Shape-controlled synthesis of bare ZnO nanomaterials with improved photoactivity and photostability

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Understanding the growth mechanisms of nanomaterials usually leads to the successful preparation of targeted micro-structures with excellent properties. In this paper, flower-like and roughly spherical ZnO nanocrystals have been successfully synthesised through facile wet chemical methods, i.e. hydrothermal pathways and homogeneous precipitation method. The photocatalytic activities of the prepared photocatalysts were evaluated by degradation of rhodamine B (RhB) and phenol under ultraviolet (UV) irradiation. Remarkably, the ZnO powder via homogeneous precipitation (urea/Zn 2+ = 2.0) exhibited better photocatalytic performance and photostability than those of flower-like ZnO substrate. The enhanced photocatalytic properties could be attributed to more active catalytic sites and effective separation of carriers, which were confirmed by low-temperature nitrogen adsorption, photocurrent responses, and photoluminescence spectral analysis. A possible mechanism for the excellent photocatalytic activity of ZnO substrates was proposed.