CN112993349A

CN112993349A - Preparation method and application of hollow nanometer groove type membrane electrode

Info

Publication number: CN112993349A
Application number: CN201911287562.8A
Authority: CN
Inventors: 侯明; 齐满满; 秦晓平; 张洪杰; 邵志刚
Original assignee: Dalian Institute of Chemical Physics of CAS
Current assignee: Dalian Institute of Chemical Physics of CAS
Priority date: 2019-12-14
Filing date: 2019-12-14
Publication date: 2021-06-18
Anticipated expiration: 2039-12-14
Also published as: CN112993349B

Abstract

The invention provides a preparation method and application of a hollow nanometer groove type membrane electrode, and particularly comprises the preparation of nanometer fibers, the loading of a catalyst on the surfaces of the nanometer fibers and the assembly of the membrane electrode. Firstly, preparing a nanofiber template through electrostatic spinning, carrying a catalyst active component on the surface of the template through a physical vapor deposition or chemical reduction method, removing the template through solvent impregnation or calcination to obtain a hollow nano-groove structure, and finally, hot-pressing the hollow nano-groove structure to an ion exchange membrane to obtain the membrane electrode. The prepared membrane electrode can be used for proton exchange membrane fuel cells, solid polymer electrolyte water electrolysis and integrated renewable fuel cells. The membrane electrode prepared by the invention has the advantages of no catalyst carrier, high catalyst utilization rate, thin catalyst layer, stable catalyst layer, simple preparation process, large-area preparation and the like.

Description

Preparation method and application of hollow nanometer groove type membrane electrode

Technical Field

The invention belongs to the technical field of water electrolysis of fuel cells and solid polymer electrolytes, and particularly relates to a preparation method and application of a hollow nanometer groove type membrane electrode.

Background

The hydrogen energy is ideal secondary energy, the combustion product is water, the water can be prepared into hydrogen in an electrolysis or photolysis mode, and the formed hydrogen circulation system is clean and environment-friendly. The solid Polymer Electrolyte (PEM) water electrolysis technology becomes a research hotspot in the field of hydrogen production due to the advantages of high efficiency, environmental friendliness, high product purity and the like.

The fuel cell is a clean and efficient energy conversion device, can effectively convert chemical energy stored in chemical substances into electric energy, and makes great progress in the fields of public transportation, aerospace and the like. Among them, the proton exchange membrane fuel cell using hydrogen as fuel has drawn attention to its advantages of high power density, fast low-temperature starting speed, environmental friendliness, etc.

The renewable fuel cell can realize the dual effects of the fuel cell and water electrolysis on the same component, has the characteristics of large storage capacity, high specific energy, small environmental pollution and the like, and has great application potential in the fields of military power supplies and spaces.

The Membrane Electrode Assembly (MEA) is the site of the electrochemical reaction and is one of the core components of PEM water electrolysis and fuel cells. It is composed of a catalyst layer and a gas diffusion layer which are positioned at two sides of an ion exchange membrane in a five-in-one mode. Currently, membrane electrodes are mainly classified into Gas Diffusion Electrodes (GDEs), thin film membrane electrodes (CCMs), and ordered MEAs (ordered MEAs) which are still under study. The GDE is generally prepared by coating a catalyst slurry, which is formed by ultrasonically dispersing a catalyst, a water repellent (generally PTFE emulsion) and an organic solvent, on a gas diffusion layer by using a process such as spraying, screen printing, etc., and then spraying a Nafion solution on the catalyst layer after high-temperature treatment. CCM is generally prepared by spraying and transfer printing processes, and catalyst slurry is prepared by ultrasonically dispersing a catalyst, an ion conductor resin and an organic solvent. The CCM process may involve spraying the catalyst slurry directly onto the membrane, or spraying it onto another support (e.g., aluminum foil) and transferring it to the membrane to form the membrane electrode. The GDE and CCM processes are mature, and can realize batch preparation, but the problems of large thickness of a catalyst layer, high catalyst consumption, low utilization rate, poor stability and the like exist. In order to solve the problems of high catalyst consumption and low catalyst utilization rate of fuel cells, the ordered thin-layer electrode (NSTF electrode) developed by 3M company has the characteristics of microscopic order, low catalyst loading capacity and the like, and can effectively reduce mass transfer resistance and improve the utilization rate of the catalyst.

