부산대학교 도서관

Graphical abstract We report the synthesis of nitrogen-doped grapheme quantum dots and its applications in the highly selective and sensitive detection of Hg(II) and paraquat in water samples. Highlights • Nitrogen doped graphene quantum dots (N-GQDs) were synthesized by one-step hydrothermal treatment of GO and ammonia. • High sensitive and selective sensing of Hg2+ and paraquat was achieved. • It was low detection limit of 23 nM and 19 μg L−1 for Hg2+ and paraquat, respectively. • It was successfully applied for the detection of Hg2+ and paraquat in environmental water samples. Abstract A simple and rapid fluorescence "on-off-on" approach for sensing Hg2+ and paraquat was designed by using nitrogen doped graphene quantum dots (N-GQDs) and N-GQDs/Hg2+ system, respectively. It was found that the fluorescence of N-GQDs solution was quenched in the presence of Hg2+ ions (turn off), and the quenched N-GQDs/Hg2+ system was recovered after addition of paraquat (turn on), due to the higher affinity of paraquat and Hg2+ than that of N-GQDs and Hg2+ that resulting into the release of Hg2+ from the surface of N-GQDs and the fluorescence recovery of N-GQDs. The developed fluorescence "on-off-on" approach exhibited high selectivity and sensitivity for detection of Hg2+ and paraquat. Under the optimum experimental conditions, good linearities were achieved over the range of 0–4.31 μM for Hg2+ and 0.05–2.0 μg mL−1 for paraquat, respectively. The detection limits for Hg2+ and paraquat were 23 nM and 19 μg L−1, respectively, and the recoveries of Hg2+ and paraquat spiked in real samples ranged from 95% to 105.8%. Results of this study suggested that the highly selective and sensitive fluorescence "on-off-on" approach can be used to the detection of Hg2+ and paraquat in real environmental water samples. [ABSTRACT FROM AUTHOR]