Sonochemical Green Method for Preparation of Mg-Doped ZnO Nanostructures in Water with Enhanced Photocatalytic Activity

In this work, Mg-doped ZnO nanostructures were prepared in water under ultrasonic irradiation for 60 min without using any organic compounds or post preparation treatments. The prepared samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive analysis of X-ray (EDX), diffuse reflectance spectroscopy (DRS), and Fourier transform-infrared (FT-IR) techniques. Powder XRD patterns display that ZnO has wurtzite hexagonal crystalline phase and loading of Mg2+ ions does not change its crystalline phase. The SEM and TEM images represented that morphology of Mg-doped ZnO nanostructures remarkably is different from the undoped one. Photocatalytic activities of the samples were investigated by degradation of methylene blue under UV irradiation. The degradation rate constant on Mg-doped ZnO nanostructures increases nearly 2.5-fold relative to the undoped one. Influence of various operational parameters, such as ultrasonic irradiation time, calcination temperature, and pH of the solution on the degradation activity was investigated and the results discussed. Finally, the results showed that the holes and hydroxide radicals are the main species in degradation of the pollutant.