▎ 摘　　要

Nitrogen-doped graphene quantum dots (N-GQDs) were synthesized by the hydrothermal method. The results of the transmission electron microscope and atomic force microscopy indicated that the average diameter and height of the homogeneously distributed N-GQDs were approximately 5 nm and less than 10 nm, respectively. The results of the X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy confirmed the successful incorporation of the N element into GQDs. The aqueous solution of N-GQDs dispersed in water remained stable and homogeneous at room temperature for 3 months. N-GQDs had a higher fluorescence intensity than GQDs and presented low toxicity and the survival rate of cells (3T3-Swiss albino) was more than 85% in the cytotoxicity test. To better understand the luminescence mechanism, the band gaps of GQDs and NGQDs were calculated using the density functional theory (DFT). The effect of the pH value on the fluorescence intensity of N-GQDs before and after the addition of Fe3+ ions was investigated. N-GQDs were applied to selectively detect Fe3+ ions, and the results exhibited a wide linear correlation between the fluorescence intensity and the Fe3+ concentration of 0-100 uM with a detection limit of 0.74 uM. This study provided a simple and efficient synthesis method and proved the ultra-high Fe3+ detection selectivity and sensitivity of N-GQDs, offering the experimental and theoretical basis for N-GQDs' applications in biosensing, bioimaging, environmental monitoring, etc.