Inorganic doping modified proton exchange membrane

Abstract

The invention relates to the technical field of exchange membranes, and discloses an inorganic doping modified proton exchange membrane which comprises the following components in percentage by weight: 10-30% of a proton exchange membrane, the composite material is prepared from 40%-60% of perfluorinated sulfonic acid resin (Nafion), 5%-10% of CeO2 nanoparticles, 5%-10% of TiO2 nanoparticles, 0.1%-1% of quantum dots, 1%-5% of graphene (GO), 2%-5% of ionic liquid and 1%-2% of polyvinyl alcohol (PVA). According to the technical scheme of combining inorganic doping modification with a composite material, CeO2 nanoparticles, quantum dots and graphene are added, so that the technical effect of remarkably improving the conductivity of the proton exchange membrane is achieved, and the problem is solved by optimizing a proton conduction path. The added inorganic particles and graphene obviously enhance the proton conductivity, and the membrane is more stable especially under high-humidity and high-temperature conditions.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of exchange membranes, in particular to an inorganic doped modified proton exchange membrane. BACKGROUND

[0002] Proton exchange membranes (PEM) are widely used in ion conductivity requirements in electrochemical reactions as key materials in applications such as all-vanadium redox flow batteries, fuel cells, water splitting electrolysis devices, etc. Nafion, as one of the most widely used proton exchange membrane materials at present, has high proton conductivity, chemical stability and mechanical strength. However, under high temperature, low humidity and severe operating conditions, the proton conductivity of Nafion membrane often decreases significantly, which is mainly due to the loss of water at high temperature and the weakening of hydration in the membrane when the humidity is too low, resulting in unstable proton migration path and affecting the performance of the membrane. Therefore, how to improve the proton conductivity of the membrane under different environments, especially in high temperature and low humidity environment, has become a key problem to improve its application field.

[0003] The existing technical solutions still have some deficiencies. For example, although the doping of inorganic nanoparticles such as CeO2 and TiO2 can improve the proton conductivity, the surface energy of the particles is high, which is easy to form agglomeration or aggregation phenomenon, resulting in limitation of the uniformity and conductivity path of the membrane. In addition, due to the poor compatibility of inorganic materials with the polymer matrix, the interface is unstable, which directly affects the mechanical strength and durability of the membrane material, especially during long-term use. Therefore, how to improve the dispersibility of inorganic materials and optimize their combination with the polymer matrix is still an important topic in the research of membrane materials.

[0004] At the same time, the application of quantum dots in the existing technology is less, and the introduction of multiple quantum dots lacks optimization of the membrane conductivity path. Quantum dots have unique electronic and proton migration properties, but their distribution in the membrane and their synergistic effect with other components have not been fully utilized. Traditional technology only focuses on the existence of quantum dots in the membrane material, and fails to fully control the distribution and structure arrangement of quantum dots in the membrane, which makes it difficult to effectively tap the potential of its conductivity performance.

[0005] Traditional proton exchange membranes usually use polyvinyl alcohol (PVA) for crosslinking to enhance the mechanical strength of the membrane, but these technical solutions have the problems of unstable crosslinking effect and insufficient mechanical properties of the membrane material in extreme environments. Especially in high humidity or high temperature environment, the mechanical strength and stability of the membrane mostly cannot meet the requirements of long-term use. Therefore, how to improve the mechanical strength and thermal stability of the membrane through effective crosslinking technology is another deficiency in the existing technology. SUMMARY

[0006] In view of the deficiencies of the prior art, the present application provides an inorganic doping modified proton exchange membrane, which solves the problems of insufficient conductivity and poor stability of the existing proton exchange membrane in a high-temperature and low-humidity environment.

[0007] To achieve the above object, the present application is implemented by the following technical scheme: an inorganic doping modified proton exchange membrane, by weight percentage, comprising the following components; perfluorosulfonic acid resin (Nafion) 40-60%, CeO2 nanoparticles 5-10%, TiO2 nanoparticles 5-10%, quantum dots 0.1-1%, graphene (GO) 1-5%, ionic liquid 2-5%, polyvinyl alcohol (PVA) 1-2%.

[0008] Preferably, the surface modification method of the CeO2 nanoparticles can make the surface rich in a large number of -OH and -SO3H groups.

[0009] Preferably, the quantum dots are copper-based quantum dots prepared by chemical vapor deposition.

[0010] Preferably, the ionic liquid is 1-ethyl-3-methyl imidazole sulfonate.

