A highly active additive for magnesium hydride from the MgO–TiO2 mixed oxide family: Magnesium dititanate

Abstract

This study explores that a promising additive, magnesium dititanate (MgTi2O5), promotes the hydrogen storage behavior of MgH2 by producing active in-situ catalytic species. Due to the creation of active species the dehydrogenation activation energy of MgH2 lowers by 95 kJ/mol. Differential scanning calorimetry (DSC) and hydrogen absorption/desorption kinetics studies provide evidence that MgTi2O5 performs better than the proven additive TiO2 for MgH2. The MgH2/MgTi2O5 composite samples tested by X-ray diffraction (XRD) and high-resolution transmission electron microscopy (HRTEM) studies prove that oxidized Mg and Mg0·56Ti0.44 are the products of interaction between MgH2 and MgTi2O5. Formation of Mg-containing rock salt nanoparticles (MgO and/or MgxTiyOx+y) is identified to be the crucial step in the catalytic dehydrogenation reaction of MgH2/MgTi2O5 hydrogen storage system, which agrees well with the previous observation made for titania additive incorporated MgH2.