WO2023010772A1

WO2023010772A1 - Her catalyst containing protective layer and electrode prepared using same

Info

Publication number: WO2023010772A1
Application number: PCT/CN2021/140998
Authority: WO
Inventors: 张畅; 王金意; 任志博; 王鹏杰; 余智勇; 徐显明; 张欢
Original assignee: 中国华能集团清洁能源技术研究院有限公司; 四川华能氢能科技有限公司; 华能集团技术创新中心有限公司; 四川华能太平驿水电有限责任公司; 四川华能宝兴河水电有限责任公司; 四川华能嘉陵江水电有限责任公司; 四川华能东西关水电股份有限公司; 四川华能康定水电有限责任公司; 四川华能涪江水电有限责任公司; 华能明台电力有限责任公司
Priority date: 2021-07-31
Filing date: 2021-12-23
Publication date: 2023-02-09
Also published as: CN113564634A; CN113564634B

Abstract

The present application provides an HER catalyst preparation method and an HER catalyst prepared thereby, and an electrode preparation method using the HER catalyst and an electrode prepared thereby. The HER catalyst preparation method comprises: adding a porous COF material and a ligand salt into a mixed solution of water and ethanol and stirring the mixture for mixing uniformly; adding urea into the uniformly mixed solution to obtain a reaction solution; adding the reaction solution into a hydrothermal kettle for sealing reaction, collecting the precipitate, and washing and drying same; and heating and reducing the dried product in a reducing atmosphere to obtain the catalyst.

Description

HER catalyst with protective layer and electrode prepared therefrom

Cross References to Related Applications

This application is based on a Chinese patent application with application number 202110877173.1 and a filing date of July 31, 2021, and claims the priority of this Chinese patent application. The entire content of this Chinese patent application is hereby incorporated by reference into this application.

technical field

The present application relates to the technical field of catalyst preparation, in particular to a method for preparing a HER catalyst and the prepared catalyst, a method for preparing an electrode, and the prepared electrode.

Background technique

Non-precious metal HER catalysts have poor stability under acidic conditions, which limits their application range, and are easy to passivate and fall off during use, resulting in agglomeration and affecting the catalytic performance of hydrogen evolution.

The use of carbon layer coating for protection is a commonly used strategy at present, but the formation of carbon layer is often accompanied by high-temperature calcination, which will adversely affect the activity of particles. There is no universal rule to follow for the structural regulation of the protective layer itself from several aspects such as increasing proton conduction, enhancing stability, and interfacial charge synergy.

COF (covalent organic framework, covalent organic framework) is an ordered porous crystalline structure constructed by covalent bonds, with ordered proton transport channels, controllable structure, adjustable functional modification components, and various The constituent unit of the. At present, COF is generally used as a potential material of proton exchange membrane in the field of hydrogen production, and there is no HER electrocatalytic material with COF as the protective layer.

Contents of the invention

This application aims to solve one of the technical problems in the related art at least to a certain extent.

To this end, in the first aspect of the present application, a method for preparing a HER catalyst is proposed, comprising: adding a porous covalent organic framework (COF) material and a ligand salt to a mixed solution of water and ethanol and stirring to mix uniformly adding urea to the uniformly mixed solution to obtain a reaction solution; adding the reaction solution into a hydrothermal kettle to seal the reaction, collecting the precipitate, washing and drying; and heating and reducing the dried product in a reducing atmosphere to obtain a catalyst.

In an embodiment, the method further includes preparing the COF material. The preparation of the COF material includes: mixing an organic framework, a small molecule organic acid and a solvent, adding a polar aqueous solution to it, ultrasonically mixing it uniformly, then heating at a low temperature under an inert atmosphere, and then filtering, washing and drying to obtain a COF material.

In an embodiment, during the low-temperature heating period, the heating temperature is 100-150° C., and the heating time is 72 hours.

In an embodiment, the organic skeleton and the small molecule organic acid are added in a molar ratio of 0.5-1:1.

In an embodiment, the ratio between the mass of the organic framework and the small molecule organic acid and the volume of the solvent is 10-30 g: 1 L.

