阅读说明：本技术 一种双功能电催化剂的制备方法及其应用 (Preparation method and application of bifunctional electrocatalyst ) 是由 白正宇 吕璐瑶 张庆 原洋 陈忠伟 于 2021-08-12 设计创作，主要内容包括：本发明公开了一种双功能电催化剂的制备方法及其应用,属于电催化材料技术领域。本发明的技术方案要点为：在高导电性一维载体壳层原位引入MOF前驱体,再与金属集流体进行稳定复合,然后通过电化学原位活化,最终制得OER/HER双功能电催化剂。本发明制备的纳米双功能电催化剂具有多级组装结构且具有多维材料复合结构特征,有利于提升双功能电催化剂OER/HER电催化活性和工作寿命,在催化水裂解上具有较好的应用前景。(The invention discloses a preparation method and application of a bifunctional electrocatalyst, and belongs to the technical field of electrocatalytic materials. The technical scheme provided by the invention has the key points that: and introducing an MOF precursor into the shell layer of the high-conductivity one-dimensional carrier in situ, then stably compounding the MOF precursor with a metal current collector, and finally preparing the OER/HER bifunctional electrocatalyst through electrochemical in-situ activation. The nanometer bifunctional electrocatalyst prepared by the invention has a multi-stage assembly structure and multi-dimensional material composite structure characteristics, is beneficial to improving the electrocatalytic activity of the bifunctional electrocatalyst OER/HER and prolonging the service life, and has a good application prospect in catalyzing water cracking.)

1. A preparation method of the bifunctional electrocatalyst is characterized in that: taking a one-dimensional conductive material with a skin-core structure as a carrier, generating a bimetallic MOF precursor containing magnetic nanoparticles in situ on a shell layer of the carrier, and then carrying out magnetic compounding with a metal current collector, then preparing nanometer double-metal hydroxide nanometer sheets through electrochemical activation, finally generating the nanometer multi-level assembled dual-function electro-catalyst with a composite low-dimensional structure and a composite high-dimensional structure, the bifunctional electrocatalyst is formed by carrying out grading multidimensional assembly on a conductive carrier with a one-dimensional skin-core structure, a bimetallic hydroxide with a two-dimensional sheet structure and a three-dimensional metal current collector, can effectively adjust the electronic structure of the electrocatalyst, expose more available active sites, enhance the synergistic effect among all components, meanwhile, the bifunctional electrocatalyst is used for electrocatalysis of OER/HER reaction, and can realize rapid charge transfer and effective substance transmission, thereby improving the electrochemical performance and the service life of the water cracking catalytic material;

the specific preparation process comprises the following steps:

step S1: adding cuprous chloride and sucrose into deionized water, stirring and mixing uniformly, transferring to a polytetrafluoroethylene reaction kettle, reacting for 36h at 160 ℃, cooling to room temperature, washing with deionized water for several times, and drying in vacuum to obtain a one-dimensional conductive material carrier, wherein the one-dimensional conductive material carrier has a skin-core structure, namely a skin layer material is carbon and an inner core material is copper;

step S2: adding the one-dimensional conductive material carrier obtained in the step S1 into ethylene glycol, sequentially adding sodium acetate, polyethylene glycol, ferric chloride hexahydrate and 1H-benzimidazole-5-carboxylic acid, stirring vigorously, transferring into a polytetrafluoroethylene reaction kettle, reacting at 170 ℃ for 6-10H, cooling to room temperature, washing with deionized water for several times, and drying in vacuum to obtain a one-dimensional conductive material carrier shell layer which is generated in situ and contains Fe₃O₄Iron-copper bimetallic MOF precursors of magnetic nanoparticles;

step S3: respectively ultrasonically cleaning a metal current collector with the size of 2cm multiplied by 4cm in deionized water, acetone and ethanol, then putting the metal current collector into the deionized water, and then adding the one-dimensional conductive material carrier shell layer obtained in the step S2 to generate a carrier shell layer containing Fe in situ₃O₄Stirring the precursor of the iron-copper bimetallic MOF of the magnetic nanoparticles for 2h at normal temperature, filtering and then carrying out vacuum drying to obtain a one-dimensional conductive material carrier shell layer which is generated in situ and contains Fe₃O₄A magnetic composite material of an iron-copper bimetallic MOF precursor of the magnetic nanoparticles and a metal current collector;

