Double 3-fold-symmetry novel ZnO hierarchical nanostructure arrays: Synthesis, characterization, and photoluminescence properties

We successfully fabricated a novel highly regular ZnO hierarchical nanostructure with six rows of single crystal ZnO nanowire (NW) arrays in double 3-fold-symmetry, using a two-stage synthesis scheme without any catalyst and chemical reagent. Our synthesis employs a simple thermal evaporation of Zn powder and chemical vapor deposition (CVD) followed by post-annealing. In the first stage, Zn-rich ZnO nanotubes are formed; then in the annealing stage, the resulting Zn-rich ZnO nanotubes provide the backbones and the supply of Zn to grow ZnO NWs. A growth model for ZnO hierarchical nanostructure based on dense arrangement principle is proposed. This novel nanostructure has strong violet emission, high surface area and specific geometric structures. These make it suitable for application on chemical sensors, battery electrodes, solar cells and optoelectronic devices.

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► Using a two-stage synthesis strategy without catalyst and chemical reagent to fabricate ZnO hierarchical nanostructures.
► Successfully fabricated a novel highly regular ZnO hierarchical nanostructure with 6 rows of single crystal ZnO nanowire arrays in double 3-fold-symmetry, which has not been reported elsewhere.
► Propose a growth model for this nanostructure based on dense arrangement principle.
► These nanostructures have a strong violet emission, benefiting from EX-Zni transforms to a relative higher Zni energy level after annealing.