Abstract: Provided are an oxygen reduction catalyst having a high electrode potential under a fuel cell operating environment, an electrode containing the oxygen reduction catalyst, a membrane electrode assembly in which a cathode is the electrode, and a fuel cell including the membrane electrode assembly. The oxygen reduction catalyst used here contains cobalt, sulfur, and oxygen as elements, has a CoS2 cubic structure in powder X-ray diffractometry, and having an S—Co/S—O peak area ratio of 6 to 15 in an S2p spectrum in X-ray photoelectron spectroscopic analysis.

Abstract: An object of the invention is to provide an oxygen reduction catalyst composed of a titanium oxynitride having high oxygen reduction capacity. The oxygen reduction catalyst of the invention is a titanium oxynitride that has a nitrogen element content of 8.0 to 15 mass %, has a crystal structure of anatase titanium dioxide in a powder X-ray diffraction measurement, and has a signal intensity ratio N—Ti—N/O—Ti—N in an X-ray photoelectron spectroscopic analysis of in the range of 0.35 to 0.70.

Abstract: The present invention relates to an oxygen reduction catalyst, an electrode, a membrane electrode assembly, and a fuel cell, and the oxygen reduction catalyst is an oxygen reduction catalyst containing substituted CoS2, in which the substituted CoS2 has a cubic crystal structure, the oxygen reduction catalyst contains the substituted CoS2 within 0.83 nm from the surface thereof, and the substituted CoS2 has at least one substitutional atom selected from the group consisting of Cr, Mo, Mn, Tc, Re, Rh, Cu, and Ag in some of Co atom sites.

Abstract: A catalyst carrier, an electrode catalyst, an electrode including the catalyst, a membrane electrode assembly including the electrode, a fuel cell including the membrane electrode assembly, and a method for producing the catalyst carrier. The catalyst carrier includes a carbon material having a chain structure including a chain of carbon particles. The catalyst carrier contains a titanium compound-carbon composite particle in which carbon encloses a titanium compound particle. The molar ratios of a carbon element, a nitrogen element, and an oxygen element to a titanium element taken as 1 in the catalyst carrier are more than 0 and 50 or less, more than 0 and 2 or less, and more than 0 and 3 or less, respectively.

Abstract: Provided is a process for producing a fuel cell electrode catalyst with high catalytic activity that is alternative to a noble metal catalyst, through a heat treatment at a relatively low temperature. A process for producing a fuel cell electrode catalyst includes a step (I) of obtaining a catalyst precursor, including a step (Ia) of mixing at least a metal compound (1), a nitrogen-containing organic compound (2), and a fluorine-containing compound (3), and a step (II) of heat-treating the catalyst precursor at a temperature of 500 to 1300° C. to obtain an electrode catalyst, a portion or the entirety of the metal compound (1) being a compound containing an atom of a metal element M1 selected from the group consisting of iron, cobalt, chromium, nickel, copper, zinc, titanium, niobium and zirconium, and at least one of the compounds (1), (2) and (3) containing an oxygen atom.

Abstract: A method for producing a fuel cell electrode catalyst, including a step (I) of bringing an aqueous solution of a transition metal compound (1) into contact with ammonia and/or ammonia water to generate a precipitate (A) containing an atom of the transition metal, a step (II) of mixing at least the precipitate (A), an organic compound (B), and a liquid medium (C) to obtain a catalyst precursor liquid, and a step (IV) of subjecting the solid in the catalyst precursor liquid to heat treatment at a temperature of 500 to 1200° C. to obtain an electrode catalyst; a portion or the entirety of the transition metal compound (1) being a compound containing a transition metal element of group 4 or group 5 of the periodic table; and the organic compound (B) being at least one selected from sugars and the like.

Abstract: A catalyst carrier, an electrode catalyst, an electrode including the catalyst, a membrane electrode assembly including the electrode, and a fuel cell including the membrane electrode assembly. The catalyst carrier includes a carbon material having a chain structure including a chain of carbon particles, and an oxide-carbon composite particle in which a carbon particle encloses a particle of an oxide of a group IV element on the periodic table, the oxide-carbon composite particle being contained in the carbon material. The catalyst carrier has a BET specific surface area of 450 to 1100 m2/g.

