Hydrogen storage properties of eutectic metal borohydrides melt-infiltrated into porous Al scaffolds

摘要

Porous Al scaffolds were synthesised and melt-infiltrated with various eutectic metal borohydride mixtures (0.725LiBH(4)-0.275KBH(4), 0.68NaBH(4)-0.32KBH(4), 0.4NaBH(4)-0.6 Mg(BH4)(2)) to simultaneously act as both a confining framework and a reactive destabilising agent for H-2 release. The scaffolds were synthesised by sintering a pellet of NaAlH4/2 mol%TiCl3 at 450 degrees C under dynamic vacuum. During the sintering process the sodium alanate (NaAlH4) decomposed to Al metal. The vacuum applied at elevated temperature promoted the Na metal to vaporise and be extruded from the pellet. The pores of the resulting Al scaffold were created during removal of the H-2 and the Na from the body of the NaAlH4/2 mol%TiCl3 pellet. According to the morphological observations carried out by a Scanning Electron Microscope (SEM), melt-infiltrated eutectic mixtures of metal borohydrides were highly dispersed into the porous scaffolds. Temperature Programmed Desorption (TPD) experiments, revealed that the melt-infiltrated samples exhibited faster H-2 desorption kinetics in comparison to bulk samples, with onset temperatures (T-des) lower than the bulk by 150-250 degrees C. The as-synthesised porous Al scaffolds acted as a reactive containment vessel for these eutectic mixtures that simultaneously nanoconfined and destabilised the mixtures. (C) 2018 Published by Elsevier B.V.