Rectifying Contact-induced Electronic Regulation of Fe Within Nitrogen-Doped Carbon for Enhanced Oxygen Reduction Reaction.

Developing efficient and durable oxygen reduction reaction (ORR) electrocatalysts from earth-abundant elements is of great significance for the advancement of sustainable energy technologies such as rechargeable zinc-air batteries. Herein, we present a 3D honeycomb-like nitrogen-doped carbon matrix decorated to in-situ form Fe nanoparticles (denoted as Fe-NPs@N-HC) via an ice-templating method. Theoretical calculations and experimental analyses collectively reveal that the work function mismatch between metallic Fe and the N-doped carbon host drives spontaneous charge transfer, establishing a built-in electric field at the heterointerface to form the rectifying contact. This interfacial effect fine tunes electronic structure and optimizes the adsorption of oxygen intermediates, thereby accelerating the ORR kinetics. Benefiting from these synergistic effects, Fe-NPs@N-HC achieves a half-wave potential of 0.86 V, superior tolerance to methanol, and excellent long-term durability in alkaline media. When integrated into a liquid zinc-air battery, Fe-NPs@N-HC also delivers a high peak power density of 126.4 mW cm-2 and outstanding cycling stability exceeding 482 cycles, surpassing the benchmark Pt/C-based system. This work demonstrates that tailoring the electronic structure through interfacial engineering, coupled with rational 3D framework design, provides a promising strategy for the development of next-generation nonprecious metal catalysts for practical energy conversion applications.