A chitosan fiber-reduced graphene oxide composite paper and its preparation method and application

Abstract

The present invention discloses a chitosan fiber-reduced graphene oxide composite paper and its preparation method and application. The composition of the chitosan fiber-reduced graphene oxide composite paper of the present invention includes a chitosan fiber-reduced graphene oxide substrate and a loaded hydrophobic material. The composition of the chitosan fiber-reduced graphene oxide substrate includes chitosan fibers and reduced graphene oxide self-assembled on the surface of the chitosan fibers. The chitosan fiber-reduced graphene oxide composite paper of the present invention has the advantages of good electrical conductivity, good mechanical properties, simple preparation process, low cost, etc., is convenient for large-scale preparation, and can be made into a gas diffusion layer as a substrate through a simple and low-cost preparation process, and is suitable for use in fuel cells.

Description

Technical Field

[0001] The present invention relates to the technical field of fuel cells, and in particular to a chitosan fiber-reduced graphene oxide composite paper and a preparation method and application thereof. Background Art

[0002] A fuel cell is a chemical device that converts the chemical energy of a fuel directly into electrical energy. It is the fourth generation of power generation technology, following hydropower, thermal power generation, and nuclear power generation. Fuel cells are a clean energy generation technology that, compared to lithium batteries, offer advantages such as environmental friendliness, high theoretical power generation efficiency (up to 85%-90%), and a wide variety of fuels. They also boast higher power density for a given volume, longer operating life, and are largely unaffected by ambient temperature. Fuel cells have significant advantages in applications such as hydrogen-powered drones, hydrogen-powered forklifts, and hydrogen-powered vehicles, and have garnered significant attention in recent years.

[0003] The gas diffusion layer is one of the key components of a fuel cell. It plays the role of supporting the catalyst layer, collecting current, conducting gas, and discharging the reaction product water in the fuel cell. At present, the main raw material of the gas diffusion layer is carbon fiber. The carbon fiber is formed into a carbon paper substrate by wet papermaking, and then subjected to resin hot pressing sintering and graphitization treatment, and then subjected to hydrophobic and microporous layer slurry spraying and sintering treatment to finally obtain the fuel cell gas diffusion layer. The performance of the carbon paper substrate will determine the preparation of the subsequent gas diffusion layer and its performance in the fuel cell to a certain extent. However, the existing carbon paper substrate has problems such as the need to improve its electrical conductivity and general mechanical properties. In addition, when used as a substrate to prepare the gas diffusion layer, there are also problems such as complex process (resin impregnation, sintering, and graphitization are required) and high cost, which makes it difficult to fully meet the requirements of practical applications.

[0004] Therefore, it is of great significance to develop a carbon paper substrate with good electrical conductivity and mechanical properties that can be made into a gas diffusion layer through a simple and low-cost preparation process. Summary of the Invention

[0005] The purpose of the present invention is to provide a chitosan fiber-reduced graphene oxide composite paper and a preparation method and application thereof.

[0006] The technical solution adopted by the present invention is:

[0007] A chitosan fiber-reduced graphene oxide composite paper comprises a chitosan fiber-reduced graphene oxide substrate and a loaded hydrophobic material; the chitosan fiber-reduced graphene oxide substrate comprises chitosan fibers and reduced graphene oxide self-assembled on the surface of the chitosan fibers.

[0008] Preferably, the mass ratio of the chitosan fiber-reduced graphene oxide substrate to the hydrophobic material is 1:0.05-0.25.

[0009] Preferably, the hydrophobic material is at least one of polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), and fluorinated ethylene propylene copolymer (FEP).

[0010] Preferably, the mass ratio of the chitosan fiber to the reduced graphene oxide is 1:0.25 - 4.

[0011] Preferably, the length of the chitosan fiber is 3 mm - 6 mm.

[0012] A method for preparing the chitosan fiber-reduced graphene oxide composite paper as described above includes the following steps:

[0013] 1) Dispersing chitosan fiber, graphene oxide, wet strength agent, and retention aid in water to obtain chitosan fiber-graphene oxide composite pulp;

[0014] 2) Making paper from the chitosan fiber-graphene oxide composite pulp to obtain chitosan fiber-graphene oxide composite paper;

[0015] 3) Immersing the chitosan fiber-graphene oxide composite paper in a reducing agent solution for reduction, and then immersing it in a hydrophobic material dispersion for hydrophobic treatment to obtain the chitosan fiber-reduced graphene oxide composite paper.

[0016] Preferably, the wet strength agent in step 1) is at least one of polyamide epichlorohydrin resin (PAE), polyvinyl alcohol (PVA), and sodium carboxymethyl cellulose (CMC-Na).

[0017] Preferably, the dosage of the wet strength agent in step 1) is 0.5% - 1% of the mass of the chitosan fiber.

[0018] Preferably, the retention aid in step 1) is at least one of polyethyleneimine (PEI), cationic polyacrylamide (CPAM), and polyoxyethylene (PEO).

[0019] Preferably, the dosage of the retention aid in step 1) is 1% - 4% of the mass of the graphene oxide.

[0020] Preferably, the specific operation of making paper in step 2) is: first bubbling the chitosan fiber-graphene oxide composite pulp for 10 s - 20 s, then making paper, then pressing for 1 min - 5 min under the condition of a pressure of 0.5 MPa - 1.0 MPa, and then drying for 8 min - 15 min under the condition of a temperature of 80°C - 90°C.

[0021] Preferably, the reducing agent solution in step 3) is at least one of ascorbic acid solution, hydrazine hydrate solution, and hydroiodic acid solution.

[0022] Preferably, the amount of the reducing agent in the reducing agent solution in step 3) is 100% to 200% of the mass of the graphene oxide.

[0023] Preferably, the reduction in step 3) is carried out at a temperature of 80° C. to 100° C., and the reduction time is 2 h to 4 h.

[0024] A gas diffusion layer comprises the chitosan fiber-reduced graphene oxide composite paper.

