Manganese Doped Zinc Sulfide Quantum Dots as Efficient Photocatalyst for Dye Decolorization

A simple aqueous based synthesis technique at room temperature was performed for preparation of pure and manganese (Mn²⁺) doped ZnS quantum dots in the presence of glutathione as the capping agent. Under UV-excitation quantum dots show photoluminescence bands at 2.13 and 3.0 eV corresponded to Mn²⁺ and intrinsic ZnS emission respectively. ZnS quantum dots were used as the photocatalyst to remove organic dyes in aqueous solution, with methylene blue as a model dye. The influence of the Mn²⁺ concentration on the dye degradation efficiency was studied. The highest photocatalytic degradation rate of methylene blue was obtained for ZnS quantum dots in glutathione shell doped with 0.125 at % of Mn²⁺.