Synthesis and Hydrogen Desorption Properties of Nanoscale α-AlH₃

Abstract: 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.