Hydrogen / electric conversion system catalyst interface ionomer regulation method and application

Abstract

This invention belongs to the field of catalytic interface regulation technology for hydrogen / electroconversion systems, and discloses a method and application for regulating ionomers at the catalyst interface of hydrogen / electroconversion systems. This invention designs covalent organic framework materials and performs amphoteric charge functionalization and stripping steps to prepare small-sized, thin-walled porous covalent organic framework nanosheets with adjustable pore size and customizable surface ionic charges. These nanosheets are used to regulate the morphology of ionomers at the catalytic interface of electrochemical engineering hydrogen / electroconversion systems, thereby significantly improving catalytic utilization efficiency and effectively addressing the poor stability caused by inhomogeneous defects at the catalytic interface, while reducing the amount of ionomers required for catalytic interface construction. This has significant implications for promoting the large-scale commercialization of hydrogen / electroconversion systems.

Description

Technical Field

[0001] This invention belongs to the field of catalytic interface regulation technology for hydrogen / electroconversion systems, and specifically relates to a method and application for regulating interfacial ionomers in hydrogen / electroconversion catalysts. Background Technology

[0002] With the advancement of the global green energy transition, the hydrogen energy industry is gradually becoming one of the fastest-growing sectors in the energy field in terms of investment. Hydrogen, as an energy carrier, achieves the reversible conversion between electrical and chemical energy in water electrolysis reactors and fuel cells, and is considered an ideal way to solve the energy shortage and environmental pollution problems facing human society. Water electrolysis reactors and fuel cells have important advantages such as high energy conversion efficiency, zero carbon emissions, rapid response, and high current density, and have broad application prospects in peak-valley energy storage, energy transportation, communications, aviation / aerospace, and underwater submarines. Currently, performance and cost are the two major technical barriers to the commercialization of hydrogen / electricity conversion systems. Because hydrogen / electricity conversion systems are highly dependent on precious metals such as platinum and iridium, the cost of hydrogen / electricity conversion system devices is driven up. Therefore, using low-precious-metal catalysts and improving the utilization rate of precious metals is an effective way to solve the cost problem. Electrocatalytic reactions in hydrogen / electroconversion systems occur at the solid-liquid-gas three-phase interface of the electrocatalyst, involving processes such as gas transport, proton / hydroxyl transport, and electron transport. The low catalytic utilization rate of hydrogen / electroconversion systems is often affected by the microenvironment of the reaction interface composed of ionomers (such as Nafion, polybenzimidazole). Studies have shown that during the preparation of catalyst slurries for hydrogen / electroconversion devices, the drying process affects the morphology of polymeric ionomers, leading to agglomeration, phase separation, and crystal phase transformation. Strong adsorption occurs on the hydrophilic surface of the electrocatalyst support and the catalytic metal surface. Under the transformation from a non-polar slurry solvent to a polar working environment, polymeric ionomers tend to further aggregate, changing from dispersed chain morphology to rod-shaped aggregates. Due to the combined effect of these factors, the catalyst microenvironment reconstructed by three-dimensional scanning exhibits a state of non-uniform aggregation and non-uniform coverage. Simply changing the amount of ionomer in the catalyst slurry cannot effectively improve this morphology. Therefore, the non-uniform aggregation and non-uniform coverage state usually causes common problems in hydrogen / electroconversion systems: (1) poisoning of catalyst particles, where the side chain groups of ionomers occupy the surface of catalytic active sites through strong adsorption, leading to a decrease in intrinsic catalytic activity and a reduction in effective active area; (2) discontinuous proton transport channels, where phase separation in ionomer aggregates forms distinct hydrophilic and hydrophobic phase intervals, resulting in complex and non-uniform transport paths for protons or hydroxide ions from the membrane to the surface of the catalytic sites. Uncovered catalytic sites can only transport ions through the aqueous environment, which means a slower transport rate and lower utilization of precious metals; (3) high local gas transport resistance, where ionomer aggregation affects the gas transport in the secondary pores originally constructed between catalysts, covers catalytic active sites, further increases the adsorption and desorption resistance of local gases, and thus affects the full utilization of active sites. Therefore, the root cause of the interface problem is due to the morphology of the ionomers. Improving the evolution process of the ionomer morphology and regulating the reasonable formation of the electrocatalytic interface are beneficial to fully utilizing the activity of the catalytic sites, i.e., reducing the low utilization of precious metals.Covalent organic frameworks (COFs) correspond to a class of porous organic materials formed solely by organic frameworks linked by covalent interactions, possessing permanent porosity and highly ordered properties. Key characteristics of COFs include ordered pore structures, functionalized groups, high specific surface area, charge transport channels, high physicochemical stability, and structural designability. These features make COFs promising materials with customizable functionalization potential. Currently, customized covalent organic framework materials have been used in proton exchange membranes, anion exchange membranes, fuel cells, and water electrolysis interfaces. Furthermore, some researchers have focused on addressing the poor performance of hydrogen electrocatalytic systems, proposing related research to tackle issues such as strong metal adsorption, uneven distribution, and localized high gas transport resistance at interfaces.

[0003] Chinese patent application CN113314722A discloses a method for reducing the poisoning effect of sulfonic acid groups on Pt catalysts within a fuel cell catalyst layer. By using a catalyst slurry modified with a highly sterically hindered alcohol, the direct contact between Nafion ionomers and the Pt surface is reduced, thereby mitigating the poisoning effect of sulfonic acid groups on the Pt-based catalyst and improving the performance of the fuel cell membrane electrode assembly. Chinese patent application CN114361469A discloses a novel fuel cell catalyst layer and its preparation method, as well as a fuel cell using this catalyst layer. This catalyst layer consists of an electrocatalyst and a special ionomer, which is a mixture of perfluorosulfonic acid ionomers and covalent organic framework (COF) ionomers. The COF ionomers possess a porous two-dimensional nanosheet structure, high ion exchange capacity, and proton conductivity, properties that contribute to improved fuel cell performance. Chinese patent application CN118412481A discloses a method for preparing a surface-nitrogen-modified carbon support for fuel cells. This method introduces oxygen-containing functional groups onto the surface of a carbon support through specific chemical treatment steps, and achieves nitrogen doping through reaction with primary amines and amides. This nitrogen-modified carbon support can improve the distribution of ionomers on the catalyst surface, reduce mass transfer problems such as local oxygen transport, increase the coverage of ionomers on the catalyst surface, and thus improve the proton conductivity inside the catalyst layer.

