Modified alkaline electrolytic water hydrogen production diaphragm and preparation method thereof

Abstract

The invention provides a modified alkaline electrolytic water hydrogen production diaphragm and a preparation method thereof. The modified diaphragm comprises a base membrane loaded with a Cu < 2 + > complexed chitosan alkali-resistant ion conduction unit, and the Cu < 2 + > complexed chitosan alkali-resistant ion conduction unit is obtained by loading chitosan through the base membrane and soaking in a Cu < 2 + > complexed solution for complexing. By introducing a copper-chitosan complex structure, a stable ionic conduction channel is constructed in an alkaline environment, and the alkali resistance and ionic conductivity of the membrane are effectively improved. According to the modified alkaline diaphragm for hydrogen production by electrolysis of water, the problems of insufficient alkali resistance, limited ion transmission capability and the like of a diaphragm material in the prior art are solved, and a new solution is provided for preparing the diaphragm for hydrogen production by electrolysis of alkaline water with long service life, high efficiency and low cost.

Description

Technical Field

[0001] The present invention relates to the fields of membrane technology and energy, and particularly to a modified alkaline water electrolysis hydrogen production diaphragm and a preparation method thereof. Background Art

[0002] Alkaline water electrolysis (AWE) is one of the mainstream technologies for industrial hydrogen production due to its low cost, mature process, and suitability for large-scale hydrogen production. In an alkaline water electrolysis system, the diaphragm plays an important role in separating hydrogen and oxygen gases and maintaining the electrolyte circulation, and its performance directly affects the electrolysis efficiency and the long-term stability of the equipment. Alkaline water electrolysis hydrogen production is one of the most mature and commercially advanced electrolysis water hydrogen production technologies, and its core is to decompose water into hydrogen and oxygen through an alkaline electrolyte under the action of direct current. In an alkaline water electrolysis hydrogen production system, the diaphragm plays an important role in separating hydrogen and oxygen gases and maintaining the electrolyte circulation, and its performance directly affects the electrolysis efficiency and the long-term stability of the equipment.

[0003] Traditional asbestos diaphragms have been gradually phased out due to carcinogenicity and easy degradation problems. New composite diaphragms (such as polysulfone and polyphenylene sulfide-based materials) and inorganic-organic composite membranes (such as ZrO2 / PPS) have become research hotspots, aiming to improve ion conductivity, mechanical strength, and corrosion resistance. Currently, the resistance of domestic diaphragms is still generally higher than that of imported diaphragms. The Zirfon membrane represented by Agfa Company in Belgium has a lower resistivity, but its price is several times that of domestic membranes. Based on this, it is of great significance to develop a new type of alkaline water electrolysis hydrogen production diaphragm.

[0004] The existing alkaline water electrolysis hydrogen production diaphragms still have problems such as high cost, insufficient gas interception performance, and difficulty in long-term stable operation in a high-concentration alkaline environment. The materials used in current commercial diaphragms make their cost relatively high and difficult to promote and apply. At the same time, the gas barrier ability of the membrane is limited, which may lead to cross-permeation of hydrogen and oxygen, reducing the electrolysis efficiency and increasing safety risks. In addition, the high-concentration alkaline electrolyte solution relied on for alkaline water electrolysis hydrogen production is likely to damage the chemical structure of the membrane material, seriously threatening the service life of the diaphragm. Existing optimizations of membrane materials often need to seek a balance among ion transport ability, gas barrier ability, and alkali resistance, thus increasing the development difficulty of high-performance diaphragms. Therefore, how to develop an alkaline water electrolysis hydrogen production diaphragm with low cost, strong alkali resistance, and excellent gas barrier ability has important research value and application prospects for improving electrolysis efficiency, reducing energy consumption, and extending the equipment life.

