Synthesis of Bi2O3-TiO2 composite film with high-photocatalytic activity under sunlight irradiation

Bi(2)O3-TiO2 composite films were synthesized by a sol-gel method under mild condition (i.e. low temperature and ambient pressure). The as-prepared films were characterized by X-ray diffraction, scanning electron microscopy, X-ray photoelectron spectroscopy, infrared spectra and fluorescence spectra. The results showed that Bi2O3-TiO2 composite films were composed of anatase titania and Bi2O3. TiO2 particles were deposited on the surface of Bi2O3 to form uniform film. Incorporating Bi2O3 with TiO2 leads to increased surface OH group density. All Bi2O3-TiO2 composite films exhibited higher photocatalytic activity compared with pure TiO2 under solar irradiation, while the film with Bi/Ti atomic ratio of 1.25% showed the highest photocatalytic activity. Furthermore, the as-prepared films can be reused with little photocatalytic activity decreasing. Without any further treatment besides rinsing, the photocatalytic activity of Bi2O3-TiO2 (1.25%) films was still higher than 77% after six-cycle utilization. (C) 2008 Elsevier B. V. All rights reserved.