[0004] Improving the rational shaping of the electrocatalytic interface has been the most important approach to enhancing the catalytic utilization efficiency of hydrogen / electroconversion systems internationally for many years. However, how to construct a more rational catalytic interface microenvironment by controlling the morphology of ionomers to fully utilize the activity of catalytic sites and obtain low noble metal utilization remains a challenging issue in this field. Materials and methods that can be universally applied to hydrogen / electrocatalytic systems still require further research. Summary of the Invention

[0005] To overcome the shortcomings and deficiencies of the prior art, the primary objective of this invention is to provide a method for regulating the ionomer morphology at the catalyst interface of a hydrogen / electroconversion system. This method involves designing a covalent organic framework material, functionalizing it with amphoteric charges, and performing stripping steps to obtain small-sized, thin-walled porous covalent organic framework nanosheets. These nanosheets possess adjustable pore size and customizable surface ionic charges, and are used to regulate the ionomer morphology at the catalyst interface of an electrochemical hydrogen / electroconversion system. This significantly improves catalytic utilization efficiency, effectively addresses the poor stability caused by inhomogeneous defects at the catalyst interface, and reduces the amount of ionomer required for catalyst interface construction.

[0006] Another objective of this invention is to provide a membrane electrode for the hydrogen / electroconversion system prepared by the above method.

[0007] Another objective of this invention is to provide the application of the above-mentioned hydrogen / electroconversion system membrane electrode in electrochemical reaction engineering such as proton exchange membrane fuel cells, anion exchange membrane fuel cells, proton exchange membrane water electrolysis, and anion exchange membrane water electrolysis.

[0008] The objective of this invention is achieved through the following solution:

[0009] A method for controlling interfacial ionomers in a hydrogen / electroconversion system catalyst includes the following steps:

[0010] (1) Preparation of covalent organic framework precursor: Dissolve organic monomers in organic solvent, mix to obtain reaction mixture, and then seal for polymerization reaction to obtain covalent organic framework precursor;

[0011] (2) Preparation of functionalized covalent organic framework nanosheets: The covalent organic framework precursor synthesized in step (1) is added to a solvent, and then a functionalizing material is added to functionalize the covalent organic framework precursor. After separation and purification, it is peeled off into nanosheets to obtain functionalized covalent organic framework nanosheets.

[0012] (3) Preparation of ionomer dispersion regulated by functionalized covalent organic framework nanosheets: functionalized covalent organic framework nanosheets were dispersed in a solvent, and then ionomers were added to mix and self-assemble to obtain ionomer dispersion regulated by functionalized covalent organic framework nanosheets.

[0013] (4) Constructing an electrochemical engineering catalytic interface: The catalyst, solvent, ionomer and functionalized covalent organic framework nanosheet-controlled ionomer dispersion are mixed to obtain a functionalized catalyst slurry. The functionalized catalyst slurry is sprayed or scraped onto one or both sides of the proton exchange membrane surface to prepare a catalytic layer or related membrane electrode.

[0014] In step (1), the covalent organic framework precursor is synthesized by Schiff base reaction polymerization. The organic monomers include aldehyde monomers and amino monomers, wherein the aldehyde monomers include terephthalaldehyde, 2,4,6-tris(4-aldehydephenyl)-1,3,5-triazine, 5'-(4-formylphenyl)-[1,1':3',1”-triphenyl]-4,4”-dicarboxaldehyde, 1,3,5-benzenetricarboxaldehyde, and tris(4-formylphenyl) The aldehyde monomer is selected from the following: amine, 4,4,4,4-(pyrene-1,3,6,8-tetramethyl)tetrabenzaldehyde; the amino monomer includes one of the following: 2,5-diaminopyridine, 2,6-diaminopyridine, 3,8-diamino-6-phenylphenanthridine, [3,3'-bipyridine]-6,6'-diamine, 1,10-phenanthroline-3,8-diamine, acridine-2,6-diamine; the molar ratio of the aldehyde monomer to the amino monomer is 1:0.5-2.

[0015] The organic solvent mentioned in step (1) includes one or more of the following: mesitylene, 1,4-dioxane, acetic acid, n-butanol, dioxane, o-dichlorobenzene, and tetrahydrofuran, preferably two or more.

[0016] The step (1) of dissolving the organic monomer in an organic solvent can be done by dissolving the aldehyde monomer and the amine monomer together in an organic solvent to obtain a reaction mixture, or by first dissolving the aldehyde monomer and the amine monomer separately in an organic solvent, and then mixing the solutions of the aldehyde monomer and the amine monomer to obtain a reaction mixture. The organic solvent used to dissolve the aldehyde monomer and the organic solvent used to dissolve the amine monomer can be the same or different.

[0017] The sealing described in step (1) is preferably performed after a freezing-evacuation-thawing cycle.

[0018] The polymerization reaction conditions described in step (1) are: reaction temperature 80-150℃, time 10-100h, and reaction conditions of stirring or reflux.

[0019] After the polymerization reaction in step (1) is completed, a purification step is also included. The specific steps are as follows: the reaction product obtained after the reaction is precipitated, filtered, washed, and dried. Among them, precipitation refers to the addition of a precipitating agent for precipitation. The precipitating agent is an aqueous solution of NaCl with a concentration of 0.1-1 mol / L. Washing refers to washing with at least one of N,N-dimethylformamide, methanol, acetone, n-hexane, tetrahydrofuran, and acetonitrile. Drying refers to vacuum drying at a temperature of 60-150℃ for 8-72 hours.

[0020] The solvent mentioned in step (2) includes at least one of dimethyl sulfoxide, N,N-dimethylformamide, tetrahydrofuran, acetonitrile, n-hexanol, toluene, chloroform, and water;

[0021] The functionalization described in step (2) is the functionalization of amphoteric groups. Therefore, the charge-functionalized material described in step (2) is at least one of 1,3-propanesulfonate lactone, propenyl-1,3-sulfonate lactone, 1,4-butanesulfonate lactone, and 1,8-naphthalenesulfonate lactone.

[0022] The mass ratio of the covalent organic framework precursor to the functionalized material in step (2) is 1:0.04-0.12; the functionalization in step (2) refers to the reaction at 80-120℃ for 12-48h.

[0023] The separation and purification described in step (2) refers to adding a settling agent to the functionalized product for sedimentation, followed by centrifugation, filtration, washing, and drying. The settling agent is an aqueous solution of NaCl with a concentration of 0.1-1 mol / L. Washing refers to washing with at least one of N,N-dimethylformamide, methanol, acetone, n-hexane, tetrahydrofuran, and acetonitrile, which can be repeated 3-4 times.

[0024] The peeling mentioned in step (2) refers to peeling by at least one of ball milling and ultrasonic dispersion; wherein the diameter of the ball milling beads is 0.1-5 mm, the ball-to-material ratio is 10-20:1, and the ball milling time is 12-72 h; the ultrasonic dispersion temperature is 30-80℃, and the time is 30 min-12 h.

