Comparative catalytic effects of NiCl2, TiC and TiN on hydrogen storage properties of LiAlH4

Abstract

Catalytic effects of NiCl2, TiC and TiN on the dehydrogenation/rehydrogenation characteristics of LiAlH4 were investigated by pressure-content-temperature (PCT), X-ray diffraction (XRD), differential scanning calorimatory (DSC), and field emission scanning electron microscopy (FESEM). The doped samples exhibit dehydrogenation at much lower temperatures. Doping with NiCl2, TiC and TiN induce a decrease in the decomposition of first step by about 50–65 °C compared to that of as received LiAlH4. Also, amount of hydrogen release is significantly higher for TiC additions than that of samples doped with TiN and NiCl2. Isothermal desorption results at 125 °C reveal that dehydrating rate of doped alanate is much faster than that of pure LiAlH4. TiC, TiN and NiCl2 dopants show the reabsorption of about 1.9 wt.%, 1.3 wt.%, and 1.1 wt.%, respectively. XRD and FESEM analyses suggest that both TiC and TiN are stable during the ball milling as well as the dehydrogenation processes. On the contrary, NiCl2 reacts and causes the partial decomposition of Li alanate during the ball milling process.