JP2004335459A - Metal carrying porous carbon film, electrode for fuel cell, and fuel cell using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a metal carrying porous carbon film made to uniformly carry metal fine particles of controlled particle sizes, having a carrier structure capable of effectively utilizing a metallic catalyst, manufactured by a simple manufacturing process, and to provide an electrode for a fuel cell, and the fuel cell using the same. <P>SOLUTION: In the metal carrying porous carbon film, metal particles having average particle diameters of 0.7-20 nm, especially 1-10 nm, are dispersed and carried on a surface wall having fine pores. The electrode for a fuel cell using the metal carrying porous carbon film and an membrane-electrode junction made by jointing the electrode for a fuel cell on both sides of a polymer electrolyte membrane are obtained. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a metal-supported porous carbon membrane, an electrode for a fuel cell, and a fuel cell using the same.

2. Description of the Related Art In recent years, development and commercialization of fuel cells have been progressing. For example, in the case of a solid polymer electrolyte fuel cell, a gas in which a porous carbon film made of a carbon fiber paper having a thickness of 0.1 to 0.3 mm is provided, and a platinum-based catalyst as an electrode catalyst is supported on the surface thereof. A diffusion electrode is joined to both sides of the solid polymer electrolyte layer, and a separator made of a dense carbon plate having a thickness of 1 to 3 mm with a gas channel groove is provided outside of the porous carbon film on both sides to form a battery cell. Is composed.
Further, in the case of a phosphoric acid type fuel cell, a gas diffusion electrode in which a porous carbon film made of a carbon fiber paper having a thickness of 0.1 to 0.3 mm is provided, and a platinum-based catalyst as an electrode catalyst is supported on the surface thereof. Is bonded to both sides of an electrolyte layer in which phosphoric acid is held by a phosphoric acid holder, and a separator having a gas flow channel groove with a thickness of 1 to 3 mm is provided outside the porous carbon film on both sides. Is composed.

Conventionally, as a carbon material of a noble metal catalyst carrier, a powdery material represented by carbon black has been used in order to increase the specific surface area of the carrier. However, when applied to a fuel cell electrode, it must be formed into a film using a resin binder having substantially no electron conductivity.
As a result, there arises a problem that the internal resistance of the electrode is increased, the in-plane reaction is non-uniform, and the battery characteristics are deteriorated.

Therefore, we have proposed a porous carbon film capable of maintaining a film shape without the intervention of a resin binder and its application to an electrode for a fuel cell (Patent Documents 2 and 3).
However, it is difficult to apply the stirring operation, which is an important step in the conventional metal dispersion and support technology using a metal precursor solution, to the porous carbon film, and it is very difficult to uniformly support nano-sized metal fine particles. Was difficult.

  In addition, metals generally used for fuel cell electrodes, particularly platinum-based materials, are very expensive and uniformly disperse and carry fine particles (preferably fine particles of 2 to 10 nm) so as to exhibit the maximum activity per weight. It is desired to do.

JP-A-5-36418 JP-A-12-335909 Japanese Patent Application No. 2002-127076

However, a technique for achieving uniform dispersion while controlling the particle size has not yet been established, and the fact is that metals such as platinum are supported based on experience and intuition.
It is an object of the present invention to uniformly support metal fine particles having a controlled particle diameter, to have a support structure capable of effectively utilizing a metal-based catalyst, and to simplify the manufacturing process. An object of the present invention is to obtain a fuel cell electrode and a fuel cell using the same.

The present invention relates to a metal-supported porous carbon membrane in which metal fine particles having an average particle diameter of 0.7 to 20 nm, particularly 1 to 10 nm are dispersed and supported on pore surface walls.
The present invention also relates to a fuel cell electrode using the metal-supported porous carbon film.
The present invention also relates to a membrane-electrode assembly in which the above-mentioned fuel cell electrode is joined to both sides of a polymer electrolyte membrane.
Further, the present invention relates to a fuel cell including the fuel cell electrode as a constituent element.

