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

In the present work, the synergetic effect of Ti-based catalysts (TiH2 and TiO2 particles) on hydrogen desorption kinetics of nanostructured magnesium hydride was investigated. Nanostructured 84 mol% MgH2–10%mol TiH2–6%mol TiO2 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 MgH2. A decrease in the decomposition temperature (as high as 100 °C) was attained after co-milling of MgH2 with the Ti-based catalysts. Meanwhile, solid-state chemical reactions between MgH2 and TiO2 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 MgH2 by 20–30 kJ/mol.