Regulative Fe‐3d Orbitals via Lying‐Down Conformation of Metalorganic Molecules‐Axially Coordinated MXene for Rechargeable Zn–Air Batteries

Abstract A bifunctional electrocatalyst is developed, exhibiting high catalytic activity and reversibility for the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) through a regulative Fe d‐orbital engineering strategy. In this strategy, iron phthalocyanine organic molecule (FeOM) crystals are axially coordinated onto multilayer Mo ₂ CT _x MXene (FeOM‐Mo ₂ CT _x ), adopting a lying‐down conformation. This hybridization fosters unique electronic guest–host interactions, with FeOM donating charge to Mo ₂ CT _x via Fe−O bonding, leading to symmetry breaking in electronic distribution and modified delocalization of Fe‐3d charge, accompanied by a Fe(II) spin‐state transition. These transformations enhance the adsorption and desorption toward oxygenated intermediates, optimizing the ^* OOH− ^* O transition to boost the reversibility of ORR and OER kinetics. The FeOM‐Mo ₂ CT _x exhibits a favorable ORR half‐wave potential of 0.961 V and a minimal OER overpotential of 349 mV at 10 mA cm ⁻² in 1.0 m KOH. The assembled aqueous zinc‐air battery (ZAB) achieves a peak power density of 155.3 mW cm ⁻² and exceptional charge–discharge durability over 1500 h, outperforming a conventional (Pt/C + RuO ₂ ) system. Overall, the findings underscore the significance of electronic structural engineering of FeOM with Mo ₂ CT _x , paving the way for innovative air cathodes in the development of rechargeable ZABs with enhanced performance and cost‐effectiveness.