ADVANTAGE OF THE INVENTION According to this invention, the metal fine particle having a controlled particle diameter is uniformly supported, and a metal-supported porous carbon film having a support structure capable of effectively utilizing a metal-based catalyst and having a simple manufacturing process is obtained. be able to.
Further, according to the present invention, an electrode for a fuel cell and a membrane-electrode assembly can be obtained by a simple manufacturing process having a support structure capable of effectively using a noble metal catalyst.
Further, according to the present invention, a fuel cell with stable operation can be obtained.

Preferred embodiments of the present invention are listed below.
1) The above metal-supporting porous carbon film, wherein the metal fine particles contain a platinum element.
2) The above metal-supported porous material, wherein the fine metal particles are finely dispersed by performing a chemical reduction reaction of a metal compound with a reducing agent via a catalyst on the fine pore surface of the porous carbon film. Carbon membrane.
3) The above metal-supported porous carbon film, wherein the catalyst is a palladium compound supported on the carbon film.
4) The above metal-supporting porous carbon film, wherein the number of metal fine particles is 15% or more and 95% or less and which are multiple twin particles.
5) The above metal-supported porous carbon film, wherein the multiple twin particles are mainly composed of platinum element.

  The metal-supported porous carbon film of the present invention preferably undergoes a chemical reduction reaction with a reducing agent via a chemical reduction catalyst on a metal compound on the pore surface of the porous carbon film by chemical plating (electroless plating). By performing the selective treatment, the fine metal particles are uniformly finely dispersed, and the fine metal particles having an average particle diameter of 0.7 to 20 nm, particularly 1 to 10 nm can be obtained by being dispersed and supported on the surface wall.

According to the above-mentioned production method, metal fine particles can be easily supported only by a very gentle stirring operation.
According to the above-described manufacturing method, metal ions are selectively reduced and precipitated at the surface of the pores of the porous carbonized film. At the same time, the growth of the metal fine particles takes the form of epitaxial growth, and the generated metal fine particles are extremely crystalline. And the particles are physicochemically stable, so that fine metal fine particles can be uniformly and finely dispersed and supported on the surface of the pore surface.

Further, according to the above-mentioned production method, the deposition of metal fine particles occurs simultaneously over the entire surface without any time lag depending on the location, the particle diameter of the metal fine particles in the carrier is monodispersed, and the particle size becomes nanoscale. Is controlled arbitrarily.
In particular, the multi-twin particles generated in the above-mentioned epitaxial growth process have a high surface activity, and the surface of the particles is composed of high-density crystal planes.Also, since the particles have a stable shape, the initial structure is maintained over a long period of time. It is considered that the overall characteristics of the battery can be improved.

  As the metal, one selected from the group consisting of palladium, platinum, rhodium, ruthenium and iridium, and alloys of these substances, any combination thereof or any combination with another transition metal, preferably platinum And noble metals that are alloys thereof.

In the present invention, a porous carbon film, a porous graphite film, preferably a porous graphite film is used as the metal-based catalyst support.
The porous carbon film has a porous structure having fine communication holes, preferably has an average pore diameter of 0.05 to 10 μm, a porosity of 25 to 85%, and particularly has a thickness of 3 to 100 μm. is there.

The porous carbon film has a porous structure having fine communication holes, and is made of a carbon film structure having a smooth surface other than the open holes. The porous carbon film having the fine communication pores is a so-called open pore in which pores communicate with other surfaces in a passage form from any surface, and the adjacent pores have a wall-like structure. The film has a structure in which the pores extend in a non-linear manner while bending, and the film other than the open holes has a smooth surface, that is, carbon has a three-dimensional network structure without a binder. Refers to the film possessed.
In particular, the porous carbon film has an average pore diameter of 0.05 to 10 μm, particularly 0.05 to 2 μm and a porosity of 25 to 85%, particularly 30 to 70% of 3 to 100 μm, and particularly 5 to 40 μm. Those having a thickness are preferable, and among them, a porous graphite film is particularly preferable.

  The carbon film structure of the porous carbon film preferably has a graphitization ratio of 10% or more, preferably 30% or more, particularly preferably 90% or more. When the graphitization ratio is 30% or more, the conductivity is higher than that of an electrode made of a general carbon powder, which is preferable. Ah.

