Preparation and photocatalytic activity of BiOX–TiO2 composite films (X=Cl, Br, I)

Abstract Being able to separate electron–hole pairs effectively, semiconductor compound systems can exhibit outstanding photocatalytic activity. Based on this consideration, BiOX–TiO 2 composite films were prepared in this work. Firstly, TiO 2 nanotube arrays were prepared through anodization of titanium foils; then BiOX (X=Cl, Br, I) was deposited into the TiO 2 nanotube arrays by vacuum impregnation and chemical precipitation to obtain the required BiOX–TiO 2 composite films. The morphologies, phase components, and photocatalytic activities of the samples were characterized by using scanning electron microscopy, X-ray diffractometry, and UV–vis spectrophotometry, respectively. Results showed that the bonding between BiOX and TiO 2 decreased in the order X=Cl, Br and I, as did the photocatalytic activity. The BiOCl–TiO 2 composite film exhibited better photocatalytic activity than those of the other samples due to effective transportation and long lifetime of the photo-induced electrons. Further experiments indicated that with BiOCl–TiO 2 composite film as photocatalysts, the decolorization ratio of methyl orange solution reached 99.7% under xenon-light irradiation for 8 h.