In this age of global warming and pollution, it is imperative that we find cleaner sources of energy. Some alternatives, such as hydrogen-powered fuel cells are quite appealing, since the exhaust from such cells is pure water. However, Hydrogen, being a gas, occupies a large volume, and this is hampering any real development in this area. Now researchers from National Institute of Science and Technology (Taner Yildirim) and Turkey's Bilkent University (Salim Ciraci) have developed a new model for a metal-laced Carbon Nano-tube, which can latch on to hydrogen molecules in numbers more than adequate for efficient hydrogen storage, a capability key to long-term efforts to develop fuel cells.

Model: Titanium-Blue, Hydrogen-Red (Courtesy: NIST)Carbon nanotubes are tubes composed entirely of carbon atoms, and often composed of a chain of carbon rings (picture here). Calculations by the researchers show that if decorated with Titanium or other transition metals, such tubes can attract Hydrogen atoms, which get attached to the Titanium atoms. The total weight of Hydrogen can be upto 8% of the weight of the tubes, which exceeds the standard of 6% specified by the FreedomCar Research Partnership involving the US Department of Energy and USA's "Big 3" automakers. Moreover, if heated, the Titanium atoms readily give up four attached Hydrogen atoms! Such reversible desorption is another requirement for practical Hydrogen storage.
The new results, obtained with a method for calculating the electronic structure of materials, surprised the researchers. Interactions among Carbon, Titanium and Hydrogen seem to give rise to unusual attractive forces. The upshot is that four Hydrogen molecules can dock on a Titanium atom, apparently by means of a unique chemical bond of modest strength. Several forces at work within the geometric arrangement appear to play a role in the reversible tethering of Hydrogen.
The results are the first glimmer of hope in sustainable storage of Hydrogen in mass quantities. If developed, this technology should allow vehicles to have a nanotube-based fuel tank, capable of storing large quantities of Hydrogen in a small enough volume to be of practical use :).