  The porous carbon film has a porous structure having fine communication holes, and is preferably a highly heat-resistant polymer film having a substantially smooth surface other than the open holes, preferably a polyimide porous film, in an anaerobic atmosphere. Can be suitably produced by heating and carbonizing in an inert gas such as nitrogen gas, argon gas, helium gas or in a vacuum. In order to increase the graphitization rate of the carbon structure and increase the mechanical strength, electrical conductivity, and thermal conductivity, the temperature is preferably in the range of 1200 to 3500 ° C, particularly 1900 to 3000 ° C, and particularly preferably in the range of 2600 to 3000 ° C. It is preferable to hold for 20 to 180 minutes in the range.

Examples of the metal compound that gives the metal fine particles by the electroless plating include an inorganic salt or a carboxylate, preferably a chloride, of palladium, platinum, rhodium, ruthenium or iridium.
The electroless plating solution preferably contains a necessary amount of a chelating agent such as tartrate, ethylenediaminetetraacetic acid, a rossel salt, and a hydrazine salt acting as a reducing agent, but substantially via a catalyst. The solution composition is not particularly limited as long as it is adjusted to a solution composition in which the desired metal is reduced and precipitated only by the reduction action.

In the above method, the surface of the porous carbon film is preferably cleaned in advance. Washing in an organic solvent, for example, acetone or methanol, is preferably used for removing fats and oils, and washing with acid is preferably used for removing inorganic components. After washing, it is preferable to sufficiently wash with water. Thereafter, a metal element acting as a catalyst in the initial stage of the electroless plating process is attached to the surface of the pores of the porous carbon film. The element to be attached is not limited as long as it has a reducing effect in the electroless plating treatment, but palladium is preferably used. Palladium can be obtained by, for example, immersing a porous carbon film in an acidic aqueous solution of tin chloride (SnCl ₂ ) so that Sn ²⁺ adheres to the surface of the pores, and then washed with water to form a palladium compound such as palladium chloride or palladium oxide. A method can be used in which immersion in an aqueous solution gives electrons from Sn ²⁺ to Pd ²⁺ , thereby causing reduced Pd to adhere to the pore surface. Alternatively, a method of dissolving a palladium compound such as a metal salt of palladium or an organic palladium complex in a suitable solvent and adsorbing Pd ions on the carbon surface using a solution obtained and reducing the solution may be used.

  In the above method, it is preferable that the electroless plating is performed by adjusting the alkalinity by adding ammonia water, an alkali hydroxide solution, pure water or the like to a metal compound having a desired concentration, for example, a platinum compound solution. As the alkali hydroxide solution, an aqueous ammonia solution is preferably used, and the degree of alkalinity is preferably in the range of pH 8 to 12.5. When adjusted to be alkaline, the metal (platinum) compound is reduced by the catalytic action of palladium and is deposited on the surface of the pores.

It is possible to immerse the porous carbon film which has been subjected to the pretreatment such as the above-mentioned washing in the electroless plating solution, and perform electroless plating at 50 to 70 ° C. for about 1 to 20 minutes, particularly for about 1 to 10 minutes. preferable. If the above-mentioned electroless plating time is too long, the diameter of the metal fine particles increases, and eventually a metal layer is formed, which is not preferable.
By the above method, fine metal particles, particularly fine platinum particles, can be uniformly supported on the pore surfaces of the porous carbon film.
In the present invention, it is necessary to keep the metal, preferably platinum, in the form of fine particles, and therefore it is preferable to keep the temperature and time within the above-mentioned ranges.

Further, it is possible to carry or alloy different metal fine particles by contacting the metal or metal compound fine particles provided by the electroless plating. For example, a porous carbon film carrying platinum by electroless plating is immersed in a solution in which metal ions are dissolved, and a reduction treatment is performed under mild conditions, for example, an operation such as heating or addition of a chemical reducing agent is performed. The metal ions can be preferentially reduced and precipitated on the surface of the platinum fine particles having a large reducing action. Thereafter, the porous carbon film is taken out, washed, dried, and then subjected to a heat treatment under suitable conditions, whereby alloying can be performed.
When considering the electrode application for fuel cells, the metal that works favorably by alloying differs depending on the purpose, but for example, platinum and ruthenium, palladium or An alloy of cobalt and an alloy of platinum and cobalt, iron or nickel are preferably selected for improving the activity, and an alloy of platinum and nickel or iron is preferably selected for cost reduction.

