Abstract: A method for producing a hydrogen-enriched gas, the method including: (A) generating a mixed gas containing hydrogen and oxygen in a reactor that decomposes water into hydrogen and oxygen using sunlight in the presence of a photocatalyst; (B) collecting the mixed gas in a storage tank; (C) supplying the mixed gas in the storage tank to a gas separation device that includes a membrane having an ability to separate hydrogen and oxygen; and (D) separating a hydrogen-enriched gas from the mixed gas in the gas separation device.

Abstract: Single crystalline nanoparticles that are tantalum nitride doped with at least one metal are described. The single crystalline nanoparticles can be doped with two metals such as Zr and Mg. The single crystalline nanoparticles can be Ta3N5:Mg+Zr, or Ta3N5:Mg, or Ta3N5:Zr or any combination thereof. Catalyst containing the single crystalline nanoparticles alone or with one or more co-catalyst are further described along with methods of making the nanoparticles and catalyst. Methods to split water utilizing the catalyst are further described.

Abstract: The present invention provides a method of producing a composite photocatalyst having a remarkable water splitting activity, which is capable of efficiently loading a co-catalyst having a small particle size in a highly dispersed manner on a surface of an optical semiconductor. According to the present invention, the method of producing a composite photocatalyst from a plurality types of optical semiconductors includes a step of heating a solid-liquid mixture containing a solvent, a co-catalyst or a co-catalyst source, and a plurality of types of optical semiconductors by irradiating the solid-liquid mixture with microwave.

Abstract: A method foe producing a transparent electrode for oxygen production having a Ta nitride layer on a transparent substrate, including: a step of forming a Ta nitride precursor layer on the transparent substrate; and a step of nitriding the Ta nitride precursor layer with a mixed gas containing ammonia and a carrier gas.

Abstract: A method for producing a transparent electrode for oxygen production having a Ta nitride layer on a transparent substrate, including: a step of forming a Ta nitride precursor layer on the transparent substrate; and a step of nitriding the Ta nitride precursor layer with a mixed gas containing ammonia and a carrier gas.

Abstract: Provided are a photocatalyst electrode for oxygen generation exhibiting a satisfactory onset potential, and a module including this photocatalyst electrode. The photocatalyst electrode for oxygen generation includes a current collector layer; a photocatalyst on the current collector layer; and a promoter supported on at least a portion of the photocatalyst, in which the promoter contains a first metal oxide having an oxygen generation overvoltage of 0.4 V or lower, and a second metal oxide having an oxygen generation overvoltage of higher than 0.4 V.

Abstract: A photocatalytic member comprises a base and a photocatalytic layer fixed on the base. The photocatalytic layer comprises first photocatalyst particles being visible light responsive photocatalyst particles for hydrogen generation, second photocatalyst particles being visible light responsive photocatalyst particles for oxygen generation, and conductive particles which are provided between the first photocatalyst particle and the second photocatalyst particle, have Fermi level at a negative position relative to an electronic energy level at the upper end of the valence band of the first photocatalyst particle and at a positive position relative to an electronic energy level at the bottom end of the conduction band of the second photocatalyst particle, and are able to store an electron and a hole. In the photocatalytic layer, the conductive particles are located to be coupled to both the first photocatalyst particles and the second photocatalyst particles.

Abstract: A method for producing a transparent electrode for oxygen production having a Ta nitride layer on a transparent substrate, including: a step of forming a Ta nitride precursor layer on the transparent substrate; and a step of nitriding the Ta nitride precursor layer with a mixed gas containing ammonia and a carrier gas.

Abstract: The present invention has an object to provide a photocatalyst electrode for oxygen generation having excellent photocurrent density, a production method for a photocatalyst electrode for oxygen generation and a module, and the photocatalyst electrode for oxygen generation of the present invention includes a current collector layer and a photocatalyst layer containing Ta3N5, wherein the photocatalyst electrode for oxygen generation has a charge separation promotion layer between the current collector layer and the photocatalyst layer.

Abstract: The present invention provides an electrode for water-splitting reaction that is capable of increasing conductive path between a photocatalyst layer and a current collecting layer without inhibiting light absorption by photocatalyst, which comprises: a photocatalyst layer 10; a current collecting layer 30; and a contact layer 20 that contains semiconductor or good conductor and is provided between the photocatalyst layer 10 and the current collecting layer 30, wherein the contact layer 20 is provided along the surface shape of the photocatalyst layer 10 at the current collecting layer 30 side of the photocatalyst layer 10.

Abstract: Provided is an artificial-photosynthesis module, which decomposes an aqueous electrolyte solution into hydrogen and oxygen by means of light, including a photoelectric conversion unit that receives light to generate electrical energy; a hydrogen gas generating part that decomposes the aqueous electrolyte solution, using the electrical energy of the photoelectric conversion unit, and generates hydrogen gas; and an oxygen gas generating part that decomposes the aqueous electrolyte solution, using the electrical energy of the photoelectric conversion unit, and generates oxygen gas. The photoelectric conversion unit, the hydrogen gas generating part, and the oxygen gas generating part are electrically connected in series, and the hydrogen gas generating part and the oxygen gas generating part are arranged within an electrolytic chamber to which the aqueous electrolyte solution is supplied. The hydrogen gas generating part has an inorganic semiconductor film having a pn junction.