[0005] CN119615276A discloses a composite diaphragm for alkaline water electrolysis and its preparation method. The composite diaphragm sequentially includes a polymer porous layer and a composite porous coating. Among them, the composite porous coating contains a support with a grid-like structure. The polymer porous layer is composed of polysulfone and chitosan. The composite porous coating is composed of an alkali-resistant polymer and inorganic nanoparticles. The alkali-resistant polymer is polysulfone. The inorganic nanoparticles include at least one of zirconia, titanium dioxide, and cerium oxide, with a particle size of 50 - 200 nm. The support is a polyphenylene sulfide mesh. Although this patent enhances the membrane performance by introducing the blend structure of chitosan and polysulfone and combining inorganic nanoparticles such as zirconia, its chitosan component is prone to swelling or degradation in an alkaline environment, affecting the long-term stability of the membrane. At the same time, this structure does not form a clear ion migration path, which may lead to insufficient OH- conduction efficiency.

[0006] CN118186492A discloses an alkaline water electrolysis composite diaphragm and its preparation method, including the following steps: S1: Dissolve a polymer in an organic solvent, then add hydrophilic inorganic nanoparticles and polyethyleneimine and mix evenly to obtain a coating slurry; S2: Coat the coating slurry on the surface of a base support mesh, and obtain a first diaphragm through reaction curing; S3: Add chitosan, polyethylene glycol, and a crosslinking agent to an acetic acid solution and mix evenly to obtain a mixed solution;

[0007] S4: Coat the mixed solution on the surface of the first diaphragm, cure and remove impurities to obtain a composite diaphragm. The polymer is at least one of polysulfone, polyphenylsulfone, and polyethersulfone. The hydrophilic inorganic nanoparticles include at least one of ZrO2, CeO2, TiO2, A l2 O3, and ZnO. The organic solvents include N-methylpyrrolidone, dimethyl sulfoxide, N,N-dimethylformamide, and N,N-dimethylacetamide. This patent adopts a double-layer coating design, coating chitosan, polyethylene glycol, and a crosslinking agent on the surface of the first diaphragm together to form a composite diaphragm structure. However, the multi-layer structure may undergo interfacial peeling during operation, and the stability of its chitosan-PEG crosslinked structure in a high-concentration alkali solution environment is questionable and is prone to disintegration, resulting in structural damage.

[0008] CN117248240A discloses a superhydrophilic alkaline water electrolysis cell composite diaphragm. The support is a polyphenylene sulfide mesh, and the polysulfone-zirconia composite membrane contains a hydrophilic polymer. The hydrophilic polymer is one or a mixture of two or more of starch derivatives, carboxymethyl cellulose, methyl cellulose, ethyl cellulose, hydroxyethyl cellulose, chitosan, polyacrylamide, polyacrylic acid, polyvinyl alcohol, polymaleic anhydride, polyquaternary ammonium salt, or polyethylene glycol, and the addition amount of the hydrophilic polymer is 1-5 wt%. Although this patent introduces a variety of hydrophilic polymers to improve the wettability and ionic conductivity of the membrane body, simply doping hydrophilic polymers is questionable for strengthening the ionic conduction channels, and there are problems of functional group shedding and hydrolysis chain breakage of hydrophilic polymers under strong alkaline conditions, resulting in compatibility and structural stability problems, and thus gradually losing functionality during alkaline soaking. Summary of the Invention

[0009] In order to solve the defect that the alkaline electrolyzed water hydrogen production diaphragm in the prior art cannot maintain structural stability for a long time in an environment of high temperature (such as 80 °C) and high-concentration alkali solution (such as 30 wt% KOH solution), the present invention proposes an alkaline electrolyzed water hydrogen production diaphragm. By introducing chitosan and performing copper complex modification, the ionic conduction ability of the membrane is improved, and the technical bottlenecks of low ionic conduction ability and insufficient alkali resistance stability of the existing alkaline electrolyzed water diaphragm are solved. Specifically, the present invention provides the following technical solutions to achieve the above object:

[0010] A modified alkaline electrolyzed water hydrogen production diaphragm, the diaphragm is composed of a functional layer and a support layer. The functional layer uses polysulfone as the skeleton, and metal oxide nanoparticles and Cu 2+ complexed chitosan are uniformly distributed in the polysulfone skeleton in an embedded form; the functional layer is a casting solution layer uniformly scraped on the support layer, and a base membrane is formed by non-solvent induced phase inversion, and then the base membrane is impregnated in a Cu complex solution; the raw materials of the casting solution include metal oxide nanoparticles, chitosan, and polysulfone; the mass ratio of metal oxide nanoparticles, chitosan, and polysulfone is 60-90:10-40:10-15.

