THE INFLUENCE OF DIFFUSION-COEFFICIENTS IN A CATALYTIC ELECTRON-TRANSFER MECHANISM ON LINEAR SWEEP VOLTAMMETRIC AND POTENTIAL STEP CHRONOAMPEROMETRIC MEASUREMENTS

The kinetic equations for a catalytic mechanism consisting of a homoge neous electron transfer followed by two competing fast second-order re actions, a coupling reaction and a homogeneous electron transfer, are solved by digital simulation for linear sweep voltammetry and potentia l step chronoamperometry at a stationary planar electrode. The simulat ions allow determination of the first homogeneous electron transfer ra te constant k(ET) and a competition parameter q for the two follow-up reactions. The influence on the current of different ratios of the dif fusion coefficients of the species involved was examined and it is sho wn that it can be rationalized from a combined ''near-reversible'', st eady-state and ''total catalysis'' approach. The lack of consideration of unequal diffusion coefficients may introduce errors in the experim ental determination of the parameter q.