CN115799543A - Ordered integrated electrode with ultralow Pt loading and preparation method thereof - Google Patents

Abstract

The invention discloses an integrated electrode with ultralow Pt loading capacity and a preparation method thereof, which are based on a composite nanowire ordered array and realize the functions of ordering the structure and simultaneously coupling electrons and protons; on the basis of the ordered composite carrier, binary or ternary active components of Pt and transition metal are prepared on the surface of the carrier by methods of adsorption reduction and underpotential deposition plus displacement reaction respectively to form an ordered integrated electrode with high catalytic activity; the electrode structure of the invention has improved degree of order, which is beneficial to realizing the high-efficiency transmission of electrode reaction substances; the proton and electron conduction functions are coupled at the same time, so that the electrode reaction efficiency can be effectively improved; active components such as noble metal Pt and the like can form an ultrathin film with the thickness of an atomic layer to be coated on the surface of the nanowire array, so that the using amount of the noble metal is obviously reduced, and the problem that the stability is influenced by agglomeration, dissolution and the like of the traditional nanoparticle catalyst in the using process is solved. The ordered integrated electrode has great application prospect in the aspects of fuel cells, water electrolysis and the like.

Description

Ordered integrated electrode with ultralow Pt loading and preparation method thereof

The technical field is as follows:

the invention relates to an ordered integrated electrode with ultralow Pt loading and a preparation method thereof, and relates to the fields of nano materials, electrochemical synthesis, fuel cells and water electrolysis cells.

The background art comprises the following steps:

membrane electrodes are the core components of fuel cells or water electrolysis cells (the reverse process of the fuel cell reaction), and their materials and structure directly affect the performance, lifetime, and cost of the cell. The traditional fuel cell electrode has the characteristics of disordered structure, low Pt utilization rate, poor stability and the like, because in the preparation process of the traditional structure electrode, a catalyst and a proton conductor are directly mixed to form slurry, the catalyst and the proton conductor in a prepared catalyst layer are distributed in a disordered manner, a high-efficiency three-phase reaction interface is not favorably constructed, a continuous through pore channel cannot be formed by the disordered structure, and the transmission of reaction gas and the discharge of water are not favorably realized. The ordered electrode structure provides a new idea for the research of the membrane electrode, and the ordered electrode generally has a relatively ordered gas-liquid/electron/proton transmission channel, so that the mass transfer resistance of gas and liquid can be reduced, the effective active area and the Pt utilization rate are improved to a certain extent, and the performance of the cell is further improved, thereby becoming the trend of the research and development of the membrane electrode.

The main direction of the research of the ordered electrode is usually realized by preparing an electrode carrier with an ordered structure, and materials generally used as the ordered electrode carrier comprise carbon nanotubes/wire arrays, metal oxides/nitrides, conductive polymers/high molecular materials and the like, and then a catalytic electrode is prepared by carrying/attaching Pt or Pt/C nanoparticle catalyst active components and the like on the surface of the ordered carrier.

Patent CN103887531A discloses an ordered gas diffusion electrode and a preparation method thereof, wherein the catalytic electrode is composed of conducting polymer nanowires arranged in an ordered manner on the surface of the gas diffusion layer, and phthalic acid diethylene glycol diacrylate (PDDA) doped on the surface and Pt catalyst nanoparticles interacting with each other. The ordered membrane electrode has the advantages of high Pt utilization rate, high stability and the like, and can effectively reduce the cost of a fuel cell catalyst; meanwhile, the mass transfer of the fuel in the catalyst layer can be effectively enhanced, so that the fuel utilization rate is improved. However, in such ordered electrodes, the catalytic active component is still nanoparticles of Pt, and under a high-potential strong-acid environment of a fuel cell, the problems of loss and agglomeration of the nanoparticles and the like inevitably exist, which affect the exertion of the electrode activity.

Patent CN106410228A discloses an ordered catalytic layer of a proton exchange membrane fuel cell and a preparation method thereof. The surface of the stainless steel is loaded with Fe, co, ni or the alloy thereof, and then the carbon layer is prepared by a CVD method. The method comprises the steps of polymerizing an ordered PPy array on the surface by an electrochemical polymerization method, firstly carrying one or two metal particle catalysts on the array, then transferring the PPy array coated with the catalysts to a Nafion membrane to construct an ordered thin-layer catalyst layer electrode, wherein the catalyst layer prepared by the method does not contain a proton conductor, the electrode reaction efficiency is limited to a certain extent, the preparation process of the electrode needs transfer operation, the preparation efficiency of the electrode and the integrity of the electrode structure are influenced, and in addition, the active components of the electrode also exist in the form of metal nanoparticles.

