Advanced analysis for electrode kinetic studies of surface reactions by applying square-wave voltammetry

Abstract

A novel methodology for electrode kinetic studies is proposed by altering either the amplitude, ESW, or the frequency, f, of a Square wave voltammetry (SWV) experiment. The apparent standard rate constant, k0, of a surface electrode reaction can be easily determined by using a relationship between the logarithm of the characteristic dimensionless kinetic parameter, k0/2f, and the peak potential separation observed in a SW voltammogram, ΔEP. It is shown that it is possible to relate the function Ωn,α = ln(k0/2f) to the peak separation provided that the number of exchanged electrons, n, and the transfer coefficient, α, involved in the electrochemical reaction are known. Two regions are defined when the dependence of Ωn,α on ESW is analized: the amplitude dependent region, ADR, where │ΔEP│<0.090V/n, and the non amplitude dependent region, NAD, for higher │ΔEP│values. A unique function Ωn,α is defined for each one of these regions thus providing an extremely easy way for obtaining the apparent standard surface rate constant.Up to now, the methodology here proposed and the so called “potential-corrected SW voltammograms” method, constitute the alternatives for electro kinetic studies based on the measurement of the peak separation generated by SWV.