JP2007059248A - Fuel cell and membrane electrode junction - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enhance catalytic activity by controlling particle size of a Pt catalyst to less than 5 nm to improve catalyst activity, and enhance a catalyst utilization efficiency by increasing a catalyst particle ratio existing on the surface of a carbon carrier using the carbon carrier with a reduced specific surface area and with less micropores. <P>SOLUTION: In a fuel cell having a fuel electrode, an oxygen electrode, and a polymer electrolyte membrane interposed between the fuel electrode and the oxygen electrode, the fuel electrode and/or the oxygen electrode contain/contains the catalyst formed by carrying particles containing at least Pt and an oxide of P on the carbon carrier. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a fuel cell and a membrane electrode assembly having a novel catalyst at a fuel electrode and / or an oxygen electrode. More specifically, the present invention relates to a fuel cell and a membrane electrode assembly having, in a fuel electrode and / or an oxygen electrode, a catalyst in which particles containing at least Pt and P oxide are supported on a carbon support.

  Conventionally, most of electric energy has been supplied by thermal power generation, hydroelectric power generation or nuclear power generation. However, thermal power generation not only causes large-scale environmental pollution because it burns fossil fuels such as oil and coal, but depletion of resources such as oil has become a problem. In addition, hydropower generation requires large-scale dam construction, and not only is there concern about the destruction of nature, but there are also limited areas for construction. Nuclear power generation is not only fatal in the radioactive contamination at the time of the accident, but also has a problem of decommissioning nuclear reactors that have reached the end of their life, and is moving in a direction that suppresses construction worldwide.

  Wind power generation and solar power generation have been used around the world as power generation methods that do not require large-scale facilities and do not cause environmental pollution. In Japan, wind power generation and solar power generation are actually used in some areas. It has been put into practical use. However, wind power generation has a drawback in that it cannot generate power without wind, and solar power generation cannot generate power without sunlight, and is affected by natural phenomena and cannot provide stable power supply. Further, in wind power generation, the frequency of the generated power fluctuates due to the strength of the wind, causing a failure of electrical equipment.

  Therefore, recently, research and development on a power generation apparatus that can extract electric energy from hydrogen energy, such as a hydrogen fuel cell, has become active. Hydrogen is obtained by decomposing water and is not only inexhaustible on the earth, but also contains a large amount of chemical energy per substance, and when used as an energy source, harmful substances and global warming gases Has the advantage of not generating.

  Research on fuel cells using methanol instead of hydrogen gas is also actively conducted. A direct methanol fuel cell that directly uses methanol, which is a liquid fuel, is expected to be a relatively small output power source for household use and industrial use because it is an inexpensive fuel in addition to easy handling of the fuel. The theoretical output voltage of the methanol-oxygen fuel cell is 1.2 V (25 ° C.) which is almost the same as that of hydrogen fuel, and in principle the same characteristics can be expected.

  In solid polymer fuel cells and direct methanol fuel cells, hydrogen and methanol are oxidized at the anode, and at the same time, oxygen is reduced at the cathode to extract electric energy. Since these oxidation-reduction reactions are difficult to proceed at room temperature, a catalyst is used in the fuel cell. In early fuel cells, platinum (Pt) has been deposited on a carbon substrate and used as a catalyst. Pt has sufficient catalytic activity for hydrogen oxidation, methanol oxidation and oxygen reduction, so far by controlling the precipitation atmosphere of the Pt catalyst on the carbon substrate, that is, by controlling external factors at the time of precipitation, Attempts have been made to use the Pt catalyst particles by reducing the particle size as much as possible and increasing the reaction surface area of the Pt catalyst.

  For example, in Patent Document 1, when Pt ions are reduced with alcohol and Pt is supported on a carbon substrate, polyvinyl alcohol is added as an organic protecting group to the reaction solution to weaken the organic protecting group on the surface of the Pt catalyst particles. It is adsorbed to make the Pt catalyst finer. In this method, an organic protecting group is adsorbed on the surface of the Pt catalyst. Therefore, after the catalyst synthesis, it is necessary to remove the organic protecting group from the catalyst surface. For this reason, a method of performing heat treatment at 400 ° C. in a hydrogen stream after the production of Pt fine particles has been proposed. However, this treatment method not only removes the organic protecting group completely from the surface of the Pt catalyst, but also heats the 400 ° C. to sinter the Pt catalyst fine particles to increase the Pt catalyst particle size and decrease the catalytic activity. There was a problem to do.

  Further, when the Pt catalyst is synthesized by an impregnation method, an electroless plating method, or an alcohol reduction method, the particle size thereof is concentrated within a range of 5 to 10 nm. When the particle size is 5 to 10 nm, the specific surface area of the Pt catalyst is small and the catalytic activity is not improved. Therefore, in order to increase the activity of the Pt catalyst, it is necessary to increase the specific surface area of the catalyst by setting the Pt particle size to less than 5 nm. In this case, the method of adding an organic protecting group and reducing the particle size of the Pt catalyst cannot be used for the reason described above.

On the other hand, carbon supports having a large specific surface area have been used so far in order to reduce the Pt catalyst particle size. For example, according to Non-Patent Document 1, a Pt catalyst having a particle diameter of 1 nm can be obtained by using a carbon support having a specific surface area of 1,500 m ² / g, and the catalyst can be highly activated. However, the carbon support having such a large specific surface area is porous and has many fine pores. Many catalysts are buried in the micropores. The catalyst buried in the micropores loses the opportunity to contact the fuel and the electrolyte membrane and does not act as a catalyst. If a carbon support with a large specific surface area is used, the catalyst particle size can be made finer and high activation can be achieved, but most of the catalyst is buried in the fine pores, and the utilization rate cannot be increased. Therefore, in the conventional catalysts, there is a trade-off relationship between using a carbon support having a large specific surface area and increasing the catalyst utilization rate by making the catalyst finer and increasing the utilization rate of the catalyst.

JP-A-56-155645 M. Uchida et al., J. Electrochem. Soc., 143, 2245 (1996).

  Accordingly, an object of the present invention is to provide a novel catalyst that simultaneously achieves high activation by refinement of the catalyst and improvement in catalyst utilization.

  As a means for solving the above-mentioned problem, the invention according to claim 1 is a fuel cell having a fuel electrode, an oxygen electrode, and a solid polymer electrolyte membrane interposed between the fuel electrode and the oxygen electrode. The fuel electrode and / or the oxygen electrode includes a catalyst in which particles containing at least Pt and P oxides are supported on a carbon support.

