Development of ZnO Nanostructured Films via Sodium Chloride Solution and Investigation of Its Growth Mechanism and Optical Properties

The controllable formation of zinc oxide (ZnO) nanostructures and nanowires by a cheap and environmental friendly fabrication method of simply subjecting metallic zinc films in sodium chloride (NaCl) solution at 170°C from 3 to 15 h under hydrothermal conditions is demonstrated in this study. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) indicate that ZnO films with different morphologies are obtained: from a film with network of circular pores to a film with nanowire-like network with bigger pores. It is observed that heating duration has an effect on its photoluminescence (PL) properties. Ultraviolet emission is observed for all ZnO films. Green emission surfaces after heating for 6 h, which subsequently disappears after 15 h of heating. It is suggested that the morphology change over different heating durations is responsible for the rise and subsequent decline in green emissions. Lastly, the growth mechanism behind zinc oxidation and morphology change is proposed and investigated with the aid of experimental method. It is verified that pitting corrosion is responsible for the growth mechanism here.