[0011] Further, the support layer is selected from polyphenylene sulfide or fiber cloth, with a thickness of 250-500 μm and a mesh count of 40-60 meshes; the thickness of the casting solution layer is 250-500 μm; the metal oxide nanoparticles are selected from at least one of nano-zirconia, nano-titanium dioxide, and nano-cerium dioxide, and the particle size of the metal oxide nanoparticles is 10-200 nm, preferably 20-40 nm; the Cu 2+ complexed chitosan is obtained by soaking chitosan in a Cu 2+ complex solution;

[0012] Further, the Cu 2+The complexing solution is formed by complexing a Cu 2+ solution with a complexing agent; the Cu 2+ solution includes at least one of copper sulfate (CuSO4) and copper chloride (CuCl2); the complexing agent includes one of ammonia water (NH3·H2O) and disodium ethylenediaminetetraacetate (EDTA-Na2).

[0013] Furthermore, the molar concentration ratio of the Cu 2+ solution to the complexing agent is 1:(1-5); preferably 1:(3-5).

[0014] Further, the molecular weight of polysulfone is 50,000-80,000; the deacetylation degree of chitosan is ≥95%, and the molecular weight is 30,000-60,000.

[0015] Further, the mass ratio of metal oxide nanoparticles, chitosan, and polysulfone in the casting solution is 60-90:10-40:10-15, and chitosan accounts for 10-40% of the total mass of metal oxide nanoparticles and chitosan, preferably 30-40%. The inventors found that controlling the mass ratio of metal oxide nanoparticles and chitosan within the above range can achieve the full mixing of the casting solution and the uniform distribution of chitosan particles. Too low or too high this ratio is not conducive to the performance of the separator.

[0016] The present invention also provides a preparation method of the above-mentioned modified alkaline electrolytic water hydrogen production separator, including the following steps:

[0017] (S1) Disperse metal oxide nanoparticles, chitosan, and polysulfone in an organic solvent, mix evenly to obtain a casting solution, scrape the casting solution onto a support layer, and form a base film through a non-solvent induced phase separation process; in this process, a non-solvent (such as water) diffuses into the casting solution system, displaces the organic solvent, and triggers the phase separation of the polymer, forming a continuous porous structure, thereby realizing the construction of a dense skeleton and microporous channels;

[0018] (S2) Add a complexing agent to the Cu 2+ solution, and adjust the pH to weakly alkaline to obtain a copper-containing complex solution through a complexation reaction;

[0019] (S3) Immerse the base film in the copper-containing complex solution to complex Cu 2+ with chitosan in the base film to produce Cu 2+ complexed chitosan, and obtain an alkaline electrolytic water hydrogen production separator after washing with water to remove the residual complex solution.

[0020] Further, in step (S1), the organic solvent is selected from at least one of N-methylpyrrolidone (NMP), N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DMAc), and dimethyl sulfoxide (DMSO). By controlling the amount of the organic solvent, the solid content of the casting solution is 30-50%;

[0021] Further, in step (S1), while adding chitosan, a membrane pore size regulator is also added. The membrane pore size regulator is selected from at least one of polyvinylpyrrolidone (PVP), polyvinyl alcohol, polyacrylic acid and its related esters. The dosage of the membrane pore size regulator is 1-5 wt% of the mass of polysulfone, preferably 2-3 wt%. The average pore size is positively correlated with the dosage of the regulator.

