JP2006252938A - Electrode for solid polymer electrolyte fuel cell and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrode for a solid polymer electrolyte fuel cell uniformly carrying a catalyst metal for markedly enhancing the activity of the catalyst metal in an extremely small amount metal carrying electrode, and providing superior characteristics, by forming a film of uniform cation exchange resin on the surface of a carbon material, and to provide its manufacturing method. <P>SOLUTION: In the electrode for the polymer electrolyte fuel cell, a catalyst metal is carried mainly on the contact surface between a carbon material and a proton-conducting channel of cation exchange resin, and the carbon material contains 0.1-10 mass% boron. A functional group containing oxygen atoms or nitrogen atoms is present in a range of 0.1-10.0 meq/g on the surface of the carbon material. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an electrode for a polymer electrolyte fuel cell and a method for producing the same.

  A polymer electrolyte fuel cell (PEFC) is one of the promising candidates as a power source for an electric vehicle or a home cogeneration system due to its high energy conversion efficiency and low environmental load. The membrane / electrode assembly used for PEFC is composed of an anode, a cathode, and a cation exchange membrane that separates the electrodes, and is manufactured by joining the electrode and the cation exchange membrane by thermocompression bonding. A polymer electrolyte fuel cell including this membrane / electrode assembly can generate electric power by supplying hydrogen as a fuel to an anode and oxygen as an oxidant to a cathode, for example.

  For example, as disclosed in Patent Document 1 and Patent Document 2, a catalyst metal is mainly supported on the contact surface between the carbon material and the proton conduction path of the cation exchange resin. Electrode is used. An electrode using this catalyst is said to be an ultra-small catalyst metal-supported electrode.

  This ultra-small catalyst metal-supported electrode for a polymer electrolyte fuel cell is produced by the following procedure. First, a carbon material and a polymer electrolyte solution are mixed. After the mixture is applied to the electrode substrate, it is dried to form a catalyst metal unsupported electrode. Next, the catalyst metal unsupported electrode is immersed in a solution containing a catalyst metal cation to adsorb the cation to the proton conduction path of the cation exchange resin contained in the electrode. Finally, the catalytic metal is supported on the contact surface between the proton conduction path of the cation exchange resin and the surface of the carbon material by chemically reducing the cation.

  On the other hand, in a polymer electrolyte fuel cell, the use of a catalyst in which a platinum (Pt) catalyst is supported on carbon powder having a boron content of 0.001 to 5% by mass improves the chemical corrosivity and conductivity. Patent Document 3 discloses a technique that uses graphitized fine carbon powder having excellent properties. Patent Document 4 uses a polymer electrolyte fuel cell electrode based on carbon alloy fine particles doped with boron atoms, the boron atom doping amount is 0.5 to 20 atomic%, and the cathode electrode. Has been disclosed that realizes a cathode catalyst that can promote the oxygen reduction reaction that occurs in the process, and that the carbon material itself of the catalyst support has an oxygen reduction catalyst function.

Japanese Patent Application No. 10-189807 JP 2000-12041 A Japanese Patent Publication No. WO01 / 092151 JP 2004-362802 A

  However, in the conventional method for producing an ultra-small catalyst metal-carrying electrode, since the affinity between the carbon material and the cation exchange resin is low, the adhesion state between the surface of the carbon material and the cation exchange resin is not uniform. Therefore, for example, the distribution state of the catalyst metal such as platinum (Pt) becomes non-uniform, so that the catalytic activity of the electrode using this catalyst metal is lowered. Therefore, the output of the PEFC provided with the conventional ultra-small catalyst metal-carrying electrode was low.

  In addition, there is a technology that contains boron in the carbon used for the electrode for the polymer electrolyte fuel cell, but there is no technology that applies the boron-added carbon to the ultra-small catalyst metal-supported electrode for the polymer electrolyte fuel cell. There is no literature focusing on the relationship between the addition of cation exchange resin coatings formed on the surface of carbon particles.

  Thus, the present invention is based on the finding that a cation exchange resin film can be uniformly formed on the surface of a carbon material by including boron in the carbon material. The object of the present invention is to form a uniform cation exchange resin film on the surface of the carbon material, so that the catalyst metal is uniformly supported, and the activity of the catalyst metal in the ultra-small amount of catalyst metal-supported electrode is remarkably enhanced. An object of the present invention is to provide a polymer electrolyte fuel cell electrode exhibiting characteristics and a method for producing the same.

  The first aspect of the present invention is the electrode for a polymer electrolyte fuel cell, wherein a catalytic metal is mainly supported on the contact surface between the carbon material and the proton conduction path of the cation exchange resin, and the carbon material is 0.1 mass% It contains 10% by mass or less of boron.

  According to a second aspect of the present invention, in the polymer electrolyte fuel cell electrode according to the first aspect, the functional group containing an oxygen atom or a nitrogen atom is present at 0.1 meq / g or more and 10.0 meq / g or less on the surface of the carbon material. It is provided with a range.

  A third aspect of the present invention relates to a method for producing an electrode for a polymer electrolyte fuel cell according to the first aspect, wherein the carbon material contains boron in a range of 0.1 mass% to 10 mass%. Forming a dispersion in which the carbon material is dispersed in a cation exchange resin solution, removing a solvent from the dispersion to obtain a mixture of the carbon material and the cation exchange resin, and the cation exchange resin. A third step of adsorbing the cation of the catalytic metal to the fixed ions of the ion exchange resin and a fourth step of chemically reducing the cation are characterized.

  A fourth aspect of the present invention relates to a method for producing an electrode for a polymer electrolyte fuel cell according to the second aspect, wherein the carbon material contains boron in a range of 0.1 mass% to 10 mass%. A second step of forming a functional group containing an oxygen atom or a nitrogen atom in the range of 0.1 meq / g to 10.0 meq / g on the surface of the carbon material, and cation exchange of the carbon material Forming a dispersion dispersed in a resin solution, removing the solvent from the dispersion to obtain a mixture of a carbon material and a cation exchange resin, and a fixed ion of the cation exchange resin with a catalyst metal A fourth step of adsorbing cations and a fifth step of chemically reducing the cations are characterized.

  The carbon material used for the polymer electrolyte fuel cell electrode of the present invention contains boron in the range of 0.1% by mass or more and 10% by mass or less. The carbon material containing boron of the present invention is a material in which a part of carbon atoms is substituted with boron atoms.

  Boron atoms have one fewer electron than carbon atoms. Since holes are formed when the boron is contained in the carbon material, the carbon material is positively charged. On the other hand, the proton conduction path of the cation exchange resin is negatively charged due to the presence of sulfonic acid groups and the like. By this negative charging, the proton conduction path of the cation exchange resin is electrically attracted to the surface of the carbon material containing boron, so that the affinity between the surface of the carbon material and the cation exchange resin is improved.

  The affinity between the surface of the carbon material and the cation exchange resin is further improved by the formation of functional groups containing oxygen atoms or nitrogen atoms in the carbon material containing boron. Due to this improvement in affinity, a more uniform cation exchange resin film is formed on the surface of the carbon material.

  As a result of the catalyst metal being uniformly supported on the surface of the carbon material, the activity of the catalyst metal of the ultra-small amount of catalyst metal-supported electrode is remarkably increased. Furthermore, since the thickness of the cation exchange resin coated on the surface of the carbon material is reduced, the diffusion distance of hydrogen or oxygen in the proton conduction path contained in the cation exchange resin is shortened. Remarkably improved. From the above, the output of PEFC using this electrode is remarkably improved.

  The electrode for a polymer electrolyte fuel cell of the present invention mainly supports a catalytic metal on the contact surface between the carbon material and the proton conduction path of the cation exchange resin, and the carbon material is 0.1% by mass or more and 10% by mass. It contains the following boron.

  The schematic diagram which shows the state of the surface layer of the carbon material which contacted the cation exchange resin of the ultra-small amount catalyst metal carrying | support electrode by this invention is shown in FIG. For comparison, FIG. 2 shows a conventional ultra-small catalyst metal-supported electrode. 1 and 2, 11 and 21 are carbon materials, 12 and 22 are cation exchange resins, 13 and 23 are proton conduction paths of the cation exchange resins, 14 and 24 are skeleton portions of the cation exchange resins, 15 and 25 is a catalyst metal involved in the electrode reaction.

  The carbon material 11 of FIG. 1 contains boron in the range of 0.1% by mass to 10% by mass. By containing boron in the carbon material, the affinity between the surface of the carbon material and the proton conduction path of the cation exchange resin is improved, so that the cation exchange resin 12 is uniformly attached to the surface. Therefore, the contact surface between the surface and the proton conduction path 13 increases.

  When boron contained in the carbon material is less than 0.1% by mass as in the past, the affinity between the surface of the material and the cation exchange resin is low, so the cation exchange resin is uniformly attached to the carbon material surface. I can't let you. As a result, the catalyst metal cannot be supported uniformly and highly dispersed. On the other hand, when the carbon material contains more than 10% by mass of boron, the higher-order structure of the material is damaged, and the electron conduction path is interrupted. As a result, the electron conduction in the electrode is lowered, so that the output of the polymer electrolyte fuel cell is lowered.

  By forming a functional group containing an oxygen atom or a nitrogen atom in a range of 0.1 meq / g or more and 10.0 meq / g or less in a carbon material containing boron in a range of 0.1 to 10% by mass, carbon Since the affinity between the surface of the material and the proton conduction path of the cation exchange resin is significantly improved, the contact surface between the surface of the carbon material and the cation exchange resin is further increased. As a result, the catalyst metal 15 is supported in a dispersed state over a wide range.

  When the amount of the functional group containing an oxygen atom or a nitrogen atom was less than 0.1 meq / g, the affinity between the carbon material and the cation exchange resin was not further improved. When the amount of the functional group is larger than 10.0 meq / g, the reason is not clear, but the electron conductivity in the electrode is lowered, so that the output of the polymer electrolyte fuel cell is lowered.