In an embodiment, the volume ratio of the polar aqueous solution to the solvent is 1:4-6.

In an embodiment, the solvent is prepared by mixing a strong polar solvent and a weak polar solvent at a volume ratio of 1:0-5.

In an embodiment, the organic skeleton is selected from monocyclic or polycyclic aromatic substances, heterocycles, and derivatives modified by various groups.

In an embodiment, the small molecule organic acid is one of sulfonic acid organic compounds, phosphoric acid organic compounds, amino organic compounds, silicic acid organic compounds or boric acid organic compounds.

In an embodiment, the COF material and the ligand salt are mixed in a mass ratio of 1-3:1.

In an embodiment, the solid content of the COF material and the ligand salt in the mixed solution of water and ethanol is 0.2-1 g/mL.

In an embodiment, the urea and the ligand salt are mixed in a molar ratio of 1:5-8.

In an embodiment, the ligand salt is one or more of metal nitrate, metal chloride or metal formate.

In an embodiment, water and ethanol are mixed in a volume ratio of 1:1-3.

In an embodiment, the reaction solution is added into a hydrothermal kettle to seal the reaction process. The volume ratio of the reaction solution to the hydrothermal kettle is 2/3-4/5, the reaction temperature is 100-120°C, and the reaction time is 12-36h .

In an embodiment, the reducing atmosphere is hydrogen, the reducing temperature is 200-300° C., and the reducing time is 20-60 minutes.

In the second aspect of the present application, a HER catalyst is proposed, which is prepared by the above-mentioned method for preparing a HER catalyst, and has COF as a protective layer.

In the third aspect of the present application, a method for preparing an electrode is proposed, including: mixing and dispersing the above-mentioned HER catalyst and a dispersion solvent to obtain a dispersion; and uniformly dripping the dispersion on the surface of the electrode substrate, and then drying.

In an embodiment, the solid content of the HER catalyst in the dispersion is 0.1-1 g/mL.

In an embodiment, the dispersion solvent is prepared by mixing water and ethanol at a volume ratio of 1:1-3.

In an embodiment, the electrode substrate material is one of stainless steel, titanium, Raney nickel or carbon material.

In the fourth aspect of the present application, an electrode is provided, which is prepared by the above-mentioned method for preparing an electrode.

Additional aspects and advantages of the application will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the application.

Description of drawings

The above and/or additional aspects and advantages of the present application will become apparent and easy to understand from the following description of the embodiments in conjunction with the accompanying drawings, wherein:

Fig. 1 is a flowchart of a method for preparing a HER catalyst according to an embodiment of the present application;

Figure 2 is a flowchart of a method for preparing a HER catalyst according to another embodiment of the present application; and

Fig. 3 is a flowchart of an electrode preparation method proposed according to another embodiment of the present application.

Detailed ways

Embodiments of the present invention are described in detail below. The embodiments described below are exemplary only for explaining the present invention and should not be construed as limiting the present invention.

The solutions of the present invention will be explained below in conjunction with examples. Those skilled in the art will understand that the following examples are only for illustrating the present invention and should not be considered as limiting the scope of the present invention. If no specific technique or condition is indicated in the examples, it shall be carried out according to the technique or condition described in the literature in this field or according to the product specification. The reagents or instruments used were not indicated by the manufacturer, and they were all commercially available conventional products.

In this application, in order to solve the problems existing in the current technical field, a method for preparing a HER catalyst and a HER catalyst, and a method and an electrode for preparing an electrode using the HER catalyst are proposed. The catalyst is prepared by preparing a COF material with a porous structure, and then loading metal particles in the pore structure of the COF material. Through the protective effect of the outer structure of the COF, the catalytic stability of the metal particles under acidic conditions can be guaranteed. At the same time, due to the COF material The porous properties allow the protons to be effectively transferred from the electrolyte to the surface of the metal particles without affecting the catalytic performance of the metal particles.

