JP2008177046A - Electrode for solid polymer fuel cell, its manufacturing method, and solid polymer fuel cell equipped with it - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method of an electrode for a solid polymer fuel cell capable of reducing carrying amount of a metal catalyst and capable of suppressing voltage drop in a large current region. <P>SOLUTION: This is the manufacturing method of an electrode for solid polymer fuel cell equipped with a conductive porous substrate, carbon fiber arranged on the conductive porous substrate, and a metal catalyst carried on the carbon fiber, and comprises (i) a process to apply a water repellency treatment on one of the surfaces of the conductive porous substrate, (ii) a process to produce a fibril-like polymer by electrolytic oxidation polymerization of a compound having an aromatic ring on the other surface of the conductive porous substrate, (iii) a process to produce carbon fiber on the conductive porous substrate by calcining the fibril-like polymer, and (iv) a process to have the metal catalyst carried on the carbon fiber. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an electrode for a polymer electrolyte fuel cell, a method for producing the same, and a polymer electrolyte fuel cell provided with the electrode for a polymer electrolyte fuel cell, and in particular, the amount of metal catalyst supported can be reduced. Thus, the present invention relates to a method for producing an electrode for a polymer electrolyte fuel cell, in which a voltage drop in a high current region is small, gas permeability is good, and flooding in a high humidity environment hardly occurs.

  In recent years, fuel cells have attracted attention as a battery with high power generation efficiency and a low environmental load, and extensive research and development has been conducted. Among fuel cells, polymer electrolyte fuel cells with high output density and low operating temperature are easier to reduce in size and cost than other types of fuel cells. It is expected to spread widely as a household cogeneration system.

  In general, in a polymer electrolyte fuel cell, a pair of electrodes are arranged with a polymer electrolyte membrane sandwiched between them, a fuel gas such as hydrogen is brought into contact with the surface of one electrode, and oxygen is applied to the surface of the other electrode. The oxygen-containing gas contained is brought into contact, and electric energy is taken out between the electrodes by using an electrochemical reaction that occurs at this time (see Non-Patent Documents 1 and 2). A catalyst layer is disposed on the electrode in contact with the polymer electrolyte membrane, and an electrochemical reaction occurs at the three-phase interface between the polymer electrolyte membrane, the catalyst layer, and the gas. Therefore, in order to improve the power generation efficiency of the polymer electrolyte fuel cell, it is necessary to increase the reaction field of the electrochemical reaction.

  In order to form a catalyst layer capable of increasing the reaction field of the electrochemical reaction, generally, a paste or slurry containing catalyst powder in which a noble metal catalyst such as platinum is supported on granular carbon such as carbon black, The method of apply | coating on electroconductive porous supports, such as carbon paper, is taken. However, the polymer electrolyte fuel cell including the catalyst layer formed by this method has low power generation efficiency.

  On the other hand, the present inventors prepared a carbon fiber by a specific method on a conductive porous support such as carbon paper, and an electrode prepared by supporting a noble metal on the carbon fiber by electroplating. Has been found to improve the power generation efficiency of the polymer electrolyte fuel cell (see Patent Document 1).

The Chemical Society of Japan, “Chemical Review No. 49, Material Chemistry of New Batteries”, Academic Publishing Center, 2001, p. 180-182 “Polymer fuel cell <2001 edition>”, Technical Information Association, 2001, p. 14-15 International Publication No. 2004/063438 Pamphlet

  However, as a result of further investigations by the present inventors, even with the electrode described in Patent Document 1, there is still room for improvement in terms of voltage drop in a high current region, and from the viewpoint of cost. From this, it was found that it was necessary to further reduce the supported amount of the metal catalyst.

  Accordingly, an object of the present invention is to solve the above-described problems of the prior art, to reduce the amount of the metal catalyst supported, and to suppress a voltage drop in a high current region. It is in providing the electrode for manufacturing and its manufacturing method. Another object of the present invention is to provide a solid polymer fuel cell comprising such a polymer electrolyte fuel cell electrode and having a small voltage drop in a high current region.

