N/Ti3+ co-doping biphasic TiO2/Bi2WO6 heterojunctions: Hydrothermal fabrication and sonophotocatalytic degradation of organic pollutants

This study describes the one-step in situ hydrothermal construction of N/Ti3+ co-doping biphasic TiO2/Bi2WO6 heterojunctions (NT-TBWx) and investigates their sonophotocatalytic degradation of organic contaminants in water. The obtained samples are characterized in detail including X-ray photoelectron spectroscopy, X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and Ultraviolet diffuse reflectance spectroscopy, etc. Their photocatalytic, sonocatalytic, and sonophotocatalytic performance are compared by the degradation of organic pollutants and found the degradation rate according to the order: photocatalysis < sonocatalysis < sonophotocatalysis. In addition, NT-TBWx samples present better sonophotocatalytic activity for the removal of methylene blue (MB), p-Nitrophenol, Rhodamine B, and levofloxacin compared with that of NT-TiO2 and pure TiO2. Especially, the highest sonophotocatalytic degradation rate is demonstrated for NT-TBW1. Additionally, the excellent stability of NT-TBWx samples is demonstrated by four cycles of sonophotocatalytic measurements with a tiny decline. Superoxide radical (center dot O-2(-)) is found to dominate the sonophotocatalytic degradation process of MB. The synergic effect among the doping level, heterophase junction, and heterojunctions as well as between sonocatalysis and photocatalysis contribute to superior sonophotocatalytic activity. This work provides a new alternative architecture of TiO2-based nanomaterials and promotes their application in environmental issues. (C) 2019 Elsevier B.V. All rights reserved.