Chinese Journal of Applied Chemistry ›› 2021, Vol. 38 ›› Issue (2): 202-211.DOI: 10.19894/j.issn.1000-0518.200223

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Preparation of Green Carbon Quantum Dots from Corn Starch and Hydrogen Ion/Hydroxyl Ion Regulated Fluorescent Switch Performance

HAO Li-Juan, WANG Ting, DONG Guo-Hua*, ZHANG Wen-Zhi*, BAI Li-Ming, DU Hai-Yao, LANG Kun, LI Xin   

  1. College of Chemistry and Chemical Engineering & Heilongjiang Provincial Key Laboratory of Catalytic Synthesis for Fine Chemicals, Qiqihar University, Qiqihar 161006, China
  • Received:2020-07-27 Accepted:2020-11-12 Published:2021-02-01 Online:2021-04-10
  • Supported by:
    National Natural Science Foundation of China (No.21776144), the Research Foundation of Education Bureau of Heilongjiang Province of China (No.135509505), the Special Project of Advantage Characteristic Discipline of Heilongjiang Province (No.YSTSXK201841), the College Students' Innovative Entrepreneurial Training Plan Program of Qiqihar University (No.202010232046) and the Innovation Project of Graduate Education of Qiqihar University (Nos.YJSCX2020028, YJSCX2019034)

Abstract: Green fluorescent carbon quantum dots (G-CQDs) were synthesized from corn starch and oxalic acid via an ethanol solvothermal method. The morphology, composition and structure of G-CQDs were analyzed using transmission electron microscopy (TEM), Fourier transform infrared spectrometer (FT-IR), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy. The results show that G-CQDs are quasi-spherical nanoparticles with the particle size of about 2~5 nm and have graphene-like structure with abundant water-soluble groups such as C—O and O—H on the surface. The fluorescence measurement assay results exhibit that the synthesized G-CQDs display strong fluorescence emission at ~520 nm with the excitation wavelength of 385 nm, and the emission intensity increases first and then decreases with the decrease of the concentration of G-CQDs. The fluorescence quantum yield of the synthesized G-CQDs can reach up to 38.5%. Moreover, the fluorescence emission of G-CQDs exhibits various decay behaviors with the varied concentration of H+ and OH-. Therefore, the synthesized G-CQDs can be utilized as the reversible “off-on” switch probe for the detection of H+ and OH-.

Key words: Carbon quantum dots, Hydrogen ion, Hydroxyl ion, Fluorescence quenching, Reversible off-on switch

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