Direct correlation between the measured electrochemical capacitance, wettability and surface functional groups of CarbonNanosheets

In this work, we studied the interfaces formed between Carbon Nanosheets (CNS) with ranging height and morphology in combination with aqueous and non-aqueous electrolyte solutions. The study concentrates on the influence of CNS wettability and surface functional groups on the electrochemical capacitance measured by Electrochemical Impedance Spectroscopy (EIS). Capacitance values at point of zero charge(pzc) were used as a reference point to compare CNS structures with different heights. A correlation was found between electrochemical capacitance values determined in water based electrolyte solution and the wettability of CNS. For example, CNS with the same height of 1.1 μm but grown from different precursors had contact angles of 16 and 141∘ and respective capacitance densities of 922 and 167 μF/cm2. The CNS capacitance was normalized to the capacitance of planar Highly Oriented Pyrolytic Graphite (HOPG) electrode to estimate the area enhancement of the various CNS samples. Surface area enhancement of 120x per micrometer of CNS layer was found.