  The carbon material 11 is not particularly limited, and carbon black such as furnace black, acetylene black, lamp black, thermal black, and channel black can be used. The carbon material is preferably one exhibiting high activity for reduction of a compound containing a cation of a catalytic metal. For example, carbon black such as Denka Black, Vulcan XC-72, Ketjen Black EC, Black Pearl 2000, etc. is preferable. .

  The carbon material 11 contains boron in the range of 0.1% by mass to 10% by mass. Therefore, the surface of the carbon material containing boron is positively charged. This positive charging electrically attracts the surface of the carbon material and the proton conduction path of the negatively charged cation exchange resin, thereby improving the affinity between the surface of the carbon material and the cation exchange resin. By this improvement, the surface of the carbon material can be widely and uniformly coated with the cation exchange resin. That is, since the contact surface between the surface and the proton conduction path of the cation exchange resin is formed in a wide range, the catalyst metal is uniformly and highly dispersed.

  A method of measuring the amount of boron contained in the carbon material is not particularly limited, but a method of quantifying by ICP emission spectroscopy analysis (Inductively Coupled Plasma Emission Spectroscopy) is preferable. The method for qualifying boron contained in the carbon material is preferably obtained from the aforementioned ICP emission spectroscopic analysis or X-ray photoelectron spectroscopic analysis.

  Furthermore, the carbon material containing boron of the present invention in the range of 0.1 mass% or more and 10 mass% or less is a functional group containing oxygen atoms or nitrogen atoms in the range of 0.1 meq / g to 10.0 meq / g. Is preferably formed. For example, a functional group containing an oxygen atom such as a carbonyl group, a sulfonic acid group, or a hydroxyl group exhibits hydrophilicity and thus has high affinity with the proton conduction path of the cation exchange resin. By improving this affinity, the affinity between the carbon material surface and the cation exchange resin is further improved.

  For example, a functional group containing a nitrogen atom such as an amino group or an amide group is positively charged due to the presence of an unshared electron pair, so that the proton conduction pathway of the cation exchange resin that is negatively charged with the surface of the carbon material is Electrically attract each other. This charging further increases the affinity between the carbon material surface and the cation exchange resin.

  By this further increase in affinity, a functional group containing boron in the range of 0.1% by mass or more and 10% by mass or less and containing an oxygen atom or a nitrogen atom in the range of 0.1 meq / g or more and 10.0 meq / g or less. The cation exchange resin can be more widely and uniformly coated on the surface of the carbon material on which is formed. As a result, the catalyst metal can also be supported more uniformly and highly dispersed.

A method for quantifying the functional group containing an oxygen atom or a nitrogen atom is not particularly limited, but a method of quantifying using a temperature-programmed desorption gas analyzer is preferable. A method for quantifying a functional group by using a temperature-programmed desorption gas analyzer is, for example, as follows. First, the carbon material is heated with an infrared lamp in a vacuum of 1 × 10 ⁻⁷ Pa or less. Next, the functional group is quantified from the mass spectrum of the desorbed gas component. The method for qualifying the functional group is preferably obtained from the above-mentioned temperature programmed desorption gas analyzer or infrared absorption spectrum.

  As the cation exchange resin 12, a resin exhibiting proton conductivity can be used. For example, perfluorosulfonic acid resin or styrene-divinylbenzenesulfonic acid resin is preferable. A cation exchange group such as a sulfonic acid group is provided at the end of the side chain of the cation exchange resin.

  The proton conduction path 13 is formed by aggregation of a plurality of cation exchange groups together with water, and protons, oxygen, or hydrogen can move through the proton conduction path. Therefore, the catalytic metal present on the surface where the proton conduction path and the carbon material are in contact has high activity for the electrode reaction. The main chain parts are assembled by intermolecular forces to form the skeleton part 14. In this part, since proton, oxygen or hydrogen is difficult to move, the activity for the electrode reaction is low.

  In the catalyst layer of the polymer electrolyte fuel cell electrode of the present invention, "the catalytic metal is mainly provided on the contact surface between the proton conduction path of the cation exchange resin and the carbon material" means that the cation exchange resin It means that the amount of catalyst metal supported on the surface of carbon particles in contact with the proton conduction path is 50% by mass or more of the total amount of catalyst metal supported. That is, 50% by mass or more of the total catalytic metal loading is a catalytic metal active for the electrode reaction, so that the utilization rate of the catalytic metal is remarkably increased.

  In the present invention, the ratio of the amount of the catalyst metal supported on the surface of the carbon particles in contact with the proton conduction path of the cation exchange resin to the total amount of the catalyst metal supported is preferably as high as possible, particularly exceeding 80% by mass. preferable. In this way, the electrode is highly activated by supporting the catalytic metal at a high rate on the contact surface between the proton conduction path and the carbon particles.

  In the catalyst-supported powder of the present invention, the catalyst metal is mainly provided on the contact surface between the proton conduction path of the cation exchange resin and the carbon material, which is described in the literature (M. Komomoto et.al., GS Yuasa). As described in Technical Report, 1, 48 (2004)), it is judged from the mass activity in the high current density region of the polymer electrolyte fuel cell, the proton conduction path of the cation exchange resin, and the volume ratio of the hydrophobic skeleton. can do.

  Regarding the time-dependent change in the electrochemically active surface area of platinum, in the conventional electrode, the electrochemically active surface area of platinum decreases due to aggregation due to the dissolution / precipitation reaction of platinum, but the electrode using the catalyst-supported powder of the present invention Then almost no aggregation occurs.

  When the polymer electrolyte fuel cell is operated at a low current density, all platinum is used for the electrochemical reaction, but when it is operated at a high current density, it exists in the proton conduction path of the cation exchange resin. Only platinum is used for the electrochemical reaction, and platinum present in the hydrophobic skeleton part does not participate in the electrochemical reaction.

  In addition, the mass activity ratio of the electrode using the catalyst-supported powder of the present invention to the conventional electrode is approximately 1 in a high voltage region higher than 0.70 V during operation of the fuel cell, and 2. 7 On the other hand, in the cation exchange resin, the volume ratio of the proton conduction path in the polymer portion is about 2.5. Therefore, in the conventional electrode, in the high voltage region above 0.70 V, platinum in the proton conduction path of the cation exchange resin and platinum in the hydrophobic skeleton portion are active, but at 0.60 V, the cation exchange resin. It is clear that only platinum in the proton conduction pathway is active.

  The catalytic metal 15 is preferably a platinum group metal such as platinum, rhodium, ruthenium, iridium, palladium, and osnium because of its high catalytic activity for electrochemical oxygen reduction reaction and hydrogen oxidation reaction. In particular, an alloy containing platinum and ruthenium is preferable as an anode catalyst because high resistance to CO poisoning can be expected. Furthermore, an alloy containing at least one element selected from the group consisting of magnesium, aluminum, vanadium, chromium, manganese, iron, cobalt, nickel, copper, zinc, silver, or tungsten and a platinum group metal is used as the catalyst metal. Thus, a reduction in the amount of platinum group metal used, an improvement in CO poisoning resistance, and a high activity for oxygen reduction reaction can be expected.

The catalyst metal contained in the electrode of the present invention is in the form of particles having a particle size of 3.0 nm or less, particularly 0.5 nm to 2.0 nm, and the amount thereof is 0.1 mg / cm ² or less. A platinum group metal amount of 0.05 mg / cm ² or less is preferable because of high catalytic activity per unit weight.

  A method for evaluating the area of the interface between the carbon material surface and the cation exchange resin is as follows: 0.4 Vvs. A method of evaluating by electric double layer capacity in RHE is preferable. 0.4Vvs. In RHE, the reaction of the functional group on the surface of the carbon material has little influence on the current density. From this, 0.4Vvs. The current density at RHE is approximately proportional to the capacity of the electric double layer. Since its capacity is reported to be proportional to the area of the interface between the carbon material and the cation exchange resin, it is an index for comparing the areas (Jun Shiroma, Tsutomu Gozo, Naoko Fujiwara, Ikuo Nishimura, Kazu Yasuda). Akira, Takehiro Sasakura, Masashi Higashi, J. Highfield, Proceedings of the 7th Solid Polymer Fuel Cell Symposium, p. 93 (2000), Z. Miyazaki, J. Electronal. Chem., 546, 73 (2003)).

The measuring method is as follows, for example. First, a membrane / electrode assembly is manufactured by heat-pressing a catalytic metal unsupported electrode as a working electrode and a platinum supported electrode as a counter electrode to a cation exchange membrane. After producing a single cell using this membrane / electrode assembly, the potential of the working electrode was set to 0.05 Vvs. 1.00 V vs. RHE. The range up to RHE is scanned at 100 mV / s. At this time, N ₂ gas and H ₂ gas are humidified at 25 ° C. and supplied to the working electrode and the counter electrode, respectively.

The cyclic voltammogram obtained by this measurement has 0.4 Vvs. The electric double layer capacity is calculated by substituting the RHE current density into the equation (1). This value is normalized by dividing by the weight of the catalyst layer (working electrode). The symbols in the formula (1) are respectively C: electric double layer capacity (F / cm ² ), j _{0.4 V} : _{0.4 V} vs. Current density in RHE (A / cm ² ), v: sweep rate (V / s).

C = j _0.4V / v
The ultra-small catalyst metal-supported electrode used in the present invention supports a catalyst metal on a platinum-unsupported electrode in which a boron-containing carbon material and a mixture of a boron-containing carbon material and a cation exchange resin are formed in a sheet shape after the carbon material contains boron. Or after impregnating the carbon material with boron, the catalyst metal is supported on a platinum-unsupported powder obtained by pulverizing a mixture of a carbon material containing boron and a cation exchange resin, and the powder is formed into a sheet. It can be manufactured by the forming method. Each manufacturing method of the catalyst metal unsupported electrode and the catalyst metal unsupported powder will be described.

