Preparation method and application of defect engineering modified MOFs composite perfluorosulfonic acid proton exchange membrane

Abstract

The invention discloses a preparation method and application of a defect engineering modified MOFs composite perfluorosulfonic acid proton exchange membrane. According to the composite proton exchange membrane prepared from the perfluorinated sulfonic acid resin and the defect disulfonic acid group MOFs synthesized through microwave assistance, high conductivity and good stability of the proton exchange membrane are achieved in a simple and efficient mode. Microwave radiation has strong energy, the reaction speed can be increased, part of metal clusters are not coordinated with ligands in time, and rich defects are generated in MOFs. The MOFs with proper structure defects can increase the pore volume, form special sites for promoting proton conduction, and form a hydrogen bond network by adsorbing water molecules or functional groups, so that the proton transmission efficiency is remarkably improved. Meanwhile, the sulfonate group also provides a proton source for proton conduction and constructs a hydrogen bond channel for adsorbing water molecules. The MOFs nanofiller and the perfluorosulfonic acid polymer have good compatibility, and good mechanical performance, thermal stability and proton stability of the composite membrane are ensured.

Description

Technical Field

[0001] The present invention belongs to the technical field of hydrogen preparation, and in particular relates to a preparation method and application of a defect-engineered modified MOFs composite perfluorosulfonic acid proton exchange membrane. Background Art

[0002] With the continuous advancement of science and technology and the continued growth of the global population, the contradictions between environmental pollution, energy crises, and economic development are becoming increasingly severe, and the sustainable development challenges facing human society are becoming increasingly severe. International energy experts predict that global energy consumption will at least double in the next few years. To effectively prevent further energy shortages and even depletion, the research and development of clean, efficient, and renewable energy sources that can maintain the sustainable development of society's resources will become a major challenge. The excellent electrochemical and thermal stability of perfluoroproton membranes have led to their widespread application in membrane electrode materials, electrosorption desalination, diaphragm materials in the chlor-alkali industry, and core materials for water electrolysis hydrogen production devices. The 21st century is increasingly being considered the century of hydrogen energy. Research on the application of perfluorosulfonic acid proton membranes in water electrolysis hydrogen production technology will also play a positive role in promoting the development and utilization of hydrogen energy.

[0003] Water electrolysis is an important technology for converting electrical energy into chemical energy. Hydrogen production technologies can be categorized into three types: alkaline water electrolysis (AWE), proton exchange membrane electrolysis (PEMWE), and high-temperature solid oxide electrolysis (SOEC). PEMWE has attracted attention due to its advantages, including high electrolysis current density, electrochemical compression during operation, minimal gas crossover, and adaptability to power supply fluctuations. However, the commercial proton exchange membrane used in PEMWE is mostly DuPont's Nafion series perfluorosulfonic acid membrane. Nafion membranes also have a certain gas permeability, which is particularly pronounced at high temperatures, high water content, and low current density. Furthermore, the membrane's relatively high price has limited its application in various fields.

[0004] Current research on proton exchange membranes in PEMWEs focuses on improving the membrane's proton conductivity and thus increasing the energy efficiency of electrolysis. Furthermore, it aims to enhance the membrane's stability, extend its service life, and reduce gas crossover. While improving proton exchange capacity while maintaining membrane stability as much as possible, developing membranes that meet these application requirements presents numerous challenges.

[0005] Therefore, there is an urgent need for a new composite proton exchange membrane for water electrolysis to solve the above technical problems. Summary of the Invention

[0006] In order to solve the above technical problems, the present invention provides a defect-engineered modified MOFs composite perfluorosulfonic acid proton exchange membrane and a preparation method thereof.

