A Strategy to Promote the Electrocatalytic Activity of Spinels for Oxygen Reduction by Structure Reversal

The electrocatalytic performance of a spinel for the oxygen reduction reaction (ORR) can be significantly promoted by reversing its crystalline structure from the normal to the inverse. As the spinel structure reversed, the activation and cleavage of O−O bonds are accelerated owing to a dissimilarity effect of the distinct metal atoms co‐occupying octahedral sites. The CoIIFeIIICoIIIO4 spinel with the Fe and Co co‐occupying inverse structure exhibits an excellent ORR activity, which even exceeds that of the state‐of‐the‐art commercial Pt/C by 42 mV in alkaline medium. Enhancing by reversing: The electrocatalytic performance of Co‐Fe based spinel for the oxygen reduction reaction can be significantly promoted by reversing its structure from normal to inverse. The enhancement of activity originates from a dissimilarity effect of Fe and Co atoms at the octahedral sites, which modulates the oxygen adsorption energy (Ead) and elongates the O−O bond compared to that on the normal spinel.