Facile synthesis of bowl-like 3D Mg(BH4)2-NaBH4-fluorographene composite with unexpected superior dehydrogenation performances
A remarkable improvement in hydrogen desorption performance of Mg(BH4)2-NaBH4 eutectic composite is achieved by simply ball-milling with fluorographene (FG). It is found that the desorption temperature of Mg(BH4)2-NaBH4 (~200 °C) is still too high and liquid phase appears during dehydrogenation. Particularly, the novel bowl-like 3D Mg(BH4)2-NaBH4-FG composite can be formed after ball-milling. The novel Mg(BH4)2-NaBH4-FG exhibits a low dehydrogenation temperature of 114.9 °C with 6.9 wt.% of pure hydrogen in seconds. In-depth investigations show that such great improved hydrogen desorption properties of Mg(BH4)2-NaBH4-FG composite could be ascribed to both the “novel bowl-like 3D structure” with large specific surface area, and the “reactant destabilized modification” due to the decreases of reaction enthalpy caused by the formation of NaMgF3. This finding provides a facile preparation of complex borohydride composites with low dehydrogenation temperature and fast rate, which accelerates its practical application in fuel cell.