Catalytic action of two-dimensional layered materials (WS2, and MoS2) on hydrogen sorption properties of MgH2

The present study reports the catalytic action of two-dimensional (2D) layered materials (MoS2 and WS2) for improving the de/re-hydrogenation kinetics of MgH2. The MgH2 start desorbing at 277 C with a hydrogen storage capacity of 5.95 wt% in the presence of WS2 catalyst whereas onset desorption temperature of MgH2 catalyzed by MoS2 is 330 C. The MgH2-WS2 absorbed hydrogen ~ 3.72 wt% within 1.3 minutes at 300 C under 13 atm hydrogen pressure and it desorbed ~5.57 wt% within 20 minutes at 300 C under 1 atm hydrogen pressure. We have performed 25 cycles of dehydrogenation (under 1 atm hydrogen pressure at 300 C) and re-hydrogenation (under 13 atm hydrogen pressure at 300 {\deg}C) to ensure cyclic stability of catalyzed version of MgH2 where MgH2-WS2 shows better cyclic stability than MgH2-MoS2. MgH2-WS2 also shows the lower reaction activation energy ~117 kJ/mol as compare to other catalyzed and uncatalyzed samples. On the other hand, these catalysts (WS2 and MoS2) do not have any impact on the thermodynamical parameters that is change in enthalpy.