Papers by Author: Masato Takeuchi

Abstract: TiO2 (Vis-TiO2) thin films absorbing UV and visible light in regions of 250-600nm have been successfully developed by applying a radio-frequency (RF) magnetron sputtering deposition method. SIMS depth profiles of Vis-TiO2 revealed that the O/Ti ratio gradually decreases from the top surface (O/Ti ratio : 2.00 ± 0.01) to the inside (1.93 ± 0.01). This unique declined O/Ti composition (anisotropic structure) may be the origin of the significant perturbation in the electronic structure of Vis-TiO2, enabling the absorption of visible light and their high photocatalytic performance under visible light irradiation. In fact, it was found that the separate evolution of H2 and O2 from water could be successfully achieved under visible light or solar light irradiation by applying these thin film photocatalysts in an H-type glass container separating the two aqueous solutions by a TiO2 thin film and proton-exchange membrane, having H2 evolution from Pt side and O2 evolution from TiO2 thin film side, respectively.

Abstract: Visible light responsive TiO2 (Vis-TiO2) thin films were successfully developed by the radio-frequency magnetron sputtering method, and their photocatalytic activities for the water splitting reactions were investigated. Pt-loaded Vis-TiO2 thin films acted as photocatalysts to decompose water involving sacrificial reagent such as methanol or silver nitrate under visible light irradiation (λ³ 420 nm). Furthermore, the separate evolution of H2 and O2 was successfully achieved under solar light irradiation by applying these photocatalysts in a H-type glass container, which consists of two water phases separated by a TiO2 thin film and proton-exchange membrane.