Calculation of cyclic voltammetric responses for the reductive formation of catalyst-substrate adducts on electrode surfaces

Electrocatalysts based on monolayers of transition-metal complexes attached to electrode surfaces frequently follow mechanisms in which a chemical step is interposed between the first and subsequent electron-transfer steps. The cyclic voltammetric responses to be anticipated for such systems were calculated using finite difference procedures to solve the relevant differential equation. The calculated variation of the peak currents and peak potentials with the kinetic parameters governing the three steps in the mechanistic scheme are presented in graphical form. Application of the results to a specific experimental system, the catalysis of the electroreduction of O_2 by a macrocyclic complex of Co^(III) adsorbed on graphite electrodes, produced reasonable agreement between calculated and observed cyclic voltammograms