[0011] A preparation method of an inorganic doping modified proton exchange membrane, comprising the following steps:

[0012] S1, dissolving perfluorosulfonic acid resin in an appropriate amount of N, N-dimethylformamide (DMF) to form a perfluorosulfonic acid resin solution;

[0013] S2, dissolving CeO2 nanoparticles and TiO2 nanoparticles in deionized water or an organic solvent respectively, and uniformly dispersing them by ultrasonic treatment;

[0014] S3, adding quantum dots, graphene, ionic liquid and polyvinyl alcohol into the solution, stirring uniformly to form a composite slurry;

[0015] S4, using a spin coating method to coat the above composite slurry on a substrate to form a uniform film layer, and the thickness of the film is controlled at 30-100 μm;

[0016] S5, cross-linking treatment is performed, polyvinyl alcohol (PVA) solution is added, and heating is performed at 50-60℃ for 1h to complete the cross-linking reaction;

[0017] S6, heat treatment is performed, the temperature range is 80-120℃, and the heat treatment time is 2-4h to complete the preparation of the film.

[0018] Preferably, the oxidation treatment of the CeO2 nanoparticles in step S2 is performed by using a mixed solution of sulfuric acid (H2SO4) with a concentration of 1 M and hydrogen peroxide with a concentration of 0.3-3%, in a volume ratio of 1:3, to enrich the CeO2 nanoparticles with -OH and -SO3H groups.

[0019] Preferably, the spin coating method in step S4 has a coating speed of 1000-3000 rpm and a spin coating time of 30-60 s.

[0020] Preferably, the ultrasonic treatment in step S2 has a treatment time of 30-45 min and a frequency of 20-25 kHz.

[0021] Preferably, the cross-linking treatment in step S2 uses a polyvinyl alcohol (PVA) solution with a concentration of 1-2% and is heated at 50-60℃ for 1 h.

[0022] Preferably, the heating rate during the heat treatment in step S2 is 2℃ / min, and the temperature is maintained for 2-4 h during the heat treatment.

[0023] The present application provides an inorganic doped modified proton exchange membrane. It has the following advantages:

[0024] 1. The present application combines the technical solutions of inorganic doping modification and composite materials by adding CeO2 nanoparticles, quantum dots and graphene, which significantly improves the conductivity of the proton exchange membrane. The existing technology cannot effectively improve the conductivity of the membrane in a high-temperature and low-humidity environment, but the present application optimizes the proton conduction path and solves this problem. The addition of inorganic particles and graphene significantly enhances the proton conductivity, especially in low-humidity and high-temperature conditions, the membrane shows more stable performance.

[0025] 2. The present application successfully realizes the optimization of the proton conduction path by using the technical solution of quantum dot regulation of the membrane structure, which improves the overall conductivity of the membrane. Compared with the traditional membrane material which relies on the design of a single material, the present application optimizes the efficiency of proton migration by introducing quantum dots. The unique electronic conduction characteristics of quantum dots enable the membrane to maintain high proton conductivity in complex environments, solving the performance bottleneck caused by poor conduction path in other technologies.

[0026] 3. The present application significantly improves the mechanical strength and thermal stability of the membrane by introducing polyvinyl alcohol (PVA) for cross-linking treatment. In the existing technology, most membrane materials are prone to deformation or performance degradation at high temperatures, but the present application effectively solves this defect through cross-linking technology. The mechanical properties of the membrane material under high temperature and long-term use are greatly improved, thereby effectively prolonging the service life and stability of the membrane.

[0027] 4、The application further improves the proton conductivity and humidity adaptability of the membrane by using ionic liquid to adjust the polarity and hydrophilicity of the membrane. BRIEF DESCRIPTION OF DRAWINGS

[0028] Figure 1 A flow chart of the method of the application. DETAILED DESCRIPTION

[0029] The technical solutions in the embodiments of the application will be clearly and completely described below with reference to the drawings in the specification of the application. Obviously, the described embodiments are only part of the embodiments of the application, rather than all the embodiments. Based on the embodiments in the application, all other embodiments obtained by those skilled in the art without creative efforts fall within the protection scope of the application.

[0030] Please refer to the drawings in the specification of the application Figure 1 The embodiment of the application provides an inorganic doped modified proton exchange membrane, which comprises the following components in percentage by weight: perfluorosulfonic acid resin (Nafion) 40-60%, CeO2 nanoparticles 5-10%, TiO2 nanoparticles 5-10%, quantum dots 0.1-1%, graphene (GO) 1-5%, ionic liquid 2-5%, and polyvinyl alcohol (PVA) 1-2%.

[0031] The surface modification method of the CeO2 nanoparticles can make the surface of the CeO2 nanoparticles rich in a large number of -OH and -SO3H groups.

[0032] The quantum dots are copper-based quantum dots prepared by a chemical vapor deposition method.

[0033] The ionic liquid is 1-ethyl-3-methylimidazolium sulfonate.

[0034] A preparation method of an inorganic doped modified proton exchange membrane comprises the following steps.

[0035] S1, dissolving perfluorosulfonic acid resin in an appropriate amount of N, N-dimethylformamide (DMF) to form a perfluorosulfonic acid resin solution;

[0036] S2, dissolving CeO2 nanoparticles and TiO2 nanoparticles in deionized water or an organic solvent respectively, and uniformly dispersing them by ultrasonic treatment;

[0037] S3, adding quantum dots, graphene, ionic liquid and polyvinyl alcohol into the solution, stirring uniformly, and forming a composite slurry;

[0038] S4. The above composite slurry is coated onto the substrate using a spin coating method to form a uniform film layer with a film thickness controlled between 30-100 μm.

