Hydrogen generation from noncatalytic hydrolysis of LiBH4/NH3BH3 mixture for fuel cell applications

Ammonia borane (NH3BH3) and lithium borohydride (LiBH4) are promising hydrides as they contain 19.6 wt.% and 18.5 wt.% hydrogen respectively. However, hydrolysis of NH3BH3 needs catalysts or high temperature to initiate the release of hydrogen. On the other hand, hydrolysis of LiBH4 is incomplete, because the agglomeration of LiBH4 and its products limits its full utilization. In the present work, hydrolysis performance of LiBH4/NH3BH3 mixture was investigated. The results show that LiBH4/NH3BH3 mixture can fully release its theoretical amount of hydrogen at room temperature without catalysts. In the presence of LiBH4, NH3BH3 can be fully hydrolyzed at room temperature. In return, in the presence of NH3BH3, the agglomeration can be avoided resulting in a complete hydrolysis process. Our results indicate that the improvements are attributed to the intermolecular electron migration between LiBH4 and NH3BH3, which changes the reactivity of these compounds. Hydrolytic heat of LiBH4 also contributes to the promoted hydrolysis of NH3BH3. Our results present a novel strategy for noncatalytic hydrolysis of NH3BH3 and LiBH4 for proton exchange membrane fuel cell applications.

► Full hydrolysis of LiBH4 is achieved in the presence of NH3BH3. ► Full hydrolysis of NH3BH3 is achieved in the presence of LiBH4. ► The hydrolytic heat of LiBH4 promotes the hydrolysis of NH3BH3. ► The mechanism is the changes of B related chemical bonds among LiBH4 and NH3BH3.