Photocatalytic degradation of organic compounds diluted in water using visible light-responsive metal ion-implanted TiO2 catalysts: Fe ion-implanted TiO2

The application of metal ion-implantation method has been made to improve the electronic properties of the TiO2 photocatalyst to realize the utilization of visible light. The photocatalytic properties of these unique TiO2 photocatalysts for the purification of water have been investigated. By the metal ion-implantation method, metal ions (Fe+, Mn+, V+, etc.) are accelerated enough to have the high kinetic energy (150 keV) and can be implanted into the bulk of TiO2. TiO2 photocatalysts which can absorb visible light and work as a photocatalyst efficiently under visible light irradiation were successfully prepared using this advanced technique. The UV-Vis absorption spectra of these metal ion-implanted TiO2 photocatalysts were found to shift toward visible light regions depending on the amount and the kind of metal ions implanted. They were found to exhibit an effective photocatalytic reactivity for the liquid-phase degradation of 2-propanol diluted in water at 295 K under visible light (λ>450 nm) irradiation. The investigation using XAFS analysis suggested that the substitution of Ti ions in TiO2 lattice with implanted metal ions is important to modify TiO2 to be able to adsorb visible light.