[0025] In step (3), the solvent includes at least one of ethanol, isopropanol, n-propanol, and acetone; the ionomer in step (3) includes at least one of perfluorosulfonic acid resin, sulfonated polyether ether ketone, sulfonated polystyrene, sulfonated polyimide, sulfonated polyether, sulfonated polytetrafluoroethylene, and polybenzimidazole. The ionomer is preferably added in the form of an ionomer solution, and more preferably is a Nafion dispersion.

[0026] In the ionomer dispersion regulated by functionalized covalent organic framework nanosheets in step (3), the concentration of ionomer ranges from 0.1wt% to 5wt%, and the concentration of functionalized covalent organic framework nanosheets ranges from 0.0001wt% to 20wt%. The mixing for self-assembly in step (3) refers to sonication at a temperature of 0-80℃ for 2 min to 12 h for self-assembly.

[0027] In step (4), the catalyst includes one of acidic / basic ORR catalysts and acidic / basic OER catalysts. The ORR catalyst includes at least one of commercially available noble metal catalysts such as Pt / C and Ru / C, alloy or intermetallic compound catalysts such as PtCo-based and PtNi-based catalysts, and non-noble metal catalysts such as Fe-NC and Co-NC. The OER catalyst includes at least one of acidic OER catalysts such as Ru and Ir-based catalysts, and basic OER catalysts such as Co, Ni, and Fe-based transition metals and their oxides. The solvent is one or more of water, ethanol, n-propanol, and isopropanol.

[0028] The ionomers mentioned in step (4) include at least one of perfluorosulfonic acid resin, sulfonated polyether ether ketone, sulfonated polystyrene, sulfonated polyimide, sulfonated polyether, sulfonated polytetrafluoroethylene, and polybenzimidazole;

[0029] In the functionalized catalyst slurry described in step (4), the dry weight ratio of the functionalized covalent organic framework nanosheets (where the dry weight ratio refers to the percentage of the mass of the functionalized covalent organic framework nanosheets to the mass of all solid substances in the dried catalyst slurry) is 0.001-5 wt%, the mass ratio of the ionomer to the functionalized covalent organic framework nanosheets is 1:0.0001-1:5, the concentration of the catalyst is 0.01-25 wt%, and the mass ratio of the ionomer to the catalyst (when the support in the catalyst is a non-carbon support) or the carbon material in the catalyst is 0.2:1-0.8:1.

[0030] To achieve efficient and high-utilization conversion of novel catalysts for hydrogen / electroconversion systems into devices, this invention employs a novel method for regulating ionomers at the catalytic interface. By rationally designing the chemical groups and structural morphology of covalent organic framework nanosheets, and using them as slurry additives, the distribution of ionomers within the ionomer film covering state is controlled during the catalyst slurry-to-device membrane electrode preparation process. When applied to hydrogen / electroconversion system devices, this method significantly improves catalytic utilization efficiency and effectively addresses the stability issues caused by inhomogeneous defects at the catalytic interface, while also reducing the amount of ionomers required for catalytic interface construction. This universal additive method effectively bridges the significant conversion gap between ideal microenvironment three-electrode testing systems and actual working membrane electrode systems, while also effectively reducing the cost of designing novel catalysts with specific catalytic microenvironments and minimizing the amount of ionomers required for microenvironment construction. This is of great significance for promoting the large-scale commercialization of hydrogen / electroconversion systems.

[0031] A catalytic layer or membrane electrode for a hydrogen / electroconversion system prepared by the above method is disclosed. The catalytic interface control method described in this invention is characterized by its targeted and customizable nature, ability to control the formation of ionomer thin layers, low local gas transport resistance, continuous ion transport channels, and universality. The preparation steps using this catalytic interface control method are green, safe, and simple, and the resulting hydrogen / electroconversion system device exhibits high polarization curve performance and high stability.

[0032] Another objective of this invention is to provide the application of the catalyst layer or membrane electrode of the above-mentioned hydrogen / electroconversion system in electrochemical reaction engineering such as proton exchange membrane fuel cells, anion exchange membrane fuel cells, proton exchange membrane water electrolysis, and anion exchange membrane water electrolysis.

[0033] This invention aims to utilize customizable functionalized covalent organic nanosheets to regulate the distribution of ionomers during the catalyst slurry preparation process. This allows for the induction of uniform thin layers with low ionomer dosage, thereby achieving uniform ion transport and low local gas transport resistance, improving the electrocatalytic utilization rate of the three-phase interface, reducing poisoning, effectively enhancing the performance and durability of the device's membrane electrode, and significantly reducing costs.

[0034] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0035] 1. The customizable functionalized covalent organic framework nanosheets provided by this invention can be designed with specific structures and functional groups for different hydrogen / electroconversion system devices under actual operating conditions. Utilizing the porous structure and amphoteric groups of the covalent organic framework, it enables control over ionomer morphology, adsorption / desorption of intermediate reactants, and adsorption / anchoring of polymer chains. Furthermore, by adjusting the pore size, thickness, and dimensions of the nanosheets, it achieves functions such as efficient gas transport, interface coverage, and interlayer regulation. When applied to industrial devices in hydrogen / electroconversion systems, it exhibits significant performance improvements, reduces ion and gas transport resistance at the device's catalytic interface, enhances the full utilization of catalytic active sites, and effectively reduces the gap in catalytic activity and performance between novel catalysts in three-electrode systems and membrane electrode systems.

[0036] 2. The customizable functionalized covalent organic framework nanosheets provided by this invention have good chemical and thermal stability under actual device conditions. They maintain stable chemical structure and morphology in environments such as high temperature and high humidity, so that the constructed catalytic microenvironment can be maintained and continuously function. When applied to actual hydrogen / electroconversion systems, they can provide good reliability for the catalytic interface layer.

[0037] 3. The catalytic interface ionomer regulation method provided by this invention has achieved good performance improvement in various hydrogen / electric conversion system devices, such as proton exchange membrane fuel cells and proton exchange membrane water electrolysis devices, and has improved the overall performance of membrane electrodes.

[0038] 4. The catalytic interface ionomer control method provided by this invention enhances the stability and durability of the device membrane electrode. The uniform ionomer thin layer reduces the problem of catalyst coverage detachment caused by ionomer agglomeration and migration, and extends the service life of the hydrogen / electric conversion system device membrane electrode.

[0039] 5. The present invention is pollution-free in the preparation process, simple to operate, requires low-level synthesis equipment, and the slurry preparation process is easy to master and control, which is conducive to the large-scale application of catalytic interface regulation methods. Attached Figure Description

[0040] Figure 1 A schematic diagram illustrating the synthesis of amphoteric functionalized covalent organic framework nanosheets;

[0041] Figure 2 These are transmission electron microscope (TEM) images of the covalent organic framework material before and after charge functionalization in Example 1 of the present invention, where A is the TEM image before charge functionalization and B is the TEM image after charge functionalization.