Chinese patent CN 109904469a introduces a method for preparing a membrane electrode with an optimized cathode catalyst layer structure, which specifically comprises adding PS microspheres as a pore-forming agent into a catalyst layer slurry, and subsequently removing the pore-forming agent to enrich the pore structure of the catalyst layer. The membrane electrode catalyst layer prepared by the method has the characteristics of large pore structure and porosity, but the thickness of the catalyst layer can be increased due to the addition of the pore-forming agent, so that the mass transfer resistance can be increased to a certain extent, and the further improvement of the performance of the battery is not facilitated. The preparation of a catalyst layer with high activity and high stability is the key to improve the performance and the service life of the water electrolysis of the fuel cell or the PEM.

Disclosure of Invention

Aiming at the problems of large thickness of catalyst layers, high catalyst consumption, low utilization rate, poor stability and the like of the traditional membrane electrode (GDE and CCM), the invention aims to provide a preparation method of a hollow nanometer groove type membrane electrode for water electrolysis of a fuel cell or a PEM (proton exchange membrane), wherein the three-dimensional interconnected structure of hollow nanometer grooves is beneficial to increasing the three-phase reaction interface area, improving the catalyst utilization rate, enhancing the stability of a catalyst layer and prolonging the service life of water electrolysis of the fuel cell or the PEM.

The technical scheme adopted by the invention is as follows:

the invention provides a membrane electrode, which comprises a membrane and a catalyst layer, wherein the catalyst layer is formed in a hollow nanometer groove shape; an ionomer in the catalyst layer; the catalyst is Pt or Ir, or the catalyst is a multicomponent alloy formed by Pt and one of Pd, Co, Ir, Fe, Ni, Cu, Mn, Au, Ag and Ru, the catalyst is unsupported in the membrane electrode, and the loading capacity of the catalyst is 0.01-50mg cm^-2。

Based on the technical scheme, preferably, the thickness of the catalyst layer is 0.1-1 μm, the diameter of the hollow nano-groove is 50-800nm, the wall thickness of the hollow nano-groove is 2-20nm, the length is 100-800nm, and the porosity of the catalyst layer is 25-50%.

The invention also provides a preparation method of the membrane electrode, which comprises the following steps:

(1) preparing a high molecular polymer solution for electrostatic spinning;

(2) carrying out electrostatic spinning on the high molecular polymer solution in the step (1) on a substrate to obtain a nanofiber template;

(3) carrying a catalyst on the surface of the polymer nanofiber template by a physical vapor deposition or chemical reduction method;

(4) removing the nanofiber template by adopting a solvent soaking or calcining mode; obtaining a hollow nano-groove catalyst layer attached on the substrate;

(5) printing the catalyst layer attached to the substrate to one side or two sides of the ion exchange membrane in a hot pressing mode;

(6) and purifying the membrane electrode to obtain the membrane electrode.

Based on the above technical scheme, the preferable high molecular polymer solution in step (1) is water-soluble polymer and water or organic solvent-soluble high molecular polymer and organic solvent: the water-soluble polymer is one or a mixture of more of polyacrylic acid, polyethylene oxide, polyvinyl alcohol, polyvinylpyrrolidone, cyclodextrin, sodium polyacrylate, hydroxypropyl cellulose (HPC) and the like; the organic solvent-soluble high-molecular polymer includes: at least one of Polyacrylonitrile (PAN), Polystyrene (PS), polyvinyl acetate, polycarbonate, polyimide, polybenzimidazole, polyamide, polyvinyl chloride, polyaniline, polymethyl methacrylate (PMMA), polypyrrole, polythiophene, polyvinylidene fluoride; the organic solvent is methanol, ethanol, N-propanol, isopropanol, N-methylpyrrolidone (NMP), N, N-Dimethylformamide (DMF), dimethyl sulfoxide (DMSO), N, N-dimethylacetamide (DMAc); the concentration of the high molecular polymer solution is 0.01 wt.% to 20 wt.%.

Based on the technical scheme, the voltage of the electrostatic spinning in the step (2) is preferably 10-25kV, the feeding speed is 0.3-1mL/h, the voltage is 8kV-20kV, the rotating speed of a rotary drum receiver is 100rpm/min-300rpm/min, and the diameter of a needle is 0.3-0.7 mm; environmental parameters: the temperature is 10-30 ℃, and the relative humidity is 10-50% RH; substrates that can be used to receive the nanofibers are: stainless steel, aluminum foil.

Based on the technical scheme, the preferable physical vapor deposition in the step (3) is one of vacuum evaporation, magnetron sputtering and ion plating; the chemical reduction method is one of chemical reduction impregnation, electrochemical deposition and underpotential deposition.