  In the present invention, a catalytic polymer is mainly supported on the contact surface between the carbon material and the proton conduction path of the cation exchange resin, and the carbon material contains 0.1% by mass to 10% by mass of boron. A method for producing an electrode for a fuel cell (this is referred to as “first production method”) includes a first step in which boron is contained in a carbon material in a range of 0.1 mass% to 10 mass%, and the carbon A second step of forming a dispersion in which the material is dispersed in a solution of the cation exchange resin, removing the solvent from the dispersion to obtain a mixture of the carbon material and the cation exchange resin, and fixing the cation exchange resin A third step of adsorbing the cation of the catalyst metal to the ions and a fourth step of chemically reducing the cation are characterized.

  Moreover, the functional group containing an oxygen atom or a nitrogen atom is in the range of 0.1 meq / g or more and 10.0 meq / g or less on the surface of the carbon material containing 0.1% by mass or more and 10% by mass or less of boron. The solid polymer fuel cell electrode manufacturing method (hereinafter referred to as “second manufacturing method”) provided in 1 is a first method in which boron is included in the carbon material in the range of 0.1 mass% to 10 mass%. A second step of forming a functional group containing an oxygen atom or a nitrogen atom in the range of 0.1 meq / g to 10.0 meq / g on the surface of the carbon material, and the carbon material as a cation. Forming a dispersion dispersed in a solution of the exchange resin, removing a solvent from the dispersion to obtain a mixture of a carbon material and a cation exchange resin; and a catalyst metal as a fixed ion of the cation exchange resin. The fourth method of adsorbing cations When, characterized in that through the fifth step of reducing the cations chemically.

  In the 1st process of the 1st manufacturing method of the present invention, and the 1st process of the 2nd manufacturing method, boron is included in carbon material in the range of 0.1 mass% or more and 10 mass% or less. The carbon material containing boron is manufactured by manufacturing a mixture of a carbon material and a boron compound and then heat-treating the mixture. As the boron compound used here, a boron compound, boron oxide, boron nitride, or the like that is easily contained in the carbon material after heat treatment can be used. These compounds may be used alone or in combination of two or more.

  The method for producing the mixture of the carbon material and the boron compound is not particularly limited, but a propeller type stirrer or the like that can be uniformly mixed is preferable. The heat treatment of the mixture of the carbon material and the boron compound is preferably held for 10 minutes or more in a non-oxidizing atmosphere and 2500 ° C. or higher. When the heating temperature is less than 2500 ° C. and the holding time is less than 10 minutes, it is not preferable because the carbon material does not contain boron. The furnace used for the heat treatment is not particularly limited, but a non-oxidizing atmosphere such as a high-frequency induction heating furnace or a graphitization furnace and a furnace that can be set to 2500 ° C. or higher are preferable.

  The non-oxidizing atmosphere can be obtained by replacing with an inert gas such as helium gas, nitrogen gas or argon gas. The inert gas used here may be used alone or in combination of two or more.

  In the second step of the second production method of the present invention, a functional group containing an oxygen atom or a nitrogen atom is added to the surface of the carbon material containing boron in a range of 0.1 meq / g or more and 10.0 meq / g or less. The method of forming is as follows, for example.

  A functional group containing an oxygen atom typified by a carbonyl group, a sulfonic acid group and a hydroxyl group is formed by oxidizing a carbon material containing boron. The method for oxidizing the carbon material is not particularly limited. For example, it is immersed in an acidic solution such as ozone water, sulfuric acid aqueous solution, hydrogen peroxide solution, nitric acid aqueous solution, oxalic acid aqueous solution, hydrochloric acid aqueous solution, acetic acid aqueous solution or potassium permanganate aqueous solution. A method of oxidizing by oxidizing, a method of oxidizing by contacting with an oxidizing gas such as oxygen gas or ozone gas, or a method of oxidizing by irradiating plasma can be used.

  Acidic aqueous solutions such as ozone water, sulfuric acid aqueous solution, hydrogen peroxide aqueous solution, nitric acid aqueous solution, oxalic acid aqueous solution, hydrochloric acid aqueous solution, acetic acid aqueous solution or potassium permanganate aqueous solution may be used alone or in combination.

  The concentration of the oxidizing agent aqueous solution is preferably 0.01 mol / l or more and 10 mol / l or less. When the concentration of the aqueous solution is less than 0.01 mol / l, the oxidation reaction on the surface of the carbon material containing boron is slow, so that it is difficult to provide hydrophilic functional groups. Conversely, when the concentration is higher than 10 mol / l, the oxidation reaction is remarkable. It is not preferable because the structure of the carbon material is destroyed by being fast.

  A method for separating the aqueous solution and the carbon material containing boron is not particularly limited, and a general centrifugal separator, a suction filter, or a pressure filter can be used. After oxidizing the material with an aqueous solution of an oxidizing agent, it is preferable to wash with deionized water. If not washed, an oxidizing agent is adhered to the carbon material containing boron, which may cause corrosion of the cation exchange resin or the polymer electrolyte fuel cell member.

  The oxidizing gas such as oxygen gas or ozone gas may be diluted with an inert gas such as nitrogen, argon or helium. The mixing ratio is preferably higher than the oxidizing gas / inert gas volume ratio of 1: 1. When the volume ratio of the oxidizing gas to the inert gas is less than 1: 1, the oxidation of the surface of the carbon material containing boron hardly progresses. The method of irradiating plasma is not particularly limited, but it is preferable to use a corona discharge treatment apparatus that discharges in air at normal temperature and pressure.

  A functional group containing a nitrogen atom such as an amide group or an amino group is formed by subjecting a carbon material containing boron to the following treatment. A method for treating the carbon material is not particularly limited. For example, a method for forming an amide group or an amino group is as follows.

  The amide group can be formed by, for example, forming a carbonyl group on a carbon material containing boron and then reacting the functional group with ammonia. The carbonyl group can be formed by the same oxidation method as described above.

  A method for reacting a carbonyl group with an amide group is as follows. From the carbonyl group to the amide group proceeds by an addition-elimination reaction between the carbonyl group and ammonia. For the reaction, a method of mixing a carbon material having a carbonyl group and an aqueous ammonia solution, or a method of bringing ammonia gas into contact with the material can be used.

The concentration of the aqueous ammonia solution should be 1.0 × 10 ⁻⁴ mol / l or more, and the aqueous solution should contain more ammonia than the amount of carbonyl groups formed in the carbon material containing boron. preferable. When the concentration is lower than this concentration, an amide group is hardly formed due to a slow addition-elimination reaction.

  The ammonia gas may be diluted with an inert gas such as nitrogen, argon or helium. As for the mixing ratio at that time, it is preferable that the ratio of the ammonia gas is larger than the volume ratio 1: 1 of the ammonia gas and the inert gas. In the case where the ratio of ammonia gas is smaller than 1: 1 by volume ratio of ammonia gas to inert gas, an amide group is hardly formed due to slow addition-elimination reaction.

  Amino group is formed by adding a nitro group to a carbon material containing boron and then reducing the functional group, or by introducing a halogen element into the material and then reacting with ammonia. Can be used.

  A method for forming an amino group from a nitro group is as follows. The nitro group can be formed, for example, by using a mixed solution of concentrated nitric acid and concentrated sulfuric acid or a method of nitration with concentrated nitric acid.

  The concentration of concentrated nitric acid and concentrated sulfuric acid or each concentration of concentrated nitric acid is preferably 5.0 mol / l or more. When the concentration is less than 5.0 mol / l, the nitration reaction on the surface of the carbon material containing boron is slow, so that it is difficult to provide a nitro group.

  Reduction from a nitro group to an amino group can be achieved, for example, by using a mixture of iron and hydrochloric acid. Instead of iron, one having high activity for the reduction reaction from a nitro group to an amino group, such as zinc or tin, can be used. These metals can be used alone or in combination.

The concentrations of the metal and hydrochloric acid contained in the mixed solution are 1.0 × 10 ⁻⁴ mol / l and 1.0 mol / l or more, respectively, and the amount thereof is that of the nitro group formed in the carbon material. A larger amount is preferred. When the concentration is lower than these concentrations, the amino group is hardly provided due to the slow reduction reaction. The metal used in this reaction can be removed by washing the catalyst metal unsupported electrode with an aqueous oxidizing agent such as sulfuric acid or nitric acid before the catalytic metal adsorption step described later.

  A method for forming an amino group by reacting with ammonia after introducing a halogen element is as follows. As a method of introducing the halogen element into the carbon material, for example, a method of mixing bromine water, hydrochloric acid or iodine water and a carbon material, or a method of bringing a carbon material into contact with bromine gas, chlorine gas or iodine gas can be used.

  When bromine water, hydrochloric acid or iodine water is used, the concentration is preferably 0.01 mol / l or more. When the concentration is less than 0.01 mol / l, it is not preferable because the halogen element is difficult to be introduced due to the slow halogenation reaction on the surface of the carbon material.

  When a halogen gas such as bromine gas, chlorine gas or iodine gas is used, it may be diluted with an inert gas such as argon or helium. The mixing ratio at that time is preferably higher in the proportion of the halogen gas than the volume ratio of 1: 1 of the halogen gas and the inert gas. When the ratio of the oxidizing gas is less than the volume ratio of 1: 1 of the halogen gas and the inert gas, the halogenation of the carbon material surface is difficult to proceed. When the halogen gas is brought into contact with the carbon material, heating or ultraviolet irradiation may be performed to promote the reaction.

As a method of substituting an amino group with a halogen element, for example, a method of mixing a carbon material into which a halogen element is introduced and an aqueous ammonia solution or a method of bringing ammonia gas into contact with the material can be used. The concentration of the aqueous ammonia solution is preferably 1.0 × 10 ⁻⁴ mol / l or more, and more preferably than the amount of halogen element introduced into the carbon material. If the concentration is lower than this concentration, the amino group is hardly provided due to the slow substitution reaction with the amino group. The ammonia gas may be diluted with an inert gas such as nitrogen, argon or helium.

