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

Ultralong and straight single-crystalline ZnO nanowires with diameters of 80-100 nm and lengths of over 10 mum ( aspect ratios similar to100:1) 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).6H(2)O and (NH4)(2)CO3. No surfactants, templates or catalysts were used during the whole process. ZnO nanowires can be obtained under hydrothermal conditions of 180-200degreesC for 20 h, but they can not be synthesized at 160degreesC for 20 h and pure ZnO can not be obtained at 200degreesC 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 similar to392 nm using a Xe lamp as the excitation source at room temperature.