Insights into an Amorphous NiCoB Nanoparticle-Catalyzed MgH 2 System for Hydrogen Storage.

In the paper, we synthesized amorphous NiCoB nanoparticles by a simple chemical reduction method and employed them as high-activity catalysts to considerably improve the hydrogen storage properties of MgH 2 . The MgH 2 -NiCoB composite quickly absorbed 3.6 wt % H 2 at a low temperature of 85 °C and released 5.5 wt % H 2 below 270 °C within 600 s. It is worth noting that the hydrogenation activation energy was reduced to 33.0 kJ·mol -1 . Detailed microstructure analysis reveals that MgB 2 , Mg 2 Ni/Mg 2 NiH 4 , and Mg 2 Co/Mg 2 CoH 5 were in situ generated during the first de/absorption cycle and dispersed at the surface of NiCoB. These active ingredients created lots of boundary interfaces to facilitate the hydrogen diffusion and destabilize the Mg-H bonds, thus decreasing the kinetic barriers. This work provides support for a promising catalytic effect of amorphous NiCoB on de/absorption reactions of MgH 2 , showing new ways for designing Mg-based hydrogen storage systems toward practical application.