Rational modulaion of Fe-N4 coordination symmetry through heteroatom doping with distinct electronegativities has emerged as a promising strategy to optimize the performance of the oxygen reduction reaction (ORR). Here, we systematically investigate the less electronegative sulfur- and phosphorus-doped Fe single-atom catalysts and demonstrate that the S-doped catalyst (Fe-SNC) achieves superior ORR activity (E1/2 = 0.904 V vs. RHE), surpassing both the P-doped Fe-PNC (0.872 V) and undoped Fe-NC control samples while maintaining exceptional durability. Synchrotron radiation X-ray absorption spectroscopy verified the precise engineering of the asymmetric Fe-S1N3 and Fe-P1N3 configurations within the ZiF-8-derived carbon matices, confirming successful manipulation of the first coordination sphere. In situ svnchrotron radiation infared spectroscopy further elucidates accelerated *OOH dissociation kinetics in Fe-SNC, which benefts from the optimization of the electronic structure of Fe 3d by S doping. These findings conclusively establish geometric symmetny breaking via electronegativity-driven electronic modulation as an effective strategy for advancing metal-N4 catalyst design.
