One-pot green synthesis of N,S co-doped biomass carbon dots from natural grapefruit juice for selective sensing of Cr(VI)

Abstract

The synthesis of biomass carbon dots (BCDs) using natural products has attracted increasing attention in the past few years owing to its advantages in terms of abundant sources and green environmental protection. However, the low luminescence quantum yield (QY) of BCDs is still a bottleneck for practical applications. Herein, nitrogen and sulfur co-doped biomass carbon dots (N,S-BCDs) with high QY (84.93%) were successfully prepared by one-pot green hydrothermal method using natural grapefruit juice and urea as carbon and nitrogen sources, respectively. The as-obtained N,S-BCDs showed an average size of 3.8 nm with strong blue luminescence and excitation-dependence fluorescence behavior. Furthermore, good selectivity and sensitivity were noticed toward hexavalent chromium (Cr(VI)) due to the dynamic quenching of fluorescence. The limit of detection (LOD) was determined as 0.155 μM, and the linearity was extended from 0 to 400 μM. Furthermore, the paper sensors for the visual semi-quantitative rapid detection of Cr(VI) were constructed by using the as-obtained N,S-BCDs, which reveals the great potential applications as fluorescent probes for the detection of heavy metal ions in the environment.