Facile synthesis of nitrogen, sulfur co-doped carbon quantum dots for selective detection of mercury (II)

Developing carbon quantum dots with high throughput and quantum yields is important to boost their application in environmental detection. This study proposes nitrogen, sulfur co-doped carbon quantum dots as a fluorescent probe for mercury detection in an aqueous environment, which was synthesized by a facile and high-output tactic using methyl orange as a precursor for the first time. Results demonstrate that the obtained carbon quantum dots have a high selectivity, low detection limit of 237 nM, and fast response time, approximately 30 s, for trace mercury. The detection mechanism involves the synergistic action of static quenching, inner filter effect, and photo-induced electron transfer. Moreover, results show a high product yield (75.6%) and quantum yield (29.4%), which are higher compared to previous studies. These findings indicate that developed carbon quantum dots are promising sensing nanomaterials for mercury detection.