Facilitating hydrogen desorption of MgH₂ by introducing highly reactive vanadium sulfide

Practical applications of magnesium hydride are hampered by high thermodynamic stability and slow kinetics. The design of highly active catalysts is essential to improve the kinetics of MgH₂. Although studies concerned with the interaction between MgH₂ and catalyst have remained quite active, detailed investigation of the beneficial effect from the phase transformation is lacking. Herein, a high-activity VS₂ was designed and introduced to catalyze MgH₂, and the MgH₂-VS₂ system exhibited superior hydrogen desorption capabilities at comparatively low temperatures (3.5 wt% H₂, 1800 s, 225 °C). This enhancement in the hydrogen storage performance of MgH₂ was attributed to the in-situ phase transformation of the catalytic species during hydrogen cycling. DFT calculations demonstrated the catalytic effect of VS₂ and in-situ formation of new species relative to MgH₂. Our results provide a deeper insight into enhancing dehydrogenation mechanism on metal hydrides of the high-activity catalyst.