Room Temperature Phosphorescence Sensor for Hg2+ Based on Mn-Doped ZnS Quantum Dots

Mercury pollution is one of the most serious concerns to human health and the environment. The development of highly sensitive and selective sensors to detect toxic mercury ions has been the focus of scientific research. In this study, L-cysteine-capped Mn-doped ZnS quantum dots (QDs) have been synthesized and used for the room temperature phosphorescence detection of Hg2+. The phosphorescence of the Mn-doped ZnS QDs could be selectively quenched in the presence of Hg2+. Under optimal conditions, good linear correlations were obtained over the concentration range from 2.0 x 10(-8) mol/L to 4.5 x 10(-6) mol/L with a detection limit of 3.8 x 10(-9) mol/L. Additionally, the long lifetime of the phosphorescence of the Mn-doped ZnS QDs can avoid the interference of the autofluorescence and scattering light of the background, which facilitates their application in real samples. The possible quenching mechanism was examined by UV-vis absorption spectra and Rayleigh scattering spectra.