[0007] The method for preparing the defect-engineered modified MOFs composite perfluorosulfonic acid proton exchange membrane provided by the present invention comprises the following steps: (1) Synthesis of defective UIO-66(SH)2: a ligand, a zirconium source, an acid regulator, and an organic solvent are mixed to obtain a reaction solution; the reaction solution is placed in a microwave reactor for reaction, and after the reaction is completed, the reaction solution is centrifuged, washed, and dried to obtain defective UIO-66(SH)2; (2) Modification of defective UIO-66(SH)2: The defective UIO-66(SH)2 powder was added to a hydrogen peroxide solution and stirred for reaction. The solid was collected by centrifugation and then added to a dilute sulfuric acid solution for immersion. After a second centrifugal washing, the defective UIO-66(SO3H)2 yellow solid (defective MOFs with disulfonic acid groups) was obtained by drying. (3) Preparation of composite proton exchange membrane: The defective UIO-66(SO3H)2 powder is added to a perfluorosulfonic acid resin dispersion, ultrasonicated and stirred evenly, the mixed solution is poured into a membrane mold, the mixed solvent is heated and dried, and the membrane is subjected to high-temperature annealing treatment to obtain the defect-engineered modified MOFs composite perfluorosulfonic acid proton exchange membrane.

[0008] Preferably, in step (1) of the above method, the ligand is first added to an organic solvent, and then the ligand solution and the organic solution of the zirconium source and the acid regulator are stirred evenly to obtain a reaction solution.

[0009] Preferably, in step (1) of the above method, the ligand is p-mercaptoterephthalic acid (H2DMBDC).

[0010] Preferably, in step (1) of the above method, the zirconium source is one or more of zirconium tetrachloride, zirconium nitrate, and zirconium oxychloride.

[0011] Preferably, in step (1) of the above method, the regulator is one or more of acetic acid, nitric acid, hydrochloric acid, citric acid, formic acid, and benzoic acid.

[0012] Preferably, in step (1) of the above method, the organic solvent is N,N-dimethylformamide (DMF).

[0013] Preferably, in step (1) of the above method, in the reaction solution, the concentration of the ligand is 0.03-0.1 mol / L, the concentration of the zirconium source is 0.03-0.1 mol / L, and the concentration adjusted by the acid is 10-15 mol / L.

[0014] Preferably, in step (1) of the above method, the mixing is carried out under stirring conditions, the stirring speed is 500-1000 rpm, and the stirring time is 2-4 h.

[0015] Preferably, in step (1) of the above method, the power of the microwave reactor is 100-200 W, the temperature of the microwave reaction is 100-150° C., and the time of the microwave reaction is 30-60 min.

[0016] Preferably, in step (1) of the above method, the solvents used for washing are DMF and dichloromethane, respectively. Preferably, in step (2) of the above method, the mass fraction of the hydrogen peroxide solution is 20-50%.

[0017] Preferably, in step (2) of the above method, the mass ratio of the defective UIO-66(SH)2 to the hydrogen peroxide solution is 1:100-1:200.

[0018] Preferably, in step (2) of the above method, the reaction temperature of the stirring reaction is 20-40° C., and the reaction time is 1-3 h. Preferably, in step (2) of the above method, the concentration of the dilute sulfuric acid solution is 0.01-0.05 mol / L, and the mass ratio of the solid to the dilute sulfuric acid solution is 1:200-1:100.

[0019] Preferably, in step (2) of the above method, the stirring time in the dilute sulfuric acid solution is 30-60 min.

[0020] Preferably, in step (2) of the above method, the solvent used in the second centrifugal washing is water.

[0021] Preferably, in step (3) of the above method, the content of MOFs is 1-10 wt% of the proton exchange membrane.

[0022] Preferably, in step (3) of the above method, the mass ratio of the MOFs powder to the perfluorosulfonic acid resin in the perfluorosulfonic acid resin dispersion is 1:(10-200).

[0023] Preferably, in step (3) of the above method, the solvent of the perfluorosulfonic acid resin dispersion is an ethanol solution, the mass fraction of the ethanol solution is 40-60 wt %, and the mass fraction of the perfluorosulfonic acid resin in the perfluorosulfonic acid resin dispersion is 5-20 wt %.

