Three-atom bridged centers activate inert electrons in MXene via Ti 3d orbital engineering to enhance electrocatalysis in lithium‑oxygen batteries

Rare-earth element doping-induced d orbital reconstruction of transition metals emerges as a critical mechanism to overcome the bottleneck of bifunctional catalytic activity in lithium-oxygen (Li O 2 ) batteries. By implementing a cerium doping defect engineering strategy, this study constructs [Ce C Ti] triatomic bridged active centers on MXene surfaces and systematically unravels the cross-scale regulation mechanism governing electronic structure deposition morphology electrochemical performance in MXene-based catalysts. Combined theoretical calculations and experimental characterizations demonstrate that the interfacial charge gradient field enables directional control of Li 2 O 2 epitaxial growth orientation, thereby inducing hierarchical porous structures while synergistically optimizing oxygen species adsorption/desorption kinetics. The [Ce C Ti] bonding disrupts inert electron chains and initiates electronic reconstruction effects, which significantly reduce reaction energy barriers through decoupling of O O bond orbital coupling strength, ultimately achieving self-consistent enhancement of oxygen reduction/evolution reaction activities. This work not only confirms the unique advantage of rare-earth element doping in modulating d orbital electron occupancy of transition metals but also elucidates the interfacial electron-lattice synergy in regulating oxygen electrode reaction pathways.