Based on the above technical scheme, the preferable solvent for removing the nanofiber template in step (4) is water, methanol, ethanol, N-propanol, isopropanol, N-methylpyrrolidone (NMP), N-Dimethylformamide (DMF), dimethyl sulfoxide (DMSO), N-dimethylacetamide (DMAc). The soaking time is 1-24h, and the soaking temperature is 20-120 ℃.

The high-temperature roasting method is to roast at the temperature of 400-.

Based on the technical scheme, the pressure of transferring to the ion exchange membrane in the step (5) is preferably 0.5-10MPa, the transferring temperature is 90-160 ℃, and the hot pressing time is 1-60 min.

Based on the technical scheme, the purification step of the membrane electrode in the step (6) is as follows:

(A) washing the membrane electrode with water, soaking the membrane electrode in deionized water for washing, wherein the washing temperature is 20-100 ℃, and the washing time is 1-24 h;

(B) cleaning the membrane electrode in a hydrogen peroxide aqueous solution; the concentration of hydrogen peroxide is 0.5-10 wt.%, and the cleaning temperature is 20-80 ℃; the cleaning time is 1-24 h;

(C) and (3) cleaning the membrane electrode in deionized water at the temperature of 20-100 ℃ for 1-24 h.

The invention also provides the application of the hollow nanometer groove type membrane electrode in proton exchange membrane fuel cells, solid polymer water electrolysis and integrated renewable fuel cells.

Advantageous effects

(1) The invention prepares a three-dimensional through hollow nanometer groove type membrane electrode by combining the electrostatic spinning technology with the physical vapor deposition technology or the chemical reduction method, and the structure is beneficial to enlarging the three-phase reaction interface area and improving the utilization rate of the catalyst;

(2) the membrane electrode catalyst layer prepared by the invention has no ionic polymer and no carrier, so that the stability of the catalyst layer is improved, and the service life of a fuel cell or PEM water electrolysis is prolonged;

(3) the membrane electrode prepared by the invention has low noble metal consumption, flexible and adjustable catalyst components and thin catalyst layer;

(4) the preparation method of the electrode is simple to operate, the preparation process is green and environment-friendly, and the electrode can be prepared in batches.

Drawings

FIG. 1 is a flow chart of the present invention for preparing a nano-groove type membrane electrode.

Fig. 2a) is a polyacrylic acid (PAA) nanofiber templating agent prepared in example 1.

Fig. 2b) is an SEM image of the Pt hollow nano-groove prepared in example 1.

Fig. 2c) is a cross-sectional view of the Pt hollow nano groove type membrane electrode prepared in example 1.

Fig. 3 is a polarization graph of the membrane electrode prepared in example 1 in a fuel cell.

FIG. 4a) is a topographical view of an electrospun membrane electrode prepared in comparative example 1.

Fig. 4b) is a cross-sectional view of the electrospun membrane electrode prepared in comparative example 1.

Fig. 5 is a polarization curve diagram of the electrospun membrane electrode prepared in comparative example 1 in a fuel cell.

Fig. 6 is a polarization curve diagram of the magnetron sputtered membrane electrode prepared in comparative example 2 in a fuel cell.

Fig. 7 is a polarization graph of the membrane electrode prepared in example 2 in a fuel cell.

Fig. 8 is a polarization graph of the membrane electrode prepared in example 3 in a fuel cell.

Fig. 9 is a polarization graph of the membrane electrode prepared in example 4 in a fuel cell.

Fig. 10 is a polarization graph of the membrane electrode prepared in example 5 in a fuel cell.

Fig. 11 is a polarization curve diagram in the membrane electrode water electrolytic cell prepared in example 6.

FIG. 12 is a graph of the performance of the membrane electrode prepared in example 7 in an integrated renewable fuel cell, a) is a water electrolysis polarization plot, b) is a polarization plot in a fuel cell.

Detailed Description

The following examples are further illustrative of the present invention while protecting obvious modifications and equivalents.

Example 1

0.5g polyacrylic acid (PAA) was weighed out and dissolved in 9.5g deionized water, and after magnetic stirring at room temperature for 3-5h, a 5 wt.% PAA aqueous solution was obtained. The environmental parameters for preparing the nanofiber template agent by electrostatic spinning are as follows: temperature 15 ℃, relative humidity 30% RH; stainless steel with the thickness of 3mm is used as a substrate; the control parameters are as follows: the slurry feed rate was 0.8mL/h, the voltage was 12kV, the rotational speed of the drum receiver was 120rpm/min, the needle diameter was 0.5nm, the distance between the needle and the receiver was 12cm, and the spinning time was 60 min. The average diameter of the resulting PAA nanofibers was 130nm (see FIG. 2 a).

