Native Graphene Oxides at Graphene Edges

Electronic properties of graphene edges on a SiO
₂
substrate have been examined using scanning probe microscopy. Distinctive dot-like protrusions appearing nearly periodically on the edges of graphene were observed, and the density of the protrusions increased as the number of graphene layers increased. Imaging analysis revealed that the electrostatic properties of these protrusions are different from those of surrounding graphene. These findings are discussed and interpreted in terms of the local oxidation at the native graphene edges.