Catalytic effect of a novel MgC0.5Co3 compound on the dehydrogenation of MgH2

Abstract

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, MgC0.5Co3 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 MgH2, the initial hydrogen desorption temperature of MgH2–MgC0.5Co3 composite lowered to 237 ​°C, decreasing by 141 ​°C. At 325 ​°C the MgH2–MgC0.5Co3 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–MgC0.5Co3 composite was dramatically reduced to 126.7 ​± ​1.4 ​kJ/mol. It was observed that MgC0.5Co3 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.