Hydrogen storage behaviors of magnesium hydride catalyzed by transition metal carbides

In this study, some transitional metal carbides (Ti3C2, Ni3C, Mo2C, Cr3C2 and NbC) were prepared to enhance the hydrogen storage behaviors of magnesium-based materials. The carbides with a weight ratio of 5 wt% were introduced into magnesium hydride (MgH2) by mechanical ball milling, and the microstructure, phase composition and hydrogen storage properties of the composites were studied in detail. The phase compositions of Ni3C, Mo2C, Cr3C2 and NbC in the ball-milled composites have not changed during hydrogen absorption and desorption cycles. However, Ti3C2 decompose into multivalent Ti during hydrogenation process. All of these metal carbides can enhance the hydrogen absorption and desorption kinetics of MgH2. Among them, Ti3C2 shows the best catalytic effect on dehydrogenation kinetic properties of MgH2, followed by the Ni3C, NbC, Mo2C and Cr3C2.