Scotch-tape-like exfoliation effect of graphene quantum dots for efficient preparation of graphene nanosheets in water

As a simple and eco-friendly strategy, the production of graphene nanosheets (GNs) by liquid-phase exfoliation (LPE) faces a challenge to the improvement of exfoliation yield for scalability, as well as the stable dispersibility for application. Herein, we electrochemically prepare a kind of graphene quantum dots (GQDs) with undestroyed crystalline structure on basal plane and a number of hydrophilic functional groups at edge, to exfoliate and disperse GNs in water with a high yield of 89-100%. The obtained GNs show a conductivity of 1.2 x 10(5) Sm-1 and water dispersibility of 1.0 mg mL(-1) for over one month, due to the firm adsorption of amphiphilic GQDs, which have non-covalent pi-pi bond interaction with graphene basal plane and strong H-bonds with water. The lateral size, functional groups and defect nature of GQDs have great influence on GNs and a scotch-tape-like exfoliation mechanism is proposed. GQDs as green stabilizer and exfoliation agent can effectively acquire the high-quality GNs and promote their potential application.