Novel magnetically recoverable BiOBr/iron oxides heterojunction with enhanced visible light-driven photocatalytic activity

In this study, novel magnetic BiOBr/Fe2O3 and BiOBr/Fe3O4 heterojunction composites were successfully synthesized by a simple solvothermal method. The characterization of the materials, based on their crystallite phase, chemical composition, morphology, and structure, indicated that the heterojunction structures were factually constructed. Under visible light irradiation, both composites exhibited significantly enhanced photocatalytic activity over BiOBr towards degradation of rhodamine B (RhB) and methyl orange (MO). In the case of RhB, 97.8% and 100% of RhB could be removed after 120 min irradiation in the presence of BiOBr/Fe2O3 and BiOBr/Fe3O4, respectively. A similar trend was observed for MO, with the degradation percentages of 91.7% and 100%, respectively, by BiOBr/Fe2O3 and BiOBr/Fe3 04 after 60 min. The extended visible light absorption range, investigated by UV-vis diffuse reflectance spectroscopy, was one of the factors responsible for the improvement of the photocatalytic performance. The formation of p-n junction between p-type BiOBr and n-type Fe2O3 or n-type Fe3O4 semiconductors could promote the effective separation of photogenerated electron-hole pairs. In addition, the superparamagnetic BiOBr/Fe2O3 and BiOBr/Fe3O4 composites can not only be easily isolated by an external magnetic field, but also maintained high activity after four recycles for the degradation of RhB and MO (C) 2014 Elsevier B.V. All rights reserved.