This study proposes an anion-mediated d-d coupling strategy by introducing B atoms to replace oxygen atoms. This modification generates high-spin Co²⁺Oh, leading to a significant enhancement of the density of states near the Fermi level. The orbital coupling between adjacent Co−O/B−Co units undergoes a dramatic magnetic transition, shifting from antiferromagnetic coupling (TN = 25 K) to ferromagnetic coupling (TC > 850 K). This CoOh-d orbital engineering enhances carrier concentration and reduces electron transfer resistance. Electrochemical analysis indicates that Co₃O₃.₆₅B₀.₃₅ exhibits excellent catalytic performance, with an overpotential of 295 mV at a current density of 30 mA cm⁻², compared to 441 mV for the pristine Co₃O₄. Furthermore, the application of a 500 mT magnetic field can further reduce the overpotential by 25.3%. In situ ATR-SEIRAS combined with theoretical calculations revealed that the orbital overlap between the Co 3d and O 2p states is significantly enhanced following spin ordering, which strengthens σ-bond interactions and promotes the adsorption of the *OOH intermediate. By regulating d–d exchange interactions, this study provides a viable strategy for the rational design of ferromagnetic OER catalysts and holds broader implications for the development of magnetoresponsive electrocatalysts.
Article link: https://pubs.acs.org/doi/10.1021/jacs.5c18826