Hydrogen‐Bond‐Assisted Synthesis of Single‐Atom and Nanocluster Synergistic Sites for Enhanced Oxygen Reduction Reaction

Abstract Electrocatalysts combining metal single‐atom and nanocluster synergy are promising alternatives to platinum‐based catalysts for oxygen reduction reaction (ORR). However, controllable synthesis of such catalysts with high ORR performance remains challenging due to metal atom aggregation into large nanoparticles. Here, a hydrogen‐bond network confinement approach to construct Co nanocluster and Co‐N x ‐C moiety coexisting active sites on nitrogen‐doped porous carbon for highly active and long‐term stable ORR is reported. The optimized Co@Co‐N‐C catalyst exhibits a half‐wave potential (E 1/2 ) of 0.92 V versus RHE and a limiting current density (J L ) of 6.02 mA cm −2 for ORR, presenting a 40 mV positive shift in E 1/2 than the competitor with the highest J L and 15.7% improvement in J L over the catalyst with the most positive E 1/2 . The enhanced catalytic performance originates from the synergy between Co nanocluster and Co‐N x ‐C moieties, which modulates the electronic structure of the Co‐based active sites and improves the electrochemically active surface area. The zinc‐air battery assembled with Co@Co‐N‐C catalyst delivers a specific capacity of 870 mAh g −1 and a maximum discharge power density of 210 mW cm −2 , representing ≈52% improvement over Pt/C‐based devices. This hydrogen‐bond‐assisted synthesis strategy opens pathways for designing high‐performing catalysts in diversified fields beyond ORR, including water splitting, CO 2 reduction, and nitrogen reduction.