Coupling Built‐in Electric Field and Lewis Acid Triggers the Lattice Oxygen‐Mediated Mechanism for Efficient Water Oxidation

Abstract The oxygen evolution reaction catalyst triggering lattice oxygen‐mediated mechanism (LOM) can break the activity limitation imposed by the adsorbate evolution mechanism scaling relationship. However, triggering LOM is challenging due to the thermodynamic disadvantages associated with lattice oxygen redox reactions. Here, a Lewis acid‐modified layered double hydroxides (LDH) heterojunction catalyst (LDH/Cr 2 O 3 ) is designed. The asymmetric charge distribution at the heterojunction interface, induced by the built‐in electric field, shifts the electron transfer center from the lower Hubbard band to non‐bonding oxygen, thereby activating LOM. The enrichment of OH − and the enhanced covalency of the metal‐oxygen bond by Lewis acid optimize the pH‐dependent and high‐energy consumption during the hydroxyl (OH * ) deprotonation process of LOM. Furthermore, the activation of lattice oxygen and accelerated OH * deprotonation facilitate the surface reconstruction of LDH. Consequently, the LDH/Cr 2 O 3 exhibits excellent catalytic activity, with an overpotential of only 237 mV (at 10 mA cm −2 ) in 1.0 m KOH electrolyte. The catalyst maintains excellent activity in simulated seawater and 0.1 m KOH electrolyte. Furthermore, it demonstrates outstanding practical functionality, as the assembled commercial‐scale alkaline electrolyzer operates stably for 50 h. This work may provide new approaches and theoretical insights for triggering and optimizing LOM.