[0039] S5. Perform cross-linking treatment by adding polyvinyl alcohol (PVA) solution and heating at 50-60℃ for 1 hour to complete the cross-linking reaction;

[0040] S6. Perform heat treatment at a temperature range of 80-120℃ for 2-4 hours to complete the membrane preparation.

[0041] Example 1

[0042] Group allocation ratio:

[0043] Perfluorosulfonic acid resin: 45%

[0044] CeO2 nanoparticles: 6%

[0045] TiO2 nanoparticles: 6%

[0046] Quantum dots (copper-based quantum dots): 0.5%

[0047] Graphene (GO): 3%

[0048] Ionic liquid (1-ethyl-3-methylimidazolium sulfonate): 3%

[0049] Polyvinyl alcohol (PVA): 2%

[0050] Specific steps:

[0051] Dissolve 45% of the perfluorosulfonic acid resin in an appropriate amount of DMF and stir until completely dissolved to form a homogeneous solution.

[0052] 6% CeO2 and 6% TiO2 nanoparticles were dissolved in deionized water with a hydrogen peroxide concentration of 3%, and ultrasonically treated for 30 minutes to ensure full dispersion of the particles.

[0053] Add 0.5% copper-based quantum dots, 3% graphene, and 3% ionic liquid to the above solution, and continue stirring for 30 minutes to ensure that the components are evenly dispersed.

[0054] Add 2% polyvinyl alcohol (PVA) solution and stir until homogeneous to form a composite slurry.

[0055] The composite slurry was coated onto the substrate using a spin coating method at a speed of 2000 rpm and a spin coating time of 45 s, with the film thickness controlled at around 50 μm.

[0056] The coated film was subjected to cross-linking treatment at a temperature of 55°C for 1 hour to complete the cross-linking process.

[0057] Heat treatment: The membrane was heat-treated at 80°C for 2 hours to remove the solvent and further enhance the stability of the membrane.

[0058] Example 2

[0059] Group allocation ratio:

[0060] Perfluorosulfonic acid resin: 50%

[0061] CeO2 nanoparticles: 7%

[0062] TiO2 nanoparticles: 4%

[0063] Quantum dots (copper-based quantum dots): 0.3%

[0064] Graphene (GO): 4%

[0065] Ionic liquid (1-ethyl-3-methylimidazolium sulfonate): 2.5%

[0066] Polyvinyl alcohol (PVA): 2.2%

[0067] Specific steps:

[0068] Dissolve 50% of the perfluorosulfonic acid resin in DMF, using magnetic stirring, and maintain the temperature at 60°C until completely dissolved.

[0069] 7% CeO2 and 4% TiO2 nanoparticles were dispersed in deionized water with a hydrogen peroxide concentration of 0.3%, and the mixture was ultrasonically treated for 40 minutes to ensure uniform dispersion of the nanoparticles.

[0070] Add 0.3% copper-based quantum dots, 4% graphene, and 2.5% ionic liquid to the above solution, and continue stirring for 40 minutes to ensure uniform distribution of the components.

[0071] Add 2.2% polyvinyl alcohol solution and stir at 50°C for 30 minutes to ensure uniform dispersion of the crosslinking agent.

[0072] The slurry was coated onto the substrate using a spin coating method at a speed of 2500 rpm for 40 seconds, with the film thickness controlled at 40 μm.

[0073] Crosslinking treatment: Heat the membrane to 60°C and hold for 1.5 hours to allow it to fully crosslink.

[0074] Heat treatment: The membrane is heat-treated at 120°C for 3 hours to remove residual solvent and enhance the mechanical strength of the membrane.

[0075] Example 3

[0076] Group allocation ratio:

[0077] Perfluorosulfonic acid resin: 55%

[0078] CeO2 nanoparticles: 8%

[0079] TiO2 nanoparticles: 5%

[0080] Quantum dots (copper-based quantum dots): 0.5%

[0081] Graphene (GO): 2.5%

[0082] Ionic liquid (1-ethyl-3-methylimidazolium sulfonate): 4%

[0083] Polyvinyl alcohol (PVA): 1.5%

[0084] Specific steps:

[0085] Dissolve 55% of the perfluorosulfonic acid resin in an appropriate amount of DMF, maintain at 60°C, and stir until completely dissolved.

[0086] 8% CeO2 and 5% TiO2 nanoparticles were dissolved in deionized water with a hydrogen peroxide concentration of 3%, and the mixture was ultrasonically treated for 35 minutes to ensure uniform dispersion of the particles.

[0087] Add 0.5% copper-based quantum dots, 2.5% graphene and 4% ionic liquid to the solution, and continue stirring for 1 hour to ensure uniform dispersion.