The invention content is as follows:

the invention aims to provide an ordered integrated electrode with ultralow Pt loading and a preparation method thereof, and the electrode has the advantages of ordered structure, electrode integration, cost reduction, precious metal utilization rate improvement and the like.

The technical purpose of the invention is realized by the following technical scheme that the ordered integrated electrode with ultralow platinum loading comprises a catalytic layer and a gas diffusion layer, and is characterized in that: the catalytic layer comprises a support, an active component and a metal substrate; the active component is Pt; the metal substrate is Pd or Pd-M, and the carrier is a composite ordered nanowire array; the active component Pt is coated on the surface of the composite ordered nanowire array carrier in a film form with a nanometer or sub-nanometer thickness; the metal substrate is positioned between the Pt film and the composite ordered nanowire array carrier in a layered mode; m in the Pd-M is a noble metal.

Further, in the above technical solution, the thickness of the thin film is 0.1nm to 3nm.

Further, in the technical proposal, the loading capacity of Pd or Pd-M on the surface of the electrode is 50-100 mu g/cm ² 。

Further, in the technical scheme, the composite ordered nanowire carrier is a composite of a conductive polymer and a proton conductor, the length of the composite ordered nanowire array is 2-15 mu m, the diameter of the composite ordered nanowire array is 50-200nm, and the loading amount of the noble metal Pt on the surface of the electrode is 2-50 mu g/cm ² 。

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

1) Preparation of composite ordered nanowire array carrier

In an electrolyte containing a proton conductor and a conductive polymer monomer, preparing a composite nanowire ordered array carrier on a gas diffusion layer by autocatalytic growth by combining a cyclic voltammetry scanning method with a potentiostatic method or combining the cyclic voltammetry scanning method with a galvanostatic method; the gas diffusion layer is carbon paper or carbon cloth

2) Preparation of the Metal substrate layer

Preparing a Pd or Pd-M metal substrate layer by using the composite ordered nanowire array carrier in the step 1) as a processing object and utilizing a continuous ion layer adsorption reaction method; m in the Pd-M is a noble metal;

3) Preparation of ultralow Pt-loaded Pt film

Under a three-electrode system, the metal substrate layer in the step 2) is taken as a working electrode and is placed in a system containing Cu ²⁺ In the second electrolyte solution, inert gas (A) is introduced into the solutionr and/or N2), realizing the deposition of the unit sublayer Cu on the surface of the metal substrate layer by using an underpotential deposition technology, and then carrying out the deposition in an inert atmosphere (Ar and/or N) ₂ ) Under protection, the working electrode is transferred to Pt-containing ²⁺ Preparing a Pt monoatomic layer based on a composite ordered carrier by utilizing a displacement reaction in a precursor solution to obtain an ordered integrated electrode;

or, the underpotential deposition of Cu and the displacement reaction of Pt are repeated to prepare continuous Pt thin film catalytic electrodes having different atomic layer thicknesses, for example, the underpotential deposition of Cu and the displacement reaction of Pt are repeated 1 to 5 times.

Further, in the above technical solution, the preparation method of the composite ordered nanowire array carrier in step 1) specifically comprises:

a. preparing an electrolyte solution I, wherein the electrolyte solution I comprises a conductive polymer monomer, a proton conductor, a structure directing agent and a phosphate buffer;

b. b, taking a carbon carrier as a reaction substrate, placing the electrolyte solution obtained in the step a in a constant temperature environment, and preparing the polypyrrole-doped perfluorinated sulfonic acid resin composite nanowire ordered array carrier on the carbon carrier through autocatalytic growth by adopting a cyclic voltammetry scanning method combined with a potentiostatic method or a cyclic voltammetry scanning method combined with a galvanostatic method;

the proton conductor is perfluorosulfonic acid resin, the conductive polymer is polypyrrole, and the monomer of the conductive polymer is a pyrrole monomer.

Further, in the above technical solution, in step 1) a, the concentration of the pyrrole monomer is 0.5-1M; the structure directing agent is one of mixed solution of sodium hexadecylsulfonate, sodium hexadecylsulfonate and sodium P-toluenesulfonate; the concentration of the structure directing agent in the electrolyte solution I is 0.5-1M; the mass fraction of the perfluorinated sulfonic acid resin in the electrolyte solution I is 0.1-10%;

in the step 1) b, the carbon carrier comprises carbon paper, carbon cloth or other carbon fibers except the carbon paper and the carbon cloth;

the cyclic voltammetry scanning method comprises the following specific steps: activating a carbon carrier by cyclic voltammetry scanning, wherein the potential interval of activation treatment is-0.241V to 0.3V, the number of scanning circles is 10-30 circles, and after the activation treatment is finished, setting the potentiostatic method as follows: setting the reaction potential at 0.8V-0.95V and the reaction time at 30min-2h;

the constant temperature environment is a constant temperature water bath kettle, and the temperature of the constant temperature water bath kettle is 25-40 ℃.

