Abstract: Pb-doped TiO₂ thin films were prepared on the surface of active carbon via a sol-gel
dip-coating method by using PbNO₃ and Ti(OBt)₄ as precursors. The as-prepared thin films were characterized by UV-VIS spectrophotometry,
transmission electron microscopy (TEM) and X-ray diffraction (XRD). Photocatalytic activities of the thin films were evaluated by photocatalytic
decoloration of methyl orange aqueous solution and photocatalytic degradation of omethoate aqueous solution, respectively. The results show that the rutile
phase is precipitated ad well as anatase phase. With an increase in the Pb amount in the films, the rutile content increases. Therefore, the band edges of
the various Pb-doped TiO₂ thin films exhibit slightly red shift compared with un-doped TiO₂ thin film. Photocatalytic activities
of the thin films are obviously enhanced due to Pb-doping. The thin film shows the highest photocatalytic activity when the Pb/TiO₂ mass ratio
=1.7%. This is probably ascribed to the fact that Pb(Ⅱ) and Pb(Ⅳ) in the Pb-doped TiO₂ thin films can transform each other via low-potential-
capturing the photo-generated holes and electrons of TiO₂ under UV illumination. Thus, the recombination of photo-generated electrons and holes is
reduced, and the photocatalytic activity of thin film is enhanced.

Key words: Pb-doping, TiO₂ thin film, sol-gel method, preparation, photocatalytic activity