  Next, the porous carbon film is taken out of the liquid, washed with water and repeatedly washed until the washing liquid becomes neutral, and then dried to obtain a metal-carrying porous carbon film which is a catalyst for a target fuel cell. be able to. Further, the conditions are such that an oxide or carbide thin film is not formed on the surface of the supported metal fine particles, preferably under vacuum, or under an inert gas atmosphere at 150 to 400 ° C., preferably 180 to 350 ° C., 10 to 10 ° C. It is more preferable that the post-heat treatment is performed under the conditions of 180 minutes, preferably 20 to 120 minutes to remove the deposits on the surface of the metal fine particles and improve the crystallinity. If the temperature is low, the effect is small, and if the temperature is too high, the metal fine particles react with the carbon of the substrate, and surface contamination and the phenomenon of embedding of the metal fine particles in the substrate occur, which is not preferable.

In the present invention, when the metal-supported porous carbon film is used for a polymer electrolyte fuel cell, the amount of the noble metal particles supported depends on the characteristics required for a fuel cell manufactured using the electrode and the film thickness of the electrode film. Although it depends on the specific surface area, it is converted into 0.01 mg / cm ² or more and 1.0 mg / cm ² or less, particularly 0.5 mg / cm ² or less, particularly 0 mg / cm ² , in terms of the unit area of the electrode. It is preferably used in an amount of 0.25 mg / cm ² or less, and is preferably used in an amount of 0.005 mg / cm ² or more, particularly 0.5 mg / cm ² or less on the hydrogen electrode of the film.

The fuel cell electrode of the present invention is preferably a metal-supported porous carbon membrane comprising the above-mentioned metal-supported porous carbon membrane and optionally a composition in which a polymer electrolyte or an oligomer electrolyte (ionomer) is uniformly dispersed in a solvent. By applying and drying the whole surface of one side or a predetermined shape.
At this time, the polymer electrolyte or the oligomer electrolyte varies depending on the thickness of the electrode membrane and the specific surface area of the pores. For example, when the thickness of the electrode is 30 μm, 0.1 mg / cm ² or more per unit area of the electrode. , 5 mg / cm ² or less, in particular 2 mg / cm ² or less, and preferably even 1 mg / cm ² or less therein.

The above-mentioned polymer electrolyte or oligomer electrolyte may be any polymer or oligomer having ionic conductivity, or any polymer which reacts with an acid or a base to produce a polymer or oligomer having ionic conductivity, or Oligomers can be mentioned.
Suitable polyelectrolytes or oligomer electrolytes include fluoropolymers having pendant ion exchange groups such as sulfonic acid groups in the form of protons or salts, such as fluoropolymers of sulfonic acids, such as Nafion membranes (DuPont), sulfones Acid fluoro-oligomers, sulfonated polyimides, sulfonated oligomers and the like can be mentioned.
The above-mentioned polymer electrolyte or oligomer electrolyte must be substantially insoluble in water at a temperature of 100 ° C. or less.

  Examples of the solvent include C1-6 alcohol, glycerin, ethylene carbonate, propylene carbonate, butyl carbonate, ethylene carbamate, propylene carbamate, butylene carbamate. And polar solvents such as acetone, acetonitrile, dimethylformamide, dimethylacetamide, 1-methyl-2-pyrrolidone, difluorobenzene and sulfolane. The organic solvent may be used alone or as a mixture with water. When a mixed solution of an organic solvent and water is used, it is preferable that the volume ratio of organic solvent: water is in the range of 10: 1 to 1: 3.

The membrane-electrode assembly of the present invention is obtained by joining the fuel cell electrode obtained as described above to both sides of the polymer electrolyte membrane, for example, by hot pressing.
As the polymer electrolyte membrane, any of the above-mentioned polymers or oligomers having ionic conductivity, or any polymer which reacts with an acid or a base to produce a polymer or oligomer having ionic conductivity, or Oligomers can be mentioned.

