Spatially Programmed Confinement Catalysis Enables High-Performance Magnesium Hydrogen Storage

Magnesium-based hydrides are among the most promising solid-state hydrogen storage materials owing to their high theoretical capacity and natural abundance. However, their practical deployment is severely constrained by sluggish kinetics, high thermodynamic barriers, and poor cycling stability. Recent advances reveal that conventional catalytic doping alone is insufficient to simultaneously modulate hydrogen activation, diffusion, and phase transformation within the reactive matrix. Here, we highlight spatially programmed confinement catalysis as an emerging paradigm to engineer the local reaction environment of MgH₂ at multiple length scales. By systematically dissecting one-dimensional (1D) axial confinements, two-dimensional (2D) interlayer nanospaces, and three-dimensional (3D) architected porous frameworks, this review demonstrates how dimensional confinement dictates interfacial chemistry, optimizes hydrogen transport pathways, and stabilizes phase evolution during cycling. Compared to traditional catalytic strategies, spatial confinement offers synergistic regulation of surface catalysis and bulk diffusion, enabling reversible hydrogen storage at significantly reduced temperatures with improved durability. We further discuss the inherent trade-offs between kinetic acceleration and gravimetric capacity, as well as the prospects of integrating confinement architectures with adaptive frameworks and intelligent catalytic interfaces. This dimensional confinement strategy marks a critical transition from passive catalyst doping toward the rational design of high-performance, architected nanoreactors for next-generation hydrogen energy systems.