High Stability and Strong Fluorescence of Carbon Nanodots as Nanosensor for Hg²⁺ in Environmental Waters

Pollution of toxic heavy-metal ions such as mercury ions (Hg²⁺) is well known to severely threaten ecological environment and human health. Correspondingly, development of a fast and sensitive method for detecting heavy-metal ions is urgently needed and has been received widespread attention in recent years. In this study, carbon nanodots (CDs) with strong blue fluorescence were synthesized by a microwave-assisted hydrothermal method. The as-prepared blue fluorescent CDs not only have excellent stability (e.g. photostability, salt stability and pH stability), but also have extremely high selectivity and sensitivity for probing Hg²⁺ via fluorescence quenching. Specifically, fluorescence of CDs is gradually quenched along with the increase in Hg²⁺ concentration, and a low concentration of Hg²⁺ can be identified (with low detection limit, 15 nM). Therefore, the novel fluorescent CDs could be developed for detecting Hg²⁺ in aqueous conditions, and have great potential for fast probing Hg²⁺ in environmental samples.