• Ni3Fe oxide nanoparticles (3.5 ± 1.5 nm) were successfully anchored onto polyaniline (PANI) support via a solvothermal strategy followed by calcination, creating a robust hetero-interface.
• The catalyst–support interaction between Ni3Fe oxide and PANI enhances Ni–O covalency through interfacial Ni–N bonds, significantly boosting charge and mass transfer during oxygen evolution reaction (OER).
• The Ni3Fe oxide/PANI catalyst exhibits outstanding OER performance with a low overpotential of 270 mV at 10 mA cm−2 and a specific activity 3.84 times higher than unsupported Ni3Fe oxide.
• Rechargeable Zn-air batteries assembled with Ni3Fe oxide/PANI achieve superior cycling stability, maintaining operation for over 400 hours at 10 mA cm−2 with a low charge potential of ~1.95 V.