Modulating Electronic Spin State of Perovskite Fluoride by Ni─F─Mn Bond Activating the Dynamic Site of Oxygen Reduction Reaction

Abstract Establishing the relationship between catalytic performance and material structure is crucial for developing design principles for highly active catalysts. Herein, a type of perovskite fluoride, NH ₄ MnF ₃ , which owns strong‐field coordination including fluorine and ammonia, is in situ grown on carbon nanotubes (CNTs) and used as a model structure to study and improve the intrinsic catalytic activity through heteroatom doping strategies. This approach optimizes spin‐dependent orbital interactions to alter the charge transfer between the catalyst and reactants. As a result, the oxygen reduction reaction (ORR) activity of NH ₄ MnF ₃ on CNTs is significantly enhanced by partial substitution of Mn sites with Ni, such as a half‐wave potential (E _1/2 ) of 0.86 V and a limiting current density of 5.26 mA cm ⁻² , which are comparable to those of the commercial Pt/C catalysts. Experimental and theoretical calculations reveal that the introduction of Ni promotes lattice distortion, adjusts the electronic states of the active Mn centers, facilitates the transition from low‐spin to intermediate‐spin states, and shifts the d ‐band center closer to the Fermi level. This study establishes a novel approach for designing high‐performance perovskite‐based fluoride electrocatalysts by modulating spin states.