CN103887531B - A kind of ordering gas-diffusion electrode and preparation thereof and application - Google Patents

Abstract

The present invention relates to a kind of ordering gas-diffusion electrode and preparation thereof and application, described membrane electrode is made up of gas diffusion layers and Catalytic Layer, described Catalytic Layer is ordering Catalytic Layer, and it is due to the conductive polymer nanometer line of gas diffusion layers surface ordering array arrangement and is doped in the PDDA (PDDA) on conductive polymer nanometer line surface and interacts with Pt catalyst particle and form.Ordering membrane electrode of the present invention has precious metals pt utilization rate height, stability advantages of higher, can effectively reduce fuel-cell catalyst cost, improves fuel battery service life；Meanwhile, membrane electrode of the present invention can effectively strengthen fuel mass transfer in Catalytic Layer, thus improves the utilization rate of fuel；Ordering membrane electrode of the present invention can be as Proton Exchange Membrane Fuel Cells, direct liquid fuel battery and PEM water type electrolyzer membrane electrode.

Description

An ordered gas diffusion electrode and its preparation and application

technical field

The invention relates to an ordered gas diffusion electrode and its preparation and application, in particular to a gas diffusion electrode that can be used in a proton exchange membrane fuel cell, a direct liquid fuel cell or a proton exchange membrane type water electrolysis cell. The present invention also relates to a preparation method of the above ordered gas diffusion electrode.

Background technique

Due to its high efficiency and environmental friendliness, proton exchange membrane fuel cells have been paid close attention to by research institutions in various countries in recent years. Membrane electrode (MEA), as the core component of fuel cell, usually consists of gas diffusion layer, catalytic layer and proton exchange membrane. The catalytic layer is the place where the electrochemical reaction occurs in the membrane electrode assembly (MEA). The performance and stability of the catalytic layer largely determine the electrochemical performance of the MEA. At the same time, the cost of the electrocatalyst in the catalytic layer also accounts for the total cost of the MEA. a large percentage of the cost. In order to improve the performance and stability of the catalytic layer and reduce the amount of electrocatalyst, it is a new method to design and prepare MEA with a catalytic layer with ordered microstructure. At present, the commonly used preparation method of the catalytic layer in MEA is: disperse the electrocatalyst in ethanol, ethylene glycol and other solvents, add an appropriate amount of As a binder, it is fully dispersed to form a uniform catalyst slurry. The catalyst slurry is prepared by spraying, brushing and other methods to form a gas diffusion electrode with a GDE structure on the diffusion layer, or to form a membrane electrode with a CCM structure on the proton exchange membrane. In the traditional gas diffusion electrode or membrane electrode mentioned above, the catalyst particles are Under the action of the binder, a loose and porous thin layer is formed, and the mass transfer resistance of the reactants in the disordered pores is relatively large, which affects the overall performance of the battery.

In summary, the preparation and development of MEA with nano-ordered catalytic layer is very important for reducing the cost of PEMFC and improving the performance of PEMFC.

The self-assembly of Pt-PDDA to prepare the catalytic layer is a self-assembly process using the positively charged groups of PDDA and negatively charged Pt-containing ions, such as chloroplatinate ions, through the electrostatic interaction of positive and negative charges, and then through chemical reduction. Prepare highly dispersed Pt nanoparticles to improve the dispersion of Pt loading and thus improve the utilization of Pt. The methods reported in the literature usually use direct self-assembly on the surface of disordered carbon supports, and the stability of the catalytic layer at high potential and the material transfer performance are not good.

Contents of the invention

The object of the present invention is to provide a novel ordered gas diffusion electrode, which has the advantages of high Pt catalyst stability, high effective utilization rate, good mass transfer performance of the catalytic layer, etc., and can be used as a proton exchange membrane fuel cell, Direct liquid fuel cell or proton exchange membrane type water electrolysis cell.

In order to achieve the above object, the present invention adopts the following specific solutions to achieve:

An ordered gas diffusion electrode, comprising a gas diffusion layer and an ordered catalytic layer based on the gas diffusion layer, the ordered catalytic layer is attached to the surface of the gas diffusion layer, and microscopically has a direction perpendicular to the surface of the gas diffusion layer Orientation-ordered nanowire array structure.

The ordered catalytic layer includes polythiophene or polythiophene derivatives or polypyrrole or polypyrrole derivatives or polyaniline or polyaniline derivatives in a microcosmic array of conductive polymer nanowires, and attached to PDDA on conductive polymer nanowires, and Pt nanoparticles attached to PDDA;

The loading amount of conductive polymer nanowires in the ordered catalytic layer is 0.5 mgcm ^{-2 , the loading amount of PDDA is 5 μgcm -2 ,} and the loading amount of Pt nanoparticles is 0.01-0.5 mgcm ^-2 .