[0088] Add 1.5% polyvinyl alcohol solution and stir for 30 minutes to form a stable composite slurry.

[0089] The slurry was applied to the substrate using a spin coating method at a speed of 1500 rpm for 50 seconds, with the film thickness controlled at 60 μm.

[0090] Cross-linking treatment is performed by heating the membrane to 50°C and holding it for 1 hour to ensure complete PVA cross-linking.

[0091] Heat treatment was performed by treating the membrane at 90°C for 2 hours to remove the solvent and enhance the membrane's stability.

[0092] Example 4

[0093] Group allocation ratio:

[0094] Perfluorosulfonic acid resin: 60%

[0095] CeO2 nanoparticles: 5%

[0096] TiO2 nanoparticles: 5%

[0097] Quantum dots (copper-based quantum dots): 0.3%

[0098] Graphene (GO): 3%

[0099] Ionic liquid (1-ethyl-3-methylimidazolium sulfonate): 2%

[0100] Polyvinyl alcohol (PVA): 2%

[0101] Specific steps:

[0102] Dissolve 60% of the perfluorosulfonic acid resin in DMF and stir until completely dissolved, while maintaining the temperature at 55°C.

[0103] 5% CeO2 and 5% TiO2 nanoparticles were dissolved in deionized water with a hydrogen peroxide concentration of 0.3%, and ultrasonic treatment was performed for 40 minutes to ensure that the particles were fully dispersed.

[0104] Add 0.3% copper-based quantum dots, 3% graphene and 2% ionic liquid, and stir until homogeneous to form a slurry.

[0105] Add 2% polyvinyl alcohol solution and continue stirring to form a composite slurry, ensuring that all components are evenly dispersed.

[0106] The composite slurry was coated onto the substrate by spin coating at a speed of 1800 rpm for 40 seconds, with the film thickness controlled at 45 μm.

[0107] Crosslinking treatment is performed by heating the membrane to 55°C and holding it at that temperature for 1 hour to complete the crosslinking process.

[0108] Heat treatment was performed, in which the membrane was treated at 100°C for 3 hours to remove the solvent and enhance the membrane structure.

[0109] Comparative Example 1: Comparison without added graphene

[0110] Group allocation ratio:

[0111] Perfluorosulfonic acid resin: 45%

[0112] CeO2 nanoparticles: 6%

[0113] TiO2 nanoparticles: 6%

[0114] Quantum dots (copper-based quantum dots): 0.5%

[0115] Graphene (GO): 0%

[0116] Ionic liquid (1-ethyl-3-methylimidazolium sulfonate): 3%

[0117] Polyvinyl alcohol (PVA): 2%

[0118] Specific steps:

[0119] Dissolve 45% of the perfluorosulfonic acid resin in an appropriate amount of DMF and stir until completely dissolved to form a homogeneous solution.

[0120] Dissolve 6% CeO2 and 6% TiO2 nanoparticles in deionized water and sonicate for 30 minutes to ensure full dispersion of the particles.

[0121] Add 0.5% copper-based quantum dots and 3% ionic liquid to the above solution, and continue stirring for 30 minutes to ensure that the components are evenly dispersed.

[0122] Add 2% polyvinyl alcohol (PVA) solution and stir until homogeneous to form a composite slurry.

[0123] The composite slurry was coated onto the substrate using a spin coating method at a speed of 2000 rpm and a spin coating time of 45 s, with the film thickness controlled at around 50 μm.

[0124] The coated film was subjected to cross-linking treatment at a temperature of 55°C for 1 hour to complete the cross-linking process.

[0125] Heat treatment: The membrane was heat-treated at 80°C for 2 hours to remove the solvent and further enhance the stability of the membrane.

[0126] Comparative Example 2: Comparison of Uncrosslinked Treatment

[0127] Group allocation ratio:

[0128] Perfluorosulfonic acid resin: 50%

[0129] CeO2 nanoparticles: 7%

[0130] TiO2 nanoparticles: 4%

[0131] Quantum dots (copper-based quantum dots): 0.3%

[0132] Graphene (GO): 4%

[0133] Ionic liquid (1-ethyl-3-methylimidazolium sulfonate): 2.5%

[0134] Polyvinyl alcohol (PVA): 0% (no PVA crosslinking used)

[0135] Specific steps:

[0136] Dissolve 50% of the perfluorosulfonic acid resin in DMF, using magnetic stirring, and maintain the temperature at 60°C until completely dissolved.

[0137] 7% CeO2 and 4% TiO2 nanoparticles were dispersed in deionized water and treated with ultrasound for 40 minutes to ensure uniform dispersion of the nanoparticles.

[0138] Add 0.3% copper-based quantum dots, 4% graphene, and 2.5% ionic liquid to the above solution, and continue stirring for 40 minutes to ensure uniform distribution of the components.

[0139] The solution was coated onto the substrate by spin coating at a speed of 2500 rpm for 40 s, and the film thickness was controlled at 40 μm.

