Enhanced hydrogen storage properties of magnesium by the synergic catalytic effect of TiH1.971 and TiH1.5 nanoparticles at room temperature

Abstract

In order to improve the hydrogen sorption kinetics of Mg at room temperature, the Mg–9.2wt%TiH1.971–3.7wt%TiH1.5 nanocomposite is successfully prepared by hydrogen plasma-metal reaction (HPMR) method and hydrogenation/dehydrogenation at 673 K. The Mg nanoparticles are hexagonal in shape with the size in the range of 50–190 nm. The spherical Ti hydrides nanoparticles of about 13 nm are uniformly dispersed on the surface of Mg nanoparticles. During hydrogenation/dehydrogenation cycle, the Ti hydrides nanoparticles restrain the growth of Mg nanoparticles. The Mg–TiH1.971–TiH1.5 nanocomposite quickly absorbs 4.3 wt% H2 in 10 min at room temperature and reaches a saturation value of 5.0 wt% in 60 min. The apparent activation energies for hydrogen absorption and desorption are 12.5 and 46.2 kJ mol−1, respectively. The improved kinetics and reduced activation energy are explained in terms of the nanostructure of Mg and the synergic catalytic effect of TiH1.971–TiH1.5 nanoparticles.