Enhanced photocatalytic activity of Bi2WO6/TiO2 nanotube array composite under visible light irradiation

Titania nanotube array (TiO2 NT) was fabricated by anodization of titanium in an electrolyte containing HF and NaHSO4. The as-anodized TiO2 NT was crystallized to anatase phase by a heat treatment at 500 degrees C. Bi2WO6/TiO2 nanotube array composite (Bi2WO6/TiO2 NT) was synthesized by hydrothermal deposition of Bi2WO6 over the crystallized TiO2 NT. Bi2WO6 extended light absorption range of TiO2 NT, and the Bi2WO6/TiO2 exhibited stronger light absorption in both UV and visible light regions. In particular, the photoelectrochemical properties and photocatalytic activity of Bi2WO6/TiO2 NT under visible light irradiation were investigated. The photocurrent of Bi2WO6/TiO2 NT is four times as high as the bare annealed TiO2 NT was, which results from the enhanced photogenerated electron-hole pairs separation. The photocatalytic activity of Bi2WO6/TiO2 NT is two times as high as that of the pure TiO2 NT under visible light irradiation, and is about one and a half times as much as that over Bi2WO6. Moreover, the effect of pH on the photocatalytic activity of Bi2WO6/TiO2 NT was also investigated, and Bi2WO6/TiO2 NT showed highest photocatalytic activity at pH 6.0. (C) 2013 Elsevier B.V. All rights reserved.