Nitrogen and boron co-doped carbon dots probe for selectively detecting Hg2+ in water samples and the detection mechanism

Mercury ions represent hazardous contaminants with significant adverse effects on human health, wildlife, and vegetation. Therefore, it is crucial to create a sensitive and trustworthy technique for identifying mercury ions. In this study, nitrogen and boron co-doped carbon dots (N,B-CDs) were created via a one-step hydrothermal approach, employing citric acid, polyethyleneimine, and boric as precursors. The resulting N,B-CDs exhibited spherical morphology with an average diameter of 2.60 nm and emitted blue fluorescence with peak emissions at 442 nm (lambda(em)) upon excitation at 360 nm (lambda(ex)), yielding a fluorescence quantum yield of 27.34%. Remarkably, N,B-CDs, without any surface modifications, functioned as a direct "turn-off" probe, enabling swift, highly selective Hg2+ detection. The N,B-CDs probe could measure Hg2+ in the linear ranges of 0.40-22 mu M and 22-208 mu M , with a detection limit of 0.12 mu M. The detection mechanism was attributed to dynamic quenching interactions between N,B-CDs, and Hg2+. Additionally, the probe was used to detect Hg2+ in both tap and river water, and the recovery rates ranged from 87.20 to 108.20% (RSD <4.89%). These findings highlighted the method's considerable practical potential for detecting Hg2+ in environmental water.