Catalytic effect of bamboo-like carbon nanotubes loaded with NiFe nanoparticles on hydrogen storage properties of MgH2

•A surfactant-model catalyst of nano NiFe loaded on bamboo-like CNT is designed.•A multiphase and multiscale MgH2/Mg2NiH4-Fe/C catalytic system is constructed.•The MgH2-NiFe@CNT composite can absorb 3.25 wt% hydrogen within 1 h at 348 K.•The initial dehydrogenation temperature of MgH2-NiFe@CNT composite is 498 K.•The dehydrogenation activation energy of MgH2 is reduced to 49.7 kJ mol−1. Catalyst doping modification has become an important strategy to solve the high desorption temperature and sluggish kinetics issues of magnesium hydride (MgH2) for further commercial application. Herein, we report a novel strategy by exploiting a catalyst with the “magnesophilic” transition metal and “magnesiphobic” carbon material to construct a MgH2-catalysts-carbon layer hydrogen storage material, where the bimetallic NiFe nanoparticles are supported atop the bamboo-like carbon nanotubes (NiFe@CNT) via calcination. The experimental results show that the built MgH2-NiFe@CNT composite can absorb 4.06 and 3.25 wt% H2 at 373 and 348 K, respectively, while the milled-MgH2 almost no longer absorbs H2 and takes only 0.82 wt% even at 423 K. More importantly, the initial desorption temperature of the MgH2-NiFe@CNT composite reduces to 498 K by 122 K in contrast to the milled-MgH2, and the dehydrogenation activation energy decreases from 151.8 to 49.7 kJ mol−1. Ex situ structural characterization and theoretical calculation show that the synergistic effects of the “hydrogen pump” role of Mg2Ni/Mg2NiH4 and “hydrogen gateway” role of α-Fe, as well as the good dispersion function of carbon nanotubes generated in situ from the NiFe@CNT, contribute the excellent hydrogen storage properties of the MgH2-NiFe@CNT composite. This study provides new insights into the modification of MgH2 by carbon-supported transition metal catalysts.