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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. [ABSTRACT FROM AUTHOR]

Hierarchical YVO4 microspheres have been prepared via L-aspartic acid (L-Asp) assisted hydrothermal route. X-ray diffraction (XRD), transmission electron microscopy (TEM) and scanning electron microscopy (SEM) were used to characterize the crystalline phase and morphologies of the products. The SEM results from different reaction stages indicate that YVO4 microspheres are self-assembled by numerous nanowires with diameter of 30-50 nm. It is found that the amount of L-Asp and reaction time play crucial roles in the formation of hierarchical nanowires-assembled YVO4 microspheres. The photocatalytic properties of YVO4 were investigated by the decomposition of Rhodamine B (RhB) under UV light irradiation and exhibit good photocatalytic activities. [ABSTRACT FROM AUTHOR]