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

•6 Mg(BH4)2-4FGi composite decompose below 170 °C.•Numerous nanoscale spots formed in 3 Mg(BH4)2–3LiBH4-4FGi composite.•Synergetic modification of FGi and LiBH4 could suppress the B2H6 released from Mg(BH4)2.•Synergetic effect of FGi and LiBH4 can significantly improve the dehydrogenation kinetics of Mg(BH4)2.

Mg(BH4)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(BH4)2 was successfully synthesized via wet-chemical technique and a significant enhancement in dehydrogenation performance of Mg(BH4)2 is achieved by the synergetic effect of fluorographite (FGi) and LiBH4. Under the effect of FGi, the hydrogen desorption of 6 Mg(BH4)2-4FGi composite could be completed below 170 °C in seconds. However, the hydrogen released from 6 Mg(BH4)2-4FGi suffers from impurities of B2H6 and HF. More importantly, it is demonstrated that almost all the B2H6 and HF impurities can be suppressed by synergetic modifying Mg(BH4)2 with FGi and LiBH4. The 3 Mg(BH4)2–3LiBH4-4FGi composite exhibits a capacity over 8.0 wt% H2 and starts to release hydrogen at 125.7 °C, which is 143.8 °C and 254.3 °C lower than that of pure Mg(BH4)2 and LiBH4, 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 (MgF2 and LiF) from the interaction between borohydrides and FGi.

Graphical abstractFigure optionsDownload full-size imageDownload as PowerPoint slide