Hydrophilicity of TiO2 films prepared by liquid phase deposition

TiO2 thin films were deposited on glass surfaces by a liquid phase deposition method. The changes of hydrophilicity of the films under ultraviolet (UV) illumination were investigated. It was observed that hydrophilicities of the films were all increased by UV illumination whether they were annealed or not. The annealed films could be entirely wetted by water after UV illumination for a certain time. In situ electron paramagnetic resonance (EPR) measurements yielded some signals attributed to O-2(-) under UV illumination. The O-2(-) was formed by electron transfer to O-2(-) indirectly proving formation of Ti3+ by UV light. X-Ray photoelectron spectroscopy analysis revealed that upon UV illumination, adsorption of water on the surface of the films increased. (C) 2000 Elsevier Science S.A. All rights reserved.