▎ 摘　　要

Here we report a bottom-up method to synthesize colloidal graphene quantum dots (GQDs) using microplasmas at ambient conditions. As-produced colloidal GQDs show 4.9 nm averaged diameter and exhibit room-temperature photoluminescence that peaks at 448 nm with a quantum efficiency of 1.5%. Solvated electrons (e(aq)(-)) generated by the microplasma interacting with the precursor solution were found to be critical for the GQD formation. Our study provides a simple method to synthesize colloidal GQDs and the insight to understand the fundamental factors involved in nano-sized graphene synthesis by microplasma-assisted liquid phase chemistry. (C) 2019 Elsevier Ltd. All rights reserved.