Electronegativity‐Guided Site Differentiation in High‐Entropy Alloy for pH‐Universal Hydrogen Evolution Reactions

ABSTRACT Enhancing the intrinsic activity of transition metal catalysts for the hydrogen evolution reaction (HER) remains a critical challenge in sustainable energy conversion. Herein, we report an electronegativity‐guided site differentiation strategy in a single‐phase CoNiCuMoW high‐entropy alloy (HEA) via electrodeposition by incorporating high‐electronegativity 4 d /5 d orbital transition metals (Mo, W) into the face‐centered cubic ( fcc ) matrix (CoNiCu). The as‐synthesized HEA demonstrates exceptional HER performance in all pH conditions, delivering an outstanding overpotential of 65 mV (alkaline), 28 mV (acidic), and 155 mV (neutral) at a current density of 100 mA cm −2 , showing performance comparable to commercial Pt/C and has excellent long‐term stability at high current density (1 A cm −2 , 1000 h). X‐Ray absorption spectroscopy (XAS) and density functional theory (DFT) calculations reveal that the incorporation of Mo/W simultaneously alters the local coordination environment and induces element‐dependent charge redistribution, accompanied by a system‐level d‐ band center downshift, thereby optimizing the hydrogen binding strength across multimetallic sites. Meanwhile, oxophilic Mo/W sites lower the water dissociation energy barrier. These synergistic effects collectively enable efficient and durable pH‐universal HER performance.