Stabilization of Lattice Oxygen Evolution Reactions in Oxophilic Ce‐mediated Bi/BiCeO_1.8H Electrocatalysts for Efficient Anion Exchange Membrane Water Electrolyzers

AbstractThe lattice oxygen mechanism (LOM) offers an efficient reaction pathway for oxygen evolution reactions (OERs) in energy storage and conversion systems. Owing to the involvement of active lattice oxygen that enhances electrochemical activity in this approach, addressing the structural and electrochemical stabilities of LOM materials is crucial. Therefore, it is important to devise effective strategies for activating lattice oxygen in such materials while minimizing material deformations and ion elution. Herein, a heterostructure (Bi/BiCeO1.8H) containing abundant under‐coordinated oxygen atoms having oxygen nonbonding states is synthesized by a simple electrochemical deposition method. Given the difference in reduction potentials between Bi and Ce, partially reduced Bi nanoparticles and surrounding under‐coordinated oxygen atoms are generated in BiCeO1.8H. It is found that the lattice oxygen can also be activated as a reactant of the OER when the valence state of Bi increases to Bi5+, increasing metal–oxygen covalency and that the oxophilic Ce3+/4+ redox couple allows maintaining the Bi nanoparticles and surrounding under‐coordinated oxygen atoms by preventing over‐oxidation of Bi. As a demonstration of the practical applications, an anion exchange membrane water electrolyzer (AEMWE) with Bi/BiCeO1.8H as the anode is analyzed. The AEMWE exhibits a low cell voltage of 1.79 V even at a high practical current density of 1.0 A cm−2. Furthermore, the cell performance remains significantly stable over 100 h with only a 2.2% increase in the initial cell voltage, demonstrating sustainable lattice oxygen redox.This article is protected by copyright. All rights reserved