Working in a close collaboration with the experimental group headed by Ragaiy Zidan at Savannah River National Laboratory, US, Ralph Scheicher and co-workers in Sweden had previously explored theoretically how carbon nanostructures can act as catalysts for hydrogen release in the complex metal hydride sodium alanate (NaAlH4). The stability of the AlH4 moiety is due to the charge transfer from Na, resulting in an ionic bond between Na+ and AlH4 and a strengthening of the covalent bond between Al and H. The interaction of NaAlH4 with any electronegative substrate, such as a carbon nanotube or fullerene, affects the amount of charge donated from Na to AlH4 and thus weakens the Al-H bonds, causing hydrogen to desorb at lower temperatures.

Focus on fullerenes

Further experiments by Zidan's group concentrated on the catalysing effects of fullerenes (C60) on hydrogen uptake and release in lithium borohydride (LiBH4). In an effort to better understand the involved mechanism, Scheicher and co-workers have carried out a detailed computational study of the interaction between LiBH4 and C60. Considering a stepwise removal of the hydrogen from LiBH4, they found that the presence of C60 can lead to a substantial reduction in the involved hydrogen removal energies. This effect is explained as a consequence of the interaction between the negatively charged borohydride complex and the C60 entity.

Full details can be found in the journal Nanotechnology.