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 utilised in interpreting the potential-dependent kinetics of the electrochemical process. Under non-reversible 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