Magnetic-Field-Induced Spin Polarization Boosts Piezoelectric SrFeO ₃ -Catalyzed H ₂ O ₂ Production

Manipulating spin states with external fields provides a powerful yet underexplored strategy for controlling interfacial charge transfer in piezoelectric catalysis. Here, we demonstrate that introducing a static magnetic field into a piezoelectric SrFeO₃ system enables modulation of the two-electron oxygen reduction reaction (2e⁻ ORR) kinetics via spin polarization. The magnetic field induces pronounced Fe spin polarization, offering a continuously tunable alternative to conventional chemical modification. X-ray magnetic circular dichroism (XMCD) and density functional theory (DFT) reveal that field-driven spin states lower the energy barrier for *OOH formation and weaken the Fe-O bond, preventing overbinding of intermediates. These effects significantly accelerate reaction kinetics, yielding a peak H₂O₂ production of 464.56 μmol L⁻¹ under 400 mT after 60 min-6.5 times higher than without a field. This work establishes magnetic-field-assisted piezocatalysis as a versatile platform for spin-state engineering, highlighting the transformative potential of magnetic control in catalytic energy conversion.