  As a result of intensive studies to achieve the above object, the present inventors performed water repellent treatment on one surface of the conductive porous substrate, and fibrillated polymer on the other surface of the conductive porous substrate. It is possible to suppress the voltage drop in a high current region by selectively producing the fibrillated polymer and calcining the fibrillated polymer to form a three-dimensional continuous carbon fiber and supporting the metal catalyst on the carbon fiber. An electrode for a polymer electrolyte fuel cell can be obtained, and it has been found that sufficient performance can be obtained even if the amount of the supported metal catalyst is reduced as compared with the prior art, and the present invention has been completed.

That is, the method for producing an electrode for a polymer electrolyte fuel cell of the present invention comprises a conductive porous substrate, a carbon fiber disposed on the conductive porous substrate, and a metal supported on the carbon fiber. A method for producing a polymer electrolyte fuel cell electrode comprising a catalyst,
(i) performing a water repellent treatment on one surface of the conductive porous substrate;
(ii) on the other surface of the conductive porous substrate, electrolytic oxidation polymerization of a compound having an aromatic ring to produce a fibril polymer;
(iii) firing the fibrillated polymer to form carbon fibers on the conductive porous substrate;
(iv) supporting a metal catalyst on the carbon fiber.

  In a preferred example of the method for producing an electrode for a polymer electrolyte fuel cell of the present invention, the conductive porous substrate is carbon paper.

  In another preferred embodiment of the method for producing a polymer electrolyte fuel cell electrode of the present invention, the water repellent treatment is performed with a fluorine-based water repellent.

  In another preferred embodiment of the method for producing a polymer electrolyte fuel cell electrode of the present invention, the compound having an aromatic ring is at least one selected from the group consisting of aniline, pyrrole, thiophene and derivatives thereof. .

  In another preferred embodiment of the method for producing an electrode for a polymer electrolyte fuel cell of the present invention, the firing is performed in a non-oxidizing atmosphere.

  In another preferred embodiment of the method for producing an electrode for a polymer electrolyte fuel cell of the present invention, the metal catalyst contains at least Pt.

  In addition, the polymer electrolyte fuel cell electrode of the present invention is manufactured by the above-described method, and the polymer electrolyte fuel cell of the present invention includes the electrode.

  According to the present invention, it is possible to provide an electrode for a polymer electrolyte fuel cell that can reduce the amount of the metal catalyst supported and can suppress a voltage drop in a high current region, and a method for manufacturing the same. Can do. In addition, it is possible to provide a polymer electrolyte fuel cell including such an electrode and having a small voltage drop in a high current region.

<Electrode for polymer electrolyte fuel cell and method for producing the same>
Below, the electrode for solid polymer type fuel cells of the present invention and its manufacturing method are explained in detail. The method for producing a polymer electrolyte fuel cell electrode of the present invention comprises (i) a step of subjecting one surface of the conductive porous substrate to a water repellent treatment, and (ii) the other side of the conductive porous substrate. On the surface, electrolytic oxidation polymerization of a compound having an aromatic ring to produce a fibril polymer; (iii) firing the fibril polymer to produce carbon fibers on the conductive porous substrate; (iv) a step of supporting a metal catalyst on the carbon fiber, and according to the method, the conductive porous substrate, and the carbon fiber disposed on the conductive porous substrate; A polymer electrolyte fuel cell electrode comprising a metal catalyst supported on the carbon fiber can be produced.