  As for the mixing ratio at that time, it is preferable that the ratio of the ammonia gas is larger than the volume ratio 1: 1 of the ammonia gas and the inert gas. When the volume ratio of ammonia gas to inert gas is less than 1: 1, the introduction of amino groups on the carbon material surface is difficult to proceed.

  In the second step of the first production method and the third step of the second production method of the present invention, a dispersion in which a carbon material is dispersed in a solution of a cation exchange resin is formed, and from the dispersion The solvent is removed to obtain a mixture of the carbon material and the cation exchange resin. The mixture of the carbon material and the cation exchange resin is unsupported with a catalyst metal and has a shape of an electrode or powder.

  A specific method for producing the catalyst metal unsupported electrode is as follows. A carbon material and a cation exchange resin solution are mixed, and the mixture is applied to an electrode substrate to form a sheet, and finally, the sheet-like mixture is dried, whereby a catalyst metal unsupported electrode Form.

  The electrode substrate is not particularly limited, and a polymer sheet such as PTFE (Polytetrafluoroethylene) or PET (Polyethylene Terephthalate), or a metal sheet such as titanium can be used.

  A specific method for producing the catalyst metal unsupported powder is as follows. After mixing the carbon material and the solution of the cation exchange resin, the mixture is dried into a powder to produce a catalyst metal unsupported powder.

  The method of drying the mixture of the carbon material and the cation exchange resin solution into a powder form is a method of drying the mixture of the carbon material and the cation exchange resin solution into a sheet and then pulverizing the mixture, or spray drying the mixture. The method is preferred. The drying temperature is not particularly limited, but is preferably 50 ° C. or higher because the time for completely evaporating the solvent is short. On the other hand, it is not preferable that the temperature is 200 ° C. or higher because the cation exchange resin deteriorates.

  In the third step of the first production method and the fourth step of the second production method of the present invention, the catalyst metal is used as the fixed ion of the cation exchange resin in the catalyst metal unsupported electrode or the catalyst metal unsupported powder. The process of adsorbing the cation is as follows.

  First, it is washed with sulfuric acid in order to remove impurities contained in the electrode or powder. Next, by immersing the electrode or powder in a solution containing a cation of the catalytic metal, the cation of the catalytic metal is adsorbed on the proton conduction path of the cation exchange resin contained in the electrode or powder. The concentration of the cation of the catalyst metal in the solution is preferably 100 mmol / l or less in order to prevent physical adsorption to a portion that is not coated with the cation exchange resin, and this solution serves as a proton conduction path of the cation exchange resin. It is preferable that the catalyst metal ion is contained in the maximum molar amount or more that can be adsorbed. Although it does not specifically limit as a solvent used for the solution containing the cation of a catalyst metal, Water or the mixed solution of water and alcohol can be used.

  In the fourth step of the first production method and the fifth step of the second production method of the present invention, the catalyst metal cation adsorbed on the catalyst metal unsupported electrode or the catalyst metal unsupported powder is chemically treated. The process of reducing is as follows.

  In order to reduce the cation adsorbed on the proton conduction path of the cation exchange resin, it is preferable to use a chemical reduction method using a reducing agent suitable for mass production. In particular, a method of vapor phase reduction with hydrogen gas or a hydrogen mixed gas, or a method of gas phase reduction with an inert gas containing hydrazine is preferable. The reduction temperature is preferably 100 ° C. or higher and 250 ° C. or lower. When the temperature is lower than 100 ° C., the progress of the catalytic metal ion reduction reaction is extremely slow. On the other hand, when the temperature is higher than 250 ° C., the cation exchange resin is significantly deteriorated, which is not preferable.

  For example, a method for producing an ultra-small catalyst metal-supported electrode using an ultra-small catalyst metal-supported powder is as follows. First, a slurry-like mixture is produced by mixing an ultra-small amount of catalyst metal-supported powder and a solvent. Next, after applying this mixture to an electrode substrate, it is dried to form a sheet by removing the solvent.

  Solvents used when producing this slurry mixture are inorganic compounds such as water, hydrocarbon liquids such as hexane, pentane, cyclohexane, octane and benzene, dichloromethane, 1,1,2-trichloro-1,1, Use halogen compounds such as 2-trifluoroethane, alcohols such as methanol, ethanol, ethylene glycol and glycerol, ethers such as anisole, ketones such as acetone, and organic compounds such as N-methyl-2-pyrrolidone, pyridine and dimethyl sulfoxide. can do. The electrode substrate is not particularly limited, and a polymer sheet such as PTFE or PET, or a metal sheet such as titanium can be used.

  The electrode for a polymer electrolyte fuel cell of the present invention is formed by bonding an ultra-small amount of catalytic metal-supporting electrode to a cation exchange membrane. For the cation exchange membrane, for example, a proton conductive cation exchange resin such as a perfluorocarbon sulfonic acid resin, a styrene-vinylbenzene sulfonic acid resin, a perfluorocarbon carboxylic acid resin, or a styrene-vinylbenzene carboxylic acid resin may be used. However, it is preferable to use a perfluorocarbon sulfonic acid resin having high chemical stability and high proton conductivity. For example, a DuPont Nafion membrane can be used as the polymer electrolyte membrane.

  Joining of the cation exchange membrane with the ultra-small amount of catalytic metal-carrying electrode in which the catalytic metal is mainly supported on the contact surface between the proton conduction path of the cation exchange resin and the carbon surface can be performed by thermocompression bonding. . The heating temperature is preferably 90 ° C. to 160 ° C. close to the glass transition temperature of the cation exchange resin. A flat press or a roll press can be used for thermocompression bonding.

  Examples will be described in detail below.

[Examples 1 to 5]
[Example 1]
After boron was included in the carbon material (Vulcan XC-72, manufactured by Cabot), a catalyst metal unsupported electrode was manufactured. First, 20 g of a carbon material (Vulcan XC-72, manufactured by Cabot) and 0.1 g of boron carbide were mixed with a propeller-type stirrer for 1 hour. Next, this mixture was heated at 2700 ° C. for 1 hour in a high frequency dielectric heating furnace. At this time, the inside of the furnace was filled with argon gas. Finally, a carbon material containing boron was manufactured by cooling. When the carbon material was quantified by ICP emission spectroscopic analysis, it contained 0.10% by mass of boron.

  Next, a catalyst metal unsupported electrode using this carbon material was manufactured. First, 86.4 g of a Nafion solution (5 mass% solution, manufactured by Aldrich) was added to 8.0 g of a carbon material containing 0.10 mass% of boron, and the mixture was stirred to prepare a mixture. Next, this mixture was heated and concentrated at 60 ° C. while stirring with a propeller-type stirrer to prepare a slurry-like mixture. The mass ratio of the solid content of Nafion to this mixture was 6.5% by mass.

This slurry-like mixture was applied to a polymer sheet (PTFE, thickness 50 μm) and air-dried to produce the catalyst metal unsupported electrode A of Example 1 on the polymer sheet. Weight of the catalyst metal unsupported electrodes of 1 cm ² per at this time was 2.2 mg / cm ^2. For application, an applicator having a slit width of 300 μm was used. Finally, this electrode was cut into a size of 50 mm × 50 mm.

From the catalyst metal non-supported electrode A, an ultra-small amount of catalyst metal-supported electrode A of the present invention was produced by the following method. First, impurities were removed by washing the catalyst metal unsupported electrode A with a 0.5 mol / l sulfuric acid aqueous solution. Next, it is immersed in an aqueous solution (60 ° C.) of 50 mmol / l [Pt (NH ₃ ) ₄ ] Cl ₂ for 24 hours, and [Pt (NH ₃ ) ₄ ] ²⁺ is added to the proton conduction path of Nafion contained in the electrode. Adsorbed. Subsequently, this electrode was washed with deionized water at 25 ° C. three times and then immersed in deionized water at 60 ° C. for 1 hour.

Furthermore, this electrode was dried with a dryer at 60 ° C. for 1 hour. Finally, [Pt (NH ₃ ) ₄ ] ²⁺ adsorbed on the proton conduction path is reduced for 6 hours in a hydrogen atmosphere at 0.15 atm and 180 ° C., and a catalytic metal is formed on the contact surface between the carbon material and the proton conduction path. Was mainly deposited to produce an ultra-small amount of catalytic metal-supported electrode A (platinum supported amount 0.05 mg / cm ² ). This platinum loading was quantified separately by chemical analysis.

[Example 2]
20 g of carbon material (Vulcan XC-72) and 0.50 g of boron carbide were mixed to produce a carbon material containing 0.52% by mass of boron, and this carbon material was used in the same manner as in Example 1. The catalyst metal unsupported electrode B of Example 2 was manufactured. The weight of the catalyst metal unsupported electrode was 2.2 mg / cm ² . Using this catalyst metal unsupported electrode B, an ultra-small amount of catalyst metal supported electrode B was produced in the same manner as in Example 1. The amount of platinum supported on this electrode was determined by chemical analysis and found to be 0.05 mg / cm ² .

[Example 3]
20 g of carbon material (Vulcan XC-72) and 1.0 g of boron carbide were mixed to produce a carbon material containing 1.1% by mass of boron, and this carbon material was used in the same manner as in Example 1. Then, the catalyst metal unsupported electrode C of Example 3 was manufactured. The weight of the catalyst metal unsupported electrode was 2.2 mg / cm ² . Using this catalyst metal unsupported electrode C, an ultra-small amount of catalyst metal supported electrode C was produced in the same manner as in Example 1. The amount of platinum supported on this electrode was determined by chemical analysis and found to be 0.05 mg / cm ² .

