Insights into an Amorphous NiCoB Nanoparticle-Catalyzed MgH2 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 MgH₂. The MgH₂-NiCoB composite quickly absorbed 3.6 wt % H₂ at a low temperature of 85 °C and released 5.5 wt % H₂ 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 MgB₂, Mg₂Ni/Mg₂NiH₄, and Mg₂Co/Mg₂CoH₅ 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 MgH₂, showing new ways for designing Mg-based hydrogen storage systems toward practical application.