Original scientific paper

A Theoretical and Experimental Study of a Two-step Quasireversible Surface Redox Reaction by Square-wave Voltammetry

Valentin Mirčeski ; Ernst-Moritz-Arndt-Universität Greifswald, Institut für Chemie und Biochemie, Soldtmannstraße 23, D-17489 Greifswald, Germany
Rubin Gulaboski ; Ernst-Moritz-Arndt-Universität Greifswald, Institut für Chemie und Biochemie, Soldtmannstraße 23, D-17489 Greifswald, Germany

Abstract

An extended theoretical treatment of a two-step surface redox reaction under the conditions of square-wave voltammetry (SWV) is presented. The theoretical model is applicable to any reversibility of both redox steps of the EE reaction. The integral equations representing this theoretical model were solved numerically. The apparent reversibility of the redox steps depends on two dimensionless kinetic parameters, κ₁ and κ₂, defined as κ₁ = k_s,1/f and κ₂ = k_s,2/f, where k_s,1 and k_s,2 are the standard rate constants of the first and second redox steps, respectively, and f is the excitation signal frequency. The response consists of either a single or two separate SW peaks, depending mainly on the difference between the formal potentials of the first and second redox steps as well as on the ratio of the kinetic parameters κ₁/κ₂. The effect of the electron transfer coefficients of both redox steps is also discussed. A part of the theoretical results are qualitatively illustrated by SW voltamograms of the azo-dye Sudan-III.

Keywords

square-wave voltammetry; EE reaction; simulations; surface reactions; azo-dyes; Sudan-III

Hrčak ID:

103055

URI

https://hrcak.srce.hr/103055

Publication date:

30.4.2003.

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