TiO(x)N(y)/TiO(2) Photocatalyst for Hydrogen Evolution under Visible-Light Irradiation. I: Characterization of N in TiO(x)N(y)/TiO(2) Photocatalyst

[Image: see text] TiO(x)N(y)/TiO(2) was synthesized by nitriding of TiO(2) in NH(3) gas. TiO(x)N(y)/TiO(2) generated hydrogen from methanol aqueous solution under visible-light irradiation. It was revealed by N K-edge XANES and N 1s XPS measurements that the N species contributing to visible-light responsiveness was the O-Ti-N species. The structure of TiO(x)N(y)/TiO(2) showing the photocatalytic activity was a double shell type with thin layers of TiO(x)N(y) that covers the TiO(2) core. Although N content on the surface decreased during the photocatalytic reaction, N was supplied from the deeper side to keep the TiO(x)N(y) phase at the surface and the activity as well.