A comparison of Marcus–Hush vs. Butler–Volmer electrode kinetics using potential pulse voltammetric techniques

Simulated voltammograms obtained by employing Butler–Volmer (BV) and Marcus–Hush (MH) models to describe the electrode kinetics are compared for commonly used potential pulse techniques: chronoamperometry, Normal Pulse Voltammetry, Differential Multi Pulse Voltammetry, Square Wave Voltammetry and Reverse Pulse Voltammetry. A comparison between both approaches is made as a function of the heterogeneous rate constant, the electrode size, the applied potential and the electrochemical method, establishing the conditions in which possible differences might be observed. The effect of these differences in the extraction of kinetic parameters, diffusion coefficients and electrode radii are examined, and criteria are given to detect possible deviations of the experimental system from Butler–Volmer kinetics from the behaviour of the chronoamperometric limiting current. The Butler–Volmer model predicts the appearance of an anodic peak in Reverse Pulse Voltammetry for irreversible processes and a peak split of differential pulse voltammograms for quasireversible processes with a value of the transfer coefficient very different from 0.5 (smaller than 0.3 for a reduction process). These striking phenomena are studied by using the Marcus–Hush approach, which also predicts the anodic peak for slow electrode reactions in Reverse Pulse Voltammetry but not the split of the curve in differential pulse techniques.