Abstract: An electrode catalyst according to the present disclosure includes a mesoporous material and catalyst metal particles which are supported in at least an inner portion of the mesoporous material and which contain platinum and a metal different from platinum. The mesoporous material has mesopores having a mode radius of greater than or equal to 1 nm and less than or equal to 25 nm and a pore volume of greater than or equal to 1.0 cm3/g and less than or equal to 3.0 cm3/g. The catalyst metal particles which are supported have an L10 structure. The proportion of the L10 structure is greater than 0.25.

Abstract: A catalyst includes a mesoporous material and catalytic metal particles supported at least within the mesoporous material and containing platinum and a metal different from platinum. The mesoporous material has mesopores with a mode radius of 1 to 25 nm and a pore volume of 1.0 to 3.0 cm3/g before supporting of the catalytic metal particles, and has an average particle size of greater than or equal to 200 nm. A molar ratio of the metal different from platinum and contained in the catalytic metal particles relative to all metals contained in the catalytic metal particles is greater than or equal to 0.25, and among the catalytic metal particles, a volume ratio of catalytic metal particles having a particle size of greater than or equal to 20 nm is less than or equal to 10%.

Abstract: An electrode catalyst of an electrochemical device according to the present disclosure is an electrode catalyst of an electrochemical device, the electrode catalyst including a mesoporous material; and catalyst metal particles supported at least in the mesoporous material. Before supporting the catalyst metal particles, the mesoporous material includes mesopores having a mode radius of 1 to 25 nm and a pore volume of 1.0 to 3.0 cm3/g, and number density of the catalyst metal particles supported in the mesopores is lower at an outer side of the mesoporous material than number density of the catalyst metal particles supported in the mesopores at an inner side thereof.

Abstract: An electrode catalyst for a fuel battery includes a mesoporous material and catalyst metal particles supported at least in the mesoporous material. In the electrode catalyst for a fuel battery, before supporting the catalyst metal particles, the mesoporous material has mesopores having a mode radius of greater than or equal to 1 nm and less than or equal to 25 nm and has a value of greater than 0.90, the value being determined by dividing a specific surface area S1-25 (m2/g) of the mesopores obtained by analyzing a nitrogen adsorption-desorption isotherm according to a BJH method, the mesopores having a radius of greater than or equal to 1 nm and less than or equal to 25 nm, by a BET specific surface area (m2/g) evaluated according to a BET method.

Abstract: A catalyst includes a mesoporous material and catalytic metal particles supported at least within the mesoporous material and containing platinum and a metal different from platinum. The mesoporous material has mesopores with a mode radius of 1 to 25 nm and a pore volume of 1.0 to 3.0 cm3/g before supporting of the catalytic metal particles, and has an average particle size of greater than or equal to 200 nm. A molar ratio of the metal different from platinum and contained in the catalytic metal particles relative to all metals contained in the catalytic metal particles is greater than or equal to 0.25, and among the catalytic metal particles, a volume ratio of catalytic metal particles having a particle size of greater than or equal to 20 nm is less than or equal to 10%.

Abstract: An electrode catalyst of an electrochemical device according to the present disclosure is an electrode catalyst of an electrochemical device, the electrode catalyst including a mesoporous material; and catalyst metal particles supported at least in the mesoporous material. Before supporting the catalyst metal particles, the mesoporous material includes mesopores having a mode radius of 1 to 25 nm and a pore volume of 1.0 to 3.0 cm3/g, and number density of the catalyst metal particles supported in the mesopores is lower at an outer side of the mesoporous material than number density of the catalyst metal particles supported in the mesopores at an inner side thereof.

