Catalysis derived from flower-like Ni MOF towards the hydrogen storage performance of magnesium hydride

Abstract

Herein, a novel flower-like Ni MOF with good thermostability is introduced into MgH 2 for the first time, and which demonstrates excellent catalytic activity on improving hydrogen storage performance of MgH 2 . The peak dehydrogenation temperature of MgH 2 -5 wt.% Ni MOF is 78 °C lower than that of pure MgH 2 . Besides, MgH 2 -5 wt.% Ni MOF shows faster de/hydrogenation kinetics, releasing 6.4 wt% hydrogen at 300 °C within 600 s and restoring about 5.7 wt% hydrogen at 150 °C after dehydrogenation. The apparent activation energy for de/hydrogenation reactions are calculated to be 107.8 and 42.8 kJ/mol H 2 respectively, which are much lower than that of MgH 2 doped with other MOFs. In addition, the catalytic mechanism of flower-like Ni MOF is investigated in depth, through XRD, XPS and TEM methods. The high catalytic activity of flower-like Ni MOF can be attributed to the combining effect of in-situ generated Mg 2 Ni/Mg 2 NiH 4 , MgO nanoparticles, amorphous C and remaining layered Ni MOF. This research extends the knowledge of elaborating efficient catalysts via MOFs in hydrogen storage materials. • A novel flower-like Ni MOF with good thermostability is fabricated. • Flower-like Ni MOF can effectively improve the hydrogen storage property of MgH 2 . • MgH 2 -5 wt.% Ni MOF can release 6.4 wt.% H 2 at 300 °C within 600 s. • Partial MOF reacts with MgH 2 to form Mg 2 Ni/Mg 2 NiH 4 , MgO nanoparticles, amorphous C. • The combining effect of in-situ formed substances and residual Ni MOF is revealed.