Oxide Heterostructure Engineering Drives Stable Lattice Oxygen Evolution for Highly Efficient and Robust Water Electrolysis

Achieving a highly active and stable oxygen evolution reaction (OER) is critical for the implementation of water electrolysis in green hydrogen production but remains challenging. Steering the OER pathway from an adsorbate evolution mechanism (AEM), where a metal site serves as the active site, to the lattice oxygen mechanism (LOM) has been found to enhance OER activity; however, it suffers from low stability. In this work, we propose to construct CuO_x/Co₃O₄ heterointerface, which enables the realization of a stable LOM pathway. The lattice oxygen characteristics are modulated near the heterointerface, resulting in a shift in the reaction pathway from AEM to LOM. In situ X-ray Absorption Fine Structure results further reveal that the valence state of cobalt is stabilized during the OER process, which alleviates corrosion of cobalt and maintains LOM stability. Consequently, the obtained CuO_x/Co₃O₄ exhibits outstanding activity and stability for overall water electrolysis in freshwater, natural seawater, and high-salt wastewater, with a low overpotential of 308 mV at 100 mA cm^-2 and stable overall water electrolysis at 500 mA cm^-2 for 100 h. Our work demonstrates interface engineering as an effective strategy to activate and stabilize lattice oxygen, advancing the design of high-performance electrocatalysts for energy and environmental applications.