[0024] Preferably, in step (3) of the above method, the ultrasonication time may be 5-30 min, and the stirring time may be 12-24 h.

[0025] Preferably, in step (3) of the above method, the drying temperature is 70-90°C and the drying time is 6-10 h.

[0026] Preferably, in step (3) of the above method, the annealing temperature is 130-150° C., and the annealing time is 2-6 h.

[0027] Preferably, in step (3) of the above method, the thickness of the modified composite proton exchange membrane is 80-120 μm.

[0028] The defect engineering modified MOFs composite perfluorosulfonic acid proton exchange membrane prepared by the above method also falls within the protection scope of the present invention.

[0029] The present invention also provides the use of the defect-engineered modified MOFs composite perfluorosulfonic acid proton exchange membrane in hydrogen production by water electrolysis.

[0030] The defect-engineered MOFs composite perfluorosulfonic acid proton exchange membrane uses zirconium chloride as a zirconium source, which is dissolved in a DMF solvent with the ligand para-mercaptoterephthalic acid. Acetic acid is then added to synthesize MOFs with abundant defective structural channels under microwave assistance. Oxidation and acidification are then performed to synthesize defective MOFs with disulfonic acid groups. The synthesized MOFs are then mixed with a perfluorosulfonic acid resin dispersion and dried and annealed at high temperature to obtain a composite proton exchange membrane. The disulfonic acid-defective MOFs synthesized through defect engineering exhibit strong hydrophilicity and low swelling rate, improving the proton conductivity of the proton exchange membrane in high-temperature, low-humidity environments. The MOF nanofillers also exhibit good compatibility with the perfluorosulfonic acid polymer, enhancing the membrane's compactness and mechanical properties while reducing the membrane's hydrogen permeability to a certain extent.

[0031] Compared with the prior art, the present invention has the following beneficial technical effects: 1. The present invention uses a composite proton exchange membrane prepared by combining perfluorosulfonic acid resin and microwave-assisted synthesis of defective disulfonic acid group MOFs, which achieves high conductivity and good stability of the proton exchange membrane in a simple and efficient manner.

[0032] 2. Microwave radiation has strong energy, which can accelerate the reaction rate. Some metal clusters fail to coordinate with ligands in time, thus generating abundant defects in MOFs.

[0033] 3. MOFs with appropriate structural defects can increase pore volume and form specific sites that promote proton conduction. By adsorbing water molecules or functional groups, they form hydrogen bond networks, significantly improving proton transfer efficiency. Furthermore, the presence of sulfonate groups provides a proton source for proton conduction and creates hydrogen bond channels for adsorbed water molecules.

[0034] 4. MOFs nanofillers have good compatibility with perfluorosulfonic acid polymers, ensuring good mechanical properties of the composite membrane and reducing the hydrogen permeability of the membrane to a certain extent.

[0035] 5. The method of the present invention is simple and efficient, has low energy consumption and low cost, and is widely applicable to the field of hydrogen production by proton exchange membrane water electrolysis. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 1 is a graph showing the electrolytic cell current density-voltage curves when the composite proton exchange membrane prepared in Example 1 and the commercial Nafion 115 membrane are used in PEMWE.

[0037] Figure 2 1 is a graph showing electrolytic cell current density-electrolysis efficiency when the composite proton exchange membrane prepared in Example 1 and the commercial Nafion 115 membrane are used in PEMWE.

[0038] Figure 3 The hydrogen content (volume fraction) in the oxygen at the anode of the electrolyzer at different current densities when the composite proton exchange membrane prepared in Example 1 and the commercial Nafion 115 membrane are used in PEMWE. DETAILED DESCRIPTION

[0039] The present invention will be further described in detail below in conjunction with specific embodiments. The examples provided are only for illustrating the present invention and are not intended to limit the scope of the present invention. The examples provided below can serve as a guide for further improvements by those skilled in the art and are not intended to limit the present invention in any way.

