Development and Challenges of Mg-Based Hydrides for Hydrogen Storage Near-Room Temperature.

Mg-based hydrides are highly promising solid-state hydrogen storage materials due to their high theoretical capacity, natural abundance, and low cost. However, their widespread implementation is constrained by inherent thermodynamic stability, sluggish kinetics, and progressive capacity fade during cycling. This review provides a comprehensive assessment of three primary modification strategies: alloying, catalytic modification, and nanoengineering. Alloying strategies, encompassing both intermetallic and disproportionation-type alloys, regulate thermodynamic stability by weakening Mg─H interactions through electronic structure modulation and lattice distortion while improving kinetics by inducing grain refinement and establishing high-density phase boundaries. Catalytic modification employs transition metals, metal oxides, and MXenes to establish multivalent active centers that accelerate reaction kinetics by facilitating hydrogen interfacial transport, lowering activation barriers via the dissociation and migration of atomic hydrogen, and destabilizing Mg─H bonds through interfacial electron transfer, while providing continuous diffusion channels and inducing heterogeneous nucleation. Nanoengineering strategies are able to thermodynamically destabilize the hydride phase through surface energy effects, shorten hydrogen diffusion paths, and increase accessible active sites for efficient hydrogen storage. By correlating these mechanisms, this work outlines prospective research directions, such as the development of integrated multi-mechanism systems, stable catalytic materials, and external field-assisted techniques to achieve hydrogen storage at near-room temperature.