Photoelectrocatalytic degradation of bisphenol A in aqueous solution using a Au-TiO2/ITO film

A series of Au-TiO2/ITO films with nanocrystaline structure was prepared by a procedure of photo-deposition and subsequent dip-coating. The Au-TiO2/ITO films were characterized by X-ray diffraction, scanning electronic microscopy, electron diffraction, X-ray photoelectron spectroscopy, and UV-VIS diffuse reflectance spectroscopy to examine the surface structure, chemical composition, the chemical state of metal, and the light absorption properties. The photocatalytic activity of the Au-TiO2/ITO films was evaluated in the photocatalytic (PC) and photoelectrocatalytic (PEC) degradation of bisphenol A (BPA) in aqueous solution. Compared with a TiO2/ITO film, the degree of BPA degradation using the Au-TiO2/ITO films was significantly higher in both the PC and PEC processes. The enhancement is attributed to the action of Au deposits on the TiO2 surface, which play a key role by attracting conduction band photoelectrons. In the PEC process, the anodic bias externally applied on the illuminated Au-TiO2/ITO film can further drive away the accumulated photoelectrons from the metal deposits and promote a process of interfacial charge transfer.