[0040] Unless otherwise specified, the experimental methods in the following examples are conventional methods and were performed according to the techniques or conditions described in the literature in the field or according to the product instructions. The materials and reagents used in the following examples, unless otherwise specified, were all commercially available.

[0041] Example 1 (1) Synthesis of defective UIO-66(SH)2 A solution of H2DMBDC (96 mg, 0.41 mmol) in DMF (8 mL) was added to a solution of ZrCl4 (95 mg, 0.41 mmol) and acetic acid (5.5 mL, 96.0 mmol) in DMF (8 mL). The resulting mixture was stirred at 1000 rpm for 2 hours. The resulting clear, pale yellow solution (2 mL) was irradiated in a microwave reactor (CEM Discover, 100 W, 140 psi) at 120°C for 40 minutes. The resulting solid was collected by centrifugation and washed sequentially with DMF and dichloromethane. The resulting defective UIO-66(SH)2 was obtained as a pale yellow precipitate and dried in air.

[0042] (2) Modification of defective UIO-66(SH)2 Defective UIO-66(SH)2 (0.2 g) was oxidized with a 30% (mass fraction) H2O2 solution (20 mL). The solid suspension was stirred at room temperature for 1 hour. The resulting solid was collected by centrifugation and soaked in a 0.02 M H2SO4 solution (20 mL) for 30 minutes to completely acidify the sulfonate groups. The resulting solid was collected by centrifugation and washed thoroughly with water several times until the supernatant was neutral. A pale yellow precipitate of UIO-66(SO3H)2 (defective MOFs with bissulfonic acid groups) was obtained and dried in an oven.

[0043] (3) Preparation of composite proton exchange membrane 2 wt% (1.5 mg) of MOFs were weighed and added to 15 mL of a 5% perfluorosulfonic acid resin dispersion (the solvent was a 50 wt% ethanol-water solution). The dispersion was ultrasonically treated for 15 minutes, stirred for 12 hours, and then cast onto a glass mold. After evaporating the solvent at 80°C for 8 hours, the membrane was annealed at 140°C for 4 hours to produce a defective MOF composite proton exchange membrane.

[0044] Example 2 (1) Synthesis of defective UIO-66(SH)2 A solution of H2DMBDC (94 mg, 0.40 mol) in DMF (9 mL) was added to a solution of ZrCl4 (97 mg, 0.42 mol) and acetic acid (5.8 mL, 96.2 mmol) in DMF (9 mL). The resulting mixture was stirred at 900 rpm for 2 hours. The resulting solution (2 mL) was irradiated in a microwave reactor (CEM Discover, 100 W, 140 psi) at 130°C for 50 minutes. The resulting solid was collected by centrifugation and washed sequentially with DMF and dichloromethane to obtain a light yellow precipitate of defective UIO-66(SH)2, which was then air-dried.

[0045] (2) Modification of defective UIO-66(SH)2 Defective UIO-66(SH)2 (0.2 g) was oxidized with a 30% (mass fraction) H2O2 solution (20 mL). The solid suspension was stirred at room temperature for 1 hour. The resulting solid was collected by centrifugation and soaked in a 0.02 M H2SO4 solution (20 mL) for 30 minutes. The resulting solid was collected by centrifugation and washed thoroughly with water several times until the supernatant was neutral. A pale yellow precipitate of UIO-66(SO3H)2 (defective MOFs with bissulfonic acid groups) was obtained and dried in an oven.

[0046] (3) Preparation of composite proton exchange membrane 4 wt% MOFs (2.8 mg) were weighed and added to 14 ml of a 5% perfluorosulfonic acid resin dispersion (solvent: 50 wt% ethanol in water). The dispersion was ultrasonically treated for 15 minutes, stirred for 12 hours, and then cast onto a glass mold. After evaporating the solvent at 70°C for 8 hours, the resulting composite proton exchange membrane was annealed at 130°C for 4 hours to form a defective MOF composite.

