Advantage of TiF3 over TiCl3 as a dopant precursor to improve the thermodynamic property of Na3AlH6

The effect of the dopant anion on thermodynamic tailoring in TiF3- and TiCl3-doped Na3AlH6 was investigated by pressure-composition desorption isotherm measurements. It was found that the dissociation pressure of the TiF3-doped hydride was substantially higher than that of the TiCl3-doped sample. This finding agrees well with the theoretically demonstrated thermodynamic modification arising upon F− substitution in the hydride lattice, thus providing direct experimental evidence to support functionality of F− anion.