Catalytic effect of a novel MgC_(0.5)Co_3 compound on the dehydrogenation of MgH_2

The application of magnesium hydride (MgH₂) is limited due to the high reaction temperature and slow kinetics during dehydrogenation. In order to ameliorate the dehydrogenation property of MgH₂, MgC_0.5Co₃ compound with induction and catalytic effects was introduced into the Mg/MgH₂ system via ball-milling and hydriding combustion methods in present study. Compared to the pure MgH_2, the initial hydrogen desorption temperature of MgH₂–MgC_0.5Co₃ composite lowered to 237 ?°C, decreasing by 141 ?°C. At 325 ?°C the MgH₂–MgC_0.5Co₃ composite could release 4.38 ?wt% H₂ within 60 ?min, which is 4.5 times the capacity of hydrogen released by as milled-MgH₂. Besides, the hydrogen desorption activation energy of the MgH₂–MgC_0.5Co₃ composite was dramatically reduced to 126.7 ?± ?1.4 ?kJ/mol. It was observed that MgC_0.5Co₃ was chemically stable and no chemical transformation occurred after cycling, which not only inhibited the nucleation and growth of composite particles, but also had a positive effect on the hydrogen desorption reaction of MgH₂ due to its catalytic effect. This study may provide references for designing and synthesizing Mg–C–Co alloy compound for the Mg-based hydrogen storage area.