材料期刊网

We report on a study of influence of dopants (Ti and Ni) on the dehydrogenation properties of NaAlH(4) using the ab initio density functional method. Calculations show that the influence of dopants on the electronic structure is much localized; only the electronic structures of atoms in the vicinity of the dopants were changed. The mechanisms by which Ti improves the dehydrogenation properties of NaAlH(4) are sensitive to the occupation of Ti in NaAlH(4). If Ti substitutes for an Al atom, it tray form Ti-Al intermetallics, and if it occupies an interstitial site, it may "capture" H atoms to form TiH(2), phase. In both cases, the [AlH(4)] groups were dramatically distorted, which is the main reason why Ti dopant improves the dehydrogenation properties of NaAlH(4). The influence of Ni on the dehydrogenation properties of NaAlH(4) is relatively in weak comparison to the Ti dopant, mainly because the Ni only affects the electronic distribution in its vicinity, and so no significant changes of the [AlH(4)] groups were observed in Ni doped systems.