step S4: generating Fe in situ by using the one-dimensional conductive material carrier shell obtained in the step S3₃O₄The magnetic composite material of the iron-copper bimetallic MOF precursor of the magnetic nanoparticles and the metal current collector is used as a working electrode, an Hg/HgO electrode is used as a reference electrode, a platinum wire is used as a counter electrode, 1mol/L KOH solution is used as electrolyte, electrochemical activation is carried out, and the activation constant current is 10mA/cm²And the activation time is 700s, so that the nano iron-copper double-metal hydroxide nanosheet is prepared, and finally the nano multistage assembled dual-function electrocatalyst with a composite low-dimensional structure and a composite high-dimensional structure is prepared.

2. A method of preparing a bifunctional electrocatalyst according to claim 1, characterised in that: the reaction time in step S2 is 8-10 h.

3. A method of preparing a bifunctional electrocatalyst according to claim 1, characterised in that: the metal current collector in step S3 is nickel foam or iron foam.

4. The preparation method of the bifunctional electrocatalyst according to claim 1, characterized by comprising the specific steps of:

step S1: adding 0.9g of cuprous chloride and 28g of sucrose into 35mL of deionized water, stirring and mixing uniformly, transferring the mixture into a 500mL polytetrafluoroethylene reaction kettle, reacting for 36h at 160 ℃, cooling to room temperature, washing with deionized water for several times, and drying in vacuum to obtain a one-dimensional conductive material carrier, wherein the one-dimensional conductive material carrier has a skin-core structure, namely a skin layer material is carbon and an inner core material is copper;

step S2: adding 10mg of the one-dimensional conductive material carrier obtained in the step S1 into 40mL of ethylene glycol, sequentially adding 1560mg of sodium acetate, 590mg of polyethylene glycol, 800mg of ferric chloride hexahydrate and 900mg of 1H-benzimidazole-5-carboxylic acid, stirring vigorously for 30min, transferring into a 50mL polytetrafluoroethylene reaction kettle, reacting at 170 ℃ for 9H, cooling to room temperature, washing with deionized water for several times, and drying in vacuum to obtain a one-dimensional conductive material carrier shell layer which contains Fe and is generated in situ₃O₄Iron-copper bimetallic MOF precursors of magnetic nanoparticles;

step S3: ultrasonically cleaning foamed nickel with the size of 2cm multiplied by 4cm in deionized water, acetone and ethanol for 30min, putting the cleaned foamed nickel into 200mL of deionized water, and adding the one-dimensional conductive material carrier shell obtained in the step S2 to generate Fe in situ₃O₄Stirring the precursor of the iron-copper bimetallic MOF of the magnetic nanoparticles for 2h at normal temperature, filtering and then carrying out vacuum drying to obtain a one-dimensional conductive material carrier shell layer which is generated in situ and contains Fe₃O₄A magnetic composite material of an iron-copper bimetallic MOF precursor of the magnetic nanoparticles and a metal current collector;

step S4: generating Fe in situ by using the one-dimensional conductive material carrier shell obtained in the step S3₃O₄The magnetic composite material of the iron-copper bimetallic MOF precursor of the magnetic nano particles and the metal current collector is used as a working electrode, and an Hg/HgO electrode is used as a referenceA specific electrode, a platinum wire is taken as a counter electrode, 1mol/L KOH solution is taken as electrolyte, electrochemical activation is carried out, the activation constant current is 10mA/cm²And the activation time is 700s, so that the nano iron-copper double-metal hydroxide nanosheet is prepared, and finally the nano multistage assembled dual-function electrocatalyst with a composite low-dimensional structure and a composite high-dimensional structure is prepared.