Further, in the above technical solution, the step 2) of preparing the metal substrate layer of Pd or Pd-M by using the continuous ion-layer adsorption reaction method specifically comprises the steps of:

c. firstly, using deionized water to clean the surface of the composite ordered nanowire array carrier, and repeatedly washing for 3-5 times;

d. c, soaking the composite ordered nanowire array carrier subjected to the step c in SnCl ₂ And a HCl solution to form Sn ²⁺ Adsorbing on the surface of the composite ordered nanowire array carrier, wherein the SnCl ₂ And HCl solution with concentration of 0.5-10mM and 0.1-1M respectively, soaking for 30min-2h, and keeping the temperature of the solution at 25-35 deg.C;

e. and transferring and soaking the soaked carrier in a precursor solution containing Pd or a mixed precursor solution of Pd and a noble metal M for 30min-2h, keeping the temperature of the solution at 25-35 ℃, and reacting to obtain the Pd or Pd-M metal substrate layer.

Further, in the above technical solution, in the step e, the precursor solution of Pd is 0.5-10mM PdCl ₂ +0.1-1M HCl or 0.5-10mM (PdCl) ₂ +MCl _x ) +0.1-1M HCl, wherein x is a number determined by the number of chlorides of M metal chlorides; MCl _x Wherein M is a noble metal.

Further, in the above technical solution, the ending potential of the underpotential deposition of Cu on the metal base layer in step 3) is 0-0.1V; step 3) of containing Cu ²⁺ The second electrolyte solution is 0.01 to 0.2mol/L of H ₂ SO ₄ And 0.01 to 0.2mol/L of CuSO ₄ The mixed solution of (1);

the Pt is contained ²⁺ The precursor solution is 0.1-10mM of K ₂ PtCl ₄ Or 0.1-10mM of K ₂ PtCl ₄ 。

In the metal base layer of Pd-M or MCl _x In the formula, M is one or two or more of Ru, au and Rh.

In conclusion, the invention has the following beneficial effects:

1. the ultralow platinum loading is embodied in the way that the main precious metal active component Pt in the catalytic electrode is coated on the surface of the electrode in the form of an ultrathin film (atomic layer) with nanometer or sub-nanometer thickness, but the shape of the nanometer particle exists, because the nanometer particle catalyst has the problems of agglomeration, dissolution and the like in the using process and influences the stability, and the size of the atomic layer is much smaller than that of the nanometer particle, the ultralow platinum loading can realize ultralow Pt dosage, reduce the cost, improve the precious metal utilization rate and have better chemical stability;

2. the carrier of the electrode is a composite carrier with an ordered structure, is a composite carrier of a conductive polymer and Nafion, the composite nanowire controllably prepared by an electrochemical polymerization method is simultaneously coupled with the conductive polymer and a proton conductor (such as perfluorinated sulfonic acid resin) to realize structural ordering and simultaneously coupled with the conduction functions of electrons and protons, and the ordering of the transmission of substances and the conduction of electrons and protons in the electrode reaction process is realized, so that the reaction efficiency of the electrode is improved;

3. the integration is embodied in two aspects, namely, a diffusion layer and a catalyst layer of the electrode are integrated, the composite nanowire ordered array directly grows on a gas diffusion layer such as carbon paper or carbon cloth, and then active components are coated on the surface of the nanowires, and the metal active components such as catalytic electrode Pt are coated on the surface of the nanowires instead of common nanoparticles which are dispersedly attached, so that the integration of the active components is further realized in the catalyst layer, and the electrode is beneficial to improving the structural strength and stability of the electrode and realizing the high-efficiency catalytic function of the electrode;

4. compared with the traditional electrode, the composite nanowire ordered array of the electrode is directly grown on a gas diffusion layer such as carbon paper or carbon cloth, an ordered structure carrier is prepared on stainless steel or other substrates and then transferred to the surface of a proton membrane, and a larger pressure is needed in the transfer process, so that the ordered structure is easily damaged, the preparation method of the invention completely avoids the problems, the structural order is improved, and the efficient transmission of electrode reaction substances is favorably realized;

5. the preparation of the ordered structure electrode carrier surface catalyst adopts an underpotential deposition technology, and is different from common electrodeposition or pulse electrodeposition, the preparation of the Pt monoatomic layer can be realized by accurately controlling the surface of a substrate to realize the monoatomic layer of Cu through the control of the ending potential, so that the highest utilization rate of Pt is realized; and the preparation of different atomic layer thicknesses can be realized by controlling the times of the steps so as to meet the diversified actual production requirements.