[0140] Without cross-linking, the membrane is directly subjected to heat treatment.

[0141] Heat treatment: The membrane is heat-treated at 120°C for 3 hours to remove residual solvent and enhance membrane stability.

[0142] Comparative Example 3: Comparison without the use of ionic liquids

[0143] Group allocation ratio:

[0144] Perfluorosulfonic acid resin: 50%

[0145] CeO2 nanoparticles: 7%

[0146] TiO2 nanoparticles: 4%

[0147] Quantum dots (copper-based quantum dots): 0.3%

[0148] Graphene (GO): 4%

[0149] Ionic liquid (1-ethyl-3-methylimidazolium sulfonate): 0%

[0150] Polyvinyl alcohol (PVA): 2.5%

[0151] Specific steps:

[0152] Dissolve 50% of the perfluorosulfonic acid resin in DMF, using magnetic stirring, and maintain the temperature at 60°C until completely dissolved.

[0153] 7% CeO2 and 4% TiO2 nanoparticles were dispersed in deionized water and treated with ultrasound for 40 minutes to ensure uniform dispersion of the nanoparticles.

[0154] Add 0.3% copper-based quantum dots and 4% graphene to the above solution, and continue stirring for 40 minutes to ensure uniform distribution of the components.

[0155] Add 2.5% polyvinyl alcohol solution and stir until homogeneous to form a composite slurry.

[0156] The slurry was coated onto the substrate by spin coating at a speed of 2500 rpm for 40 seconds, and the film thickness was controlled at 40 μm.

[0157] To perform cross-linking treatment, heat the membrane to 60°C and maintain for 1 hour to ensure complete PVA cross-linking.

[0158] Heat treatment: The membrane is treated at 120℃ for 3 hours to remove the solvent and enhance the stability of the membrane.

[0159] Comparative Example 4: Comparison of a small number of quantum dots

[0160] Group allocation ratio:

[0161] Perfluorosulfonic acid resin: 50%

[0162] CeO2 nanoparticles: 6%

[0163] TiO2 nanoparticles: 6%

[0164] Quantum dots (copper-based quantum dots): 0.1%

[0165] Graphene (GO): 4%

[0166] Ionic liquid (1-ethyl-3-methylimidazolium sulfonate): 3%

[0167] Polyvinyl alcohol (PVA): 2%

[0168] Specific steps:

[0169] Dissolve 50% of the perfluorosulfonic acid resin in DMF, using magnetic stirring, and maintain the temperature at 60°C until completely dissolved.

[0170] 6% CeO2 and 6% TiO2 nanoparticles were dissolved in deionized water and treated with ultrasound for 40 minutes to ensure full dispersion of the particles.

[0171] Add 0.1% copper-based quantum dots, 4% graphene, and 3% ionic liquid to the above solution, and continue stirring for 40 minutes to ensure that the components are evenly dispersed.

[0172] Add 2% polyvinyl alcohol (PVA) solution and stir until homogeneous to form a composite slurry.

[0173] The composite slurry was coated onto the substrate using a spin coating method at a speed of 2000 rpm and a spin coating time of 45 s, with the film thickness controlled at 50 μm.

[0174] The coated film was subjected to cross-linking treatment at a temperature of 55°C for 1 hour to complete the cross-linking process.

[0175] Heat treatment: The membrane was heat-treated at 80°C for 2 hours to remove the solvent and further enhance the stability of the membrane.

[0176] Experiment 1: Proton Conductivity Test Experiment

[0177] Sample preparation:

[0178] Example 1: Dissolve 45% perfluorosulfonic acid resin in an appropriate amount of DMF and stir until completely dissolved to form a homogeneous solution.

[0179] Comparative Example 1: 45% perfluorosulfonic acid resin was dissolved in the same DMF solvent, and 0% graphene (GO) was added. The remaining components (CeO2, TiO2, quantum dots, ionic liquid, PVA) were the same as in the example.

[0180] Add 6% CeO2 and 6% TiO2 nanoparticles to the above solution respectively. Dissolve the 6% CeO2 and TiO2 nanoparticles in deionized water and sonicate for 30 min to ensure uniform dispersion.

[0181] Add 0.5% copper-based quantum dots to the solution and stir for 1 hour to ensure uniform dispersion.

[0182] Add 3% graphene and continue stirring for 30 minutes. Then add 3% ionic liquid and continue stirring for 30 minutes.

[0183] Add 2% polyvinyl alcohol (PVA) solution to the mixed solution and stir until homogeneous to form a composite slurry.

[0184] Membrane preparation:

[0185] The composite slurry was applied to a glass substrate using a spin coating method. The coating speed was 2000 rpm, the spin coating time was 45 s, and the film thickness was controlled at 50 μm.

[0186] The coated film is heated to 55°C and held for 1 hour for crosslinking treatment.

[0187] Heat treatment process: The membrane is heat-treated at 80°C for 2 hours to remove solvent and enhance membrane stability.

