Synthesis And Visible-Light-Driven Photoactivity Of Flower-Like Bi₂WO₆ Microspheres And Bi₂WO₆-Fe₂O₃ Composites

With the increasing concerns of environmental contamination and energy crisis, semiconductor photocatalysis as a green solution has been drawing great interests. However, this technology is mainly restricted by lower utilization rates of solar light, harder recovery of photocatalysts, and higher costs. Recently, the synthesis and modification of nano-micro hierarchical visible-light-driven photocatalysts are considered as the effective paths to solve these problems. Among the visible-light-driven photocatalysts, Bi₂WO₆ has been widely investigated due to its unique layered structure and relatively high visible-light catalytic activity. The research on the synthesis and modifications of Bi₂WO₆ nano-micro hiearachical structures shows great theoretical significance and application potential.In this work, {010}-oriented flower-like Bi₂WO₆ microsphere with high adsorptivity and visible-light photoactivity was initially prepared via a hydrothermal method without any additives under neutral environment. The influence of hydrothermal parameters on the morphology and structure was studied, and the dye molecule adsorption properties and the photocatalytic activity on Rhodamin B was investigated. Besides, the photocatalytic activity center on catalysis surface was analyzed through first-principles calculations.The results demonstrate that the morphology of flower-like Bi₂WO₆ can be controlled via adjusting hydrothermal temperature and time. According to first-principles calculation, Bi atoms at the surface of Bi₂WO₆ act as the center for the photocatalytic oxidation reaction under illumination. Additionally, rough surface, hierarchical structure, mesoporous structure and {010}-oriented facets preference of Bi₂WO₆ mainly contribute to the superior adsorptivity and visible-light photoactivity. The high adsorption for both rhodamin B and methylene blue implies the dye adsorption of flower-like Bi₂WO₆ microsphere is possible for working with the majority of dyes. It already shows a great potential in the application of environment cleaning.In order to improve the utilization of solar energy, α-Fe₂O₃ nanoparticles with an average diameter of about 50 nm were successfully synthesized on Bi₂WO₆ nanoplates through solvothermal method. The results show that the process of solvothermal reaction has almost no effect on microstructure and phase structure of flower-like Bi₂WO₆. The addition of α-Fe₂O₃ has greatly improved the range of visible-light response and degradation efficiency of Bi₂WO₆.