TiOxNy/TiO2 Photocatalyst for Hydrogen Evolution under Visible-Light Irradiation. I: Characterization of N in TiOxNy/TiO2 Photocatalyst

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.