CALCULATION OF CYCLIC VOLTAMMETRIC RESPONSES FOR THE REDUCTION OF SUBSTRATES BY AN INNER-SPHERE MECHANISM AT ELECTRODE SURFACES WITH SINGLEMONOLAYERS OF CATALYSTS

Cyclic voltammetric responses are calculated for the reduction of a su bstrate at an electrode coated with a monolayer of catalyst with which the substrate must form a complex in order to be reduced. The effects of variations in the equilibrium constant for the formation of the ca talyst-substrate complex, in the rate constant for its electroreductio n and in the relative formal potentials of the catalyst and catalyst-s ubstrate complex couples were evaluated. In every case the catalytic c omponent of the total currents can be obtained by simple subtraction o f the catalyst response measured in the absence of substrate. The peak potentials of the catalytic responses are usually more negative than the formal potential of the catalyst in the coatings. Both of these fe atures differ from the behavior expected for the case where the substr ate is reduced via outer-sphere electron-transfer to the catalyst coat ing [3]. The situations in which the voltammetric responses may be use d to discriminate between these two mechanisms are discussed.