[0025] Preferably, the gas diffusion layer comprises a carrier chitosan fiber-reduced graphene oxide composite paper, and also includes supported carbon black and a hydrophobic material.

[0026] Preferably, the mass ratio of the chitosan fiber-reduced graphene oxide composite paper to the hydrophobic material is 1:0.05-0.25.

[0027] Preferably, the mass ratio of the carbon black to the hydrophobic material is 1:0.05-0.25.

[0028] Preferably, the carbon black is at least one of acetylene black, biomass carbon black, and rubber carbon black.

[0029] Preferably, the hydrophobic material is at least one of polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), and perfluoroethylene propylene copolymer (FEP).

[0030] A method for preparing the gas diffusion layer as described above comprises the following steps:

[0031] Carbon black and hydrophobic material are dispersed in a solvent to prepare a mixed slurry, which is then sprayed on the surface of the chitosan fiber-reduced graphene oxide composite paper and then maintained at a temperature of 300°C to 400°C for 2h to 4h to obtain a gas diffusion layer.

[0032] Preferably, the spraying amount of the mixed slurry on the chitosan fiber-reduced graphene oxide composite paper is 3 mg / cm 2 ~5mg / cm 2 .

[0033] A fuel cell comprises the chitosan fiber-reduced graphene oxide composite paper.

[0034] The beneficial effects of the present invention are as follows: the chitosan fiber-reduced graphene oxide composite paper of the present invention has the advantages of good electrical conductivity, good mechanical properties, simple preparation process, low cost, etc., is easy to prepare on a large scale, and can be used as a substrate to make a gas diffusion layer through a simple and low-cost preparation process, which is suitable for use in fuel cells.

[0035] Specifically:

[0036] 1) The chitosan fiber-reduced graphene oxide composite paper of the present invention combines the advantages of chitosan fibers and reduced graphene oxide (for example: the flexibility and foldability of chitosan fibers; the excellent mechanical properties of reduced graphene oxide). Using it as a substrate can prepare a gas diffusion layer with light weight and good flexibility;

[0037] 2) The chitosan fiber-reduced graphene oxide composite paper of the present invention can be directly prepared on traditional papermaking equipment, and it is very easy to achieve large-scale preparation;

[0038] 3) The chitosan fiber-reduced graphene oxide composite paper of the present invention can be directly subjected to hydrophobic treatment and spraying process, and a gas diffusion layer can be made without the need for thermosetting resin hot pressing, sintering process and graphitization treatment;

[0039] 4) The gas diffusion layer made of the chitosan fiber-reduced graphene oxide composite paper of the present invention has the advantages of wide raw material sources, low price, simple preparation process, etc.;

[0040] 5) The gas diffusion layer made of the chitosan fiber-reduced graphene oxide composite paper of the present invention has the advantages of small thickness and high conductivity, and is suitable for use in fuel cells;

[0041] 6) The present invention uses chitosan fibers and graphene oxide to prepare chitosan fiber-reduced graphene oxide composite paper. The surface of chitosan fibers contains a large number of groups, which can adsorb and induce graphene oxide to perform layer-by-layer self-assembly on the surface of chitosan fibers, which is beneficial to the uniform dispersion of graphene oxide. And by adding wet strength agents and retention aids, graphene oxide can be retained as much as possible, avoiding the loss of graphene oxide. Description of the Drawings

[0042] Figure 1 It is a physical picture of the chitosan fiber-reduced graphene oxide composite paper of Example 3.

[0043] Figure 2 It is an SEM picture of the chitosan fiber-reduced graphene oxide composite paper of Example 3.

[0044] Figure 3 It is a graph of the test results of the sheet resistance of the chitosan fiber-reduced graphene oxide composite paper with different reduced graphene oxide contents.

[0045] Figure 4 It is a graph of the test results of the conductivity of the chitosan fiber-reduced graphene oxide composite paper of Example 3.

[0046] Figure 5 It is a graph of the test results of the tensile strength of the chitosan fiber-reduced graphene oxide composite paper with different reduced graphene oxide contents.

[0047] Figure 6 This is a physical picture of the fuel cell testing device.

[0048] Figure 7 This is the polarization curve of a single fuel cell made of the chitosan fiber-reduced graphene oxide composite paper of Example 3. DETAILED DESCRIPTION

[0049] The present invention will be further explained and illustrated below with reference to specific embodiments.

[0050] Example 1:

[0051] A chitosan fiber-reduced graphene oxide composite paper, the preparation method of which is as follows:

[0052] 1) 1 g of graphene oxide (prepared by the modified Hummers method) was added to 1000 mL of ultrapure water and stirred for 20 min. The mixture was then transferred to a cell disruptor and ultrasonicated at 30°C and 400 W for 30 min to obtain a graphene oxide dispersion (concentration: 0.001 g / mL).

[0053] 2) adding 3.0144 g of chitosan fibers (length 3 mm to 6 mm) and 1500 mL of water into a pulp deflaker and deflaking at 30,000 revolutions to obtain chitosan fiber pulp (concentration approximately 0.2 wt%);

[0054] 3) Add 0.2 g of PAE (viscosity 25 mPa·s to 75 mPa·s, viscosity test temperature 25°C; pH 4.0 to 7.0) to 199.8 g of ultrapure water and stir at 300 rpm for 6 h to obtain a PAE solution (concentration approximately 0.001 g / mL);

[0055] 4) Add 0.2 g of CPAM (weight-average molecular weight, 12,000,000) to 199.8 g of ultrapure water and stir at 300 rpm for 6 h to obtain a CPAM solution (concentration, approximately 0.001 g / mL);

[0056] 5) adding 15.1 mL of PAE solution to the chitosan fiber pulp of step 2) and stirring for 10 min, then adding 18.84 mL of CPAM solution and stirring for 10 min, then adding 753.6 mL of graphene oxide dispersion and stirring for 10 min to obtain chitosan fiber-graphene oxide composite pulp (the amount of PAE is 0.5% of the mass of the chitosan fiber, and the amount of CPAM is 2.5% of the mass of the graphene oxide);

[0057] 6) Bubble the chitosan fiber-graphene oxide composite pulp for 20 s, then form paper using a manual sheet former for paper, then press for 1 min under the condition of a pressure of 0.5 MPa, and then dry for 8 min under the condition of a temperature of 80 °C to obtain chitosan fiber-graphene oxide composite paper (grammage is about 120 g / m 2 , and the graphene oxide content is about 20 wt%);

[0058] 7) Immerse the chitosan fiber-graphene oxide composite paper in water, then add 0.7536 g of hydrazine hydrate (the dosage of hydrazine hydrate is 100% of the mass of graphene oxide), reduce it at a temperature of 80 °C for 2 h, then take it out and wash it with ultrapure water, then immerse it in a 10% PTFE (weight average molecular weight is 5000) solution, and then take it out and hold it at a temperature of 300 °C for 4 h to obtain chitosan fiber-reduced graphene oxide composite paper (the loading amount of PTFE is 5%).

