Foxtail millet-derived highly fluorescent multi-heteroatoms doped carbon quantum dots towards fluorescent ink and smart nanosensor for selective ion detection

Zhiyi Chen, Zhiwei Zhao, Zhengluo Wang , Yanru Zhang, Xuan Sun, Linrui Hou, Changzhou Yuan

Index: 10.1039/C8NJ01072B

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Abstract

Carbon quantum dots (CQDs) are attracting enormous attentions as a smart material benefiting from their congenital virtues. Unfortunately, the low quantum yield (QY) and modest fluorescent stability seriously restrain their practically versatile applications. Herein, a facile yet green strategy has been developed for synthesizing nitrogen/sulfur/phosphrous (N/S/P) co-doped CQDs via hydrothermal treatment of natural foxtail millet without any extra additives or organic agents. The resultant N/S/P co-doped CQDs were endowed with remarkable excitation-dependent emission, high QY (~21.2%), superior fluorescence stability, and long lifetime (~2.05 ns) owing to multi-heteroatoms doping. Thanks to their strong blue-green fluorescence upon irradiation with UV light (365 nm), the water-soluble CQDs demonstrated huge potential in anticounterfeit application as a fluorescent ink. When utilized as a fluorescence sensor for cation determination, the multi-heteroatoms doped CQDs especially displayed the highest sensitivity and selectivity for the Fe3+ along with good linear correlation ranging from 5 to 150 μM and low detection limit of 0.046 μM. More remarkably, our fabricated high-quality CQDs would hold great promises in analytical and/or environmental fields.