[0047] Example 3 (1) Synthesis of defective UIO-66(SH)2 A solution of H2DMBDC (98 mg, 0.42 mol) in DMF (7 mL) was added to a solution of ZrCl4 (94 mg, 0.40 mol) and acetic acid (5.3 mL, 92.7 mmol) in DMF (7 mL). The resulting mixture was stirred at 100 rpm for 2 hours. The solution (2 mL) was then irradiated in a microwave reactor (CEM Discover, 100 W, 140 psi) at 110°C for 35 minutes. The solid was collected by centrifugation and washed sequentially with DMF and dichloromethane to obtain a light yellow precipitate of defective UIO-66(SH)2, which was then air-dried.

[0048] (2) Modification of defective UIO-66(SH)2 Defective UIO-66(SH)2 (0.2 g) was oxidized with a 30% (mass fraction) H2O2 solution (20 mL). The solid suspension was stirred at room temperature for 1 hour. The solid was collected by centrifugation and soaked in a 0.02 M H2SO4 solution (20 mL) for 30 minutes to completely acidify the sulfonate groups. The resulting solid was collected by centrifugation and washed thoroughly with water several times until the supernatant was neutral. A pale yellow precipitate of UIO-66(SO3H)2 (defective MOFs with bissulfonic acid groups) was obtained and dried in an oven.

[0049] (3) Preparation of composite proton exchange membrane 16 ml of a 5% perfluorosulfonic acid resin dispersion (solvent: 50 wt% ethanol in water) was filled with 1 wt% (0.8 mg) of MOFs. The dispersion was ultrasonically treated for 15 minutes, stirred for 12 hours, and then cast onto a glass mold. After evaporating the solvent at 90°C for 6 hours, the membrane was annealed at 150°C for 3 hours to produce a defective MOF composite proton exchange membrane.

[0050] Comparative Example 1 A solution of H2DMBDC (96 mg) in DMF (8 mL) was added to a solution of ZrCl4 (96 mg) and acetic acid (5.6 mL) in DMF (8 mL) and stirred for 2 hours. The solution (2 mL) was poured into an autoclave and heated at 120°C for 12 hours. The solid was collected by centrifugation, washed with DMF and dichloromethane, and dried in air to yield UIO-66(SH)2.

[0051] UIO-66(SH)2 (0.2 g) was oxidized with a 30% H2O2 solution (20 mL). The solid suspension was stirred at room temperature for 1 hour. The solid was collected by centrifugation and soaked in a 0.02 M H2SO4 solution (20 mL) for 30 minutes. The solid was collected by centrifugation, washed thoroughly with water several times, and dried in an oven.

[0052] 2 wt% (1.5 g) of MOFs were weighed and added to 15 ml of a 5% perfluorosulfonic acid resin dispersion (the solvent was a 50 wt% ethanol-water solution). The dispersion was ultrasonically treated for 15 minutes, stirred for 12 hours, and then cast onto a glass mold. After evaporating the solvent at 80°C for 8 hours, the membrane was annealed at 140°C for 4 hours to obtain a defective MOF composite proton exchange membrane.

[0053] Comparative Example 2 A solution of H2DMBDC (95 mg) in DMF (8 mL) was added to a solution of ZrCl4 (95 mg) and acetic acid (5.5 mL) in DMF (8 mL) and stirred for 2 hours. The solution (2 mL) was irradiated in a microwave reactor at 120°C for 40 minutes. The solid was collected by centrifugation, washed with DMF and dichloromethane, and dried in air. This yielded both unoxidized and acidified MOFs.

[0054] 2 wt% (1.5 g) of MOFs were weighed and added to 15 ml of a 5% perfluorosulfonic acid resin dispersion (the solvent was a 50 wt% ethanol-water solution). The dispersion was ultrasonically treated for 15 minutes, stirred for 12 hours, and then cast onto a glass mold. After evaporating the solvent at 80°C for 7 hours, the membrane was annealed at 145°C for 4 hours to produce a defective MOF composite proton exchange membrane.

