A ratiometric fluorescence sensor based on carbon quantum dots realized the quantitative and visual detection of Hg2.

In this paper, based on the fluorescence of Carbon quantum dots (CQDs) would be quenched by mercury ions (Hg2+ ) and the non-response of Hg2+ to Rhodamine B fluorescence, a dual emission ratio fluorescence sensor was constructed to realize the quantitative detection of Hg2+ . Under the excitation light of 365 nm, the fluorescence spectrum show double emission peaks at 437 nm and 590 nm, corresponding to the fluorescence emissions of CQDs and Rhodamine B, respectively. This method quantitatively detected Hg2+ based on the linear relationship between the ratio of the intensities of the two emission peaks F437 /F590 and the concentration of Hg2+ . The detection range was 10~70 nM, and the limit of detection (LOD, S/N =3) was 3.3 nM. In addition, this method could also realize the qualitative and semi-quantitative detection of Hg2+ according to the fluorescence color change of the probe under ultraviolet light. After various evaluations, the method could be successfully applied to the quantitative and visual detection of Hg2+ in tap water, and demonstrated the excellent selectivity, anti-interference performance and repeatability of the method.