Enhanced kinetics for hydrogen exchange in LiBH 4 incorporated within nanoporous carbon scaffolds are described. Dehydrogenation rates up to 50 times faster than those in the bulk material are measured at 300 °C in a nanostructured hydride formed by filling a porous carbon aerogel host with LiBH 4 . Furthermore, the activation energy for hydrogen desorption, measured using the approach developed by Ozawa, is reduced from 146 kJ/mol for bulk LiBH 4 to 103 kJ/mol for nanostructured LiBH 4, and the faster kinetics result in desorption temperatures that are reduced by up to 75 °C. In addition, nanostructured hydrides exhibit increased cycling capacity over multiple sorption cycles. This work demonstrates that confinement within a porous scaffold host is a promising approach for enhancing hydrogen uptake and release in reversible light-metal complex hydrides.
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Gross et al. (2008) studied this question.