[0042] Figure 3 The images shown are atomic force microscopy (AFM) images of the covalent organic framework material nanosheets before and after functionalization in Example 1 of this invention, where A and B are AFM images and thickness distributions before charge functionalization, and C and D are AFM images and thickness distributions after charge functionalization.

[0043] Figure 4 The image shows the TEM and elemental distribution of the catalyst interface in Example 2 of the present invention, where A is the TEM image and B is the elemental distribution image.

[0044] Figure 5 The image shows the TEM and elemental distribution of the catalyst interface in Comparative Example 3 of this invention, where A is the TEM image and B is the elemental distribution image.

[0045] Figure 6 This is an AFM image of the catalyst interface in Example 2 of the present invention;

[0046] Figure 7 This is the AFM diagram of the catalyst interface in Comparative Example 3 of the present invention;

[0047] Figure 8 The polarization curves of hydrogen-oxygen fuel cells in Example 1 and Comparative Examples 1 and 2 of this invention are shown.

[0048] Figure 9 The polarization curves of hydrogen-oxygen fuel cells in Example 2, Comparative Examples 3 and 4 of this invention are shown.

[0049] Figure 10The images show in-situ electrochemical test results of Example 1, Comparative Examples 1 and 2 of the present invention, where A is the effective electrochemical active area, B is the proton conductivity, and C is the local oxygen transport resistance.

[0050] Figure 11 The images show the proton exchange membrane electrolysis membrane electrode polarization curves of Embodiment 3 and Comparative Example 5 of the present invention. Detailed Implementation

[0051] The present invention will be further described in detail below with reference to embodiments and accompanying drawings, but the embodiments of the present invention are not limited thereto. Unless otherwise specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments used, unless otherwise specified, are all commercially available conventional products.

[0052] Example 1

[0053] (1) 0.2 mmol of 2,4,6-tris(4-aldehydephenyl)-1,3,5-triazine was dissolved in 1.5 mL of n-butanol solvent, and 0.3 mmol of 3,8-diamino-6-phenylphenanthridine was dissolved in 1.5 mL of tetrahydrofuran solvent. The two solutions were ultrasonically dispersed in an ice-water bath at 0 °C for 30 min. After mixing the two solutions, they were stirred at 0 °C for 1 h. After a freeze-vacuum-thaw cycle, the mixture was sealed and subjected to polymerization reaction in an oil bath at 120 °C for 24 h. 1 mol / L NaCl aqueous solution was added for precipitation. The mixture was washed three times with tetrahydrofuran-n-hexane, deoxygenated, and stored in n-hexane solvent overnight. After separation and washing, it was dried under vacuum at 80 °C to synthesize the covalent organic framework precursor A1.

[0054] (2) 100 mg of the synthesized covalent organic framework precursor A1 was added to a mixed solution with a volume ratio of acetonitrile:n-hexanol of 1:1. After freezing-vacuuming-thawing cycle, the mixture was ultrasonically dispersed for 30 min. 5 μL of propenyl-1,3-sulfonyl lactone was added, and the mixture was reacted at 100 °C for 12 h to carry out the grafting of amphoteric charge functionalization reaction. 1 mol / L NaCl aqueous solution was added for sedimentation. After centrifugation and filtration, acetonitrile, N,N-dimethylformamide, and methanol were added for washing. The mixture was vacuum dried and ground into powder. The powder was further ball-milled for 72 h to exfoliate the material into nanosheets. The diameter of the ball milling beads ranged from 0.1 to 5 mm, and the ball-to-material ratio was 10:1. The mixture was washed again with methanol and ultrasonically dispersed at 30 °C for 4 h. The upper dispersed nanosheets were then collected and vacuum dried to obtain the ion-functionalized covalent organic framework nanosheet material B1.

[0055] (3) Take 2 mg of amphoteric functionalized covalent organic framework nanosheet material B1, add it to 20 mL of a mixed solution of ethanol: n-propanol with a volume ratio of 1:3, and ultrasonically disperse for 1 h to obtain a covalent organic framework nanosheet dispersion; take 1 mL of the covalent organic framework nanosheet dispersion and mix it with 1 mL of 0.2 wt% Nafion dispersion uniformly dispersed in ethanol, and ultrasonically disperse for 1 h in an ice-water bath at 0 °C to obtain a dispersion mixture of ionomers regulated by amphoteric functionalized covalent organic framework nanosheets C1.

[0056] (4) Take 5 mg of 20% Pt / C catalyst, 10 mL of a mixed solution of ethanol:n-propanol in a volume ratio of 1:3, 50 μL of amphoteric functionalized covalent organic framework nanosheet-regulated ionomer dispersion mixture C1, and 16.3 μL of 5 wt% Nafion solution. Mix them evenly in an ice-water bath at 0℃ and ultrasonically disperse for 1 h to prepare the cathode catalyst slurry; the anode catalyst slurry contains 6 mg of 20% Pt / C catalyst, 62 μL of 5 wt% Nafion solution, and 10 mL of a mixed solution of ethanol:isopropanol in a volume ratio of 1:3; uniformly spray the cathode catalyst slurry and the anode catalyst slurry onto both sides of a Gore 15 μm proton exchange membrane to prepare the fuel cell membrane electrode, wherein the anode catalyst loading is 0.1 mg Pt / cm 2 The mass ratio of ionomers in the anode catalyst layer to carbon materials in the catalyst is 0.6:1; the cathode catalyst loading is 0.1 mg Pt / cm³. 2 The ratio of the mass of ionomers in the cathode catalyst layer to the mass of carbon materials in the catalyst is 0.2:1.

[0057] The membrane electrode assembly described above was assembled into a fuel cell, and the battery performance was tested under the following conditions: the anode fuel was hydrogen with a flow rate of 0.3 slpm, the cathode oxidant was oxygen with a flow rate of 0.4 slpm, the battery temperature was 80℃, the relative humidity of the anode and cathode was 100%, and the back pressure of the anode and cathode was 200 kPa.

[0058] Comparative Example 1:

[0059] Using the same method, the difference from Example 1 is that, instead of adding amphoteric functionalized covalent organic framework nanosheets, 5 wt% Nafion solution is used to directly replace the 50 μL of ionomer dispersion mixture C1 controlled by amphoteric functionalized covalent organic framework nanosheets in step (4). The amount of Nafion solution used satisfies the ratio of ionomer mass in the cathode catalyst layer to carbon material mass in the catalyst = 0.6:1. The catalyst is then prepared as a cathode catalyst layer slurry. The anode catalyst layer slurry is the same as in Example 1 and is sprayed onto both sides of the proton exchange membrane to prepare a fuel cell membrane electrode.