Abstract: The present invention provides a method of producing a composite photocatalyst having a remarkable water splitting activity, which is capable of efficiently loading a co-catalyst having a small particle size in a highly dispersed manner on a surface of an optical semiconductor. According to the present invention, the method of producing a composite photocatalyst from a plurality types of optical semiconductors includes a step of heating a solid-liquid mixture containing a solvent, a co-catalyst or a co-catalyst source, and a plurality of types of optical semiconductors by irradiating the solid-liquid mixture with microwave.

Abstract: Provided is a method for producing a photocatalyst electrode for water decomposition that exhibits excellent detachability between the substrate and the photocatalyst layer and exhibits high photocurrent density. The method for producing a photocatalyst electrode for water decomposition of the invention includes: a metal layer forming step of forming a metal layer on one surface of a first substrate by a vapor phase film-forming method or a liquid phase film-forming method; a photocatalyst layer forming step of forming a photocatalyst layer by subjecting the metal layer to at least one treatment selected from an oxidation treatment, a nitriding treatment, a sulfurization treatment, or a selenization treatment; a current collecting layer forming step of forming a current collecting layer on a surface of the photocatalyst layer, the surface being on the opposite side of the first substrate; and a detachment step of detaching the first substrate from the photocatalyst layer.

Abstract: The present invention provides a method of producing a composite photocatalyst having a remarkable water splitting activity, which is capable of efficiently loading a co-catalyst having a small particle size in a highly dispersed manner on a surface of an optical semiconductor. According to the present invention, the method of producing a composite photocatalyst from a plurality types of optical semiconductors includes a step of heating a solid-liquid mixture containing a solvent, a co-catalyst or a co-catalyst source, and a plurality of types of optical semiconductors by irradiating the solid-liquid mixture with microwave.

Abstract: Provided is an artificial-photosynthesis array configured of artificial-photosynthesis modules which have been arranged in one or more rows and which receive light and decompose a supplied aqueous electrolyte solution to thereby obtain hydrogen gas and oxygen gas. The artificial-photosynthesis modules each includes an electrolytic chamber for hydrogen where hydrogen gas is generated and an electrolytic chamber for oxygen where oxygen gas is generated, the chambers being isolated from each other. The electrolytic chambers for hydrogen and electrolytic chambers for oxygen of the artificial-photosynthesis modules are alternately connected so that the electrolytic chamber for hydrogen of each artificial-photosynthesis module is connected to the electrolytic chamber for oxygen of another module and the electrolytic chamber for oxygen of each artificial-photosynthesis module is connected to the electrolytic chamber for hydrogen of another module.

Abstract: A photocatalytic member comprises a base and a photocatalytic layer fixed on the base. The photocatalytic layer comprises first photocatalyst particles being visible light responsive photocatalyst particles for hydrogen generation, second photocatalyst particles being visible light responsive photocatalyst particles for oxygen generation, and conductive particles which are provided between the first photocatalyst particle and the second photocatalyst particle, have Fermi level at a negative position relative to an electronic energy level at the upper end of the valence band of the first photocatalyst particle and at a positive position relative to an electronic energy level at the bottom end of the conduction band of the second photocatalyst particle, and are able to store an electron and a hole. In the photocatalytic layer, the conductive particles are located to be coupled to both the first photocatalyst particles and the second photocatalyst particles.

Abstract: A hydrogen generation electrode is used for an artificial photosynthesis module that decomposes an electrolytic aqueous solution into hydrogen and oxygen with light. The hydrogen generation electrode has a conductive layer, an inorganic semiconductor layer that is provided on the conductive layer and has a pn junction, and a functional layer that covers an inorganic semiconductor layer. The steam permeability of the functional layer is 5 g/(m2·day) or less.

Abstract: The present invention provides a photocatalyst for water splitting which includes barium niobium oxynitride and exhibits excellent water splitting performance and a production method for the same, and a water splitting photoelectrode. The photocatalyst for water splitting of the present invention is a photocatalyst for water splitting including: an optical semiconductor and a promoter supported by the optical semiconductor, in which the optical semiconductor includes barium niobium oxynitride, and the promoter includes at least one substance selected from a group consisting of cobalt oxides and metallic cobalt.

Abstract: Provided are a photocatalyst electrode for oxygen generation exhibiting a satisfactory onset potential, and a module including this photocatalyst electrode. The photocatalyst electrode for oxygen generation includes a current collector layer; a photocatalyst on the current collector layer; and a promoter supported on at least a portion of the photocatalyst, in which the promoter contains a first metal oxide having an oxygen generation overvoltage of 0.4 V or lower, and a second metal oxide having an oxygen generation overvoltage of higher than 0.4 V.

Abstract: Provided are a photocatalyst having higher activity for hydrogen production through water splitting and a photoelectrode comprising the photocatalyst. The photocatalyst for water splitting of the present invention comprises a Ga selenide, an Ag—Ga selenide, or both thereof.