  In the method for producing an electrode for a polymer electrolyte fuel cell of the present invention, the water repellent treatment is performed in the step (ii) by performing the water repellent treatment on one surface of the conductive porous substrate in the step (i). It is possible to prevent the formation of a fibril-like polymer on the finished surface. Therefore, in step (ii), a fibrillated polymer is formed only on the surface of the conductive porous substrate that has not been subjected to the water-repellent treatment, and by firing in step (iii), only one side of the conductive porous substrate is produced. The carbon fiber can be selectively produced. In this case, in the step (iv), the metal catalyst is supported on the carbon fiber selectively generated only on one surface of the conductive porous substrate, and therefore the metal catalyst is supported only on the target surface. As a result, the supported amount of the metal catalyst can be reduced. In addition, the water-repellent surface of the conductive porous substrate does not contain carbon fiber or metal catalyst, so it has high gas permeability and is difficult to flood even in a high humidity environment. Even when the battery is operated in a high current region, the voltage drop is small.

  In the method for producing an electrode for a polymer electrolyte fuel cell of the present invention, the water repellent treatment is performed on one surface of the conductive porous substrate in the step (i). Here, the conductive porous substrate to be used may be any porous and conductive material, and specifically includes carbon paper, porous carbon cloth, etc. Among these, carbon Paper is preferred.

  Further, the water repellent treatment is preferably carried out with a fluorine-based water repellent mainly composed of a fluorine-based copolymer such as polytetrafluoroethylene or tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer. By subjecting one surface of the conductive porous substrate to surface treatment with this water repellent, it is possible to reliably prevent the formation of a fibril polymer on the surface in the step (ii). The water repellent treatment is carried out, for example, by dissolving a water repellent in a suitable solvent and applying it to one surface of the conductive porous substrate, and the concentration of the water repellent component in the water repellent solution. Etc. can be appropriately adjusted. Further, after the application of the water repellent solution, it is preferable to perform a heat treatment to remove the solvent and fix the water repellent.

  In the method for producing a polymer electrolyte fuel cell electrode of the present invention, in step (ii), the other surface of the conductive porous substrate, that is, the surface of the conductive porous substrate that has not been subjected to water repellent treatment. In the above, a compound having an aromatic ring is subjected to electrolytic oxidation polymerization to produce a fibrillated polymer. Here, the surface of the conductive porous substrate that has been subjected to the water-repellent treatment has a low affinity with the electrolytic solution, so that the surface of the conductive porous substrate that has not been subjected to the water-repellent treatment is selectively fibrillated. A polymer can be produced.

  Examples of the compound having an aromatic ring include a compound having a benzene ring and a compound having an aromatic heterocyclic ring. Here, as the compound having a benzene ring, aniline and aniline derivatives are preferable, and as the compound having an aromatic heterocyclic ring, pyrrole, thiophene and derivatives thereof are preferable. These compounds having an aromatic ring may be used singly or as a mixture of two or more.

In the electrolytic oxidation polymerization, it is preferable to mix an acid together with a raw material compound having an aromatic ring. In this case, the negative ion of the acid is taken into the fibril polymer synthesized as a dopant to obtain a fibril polymer excellent in conductivity. By using this fibril polymer, the conductivity of the carbon fiber is finally improved. Further improvement can be achieved. Here, examples of the acid mixed in the electrolytic oxidation polymerization include HBF ₄ , H ₂ SO ₄ , HCl, HClO _{4 and the} like. The acid concentration is preferably in the range of 0.1 to 3 mol / L, more preferably in the range of 0.5 to 2.5 mol / L.