[Example 4]
Carbon material (Vulcan XC-72) 20 g and boron carbide 5.0 g were mixed to produce a carbon material containing 5.1% by mass of boron, and this carbon material was used in the same manner as in Example 1. A catalyst metal unsupported electrode D of Example 4 was manufactured. The weight of the catalyst metal unsupported electrode was 2.2 mg / cm ² . Using this catalyst metal unsupported electrode D, an ultra-small amount of catalyst metal supported electrode D was produced in the same manner as in Example 1. The amount of platinum supported on this electrode was determined by chemical analysis and found to be 0.05 mg / cm ² .

[Example 5]
20 g of carbon material (Vulcan XC-72) and 10.0 g of boron carbide were mixed to produce a carbon material containing 10.0% by mass of boron, and this carbon material was used in the same manner as in Example 1. A catalyst metal unsupported electrode E of Example 5 was manufactured. The weight of the catalyst metal unsupported electrode was 2.2 mg / cm ² . Using this catalyst metal unsupported electrode E, an ultra-small amount of catalyst metal supported electrode E was produced in the same manner as in Example 1. The amount of platinum supported on this electrode was determined by chemical analysis and found to be 0.05 mg / cm ² .

[Examples 6 to 10]
[Example 6]
In the same manner as in Example 1, after 0.1% by mass of boron was contained in the carbon material (Vulcan XC-72), functional groups containing oxygen atoms were formed on the carbon material by the following method.

  First, 20 g of carbon material (Vulcan XC-72) containing 0.1% by mass of boron was collected in a 5 L beaker, and 10 ml of ethanol and 2 l of an oxidizing agent aqueous solution (sulfuric acid, 0.10 mol / l) were added thereto. The mixture of the carbon material, the aqueous oxidizing agent solution and ethanol was evacuated while stirring, and then stirred for 1 hour with a propeller-type stirrer.

  Next, this mixture was subjected to suction filtration to separate the carbon material and the oxidizing agent aqueous solution. After adding 2 l of deionized water to the carbon material and stirring for 10 minutes, the carbon material and deionized water were separated by suction filtration. This cleaning was repeated 5 times to clean the carbon material. Finally, the carbon material was vacuum-dried at 100 ° C. for 24 hours and then pulverized by a blender mill.

  When functional groups containing oxygen atoms present on the surface of the obtained carbon material were quantified with a temperature programmed desorption gas analyzer, carbonyl groups, sulfonic acid groups, hydroxyl groups, and the like were present in total of 0.10 meq / g. .

A catalyst metal unsupported electrode F of Example 6 was manufactured in the same manner as Example 1 except that this carbon material was used. The weight of the catalyst metal unsupported electrode was 2.2 mg / cm ² . Using this catalyst metal unsupported electrode F, an ultra-small amount of catalyst metal supported electrode F was produced in the same manner as in Example 1. The amount of platinum supported on this electrode was determined by chemical analysis and found to be 0.05 mg / cm ² .

[Example 7]
A functional group containing carbon material oxygen atoms was formed in the same manner as in Example 6 except that 0.50 mol / l sulfuric acid was used as the oxidizing agent aqueous solution. The functional group containing an oxygen atom present on the surface of the obtained carbon material was 0.49 meq / g. A catalyst metal unsupported electrode G of Example 7 was manufactured in the same manner as Example 6 except that this carbon material was used. The weight of the catalyst metal unsupported electrode was 2.2 mg / cm ² . Using this catalyst metal unsupported electrode G, an ultra-small amount of catalyst metal supported electrode G was produced in the same manner as in Example 6. The amount of platinum supported on this electrode was determined by chemical analysis and found to be 0.05 mg / cm ² .

[Example 8]
A functional group containing a carbon material oxygen atom was formed in the same manner as in Example 6 except that 1.5 mol / l sulfuric acid was used as the oxidizing agent aqueous solution. The functional group containing an oxygen atom present on the surface of the obtained carbon material was 1.2 meq / g. A catalyst metal unsupported electrode H of Example 8 was manufactured in the same manner as Example 6 except that this carbon material was used. The weight of the catalyst metal unsupported electrode was 2.2 mg / cm ² . Using this catalyst metal unsupported electrode H, an ultra-small amount of catalyst metal supported electrode H was produced in the same manner as in Example 6. The amount of platinum supported on this electrode was determined by chemical analysis and found to be 0.05 mg / cm ² .

[Example 9]
A functional group containing carbon material oxygen atoms was formed in the same manner as in Example 6 except that 5.0 mol / l sulfuric acid was used as the oxidizing agent aqueous solution. The functional group containing an oxygen atom present on the surface of the obtained carbon material was 4.9 meq / g. A catalyst metal unsupported electrode I of Example 9 was produced in the same manner as in Example 6 except that this carbon material was used. The weight of the catalyst metal unsupported electrode was 2.2 mg / cm ² . Using this catalyst metal unsupported electrode I, an ultra-small amount of catalyst metal supported electrode I was produced in the same manner as in Example 6. The amount of platinum supported on this electrode was determined by chemical analysis and found to be 0.05 mg / cm ² .

[Example 10]
Functional groups containing carbon material oxygen atoms were formed in the same manner as in Example 6 except that 10.0 mol / l sulfuric acid was used as the oxidizing agent aqueous solution. The functional group containing oxygen atoms present on the surface of the obtained carbon material was 10.0 meq / g. A catalyst metal unsupported electrode J of Example 10 was produced in the same manner as in Example 6 except that this carbon material was used. The weight of the catalyst metal unsupported electrode was 2.2 mg / cm ² . Using this catalyst metal unsupported electrode J, an ultra-small amount of catalyst metal supported electrode J was produced in the same manner as in Example 6. The amount of platinum supported on this electrode was determined by chemical analysis and found to be 0.05 mg / cm ² .

[Examples 11 to 15]
[Example 11]
In the same manner as in Example 1, after 0.1% by mass of boron was contained in the carbon material (Vulcan XC-72), functional groups containing nitrogen atoms were formed on the carbon material by the following method.

  First, 20 g of carbon material containing 0.1% by mass of boron (Vulcan XC-72) was collected in a 5 L beaker, and 10 ml of ethanol and 2 l of an oxidizing agent aqueous solution (hydrogen peroxide solution, 0.10 mol / l) were added thereto. It was. The mixture of the carbon material, the aqueous oxidizing agent solution and ethanol was evacuated while stirring, and then stirred for 1 hour with a propeller-type stirrer.

  Next, this mixture was subjected to suction filtration to separate the carbon material and the oxidizing agent aqueous solution. After adding 2 l of deionized water to this carbon material and stirring for 10 minutes, the carbon material and deionized water were separated by suction filtration. This cleaning was repeated 5 times to clean the carbon material. Finally, this carbon material was vacuum-dried at 100 ° C. for 24 hours.

  When the carbonyl group existing on the surface of the obtained carbon material was quantified by a temperature programmed desorption gas analyzer, it was found to be 0.14 meq / g.

  The addition-elimination reaction from the carbonyl group to the amide group was carried out by the following method. First, 20 g of a carbon material in which a carbonyl group was formed was collected in a 5 L beaker, and 10 ml of ethanol and 2 l of an aqueous ammonia solution (1.0 mol / l) were added thereto. The mixture of the carbon material, the aqueous oxidizing agent solution and ethanol was evacuated while stirring, and then stirred for 1 hour with a propeller-type stirrer.

  Next, this mixture was subjected to suction filtration to separate the carbon material and the aqueous ammonia solution. After adding 2 l of deionized water to this carbon material and stirring for 10 minutes, the carbon material and deionized water were separated by suction filtration. This cleaning was repeated 5 times to clean the carbon material, and this carbon material was vacuum dried at 100 ° C. for 24 hours.

  When functional groups containing nitrogen atoms present on the surface of the obtained carbon material were quantified with a temperature programmed desorption gas analyzer, amide groups and amino groups were present in total of 0.10 meq / g.

A catalyst metal unsupported electrode K of Example 11 was manufactured in the same manner as Example 1 except that this carbon material was used. The weight of the catalyst metal unsupported electrode was 2.2 mg / cm ² . Using this catalyst metal unsupported electrode K, an ultra-small amount of catalyst metal supported electrode K was produced in the same manner as in Example 11. The amount of platinum supported on this electrode was determined by chemical analysis and found to be 0.05 mg / cm ² .

[Example 12]
A functional group containing carbon material oxygen atoms was formed in the same manner as in Example 11 except that 0.2 mol / l hydrogen peroxide solution was used as the oxidizing agent aqueous solution. The functional group containing an oxygen atom present on the surface of the obtained carbon material was 0.48 meq / g. A catalyst metal unsupported electrode L of Example 12 was manufactured in the same manner as Example 11 except that this carbon material was used. The weight of the catalyst metal unsupported electrode was 2.2 mg / cm ² . Using this catalyst metal unsupported electrode L, an ultra-small amount of catalyst metal supported electrode L was produced in the same manner as in Example 11. The amount of platinum supported on this electrode was determined by chemical analysis and found to be 0.05 mg / cm ² .

[Example 13]
A functional group containing carbon material oxygen atoms was formed in the same manner as in Example 11 except that 0.5 mol / l hydrogen peroxide was used as the oxidizing agent aqueous solution. The functional group containing an oxygen atom present on the surface of the obtained carbon material was 1.2 meq / g. A catalyst metal unsupported electrode M of Example 13 was manufactured in the same manner as Example 11 except that this carbon material was used. The weight of the catalyst metal unsupported electrode was 2.2 mg / cm ² . Using this catalyst metal unsupported electrode M, an ultra-small amount of catalyst metal supported electrode M was produced in the same manner as in Example 11. The amount of platinum supported on this electrode was determined by chemical analysis and found to be 0.05 mg / cm ² .

