Hierarchically Porous Carbon‐Supported Fe Dual‐Sites for Synergistic Oxygen Reduction in Zinc–Air Batteries

Abstract Understanding the active‐site dynamics in oxygen reduction reaction (ORR) electrocatalysts is critical for advancing energy conversion technologies. Herein, a dual‐site iron‐based catalyst, comprising atomically dispersed Fe single atoms and subnanometric Fe clusters anchored on a hierarchically porous carbon framework is synthesized via starch‐derived pyrolysis. This electrocatalyst exhibits enhanced ORR performance, featuring high activity, dominant four‐electron selectivity, and exceptional durability. Mechanistic spectroscopy investigations identify the formation of oxygenated intermediates (e.g., * OOH) at the iron active sites, directly evidencing oxygen activation on Fe centers. Complementary in situ spectroscopy tracked the dynamic coordination of water and hydroxyl species at the catalyst–electrolyte interface, offering insight into the proton‐coupled electron transfer pathways. Theoretical calculations reveal that the axial adsorption of a hydroxyl group on iron sites induces a downshift of the d‐band center, effectively optimizing the adsorption–desorption energetics and significantly reducing the activation barrier for the rate‐determining step, thereby accelerating ORR kinetics. Practical integration into zinc–air batteries confirmed the good performance, substantially surpassing the Pt/C counterpart. This work unveils a synergistic dual‐site activation mechanism governed by local coordination and electronic modulation, offering a rational pathway toward designing high‐performance, non‐precious metal ORR catalysts for next‐generation energy devices.