[0055] Performance tests were conducted on the composite proton exchange membranes of Examples 1-3 and Comparative Examples 1-2, as well as a membrane commonly used in the market (Nafion 115). The results are shown in Table 1.

[0056] Table 1 Performance test results

[0057] As can be seen from Table 1, the conductivity and water absorption of Examples 1-3 are significantly improved compared to those of Nafion 115 membranes, and the tensile strength is greater than that of Nafion 115, indicating that the defective MOFs blend membrane ensures the stability of the membrane while improving the proton conduction rate. Compared with Example 1, the water absorption of the composite membrane of Example 1 using microwave-assisted synthesis of MOFs is higher than that of the unused comparative example 1, and the swelling rate is relatively low, indicating that the proper introduction of the defective MOFs structure can increase the pore volume and form a hydrogen bond network by adsorbing water molecules to improve the proton transfer efficiency. Compared with Example 1, the conductivity and water absorption of the composite membrane of Example 1 blended with disulfonic acid group MOFs are relatively high in Comparative Example 2, indicating that the introduction of disulfonic acid groups provides a proton source and hopping site for proton conduction and constructs a hydrogen bond channel for adsorbing water molecules.

[0058] Comparative Example 3 Commercially available Nafion 115 perfluorosulfonic acid membrane.

[0059] The membrane prepared in Example 1 was used as the modified composite proton exchange membrane, and Nafion 115 membrane was used as the comparison membrane. A single electrolyzer was assembled for the experiment (the membrane electrode active area was 5 × 5 cm 2 The catalyst loadings were 2 mg at the anode and Ir / cm 2 and cathode 1 mg Pt / cm 2 Titanium felt is used as the gas diffusion layer on both sides, and titanium bipolar plates with 1 mm fluid channels are adopted).

[0060] The test results are as follows Figure 1-2 As shown in the figure: According to the polarization curve, the voltage of the electrolytic cell of the composite membrane of Example 1 is always low, which indicates that its resistance is low. The electrolysis efficiency is further calculated based on the polarization curve. 2When the voltage of the composite membrane electrolytic cell of Example 1 is 2.2 V, the current density reaches 2.0 A / cm 2 , the hydrogen content in the anode oxygen was less than 0.5 vol.%, while when the electrolyzer voltage of Nafion 115 was 2.2 V, the hydrogen content in the anode oxygen was 1.0 vol.%. These results indicate that the use of defective MOFs effectively improves the proton conductivity of the membrane, increases the electrolysis efficiency, and reduces the hydrogen permeability of the membrane to a certain extent.

[0061] From the above, it can be seen that the performance of the composite proton exchange membrane of the present invention is significantly better than that of the prior art.

[0062] The present invention has been described in detail above. It will be apparent to those skilled in the art that the present invention may be practiced over a wide range of parameters, concentrations, and conditions without departing from the spirit and scope of the present invention and without unnecessary experimentation. Although specific embodiments have been given herein, it should be understood that further modifications may be made to the present invention. In summary, this application is intended to encompass any variations, uses, or improvements to the present invention, including those made by conventional techniques known in the art that depart from the scope of the present invention. Applications of the essential features may be made within the scope of the following claims.

