Sol-gel fabrication of Ag-Coated ZnO quantum dots nanocomposites with excellent photocatalytic activity

The development of metal/semiconductor photoactive materials has progressed remarkably with respect to heterogeneous photocatalysis . In this study, pristine ZnO quantum dots (ZQ) and Ag/ZQ nanocomposites with different Ag loadings were prepared using a cost-effective method. The synthesized samples were characterized using X-ray diffraction, high-resolution transmission electron microscopy, X-ray photoelectron spectroscopy, and electron paramagnetic resonance analyses. Photocatalytic experiments indicated that the Ag11/ZQ nanocomposite (Ag content of 11 wt%), exhibited excellent photocatalytic activity for methylene blue degradation. A combination of ultraviolet–visible spectroscopy, photoluminescence spectroscopy, electrochemical impedance spectroscopy , time-resolved photoluminescence analyses, and analog computational analysis were employed to propose the mechanism underlying the enhanced photocatalytic activity of Ag/ZQ nanocomposites. This was attributed to the effective charge transfer to the surface-decorated Ag, which efficiently suppresses electron–hole recombination in the ZQ, as well as oxygen vacancies (V O ) on the ZQ surface provide more reactive sites. Consequently, Ag/ZQ nanocomposites are promising photocatalytic materials for the removal of organic pollutants from wastewater.