[0059] A gas diffusion layer, and its preparation method is as follows:

[0060] Disperse PTFE (weight average molecular weight is 5000) and acetylene black with ethanol to make 100 mL of a mixed slurry. The mass ratio of PTFE to acetylene black is 1:0.05, and then spray it on the surface of the chitosan fiber-reduced graphene oxide composite paper in this example. The spraying amount of the mixed slurry on the chitosan fiber-reduced graphene oxide composite paper is 5 mg / cm 2 , and then hold it at a temperature of 300 °C for 4 h to obtain a gas diffusion layer.

[0061] A fuel cell is assembled from a membrane electrode and the gas diffusion layer in this example.

[0062] After testing (the planar resistance is tested with reference to "GB / T 20042.7-2014 Proton Exchange Membrane Fuel Cells - Part 7 Test Methods for the Characteristics of Carbon Paper"; the tensile strength is tested using a tensile testing machine. The size specification of the test sample is 7 cm × 1 cm, and the average value is taken after repeating the test 3 times), the planar resistance of the chitosan fiber-reduced graphene oxide composite paper in this example is 1210 Ω, and the tensile strength is 16.73 MPa.

[0063] Example 2:

[0064] A chitosan fiber-reduced graphene oxide composite paper, and its preparation method is as follows:

[0065] 1) Add 1.884 g of graphene oxide (prepared by the improved Hummers method) to 376.8 mL of ultrapure water, stir for 20 min, then transfer it to a cell disruptor and ultrasonicate for 2 h at a temperature of 30 °C and an ultrasonic power of 100 W to obtain a graphene oxide dispersion (concentration: 0.005 g / mL);

[0066] 2) Add 1.884 g of chitosan fibers (length: 3 mm - 6 mm) and 942 mL of water to a pulper and defibrate for 30,000 revolutions to obtain chitosan fiber pulp (concentration: approximately 0.2 wt%);

[0067] 3) Add 0.2 g of PAE (viscosity: 25 mPa·s - 75 mPa·s, viscosity measured at 25 °C; pH value: 4.0 - 7.0) to 199.8 g of ultrapure water and stir for 6 h at a stirring rate of 300 rpm to obtain a PAE solution (concentration: approximately 0.001 g / mL);[[ID=e7]]

[0068] 4) Add 0.2 g of PEI (weight-average molecular weight: 1800) to 199.8 g of ultrapure water and stir for 6 h at a stirring rate of 300 rpm to obtain a PEI solution (concentration: approximately 0.001 g / mL);

[0069] 5) Add 14.13 mL of the PAE solution to the chitosan fiber pulp obtained in step 2), stir for 10 min, then add 18.84 mL of the PEI solution, stir for 10 min, and then add the graphene oxide dispersion obtained in step 1), stir for 10 min to obtain chitosan fiber - graphene oxide composite pulp (the dosage of PAE is 0.75% of the mass of chitosan fibers, and the dosage of PEI is 1% of the mass of graphene oxide);

[0070] 6) Bubble the chitosan fiber - graphene oxide composite pulp for 10 s, then form paper using a manual sheet former, then press for 3 min under a pressure of 0.7 MPa, and then dry for 12 min at a temperature of 85 °C to obtain chitosan fiber - graphene oxide composite paper (grammage: approximately 120 g / m 2 , graphene oxide content: approximately 50 wt%);

[0071] 7) Immerse the chitosan fiber - graphene oxide composite paper in water, then add 3.768 g of ascorbic acid (the dosage of ascorbic acid is 200% of the mass of graphene oxide), reduce at a temperature of 90 °C for 3 h, then take it out and wash with ultrapure water, then immerse it in a 10% PVDF (weight-average molecular weight: 400,000) solution, and then take it out and hold at a temperature of 350 °C for 3 h to obtain chitosan fiber - reduced graphene oxide composite paper (PVDF loading: 15%).

[0072] A gas diffusion layer is prepared as follows:

[0073] PVDF (weight-average molecular weight of 400,000) and biomass carbon black are dispersed in ethanol to prepare a 100 mL mixed slurry. The mass ratio of PVDF to biomass carbon black is 1:0.15, and then it is sprayed on the surface of the chitosan fiber-reduced graphene oxide composite paper in this example. The spraying amount of the mixed slurry on the chitosan fiber-reduced graphene oxide composite paper is 4 mg / cm 2 , and then it is kept at 350 °C for 3 h to obtain the gas diffusion layer.

[0074] A fuel cell is assembled from a membrane electrode and the gas diffusion layer in this example.

[0075] After testing (the testing method is the same as that in Example 1), the surface resistance of the chitosan fiber-reduced graphene oxide composite paper in this example is 15.8 Ω, and the tensile strength is 12.46 MPa.