[0188] Proton conductivity test:

[0189] The proton conductivity of the membrane was measured using electrochemical impedance spectroscopy (EIS) at frequencies ranging from 10 mHz to 1 MHz and at temperatures of 60 °C, 80 °C, and 100 °C.

[0190] Different humidity environments were set at each test temperature: 30%, 60%, and 90% RH. Tests were conducted for 30 minutes at each humidity level for 24 hours to ensure stable conductivity data.

[0191] Data Analysis:

[0192] The conductivity differences between Example 1 and Comparative Example 1 under different humidity and temperature conditions were compared to analyze the effect of graphene on the proton conductivity of the film.

[0193]

[0194] Table Title: Comparison of Proton Conductivity under Different Humidity and Temperature Conditions

[0195] Summarize;

[0196] Experimental results show that Example 1 exhibits significantly higher proton conductivity under all test conditions. Particularly under high humidity and high temperature environments, the graphene-added example demonstrates a significant improvement in conductivity compared to Comparative Example 1. The introduction of graphene provides more proton transport channels by increasing the specific surface area and electronic conduction pathways of the film. Based on mechanistic analysis, graphene can form a network structure with CeO2 and TiO2 particles, enhancing the conductivity and stability of the film. This enhancement of conduction pathways is particularly significant at high humidity levels, as water acts as a proton carrier in the film, and graphene helps maintain efficient water transfer.

[0197] Ionic liquids enhance proton conductivity by binding with the sulfonic acid groups of the perfluorosulfonic acid resin matrix, thereby adjusting the polarity and hydrophilicity of the membrane. However, in Comparative Example 1, which does not contain graphene, the conductivity is still lower than that of Example 1, especially in low humidity environments where the improvement in proton conductivity is relatively small.

[0198] Experiment 2: Mechanical Strength Test of Membrane Materials

[0199] Sample preparation:

[0200] Example 2: A proton exchange membrane was prepared according to the following composition ratio (50% perfluorosulfonic acid resin, 7% CeO2, 4% TiO2, 0.3% quantum dots, 4% graphene, 2.5% ionic liquid, and 2.2% PVA).

[0201] Comparative Example 2: Proton exchange membranes were prepared according to the following composition ratio (50% perfluorosulfonic acid resin, 7% CeO2, 4% TiO2, 0.3% quantum dots, 4% graphene, 2.5% ionic liquid, and 0% PVA).

[0202] All solutions were prepared according to the previous steps. CeO2 and TiO2 nanoparticles were dissolved and ultrasonically treated for 30 min to ensure uniform dispersion of the particles.

[0203] Membrane preparation:

[0204] The composite slurry was coated onto a glass substrate by spin coating at a speed of 2500 rpm for 40 seconds, with the film thickness controlled at 40 μm.

[0205] The coated film is heated to 60°C for cross-linking treatment and kept for 1 hour.

[0206] Heat treatment process: The membrane is treated at 120°C for 3 hours to remove solvent and enhance membrane stability.

[0207] Mechanical strength test:

[0208] Tensile strength tests were performed using a universal testing machine. The test sample dimensions were 20 mm wide and 100 mm long.

[0209] The test speed was set to 2 mm / min until the membrane broke.

[0210] The tensile strength, elongation at break, and Young's modulus of the sample were measured.

[0211] Experimental setup:

[0212] The sample was tested five times, and the average value was taken.

[0213] Test temperature: room temperature (25℃), keep dry.

[0214] Data Analysis:

[0215] The tensile strength, elongation at break, and Young's modulus of Example 2 and Comparative Example 2 were compared. The effect of crosslinking treatment on the mechanical strength of the membrane was analyzed.

[0216]

[0217] Table Title: Comparison of Mechanical Properties of Different Membrane Materials

[0218] Summarize;

[0219] The membrane material of Example 2 significantly outperforms Comparative Example 2 in mechanical properties such as tensile strength, elongation at break, and Young's modulus. By introducing polyvinyl alcohol (PVA) for crosslinking, the membrane of Example 2 exhibits higher tensile strength and better ductility. This result indicates that the crosslinking process strengthens the overall structure of the membrane, enabling it to maintain excellent mechanical properties even at high temperatures. In contrast, the uncrosslinked membrane of Comparative Example 2 has significantly lower mechanical strength and is prone to premature fracture during stretching.

[0220] The cross-linking effect of PVA also has a positive impact on the membrane's microstructure, further enhancing its adaptability to the external environment. Through this cross-linking process, the mechanical strength of the membrane is significantly improved, especially exhibiting stronger ductility under tension.

[0221] Experiment 3: Membrane Material Stability Test

[0222] Sample preparation:

[0223] Example 3: Proton exchange membranes were prepared according to the following composition ratio (55% perfluorosulfonic acid resin, 8% CeO2, 5% TiO2, 0.5% quantum dots, 2.5% graphene, 4% ionic liquid, and 1.5% PVA).

