Controllable photoexfoliation of monolayer graphene quantum dots using temporally and spatially shaped femtosecond laser

Graphene quantum dots (GQDs) have displayed significant momentum in numerous fields due to their unique electronic properties. However, how to obtain uniformly monolayer quantum dots and explain the synthesis mechanism are still a key technical problem. Here, a rapid and controllable photoexfoliation rate of monolayer graphene quantum dots of up to 80 % was achieved by using temporally and spatially shaped femtosecond laser to ablate bulk highly oriented pyrolytic graphite targets in liquid. Theoretical calculations suggested that the temporally shaped laser can minimize the spatial range of electron excitation, maximize the Coulomb repulsion between the outer layers and Coulomb explosion within the topmost layer through multi-level electron excitation. The above multilevel photoexfoliations lead to the formation of monolayer GQDs. These findings demonstrate a perfect theoretical explanation of controllable and rapid preparation of monolayer quantum dots, accelerating its industrialization in energy storage devices. • A new way to prepare monolayer graphene quantum dots was proposed through temporally and spatially shaped femtosecond laser. • Rapid, controllable photoexfoliation of monolayer graphene quantum dots rate up to 80 %, which is benefited from the spatial optical field improves the effective area. • The photoexfoliation mechanism revealed by simulation shows that temporally shaped laserminimizes electron excitation range, maximizes the Coulomb repulsive force via multi-level electron excitation. • The method for preparing monolayer quantum dots has material applicability, accelerating the quantum dots industrialization in energy storage devices.