Bio-Inspired Hierarchical Nanoreactor With Hetero-Coordinated Fe-P-Co Bridges for Whole-Pathway-Regulated Electrocatalytic Oxygen Reduction.

Abstract

Efficient oxygen reduction reaction (ORR) requires coordination of oxygen adsorption, transport, and catalysis at active sites. Yet most studies address only one step, overlooking whole-pathway O₂ regulation and thus limiting performance. Here, we report a bioinspired Co-doped Fe₂P on N-doped carbon featuring a hierarchical eucalyptus-like nanoarchitecture, engineered to regulate oxygen throughout the electrochemical cycle, where Fe-P-Co hetero-coordinated bridges anchored to the carbon substrate through Fe─N bonds induce strong electronic coupling and polarization. The hierarchical structure generated local electric fields that enriched OH^- and O₂, while multilevel porosity accelerated oxygen transport. This enabled coordinated optimization of oxygen adsorption, transfer, and active-site electronic configuration. This nanohybrid achieved a half-wave potential of 0.938 V vs. RHE, sustained discharge in Al-air batteries for 373 h, and delivered an energy density of 3487 Wh/kg. Theoretical simulations revealed that Co-doping shortened Fe─P bonds and tuned the Fe electronic environment, lowering the d-band center and weakening Fe 3d-O 2p interactions, which reduced the *OH desorption barrier and accelerated ORR kinetics. In situ Raman spectroscopy revealed that Fe-P-Co bridges served as active centers facilitating *OH release during ORR. These findings indicate that integrating hierarchical architecture, hetero-coordinated Fe-P-Co bridges, and electronic-state modulation enables whole-pathway O₂ management for efficient oxygen electrocatalysis.