Vacancy Mediated Hydrogen Desorption in NaAlH4
2005 (English)In: Physical Review B, ISSN 1098-0121, Vol. 72, no 16, 165101- p.Article in journal (Refereed) Published
First principles calculations based on density functional theory are carried out to understand the mechanisms responsible for hydrogen desorption from Ti doped sodium-alanate (NaAlH4). While the energy needed to remove a hydrogen atom from NaAlH4 with Ti substituted either at the Na site or at Al site is found to be significantly lower than that from the pristine NaAlH4, the presence of Na-vacancies is shown to play an even larger role: It is not only an order of magnitude smaller than that from Ti doped sodium alanate, but the removal of hydrogen associated with a Na-vacancy is exothermic with respect to formation of H2 molecule. Furthermore, we show that the unusual stabilization of the magic AlH3 cluster in the vacancy containing sodium-alanate is responsible for this diminished value of hydrogen removal energy. It is suggested that this role of vacancy can be exploited in the design and synthesis of complex light metal hydrides suitable for hydrogen storage.
Place, publisher, year, edition, pages
2005. Vol. 72, no 16, 165101- p.
hydrogen sorage, sodium alanate, electronic structure
IdentifiersURN: urn:nbn:se:uu:diva-77809DOI: doi:10.1103/PhysRevB.72.165101OAI: oai:DiVA.org:uu-77809DiVA: diva2:105721