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

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 (FeCoNiMnWO4, HEW) with CeO2 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-CeO2 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.