Is graphene oxide an insulating material?

Graphene and graphene oxide are increasingly attracting worldwide attention from academia and industry. The physical properties of graphene have been documented recently, and we have known that the sea of electrons in the two-dimensional, single layer of sp² hybridized carbon atoms causes graphene to act both as electrical and thermal conductors. In contrast, graphene oxide, an oxidized graphene sheet with carboxylic acid at the edges and phenol hydroxyl and epoxide groups on the basal plane, is generally considered to be an insulating material. Is graphene oxide is an insulating material? This work tries to answer this question by measuring the temperature-dependent electrical property of graphene oxide paper by using a broadband dielectric spectroscopy.