| Article ID | Journal | Published Year | Pages | File Type |
|---|---|---|---|---|
| 1282433 | International Journal of Hydrogen Energy | 2011 | 5 Pages |
We reported on the hydrogen desorption properties, microstructure, kinetics, and chemical bonding state of catalyst surface for composites of MgH2 and 1 mol% Nb2O5 ball-milled for 0.02 h, 0.2 h, 2 h, 20 h under 1 MPa H2 atmosphere, as well as hand-mixed (HM) one. Hydrogen desorption properties were significantly improved by ball-milling with Nb2O5. Then, we estimated by Kissinger Method the activation energy (Ea) of hydrogen desorption reaction that decreased with the increase of ball-milling time. Especially, Ea of the sample ball-milled for 0.2 h was drastically decreased, compared with that of the sample ball-milled for 0.02 h. TEM observations revealed that the distribution of Nb2O5 in MgH2 was gradually improved during ball-milling. On the other hand, we confirmed by XPS that in the sample ball-milled for 0.2 h, Nb2O5-x phase(s) existed at least on the surface. It can be suggested that these deoxidized Nb2O5-x phases eventually decrease Ea as substantial catalyst rather than Nb2O5 itself.
► MgH2 and 1 mol% Nb2O5 ball-milled composites were studied. ► The kinetics of desorption was improved with the increase of milling time. ► The particle size was gradually reduced during milling. ► Nb2O5-x phase(s) were found on the surface of the samples milled for 0.2 h ► Refined particle size and reduced Nb may lead to an improvement of kinetics.
