Tafel-Volmer Electrode Reactions: The Influence of Electron-Transfer Kinetics

A typical Tafel-Volmer electrode reaction, embracing a preceding chemisorption step and a following electron transfer, is explored by simulation. Two different electron-transfer formalisms, Butler-Volmer and a Marcus-Hush-like approach, are utilized in interpreting the potential-dependent kinetics of the electrochemical process. Under nonreversible electron-transfer conditions, the steady-state voltammetric response at a microdisk electrode is sensitive to the underlying electron-transfer kinetics, such that with weak adsorption conditions, the discrepancies between the two-electron-transfer models are more pronounced. At high overpotentials, a non-diffusion-limited current may either arise from slow adsorption or be a result of Marcus Hush type kinetics.