Abstract: A catalyst carrier, an electrode catalyst, an electrode including the catalyst, a membrane electrode assembly including the electrode, and a fuel cell including the membrane electrode assembly. The catalyst carrier includes a carbon material having a chain structure including a chain of carbon particles and an alumina-carbon composite particle in which a carbon particle encloses an alumina particle, the alumina-carbon composite particle is contained in the carbon material, and the catalyst carrier has a BET specific surface area of 450 to 1100 m2/g.

Abstract: A method is provided for producing a platinum alloy-containing fuel cell electrode catalyst with high activity which is suited for its industrial mass-production. The method for producing a fuel cell electrode catalyst includes a step of preparing a dispersion in which particles of a fuel cell electrode catalyst precursor including a platinum alloy is dispersed in an electrolyte solution, and a step of alternately subjecting the dispersion to bubbling with an oxidizing gas and to bubbling with an inert gas or a reducing gas.

Abstract: A catalyst carrier, an electrode catalyst, an electrode including the catalyst, a membrane electrode assembly including the electrode, and a fuel cell including the membrane electrode assembly. The catalyst carrier includes a carbon material having a chain structure including a chain of carbon particles and an alumina-carbon composite particle in which a carbon particle encloses an alumina particle, the alumina-carbon composite particle is contained in the carbon material, and the catalyst carrier has a BET specific surface area of 450 to 1100 m2/g.

Abstract: A catalyst carrier, an electrode catalyst, an electrode including the catalyst, a membrane electrode assembly including the electrode, a fuel cell including the membrane electrode assembly, and a method for producing the catalyst carrier. The catalyst carrier includes a carbon material having a chain structure including a chain of carbon particles. The catalyst carrier contains a titanium compound-carbon composite particle in which carbon encloses a titanium compound particle. The molar ratios of a carbon element, a nitrogen element, and an oxygen element to a titanium element taken as 1 in the catalyst carrier are more than 0 and 50 or less, more than 0 and 2 or less, and more than 0 and 3 or less, respectively.

Abstract: A catalyst carrier, an electrode catalyst, an electrode including the catalyst, a membrane electrode assembly including the electrode, and a fuel cell including the membrane electrode assembly. The catalyst carrier includes a carbon material having a chain structure including a chain of carbon particles, and an oxide-carbon composite particle in which a carbon particle encloses a particle of an oxide of a group IV element on the periodic table, the oxide-carbon composite particle being contained in the carbon material. The catalyst carrier has a BET specific surface area of 450 to 1100 m2/g.

Abstract: A catalyst carrier production process includes a step (a) of mixing a transition metal compound (1), a nitrogen-containing organic compound (2), and a solvent to provide a catalyst carrier precursor solution; a step (b) of removing the solvent from the catalyst carrier precursor solution; and a step (c) of thermally treating a solid residue obtained in the step (b) at a temperature of 500 to 1100° C. to provide a catalyst carrier; wherein the transition metal compound (1) is partly or wholly a compound including a transition metal element (M1) selected from the group 4 and 5 elements of the periodic table as a transition metal element; and at least one of the transition metal compound (1) and the nitrogen-containing organic compound (2) includes an oxygen atom.

Abstract: A method is provided for producing a platinum alloy-containing fuel cell electrode catalyst with high activity which is suited for its industrial mass-production. The method for producing a fuel cell electrode catalyst includes a step of preparing a dispersion in which particles of a fuel cell electrode catalyst precursor including a platinum alloy is dispersed in an electrolyte solution, and a step of alternately subjecting the dispersion to bubbling with an oxidizing gas and to bubbling with an inert gas or a reducing gas.

