Preparation of Ag/ZnMgO nanocomposites as novel highly efficient photocatalysts by one-pot method under microwave irradiation

A series of Ag/Zn0.85Mg0.15O (Ag/ZnMgO) nanocomposites with different contents of metallic silver (0.85, 1.7, 3.4, and 6.7 wt%) were prepared in water using a one-pot method under microwave irradiation for 5 min. This large-scale method is fast and does not use any post preparation treatments. The X-ray diffraction (XRD) patterns have peaks corresponding to wurtzite hexagonal crystalline ZnO and cubic Ag. Purity and composition of the prepared samples were verified by energy dispersive X-ray (EDX). The scanning electron microscopy (SEM) and transmission electron microscopy (TEM) images show that morphology of the samples changes by adding silver element. The diffuse reflectance spectroscopy (DRS) studies demonstrate that by increasing the amount of Ag, the absorption in the visible range increases. Electrochemical impedance spectroscopy (EIS) data show that in the presence of magnesium and silver elements, interfacial charge transfer resistance decreases relative to ZnO nanostructures. Activity of the nanocomposites for degradation of methylene blue was evaluated under UV irradiation. The degradation rate constant on Ag (3.4 wt%)/ZnMgO nanocomposite is about 11.2, 4.7 and 9.6-fold greater than those of ZnO, ZnMgO and Ag (3.4 wt%)/ZnO photocatalysts, respectively. In addition, influence of various operational parameters on the degradation rate constant was investigated and the results were discussed.