Microwave hydrothermal synthesis of Sr2+ doped ZnO crystallites with enhanced photocatalytic properties

Pure and Sr2+ doped ZnO crystallites were successfully synthesized via a microwave hydrothermal method using Zn(NO3)2·6H2O and Sr(NO3)2·6H2O as source materials. The phase and microstructure of the as-prepared Zn1−xSrxO crystallites were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). Ultraviolet–visible spectrum (UV–vis) and photochemical reaction instrument were used to analyze the photocatalytic properties of the particles. XRD results show that the diffraction peaks of the as-prepared Zn1−xSrxO crystallites shifted slightly toward lower 2θ angle with the increasing of Sr2+ doping concentration from 0% to 0.3%. The pure ZnO crystallites with lamellar structure are found transforming to a hexagonal columnar morphology with the increase of Sr2+ doping concentration. UV–vis analysis shows that the particles have a higher absorption in UV region with a slightly decreased of optical band (Eg) gap. The photocatalytic activity of Sr2+ doped ZnO crystallites was evaluated by the Rhodamine B (RhB) degradation in aqueous solution under visible-light irradiation. Compared with the pure ZnO particles, the photocatalytic properties of the Sr2+ doped ZnO crystallites are obviously improved. The photocatalysis experiment results demonstrate that the 0.1% Sr2+ doped ZnO exhibits the best photocatalytic activity for the degradation of Rhodamine B.