Dynamic trade-off of electronic structures to activate and stabilize lattice oxygen via a Ceδ+–O/Co–Fe hydroxide interface for industrial level water oxidation†

Developing highly active lattice oxygen mechanism (LOM)-based oxygen evolution reaction (OER) catalysts capable of stable operation under high potential remains a critical bottleneck for advancing anion exchange membrane water electrolysis (AEMWE) technology. Herein, we propose dynamic modulation of the electronic structure of the electrocatalyst during the OER utilizing the flexible redox states of Ce^δ+ as an electronic buffer. Specifically, at the OER activation stage, CeO₂ with lower Fermi levels accelerates surface reconstruction of Fe–Co(OH)₂ into active phase Co(IV)–O_x to trigger the LOM. Subsequently, the formative Co(IV)–O_x can reverse-trap electrons from CeO₂ to maintain a stable chemical state under high bias. This shuttling of electrons between Co²⁺ → Ce^3+/4+ and Ce^3+/4+ → Co^3+/4+ can activate and stabilize lattice oxygen, thereby synergistically enhancing both intrinsic activity and stability. Remarkably, the constructed CeO₂/Fe–Co(OH)₂ catalyst demonstrates outstanding activity (189 and 346 mV at 10 and 1000 mA cm⁻²) and viable durability (800 h at 1000 mA cm⁻²), achieving 1000 mA cm⁻² at 1.78 V for 1600 h in practical AEMWE setups. This work provides a promising avenue for designing high-efficiency and durable OER catalysts, addressing key challenges in AEMWE technology.