MXene-supported VH_x nanoparticles enhancing hydrogen storage properties of magnesium hydride

Magnesium hydride (MgH₂) is a highly attractive candidate for solid-state hydrogen storage because of its high mass density, excellent cyclic stability, and low cost. However, the commercialization of MgH₂ has been hindered by its sluggish hydrogen sorption kinetics and elevated operating temperatures. In this study, vanadium hydride nanoparticles (VH_x) adhered to Ti₃C₂ composite catalyst was synthesized by ball milling to improve the hydrogen storage properties of MgH₂. The onset dehydrogenation temperature of the MgH₂ + 10wt% VH_x@Ti₃C₂ composite decreased from 267.6 to 190.3°C. In addition, the MgH₂ + 10wt% VH_x@Ti₃C₂ composite could release 6.72wt% hydrogen within 10 min at 290°C. By comparison, pure MgH₂ started to release hydrogen at 267.6°C, whereas only 0.29wt% hydrogen was released under the same conditions. After 20 cycles, more than 95% of the initial hydrogen absorption and desorption capacities were retained, indicating that the MgH₂ + 10wt% VH_x@Ti₃C₂ composite exhibited good cycling performance. Investigation of the catalytic mechanism demonstrated that the layered structure of Ti₃C₂ served as a matrix supplying a large number of active sites, and VH_x functioned as a “hydrogen pump” to accelerate the migration of H ions, thereby facilitating the hydrogen absorption and desorption processes of MgH₂ and enhancing its hydrogen storage properties. This study provides a viable strategy for designing vanadium-based catalysts to improve solid-state hydrogen storage materials.