[Example 14]
A functional group containing carbon material oxygen atoms was formed in the same manner as in Example 11 except that 1.5 mol / l hydrogen peroxide solution was used as the oxidizing agent aqueous solution. The functional group containing an oxygen atom present on the surface of the obtained carbon material was 5.1 meq / g. A catalyst metal unsupported electrode N of Example 14 was manufactured in the same manner as Example 11 except that this carbon material was used. The weight of the catalyst metal unsupported electrode was 2.2 mg / cm ² . Using this catalyst metal unsupported electrode N, an ultra-small amount of catalyst metal supported electrode N was produced in the same manner as in Example 11. The amount of platinum supported on this electrode was determined by chemical analysis and found to be 0.05 mg / cm ² .

[Example 15]
A functional group containing a carbon material oxygen atom was formed in the same manner as in Example 11 except that 5.0 mol / l of hydrogen peroxide was used as the oxidizing agent aqueous solution. The functional group containing oxygen atoms present on the surface of the obtained carbon material was 10.0 meq / g. A catalyst metal unsupported electrode O of Example 15 was manufactured in the same manner as Example 11 except that this carbon material was used. The weight of the catalyst metal unsupported electrode was 2.2 mg / cm ² . Using this catalyst metal unsupported electrode O, an ultra-small amount of catalyst metal supported electrode O was produced in the same manner as in Example 11. The amount of platinum supported on this electrode was determined by chemical analysis and found to be 0.05 mg / cm ² .

[Examples 16 to 18]
[Example 16]
A carbon material containing 0.1% by mass of boron was manufactured by the same manufacturing method as in Example 1. A catalyst metal unsupported powder using this carbon material was produced by the following procedure. First, 486.0 g of Nafion solution (5% by mass, manufactured by Aldrich) was added to 45.0 g of a carbon material containing boron, and the mixture was stirred to obtain a mixture.

  Next, this mixture was heated and concentrated at 60 ° C. while stirring with a propeller stirrer to form a slurry. The mass ratio of Nafion solids to the mixture after concentration was 6.5% by mass. This slurry-like mixture was applied onto a glass plate and air dried. The dried mixture was peeled from the glass plate and pulverized with a planetary ball mill to produce a catalyst metal unsupported powder. Finally, the powder was washed with 0.5 mol / l sulfuric acid to remove impurities.

An ultra-small amount of catalyst metal-supported powder was produced from this catalyst metal-unsupported powder by the following procedure. First, 25.0 g of catalyst metal unsupported powder and about 380 ml of an aqueous solution of 50 mmol / l [Pt (NH ₃ ) ₄ ] Cl ₂ were transferred to a 1 L beaker and stirred at room temperature using a propeller-type stirrer while reducing the pressure. did. Next, the pressure was returned to atmospheric pressure, and the mixture was stirred for 24 hours while maintaining the temperature at 80 ° C.

Subsequently, the aqueous solution of [Pt (NH ₃ ) ₄ ] Cl ₂ was removed by suction filtration, and this powder was washed with deionized water. This washing was repeated 5 times. Further, the powder was dried with a dryer at 60 ° C. for 1 hour. Finally, by reducing [Pt (NH ₃ ) ₄ ] ²⁺ adsorbed on the proton conduction path of the cation exchange resin in a hydrogen atmosphere at 0.15 MPa and 180 ° C. for 6 hours, the carbon material and the proton conduction path are reduced. Platinum as a catalyst metal was mainly deposited on the contact surface, and an ultra-small amount of catalyst metal-supported powder P of Example 16 was produced.

  An ultra-small amount of catalyst metal-supporting electrode P using this powder was manufactured by the following procedure. First, 4.0 g of ultra-small catalyst metal-supported powder P and 19.0 g of N-methyl-2-pyrrolidone (NMP) were mixed, and ultra-small catalyst metal-supported powder P was made into a slurry using a planetary ball mill.

Next, this slurry was applied onto a polymer sheet (PRFE, thickness 50 μm) and dried at 130 ° C. to produce an ultra-small amount of catalyst metal-supporting electrode P. For application, an applicator having a slit width of 300 μm was used. Finally, this electrode was cut into a size of 50 mm × 50 mm. Through the above steps, an ultra-small amount of catalytic metal-supported electrode P of Example 16 was manufactured. The amount of platinum supported on this electrode was 0.05 mg / cm ^{2 as} determined by chemical analysis.

[Example 17]
The ultra-small catalyst metal-supported electrode Q of Example 17 was manufactured in the same procedure as in Example 16. However, the carbon material of this electrode was formed by adding 0.1% by mass of boron in the same manner as in Example 1 and then forming 0.10 meq / g of functional groups containing oxygen atoms in the same manner as in Example 6. I let you. The amount of platinum supported on this electrode was 0.05 mg / cm ^{2 as} determined by chemical analysis.

[Example 18]
The ultra-small catalyst metal-supported electrode R of Example 18 was manufactured in the same procedure as in Example 16. However, the carbon material of this electrode was formed by adding 0.1% by mass of boron in the same manner as in Example 1 and then forming 0.10 meq / g of functional groups containing nitrogen atoms in the same manner as in Example 11. I let you. The amount of platinum supported on this electrode was 0.05 mg / cm ^{2 as} determined by chemical analysis.

[Comparative Examples 1-5]
[Comparative Example 1]
The catalyst metal unsupported electrode S and the ultra-small catalyst metal supported electrode S of Comparative Example 1 were manufactured in the same procedure as in Example 1. However, the carbon material of this electrode was not subjected to treatment to contain boron. Boron contained in this carbon material was quantified by ICP emission spectroscopic analysis and found to be 0.01% by mass. Further, this carbon material was not subjected to a treatment for forming a functional group containing an oxygen atom or a nitrogen atom. When functional groups containing oxygen atoms or nitrogen atoms present on the surface of the carbon material were quantified with a temperature programmed desorption gas analyzer, the amount of these functional groups was 0.01 meq / g. The amount of platinum supported on this electrode was 0.05 mg / cm ^{2 as} determined by chemical analysis.

[Comparative Example 2]
The ultra-small catalyst metal-supported electrode T of Comparative Example 2 was manufactured in the same procedure as in Example 16. However, the carbon material of this electrode was not subjected to treatment to contain boron. Boron contained in this carbon material was quantified by ICP emission spectroscopic analysis and found to be 0.01% by mass. Further, this carbon material was not subjected to a treatment for forming a functional group containing an oxygen atom or a nitrogen atom. When functional groups containing oxygen atoms or nitrogen atoms present on the surface of the carbon material were quantified with a temperature programmed desorption gas analyzer, the amount of these functional groups was 0.01 meq / g. The amount of platinum supported on this electrode was 0.05 mg / cm ^{2 as} determined by chemical analysis.

[Comparative Example 3]
The ultra-small catalyst metal-supported electrode U of Comparative Example 3 was manufactured in the same procedure as in Example 1. The carbon material used for the electrode contains 20% by mass of boron. This carbon material containing boron was obtained by mixing 20.0 g of boron carbide and 20.0 g of a carbon material and heating them. The amount of platinum supported on this electrode was 0.05 mg / cm ^{2 as} determined by chemical analysis.

[Comparative Example 4]
The ultra-small catalyst metal-supported electrode V of Comparative Example 4 was produced in the same procedure as in Example 1. After the carbon material of the electrode contained 0.1% by mass of boron, a functional group containing 20.0 meq / g oxygen atoms was formed. This functional group was formed by treatment with a 15.0 mol / l sulfuric acid aqueous solution. The amount of platinum supported on this electrode was 0.05 mg / cm ^{2 as} determined by chemical analysis.

[Comparative Example 5]
The ultra-small catalyst metal-supported electrode W of Comparative Example 5 was manufactured in the same procedure as in Example 1. After the carbon material of the electrode contained 0.1% by mass of boron, a functional group containing 20.0 meq / g of nitrogen atoms was formed. This functional group was formed by forming a carbonyl group with a 15.0 mol / l aqueous hydrogen peroxide solution and then treating with a 1.0 mol / l aqueous ammonia solution. The amount of platinum supported on this electrode was 0.05 mg / cm ^{2 as} determined by chemical analysis.

[Measurement of electric double layer capacity]
The electric double layer capacities of the catalyst metal unsupported electrodes A to E, S and U produced in Examples 1 to 5, Comparative Example 1 and Comparative Example 3 produce an electrochemical cell having these electrodes on the working electrode. Was measured.

  The membrane / electrode assembly used in this electrochemical cell is composed of an electrode made of catalyst metal unsupported electrodes A to E and S as working electrodes and platinum-supported carbon as a counter electrode, and a cation exchange membrane (Nafion 115, thickness 125 μm, Dupont Manufactured by heat pressure bonding on both sides. The heating condition is to keep the temperature of the press surface at 130 ° C. for 5 minutes.

  The counter electrode was manufactured as follows using platinum-supported carbon (TEC10E70TPM, manufactured by Tanaka Kikinzoku Co., Ltd.). First, 10.0 g of platinum-supported carbon powder was gradually added to a solution of 15 ml of deionized water and 1 ml of 2-propanol. Next, 44.2 g of Nafion solution (5 mass% solution, manufactured by Aldrich) and 15.0 g of N, N-dimethyl sulfoxide are added to a mixture of platinum-supported carbon powder and deionized water, and a propeller type stirrer is used. The mixture was stirred to prepare a mixture of platinum-supported carbon powder and Nafion solution.

This mixture was applied to a polymer sheet (PTFE, thickness 50 μm) and dried at 130 ° C. to produce an electrode (supported amount 0.5 mg / cm ² ) using platinum-supported carbon powder. An applicator with a slit width of 60 μm was used for coating. Finally, this electrode was cut into a size of 50 mm × 50 mm.

  Next, the electrochemical cell used in the measurement was manufactured by placing conductive porous carbon paper imparted with water repellency on each surface of the joined body and sandwiching it between a pair of gas flow plates. Using this cell, the cyclic voltammogram of the working electrode was measured with the electrode using platinum-supported carbon powder as the counter electrode, and the electric double layer capacity was calculated.

