Atomic Cobalt Metal Centers with Asymmetric N/B-Coordination for Promoting Oxygen Reduction Reaction

Cobalt single atom catalysts (SACs) have exhibited promising performance in both the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER), positioning them as potential dual-functional catalysts for Zn-air battery. However, the long-standing challenge lies in achieving satisfactory dual-functionality and stability of these SACs. In this study, to optimize the 4e^‒ ORR performance, boron (B) atoms are employed with low electronegativity to regulate the structure of the Co–N–C catalytic center. This resulted in the formation of an asymmetrically coordinated Co metal center catalyst (Co-N₃B). Compared to the Co-N₄, Co-N₃B exhibited lower free energy for ORR and stronger adsorption energy toward ^*O species, effectively suppressing the 2e^‒ ORR pathway at the cobalt site and preventing catalyst corrosion induced by hydrogen peroxide (H₂O₂) in ORR reactions, thereby enhancing catalyst stability. In situ attenuated total reflectance surface-enhanced infrared absorption spectroscopy (ATR-SEIRAS) further validated excellent interaction between Co active centers and O intermediates. Furthermore, the self-made rechargeable zinc-air battery demonstrated remarkable discharge peak power density (≈253 mW cm^‒2), energy density (≈819 mAh g^‒1), and cyclic stability exceeding 110 h. This study provides new insights into constructing catalysts with atomic-level precision and offers strong references for practical applications in energy storage and convension electrocatalysts.