Stable Electronic Asymmetry on Ru Nanoclusters Triggered by the Ru‐O‐Ce Bridge Structure for Efficient Hydrogen Energy Conversion

Abstract The electrocatalytic efficiency of Ru clusters directly depends on their surface valence states, with a critical challenge being the sustained coexistence of high‐valent Ru ⁿ⁺ and metallic Ru ⁰ sites during hydrogen energy conversion. Herein, a strategy is proposed utilizing metal‐support interfacial chemical bonds to create electronic asymmetry in Ru clusters, forming stable Ru ⁿ⁺ ‐Ru ⁰ ensembles. This concept is embodied in Ru _NC ‐O‐Ce _SA /C, a novel electrocatalyst where Ce single atoms and Ru nanoclusters are anchored on oxygen‐functionalized carbon and interconnected via Ru‐O‐Ce bridge bonds. In situ Raman spectroscopy and theoretical analyses reveal that Ru‐to‐Ce electron transfer through these bridge bonds induces stable electronic asymmetry within Ru clusters, spatially separating Ru ⁿ⁺ (near bonds) and Ru ⁰ (far from bonds) sites. These engineered sites optimally adsorb OH (Ru ⁰ ) and H (Ru ⁿ⁺ ), respectively. In addition, the unique Ru ⁰ ‐Ru ⁿ⁺ combination are particularly effective in enhancing the transport rates of interfacial H ₂ O. These synergetic interactions are responsible for the high electrocatalytic activity of the Ru _NC ‐O‐Ce _SA /C electrocatalyst, with both its alkaline hydrogen evolution reaction (HER) and hydrogen oxidation reaction (HOR) mass activity being an order of magnitude higher than those of commercial Pt/C. This work establishes chemical bond‐mediated electronic asymmetry engineering as an effective approach for designing advanced multivalent electrocatalysts.