Interfacial Electric Field Engineering of High‐Entropy Heterostructures Triggering Self‐Limiting Reconstruction for Industrial‐Scale Electrocatalysis

ABSTRACT Severe structural degradation of electrocatalysts under ampere‐level operation remains a formidable bottleneck for industrial‐scale green hydrogen production. Herein, an interfacial electric field engineering strategy is reported by integrating a high‐entropy tungstate (FeCoNiMnWO 4 , HEW) with CeO 2 nanoparticles. Theoretical calculations and direct surface potential mapping reveal that the intrinsic Fermi level offset drives spontaneous electron transfer, establishing a robust built‐in electric field (BIEF) at the heterointerface. In situ spectroscopy and comprehensive thermodynamic analyses uncover that this engineered field acts as a critical regulator, inducing a “self‐limiting” surface amorphization. The BIEF thermodynamically triggers the sacrificial leaching of metastable W species to form a highly active metal oxyhydroxide layer, while a high barrier for continuous lattice oxygen consumption prevents catastrophic bulk degradation. This regulated phase evolution directs the steady‐state catalysis exclusively via the adsorbate evolution mechanism (AEM), lowering the thermodynamic barrier of the rate‐determining step ( * OH → * O). Consequently, the HEW‐CeO 2 heterostructure delivers exceptional oxygen evolution reaction (OER) performance, requiring only 337 mV overpotential to sustain 1000 mA cm −2 for over 100 h. This work establishes a versatile paradigm for coupling interfacial field engineering with dynamic phase evolution in advanced energy conversion.