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

Abstract

With the purpose of improving the hydrogen sorption kinetics of Mg at moderate temperatures, the Mg–TiH1.971–VH2 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 % H2 within 5 min at 473 K and 2.5 wt % H2 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 TiH1.971 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 ...