Abstract: F-doped TiO₂ (FTO) sol was prepared using NH₄F as the fluorine precursor by a hydrothermal method. FTO thin film was then prepared via dip-coating. The TiO₂ thin film prepared from the TiO₂ sol that was hydrothermally treated at 120 ^oC for 10 h had preferable transparence and high photocatalytic activity. F doping did not significantly change the grain size of TiO₂ but greatly enhanced the photocatalytic activity of the TiO₂ film. The optimal doping concentration of F corresponded to F/Ti molar ratio of 0.01. The photocatalytic activity of the FTO thin film was 23% higher than that of TiO₂ thin film. X-ray photoelectron spectroscopy results showed that there were two forms of F element in the FTO thin film: surface chemically adsorbed F and substituent lattice F. Both surface adsorbed F and substituent lattice F played a role in the photocatalytic activity enhancement of the FTO thin film.

Key words: fluorine, doping, titanium dioxide, thin film, photocatalysis, rhodamine B, degradation