▎ 摘　　要

Graphene quantum dots containing nitrogen (NGQDs) were synthesized by the hydrothermal method. AFM, TEM and XPS were employed to investigate the morphology and composition of NGQDs, and their optical properties were studied by UV-Vis and photoluminescent (PL) spectroscopy. AFM and TEM images showed that NGQDs were about 8.9 nm in size and 0.6-2.0 nm in thickness (1-3 layers graphene). The result of XPS showed that nitrogen content in NGQDs was similar to 17% and nitrogen existed mainly in the form of "pyrrolic N". Spectroscopy experiments indicated that excitation spectra of NGQDs were similar to their absorption spectra, and their emission spectra were excitation-independent. In addition, quantum yield of NGQDs was calculated to be similar to 18%, increasing with the content of nitrogen in NGQDs increase. Furthermore, the lifetime decay curve was well fitted to a double exponential decay curve (tau(1)=2.93 ns, tau(2)=9.00 ns), which indicates that there are two feature chromophores in NGQDs. The chromophores are sp(2) clusters with oxygen groups and pyrrolic ring.