In the first aspect of the present application a method for preparing a HER catalyst comprising a protective layer is proposed. As shown in Figure 1, the method includes:

S101, adding the porous COF material and the ligand salt into the mixed solution of water and ethanol and stirring to mix evenly;

S102, adding urea to the uniformly mixed solution, and mixing to obtain a reaction solution;

S103, adding the reaction solution into a hydrothermal kettle to seal the reaction, collecting the precipitate, washing and drying; and

S104, heating and reducing the dried product in a reducing atmosphere to obtain a catalyst.

In this application, the heteroatoms in COF, such as B, N, P, S, have higher electron density and are easy to attract metal cations to play an anchoring role. The added metal ligand salt is uniformly dispersed in the COF during the uniform stirring process, and then the metal oxide is formed in situ during the hydrothermal process. Then under the reducing atmosphere, the metal oxides are reduced to metal particles with catalytic properties.

In this application, COF plays the role of a dispersed carrier in the synthesis process, avoiding the agglomeration of metal oxide particles during the synthesis process, and is conducive to the formation of uniform nanoparticles with a large active specific surface area and reaction utilization. The COF layer forms a protective layer on the outside of the reduced metal particles to prevent corrosion in an acidic environment, as well as the agglomeration, shedding, passivation or loss of metal particles during the reaction process. The combination of metal and non-metal enhances the charge transfer effect, and the COF layer has good proton transport ability, which can effectively transfer protons from the electrolyte to the surface of the metal particles while protecting the metal in the internal pores, without affecting the catalytic performance of the metal particles. performance.

In this application, since the COF material has a porous structure, the metal particles are loaded in the pores of the COF material through the reaction. The nano-metal particles in the pores have an electrocatalytic effect, and the outer shell is a COF layer. The protective effect of the COF layer can effectively prevent The metal particles are directly immersed in the acid solution to react, which makes the stability of the catalyst poor. At the same time, COF is used as the outer protective layer. As COF is used as a precursor, it can be combined with a variety of metals, and it has strong universality. The combination of COF enhances the charge transfer effect, and the COF layer has good proton transport ability, which can effectively transfer protons from the electrolyte to the surface of the metal particles while protecting the metal in the internal pores, without affecting the catalytic performance of the metal particles. The protection of COF can avoid the passivation of particles during use and improve the catalytic effect of HER.

As shown in FIG. 2 , the preparation method of the present application further includes: S205, preparing a COF material. S201-S204 in FIG. 2 are the same as S101-S104 in FIG. 1 , and will not be repeated here.

Specifically, the preparation of the COF material of S205 may include: after mixing the organic framework, small molecule organic acid and solvent, adding a polar aqueous solution to it, ultrasonically mixing, and then heating at low temperature under an inert atmosphere, and then filtering, washing and drying, Obtain COF material.

By controlling the composition and content of the organic framework and small molecule organic acids, the composition of the COF material can be changed. By introducing heteroatoms B, N, P or S into the COF, the heteroatoms can react with the ligand metal, thereby making the metal particles Loaded inside the pores of the COF material, by controlling the preparation method of the COF material, the prepared COF layer has a porous structure, and the metal nanoparticles are loaded in the pore structure, which can be used as a dispersant for the metal nanoparticles to prevent the particles from being in the process of processing and catalysis. The agglomeration, and the hierarchical pore structure is conducive to good gas diffusion and charge transfer, and improves the electrocatalytic reaction effect.

In some embodiments, the organic framework and the small molecule organic acid are added in a molar ratio of 0.5-1:1. The ratio between the mass of the organic skeleton and the small molecule organic acid and the volume of the solvent is 10-30g:1L. The volume ratio of the polar aqueous solution and the solvent is 1:4-6. The solvent is prepared by mixing a strong polar solvent and a weak polar solvent at a volume ratio of 1:0-5, and the solvent is a common organic solvent, such as nitriles, alcohols, acids, esters, amines, haloalkanes, Benzene and its derivatives.