The measurement conditions are as follows. The sweep rate was 100 mV / s, and N ₂ gas was supplied to the working electrode side and H ₂ gas was supplied to the counter electrode side at a humidification temperature of 25 ° C. The 0.4 V vs. obtained by this measurement. The electric double layer capacity was calculated by dividing the current density at RHE by the sweep rate and the weight per cm ^{2 of the} catalyst metal unsupported electrode.

  FIG. 3 shows electric double layer capacities of the catalyst metal unsupported electrodes A to E, S, and U manufactured in Examples 1 to 5, Comparative Example 1 and Comparative Example 3. From FIG. 3, the electric double layer capacities of the catalyst metal unsupported electrodes A to E of Examples 1 to 5 are 104%, 113%, 121%, 117 compared with the case of the catalyst metal unsupported electrode S of Comparative Example 1. % And 100%, respectively.

  The electric double layer capacity is proportional to the area of the carbon material, the cation exchange resin, and the interface. Therefore, the area of the interface between the carbon material and the cation exchange resin of the catalyst metal unsupported electrodes A to E of Examples 1 to 5 is 104% and 113% as compared with the case of the catalyst metal unsupported electrode S of Comparative Example 1. , 121%, 117% and 100%, respectively. This improvement can be attributed to the fact that the surface of the material is uniformly and widely coated with the cation exchange resin by improving the affinity between the surface of the carbon material containing boron and the cation exchange resin.

  Furthermore, FIG. 3 shows that the electric double layer capacity of the catalyst metal unsupported electrode U of Comparative Example 3 was lower than that of the catalyst metal unsupported electrodes A to E of Examples 1 to 5. This decrease is considered to be caused by the damage of the carbon material by containing 20% by mass of boron in the carbon material. It is considered that the electric conduction layer in the electrode was interrupted by this damage, and the electric double layer capacity was lowered.

  FIG. 4 shows the electric double layer capacities of the catalyst metal unsupported electrodes F to J, S, and V manufactured in Examples 6 to 10, Comparative Example 1 and Comparative Example 4. From FIG. 4, the electric double layer capacities of the catalyst metal unsupported electrodes F to J of Examples 6 to 10 are 142%, 146%, 158%, 146 as compared with the case of the catalyst metal unsupported electrode S of Comparative Example 1. % And 129%, respectively.

  The electric double layer capacity is proportional to the area of the carbon material, the cation exchange resin, and the interface. Therefore, the area of the interface between the carbon material and the cation exchange resin of the catalyst metal unsupported electrodes F to J of Examples 6 to 10 is 142% and 146% as compared with the case of the catalyst metal unsupported electrode S of Comparative Example 1. 158%, 146% and 129%, respectively.

  This remarkable improvement is due to the fact that functional groups containing oxygen atoms are formed on the surface of the carbon material in addition to the inclusion of boron in the carbon material, thereby significantly improving the affinity between the surface of the material and the cation exchange resin. This is thought to be due to the fact that That is, it is considered that the cation exchange resin is uniformly and widely coated on the surface of the carbon material due to the improvement of the affinity.

  Furthermore, FIG. 4 shows that the electric double layer capacity of the catalyst metal unsupported electrode V of Comparative Example 4 was lower than that of the catalyst metal unsupported electrodes F to J of Examples 6 to 10. This decrease is considered to be caused by the destruction of the higher-order structure of the carbon material in the step of forming the functional group containing an oxygen atom. It is considered that the electric double layer capacity was lowered because the electron conduction path in the electrode was interrupted by this damage.

  FIG. 5 shows electric double layer capacities of the catalyst metal unsupported electrodes K to O and S manufactured in Examples 11 to 15, Comparative Example 1 and Comparative Example 5. From FIG. 5, the electric double layer capacities of the catalyst metal unsupported electrodes K to O of Examples 11 to 15 are 129%, 150%, 167%, and 146 as compared with the case of the catalyst metal unsupported electrode S of Comparative Example 1. % And 133%, respectively.

  The electric double layer capacity is proportional to the area of the carbon material, the cation exchange resin, and the interface. Therefore, the area of the interface between the carbon material and the cation exchange resin of the catalyst metal unsupported electrodes K to O of Examples 11 to 15 is 129% and 150% as compared with the case of the catalyst metal unsupported electrode S of Comparative Example 1. , 167%, 146% and 133%, respectively.

  This remarkable improvement is that the affinity between the carbon material surface and the cation exchange resin has been significantly improved by the formation of functional groups containing nitrogen atoms on the carbon material surface in addition to the inclusion of boron in the carbon material. This is thought to be caused by this. In other words, it is considered that the cation exchange resin is uniformly and widely coated on the surface due to the improved affinity.

  Furthermore, FIG. 5 shows that the electric double layer capacity of the catalyst metal unsupported electrode W of Comparative Example 5 was lower than that of the catalyst metal unsupported electrodes K to O of Examples 11 to 15. This decrease is considered to be due to the destruction of the higher-order structure of the carbon material in the step of forming the functional group containing a nitrogen atom. It is considered that the electric double layer capacity was lowered because the electron conduction path in the electrode was interrupted by this damage.

[Measurement of cell performance]
Membrane / electrode assemblies using the ultra-small catalyst metal-supported electrodes A to J, P, and S to U manufactured in Examples 1 to 10, Example 16, and Comparative Examples 1 to 3 were manufactured, and this assembly was provided. The performance of the polymer electrolyte fuel cell was investigated. The membrane / electrode assembly was manufactured by thermocompression bonding an ultra-small amount of catalytic metal-supporting electrode on both the cathode side and the anode side to both sides of a cation exchange membrane (Nafion 115, thickness 125 μm, manufactured by DuPont). The heating condition is a press surface temperature of 130 ° C. for 5 minutes.

  The polymer electrolyte fuel cell used in the measurement was manufactured by placing conductive porous carbon paper with water repellency on each surface of the membrane / electrode assembly and sandwiching it between a pair of gas flow plates. . The polymer electrolyte fuel cells provided with the ultra-small catalyst metal-supported electrodes A to J and S to U were designated as polymer electrolyte fuel cells A to J and S to U, respectively.

The performance of these polymer electrolyte fuel cells was evaluated by comparing cell voltages at a current-voltage characteristic of 300 mA / cm ² . The measurement conditions were a cell temperature of 70 ° C., an anode gas of pure hydrogen, an anode utilization factor of 70%, an anode humidification temperature of 70 ° C., a cathode gas of air, a cathode utilization factor of 40%, and a cathode humidification temperature of 70 ° C.

FIG. 6 shows the cell voltage at 300 mA / cm ² of the polymer electrolyte fuel cells using the ultra-small catalyst metal-supported electrodes manufactured in Examples 1 to 5, Comparative Example 1 and Comparative Example 3. From FIG. 6, compared with the polymer electrolyte fuel cell S provided with the electrode of the comparative example 1, the polymer electrolyte fuel cell AE provided with the ultra-small catalyst metal carrying electrode manufactured in Examples 1-5 is compared with They improved by 37 mV, 41 mV, 46 mV, 42 mV and 35 mV, respectively.

  On the other hand, the cell performance of the polymer electrolyte fuel cell U provided with the ultra-small catalyst metal-supported electrode U manufactured in Comparative Example 3 was 589 mV, which was lower than those in Examples 1-5. Further, the cell performance of the polymer electrolyte fuel cell P provided with the ultra-small catalyst metal-supported electrode P manufactured in Example 16 is 631 mV, and the solid polymer provided with the ultra-small catalyst metal-supported electrode T of Comparative Example 2 is used. Compared to the case of the fuel cell T, it was improved by 39 mV.

The relationship between the double layer capacity | capacitance of the catalyst metal unsupported electrode produced in Examples 1-5, the comparative example 1, and the comparative example 3, and the cell voltage in 300 mA / cm < ² > of a polymer electrolyte fuel cell using the same is a figure. 7 shows. FIG. 7 shows that the performance of the polymer electrolyte fuel cells of Examples 1 to 5 having an ultra-small amount of catalyst metal-supported electrode manufactured from a catalyst metal-unsupported electrode having a large double-layer capacity is as follows. It was found that the performance was improved as compared with the polymer electrolyte fuel cells of Comparative Example 1 and Comparative Example 3 equipped with an ultra-small amount of catalytic metal-supported electrode manufactured from the supported electrode.

  The improvement in the cell performance of the polymer electrolyte fuel cell comprising the ultra-small amount of catalytic metal-supported electrode produced in Examples 1 to 5 is that the surface of the carbon material is coated with a wide and uniform cation exchange resin. It is thought to be caused by That is, the catalytic metal supported on the proton conduction path of the cation exchange resin is small and highly dispersed, thereby improving the activity of the catalytic metal, and reducing the thickness of the cation exchange resin coated on the carbon material. This is thought to be because the progress of the electrode reaction was promoted by shortening the diffusion distance of hydrogen or oxygen in the proton conduction path.

  The fact that the cell performance of the polymer electrolyte fuel cell provided with the ultra-small amount of catalytic metal-supported electrode produced in Comparative Example 3 showed a lower value than that of Examples 1 to 5 indicates that the carbon material contains a large amount of boron. This is considered to be caused by the damage of the structure of the material. It is thought that the performance of the polymer electrolyte fuel cell was lowered because the electron conduction path in the electrode was interrupted due to the damage.

FIG. 8 shows the cell voltage at 300 mA / cm ² of the polymer electrolyte fuel cells using the ultra-small catalyst metal-supported electrodes produced in Examples 6 to 10, Example 17, Comparative Example 1, Comparative Example 2 and Comparative Example 4. Shown in From FIG. 8, the polymer electrolyte fuel cells F to J having the ultra-small catalyst metal-supported electrodes manufactured in Examples 6 to 10 are respectively compared with the polymer electrolyte fuel cell S having the electrode of Comparative Example 1. Improved 53 mV, 57 mV, 71 mV, 60 mV and 50 mV.

