Square-wave voltammetry of quasi-reversible electrode processes with coupled homogeneous chemical reactions

The electrochemical behaviour of systems complicated by electrode kinetic and quasi-reversible preceding or following homogeneous chemical reactions under square-wave voltammetry (SWV) conditions is analysed theoretically. The results are discussed in detail, considering the influence of rate and equilibrium constants, together with experimentally controlled parameters such as f and Esw. Both kinetic stages act synergistically for the case of a CE mechanism, but the EC reaction scheme exhibits more complex behaviour, especially for reversible and quasi-reversible electrochemical reactions, which present a minimum response of current for the quasi-reversible chemical reactions. These curves are characteristic for each system, providing not only the bases for their distinction but also for the extraction of kinetic and thermodynamic information.