In some embodiments, the organic skeleton is monocyclic or polycyclic aromatic-based substances and derivatives modified by heterocyclic and various groups; that is, the organic skeleton is monocyclic aromatic-based substances, polycyclic aromatic-based substances, heterocyclic Derivatives of ring-modified monocyclic aromatic substances, derivatives of heterocyclic-modified polycyclic aromatic substances, derivatives of various group-modified monocyclic aromatic substances, various group-modified polycyclic aromatic substances One of the derivatives of a substance. That is to say, the organic skeleton can be organic substances such as benzenes, anthracenes, phenols, pyridines, pyrimidines, and triazines.

In some embodiments, the small molecule organic acid is one of sulfonic acid organic compounds, phosphoric acid organic compounds, amino organic compounds, silicic acid organic compounds or boric acid organic compounds.

By changing the type of organic framework and small molecule organic acid, the composition of each element in the COF material is changed, thereby changing its binding effect with the ligand metal. By controlling the type of organic framework and small molecule organic acid, the ligand metal It can be firmly combined and evenly dispersed on COF materials.

In some embodiments, when heating at a low temperature under an inert atmosphere, the heating temperature is 100-150° C., and the heating time is 72 hours. During the filtration washing and drying process, the formed precipitate was collected by filtration, and residual monomers were removed with organic solvents dioxane, ethanol and acetone.

In some embodiments, the COF material and the ligand salt are mixed in a mass ratio of 1-3:1. The solid content of the COF material and ligand salt in water and ethanol is 0.2-1 g/mL. The urea and the ligand salt are mixed according to a molar ratio of 1:5-8.

In some embodiments, the ligand salt is one or more of metal nitrate, metal chloride, and metal formate; the corresponding metal element can be one of nickel, cobalt, iron, molybdenum, and manganese. One or more, that is, the metal nitrate can be one or more of nickel nitrate, cobalt nitrate, iron nitrate, molybdenum nitrate, and manganese nitrate.

In some embodiments, the water and ethanol are mixed in a volume ratio of 1:1-3.

In some embodiments, the reaction solution is added into a hydrothermal kettle to seal the reaction process. The volume ratio of the reaction solution to the hydrothermal kettle is 2/3-4/5, the reaction temperature is 100-120°C, and the reaction time is 12- 36h.

It can be seen that COF is used as a carrier in the catalyst preparation process, and metal particles are directly loaded in the COF pores. The reaction conditions are mild during the loading process, and the damage to the catalytic performance of the particles by high temperature is avoided. Moreover, the protective effect of the COF protective layer is good; the proton passing rate is high, and the influence on the catalytic performance of the core metal is small. The composition of the COF protective layer is highly adjustable and can be designed according to the chemical properties and physical morphology of the core metal to achieve the purpose of interface regulation and enhanced HER charge transport.

In some embodiments, the reducing atmosphere is hydrogen, the reducing temperature is 200-300° C., and the reducing time is 20-60 minutes.

The reduction reaction is carried out by hydrogen, so that the metal ions loaded in the pores of the COF material are reduced to nano-metal particles to realize the catalytic effect.

In another aspect of the present application a method for preparing an electrode is presented. As shown in Figure 3, the method includes:

S301, mixing and dispersing the above HER catalyst and a dispersion solvent to obtain a dispersion liquid; and

S302, uniformly drop the dispersion liquid on the surface of the electrode substrate, and then dry it.

By dripping the dispersion on the surface of the electrode substrate and then drying it, the surface of the electrode substrate is covered with a catalytic layer to form a composite electrode. At the same time, the catalytic layer is not easy to fall off, which can improve the stability of the composite electrode and catalyze The catalytic metal particles in the layer are loaded in the pore structure of the COF material. Through the protection of the COF material, the acid resistance of the catalytic layer can be improved to achieve a stable catalytic effect.

In some embodiments, the solid content of the HER catalyst in the dispersion is 0.1-1 g/mL. The dispersing solvent is prepared by mixing water and ethanol at a volume ratio of 1:1-3. The electrode substrate material is one of stainless steel, titanium, Raney nickel or carbon material; the drying condition is vacuum drying at 80-100° C. for more than 12 hours.

It should be understood that the technical features and technical effects described in the method embodiments of the present application are also applicable to the product embodiments of the present application, and will not be repeated here.

