Preparation and characteristics of ZnO nanoflowers

Abstract

Unlike the general substrates such as SiO2, ITO, and AZO, the metal foil used as a substrate is rarely studied in application in the substrate, however, it has lots of advantages including cheapness, good conductivity and excellent scalability. In this paper, an acanthosphere-like structure named ZnO nanoflowers is successfully synthesized on Cu foil by using chemical vapor deposition method. The gas flows with oxygen-argon ratios ranging from 1 : 150, 1 : 200, 1 : 250 to 1 : 400, which impacted on Cu foil, and the property of the ZnO nanoflowers are carefully studied. The SEM images shown that there are lots of ZnO nanorods grown on the sphere cores, and look like flowers. The ZnO nanoflowers contains uniformly sized ZnO nanorods and morphology with best flower structure when the oxygen/argon gas flow ratio is 1 : 250. Furthermore, the length-diameter ratio of the ZnO nanorods on the ZnO nanoflowers decreases as the oxygen-argon gas flow ratio decreases. The ZnO is of hexagonal wurtzite structure indicated by XRD pattern and there exist no other diffraction peaks existence except those from the Cu foil. In addition, the photoluminescence of ZnO nanoflower changes from a wave packet into a broad peak in the visible region when the oxygen-argon gas flow ratio between decreases. Further study of the photoluminescence by fitting the peaks in visible region with gaussian function indicates that the photoluminescence relating to the oxygen vacancy defects increases, but that relating to the zinc vacancy defects decreases. Therefore, the white light emitting device may be constructed based on the ZnO nanoflowers studied shown above. Finally, a possible model of the ZnO nanoflowers grown on Cu foil is proposed based on the experimental results.