Confinement Phosphorization Strategy Unlocks FeP–N–C Catalysts for Highly Stable Zinc‐Air Batteries

Abstract

ABSTRACT Rechargeable zinc‐air batteries (RZABs) are promising next‐generation energy storage systems due to their high theoretical energy density. However, their practical application is hindered by the slow reaction kinetics of oxygen reduction/evolution (ORR/OER) at air cathodes. Herein, an innovative N‐rich copolymer‐confined phosphorization strategy for synthesizing FeP nanoparticles encapsulated in carbon matrix (FeP–NPC) has been developed. The methodology employs an iron‐phytic acid/aniline/pyrrole ternary copolymer precursor, achieving atomic‐level interfacial coupling between FeP nanocrystals and carbon substrate through precisely controlled phosphating thermodynamics. Electrochemical characterization reveals exceptional bifunctional activity with ORR onset potential of 1.04 V versus RHE (0.85 V half‐wave potential) and OER overpotential of 1.66 V at 10 mA cm −2 in 0.1 M KOH electrolyte, comparable to commercial Pt/C‐RuO 2 benchmarks. The assembled RZAB demonstrates a peak power density of 185.0 mW cm −2 with remarkable durability maintaining 53.5% round‐trip efficiency over 530 h cycling. Advanced spectroscopic analysis and DFT calculations elucidate that the N‐rich carbon matrix induces the formation of FeP–N–C active sites which facilitates d ‐band center downshifting of FeP via interfacial charge redistribution, thereby optimizing oxygen intermediate adsorption/desorption energetics. Furthermore, the conductive carbon network acts as an electron reservoir to facilitate charge transfer kinetics during bifunctional catalysis. This interface engineering strategy provides a paradigm for developing cost‐effective transition metal phosphide catalysts, advancing the practical implementation of metal‐air battery technologies in energy storage systems.