Measuring the Capacitance at Few- and Many-Layered Graphene Electrodes in Aqueous Acidic Solutions

The differential capacitance of 1-2 layered and 6-7 layered graphene (LG) was measured in aqueous 0.01, 0.1, 1.0, and 3 M perchloric and sulfuric acid solutions. The total measured capacitance was evaluated for approx. +/- 500 mV either side of the potential of zero charge to observe the contribution from the quantum capacitance and shielding effects on the measured capacitance. The experimental results were compared to the recent theoretical evaluations of similar electrode-electrolyte interfaces for supercapacitor applications. At 6-7 LG electrodes, the measured differential capacitance was dependent on the solution and electrical double layer structures, and although the 1-2 layered electrode showed far fewer differences upon changing solution conditions, it was not strictly independent. The concept of shielding effects within the graphene electrode and a dielectric capacitance as proposed by theory would account for these observations.