Abstract
A novel eutectic hydrogen storage system, LiBH4 center dot NH3-nNH(3)BH(3), which exists in a liquid state at room temperature, was synthesized through a simple mixing of LiBH4 center dot NH3 and NH3BH3 (AB). In the temperature range of 90-110 degrees C, the eutectic system showed significantly improved dehydrogenation properties compared to the neat ABand LiBH4 center dot NH3 alone. For example, in the case of the LiBH4 center dot NH3/AB with a mole ratio of 1 : 3, over 8 wt.% hydrogen could be released at 90 degrees C within 4 h, while only 5 wt. % hydrogen released from the neatABat the same conditions. Through a series of experiments it has been demonstrated that the hydrogen release of the new system is resulted from an interaction of AB and the NH3 group in the LiBH4 center dot NH3, in which LiBH4 works as a carrier of ammonia and plays a crucial role in promoting the interaction between the NH3 group and AB. The enhanced dehydrogenation of LiBH4 center dot NH3/AB may result from the polar liquid state reaction environments and the initially promoted formation of the diammoniate of diborane, which will facilitate the B-H/H-N interaction between LiBH4 center dot NH3 and AB. Kinetics analysis revealed that the rate-controlling steps of the dehydrogenation process are three-dimensional diffusion of hydrogen at temperatures ranging from 90 to 110 degrees C.