Asymmetric Oxygen Bridges: A Unified Design Framework for Enhanced Catalysis

The asymmetric oxygen bridges (AOBs), composed of asymmetric Metal₁-Oxygen-Metal₂ (M₁-O-M₂) with intrinsic electronic and geometric asymmetry, have gained significant attention in heterogeneous catalysis. The intrinsic asymmetric coordination induces unique and controllable interfacial charge polarization, which have recently inspired novel design concepts to achieve improved structure-activity relationships. However, fully exploiting their potential requires a systematic framework to unify design principles. This review systematically presents the unique characteristics of AOBs originated by the different valence states, ionic radius and electronegativities of oxygen bridged metal sites. By analyzing the structure-activity relationship between atomic-scale charge polarization and lattice strain with macroscopic functionality, the enhancing mechanisms of AOBs from categories including heteronuclear AOBs, homonuclear hetero-valent AOBs, heteroatoms modified AOBs and dynamically tunable AOBs is illustrated. These insights will provide new opportunities for understanding of catalytic mechanisms, the design of highly efficient catalysts and the development of more efficient energy conversion technologies.