Dynamics of double-layer by AC Modulation of the Interfacial Capacitance and Associated Transfer Functions

The Modulation of Interface Capacitance Transfer Function (MICTF) technique in combination with Electrochemical Impedance Spectroscopy (EIS) and derived transfer functions has been developed for the study of double-layer relaxation and adsorption processes. Using a Hg electrode in NaBr and KCl solutions as examples, the MICTF is shown to be well-suited for the investigation of physico-chemical processes occurring inside the diffuse layer. Two time-constants are found and their characteristics are analyzed as a function of the potential of zero charge (PZC), the electrolyte concentration, and the nature of the electrolyte. Interpretation is discussed in the framework of accepted double-layer theories including relaxation in the diffuse double-layer and adsorption processes.