[0224] Comparative Example 3: Proton exchange membranes were prepared according to the following composition ratios (55% perfluorosulfonic acid resin, 8% CeO2, 5% TiO2, 0.5% quantum dots, 2.5% graphene, 0% ionic liquid, and 1.5% PVA).

[0225] All solutions were prepared according to the previous steps. CeO2 and TiO2 nanoparticles were dissolved and sonicated for 35 min to ensure uniform dispersion.

[0226] Membrane preparation:

[0227] The composite slurry was coated onto a glass substrate by spin coating at a speed of 1500 rpm for 50 seconds, with the film thickness controlled at 60 μm.

[0228] The coated film is heated to 60°C and kept at that temperature for 1 hour for crosslinking treatment.

[0229] Heat treatment process: The membrane was treated at 120℃ for 3 hours to remove solvent and enhance membrane stability. Thermal stability test:

[0230] Thermogravimetric analysis (TGA) was used to test the thermal weight loss of the membrane. The test temperature range was 30℃-500℃, the heating rate was 10℃ / min, and the mass change of the membrane at different temperatures was recorded.

[0231] The mass loss of the sample at high temperature was measured to analyze the thermal stability of the membrane material.

[0232] Accelerated aging test:

[0233] The membrane was subjected to accelerated aging testing for 72 hours at 80°C and 90% relative humidity. The proton conductivity and mechanical strength of the membrane were periodically tested.

[0234] The proton conductivity of the membrane under high temperature and high humidity conditions was measured using the electrochemical impedance spectroscopy (EIS) method, with a test frequency range of 10 mHz to 1 MHz.

[0235] The conductivity and mechanical properties of the membrane were tested every 12 hours, and the data were recorded.

[0236] Data Analysis:

[0237] By comparing the changes in thermal stability, proton conductivity, and mechanical properties between Example 3 and Comparative Example 3, the role of ionic liquids in membrane stability is analyzed.

[0238]

[0239] Table Title: Comparison of Thermal Stability and Proton Conductivity of Different Membrane Materials

[0240] Summarize;

[0241] The experimental results clearly demonstrate the differences between Example 3 and Comparative Example 3. By introducing an ionic liquid, Example 3 exhibited a significant advantage in stability under high temperature and high humidity conditions. After 72 hours of accelerated aging testing, the membrane of Example 3 maintained high proton conductivity and minimal mass loss, while Comparative Example 3 performed poorly under the same conditions, showing a significant decrease in proton conductivity and substantial mass loss. This indicates that the ionic liquid not only improves the conductivity of the membrane but also effectively enhances its thermal stability and long-term durability.

[0242] Ionic liquids enhance the hydrophilicity and proton conductivity of the membrane by forming hydrogen bonds with the sulfonic acid groups of Nafion. The addition of ionic liquids allows water molecules to exist more stably within the membrane, which is crucial for proton conductivity under high humidity conditions. Simultaneously, ionic liquids further improve the proton conductivity of the membrane by adjusting its polarity. In contrast, Comparative Example 3, without added ionic liquids, suffers from poor hydrophilicity, leading to obstructed water and proton conduction pathways under high humidity conditions, ultimately affecting its stability and conductivity.

[0243] Experiment 4: Proton Conduction Path Analysis Experiment

[0244] Sample preparation:

[0245] Example 4: A proton exchange membrane was prepared according to the composition ratio (Nafion 60%, CeO 25%, TiO 25%, quantum dot 0.3%, graphene 3%, ionic liquid 2%, PVA 2%).

[0246] Comparative Example 4: Proton exchange membranes were prepared according to the composition ratio (Nafion 60%, CeO 25%, TiO 25%, quantum dots 0.1%, graphene 3%, ionic liquid 2%, PVA 2%).

[0247] All solutions were prepared according to the steps described above. CeO2 and TiO2 nanoparticles were dissolved and ultrasonically treated for 40 min to ensure uniform particle dispersion.

[0248] Membrane preparation:

[0249] The composite slurry was coated onto a glass substrate by spin coating at a speed of 1800 rpm for 40 seconds, with the film thickness controlled at 45 μm.

[0250] The coated film was crosslinked at 60°C for 1 hour.

[0251] Heat treatment process: The membrane is treated at 100℃ for 3 hours to remove solvent and enhance membrane stability.

[0252] Proton conduction pathway analysis:

[0253] Scanning electron microscopy (SEM): Observes the microstructure of the membrane and the proton conduction pathway, with a focus on analyzing the distribution of quantum dots and graphene in the membrane.

[0254] Transmission electron microscopy (TEM): Further analysis of the distribution of quantum dots and nanoparticles and their impact on proton conduction pathways, especially the nanochannel structures they form within the film.

[0255] Proton mobility test: The proton mobility of the membrane is measured by the ion mobility method. The proton conduction ability of the membrane is evaluated by the change in conductivity and the current-voltage relationship.

[0256] Experimental setup:

[0257] The samples were tested three times to ensure the reliability of the data.