  As means for solving the problem, the invention according to claim 2 is the fuel cell according to claim 1, wherein the content of P in the particles is 1 to 50 at%.

  As means for solving the above-mentioned problems, the invention according to claim 3 is the fuel cell according to claim 1, wherein the particle diameter of the particles is in the range of 1 to 3 nm.

As a means for solving the above-mentioned problems, the invention according to claim 4 is the fuel cell according to claim 1, wherein the specific surface area of the carbon support is 20 to 300 m ² / g.

  As a means for solving the above problems, the invention according to claim 5 is directed to a solid polymer having a fuel electrode, an oxygen electrode, and a solid polymer electrolyte membrane interposed between the fuel electrode and the oxygen electrode. In the solid fuel cell, the fuel electrode and / or the oxygen electrode includes a catalyst in which particles containing at least Pt and P oxide are supported on a carbon support.

  As means for solving the above-mentioned problems, the invention according to claim 6 is directed to a fuel electrode catalyst layer, an oxygen electrode catalyst layer, and a solid height interposed between the fuel electrode catalyst layer and the oxygen electrode catalyst layer. In the membrane electrode assembly comprising a molecular electrolyte membrane, the fuel electrode catalyst layer and / or the oxygen electrode catalyst layer include a catalyst in which particles containing at least Pt and P oxide are supported on a carbon support. Is a membrane electrode assembly.

  As a means for solving the above-mentioned problems, the invention according to claim 7 is the membrane electrode assembly according to claim 6, wherein the content of P in the particles is 1 to 50 at%.

  As a means for solving the above-mentioned problems, the invention according to claim 8 is the membrane electrode assembly according to claim 6, wherein the particle diameter of the particles is in the range of 1 to 3 nm.

As a means for solving the above-mentioned problems, the invention according to claim 9 is the membrane electrode assembly according to claim 6, wherein the specific surface area of the carbon support is 20 to 300 m ² / g.

  As a means for solving the problems, the invention according to claim 10 is a membrane electrode assembly according to claim 6, which is used in a polymer electrolyte fuel cell.

  According to the present invention, when depositing Pt catalyst fine particles on a carbon support by an electroless plating method, an alcohol reduction method, or an ultrasonic reduction method, when adding P to the Pt catalyst to form a binary catalyst, It was discovered that when catalyst particles are deposited on the carbon support, P acts from the inside and outside of the particles to refine the deposited Pt catalyst particles and increase the surface area of the catalyst, resulting in improved catalyst activity. It was.

  1 and 2 are schematic cross-sectional views of catalyst fine particles 1 obtained from the present invention. From the X-ray photoelectron spectroscopic analysis (XPS analysis), in the catalyst particles synthesized by the alcohol reduction method, as shown in FIG. 1, P7 is present as an oxide on the outer surface of the Pt particles 5 supported on the carbon support 3. In the catalyst synthesized by the electroless plating method, as shown in FIG. 2, P7 is present as an oxide on the outer surface of the Pt particle 5, and P8 is present as a metal phosphide or phosphorus alone inside the Pt particle 5. It is suggested that it exists. Therefore, it is considered that P7 and P8 act from the outside or the inside of the Pt particle 5, the particle growth is suppressed, and the entire catalyst fine particle 1 is miniaturized.

In general, a Nafion membrane manufactured by DuPont is used as a solid polymer electrolyte membrane between a fuel electrode catalyst layer and an oxygen electrode catalyst layer of a fuel cell. In the Nafion membrane, the hydrogen atom of the sulfonic acid group becomes H ⁺ and exhibits proton conductivity, so that the Nafion membrane itself exhibits extremely high acidity. Therefore, the interface between the Nafion membrane and the electrode catalyst layer and the catalyst particles pasted with the Nafion resin and the Nafion interface become strongly acidic. In the past, addition of a third metal element (for example, Mo, Mn, Fe, Co, etc.) has been attempted to increase the oxygen reduction activity of the Pt catalyst.

However, since these transition metals do not have sufficient acid resistance, they are eluted as metal ions when in contact with a strongly acidic Nafion resin. As a result of ion conversion of the eluted metal ions with H ⁺ in the Nafion membrane, the proton conductivity of Nafion is lowered and the battery characteristics are deteriorated. However, P was found to be extremely suitable as an additive element for a fuel cell catalyst without acid elution because it has acid resistance unlike conventional third metal elements.

In the present invention, a carbon support having a specific surface area of 20 to 300 m ² / g can be used as the catalyst support. The porosity of the carbon support having a specific surface area in this range is low, and there are few micropores present in the carbon support. Acetylene black (AB), multi-wall carbon nanotubes (MWCNT) and the like are non-porous carbon carriers having no micropores. If these low-porous or non-porous carbon carriers are used, the catalyst particles buried in the micropores are reduced, and a large amount of catalyst particles can be deposited on the carbon carrier surface. If the catalyst particles are present on the surface of the carbon support, the establishment of contact between the fuel and the electrolyte polymer increases, and as a result, the catalyst utilization rate can be improved.

  In addition, MWCNT is bulky compared to conventionally used carbon black. For this reason, when the catalyst is pasted with Nafion resin and is made into an electrode catalyst film by a press machine, there are more physical voids in the electrode catalyst film than in the conventional carbon black support. For this reason, sufficient diffusion of fuel on the catalyst is ensured. Moreover, the diffusibility of the water produced | generated on the cathode catalyst improves, and produced water can move to the electrode catalyst membrane surface quickly, As a result, it becomes possible to improve battery characteristics. Furthermore, MWCNT has a lower specific resistance than carbon black that has been used conventionally. For this reason, it was discovered that IR loss can be suppressed, and as a result, the decrease in battery voltage can be suppressed.

  The fuel cell according to the present invention includes a catalyst in which particles containing at least Pt and P oxides are supported on a carbon support. The content of P in the particles is preferably 1 to 50 at.%. When the P content is 1 at.% Or more, the particle size can be reduced and the catalytic activity can be further increased. Further, when the P content is 50 at.% Or less, the Pt content is increased correspondingly, and the catalytic activity is also improved.

  The particle size of the particles of the present invention is suitably 1 to 3 nm. When the particle size is in the range of 1 to 3 nm, the catalyst surface energy is stable, the specific surface area is sufficiently large, and higher catalyst activity can be obtained.

The specific surface area of the carbon support used as the catalyst support of the present invention is suitably 20 to 300 m ² / g. A specific surface area of 20 m ² / g or more is preferable from the viewpoint of increasing the amount of catalyst supported, and a specific surface area of 300 m ² / g or less is excellent in that the number of micropores in the carbon is small and catalyst embedding in the micropores can be prevented. Yes.