Pt is carried on the surface of the PAA nanofiber template by adopting a magnetron sputtering technology, the sputtering power is 100W, the sputtering time is 10min, and the pressure in a sputtering chamber is 0.8 Pa. And then soaking the Pt-loaded nanofiber in deionized water at 25 ℃ to dissolve the PAA nanofiber, wherein the soaking time is 12 h. Then transferring the sample without the template agent to a transfer printing machine in a mode of hot pressing at 135 ℃ and 2MPa for 5min

212 one side of the membrane and the stainless steel substrate is removed. The membrane electrode purification treatment comprises the following steps: boiling the membrane electrode in deionized water at 80 ℃ for 2H to remove residual template agent, and then boiling the membrane electrode in deionized water at 80 ℃ for 3 wt.% of H₂O₂And (3) boiling for 2h to remove impurities on the surface of the nanometer groove, and finally boiling for 2h in deionized water at the temperature of 80 ℃. FIG. 2b is a diagram of the morphology of the membrane electrode with hollow nano-grooves, the diameter of the nano-groove is 180nm, the wall thickness of the single nano-groove is 10nm, and the thickness of the catalytic layer is 170nm (FIG. 2 c).

The dried membrane electrode was used as the cathode of a membrane electrode assembly, and the Pt loading amount measured by ICP-OES was 45. mu.g cm^-2(ii) a The anode was a gas diffusion electrode, the catalyst was commercial Pt/C (70 wt.%, Johnson Matthey), and the Pt loading was 0.3mg cm^-2. The effective area of the membrane electrode assembly was 5cm². The battery test conditions were: battery temperature 80 ℃, saturation humidification, H₂/O₂Flow rate 125/250mL min^-1The peak power obtained by the cell is 0.82W cm under the condition that the back pressure of the cell is 1.5bar^-2(FIG. 3).

Comparative example 1

0.1g of 40 wt.% Pt/C catalyst and 0.9g of 5 wt.% Nafion solution are weighed, 0.06g of water and 0.3g of isopropanol are added, ultrasonic mixing is carried out, then 0.02g of polyacrylic acid high molecular polymer is added, and stirring is carried out for 12 hours, so as to obtain heterogeneous catalyst slurry. The catalyst layer is prepared by adopting an electrostatic spinning technology. The environmental parameters of electrostatic spinning are 15 ℃ of temperature and 30% RH of relative humidity; the control parameters are as follows: the slurry feed rate was 0.8mL/h, the voltage was 12kV, the rotational speed of the drum receiver was 120rpm/min, the diameter of the needle was 0.5mm, and the distance from the needle to the receiver was 12 cm. By controlling the spinning timeThe obtained Pt loading amount was 100. mu.g cm^-2The morphology of the catalytic layer of (2) is shown in fig. 4a, the catalytic layer thickness is about 700nm (fig. 4 b). Finally, the catalytic layer is transferred to

212, hot-pressing at 140 deg.C under 0.2-0.5MPa for 120-. The anode used a commercial gas diffusion electrode, the catalyst was commercial Pt/C (70 wt.%, Johnson Matthey), and the Pt loading was 0.3mg cm^-2. The effective area of the membrane electrode assembly was 5cm². The battery test conditions were: the peak power obtained for the cell was 0.78W cm as in example 1^-2(FIG. 5). Unlike example 1 of the present invention, the catalyst layer prepared by electrospinning was large in thickness.

Comparative example 2

Cutting a Gas Diffusion Layer (GDL) into a rectangular strip with the size of 3cm multiplied by 6cm, sticking the gas diffusion layer to a stainless steel flat plate for magnetron sputtering by using a double-sided adhesive, wherein a microporous layer of the gas diffusion layer is opposite to a Pt target material for magnetron sputtering. The vacuum pressure in the chamber to be sputtered is reduced to 2.5X 10^-3And when the pressure is Pa, slowly filling argon until the pressure in the sputtering chamber is 0.8Pa, sputtering power is 100W, and sputtering time is 10min, thus obtaining the gas diffusion electrode. It was used as the cathode side of a membrane electrode assembly, and the amount of Pt supported by ICP-OES was 55. mu.g cm^-2. The anode used a commercial gas diffusion electrode, the catalyst was commercial Pt/C (70 wt.%, Johnson Matthey), and the Pt loading was 0.3mg cm^-2. The effective area of the membrane electrode assembly was 5cm². The battery test conditions were: battery temperature 80 ℃, saturation humidification, H₂/O₂Flow rate 125/250mL min^-1The peak power obtained by the cell is 0.53W cm under the condition that the back pressure of the cell is 1.5bar^-2(FIG. 6). The catalyst in the embodiment is in a disordered distribution state because the nano-fiber template is not used, so that the utilization rate of the catalyst is reduced.

