Enhanced Hydrogen Storage Properties of Mg–Ti–V Nanocomposite at Moderate Temperatures

With the purpose of improving the hydrogen sorption kinetics of Mg at moderate temperatures, the Mg–TiH 1.971 –VH 2 nanocomposite is synthesized by means of the hydrogen plasma–metal reaction (HPMR) approach. The nanocomposite is consequently hydrogenated and dehydrogenated at 673 K to synthesize Mg–9.6 wt % Ti–2.9 wt % V nanocomposite. The Mg Nanoparticles (NPs) in hexagonal shape range from 30 to 300 nm. The spherical Ti and V NPs of about 23 nm are uniformly distributed on the surfaces of the Mg NPs. The Mg–Ti–V nanocomposite quickly absorbs 4.7 wt % H 2 within 5 min at 473 K and 2.5 wt % H 2 within 10 min at 373 K. The apparent activation energies for hydrogenation and dehydrogenation are 29.2 and 73.8 kJ mol –1, respectively. During the hydrogenation/dehydrogenation cycle, the Ti and V NPs restrain the growth of Mg NPs. The dehydrogenation of TiH 1.971 to Ti is interpreted as the catalytic impact of V NPs. The improved sorption kinetics at moderate temperatures and the reduced activation energy derive from the nanostructure of Mg and the synergic catalytic impact of Ti and V NPs.