[0022] Further, in step (S2), the complexing agent is selected from ammonia water (NH3·H2O) and disodium ethylenediaminetetraacetate (EDTA-Na2), and the Cu 2+ solution is selected from one of copper sulfate (CuSO4) and copper chloride (CuCl2) solutions. The concentration of the Cu 2+ solution is 0.1-0.4 mol / L, preferably 0.1-0.2 mol / L; the molar ratio of Cu 2+ to the complexing agent is 1:(3-5); adjust the pH to 9-10 to ensure the stability of the copper complex.

[0023] Further, in step (S3), immerse at 15-40 °C, preferably at 20-30 °C for 12-36 h, and rinse 3-5 times with deionized water to remove the residual complex.

[0024] The modified alkaline water electrolysis hydrogen production diaphragm of the present invention is used as an ion exchange diaphragm in an alkaline water electrolysis system to conduct hydroxide ions in the electrolysis system and block the gases generated in the two cells to prevent gas mixing.

[0025] The present invention has the following beneficial effects:

[0026] Traditional asbestos diaphragms have been gradually phased out due to carcinogenicity and easy degradation problems. Alternative materials need to consider high ionic conductivity, chemical stability and mechanical strength. At present, mainly by introducing nanoparticles (such as ZrO2, TiO2) to improve the ionic conductivity of the membrane. Chitosan molecules are rich in both amino (-NH2) and hydroxyl (-OH) groups. -NH2 can coordinate with Cu 2+ during the complexation process to form a copper-chitosan complex structure with a spatially network-like distribution, and maintain the structural integrity under alkaline conditions. This special three-dimensional structure can construct a large number of ion conduction channels, and at the same time -OH effectively promotes ion transport, significantly improving the ionic conduction performance. The present invention passes through Cu 2+The complex chitosan creates a unique spatial structure, constructs a large number of ion conduction channels, effectively promotes ion transport, breaks through the technical bottlenecks of the existing alkaline electrolyzed water membranes with poor membrane conductivity and poor alkali resistance, and provides a new solution for the long-life, high-efficiency, and low-cost development of alkaline water electrolysis hydrogen production technology. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a schematic diagram of the preparation process of the alkaline electrolyzed water hydrogen production membrane of the present invention;

[0028] Figure 2 It is a sample diagram of the alkaline electrolyzed water hydrogen production membrane prepared in Example 1 of the present invention;

[0029] Figure 3 It is a structural diagram of the copper-chitosan complex unit of the present invention;

[0030] Figure 4 It is an SEM diagram of the alkaline electrolyzed water hydrogen production membrane in Example 1;

[0031] Figure 5 It is the FTIR scanning result of the sample soaked in copper complex solutions with different concentrations. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0032] In order to make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to specific embodiments and the accompanying drawings.

[0033] Figure 1 It is a schematic diagram of the preparation process of the alkaline electrolyzed water hydrogen production membrane of the present invention. For example, chitosan, nano-ZrO, polysulfone, and polyvinylpyrrolidone (PVP) are added to NMP, stirred evenly to form a casting solution, which is scrape-coated on a support layer, and a base membrane is formed through non-solvent phase inversion. Then, the base membrane is impregnated in a copper complex solution for modification to obtain the product alkaline electrolyzed water hydrogen production membrane.

[0034] In the embodiment of the present invention, the molecular weight of polysulfone is 73,000; the deacetylation degree of chitosan is 98%, and the molecular weight is 40,000.

[0035] Preparation of the Alkaline Electrolyzed Water Hydrogen Production Membrane in Example 1

[0036] (S1) Dissolve polysulfone in N-methylpyrrolidone, then add nano-zirconia, chitosan and polyvinylpyrrolidone (molecular weight 40,000) to make the mass ratio of nano-zirconia, chitosan, polysulfone and polyvinylpyrrolidone in the casting solution 60:40:15:0.3. Stir well for 1 h and degas by ultrasonic treatment to make a casting solution with a solid content of 40%. Pour the casting solution onto a support of polyphenylene sulfide (250 μm, mesh number 40), set the height of the doctor blade to 300 μm, and uniformly scrape-coat it with a film coater at a speed of 20 mm / s and immerse it in deionized water for phase inversion to obtain a base film.

