Electrolytic Oxygen Evolution in Alkaline Medium on La1 − x Sr x FeO3 − y Perovskite‐Related Ferrites: II . Influence of Bulk Properties

Abstract

The influence of the bulk properties upon the oxygen reaction in alkaline medium has been considered for phases . The evolution of electrocatalytic properties is discussed as a function of composition ratio of Fe⁴⁺ content , and of vacancy concentration . The electrocatalytic activity goes through a maximum for and increases continuously with τ. The active sites of the reaction mechanism are Fe⁴⁺ cations in high spin configuration located in surface fivefold coordinated sites of symmetry; a seven‐step mechanism is proposed involving the variation of both coordination and oxidation state of iron. It has been shown that the activity increases with the covalency of the Fe‒O bonds in the bulk. From transport properties, it follows that n‐type materials are the most efficient, and that the activity increases when the concentration of delocalized electrons in the σ^* band decreases. This enhancement can also be associated with an increase in electron mobility.