Surface-engineered CeO bond architectures maximizing atomic efficiency for superior oxygen reduction in magnesium-air battery systems.

The strategic design of atomic-efficient catalysts through targeted bonding engineering remains pivotal for advancing oxygen reduction reaction (ORR) in metal-air batteries. This study pioneers a comparative investigation between surface-engineering CeO bond construction (Ce surface decorated MnO, Ce-SD-MnO) and conventional bulk doping strategy (Ce bulk doping MnO, Ce-BD-MnO), revealing fundamental structure-activity relationships. Advanced High-Angle Annular Dark-Field Scanning Transmission Electron Microscopy (HAADF-STEM) and X-ray Absorption Fine Structure (XAFS) analyses demonstrate that surface-anchored Ce atoms induce localized lattice distortion in Ce-SD-MnO, generating synergistic surface defects and oxygen vacancies, while Ce-BD-MnO merely causes non-active lattice expansion. First-principles calculations unveil that surface CeO motifs optimally modulate the Mn d-band center, simultaneously enhancing charge density near the Fermi level and reducing *OOH adsorption energy. These atomic-level synergies empower Ce-SD-MnO with exceptional ORR activity and durability. Implemented in Magnesium-air batteries, the surface-engineered catalyst delivers excellent performance: 120.7 mW cm peak power density (46.3 % enhancement vs bulk-doped counterpart) and 98.5 % voltage retention after 11 h, establishing new stability benchmarks. This work provides fundamental insights into surface bond engineering for breaking the atomic efficiency-stability trade-off, offering a universal paradigm for designing energy conversion catalysts.