Description of the drawings:

FIG. 1 is a graph of the under-potential deposition of Cu on the surface of an ordered composite nanowire array carrier;

FIG. 2 is a scanning electron microscope photograph of an ultra-low Pt loading ordered integrated electrode surface topography;

FIG. 3 is a view of the contact angle of the surface of the integrated electrode after the composite nanowire array carrier and the Pt thin film are prepared;

FIG. 4 is a graph of cell performance with sample 1 as the cathode;

FIG. 5 is a graph of cell performance with sample 3 as the cathode;

FIG. 6 is a graph of cell performance with sample 4 as the cathode;

FIG. 7 is a graph of cell performance with sample 5 as the cathode;

fig. 8 is a graph of cell performance with sample 6 as the cathode.

The specific implementation mode is as follows:

example 1: preparation of ultralow Pt loading ordered integrated electrode based on composite nanowire array and application of electrode to fuel cell cathode

(1) Preparation of ordered nanowire array composite carrier

The carbon paper is used as a substrate, a composite carrier is prepared in a phosphate buffer solution containing pyrrole monomers, perfluorinated sulfonic acid resin and a structure directing agent by adopting a cyclic voltammetry scanning method, the concentration of the pyrrole monomers is 0.5M, the structure directing agent is 0.8M of mixed solution of sodium hexadecylsulfonate and P-sodium toluenesulfonate, and in the mixed solution, the molar ratio of the sodium hexadecylsulfonate to the P-sodium toluenesulfonate is 1:1, the mass fraction of the perfluorinated sulfonic acid resin is 1 percent; under a three-electrode system, cyclic voltammetry scanning is carried out for 20 circles in a range from-0.241V to 0.3V, the reaction potential is 0.85V, the reaction time is 30min, and the composite nanowire ordered array carrier is obtained by an electrolyte thermostatic water bath at 35 ℃.

(2) Preparation of underpotential deposition metal substrate

Cleaning the composite nanowire ordered array carrier for 3 times by using a large amount of deionized water, and firstly soaking the composite nanowire ordered array carrier into 5mM SnCl ₂ Maintaining the mixed solution of HCl solution and 0.5M for 45min at 30 deg.C; it was then transferred to 2mM PdCl ₂ Soaking in 0.5M HCl for 1h at 30 deg.C for Sn adsorbed on the surface of the array carrier ²⁺ And Pd ²⁺ Carrying out oxidation-reduction reaction to prepare a Pd substrate layer on the surface of the ordered array carrier, wherein the loading capacity of Pd is 50 mu g/cm ² 。

(3) Preparing Pt thin film active component on ordered array carrier surface

Preparing a Pt film on the surface of a Pd substrate layer by using an underpotential deposition combined displacement reaction method: under a three-electrode system, the carrier for preparing the Pd substrate layer is used as a working electrode, and the working electrode is saturated by argon gas and is 0.05M H ₂ SO ₄ And 0.05M CuSO ₄ In the mixed solution, the scanning speed is 0.2mV/s, the low-potential deposition of Cu on the surface of Pd occurs from the slow scanning of open-circuit potential to the deposition finishing potential of 0.01V (vs. SCE), the deposition of a Cu monoatomic layer is realized, and the current-voltage curve in the low-potential deposition process is shown in figure 1; the working electrode was transferred to 2mM K under inert atmosphere ₂ PtCl ₄ In the solution, the system reaction temperature is 30 ℃, the reaction time is 20min, and a displacement reaction is carried out to prepare the Pt monoatomic layer based on the composite ordered array carrier; repeatedly carrying out underpotential deposition and replacement reaction of Cu to obtain an ordered integrated electrode; the orderly integrated electrode obtained by carrying out the underpotential deposition and replacement reaction of Cu 2 times in total by the above method is recorded as sample 1, and the orderly integrated electrode obtained by carrying out the underpotential deposition and replacement reaction of Cu 3 times in total by the above method is recorded as sample 1The sequence integrated electrode was designated as sample 2, and continuous Pt thin film integrated catalytic electrodes of different atomic layer thicknesses were obtained.

Under the condition of the embodiment, the ending potential of the underpotential deposition of the Cu on the Pd base layer is 0.01V, the reduction current is sharply increased when the potential is continuously reduced, the bulk reduction deposition of the Cu occurs at the moment, and the process is uncontrollable, so the ending potential is controlled to be 0.01V, and the underpotential deposition of the Cu only occurs on the surface of the Pd to form the Cu monoatomic layer.

