Metal ammine complexes (MACs) were recently regarded as one of promising materials for reversible hydrogen storage due to their high hydrogen content. In this work, a first attempt is conducted to elucidate the hydrogen storage reversibility by combining Mg(NH 3 ) 6 Cl 2 with LiH. It is found that hydrogen is gradually evolved from the combined system during ball milling. After 24 h of milling, approximate 3.5 mass% of hydrogen, equivalent to 6 mol of H 2 molecules, is released from the Mg(NH 3 ) 6 Cl 2 -18LiH mixture. Additional 3.4 mass% of hydrogen is further desorbed from the combined system milled for 24 h with a two-step reaction in heating process. Totally $ 12 mol of H 2 molecules are librated from the Mg(NH 3 ) 6 Cl 2 -18LiH mixture along with the formation and consumption of Mg(NH 2 ) 2 and LiNH 2 in the ball milling and subsequent heating process. The resultant products consist of Li 2 Mg(NH) 2 , Li 2 NH, LiH and LiCl after dehydrogenation at 310 C. Further hydrogenation experiment indicates that $ 6 mol of H 2 molecules are reversibly stored in the Mg(NH 3 ) 6 Cl 2 -12LiH mixture.

Heterostructured nanowires, such as core/shell nanowires and nanoparticle-decorated nanowires, are versatile building blocks for a wide range of applications because they integrate dissimilar materials at the nanometer scale to achieve unique functionalities. The sol-flame method is a new, rapid, low-cost, versatile, and scalable method for the synthesis of heterostructured nanowires, in which arrays of nanowires are decorated with other materials in the form of shells or chains of nanoparticles. In a typical sol-flame synthesis, nanowires are dip-coated with a solution containing precursors of the materials to be decorated, then dried in air, and subsequently heated in the post-flame region of a flame at high temperature (over 900°C) for only a few seconds. Here, we report the effects of the precursor solution on the final morphology of the heterostructured nanowire using Co3O4 decorated CuO nanowires as a model system. When a volatile cobalt salt precursor is used with sufficient residual solvent, both solvent and cobalt precursor evaporate during the flame annealing step, leading to the formation of Co3O4 nanoparticle chains by a gas-solid transition. The length of the nanoparticle chains is mainly controlled by the temperature of combustion of the solvent. On the other hand, when a non-volatile cobalt salt precursor is used, only the solvent evaporates and the cobalt salt is converted to nanoparticles by a liquid–solid transition, forming a conformal Co3O4 shell. This study facilitates the use of the sol-flame method for synthesizing heterostructured nanowires with controlled morphologies to satisfy the needs of diverse applications.

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