[0037] (S2) Drop Na2EDTA into the aqueous solution of CuCl2 to make the molar ratio of Cu 2+ and Na2EDTA 1:3 to form a 0.1 mol / L Cu-EDTA complex solution, and then adjust the pH of the solution to maintain it at 9-10.

[0038] (S3) Immerse the above base film completely in the above copper complex solution, soak it at room temperature for 24 h, take it out and rinse it 5 times with deionized water, and dry it to obtain an alkaline electrolyzed water hydrogen production membrane.

[0039] The physical picture of the alkaline electrolyzed water hydrogen production membrane prepared in Example 1 is as Figure 2 shown. Figure 3 is the structural diagram of the copper-chitosan complex unit.

[0040] Figure 4 is the scanning electron microscope (SEM) picture of the alkaline electrolyzed water hydrogen production membrane prepared in Example 1. It can be seen that the surface of the membrane is flat, the zirconia particles are evenly distributed, chitosan binds well with the membrane layer, and no obvious agglomeration or precipitation phenomenon appears, indicating that the complexation adsorption process is uniform and stable. This uniform loading structure helps the uniform formation of the copper complex structure, is beneficial to improving the alkali resistance stability of the membrane, and optimizes its ion transport characteristics.

[0041] In order to test the tensile strength performance of the membrane, the test is carried out according to the national standard GB / T 1040.3-2006. The specimen is cut into a long strip with a length of 150 mm, a width of 10 mm, and a thickness of about 300 μm. An electronic tensile testing machine (model: YG028PC) is used, the initial clamping distance is set to 50 mm, and the tensile speed is 5 mm / min. The two ends of the specimen are stably clamped between the upper and lower fixtures and are stretched at a constant tensile rate until the specimen breaks.

[0042] Cut the sample into a suitable size, install it in a pore size meter, measure the gas flow rate passing through under different pressures, and thus measure the average pore size and bubble point pressure of the membrane. Through detection, the average pore size of the modified membrane prepared in Example 1 is 50 nm, and the bubble point pressure is 3.0 bar, which has better gas barrier performance than the commercial membrane.

[0043] To evaluate the ionic conductivity of the membrane, the sample was cut into a suitable size and installed in an H-shaped double-tank electrolytic cell. Using Raney nickel as the cathode and nickel-iron foam as the anode, the area resistance of the membrane was measured in a 30 wt% KOH solution at 80 °C, which was 0.14 Ω·cm 2 . To evaluate the gas barrier ability of the membrane, the separator prepared in Example 1 was immersed in a 30 wt% KOH solution. After soaking in a high-concentration alkali solution for 1000 h continuously, the area resistance of the separator was 0.15 Ω·cm 2 , and no obvious change occurred, demonstrating the alkali resistance of the modified separator.

[0044] Example 2

[0045] Under other unchanged conditions, the ratio of chitosan to nano-zirconia in step S1 of Example 1 was changed. By adjusting the ratio of chitosan to nano-zirconia in step S1, samples with different doping ratios were prepared. Among them, when the mass ratios of nano-zirconia, chitosan, and polysulfone were 90:10:15 respectively, the corresponding chitosan doping ratio was 10%; when the mass ratio was 80:20:15, the corresponding doping ratio was 20%; when the mass ratio was 70:30:15, the corresponding doping ratio was 30%; when the mass ratio was 60:40:15, the corresponding doping ratio was 40%. The tensile strength characterization results of the modified separators with different chitosan doping ratios are shown in Table 1:

[0046] Table 1 Tensile strength of modified separators with different chitosan doping ratios

[0047]

[0048] Example 3

[0049] Under other unchanged conditions, the electrochemical performance of the modified separator prepared by soaking treatment with copper complex solutions of different concentrations in step S2 of Example 1 was represented by the area resistance. The results are shown in Table 2:

[0050] Table 2 Area resistance of modified separators prepared by soaking treatment with copper complex solutions of different concentrations

[0051]

[0052] Figure 5 For the FTIR scanning results of samples soaked in copper complex solutions of different concentrations, it can be seen that at 3500 cm - -1 and 1585 cm -The characteristic peaks at 1 are the stretching vibration peak of -OH and the absorption peak of Cu-N coordination, indicating that Cu and chitosan have formed a complex. As the concentration of copper ions increases, the stretching vibration peak of -OH gradually weakens, while the absorption peak of Cu-N coordination increases, indicating that more chitosan has formed a complex with Cu.