The production method of the catalyst of the present invention by the alcohol reduction method is basically:
(1) dispersing a carbon carrier in one or more types of alcohol or alcohol aqueous solution;
(2) adding a Pt supply source and a reducing P-containing compound to an alcohol or an alcohol aqueous solution in which the carbon carrier is dispersed;
(3) adjusting the pH of the alcohol or alcohol aqueous solution containing the carbon support, the Pt supply source and the P-containing compound;
(4) A step of heating and refluxing the alcohol or the aqueous alcohol solution adjusted to the pH in an inert atmosphere, and generating a fuel cell catalyst in which particles containing at least Pt and P oxide are supported on a carbon support. Consists of things.

The production method of the catalyst of the present invention by electroless plating is basically
(1) dispersing a carbon carrier in pure water;
(2) adding a Pt supply source and a reducing P-containing compound to a pure aqueous solution in which the carbon support is dispersed;
(3) adjusting the pH of the aqueous solution containing the carbon support, the Pt supply source and the reducing P-containing compound;
(4) a step of raising the temperature of the aqueous solution containing the carbon support, the Pt supply source and the reducing P-containing compound in the air or in an inert atmosphere, and particles containing at least Pt and P oxides on the carbon support To produce a fuel cell catalyst on which is supported.

The production method of the catalyst of the present invention by the ultrasonic reduction method is basically
(1) dispersing a carbon carrier in pure water;
(2) adding a Pt supply source and a reducing P-containing compound to the aqueous solution in which the carbon support is dispersed;
(3) adjusting the pH of the aqueous solution in which the carbon support is dispersed and containing the Pt supply source and the reducing P-containing compound;
(4) A step for irradiating the aqueous solution with an ultrasonic wave in the air or in an inert atmosphere to produce a fuel cell catalyst in which particles containing at least Pt and P oxide are supported on the carbon support. Consists of.

  The particle size of the catalyst produced by the production method of the present invention is reduced by the presence of P compared to the particle size of the conventional Pt catalyst. Generally, the particle size of the Pt catalyst produced by the conventional production method is ˜10 nm, but the particle size of the catalyst according to the present invention is reduced to less than 5 nm. This particle size reduction increases the specific surface area of the catalyst and greatly improves hydrogen oxidation and oxygen reduction activity.

  Another feature of the catalyst of the present invention is that the particle size is maintained even when a carbon support having a small specific surface area is used. Until now, if a carbon support having a small specific surface area was used, the number of micropores was small, and the catalyst was not buried in the micropores, and the catalyst utilization rate could be increased. However, on the other hand, the catalyst particle size increased, and the catalytic activity could not be increased. The particle size of the PtP catalyst according to the present invention does not depend on the specific surface area of the carbon support used. Therefore, even if a PtP catalyst is deposited on a carbon support having a large specific surface area, the fine particle size is maintained, and the catalyst utilization rate can be increased while maintaining high activity.

  The acid used for adjusting the pH of the synthesis solution to the acidic side is preferably sulfuric acid having a boiling point higher than 200 ° C. In the alcohol reduction method, the reflux may be performed at a high temperature of about 200 ° C. If the acid has a boiling point of less than 200 ° C, the acid may be dissipated due to the high-temperature reflux, and the pH in the synthesis system is within a predetermined range. It becomes difficult to maintain within. Therefore, hydrochloric acid and nitric acid are not preferred because they have low boiling points and dissipate during heating to reflux. For the same reason, NaOH or KOH is suitable for adjusting the pH of the synthesis solution to the alkali side.

  Examples of the reducing P-containing compound that can be used in the method for producing the catalyst of the present invention include phosphorous acid, phosphite (including both normal salt and acid salt), hypophosphorous acid, and hypophosphite. The salt is preferably an alkali metal salt (for example, sodium phosphite, sodium hydrogen phosphite, sodium hypophosphite, etc.) or an ammonium salt (ammonium phosphite, ammonium hydrogen phosphite, ammonium hypophosphite, etc.). The oxidation number of P in phosphoric acid and phosphate is +5. The +5 valence is the highest valence of P, and its electron configuration is the same noble gas electron configuration as Ne. For this reason, P atoms in phosphoric acid and phosphate are chemically stabilized by the octet rule, and do not serve as a P supply source, and thus are not suitable for the present invention. Accordingly, phosphoric acid and phosphate having +5 valent P atoms cannot be used in the present invention.

  Examples of the Pt source used in the present invention include a dinitrodiamine platinum complex, a platinum triphenylphosphine complex, bis (acetylacetonato) platinum (II), hexachloroplatinic acid, and potassium tetrachloroplatinum (II). Can be used. These platinum compounds may be used alone or in combination of two or more.

  In the alcohol reduction method, when a compound for synthesizing a catalyst is added to an alcohol solvent and refluxed at a temperature near the boiling point of the alcohol solvent, the alcohol (R—OH) emits electrons during the heating and reflux to generate Pt ions. And is oxidized to aldehyde (R′—CHO). In the electroless plating method, for example, when hypophosphite ions are oxidized to phosphite ions or phosphate ions, electrons are released, and these electrons are received by Pt ions and reduced to metal. In the ultrasonic reduction method, a high-pressure and high-temperature field is formed by cavitation to generate a reducing chemical species, thereby reducing Pt ions.

  Examples of the alcohol used in the alcohol reduction method in the present invention include methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, isobutyl alcohol, sec-butyl alcohol, ethylene glycol, glycerin, tetraethylene glycol, Examples include propylene glycol, isoamyl alcohol, n-amyl alcohol, allyl alcohol, 2-ethoxy alcohol, and 1,2-hexadecanediol. One kind or two or more kinds of these alcohols can be appropriately selected and used. In refluxing, in order to prevent oxidation of Pt fine particles, it is preferable to perform refluxing while replacing the inside of the reaction system with an inert gas such as nitrogen or argon.

  The heating temperature and reflux time in the alcohol reduction method vary depending on the type of alcohol used. Generally, the heating temperature is about 60 to 300 ° C., and the reflux time is in the range of 30 minutes to 6 hours. In the case of the electroless plating method, the general bath temperature is 50 to 90 ° C., and the reduction time is 30 minutes to 2 hours. In the case of the ultrasonic reduction method, the ultrasonic irradiation time is 30 minutes to 4 hours.

