Ohmic resistance and constant phase element effects on cyclic voltammograms using a combined model of mass transport and equivalent circuits

A few key theoretical issues of importance in modern molecular electrochemistry

“…In fact under most experimental conditions the double layer capacitance is best represented by a constant phase element (CPE) [58,59]. Though CPE double layer capacitances are seldom considered in rationalizing voltammetric experiments, CPEs are now widely accepted and used to model electrical equivalent circuits in electrochemical impedance spectroscopy [60].…”

“…Though CPE double layer capacitances are seldom considered in rationalizing voltammetric experiments, CPEs are now widely accepted and used to model electrical equivalent circuits in electrochemical impedance spectroscopy [60]. Incorrectly predicted ohmic drop and capacitive background may have severe consequences on the interpretation of transient voltammetric data as soon precise measurements are sought [58]. This clearly claims for the integration of CPEs in finite difference numerical simulation programs able to treat any complex mechanistic sequence.…”

Determination of Constant Phase Element Parameters under Cyclic Voltammetry Conditions Using a Semi-theoretical Equation

“…However, the non-faradaic current is not linear with the applied potential, and it is also coupled with the faradaic current through ohmic drop effects. 7,8 In addition, if the ohmic drop effect is appreciable compared to the accuracy of the measurement, the faradaic peak potential is flattened and shifted more toward the irreversible regime because of the nonlinear scan rate. Usually, ohmic drop effects can be minimized by either lowering the scan rate, reducing the electrode surface area, [9][10][11] or increasing the supporting electrolyte concentration.…”

“…To distinguish between faradaic and non-faradaic currents in cyclic voltammograms, a model that includes the combined effects of ohmic resistance, CPE, mass transfer, and faradaic processes has been proposed. 7 A set of equations such as Fick's second law and the Butler-Volmer equation were used to solve for the faradaic current, while the non-faradaic current was calculated using the time-domain response of a CPE. By adopting the equivalent circuit concept, the total current can be obtained.…”

“…[47][48][49][50] Therefore, to distinguish between the faradaic and non-faradaic currents in cyclic voltammograms, it is important to directly determine the CPE parameters from cyclic voltammetry. Although several studies have investigated the time-domain response of a CPE, [5][6][7][8]51,52 few studies have focused on obtaining the CPE parameters in cyclic voltammetry experiments. 53 However, those approaches were limited to the case when a large faradaic current is not present in the first cycle.…”