Enhanced hydrogen storage properties of MgH₂ co-catalyzed with zirconium oxide and single-walled carbon nanotubes

The hydrogen storage performance of ball-milled MgH₂ with 5 wt% ZrO₂ + 5 wt% single-walled carbon nanotubes as additives was investigated. We found that the hydrogen sorption kinetics of magnesium is markedly improved by these co-additives. At a temperature of 423 K, the sample absorbs around 6.73 wt% H₂ in the first 100 s. However, at a temperature of 298 K, the sample absorbs 1.06 wt% H₂ in 100 s. Notably, the sample still absorbs 4.00 wt% H₂ within 700 s under ambient temperature conditions (298 K). The theoretical analysis of MgH_2, ZrO₂ and SWCNT alloy powers at different temperatures also have been studied. By theoretical analysis of the experimental data of the pyrolytic hydriding reaction and fitting them with the Johnson-Mehl-Avrami (JMA) equation, the kinetic equation and the corresponding kinetic parameters including the reaction order, the reaction rate constant, and the reaction activation energy have been obtained. Furthermore, the reason why the MgH₂ and ZrO₂ alloy powders can absorption at room temperature has been interpreted referring to the thermodynamic and kinetic factors.