Example 2

0.25g of polyvinyl alcohol (PVA) was weighed out and dissolved in 2.25g of deionized water, and the solution was magnetically stirred at 80 ℃ for 12 hours to give a 10 wt.% aqueous solution of PVA. The environmental parameters for preparing the nanofiber template agent by electrostatic spinning are as follows: temperature 20 ℃, relative humidity 25% RH; stainless steel with the thickness of 3mm is used as a substrate; the control parameters are as follows: the slurry feed rate was 0.5mL/h, the voltage was 10kV, the rotational speed of the drum receiver was 150rpm/min, the needle diameter was 0.5nm, the distance between the needle and the receiver was 10cm, and the spinning time was 60 min. The average diameter of the PVA nanofibers was 127 nm.

Pt is loaded on the surface of the PVA nanofiber template agent by adopting a magnetron sputtering technology, the sputtering power is 100W, the sputtering time is 15min, and the pressure in a sputtering chamber is 0.8 Pa. And then soaking the Pt-loaded nanofiber in deionized water at the temperature of 80 ℃ to dissolve the PVA nanofiber, wherein the soaking time is 20 h. Then transferring the sample without the template agent to a hot pressing way of 150 ℃ and 0.5MPa for 20min

212 one side of the membrane and the stainless steel substrate is removed. The membrane electrode purification treatment comprises the following steps: boiling the membrane electrode in deionized water at 80 ℃ for 2H to remove residual template agent, and then boiling the membrane electrode in 5 wt.% of H at 80 DEG C₂O₂And (3) boiling for 2h to remove impurities on the surface of the nanometer groove, and finally boiling for 2h in deionized water at the temperature of 80 ℃. The diameter of the hollow nanometer cell membrane electrode prepared by taking PVA as a template agent is 170nm, the wall thickness of the hollow nanometer cell is 10nm, and the thickness of the catalytic layer is 190 nm.

The dried membrane electrode was used as the cathode of a membrane electrode assembly, and the Pt loading, as measured by ICP-OES, was 55 μ gcm^-2The anode was a gas diffusion electrode, the catalyst was commercial Pt/C, and the Pt loading was 0.3mg cm^-2. The effective area of the membrane electrode assembly was 5cm². The battery test conditions were: battery temperature 80 ℃, saturation humidification, H₂/O₂Flow rate 125/250mL min^-1The peak power obtained by the cell is 0.87W cm under the cell backpressure of 2bar^-2(FIG. 7).

Example 3

The PVA nanofibers were prepared according to the same procedure as in example 2.

Carrying Pt and Co on the surface of the PVA nano-fiber template agent by adopting a magnetron sputtering technology, wherein the sputtering power is 100W, the sputtering time is 15min, and the pressure in a sputtering chamber is0.8 Pa. And then soaking the Pt and Co loaded nano fibers in deionized water at the temperature of 80 ℃ to dissolve the PVA nano fibers, wherein the soaking time is 12 h. Then transferring the sample without the template agent to a transfer printing machine in a mode of hot pressing at 150 ℃ and 2MPa for 20min

212 one side of the membrane and the stainless steel substrate is removed. The membrane electrode purification treatment comprises the following steps: boiling the membrane electrode in deionized water at 80 ℃ for 2H to remove residual template agent, and then boiling the membrane electrode in 5 wt.% of H at 80 DEG C₂O₂And (3) boiling for 2h to remove impurities on the surface of the nanometer groove, and finally boiling for 2h in deionized water at the temperature of 80 ℃. The shape and appearance of the membrane electrode of the hollow nano-groove prepared by taking PVA as a template agent are 170nm in diameter, 10nm in wall thickness of the hollow nano-groove and 190nm in thickness of the catalytic layer.

The dried membrane electrode was used as the cathode of a membrane electrode assembly, and the Pt loading was measured by ICP-OES to be 40. mu.g cm^-2Co loading of 15. mu.g cm^-2The anode was a gas diffusion electrode, the catalyst was commercial Pt/C (70 wt.%, Johnson Matthey), and the Pt loading was 0.3mg cm^-2. The effective area of the membrane electrode assembly was 5cm². The battery test conditions were: battery temperature 80 ℃, saturation humidification, H₂/O₂Flow rate 125/250mL min^-1The peak power obtained by the battery is 0.92W cm under the condition that the back pressure of the battery is 2bar^-2(FIG. 8).

