On the impedance of electrodes with rough interfaces

Published treatments of the impedance of “blocking” electrodes with self-similar rough surfaces can be generalized to include the effects of slow faradaic processes. A procedure is outlined to transform the measured half-cell impedance to the shape of the equivalent impedance on a microscopically smooth planar electrode. The analysis supports a fractional phase shift (rather than a constant one) due to interfacial roughness, and can be used to obtain a measure of such roughness from the experimental data.