Graphene‐Supported Ni/Sc ₂ O ₃ Nanoheterostructures: Oxygen Vacancy‐Enhanced Catalysis for High‐Performance Mg‐Based Hydrogen Storage

Abstract Efficient hydrogen storage remains a critical challenge for large‐scale energy applications. Here, a novel catalyst design—ultrafine Ni/Sc 2 O 3 nanoheterostructures anchored on few‐layer graphene (Ni/Sc 2 O 3 @FLG)—that dramatically enhances the hydrogen sorption performance of MgH 2 is reported. The integrated heterostructure combines strong Ni‐Sc 2 O 3 interactions, abundant oxygen vacancies, and a high‐surface‐area FLG scaffold to achieve exceptional catalytic activity. When incorporated into MgH 2 , the composite exhibits an onset dehydrogenation temperature as low as 170 °C and a peak temperature of 233.7 °C, representing a reduction of 139 °C compared to pristine MgH 2 . At 300 °C, 6.04 wt.% H 2 is released within 5 min, while rapid hydrogen uptake occurs even at 100 °C (5.19 wt.% in 30 s). The material maintains 95% capacity over 50 cycles with negligible kinetic degradation. Mechanistic studies and density functional theory calculations reveal that the superior performance originates from synergistic effects: oxygen vacancy‐induced electron channeling, in situ formation of active phases (Mg 2 Ni/Mg 2 NiH 4 and metallic Sc), and a hydrogen pump effect. This work provides a scalable strategy for designing multifunctional nanocatalysts and offers new insights into accelerating hydrogen sorption kinetics in Mg‐based systems.