  The fuel cell of the present invention comprises the above-mentioned membrane-electrode assembly as a constituent element, and preferably uses the above-mentioned membrane-electrode assembly on the oxygen side where water generation is large, and the above-mentioned membrane-electrode assembly on the hydrogen side (fuel side). A membrane-electrode assembly or various other membrane-electrode assemblies (also referred to as a membrane-electrode structure) is used. For example, a pair of separators is provided on both sides of the electrode directly or via a gas diffusion layer. This can be obtained by disposing a seal between the pair of separators to prevent leakage of the reaction gas.

Next, the present invention will be described with reference to examples. However, the present invention is not limited to the following examples.
In the present invention, air permeability, porosity, average pore size, graphitization rate, and performance evaluation of a fuel cell were measured by the following methods.

1) Air permeability Measured according to JIS P8117. A B-type Gurley densometer (manufactured by Toyo Seiki Co., Ltd.) was used as a measuring device. The membrane of the sample is fastened to a circular hole having a diameter of 28.6 mm and an area of 645 mm ² , and the air in the cylinder is allowed to pass through the test hole to the outside of the cylinder with an inner cylinder weight of 567 g. The time during which 100 cc of air passed was measured and defined as the air permeability (Gurley value).

2) Porosity The thickness, area and weight of the film cut into a predetermined size were measured, and the porosity was determined from the basis weight by the following formula. In the following formula, S is the film area, d is the film thickness, w is the measured weight, D is the density, which is 1.34 for polyimide, and the carbon film structure is a sample in consideration of the graphitization ratio obtained by a method described later. The density was calculated for each.
Porosity = (1− (W / S × d × D)) × 100

3) Average pore diameter on membrane surface A scanning electron microscope photograph of the membrane surface was taken, the pore area was measured for 50 or more openings, and the pore shape was determined to be a perfect circle according to the following equation from the average value of the pore areas. The average diameter was determined by calculation. Sa in the following equation means the average value of the hole area.
Average pore size = 2 × (Sa / π) ^1/2
4) Graphitization rate X-ray diffraction was measured and determined by the Ruland method.

5) Thickness of porous carbon film The thickness of the porous carbon film was determined by a contact-type film thickness meter and a scanning microscope observation of a cross section.
6) Size of noble metal particles The size of noble metal fine particles dispersed in the electrode was evaluated by TEM and SEM observation.

7) Performance evaluation of fuel cell By using a fuel cell electronic load device, the fuel gas pressure inside the cell is set to 0.1 MPa, the cell temperature is set to 80 ° C, and the fuel gas is humidified via a bubbler at 70 ° C. Power generation was performed, and current-voltage characteristics were measured.

Reference Example 1
Production of Porous Polyimide Film A polyamic acid solution obtained by polymerizing 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride and paraphenylenediamine in N-methyl-2-pyrrolidone is subjected to mirror polishing. The film was cast on a stainless steel substrate having a predetermined thickness, and NMP was uniformly applied thereon by using a doctor knife and allowed to stand still for 1 minute, and then immersed in methanol to deposit a polyamic acid film. Was. Then, the film was immersed in an ion-exchange water bath to peel off the film from the stainless steel substrate, dried, and then heat-treated at 400 ° C. for 20 minutes to obtain a porous polyimide film.
It was confirmed by SEM observation that this film had a network structure in which polyimide was connected three-dimensionally.
This film had an imidation ratio of 90%, a film thickness of 32 μm, an air permeability of 20 seconds / 100 ml, a porosity of 45%, and an average pore diameter of 0.15 μm on the film surface.

Reference Example 2
Manufacture of porous carbon film This porous polyimide film was carbonized at a temperature of 2100 ° C. for 120 minutes in a nitrogen gas stream, and the graphitization rate was 40%, the film thickness was 27 μm, the air permeability was 26 seconds / 100 ml, and the porosity was 40%. Thus, a porous carbon film having an average pore diameter of 0.13 μm was obtained. It was confirmed by SEM observation that this film had a network structure in which carbon was connected three-dimensionally.

