Coupled Synergistic Pathway of FeOOH/CeF ₃ Heterojunction Toward High‐Current‐Density and Durable Oxygen Evolution Reaction

ABSTRACT Designing effective and durable electrocatalysts for the oxygen evolution reaction (OER) that can operate sustainably under high current densities remains a critical challenge. A significant obstacle lies in overcoming the inherent trade‐off between activity and stability, primarily caused by the linear scaling relationships of adsorbates in multi‐step reactions and the formation of oxygen vacancies associated with lattice oxygen participation. Herein, we report a FeOOH/CeF 3 heterojunction catalyst on nickel foam that leverages reversible Ce 3+ /Ce 4+ redox couples and highly electronegative fluorine to accelerate electron transfer across the interface, resulting in a high d‐band electron occupancy at Fe sites. At the atomic scale, this heterointerface enhances Fe–O bond covalency and lattice stability, moderately activating lattice oxygen while suppressing Fe peroxidation and dissolution. In situ studies confirm that the catalyst synergizes the adsorbate evolution mechanism with the lattice oxygen mechanism, disturbing the conventional activity‐stability trade‐off. The optimized electrocatalyst achieves low overpotentials of 194 and 224 mV at 10 and 100 mA cm −2 , respectively, and sustains over 200 h of operation at 500 mA cm −2 . This study offers an efficient heterostructure design strategy for high‐performance OER via dual‐mechanism coupling.