Kinetically controlled synthesis of bismuth tungstate with different structures by a NH4F assisted hydrothermal method and surface-dependent photocatalytic properties

[Display omitted] •Bi2WO6 with different morphologies are synthesized by a NH4F assisted hydrothermal method.•The effects of NH4F are systematically investigated.•The NH4F employed are of significant effect on controlling the reaction kinetics.•Two different growth mechanisms are proposed for the obtained samples.•The obtained samples show different photocatalytic activities on decomposing RhB. Controlled synthesis of well-shaped nanocrystals is of significant importance to understand the surface-related properties. Herein, hierarchical Bi2WO6 particles with different morphologies, such as flower-like and pancake-like morphologies were selectively prepared using a simple fluoride ion-assisted hydrothermal process. Morphological modulation of the samples could be easily realized by controlling the initial amount of NH4F. The effect of NH4F as well as the formation mechanism of these Bi2WO6 hierarchical structures were systematically investigated. The morphological control of the final products are proved to be a kinetic control of the reaction, which is closely related to the concentration of fluoride ion in the solution. The as-obtained hierarchical Bi2WO6 particles exhibit different visible-light-driven photo-catalytic activities for the degradation of Rhodamine-B (RhB). The differences in photo-catalytic activities among the as-obtained samples are associated the surface adsorption properties, which result from the synthetic conditions.