Synthesis of core-shell α-AlH3@Al(OH)3 nanocomposite with improved low-temperature dehydriding properties by mechanochemical mixing and ionic liquid treatment

Nano alpha-AlH3 is a promising H-2 storage material, with high gravimetric capacity and dehydriding temperature. However, its instability at ambient conditions and relatively slow dehydriding kinetics hinder its applications. This work reports a simple and environmentally friendly synthesis of a novel core-shell alpha-AlH3@Al(OH)(3) nanocomposite with 1.2 nm thick shell. First, alpha-AlH3/LiCl nanocomposite was synthesized using a mechanochemical method, during which, alpha-AlH3 was stabilized using imidazolium ionic liquid (IL). After IL application and consequent rinsing with water, alpha-AlH3@Al(OH)(3) composite formed. Its dehydriding kinetics was significantly faster (with the activation energy equal to 52.6 kJ/mol) relative to the pure alpha-AlH3. At 140 degrees C, the alpha-AlH3@Al(OH)(3) released 10.0 wt% of its original hydrogen content within 1000 s. For comparison, the same amount of hydrogen was released by the commercial alpha-AlH3 only after 3600 s. The presence of the Al(OH)(3) shell stabilized the alpha-AlH3 and resulted in absolutely no decomposition of the AlH3 in the alpha-AlH3@Al(OH)(3) composite under ambient conditions for 7 days. Synthesis of this novel core-shell alpha-AlH3@Al(OH)(3) nanocomposite is a new and very promising strategy to improve the stability and the hydrogen storage kinetics simultaneously. (C) 2020 Elsevier Ltd. All rights reserved.

Automated summary

A novel core-shell alpha-AlH3@Al(OH)3 nanocomposite with a 1.2 nm thick shell was synthesized using an environmentally friendly method. The presence of the Al(OH)3 shell significantly improved the dehydriding kinetics of alpha-AlH3 and stabilized it under ambient conditions. This new strategy shows great promise in enhancing both stability and hydrogen storage kinetics.