The gas diffusion layer is composed of a support layer and a microporous layer attached to the surface of the support layer; the support layer is carbon paper or carbon cloth; the microporous layer is VulcanXC-72 carbon powder, acetylene black carbon powder , carbon nanotubes or graphene mixed with PTFE or Nafion and then scraped, brushed or sprayed onto the surface of the support layer.

The preparation method of the ordered gas diffusion electrode comprises the following preparation steps,

a. Preparation of ordered nanowire array structure doped with PDDA (diethylene glycol diacrylate)

Electrodeposition of conductive polymer polythiophene or polythiophene derivatives or polypyrrole or polypyrrole derivatives or polyaniline doped with PDDA on the surface of the gas diffusion layer or the surface of the microporous layer of the gas diffusion layer by electrodeposition One of the polyaniline derivatives to obtain a microscopically ordered PDDA-doped conductive polymer nanowire array structure in the direction perpendicular to the surface of the diffusion layer;

b. Self-assembly preparation of the catalytic layer

Apply chloroplatinic acid aqueous solution with a Pt concentration of 1-10mgmL ^-1 at 10-100 μL per square centimeter to the surface of the nanowire array structure obtained in the above step a, and let it stand at room temperature for 12-24 hours; add 2-10 times the Pt substance Amount of ascorbic acid aqueous solution or sodium borohydride aqueous solution or dimethylammonium borane aqueous solution or hydrazine hydrate drop-coated on the surface of the conductive polymer nanowire array, let it stand for 2-10 hours, rinsed with deionized water and dried at room temperature , to obtain an ordered gas diffusion electrode.

The electrodeposition method in the step a is specifically: immersing one side of the gas diffusion layer in an electrolytic solution containing one of thiophene or pyrrole or aniline or thiophene derivatives or pyrrole derivatives or aniline derivative solutions, and simultaneously containing a supporting electrolyte and PDDA. In the solution, the gas diffusion layer was used as the working electrode, the Pt sheet was used as the counter electrode, and the saturated calomel electrode was used as the reference electrode, and a three-electrode system was used for electrodeposition.

In step a, when the molecular weight of the PDDA is less than one hundred thousand, the mass concentration of the PDDA aqueous solution is 20-30%; when the molecular weight of the PDDA is less than two hundred thousand or more than one hundred thousand, the concentration of the PDDA aqueous solution is greater than 30%. , and less than or equal to 50%;

In step b, the concentration of the chloroplatinic acid aqueous solution is 1-10 mg·ml ^-1 .

The concentration of thiophene or pyrrole or aniline or thiophene derivatives or pyrrole derivatives or aniline derivatives in the electrolyte solution in the electrodeposition process is 0.01-0.5M;

The supporting electrolyte added in the electrolyte solution in the electrodeposition process is sodium p-toluenesulfonate, sodium dodecylsulfonate, β-naphthalenesulfonic acid, bistrimethylsilyl trifluoroacetamide, perchlorate, sulfuric acid One or more of salt and chloride; the concentration of the supporting electrolyte in the electrolyte solution during the electrodeposition process is 0.01-0.5M;

The electrodeposition potential of the electrodeposition is 0.75-1.1V (vsNHE);

The electrodeposition time length of the electrodeposition is 0.25-1h.

The mass concentration of PDDA in the electrolyte is 0.05-5%.

The ordered gas diffusion electrode can be used in a proton exchange membrane fuel cell, or a direct liquid fuel cell, or a proton exchange membrane type water electrolysis cell.

Compared with the prior art, the present invention has the following advantages:

1. High stability of the catalyst: Compared with the membrane electrode prepared by the traditional process (including the gas diffusion electrode of the GDE structure and the membrane electrode of the CCM structure, the same below), the gas diffusion electrode described in the present invention, because the Pt catalyst nanoparticles are attached to On the conductive polymer arranged in an orderly array, it has the advantage of high catalyst stability;

2. High utilization rate of the catalyst: Compared with the traditional membrane electrode, the ordered gas diffusion electrode prepared by the method of the present invention increases the effective utilization area of the catalyst and improves the oxygen reduction capacity per unit mass of the catalyst;

3. Good mass transfer performance in the catalytic layer: using the ordered gas diffusion electrode of the present invention, since the catalytic layer is arranged in an ordered array, compared with the traditional disordered catalytic layer, the fuel or oxidant is Better mass transfer performance in the catalytic layer;

4. Strong practicability: Compared with using other substrates such as silicon, gold, quartz, etc. to grow ordered nanostructures, this method uses a gas diffusion layer as a growth substrate for ordered nanostructures of conductive polymers. The method is simple and does not require subsequent hot pressing Such stripping steps do not destroy the integrity of the structure, and the stability of conductive polymers at high potentials is better than that of carbon materials, and catalyst aggregation due to carbon corrosion does not occur.

