Study of rapidly synthesis of ZnO nanorods by microwave hydrothermal method and photocatalytic performance

Nano-zinc oxide materials have been widely studied and applied due to their excellent photocatalytic properties. In this study, ZnO nanorods were rapidly synthesized via a microwave-assisted hydrothermal method, using Zn(OH)₂ precursor and ZnO seeds that were prepared by zinc sulfate, zinc acetate, and zinc hydroxide as raw materials. The morphology, nanostructure, and optical properties of ZnO nanorods were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and UV-vis spectroscopy. To investigate the effect of microwave irradiation on the photocatalytic activity of the ZnO nanorods, the photocatalytic properties of the samples were tested by degrading rhodamine B (RhB) under ultraviolet and visible light for about 80 min. The experimental results indicate that Zn(OH)₂ precursor and ZnO seeds can be successfully converted into a three-dimensional cage structure based on the self-assembly of ZnO nanorods in 30 min with microwave irradiation reaction. Compared with the conventional method of synthesizing ZnO nanorods, the samples under microwave irradiation featured a better crystallinity performance. The UV-vis results show that microwave radiation can cause a red shift of the absorption edge of synthesized ZnO nanorods and reduce the band gap energy, thereby enhancing the photocatalytic activity and efficiency of the ZnO nanorods. The photocatalytic test results indicate that ZnO nanorods synthesized by the microwave-assisted hydrothermal method have a better efficiency of light absorption; the samples have a better degradation rate of rhodamine B under the ultraviolet and visible light irradiation. The degradation efficiency of rhodamine B by ZnO nanorods could reach 98.5% within 80 min under ultraviolet light irradiation. The microwave-assisted synthesis method can allow to synthesize a large amount of ZnO nanorods materials in a short time, and it has the advantages of high-efficiency batch preparation and environmental friendliness.