A Thermodynamic–Kinetic Rethinking of Lattice Oxygen Mechanisms in Water Oxidation

The structural complexity of catalyst surfaces renders the mechanism of heterogeneous water oxidation highly debated. Nevertheless, three principal reaction pathways, the adsorbate evolution mechanism (AEM), the lattice oxygen mechanism (LOM), and the oxygen coupling mechanism (OCM), have been widely proposed to account for the critical O─O bond formation step during water oxidation. Among them, LOM has garnered significant attention, motivating the development of catalysts designed to activate lattice oxygen. However, the development of highly efficient catalysts based on either AEM or LOM remains controversial, and there is no consensus on whether catalytic activity and stability are directly governed by a particular mechanism. This perspective assesses commonly employed characterization techniques to identify the LOM, emphasizing potential sources of misinterpretation that may lead to misleading conclusions. Furthermore, a comprehensive thermodynamic and kinetic analysis of the LOM is presented, revealing conceptual pitfalls that often arise in mechanistic assignments. A more precise understanding of the lattice oxygen oxidation pathway is urgently needed to elucidate the exact role of lattice oxygen in the evolution of molecular oxygen in heterogeneous systems.