Hydrogen hopes in carbon shells

To succeed as alternatives to conventional cars and trucks, hydrogen-powered vehicles will need a safe, lightweight, compact, and cheap way to store their fuel. Now, theorists studying spherical, 60-carbon shells called buckyballs (SN: 5/20/06, p. 308: Available to subscribers at Feeling cagey) suggest that lithium atoms added to buckyball surfaces bestow on those molecules a remarkable capacity to store hydrogen.

The Department of Energy has proposed that by 2015, hydrogen-powered vehicles should hold hydrogen weighing no less than 9 percent of a storage system’s total weight. Lithium-bedecked buckyballs could theoretically store up to 13 percent of their mass in hydrogen, says physicist Puru Jena of Virginia Commonwealth University in Richmond.

Supercomputer simulations of buckyballs with 12 lithium atoms distributed evenly on their surfaces indicate that each lithium atom would hold 10 atoms of hydrogen, Jena and his colleagues report in the Aug. 2 Journal of the American Chemical Society.

Some lithium atoms would hold fewer hydrogen atoms because bonds among buckyballs would probably block some hydrogen-binding sites, Jena notes.

Also, cryogenic temperatures might prove necessary to make the hydrogen stay put. If so, scientists may need to chemically modify the lithium-studded buckyballs to fix that problem, Jena adds.

Several groups at other universities are launching efforts to synthesize the proposed lithium-buckyball molecules.