Visible-light photocatalysis of nitrogen-doped TiO2 nanoparticulate films prepared by low-energy ion implantation

Nitrogen-doped TiO2 (N–TiO2) films were prepared by low-energy implantation of nitrogen ions into pulsed laser deposited anatase TiO2 films. The anatase phase of the films was not changed by the implantation with very low energy of 200 eV. XPS measurements revealed that the implanted nitrogen species were mainly interstitial ones. The nitrogen concentration was increased with increasing ion flux which could be controlled by adjusting the gas flow rate of the ion source. All the produced N–TiO2 films exhibited visible-light photocatalytic activities in degradation of methylene blue in aqueous solutions, indicating that interstitial nitrogen could also be responsible for the photocatalysis in visible region. Higher visible-light photocatalytic efficiency was achieved with higher implanted nitrogen concentration.