Impedance of rough capacitive electrodes: the role of surface disorder

The interfacial impedance of solid electrodes in the absence of Faradaic reactions usually deviates from purely capacitive behaviour; this effect is enhanced on rough electrodes. We present a qualitative experiment showing that capacitance dispersion on solid electrodes is due to surface disorder (i.e. heterogeneities on the atomic scale) rather than roughness (i.e. geometric irregularities much larger than those on the atomic scale).