Remarkable enhancement in dehydrogenation properties of Mg(BH4)2 modified by the synergetic effect of fluorographite and LiBH4

Mg(BH 4 ) 2 is considered as one of the most promising light metal complex hydrides because of its high volumetric and gravimetric hydrogen capacities and world-wide abundance. However, its higher major desorption temperatures (above 300 °C) and poor reaction kinetics have to be improved for the practical application. Herein, Mg(BH 4 ) 2 was successfully synthesized via wet-chemical technique and a significant enhancement in dehydrogenation performance of Mg(BH 4 ) 2 is achieved by the synergetic effect of fluorographite (FGi) and LiBH 4 . Under the effect of FGi, the hydrogen desorption of 6 Mg(BH 4 ) 2 -4FGi composite could be completed below 170 °C in seconds. However, the hydrogen released from 6 Mg(BH 4 ) 2 -4FGi suffers from impurities of B 2 H 6 and HF. More importantly, it is demonstrated that almost all the B 2 H 6 and HF impurities can be suppressed by synergetic modifying Mg(BH 4 ) 2 with FGi and LiBH 4 . The 3 Mg(BH 4 ) 2 –3LiBH 4 -4FGi composite exhibits a capacity over 8.0 wt% H 2 and starts to release hydrogen at 125.7 °C, which is 143.8 °C and 254.3 °C lower than that of pure Mg(BH 4 ) 2 and LiBH 4 , respectively. These significant improvements could be attributed to both the novel morphology that numerous nano-scale borohydride spots formed on the surface of FGi, and the formations of stable fluorides (MgF 2 and LiF) from the interaction between borohydrides and FGi.