Tunable Metal-Hydrogen Bonding in Cu-Ru ICatalysts 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/MgH₂). While incorporating polyhydrides (e.g., LiBH₄ and LiNH₂) and catalysts enables Mg/MgH₂ 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. MgCu₂ 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-MgCu₂), the d-band center is optimized, enhancing catalytic activity by 5.5 times compared to plain MgCu₂, without compromising its chemical stability. The Ru-MgCu₂ 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-MgCu₂ 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.