Reference Example 3
Manufacture of porous graphite film The above-mentioned porous carbon film was held at 3000 ° C. for 120 minutes in an atmosphere of argon gas to have a graphitization ratio (crystallinity) of 90% or more, an average pore diameter of 0.11 μm, and a film thickness of 24 μm. A porous graphite film having a lattice constant of 2.53 ° on the a-axis, 6.68 ° on the c-axis, and a crystallite size of 180 ° on the (002) plane and 90 ° on the (101) plane was obtained. When methanol was dropped on the surface of the film, it passed through to the back side, confirming that the film had fine continuous holes inside.

The porous carbon film obtained in Reference Example 2 was immersed in acetone and methanol for washing, washed with water, immersed in an SnCl ₂ hydrochloric acid aqueous solution for 5 minutes, and then immersed in a water bath for 1 minute. Then, the substrate was immersed in an aqueous solution of PdCl ₂ hydrochloric acid for 5 minutes, and then washed with pure water.
TPX-205MU (a solution comprising a platinum compound and an additive) and TPX-205R (a solution comprising a reducing agent and an additive) manufactured by Tanaka Kikinzoku Co., Ltd., which are commercially available as a solvent for producing a platinum electroless plating solution, and ammonia water Then, pure water was mixed and stirred at appropriate times to prepare an electroless plating solution having a pH of about 10 at room temperature, and then heated to a solution temperature of 60 ° C.
In this electroless plating bath, the porous carbon film whose periphery is held by a fluororesin mold is immersed, and the platinum fine particles are deposited on the surface of the pores of the porous carbon film by rotating the entire frame at a slow speed as needed. Was. Eight minutes later, the film was taken out of the plating bath, washed in pure water, and dried to obtain a porous carbon film in which fine platinum particles were dispersed.

The surface and cross section of the porous carbon film in which the fine platinum particles were dispersed were observed with a scanning electron microscope (SEM).
As a result, it was confirmed that the platinum fine particles of about 10 nm were uniformly dispersed and supported without causing aggregation. Further, observation of the platinum fine particles with a high-resolution transmission electron microscope (hereinafter sometimes abbreviated as HRTEM) revealed that the ratio of multiple twin particles was about 20% in terms of the number of particles.

The porous carbon film obtained in Reference Example 2 was immersed in acetone and methanol for washing. After washing with water, it was immersed in a solution prepared by dissolving organic palladium (Pd-C8, manufactured by Degussa Japan) in methanol for 1 hour, taken out, and then subjected to a heat treatment at 300 ° C. for 1.5 hours in the air. Thus, the Pd element was dispersed in the carbon film.
Thereafter, the same operation as in Example 1 was performed except that the plating time was set to 3 minutes and 5 minutes, to obtain a porous carbon film in which fine platinum particles were dispersed. A part thereof was heat-treated at 210 ° C. for 60 minutes in a vacuum atmosphere.
SEM and HRTEM observations were performed on the porous carbon film on which these platinum fine particles were dispersed and supported, and the average particle diameter and the ratio of polycrystalline particles were determined. In addition, it was confirmed that the platinum particles were dispersed and supported on the surface of the film and the surface of the pores inside the film in each of the carbon films.
Table 1 summarizes the average diameter of the platinum fine particles and the ratio of the polycrystalline particles of the platinum-supported porous carbon film of Example 2, and the results of elemental analysis by ICP emission spectrometry. After the post heat treatment, the diameter of the platinum fine particles determined from the SEM observation and the TEM observation did not change from that before the heat treatment.

A platinum-supported porous graphite film was obtained in the same manner as in Example 2, except that the porous graphite film obtained in Reference Example 3 was used.
SEM and HRTEM observations were performed to determine the average particle diameter and the ratio of polycrystalline particles. In addition, it was confirmed that the platinum particles were dispersed and supported on the surface of the film and the surface of the pores inside the film in each of the carbon films.
Table 2 summarizes the average diameter of the platinum fine particles and the ratio of the polycrystalline particles of the platinum-supported porous graphite film of Example 3, and the results of elemental analysis by ICP emission analysis. After the post heat treatment, the diameter of the platinum fine particles determined from the SEM observation and the TEM observation did not change from that before the cross-linking treatment.

