Production of few-layer graphene by supercritical CO 2 exfoliation of graphite

Abstract

In this study, the authors report a supercritical CO 2 processing technique for intercalating and exfoliating layered graphite. Few-layer graphene is produced by immersing powdered natural graphite in supercritical CO 2 for 30 min followed by rapidly depressurizing the supercritical fluid to expand and exfoliate graphite. The graphene nanosheets are collected by discharging the expanding CO 2 gas directly into a solution containing dispersant sodium dodecyl sulfate (SDS) 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.