Construction of Asymmetric Fe‐N₃P₁ Sites on Freestanding Nitrogen/Phosphorus Co‐Doped Carbon Nanofibers for Boosting Oxygen Electrocatalysis and Zinc–Air Batteries

Abstract The construction of freestanding carbon nanofiber membrane with single‐atomic metal active sites and interconnected microchannels as air electrodes is vital for boosting the performance of zinc–air batteries (ZABs). Herein, single‐atomic Fe sites is prepared on freestanding hierarchical nitrogen/phosphorus co‐doped carbon nanofibers (Fe SACs@PNCNFs) by loading Fe‐doped zeolitic imidazolate framework‐8 with leaf‐like structures on electrospun polyacrylonitrile (PAN) nanofibers with subsequent multi‐step pyrolysis in the presence of sodium monophosphate, which are confirmed to be in the form of Fe‐N₃P₁ by X‐ray adsorption spectra. The asymmetric N/P coordinated Fe sites is theoretically demonstrated to boost the ORR performance with a half‐wave potential of 0.89 V due to the weakened ^*O adsorption while stabilizing ^*OOH adsorption arising from the increased charge density of Fe sites compared to symmetric N coordinated Fe sites with Fe‐N₄. Moreover, when liquid and quasi‐solid ZABs are assembled, excellent battery performance is also achieved with peak power density of 163 and 72 mW cm⁻² as well as good stability for more than 190 and 65 h, respectively.