Description of drawings

Fig. 1 is a structural schematic diagram of (a) ordered gas diffusion electrode and (b) traditional gas diffusion electrode according to the present invention. It can be seen from the figure that compared with the traditional gas diffusion electrode (b), ① the loading of Pt catalyst in the ordered gas diffusion electrode (a) is relatively low; ② in the ordered gas diffusion electrode (a), Pt is combined with PDDA on the surface of the ordered conductive polymer through electrostatic interaction, which realizes the highly dispersed loading of Pt nanoparticles, improves the catalyst loading and the proportion of catalysts that can be effectively used when exposed to the surface; ③ordered The array arrangement structure formed in the gas diffusion electrode (a) is conducive to the mass transfer of reactants and reaction products in the catalytic layer, which is conducive to improving the utilization rate of reactants, thereby improving battery performance.

Fig. 2 is an electron micrograph (embodiment 1) after the electro-deposition of conductive polymer PPy on the surface of the diffusion layer by the method of the present invention; The ordered array structure improves the effective loading area of Pt particles and provides a channel for effective material transfer.

Fig. 3 is an electron micrograph (embodiment 1) of an ordered gas diffusion electrode prepared by the method of the present invention after carrying a catalyst; it can be seen that Pt nanoparticles are uniformly distributed on the surface of PPy, and in the presence of PDDA The sites present agglomerated particle clusters, making the Pt particles effectively exposed to the three-phase reaction interface and improving the utilization of the Pt particles.

Fig. 4 is the cyclic voltammetry curve of ordering membrane electrode catalyst (a) in embodiment 1 and the commodity E-Tek catalyst (b) in comparative example 1, and electrolytic solution is N ₂ saturated 0.5M sulfuric acid solution, scan speed The rate is 50mV·s ^-1 . As can be seen from the calculation results of this figure, the electrochemically active surface area of the ordered membrane electrode catalyst layer in Example 1 can reach 55.4 square meters per gram of platinum, compared with the electrochemically active surface area of the commercial catalyst in Comparative Example 1 of 39.6 The square meter per gram of platinum has increased by 40%, and the utilization rate of the catalyst has been greatly improved.

Figure 5 shows the cyclic voltammetry test curves before and after the aging test of the ordered gas diffusion electrode catalyst (a) in Example 1 and the traditional gas diffusion electrode commercial E-Tek catalyst (b) in Comparative Example 1, and Figure 5 (c) is the aging test The normalized electrochemical surface area of the catalyst in the catalytic layer before and after the test; the electrolyte solution is N2-saturated 0.5M sulfuric acid solution, the scanning range is 0.85-1.2Vvs.NHE, the scanning rate is 200mV s ^-1 , and the number of scanning cycles is 1000 lock up. It can be seen from the figure that after 1000 cycles of scanning, the electrochemically active surface area of the catalyst in the catalytic layer of the ordered gas diffusion electrode can be maintained at more than 60% of that before the aging test. The electrochemically active surface area of the catalyst decreased to about 40% before the aging test, mainly because the catalyst carrier on the ordered gas diffusion electrode was a conductive polymer, and the conductive polymer was not easy to corrode at a high potential, so its stability Compared with the stability of the carbon-supported catalyst in the traditional gas diffusion electrode, it shows that the ordered gas diffusion electrode structure plays an important role in maintaining the stability of the catalyst.

The oxygen reduction test curves of ordered gas diffusion electrode catalyst (a) in Fig. 6 embodiment 1 and traditional gas diffusion electrode commercial E-Tek catalyst (b) in comparative example ₁ before and after aging test, wherein the electrolyte solution is O Saturated 0.5M sulfuric acid solution, the scan rate is 20mV·s ^-1 . It can be seen from the figure that after 1000 cycles of scanning, the oxygen reduction half-wave potential of the catalyst in the catalytic layer of the ordered gas diffusion electrode dropped by about 8mV, while the oxygen reduction half-wave potential of the E-Tek catalyst in the catalytic layer of the traditional gas diffusion electrode The potential drops by more than 20mV, which is mainly due to the fact that the catalyst carrier on the ordered gas diffusion electrode is a conductive polymer, and the conductive polymer is not easy to corrode at a high potential, so its stability is compared with that of the carbon-supported catalyst in the traditional gas diffusion electrode. The stability of the catalyst is good, which means that the structure in the ordered gas diffusion electrode plays an important role in maintaining the catalytic oxygen reduction stability of the catalyst.

detailed description

The present invention is described in detail by examples below, but the present invention is not limited to the following examples.

