Production of few-layer graphene by supercritical CO2 exfoliation of graphite

In this study, the authors report a supercritical CO2 processing technique for intercalating and exfoliating layered graphite. Few-layer graphene is produced by immersing powdered natural graphite in supercritical CO2 for 30 min followed by rapidly depressurizing the supercritical fluid to expand and exfoliate graphite. The graphene nanosheets are collected by discharging the expanding CO2 gas directly into a solution containing dispersant sodium dodecyl sulfate (SIDS) to avoid restacking. Atomic force microscopy (AFM) shows that the typical graphene sheet contains about 10 atomic layers. This technique offers a low-cost, simple approach to large-scale production of pure graphene sheets without the need for complicated processing steps or chemical treatment. (C) 2009 Elsevier B.V. All rights reserved.