Abstract:

Heterogeneous element doping is widely used in the modification of carbon quantum dots (CQDs) due to improving the fluorescence properties of CQDs. In this study, the nitrogen and sulfur co-doped carbon quantum dots (N,S-CQD) was prepared by electrochemical oxidation, in which Zhaotong lignite was selected as the carbon source, sodium chloride solution as the electrolyte and thiourea as the auxiliary respectively. The fluorescence quantum yield was 1.60%. The structure, composition and optical properties of N,S-CQD were studied by a variety of spectroscopic methods. N,S-CQDs were spherical particles with uniform size distribution and an average particle size of 1.66nm, in which C and O elements dominated as well as a certain amount of N and S elements. N,S-CQDs significantly absorbed in the UV region, and fluorescence analysis indicated that their optimum excitation wavelength and the emission wavelength located at 280nm and 313nm, respectively. N,S-CQDs were then applied to the detection of trace Fe³⁺ based on the quenching effect of Fe³⁺ on the fluorescence intensity. N,S-CQDs exhibited high selectivity and sensitivity for Fe³⁺ with the concentration range of 15—150μmol/L, and the minimum detection limit (L) was calculated to be 1.22μmol/L, indicating that N,S-CQDs could be utilized as a reliable candidate material for detecting trace Fe³⁺.

Key words: lignite, doped carbon quantum dots, electrochemical oxidation, Fe³⁺ detection

摘要：

异质元素掺杂可以有效改善碳量子点的荧光性能，被广泛应用于碳量子点的改性。选取昭通褐煤为碳源，氯化钠溶液为电解液，硫脲为助剂，采用电化学氧化法完成N、S共掺杂碳量子点（N,S-CQD）的制备，荧光量子产率为1.60%。采用多种表征方法研究了N,S-CQD的结构、组成和光学特性。首先在结构组成方面，N,S-CQD是一类球形颗粒，尺寸分布均匀，平均粒径为1.66nm，其中主要存在C、O元素，还存在部分N和S元素；其次在光学性质方面，N,S-CQD在紫外光区吸收明显，荧光分析显示其最佳激发波长为280nm，最佳发射波长为313nm。最后基于Fe³⁺对N,S-CQD的荧光猝灭效应，将N,S-CQD应用于痕量Fe³⁺的检测，N,S-CQD对15~150μmol/L浓度范围内Fe³⁺的检测表现出较高的选择性和灵敏度，通过计算得出最低检出限L=1.22μmol/L，表明N,S-CQD可应用于痕量Fe³⁺的检测。

关键词: 褐煤, 掺杂碳量子点, 电化学氧化法, Fe³⁺检测