Insights into an Amorphous NiCoB Nanoparticle-Catalyzed MgH₂ System for Hydrogen Storage

Abstract

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.