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Oxygen evolution by electrolysis of aqueous solutions has been studied on nonstoichiometric perovskite‐related ferrites of composition . Electrochemical measurements have been carried out according to a methodology previously proposed for ceramic‐type materials. The physical chemical and geometrical parameters are preliminarily fixed. A maximum of the electrocatalytic activity appears for , which also corresponds to the highest value of Fe4+ ratio . Two Tafel regions have been observed and kinetic parameters show that: at low potential the acid‐base reaction is rate determining whereas at high potential it is the first electron transfer . This change with potential implies that the transport properties of the materials play a decisive role in the reaction mechanism.
Wattiaux et al. (Wed,) studied this question.