Study of partially blocked electrodes by means of electromechanical impedance measurements
Résumé
The study of the reduction of dissolved oxygen, in an aerated sulphuric acid medium, to the surface of a rotating disc electrode of iron has been carried out so as to determine the nature of coverages involved in the processes taking place on both sides of the corrosion potential.
The measurements of the diffusional component due to the reduction of oxygen was derived from the frequency analysis of the current response to a sine wave modulation of the disc velocity (eletromechanical impedance).
The treatment of our data shows that a blocking of the reactional area with respect to the oxygen reduction is caused by a hydrogenated species having a long time. This blocking remains very important (80%) at the corrosion potential and decreases to zero for anodic currents higher than 5 mA cm−2.