Example 4

The procedure for preparing a 10 wt.% PVA solution was the same as in example 2. To the PVA solution was added an amount of 60 wt.% PTFE emulsion such that the ratio of PTFE: PVA is 4:6 (mass ratio), and then the spinning solution is obtained by magnetic stirring for 12 hours at room temperature. The electrostatic spinning parameters were the same as in example 2, and the diameter of the obtained nanofiber templating agent was 220 nm.

Pt and Pd are loaded on the surface of the PTFE/PVA nanofiber template by adopting a magnetron sputtering technology, the sputtering power is 100W, the sputtering time is 15min, and the pressure in a sputtering chamber is 0.8 Pa. And then, the Pt and Pd supported nano-fibers are roasted for 2h at 400 ℃ in a nitrogen atmosphere to remove PVA in the composite fibers and simultaneously cause phase transformation of PTFE. Then transferring the sample without the template agent to a transfer printing machine in a mode of hot pressing at 140 ℃ and 1MPa for 10min

212 one side of the membrane and the stainless steel substrate is removed. The membrane electrode purification treatment comprises the following steps: boiling the membrane electrode in deionized water at 80 ℃ for 2H to remove residual template agent, and then boiling the membrane electrode in 10 wt.% of H at 80 DEG C₂O₂And (3) boiling for 2h to remove impurities on the surface of the nanometer groove, and finally boiling for 2h in deionized water at the temperature of 80 ℃. The diameter of the hollow nano-cell membrane prepared from the PTFE/PVA nano-fiber template agent is 260nm, the wall thickness of the hollow nano-cell is 10nm, and the thickness of the catalytic layer is 200 nm.

The dried membrane electrode was used as the cathode of a membrane electrode assembly, and the Pt loading was measured by ICP-OES to be 30. mu.g cm^-2Pd loading of 30. mu.g cm^-2(ii) a The anode was a gas diffusion electrode, the catalyst was commercial Pt/C (70 wt.%, Johnson Matthey), and the Pt loading was 0.3mg cm^-2. The effective area of the membrane electrode assembly was 5cm². The battery test conditions were: battery temperature 80 ℃, saturation humidification, H₂/O₂Flow rate 125/250mL min^-1The peak power obtained by the battery is 0.76W cm under the condition that the back pressure of the battery is 2bar^-2(FIG. 9).

Example 5

0.25g Polyacrylonitrile (PAN) was weighed out and dissolved in 2.25g N, N-Dimethylformamide (DMF), and magnetic stirring was carried out at 60 ℃ for 12h to obtain 10 wt.% PAN solution. The environmental parameters for preparing the nanofiber template agent by electrostatic spinning are as follows: temperature 20 ℃, relative humidity 25% RH; stainless steel with the thickness of 3mm is used as a substrate; the control parameters are as follows: the slurry feed rate was 0.5mL/h, the voltage was 10kV, the rotational speed of the drum receiver was 150rpm/min, the needle diameter was 0.5nm, the distance between the needle and the receiver was 10cm, and the spinning time was 60 min. The average diameter of the resulting PAN nanofibers was 150 nm.

Depositing Pt on the surface of the PAN nano-fiber template agent by adopting an underpotential electrodeposition mode, firstly taking the PAN nano-fiber template agent as a working electrode, taking a saturated calomel electrode as a reference electrode, taking a graphite electrode as a counter electrode, and taking an electrolyte solution of 50mM CuSO₄And 0.5MH₂SO₄. In a three-electrode system, the working electrode potential is varied from 0.85V to 1mV s^-1The sweep speed was swept to 0.36V. And then adding a platinum dichloride solution into the electrolyte solution to enable the concentration of the platinum dichloride solution to reach 5mM finally, and standing for 30min to enable platinum to be deposited on the surface of the PAN. And then soaking the Pt-loaded nanofiber in DMF (dimethyl formamide) at the temperature of 80 ℃ to dissolve the PAN nanofiber, wherein the soaking time is 12 h. Transferring the sample with the template agent removed to a transfer printing machine by hot pressing at 120 ℃ and 5MPa for 10min

212 one side of the membrane and the stainless steel substrate is removed. The membrane electrode cleaning treatment procedure was the same as in example 1. Drying the membrane electrode and then using the dried membrane electrode as a cathode of a membrane electrode assembly; pt loading of 30. mu.g cm as determined by ICP-OES^-2(ii) a The anode was a gas diffusion electrode, the catalyst was commercial Pt/C (70 wt.%, Johnson Matthey), and the Pt loading was 0.3mg cm^-2. The effective area of the membrane electrode assembly was 5cm². The battery test conditions were: battery temperature 80 ℃, saturation humidification, H₂/O₂Flow rate 125/250mL min^-1The back pressure of the battery is 2bar, and the peak power obtained by the battery is 0.46W cm^-2(FIG. 10).