[0076] Example 3:

[0077] A chitosan fiber-reduced graphene oxide composite paper is prepared as follows:

[0078] 1) 2.6376 g of graphene oxide (prepared by the improved Hummers method) is added to 263.76 mL of ultrapure water, stirred for 20 min, and then transferred to a cell disruptor. It is ultrasonically treated for 2 h at a temperature of 30 °C and an ultrasonic power of 100 W to obtain a graphene oxide dispersion (concentration of 0.01 g / mL);

[0079] 2) 1.1304 g of chitosan fibers (length 3 mm - 6 mm) and 565.2 mL of water are added to a pulp disintegrator and disintegrated for 30,000 revolutions to obtain chitosan fiber pulp (concentration about 0.2 wt%);

[0080] 3) 0.2 g of PAE (viscosity 25 mPa·s - 75 mPa·s, viscosity test temperature 25 °C; pH value 4.0 - 7.0) is added to 199.8 g of ultrapure water and stirred at a stirring rate of 300 rpm for 6 h to obtain a PAE solution (concentration about 0.001 g / mL);

[0081] 4) 0.2 g of PEO (weight-average molecular weight of 3,000,000) is added to 199.8 g of ultrapure water and stirred at a stirring rate of 300 rpm for 6 h to obtain a PEO solution (concentration about 0.001 g / mL);

[0082] 5) Add 11.304 mL of PAE solution to the chitosan fiber pulp in step 2), stir for 10 min, then add 105.5 mL of PEO solution, stir for 10 min, and then add the graphene oxide dispersion in step 1), stir for 10 min to obtain chitosan fiber-graphene oxide composite pulp (the dosage of PAE is 1% of the mass of chitosan fiber, and the dosage of PEO is 4% of the mass of graphene oxide);

[0083] 6) Bubble the chitosan fiber-graphene oxide composite pulp for 15 s, then form paper with a manual paper sheet former, then press for 5 min under the condition of a pressure of 1 MPa, and then dry for 15 min under the condition of a temperature of 90 °C to obtain chitosan fiber-graphene oxide composite paper (the grammage is about 120 g / m 2 , and the graphene oxide content is about 70 wt%);

[0084] 7) Immerse the chitosan fiber-graphene oxide composite paper in water, then add 7.9128 g of hydroiodic acid (HI) with a mass fraction of 50% (the dosage of HI is 150% of the mass of graphene oxide), reduce it at a temperature of 100 °C for 4 h, then take it out and wash it with ultrapure water, then immerse it in a 10% FEP (weight average molecular weight is 250.04) solution, and then take it out and keep it at a temperature of 400 °C for 2 h to obtain chitosan fiber-reduced graphene oxide composite paper (the loading amount of FEP is 25%).

[0085] A gas diffusion layer, the preparation method thereof is as follows:

[0086] Disperse FEP (weight average molecular weight is 250.04) and rubber carbon black with ethanol to make 100 mL of mixed slurry, the mass ratio of FEP to rubber carbon black is 1:0.25, and then spray it on the surface of the chitosan fiber-reduced graphene oxide composite paper in this example. The spraying amount of the mixed slurry on the chitosan fiber-reduced graphene oxide composite paper is 3 mg / cm 2 , and then keep it at a temperature of 400 °C for 2 h to obtain the gas diffusion layer.

[0087] A fuel cell, which is assembled from a membrane electrode and the gas diffusion layer in this example.

[0088] After testing (the testing method is the same as that in Example 1), the surface resistance of the chitosan fiber-reduced graphene oxide composite paper in this example is 0.4 Ω, and the tensile strength is 7.65 MPa.

[0089] Performance test:

[0090] a) The physical picture of the chitosan fiber-reduced graphene oxide composite paper in this example is as Figure 1 shown.

[0091] Depend on Figure 1 It can be seen that the chitosan fiber-reduced graphene oxide composite paper of this embodiment has good uniformity, and the components are tightly combined without obvious damage.

[0092] b) The scanning electron microscope (SEM) image of the chitosan fiber-reduced graphene oxide composite paper of this embodiment is as follows Figure 2 shown.

[0093] Depend on Figure 2 It can be seen that reduced graphene oxide is tightly loaded on the surface of chitosan fibers, thereby giving the composite paper good conductivity.

[0094] c) Referring to the operation of this embodiment, the sheet resistance test results of the prepared chitosan fiber-reduced graphene oxide composite paper with different reduced graphene oxide contents are as follows: Figure 3 shown.

[0095] Depend on Figure 3 It can be seen that the square resistance of the chitosan fiber-reduced graphene oxide composite paper decreases with the increase of the reduced graphene oxide content (when the reduced graphene oxide content is 0, the obtained chitosan fiber paper is not conductive), and when the reduced graphene oxide content reaches 70wt%, the square resistance changes little, and the resistance is only 0.2Ω~0.4Ω, indicating that the chitosan fiber-reduced graphene oxide composite paper has good conductive properties.

[0096] d) The chitosan fiber-reduced graphene oxide composite paper of this embodiment is connected in series with an LED lamp, and then connected to a power supply. The conductivity of the chitosan fiber-reduced graphene oxide composite paper is tested by observing whether the LED lamp can be lit. The test results are as follows: Figure 4 shown.

[0097] Depend on Figure 4 It can be seen that the LED lamp is normally lit, indicating that the chitosan fiber-reduced graphene oxide composite paper of this embodiment has good conductive properties.

[0098] e) Referring to the operation of this embodiment, the tensile strength test results of the prepared chitosan fiber-reduced graphene oxide composite paper with different reduced graphene oxide contents are as follows: Figure 5 shown.

[0099] Depend on Figure 5 It can be seen that the tensile strength of the chitosan fiber-reduced graphene oxide composite paper increases with the increase of the reduced graphene oxide content, and the chitosan fiber-reduced graphene oxide composite paper with a reduced graphene oxide content of 20wt% to 70wt% has good mechanical properties.

[0100] f) The chitosan fiber-reduced graphene oxide composite paper of this embodiment is placed into a fuel cell test device (such as Figure 6 As shown), the single cell performance test was carried out under the conditions of temperature of 80°C, relative humidity of 100%, hydrogen flow rate of 400mL / min, and air flow rate of 1500mL / min. The polarization curve of the fuel cell single cell obtained by the test is shown as follows Figure 7 shown.

