbon aerogel membrane for fuel cells according to claim 1, characterized in that: In step 1, in the mixed solution, the mass concentration of sodium hydroxide is 6%, and the mass concentration of urea is 4%.

3. The method for preparing silver- and nitrogen-doped cellulose-based carbon aerogel membrane for fuel cells according to claim 1, characterized in that: In step 2, the mass portion of cotton linters is 1 part, the low-speed stirring swelling time is 15 minutes, the freezing temperature is -18°C, and the freezing time is 24 hours.

4. The method for preparing silver- and nitrogen-doped cellulose-based carbon aerogel membrane for fuel cells according to claim 1, characterized in that: In step 3, the silver-loaded nanocellulose was mixed with the cellulose solution at a rate of 1% of the mass of the cellulose, and the mixing time was 1 h.

5. The method for preparing silver- and nitrogen-doped cellulose-based carbon aerogel membrane for fuel cells according to claim 1, characterized in that: In step 3, the preparation of the nanosilver-loaded nanocellulose is to add a surface positively charged nanosilver solution with a mass concentration of 1% to a nanocellulose solution prepared by Tempo oxidation method with a mass concentration of 1% at a volume ratio of 1-4:1, and mix them thoroughly to load the nanosilver particles on the surface of the nanocellulose.

6. The method for preparing silver- and nitrogen-doped cellulose-based carbon aerogel membrane for fuel cells according to claim 5, characterized in that: The volume ratio of the surface positively charged nanosilver solution to the nanocellulose solution prepared by the Tempo oxidation method is 3:

1.

7. The method for preparing silver- and nitrogen-doped cellulose-based carbon aerogel membrane for fuel cells according to claim 1, characterized in that: In step 6, the freeze drying temperature of the freeze dryer is -50°C and the vacuum degree is 0.06 MPa.

8. The method for preparing silver- and nitrogen-doped cellulose-based carbon aerogel membrane for fuel cells according to claim 1, characterized in that: The carbonization treatment is to heat the temperature to 450-550°C at a heating rate of 3-8°C / min and keep it warm for 1-3h, then heat the temperature to 950-1100°C at a heating rate of 1-3°C / min and keep it warm for 1-3h, then cool the temperature to 150-250°C at a heating rate of 3-8°C / min, and then cool naturally.

9. The method for preparing silver- and nitrogen-doped cellulose-based carbon aerogel membrane for fuel cells according to claim 1, characterized in that: The carbonization treatment is to heat the sample to 500°C at a heating rate of 5°C / min and keep the temperature for 2 hours, then heat the sample to 1000°C at a heating rate of 2°C / min and keep the temperature for 2 hours, then cool the sample to 200°C at a heating rate of 2°C / min, and then cool the sample naturally.

Images