Spatial Relay Catalysis in a Hybrid Ni Single‐Atoms/Mg ₂ Ni Nanoparticle System for High‐Performance Hydrogen Storage of MgH ₂

Catalysis is crucial for lowering the operating temperature of MgH 2 hydrogen storage, enabling its practical use under milder conditions. However, single‐component catalysts typically lack the versatility to efficiently drive all reaction steps involved in the (de)hydrogenation of MgH 2 . Herein, we reveal that Ni single‐atom catalysts (Ni 1 ) excel specifically in hydrogen dissociation/recombination on the Mg/MgH 2 surface, whereas Mg 2 Ni nanoparticles are more effective in cleaving Mg─H bonds and facilitating hydrogen transport within the bulk. This complementary functionality motivates their integration into a hybrid system with spatial relay catalysis. The synthesized Ni 1 @Mg 2 Ni‐MgH 2 composite exhibits remarkably enhanced low‐temperature performance, absorbing 5 wt.% H 2 at 150°C within 60 min and releasing hydrogen from as low as 177°C, outperforming the individual components. This work demonstrates a successful spatial relay catalysis strategy between the emerging single‐atom catalysts and a conventional intermetallic compound, paving a new avenue for the design of hybrid catalytic systems for complex reactions.