PHOTOCATALYST, HYDROGEN GENERATION DEVICE, AND ENERGY SYSTEM CONTAINING NIOBIUM NITRIDE

The present invention is a niobium nitride which has a composition represented by the composition formula Nb 3 N 5 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.