Processable Aqueous Dispersions of Graphene Stabilized by Graphene Quantum Dots

Abstract

Dispersing graphene in various solvents is one of the key technologies toward the practical applications of graphene. Herein, using graphene quantum dots (GQDs) as stabilizer, aqueous dispersions of graphene with good stability were demonstrated by directly dispersing commercialized graphene powder into water. Amazingly, 100 mg of graphene powder could be stabilized by an average of merely 7.8 mg GQDs to form aqueous dispersions with a maximum concentration of up to 0.4 mg/mL and stability at least 3 months. The introduction of a small amount of GQDs also allowed for the fabrication of water-redispersible graphene slurry and powder, which would largely facilitate the transportation and applications of graphene. The mechanism of the GQDs stabilized graphene in water was proposed and experimentally verified through UV–visible spectroscopy and zeta potential measurements. Moreover, flexible graphene papers directly assembled from the water-dispersible graphene exhibited controllable thickness, good conductivity, and acceptable strength. With properties not compromised by GQDs, water-dispersible graphene is expected to be widely applicable in electrical and electrochemical device fields.