Overall photodecomposition of water on a layered niobiate catalyst

The photolysis of water into hydrogen and oxygen is a reaction involving the transformation of a high amount of energy. Recently, it was found that a photocatalyst having a layered structure gave not only a behaviour different from that observed with a conventional bulk-solid type semiconductor photocatalyst, but also that the layered photocatalyst gave a stable and high photocatalytic activity for water decomposition. A new type of photocatalyst, Ni-K 4 Nb 6 O 17 , has ultrafine particles of nickel metal in the interlayer spaces. It has a structure of what may be called a “two-dimensional photocatalyst,” which decomposes intercalated water molecules. It is also interesting in its mechanism in which it works in the decomposition of water. In this paper, our recent results concerning this new type of photocatalyst are reviewed.