The influence of narrow optical gap silver oxide on zinc oxide nanoparticles produced by microwave-assisted colloidal synthesis: photocatalytic studies

This paper reports a photocatalytic study on wide band gap zinc oxide (ZnO) incorporated by narrow band gap silver oxide (Ag₂O), namely Ag₂O/ZnO nanocomposites, which were prepared by colloidal synthesis with microwave supports. The Ag₂O/ZnO nanocomposites were prepared with three different molar ratios (MR) of Ag₂O to ZnO (MR: 0.25, 0.5 and 0.75). In order to confirm qualitatively the concentration ratio of Ag₂O in ZnO, crystal phase intensity ratio was executed by peak indexing from x-ray diffraction. The Ag₂O/ZnO nanocomposites properties were further investigated using diffuse reflectance spectroscopy. The nanocomposites were tested for the degradation of organic dyes solutions under visible and UV light irradiations. The photocatalytic activity of Ag₂O/ZnO nanocomposites under visible light increased with increasing molar ratio of Ag₂O to ZnO, while the opposite trends observed under UV light irradiation. The improvement of photoabsorption together with photocatalytic activities might be suspected due to the p-n heterojunction structure in Ag₂O/ZnO nanocomposites. The corresponding mechanism will be discussed in detail.