MgH2 confinement in MOF-derived N-doped porous carbon nanofibers for enhanced hydrogen storage

Magnesium hydride (MgH 2 ) is one of the most promising hydrogen storage materials, while the high desorption temperature and sluggish kinetics hamper its further commercialization. Herein, a novel MOF-derived 1D N-doped hierarchically porous carbon nanofiber (pCNF) is firstly prepared and used as the scaffold for self-assembly of MgH 2 /Ni nanoparticles (NPs). The resultant MgH 2 /Ni@pCNF nanocomposites show faster desorption kinetics ( E a  = 96.58 kJ/mol H 2 ), lower onset desorption temperature ( T onset  = 200 °C) when compare to the commercial MgH 2 ( E a  = 142.27 kJ/mol H 2 , T onset  = 350 °C). Moreover, hydrogen absorption can be achieved at a temperature as low as 100 °C with a capacity of 2.2 wt% within 120 min. Additionally, the composites exhibit excellent cycling stability with a capacity retention over 95.4% after 10 complete re-/dehydriding cycles at 300 °C. In-situ HRTEM observations of the desorption process combined with XPS and XRD indicate that the synergistic effects from nanoconfinement of Mg/MgH 2 in pCNF, electron-donating ability of N atoms and the “hydrogen pump” function of Mg 2 Ni/Mg 2 NiH 4 account for the unprecedent hydrogen storage properties. The strategy of using the MOF-derived 1D pCNF as support for nanoparticles provides a new approach for fabricating nanostructured energy materials with enhanced performances.