5. The application of the bifunctional electrocatalyst prepared according to any one of claims 1 to 4 in electrocatalytic OER/HER reactions, wherein the multi-stage assembled bimetallic hydroxide nanosheets are used as the main catalytic active site region and are uniformly and stably dispersed on the surface of a carrier, and the controllability of the synthetic process and the stability under the working environment are improved by the method of interface action stabilization and electron conduction promotion, so that the bifunctional electrocatalyst material structure has the outstanding technical advantages of efficient material transmission and rapid charge transfer, and is favorable for improving the OER/HER electrocatalytic activity and the working life.

Technical Field

The invention belongs to the technical field of bifunctional electrocatalytic materials, and particularly relates to a preparation method and application of a bifunctional electrocatalytic agent.

Background

With global warming, energy crisis and environmental pollution getting worse, there is an urgent need to find clean renewable energy sources that can replace traditional fossil energy sources. Hydrogen energy is attracting increasing research interest in the fields of chemistry, materials and energy science as an environmentally friendly, high calorific value fuel and secondary energy source. Electrocatalytic water splitting is recognized as one of the sustainable methods to efficiently provide pollution-free and renewable energy hydrogen. An electrocatalytic water splitting device which generates hydrogen at a cathode and oxygen at an anode is a promising clean energy continuous power generation technology, and the electrocatalytic water splitting is composed of an anode Oxygen Evolution Reaction (OER) and a cathode Hydrogen Evolution Reaction (HER), however, the kinetics of the hydrogen evolution reaction and the oxygen evolution reaction are slow, so that the voltage of a battery is large, and further application of the hydrogen evolution reaction and the hydrogen evolution reaction is limited.

Noble metal materials (e.g. Pt, IrO)₂And RuO₂) Is the most advanced catalytic material for OER and HER. However, their commercial spread is hindered by their low reserves, high cost and the feature of catalyzing only one of the reactions. In addition, OER and HER must occur simultaneously in the same electrolyte to achieve total water splitting, and therefore the design and synthesis of high performance, low cost bifunctional electrocatalysts has attracted extensive attention.

In order to improve the activity and the service life of the electrocatalytic material, an important technical approach is to improve the uniform dispersion degree of the active components of the catalyst by innovating the catalyst carrier and optimizing the performance of the catalyst carrier. For the electrocatalyst containing non-noble metal-based catalytic active sites, a suitable material with a one-dimensional, two-dimensional or three-dimensional structure can be selected as a multifunctional carrier to further construct an electrocatalyst material with a nano-assembly structure, which mainly has the effects of enhancing charge transmission and mass transmission, thereby effectively improving the catalytic performance and efficiency.

The metal current collector is used as a growth carrier of the catalytic material, and is also an effective means for increasing the conductivity of the catalytic material, and an electro-catalytic material system without a modifier and an adhesive can be synthesized by the preparation method of the catalyst growing on the surface of the metal current collector in situ, so that the electro-catalytic material system has a remarkable effect on improving the electrochemical specific surface area and the stability of the catalytic material.

However, the inventor of the present application finds that the above-mentioned technology has at least the following technical problems in the process of implementing the technical solution of the invention in the embodiment of the present application: the Metal Organic Framework (MOF) is used as a precursor material of a catalytic active component, and grows in situ on the surface of a metal current collector, which is a common application form. However, since the MOF material is composed of metal ions and organic ligands, and metal sites are embedded by the organic ligands, the surface of the MOF material is nonpolar to a certain degree, while the surface of the metal current collector is polar, and objective surface properties of the metal current collector are significantly different from those of the metal current collector, which inevitably causes aggregation and desorption of the MOF material in the derivatization process and the catalytic working environment, especially under the bubbling impact when bubbles are generated in the oxygen evolution reaction and the hydrogen evolution reaction, thereby reducing the catalytic active sites in the catalytic material. Also, while the metallic current collector provides electron conductivity on a macroscopic level for supporting the electrocatalytic material, local charge transport is still limited due to the self-non-conductivity of the MOF material, resulting in a limited electrochemical reaction state.

Disclosure of Invention

The technical problem to be solved by the invention is to provide a preparation method of the bifunctional electrocatalyst, and the bifunctional electrocatalyst prepared by the method is used for electrocatalysis of OER/HER reaction, so that the electrochemical performance of the water cracking catalytic material is effectively improved, and the service life of the water cracking catalytic material is effectively prolonged.