In the following, the method proposed in the present application, the prepared HER catalyst, and the electrode prepared by using the HER catalyst will be described in detail in combination with the following specific examples.

Embodiment 1: the preparation of HER catalyst:

Preparation of COF material: Add organic framework 2,4,6-triformylphloroglucinol and small molecule organic acid 2,5-diaminobenzenesulfonic acid into a heat-resistant container at a molar ratio of 0.7:1, and simultaneously add Add a solvent (a mixture of n-butanol and o-dichlorobenzene at a ratio of 1:1) to a heat-resistant container, and control adding 20 g of 2,4,6-triformylphloroglucinol and small molecule organic acid 2,5- A mixture of diaminobenzenesulfonic acid, add ethanol water solution (ethanol: water = 1:1, volume ratio) to it, control the volume ratio of ethanol water solution and solvent to 1:5, and then sonicate the reaction mixture to obtain a uniform suspension Liquid; heat the reaction tube in the container to 100°C under an inert atmosphere, continue heating for 72h, then filter and collect the formed precipitate, remove residual monomers with organic solvents dioxane, ethanol and acetone, in Vacuum drying at 100°C for more than 12 hours to obtain COF materials;

Add 1g of ferric nitrate and 2g of COF material into a mixed solution of 5mL of water and 5mL of ethanol and stir to mix evenly;

Add urea to the uniformly mixed solution (the amount of urea substance: the amount of ligand salt substance = 1:6), and mix to obtain a reaction solution;

Put the reaction solution into the hydrothermal kettle and seal it, control the volume ratio of the reaction solution and the hydrothermal kettle to 2/3-4/5, then place the hydrothermal kettle at 100-120°C to heat the reaction for 12-36h, and collect the precipitate after the reaction items, washed and dried in vacuum.

The dried product was heated and reduced in hydrogen, the heating temperature was controlled to be 250° C., and the reaction time was 50 minutes to obtain a catalyst.

Embodiment 2: the preparation of HER catalyst

Preparation of COF materials: Add organic framework 1,4,5,8-tetrahydroxyanthraquinone and tetramethyl orthosilicate into a heat-resistant container at a ratio of 0.5:1, and simultaneously add Add methanol, control every liter of methanol and add 22g of the mixture of 2,3,6,7-tetrahydroxyanthraquinone and tetramethyl orthosilicate; then the reaction mixture is sonicated to obtain a uniform suspension; the resulting suspension Heat the reaction tube in the container to 120°C under an inert atmosphere, continue heating for 72h, then filter and collect the formed precipitate, remove residual monomers with ethanol and acetone, and vacuum dry at 100°C for more than 12 hours to obtain a COF material ;

Add 0.5g of nickel nitrate, 0.5g of ferric nitrate and 2g of COF material into a mixed solution of 5mL of water and 5mL of ethanol and stir to mix evenly;

Comparative example 1: the preparation of catalyst:

The nickel nitrate aqueous solution of 25g/L is added in the heat-resistant reaction vessel, then adds ethanol aqueous solution (the volume ratio of ethanol aqueous solution and nickel nitrate aqueous solution is 1:5) wherein, adds urea (the amount of urea substance: part salt substance Amount = 1:6), fully mixed to obtain a uniform suspension;

Heat the reaction vessel to 100-150°C for 72 hours under an inert atmosphere. After the reaction, filter the product to collect the formed precipitate, then wash with ethanol and water for 2-3 times, and then vacuum dry at 80-100°C for 12 hours. above;

The material obtained after drying was heated and reduced at 250° C. for 40 min under a reducing atmosphere to obtain a catalyst.

Comparative example 2: the preparation of catalyst:

The preparation method of catalyst is the same as the method of comparative example 1, the nickel nitrate aqueous solution of 25g/L in comparative example 1 is replaced with the nickel nitrate and ferric nitrate mixed solution of 25g/L, simultaneously the quality of nickel nitrate and ferric nitrate is identical .

