Etude des mécanismes des réactions électrochimiques par simulation de voltampérométrie cyclique. Application aux réactions d’électrodéposition. (Study of the mechanismsof electrochemical reactions by simulation of cyclic voltammetry.Application to electrodeposition reactions)

Abstract

The absence of general theoretical models describing linear sweep voltammetry (LSV) or cyclic voltammetry (CV) responses for soluble-insoluble systems such as one-step electrodeposition reactions under quasi-reversible condition makes it difficult to extract quantitative kinetic information from experimental voltammograms. In this work, the semi-analytical method and the finite-element method included in COMSOL Multiphysics software for simulating LSV and CV responses for one–step electrodeposition process are described, for a case where instantaneous nucleation takes place, such as metal deposition on same metal. Voltammetric peaks were analyzed following variation of both dimensionless rate constants and charge transfer coefficients in a broad range. Therefore, kinetic curves for electron transfer processes were established and fitted perfectly by sigmoidal Boltzmann function and linear models. With these models, LSV or CV experimental data can be used to measure electrodeposition reactions kinetics whatever the degree of reversibility. The Cu(I)/Cu(0) couple in acetonitrile was selected as an experimental example. The model developed in this work predicts accurately the current response for Cu electrodeposition reaction and an excellent experiment-theory agreement was found. Furthermore, the LSV and CV models developed in this work, allow the theoretical concentration profiles for soluble-insoluble redox couples to be established for either reversible, quasi-reversible and irreversible cases.