Zinc oxide nanostructures: epitaxially growing from hexagonal zinc nanostructures.

The epitaxial growth of ZnO nanosheets and nanoneedles from a Zn/ZnO core/shell structure is verified by an experiment in which the ZnO nanoneedles and nanosheets are synthesized in air within an ultra-low temperature range from 250 to 400 °C by thermal oxidation of Zn films made up of hexagonal nanodiscs or nanoprisms. The hexagonal Zn structures are oxidized to form a Zn/ZnO core/shell structure with an epitaxial relationship; ZnO nanoneedles and nanosheets are found to grow epitaxially from the ZnO shell, along sixfold symmetric [Formula: see text] directions, showing the same lattice orientation as the Zn core. The stability difference among different facets of hexagonal Zn crystal structures plays a key role in the formation of ZnO nanosheets, nanoneedles and the Zn/ZnO core/shell structure, as well as ZnO hollow structures. A vapor-solid mechanism is suggested to explain the epitaxial growth process of the ZnO products. Photoluminescence properties of the ZnO nanostructures are also explored.