Peak current—frequency relationship in adsorptive stripping square-wave voltammetry

Abstract

A reversible redox reaction between the adsorbed reactant and the dissolved product or the amalgam is analysed. The relationship between the square-wave (SW) stripping peak current and the SW frequency is a curve defined by Δφ max = 0, for f sw = 0, and an asymptote Δφ max = kf SW + z. The intercept z depends on the duration t 0 of the adsorptive accumulation and apparently vanishes when t 0 > 30 s. Consequently, the ratio Δφ max / f SW may not be constant for all frequencies. This effect is caused by the additional adsorption of the reactant after the end of the accumulation period. The SW peak potentials depend linearly on the logarithm of frequency, with a slope which approaches −2.3 RT/2 nF and depends on both the accumulation time and the step increment. If only the product is adsorbed, the SW peak currents depend linearly on the square root of frequency. The peak potentials are a linear function of the logarithm of frequency, with slope 2.3 RT/2 nF.