N- and S-codoped carbon quantum dots for enhancing fluorescence sensing of trace Hg 2

• Published in: Physical chemistry chemical physics : PCCP 2023-10, Vol.25 (41), p.28230-28240
• Main Authors: Wang, Yujie, Xu, Guoliang, Zhang, Xinghe, Yang, Xiaona, Hou, Hongbo, Ai, Wei, Zhao, Liju
• Format: Article
• Language: English
• ISSN: 1463-9076; 1463-9084
• DOI: 10.1039/D3CP02924G

Carbon-quantum-dot-based fluorescence sensing of Hg 2+ is a well-known cost-effective tactic with fast response and high sensitivity, while rationally constructing heteroatom-doped carbon quantum dots with improved fluorescence sensing performances through tuning the electronic and chemical structures of the reactive site still remains a challenging project for monitoring trace Hg 2+ in aquatic ecosystems to avoid harm resulting from its high toxicity, nonbiodegradabilty and accumulative effects on human health. Herein, intriguing N,S-codoped carbon quantum dots were synthesized via a facile one-step hydrothermal procedure. As an admirable fluorescent probe with plentiful heteroatom-related functional groups, these N,S-codoped carbon quantum dots can exhibit an absolute fluorescence quantum yield as high as 11.6%, excellent solubility and stability over three months, remarkable sensitivity for Hg 2+ detection with an attractive detection limit of 0.27 μg L −1 and admirable selectivity for Hg 2+ against thirteen other metal ions. Density functional theory calculations reveal that electron-enriched meta -S of the unique graphitic N with homocyclic meta -thiophene sulfur structure can regulate this N site to have more electrons and preferable affinity towards Hg, hence achieving enhanced fluorescence quenching due to greater charge transfer from N to Hg after the coordination interaction. This strategy provides a promising avenue for precisely designing purpose-made quantum dots with the dedicated fluorescence sensing applications.