Zn-catalysed growth and optical properties of modulated ZnO hierarchical nanostructures

Modulated ZnO hierarchical nanostructures have been successfully synthesised by the one-step thermal evaporation method.The ZnO hierarchical nanostructures consist of large quantities of high-dense nanowires strewn with some small balls, and these balls are connected with wires by short rods.The composition detection results show that the ball is metallic Zn, which further confirms that Zn can serve as the catalyst for vapour-liquid-solid growth of the ZnO hierarchical nanostructures.The photoluminescence spectrum of the modulated ZnO hierarchical nanostructures includes a weak ultraviolet peak centred at 380 nm and a strong green emission centred at 500 nm, which can be attributed to the exciton emission at the near-band edge and a mass of singly ionised oxygen vacancies in products, respectively.