Catalytic effect of SrTiO₃ on the dehydrogenation properties of LiAlH₄

Lithium alanate (LiAlH₄) is regarded as one of the potential materials for on-board hydrogen storage applications because of its high hydrogen capacity. However, this advantage is restricted by several obstacles such as high decomposition temperature and slow desorption kinetics that deny its marketability. Hence, efforts such as decreasing the particle size by the mechanical milling technique and by adding dopants/catalysts have been investigated widely to overcome these drawbacks. In this work, the influences of strontium titanate (SrTiO₃) on the dehydrogenation properties of LiAlH₄ have been investigated for the first time. The onset decomposition temperature of the 10 wt% SrTiO₃-doped LiAlH₄ sample decreased from 145 °C to 80 °C in the first dehydrogenation step and from 178 °C to 120 °C in the second dehydrogenation step. For the desorption kinetic measurements at 90 °C, the 10 wt% SrTiO₃-doped LiAlH₄ sample could desorb about 3.0 wt% of H₂ in 20 min compared to 0.2 wt% by the as-milled LiAlH₄. The activation energies calculated by Kissinger analysis in the two-step dehydrogenation process of LiAlH₄ were lowered after the addition of SrTiO₃. From the X-ray diffraction analysis, we found that SrTiO₃ did not react during the mechanical milling and heating (desorption) processes. SrTiO₃ is believed to play a catalytic role by reducing the physical size of LiAlH₄ during the mechanical milling process thereby improving the dehydrogenation storage properties of LiAlH₄.