Claims

1. A method for preparing a defect-engineered modified MOFs composite perfluorosulfonic acid proton exchange membrane, comprising the following steps: (1) mixing a ligand, a zirconium source, an acid regulator, and an organic solvent to obtain a reaction solution; placing the reaction solution in a microwave reactor for reaction, and centrifuging, washing, and drying after the reaction to obtain defective UIO-66(SH)2; (2) adding the defective UIO-66(SH)2 into a hydrogen peroxide solution and stirring the mixture to react, collecting the solid by centrifugation, and then soaking the collected solid in a dilute sulfuric acid solution. After a second centrifugal washing, the solid was dried to obtain a modified defective UIO-66(SH)2, i.e., defective UIO-66(SO3H)2; (3) Preparation of composite proton exchange membrane: The defective UIO-66(SO3H)2 is added to a perfluorosulfonic acid resin dispersion, ultrasonicated and stirred evenly, the mixed solution is poured into a membrane mold, the solvent is heated and dried, and the membrane is subjected to high-temperature annealing treatment to obtain the defect-engineered modified MOFs composite perfluorosulfonic acid proton exchange membrane.

2. The preparation method according to claim 1, wherein: In the step (1), the ligand is p-mercaptoterephthalic acid; And / or, in step (1), the zirconium source is one or more of zirconium tetrachloride, zirconium nitrate, and zirconium oxychloride; And / or, in step (1), the acid regulator is one or more of acetic acid, nitric acid, hydrochloric acid, citric acid, formic acid, and benzoic acid; And / or, in step (1), the organic solvent is one or more of N,N-dimethylformamide, N,N-diethylformamide, tetrahydrofuran, pyrrolidone, and dimethyl sulfoxide; And / or, in step (1), in the reaction solution, the concentration of the ligand is 0.03-0.1 mol / L, the concentration of the zirconium source is 0.03-0.1 mol / L, and the concentration of the acid regulator is 10-15 mol / L; And / or, in the step (1), the mixing is carried out under stirring conditions, the stirring speed is 500-1000 rpm, and the stirring time is 2-4 h.

3. The preparation method according to claim 1 or 2, characterized in that: In the step (1), the power of the microwave reactor is 100-200 W, the temperature of the microwave reaction is 100-150° C., and the time of the microwave reaction is 30-60 min.

4. The preparation method according to any one of claims 1 to 3, characterized in that: In step (2), the mass fraction of the hydrogen peroxide solution is 20-50%; And / or, in step (2), the mass ratio of the defective UIO-66(SH)2 to the hydrogen peroxide solution is 1:100-1:200; And / or, in the step (2), the reaction temperature of the stirring reaction is 20-40° C., and the reaction time is 1-3 h.

5. The preparation method according to any one of claims 1 to 4, characterized in that: In the step (2), the concentration of the dilute sulfuric acid solution is 0.01-0.05 mol / L, and the mass ratio of the solid to the dilute sulfuric acid solution is 1:200-1:100; And / or, in step (2), the stirring time in the dilute sulfuric acid solution is 30-60 min.

6. The preparation method according to any one of claims 1 to 5, characterized in that: In the step (3), the mass ratio of the defective UIO-66(SO3H)2 to the perfluorosulfonic acid resin in the perfluorosulfonic acid resin dispersion is 1:(10-200); And / or, in step (3), the perfluorosulfonic acid resin dispersion solvent is an ethanol solution, the mass fraction of the ethanol solution is 40-60 wt%, and the mass fraction of the perfluorosulfonic acid resin in the perfluorosulfonic acid resin dispersion is 5-20 wt%; And / or, in the step (3), the ultrasonication time is 5-30 min, and the stirring time is 12-24 h.

7. The preparation method according to any one of claims 1 to 6, characterized in that: In the step (3), the drying temperature is 70-90°C and the drying time is 6-10 h; And / or, in the step (3), the annealing temperature is 130-150° C., and the annealing time is 2-6 h.

8. The defect-engineered modified MOFs composite perfluorosulfonic acid proton exchange membrane prepared by the method according to any one of claims 1 to 7.

9. The proton exchange membrane according to claim 8, characterized in that: The thickness of the defect engineering modified MOFs composite perfluorosulfonic acid proton exchange membrane is 80-120 μm.

10. Use of the defect-engineered modified MOFs composite perfluorosulfonic acid proton exchange membrane according to claim 8 or 9 in the field of hydrogen production by water electrolysis.

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