Separate evolution of H2 and O2 from H2O on visible light-responsive TiO2 thin film photocatalysts prepared by an RF magnetron sputtering method

Visible light-responsive TiO2 thin film photocatalysts (Vis-TiO2) have been prepared on Ti metal foil (Vis-TiO2/Ti) or ITO glass (Vis-TiO2/ITO) substrates by a radio-frequency magnetron sputtering (RF-MS) method. The UV–Vis spectra as well as photoelectrochemical performance of Vis-TiO2 were affected by various calcination treatments such as calcination in air or NH3. Calcination treatment in NH3 (1.0 × 104 Pa, 673 K) was particularly effective in increasing the visible light absorption of Vis-TiO2 as well as in enhancing its photoelectrochemical performance and photocatalytic activity. A novel Vis-TiO2 thin film photocatalyst (Vis-TiO2/Ti/Pt) was prepared by an RF-MS method where Vis-TiO2 was deposited on one side of a Ti metal foil substrate and nanoparticles of Pt were deposited on the other side. The separate evolution of H2 and O2 from H2O could be successfully achieved by using an H-type glass cell consisting of two aqueous phases separated by Vis-TiO2/Ti/Pt and a proton-exchange membrane. It was found that the rate of the separate evolution of H2 and O2 was also dramatically enhanced by calcination treatment of Vis-TiO2 in NH3.