A generalized electrode mechanism unifying classical electrochemical pathways in square-wave voltammetry

The electrochemical framework consisting of two successive electron-transfer steps (EE) separated by a reversible homogeneous chemical equilibrium (Crev), followed by an irreversible regenerative chemical reaction (C′) linked to the participants in the second electron-transfer step is assigned as ECrevEC′ mechanism. The ECrevEC′ electrochemical scheme can be considered as a comprehensive and unifying mechanism that covers a broad spectrum of important classical electrochemical mechanisms as limiting cases. Depending on the magnitude of equilibrium constant of the intermediate chemical step ( K eq), the associated chemical rate parameter governing this equilibrium ( k chem ), and the kinetic rate constant of the irreversible regenerative reaction ( k c ), the ECrevEC′ mechanism can coherently reproduce the features of the simple “E mechanism”, as well as the “ECrev”, “CErev”, “EC′ (regenerative)”, and also the “EE”, “ECrevE” and EEC’ mechanisms. Theoretical treatment of this complex reaction scheme is of fundamental importance, as it enables a systematic and unified exploration of the entire mechanistic landscape within a single mathematical formalism. Mathematical modeling of this complex mechanism affords detailed insight into the coupled effects of electron-transfer kinetics, chemical equilibria, and homogeneous regeneration reactions. Voltammetric simulations based on the ECrevEC′ mechanism exhibit rich and valuable diagnostic features in both forward and backward current responses, permitting important mechanistic distinctions to be resolved via analysis of relevant parameters of the voltammetric patterns. The ECrevEC’ framework provides a powerful tool for the interpretation of experimental data in complex voltammetric systems involving multiple coupled chemical reactions. This electrochemical scheme is widely applicable theoretical platform with high relevance to redox catalysis, bioelectrochemistry and energy-conversion systems.