[0053] Comparative Example 1

[0054] The preparation process only performs step (S1) of Example 1 and does not perform steps (S2) and (S3). That is, the base film obtained in step S1 is used as the alkaline electrolyzed water hydrogen production diaphragm without soaking in the copper complex solution. After performance characterization and alkali resistance testing, the area resistance of the diaphragm made in Comparative Example 1 is 0.34 Ω·cm 2 ; in the 30 wt% KOH alkali resistance test, the area resistance of the diaphragm increased significantly to 0.64 Ω·cm when soaked for 300 h 2 , and the alkali resistance is significantly lower than that of the modified diaphragm prepared in Example 1.

[0055] Comparative Example 2

[0056] The preparation process is the same as that in Example 1, except that in step (S2), the CuCl2 solution used to prepare the complex solution is replaced with an equimolar concentration of ZnCl2 solution (0.1 mol / L) to make a Zn-EDTA solution. After performance characterization, the area resistance of the modified diaphragm made in this comparative example is 0.22 Ω·cm 2 , and after 1000 h of 30 wt% KOH alkali resistance test, the area resistance of the diaphragm is 0.28 Ω·cm 2 .

[0057] Comparative Example 3

[0058] The preparation process is the same as that in Example 1, except that in step (S2), the CuCl2 solution used to prepare the complex solution is replaced with an equimolar concentration of MgCl2 solution (0.1 mol / L) to make a Mg-EDTA solution. After performance characterization, the area resistance of the modified diaphragm made in this comparative example is 0.25 Ω·cm 2 , and after 1000 h of 30 wt% KOH alkali resistance test, the area resistance of the diaphragm is 0.37 Ω·cm 2 .

[0059] Comparative Example 4

[0060] The preparation process is the same as that in Example 1, except that in step (S2), the CuCl2 solution used to prepare the complex solution is replaced with an equimolar concentration of CaCl2 solution (0.1 mol / L) to make a Ca-EDTA solution. After performance characterization, the area resistance of the modified diaphragm made in this comparative example is 0.21 Ω·cm 2After the alkali resistance test of 30 wt% KOH at 1000 h, the area resistance of the separator is 0.40 Ω·cm 2 .

[0061] Comparing Example 1 with the above comparative example, it can be seen that after impregnation with the copper complex solution, the performance and stability of the separator can be greatly improved. Although the reason is not clear yet, the inventors found that the improvement of the performance of the alkaline electrolytic water hydrogen production separator by metal ion complexation is limited to the complexation with Cu 2+ . The complexation with Zn 2+ , Mg 2+ , Ca 2+ cannot achieve the performance improvement of the separator as that after complexation with Cu 2+ .

Claims

1. A modified alkaline electrolyzed water hydrogen production membrane, which is composed of a functional layer and a support layer, and is characterized in that, The functional layer uses polysulfone as the backbone, and metal oxide nanoparticles and Cu2 + complexed chitosan are uniformly distributed in the polysulfone backbone in an embedded form; The functional layer is a casting solution layer evenly scraped on the support layer, and a base film is formed through non-solvent induced phase inversion. Then, the base film is impregnated in a complex solution of Cu 2+ to obtain; the raw materials of the casting solution include metal oxide nanoparticles, chitosan, and polysulfone; the mass ratio of metal oxide nanoparticles, chitosan, and polysulfone is 60-90:10-40:10-15; and chitosan accounts for 10-40% of the total mass of metal oxide nanoparticles and chitosan.