Example 1:

1) Preparation of gas diffusion layer:

Soak Toray carbon paper in 20% PTFE aqueous solution, take it out and air dry after fully soaking, and weigh it. Repeat the above steps until the PTFE loading is about 15% (the mass of carbon paper after hydrophobization treatment). Mix VulcanXC-72 carbon powder with 20% PTFE aqueous solution at a mass concentration of 10% relative to the mass of carbon powder and PTFE, and dilute with ethanol 20 times the mass of carbon powder, disperse under ultrasonic conditions for 20 minutes, and stir evenly. The above-mentioned hydrophobized carbon paper was placed on a glass plate and fixed, and the above-mentioned slurry was scraped on the surface of the carbon paper and weighed until the carbon powder loading was 1 mgcm ^-2 , and the gas diffusion layer was obtained.

2) Preparation of ordered gas diffusion electrodes:

a. Preparation of surface-modified ordered nanowire array structure

The gas diffusion layer obtained in the above step 1) is placed in a plastic fixture, and a conductive platinum sheet is inserted into the plastic fixture, and at the same time, good contact between the conductive platinum sheet and the gas diffusion layer is ensured. The above device was placed in a three-electrode electrodeposition system, the conductive platinum sheet in good contact with the gas diffusion layer was used as the working electrode, the saturated calomel electrode was used as the counter electrode and the reference electrode, and the electrolyte contained 0.1M pyrrole, 0.1M Sodium toluenesulfonate, 0.2M phosphate buffer solution of ultra-low molecular weight (MW<100,000) PDDA with a mass concentration of 1%, applied a working voltage of 0.65V (vsSCE) on the conductive platinum sheet for 30min, that is, the electrode on the surface of the gas diffusion layer A layer of polypyrrole (PPy) doped with PDDA arranged in an ordered array was deposited and labeled as PDDAPPy-GDL sample.

b. Self-assembly preparation of catalytic layer

An aqueous solution of chloroplatinic acid containing 7.4 mgmL ^-1 of Pt was drop-coated at 20 μL per square centimeter on the conductive polymer surface of the PDDAPPy-GDL sample obtained in step 2) a above, and left to stand for 24 hours. The ascorbic acid aqueous solution with a concentration of 37mgmL ^-1 was also drop-coated at 20 μL per square centimeter on the conductive polymer surface of the PDDAPPy-GDL sample drop-coated with chloroplatinic acid, and left to stand for 4 hours. After the surface liquid color changed from bright yellow to a colorless transparent solution, the conductive polymer surface of the PDDAPPy-GDL sample loaded with the catalyst was repeatedly washed with deionized water, and the ordered gas diffusion electrode was obtained after air drying.

Example 2:

1) Preparation of gas diffusion layer:

Soak Toray carbon paper in 20% PTFE aqueous solution, take it out and air dry after fully soaking, and weigh it. Repeat the above steps until the PTFE loading is about 15% (the mass of carbon paper after hydrophobization treatment). Mix VulcanXC-72 carbon powder with 20% PTFE aqueous solution at a mass concentration of 10% relative to the mass of carbon powder and PTFE, and dilute with ethanol 20 times the mass of carbon powder, disperse under ultrasonic conditions for 20 minutes, and stir evenly. The above-mentioned hydrophobized carbon paper was placed on a glass plate and fixed, and the above-mentioned slurry was scraped on the surface of the carbon paper and weighed until the carbon powder loading was 1 mgcm ^-2 , and the gas diffusion layer was obtained.

The graphene powder prepared by the thermal expansion method was ultrasonically dispersed in the ethanol solution, and the slurry was loaded on the surface of the microporous layer of the gas diffusion layer by the scraping method, and weighed until the loading was 0.2 mgcm ^-2 . A graphene-modified gas diffusion layer is obtained.

2) Preparation of ordered gas diffusion electrodes:

a. Preparation of surface-modified ordered nanowire array structure

The gas diffusion layer obtained in the above step 1) is placed in a plastic fixture, and a conductive platinum sheet is inserted into the plastic fixture, and at the same time, good contact between the conductive platinum sheet and the gas diffusion layer is ensured. The above device was placed in a three-electrode electrodeposition system, and the electrolyte was 0.2M phosphate buffer containing 0.1M pyrrole, 0.1M sodium p-toluenesulfonate, and ultra-low molecular weight (MW<100,000) PDDA with a mass concentration of 1%. , a working voltage of 0.65V (vsSCE) was applied to the conductive platinum sheet for 30 minutes, that is, a layer of polypyrrole (PPy) doped with PDDA arranged in an orderly array was formed by electrodeposition on the surface of the gas diffusion layer, marked as PDDAPPy-GDL sample.

b. Self-assembly preparation of catalytic layer

An aqueous solution of chloroplatinic acid containing 7.4 mgmL ^-1 of Pt was drop-coated at 20 μL per square centimeter on the gas diffusion layer grown with ordered conductive polymer nanostructures obtained in the above step 2) a, and left to stand for 24 hours. The ascorbic acid aqueous solution with a concentration of 37mgmL ^-1 was also drop-coated at 20 μL per square centimeter on the surface of the above-mentioned electrode drop-coated with chloroplatinic acid, and left to stand for 4 hours. After the color of the surface liquid changes from bright yellow to a colorless transparent solution, the surface of the ordered membrane electrode loaded with the catalyst is repeatedly washed with deionized water, and the ordered membrane electrode is obtained after air-drying.

