Researchers at the Technische Universität Dresden have designed packing of carbon nanotubes with three and four different orientations of tube axes that are stable and can store hydrogen with uptake amounts up to 19.0 wt% at 77 K (-196 °C)) and 5.5 wt% at 300 K (27 °C)), approaching the US Department of Energy target of 6 wt% by 2015.
|One of the carbon nanotube structures. Credit: Assfour et al. Click to enlarge.|
Inspired by natural sponges, the team designed a computer model that placed carbon nanotubes in the hole positions of a theoretical sponge network. “Putting cylinders next to each other is a way of packing them. But there is another way—to put them so they cross over each other, like the holes in a sponge. Using modelling we found how many arrangements the nanotubes could be arranged in to fit this criteria,” Stefano Leoni told Chemistry World.
The carbon nanotubes are arranged in parallel, but with none of them intersecting. Each nanotube is in contact with others, but not all the way along the edge of the nanotube. The next step will be to make the structures experimentally.
Assfour, B., Leoni, S., Seifert, G. and Baburin, I. A. (2011) Packings of Carbon Nanotubes—New Materials for Hydrogen Storage. Advanced Materials doi: 10.1002/adma.201003669