The invention adopts the following technical scheme for solving the technical problems, and the preparation method of the bifunctional electrocatalyst is characterized by comprising the following steps of: taking a one-dimensional conductive material with a skin-core structure as a carrier, generating a bimetallic MOF precursor containing magnetic nanoparticles in situ on a shell layer of the carrier, and then carrying out magnetic compounding with a metal current collector, then preparing nanometer double-metal hydroxide nanometer sheets through electrochemical activation, finally generating the nanometer multi-level assembled dual-function electro-catalyst with a composite low-dimensional structure and a composite high-dimensional structure, the bifunctional electrocatalyst is formed by carrying out grading multidimensional assembly on a conductive carrier with a one-dimensional skin-core structure, a bimetallic hydroxide with a two-dimensional sheet structure and a three-dimensional metal current collector, can effectively adjust the electronic structure of the electrocatalyst, expose more available active sites, enhance the synergistic effect among all components, meanwhile, the bifunctional electrocatalyst is used for electrocatalysis of OER/HER reaction, and can realize rapid charge transfer and effective substance transmission, thereby improving the electrochemical performance and the service life of the water cracking catalytic material;

the specific preparation process comprises the following steps:

step S1: adding cuprous chloride and sucrose into deionized water, stirring and mixing uniformly, transferring to a polytetrafluoroethylene reaction kettle, reacting for 36h at 160 ℃, cooling to room temperature, washing with deionized water for several times, and drying in vacuum to obtain a one-dimensional conductive material carrier, wherein the one-dimensional conductive material carrier has a skin-core structure, namely a skin layer material is carbon and an inner core material is copper;

step S2: adding the one-dimensional conductive material carrier obtained in the step S1 into ethylene glycol, sequentially adding sodium acetate, polyethylene glycol, ferric chloride hexahydrate and 1H-benzimidazole-5-carboxylic acid, stirring vigorously, transferring into a polytetrafluoroethylene reaction kettle, reacting at 170 ℃ for 6-10H, cooling to room temperature, washing with deionized water for several times, and drying in vacuum to obtain a one-dimensional conductive material carrier shell layer which is generated in situ and contains Fe₃O₄Iron-copper bimetallic MOF precursors of magnetic nanoparticles;

step S3: respectively ultrasonically cleaning a metal current collector with the size of 2cm multiplied by 4cm in deionized water, acetone and ethanol, then putting the metal current collector into the deionized water, and then adding the one-dimensional conductive material carrier shell layer obtained in the step S2 to generate a carrier shell layer containing Fe in situ₃O₄Stirring the precursor of the iron-copper bimetallic MOF of the magnetic nanoparticles for 2h at normal temperature, filtering and then carrying out vacuum drying to obtain a one-dimensional conductive material carrier shell layer which is generated in situ and contains Fe₃O₄A magnetic composite material of an iron-copper bimetallic MOF precursor of the magnetic nanoparticles and a metal current collector;

step S4: generating Fe in situ by using the one-dimensional conductive material carrier shell obtained in the step S3₃O₄The magnetic composite material of the iron-copper bimetallic MOF precursor of the magnetic nanoparticles and the metal current collector is used as a working electrode, an Hg/HgO electrode is used as a reference electrode, a platinum wire is used as a counter electrode, and a 1mol/L KOH solution (pH = 13).6) Performing electrochemical activation for the electrolyte, wherein the constant activation current is 10mA/cm²And the activation time is 700s, so that the nano iron-copper double-metal hydroxide nanosheet is prepared, and finally the nano multistage assembled dual-function electrocatalyst with a composite low-dimensional structure and a composite high-dimensional structure is prepared.

Further limiting, the reaction time in step S2 is 8-10 h.

Further, the metal current collector in step S3 is nickel foam or iron foam.