Example 3:

1) Preparation of gas diffusion layer:

Soak Toray carbon paper in 20% PTFE aqueous solution, take it out and air dry after fully soaking, and weigh it. Repeat the above steps until the PTFE loading is about 15% (the mass of carbon paper after hydrophobization treatment). Mix VulcanXC-72 carbon powder with 20% PTFE aqueous solution at a mass concentration of 10% relative to the mass of carbon powder and PTFE, and dilute with ethanol 20 times the mass of carbon powder, disperse under ultrasonic conditions for 20 minutes, and stir evenly. The above-mentioned hydrophobized carbon paper was placed on a glass plate and fixed, and the above-mentioned slurry was scraped on the surface of the carbon paper and weighed until the carbon powder loading was 1 mgcm ^-2 , and the gas diffusion layer was obtained.

The multi-walled carbon nanotube powder prepared by chemical vapor deposition is ultrasonically dispersed in ethanol solution, and the slurry is loaded on the surface of the microporous layer of the gas diffusion layer by scraping method, and weighed until the loading is 0.2 mgcm ^-2 . A gas diffusion layer decorated with carbon nanotubes is obtained.

2) Preparation of ordered membrane electrodes:

a. Preparation of surface-modified ordered nanowire array structure

The gas diffusion layer obtained in the above step 1) is placed in a plastic fixture, and a conductive platinum sheet is inserted into the plastic fixture, and at the same time, good contact between the conductive platinum sheet and the gas diffusion layer is ensured. The above device was placed in a three-electrode electrodeposition system, and the electrolyte was 0.2M phosphate buffer containing 0.1M pyrrole, 0.1M sodium p-toluenesulfonate, and ultra-low molecular weight (MW<100,000) PDDA with a mass concentration of 1%. , a working voltage of 0.65V (vsSCE) was applied to the conductive platinum sheet for 30 minutes, that is, a layer of polypyrrole (PPy) doped with PDDA arranged in an orderly array was formed by electrodeposition on the surface of the gas diffusion layer, marked as PDDAPPy-GDL sample.

b. Self-assembly preparation of catalytic layer

An aqueous solution of chloroplatinic acid containing 7.4 mgmL ^-1 of Pt was drop-coated at 20 μL per square centimeter on the gas diffusion layer grown with ordered conductive polymer nanostructures obtained in the above step 2) a, and left to stand for 24 hours. The ascorbic acid aqueous solution with a concentration of 37mgmL ^-1 was also drop-coated at 20 μL per square centimeter on the surface of the above-mentioned electrode drop-coated with chloroplatinic acid, and left to stand for 4 hours. After the color of the surface liquid changes from bright yellow to a colorless transparent solution, the surface of the ordered membrane electrode loaded with the catalyst is repeatedly washed with deionized water, and the ordered membrane electrode is obtained after air-drying.

Example 4:

1) Preparation of gas diffusion layer:

Soak Toray carbon paper in 20% PTFE aqueous solution, take it out and air dry after fully soaking, and weigh it. Repeat the above steps until the PTFE loading is about 15% (the mass of carbon paper after hydrophobization treatment). Mix VulcanXC-72 carbon powder with 20% PTFE aqueous solution at a mass concentration of 10% relative to the mass of carbon powder and PTFE, and dilute with ethanol 20 times the mass of carbon powder, disperse under ultrasonic conditions for 20 minutes, and stir evenly. The above-mentioned hydrophobized carbon paper was placed on a glass plate and fixed, and the above-mentioned slurry was scraped on the surface of the carbon paper and weighed until the carbon powder loading was 1 mgcm ^-2 , and the gas diffusion layer was obtained.

2) Preparation of ordered membrane electrodes:

a. Preparation of surface-modified ordered nanowire array structure

The gas diffusion layer obtained in the above step 1) is placed in a plastic fixture, and a conductive platinum sheet is inserted into the plastic fixture, and at the same time, good contact between the conductive platinum sheet and the gas diffusion layer is ensured. The above device was placed in a three-electrode electrodeposition system, and the electrolyte was 0.2M phosphate buffer containing 0.1M pyrrole, 0.1M sodium p-toluenesulfonate, and ultra-low molecular weight (MW<100,000) PDDA with a mass concentration of 1%. , a working voltage of 0.75V (vsSCE) was applied to the conductive platinum sheet for 60 minutes, that is, a layer of polypyrrole (PPy) doped with PDDA arranged in an orderly array was formed by electrodeposition on the surface of the gas diffusion layer, marked as PDDAPPy-GDL sample.

