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

Abstract

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.