Enhanced sunlight-driven photocatalytic activity of (Cu, TM) (TM = Mg, Mn, Ag) dual-doped ZnS quantum dots for multi-dye degradation and improved reusability through PVA polymer Integration

Abstract

This study investigates the potential of transition metal-doped ZnS quantum dots (QDs) for solar energy harvesting, focusing on their large surface area and unique optical properties. Using a simple co-precipitation method, Cu-doped and (TM, Cu) dual-doped ZnS QDs were synthesized, with TM representing Mg, Mn, and Ag. Comprehensive characterization, including XRD, TEM, EDAX, XPS, and UV–Vis spectroscopy, confirmed successful doping and the cubic phase of ZnS, with crystallite sizes between 1.39 and 1.60 nm. The doping enhanced the band gaps due to quantum confinement, ranging from 3.65 to 4.09 eV. We focused on photocatalytic degradation of crystal violet dye, where (Ag, Cu) dual-doped QDs showed 99 % efficiency in 100 min. Kinetic analysis identified these QDs as superior, with a high rate constant and short half-life. Additionally, an innovative PVA/QDs membrane demonstrated degradation efficiencies of 62 % to 95 %, showing promise for environmental cleanup under solar illumination.