Modulation of d-d orbital hybridization via creating asymmetrical paired iron sites for oxygen reduction reaction
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Zhijun Li , Hongxue Liu , Yunlu Chen , Siqi Ji , Xue Lu , Wenkai Yang , Yu Wang , J. Hugh Horton , Yujia Tang and Xinlong Tian
First published on 8th May 2026
Abstract
Diatomic catalysts bearing unique electronic structures hold promise for accelerating the kinetically sluggish oxygen reduction reaction (ORR). However, a rational design principle for modulating metal sites’ microenvironments to boost activity and stability is challenging. Herein, we present a coordination manipulation strategy to create paired Fe sites directly bonding with the P heteroatom in Fe2P1N5 moieties over a nitrogen-doped carbon matrix (Fe2/NCP). This catalyst delivers high ORR activity with half-wave potentials of 0.94 and 0.82 V in alkaline and acidic conditions, respectively, along with robust structural stability. The strong ORR activity and stability are further validated using zinc-air batteries incorporating the catalyst. Such performance enhancement originates from the electron spin-state modulation and electronic delocalization due to the P doping. This strengthens the d‒d orbital hybridization for spin electron filling in the Fe 3dz2 orbital, which suppresses the electron donation from the absorbate-σ orbital to facilitate *OH desorption. This work underscores the importance of asymmetrical electronic structure manipulation in designing high-performance metal catalysts.