The surface morphology of the prepared sample 1 is observed by a scanning electron microscope, as shown in fig. 2, the ordered integrated electrode presents a regular nanowire ordered array morphology, the diameter of the nanowire is about 100 nanometers, and the length of the nanowire is about 2 micrometers. Contact angle tests are carried out on the electrode surface of the sample 1 and the surface of the ordered nanowire array composite carrier, and the results are shown in figure 3, wherein the left figure is the nanowire array composite carrier, and the right figure is the sample 1. The nanowire array composite carrier is a conducting polymer-based high polymer material, the surface contact angle of the nanowire array composite carrier reaches 140.2 degrees, after the metal substrate layer and the Pt film active component are prepared, the contact angle of the electrode surface is reduced to 102.3 degrees, and the hydrophilic characteristic of the electrode surface is optimized.

Sample 1 was used as the cathode (Pt loading 4.. 3. Mu.g/cm) ² ) With a proton exchange membrane (Nafion 211) and an anode (conventional electrode, pt loading 50. Mu.g/cm) ² ) The membrane electrode was assembled for evaluation of cell performance, and the results of the electrode test are shown in FIG. 4, in which the open circuit voltage of the single cell is 0.95V, the cell voltage is 0.56V at 1000 current density, and the maximum power density is 570mW/cm ² . For further comparison with the electrode of conventional construction, sample 2 was used as the cathode (Pt loading of 8.9. Mu.g/cm) ² ) With a proton exchange membrane (Nafion 211) and an anode (conventional electrode, pt loading 50. Mu.g/cm) ² ) The membrane electrode is assembled for evaluating the battery performance, and the battery performance of the electrode with the traditional structure is evaluated under the same condition (the Pt loading of the anode is 50 mu g/cm) ² The Pt loading capacity of the cathode is 100 mu g/cm ² ) The performance data are shown in the attached table 1, and the maximum power densities of the ultra-low Pt loading capacity orderly integrated electrode and the electrode with the traditional structure respectively reach 780mW/cm ² And 860mW/cm ² The lowest Pt dosage of the electrode is converted according to the Pt loading amount of the cathode,the traditional structure electrode is 0.12g/kW, and the Pt consumption of the ordered integrated electrode with ultra-low Pt loading capacity is only 0.01g/kW, which is reduced by one order of magnitude compared with the traditional structure electrode.

TABLE 1 comparison of cell performance with sample 2 and conventional electrode as cathode

Example 2

Preparation of ultralow Pt loading ordered integrated electrode based on composite nanowire array and application of electrode to fuel cell cathode

Carbon paper is used as a substrate, a composite carrier is prepared by adopting a cyclic voltammetry method, the concentration of pyrrole monomers in an electrolyte solution I is 1.0M, a structure directing agent is a 1.0M sodium hexadecylbenzene sulfonate solution, and the mass fraction of perfluorinated sulfonic acid resin is 1%; under a three-electrode system, cyclic voltammetry scanning is carried out for 20 circles in a range from-0.241V to 0.3V, the reaction potential is 0.95V, the reaction time is 30min, and the composite nanowire ordered array carrier is obtained in an electrolyte constant-temperature water bath at 35 ℃. The carrier was washed 3 times with deionized water and then immersed in 5mM SnCl ₂ Maintaining the mixed solution of HCl solution and 0.5M for 45min at 30 deg.C; it was then transferred to 5mM PdCl ₂ +AuCl ₃ Soaking in 0.5M HCl mixed solution for 1h, keeping the temperature of the solution at 30 ℃, and preparing a PdAu substrate layer on the surface of the ordered array carrier, wherein the loading capacity of PdAu of the substrate layer is 0.1mg/cm ² . The PdAu basal layer prepared above is used as a working electrode and is saturated with 0.05M H in argon ₂ SO ₄ And 0.05M CuSO ₄ In the mixed solution, the scanning speed is 0.2mV/s, the slow scanning is carried out from the open circuit potential to the deposition ending potential, 0.015V (vs. SCE) is carried out, the underpotential deposition of Cu on the surface of PdAu is generated, and the working electrode is transferred to 2mM K under the protection of inert atmosphere ₂ PtCl ₄ In the solution, the reaction temperature of the system is 30 ℃, the reaction time is 20min, and a Pt monoatomic layer based on the composite carrier is prepared; repeatedly carrying out underpotential deposition and replacement reaction of Cu to obtain an ordered integrated electrode; the method is adopted to carry out underpotential deposition and replacement reaction of Cu for 2 times in total to prepare the ordered IThe integrated electrode was designated as sample 3. Sample 3 was used as the cathode, with a proton exchange membrane (Nafion 211) and an anode (conventional electrode, pt loading 50. Mu.g/cm) ² ) The membrane electrode was assembled for evaluation of cell performance, and the results of the electrode tests are shown in FIG. 5, the open circuit voltage of the single cell is 0.96V, the cell voltage is 0.58V at 1000 current density, and the maximum power density is up to 580mW/cm ² 10000 circles of accelerated scanning is performed, the power density loss of the battery is only 3%, and the ultrahigh stability of the ordered electrode is reflected.

