Synthesis and Characterization of Flower-Like ZnO Microspheres Assembled by Nanosheets

This study demonstrates a facile but effective hydrothermal method for the synthesis of zinc oxide (ZnO) nanosheets (tens of nanometer in thickness) and their assembly microspheres (10-40 mu m in diameter) on the surface of metallic zinc (Zn) foil. The morphology, microstructure, and composition of the as-synthesized products are studied by various advanced experimental techniques, such as X-ray diffraction (XRD), scanning electron microscope (SEM), and transmission electron microscope (TEM). The possible formation mechanism of the ZnO microsphere is briefly discussed, and the growth direction of nanosheets is along < 100 >, confirmed by high-resolution TEM technique. The influence of various experimental parameters including reaction temperature, time, type and concentration of zinc salts on the morphology and size of the synthesized products are investigated. Finally, photoluminescence spectrum of such nanostructures is measured and shows a weak UV emission peak at similar to 382 nm and a strong purple emission peak at similar to 393 nm. The findings will be useful for the synthesis of other semiconductors under mild conditions.