Modulating the Spin Structure of LiFeO 2 by Cr Substitution for Oxygen Electrocatalysis

The oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) are crucial for renewable energy technologies like fuel cells and metal‐air batteries, yet their performance is limited by sluggish kinetics. Addressing the need for efficient catalysts, a series of Cr‐doped LiFeO 2 (LiFe 1‐x Cr x O 2 , x = 0.00 to 1.00) have been synthesized via a sol‐gel method for ORR and OER catalysis. Among these, LiFe 0.25 Cr 0.75 O 2 exhibits superior bifunctional oxygen electrocatalytic activity (0.74 V and 1.58 V vs. RHE to reach 25 µA cm oxide −2 for ORR and OER). In LiFe 1‐x Cr x O 2 , a structural transformation from a fcc to a layered hexagonal phase has been observed with Cr increasing, enhancing cation ordering and ion transport capability. Cr doping also modulates the spin state of Fe active sites, reducing the effective magnetic moment and e g orbital occupancy, thereby strengthening Fe–O bonding. Following a “dual‐metal competitive bonding” mechanism, the strengthened Fe─O bond weakens the coordination with adjacent metal sites, shifting the adsorption configuration from bridging to atop M 1 O 1 , thereby promoting OOH desorption. Furthermore, this study innovatively introduces the total bonding energy of dual‐metal dioxygen atoms (B ICOHP ) as a novel OER activity factor, providing new theoretical insights and experimental guidance for designing spin‐regulated transition metal oxide catalysts.