The influence of NbF
5 as an additive on the H-sorption kinetics of MgH
2 was investigated. We found that the hydrogen sorption capacity and sorption kinetics of the composites were dependent on the addition amount of NbF
5 as well as the milling time. Fast kinetics are obtained using 2 mol % NbF
5. At 573 K, the MgH
2 + 2 mol % NbF
5 milled for 5 h can absorb 5 wt. % hydrogen in 12 s and 6 wt. % in 60 min, and desorb 4.4 wt. % in 10 min and 5 wt. % in 60 min. DSC examination indicates that the desorption temperature is reduced by 64 K, and the activation energy for hydrogen desorption is estimated to be
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90 kJ/mol H
2 from the Kissinger Plot, indicating that MgH
2 is significantly activated due to the catalytic effect of NbF
5. Furthermore, X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) were performed to characterize the structural evolution upon milling and dehydrogenation.
