Enhanced Catalytic Activity of LaMnO₃ Perovskite Toward Oxygen Reduction Reaction Using Oxygen-Vacancy Engineering

Abstract

Zinc-air batteries (ZABs) have garnered significant attention due to their high theoretical energy density, safety, and environmental sustainability. However, the slow oxygen reduction reaction (ORR) kinetics at the cathode remains a major challenge for improving ZAB performances. In this study, ABO₃-type perovskite transition metal oxides, particularly LaMnO₃, are explored as potential nonprecious metal catalysts to address these limitations. In this work, the LaMnO₃ catalyst was prepared using the sol-gel method, and oxygen vacancies were introduced through a novel carbon reduction approach using conductive carbon black as the reducing agent. The catalyst was reduced at different temperatures to optimize its ORR activity. The 500 °C-reduced sample (LMOC-500) shows the superior catalytic performances, achieving an onset potential of 0.937 V versus RHE and a half-wave potential of 0.824 V versus RHE. The optimized material also exhibited excellent stability in long-term discharge tests in ZAB applications, demonstrating its potential application as the ORR catalyst for ZABs.