摘要： Quantum dots (QDs) are a class of zero-dimensional nanocrystal materials, whose lengths are limited to 2?10 nm. Their unique advantages such as wide excitation spectra, narrow emission spectra, and high quantum yield make their application possible in ?uorescence sensing, wherein QDs such as CdSe, CdTe, and CdS are used. Indeed, QDs have a wide range of applications in ?uorescence sensing, and there have been many reports of applications based on QDs as ion probes. The emission spectra of QDs can be adjusted by changing the size of the QDs or doping them with other ions/elements. However, the high toxicity of Cd and the poor anti-interference ability of single-emission ?uorescent probes greatly limit the applications of QDs in many ?elds. In this paper, ZnS QDs are doped with the rare-earth element Ce to form a low-toxicity double-emission ratiometric ?uorescent sensor, ZnS:Ce, for Hg2+ detection. The results of transmission electron microscopy (TEM), X-ray di?ractometry, X-ray photoelectron spectroscopy, and optical spectroscopy show that ZnS:Ce QDs were successfully synthesized. Under the optimal conditions, the concentration of Hg2+ was in the range of 10?100 μM, which had a linear relationship with the ?uorescence intensity of the ZnS:Ce QDs: the linear correlation coe?cient was 0.998, and the detection limit was 0.82 μM L?1. In addition, the ?uorescent sensor had good selectivity for Hg2+, and it was successfully applied to the detection of Hg2+ in laboratory water samples.