Bifunctional catalytic activity of LaCoO3 perovskite air electrode for rechargeable Zn–air batteries boosted by molybdenum doping.

Perovskite oxides are widely regarded as efficient and low-cost catalytic materials for the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) on the air-electrode side of zinc-air batteries (ZABs). Herein, LaCo 1−x Mo x O 3 (LCM, x = 0, 0.05, 0.1, and 0.15) perovskite electrocatalysts are prepared by self-propagating high-temperature synthesis and evaluated as the bifunctional electrocatalytic activity for ZABs. Results show that the ORR and OER activities of LaCoO 3 (LCO) can be efficiently enhanced simultaneously with the proper substitution of Mo for Co, and the optimal performance is obtained in LaCo 0.95 Mo 0.05 O 3 (LCM-5). In comparison with LCO, LCM-5 demonstrates significantly enhanced bifunctional catalytic activity, in which a more positive ORR onset potential (0.861 V) at −0.1 mA cm−2 and a lower OER overpotential (405 mV) at 10 mA cm−2 are achieved. When using LCM-5 as an air electrode catalyst for ZABs, it delivers a specific discharge capacity of over 800 mA h g−1, a high power density of 136.1 mW cm−2, and excellent long-term cycle stability (120 h at 10 mA cm−2). This finding is primarily due to the regulation of the B-site Co valence states and the increase in surface oxygen vacancies. This study suggests the possibility of enhancing the bifunctional catalytic activity of LaCoO 3 perovskite air electrodes for ZABs by a simple doping process. • Improved catalytic activities toward ORR and OER simultaneously were observed. • The B-site Co valence states and oxygen vacancies were optimized by Mo doping. • The ZABs with LCM-5 as cathode deliver excellent long-term cycle stability. [ABSTRACT FROM AUTHOR]