Continuous synthesis of N, S co-coped carbon dots for selective detection of CD (II) ions

Abstract

Despite the rising interest in carbon dots (CDs) for applications as nano sensors, rapid and reproducible synthesis of CDs is a crucial problem forscalable production and practical application. The microreactor system was applied in this work for continuous synthesis of functionalized carbon dots with high monodispersity. Nitrogen and sulfur co-coped CDs were produced from L-cysteine and citric acid through coil microreactor in 10 min. The obtained N, S co-coped CDs had a shape of nearly sphere with an average diameter of 2.8 nm. The CDs exhibited bright blue fluorescence when excited upon ultraviolet light, reaching a high quantum yield at 68.2%. The fluorescence could be selectively quenched by Cd2+ and were demonstrated suitable for Cd2+ detection with high sensitivity and excellent selectivity. In this study, the N, S co-coped CDs reached the detection limit of 0.079 ppb within a wide linear range from 0 ppb to 300 ppb. In addition, this detection method held a strong anti-interference ability in complex ionic environments and was demonstrated low cell-toxicity, indicating promising applications in Cd2+ detection.