Understanding the high chemi-catalytic reactivity of graphene quantum dots to rapidly generate reactive oxygen species

•Nitrogen-doped graphene quantum dots (N-GQD) were prepared by an efficient mechanochemical approach via the ball mill.•The unique structures of the N-GQDs can rapidly generate large amounts of ROS.•The N-GQDs can generate a large amount of ROS only in the presence of acid.•The N-GQDs have catalytical capacity for the hydrothermal synthesis of MIL-101(Cr).