[0101] Depend on Figure 7 It can be seen that the current density of the fuel cell made of the chitosan fiber-reduced graphene oxide composite paper of this embodiment can reach 1050mA / cm when the voltage is 0.65V. 2 , the maximum power density can reach 800mw / cm 2 The performance exceeds that of most similar products, indicating that the chitosan fiber-reduced graphene oxide composite paper of this embodiment has a relatively broad application prospect in fuel cells.

[0102] Example 4:

[0103] A chitosan fiber-reduced graphene oxide composite paper, the preparation method of which is as follows:

[0104] 1) 1 g of graphene oxide (prepared by the modified Hummers method) was added to 1000 mL of ultrapure water and stirred for 20 min. The mixture was then transferred to a cell disruptor and ultrasonicated at 30°C and 400 W for 30 min to obtain a graphene oxide dispersion (concentration: 0.001 g / mL).

[0105] 2) adding 3.0144 g of chitosan fibers (length 3 mm to 6 mm) and 1500 mL of water into a pulp deflaker and deflaking at 30,000 revolutions to obtain chitosan fiber pulp (concentration approximately 0.2 wt%);

[0106] 3) Add 0.2 g of PVA (weight-average molecular weight 89,000) to 199.8 g of ultrapure water and stir at 300 rpm for 6 h to obtain a PVA solution (concentration approximately 0.001 g / mL);

[0107] 4) Add 0.2 g of CPAM (weight-average molecular weight, 12,000,000) to 199.8 g of ultrapure water and stir at 300 rpm for 6 h to obtain a CPAM solution (concentration, approximately 0.001 g / mL);

[0108] 5) adding 15.1 mL of the PVA solution to the chitosan fiber pulp of step 2) and stirring for 10 min, then adding 18.84 mL of the CPAM solution and stirring for 10 min, then adding 753.6 mL of the graphene oxide dispersion and stirring for 10 min to obtain a chitosan fiber-graphene oxide composite pulp (the amount of PVA is 0.5% of the mass of the chitosan fiber, and the amount of CPAM is 2.5% of the mass of the graphene oxide);

[0109] 6) The chitosan fiber-graphene oxide composite pulp was bubbled for 15 seconds, and then formed into paper using a manual paper sheeting machine, and then pressed for 5 minutes under a pressure of 0.5 MPa, and then dried at a temperature of 80°C for 15 minutes to obtain chitosan fiber-graphene oxide composite paper (weight about 120 g / m 2 , graphene oxide content is about 20wt%);

[0110] 7) The chitosan fiber-graphene oxide composite paper was immersed in water, and then 0.7536 g of hydrazine hydrate was added (the amount of hydrazine hydrate was 100% of the mass of graphene oxide), and reduced at a temperature of 80 ° C for 3 h. Then, it was taken out and washed with ultrapure water, and then immersed in a 10% mass fraction of PVDF (weight average molecular weight of 400000) solution. Then, it was taken out and kept at a temperature of 400 ° C for 4 h to obtain chitosan fiber-reduced graphene oxide composite paper (PVDF loading amount is 15%).

[0111] A gas diffusion layer, the preparation method of which is as follows:

[0112] PVDF (weight average molecular weight of 400,000) and acetylene black were dispersed in ethanol to prepare 100 mL of mixed slurry, with a mass ratio of PVDF to acetylene black of 1:0.15, and then sprayed on the surface of the chitosan fiber-reduced graphene oxide composite paper in this embodiment. The spraying amount of the mixed slurry on the chitosan fiber-reduced graphene oxide composite paper was 5 mg / cm 2 , and then maintain it at a temperature of 300℃ for 5h to obtain a gas diffusion layer.

[0113] A fuel cell is assembled from a membrane electrode and a gas diffusion layer in this embodiment.

[0114] After testing (the testing method is the same as that of Example 1), the chitosan fiber-reduced graphene oxide composite paper of this embodiment has a plane resistance of 1160Ω and a tensile strength of 17.44 MPa.

[0115] Example 5:

[0116] A chitosan fiber-reduced graphene oxide composite paper, the preparation method of which is as follows:

[0117] 1) Add 1.884 g of graphene oxide (prepared by the improved Hummers method) to 376.8 mL of ultrapure water, stir for 20 min, then transfer it to a cell disruptor and sonicate for 2 h at a temperature of 30 °C and a sonication power of 100 W to obtain a graphene oxide dispersion (concentration: 0.005 g / mL);

[0118] 2) Add 1.884 g of chitosan fibers (length: 3 mm - 6 mm) and 942 mL of water to a pulper and defibrate for 30,000 revolutions to obtain chitosan fiber pulp (concentration: approximately 0.2 wt%);

[0119] 3) Add 0.2 g of PVA (weight average molecular weight: 89,000) to 199.8 g of ultrapure water and stir for 6 h at a stirring rate of 300 rpm to obtain a PVA solution (concentration: approximately 0.001 g / mL);

[0120] 4) Add 0.2 g of PEI (weight average molecular weight: 1,800) to 199.8 g of ultrapure water and stir for 6 h at a stirring rate of 300 rpm to obtain a PEI solution (concentration: approximately 0.001 g / mL);

[0121] 5) Add 14.13 mL of the PVA solution to the chitosan fiber pulp obtained in step 2), stir for 10 min, then add 18.84 mL of the PEI solution, stir for 10 min, and then add the graphene oxide dispersion obtained in step 1), stir for 10 min to obtain chitosan fiber - graphene oxide composite pulp (the dosage of PVA is 0.75% of the mass of chitosan fibers, and the dosage of PEI is 1% of the mass of graphene oxide);

[0122] 6) Bubble the chitosan fiber - graphene oxide composite pulp for 10 s, then form paper using a manual sheet former for paper, then press for 1 min at a pressure of 1 MPa, and then dry for 8 min at a temperature of 90 °C to obtain chitosan fiber - graphene oxide composite paper (grammage: approximately 120 g / m 2 , graphene oxide content: approximately 50 wt%);

[0123] 7) Immerse the chitosan fiber - graphene oxide composite paper in water, then add 3.768 g of ascorbic acid (the dosage of ascorbic acid is 200% of the mass of graphene oxide), reduce at a temperature of 90 °C for 4 h, then take it out and wash with ultrapure water, then immerse it in a 10% FEP (weight average molecular weight: 250.04) solution, then take it out and hold at a temperature of 300 °C for 3 h to obtain chitosan fiber - reduced graphene oxide composite paper (FEP loading: 25%).