  In the present invention, in the alcohol reduction method, the Pt supply source and the reducing P-containing compound are dissolved in at least one kind of alcohol. This alcohol may contain water in addition to the case of consisting only of alcohol. In the case of the electroless plating method and the ultrasonic reduction method, the Pt supply source and the reducing P-containing compound are basically added to pure water. In the electroless plating method and the ultrasonic reduction method, the above-described alcohol may be added as a reduction aid.

Bis (acetylacetonato) platinum (II) 2.56 mmol and sodium hypophosphite 1.28 mmol were dissolved in 100 ml of ethylene glycol, respectively, and a multi-wall carbon nanotube (MWCNT, specific surface area 30 m ² / g) 0 as a non-porous support was obtained. .5 g was added to 200 ml ethylene glycol solution dispersed. A sulfuric acid aqueous solution was dropped, and the solution was adjusted to pH 3 using pH test paper. The solution was refluxed for 4 hours with stirring at 200 ° C. in a nitrogen gas atmosphere, and the PtP catalyst was deposited and supported on the multi-wall carbon nanotubes. After completion of the reaction, the catalyst was obtained by filtration, washing and drying.

Bis (acetylacetonato) platinum (II) 2.56 mmol and sodium hypophosphite 1.28 mmol were dissolved in 100 ml of ethylene glycol, respectively, and 0.5 g of acetylene black (AB, specific surface area 68 m ² / g) as a non-porous support. Was added to 200 ml of the dispersed ethylene glycol solution. A sulfuric acid aqueous solution was dropped, and the solution was adjusted to pH 3 using pH test paper. This solution was refluxed for 4 hours with stirring at 200 ° C. in a nitrogen gas atmosphere, and a PtP catalyst was deposited and supported on acetylene black. After completion of the reaction, the catalyst was obtained by filtration, washing and drying.

Dissolve 2.56 mmol of bis (acetylacetonato) platinum (II) and 1.28 mmol of sodium hypophosphite in 100 ml of ethylene glycol, respectively, and add 0.5 g of carbon black (CB, specific surface area 140 m ^{2 /} g) as a porous carrier. To the dispersed 200 ml ethylene glycol solution. A sulfuric acid aqueous solution was dropped, and the solution was adjusted to pH 3 using pH test paper. This solution was refluxed for 4 hours with stirring at 200 ° C. in a nitrogen gas atmosphere, and a PtP catalyst was deposited and supported on carbon black. After completion of the reaction, the catalyst was obtained by filtration, washing and drying.

Dissolve 2.56 mmol of bis (acetylacetonato) platinum (II) and 1.28 mmol of sodium hypophosphite in 100 ml of ethylene glycol, and add 0.5 g of carbon black (CB, specific surface area of 254 m ^{2 /} g) as a porous carrier. To the dispersed 200 ml ethylene glycol solution. A sulfuric acid aqueous solution was dropped, and the solution was adjusted to pH 3 using pH test paper. This solution was refluxed for 4 hours with stirring at 200 ° C. in a nitrogen gas atmosphere, and a PtP catalyst was deposited and supported on carbon black. After completion of the reaction, the catalyst was obtained by filtration, washing and drying.

Bis (acetylacetonato) platinum (II) 2.56 mmol and sodium phosphite 1.28 mmol were dissolved in 100 ml of ethylene glycol, respectively, and multi-wall carbon nanotubes (MWCNT, specific surface area 30 m ² / g) as non-porous support It was added to 200 ml of ethylene glycol solution in which 5 g was dispersed. The solution was refluxed for 4 hours with stirring at 200 ° C. in a nitrogen gas atmosphere, and the PtP catalyst was deposited and supported on the multi-wall carbon nanotubes. After completion of the reaction, the catalyst was obtained by filtration, washing and drying.

Dissolve 2.56 mmol of bis (acetylacetonato) platinum (II) and 1.28 mmol of sodium phosphite in 100 ml of ethylene glycol, respectively, and add 0.5 g of acetylene black (AB, specific surface area 68 m ^{2 /} g) as a non-porous carrier. To the dispersed 200 ml ethylene glycol solution. A sulfuric acid aqueous solution was dropped, and the solution was adjusted to pH 3 using pH test paper. This solution was refluxed for 4 hours with stirring at 200 ° C. in a nitrogen gas atmosphere, and a PtP catalyst was deposited and supported on acetylene black. After completion of the reaction, the catalyst was obtained by filtration, washing and drying.

Dissolve 2.56 mmol of bis (acetylacetonato) platinum (II) and 1.28 mmol of sodium phosphite in 100 ml of ethylene glycol, and disperse 0.5 g of carbon black (CB, specific surface area 140 m ^{2 /} g) as a porous carrier. To the 200 ml ethylene glycol solution. A sulfuric acid aqueous solution was dropped, and the solution was adjusted to pH 3 using pH test paper. This solution was refluxed for 4 hours with stirring at 200 ° C. in a nitrogen gas atmosphere, and a PtP catalyst was deposited and supported on carbon black. After completion of the reaction, the catalyst was obtained by filtration, washing and drying.

Dissolve 2.56 mmol of bis (acetylacetonato) platinum (II) and 1.28 mmol of sodium phosphite in 100 ml of ethylene glycol, and disperse 0.5 g of carbon black (CB, specific surface area 254 m ^{2 /} g) as a porous carrier. To the 200 ml ethylene glycol solution. A sulfuric acid aqueous solution was dropped, and the solution was adjusted to pH 3 using pH test paper. This solution was refluxed for 4 hours with stirring at 200 ° C. in a nitrogen gas atmosphere, and a PtP catalyst was deposited and supported on carbon black. After completion of the reaction, the catalyst was obtained by filtration, washing and drying.

0.5 g of multi-wall carbon nanotubes (MWCNT, specific surface area 30 m ^{2 /} g), which is a non-porous carrier, was dispersed in ion-exchanged water. 2.56 mmol of hexachloroplatinic acid hexahydrate and 5.12 mmol of sodium hypophosphite were dissolved in 500 ml of ion-exchanged water and added. An aqueous sodium hydroxide solution was added dropwise, and the solution was adjusted to pH 11 using a pH meter. The bath temperature was raised to 80 ° C. using a hot plate while stirring in the atmosphere, and electroless plating was performed for 2 hours to deposit and support the PtP catalyst on the multi-wall carbon nanotubes. After completion of the reaction, the catalyst was obtained by filtration, washing and drying.

