Wet chemical synthesis of ultralong and straight single-crystalline ZnO nanowires and their excellent UV emission properties

Abstract

Ultralong and straight single-crystalline ZnO nanowires with diameters of 80–100 nm and lengths of over 10 µm (aspect ratios ∼100∶1) have been successfully synthesized by a simple hydrothermal treatment of the zinc carbonate hydroxide hydrate (Zn₄CO₃(OH)₆·H₂O) obtained via a precipitation reaction between the solutions of Zn(NO₃)₂·6H₂O and (NH₄)₂CO₃. No surfactants, templates or catalysts were used during the whole process. ZnO nanowires can be obtained under hydrothermal conditions of 180–200 °C for 20 h, but they can not be synthesized at 160 °C for 20 h and pure ZnO can not be obtained at 200 °C for 5 h. The growth direction of the ZnO nanowires is [0 1 −1 0]. A dissolution–recrystallization–decomposition–growth mechanism is suggested for the formation of the ZnO nanowires. The as-synthesized ZnO nanowires show a strong UV emission peaking at ∼392 nm using a Xe lamp as the excitation source at room temperature.