Hydrogen sorption properties of a MgH2 - V2O5 composite prepared

A 90 wt.% MgH2 – 10 wt.% V2O5 composite was obtained by ball milling of a mixture of magnesium hydride and vanadia for 60 min under argon. Hydrogen sorption properties of the composite were determined volumetrically with a Sieverts-type device. Absorption was studied at temperatures of 473 and 573 K and pressure of 1 MPa, while desorption was investigated at T = 573 and 623 K and P = 0.15 MPa. Structure, phase and surface composition of the starting compounds and the composite before and after hydriding were determined by XRD, thermal analysis, TEM and XPS. After hydriding the composite at 573 K, a high absorption capacity value of 6.3 wt.% H2 was attained. However, fast hydrogen desorption was observed only at temperatures higher than those needed for practical use. Some ideas about further studies to be performed in view to improving the performance of vanadia-containing magnesium composites for hydrogen storage were discussed.