KH+Ti co-doped NaAlH4 for high-capacity hydrogen storage
Abstract
A method for preparation of Ti-doped NaAlH4 with high hydrogen capacity was developed, in which the NaH/Al mixture was mechanically milled with a catalytic amount of KH together with metallic Ti. The addition of KH was found to result in a pronounced improvement in the dehydriding performance of the Na3AlH6/NaH+Al step. As a result, the practical cycling hydrogen capacity has been markedly enhanced from 3.3 wt % for the Ti-doped hydride to 4.7 wt % for KH+Ti co-doped material. Moreover, the pronounced enhancement on hydrogen capacity arising upon adding KH was observed to persist in the following dehydrogenation/hydrogenation cycles. Structural investigation shows that the addition of KH has led to a lattice expansion. Moreover, it was found that the enthalpy change of the Na3AlH6/NaH+Al decomposition step underwent a considerable decrease upon adding KH. Therefore, the observed property improvement may be ascribed to a favorable thermodynamic adjustment arising upon the addition of KH.
- Publication:
-
Journal of Applied Physics
- Pub Date:
- October 2005
- DOI:
- 10.1063/1.2084308
- Bibcode:
- 2005JAP....98g4905W
- Keywords:
-
- 05.70.-a;
- 82.65.+r;
- 68.43.Mn;
- Thermodynamics;
- Surface and interface chemistry;
- heterogeneous catalysis at surfaces;
- Adsorption/desorption kinetics