Example 3

Preparation of ultralow Pt loading ordered integrated electrode based on composite nanowire array and application of electrode to fuel cell cathode

The carbon paper is used as a substrate, the composite carrier is prepared by adopting a cyclic voltammetry method, the concentration of pyrrole monomers in the electrolyte solution I is 0.5M, the structure directing agent is a mixed solution of 1.0M sodium hexadecylbenzene sulfonate solution and P-sodium toluene sulfonate, and in the mixed solution, the molar ratio of sodium hexadecylbenzene sulfonate to P-sodium toluene sulfonate is 1:1, the mass fraction of the perfluorinated sulfonic acid resin is 1 percent; under a three-electrode system, cyclic voltammetry scanning is carried out for 20 circles in a range from-0.241V to 0.3V, the reaction potential is 0.8V, the reaction time is 30min, and the composite nanowire ordered array carrier is obtained by an electrolyte thermostatic water bath at 35 ℃. The carrier was washed 3 times with deionized water and then immersed in 5mM SnCl ₂ Maintaining the mixed solution of HCl solution and 0.5M for 45min at 30 deg.C; it was then transferred to 5mM PdCl ₂ Soaking in 0.5M HCl for 1h at 30 deg.C to obtain Pd substrate layer with Pd loading of 0.1mg/cm ² . Using the prepared Pd substrate layer as a working electrode, and saturating the working electrode with 0.05M H in argon ₂ SO ₄ And 0.05M CuSO ₄ In the mixed solution (2), an underpotential deposition of Cu on the Pd surface is caused by slow scanning from the open circuit potential to the deposition termination potential of 0.01V (vs. SCE) at a scanning speed of 0.2mV/s, and the working electrode is transferred to 2mM Na under the protection of an inert atmosphere ₂ PtCl ₄ In the solution, the reaction temperature of the system is 30 ℃, the reaction time is 20min, and a Pt monoatomic layer based on the composite carrier is prepared and recorded as a sample 4. Sample 4 was used as the cathode, with a proton exchange membrane (Nafion 211) and the anodePole (conventional electrode, pt loading 50. Mu.g/cm) ² ) The membrane electrode was assembled for evaluation of cell performance, and the results of the electrode tests are shown in FIG. 6, in which the open-circuit voltage of the single cell is 0.93V, the cell voltage is 0.55V at 1000 current density, and the maximum power density is 550mW/cm ² 。

Comparative example 1

Preparation of ultralow Pt loading ordered integrated electrode based on composite nanowire array and application of electrode to fuel cell cathode

The carbon paper is used as a substrate, a composite carrier is prepared by adopting a cyclic voltammetry method, the concentration of pyrrole monomers in an electrolyte solution I is 0.5M, a structure directing agent is a mixed solution of 1.0M sodium hexadecylbenzene sulfonate solution and P-sodium toluene sulfonate, and the molar ratio of the sodium hexadecylbenzene sulfonate to the P-sodium toluene sulfonate in the mixed solution is 1:1, adding no perfluorinated sulfonic acid resin into the electrolyte solution I; under a three-electrode system, cyclic voltammetry scanning is carried out for 20 circles in a range from-0.241V to 0.3V, the reaction potential is 0.8V, the reaction time is 30min, and the composite nanowire ordered array carrier is obtained in an electrolyte constant-temperature water bath at 35 ℃. The carrier was washed 3 times with deionized water and then immersed in 5mM SnCl ₂ Maintaining the mixed solution of HCl solution and 0.5M for 45min at 30 deg.C; it was then transferred to 5mM PdCl ₂ And 0.5M HCl for 1h, keeping the temperature of the solution at 30 ℃, and preparing a Pd substrate layer on the surface of the ordered array carrier. Using the Pd substrate layer prepared above as a working electrode, and saturating the Pd substrate layer with 0.05M H in argon ₂ SO ₄ And 0.05M CuSO ₄ In the mixed solution, the low-potential deposition of Cu on the surface of Pd occurs at a scanning speed of 0.2mV/s from the open circuit potential to the deposition end potential of 0.01V (vs. SCE), and the working electrode is transferred to 2mM Na under the protection of inert atmosphere ₂ PtCl ₄ In the solution, the reaction temperature of the system is 30 ℃, the reaction time is 20min, and a Pt monoatomic layer based on the composite carrier is prepared and recorded as a sample 5. Sample 5 was used as the cathode with a proton exchange membrane (Nafion 211) and an anode (conventional electrode, pt loading 50. Mu.g/cm) ² ) The membrane electrode is assembled for evaluating the performance of the battery, and because the electrolyte solution is not added with the perfluorinated sulfonic acid resin and the carrier is not provided with a proton conductor, the proton conduction efficiency is low, and the reverse of the electrode is causedThe efficiency is low, the electrode performance is poor, the test result of the electrode is shown in figure 7, the open-circuit voltage of a single cell is 0.93V, the cell voltage is only 0.50V under the current density of 1000, and the maximum power density is 500mW/cm ² 。