[0060] Comparative Example 2:

[0061] Using the same method, the difference from Example 1 is that the covalent organic framework precursor A1 is directly exfoliated under the same conditions as in step (2) to prepare a non-ampholy functionalized covalent organic framework material (i.e., the covalent organic framework precursor A1 is ground into powder, further ball-milled for 72 hours to exfoliate the material into nanosheets, the diameter of the ball milling beads is 0.1-5 mm, the ball-to-material ratio is 10:1; after washing with methanol again, the upper dispersed nanosheets are ultrasonically dispersed at 30°C for 4 hours and then vacuum dried). This material replaces the amphoteric functionalized covalent organic framework nanosheet material B1 in step (3) to prepare the catalyst as a cathode catalyst layer slurry. The anode catalyst layer slurry is the same as in Example 1. It is sprayed onto both sides of the proton exchange membrane to prepare a fuel cell membrane electrode. The total amount of ionomers used in the cathode catalyst layer and the total amount of ionomers used in the anode are the same as those in the cathode and anode in Example 1, respectively.

[0062] Example 2

[0063] (1) 0.2 mmol of 1,3,5-benzyltricarboxaldehyde was dissolved in 1.5 mL of mesitylene solvent, and 0.3 mmol of [3,3'-bipyridine]-6,6'-diamine was dissolved in 1.5 mL of dioxane solvent. The two solutions were ultrasonically dispersed in an ice-water bath at 0 °C for 30 min. After mixing the two solutions, they were stirred at 0 °C for 1 h. After a freeze-vacuum-thaw cycle, the mixture was sealed and subjected to polymerization reaction in an oil bath at 150 °C for 72 h. 1 mol / L NaCl aqueous solution was added for precipitation. The mixture was washed three times with methanol-tetrahydrofuran. After separation and washing, it was dried under vacuum at 80 °C to synthesize the covalent organic framework precursor A2.

[0064] (2) Take 200 mg of the synthesized covalent organic framework precursor A2 and add it to a mixed solution of acetonitrile:chloroform with a volume ratio of 3:1. Disperse it ultrasonically for 1 h, add 6.25 uL of 1,3-propanesulfonic acid lactone, and react at 120 °C for 24 h to carry out the grafting of amphoteric charge functionalization reaction. Add 1 mol / L NaCl for precipitation, centrifuge and filter, and then add acetonitrile, tetrahydrofuran and methanol for washing respectively. Vacuum dry and grind into powder, and further ball mill for 24 h to exfoliate the material into nanosheets. The diameter of the ball milling beads ranges from 0.1 to 5 mm and the ball-to-material ratio is 10:1. After washing with methanol again, ultrasonically disperse at 30 °C for 8 h and take the upper dispersed nanosheets. After vacuum drying, the amphoteric charge functionalized covalent organic framework material B2 is obtained.

[0065] (3) Take 0.5 mg of amphoteric functionalized covalent organic framework nanosheet material B2, add it to 20 mL of a mixed solution with a volume ratio of ethanol: n-propanol of 1:3, and ultrasonically disperse for 1 h to obtain a covalent organic framework nanosheet dispersion; take 5 mL of the covalent organic framework nanosheet dispersion and mix it with 5 mL of 0.2 wt% Nafion dispersion uniformly dispersed in ethanol, and ultrasonically disperse for 1 h in an ice-water bath at 0 °C to obtain an ion-functionalized covalent organic framework nanosheet-regulated ionomer dispersion mixture C2;

[0066] (4) Take 5 mg of 60% Pt / C catalyst, 10 mL of a methanol:ethanol mixture (volume ratio 1:1), 50 μL of amphoteric functionalized covalent organic framework nanosheet-doped ionomer dispersion mixture C2, and 25 μL of 5 wt% Nafion solution. Mix them evenly in an ice-water bath at 0℃ and ultrasonically disperse for 1 h to prepare the cathode catalyst slurry. The anode catalyst slurry contains 6 mg of 60% Pt / C catalyst, 31 μL of 5 wt% Nafion solution, and 10 mL of an ethanol:isopropanol mixture (volume ratio 1:3). After ultrasonically dispersing the cathode and anode catalyst slurries, spray them evenly onto both sides of a Gore 15 μm proton exchange membrane to prepare the fuel cell membrane electrode, wherein the anode catalyst loading is 0.08 mg Pt / cm³. 2 The mass ratio of ionomer to catalyst carbon material in the anode catalyst layer is 0.6:1; the cathode catalyst loading is 0.08 mg Pt / cm³. 2 The ratio of cathode catalyst layer ionomer mass to catalyst carbon material is 0.6:1.

[0067] The above membrane electrode assembly was assembled into a fuel cell, and the battery performance was tested under the following conditions: the anode fuel was hydrogen with a flow rate of 0.3 slpm, the cathode oxidant was oxygen with a flow rate of 0.4 slpm, the battery temperature was 80℃, the relative humidity of the anode and cathode was 80%, and the back pressure of the anode and cathode was 150 kPa.

[0068] Comparative Example 3:

[0069] Using the same method, the difference from Example 2 is that, instead of adding zwitterionic functionalized covalent organic framework nanosheets, 5 wt% Nafion solution is used to replace the 50 μL zwitterionic functionalized covalent organic framework nanosheet-controlled ionomer dispersion mixture C2 in step (4). The catalyst is prepared as a cathode catalyst layer slurry, and the anode catalyst layer slurry is the same as in Example 1. It is sprayed onto both sides of the proton exchange membrane to prepare a fuel cell membrane electrode. The total amount of ionomers used in the cathode catalyst layer and the total amount of ionomers used in the anode are the same as those in the cathode and anode in Example 2, respectively.

[0070] Comparative Example 4:

[0071] Using the same method, the difference from Example 2 is that the covalent organic framework precursor A2 is directly exfoliated under the same conditions as in step (2) to prepare a non-ampholy functionalized covalent organic framework material (i.e., the covalent organic framework precursor A2 is ground into powder, further ball-milled for 24 hours to exfoliate the material into nanosheets, the diameter of the ball milling beads is 0.1-5 mm, the ball-to-material ratio is 10:1; after washing with methanol again, the upper dispersed nanosheets are ultrasonically dispersed at 30°C for 8 hours and then vacuum dried). This material replaces the amphoteric functionalized covalent organic framework nanosheet material B2 in step (3) to prepare the catalyst as a cathode catalyst layer slurry. The anode catalyst layer slurry is the same as in Example 2. It is sprayed onto both sides of the proton exchange membrane to prepare a fuel cell membrane electrode. The total amount of ionomers used in the cathode catalyst layer and the total amount of ionomers used in the anode are the same as those in the cathode and anode in Example 2, respectively.