b. Self-assembly preparation of catalytic layer

An aqueous solution of chloroplatinic acid containing 7.4 mgmL ^-1 of Pt was drop-coated at 40 μL per square centimeter on the gas diffusion layer grown with ordered conductive polymer nanostructures obtained in the above step 2) a, and left to stand for 24 hours. The ascorbic acid aqueous solution with a concentration of 37mgmL ^-1 was also drop-coated at 40 μL per square centimeter on the surface of the above-mentioned electrode drop-coated with chloroplatinic acid, and left to stand for 4 hours. After the color of the surface liquid changes from bright yellow to a colorless transparent solution, the surface of the ordered membrane electrode loaded with the catalyst is repeatedly washed with deionized water, and the ordered membrane electrode is obtained after air-drying.

Example 5:

1) Preparation of gas diffusion layer:

Soak Toray carbon paper in 20% PTFE aqueous solution, take it out and air dry after fully soaking, and weigh it. Repeat the above steps until the PTFE loading is about 15% (the mass of carbon paper after hydrophobization treatment). Mix VulcanXC-72 carbon powder with 20% PTFE aqueous solution at a mass concentration of 10% relative to the mass of carbon powder and PTFE, and dilute with ethanol 20 times the mass of carbon powder, disperse under ultrasonic conditions for 20 minutes, and stir evenly. The above-mentioned hydrophobized carbon paper was placed on a glass plate and fixed, and the above-mentioned slurry was scraped on the surface of the carbon paper and weighed until the carbon powder loading was 1 mgcm ^-2 , and the gas diffusion layer was obtained.

2) Preparation of ordered membrane electrodes:

a. Preparation of surface-modified ordered nanowire array structure

The gas diffusion layer obtained in the above step 1) is placed in a plastic fixture, and a conductive platinum sheet is inserted into the plastic fixture, and at the same time, good contact between the conductive platinum sheet and the gas diffusion layer is ensured. The above device was placed in a three-electrode electrodeposition system, and the electrolyte was 0.2M phosphate buffer containing 0.1M pyrrole, 0.1M sodium p-toluenesulfonate, and ultra-low molecular weight (MW<100,000) PDDA with a mass concentration of 1%. , a working voltage of 0.6V (vsSCE) was applied to the conductive platinum sheet for 20 minutes, that is, a layer of polypyrrole (PPy) doped with PDDA arranged in an ordered array was electrodeposited on the surface of the gas diffusion layer, marked as PDDAPPy-GDL sample.

b. Self-assembly preparation of catalytic layer

An aqueous solution of chloroplatinic acid containing 7.4 mgmL ^-1 of Pt was drop-coated at 10 μL per square centimeter on the gas diffusion layer grown with ordered conductive polymer nanostructures obtained in the above step 2) a, and left to stand for 24 hours. The ascorbic acid aqueous solution with a concentration of 37mgmL ^-1 was also drop-coated at 10 μL per square centimeter on the surface of the above-mentioned electrode drop-coated with chloroplatinic acid, and left to stand for 4 hours. After the color of the surface liquid changes from bright yellow to a colorless transparent solution, the surface of the ordered membrane electrode loaded with the catalyst is repeatedly washed with deionized water, and the ordered membrane electrode is obtained after air-drying.

Embodiment 6:

1) Preparation of gas diffusion layer:

Soak the SGL carbon paper in 20% PTFE aqueous solution, take it out and air-dry it after fully soaking, and weigh it. Repeat the above steps until the PTFE loading is about 15% (the mass of carbon paper after hydrophobization treatment). Mix VulcanXC-72 carbon powder with 20% PTFE aqueous solution at a mass concentration of 10% relative to the mass of carbon powder and PTFE, and dilute with ethanol 20 times the mass of carbon powder, disperse under ultrasonic conditions for 20 minutes, and stir evenly. The above-mentioned hydrophobized carbon paper was placed on a glass plate and fixed, and the above-mentioned slurry was scraped on the surface of the carbon paper and weighed until the carbon powder loading was 1 mgcm ^-2 , and the gas diffusion layer was obtained.

