Effect of Experimental Parameters on the Hydrothermal Synthesis of Bi2WO6 Nanostructures.

Bi2WO6 nanostructures were synthesized by a hydrothermal route, where the effect of various experimental parameters on the products was investigated. It is demonstrated that the sample morphology and size is highly dependent on the NaOH content (or pH value). At C NaOH = 0-0.0175 mol (pH range of 1-4), the prepared samples present flower-like hierarchical microspheres which are constructed from thin nanosheets via the self-assembly process. The size of the hierarchical microspheres exhibits a decreasing trend with increasing the NaOH content, from 7 μm at C NaOH = 0 mol to 1.5 μm at C NaOH = 0.0175 mol. At C NaOH = 0.03-0.0545 mol (pH: 5-9), the prepared samples exhibit irregular flake-like structures, and their size increases with the increase in NaOH content. At C NaOH = 0.055-0.05525 mol (pH: 10-11), the prepared samples are composed of uniform sphere-like particles with an average size of 85 nm. Compared to the NaOH content, the reaction temperature and time has a relatively small effect on the product morphology and size. The photocatalytic activity of the samples was evaluated by degrading rhodamine B (RhB) under irradiation of simulated sunlight. Among these samples, the samples composed of flower-like hierarchical microspheres have relatively high photocatalytic activity. In particular, the microspheres prepared at C NaOH = 0.01 mol exhibit the highest photocatalytic activity, and the degradation percentage reaches 99 % after 2 h of irradiation.