MOF-derived Ni3Fe/Ni/NiFe2O4@C for enhanced hydrogen storage performance of MgH2

Magnesium hydride (MgH 2 ) is an important material for hydrogen (H 2 ) storage and transportation owing to its high capacity and reversibility. However, its intrinsic properties have considerably limited its industrial application. In this study, the NiFe-800 catalyst as metal-organic framework (MOF) derivative was first utilized to promote the intrinsic properties of MgH 2 . Compared to pure MgH 2 , which releases 1.24 wt% H 2 in 60 min at 275 °C, the MgH 2 -10 NiFe-800 composite releases 5.85 wt% H 2 in the same time. Even at a lower temperature of 250 °C, the MgH 2 -10 NiFe-800 composite releases 3.57 wt% H 2 , surpassing the performance of pure MgH 2 at 275 °C. Correspondingly, while pure MgH 2 absorbs 2.08 wt% H 2 in 60 min at 125 °C, the MgH 2 -10 NiFe-800 composite absorbs 5.35 wt% H 2 in just 1 min. Remarkably, the MgH 2 -10 NiFe-800 composite absorbs 2.27 wt% H 2 in 60 min at 50 °C and 4.64 wt% H 2 at 75 °C. This indicates that MgH 2 -10 NiFe-800 exhibits optimum performance with excellent kinetics at low temperatures. Furthermore, the capacity of the MgH 2 -10 NiFe-800 composite remains largely stable after 10 cycles. Moreover, the Mg 2 Ni/Mg 2 NiH 4 acts as a “hydrogen pump”, providing effective diffusion channels that enhance the kinetic process of the composite during cycling. Additionally, Fe 0 facilitates electron transfer and creates hydrogen diffusion channels and catalytic sites. Finally, carbon (C) effectively prevents particle agglomeration and maintains the cyclic stability of the composites. Consequently, the synergistic effects of Mg 2 Ni/Mg 2 NiH 4 , Fe 0 , and C considerably improve the kinetic properties and cycling stability of MgH 2 . This work offers an effective and valuable approach to improving the hydrogen storage efficiency in the commercial application of MgH 2 .