2) Preparation of ordered membrane electrodes:

a. Preparation of surface-modified ordered nanowire array structure

The gas diffusion layer obtained in the above step 1) is placed in a plastic fixture, and a conductive platinum sheet is inserted into the plastic fixture, and at the same time, good contact between the conductive platinum sheet and the gas diffusion layer is ensured. The above device was placed in a three-electrode electrodeposition system, and the electrolyte was 0.2M phosphate buffer containing 0.1M pyrrole, 0.1M sodium p-toluenesulfonate, and ultra-low molecular weight (MW<100,000) PDDA with a mass concentration of 1%. , a working voltage of 0.65V (vsSCE) was applied to the conductive platinum sheet for 30 minutes, that is, a layer of polypyrrole (PPy) doped with PDDA arranged in an orderly array was formed by electrodeposition on the surface of the gas diffusion layer, marked as PDDAPPy-GDL sample.

b. Self-assembly preparation of catalytic layer

An aqueous solution of chloroplatinic acid containing 7.4 mgmL ^-1 of Pt was drop-coated at 20 μL per square centimeter on the gas diffusion layer grown with ordered conductive polymer nanostructures obtained in the above step 2) a, and left to stand for 24 hours. The ascorbic acid aqueous solution with a concentration of 37mgmL ^-1 was also drop-coated at 20 μL per square centimeter on the surface of the above-mentioned electrode drop-coated with chloroplatinic acid, and left to stand for 4 hours. After the color of the surface liquid changes from bright yellow to a colorless transparent solution, the surface of the ordered membrane electrode loaded with the catalyst is repeatedly washed with deionized water, and the ordered membrane electrode is obtained after air-drying.

Comparative example 1:

1) Preparation of gas diffusion layer:

Soak Toray carbon paper in 20% PTFE aqueous solution, take it out and air dry after fully soaking, and weigh it. Repeat the above steps until the PTFE loading is about 15% (the mass of carbon paper after hydrophobization treatment). Mix VulcanXC-72 carbon powder with 20% PTFE aqueous solution at a mass concentration of 10% relative to the mass of carbon powder and PTFE, and dilute with ethanol 20 times the mass of carbon powder, disperse under ultrasonic conditions for 20 minutes, and stir evenly. The above-mentioned hydrophobized carbon paper was placed on a glass plate and fixed, and the above-mentioned slurry was scraped on the surface of the carbon paper and weighed until the carbon powder loading was 1 mgcm ^-2 , and the gas diffusion layer was obtained.

2) Preparation of catalyst slurry:

Put 3 mg of commercial platinum-carbon catalyst (E-Tek) in a beaker, add 50 mg of deionized water, and ultrasonically disperse for 5 minutes. Add 7 mg of 5% Nafion solution (DuPont) and ultrasonically disperse for 5 minutes. Add 50 mg of absolute ethanol and ultrasonically disperse for 30 minutes to obtain a catalyst slurry.

3) Preparation of catalytic layer:

Fix the sample obtained in the above step 1) on a vacuum hot stage, heat it to 60°C, take it off and weigh it after 30 minutes, and fix it on the hot stage again; take the catalyst slurry obtained in the above step 2) and spray it evenly with a spray pen with nitrogen The surface of the sample obtained in step 1) was kept at 60°C for 30 minutes after spraying, and then weighed. The catalyst loading was about 0.5 mg·cm ^-2 . Obtain a traditional structure membrane electrode.

Comparative example 2:

1) Preparation of gas diffusion layer:

Soak Toray carbon paper in 20% PTFE aqueous solution, take it out and air dry after fully soaking, and weigh it. Repeat the above steps until the PTFE loading is about 15% (the mass of carbon paper after hydrophobization treatment). Mix VulcanXC-72 carbon powder with 20% PTFE aqueous solution at a mass concentration of 10% relative to the mass of carbon powder and PTFE, and dilute with ethanol 20 times the mass of carbon powder, disperse under ultrasonic conditions for 20 minutes, and stir evenly. The above-mentioned hydrophobized carbon paper was placed on a glass plate and fixed, and the above-mentioned slurry was scraped on the surface of the carbon paper and weighed until the carbon powder loading was 1 mgcm ^-2 , and the gas diffusion layer was obtained.

2) Preparation of catalyst slurry:

Put 3 mg of commercial platinum black catalyst (JM) in a beaker, add 50 mg of deionized water, and ultrasonically disperse for 5 minutes. Add 7 mg of 5% Nafion solution (DuPont) and ultrasonically disperse for 5 minutes. Add 50 mg of absolute ethanol and ultrasonically disperse for 30 minutes to obtain a catalyst slurry.

3) Preparation of catalytic layer:

Fix the sample obtained in the above step 1) on a vacuum hot stage, heat it to 60°C, take it off and weigh it after 30 minutes, and fix it on the hot stage again; take the catalyst slurry obtained in the above step 2) and spray it evenly with a spray pen with nitrogen The surface of the sample obtained in step 1) was kept at 60°C for 30 minutes after spraying, and then weighed. The catalyst loading was about 0.5 mg·cm ^-2 . Obtain a traditional structure membrane electrode.

