Diagnostic Criteria for Identifying an ECE Mechanism with Cyclic Square Wave Voltammetry

Abstract

Theory for cyclic square wave voltammetry of an irreversible first-order chemical reaction coupling two electron transfers, i.e. an ECE mechanism, is presented. Theoretical voltammograms were calculated following systematic variation of empirical parameters to assess their impact on the shape of the voltammogram. Note that the results presented herein are applicable only to ECE processes where E0 for the second electron transfer step is negative of that for the first. Under this condition, disproportionation reactions do not occur. From the trends obtained, diagnostic criteria for this mechanism were deduced.When properly applied, these criteria will enable non-experts in voltammetry to assign the electrode reaction mechanism and accurately measure reaction kinetics over the range -2 ≤ log kf ≤ 6. c The Author(s) 2015.