Abstract: A membrane electrode assembly which includes an anode, a cathode and a solid polymer electrolyte membrane that are specifically arranged, wherein the cathode has a cathode catalyst layer and a cathode diffusion layer that is arranged on a surface of the cathode catalyst layer, the surface being on the side opposite the solid polymer electrolyte membrane side, the cathode catalyst layer contains an oxygen reduction catalyst composed of composite particles each of which is constituted of a catalyst metal containing palladium or a palladium alloy and a catalyst carrier containing, as constituent elements, a specific transition metal element M1, a transition metal element M2 other than the transition metal element M1, carbon, nitrogen and oxygen in a specific ratio, and the cathode diffusion layer contains an oxidation catalyst and a water-repellent resin.

Abstract: A catalyst carrier production process includes a step (a) of mixing a transition metal compound (1), a nitrogen-containing organic compound (2), and a solvent to provide a catalyst carrier precursor solution; a step (b) of removing the solvent from the catalyst carrier precursor solution; and a step (c) of thermally treating a solid residue obtained in the step (b) at a temperature of 500 to 1100° C. to provide a catalyst carrier; wherein the transition metal compound (1) is partly or wholly a compound including a transition metal element (M1) selected from the group 4 and 5 elements of the periodic table as a transition metal element; and at least one of the transition metal compound (1) and the nitrogen-containing organic compound (2) includes an oxygen atom.

Abstract: In a direct-liquid fuel cell supplied directly with a liquid fuel, a process for producing an electrode catalyst for a direct-liquid fuel cell is provided which is capable of suppressing decrease in cathode potential caused by liquid fuel crossover and providing an inexpensive and high-performance electrode catalyst for a direct-liquid fuel cell. The process for producing an electrode catalyst for a direct-liquid fuel cell includes Step A of mixing at least a transition metal-containing compound with a nitrogen-containing organic compound to obtain a catalyst precursor composition, and Step C of heat-treating the catalyst precursor composition at a temperature of from 500 to 1100° C. to obtain an electrode catalyst, wherein part or entirety of the transition metal-containing compound includes, as a transition metal element, at least one transition metal element M1 selected from Group IV and Group V elements of the periodic table.

Abstract: A method for producing a fuel cell electrode catalyst including a metal element selected from aluminum, chromium, manganese, iron, cobalt, nickel, copper, strontium, yttrium, tin, tungsten, and cerium and having high catalytic activity through heat treatment at comparatively low temperature. The method including: a step (1) of mixing at least a certain metal compound (1), a nitrogen-containing organic compound (2), and a solvent to obtain a catalyst precursor solution, a step (2) of removing the solvent from the catalyst precursor solution, and a step (3) of heat-treating a solid residue, obtained in the step (2), at a temperature of 500 to 1100° C. to obtain an electrode catalyst; a portion or the entirety of the metal compound (1) being a compound containing, as the metal element, a metal element M1 selected from aluminum, chromium, manganese, iron, cobalt, nickel, copper, strontium, yttrium, tin, tungsten, and cerium.

Abstract: A catalyst carrier production process includes a step (a) of mixing a transition metal compound (1), a nitrogen-containing organic compound (2), and a solvent to provide a catalyst carrier precursor solution; a step (b) of removing the solvent from the catalyst carrier precursor solution; and a step (c) of the thermally treating a solid residue obtained in the step (b) at a temperature of 500 to 1100° C. to provide a catalyst carrier; wherein the transition metal compound (1) is partly or wholly a compound including a transition metal element (M1) selected from the group 4 and 5 elements of the periodic table as a transition metal element; and at least one of the transition metal compound (1) and the nitrogen-containing organic compound (2) includes an oxygen atom.

Abstract: A catalyst particle including platinum and palladium, and having a proportion of palladium in the surface of the particle, measured by X-ray photoelectron spectroscopy (XPS), of 45 to 55 atom % with respect to a total amount of platinum and palladium of 100 atom %. Also disclosed is a support-type catalyst particle, a fuel cell catalyst layer, an electrode including the fuel cell catalyst layer and a membrane electrode assembly including the electrode.