Chem. J. Chinese Universities ›› 2023, Vol. 44 ›› Issue (2): 20220464.doi: 10.7503/cjcu20220464

• Analytical Chemistry • Previous Articles     Next Articles

Conjugate Size and Surface Oxidation Synergistically Trigger Red Fluorescence in Carbon Dots for Detecting Trace Water in Organic Solvents

FU Fangmei1, XU Mengru1, LIANG Zishan1, HUANG Sirui1, LI Hui1, ZHANG Haoran1,2, LI Wei1,2, ZHENG Mingtao1,2, LEI Bingfu1,2()   

  1. 1.Key Laboratory for Biobased Materials and Energy of Ministry of Education /Guangdong Provincial Engineering Technology Research Center for Optical Agriculture,College of Materials and Energy,South China Agricultural University,Guangzhou 510642,China
    2.Maoming Branch,Guangdong Laboratory for Lingnan Modern Agriculture,Maoming 525000,China
  • Received:2022-07-08 Online:2023-02-10 Published:2022-09-15
  • Contact: LEI Bingfu E-mail:tleibf@scau.edu.cn
  • Supported by:
    the National Natural Science Foundation of China(52102042);the Independent Research and Development Project of Maoming Laboratory, Guangdong Laboratory for Lingnan Modern Agriculture, China(2021ZZ004);the Key Realm Research & Development Program of Guangdong Province, China(2021B0707010003);the Guangdong Provincial Science and Technology Project, China(2021A0505050006)

Abstract:

In this paper, o-phenylenediamine and dopamine hydrochloride were used as precursors, and the pH values of the reaction system(pH=7, 3, 1) were adjusted by phosphoric acid to obtain carbon dots(CDs) with gradually red-shifted fluorescence, namely CDs-7(green), CDs-3(orange) and CDs-1(red), respectively. Trans-mission electron microscopy(TEM), Raman spectroscopy(Raman), Fourier transform infrared spectroscopy (FTIR), X-ray electron spectroscopy(XPS), UV-Vis absorption spectrum and fluorescence lifetime decay curves analysis demonstrated that the decrease of the reaction system pH promoted the precursor carbonization and cross-linking, which led to the increase of sp2 conjugate domain size and graphitization, resulting in the fluorescence red-shift of CDs. In addition, the acidic environment favors the formation of carboxyl groups by oxidation on the surface of CDs, which further promotes the red-shift of CDs fluorescence while improving the quantum efficiency(QY). Finally, because of its high QY(14.8%) and solvent-dependent luminescence, CDs-1 was used as a fluorescent probe to detect trace water in ethyl alcohol(EtOH), NN-dimethylformamide(DMF) and 1,4-dioxane(DIO), with detection limits of 0.86%, 0.123% and 0.023% respectively. It is proved that CDs-1 has great potential in the detection of trace water.

Key words: Carbon dots, Fluorescent probe, Trace water, Fluorescence redshift

CLC Number: 

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