POTENTIODYNAMIC FREQUENCY RESPONSE OF ATOMIC LAYERS IN REVERSIBLE AND IRREVERSIBLE UNDERPOTENTIAL DEPOSITION

Abstract

The potentiodynamic electrochemical frequency response of atomic layers underpotential deposition (UPD) shows different kinds of constituents in reversible and irreversible processes in a cyclic potential scan. The total response of reversible UPD decomposes into the constituent responses of double layer and Faradaic processes represented by adsorption capacitance and resistance in equivalent electric circuit (EEC). Anions that affect metal monolayer deposition give a separate RC branch in the EEC with characteristic R and C dependencies on the potential. The EEC of irreversible UPD does not contain adsorption capacitance. The Faradaic part of the response is revealed by charge transfer resistance and the Warburg impedance, showing hysteresis in cyclic scans. Nonideal double layer capacitance in the irreversible UPD is well represented by constant phase element.