Acetylene black (AB, specific surface area 68 m ^{2 /} g) 0.5 g, which is a non-porous carrier, was dispersed in deionized water in pure water. 2.56 mmol of hexachloroplatinic acid hexahydrate and 5.12 mmol of sodium hypophosphite were dissolved in 500 ml of ion-exchanged water and added. An aqueous sodium hydroxide solution was added dropwise, and the solution was adjusted to pH 11 using a pH meter. The liquid temperature was raised to 80 ° C. using a hot plate while stirring in the atmosphere, and electroless plating was performed for 2 hours to deposit and support the PtP catalyst on acetylene black. After completion of the reaction, the catalyst was obtained by filtration, washing and drying.

Carbon ion (CB, specific surface area 140 m ^{2 /} g) 0.5 g as a porous carrier was dispersed in ion exchange water. 2.56 mmol of hexachloroplatinic acid hexahydrate and 5.12 mmol of sodium hypophosphite were dissolved in 500 ml of ion-exchanged water and added. An aqueous sodium hydroxide solution was added dropwise, and the solution was adjusted to pH 11 using a pH meter. The liquid temperature was raised to 80 ° C. using a hot plate while stirring in the atmosphere, and electroless plating was performed for 2 hours to deposit and support the PtP catalyst on the carbon black. After completion of the reaction, the catalyst was obtained by filtration, washing and drying.

In ion-exchanged water, 0.5 g of carbon black (CB, specific surface area of 254 m ^{2 /} g) as a porous carrier was dispersed. 2.56 mmol of hexachloroplatinic acid hexahydrate and 5.12 mmol of sodium hypophosphite were dissolved in 500 ml of ion-exchanged water and added. An aqueous sodium hydroxide solution was added dropwise, and the solution was adjusted to pH 11 using a pH meter. The liquid temperature was raised to 80 ° C. using a hot plate while stirring in the atmosphere, and electroless plating was performed for 2 hours to deposit and support the PtP catalyst on the carbon black. After completion of the reaction, the catalyst was obtained by filtration, washing and drying.

0.5 g of multi-wall carbon nanotubes (MWCNT, specific surface area 30 m ^{2 /} g), which is a non-porous carrier, was dispersed in ion-exchanged water. 2.56 mmol of hexachloroplatinic acid hexahydrate and 5.12 mmol of sodium phosphite were dissolved in 500 ml of ion-exchanged water and added. An aqueous sodium hydroxide solution was added dropwise, and the solution was adjusted to pH 11 using a pH meter. The liquid temperature was raised to 80 ° C. using a hot plate while stirring in the atmosphere, and electroless plating was performed for 2 hours to deposit and support the PtP catalyst on the multi-wall carbon nanotubes. After completion of the reaction, the catalyst was obtained by filtration, washing and drying.

In ion-exchanged water, 0.5 g of acetylene black (AB, specific surface area 68 m ^{2 /} g), which is a non-porous carrier, was dispersed. 2.56 mmol of hexachloroplatinic acid hexahydrate and 5.12 mmol of sodium phosphite were dissolved in 500 ml of ion-exchanged water and added. An aqueous sodium hydroxide solution was added dropwise, and the solution was adjusted to pH 11 using a pH meter. The liquid temperature was raised to 80 ° C. using a hot plate while stirring in the atmosphere, and electroless plating was performed for 2 hours to deposit and support the PtP catalyst on acetylene black. After completion of the reaction, the catalyst was obtained by filtration, washing and drying.

Carbon ion (CB, specific surface area 140 m ^{2 /} g) 0.5 g as a porous carrier was dispersed in ion exchange water. 2.56 mmol of hexachloroplatinic acid hexahydrate and 5.12 mmol of sodium phosphite were dissolved in 500 ml of ion-exchanged water and added. An aqueous sodium hydroxide solution was added dropwise, and the solution was adjusted to pH 11 using a pH meter. The liquid temperature was raised to 80 ° C. using a hot plate while stirring in the atmosphere, and electroless plating was performed for 2 hours to deposit and support the PtP catalyst on the carbon black. After completion of the reaction, the catalyst was obtained by filtration, washing and drying.

In ion-exchanged water, 0.5 g of carbon black (CB, specific surface area of 254 m ^{2 /} g) as a porous carrier was dispersed. 2.56 mmol of hexachloroplatinic acid hexahydrate and 5.12 mmol of sodium phosphite were dissolved in 500 ml of ion-exchanged water and added. An aqueous sodium hydroxide solution was added dropwise, and the solution was adjusted to pH 11 using a pH meter. The liquid temperature was raised to 80 ° C. using a hot plate while stirring in the atmosphere, and electroless plating was performed for 2 hours to deposit and support the PtP catalyst on the carbon black. After completion of the reaction, the catalyst was obtained by filtration, washing and drying.

0.5 g of multi-wall carbon nanotubes (MWCNT, specific surface area 30 m ^{2 /} g), which is a non-porous carrier, was dispersed in ion-exchanged water. 2.56 mmol of hexachloroplatinic acid hexahydrate and 2.56 mmol of sodium hypophosphite were dissolved in 500 ml of ion-exchanged water and added. An aqueous sodium hydroxide solution was added dropwise, and the solution was adjusted to pH 10 using a pH meter. In the atmosphere, this solution was subjected to ultrasonic irradiation treatment for 2 hours using a commercially available ultrasonic cleaning device, and the PtP catalyst was deposited and supported on the multi-wall carbon nanotubes. After completion of the reaction, the catalyst was obtained by filtration, washing and drying.

In ion-exchanged water, 0.5 g of acetylene black (AB, specific surface area 68 m ^{2 /} g), which is a non-porous carrier, was dispersed. 2.56 mmol of hexachloroplatinic acid hexahydrate and 2.56 mmol of sodium hypophosphite were dissolved in 500 ml of ion-exchanged water and added. An aqueous sodium hydroxide solution was added dropwise, and the solution was adjusted to pH 10 using a pH meter. In the atmosphere, this solution was subjected to ultrasonic irradiation treatment for 2 hours using a commercially available ultrasonic cleaning device, and the PtP catalyst was deposited and supported on acetylene black. After completion of the reaction, the catalyst was obtained by filtration, washing and drying.

Carbon ion (CB, specific surface area 140 m ^{2 /} g) 0.5 g as a porous carrier was dispersed in ion exchange water. 2.56 mmol of hexachloroplatinic acid hexahydrate and 2.56 mmol of sodium hypophosphite were dissolved in 500 ml of ion-exchanged water and added. An aqueous sodium hydroxide solution was added dropwise, and the solution was adjusted to pH 10 using a pH meter. In the atmosphere, this solution was subjected to ultrasonic irradiation treatment for 2 hours using a commercially available ultrasonic cleaning device, and a PtP catalyst was deposited and supported on carbon black. After completion of the reaction, the catalyst was obtained by filtration, washing and drying.