Further limited, the preparation method of the bifunctional electrocatalyst is characterized by comprising the following specific steps:

step S1: adding 0.9g of cuprous chloride and 28g of sucrose into 35mL of deionized water, stirring and mixing uniformly, transferring the mixture into a 500mL polytetrafluoroethylene reaction kettle, reacting for 36h at 160 ℃, cooling to room temperature, washing with deionized water for several times, and drying in vacuum to obtain a one-dimensional conductive material carrier, wherein the one-dimensional conductive material carrier has a skin-core structure, namely a skin layer material is carbon and an inner core material is copper;

step S2: adding 10mg of the one-dimensional conductive material carrier obtained in the step S1 into 40mL of ethylene glycol, sequentially adding 1560mg of sodium acetate, 590mg of polyethylene glycol, 800mg of ferric chloride hexahydrate and 900mg of 1H-benzimidazole-5-carboxylic acid, stirring vigorously for 30min, transferring into a 50mL polytetrafluoroethylene reaction kettle, reacting at 170 ℃ for 9H, cooling to room temperature, washing with deionized water for several times, and drying in vacuum to obtain a one-dimensional conductive material carrier shell layer which contains Fe and is generated in situ₃O₄Iron-copper bimetallic MOF precursors of magnetic nanoparticles;

step S3: ultrasonically cleaning foamed nickel with the size of 2cm multiplied by 4cm in deionized water, acetone and ethanol for 30min, putting the cleaned foamed nickel into 200mL of deionized water, and adding the one-dimensional conductive material carrier shell obtained in the step S2 to generate Fe in situ₃O₄Stirring the precursor of the iron-copper bimetallic MOF of the magnetic nanoparticles for 2h at normal temperature, filtering and then carrying out vacuum drying to obtain a one-dimensional conductive material carrier shell layer which is generated in situ and contains Fe₃O₄A magnetic composite material of an iron-copper bimetallic MOF precursor of the magnetic nanoparticles and a metal current collector;

step S4: to be provided withThe one-dimensional conductive material carrier shell layer obtained in the step S3 is generated in situ to contain Fe₃O₄The magnetic composite material of the iron-copper bimetallic MOF precursor of the magnetic nanoparticles and the metal current collector is used as a working electrode, an Hg/HgO electrode is used as a reference electrode, a platinum wire is used as a counter electrode, 1mol/L KOH solution (pH = 13.6) is used as electrolyte, electrochemical activation is carried out, and the activation constant current is 10mA/cm²And the activation time is 700s, so that the nano iron-copper double-metal hydroxide nanosheet is prepared, and finally the nano multistage assembled dual-function electrocatalyst with a composite low-dimensional structure and a composite high-dimensional structure is prepared.

The application of the bifunctional electrocatalyst in the electrocatalytic OER/HER reaction takes the multi-level assembled bimetallic hydroxide nanosheets as the main catalytic active site area, the nanosheets are uniformly and stably dispersed on the surface of a carrier, and the controllability of the synthetic process and the stability under the working environment are improved by the method of interface action stabilization and electron conduction promotion, so that the material structure of the bifunctional electrocatalyst has the outstanding technical advantages of high-efficiency material transmission and rapid charge transfer, and the improvement of the OER/HER electrocatalytic activity and the service life are facilitated.

Compared with the prior art, the invention has the following advantages and beneficial effects:

1. the method utilizes the in-situ growth effect to enhance the close coupling between the one-dimensional high-conductivity carrier and the MOF-loaded precursor, so that more high-dispersion and high-stability catalytic active sites can be generated, and the charge transfer efficiency of the carrier interface can be accelerated. Therefore, the agglomeration and loss of active sites in the material preparation and catalysis processes are restrained by the stable anchoring effect of the interface, the electrocatalytic reaction efficiency is improved by the good carrier electron transmission effect, and the activity and the stability of the catalyst are effectively improved.

2. The MOF precursor composite material loaded on the one-dimensional carrier prepared by the invention has high conductivity and magnetism, so that the composite material is firmly combined with a metal current collector, the integral stability of a microstructure of a catalytic dual-function catalyst is kept in the operation process of an energy storage battery, and the good stability and the service life of the catalyst are further ensured. And the formed good electronic conductivity of the whole structure provides excellent electrocatalytic activity.

