Influence of the nature of defects in ZnO nanocrystals synthesized by chemical bath deposition on photocatalytic activity

Abstract

We investigated the influence of various native defects in ZnO nanocrystals with homogeneous morphological properties on the structural, optical and photocatalytic characteristics of ZnO nanocrystals. In the photoluminescence spectrum of as-grown ZnO nanocrystals, a yellow emission band (YB) was observed, corresponding to interstitial oxygen (volume defect). When the ZnO nanocrystals were annealed at 200 °C, this YB disappeared and the NBE emission intensity increased. When ZnO nanocrystals were annealed at a temperature of 500°С, a green emission band appeared in the photoluminescence spectrum. This emission band belongs to oxygen vacancies, and this defect is located in the surface or subsurface of the nanostructure (surface defect). Studies have shown that the photocatalytic properties of ZnO nanocrystals depend on the nature of the native defects, and the increase in the concentration of defects and the appearance of surface defects lead to an increase in the photocatalytic activity of the sample.