S,N-Codoped Carbon Dots Derived From Acetone and Thiourea via Solvothermal Method: A Fluorescent Probe for Ag+ Ion Detection.

High concentrations of silver ions can lead to adverse effects on the skin, digestive system, nervous system, and other bodily functions at high concentrations. Therefore, it is crucial to monitor their concentration in water. This study has identified sulfur and nitrogen codoped carbon dots (S,N-CDs), which achieved optimal fluorescent performance with a fluorescence quantum yield as high as 37.9%. The amino (-NH₂) and mercapto (-SH) groups on the surface of S,N-CDs, which contain lone pair electrons, readily coordinate with silver ions to form complexes. Furthermore, a strong linear relationship is observed within the concentration range of 0.001-450 μM, making this method suitable for detecting silver ion concentrations. This study presents a cost-effective, easy-to-prepare, efficient, and selective fluorescent sensor for detecting silver ion concentrations, with potential applications in monitoring silver ions in water.