In the step (ii), in the solution containing the compound having an aromatic ring, the conductive porous substrate in which only one of the surfaces is water-repellent is immersed as a working electrode, and the counter electrode is further immersed between the electrodes. A voltage higher than the oxidation potential of the compound having an aromatic ring may be applied, or a current having a condition sufficient to ensure a sufficient voltage to polymerize the compound having the aromatic ring may be passed, thereby making the conductive porous A fibrillated polymer is formed on the surface of the porous substrate (working electrode) that has not been subjected to the water repellent treatment. Here, as the counter electrode, a plate made of a highly conductive material such as stainless steel, platinum, or carbon, a porous support, or the like can be used. An example of a method for synthesizing a fibril-like polymer by this electrolytic oxidation polymerization method is as follows. A working electrode composed of a conductive porous substrate in an electrolytic solution containing a compound having an acid and an aromatic ring, such as H ₂ SO ₄ and HBF ₄ , and A method of polymerizing and depositing a fibrillated polymer on the working electrode side made of a conductive porous substrate by immersing the counter electrode and passing a current of 0.1 to 1000 mA / cm ² , preferably 0.2 to 100 mA / cm ² between both electrodes Is exemplified. Here, the concentration of the compound having an aromatic ring in the electrolytic solution is preferably 0.05 to 3 mol / L, and more preferably 0.25 to 1.5 mol / L. Moreover, in addition to the said component, you may add a soluble salt etc. to an electrolyte solution suitably in order to adjust pH.

  The fibril-like polymer obtained by electrolytic oxidation polymerization of the compound having an aromatic ring usually has a three-dimensional continuous structure, has a diameter of 30 to several hundred nm, preferably 40 to 500 nm, and has a length of 0.5. It is μm to 100 mm, preferably 1 μm to 10 mm.

  In the method for producing an electrode for a polymer electrolyte fuel cell of the present invention, in the step (iii), the fibrillated polymer is baked and carbonized to generate carbon fibers on the conductive porous substrate. In addition, before the step (iii), it is preferable that the fibrillated polymer is washed with a solvent such as water or an organic solvent and dried. Here, the drying method is not particularly limited, and examples thereof include a method using a fluidized bed drying device, an air dryer, a spray dryer, etc., in addition to air drying and vacuum drying.

  The firing conditions in the step (iii) are not particularly limited, and may be set as appropriate so as to obtain optimum conductivity. Particularly, when high conductivity is required, the temperature is 500 to 3000 ° C., Preferably, baking is performed at 600 to 2800 ° C. for 0.5 to 6 hours. In the production method of the present invention, the firing step is preferably performed in a non-oxidizing atmosphere, and examples of the non-oxidizing atmosphere include a nitrogen atmosphere, an argon atmosphere, and a helium atmosphere. It can also be.

The carbon fiber usually has a three-dimensional continuous structure, has a diameter of 30 to several hundred nm, preferably 40 to 500 nm, has a length of 0.5 μm to 100 mm, preferably 1 μm to 10 mm, and has a surface resistance. 10 ⁶ to 10 ⁻² Ω, preferably 10 ⁴ to 10 ⁻² Ω. The carbon fiber has a residual carbon ratio of 90 to 20%, preferably 80 to 25%. Since the carbon fiber has a structure in which the entire carbon is three-dimensionally continuous, the carbon fiber has higher conductivity than the granular carbon.

  In the method for producing an electrode for a polymer electrolyte fuel cell of the present invention, a metal catalyst is supported on the carbon fiber in the step (iv). Here, as the metal catalyst supported on the carbon fiber, a noble metal is preferable, and Pt is particularly preferable. In the present invention, Pt may be used alone or as an alloy with another metal such as Ru. By using Pt as the noble metal, hydrogen can be oxidized with high efficiency even at a low temperature of 100 ° C. or lower. In addition, by using an alloy such as Pt and Ru, it is possible to prevent poisoning of Pt by CO and prevent a decrease in the activity of the catalyst. The particle size of the metal catalyst supported on the carbon fiber is preferably in the range of 0.5 to 20 nm, and the support rate of the metal catalyst is preferably in the range of 0.05 to 5 g with respect to 1 g of the carbon fiber. Here, the method for supporting the metal catalyst on the carbon fiber is not particularly limited, and examples thereof include an impregnation method, an electroplating method (electrolytic reduction method), an electroless plating method, and a sputtering method. .

