The present work concerns the catalytic effect of VNbO5, a ternary oxide prepared via a solid-state
route, on the sorption performance of MgH2. Three doped systems, namely 5, 10 and 15 wt% VNbO5–
MgH2 have been prepared by ball milling and thoroughly characterized. Hydrogen sorption, evaluated by
temperature programmed desorption experiments, revealed a significant reduction of the desorption
temperature from 330 1C for the un-doped sample (prepared and tested for comparison) to 235 1C for
the VNbO5-doped sample. Furthermore, more than 5 wt% of hydrogen can be absorbed in 5 minutes at
160 1C under 20 bar of hydrogen, which is remarkable compared to the 0.7 wt% achieved for the
un-doped system. The sample doped with 15 wt% of additive, showed good reversibility: over 5 wt% of
hydrogen with negligible degradation even after 70 consecutive cycles at 275 1C and 50 cycles at
300 1C. The kinetics analysis carried out by Kissinger’s method exhibited a considerable reduction of the
activation energy for the desorption process. Finally, pressure-composition-isotherm experiments
conducted at three different temperatures allowed estimating the thermodynamic stability of the system
and shed light on the additive role of VNbO5.
