Support Protection Mechanism Enables Efficient and Stable Anion Exchange Membrane Water Electrolyzers

Designing oxygen evolution reaction (OER) catalysts that simultaneously achieve high activity and long-term stability remains a critical challenge for the development of alkaline anion exchange membrane water electrolyzers (AEMWEs). Here, we uncover a unique support protection mechanism in which lattice-confined ruthenium (Ru) single atoms offer robust protection for the spinel Co3O4 support, realizing outstanding stability in AEMWEs. Theoretical calculations and structural characterizations reveal that lattice confinement promotes the formation of robust Ru-O-Co bridges by simultaneously shortening the Co-O and Ru-O bond lengths, thereby suppressing Co dissolution and optimizing the electronic structure for efficient catalysis. Furthermore, in situ electrochemical analysis demonstrates that the lattice confinement of Ru atoms accelerates OER kinetics through facilitated proton-coupled electron transfer (PCET) steps and partially activated lattice oxygen. As a result, the RuLCA-Co3O4 dominated by the adsorbate evolution mechanism (AEM) exhibits a lower overpotential of 260 mV at 10 mA cm-2, which is lower than that of RuSCA-Co3O4 dominated by the lattice oxygen mechanism (LOM) pathway. Meanwhile, the lattice-confined RuLCA-Co3O4 exhibits nearly 9-fold lower Co dissolution compared to surface-coordinated RuSCA-Co3O4 after an accelerated durability test (ADT). Moreover, RuLCA-Co3O4 maintains an outstanding stability for over 1000 h in an AEMWE system with a low degradation rate of 88.1 μV h-1, outperforming RuSCA-Co3O4. This work establishes lattice confinement as an effective strategy to decouple activity-stability trade-offs in alkaline OER and provides a viable design principle for durable AEMWE anodes.