Process for cracking hydrocarbon gases, wherein the hydrocarbon gas is passed through a flow channel of an absorptive receiver reactor (1, 30, 40), characterized in that cracking takes place during the passing through the receiver reactor (1, 30, 40), wherein in a first region (21) of the flow channel (2) the hydrocarbon gas is heated to its cracking temperature, in an adjoining second, downstream flow region (22) is heated to beyond its cracking temperature and in a third, further downstream region (23) of the flow channel is heated yet further and is brought therein into physical contact, over the cross-section of said region, with a reaction accelerator, after which the stream of products downstream of the reaction accelerator is discharged from the receiver reactor (1, 30, 40), and wherein the heating of the hydrocarbon gas to above its cracking temperature is achieved by absorption of blackbody radiation (20) which is given off by the reaction accelerator heated by solar radiation (7) incident thereupon to the hydrocarbon gas flowing towards it, in such a way that the hydrocarbon gas in the flow channel (2) and extending up to the reaction accelerator forms disc-shaped, consecutive temperature zones (60 to 67) of ever-increasing temperature extending transversely to the flow channel (2).

In an apparatus producing hydrogen gas by the decomposition reaction of water using photocatalyst, its miniaturization is achieved while suppressing the decrease of production efficiency of hydrogen gas as low as possible or improving the efficiency. The apparatus 1 comprises a container portion 2 receiving water W; a photocatalyst member 3 immersed in the water, having photocatalyst which generates excited electrons and positive holes when irradiated with light, causes a decomposition reaction of the water and generates hydrogen gas; a light source 4 emitting the light irradiated to the photocatalyst member; and a heat exchange device 7 conducting waste heat of the light source to the water in the container portion; wherein the water to be decomposed on the photocatalyst member in the container portion is warmed by the waste heat of the light source by the heat exchange device.

A hydrogen release and storage system (100) of the present invention includes a hydrogen compound member (101), a container (102) that accommodates the hydrogen compound member (101), a heating apparatus (103) configured to heat the inside of the container (102), a cooling apparatus (104) configured to cool the inside of the container (102) and a water supply apparatus (105) configured to supply water to the container (102).

Provided is a molybdenum sulfide that is ribbon-shaped and particularly suitable for a hydrogen generation catalyst. Disclosed are a ribbon-shaped molybdenum sulfide, in which 50 particles as measured by observation with a scanning electron microscope (SEM) have a shape of, on average, 500 to 10000 nm in length, 10 to 1000 nm in width, and 3 to 200 nm in thickness; a method for producing the ribbon-shaped molybdenum sulfide, including: (1) heating a molybdenum oxide at a temperature of 200 to 1000° C. in the presence of a sulfur source; or (2) heating a molybdenum oxide at a temperature of 100 to 800° C. in the absence of a sulfur source, and then heating the molybdenum oxide at a temperature of 200 to 1000° C. in the presence of a sulfur source; and a hydrogen generation catalyst including the ribbon-shaped molybdenum sulfide.

The nitride semiconductor photocatalytic thin film of the present embodiment is a nitride semiconductor photocatalytic thin film that exhibits a catalytic function to cause a redox reaction by light irradiation. The nitride semiconductor photocatalytic thin film includes: a conductive substrate; a semiconductor thin film disposed on a surface of the conductive substrate; a first catalyst layer that forms an ohmic junction on a portion of a surface of the semiconductor thin film; a second catalyst layer that forms a Schottky junction on a portion of the surface of the semiconductor thin film, and a protective layer disposed to cover a back surface of the conductive substrate and side surfaces of the conductive substrate and the semiconductor thin film. The substrate and the semiconductor thin film include a same element and have a same crystal structure.

In an apparatus producing hydrogen gas by a decomposition reaction of water using a photocatalyst, the water is warmed with waste heat of a light source for improving the production efficiency of hydrogen gas. The hydrogen gas producing apparatus 1 comprises a container portion receiving water; a photocatalyst body, dispersed or placed in the water, having a photocatalyst material to generate excited electrons and electron holes by irradiation of light, causing the decomposition reaction of water which decomposes water into hydrogen and oxygen to generate hydrogen gas; a light source emitting the light to be irradiated to the photocatalyst body; and a housing carrying the light source; wherein the housing is placed in the water, which is warmed by the waste heat of the light source discharged from the housing surface which is coated with a photocatalyst material.

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.

A method can include incorporating graphene oxide (GO) in a solution, reducing the graphene oxide (GO) by refluxing carbon nitride (C.sub.3N.sub.4) in the solution to form carbon-nitride refluxed-graphene-oxide (C.sub.3N.sub.4-rGO) composites, and incorporating ruthenium ions into the C.sub.3N.sub.4-rGO composites to form C.sub.3N.sub.4-rGO-Ru complexes.

A method can include incorporating graphene oxide (GO) in a solution, reducing the graphene oxide (GO) by refluxing carbon nitride (C.sub.3N.sub.4) in the solution to form carbon-nitride refluxed-graphene-oxide (C.sub.3N.sub.4-rGO) composites, and incorporating ruthenium ions into the C.sub.3N.sub.4-rGO composites to form C.sub.3N.sub.4-rGO-Ru complexes.

Disclosed are metal nitride photoctalyst particles and/or metal oxynitride photocatalyst particles having high dispersibility. The metal nitride photoctalyst particles and/or metal oxynitride photocatalyst particles having high dispersibility can be obtained by containing metal nitride photoctalyst particles and/or metal oxynitride photocatalyst particles, which are capable of splitting water under visible light irradiation, and a phosphoric acid polymer that is adsorbed on the surface of the particles. Further, because these particles have high photocatalytic activity under visible light irradiation, splitting water by using these particles can generate hydrogen and/or oxygen with high efficiency.