Chinese Journal of Applied Chemistry ›› 2022, Vol. 39 ›› Issue (6): 980-989.DOI: 10.19894/j.issn.1000-0518.210263

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Synthesis of Sulfur and Nitrogen Doped Carbon Dots for Cu(Ⅱ) Detection

Hai-Yan QI1(), Chen-Qi ZHANG1, Jin-Long LI2, Jun LI3   

  1. 1.Qiqihar University Institute of Chemical Engineering,Qiqihar 161006,China
    2.Key Laboratory of Fine Chemicals of College of Heilongjiang Province,Qiqihar 161006,China
    3.Heilongjiang Industrial Hemp Processing Technology Innovation Center,Qiqihar 161006,China
  • Received:2021-05-31 Accepted:2021-09-27 Published:2022-06-01 Online:2022-06-27
  • Contact: Hai-Yan QI
  • About author:E⁃
  • Supported by:
    the Fundamental Research Funds in Heilongjiang Provincial Universities(300882);the Program for Science and Technology of Qiqihar(GYGG?201903)


Nitrogen and sulfur co-doped blue fluorescent carbon dots (NS-CDs) for detection of copper ion in real samples were prepared by the hydrothermal method using citric acid as the carbon source. The structure, composition and optical properties of NS-CDs were characterized by high-resolution transmission electron microscopy, X-ray diffraction, infrared absorption spectroscopy, X-ray photoelectron spectroscopy, and fluorescence spectroscopy. The results show that the NS-CDs have amorphous carbon structure, high dispersibility, and its particle size is in the range of 0.6~2.2 nm. There are carboxyl, hydroxyl and amide functional groups on NS-CDs′ surfaces. The C, N, O and S element contents of NS-CDs are 54.01%, 24.49%, 19.39% and 2.11%, respectively. NS-CDs show good fluorescence stability for the irradiation by ultraviolet light, pH value, and ionic strength, and the fluorescence quantum yield is 25%. Cu2+ could interact with the functional groups on NS-CDs, resulting in the aggregation/network structure and causing quenching of fluorescence intensity. A fluorescence analysis method is established to detect Cu2+ with linear ranges of 0~10, 10~50 and 50~100 μmol/L, respectively. The detection limit is achieved as 41 nmol/L (S/N=3), which meets the Chinese guidelines for Cu2+ in soil in Environmental Quality Standard for Soils. The method is successfully applied in detection of Cu2+ in soil samples with recoveries of 104.9%~105.6%. The copper ion concentration is 2.55 μmol/L. The method is rapid, sensitive and highly selective for detection of Cu2+.

Key words: Carbon dots, Fluorescence quenching, Copper ions, Detection

CLC Number: