Research progress on Ti-based materials for MgH 2 hydrogen storage systems

Magnesium hydride (MgH2) as a solid-state hydrogen storage material has obtained intense attention in extensive research because of its high hydrogen-storage capacity, excellent reversibility, and relatively low cost. However, two primary obstacles of slow kinetics during hydrogenation/dehydrogenation process and high thermodynamic stability of Mg-H bond hinders the large-scale application of MgH2. Therefore, developing high-efficiency catalysts is necessary for hydrogen storage systems. Titanium (Ti) as an active element, shows promising in enhancing hydrogen storage activity and has been reported extensively. Herein, this review summarized the synthesis approaches, testing technology, and hydrogen storage performance of various Ti-based additives in detail. The structure-activity relationship of Ti-based materials was researched by combining experiment and DFT simulations. In particular, the focus is on the investigation of synthesis, characterization and reaction mechanism of various Ti-based additives. The real active sites and different reaction mechanisms during MgH2 hydrogen storage system are discussed. Finally, a summary and outlook were also presented. This review has the potential to guide the design of high-efficient catalysts and provide embedded guidance for future development and application of Mg-based materials in hydrogen storage system.