Mathematical Model beyond Surface ECrev Mechanism in Protein-Film Voltammetry Considered by Butler-Volmer Kinetics

Protein-film voltammetry is an elegant electrochemical methodology based on the direct electrochemical conversion of redox-active species immobilized at the electrode surface. In this case, the reacting molecules do not diffuse from the bulk solution toward the electrode. Instead, the entire electrochemical response is controlled by the amount of adsorbed material, the rate of heterogeneous electron transfer, and possible coupled chemical transformations inside the surface-confined film.
The surface mechanism considered here is a reversible one-electron transformation between the adsorbed reduced and oxidized forms of a protein, followed by a reversible chemical conversion of the oxidized form into another adsorbed state:
Red(ads)⇌Ox(ads)+e-
Ox(ads)⇌Y(ads)
The first reaction is the electrode reaction. It is characterized by the standard heterogeneous electron-transfer rate constant, k_s, and the electron-transfer coefficient, α. The second reaction is a surface-confined reversible chemical reaction, described by the forward rate constant kf, the backward rate constant kb, and the equilibrium constant Keq equal to Keq = kf/kb. While we give entire mathematical algorithm to solve this mechanism, we also give hints and free files available at tge Repository of the Goce Delcev University, Stip that enable simulation of this mechanism under conditions of square-wave and cyclic voltammetry.