Half-ordered bisymmetry breaking induced by spin-orbit-coupling-dependent alternating atomic hybridization accelerate acidic oxygen evolution reaction.

The development of non-noble metal oxide catalysts for oxygen evolution reaction (OER) under acidic conditions is critical to sustainable energy conversion and storage. However, achieving catalytic performance comparable to that of noble metals remains a significant challenge. Herein we leverage crystal field theory and the site occupancy preferences of magnetic ions to introduce magnetic sites in a half-selective manner into the conventional spinel-structured catalyst Co3O4, thereby realizing alternating atomic hybridization within the crystal lattice. Drawing on the long-range exchange interaction in a half-ordered crystal field, bisymmetry breaking occurs thanks to the synergistic effect of the double magnetic sites, triggering a controllable spin-state transition at the active site. Meanwhile effective metal-adsorbate bonding induced by enhanced spin-orbit coupling leads to fast charge transfer and low rate-determining barrier. As a result, the spin-electron state modulated Co4Fe2MnOx delivers an OER overpotential drastically reduced by 240 mV compared to the conventional Co3O4, while maintaining outstanding stability of over 300 h at a high current density of 200 mA cm-2. This work provides a new insight into the design of high-performance non-noble metal oxide catalysts for acidic OER applications.