Fabrication of Bi2O3/TiO2 Nanotube Arrays with High Visible-Light Photocatalytic Activity by Impregnation-Decomposition Method

Bi2O3/TiO2 nanotube arrays (NTs) were prepared by depositing Bi2O3 nanoparticles (NPs) onto the tube wall of self-organized TiO2 NTs using an impregnation-decomposition method. Chemical composition of the resulting Bi2O3/TiO2 NTs was determined by inductively coupled plasma atomic emission spectrometry (ICP-AES). The prepared samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and UV-visible (UV-Vis) diffuse reflectance spectroscopy. Photocatalytic activity was evaluated by degradation of aqueous methyl orange (MO) solution under visible-light irradiation (lambda>400 nm). The Bi2O3 nanoparticles were found to be uniformly deposited into the nanotubes. Bi2O3/TiO2 NTs exhibited much higher visible-light activity than pure Bi2O3 films and N-TiO2 NTs, which was attributed to synergistic effects of the strong visible-light absorption of Bi2O3/TiO2 NTs and the heterojunction formed between Bi2O3 and TiO2.