  Further, the cell performance of the polymer electrolyte fuel cell Q provided with the ultra-small catalyst metal-supported electrode Q manufactured in Example 17 is 645 mV, and the solid polymer provided with the ultra-small catalyst metal-supported electrode T of Comparative Example 2 is used. Compared to the case of the fuel cell T, it was improved by 53 mV. On the other hand, the cell performance of the polymer electrolyte fuel cell V provided with the ultra-small amount of catalytic metal-carrying electricity V manufactured in Comparative Example 4 was 589 mV, which was lower than those in Examples 6 to 10.

The relationship between the double layer capacity of the catalyst metal unsupported electrode manufactured in Examples 6 to 10 and Comparative Examples 1 and 4 and the cell voltage at 300 mA / cm ² of the polymer electrolyte fuel cell using the same is shown. 9 shows. From FIG. 9, the performance of the polymer electrolyte fuel cells of Examples 6 to 10 having the ultra-small amount of catalyst metal-supported electrode manufactured from the catalyst metal unsupported electrode having a large double layer capacity is as follows. It was found that the performance was improved as compared with the polymer electrolyte fuel cells of Comparative Example 1 and Comparative Example 4 provided with an ultra-small amount of catalytic metal supported electrode manufactured from the supported electrode.

  The improvement in the cell performance of the polymer electrolyte fuel cell provided with the ultra-small catalyst metal-supported electrode produced in Examples 6 to 10 was obtained by forming a functional group containing an oxygen atom in a carbon material containing boron. This is considered to be due to the fact that the surface of the material is widely and uniformly coated with the cation exchange resin.

  That is, the catalytic metal supported on the proton conduction path of the cation exchange resin is small and highly dispersed, thereby improving the activity of the catalytic metal, and reducing the thickness of the cation exchange resin coated on the carbon material. This is thought to be because the progress of the electrode reaction was promoted by shortening the diffusion distance of hydrogen atoms or oxygen atoms in the proton conduction path.

  The cell performance of the polymer electrolyte fuel cell provided with the ultra-small amount of catalytic metal-supported electrode produced in Comparative Example 4 showed a lower value than that of Examples 6 to 10 because the carbon material contained oxygen atoms. This is considered to be due to the destruction of the higher-order structure of the material when forming the group. It is considered that the performance of the polymer electrolyte fuel cell was lowered because the electron conduction path in the electrode was interrupted by this damage.

FIG. 10 shows the cell voltage at 300 mA / cm ² of the polymer electrolyte fuel cells using the ultra-small catalyst metal-supported electrodes produced in Examples 11 to 15, Example 18, Comparative Example 1, Comparative Example 2 and Comparative Example 5. Shown in From FIG. 10, the polymer electrolyte fuel cells K to O having the ultra-small catalyst metal-supported electrodes manufactured in Examples 11 to 15 were respectively compared with the polymer electrolyte fuel cell S having the electrode of Comparative Example 1. 57 mV, 60 mV, 72 mV, 59 mV and 55 mV were improved.

  Further, the cell performance of the polymer electrolyte fuel cell R having the ultra-small catalyst metal-supporting electrode R manufactured in Example 18 is 649 mV, and the solid polymer having the ultra-small catalyst metal-supporting electrode T of Comparative Example 2 is used. Compared with the fuel cell T, the fuel cell was improved by 57 mV. On the other hand, the cell performance of the polymer electrolyte fuel cell W provided with the ultra-small amount of catalyst metal-carrying electricity W manufactured in Comparative Example 5 was 592 mV, which was lower than that in Examples 11-15.

The relationship between the double layer capacity of the ultra-small catalyst metal-supported electrode produced in Examples 11 to 15 and Comparative Examples 1 and 5 and the cell voltage at 300 mA / cm ² of the polymer electrolyte fuel cell using the same. As shown in FIG. From FIG. 11, the performance of the polymer electrolyte fuel cells of Examples 11 to 15 having the ultra-small amount of catalyst metal-supported electrode manufactured from the catalyst metal unsupported electrode having a large double layer capacity is as follows. It was found that the performance was improved as compared with the polymer electrolyte fuel cells of Comparative Example 1 and Comparative Example 5 provided with an ultra-small amount of catalytic metal supported electrode manufactured from the supported electrode.

  The improvement in the cell performance of the polymer electrolyte fuel cell provided with the ultra-small catalyst metal-supported electrode produced in Examples 11 to 15 was obtained by forming a functional group containing an oxygen atom in a carbon material containing boron. This is considered to be due to the fact that the surface of the material was widely and uniformly coated with the cation exchange resin. That is, the catalytic metal supported on the proton conduction path of the cation exchange resin is small and highly dispersed, thereby improving the activity of the catalytic metal, and reducing the thickness of the cation exchange resin coated on the carbon material. This is thought to be because the progress of the electrode reaction was promoted by shortening the diffusion distance of hydrogen atoms or oxygen atoms in the proton conduction path.

  The cell performance of the polymer electrolyte fuel cell having an ultra-small amount of catalytic metal-supported electrode produced in Comparative Example 5 showed a lower value than that of Examples 11 to 15 because the carbon material contained a nitrogen atom. This is considered to be due to the destruction of the higher-order structure of the material when forming the group. It is considered that the performance of the polymer electrolyte fuel cell was deteriorated because the electron conduction path in the electrode was interrupted by the damage.

  From the above results, it was found that the performance of the polymer electrolyte fuel cell is improved by using the electrode for the polymer electrolyte fuel cell produced by the production method of the present invention.

The schematic diagram which shows the state of the surface layer of the carbon material which contacted the cation exchange resin of the catalyst used for the ultra-small amount catalyst metal carrying | support electrode by this invention. The schematic diagram which shows the state of the surface layer of the carbon material which contacted the cation exchange resin of the catalyst used for the conventional ultra-small catalyst metal carrying | support electrode. The figure which compared the electric double layer capacity | capacitance of the catalyst metal unsupported electrode manufactured in Examples 1-5, the comparative example 1, and the comparative example 3. FIG. The figure which compared the electric double layer capacity | capacitance of the catalyst metal unsupported electrode manufactured in Examples 6-10, the comparative example 1, and the comparative example 4. FIG. The figure which compared the electric double layer capacity | capacitance of the catalyst metal unsupported electrode manufactured in Examples 11-15, the comparative example 1, and the comparative example 5. FIG. The figure which compared the cell voltage in 300 mA / cm < ² > of the polymer electrolyte fuel cell using the ultra-small amount catalyst metal carrying | support electrode manufactured in Examples 1-5, the comparative example 1, and the comparative example 3. FIG. The relationship between the double layer capacity | capacitance of the catalyst metal unsupported electrode produced in Examples 1-5, the comparative example 1, and the comparative example 3 and the cell voltage in 300 mA / cm < ² > of a polymer electrolyte fuel cell using the same is shown. Figure. The cell voltages at 300 mA / cm ² of the polymer electrolyte fuel cells using the ultra-small catalyst metal-supported electrodes produced in Examples 6 to 10, Example 17, Comparative Example 1, Comparative Example 2 and Comparative Example 4 were compared. Figure. The relationship between the double layer capacity | capacitance of the catalyst metal unsupported electrode produced in Examples 6-10, the comparative example 1, and the comparative example 4 and the cell voltage in 300 mA / cm < ² > of a polymer electrolyte fuel cell using the same is shown. Figure. The cell voltages at 300 mA / cm ² of the polymer electrolyte fuel cells using the ultra-small catalyst metal-supported electrodes produced in Examples 11 to 15, Example 18, Comparative Example 1, Comparative Example 2 and Comparative Example 5 were compared. Figure. The relationship between the double layer capacity of the ultra-small catalyst metal-supported electrode produced in Examples 11 to 15 and Comparative Examples 1 and 5 and the cell voltage at 300 mA / cm ² of the polymer electrolyte fuel cell using the same. The figure shown.

Explanation of symbols

11, 21 Carbon material 12, 22 Cation exchange resin 13, 23 Proton conduction path of cation exchange resin 14, 24 Skeletal portion of cation exchange resin 15, 25 Catalytic metal involved in electrochemical reaction

Claims (4)

A solid polymer characterized in that a catalytic metal is mainly supported on a contact surface between a carbon material and a proton conduction path of a cation exchange resin, and the carbon material contains 0.1% by mass or more and 10% by mass or less of boron. Type fuel cell electrode. 2. The polymer electrolyte fuel cell according to claim 1, wherein a functional group containing an oxygen atom or a nitrogen atom is provided on the surface of the carbon material in a range of 0.1 meq / g to 10.0 meq / g. Electrode. A first step of containing boron in a range of 0.1% by mass to 10% by mass in the carbon material, and forming a dispersion in which the carbon material is dispersed in a cation exchange resin solution; A second step of obtaining a mixture of the carbon material and the cation exchange resin, a third step of adsorbing the cation of the catalytic metal to the fixed ion of the cation exchange resin, and the cation chemically The method for producing an electrode for a polymer electrolyte fuel cell according to claim 1, wherein a fourth step of reducing the polymer is performed. A first step in which boron is contained in the carbon material in a range of 0.1% by mass or more and 10% by mass or less; and a functional group containing an oxygen atom or a nitrogen atom on the surface of the carbon material at 0.1 meq / g or more and 10 A second step of forming within a range of 0.0 meq / g or less, and forming a dispersion in which the carbon material is dispersed in a solution of a cation exchange resin, and removing the solvent from the dispersion to exchange the cation with the carbon material. A third step of obtaining a resin mixture, a fourth step of adsorbing the cation of the catalytic metal on the fixed ions of the cation exchange resin, and a fifth step of chemically reducing the cation. The method for producing an electrode for a polymer electrolyte fuel cell according to claim 2.

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