Abstract: The introduction of the heterogeneous catalysts with high activity can significantly improve hydrogen storage performance of MgH₂, therefore, in this paper, we synthesize a carbon-supported transition metal compound, FeCoS@C derivative from ZIF-67, by utilizing the in situ formed C dispersive multiphase Mg₂Co, α-Fe, Co₃Fe₇, and MgS to implement catalysis to MgH₂. Noteworthily, MgH₂-FeCoS@C rapidly absorbs 6.78 wt% H₂ within 60 s at 573 K and can also absorb 4.56 wt% H₂ in 900 s at 473 K. Besides, the addition of FeCoS@C results in decreasing of the initial dehydrogenation temperatures of MgH₂ from 620 to 550 K. The dehydrogenation activation energy of MgH₂ decreases from 160.7 to 91.9 kJ mol^-1. Studies show that the Mg₂Co, α-Fe, and Co₃Fe₇ act as “hydrogen channels” to accelerate hydrogen transfer due to the presence of transition metals, and MgS with excellent catalytic effect formed from MgH₂-FeCoS@C provides a strong and stable catalytic effect. Besides, the carbon skeleton obtained by the carbonization of ZIF-67 not only serves as a dispersion for the multiphase catalytic system, but also provides more active sites for the catalysts. Our study shows that the multiphase and multiscale catalytic system provides an effective strategy for improving the hydrogen storage performance of MgH₂.

Key words: Hydrogen storage material, Magnesium hydride, Heterogeneous catalyst, Synergistic catalytic, MOF materials