High capacity hydrogen storage in a hybrid ammonia borane–lithium amide material

Abstract

The direct (solventless) reaction of lithium amide with ammonia borane is described and is demonstrated to form a new hybrid material approximating to LiNH₂BH₃NH₃. This material rapidly loses 3.2 mole equivalents of hydrogen, (11.9 wt%) on heating to 250 °C, with the most rapid hydrogen release occurring at temperatures as low as 60 °C. The product was an insoluble, amorphous polymer with the general formula –(NLi–BNH₂)_n– which did not rehydrogenate directly on exposure to hydrogen gas pressure. The hybrid material and its decomposition products were characterised by solid state ¹¹B NMR. Selective deuterium labelling helped to elucidate a reaction sequence for the hydrogen release using mass spectrometry of the released gases.