Self-inhibition in catalytic processes: Cyclic voltammetry

The effect of inhibition by reaction products on cyclic voltammetric responses in catalytic systems is investigated under the assumption that the kinetics of their adsorption onto the electrode surface is Langmuirian and that the covered part of the electrode is totally inactive toward electron transfer to the catalyst. The current responses thus depend on three dimensionless parameters related to the various experimental parameters, i.e. rate constant of the catalytic reaction, bulk concentrations and diffusion coefficients of catalyst and substrate, maximal surface concentration and rate constants for adsorption and desorption of the inhibiting products. Two sub-cases where adsorption is irreversible and where adsorption and desorption are equilibrated respectively are discussed in full detail. The responses thus depend on only two dimensionless parameters and can be analyzed in terms of a zone diagram in each case. The dimensionless current responses can be expressed as easily computed closed form or integral equations. Numerous typical examples of dimensionless voltammograms are given and the variations of their main height, potential location and shape characterictics with the parameters are described.