Synthesis of Porous and Visible-Light Absorbing Bi2WO6/TiO2 Heterojunction Films with Improved Photoelectrochemical and Photocatalytic Performances

This work reports the preparation of porous and visible-light absorbing Bi2WO6/TiO2 heterojunction films as a photoelectrode and their photoelectrochemical and photocatalytic performances. The Bi2WO6 underlayers with high surface roughness were prepared by a superhydrophilicity-assisted method. The Bi2WO6/TiO2 bilayer films showed high interface area between the Bi2WO6 and TiO2 layers. Significant enhancement in visible light photocurrent generation on the optimal Bi2WO6/TiO2 film was observed as compared with unmodified Bi2WO6 (a factor of 2) and unmodified TiO2 (a factor of 13) films. The optimal visible-light photocatalytic activity of the Bi2WO6/TiO2 film was 15.1 nm of stearic acid degraded, which was 6 and 4.6 times higher than that of unmodified Bi2WO6 and TiO2 films, respectively. The enhanced photoelectrochemical and photocatalytic performances of Bi2WO6/TiO2 films were attributed to the improved charge separation efficiency derived from the suitable valence band interaction between the two semiconductors, as well as high interface area and porous structure of the heterojunction bilayer films. Charge separation between Bi2WO6 (underlayer) and TiO2 (overlayer) was verified by photoluminescence (PL) and current−voltage (I−V) characteristics studies.