Comparative example 2

Preparation and performance test of Pt/C nanoparticle-supported catalytic electrode on surface of ordered nanowire array

Carbon paper is used as a substrate, a composite carrier is prepared by adopting a cyclic voltammetry method, the concentration of pyrrole monomers in an electrolyte solution I is 1.0M, a structure directing agent is a 1.0M sodium hexadecylbenzene sulfonate solution, and the mass fraction of perfluorinated sulfonic acid resin is 1%; under a three-electrode system, cyclic voltammetry scanning is carried out for 20 circles in a range from-0.241V to 0.3V, the reaction potential is 0.95V, the reaction time is 30min, and the composite nanowire ordered array carrier is obtained in an electrolyte constant-temperature water bath at 35 ℃. An electrode of an ordered array carrier loaded Pt nano particle catalyst is prepared on the surface of a carrier in an ultrasonic spraying mode and is marked as a sample 6, and the Pt loading capacity of the electrode is controlled to be 0.1mg/cm by controlling slurry and spraying parameters ² . Sample 6 was used as the cathode with a proton exchange membrane (Nafion 211) and an anode (conventional electrode, pt loading 50. Mu.g/cm) ² ) The membrane electrode was assembled for cell performance and accelerated decay stability testing, and the results of the electrode testing are shown in FIG. 8, with single cell open circuit voltage of 0.96V, cell voltage of 0.59V at 1000 current density, and maximum power density of 720mW/cm ² 10000 cycles of accelerated scanning shows that the power density loss of the battery reaches 18.9 percent, and the stability of the battery is far lower than that of the ultralow platinum loading ordered integrated electrode (embodiment 2).

Claims (10)

1. An ordered integrated electrode with ultra-low platinum loading comprising a catalytic layer and a gas diffusion layer, characterized in that: the catalytic layer comprises a support, an active component and a metal substrate; the active component is Pt; the metal substrate is Pd or Pd-M, and the carrier is a composite ordered nanowire array; the active component Pt is coated on the surface of the composite ordered nanowire array carrier in a film form with a nanometer or sub-nanometer thickness; the metal substrate is positioned between the Pt thin film and the composite ordered nanowire array carrier in a layered mode; m in the Pd-M is a noble metal.

2. The electrode of claim 1, wherein: the thickness of the film is 0.1 nm-3 nm.

3. The electrode of claim 1 or 2, wherein: the Pd or Pd-M is loaded on the surface of the electrode at 50-100 mu g/cm ² 。

4. The electrode of claim 1 or 2, wherein: the composite ordered nanowire carrier is a composite of a conductive polymer and a proton conductor, the length of the composite ordered nanowire array is 2-15 mu m, the diameter of the composite ordered nanowire array is 50-200nm, and the loading capacity of the noble metal Pt on the surface of the electrode is 2-50 mu g/cm ² 。

5. The method for preparing the electrode according to any one of claims 1 to 4, comprising the following steps:

1) Preparation of composite ordered nanowire array carrier

Preparing a composite nanowire ordered array carrier on a gas diffusion layer by adopting a cyclic voltammetry scanning method combined with a potentiostatic method or a cyclic voltammetry scanning method combined with a galvanostatic method in an electrolyte containing a proton conductor and a conductive polymer monomer; the gas diffusion layer is carbon paper or carbon cloth;

2) Preparation of the Metal substrate layer

Preparing a Pd or Pd-M metal substrate layer by using the composite ordered nanowire array carrier in the step 1) as a processing object and utilizing a continuous ion layer adsorption reaction method; m in the Pd-M is a noble metal;

