Effects of Ti-based catalysts on hydrogen desorption kinetics of nanostructured magnesium hydride

In the present work, the synergetic effect of Ti-based catalysts (TiH sub(2) and TiO sub(2) particles) on hydrogen desorption kinetics of nanostructured magnesium hydride was investigated. Nanostructured 84 mol% MgH sub(2)-10%mol TiH sub(2)-6%mol TiO sub(2) nanocomposite powder was prepared by high-energy ball milling and subjected to thermal analyses. Evaluation of the absorption/desorption properties revealed that the addition of the Ti-based catalysts significantly improved the hydrogen storage performance of MgH sub(2). A decrease in the decomposition temperature (as high as 100 degree C) was attained after co-milling of MgH sub(2) with the Ti-based catalysts. Meanwhile, solid-state chemical reactions between MgH sub(2) and TiO sub(2) nanoparticles during co-milling slightly decreased the maximum hydrogen capacity. It was also found that formation of micro-cracks at the particle surfaces during thermal cycling enhanced the H-kinetics. Isothermal and non-isothermal thermal analysis revealed that the addition of Ti-catalysts reduced the decomposition activation energy of MgH sub(2) by 20-30 kJ/mol.