Yolk-shell ZnWO4 microspheres: one-pot synthesis, characterization and photocatalytic properties

Novel yolk-shell ZnWO4 microspheres have been fabricated via a one-pot hydrothermal process in the presence of L-aspartic acid (L-Asp). The as-obtained products were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, nitrogen adsorption-desorption experimentation and UV-vis absorption spectroscopy. The effects of the reaction conditions on the morphology and crystallinity of the products were studied, as well as the amount of L-Asp, reaction time and reaction temperature. As the chelating agent and shape modifier, L-Asp plays a key role in the crystal growth of the yolk-shell ZnWO4 microspheres. A possible formation mechanism for the yolk-shell microspheres is proposed. The photocatalytic properties of the yolk-shell ZnWO4 microspheres were investigated by the decomposition of Rhodamine B (RhB) and methylene blue (MB) under UV light irradiation and the results show that they have excellent photocatalytic activities. Furthermore, the obtained yolk-shell ZnWO4 microspheres are chemically stable and the efficiency remained almost the same after being recycled five times, suggesting that the yolk-shell ZnWO4 microspheres are promising photocatalysts for practical applications.