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 degrees 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.