Lattice Oxygen Redox Mechanisms in the Alkaline Oxygen Evolution Reaction

Understanding of fundamental mechanism and kinetics of the oxygen evolution reaction (OER) is pivotal for designing efficient OER electrocatalysts owing to its key role in electrochemical energy conversion devices. In the past few years, the lattice oxygen oxidation mechanism (LOM) arising from the anodic redox chemistry has attracted significant attention as it involves a direct OO coupling and thus bypasses thermodynamic limitations in the traditional adsorbate evolution mechanism (AEM). Transition metal-based oxyhydroxides are generally acknowledged as the real catalytic phase in alkaline media. In particular, their low-dimensional layered structures offer sufficient structural flexibility to trigger the LOM. Herein, a comprehensive overview is provided for recent advances in anion redox from LOM-based electrocatalysts. Based on analyses of electronic structure of electrocatalysts and LOM, a strategy is proposed to activate LOM. Possible identification techniques for corroboration of the oxygen redox are also reviewed. In addition, the structural reconstruction process induced by the LOM is focused and the importance of multiple in situ/operando characterizations is highlighted to unveil the structural and chemical origins of the LOM. To conclude, a prospect on the remaining challenges and future opportunities for LOM electrocatalysts is presented. Recent advances concerning lattice oxygen oxidation mechanism (LOM)-based electrocatalysts in alkaline media are comprehensively summarized. The strategy is systematically introduced for triggering LOM, together with theoretical and experimental methodologies for the identification of LOM. The applications of advanced in situ/operando technologies are highlighted to uncover the chemical and structural origins of LOM. Finally, current challenges and future opportunities for LOM electrocatalysts are presented. image