One pot synthesis of highly fluorescent N doped C-dots and used as fluorescent probe detection for Hg2+ and Ag+ in aqueous solution

• Highly luminescent N-doped carbon dots were prepared by an efficient one-step route. Sensitive and selective sensing of Hg2+ and Ag+ was achieved.
• The mechanism of the Hg2+ and Ag+ sensing was studied.
• The quenched fluorescence of the NCDs by Hg2+ and Ag+ can be recovered by adding EDTA solution.
• The probe is applied to detection for Hg2+ and Ag+ in real environmental water samples.

A kind of biocompatible fluorescent nitrogen doped carbon quantum dots (NCDs) has been synthesized using uric acid as raw material through a facile, effective and green thermal treatment method in one pot. The surface morphology and optical properties of the synthesized NCDs were characterized. Without further chemical modification, the NCDs emit bright blue fluorescence with a high quantum yield of 56% due to the enhancement effect of N dopant atoms on a surface of carbon quantum dots. Owing to the strong blue fluorescence, negligible toxicity and the special response of heavy metal ions, the NCDs have been used as a fluorescence probe for sensitive and selective detection of Hg2+ and Ag+ ions with detection limit of 4.8 nM and 1 nM, respectively. Moreover, it was successfully applied to determination of Hg2+ and Ag+ in real environmental water samples, which offers the advantages of simplicity and cost efficiency.