Cu doped ZnO hierarchical nanostructures: morphological evolution and photocatalytic property

Abstract

Copper doped ZnO hierarchical nanostructures have been synthesized with a facile solution route at room temperature. Structural properties of the as-synthesized nanostructures have been studied X-ray diffraction, field emission scanning electron microscopy with energy dispersive. Meanwhile, light-absorption properties were studied with UV–Vis absorption spectroscopy. Photocatalytic performance of Cu-doped ZnO hierarchical nanostructures were evaluated by the light-driven degradation of methylene blue. The results indicated that Cu doping lead to the augment of average crystallite size of ZnO crystals. Moreover, morphological evolution of ZnO nanostructures was found with the addition of Cu ions. The photocatalytic test showed that there is an optimum Cu doping concentration which results in the enhancement of photocatalytic performance of Cu doped ZnO hierarchical nanostructures, compared with pristine ZnO. A novel and reasonable mechanism was proposed. It is believed that the enhanced photocatalytic performance of Cu doped ZnO hierarchical nanostructures can be attributed to the formation of acceptor level (Cu2+–Cu+) in the midgap of ZnO, which improved the utilization of light and separation efficiency of photogenerated electron hole pairs.