2. The modified alkaline electrolyzed water hydrogen production diaphragm according to claim 1, wherein The support layer is selected from polyphenylene sulfide or fiber fabric, with a thickness of 250 - 500 μm and a mesh count of 40 - 60 meshes; the thickness of the casting solution layer is 250 - 500 μm; the metal oxide nanoparticles are selected from at least one of nano-zirconia, nano-titanium dioxide, and nano-cerium dioxide, and the particle size of the metal oxide nanoparticles is 10 - 200 nm, preferably 20 - 40 nm.

3. The modified alkaline electrolyzed water hydrogen production diaphragm according to claim 2, wherein The complex solution of Cu is formed by complexing a Cu2 + solution with a complexing agent; the Cu 2+ solution includes at least one of copper sulfate (CuSO4) and copper chloride (CuCl2); the complexing agent includes one of ammonia water (NH3·H2O) and disodium ethylenediaminetetraacetate (EDTA-Na2).

4. The modified alkaline electrolyzed water hydrogen production diaphragm according to claim 3, characterized in that, The described Cu 2+ The molar concentration ratio of the solution to the complexing agent is 1:(1 to 5); preferably 1:(3 to 5).

5. The modified alkaline electrolyzed water hydrogen production diaphragm according to claim 1, wherein The molecular weight of polysulfone is 50,000 - 80,000; the degree of deacetylation of chitosan is ≥95%, and the molecular weight is 30,000 - 60,000; preferably, chitosan accounts for 10 - 20% of the total mass of the metal oxide nanoparticles and chitosan.

6. The preparation method of the alkaline electrolyzed water hydrogen production diaphragm according to any one of claims 1-5, characterized in that, Comprising the following steps: (S1) Disperse the metal oxide nanoparticles, chitosan, and polysulfone in an organic solvent, mix evenly to obtain a casting solution, scrape the casting solution onto the support layer, and form a base film through a non-solvent induced phase inversion process; (S2) Add a complexing agent to the Cu 2+ solution, adjust the pH to weakly alkaline, and obtain a copper complex solution through a complexation reaction; (S3) Immerse the base membrane in a copper complex solution to complex Cu 2+ with chitosan in the base membrane to produce Cu 2+ complexed chitosan, wash with water, and dry to modify the alkaline electrolyzed water hydrogen production diaphragm.

7. The preparation method according to claim 6, characterized in that, In step (S1), the organic solvent is selected from at least one of N-methylpyrrolidone (NMP), N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DMAc), and dimethyl sulfoxide (DMSO), and the amount of the organic solvent used is such that the solid content of the casting solution is 30 - 50%.

8. The preparation method according to claim 6, characterized in that, In step (S1), while adding chitosan, a membrane pore size regulator is also added. The membrane pore size regulator is selected from at least one of polyvinylpyrrolidone (PVP), polyvinyl alcohol, polyacrylic acid, and its related esters, and the amount of the membrane pore size regulator used is 1 - 5 wt% of the mass of polysulfone, preferably 2 - 3 wt%.

9. The preparation method according to claim 6, characterized in that, In step (S2), the complexing agent is selected from ammonia water (NH3·H2O) and disodium ethylenediaminetetraacetate (EDTA-Na2), and the Cu 2+ solution is selected from one of copper sulfate (CuSO4) and copper chloride (CuCl2) solutions, and the Cu 2+ solution concentration is 0.1 - 0.4 mol / L, preferably 0.1 - 0.2 mol / L; and the Cu 2+ molar ratio of and the complexing agent is 1:(3 - 5); adjusting the weak alkalinity is to adjust the pH to 9 - 10; further, in step (S3), the impregnation treatment is carried out at a temperature of 15 - 40 °C, preferably 20 - 30 °C, and the duration is 12 - 36 hours.

10. Use of the modified alkaline electrolyzed water hydrogen production membrane according to any one of claims 1 - 5 as an ion exchange membrane in an alkaline water electrolysis system.

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