Abstract: A photoelectrode (100) of the present invention includes a conductive layer (12) and a photocatalytic layer (13) provided on the conductive layer (12). The conductive layer (12) is made of a metal nitride. The photocatalytic layer (13) is made of at least one selected from the group consisting of a nitride semiconductor and an oxynitride semiconductor. When the photocatalytic layer (13) is made of a n-type semiconductor, the energy difference between the vacuum level and the Fermi level of the conductive layer (12) is smaller than the energy difference between the vacuum level and the Fermi level of the photocatalytic layer (13). When the photocatalytic layer (13) is made of a p-type semiconductor, the energy difference between the vacuum level and the Fermi level of the conductive layer (12) is larger than the energy difference between the vacuum level and the Fermi level of the photocatalytic layer (13).

Abstract: The NbON film of the present invention is a NbON film in which a photocurrent is generated by light irradiation. The NbON film of the present invention is desirably a single-phase film. The hydrogen generation device (600) of the present invention includes: an optical semiconductor electrode (620) including a conductor (621) and the NbON film (622) of the present invention disposed on the conductor (621); a counter electrode (630) connected electrically to the conductor (621); a water-containing electrolyte (640) disposed in contact with a surface of the NbON film (622) and a surface of the counter electrode (630); and a container (610) containing the optical semiconductor electrode (620), the counter electrode (630), and the electrolyte (640). In this device, hydrogen is generated by irradiating the NbON film (622) with light.

Abstract: The present invention provides a method for generating oxygen. The method comprises (a) preparing a water electrolysis device comprising a container storing an electrolyte aqueous solution; an anode which is in contact with the electrolyte aqueous solution and includes at least one silver delafossite compound selected from the group consisting of a silver cobalt delafossite compound represented by a chemical formula AgCoO2 and a silver rhodium delafossite compound represented by a chemical formula AgRhO2; a cathode which is in contact with the electrolyte aqueous solution; and a power supply, wherein the at least one silver delafossite compound is in contact with the electrolyte aqueous solution, and (b) applying an electric potential difference between the cathode and the anode using the power supply to generate oxygen on the anode due to electrolysis of water which occurs on the at least one silver delafossite compound.

Abstract: A photosemiconductor electrode (400) of the present invention includes a conductor (410) and a photosemiconductor layer (first semiconductor layer) (420) provided on the conductor (410). The photosemiconductor layer (420) includes a photosemiconductor (e.g., a photosemiconductor film (421)) and an oxide containing iridium element (e.g., iridium oxide (422)). The Fermi level of the oxide containing iridium element is more negative than the Fermi level of the photosemiconductor and is more negative than ?4.44 eV, with respect to the vacuum level.

Abstract: The present invention is a niobium nitride which has a composition represented by the composition formula Nb3N5 and in which a constituent element Nb has a valence of substantially +5. The method for producing the niobium nitride of the present invention includes the step of nitriding an organic niobium compound by reacting the organic niobium compound with a nitrogen compound gas.

Abstract: The present invention provides a method for efficiently generating oxygen by electrolyzing water using a copper delafossite compound as an anode. First, in the present invention, a water electrolysis device is prepared. The water electrolysis device comprises a container, a power supply, an anode, a cathode; and an aqueous electrolytic solution. The anode and the cathode are in contact with the aqueous electrolytic solution. The anode has a copper cobalt delafossite compound represented by a chemical formula CuCoO2. The copper cobalt delafossite compound is in contact with the aqueous electrolytic solution. Then, an electric potential difference is applied between the cathode and the anode using the power supply to generate oxygen on the anode due to electrolysis of water which occurs on the copper cobalt delafossite compound.

Abstract: The present invention is a niobium nitride which has a composition represented by the composition formula Nb3N5 and in which a constituent element Nb has a valence of substantially +5. The method for producing the niobium nitride of the present invention includes the step of nitriding an organic niobium compound by reacting the organic niobium compound with a nitrogen compound gas.

