Effect of titanium based complex catalyst and carbon nanotubes on hydrogen storage performance of magnesium

Mg (MgH₂)-based composites, using carbon nanotubes (CNTs) and pre-synthesized titanium based complex (TCat) as the catalysts, were prepared by high energy ball milling technique. The use of both catalysts demonstrated markedly improved the hydrogen storage performance, e.g. a significant increase of hydrogen release rate and decrease of desorption temperature. The synthesized composites can absorb almost 6 wt% of hydrogen within 3 min at 200 °C and desorb 6 wt% hydrogen in 10 min at 310 °C. The influence of CNTs and TCat on desorption temperature was also investigated by using temperature programmed desorption (TPD). The TPD results reveal that the peak desorption temperature and the onset temperature can be lowered by 109 °C and 155 °C, respectively, compared to the non-catalyzed MgH₂. The reaction enthalpy and entropy of hydrogen desorption for the synthesized MgH₂-based composites are calculated by the van’t Hoff analysis to be 73.1 kJ/mol H₂ and 130.2 J/mol H₂ K, respectively.