▎ 摘　　要

A simple, economical and efficient method is introduced for the functionalization of graphene quantum dots (GQDs). The GQDs was synthesized by the thermal pyrolysis of citric acid then mono-ethanolamine (MEA) was used to functionalize its surfaces. The resultant MEA-functionalized GQDs (MEA-GQDs) had remarkable fluorescence emissions with high quantum yield. The interaction studies showed that the fluorescence emissions of MEA-GQDs quenched selectively in the presence of Hg2+ ions due to the complex formation of Hg2+ ion with functional groups on MEA-GQDs. Further studies showed that, in the presence of ethyl xanthate ions (EtX-), the intensity was recovered because of the formation of a stronger complex between the thiol group of EtX- and Hg2+ ions and the dissociation of the previous weaker complex between MEA-GQDs and Hg2+ ions. In the optimal conditions, Hg2+ and EtX- ions could both be detected in the concentration ranges of 0.05-5 and 0.05-3 A mu M with limits of detection of 10 and 30 nM, respectively. The new MEA-GQDs-based nanosensor was successfully applied for the determination of Hg2+ and EtX- ions in spiked groundwater as a real sample with the satisfactory recovery of 97.6-101%.