Abstract In this work, the NiCu solid solutions with different Ni/Cu molar ratios were prepared and then doped into MgH2 through ball milling to modify its hydrogen sorption properties. The experimental results show that the Ni–25%Cu and Ni–50%Cu exhibit the superior catalytic effect over pure Ni, pure Cu and Ni–75%Cu on the dehydrogenation of MgH2. Among them, the 5h-milled MgH2/Ni–50%Cu system starts to desorb hydrogen at 205.8 °C, which is about 96.9 °C lower than that of as-milled pristine MgH2. Moreover, the MgH2/Ni-50% Cu system can release 5.14 wt% hydrogen at 300 °C within 15 min, while MgH2 can only release 2.92 wt% hydrogen under the same condition. More importantly, the dehydrogenated MgH2/Ni–50%Cu can reabsorb 4.37 wt% hydrogen even at 250 °C for 30 min. The enhanced hydrogen sorption kinetics of MgH2/Ni–50%Cu mainly attributes to the “hydrogen spillover” effect of in-situ formed Mg2Ni(Cu) phases. Further theoretical calculations reveal that the strong interactions between H and Ni/Cu result in the weakened stability of MgH2, decreased bond strength of Mg–H and enhanced dehydrogenation properties of MgH2. This research provides an important guidance for design multiple transition metals catalysts to improve efficiently hydrogen storage properties of magnesium-based and other metal-based hydrides.

中文翻译：

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NiCu固溶体对MgH2储氢性能的催化作用及机理

摘要 本工作制备了不同Ni/Cu摩尔比的NiCu固溶体，然后通过球磨将其掺入MgH2中以改善其吸氢性能。实验结果表明，Ni-25%Cu和Ni-50%Cu对MgH2的脱氢表现出优于纯Ni、纯Cu和Ni-75%Cu的催化效果。其中，5h 研磨的 MgH2/Ni–50%Cu 系统在 205.8 °C 开始解吸氢，比研磨的原始 MgH2 低约 96.9 °C。此外，MgH2/Ni-50% Cu 体系在 300 °C 下可以在 15 分钟内释放 5.14 wt% 的氢气，而 MgH2 在相同条件下只能释放 2.92 wt% 的氢气。更重要的是，脱氢的 MgH2/Ni–50%Cu 即使在 250°C 下 30 分钟也能重新吸收 4.37 wt% 的氢气。MgH2/Ni–50%Cu 增强的吸氢动力学主要归因于原位形成的 Mg2Ni(Cu) 相的“氢溢出”效应。进一步的理论计算表明，H 和 Ni/Cu 之间的强相互作用导致 MgH2 的稳定性减弱，Mg-H 的结合强度降低，MgH2 的脱氢性能增强。该研究为设计多种过渡金属催化剂以有效提高镁基和其他金属基氢化物的储氢性能提供了重要指导。