Natural superhydrophilic TiO2/SiO2 composite thin films deposited by radio frequency magnetron sputtering

TiO2/SiO2 composite thin films deposited on various substrates have been prepared by radio frequency magnetron sputtering from a composite target. The composite films were characterized by X-ray diffraction (XRD), atomic force microscopy, X-ray photoelectron spectroscopy and water contact angel measurements. XRD analysis indicates the amorphous structures of TiO2/SiO2 composite thin films. Contact-angle results show that TiO2/SiO2 Composite thin films represent natural superhydrophilicity without UV irradiation due to the enhanced acidity at SiO2-TiO2 interfaces. The heat treatment is necessary to promote thermal diffusion of Si4+ or Ti4+ Cations within TiO2 or SiO2 hosts. in addition, radio frequency magnetron sputtering also may play a role in the formation of hydrophilic film surfaces. (C) 2009 Elsevier B.V. All rights reserved.