A new approach to a first order irreversible homogeneous chemical reaction followed by an electrochemical process (CiE mechanism): theory, simulation and application

Abstract

Chronoamperometric profiles were derived for systems in which an irreversible, homogeneous chemical reaction generates an electroactive species that readily reacts at the surface of a planar electrode. From the resulting current (i) equations, a semi-operation (convolution voltammetry and semi-differentiation) approach was proposed to extract the rate constant of the chemical reaction through non-linear fitting. These equations were validated using digital simulations, and the semi-derivative approach successfully recovered the simulated parameters. The proposed kinetic method was then experimentally applied to a well described chemical reaction, the oxidation of iodide by hydrogen peroxide in acidic medium, followed by the electrochemical reduction of triiodide. The rate constants obtained from the method were in agreement with existing literature across various temperatures, and an Arrhenius plot led to a reasonable value for the activation energy of the process.