Oxygen Reduction Reaction on Perovskite Materials: Mechanisms, Performance, and Trends

The oxygen reduction reaction (ORR) remains a major kinetic bottleneck in fuel cells, metal-air batteries, and related electrochemical devices. Perovskite oxides are attractive ORR catalysts due to the ABO3 lattice, which permits systematic control of transition-metal electronic structure, metal–oxygen covalency, and defect chemistry. This review compares low-temperature electrocatalytic ORR, including the 2e− and 4e− pathways, with high-temperature cathodic ORR in mixed ionic–electronic conductors, where oxygen adsorption, charge transfer, O=O bond cleavage, oxygen incorporation, and bulk transport are interlinked. The main optimization strategies, including A-site and B-site doping, defect engineering, nanostructuring, heterostructure/composite formation, and mechanisms, are discussed. Particular attention is given to the distinct requirements of fuel cells and metal-air batteries. Across these systems, perovskite ORR performance is governed by the joint evolution of surface chemistry, defect structure, and electrode architecture under operating conditions.