3) Preparation of ultralow Pt loading Pt film

Under a three-electrode system, the metal substrate layer in the step 2) is taken as a working electrode and is placed in a system containing Cu ²⁺ In the second electrolyte solution, the deposition of the monoatomic layer Cu on the surface of the metal substrate layer is realized by using an underpotential deposition technology, and then the working electrode is transferred to the Pt-containing material under the protection of inert atmosphere ²⁺ In the precursor solution, the composite base is prepared by utilizing a displacement reactionThe ordered integrated electrode is obtained by the Pt monoatomic layer of the ordered carrier;

or repeatedly carrying out underpotential deposition of Cu and replacement reaction of Pt to prepare continuous Pt thin film catalytic electrodes with different atomic layer thicknesses.

6. The method of claim 5, wherein: the preparation method of the composite ordered nanowire array carrier in the step 1) specifically comprises the following steps:

a. preparing an electrolyte solution I, wherein the electrolyte solution I comprises a conductive polymer monomer, a proton conductor, a structure directing agent and a phosphate buffer;

b. b, taking a carbon carrier as a reaction substrate, placing the electrolyte solution obtained in the step a in a constant temperature environment, and preparing the polypyrrole-doped perfluorinated sulfonic acid resin composite nanowire ordered array carrier on the carbon carrier through autocatalytic growth by adopting a cyclic voltammetry scanning method combined with a potentiostatic method or a cyclic voltammetry scanning method combined with a galvanostatic method;

the proton conductor is perfluorosulfonic acid resin, the conductive polymer is polypyrrole, and the monomer of the conductive polymer is a pyrrole monomer.

7. The method of manufacturing according to claim 6, characterized in that: in the step 1) a, the concentration of the pyrrole monomer is 0.5-1M;

the structure directing agent is one of mixed solution of sodium hexadecylsulfonate, sodium hexadecylsulfonate and sodium P-toluenesulfonate; the concentration of the structure directing agent in the electrolyte solution I is 0.5-1M;

the mass fraction of the perfluorinated sulfonic acid resin in the electrolyte solution I is 0.1-10%;

in the step 1) b, the carbon carrier comprises carbon paper, carbon cloth or other carbon fibers except the carbon paper and the carbon cloth;

the cyclic voltammetry scanning method comprises the following specific steps: activating a carbon carrier by cyclic voltammetry scanning, wherein the potential interval of activation treatment is-0.241V to 0.3V, the number of scanning circles is 10-30 circles, and after the activation treatment is finished, setting the potentiostatic method as follows: setting the reaction potential at 0.8V-0.95V and the reaction time at 30min-2h;

the constant temperature environment is a constant temperature water bath kettle, and the temperature of the constant temperature water bath kettle is 25-40 ℃.

8. The method of claim 5, wherein: the method for preparing the Pd or Pd-M metal substrate layer by using the continuous ion layer adsorption reaction method in the step 2) comprises the following specific steps:

c. firstly, using deionized water to clean the surface of the composite ordered nanowire array carrier, and repeatedly washing for 3-5 times;

d. c, soaking the composite ordered nanowire array carrier in SnCl ₂ And a HCl solution to form Sn ²⁺ Adsorbing on the surface of the composite ordered nanowire array carrier, wherein the SnCl ₂ And HCl solution with concentration of 0.5-10mM and 0.1-1M respectively, soaking for 30min-2h, and keeping the temperature of the solution at 25-35 deg.C;

e. and transferring and soaking the soaked carrier in a precursor solution containing Pd or a mixed precursor solution of Pd and a noble metal M for 30min-2h, keeping the temperature of the solution at 25-35 ℃, and reacting to obtain the Pd or Pd-M metal substrate layer.

9. The method for producing according to claim 8, characterized in that: in the step e, the precursor solution of Pd is 0.5-10mM PdCl ₂ +0.1-1M HCl or 0.5-10mM (PdCl) ₂ +MCl _x ) +0.1-1M HCl, wherein x is a number determined by the number of chlorides of M metal chlorides; MCl _x And M is a noble metal.

10. The production method according to claim 5, characterized in that: the ending potential of the underpotential deposition of Cu on the metal substrate layer in the step 3) is 0-0.1V; step 3) of containing Cu ²⁺ The second electrolyte solution is 0.01 to 0.2mol/L of H ₂ SO ₄ And 0.01 to 0.2mol/L of CuSO ₄ The mixed solution of (1);

the Pt is contained ²⁺ The precursor solution is0.1-10mM K ₂ PtCl ₄ Or 0.1-10mM of K ₂ PtCl ₄ 。

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