The interfacial capacitance of large area, single layer graphene was directly measured with electrolyte accessing both sides of the graphene sheet. PMMA and photoresist patterns were used as supports to suspend the CVD grown graphene in electrolyte during electrochemical testing. Both one and two sides of single layer graphene films were measured and compared. The results show that the area normalized charge that can be stored simultaneously on both sides is significantly lower than could be stored on just one side of single layer graphene, consistent with charge storage having a quantum capacitance component. These measurements are also consistent with the specific capacitance of graphene materials as previously measured in supercapacitor cells and provide a basis for the further understanding and development of graphene based materials for electrical energy storage.
