THE ORIGIN OF INCLINED PLATEAU CURRENTS IN STEADY-STATE VOLTAMMOGRAMS FOR ELECTRODE PROCESSES INVOLVING ELECTROCATALYSIS

Steady-state current-potential curves recorded at rotating disk electrodes for electrode reactions that are subject to electrocatalysis often exhibit increasingly inclined (instead of flat) plateau currents as the rotation rate is increased. Evidence and arguments are presented in support of the proposition that the phenomenon is a reflection of a true potential-dependence of the currents measured on the plateaux. A model is suggested to explain the reason for this potential dependence; current-potential curves calculated on the basis of the model are compared with experimental curves for the reduction of O2 at catalyst-coated and bare graphite electrodes to demonstrate the adequacy of the model.