Abstract:A synergistic approach involving experiment and first-principles theory not only shows that carbon nanostructures can be used as catalysts for hydrogen uptake and release in complex metal hydrides such as sodium alanate, NaAlH 4 , but also provides an unambiguous understanding of how the catalysts work. The stability of NaAlH 4 originates from the charge transfer from Na to the AlH 4 moiety, resulting in an ionic bond between Na + and AlH 4 -and a covalent bond between Al and H. Interaction of NaAlH 4 with an electro-negative substrate such as carbon fullerene or nanotube affects the ability of Na to donate its charge to AlH 4 , consequently weakening the Al-H bond and causing hydrogen to desorb at lower temperatures as well as facilitating the absorption of H 2 to reverse the dehydrogenation reaction. Ab initio molecular dynamics simulation further reveals the time evolution of the charge transfer process with hydrogen desorption occurring when the charge transfer is complete. Introduction:

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