High quality graphene with large flakes exfoliated by oleyl amine.

Large-flake graphene membranes up to 300 microm(2) can be exfoliated from graphite by oleyl amine based on solvothermal conditions. The exfoliated graphene sheets are of high quality and have few defects. The graphene dispersion, predominantly composed of monolayer graphene, had a high concentration of 0.15 mg ml(-1), and can be stabilized against re-aggregation.