Example 6

0.1g of polyethylene oxide (PEO) was weighed out and dissolved in 9.9g of deionized water, and the solution was magnetically stirred at room temperature for 3-5h to obtain a 1 wt.% aqueous PEO solution. The electrospinning parameters were the same as in example 1. The average diameter of the resulting PEO nanofibers was 100 nm.

Ir is loaded on the surface of a PEO nanofiber template by adopting a vacuum evaporation technology, the electron beam current is controlled at 27A when the vacuum degree is 0.01Pa, and the evaporation time is 30 min. And then soaking the Ir-loaded nanofiber in deionized water at 25 ℃ to dissolve the PEO nanofiber, wherein the soaking time is 24 hours. Then transferring the sample without the template agent to a transfer printing machine in a mode of hot pressing at 140 ℃ and 2MPa for 5min

212 one side of the membrane and the stainless steel substrate is removed. The membrane electrode cleaning treatment procedure was the same as in example 1. The diameter of the hollow nanometer cell membrane prepared by using PEO as a nanometer fiber template agent is 190nm, the wall thickness of the hollow nanometer cell is 15nm, and the thickness of the catalytic layer is 200 nm.

The dried membrane electrode was used on the oxygen side of the membrane electrode assembly, and the Ir loading, as measured by ICP-OES, was 150. mu.g cm^-2(ii) a The hydrogen side of the membrane electrode was a gas diffusion electrode, the catalyst was commercial Pt/C (70 wt.%, Johnson Matthey), and the Pt loading was 0.7mg cm^-2. The effective area of the membrane electrode assembly was 5cm². The electrolytic cell test conditions are as follows: the temperature of the electrolytic cell is 80 ℃, and the water inlet flow of the anode on one side is 3mLmin^-1And the operation is carried out at normal pressure. The water electrolysis performance chart is shown in FIG. 11, and the current density is 1000mA cm^-2The electrolytic voltage was 1.592V.

Example 7

1g of polyvinylidene fluoride (PVDF) was dissolved in 9g of dimethylacetamide (DMAc) and magnetically stirred at 60 ℃ for 12 hours to obtain a 10 wt.% PVDF solution. The environmental parameters for preparing the nanofiber template agent by electrostatic spinning are as follows: temperature 30 ℃, relative humidity 10% RH; stainless steel with the thickness of 3mm is used as a substrate; the control parameters are as follows: the slurry feed rate was 0.6mL/h, the voltage was 11kV, the rotational speed of the drum receiver was 120rpm/min, the needle diameter was 0.5nm, the distance between the needle and the receiver was 11cm, and the spinning time was 120 min. The average diameter of the PVDF nanofibers obtained was 160 nm.

And simultaneously loading Pt and Ir on the surface of the PVDF nano-fiber template by adopting a magnetron sputtering technology, wherein the sputtering power is 100W, the sputtering time is 30min, and the pressure in a sputtering chamber is 0.8 Pa. And (3) roasting the Pt and Ir supported nanofiber for 3h at 800 ℃ in a nitrogen atmosphere to remove the nanofiber template. Then transferring the sample without the template agent to a transfer printing machine in a mode of hot pressing at 135 ℃ and 2MPa for 5min

212 one side of the membrane and the stainless steel substrate is removed. The membrane electrode clean-up procedure was the same as in example 1. The diameter of the obtained nano-groove is 250nm, the wall thickness of the hollow nano-groove is 25nm, and the thickness of the catalytic layer is 300 nm.

The dried membrane electrode was used on the oxygen side of the membrane electrode assembly, and the Ir loading was measured by ICP-OES as 200. mu.g cm^-2The Pt loading was 100. mu.g cm^-2(ii) a The hydrogen side of the membrane electrode was a gas diffusion electrode and the catalyst was commercial Pt/C (70 wt.%, Johnson Matt)hey), Pt supporting amount of 0.3mg cm^-2. The battery test conditions were: battery temperature 80 ℃, saturation humidification, H₂/O₂Flow rate 125/250mL min^-1The cell was backed at 2 bar. The effective area of the membrane electrode assembly was 5cm². The electrolytic cell test conditions are as follows: the temperature of the electrolytic cell is 80 ℃, and the side water inflow of the oxygen electrode is 3mL min^-1And the operation is carried out at normal pressure. The maximum power density of the integrated renewable fuel cell is 0.86W cm under the condition of a battery^-2(FIG. 12 a); in the case of electrolysis, the current density was 1000mA cm^-2The electrolytic voltage was 1.626V (FIG. 12 b).

