Synthesis and Hydrogen Desorption Properties of Nanoscale α-AlH3

Aluminum hydride is particularly attractive as a hydrogen storage material due to its high hydrogen volumetric capacity and relatively low hydrogen desorption temperature. However, the properties of nanoscale α‑AlH3 particles are not studied completely due to the difficulties in their synthesis. In this work, we report the synthesis of nanoscale α-AlH3 based on a modified method, together with its activation energy measurements and hydrogen release kinetics. We have discovered that the dehydrogenation activation energy (93.23 kJ/mol) of nanoscale α-AlH3 is remarkably lower than that of micrometer-sized α-AlH3, which further expand practical application of AlH3. Moreover, we demonstrate that the decomposition kinetics of nanoscale α-AlH3 is controlled by nucleation and growth of the aluminum phase in three dimensions. This work first time provides systematic investigation of thermodynamic properties of nano-scale AlH3, which paves the way for its practical applications.