Catalyst-free synthesis of honeycomb-like and straight ZnO nanowires

Honeycomb-like ZnO nanowire arrays and straight nanowires were directly grown on the carbon-coated Si substrates without the aid of any metal catalysts, revealing an interesting growth behavior. It is found that one-dimensional (1D) nanostructures can easily grow on the carbon surface at different temperature region mainly due to the large difference in interface energy between the ZnO and C surface. Both the honeycomb-like nanowire arrays and straight nanowires exhibit excellent ultraviolet (UV) quality and common defect-related green emissions are almost not detected, indicating their perfect crystalline nature.