A strategy of fabricating efficient Mg2Ni nano-catalysts in Mg-Ni-Ag fibers and their excellent hydrogen storage properties at near-room temperatures.

In this study, a new strategy was utilized to fabricate Mg-based hydrogen storage fibers with uniform elemental distribution and diameters of 30–50 μm. The in-situ formation of nano-precipitates in Mg 85 Ni 14.8 Ag 0.2 metallic glass fibers was visually observed at varied annealing temperatures. It indicates the metastable Mg 6 Ni phase is formed from an amorphous microstructure initially. Then, the needle-like Mg 2 Ni nanoparticles precipitate at 140–160 °C and subsequently grow into spherical shapes. This results in the formation of the fiber structure with well-distributed nano-Mg 2 Ni particles. The alloy fibers can absorb H 2 at only 40 °C, and the activation energy for hydrogenation is lowed to be 46.9 kJ/mol. The onset desorption temperature of hydride is reduced to 220 °C due to the improved the catalytic efficiency by uniformly distributed Mg 2 Ni nanoparticles. The abundant interfaces, as well as the shortened distance by micropores, serve as paths for the fast diffusion of H atoms. A strategy for fabricating efficient Mg 2 Ni nano-catalysts in a novel Mg-Ni-Ag fiber and its enhanced hydrogen storage properties. [Display omitted] [ABSTRACT FROM AUTHOR]