Research PaperHighly fluorescent N, S-co-doped carbon dots and their potential applications as antioxidants and sensitive probes for Cr (VI) detection

•The N, S co-doped carbon dots (N,SCDs) were synthesized from biomass and compound.•The N,SCDs have excellent antioxidant properties.•The N,SCDs are sensitive to detect trace of Cr (VI).

In this study, a facile synthesis of N, S-co-doped carbon dots (N, SCDs) from biomass was developed by hydrothermal treatment, using ammonium persulfate as passivator. The N, SCDs have favorable fluorescent properties including high quantum yield (18.7%) and idea fluorescent stability. In addition, the N, SCDs exhibit excellent radical scavenging activities against DPPH radicals, hydroxyl radicals and superoxide anion radicals. It is found that the fluorescence of N, SCDs can be effectively quenched by Cr (VI). The quenching mechanism could be explained due to the antioxidation of N, SCDs. Based on this feature, the selective and sensitive detection of Cr (VI) was performed, showing that a good linear relationship between fluorescence intensity of N, SCDs and Cr (VI) was achieved at the concentration from 1 to 40 μM. Furthermore, the detection was applied in real water samples (Taihu and tap waters), resulting in high sensitivity and good recoveries. In a word, this study provides more applications of N, SCDs in antioxidant fields and environmental fields for Cr (VI) detection.

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