Synergistic Integration of Co Nanoparticles and Asymmetric Atomic Co–N/O Sites for an Efficient Oxygen Reduction Reaction

The single-atom Co–N–C catalyst has shown great promise for the oxygen reduction reaction (ORR). However, its intrinsic activity remains suboptimal, highlighting the need for a deeper understanding of the electron configuration of the Co–N–C catalyst and the development of effective modulation strategies. Herein, we developed an effective ligand engineering approach to modulate the local electronic structure of the Co–N–C catalyst comprising a single-site Co atom co-coordinated with N and O (Co–N/O) anchored into a carbon matrix along with uniformly dispersed Co nanoparticles (CoNP), denoted as CoNP@Co–N/O–C. In this unique structure, the engineered CoNP and asymmetric N/O-coordinated environment synergistically induce electron redistribution and regulate electron configuration around the single Co site, thereby accelerating charge transfer and enhancing catalytic activity. Consequently, the CoNP@Co–N/O–C catalyst demonstrates exceptional ORR performance with a half-wave potential of 0.90 and 0.77 V versus RHE in 0.1 M KOH and 0.5 M H2SO4, respectively. Moreover, rechargeable zinc–air batteries (ZABs) assembled with CoNP@Co–N/O–C as an air cathode deliver a high peak power density of 226.7 mW cm–2 and excellent cycling stability over 240 h at 10 mA cm–2. This study presents a promising strategy for designing high-performance ORR electrocatalysts with asymmetric coordination environments for advanced energy conversion applications.