Graphene layers from thermal oxidation of exfoliated graphite plates

Graphite platelets of 1–5 μm in diameter consisting of a few graphenes were generated from commercially available exfoliated graphite by ultrasonic treatment in benzene (1 mg material in 20 ml solvent) for 3 h. Droplets from the suspension were dispersed on silicon wafer. The graphite platelets were characterized by atomic force microscopy (AFM). Successive oxidation of the sample was carried out at 450–550 °C in air. AFM measurements showed that the thermal oxidation removed 2–3 graphenes from the platelets and it left behind single graphene layers.