Coupling immobilized TiO2 nanobelts and Au nanoparticles for enhanced photocatalytic and photoelectrocatalytic activity and mechanism insights

A visible light responsive nanocomposite was prepared by depositing Au nanoparticles on the surface of immobilized anatase TiO2 nanobelts (TiO2 NBs/Au NPs). The designed materials were characterized by field-emission scanning electron microscopy, transmission electron microscopy, X-ray diffraction, diffuse reflectance UV-vis spectroscopy and photoluminescence spectra. The photoelectric properties were investigated by photoelectrochemical measurement. The results reveal that the Au NPs with diameter of 5-15 nm were uniformly deposited on the surface of TiO2 NBs. Compared to bare TiO2 NBs, a stronger visible light absorption and a higher photoelectrochemical response were achieved over TiO2 NBs/Au NPs. The TiO2 NBs/Au NPs nanocomposites exhibit higher photocatalytic activity than TiO2 NBs under irradiation of simulated solar light and visible light, respectively. Moreover, the prepared photocatalyst exhibits super reusability. The possible radical species involved in the degradation of Tetrabromobisphenol A (TBBPA) were analyzed by active species trapping. It is indicated that the degradation of TBBPA was primarily driven by hydroxyl radicals and holes. Meanwhile, it is interesting to find that the modification of Au NPs can contribute to enhancement of the direct utilization of photoexcited holes. The possible intermediates or products were identified by LC-MS, and the tentative degradation pathways of TBBPA were proposed. It is hoped that our work could offer valuable information on the design of efficient, recyclable and visible light responsive photocatalyst. (C) 2013 Elsevier B.V. All rights reserved.