In ion-exchanged water, 0.5 g of carbon black (CB, specific surface area of 254 m ^{2 /} g) as a porous carrier was dispersed. 2.56 mmol of hexachloroplatinic acid hexahydrate and 2.56 mmol of sodium hypophosphite were dissolved in 500 ml of ion-exchanged water and added. An aqueous sodium hydroxide solution was added dropwise, and the solution was adjusted to pH 10 using a pH meter. In the atmosphere, this solution was subjected to ultrasonic irradiation treatment for 2 hours using a commercially available ultrasonic cleaning device, and a PtP catalyst was deposited and supported on carbon black. After completion of the reaction, the catalyst was obtained by filtration, washing and drying.

0.5 g of multi-wall carbon nanotubes (MWCNT, specific surface area 30 m ^{2 /} g), which is a non-porous carrier, was dispersed in ion-exchanged water. 2.56 mmol of hexachloroplatinic acid hexahydrate and 2.56 mmol of sodium phosphite were dissolved in 500 ml of ion-exchanged water and added. An aqueous sodium hydroxide solution was added dropwise, and the solution was adjusted to pH 10 using a pH meter. In the atmosphere, this solution was subjected to ultrasonic irradiation treatment for 2 hours using a commercially available ultrasonic cleaning device, and the PtP catalyst was deposited and supported on the multi-wall carbon nanotubes. After completion of the reaction, the catalyst was obtained by filtration, washing and drying.

In ion-exchanged water, 0.5 g of acetylene black (AB, specific surface area 68 m ^{2 /} g), which is a non-porous carrier, was dispersed. 2.56 mmol of hexachloroplatinic acid hexahydrate and 2.56 mmol of sodium phosphite were dissolved in 500 ml of ion-exchanged water and added. An aqueous sodium hydroxide solution was added dropwise, and the solution was adjusted to pH 10 using a pH meter. In the atmosphere, this solution was subjected to ultrasonic irradiation treatment for 2 hours using a commercially available ultrasonic cleaning device, and the PtP catalyst was deposited and supported on acetylene black. After completion of the reaction, the catalyst was obtained by filtration, washing and drying.

Carbon ion (CB, specific surface area 140 m ^{2 /} g) 0.5 g as a porous carrier was dispersed in ion exchange water. 2.56 mmol of hexachloroplatinic acid hexahydrate and 2.56 mmol of sodium phosphite were dissolved in 500 ml of ion-exchanged water and added. An aqueous sodium hydroxide solution was added dropwise, and the solution was adjusted to pH 10 using a pH meter. In the atmosphere, this solution was subjected to ultrasonic irradiation treatment for 2 hours using a commercially available ultrasonic cleaning device, and a PtP catalyst was deposited and supported on carbon black. After completion of the reaction, the catalyst was obtained by filtration, washing and drying.

In ion-exchanged water, 0.5 g of carbon black (CB, specific surface area of 254 m ^{2 /} g) as a porous carrier was dispersed. 2.56 mmol of hexachloroplatinic acid hexahydrate and 2.56 mmol of sodium phosphite were dissolved in 500 ml of ion-exchanged water and added. An aqueous sodium hydroxide solution was added dropwise, and the solution was adjusted to pH 10 using a pH meter. In the atmosphere, this solution was subjected to ultrasonic irradiation treatment for 2 hours using a commercially available ultrasonic cleaning device, and a PtP catalyst was deposited and supported on carbon black. After completion of the reaction, the catalyst was obtained by filtration, washing and drying.

Dissolve 2.56 mmol of hexachloroplatinic acid hexahydrate and 1.28 mmol of sodium hypophosphite in 100 ml of ethylene glycol aqueous solution (ethylene glycol: ion-exchanged water = 50 vol.%: 50 vol.%), Respectively. It was added to a 200 m ethylene glycol aqueous solution (ethylene glycol: ion-exchanged water = 50 vol.%: 50 vol.%) In which 0.5 g of a certain multi-wall carbon nanotube (MWCNT, specific surface area 30 m ^{2 /} g) was dispersed. A sulfuric acid aqueous solution was dropped, and the solution was adjusted to pH 3 using pH test paper. The solution was refluxed for 4 hours with stirring at 130 ° C. in a nitrogen gas atmosphere, and a PtP catalyst was deposited and supported on the multi-wall carbon nanotubes. After completion of the reaction, the catalyst was obtained by filtration, washing and drying.

A multiporous solid carrier is obtained by dissolving 2.56 mmol of hexachloroplatinic acid hexahydrate and 1.28 mmol of sodium hypophosphite in 100 ml of an aqueous ethanol solution (ethanol: ion-exchanged water = 50 vol.%: 50 vol.%). This was added to a 200 m aqueous ethanol solution (ethanol: ion-exchanged water = 50 vol.%: 50 vol.%) In which 0.5 g of wall carbon nanotubes (MWCNT, specific surface area 30 m ^{2 /} g) was dispersed. A sulfuric acid aqueous solution was dropped, and the solution was adjusted to pH 3 using pH test paper. Under a nitrogen gas atmosphere, this solution was refluxed for 4 hours at 95 ° C. with stirring, and PtP catalyst fine particles were deposited and supported on the multi-wall carbon nanotubes. After completion of the reaction, the catalyst was obtained by filtration, washing and drying.

Dissolve 2.56 mmol of bis (acetylacetonato) platinum (II) and 1.28 mmol of sodium hypophosphite in 100 ml of ethylene glycol, and add 0.5 g of carbon black (CB, specific surface area 800 m ^{2 /} g) as a porous carrier. To the dispersed 200 ml ethylene glycol solution. A sulfuric acid aqueous solution was dropped, and the solution was adjusted to pH 3 using pH test paper. This solution was refluxed for 4 hours with stirring at 200 ° C. in a nitrogen gas atmosphere, and a PtP catalyst was deposited and supported on carbon black. After completion of the reaction, the catalyst was obtained by filtration, washing and drying.
(Comparative Example 1)

