Received: August 4, 2007

In Final Form: September 9, 2007

Abstract:

Searching for hydrogen storage materials suitable for applications has been the focus of extensive research in industry and academia. With the great success in obtaining stable hollow silicon-based nanostructures, one is naturally led to wonder whether silicon-based nanostructures are possible for chemical hydrogen storage. Here a hydrogenated silicon fullerene (HSF), Si₆₀H₆₀, is considered as a prototype of stable silicon-based nanostructures for hydrogen storage. By performing density functional theory calculations we show that the HSF is stable over hydrogen molecule attack and thus qualified for acting as a potential hydrogen storage medium. The interaction between the HSF with hydrogen molecules is found to be essentially via van der Waals force, making the HSF prefer storing hydrogen in molecular form. It is demonstrated that up to 58 hydrogen molecules can be stored into its interior cavity, and together with 60 hydrogen atoms in the exterior surface, total gravimetric density of hydrogen of 58H₂@Si₆₀H₆₀ amounts to 9.48%, which is much higher than any reported capacity of hydrogen storage in other media or the target of the Department of Energy (6 wt %). The present results provide valuable guidance for developing practical high-capacity hydrogen storage materials.

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