Innovative applications of single-atom catalysts in MgH₂/Mg system to build high-efficiency hydrogen storage

MgH₂ shows significant potential for a solid-state hydrogen storage medium due to the advantages of high hydrogen capacity, excellent reversibility, and low cost. However, its large-scale application still requires overcoming significant thermodynamic and kinetic hurdles. Catalyst design and optimization enhancements are crucial for the hydrogen storage properties of MgH₂, wherein single-atom catalysts, characterized by their small size and high proportion of unsaturated coordination sites, have recently demonstrated a significant advance and considerable promise in this regard. This review presents recent progress on state-of-the-art single-atom catalysts for enhancing MgH₂ hydrogen storage, examining both supported and unsupported catalyst types, i.e., transition metal @ N-modified carbon materials and transition metal @ transition metal compounds, and metallene-derived compounds and single-atom alloys, respectively. We systematically discussed the single-atom catalysts in MgH₂ hydrogen storage systems, focusing on synthesis strategies, characterization techniques, catalytic mechanisms, as well as existing challenges and future perspectives. We aimed to provide a comprehensive and cohesive understanding for researchers in the field, and promote the development of single-atom catalysts and their significant optimization of the hydrogen storage performance of MgH₂.