Negative Resistances and Inductances in Equivalent Circuits for Adsorption-Reaction Kinetics

The origin and nature of inductive arcs in electrochemical impedance spectra of reacting systems have been debated in the literature. In this work, inductances are shown to be an essential component in the electrical equivalent models of adsorption-reaction kinetics. An example reaction with one adsorbed intermediate species is analyzed in detail. The analysis is extended for a few other cases including second order reaction to show that the arguments are also applicable for more complicated cases. Similarly reactions with two adsorbed intermediates are analyzed and the applicability of resistances and inductances to model the system is confirmed. Even in the cases where the low frequency impedance appears to be capacitive, a negative inductance is shown to be a more appropriate choice than a capacitance. The physical basis of the origin of the inductances, negative inductances and negative resistances are discussed.