[0072] The above-mentioned catalyst was used to prepare the membrane electrode, and the fuel cell performance was tested using the same method as in Example 2.

[0073] Figure 1 This is a schematic diagram illustrating the synthesis of the covalent organic framework material and its functionalization process described in this invention.

[0074] Figure 2 These are transmission electron microscope (TEM) images of the covalent organic framework material before and after charge functionalization in Example 1 of this invention. Before charge functionalization, it exhibits high crystallinity, and after functionalization, it is exfoliated into a nanosheet morphology.

[0075] Figure 3 These are atomic force microscopy images of the covalent organic framework nanosheet material before and after charge functionalization in Example 1 of the present invention. After charge functionalization, the size of the nanosheets becomes smaller and the thickness is reduced.

[0076] Figure 4 The transmission electron microscope and elemental distribution map of the catalyst interface in Example 2 of the present invention show that the ionomer thin layer and elemental distribution at the catalyst interface are uniform, which is beneficial to the construction of the proton transport network on the catalyst surface and to obtain low oxygen transport resistance.

[0077] Figure 5 The transmission electron microscope and elemental distribution diagram of the catalyst interface in Comparative Example 3 of this invention show that the addition of nonfunctionalized covalent organic framework nanosheets cannot modify or improve the distribution of ionomers in the catalyst interface layer.

[0078] Figure 6 The image shown is an atomic force microscopy (AFM) image of the catalyst interface in Example 2 of this invention. The bright areas in the adhesion force image correspond to hydrophilic regions with stronger and more uniform adhesion, indicating that under the polar solvent environment of the corresponding fuel cell operating conditions, the ionomer membrane regulated by the functionalized covalent organic framework exhibits a more uniform morphology, with no significant phase separation, and forms a thin, uniformly thick ionomer layer. Uniform proton transport and low oxygen transport resistance at the catalytic interface are beneficial for the efficient utilization of the catalyst.

[0079] Figure 7 The image shows an atomic force microscope image of the catalyst interface in Comparative Example 3 of this invention. The adhesion force image shows that the original ionomers aggregated and underwent significant phase separation in a polar solvent environment, forming hydrophilic and hydrophobic separation regions, which restricts the construction of proton transport channels at the catalyst interface and the formation of thin ionomer layers with low oxygen transport resistance.

[0080] Figure 8 The figures show the polarization curves of hydrogen-oxygen fuel cells in Example 1 and Comparative Examples 1 and 2 of this invention. Compared with Comparative Example 1, the membrane electrode with added zwitterionic functionalized covalent organic framework nanosheets in Example 1 showed significantly improved performance in the active polarization region and the mixing control region, indicating the improved catalyst utilization rate brought about by the charge functionalization of the covalent organic framework nanosheet material. The performance was also significantly improved in the mass transfer polarization region. Due to the porous structure of the covalent organic framework and the thin ionomer layer it constructed, the oxygen transport resistance was reduced, increasing the peak power density and limiting current density. In Comparative Example 2, although the membrane electrode with added non-zwitterionic functionalized covalent organic framework nanosheets showed some improvement compared to the unadded one due to the presence of the porous framework, it lacked the regulatory effect of zwitterionic functionalization on the ionomer interface. The performance improvement in the active polarization region and the mass transfer control region was limited, further demonstrating the regulatory and improving effect of zwitterionic functionalization on the interface.

[0081] Figure 9 The figures show the polarization curves of hydrogen-oxygen fuel cells in Examples 2, 3, and 4 of this invention. Similar to the trend in Example 1, the membrane electrode with added amphoteric functionalized covalent organic framework nanosheets showed significant performance improvements in the active polarization region and the mixing control region, and the performance was also improved in the mass transfer polarization region. In Comparative Example 4, the non-charge functionalized covalent organic framework nanosheets failed to regulate the construction of the catalytic interface, but due to the porous structure of the covalent organic framework, the oxygen transport resistance was reduced, thereby increasing the peak power density and limiting current density.

[0082] Figure 10 The electrochemical effective active area curves, proton transport resistance curves, and oxygen transport resistance curves of Example 1 and Comparative Examples 1 and 2 of the present invention are shown. The ionomer regulation method of the present invention improves the electrochemical effective active area of ​​the catalyst in fuel cell devices by constructing a more complete proton transport network and reducing the oxygen transport resistance at the catalyst layer interface, thereby improving the catalyst utilization rate.

[0083] Example 3

[0084] (1) 0.2 mmol of terephthalaldehyde was dissolved in 1.5 mL of 1,4-dioxane solvent, and 0.3 mmol of 2,6-diaminopyridine was dissolved in 1.5 mL of o-dichlorobenzene solvent. After freezing-vacuuming-thawing cycle, the mixture was sealed and subjected to polymerization reaction in an oil bath at 120℃ for 72 h. 0.5 mol / L NaCl aqueous solution was added for precipitation. The mixture was washed three times with methanol-tetrahydrofuran-acetone. After separation and washing, the mixture was dried under vacuum at 80℃ to synthesize the covalent organic framework precursor A3.

[0085] (2) Take 100 mg of the synthesized covalent organic framework precursor A3 and add it to a mixed solution of acetonitrile:chloroform with a volume ratio of 3:1. Disperse it ultrasonically for 1 h, add 6.25 uL of 1,4-butanesulfonate lactone, and react at 120 °C for 12 h to carry out the grafting of amphoteric functionalization reaction. Add 0.5 mol / L NaCl for precipitation, centrifuge and filter, and add acetonitrile, tetrahydrofuran and methanol for washing respectively. Vacuum dry and grind into powder, and further ball mill for 24 h to exfoliate the material into nanosheets. After washing with methanol again, ultrasonically disperse at 30 °C for 8 h and take the upper dispersed nanosheets. After vacuum drying, the amphoteric functionalized covalent organic framework material B3 is obtained.

