Application of ion beams for preparation of TiO2 thin film photocatalysts operatable under visible light irradiation:: Ion-assisted deposition and metal ion-implantation

The visible light sensitive TiO2 thin film photocatalysts can be developed by the application of ion beam techniques, i.e. the combination of an ion-assisted deposition (IAD) method and a metal ion-implantation. The transparent TiO2 thin film photocatalysts have been prepared on silica glass plate by the IAD method. Then the transition metal ions (V-divided by) were implanted into the TiO2 thin films at high energy acceleration using a metal ion-implantation technique to improve the electronic properties of the TiO2 thin film to be able to work effectively as photocatalysts under visible light ( lambda > 450 nm) and/or solar light irradiation. The investigation using X-ray absorption fine structure analysis and ab initio molecular calculation suggest that the substitution of octahedrally coordinated Ti ions in TiO2 lattice with implanted metal ions (V+) is important to modify TiO2 to be able to adsorb visible light and operate under visible light irradiation. (C) 2003 Elsevier Science B.V. All rights reserved.