Application of ion beam techniques for preparation of metal ion-implanted TiO₂ thin film photocatalyst available under visible light irradiation: metal ion-implantation and ionized cluster beam method

Transparent TiO₂ thin film photocatalysts have been prepared on silica glass plate by an ionized cluster beam (ICB) method. In order to improve the electronic properties of these photocatalysts, transition metal ions V⁺, Cr⁺, Mn⁺, Fe⁺) were implanted into the TiO₂ thin films at high energy acceleration using an advanced metal ion-implantation technique. The combination of these ion beam techniques can allow us to prepare the TiO₂ thin film photocatalysts which can work effectively under visible light (λ > 450 nm) and/or solar light irradiation. The investigation using XAFS and ab initio molecular calculation suggests that the substitution of octahedrally coordinated Ti ions in TiO₂ lattice with implanted metal ions is important to modify TiO₂ to be able to adsorb visible light and operate under visible light irradiation.