水溶性氮掺杂石墨烯量子点的合成及其对Pb^(2+)的选择性识别研究

Synthesis of Water Soluble Nitrogen-doped Graphene Quantum Dots and Its Fluorescence Recognition of Pb^(2+)

以氧化剥离碳纤维法制备的石墨烯量子点(GQDs)为原料,以N,N-二甲基甲酰胺(DMF)为氮源和溶剂,采用溶剂热法,制备了氮掺杂的水溶性石墨烯量子点(N-GQDs)。当反应时间小于24h时,N-GQDs的氮掺杂量和发光量子效率随反应时间的延长而增大,同时其荧光颜色逐渐从黄色向绿、蓝转变。N-GQDs的发光量子效率最高可从GQDs的4.0%增加到30.1%。氮掺杂一方面增加了N-GQDs中C—N键含量,另一方面增强了N-GQDs的结构有序性,从而提高了其发光量子效率。作为荧光探针,N-GQDs对水溶液中的Pb^(2+)具有良好的识别作用。荧光滴定实验证明,在8.0×10-7 mol/L^1.5×10-4 mol/L的线性范围内,以NGQDs为荧光探针,可以有效测定水溶液中Pb^(2+)的浓度。与未掺杂的GQDs相比,氮掺杂显著提高了石墨烯量子点对Pb^(2+)的选择性。

In this paper,a facile approach for producing the nitrogen doped graphene quantum dots(N-GQDs)was carried out through solvothermal treatment.The graphene quantum dots(GQDs)derived from carbon fibers in N,N-dimethylformamide.The nitrogen content and the fluorescent quantum yield(QY)could be enhanced by prolonging the reaction time,and simultaneously the fluorescent color of the N-GQDs changed from orange to green and blue.Compared with low QY of 4.0%of GQDs,high QY of 30.1%could be reached by the blue fluorescent N-GQDs with the nitrogen content of 7.7%with solvothermal treatment of 24 h.Doping with nitrogen not only increase the content of C-N bonds,but also enhance the order of the structure,thus inceasing the fluorescent QY of N-GQDs.As a fluorescent probe,the N-GQDs could selectively detect the Pb 2+in aqueous solution.The N-GQDs fluorescence probe could be used to determine the level of Pb 2+in water sample in the range of 8.0×10-7 mol/L to 1.5×10-4 mol/L.Compared with the GQDs,the selectivity of the N-GQDs to Pb 2+was enhanced by the nitrogen doping.