Stabilization of Nanosized Borohydrides for Hydrogen Storage: Suppressing the Melting with TiCl3 Doping

Abstract

Lightweight complex hydrides, M(BH4)n (M = Li, Na, Mg, and Ca; n = 1 for Li and Na, n = 2 for Mg and Ca), are believed to be promising hydrogen storage materials with extreme high hydrogen density up to 18.5 mass %. However, these materials suffer high dehydrogenation temperature, melting, and reversibility problems, which exclude them from the list of practical hydrogen storage systems. Herein, borohydrides (M(BH4)n–Ti, with M = M1 or M2 and n = 1 or 2), were modified with TiCl3 via a wet chemistry approach, and in some cases this led to the formation of solvent-stabilized nanoparticles. As a result of TiCl3 modification, the melting before hydrogen release was suppressed as evidenced by DSC and thermal microscopy observations. Furthermore, the hydrogen release temperature of M(BH4)n–Ti was significantly reduced. For example, the dehydrogenation temperature of NaBH4–Ti was reduced from 570 to 120 °C. Ti modification was also found to improve to some extent the reversibility of the doped materials. In par...