Morphology-controlled synthesis of ZnO 3D hierarchical structures and their photocatalytic performance

ZnO 3D hierarchical structures assembled by different low-dimensional building blocks (nanosheet, nanoneedle) have been successfully synthesized at room temperature without the addition of organic agents. The morphology of the hierarchical structures can be well controlled by simply changing the concentration of the reactant. On the basis of the experimental results, a possible mechanism for the formation of the ZnO 3D hierarchical structures is proposed. The room temperature photoluminescence spectra of the ZnO 3D hierarchical structures show that the relative intensity of UV emission increases from nanosheets to the thin needle flowers and can be tuned by controlling the morphology. Importantly, the thin needle flowers sample exhibits an enhanced photocatalytic performance as compared with the other ZnO nanostructures due to structural features and good optical quality.