In the method of the present invention, it is preferable to carry the metal catalyst on the carbon fiber by an electroplating method in which a current is applied in a pulsed manner. Here, the current application condition is the following formula (I):
Duty ratio = t ₁ / (t ₁ + t ₂ ) × 100 (I)
It is preferable that the duty ratio represented by [where t ₁ represents current application time (seconds) and t ₂ represents rest time (seconds)] be 2 to 20%. If the duty ratio in the pulse current is less than 2%, it takes a long time to satisfy the predetermined energized charge amount, which is not suitable for practical use, and the effect of improving the surface area of the metal catalyst is insufficient, while the duty ratio is 20 If it exceeds%, the effect of applying current in a pulsed manner is small, and the surface area of the supported metal catalyst cannot be sufficiently improved.

Dwell time in the electroplating (t ₂₎ is preferably set to 0.05 to 0.5 seconds. When the pause time (t ₂ ) is less than 0.05 seconds, the effect of applying the current in a pulsed manner is small, and the surface area of the supported metal catalyst cannot be sufficiently improved, while the pause time (t ₂ ) is 0.5. If it exceeds 2 seconds, it takes a total time to satisfy the predetermined energized charge amount, which is not suitable for practical use, and the effect of improving the surface area of the metal catalyst is insufficient.

In the electroplating, the current density is preferably in the range of 10 to 500 mA / cm ² , and the energization charge amount is preferably in the range of 0.1 to 5C. The application time (t ₁ ) is preferably selected so that the rest time (t ₂ ) is in the range of 0.05 to 0.5 seconds while the duty ratio is 2 to 20%. Furthermore, the number of pulses (number of cycles) in pulse plating is preferably selected as appropriate so as to be in the above-described range of the preferred energized charge amount.

  The electrode for a polymer electrolyte fuel cell of the present invention produced by the above-described method comprises a conductive porous substrate, carbon fibers disposed on the conductive porous substrate, and supported on the carbon fibers. It can be used as a fuel electrode or an air electrode (oxygen electrode). Here, in the polymer electrolyte fuel cell electrode, the carbon fiber and the metal catalyst function as a catalyst layer, and the conductive porous substrate is a fuel such as hydrogen gas to the catalyst layer composed of the carbon fiber and the metal catalyst. Alternatively, it functions as a gas diffusion layer that supplies an oxygen-containing gas such as oxygen or air, and as a current collector that exchanges generated electrons.

The catalyst layer composed of the carbon fiber and the metal may be impregnated with a polymer electrolyte. As the polymer electrolyte, an ion conductive polymer can be used, and as the ion conductive polymer, Examples thereof include polymers having an ion exchange group such as sulfonic acid, carboxylic acid, phosphonic acid, and phosphonous acid, and the polymer may or may not contain fluorine. Examples of the ion conductive polymer include perfluorocarbon sulfonic acid polymers such as Nafion (registered trademark). The amount of impregnation of the polymer electrolyte is preferably in the range of 10 to 500 parts by mass of the polymer electrolyte with respect to 100 parts by mass of the catalyst layer. The thickness of the catalyst layer is not particularly limited, but is preferably in the range of 0.1 to 100 μm. The amount of the metal catalyst supported on the catalyst layer is determined by the loading rate and the thickness of the catalyst layer, and is preferably in the range of 0.001 to 0.8 mg / cm ² .

<Solid polymer fuel cell>
Next, a polymer electrolyte fuel cell using the polymer electrolyte fuel cell electrode of the present invention will be described with reference to FIG. The illustrated polymer electrolyte fuel cell includes a membrane electrode assembly (MEA) 1 and separators 2 located on both sides thereof. The membrane electrode assembly (MEA) 1 includes a solid polymer electrolyte membrane 3 and fuel electrodes 4A and air electrodes 4B located on both sides thereof. In the fuel electrode 4A, a reaction represented by 2H ₂ → 4H ⁺ + 4e ⁻ occurs, the generated H ⁺ passes through the solid polymer electrolyte membrane 3 to the air electrode 4B, and the generated e ⁻ is taken out to the outside. Current. On the other hand, in the air electrode 4B, a reaction represented by O ₂ + 4H ⁺ + 4e ⁻ → 2H ₂ O occurs, and water is generated. The fuel electrode 4A and the air electrode 4B are composed of a catalyst layer (metal catalyst-supporting carbon fiber) 5 and a gas diffusion layer (conductive porous substrate) 6, and are arranged so that the catalyst layer 5 is in contact with the solid polymer electrolyte membrane 3. Has been.

