Improved photocatalytic activity of Sn4+ doped TiO2 nanoparticulate films prepared by plasma-enhanced chemical vapor deposition

Sn4+ ion doped TiO2 (TiO2-Sn4+) nanoparticulate films with a doping ratio of about 7:100 [(Sn):(Ti)] were prepared by the plasma-enhanced chemical vapor deposition (PCVD) method. The doping mode (lattice Ti substituted by Sn4+ ions) and the doping energy level of Sn4+ were determined by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), surface photovoltage spectroscopy (SPS) and electric field induced surface photovoltage spectroscopy (EFISPS). It is found that the introduction of a doping energy level of Sn4+ ions is profitable to the separation of photogenerated carriers under both UV and visible light excitation. Characterization of the films with XRD and SPS indicates that after doping by Sn, more surface defects are present on the surface. Consequently, the photocatalytic activity for photodegradation of phenol in the presence of the TiO2-Sn4+ film is higher than that of the pure TiO2 film under both UV and visible light irradiation.