Dual‐Site Activation of High‐Entropy Alloy Electrocatalysts via Ruthenium‐Induced Electron Transfer for Alkaline Hydrogen Evolution

ABSTRACT Hydrogen evolution in alkaline media is kinetically limited by sluggish water dissociation, requiring catalysts that can accelerate both H 2 O activation and proton adsorption. Here, ruthenium‐incorporated high‐entropy alloys (Ru‐HEAs) are developed as efficient alkaline HER electrocatalysts by exploiting Ru‐driven electron redistribution within a multi‐metallic lattice. Spectroscopic analyses show that electronegative Ru atoms withdraw electrons from neighboring Co and Ni atoms, shifting them to higher oxidation states and modifying their local electronic environments. This electronic modulation activates Co/Ni sites simultaneously. DFT calculations confirm that Co and Ni serve as the dominant adsorption centers, and that Ru incorporation alters their d‐band centers to lower both the thermodynamic and kinetic barriers of water dissociation while shifting hydrogen adsorption toward near‐thermoneutral energetics. As a result, Ru‐HEA/C delivers a low overpotential of only 29 mV at 10 mA cm − 2 and a Tafel slope of 67.8 mV dec − 1 with high Ru mass activity, outperforming pristine HEA and commercial Ru/C despite its low Ru loading. These findings clarify the role of Ru atoms in a high‐entropy environment as an electronic modulator that triggers dual‐site activation rather than merely providing additional active sites. This work establishes a generalizable design principle for HEA electrocatalysts optimized for alkaline hydrogen evolution.