Surface electrode processes in the light of implicit anodic and cathodic current components

Abstract

A recently introduced methodology (Sci Rep 14:17314) for estimating the implicit anodic and cathodic current components of a net, experimentally measured current at a given potential is applied to surface-confined, diffusionless electrode processes. Under the simplest conditions of a voltammetric experiment with a linear potential sweep, the conventional voltammogram is deconstructed into genuine anodic and cathodic current components. These components exhibit high sensitivity to electrode kinetics, offering an alternative perspective on electrochemical reversibility compared to conventional cyclic voltammetry. To calculate the implicit current components, prior knowledge of the formal potential of the redox couple is required, along with integration of the net current. Once determined, these current components allow independent estimation of the electrode kinetic parameters, i.e., standard rate constant and the electron transfer coefficient, either through Tafel-like analysis or by employing a novel form of differential current. In the kinetic regime of very fast, seemingly electrochemically reversible electrode reactions—where the net current becomes independent of electrode kinetics—the implicit current components remain highly sensitive to these kinetics. The theoretical considerations are supported by experiments on the reduction of methylene blue, covalently immobilized on a gold electrode via the self-assembly of a mixed peptide-thiol layer.