Highly fine, dispersive, and active catalysts are essential for lowering the operating temperature of MgH2, a promising high-capacity material for solid-state hydrogen storage. In this work, ultrafine Ni nanoparticles (2–6 nm) are synthesized from the precursor nickel acetylacetonate (C10H14NiO4) on the surface of MgH2 by H2 plasma reduction process, followed by further ball milling. The obtained composite could rapidly release more than 6.5 wt % H within 10 min at 275 °C. Even at a low temperature of 225 °C, up to 6 wt % H could be desorbed. The MgH2–Ni composite also exhibits excellent low-temperature hydrogenation kinetics and almost no capacity degradation over nine hydrogenation/dehydrogenation cycles. The significant improvement in the hydrogen-storage properties is attributed to the in situ formation of ultrafine and stable Mg2NiH0.3 nanocrystals during cycling. This work provides a convenient approach to synthesize ultrafine metal nanoparticles for catalytic applications in the field of high energy storage density hydride materials.

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As non-precious-metal catalysts for the hydrogen evolution reaction (HER), molybdenum carbides have attracted extensive attention in recent years. Molybdenum carbides usually require high synthesis temperatures (>700 °C), which leads to a high cost. In this study, we report a controllable synthesis of heterophase molybdenum carbides (MoC/Mo2C) using a simple ball milling method without external thermal input. The as-obtained MoC/Mo2C catalysts exhibit excellent HER electrocatalytic activity and durability at all pH conditions in comparison with MoC or Mo2C alone. The interface of MoC/Mo2C formed in situ is the key factor in improving the electrocatalytic activity. This fabrication method is cheap and effective in generating heterophase interfaces, which can be employed in many other fields where interface engineering is needed.

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