  In Examples 2 and 3, the obtained platinum-supported porous carbon film and platinum-supported graphite film were subjected to X-ray scattering measurement to confirm the crystal structure of platinum. In addition, it was confirmed that the sample subjected to the post-heat treatment had sharper scattering on the wide angle side and higher crystallinity.

Of the platinum-carrying porous carbon films obtained in Example 2, those subjected to a post-heat treatment with an electroless plating time of 6 minutes, Nafion / DMF / aqueous solution was dropped at 0.3 mg / cm ² per electrode projected area. The electrode was obtained by coating the proton conductive membrane by heat treatment.
The electrodes were placed on both sides of a commercially available Nafion 11 membrane (manufactured by DuPont) and hot pressed to obtain a membrane-electrode assembly (MEA) of a polymer electrolyte fuel cell. The total amount of platinum and palladium per projected area of this electrode was 0.48 mg / cm ² .
The MEA was sandwiched between both sides of a carbon paper manufactured by Toray and assembled into a fuel cell manufactured by Electrochem, and a fuel cell power generation test was conducted using hydrogen and oxygen gas at a cell temperature of 80 ° C. Was done.
As a result, good power generation characteristics were confirmed. FIG. 8 shows the results. Further, even when the MEA was taken out of the cell after the power generation test, no MEA destruction was observed. After several days, this MEA was incorporated into the fuel cell again, and a similar power generation test was performed. As a result, good power generation characteristics were exhibited with good reproducibility.
In addition, a test using an electrode that was not subjected to post-heat treatment was performed separately from Example 5, and as a result, the output characteristics were about 8% lower than that of the electrode that was heat-treated after 210 ° C.

FIG. 1 is an SEM photograph of the surface of a platinum-supported porous carbon film obtained in Example 1, which is an example of the present invention. FIG. 2 is an SEM photograph of the surface of the platinum-carrying porous carbon film obtained in Example 2, which is an example of the present invention. FIG. 3 is an SEM photograph of the surface of the platinum-supported porous graphite film obtained in Example 3, which is an example of the present invention. FIG. 4 is a high-resolution TEM photograph of the platinum-supported porous graphite film obtained in Example 3, which is an example of the present invention. FIG. 5 is an enlarged photograph of FIG. The picture on the right is the twin twin particles obtained. FIG. 6 is an X-ray scattering profile after the post-heat treatment of the platinum-supported porous graphite film obtained in Example 3, which is an example of the present invention. FIG. 7 is an external photograph of the MEA obtained in Example 5, which is an example of the present invention. FIG. 8 shows a power generation characteristic (IV curve) measured using the fuel cell obtained in Example 5, which is an example of the present invention.

Claims (9)

A metal-supported porous carbon membrane in which metal fine particles having an average particle diameter of 0.7 to 20 nm are dispersed and supported on the surface of the pore surface. The metal-supported porous carbon membrane according to claim 1, wherein the metal fine particles contain a platinum element. The metal fine particles according to claim 1 or 2, wherein the metal fine particles are finely dispersed by performing a chemical reduction reaction with a reducing agent via a catalyst on the metal compound on the surface of the pores of the porous carbon film. Metal-supported porous carbon membrane. The metal-supported porous carbon membrane according to claim 3, wherein the catalyst is a palladium compound supported on the carbon membrane. The metal-supporting porous carbon membrane according to any one of claims 1 to 4, wherein 15 to 95% of the metal fine particles are composed of multiple twin particles. The metal-supported porous carbon film according to claim 5, wherein the multiple twin particles are mainly composed of a platinum element. An electrode for a fuel cell using the metal-supported porous carbon membrane according to claim 1. A membrane-electrode assembly obtained by joining the fuel cell electrode according to claim 7 to both sides of a polymer electrolyte membrane. A fuel cell comprising the fuel cell electrode according to claim 7 as a component.

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