[0124] A gas diffusion layer, the preparation method of which is as follows:

[0125] FEP (weight average molecular weight of 250.04) and biomass carbon black were dispersed in ethanol to prepare 100 mL of mixed slurry, with a mass ratio of FEP to biomass carbon black of 1:0.25, and then sprayed on the surface of the chitosan fiber-reduced graphene oxide composite paper in this embodiment. The spraying amount of the mixed slurry on the chitosan fiber-reduced graphene oxide composite paper was 5 mg / cm 2 , and then maintain it at a temperature of 300℃ for 5h to obtain a gas diffusion layer.

[0126] A fuel cell is assembled from a membrane electrode and a gas diffusion layer in this embodiment.

[0127] After testing (the testing method is the same as that of Example 1), the chitosan fiber-reduced graphene oxide composite paper of this embodiment has a plane resistance of 13.2Ω and a tensile strength of 13.52 MPa.

[0128] Example 6:

[0129] A chitosan fiber-reduced graphene oxide composite paper, the preparation method of which is as follows:

[0130] 1) 2.6376 g of graphene oxide (prepared by a modified Hummers method) was added to 263.76 mL of ultrapure water and stirred for 20 min. The mixture was then transferred to a cell disruptor and ultrasonicated at 30°C and 100 W for 2 h to obtain a graphene oxide dispersion (concentration: 0.01 g / mL).

[0131] 2) adding 1.1304 g of chitosan fibers (3 mm to 6 mm in length) and 565.2 mL of water into a pulp deflaker and deflaking the fibers at 30,000 revolutions to obtain chitosan fiber pulp (concentration of approximately 0.2 wt%);

[0132] 3) Add 0.2 g of PVA (weight-average molecular weight 89,000) to 199.8 g of ultrapure water and stir at 300 rpm for 6 h to obtain a PVA solution (concentration approximately 0.001 g / mL);

[0133] 4) Add 0.2 g of PEO (weight-average molecular weight, 3,000,000) to 199.8 g of ultrapure water and stir at 300 rpm for 6 h to obtain a PEO solution (concentration, approximately 0.001 g / mL);

[0134] 5) Add 11.304 mL of PVA solution to the chitosan fiber pulp in step 2), stir for 10 min, then add 105.5 mL of PEO solution, stir for 10 min, and then add the graphene oxide dispersion in step 1), stir for 10 min to obtain chitosan fiber-graphene oxide composite pulp (the dosage of PVA is 1% of the mass of chitosan fiber, and the dosage of PEO is 4% of the mass of graphene oxide);

[0135] 6) Bubble the chitosan fiber-graphene oxide composite pulp for 20 s, then form paper with a manual paper sheet former, then press for 1 min under the condition of a pressure of 0.7 MPa, and then dry for 15 min under the condition of a temperature of 85 °C to obtain chitosan fiber-graphene oxide composite paper (the grammage is about 120 g / m 2 , and the graphene oxide content is about 70 wt%);

[0136] 7) Immerse the chitosan fiber-graphene oxide composite paper in water, then add 7.9128 g of hydroiodic acid with a mass fraction of 50% (the dosage of HI is 150% of the mass of graphene oxide), reduce it at a temperature of 100 °C for 2 h, then take it out and wash it with ultrapure water, then immerse it in a 10% PTFE (weight average molecular weight of 5000) solution, and then take it out and keep it at a temperature of 350 °C for 2 h to obtain chitosan fiber-reduced graphene oxide composite paper (the loading amount of PTFE is 5%).

[0137] A gas diffusion layer, and its preparation method is as follows:

[0138] Disperse PTFE (weight average molecular weight of 5000) and rubber carbon black with ethanol to make 100 mL of mixed slurry, the mass ratio of PTFE to rubber carbon black is 1:0.05, and then spray it on the surface of the chitosan fiber-reduced graphene oxide composite paper in this example. The spraying amount of the mixed slurry on the chitosan fiber-reduced graphene oxide composite paper is 5 mg / cm 2 , and then keep it at a temperature of 300 °C for 5 h to obtain the gas diffusion layer.

[0139] A fuel cell is assembled from a membrane electrode and the gas diffusion layer in this example.

[0140] After testing (the testing method is the same as that in Example 1), the surface resistance of the chitosan fiber-reduced graphene oxide composite paper in this example is 0.32 Ω, and the tensile strength is 7.91 MPa.

[0141] Example 7:

[0142] A chitosan fiber-reduced graphene oxide composite paper, and its preparation method is as follows:

[0143] 1) Add 1 g of graphene oxide (prepared by the improved Hummers method) to 1000 mL of ultrapure water, stir for 20 min, then transfer it to a cell disruptor and sonicate for 30 min at a temperature of 30 °C and a sonication power of 400 W to obtain a graphene oxide dispersion (concentration: 0.001 g / mL);

[0144] 2) Add 3.0144 g of chitosan fibers (length: 3 mm - 6 mm) and 1500 mL of water to a pulper and defibrate for 30000 revolutions to obtain chitosan fiber pulp (concentration: approximately 0.2 wt%);

[0145] 3) Add 0.2 g of CMC-Na (weight-average molecular weight: 242.16) to 199.8 g of ultrapure water and stir for 6 h at a stirring rate of 300 rpm to obtain a CMC-Na solution (concentration: approximately 0.001 g / mL);

[0146] 4) Add 0.2 g of CPAM (weight-average molecular weight: 12000000) to 199.8 g of ultrapure water and stir for 6 h at a stirring rate of 300 rpm to obtain a CPAM solution (concentration: approximately 0.001 g / mL);