Claims

1. The membrane electrode comprises a membrane and a catalyst layer, and is characterized in that the catalyst layer is a three-dimensional through hollow nanometer groove type; the catalyst of the catalyst layer is metal Pt or Ir, or the catalyst is a multi-element alloy formed by Pt and one of Pd, Co, Ir, Fe, Ni, Cu, Mn, Au, Ag and Ru; the loading capacity of the catalyst of the membrane electrode is 0.01-50mg cm^-2。

2. The membrane electrode as claimed in claim 1, wherein the thickness of the catalyst layer is 0.1-1 μm, the diameter of the hollow nano-groove is 50-800nm, the wall thickness of the hollow nano-groove is 2-20nm, the length is 100-800nm, and the porosity of the catalyst layer is 25-50%.

3. A method of producing a membrane electrode according to claim 1 or 2, characterized in that: the preparation method comprises the following steps:

(1) preparing a high molecular polymer solution for electrostatic spinning;

(2) carrying out electrostatic spinning on the high molecular polymer solution in the step (1) on a substrate; obtaining a nanofiber template;

(3) carrying a catalyst on the surface of the nanofiber template by a physical vapor deposition or chemical reduction method;

(5) transferring the catalyst layer with the substrate to one side or two sides of an ion exchange membrane in a hot pressing mode;

(6) and purifying to obtain the membrane electrode.

4. The membrane electrode production method according to claim 3, wherein: the high molecular polymer solution which can be used for spinning in the step (1) is water-soluble polymer and water; or the high molecular polymer solution used for spinning is high molecular polymer and organic solvent which can be dissolved in organic solvent;

the water-soluble polymer is at least one of polyacrylic acid, polyethylene oxide, polyvinyl alcohol, polyvinylpyrrolidone, cyclodextrin, sodium polyacrylate and hydroxypropyl cellulose (HPC);

the high molecular polymer soluble in the organic solvent is at least one of Polyacrylonitrile (PAN), Polystyrene (PS), polyvinyl acetate, polycarbonate, polyimide, polybenzimidazole, polyamide, polyvinyl chloride, polyaniline, polymethyl methacrylate (PMMA), polypyrrole, polythiophene and polyvinylidene fluoride;

the organic solvent is methanol, ethanol, N-propanol, isopropanol, N-methylpyrrolidone (NMP), N, N-Dimethylformamide (DMF), dimethyl sulfoxide (DMSO), N, N-dimethylacetamide (DMAc);

the concentration of the high molecular polymer solution is 0.01 wt.% to 20 wt.%.

5. The membrane electrode production method according to claim 3, wherein: in the step (2), the voltage of electrostatic spinning is 10-25kV, the feeding speed is 0.3-1mL/h, the rotating speed of a rotary drum receiver is 100-300 rpm/min, and the diameter of a needle head is 0.3-0.7 mm; environmental parameters: the temperature is 10-30 ℃, and the relative humidity is 10-50% RH; the substrate is stainless steel or aluminum foil.

6. The membrane electrode production method according to claim 3, wherein: the physical vapor deposition in the step (3) is one of vacuum evaporation, magnetron sputtering and ion plating; the chemical reduction method is one of chemical reduction impregnation, electrochemical deposition and underpotential deposition.

7. The membrane electrode production method according to claim 3, wherein: the solvent for removing the nanofiber template in the step (4) is water, methanol, ethanol, N-propanol, isopropanol, N-methylpyrrolidone (NMP), N, N-Dimethylformamide (DMF), dimethyl sulfoxide (DMSO), N, N-dimethylacetamide (DMAc); the soaking time of the solvent soaking method is 1-24h, and the soaking temperature is 20-120 ℃;

the high-temperature roasting method is to roast at the temperature of 400-.

8. The membrane electrode production method according to claim 3, wherein: the transfer pressure of the ion exchange membrane transferred in the step (5) is 0.5-10MPa, the transfer temperature is 90-160 ℃, and the hot pressing time is 1-60 min.

9. The membrane electrode production method according to claim 3, wherein: the purification step of the membrane electrode in the step (6) is as follows:

10. Use of a membrane electrode according to claim 1 or 2, characterized in that: the membrane electrode is used for proton exchange membrane fuel cells, solid polymer electrolyte water electrolysis and integrated renewable fuel cells.