▎ 摘　　要

A facile, rapid method based on a liquid-liquid extraction system for the purification of graphene quantum dots is reported in this study. Nitrogen-doped graphene quantum dots (N-GQDs) were synthesized by a simple hydrothermal route for cutting graphene oxide sheets. Then, through the liquid-liquid extraction system of tetrahydrofuran-(NH4)(2)SO4-water, N-GQDs have been successfully purified. The as-prepared N-GQDs have an average size of 6 nm and exhibit optimum excitation and emission wavelengths of 330 and 435 nm, respectively. N-GQDs were demonstrated as a sensitive fluorescent sensing probe for Fe3+. The sensor can detect Fe3+ (R-2 = 0.992) in the concentration range of 0.2-30 mu M, with a detection limit of 0.06 mu M. This method of quantitative analysis of Fe3+ has good linearity and reliable reproducibility.