Dissolve 2.56 mmol of bis (acetylacetonato) platinum (II) in 200 ml of ethylene glycol, and disperse 0.5 g of multi-wall carbon nanotubes (MWCNT, specific surface area of 30 m ² / g) as a non-porous carrier. Added to ethylene glycol solution. A sulfuric acid aqueous solution was dropped, and the solution was adjusted to pH 3 using pH test paper. This solution was refluxed for 4 hours with stirring at 200 ° C. in a nitrogen gas atmosphere, and a Pt catalyst was deposited and supported on the multi-wall carbon nanotubes. After completion of the reaction, the catalyst was obtained by filtration, washing and drying.
(Comparative Example 2)

200 ml of ethylene glycol in which 2.56 mmol of bis (acetylacetonato) platinum (II) was dissolved in 200 ml of ethylene glycol and 0.5 g of acetylene black (AB, specific surface area 68 m ² / g) as a non-porous carrier was dispersed. Added to the solution. A sulfuric acid aqueous solution was dropped, and the solution was adjusted to pH 3 using pH test paper. This solution was refluxed for 4 hours with stirring at 200 ° C. in a nitrogen gas atmosphere, and the Pt catalyst was deposited and supported on acetylene black. After completion of the reaction, the catalyst was obtained by filtration, washing and drying.
(Comparative Example 3)

200 ml of ethylene glycol solution in which 2.56 mmol of bis (acetylacetonato) platinum (II) is dissolved in 200 ml of ethylene glycol and 0.5 g of carbon black (CB, specific surface area 140 m ² / g) as a porous carrier is dispersed. Added to. A sulfuric acid aqueous solution was dropped, and the solution was adjusted to pH 3 using pH test paper. This solution was refluxed for 4 hours with stirring at 200 ° C. in a nitrogen gas atmosphere, and the Pt catalyst was deposited and supported on carbon black. After completion of the reaction, the catalyst was obtained by filtration, washing and drying.
(Comparative Example 4)

200 ml of ethylene glycol solution in which 2.56 mmol of bis (acetylacetonato) platinum (II) is dissolved in 200 ml of ethylene glycol and 0.5 g of carbon black (CB, specific surface area 254 m ² / g) as a porous carrier is dispersed. Added to. A sulfuric acid aqueous solution was dropped, and the solution was adjusted to pH 3 using pH test paper. This solution was refluxed for 4 hours with stirring at 200 ° C. in a nitrogen gas atmosphere, and the Pt catalyst was deposited and supported on carbon black. After completion of the reaction, the catalyst was obtained by filtration, washing and drying.

  The composition of each catalyst obtained in Examples 1 to 27 and Comparative Examples 1 to 4 was examined by fluorescent X-ray analysis (XRF). The particle size was examined with a transmission electron microscope (TEM). The results are shown in Table 1. In Examples 1 to 27, it can be seen that P is added to the Pt catalyst by adding sodium hypophosphite or sodium phosphite into the synthesis system. The particle size of the PtP catalyst obtained in the examples is reduced to 2 nm.

  In Examples 1 to 26, addition of P has an effect of reducing the particle size of the Pt catalyst to 2 nm even when a non-porous carbon support having a small specific surface area is used. The use of a non-porous carbon carrier having a small specific surface area improves the catalyst utilization efficiency by precipitating all the catalyst on the surface of the carrier. Even when a non-porous carbon support having a low specific surface area is used, the addition of P can reduce the catalyst particle size to 2 nm and maintain high catalytic activity. Therefore, the catalyst of the present invention is a very useful catalyst material that can achieve high activation and improvement in catalyst utilization at the same time.

  Furthermore, in Example 25, an ethylene glycol aqueous solution was used as the alcohol, and the reflux temperature was lowered from 200 ° C. to 130 ° C. to synthesize a PtP catalyst. The growth of fine particles is suppressed by reducing the synthesis temperature. Therefore, by reducing the synthesis temperature to 130 ° C., a PtP catalyst having a particle size of 1.8 nm is obtained. Similarly, in Example 26, an aqueous ethanol solution was used and a PtP catalyst was synthesized at a reflux temperature of 95 ° C. As a result, a PtP catalyst having a particle size of 1.5 nm is obtained.

On the other hand, since Comparative Examples 1 to 4 do not contain P, the particle size of the Pt catalyst is as large as 6 to 10 nm. Although the particle size of the Pt catalyst tends to decrease as the specific surface area of the carbon support used increases, the particle size is about ˜5 nm even when CB having a specific surface area of 254 m ² / g is used.

MWCNT：マルチウォールカーボンナノチューブ AB：アセチレンブラック CB：カーボンブラック

MWCNT: Multi-wall carbon nanotubes AB: Acetylene black CB: Carbon black

After adding and stirring the alcohol solution of a pure water and Nafion (made by Du Pont) to the carbon carrying catalyst obtained in Examples 1-27, the viscosity was adjusted and it was set as the ink for catalysts. This was applied onto a Teflon (registered trademark) sheet so that the application amount of the PtP catalyst was 0.3 mg / cm ² (for hydrogen electrode) and 0.6 mg / cm ² (for oxygen electrode). After drying, the catalyst electrode prepared above was transferred to both sides of the solid polymer electrolyte membrane (Nafion membrane 112 manufactured by DuPont) by hot pressing, and then the Teflon (registered trademark) sheet was peeled off to prepare a membrane electrode assembly. Using this membrane electrode assembly, a polymer electrolyte fuel cell shown in FIG. 3 was produced. In FIG. 3, reference numeral 40 denotes a polymer electrolyte fuel cell. Reference numeral 44 denotes an oxygen electrode side current collector, 43 denotes an oxygen electrode side diffusion layer, 41 denotes a solid polymer electrolyte membrane, 48 denotes a hydrogen electrode side diffusion layer, 47 denotes a hydrogen electrode side current collector, and 42 denotes an air introduction hole. , 45 represents an oxygen electrode PtP catalyst layer, 46 represents a hydrogen electrode PtP catalyst layer, and 49 represents a hydrogen fuel introduction hole. The oxygen electrode side current collector 44 has a function as a structure that takes in air (oxygen) through the air introduction hole 42 and also has a current collecting function. The solid polymer electrolyte membrane (Nafion membrane 112 manufactured by DuPont) 41 has a function of transporting protons generated at the hydrogen electrode to the oxygen electrode side and a function as a separator for preventing a short circuit between the hydrogen electrode and the oxygen electrode. It will be. In the polymer electrolyte fuel cell 40 configured as described above, the hydrogen gas supplied from the hydrogen electrode side current collector 47 is led to the hydrogen electrode catalyst layer 46 through the hydrogen electrode side diffusion layer 48 and is oxidized and electrons. These protons move to the oxygen electrode side through the solid polymer electrolyte membrane 41. At the oxygen electrode, oxygen taken in from the oxygen electrode side current collector 44 is reduced by electrons generated at the hydrogen electrode, and this reacts with the protons to generate water. In the polymer electrolyte fuel cell 40 shown in FIG. 3, power generation occurs due to such hydrogen oxidation reaction and oxygen reduction reaction.
(Comparative Example 5)

  A polymer electrolyte fuel cell was produced in the same manner as in Example 28 except that the Pt catalyst obtained in Comparative Examples 1 to 4 was used as an electrode catalyst instead of the carbon-supported catalyst of the present invention in Example 28. did.

