Growth of red-cell-like Bi2WO6 hierarchical architectures and their use as recyclable visible-light photocatalysts

Bismuth Tungstate (Bi₂WO₆) that was prepared by solid-state reaction at high temperature in previous work showed catalytic activity in the degradation of organic compound under visible light irradiation. During the past three years, some reports on the fabrication of Bi₂WO₆ nano-/microstructures in solution and their use as visible-light photocatalysts have emerged. Despite much progress in this exciting field, no report has discussed the repeating usage of this material to degrade organic compounds, partially due to the lack of well-defined Bi₂WO₆ structures. In this article, red-cell-like Bi₂WO₆ hierarchical architectures consisting of a number of square nanoplates of average ~30 nm in side length have been firstly synthesized by a hydrothermal method at 180degC for 12 h. These as-prepared microstructures have biconcave configurations with typical sizes of 1.8-2.5 mum, uniform and monodisperse. TEM examination indicates that the single-crystal subunit nanoplates with (001) as their two-dimensional (2D) surfaces assemble orderly using both their edges and faces. The good photocatalytic activity in the degradation of rhodamine B under visible light irradiation (lambdaGt400 nm) is also discussed. Furthermore, we show that these architectures can serve as effective and convenient recyclable photocatalysts, which is crucial to industrial applications. Only a slight decrease in the photodecomposition rate is observed after 5 cycles of the photocatalysis experiment. All these results demonstrate that the red-cell-like Bi₂WO₆ hierarchical architectures are promising visible-light-driven photocatalysts and have many potential applications in environmental protection.