Controlled synthesis of three-dimensional hierarchical Bi2WO6 microspheres with optimum photocatalytic activity

Three-dimensional (3D) hierarchical Bi2WO6 microsphere and octahedral Bi2WO6 have been synthesized by a facile hydrothermal method using KNO3 solution and distilled water as solvent, respectively. The obtained products were characterized by X-ray diffraction, scanning electron microscopy, N2 adsorption/desorption, and UV–vis diffuse reflectance spectroscopy in detail. The concentration of KNO3 played a key role in the formation of 3D hierarchical Bi2WO6 microspheres. A possible formation mechanism of Bi2WO6 microsphere was proposed. The photocatalytic activity of the as-synthesized products was evaluated by monitoring the degradation of MB solution under sunlight irradiation. It was found that the photocatalytic activity of the 3D hierarchical Bi2WO6 microsphere was superior to the octahedral Bi2WO6, which was attributed to the larger surface area and special hierarchical structure of Bi2WO6 microsphere.