Harnessing π–d Orbital Hybridization in Non‐Conjugated Linker‐Engineered Iron‐Tetrapyrrole Frameworks to Boost Oxygen Reduction

Well‐defined Fe–N 4 molecular catalysts offer an ideal platform for probing oxygen reduction reaction (ORR) catalytic fundamentals, yet their rational molecular design remains challenging. More critically, the role and tunability of π–d orbital hybridization, a key electronic interaction between the Fe center and its organic matrix, are poorly understood, hindering electronic‐level catalyst optimization. To address these issues, we introduce a nonconjugated linker engineering strategy for constructing covalent organic polymers (COPs) with atomically precise iron‐tetrapyrrole units. By incorporating cycloalkane‐based spacers, we selectively tune the π–d orbital interaction between the Fe 3d orbitals and the tetrapyrrole π‐system. This deliberate electronic modulation optimizes the d‐band center and delocalizes electron density, thereby enhancing the intrinsic activity of the Fe–N 4 sites. The optimized polymer linked by cyclohexane (COP‐CYC) exhibits outstanding alkaline ORR performance, achieving a half‐wave potential of 0.90 V and a high turnover frequency of 0.835 e − site −1 s −1 . When integrated into ampere‐hour‐scale zinc–air batteries, COP‐CYC delivers a peak power density of 2.77 W and a capacity of 4.77 Ah, demonstrating its potential for high‐power, high‐capacity energy storage. This work not only establishes a clear relationship between linker‐modulated π–d orbital hybridization and ORR activity but also provides a generalizable molecular‐design strategy for advanced electrocatalysts.