Claims (8)

1. a preparation method of an ordered gas diffusion electrode, characterized in that: comprising the following preparation steps, a. Preparation of ordered nanowire array structure doped with PDDA polydienylpropylenedimethylammonium chloride The conductive polymer doped with PDDA is electrodeposited on the surface of one side of the gas diffusion layer or the surface of the microporous layer of the gas diffusion layer by electrodeposition, and the conductive polymer is polythiophene or polythiophene derivatives or polypyrrole or poly One of pyrrole derivatives or polyaniline or polyaniline derivatives to obtain a microscopically ordered PDDA-doped conductive polymer nanowire array structure in the direction perpendicular to the surface of the diffusion layer; b. Self-assembly preparation of the catalytic layer An aqueous solution of chloroplatinic acid with a Pt concentration of 1-10 mg·mL ^-1 is drop-coated at 10-100 μL per square centimeter on the surface of the nanowire array structure obtained in step a above, and left to stand at room temperature for 12-24 hours; the aqueous solution of ascorbic acid or An aqueous solution of sodium borohydride or an aqueous solution of dimethylammonium borane or one or more of hydrazine hydrate is drip-coated on the surface of the above-mentioned conductive polymer nanowire array to make ascorbic acid or sodium borohydride or dimethylammonium borane Or the amount of hydrazine hydrate is 2-10 times the amount of Pt, let stand for 2-10 hours, rinse with deionized water and dry at room temperature to obtain an ordered gas diffusion electrode; The ordered gas diffusion electrode prepared by the method comprises a gas diffusion layer and an ordered catalytic layer based on the gas diffusion layer, the ordered catalytic layer is attached to the surface of the gas diffusion layer, and microscopically has a structure perpendicular to the gas diffusion layer Orientation-ordered nanowire array structure in the surface direction. 2. the preparation method of ordered gas diffusion electrode as claimed in claim 1, is characterized in that: The electrodeposition method in the step a is specifically: immersing one side of the gas diffusion layer in an electrolytic solution containing one of thiophene or pyrrole or aniline or thiophene derivatives or pyrrole derivatives or aniline derivative solutions, and simultaneously containing a supporting electrolyte and PDDA. In the solution, the gas diffusion layer was used as the working electrode, the Pt sheet was used as the counter electrode, and the saturated calomel electrode was used as the reference electrode, and a three-electrode system was used for electrodeposition. 3. the preparation method of ordered gas diffusion electrode as claimed in claim 1, is characterized in that: In step a, when the molecular weight of the PDDA is less than 100,000, the mass concentration of the PDDA aqueous solution is 20-30%; %, and less than or equal to 50%; In step b, the concentration of the chloroplatinic acid aqueous solution is 1-10 mg·ml ^-1 . 4. the preparation method of ordered gas diffusion electrode as claimed in claim 1 or 2, is characterized in that: The concentration of thiophene or pyrrole or aniline or thiophene derivatives or pyrrole derivatives or aniline derivatives in the electrolyte solution in the electrodeposition process is 0.01-0.5M; The supporting electrolyte added in the electrolyte solution in the electrodeposition process is sodium p-toluenesulfonate, sodium dodecylsulfonate, β-naphthalenesulfonic acid, bistrimethylsilyl trifluoroacetamide, perchlorate, sulfuric acid One or more of salt and chloride; the concentration of the supporting electrolyte in the electrolyte solution during the electrodeposition process is 0.01-0.5M; The electrodeposition potential of the electrodeposition is 0.65-0.75V relative to the saturated calomel electrode; The electrodeposition time length of the electrodeposition is 0.25-1h. 5. the preparation method of ordered gas diffusion electrode as claimed in claim 2, is characterized in that: The mass concentration of PDDA in the electrolyte is 0.05-5%. 6. the preparation method of ordered gas diffusion electrode as claimed in claim 1, is characterized in that: The ordered catalytic layer includes polythiophene or polythiophene derivatives or polypyrrole or polypyrrole derivatives or polyaniline or polyaniline derivatives in a microcosmic array of conductive polymer nanowires, and attached to PDDA on conductive polymer nanowires, and Pt nanoparticles attached to PDDA; The loading amount of conductive polymer nanowires in the ordered catalytic layer is 0.5mg·cm ^-2 , the loading amount of PDDA is 5μg·cm ^-2 , and the loading amount of Pt nanoparticles is 0.01-0.5mg·cm ^{- 2} . 7. the preparation method of ordered gas diffusion electrode as claimed in claim 1, is characterized in that: The gas diffusion layer is composed of a support layer and a microporous layer attached to one side of the support layer; The support layer is carbon paper or carbon cloth; the microporous layer is VulcanXC-72 carbon powder, acetylene black carbon powder, carbon nanotubes or graphene mixed with PTFE or Nafion and then applied to the support layer by scraping, brushing or spraying Made on the surface. 8. the preparation method of ordered gas diffusion electrode as claimed in claim 1, is characterized in that: The ordered gas diffusion electrode prepared by the method is used in a proton exchange membrane fuel cell, or a direct liquid fuel cell, or a proton exchange membrane type water electrolysis cell.