The oxygen evolution reaction (OER) is crucial for proton exchange membrane (PEM) water electrolysis; how ever, the development of economical and sustainable anode catalysts remains a great challenge. Here, we engineered spinel Co3O4 nanorods (NRs) through a tetra/octahedral crystal field proportion modulation strategy to form a type of asymmetric bimetallic catalytic sites in the compression-strained Co–O lattice ((Ir, F)-Co3O4 NRs), achieving a low overpotential of 226 mV at 10 mA cm− 2 and maintaining a stable cell voltage of 1.59 V for 150 h at 0.30 A cm− 2 with negligible decay in the PEM device. The substitution of cationic Irx+ for Co3+ in the octahedral sites effectively modulates the ratio of tetrahedral to octahedral crystal fields in spinel Co3O4. Together with the compression strain in the Co–O lattice induced by the anionic Fx- doping, the asymmetric bimetallic sites with lowered oxidation state and shortened Co–Ir distance are fabricated. In situ X-ray ab sorption and synchrotron radiation infrared techniques reveal that the activated Ir–Co synergistic bimetallic sites, with optimal interatomic spacing, provide an ideal configuration for *O–O* radical coupling, thereby driving the catalytic process to follow a kinetically accelerated oxide pathway mechanism. This work offers valuable insights into the strain-induced optimal pathway mechanism for advancing industrial PEM water electrolysis applications.
