Advances in Understanding Mechanisms of Perovskite and Pyrochlore as Electrocatalysts using In Situ X‐ray Absorption Spectroscopy

Metal oxides are one of the promising candidates as electrocatalysts for electrical energy storage (EES) systems. Particularly, perovskite and pyrochlore oxides have been intensively investigated as bi-functional electrocatalysts because of their superior catalytic activities during oxygen reduction and evolution reactions. However, the origin of outstanding catalytic activities and structural changes of materials are not clearly revealed, in part due to the difficulty in identification during electrocatalysis. In this Minireview, we present a critical overview of recent progress in understanding catalytic mechanisms of perovskite and pyrochlore oxides, highlighting the innovative in situ X-ray absorption spectroscopy (XAS) analysis for electrochemical tests.