  In the polymer electrolyte fuel cell of the present invention, an ion conductive polymer can be used as the solid polymer electrolyte membrane 3, and the catalyst layer can be impregnated as the ion conductive polymer. What was illustrated as a suitable polymer electrolyte can be used. Moreover, as the separator 2, the normal separator with which flow paths (not shown), such as fuel, air, and produced | generated water, were formed in the surface can be used.

  In the polymer electrolyte fuel cell of the present invention, the catalyst layer 5 is formed by supporting a metal catalyst on carbon fiber, and the surface area of the supported metal is very large. Therefore, the solid polymer electrolyte membrane 3 and the catalyst layer 5 The reaction field of the electrochemical reaction at the three-phase interface with the gas is very large. As a result, the power generation efficiency of the polymer electrolyte fuel cell is greatly improved. Further, since the gas diffusion layer 6 is not provided with carbon fibers or the like on the surface not in contact with the catalyst layer 5, the gas diffusion layer 6 has very high gas permeability. Therefore, in the polymer electrolyte fuel cell of the present invention, flooding hardly occurs even in a high humidity environment, and even when operated in a high current region, the voltage drop is small.

  Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not limited to the following examples.

(Example 1)
<Production of carbon fiber>
In an acidic aqueous solution containing aniline 0.5 mol / L and borohydrofluoric acid 1.0 mol / L, carbon paper [manufactured by Toray] was installed as a working electrode, and punching metal made of SUS316L was installed as a counter electrode at 15 ° C. Electrolytic oxidation polymerization was carried out at a constant current of 5 mA / cm ² for 700 seconds, and polyaniline was electrodeposited on the working electrode. Here, the used carbon paper was previously sprayed with a fluorine-based treatment agent [Die Free GA-6010, manufactured by Daikin Industries] on one side and subjected to heat treatment at 170 ° C. for 5 minutes. Next, the obtained polyaniline was immersed in a 1.0 mol / L NaOH aqueous solution for 1 hour, washed sufficiently with pure water, and dried under reduced pressure at 100 ° C. Further, the obtained polyaniline was heated together with carbon paper to 1200 ° C. in an Ar reduced pressure atmosphere over 2 hours, and held at that temperature for 1 hour for firing treatment. Then, it cooled to room temperature and took out the obtained baked material (carbon fiber).

<Platinum support>
Next, the fired product (carbon fiber) obtained above was placed as a working electrode in an aqueous solution obtained by dissolving 10 g of chloroplatinic acid hexahydrate together with carbon paper in 1 L of pure water, and further, white as a counter electrode. A gold-plated titanium plate was installed. Thereafter, a pulse current of 120 mA / cm ² was passed at room temperature, and platinum was supported on the carbon fiber. The pulse conditions were as follows: application time (on time): 0.005 seconds, rest time (off time): 0.1 seconds, and energization amount: 1.0 C / cm ² . Moreover, after energization was completed, it was sufficiently washed and dried. The platinum loading was calculated from the mass change and found to be 0.33 mg / cm ² .

<Production of MEA>
Next, the carbon paper with platinum-supported carbon fibers obtained as described above is punched out to a size of 50 mm square, and Nafion (registered trademark) solution is applied to the side where the platinum-supported carbon fibers are disposed, and then at 100 ° C. The solvent was removed by drying. The amount of Nafion was adjusted to 0.4 mg / cm ² . The two Nafion-coated platinum-supported carbon fibers / carbon paper sandwiched the Nafion 112 membrane and integrated by hot pressing to obtain a membrane electrode assembly (MEA).

