A comparison study of catalytic effects of MoS2 and CeO2 on hydrogen storage performances of as-milled SmMg11Ni alloy

In this paper, SmMg11Ni + 5 wt% M (M = MoS2, CeO2) (named SmMg11Ni-5M (M = MoS2, CeO2)) alloys were prepared by ball milling. The structure and hydrogenation/dehydrogenation thermodynamics and kinetics of as-milled alloys have been observed and calculated carefully. The results show that both of the as-milled alloys have the nanocrystalline and amorphous structures. The CeO2 catalyzed alloy shows a larger hydrogen absorption capacity and faster hydriding rate as compared with the MoS2 catalyzed one. M = CeO2 alloy exhibits the lower onset hydrogen desorption temperature and superior hydrogen desorption property than the M = MoS2 one. The order of hydrogen desorption activation energies is E(CeO2) < E(MoS2), which is responsible for the M = CeO2 alloy possessing the much faster dehydriding rate. The thermodynamic parameters of SmMg11Ni-5M (M = MoS2, CeO2) alloys are calculated, deriving ΔHdes(MoS2) = 77.55 kJ/mol and ΔHdes(CeO2) = 74.86 kJ/mol, respectively, viz. ΔHdes(MoS2) > ΔHdes(CeO2).