Simulation of hydrogen storage in novel carbon and/or light metal-based nanostructured and nanocomposite materials
In this project we explore computationally the hydrogen storage potential of novel nanomaterials based on carbon and/or magnesium. Efficient storage technology is a crucial issue in the move to an efficient and clean energy supply through a hydrogen economy. The successful development of such technology will have enormous commercial implications.
The project has developed strongly in the past year and now plays a crucial role not only for purely computational investigations but also in supporting and augmenting the impact of experimentally based publications. Our project is characterised by very close interaction between the experimental and computational members of the team, and stands out internationally because of this close and fruitful collaboration between theory and experiment.
A major focus of the Mg-based work in the past year has been to uncover the catalytic mechanism of additives that have been found experimentally to have a favourable impact on the storage properties of the nanocomposite materials. This work plays a very significant role within the field, as it allows one to characterise individual molecular steps in a complex kinetic process that are often not accessible via current experimental techniques. In this way the computational program provides understanding that can guide further experimental work, powerfully augmenting the active experimental program within the Centre.
Major achievements and research highlights
2007 has seen continued strong development in the hydrogen storage modelling program. We have demonstrated a spill-over mechanism for splitting of molecular hydrogen at a catalytic site and subsequent migration of atomic hydrogen across the surface away from the catalytic site. This was found for Pd in a Mg surface, and is the first time that this mechanism - previously invoked qualitatively to interpret experimental data - has been verified with a first-principle modelling approach. In parallel experimental work, the results of a new improved combination of catalysts (V, Ti and single-walled carbon nanotubes) in Mg, which yield excellent hydrogen absorption properties, have likewise been published in the high profile Journal of the American Chemical Society. We have elaborated the catalytic mechanism of action of Ti in the rehydrogenation of solid Al – an important part of the loading cycle for sodium alanate. We have extended our study of the possible role of alkali metal vacancies in facilitating dehydrogenation of complex metal hydrides (published in Applied Physics Letters for NaAlH4) to consider a similar role for Li vacancies in LiBH4.
Future plans and directions
The symbiosis between theory and experiment in the hydrogen storage effort within the Centre has led to new insights and new materials with markedly improved efficiency for hydrogen storage. This has already led to one patent in preparation, and, in the coming year we anticipate several high profile publications, alongside the systematic elaboration of catalysis and mechanistic aspects in these materials.
