Novel core-shell structured MgH/AlH@CNT nanocomposites with extremely high dehydriding-rehydriding properties derived from nanoconfinement

In this work, a simple and efficient nanoconfinement method is developed to construct a novel "core-shell" structured MgH 2 /AlH 3 @CNT nanocomposite (MgH 2 /AlH 3 @CNTs). CNTs with a high specific surface area (550 m 2 g −1 ) and a small diameter (approximately 6-8 nm) contribute to finer crystal size (60-80 nm) of the core-shell structured MgH 2 /AlH 3 @CNT nanoparticles. Owing to the special "core-shell" structure, this nanocomposite shows significantly better H 2 de- and absorption thermodynamics and kinetics. The composite releases H 2 at ∼71 °C, which is substantially below the temperatures observed for the MgH 2 , nano-AlH 3 , and other MgH 2 /AlH 3 composites. It also shows dramatically improved dehydriding and rehydriding kinetics, rapidly releasing 8.20 wt% H 2 in 1 h at 200 °C and taking up 5.61 wt% H 2 in 0.16 h at 250 °C. During dehydrogenation and rehydrogenation, the CNTs can effectively prevent the aggregation of the nanocomposite particles and enhance the MgH 2 and AlH 3 direct contact. Thus, the application of these noteworthy core-shell MgH 2 /AlH 3 @CNTs offers a very promising way to improve the kinetics of the nanoconfinement system. A simple and efficient nanoconfinement method is developed to construct a novel "core-shell" structured MgH 2 /AlH 3 @CNT nanocomposite.