Sulfur and nitrogen co-doped carbon quantum dots as the chemiluminescence probe for detection of Cu2+ ions

Herein, we investigated the direct chemiluminescence (CL) of sulfur and nitrogen co-doped carbon quantum dots (S,N-CQDs) induced by some common oxidants. The results showed that KMnO4 can produce much more intensive CL than other oxidants. The mechanism of the CL reaction was proposed based on the UV–vis, fluorescence and CL emission spectra. Moreover, the effect of some metal ions on the S,N-CQDs–KMnO4 CL system was studied and found that the CL intensity of this system was significantly declined by Cu2+ ions. Based on this effect, a simple and selective CL sensor was established for the detection of trace amount of Cu2+ in the concentration range of 0.01–0.5 mg L−1 with a limit of detection (3 s) of 2.1 µg L−1. The method was exploited for the determination of Cu2+ in human plasma and water samples with satisfactory results.