Atomic-level Geometric Engineering Modulating d-s Hybridization of Ordered RuGa Intermetallic for Efficient Hydrogen Electrocatalysis.

Ruthenium (Ru) is a promising alternative to platinum for hydrogen oxidation (HOR) and evolution (HER), yet its intrinsically strong hydrogen binding, governed by its atomic geometry, limits activity. Herein, we report a highly efficient and durable RuGa intermetallic catalyst with an atomically ordered structure that disrupts the geometric symmetry of Ru, thereby optimizing hydrogen adsorption. The catalyst achieves a specific exchange current density of 1.02 mA cm⁻ ² and a mass activity of 1850 mA mgRu ⁻ ¹ for HOR, 5.5- and 3-fold higher than Ru/C, respectively. For HER, it requires only 11 mV to reach 10 mA cm⁻ ² and shows a 7.4-fold higher mass activity than Ru/C. Remarkably, it exhibits negligible degradation after 1000 HOR and 10 000 HER cycles. Density functional theory calculations and in situ Raman analyses reveal that geometric engineering enhances Ru 4d-H 1s hybridization, weakens Ru-H bonding, and lowers hydrogen adsorption energy, thus accelerating HER/HOR kinetics and preventing active-site poisoning. This work establishes a paradigm for designing high-performance Ru-based electrocatalysts through atomic-level geometric modulation.