3. According to the invention, the MOF precursor is endowed with magnetic properties through material structure design, so that the surface property difference between the MOF material and a metal current collector is overcome, the aggregation and desorption phenomena of the catalyst material under the bubbling impact when bubbles are generated in the oxygen evolution reaction and the hydrogen evolution reaction of the catalytic working environment are avoided, and the activity and stability of the catalytic active sites of the bifunctional electrocatalyst are further improved.

4. According to the invention, the MOF precursor is electrochemically activated in situ to generate the nano-assembly layered double hydroxide, and the target product bifunctional electrocatalyst has large porosity and electrochemical active area through controllable reaction. The designed and synthesized high-conductivity one-dimensional carrier is embedded in the material in a penetrating manner, has very high charge transfer capacity, can provide sufficient reaction sites for electrochemical reaction, solves the problem that the transport of local charges of the MOF material is limited, and enables the electrochemical activation reaction to be more stable and effective.

5. The invention gives full play to the advantages of the composite material with the multidimensional structure, carries out grading multidimensional assembly on the conductive carrier with the one-dimensional sheath-core structure, the bimetallic hydroxide with the two-dimensional sheet structure and the three-dimensional metal current collector, can effectively adjust the electronic structure of the catalyst, exposes more available active sites, enhances the synergistic effect among the components, and is very important for the electrocatalytic reaction needing rapid charge transfer and effective mass transmission.

Drawings

FIG. 1 is an SEM image (a) and a TEM image (b) of the bifunctional electrocatalyst material prepared in the example;

FIG. 2 shows different catalyst materials in N prepared in examples and comparative examples₂OER curve (a) in saturated 1M KOH solution at 1600rpm and a scan rate of 5mV^-1And a corresponding stability test curve (b);

FIG. 3 shows different catalyst materials in N prepared in examples and comparative examples₂HER Curve (a) in a saturated 0.1M KOH solution at 1600rpm and a scanning rate of 5mV^-1And a corresponding stability test curve (b).

Detailed Description

The invention takes a one-dimensional conductive material with skin-core structure characteristics as a carrier, generates a bimetallic MOF precursor containing magnetic nanoparticles in situ in a shell layer of the carrier, then carries out magnetic compounding with a metal current collector, prepares nanometer bimetallic hydroxide nanosheets through electrochemical activation, and generates the bifunctional electrocatalyst material with a composite low-dimensional structure and a composite high-dimensional structure. Therefore, the invention forms an integrated realization technical scheme of microstructure property regulation, composite interface construction reinforcement and integral electronic conduction promotion of the fuel cell catalyst, and realizes the comprehensive promotion of the catalytic activity and stability of the fuel cell catalyst.

In order to better explain the technical scheme, the technical scheme is described in detail with reference to specific embodiments. It should not be understood that the scope of the above-described subject matter is limited to the following examples, and any techniques implemented based on the above-described subject matter are within the scope of the present invention.

Electrochemical testing was performed using a three-electrode system. The metal current collector compounded with catalytic material is used as a working electrode, the catalyst is the target catalytic material prepared in the examples, the comparative example 1, the comparative example 2 and the comparative example 3, and the counter electrode and the reference electrode are respectively 1cm²The electrolyte is 1M KOH aqueous solution.

Examples

Step S1: adding 0.9g of cuprous chloride and 28g of sucrose into 35mL of deionized water, stirring and mixing uniformly, transferring the mixture into a 500mL polytetrafluoroethylene reaction kettle, reacting for 36h at 160 ℃, cooling to room temperature, washing with deionized water for several times, and drying in vacuum to obtain a one-dimensional conductive material carrier, wherein the one-dimensional conductive material carrier has a skin-core structure, namely a skin layer material is carbon and an inner core material is copper;

step S2: adding 10mg of the one-dimensional conductive material carrier obtained in the step S1 into 40mL of ethylene glycol, sequentially adding 1560mg of sodium acetate, 590mg of polyethylene glycol, 800mg of ferric chloride hexahydrate and 900mg of 1H-benzimidazole-5-carboxylic acid, violently stirring for 30min, transferring to a 50mL polytetrafluoroethylene reaction kettle, and putting into the kettleReacting at 170 ℃ for 9h, cooling to room temperature, washing with deionized water for a plurality of times, and then drying in vacuum to obtain the one-dimensional conductive material carrier shell which is generated in situ and contains Fe₃O₄Iron-copper bimetallic MOF precursors of magnetic nanoparticles;

