Hydrophilicity on carbon-doped TiO2 thin films under visible light

Carbon-cloped TiO2 thin films in the anatase phase with dopant concentrations of 1.1, 0.9, and 0.7 mol% were fabricated by a radio-frequency magnetron sputtering method. Dopant carbons were located at the oxygen sites. Carbon substitution caused the absorbance edge and/or the shoulder of TiO2 to shift to a higher wavelength region. Carbon-doped TiO2 thin films underwent a hydrophilic conversion when irradiating with visible light (400-530 nm). The hydrophilic property under visible light was inferior to that under ultraviolet light, which is explained by considering that the visible light sensitivity originates from the localized C 2p formed in the band-gap. (c) 2005 Elsevier B.V. All rights reserved.