Tianjin Key Laboratory of Advanced Functional Porous Materials, Institute for New Energy Materials & Low-Carbon Technologies, School of Materials Science and Engineering, Tianjin University of Technology, NO.391 Binshui West Street Xiqing District, Tianjin 300384, China.
Molecules. 2018 Nov 28;23(12):3113. doi: 10.3390/molecules23123113.
Magnesium hydride (MgH₂) has become popular to study in hydrogen storage materials research due to its high theoretical capacity and low cost. However, the high hydrogen desorption temperature and enthalpy as well as the depressed kinetics, have severely blocked its actual utilizations. Hence, our work introduced Ni@C materials with a core-shell structure to synthesize MgH₂- wt.% Ni@C composites for improving the hydrogen desorption characteristics. The influences of the Ni@C addition on the hydrogen desorption performances and micro-structure of MgH₂ have been well investigated. The addition of Ni@C can effectively improve the dehydrogenation kinetics. It is interesting found that: i) the hydrogen desorption kinetics of MgH₂ were enhanced with the increased Ni@C additive amount; and ii) the dehydrogenation amount decreased with a rather larger Ni@C additive amount. The additive amount of 4 wt.% Ni@C has been chosen in this study for a balance of kinetics and amount. The MgH₂-4 wt.% Ni@C composites release 5.9 wt.% of hydrogen in 5 min and 6.6 wt.% of hydrogen in 20 min. It reflects that the enhanced hydrogen desorption is much faster than the pure MgH₂ materials (0.3 wt.% hydrogen in 20 min). More significantly, the activation energy () of the MgH₂-4 wt.% Ni@C composites is 112 kJ mol, implying excellent dehydrogenation kinetics.
氢化镁（MgH₂）因其理论容量高、成本低而成为储氢材料研究的热点。然而，其较高的脱氢温度和焓以及较差的动力学性能严重阻碍了其实际应用。因此，我们的工作引入了具有核壳结构的 Ni@C 材料，以合成 MgH₂- wt.% Ni@C 复合材料来改善其脱氢特性。研究了 Ni@C 的添加对 MgH₂脱氢性能和微观结构的影响。Ni@C 的添加可以有效提高脱氢动力学。有趣的是发现：i）随着 Ni@C 添加剂用量的增加，MgH₂的脱氢动力学得到了提高；ii）脱氢量随着较大的 Ni@C 添加剂用量而减少。在这项研究中，选择了 4wt%的 Ni@C 添加剂，以平衡动力学和数量。MgH₂-4wt%Ni@C 复合材料在 5 分钟内释放 5.9wt%的氢气，在 20 分钟内释放 6.6wt%的氢气。这表明增强的脱氢速度比纯 MgH₂材料（20 分钟内 0.3wt%的氢气）快得多。更重要的是，MgH₂-4wt%Ni@C 复合材料的活化能（）为 112kJ/mol，表明具有优异的脱氢动力学性能。
