The Electrochemical Behavior of Scratched Iron Surfaces in Aqueous Solutions

A technique involving rapid scratching of rotating disk electrodes under potential control is presented and used to examine rapid reaction steps in the anodic behavior of iron in aqueous solutions of p H 0–14. Both anodic and cathodic reaction rates are greatly accelerated during scratching; current densities of up to ∼10 A cm −2 of bare metal surface were observed. The results obey Tafel's law and demonstrate the formation of an adsorbed layer of by: ( i ) , followed by ( ii ) for , or ( iii ) , and ( iv ) for . The layer of adsorbed is formed at potentials negative with respect to the reversible potentials for oxide formation and exists on the surface during steady‐state anodic oxidation of Fe and during cathodic reduction of H + from solution. The results are discussed in terms of the mechanism of steady‐state dissolution of Fe.