Structure-controllable synthesis of ZnO nanowires using water vapor in an atmospheric-pressure microwave plasma system

Abstract

Although the use of atmospheric-pressure microwave plasma to synthesize ZnO nanowires addresses various issues associated with conventional synthesis methods, it is difficult to obtain nanowires with controlled diameters and lengths. Herein, we investigated the effects of microwave input power and water vapor on the structure of ZnO nanowires grown using an atmospheric-pressure microwave plasma system. It was found that the aspect ratio of ZnO nanowires could be controlled by adjusting the plasma temperature and the amount of OH radicals. This method successfully produced ZnO nanowires in a structure-controllable manner with a wide range of aspect ratios from 10 to 340. Interestingly, we found that the sensitivity of the ZnO nanowires to UV irradiation was closely related to the morphology. In particular, the ZnO nanowires with high aspect ratios and densities showed excellent sensing characteristics.