Carbon nanohorns offer hydrogen storage hope
Carbon nanohorns could be used to store hydrogen, according to new research from an international team of scientists.
Hydrogen has long been held up as clean alternative to fossil fuels. However, its wider application is being held back because of difficulties finding a safe and economically viable way to store it.
One option which is being explored is the possibility of storing hydrogen in porous materials. With their low mass and high capacity for adsorption, carbon nanostructures offer high potential in this respect. However, experiments with carbon nanotubes have thrown up some problems. For a start, hydrogen storage in carbon nanotubes is only possible at extremely low temperatures (below -196°C). Furthermore, when the sample is heated to room temperature, most of the hydrogen evaporates.
Writing in the journal Physical Review Letters, the researchers, from the UK, Spain, France and the US, explain how carbon nanohorns could be used to store hydrogen more effectively than nanotubes.
Carbon nanohorns are, as their name suggests, horn-shaped structures made from a single layer of carbon atoms. The nanohorns are around 2-3 nanometres long, and they aggregate together to form flower-like structures of 80-100nm. By using high resolution neutron spectroscopy, the scientists were able to study the strength of the interactions between hydrogen molecules and the carbon nanohorns.
They found that interaction between hydrogen and carbon nanohorns is much stronger than the interaction between hydrogen and carbon nanotubes.
'The results show that hydrogen interacts far more strongly with such carbonous nanostructures than it does to carbon nanotubes, suggesting that nanohorns and related nanostructures may offer significantly better prospects as light-weight media for hydrogen storage applications,' the researchers conclude.
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Data Source Provider: Centre National de la Recherche Scientifique (CNRS), Physical Review Letters
Document Reference: Fernandez-Alonso, F et al. (2007) Nature of the bound states of molecular hydrogen in carbon nanohorns. Physical Review Letters 98 (21), 215503.
Subject Index: Coordination, Cooperation; Materials Technology; Renewable Sources of Energy; Scientific Research