The power density of the polymer electrolyte fuel cells obtained in Example 28 and Comparative Example 5 was measured. The measurement results are shown in Table 2. In Example 28, since the catalyst of the present invention was used, the catalyst particle size was 2 nm or less. The catalysts prepared in Examples 1 to 26 are non-porous carbon supports or porous supports, but use a carbon support having a specific surface area of less than 300 m ² / g and few micropores. Therefore, at the same time as the catalyst activity is increased, the catalyst utilization rate is increased, and a high power density of 235 mW / cm ² or more is obtained. In Example 27 in which CB having a large specific surface area of 800 m ² / g was used as the carrier, the power density was 200 mW / cm ² .

  In the table, it can be seen that the power density of the carbon support increases in the order of CB, AB, and MWCNT. The reason why CB gave the lowest power density is that because CB is a porous carrier, some PtP catalysts are buried in the micropores and cannot contribute to hydrogen oxidation and oxygen reduction reactions. Since AB is a non-porous support, it provides a higher power density than CB support. In addition to being non-porous, the MWCNT support has many physical voids in the electrode catalyst layer due to its shape. This promotes diffusion of hydrogen gas and oxygen gas as fuel and water generated at the cathode electrode. Furthermore, since the specific resistance of MWCNT is lower than that of CB, IR loss can be reduced, and as a result of suppressing the decrease in battery voltage, it is considered that a high output density was given.

In Example 25, the reflux temperature was reduced from 200 ° C. to 130 ° C., and in Example 26, the temperature was lowered to 95 ° C. to synthesize a PtP catalyst. This reduction in the synthesis temperature suppresses catalyst particle growth, and the particle size of the PtP catalyst is reduced to 1.8 nm and 1.5 nm. Due to this particle size reduction, the specific surface area of the catalyst is increased, the catalytic activity is enhanced, and a high power density of 260 mW / cm ² or higher is obtained.

On the other hand, in Comparative Example 5, the particle size of the Pt catalyst not containing P was as large as ˜5 to 10 nm, and the output density was as low as 170 to 185 mW / cm ² .

MWCNT：マルチウォールカーボンナノチューブ AB：アセチレンブラック CB：カーボンブラック

MWCNT: Multi-wall carbon nanotubes AB: Acetylene black CB: Carbon black

Bis (acetylacetonato) platinum (II) 2.56 mmol and sodium hypophosphite (NaPH ₂ O ₂ ) 0 to 0.14 mmol were dissolved in 100 ml of ethylene glycol, respectively, and carbon nanotubes (CB, specific surface area 140 m) as a porous carrier were dissolved. ^{2 /} g) was added to 200 ml of ethylene glycol solution in which 0.5 g was dispersed. A sulfuric acid aqueous solution was dropped, and the solution was adjusted to pH 3 using pH test paper. This solution was refluxed for 4 hours with stirring at 200 ° C. in a nitrogen gas atmosphere, and Pt and PtP catalysts were deposited and supported on carbon black. After completion of the reaction, the catalyst was obtained by filtration, washing and drying.

The particle size of the catalyst was examined with an electron microscope, and the composition was analyzed with fluorescence X. Further, using the synthesized catalyst, a polymer electrolyte fuel cell was produced in the same manner as in Example 28, and the cell characteristics were evaluated. The results are summarized in Table 3. It was found that high power density of 200 mW / cm ² or more was obtained with a P content of 1 to 45 at.%.

It is a typical sectional view of catalyst fine particles of the present invention. It is a typical sectional view of catalyst fine particles of the present invention. It is a partial schematic block diagram of an example of a polymer electrolyte fuel cell.

Explanation of symbols

1 PtP catalyst fine particles of the present invention 3 Carbon support 5 Pt particles 7 P
8 P
40 polymer electrolyte fuel cell 41 polymer electrolyte membrane 42 air introduction hole 43 oxygen electrode side diffusion layer 44 oxygen electrode side current collector 45 oxygen electrode PtP catalyst layer 46 hydrogen electrode PtRu catalyst layer 47 hydrogen electrode side current collector 48 Hydrogen electrode side diffusion layer 49 Hydrogen fuel introduction hole

Claims (10)

In a fuel cell having a fuel electrode, an oxygen electrode, and a solid polymer electrolyte membrane interposed between the fuel electrode and the oxygen electrode,
The fuel electrode and / or oxygen electrode,
A fuel cell comprising a catalyst having particles containing at least Pt and P oxide supported on a carbon support. 2. The fuel cell according to claim 1, wherein the content of P in the particles is 1 to 50 at%. The fuel cell according to claim 1, wherein the particle diameter is in the range of 1 to 3 nm. ^2. The fuel cell according to claim 1, wherein the specific surface area of the carbon support is 20 to 300 m < ² > / g. In a polymer electrolyte fuel cell having a fuel electrode, an oxygen electrode, and a polymer electrolyte membrane interposed between the fuel electrode and the oxygen electrode,
The fuel electrode and / or oxygen electrode,
A solid polymer fuel cell comprising a catalyst in which particles containing at least Pt and P oxides are supported on a carbon support. In a membrane electrode assembly comprising a fuel electrode catalyst layer, an oxygen electrode catalyst layer, and a solid polymer electrolyte membrane interposed between the fuel electrode catalyst layer and the oxygen electrode catalyst layer,
The fuel electrode catalyst layer and / or the oxygen electrode catalyst layer,
A membrane electrode assembly comprising a catalyst in which particles containing at least Pt and P oxides are supported on a carbon support. 7. The membrane electrode assembly according to claim 6, wherein the content of P in the particles is 1 to 50 at%. The membrane electrode assembly according to claim 6, wherein the particle diameter is in the range of 1 to 3 nm. 7. The membrane electrode assembly according to claim 6, wherein the carbon carrier has a specific surface area of 20 to 300 m < ² > / g. 7. The membrane electrode assembly according to claim 6, which is used in a polymer electrolyte fuel cell.

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