step S3: ultrasonically cleaning foamed nickel with the size of 2cm multiplied by 4cm in deionized water, acetone and ethanol for 30min, putting the cleaned foamed nickel into 200mL of deionized water, and adding the one-dimensional conductive material carrier shell obtained in the step S2 to generate Fe in situ₃O₄Stirring the precursor of the iron-copper bimetallic MOF of the magnetic nanoparticles for 2h at normal temperature, filtering and then carrying out vacuum drying to obtain a one-dimensional conductive material carrier shell layer which is generated in situ and contains Fe₃O₄A magnetic composite material of an iron-copper bimetallic MOF precursor of the magnetic nanoparticles and a metal current collector;

step S4: generating Fe in situ by using the one-dimensional conductive material carrier shell obtained in the step S3₃O₄The magnetic composite material of the iron-copper bimetallic MOF precursor of the magnetic nanoparticles and the metal current collector is used as a working electrode, an Hg/HgO electrode is used as a reference electrode, a platinum wire is used as a counter electrode, 1mol/L KOH solution (pH = 13.6) is used as electrolyte, electrochemical activation is carried out, and the activation constant current is 10mA/cm²And the activation time is 700s, so that nano iron-copper double-metal hydroxide nanosheets are prepared, and finally, the nano multistage assembled dual-function electrocatalyst material with a composite low-dimensional structure and a composite high-dimensional structure is prepared, as shown in fig. 1, the dual-function electrocatalyst material is prepared by carrying out hierarchical multi-dimensional assembly on a conductive carrier with a one-dimensional skin-core structure, double-metal hydroxide with a two-dimensional sheet structure and a three-dimensional metal current collector.

Comparative example 1 (etching time > 10 h)

Step S1: adding 0.9g of cuprous chloride and 28g of sucrose into 35mL of deionized water, stirring and mixing uniformly, transferring the mixture into a 500mL polytetrafluoroethylene reaction kettle, reacting for 36h at 160 ℃, cooling to room temperature, washing with deionized water for several times, and drying in vacuum to obtain a one-dimensional conductive material carrier, wherein the one-dimensional conductive material carrier has a skin-core structure, namely a skin layer material is carbon and an inner core material is copper;

step S2: adding 10mg of the one-dimensional conductive material carrier obtained in the step S1 into 40mL of ethylene glycol, sequentially adding 1560mg of sodium acetate, 590mg of polyethylene glycol, 800mg of ferric chloride hexahydrate and 900mg of 1H-benzimidazole-5-carboxylic acid, violently stirring for 30min, transferring to a 50mL polytetrafluoroethylene reaction kettle, reacting at 170 ℃ for 12H, cooling to room temperature, washing with deionized water for several times, and vacuum drying to obtain a precursor;

step S3: ultrasonically cleaning foamed nickel with the size of 2cm multiplied by 4cm in deionized water, acetone and ethanol for 30min respectively, then placing the cleaned foamed nickel into 200mL of deionized water, then adding the precursor obtained in the step S2, stirring for 2h at normal temperature, filtering and drying in vacuum to obtain a composite material;

step S4: using the composite material obtained in the step S3 as a working electrode, using an Hg/HgO electrode as a reference electrode, using a platinum wire as a counter electrode, using a 1mol/L KOH solution (pH = 13.6) as an electrolyte, and performing electrochemical activation at a constant activation current of 10mA/cm²And the activation time is 700s, thus obtaining the catalyst material.