The HER catalysts and comparative catalysts prepared in the above examples were used to prepare electrolytic hydrogen electrodes, and the specific preparation process is described in detail through the following examples.

The electrode prepared by the catalyst of embodiment 1:

A specific preparation process for preparing an electrolytic hydrogen electrode using the HER catalyst prepared in Example 1 is as follows:

Mix and disperse 0.3 g of the HER catalyst prepared in Example 1 with 0.5 mL of water and 0.5 mL of ethanol to obtain a dispersion;

The dispersion liquid is evenly added dropwise on the surface of the carbon electrode plate, and then vacuum-dried at 80-100°C for more than 12 hours, and a catalyst layer is compounded on the surface of the prepared composite electrode.

The electrode prepared by the catalyst of embodiment 2:

A specific preparation process for preparing an electrolytic hydrogen electrode using the HER catalyst prepared in Example 2 is as follows:

Mix and disperse 0.1 g of the HER catalyst prepared in Example 2 with 0.5 mL of water and 0.5 mL of ethanol to obtain a dispersion;

The electrode prepared by the catalyst of comparative example 1:

The preparation process of the electrode is the same as that of the electrode prepared by the catalyst in Example 1.

The electrode prepared by the catalyst of comparative example 2:

The preparation process of this electrode is the same as that of the electrode prepared by the catalyst in Example 2.

The performance of the electrodes prepared in the above examples was tested, and the specific test results are shown in Table 1.

The hydrogen evolution overpotential of the electrolytic hydrogen production electrode was tested in a standard three-electrode system connected to an electrochemical workstation, with a platinum electrode as an auxiliary electrode and a mercury-mercury oxide electrode as a reference electrode. All tests were carried out at 25°C, and the electrolyte was 0.5M _H2SO4 _solution . The voltage scanning speed is 10mV/s, and the current density is set at 10mA/cm ² or 100mA/cm ² . In addition, the performance attenuation of the electrode is judged by the rate of change of the hydrogen evolution overpotential after working at a constant current density for a period of time. The specific method is: measure the hydrogen evolution overpotential η ₀ at t=0; keep working at a certain current density for a period of time After that, the hydrogen evolution overpotential η _t is measured; the performance decay rate is calculated: (η _t -η ₀ )/η ₀ t. In the performance decay rate experiment, the current density was set at 100 mA/cm ² . Working time t=12h.

The performance test result of the electrode prepared by the catalyst prepared in Table 1 embodiment 1-2 and comparative example 1-2

电极类型electrode type	η ₁₀,mV η ₁₀ ,mV	η ₁₀₀,mV η ₁₀₀ ,mV	性能衰减率，％/1000hPerformance decay rate, %/1000h
实施例1催化剂制备的电极The electrode prepared by the catalyst of embodiment 1	124124	378378	0.90.9
对比例1催化剂制备的电极The electrode prepared by the catalyst of comparative example 1	132132	367367	12.412.4
实施例2催化剂制备的电极The electrode prepared by the catalyst of embodiment 2	8585	176176	0.40.4
对比例2催化剂制备的电极The electrode prepared by the catalyst of comparative example 2	9393	197197	7.57.5

It can be seen from Table 1 that the electrode voltage decay rate prepared by the catalysts prepared in Example 1 and Example 2 of the present application is not higher than 0.9%/1000h, while the electrode voltage decay rate prepared by the comparative catalyst prepared without coating the COF material Larger, reaching 12.4%/1000h.

It should be noted that in the description of the present application, terms such as "first" and "second" are used for description purposes only, and should not be understood as indicating or implying relative importance. In addition, in the description of the present application, unless otherwise specified, "plurality" means two or more.

Any process or method descriptions in flowcharts or otherwise described herein may be understood to represent modules, segments or portions of code comprising one or more executable instructions for implementing specific logical functions or steps of the process , and the scope of preferred embodiments of the present application includes additional implementations in which functions may be performed out of the order shown or discussed, including in substantially simultaneous fashion or in reverse order depending on the functions involved, which shall It should be understood by those skilled in the art to which the embodiments of the present application belong.

