Loading of metallic silver onto ZnO for enhancement of electron population and photocatalytic activity

Abstract

ZnO is a well-known metal oxide for photocatalysis purpose. In a real setting, nonetheless, its photocatalytic activity is still rather poor, and thus, needs to be improved. In this research, ZnO is loaded with metallic Ag with varied Ag loading amount through a one-pot hydrothermal route for the improvement of photocatalytic activity. Various characterization techniques, including synchrotron XANES, XPS, XRD, Raman, ICP-OES, DRS, Raman, light-induced IR, SEM, and HR-TEM, are employed for elucidating the physicochemical features of the prepared samples. XPS and XANES confirm that the oxidation state of the loaded Ag is 0, while HR-TEM confirms the presence of Ag in the form of nanoclusters with a size of about 3 nm on the ZnO surface. An enhanced population of photoexcited electrons is observed following the Ag loading. Upon the Ag loading, the photocatalytic activity of ZnO for the mineralization of several recalcitrant organic compounds is also enhanced. Volcano-like enhancement patterns of the electron population and photocatalytic activity are present. The electron population is linearly correlated with photocatalytic activity, confirming the electron population, and thus the presence of metallic Ag, for controlling the photocatalytic activity of Ag-loaded ZnO.