[0258] During the preparation of SEM and TEM samples, the membrane cross-section is cryo-cut to obtain clear images of the microstructure.

[0259] The proton mobility test was conducted at room temperature using a 100Hz AC voltage.

[0260] Data Analysis:

[0261] By comparing the differences between Example 4 and Comparative Example 4 in terms of proton mobility and conduction path structure, the optimization effect of quantum dot content on proton conductivity was analyzed.

[0262]

[0263] Table Title: Proton Mobility and Microstructure Analysis of Different Membrane Materials

[0264] Summarize;

[0265] The proton mobility in Example 4 was significantly higher than that in Comparative Example 4, indicating that the addition of quantum dots has a positive effect on improving the proton conductivity of the film. SEM and TEM images further confirmed this. In Example 4, the quantum dots in the film were uniformly distributed, forming a more regular nanochannel structure, which provided an ideal path for the smooth migration of protons. In contrast, in Comparative Example 4, the quantum dots were unevenly distributed and lacked continuous proton conduction channels, which led to a significant decrease in the proton conductivity of the film.

[0266] Quantum dots, through their unique electron and proton migration properties, form an effective proton conduction network within the film. Simultaneously, graphene, acting as a carrier, facilitates the uniform distribution of quantum dots within the film, preventing aggregation and further enhancing the film's conductivity. In contrast, a smaller number of quantum dots and an uneven distribution, as seen in Comparative Example 4, fail to effectively promote proton conduction, resulting in lower proton mobility and conductivity. Quantum dots improve the proton conduction pathway, while graphene provides the electron conduction pathway; the combination of these two significantly improves the overall performance of the film.

[0267] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. An inorganically doped proton exchange membrane, characterized in that, By weight percentage, it includes the following components; The composition includes: 40-60% perfluorosulfonic acid resin (Nafion), 5-10% CeO2 nanoparticles, 5-10% TiO2 nanoparticles, 0.1-1% quantum dots, 1-5% graphene (GO), 2-5% ionic liquid, and 1-2% polyvinyl alcohol (PVA).

2. The inorganic doped proton exchange membrane according to claim 1, characterized in that, The surface modification method of the CeO2 nanoparticles can enrich their surface with a large number of -OH and -SO3H groups.

3. The inorganic doped proton exchange membrane according to claim 1, characterized in that, The quantum dots are copper-based quantum dots, prepared by chemical vapor deposition.

4. The inorganic doped proton exchange membrane according to claim 1, characterized in that, The ionic liquid is 1-ethyl-3-methylimidazolium sulfonate.

5. A method for preparing an inorganically doped proton exchange membrane, comprising the inorganically doped proton exchange membrane according to claims 1-4, characterized in that, Includes the following steps; S1. Dissolve perfluorosulfonic acid resin in an appropriate amount of N,N-dimethylformamide (DMF) to form a perfluorosulfonic acid resin solution; S2. Dissolve CeO2 nanoparticles and TiO2 nanoparticles in deionized water or organic solvent respectively, and then disperse them uniformly by ultrasonic treatment. S3. Add quantum dots, graphene, ionic liquid and polyvinyl alcohol to the solution and stir evenly to form a composite slurry; S4. The above composite slurry is coated onto the substrate using a spin coating method to form a uniform film layer with a film thickness controlled between 30-100 μm. S5. Perform cross-linking treatment by adding polyvinyl alcohol (PVA) solution and heating at 50-60℃ for 1 hour to complete the cross-linking reaction; S6. Perform heat treatment at a temperature range of 80-120℃ for 2-4 hours to complete the membrane preparation.

6. The method for preparing an inorganically doped proton exchange membrane according to claim 5, characterized in that, In step S2, the oxidation treatment of CeO2 nanoparticles is carried out by using a mixed solution of sulfuric acid (H2SO4) with a concentration of 1M and hydrogen peroxide (H2O2). The concentration of hydrogen peroxide is 0.3-3%, which enriches the CeO2 nanoparticles with -OH and -SO3H groups. The volume ratio of the mixed solution is 1:

3.

7. The method for preparing an inorganically doped proton exchange membrane according to claim 5, characterized in that, In step S4, the coating speed of the spin coating method is 1000-3000 rpm, and the spin coating time is 30-60 s.

8. The method for preparing an inorganically doped proton exchange membrane according to claim 5, characterized in that, In step S2, the ultrasonic treatment time is 30-45 minutes and the frequency is 20-25 kHz.

9. The method for preparing an inorganically doped proton exchange membrane according to claim 5, characterized in that, In step S2, the crosslinking treatment uses a polyvinyl alcohol (PVA) solution with a concentration of 1-2%, and is heated at 50-60°C for 1 hour.

10. The method for preparing an inorganically doped proton exchange membrane according to claim 5, characterized in that, The heating rate in step S2 is 2℃ / min, and the temperature is maintained for 2-4 hours during the heat treatment process.

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