Comparative example 2 (foam nickel was grown in situ without adsorbing it with magnetic particles)

Step S1: adding 0.9g of cuprous chloride and 28g of sucrose into 35mL of deionized water, uniformly stirring, transferring to a 50mL polytetrafluoroethylene reaction kettle, reacting at 160 ℃ for 36h, cooling to room temperature, washing with deionized water for several times, and then carrying out vacuum drying to obtain a one-dimensional conductive material carrier, wherein the one-dimensional conductive material carrier has a skin-core structure, namely the skin material is carbon and the inner core material is copper;

step S2: respectively ultrasonically cleaning foamed nickel with the size of 2cm multiplied by 4cm in deionized water, acetone and ethanol for 30 min;

step S3: adding the cleaned nickel foam obtained in the step S2 into 40mL of deionized water, then adding 10mg of the one-dimensional conductive material carrier obtained in the step S1, then sequentially adding 800mg of ferric chloride hexahydrate and 900mg of 1H-benzimidazole-5-carboxylic acid, fully stirring, reacting at 120 ℃ for 9H, standing for 5H, filtering, and performing vacuum drying to obtain a precursor;

step S4: taking the precursor obtained in the step S3 as a working electrode, taking an Hg/HgO electrode as a reference electrode, taking a platinum wire as a counter electrode, and taking 1mol/LKOH solution (pH = 13.6) is used as electrolyte, electrochemical activation is carried out, and the constant current of activation is 10mA/cm²And the activation time is 700s, thus obtaining the catalyst material.

Comparative example 3 (No cable is active during electrochemical activation)

Step S1: adding 1560mg of sodium acetate, 590mg of polyethylene glycol and 800mg of ferric chloride hexahydrate into 40mL of ethylene glycol in sequence, stirring vigorously for 30min, transferring into a 50mL polytetrafluoroethylene reaction kettle, reacting at 200 ℃ for 12h, cooling to room temperature, washing with deionized water for several times, and drying in vacuum to obtain Fe₃O₄Magnetic nanoparticle dark brown samples;

step S2: fe obtained in step S1₃O₄Adding a magnetic nanoparticle black brown sample into 40mL of deionized water, sequentially adding 460mg of copper chloride and 960mg of 1H-benzimidazole-5-carboxylic acid, violently stirring for 30min, transferring to a 50mL polytetrafluoroethylene reaction kettle, reacting at 200 ℃ for 12h, cooling to room temperature, washing with deionized water for several times, and performing vacuum drying to obtain a precursor;

step S3: ultrasonically cleaning foamed nickel with the size of 2cm multiplied by 4cm in deionized water, acetone and ethanol for 30min respectively, putting the cleaned foamed nickel into 200mL of deionized water, adding the precursor obtained in the step S2, stirring for 2h at normal temperature, filtering and drying in vacuum to obtain a composite material;

step S4: using the composite material obtained in the step S3 as a working electrode, using an Hg/HgO electrode as a reference electrode, using a platinum wire as a counter electrode, using a 1mol/L KOH solution (pH = 13.6) as an electrolyte, and performing electrochemical activation at a constant activation current of 10mA/cm²And the activation time is 700s, thus obtaining the catalyst material.

The bifunctional electrocatalyst prepared by the embodiment of the invention has good OER/HER catalytic activity and stability. As can be seen from the electrical property test results of fig. 2 and 3, the bifunctional electrocatalysts prepared in the examples have greater OER/HER catalytic activity and better stability.

Through the analysis of the embodiment and the comparative examples 1 to 3, it can be found that the control of the appropriate reaction time, the magnetic adsorption between the MOF material and the metal current collector, the promotion of the electrochemical activation by the high-conductivity one-dimensional carrier and other key factors is very important for the electrocatalytic reaction of the rapid charge transfer and the effective mass transfer, and the performance advantage of the multi-dimensional structure composite electrocatalytic material can be fully exerted. The invention forms an integrated realization technical scheme of microstructure property regulation, composite interface construction reinforcement and integral electron conduction promotion of the bifunctional electrocatalyst, and realizes the comprehensive promotion of the catalytic activity and stability of the bifunctional electrocatalyst.

The foregoing embodiments illustrate the principles, principal features and advantages of the invention, and it will be understood by those skilled in the art that the invention is not limited to the foregoing embodiments, which are merely illustrative of the principles of the invention, and that various changes and modifications may be made therein without departing from the scope of the principles of the invention.