Controllable topological transformation from BiOCl hierarchical microspheres to Bi2WO6 superstructures in the Bi-W-Cl-O system

In this work, three-dimensional (3D) Bi2WO6 superstructures assembled by nanosheets were prepared using the topological transformation of BiOCl hierarchical microspheres via a facile one-pot solvothermal method. Interestingly, it was found that the transformation process experienced three stages including BiOCl, BiOCl/Bi2WO6 composites and Bi2WO6 with increasing solvothermal time at 150 degrees C, which was confirmed by X-Ray Diffraction (XRD), Raman spectrometer and Transmission Electron Microscopy (TEM) results. Importantly, the crystal growth of Bi2WO6 superstructures occurred at the exposed (001) facets of BiOCl nanosheets with WO66 units replacing the interlaminar Cl atoms. Also, the growth mechanism was revealed and discussed in the thermodynamic and kinetic dynamic aspects. Compared with BiOCl superstructures, the BiOCl/Bi2WO6 composites and Bi2WO6 superstructures showed better photocatalytic activity in the degradation of benzene gases under visible-light irradiation owing to the existence of visible-light-active Bi2WO6. This topological transformation by regulating the solvothermal synthetic conditions may provide a new insight into the controllable synthesis of other 3D compounds. (C) 2015 Elsevier B.V. All rights reserved.