氮掺杂石墨烯量子点对Cr(Ⅵ)的选择性检测

Nitrogen-doped graphene quantum dots for selective detection of Cr(Ⅵ)

为制备生物兼容性良好的Cr(Ⅵ)离子检测材料,以柠檬酸为碳源,以氨水为氮源,采用水热法制备了具有良好水溶性和荧光性能的氮掺杂石墨烯量子点(N-GQDs).以N-GQDs作为荧光探针,基于Cr(Ⅵ)能够使荧光探针的荧光发生淬灭的原理,实现对水溶液中Cr(Ⅵ)的选择性检测.研究水热温度、反应时间、溶液的pH值对N-GQDs荧光性能的影响,并借助傅里叶红外光谱(FTIR)、X射线电子能谱(XPS)表征了氮掺杂石墨烯量子点的化学信息.结果表明:随着水热温度、反应时间、pH值的增加,N-GQDs的荧光强度先增大后降低;在水热温度180℃、反应时间10 h、pH=7.0时,氮掺杂石墨烯量子点的荧光性能最好,此时该荧光探针在水溶液中的最低检测限可达到50 nmol/L.

In order to prepare the detection material with good biocompatibility for Cr （Ⅵ） ion, the nitrogen -doped graphene quantum dots （N-GQDs） were synthesized by hydrothermal method using critic acid as carbon source and ammonia as nitrogen source. The obtained N-GQDs have good water-soluble and perfect fluorescence properties. Using N-GQDs as the fluorescent probe, the selective detection of Cr （Ⅵ） in aqueous solution was based on the principle that the fluorescence of N-GQDs can be quenched by Cr （Ⅵ）. The effects of hydrothermal temperature, reaction time and pH value of the solution on the fluorescence intensity of N-GQDs were also studied. The microstructures of N-GQDs were characterized by Fourier transform infrared spectroscopy （FTIR） and X- ray photoelectron spectroscopy （XPS）. The experimental results indicated that with the increase of the hydrot- nermal temperature, reaction time and pH value, the fluorescence intensity of N -GQDs firstly increased and then decreased; when the hydrothermal temperature was 180 ℃,reaction time was 10 h, and the pH was 7.0, the N -GQDs had the highest fluorescence intensity. Under the optimum conditions, the N -GQDs fluorescent probe has detection limit as low as 50 nmol/L in aqueous solution.