A first principles analysis of hydrogen storage in metal complex hydrides

FUEL 99

Qingfeng Ge, Department of Chemistry and Biochemistry, Southern Illinois University, 1245 Lincoln Dr, Carbondale, IL 62901
Ti-doped NaAlH4 has been widely studied as a prototype to understand and explore light-metal complex hydrides as potential hydrogen storage materials for on-board vehicle applications. Over the past several years, tremendous efforts have been made toward improving hydrogen storage capacity and adsorption/desorption kinetics. In this talk, I will present results of our density-functional-theory calculations of the structure and interactions of hydrogen with metal atoms in a series of light metal complexes. Low-index surfaces were built from the corresponding relaxed bulk structures. The energy costs to create hydrogen vacancies on these low-index surfaces were determined and used as a measure of desorption energy of hydrogen from these surfaces. In addition, we explored the role of Ti in facilitating hydrogen desorption in Ti-doped NaAlH4. A complex structure, with Ti occupying interstitial site and interacting directly with three neighboring (AlH4)- groups in a slab simulating NaAlH4(001), will be discussed in the context of recent experimental results.