Rice University
Rice Magazine| The Magazine of Rice University | No. 1 | 2008

Tiny Buckyballs Squeeze Hydrogen Like Giant Jupiter

Materials scientists at Rice University have made the surprising discovery that buckyballs are so strong they can hold volumes of hydrogen nearly as dense as those at the center of Jupiter.


Today, the hunt is on in earnest for viable alternative fuels to power automobiles. One of the most promising is hydrogen, which is so clean-burning and abundant that the U.S. Department of Energy has devoted more than $1 billion to developing technologies for hydrogen-powered automobiles. But there is a snag. Because hydrogen is the lightest element in the universe, it is very difficult to store in bulk. It is estimated that a hydrogen-powered car with the range of a gasoline-powered car would require a storage system that could hold the element at densities greater than those found in pure liquid hydrogen.

That’s a pretty strong container, but Rice materials scientists may have found it, and it’s a lot smaller than expected. Buckyball small.

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“Based on our calculations, it appears that some buckyballs are capable of holding volumes of hydrogen so dense as to be almost metallic,” said lead researcher Boris Yakobson, professor of mechanical engineering and materials science at Rice.

“It appears they can hold about 8 percent of their weight in hydrogen at room temperature, which is considerably better than the federal target of 6 percent.”

In layman’s terms, that’s nearly as dense as the pressures at the center of Jupiter.

Yakobson said scientists have long argued the merits of storing hydrogen in tiny molecular containers like buckyballs, and experiments have shown that it’s possible to store small volumes of hydrogen inside buckyballs. The new research by Yakobson and former postdoctoral researchers Olga Pupysheva and Amir Farajian offers the first method of precisely calculating how much hydrogen a buckyball can hold before breaking.

“Bonds between carbon atoms are among the strongest chemical bonds in nature,” Yakobson said. “These bonds are what make diamond the hardest known substance, and our research showed that it takes an enormous amount of internal pressure to deform and break the carbon-carbon bonds in a fullerene.”

If a feasible way to produce hydrogen-filled buckyballs is developed, Yakobson said, it might be possible to store them as a powder.

“They will likely assemble into weak molecular crystals or form a thin powder,” he said. “They might find use in their whole form or be punctured under certain conditions to release pure hydrogen for fuel cells or other types of engines.”

The research, which was supported by the Office of Naval Research and the U.S. Department of Energy, appeared on the cover of the American Chemical Society’s journal Nano Letters.

Paper, Plastic or Nano?