In the description of this specification, descriptions referring to the terms "one embodiment", "some embodiments", "example", "specific examples", or "some examples" mean that specific features described in connection with the embodiment or example , structure, material or characteristic is included in at least one embodiment or example of the present application. In this specification, schematic representations of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

Although the embodiments of the present application have been shown and described above, it can be understood that the above embodiments are exemplary and should not be construed as limitations on the present application, and those skilled in the art can make the above-mentioned The embodiments are subject to changes, modifications, substitutions and variations.

Claims

A method for preparing a HER catalyst comprising:

Adding a covalent organic framework (COF) material with a porous structure and a ligand salt into a mixed solution of water and ethanol and stirring to mix evenly;

Add urea to the uniformly mixed solution, and mix to obtain a reaction solution;

Adding the reaction solution into a hydrothermal kettle to seal the reaction and collecting the precipitate, washing and drying; and

The dried product is heated and reduced in a reducing atmosphere to obtain a catalyst.
The method according to claim 1, wherein the method further comprises preparing the COF material, and preparing the COF material comprises:

After mixing the organic framework, small molecule organic acid and solvent, add a polar aqueous solution to it, mix uniformly by ultrasonic, then heat at low temperature under an inert atmosphere, and then filter, wash and dry to obtain a COF material.
The method according to claim 2, wherein during the low-temperature heating, the heating temperature is 100-150° C., and the heating time is 72 hours.
The method according to claim 2 or 3, wherein said organic framework and small molecule organic acid are added in a molar ratio of 0.5-1:1; and/or

The ratio between the mass of the organic framework and the small molecule organic acid and the volume of the solvent is 10-30g: 1L; and/or

The volume ratio of the polar aqueous solution and the solvent is 1:4-6.
The method according to any one of claims 2-4, wherein the solvent is prepared by mixing a strong polar solvent and a weak polar solvent according to a volume ratio of 1:0-5.
The method according to any one of claims 1-5, wherein the organic skeleton is selected from monocyclic or polycyclic aromatic base substances, heterocycles, derivatives modified by various groups.
The method according to any one of claims 1-6, wherein the small molecule organic acid is one of sulfonic acid organic compounds, phosphoric acid organic compounds, amino organic compounds, silicic acid organic compounds or boric acid organic compounds.
The method according to any one of claims 1-7, wherein the COF material and the ligand salt are mixed in a mass ratio of 1-3:1; and/or

The solid content of the COF material and the ligand salt in the mixed solution of water and ethanol is 0.2-1 g/mL.
The method according to any one of claims 1-8, wherein the urea and the ligand salt are mixed according to a molar ratio of 1:5-8.
The method according to any one of claims 1-9, wherein the ligand salt is one or more of metal nitrates, metal chlorides or metal formates.
The method according to any one of claims 1-10, wherein water and ethanol are mixed in a ratio of 1:1-3 by volume.
The method as described in any one of claims 1-11, wherein said reaction solution is added into the hydrothermal kettle and the volume ratio of the reaction solution and the hydrothermal kettle during the sealing reaction is 2/3-4/5, and the reaction temperature is 100-120°C, the reaction time is 12-36h.
The method according to any one of claims 1-12, wherein the reducing atmosphere is hydrogen, the reducing temperature is 200-300°C, and the reducing time is 20-60min.
A HER catalyst, prepared by the method for preparing a HER catalyst according to any one of claims 1-13, having COF as a protective layer.
A method for preparing an electrode comprising:

mixing and dispersing the HER catalyst according to claim 14 and a dispersing solvent to obtain a dispersion; and

The dispersion liquid is evenly dripped on the surface of the electrode substrate, followed by drying.
The method according to claim 15, wherein the solid content of the HER catalyst in the dispersion is 0.1-1g/mL; and/or

The dispersing solvent is prepared by mixing water and ethanol at a volume ratio of 1:1-3.
The method according to claim 15 or 16, wherein the electrode substrate material is one of stainless steel, titanium, Raney nickel or carbon material.
An electrode prepared by the method for preparing an electrode according to any one of claims 15-17.