Remarkable synergistic effects of Mg2NiH4 and transition metal carbides (TiC, ZrC, WC) on enhancing the hydrogen storage properties of MgH2

Nanostructuring and catalyzing are effective methods for improving the hydrogen storage properties of MgH 2 . In this work, transition-metal-carbides (TiC, ZrC and WC) are introduced into Mg–Ni alloy to enhance its hydrogen storage performance. 5 wt% transition-metal-carbide containing Mg 95 Ni 5 (atomic ratio) nanocomposites are prepared by mechanical milling pretreatment followed by hydriding combustion synthesis and mechanical milling process, and the synergetic enhancement effects of Mg 2 NiH 4 and transition-metal-carbides are investigated systematically. Due to the inductive effect of Mg 2 NiH 4 and charge transfer effect between Mg/MgH 2 and transition-metal-carbides, Mg 95 Ni 5 -5 wt.% transition-metal-carbide samples all exhibit excellent hydrogen storage kinetic at moderate temperature and start to release hydrogen around 216 °C. Among them, 2.5 wt% H 2 (220 °C) and 4.7 wt% H 2 (250 °C) can be released from the Mg 95 Ni 5 -5 wt.% TiC sample within 1800 s. The unique mosaic structure endows the Mg 95 Ni 5 -5 wt.% TiC with excellent structural stability, thus can reach 95% of saturated hydrogen capacity within 120 s even after 10 cycles of de-/hydrogenation at 275 °C. And the probable synergistic enhancement mechanism for hydrogenation and dehydrogenation is proposed.