Fullerenes for Hydrogen Storage

18 October 2007

Nanowerk. A new theoretical study provides the most accurate method to date for the structural optimization of hydrogen-C60 composites to encapsulate hydrogen inside hollow molecules, under room temperature.

Fullerenes are ideal nanocages for hydrogen storage, not only because they are hollow but also because hydrogen can be adsorbed on the fullerene surface.

“We wanted to look at the properties of fullerene nanocages containing hydrogen and, as we studied the literature, found that the results in the few theoretical papers that considered endohedral C60 fullerene containing hydrogen molecules were contradictory,” Dr. Boris I. Yakobson tells Nanowerk.

Since the previous studies did not agree with each other, Yakobson, a Professor in Materials Science and Computational Materials Science in the Department of Mechanical Engineering & Materials Science at Rice University in Houston, Texas, and his group decided to use a more accurate method—density functional theory—to determine the geometry of these composite structures, and to systematically study their properties for both high and low hydrogen content. They also performed ab initio molecular dynamics simulations in order to investigate the stability of the optimized structures.

The results of their study have been published in the 9 October online edition of Nano Letters.

Dr. Amir A. Farajian, a co-author of the paper, says that endohedral fullerenes (i.e. fullerenes encapsulating additional atoms) containing more than one hydrogen molecule have not been obtained experimentally yet. “It is very difficult to synthesize them, because they are highly endothermic” he says. ”However, our calculations show that these structures can exist, and once they are created, they will not break easily. They have a high content of hydrogen, which can be released in a controllable way. So, if anybody manages to obtain them, they will be a great hydrogen storage media.”

Resources:

• Pupysheva, O.V., Farajian, A.A., and Yakobson, B.I. “Fullerene Nanocage Capacity for Hydrogen Storage” Nano Lett., 2007, 10.1021/nl071436g