Boosting the Bifunctional Catalytic Activity of La0.85Y0.15Ni0.7Fe0.3O3 Perovskite Air Electrode with Facile Hybrid Strategy of Metallic Oxide for Rechargeable Zn–Air Batteries

Developing cost-effective, sustainable, and high-performance air electrode catalysts for the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) remains a significant challenge in the advancement of rechargeable zinc–air batteries (ZABs). Herein, we successfully construct a vacancy-rich heterogeneous perovskite La0.85Y0.15Ni0.7Fe0.3O3 (LYNF) hybridized with Co3O4 spinel nanoparticles using a simple chemical bath-assisted method. The Co3O4 composite LYNF material is systematically evaluated as the bifunctional catalyst for ZABs in the proportion of 25 wt%, 50w t%, and 75 wt% (denoted as LYNF-xCo3O4, x = 0.25, 0.5, 0.75). The results confirm an intimate coupling between the perovskite and spinel phases, along with a significant increase in oxygen vacancy concentration. Among the composites, LYNF-0.5Co3O4 exhibits the best performance, achieving an ORR onset potential of 0.813 V vs. RHE at −0.1 mA cm−2 and a lower OER overpotential of 441 mV at 10 mA cm−2. When applied as the air electrode catalyst in ZABs, LYNF-0.5Co3O4 displays the highest discharge voltage and a peak power density of 115 mW cm−2, representing a 20% improvement over pristine LYNF. The enhanced performance of the LYNF-0.5Co3O4 composite is attributed to the accumulation of Co3O4 nanoparticles within the LYNF matrix, which introduces numerous electrochemically active sites and facilitates the charge and mass transport during the catalytic process in ZABs.