▎ 摘　　要

In this article, we report a feasible etching method to tune the bandgap of graphene quantum dots (GQDs). Since the bandgap in fluorescent carbon materials is dependent on the GQDs' size and chemical composition, GQDs with different sizes have been fabricated using the corresponding gold nanoparticle arrays as etching masks. During the O-2 etching process, the diameter of the GQDs decreased gradually accompanied by an increase in oxygen ratio. Femtosecond broadband transient absorption (TA) spectroscopy was used to investigate the variation trend in the bandgap of the GQDs. The present work affords an efficient route to investigate the photoluminescence (PL) mechanism of GQDs by tuning the size and surface chemical groups.