Simple Analysis of Quasi-Reversible Steady-State Voltammograms

Abstract

The kinetic parameters (k° and α) of a uncomplicated quaslreverslble electrochemical reaction studied by any steady-state voltammetrlc technique can be found directly from the values of two easily accessible experimental parameters, (E1/4-£1/2) and (E1/2-E3/4), where E1/2is the experimental halfwave potential and E1/4and E3/4are voltammetrlc quartlle potentials. For any type of steady-state (or pseudo-steady-state) current-potential curve obtained with a uniformly accessible working electrode, e.g., voltammetry at a rotating disk or hemispherical microelectrode, polarography, sample current voltammetry, and thin-layer voltammetry, a table Is given which shows the kinetic parameters, i.e., standard rate constant, k°, and the transfer coefficient, α, and also the formal potential, E°', from the two above experimental values. An analogous table is presented for the nonunlformly accessible microdisk electrode. Unlike previously reported approaches, an independent evaluation of the standard (formal) potential is unnecessary. This analysis also does not rely on values of the electrode surface area and the bulk concentration of electroactive species which usually decrease the accuracy of the results. The application of the proposed methodology to other electrochemical systems including scanning electrochemical microscopy (SECM) and ultramicroelectrodes shaped as a cone or spherical segment is also discussed. © 1992, American Chemical Society. All rights reserved.