TiO2 doped with iron (Fe-TiO2) thin films were synthesized using sol-gel method. TiO2 codoped with iron and nitrogen (Fe/N-TiO2) thin films were prepared by calcining Fe-TiO2 thin films in ammonia atmosphere. The influence of iron and nitrogen doping concentration, heat-treatment temperature and film thickness on the hydrophilicity of the films were studied by XRD, XPS, SEM, UV-Vis spectra and measured water contact angle. The results indicated that Fe/N-TiO2 (0.5%Fe, molar percent) films were optimum in hydrophilicity, especially under visible-light irradiation. Doping iron mostly reduced the recombination of electrons and holes, and doping nitrogen in TiO2 enhances photoresponse in visible-light region. The hydrophilicity benefited from both effects