[0147] 5) Add 15.1 mL of the PCMC-Na solution to the chitosan fiber pulp obtained in step 2), stir for 10 min, then add 18.84 mL of the CPAM solution, stir for 10 min, and then add 753.6 mL of the graphene oxide dispersion and stir for 10 min to obtain chitosan fiber-graphene oxide composite pulp (the dosage of CMC-Na is 0.5% of the mass of chitosan fibers, and the dosage of CPAM is 2.5% of the mass of graphene oxide);

[0148] 6) Bubble the chitosan fiber-graphene oxide composite pulp for 10 s, then form paper using a manual sheet former for paper, then press for 5 min at a pressure of 0.5 MPa, and then dry for 15 min at a temperature of 80 °C to obtain chitosan fiber-graphene oxide composite paper (grammage: approximately 120 g / m 2 , graphene oxide content: approximately 20 wt%);

[0149] 7) Immerse the chitosan fiber-graphene oxide composite paper in water, then add 0.7536 g of hydrazine hydrate (the dosage of hydrazine hydrate is 100% of the mass of graphene oxide), reduce it at a temperature of 80 °C for 4 h, then take it out and wash it with ultrapure water, then immerse it in a 10% FEP (weight-average molecular weight: 250.04) solution, and then take it out and hold it at a temperature of 350 °C for 4 h to obtain chitosan fiber-reduced graphene oxide composite paper (FEP loading: 25%).

[0150] A gas diffusion layer, the preparation method of which is as follows:

[0151] FEP (weight average molecular weight of 250.04) and acetylene black were dispersed in ethanol to prepare 100 mL of mixed slurry, with a mass ratio of FEP to acetylene black of 1:0.25, and then sprayed on the surface of the chitosan fiber-reduced graphene oxide composite paper in this embodiment. The spraying amount of the mixed slurry on the chitosan fiber-reduced graphene oxide composite paper was 5 mg / cm 2 , and then maintain it at a temperature of 300℃ for 5h to obtain a gas diffusion layer.

[0152] A fuel cell is assembled from a membrane electrode and a gas diffusion layer in this embodiment.

[0153] After testing (the testing method is the same as that of Example 1), the chitosan fiber-reduced graphene oxide composite paper of this embodiment has a plane resistance of 1248Ω and a tensile strength of 16.02 MPa.

[0154] Example 8:

[0155] A chitosan fiber-reduced graphene oxide composite paper, the preparation method of which is as follows:

[0156] 1.884 g of graphene oxide (prepared by a modified Hummers method) was added to 376.8 mL of ultrapure water and stirred for 20 min. The mixture was then transferred to a cell disruptor and ultrasonicated at 30°C and 100 W for 2 h to obtain a graphene oxide dispersion (concentration: 0.005 g / mL).

[0157] 2) adding 1.884 g of chitosan fibers (3 mm to 6 mm in length) and 942 mL of water into a pulp deflaker and deflaking the fibers at 30,000 revolutions to obtain chitosan fiber pulp (concentration of approximately 0.2 wt%);

[0158] 3) Add 0.2 g of CMC-Na (weight-average molecular weight 242.16) to 199.8 g of ultrapure water and stir at 300 rpm for 6 h to obtain a CMC-Na solution (concentration approximately 0.001 g / mL);

[0159] 4) Add 0.2 g of PEI (weight-average molecular weight 1800) to 199.8 g of ultrapure water and stir at 300 rpm for 6 h to obtain a PEI solution (concentration approximately 0.001 g / mL);

[0160] 5) adding 14.13 mL of CMC-Na solution to the chitosan fiber pulp of step 2) and stirring for 10 min, then adding 18.84 mL of PEI solution and stirring for 10 min, and then adding the graphene oxide dispersion of step 1) and stirring for 10 min to obtain chitosan fiber-graphene oxide composite pulp (the amount of CMC-Na is 0.75% of the mass of the chitosan fiber, and the amount of PEI is 1% of the mass of the graphene oxide);

[0161] 6) The chitosan fiber-graphene oxide composite pulp was bubbled for 15 seconds, and then formed into paper using a manual paper sheeting machine, and then pressed for 3 minutes under a pressure of 0.7 MPa, and then dried at a temperature of 85°C for 12 minutes to obtain chitosan fiber-graphene oxide composite paper (weight about 120 g / m 2 , graphene oxide content is about 50wt%);

[0162] 7) The chitosan fiber-graphene oxide composite paper was immersed in water, and then 3.768 g of ascorbic acid was added (the amount of ascorbic acid was 200% of the mass of graphene oxide), and reduced at a temperature of 90 ° C for 2 h. Then, it was taken out and washed with ultrapure water, and then immersed in a 10% mass fraction of PTFE (weight average molecular weight of 5000) solution, and then taken out and kept at a temperature of 300 ° C for 2 h to obtain chitosan fiber-reduced graphene oxide composite paper (PTFE loading amount was 5%).

[0163] A gas diffusion layer, the preparation method of which is as follows:

[0164] PTFE (weight average molecular weight of 5000) and biomass carbon black were dispersed in ethanol to prepare 100 mL of mixed slurry, with a mass ratio of PTFE to biomass carbon black of 1:0.05, and then sprayed on the surface of the chitosan fiber-reduced graphene oxide composite paper in this embodiment. The spraying amount of the mixed slurry on the chitosan fiber-reduced graphene oxide composite paper was 5 mg / cm 2 , and then maintain it at a temperature of 300℃ for 5h to obtain a gas diffusion layer.

[0165] A fuel cell is assembled from a membrane electrode and a gas diffusion layer in this embodiment.

[0166] After testing (the testing method is the same as that of Example 1), the chitosan fiber-reduced graphene oxide composite paper of this embodiment has a plane resistance of 11.6Ω and a tensile strength of 11.60 MPa.

