Energy band structure and photocatalytic activity of Sn-doped TiO₂ thin film

TiO₂ thin films were successfully deposited onto microscope glass substrates by using RF sputtering technology. Then Sn ions were implanted into the TiO₂ thin film with ion implantation method. The photocatalytic activities of the Sn-doped and un-doped TiO₂ thin films under visible light were evaluated by the photodegradation of methylene blue dye solution. The results indicate that the photocatalytic activity of the Sn-doped anatase TiO₂ thin film is enhanced under the visible light irradiation. The energy band structures of the Sn-doped and un-doped TiO₂ were calculated by the first-principle based on density functional theory (DFT). The Sn doping takes slight effect on the band structure of TiO₂, whereas doping energy level is formed by Sn 5s orbit near the bottom of the TiO₂ valence band.