Theoretical analysis of multistep electrochemical mechanism coupled with various homogeneous chemical reactions in cyclic voltammetry

Because multistep electrochemical mechanisms are often coupled with chemical reactions, there is a real need in voltammetry to develop a sort of generalized mechanistic framework that unifies sequential electron transfers and homogeneous chemical reactions within a single platform. In this work, the diffusional two-step electrochemical mechanism (assigned in the work as E1CrevE2C′ mechanism) is theoretically elaborated and comprehensively analyzed. It is seen as an electrochemical platform consisting of two sequential electron-transfer steps that are bridged through a reversible chemical transformation and followed by an irreversible regenerative (catalytic) chemical reaction. The model was solved under Butler-Volmer kinetics under conditions of cyclic staircase voltammetry, by considering the effects of diffusional mass transport, interfacial electron transfer, and homogeneous chemical kinetics within a unified formalism. The large set of voltammetric patterns provide the readers insights into various aspects of analyzed mechanism under conditions of cyclic staircase voltammetry. The simulated voltammograms provide insights into the mutual interplay between electron-transfer kinetics, reversible chemical equilibria, catalytic regeneration, and diffusional transport. By systematic variation of relevant kinetic and thermodynamic parameters, the mechanism converges to several well-known classical electrochemical pathways, such as E, EE, EC′, ECrevE, and EEC′, among others. Thus, the ECrevEC′ mechanism can be seen as a versatile platform for getting mechanistic characterization of various complex electrochemical systems. This theoretical approach offers a sort of generalized framework for the analysis of multistep electrochemical systems. Beyond its mechanistic significance, the work is intended to provide electrochemists with a practical theoretical framework for understanding voltammetry of complex E1CrevE2C′ systems.