Polarization Curves of Redox Systems Involving Consecutive Electron-Transfers: Some Theoretical Aspects

An equation, first worked out by Vetter, describing the complete polarization curves for redox systems involving two consecutive electron transfer steps, has been examined in detail by computer solutions. It is shown that quite wide variations in the values of the individual transfer coefficients have little effect on the shape of the theoretical curves. However, as the ratio of the individual exchange currents approaches 100:1, two definite linear‐logarithmic regions appear in one branch of the curve. It is further shown that in many cases the diffusion current masks the true Tafel portion, leaving the "pseudo‐Tafel" part as the only observable linear‐logarithmic region.