Hydrogen Release from Ammonia Borane Nanoconfined in Metal–Organic Frameworks with MIL-53 Topology

With a gravimetric hydrogen density of 19.6 wt % and the capability of storing up to 146 kgH₂ m–³, ammonia borane (NH₃·BH₃) possesses excellent hydrogen storage properties. Nanoconfinement in six different porous metal–organic frameworks with MIL-53 topology is shown to reduce the hydrogen release temperature and modify its decomposition pathway. In particular, the modification of terephthalic acid as linker by OH and NH₂ groups resulted in reduced hydrogen release temperatures and reduced formation of gaseous byproducts. In situ XRD diffraction and ¹¹B MAS NMR studies helped to confirm the stability of the porous host and identify ammonia borane decomposition products.