Bifunctional Nitrogen and Fluorine Co-Doped Carbon Dots for Selective Detection of Copper and Sulfide Ions in Real...

Copper ions (Cu²⁺) and sulfur ions (S^2-) are important elements widely used in industry. However, these ions have the risk of polluting the water environment. Therefore, rapid and quantitative detection methods for Cu²⁺ and S^2- are urgently required. Using 2,4-difluorobenzoic acid and L-lysine as precursors, nitrogen and fluorine co-doped dots (N, F-CDs) were synthesized in this study via a hydrothermal method. The aqueous N, F-CDs showed excellent stability, exhibited satisfactory selectivity and excellent anti-interference ability for Cu²⁺ detection. The N, F-CDs, based on the redox reactions for selective and quantitative detection of Cu²⁺, showed a wide linear range (0-200 μM) with a detection limit (215 nM). By forming the N, F-CDs@Cu²⁺ sensing platform and based on the high affinity of S^2- to Cu²⁺, the N, F-CDs@Cu²⁺ can specifically detect S^2- over a linear range of 0-200 μM with a detection limit of 347 nM. In addition, these fluorescent probes achieved good results when used for Cu²⁺ and S^2- detection in environmental water samples, implying the good potential for applications.