Tunable Metal‐Hydrogen Bonding in Cu‐Ru Catalysts Enables Selective Hydrogen Storage Reactions in Mg‐Based Composite

Abstract Thermodynamic and kinetic limitations have long hindered the development of Mg‐based hydrogen storage materials (Mg/MgH ₂ ). While incorporating polyhydrides (e.g., LiBH ₄ and LiNH ₂ ) and catalysts enables Mg/MgH ₂ to operate under milder temperatures, these multi‐component systems often experience undesirable side reactions. Herein, we report that Ru‒Cu‐based intermetallic catalysts with optimized d ‐band centers can effectively address these challenges. MgCu ₂ employed in this study exhibits high chemical stability, with its phase and chemical properties remaining unchanged after multiple hydrogen storage cycles. Through Ru incorporation (Ru‐MgCu ₂ ), the d ‐band center is optimized, enhancing catalytic activity by 5.5 times compared to plain MgCu ₂ , without compromising its chemical stability. The Ru‐MgCu ₂ catalyzed Mg‐based composite achieves hydrogen release of 4.5 wt.% within 10 min at 200 °C and 2.3 wt.% within 20 min at 160 °C, with an activation energy of 72.0 kJ·mol ^‒1 . The chemical and morphological properties of Ru‐MgCu ₂ remained largely unchanged before and after the reactions, realizing high cycle stability of the Mg‐based hydrogen storage composite. These discoveries suggest the late transition metal‐based catalysts as the promising playground for efficient catalyst design with high stability.