[0086] (3) Take 0.5 mg of amphoteric functionalized covalent organic framework nanosheet material B3, add it to 20 mL of a mixed solution with a volume ratio of ethanol: n-propanol of 1:3, and ultrasonically disperse for 1 h to obtain a covalent organic framework nanosheet dispersion; take 5 mL of the covalent organic framework nanosheet dispersion and mix it with 5 mL of 0.2 wt% Nafion dispersion uniformly dispersed in ethanol, ultrasonically disperse for 1 h in an ice-water bath at 0 °C, and self-assemble to obtain an ionomer dispersion mixture C3 of amphoteric functionalized covalent organic framework nanosheet controlled doping;

[0087] (4) Take 20 mg of iridium oxide catalyst, 5 mL of isopropanol solution, 120 μL of amphoteric functionalized covalent organic framework nanosheet-doped ionomer dispersion mixture C3, and 150 μL of 5 wt% Nafion solution. Mix them evenly in an ice-water bath at 0 °C and ultrasonically disperse for 1 h to prepare an anode catalyst slurry for water electrolysis. After ultrasonic dispersion, the slurry is uniformly sprayed onto the porous transport layer of the anode. The cathode catalyst layer slurry contains 6 mg of 40% Pt / C catalyst, 89 μL of 5 wt% Nafion solution, and 5 mL of a water:isopropanol mixture with a volume ratio of 1:1. After ultrasonic dispersion, it is uniformly sprayed onto one side of the Nafion 115 proton exchange membrane and assembled with the porous transport layer to prepare an acidic water electrolysis membrane electrode, wherein the anode loading is 1 mg Ir / cm 2 The cathode loading is 0.4 mg Pt / cm³. 2 The ratio of ionomer mass in the anode catalyst layer to catalyst mass is 0.35:1, and the ratio of ionomer mass in the cathode catalyst layer to catalyst carbon material mass is 1.15:1.

[0088] Comparative Example 5:

[0089] Using the same method, the difference from Example 3 is that, instead of adding amphoteric functionalized covalent organic framework nanosheets, 5% wt Nafion solution is used to directly replace the 120 μL of amphoteric functionalized covalent organic framework nanosheet-controlled ionomer dispersion mixture C3 in step (4). The amount of Nafion solution used satisfies the ratio of ionomer mass to catalyst mass of anode catalyst layer = 0.8:1. The catalyst is prepared as a slurry and sprayed onto the porous transport layer. The cathode catalyst layer slurry is the same as in Example 3 and is prepared as an acidic water electrolysis membrane electrode using the same method.

[0090] The above membrane electrode was assembled into a water electrolysis device for performance testing. The electrolyte was high-purity deionized water, and the temperature was 80°C.

[0091] Figure 11 The images show the polarization curves of the proton exchange membrane electrolysis water membrane electrodes in Example 3 and Comparative Example 5 of this invention. The ionomer control method described in this invention facilitates the transport of oxygen and water molecules through the ordered porous structure of COF nanosheets, reducing mass transfer resistance and thus lowering polarization loss. The polarization curves exhibit lower overpotential and higher current density.

[0092] Consistent with Example 2, the amphoteric functionalized covalent organic framework nanosheet material, as a catalytic interface additive, effectively improves the performance of water electrolysis devices, stabilizes the interfacial catalytic utilization rate, and enhances the durability of water electrolysis membrane electrodes.

[0093] Example 4

[0094] (1) 0.2 mmol of 5'-(4-formylphenyl)-[1,1':3',1”-triphenyl]-4,4”-dicarboxaldehyde was dissolved in 1.5 mL of chloroform, and 0.3 mmol of 3,8-diamino-6-phenylphenanthridine was dissolved in 1.5 mL of 1,4-dioxane. After freezing-vacuuming-thawing cycles, the mixture was sealed and subjected to polymerization at 110 °C for 72 h in an oil bath. 0.5 mol / L NaCl aqueous solution was added for precipitation. The mixture was washed three times with methanol-tetrahydrofuran-acetone. After separation and washing, the mixture was dried under vacuum at 80 °C to synthesize the covalent organic framework precursor A4.

[0095] (2) Take 100 mg of the synthesized covalent organic framework precursor A4 and add it to a mixed solution of acetonitrile:chloroform with a volume ratio of 3:1. Disperse it ultrasonically for 1 h, add 6.25 uL of 1,3-propanesulfonic acid lactone, and react at 120 °C for 12 h to carry out the grafting of amphoteric functionalization reaction. Add 0.5 mol / L NaCl for precipitation, centrifuge and filter, and then add acetonitrile, tetrahydrofuran and methanol for washing respectively. Vacuum dry and grind into powder, and further ball mill for 24 h to exfoliate the material into nanosheets. The diameter of the ball milling beads ranges from 0.1 to 5 mm and the ball-to-material ratio is 10:1. After washing with methanol again, ultrasonically disperse at 30 °C for 8 h and take the upper dispersed nanosheets. After vacuum drying, the amphoteric functionalized covalent organic framework material B4 is obtained.

[0096] (3) Take 0.5 mg of amphoteric functionalized covalent organic framework nanosheet material B4, add it to 20 mL of a mixed solution with a volume ratio of ethanol: n-propanol of 1:3, and ultrasonically disperse for 1 h to obtain a covalent organic framework nanosheet dispersion; take 5 mL of the covalent organic framework nanosheet dispersion and 3 mL of a mixed solution of 2 wt% polybenzimidazole and 5% KOH uniformly dispersed in ethanol, mix them evenly, ultrasonically disperse for 1 h in an ice-water bath at 0 °C, and self-assemble to obtain an ionomer dispersion mixture C4 of amphoteric functionalized covalent organic framework nanosheet controlled doping;

[0097] (4) Take 50 mg of NiFe-LDH catalyst, 5 mL of isopropanol solution, 120 μL of amphoteric functionalized covalent organic framework nanosheet-doped ionomer dispersion mixture C4, and 150 μL of a mixed aqueous solution of 2 wt% polybenzimidazole and 5 wt% KOH. Mix them evenly in an ice-water bath at 0 °C and ultrasonically disperse for 1 h to prepare an anode catalyst slurry for water electrolysis. After ultrasonic dispersion, the slurry is uniformly sprayed onto the porous transport layer of the anode. The cathode catalyst layer slurry contains 6 mg of 40% Pt / C catalyst, 89 μL of 5 wt% Nafion solution, and 5 mL of a mixed solution of water and isopropanol with a volume ratio of 1:1. After ultrasonic dispersion, it is uniformly sprayed onto one side of the polyetheretherketone membrane and assembled with the porous transport layer to prepare an acidic water electrolysis membrane electrode, wherein the anode catalyst loading is 4 mg / cm³. 2 The cathode loading is 0.4 mg Pt / cm³. 2 The ratio of the mass of the cathode catalyst layer ionomer to the mass of the carbon material in the catalyst is 1.15:1.

[0098] The membrane electrode was used in the testing of water electrolysis devices. The electrolyte was a 0.1M KOH solution, and the test temperature was 80℃.

[0099] Consistent with Example 3, functionalized covalent organic framework nanosheets, as catalytic interface additives, effectively improve the performance of anion exchange membrane water electrolysis devices, stabilize the interfacial catalytic utilization rate, and enhance the durability of water electrolysis membrane electrodes.

[0100] Therefore, the method for regulating the ionomer at the catalytic interface of the hydrogen / electroconversion system provided by this invention can easily and effectively improve the performance of hydrogen / electroconversion system devices and effectively address the problem of low utilization and conversion rate of highly active catalysts in electrochemical devices.

