Unraveling excitation-dependent fluorescence of nitrogen and sodium co-doped carbon dots for dual detection of Fe3+ and Ag+

Carbon dot-based fluorescence sensors show great potential for developing metal ion detectors. This study focuses on developing a nanoprobe for the dual detection of different metal ions by harnessing the excitation-dependent fluorescence (EDFL) behavior of nitrogen and sodium co-doped carbon dots (N:Na-CDs). N:Na-CDs were synthesized using a microwave-assisted hydrothermal technique. The synthesized N:Na-CDs exhibited desirable functional groups containing nitrogen and sodium. Both experimental and computational results demonstrate that the presence of nitrogen and sodium-containing groups can modify N:Na-CDs' electronic and chemical structures, thereby inducing EDFL behavior. Interestingly, the different fluorescence centers of N:Na-CDs as a single nanoprobe can be effectively used for selective and sensitive Fe3+ and Ag+ detection under 360 and 440 nm excitation wavelengths, respectively. The limit of detection (LOD) of Fe3+ and Ag+ separately was found as 0.25 and 0.14