Shape-selective synthesis of Bi2WO6 hierarchical structures and their morphology-dependent photocatalytic activities

Various morphologies of Bi2WO6 including packed nanoplates, three dimensional (3D) hierarchical flower-like and clew-like microspheres were successfully synthesized through a simple hydrothermal route using L-lysine as a structure-directing agent. It was found that the morphological modulation of the as-prepared products could be easily realized by adjusting the solution pH values of the precursors. On the basis of a series of time-dependent experiments, the possible mechanisms for the formation of three different structures were proposed. The photocatalytic activities of the different morphologies of Bi2WO6 were evaluated by photodegradation of Rhodamine B (RhB) solution under visible light irradiation (lambda > 400 nm). In comparison with clew-like and plate-like Bi2WO6 structures, Bi2WO6 with a hierarchical flower-like architecture exhibited the highest visible-light-photocatalytic activity. The enhanced photocatalytic activity could be mainly ascribed to the unique structural features of flower-like microspheres with hierarchical architectures.