[0101] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. A method for controlling the interfacial ionomers of a catalyst in a hydrogen / electroconversion system, characterized in that... Includes the following steps: (1) Preparation of covalent organic framework precursor: Dissolve organic monomers in organic solvent, mix to obtain reaction mixture, and then seal for polymerization reaction to obtain covalent organic framework precursor; (2) Preparation of functionalized covalent organic framework nanosheets: The covalent organic framework precursor synthesized in step (1) is added to a solvent, and then a functionalizing material is added to functionalize the covalent organic framework precursor. After separation and purification, it is peeled off into nanosheets to obtain functionalized covalent organic framework nanosheets. (3) Preparation of ionomer dispersion regulated by functionalized covalent organic framework nanosheets: functionalized covalent organic framework nanosheets were dispersed in a solvent, and then ionomers were added to mix and self-assemble to obtain ionomer dispersion regulated by functionalized covalent organic framework nanosheets. (4) Constructing an electrochemical engineering catalytic interface: The catalyst, solvent, ionomer and functionalized covalent organic framework nanosheet-controlled ionomer dispersion are mixed to obtain a functionalized catalyst slurry. The functionalized catalyst slurry is sprayed or scraped onto one or both sides of the proton exchange membrane surface to prepare a catalytic layer or related membrane electrode.

2. The method for controlling the interfacial ionomers of the catalyst in the hydrogen / electroconversion system according to claim 1, characterized in that: In step (1), the organic monomers include aldehyde monomers and amino monomers, wherein the aldehyde monomers include one of terephthalaldehyde, 2,4,6-tris(4-aldehydephenyl)-1,3,5-triazine, 5'-(4-formylphenyl)-[1,1':3',1”-triphenyl]-4,4”-dicarboxaldehyde, 1,3,5-benzenetricarboxaldehyde, tris(4-formylphenyl)amine, and 4,4,4,4-(pyrene-1,3,6,8-tetramethyl)tetrabenzaldehyde; the amino monomers include one of 2,5-diaminopyridine, 2,6-diaminopyridine, 3,8-diamino-6-phenylphenanthridine, [3,3'-bipyridine]-6,6'-diamine, 1,10-phenanthroline-3,8-diamine, and acridine-2,6-diamine; the molar ratio of the aldehyde monomer to the amino monomer is 1:0.5-2; The organic solvent mentioned in step (1) includes one or more of the following: mesitylene, 1,4-dioxane, acetic acid, n-butanol, dioxane, o-dichlorobenzene, and tetrahydrofuran; The polymerization reaction conditions described in step (1) are: reaction temperature 80-150℃, time 10-100h.

3. The method for controlling the interfacial ionomers of the catalyst in the hydrogen / electroconversion system according to claim 1, characterized in that: The charge-functionalized material mentioned in step (2) is at least one of 1,3-propanesulfonate lactone, propenyl-1,3-sulfonate lactone, 1,4-butanesulfonate lactone, and 1,8-naphthalenesulfonate lactone.

4. The method for controlling the interfacial ionomers of the catalyst in the hydrogen / electroconversion system according to claim 1, characterized in that: The solvent mentioned in step (2) includes at least one of dimethyl sulfoxide, N,N-dimethylformamide, tetrahydrofuran, acetonitrile, n-hexanol, toluene, chloroform, and water; The mass ratio of the covalent organic framework precursor to the functionalized material in step (2) is 1:0.04-0.12; the functionalization in step (2) refers to the reaction at 80-120℃ for 12-48h.

5. The method for controlling the interfacial ionomers of the catalyst in the hydrogen / electroconversion system according to claim 1, characterized in that: The peeling mentioned in step (2) refers to peeling by at least one of ball milling and ultrasonic dispersion; wherein the diameter of the ball milling beads is 0.1-5 mm, the ball-to-material ratio is 10-20:1, and the ball milling time is 12-72 h; the ultrasonic dispersion temperature is 30-80℃, and the time is 30 min-12 h.

6. The method for controlling the interfacial ionomers of the catalyst in the hydrogen / electroconversion system according to claim 1, characterized in that: In step (3), the solvent includes at least one of ethanol, isopropanol, n-propanol, and acetone; The ionomer mentioned in step (3) includes at least one of perfluorosulfonic acid resin, sulfonated polyether ether ketone, sulfonated polystyrene, sulfonated polyimide, sulfonated polyether, sulfonated polytetrafluoroethylene, and polybenzimidazole; In the ionomer dispersion regulated by functionalized covalent organic framework nanosheets described in step (3), the concentration of ionomer ranges from 0.1wt% to 5wt%, and the concentration of functionalized covalent organic framework nanosheets ranges from 0.0001wt% to 20wt%. The mixing for self-assembly mentioned in step (3) refers to sonication at a temperature of 0-80℃ for 2 min-12 h to carry out self-assembly.

7. The method for controlling the interfacial ionomers of the catalyst in the hydrogen / electroconversion system according to claim 1, characterized in that: In step (4), the catalyst includes one of acidic / basic ORR catalyst and acidic / basic OER catalyst. The ORR catalyst includes at least one of Pt / C catalyst, Ru / C catalyst, PtCo-based catalyst, PtNi-based catalyst, Fe-NC catalyst, and Co-NC catalyst. The OER catalyst includes at least one of Ru or Ir-based acidic OER catalyst and Co, Ni, or Fe-based transition metal and their oxide basic OER catalyst. The solvent is one or more of water, ethanol, n-propanol, and isopropanol. The ionomer in step (4) includes at least one of perfluorosulfonic acid resin, sulfonated polyether ether ketone, sulfonated polystyrene, sulfonated polyimide, sulfonated polyether, sulfonated polytetrafluoroethylene, and polybenzimidazole.

8. The method for controlling the interfacial ionomers of the catalyst in the hydrogen / electroconversion system according to claim 1, characterized in that: In the functionalized catalyst slurry described in step (4), the dry weight ratio of functionalized covalent organic framework nanosheets is 0.001-5wt%, the mass ratio of ionomer to functionalized covalent organic framework nanosheets is 1:0.0001-1:5, the concentration of catalyst is 0.01-25wt%, and the mass ratio of ionomer to catalyst or carbon material in catalyst is 0.2:1-0.8:

1.

9. A catalytic layer or membrane electrode for a hydrogen / electroconversion system prepared by the method according to any one of claims 1-8.

10. The application of the catalytic layer or membrane electrode of the hydrogen / electric conversion system according to claim 9 in proton exchange membrane fuel cells, anion exchange membrane fuel cells, proton exchange membrane water electrolysis, and anion exchange membrane water electrolysis.

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