Abstract: The optical semiconductor of the present invention is an optical semiconductor containing In, Ga, Zn, O and N, and has a composition in which a part of oxygen (O) is substituted by nitrogen (N) in a general formula: In2xGa2(1-x)O3(ZnO)y, where x and y satisfy 0.2<x<1 and 0.5?y. In the general formula, x is preferably 0.5, and furthermore, y is preferably 1 or more and 6 or less, and more preferably 2 or 6. It is preferred that the optical semiconductor of the present invention have a wurtzite crystal structure. The optical semiconductor of the present invention is an excellent optical semiconductor because it has a smaller band gap, can utilize visible light, and has high carrier mobility and thus has high quantum efficiency.

Abstract: A photoelectrochemical cell (100) includes: a semiconductor electrode (120) including a substrate (121), a first n-type semiconductor layer (122) disposed on the substrate (121), and a second n-type semiconductor layer (123) and a conductor (124) disposed apart from each other on the first n-type semiconductor layer (122); a counter electrode (130) connected electrically to the conductor (124); an electrolyte (140) in contact with surfaces of the second n-type semiconductor layer (123) and the counter electrode (130); and a container (110) accommodating the semiconductor electrode (120), the counter electrode (130) and the electrolyte (140).

Abstract: The method for producing the optical semiconductor of the present disclosure includes a mixing step of producing a mixture containing a reduction inhibitor and a niobium compound that contains at least oxygen in its composition; a nitriding step of nitriding the mixture by the reaction between the mixture and a nitrogen compound gas; and a washing step of isolating niobium oxynitride from the material obtained through the nitriding step by dissolving chemical species other than niobium oxynitride with a washing liquid. The optical semiconductor of the present disclosure substantially consists of niobium oxynitride having a crystal structure of baddeleyite and having a composition represented by the composition formula, NbON.

Abstract: The present invention is a niobium nitride which has a composition represented by the composition formula Nb3N5 and in which a constituent element Nb has a valence of substantially +5. The method for producing the niobium nitride of the present invention includes the step of nitriding an organic niobium compound by reacting the organic niobium compound with a nitrogen compound gas.

Abstract: A photoelectrode (100) of the present invention includes a conductive layer (12) and a photocatalytic layer (13) provided on the conductive layer (12). The conductive layer (12) is made of a metal nitride. The photocatalytic layer (13) is made of at least one selected from the group consisting of a nitride semiconductor and an oxynitride semiconductor. When the photocatalytic layer (13) is made of a n-type semiconductor, the energy difference between the vacuum level and the Fermi level of the conductive layer (12) is smaller than the energy difference between the vacuum level and the Fermi level of the photocatalytic layer (13). When the photocatalytic layer (13) is made of a p-type semiconductor, the energy difference between the vacuum level and the Fermi level of the conductive layer (12) is larger than the energy difference between the vacuum level and the Fermi level of the photocatalytic layer (13).

Abstract: An energy system includes an solar hydrogen producing unit (101) that produces hydrogen through decomposition of water by a photocatalytic effect, a fuel cell (103) that generates electricity by a reaction between the hydrogen produced by the solar hydrogen producing unit (101) and an oxidizing gas and discharges water as a reaction product, and a water distribution mechanism (104) that returns the water serving as the reaction product discharged from the fuel cell (103) to the solar hydrogen producing unit (101). With the configuration, an energy system that suppresses an amount of external water supply to a low level to achieve good water balance can be provided.

Abstract: The NbON film of the present invention is a NbON film in which a photocurrent is generated by light irradiation. The NbON film of the present invention is desirably a single-phase film. The hydrogen generation device (600) of the present invention includes: an optical semiconductor electrode (620) including a conductor (621) and the NbON film (622) of the present invention disposed on the conductor (621); a counter electrode (630) connected electrically to the conductor (621); a water-containing electrolyte (640) disposed in contact with a surface of the NbON film (622) and a surface of the counter electrode (630); and a container (610) containing the optical semiconductor electrode (620), the counter electrode (630), and the electrolyte (640). In this device, hydrogen is generated by irradiating the NbON film (622) with light.