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Wednesday, October 15, 2008

Hydrogen Powered Vehicles steps forward with new meterial

Its not a dream that you are driving your car by water, Reseach is going forward and bringing us the posibility possible,
Researchers in Greece report design of a new material that almost meets the U.S. Department of Energy (DOE) 2010 goals for hydrogen storage and could help eliminate a key roadblock to practical hydrogen-powered vehicles.

Their study on a way of safely storing hydrogen, an explosive gas, is scheduled for the Oct. 8 issue of ACS' Nano Letters, a monthly journal.

Georgios K. Dimitrakakis, Emmanuel Tylianakis, and George E. Froudakis note that researchers long have sought ways of using carbon nanotubes (CNTs) to store hydrogen in fuel cell vehicles. CNTs are minute cylinders of carbon about 50,000 times thinner than the width of a human hair. Scientists hope to use CNTs as miniature storage tanks for hydrogen in the coming generation of fuel cell vehicles.

In the new study, the researchers used computer modeling to design a unique hydrogen-storage structure consisting of parallel graphene sheets — layers of carbon just one atom thick —stabilized by vertical columns of CNTs. They also added lithium ions to the material's design to enhance its storage capacity.

The scientists' calculations showed that their so-called "pillared graphene" could theoretically store up to 41 grams of hydrogen per liter, almost matching the DOE's target (45 grams of hydrogen per liter) for transportation applications.

"Experimentalists are challenged to fabricate this material and validate its storage capacity," the researchers note

Silicon Nanotubes For Hydrogen Storage In Fuel Cell Vehicles
After powering the micro-electronics revolution, silicon could carve out an important new role in speeding the debut of ultra-clean fuel cell vehicles powered by hydrogen, researchers in China suggest. Their calculations show for the first time that silicon nanotubes can store hydrogen more efficiently than their carbon nanotube counterparts.

Dapeng Cao and colleagues note that researchers have focused on the potential use of carbon nanotubes for storing hydrogen in fuel cell vehicles for years. Despite nanotubes' great promise, they have been unable to meet the hydrogen storage goals proposed by the U.S. Department of Energy for hydrogen fuel cell vehicles. A more efficient material for hydrogen storage is needed, scientists say.

In the study, Cao's group used powerful molecular modeling tools to compare the hydrogen storage capacities of newly developed silicon nanotubes to carbon nanotubes. They found that, in theory, silicon nanotubes can absorb hydrogen molecules more efficiently than carbon nanotubes under normal fuel cell operating conditions. The calculations pave the way for tests to determine whether silicon nanotubes can meet government standards for hydrogen storage, the scientists note.

The article "Silicon Nanotube as a Promising Candidate for Hydrogen Storage: From the First Principle Calculations to Grand Canonical Monte Carlo Simulations" will appear in the April 24 issue of ACS' Journal of Physical Chemistry C.

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