Surface Electrode Mechanism Associated with Preceding and Follow up Chemical Reactions - Theoretical Analysis in Square-Wave Voltammetry

Surface electrode reaction (E), coupled with reversible preceding and reversible follow up chemical steps (C), or so-called "surface CEC mechanism" is considered theoretically under conditions of square-wave voltammetry. Large set of square-wave voltammograms of considered electrode system are calculated as a function of thermodynamics and kinetics of chemical steps involved in this complex mechanism. The surface CEC mechanism can be simplified to a surface CE, or a surface EC mechanism, if one assumes defined magnitudes of the equilibrium constants of chemical steps involved. Although the influence of the square-wave frequency to the voltammetric patterns is quite complex, a frequency analysis can reveal important aspects to recognize this mechanism. While we present important differences that can distinguish between the effect of the kinetics of both chemical steps, we also give the readers hints on how to design experiments in order to get access to all relevant kinetic constants. Theoretical results elaborated in this work are quite important, since there are important experimental systems, such as redox enzymes and metal-ligand complexes, whose voltammetric behaviour fits to this mechanism.