An approach for advancing the hydrogen storage properties via H-induced precipitation of even nanocatalytsts in rapid solidified Mg–Ni–Y alloy fibers

Optimization for hydrogen storage properties of Mg-based alloy is mainly restricted by coarse α-Mg grains and uneven catalytic phases. In this study, a strategy of melt-spinning rapid solidification is proposed to fabricate one-dimensional Mg₉₇Ni₂Y₁ alloy fiber with submicron-sized α-Mg grains and uniform microstructure. After heat treatment and activation process, ultrafine Mg₂Ni and YH₂ phases are in-situ generated and uniformly distributed. The results indicate that 5.24 wt% H₂ is absorbed at 305 °C in 30 min, higher than the as-cast alloy powder of 4.49 wt% H₂. Meanwhile, the dehydrogenation rate is accelerated at lower temperatures. Based on the DSC curve, the hydrogen pumping effect in the fiber alloy powder is more significant, reducing the dehydrogenation temperature of MgH₂. The fiber alloy powder absorbs more hydrogen in stage 1, leading to enhanced hydrogenation kinetics. The uniform and refined microstructure formed by the rapid-solidified fiber is the key factor for enhanced de-/hydrogenation properties.