Magnetically recoverable Bi2WO6-Fe3O4 composite photocatalysts: Fabrication and photocatalytic activity

Three-dimensional (3D) hierarchical Bi2WO6-Fe3O4 microspheres were successfully synthesized by a simple hydrothermal route. These microspheres with average diameters of 2-3 mu m are constructed by Bi2WO6 nanosheets, which are decorated by Fe3O4 nanoparticles with an average diameter of 150 nm. Morphological modulation of the obtained products could be easily realized by tuning the pH value of the reaction system. The photocatalytic properties of the composites were studied with the photo-degradation of Rhodamine B (RhB) as a probe reaction. Comparing with bulk Bi2WO6 (SSR-Bi2WO6) and TiO2 (P25), Bi2WO6-Fe3O4 microspheres show improved photocatalytic activity under visible light irradiation, and can efficiently catalyze the degradation of RhB up to 98.6% within 150 min. Kinetic analysis reveals that the reaction rate constant k of Bi2WO6-Fe3O4 microspheres is over three times that of P25 and nearly seven times that of SSR-Bi2WO6. The Bi2WO6-Fe3O4 photocatalyst can be easily re-collected from the reaction system upon applying an external magnetic field. This kind of composite photocatalysts with easiness of separation can have potential applications in water treatment and environmental cleaning. (C) 2012 Elsevier B.V. All rights reserved.