A ratiometric fluorescence sensor based on carbon quantum dots realized the quantitative and visual detection of Hg 2+

In this paper, based on the fluorescence of carbon quantum dots (CQDs) quenched by mercury ions (Hg2+ ) and the nonresponse of Hg2+ to rhodamine B fluorescence, a dual emission ratio fluorescence sensor was constructed to realize the quantitative detection of Hg2+ . Under excitation at 365 nm, the fluorescence spectrum showed 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 (S/N = 3) was 3.3 nM. In addition, this method could also realize the qualitative and semiquantitative detection of Hg2+ according to the fluorescence colour 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 excellent selectivity, anti-interference performance, and repeatability of the method.