<Performance evaluation of fuel cell>
The obtained membrane electrode assembly was incorporated into a test cell (EFC25-01SP) manufactured by Electrochemical Co., and a fuel cell was produced. The power generation characteristics of the obtained fuel cell were determined with a fuel gas (hydrogen) flow rate of 0.3 L / min, Measurement was performed under the conditions of a fuel gas humidification temperature of 80 ° C., an oxidizing gas (oxygen) flow rate of 0.3 L / min, an oxidizing gas humidification temperature of 75 ° C., and a cell temperature of 80 ° C. Table 1 shows the voltage at each current.

(Example 2)
A carbon fiber was produced in the same manner as in Example 1. Further, platinum was supported in the same manner as in Example 1 except that the energization amount was 0.8 C / cm ² . The platinum loading determined from the mass change was 0.27 mg / cm ² . Further, an MEA was produced in the same manner as in Example 1, a fuel cell was assembled, and power generation performance was evaluated. Table 2 shows the voltage at each current.

(Comparative Example 1)
Carbon fibers were produced in the same manner as in Example 1 except that carbon paper that had not been subjected to water repellent treatment with a fluorine-based treating agent was used. Further, platinum was supported in the same manner as in Example 1. The platinum loading determined from the mass change was 0.27 mg / cm ² . Further, an MEA was produced in the same manner as in Example 1, a fuel cell was assembled, and power generation performance was evaluated. Table 3 shows the voltage at each current.

  From Tables 1, 2 and 3, it can be seen that the fuel cell including the electrodes of Examples 1 and 2 according to the present invention has a small voltage drop in the high current region. On the other hand, the fuel cell equipped with the electrode of Comparative Example 1 produced using carbon paper that was not subjected to water repellent treatment had a large voltage drop in the high current region.

It is sectional drawing of an example of the polymer electrolyte fuel cell of this invention.

Explanation of symbols

1 Membrane electrode assembly (MEA)
2 Separator 3 Solid polymer electrolyte membrane 4A Fuel electrode 4B Air electrode 5 Catalyst layer (carbon catalyst-supporting carbon fiber)
6 Gas diffusion layer (conductive porous substrate)

Claims (8)

A method for producing an electrode for a polymer electrolyte fuel cell, comprising: a conductive porous substrate; a carbon fiber disposed on the conductive porous substrate; and a metal catalyst supported on the carbon fiber. And
(i) performing a water repellent treatment on one surface of the conductive porous substrate;
(ii) on the other surface of the conductive porous substrate, electrolytic oxidation polymerization of a compound having an aromatic ring to produce a fibril polymer;
(iii) firing the fibrillated polymer to form carbon fibers on the conductive porous substrate;
(iv) A method for producing an electrode for a polymer electrolyte fuel cell, comprising a step of supporting a metal catalyst on the carbon fiber.   The method for producing an electrode for a polymer electrolyte fuel cell according to claim 1, wherein the conductive porous substrate is carbon paper.   The method for producing an electrode for a polymer electrolyte fuel cell according to claim 1, wherein the water repellent treatment is performed with a fluorine-based water repellent.   2. The method for producing an electrode for a polymer electrolyte fuel cell according to claim 1, wherein the compound having an aromatic ring is at least one selected from the group consisting of aniline, pyrrole, thiophene and derivatives thereof. .   The method for producing an electrode for a polymer electrolyte fuel cell according to claim 1, wherein the firing is performed in a non-oxidizing atmosphere.   The method for producing a polymer electrolyte fuel cell electrode according to claim 1, wherein the metal catalyst contains at least Pt.   An electrode for a polymer electrolyte fuel cell produced by the method according to claim 1.   A polymer electrolyte fuel cell comprising the electrode for a polymer electrolyte fuel cell according to claim 7.

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