Spatial Relay Catalysis in a Hybrid Ni Single-Atoms/Mg₂Ni Nanoparticle System for High-Performance Hydrogen Storage of MgH₂

Catalysis is crucial for lowering the operating temperature of MgH₂ 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 MgH₂. Herein, we reveal that Ni single-atom catalysts (Ni₁) excel specifically in hydrogen dissociation/recombination on the Mg/MgH₂ surface, whereas Mg₂Ni 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 Ni₁@Mg₂Ni-MgH₂ composite exhibits remarkably enhanced low-temperature performance, absorbing 5 wt.% H₂ 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.