Production of pristine graphene quantum dots from graphite by a shear-mixer in supercritical CO2.

Graphical abstract Highlights • Pristine graphene quantum dots were prepared using a shear-mixer in supercritical CO 2. • The PL quantum yield achieved 8.6% measured against the standard quinine sulfate. • The mechanism for forming the PGQDs was elucidated. Abstract Graphene quantum dots exhibit unique electronic and optical properties due to their combined properties of quantum confinements and edge effects and have broad applications like bio-imaging, drug delivery, biosensors and photovoltaic applications. In this paper, we presented a facile and green preparation of pristine graphene quantum dots (PGQDs) from graphite using a shear-assisted supercritical CO 2 approach. The effects of the pressure, graphite amount, and shearing speed on the yield of the PGQDs were investigated. The fluorescence quantum yield of the PGQDs achieved 8.6%, and it was highly stable with blue light emission. The mechanism for forming the PGQDs was elucidated. [ABSTRACT FROM AUTHOR]