[0167] Example 9:

[0168] A chitosan fiber-reduced graphene oxide composite paper, the preparation method of which is as follows:

[0169] 1) Add 2.6376 g of graphene oxide (prepared by the improved Hummers method) to 263.76 mL of ultrapure water, stir for 20 min, then transfer it to a cell disruptor and sonicate for 2 h at a temperature of 30 °C and an ultrasonic power of 100 W to obtain a graphene oxide dispersion (concentration: 0.01 g / mL);

[0170] 2) Add 1.1304 g of chitosan fibers (length: 3 mm - 6 mm) and 565.2 mL of water to a pulper and defibrate for 30,000 revolutions to obtain chitosan fiber pulp (concentration: approximately 0.2 wt%);

[0171] 3) Add 0.2 g of CMC-Na (weight-average molecular weight: 242.16) to 199.8 g of ultrapure water and stir for 6 h at a stirring rate of 300 rpm to obtain a CMC-Na solution (concentration: approximately 0.001 g / mL);

[0172] 4) Add 0.2 g of PEO (weight-average molecular weight: 3,000,000) to 199.8 g of ultrapure water and stir for 6 h at a stirring rate of 300 rpm to obtain a CPAM solution (concentration: approximately 0.001 g / mL);

[0173] 5) Add 11.304 mL of the CMC-Na solution to the chitosan fiber pulp in step 2), stir for 10 min, then add 105.5 mL of the PEO solution, stir for 10 min, and then add the graphene oxide dispersion in step 1) and stir for 10 min to obtain chitosan fiber-graphene oxide composite pulp (the dosage of CMC-Na is 1% of the mass of chitosan fibers, and the dosage of PEO is 4% of the mass of graphene oxide);

[0174] 6) Bubble the chitosan fiber-graphene oxide composite pulp for 20 s, then form paper using a manual sheet former, then press for 5 min under a pressure of 1 MPa, and then dry for 12 min at a temperature of 90 °C to obtain chitosan fiber-graphene oxide composite paper (grammage: approximately 120 g / m 2 , graphene oxide content: approximately 70 wt%);

[0175] 7) Immerse the chitosan fiber-graphene oxide composite paper in water, then add 7.9128 g of 50% hydroiodic acid (HI dosage: 50% of the mass of graphene oxide), reduce at a temperature of 100 °C for 3 h, then take it out and wash with ultrapure water, then immerse it in a 10% PVDF (weight-average molecular weight: 400,000) solution, and then take it out and hold at a temperature of 400 °C for 3 h to obtain chitosan fiber-reduced graphene oxide composite paper (PVDF loading: 15%).

[0176] A gas diffusion layer is prepared as follows:

[0177] PVDF (weight-average molecular weight of 400,000) and rubber carbon black are dispersed in ethanol to form a 100 mL mixed slurry. The mass ratio of PVDF to rubber carbon black is 1:0.15, and then it is sprayed on the surface of the chitosan fiber-reduced graphene oxide composite paper in this embodiment. The spraying amount of the mixed slurry on the chitosan fiber-reduced graphene oxide composite paper is 5 mg / cm 2 , and then it is maintained at 300 °C for 5 h to obtain the gas diffusion layer.

[0178] A fuel cell is assembled from a membrane electrode and the gas diffusion layer in this embodiment.

[0179] After testing (the testing method is the same as that in Example 1), the surface resistance of the chitosan fiber-reduced graphene oxide composite paper in this embodiment is 0.43 Ω, and the tensile strength is 7.39 MPa.

[0180] The above embodiments are preferred embodiments of the present invention. However, the embodiments of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications made without departing from the spirit and principle of the present invention shall be equivalent replacement methods and are all included in the protection scope of the present invention.

Claims

1. A gas diffusion layer, characterized in that, It includes a chitosan fiber-reduced graphene oxide composite paper; the composition of the chitosan fiber-reduced graphene oxide composite paper includes a chitosan fiber-reduced graphene oxide substrate and a loaded hydrophobic material; the composition of the chitosan fiber-reduced graphene oxide substrate includes chitosan fibers and reduced graphene oxide self-assembled on the surface of the chitosan fibers; the mass ratio of the chitosan fiber-reduced graphene oxide substrate to the hydrophobic material is 1:0.05 to 0.25; the hydrophobic material is at least one of polytetrafluoroethylene, polyvinylidene fluoride, and ethylene propylene perfluoride copolymer; the mass ratio of the chitosan fibers to the reduced graphene oxide is 1:0.25 to 4.

2. The gas diffusion layer according to claim 1, wherein: The length of the chitosan fibers is 3 mm to 6 mm.

3. The gas diffusion layer according to claim 1 or 2, characterized in that: The chitosan fiber-reduced graphene oxide composite paper is made by a preparation method including the following steps: 1) Dispersing chitosan fibers, graphene oxide, a wet strength agent, and a retention aid in water to obtain a chitosan fiber-graphene oxide composite pulp; 2) Sheet-forming the chitosan fiber-graphene oxide composite pulp to obtain a chitosan fiber-graphene oxide composite paper; 3) Immersing the chitosan fiber-graphene oxide composite paper in a reducing agent solution for reduction, and then immersing it in a hydrophobic material dispersion for hydrophobic treatment to obtain the chitosan fiber-reduced graphene oxide composite paper.

4. The gas diffusion layer according to claim 3, wherein: The wet strength agent in step 1) is at least one of polyamide epichlorohydrin resin, polyvinyl alcohol, and sodium carboxymethyl cellulose; the retention aid in step 1) is at least one of polyethyleneimine, cationic polyacrylamide, and polyoxyethylene; the reducing agent solution in step 3) is at least one of ascorbic acid solution, hydrazine hydrate solution, and hydroiodic acid solution.

5. The gas diffusion layer according to claim 3, wherein: The dosage of the wet strength agent in step 1) is 0.5% to 1% of the mass of the chitosan fibers; the dosage of the retention aid in step 1) is 1% to 4% of the mass of the graphene oxide; the dosage of the reducing agent in the reducing agent solution in step 3) is 100% to 200% of the mass of the graphene oxide; the reduction in step 3) is carried out under the condition of a temperature of 80°C to 100°C, and the reduction time is 2 h to 4 h.

6. A fuel cell, characterized in that, It includes the gas diffusion layer according to any one of claims 1 to 5.

Images