程光杰 祝杰 张清杰 王常春

摘要：本文系统研究了石墨烯（graphene）对MgYAl合金储氢性能的增强作用。结果表明，在高压氢气氛球磨作用下，MgYAl将转变为MgH、YAl、YH和Mg（Al）固溶体，而石墨烯以非晶形式均匀分布在基体中。与纯MgYAl合金相比，添加5 wt%石墨烯可以显著改善其动力学性能和循环稳定性。所制备的MgYAl–5 wt% graphene复合材料在300 ºC时，30min可快速放氢5.77 wt%，放氢反应激活能由纯合金的115 kJ/mol降至108.17 kJ/mol。经过50次循环后，此复合材料的放氢量衰减至4.83 wt%，容量保持率约为84%，高于纯合金的容量保持率（77%）。上述性能改善归因于，所添加的高比表面积石墨烯不仅作为活性催化位点促进H原子进出Mg基体，还作为缓冲剂来抑制Mg晶粒长大。

关键词：储氢  Mg基合金  催化  石墨烯  动力学

Reversible Hydrogen Storage Properties of MgYAl Alloys Enhanced by Doping Graphene

CHENG GuangJie  ZHU Jie  ZHANG QingJie  WANG Changchun

（The 404 Company Limited CNNC， Lanzhou， Gansu Province， ;732850 China）

Abstract： The effect of graphene on hydrogen storage properties of MgYAl alloy is studied systemically in this paper. The results show that the MgYAltransforms into MgH， YAl， YH and Mg（Al） solid solution upon ball-milling under H atmosphere， whereas the graphene exists as an amorphous nature. Compared to pure MgYAl alloy， doping graphene is an effective strategy for promoting kinetic and cyclic performances. The MgYAl–5 wt% graphene composites can release 5.77 wt% H within 30 min at 300 ºC by a reduced activation energy from 115 kJ/mol to 108.17 kJ/mol. After 50 cycles， the hydrogen desorption of this composite decayed to 4.83 wt%， and the capacity retention rate was about 84%， which was higher than that of the pure alloy （77%）. The above performance improvement is attributed to that the added graphene with high specific surface area not only acts as an active catalytic site to facilitate the transfer of H atoms into and out of the Mg matrix， but also acts as a buffer to suppress Mg grain growth..

Key Words： Hydrogen storage; Mg-based alloys; Catalysis; Graphene; Kinetics

實现氢的安全、高效存储是氢能技术利用的关键。与传统的高压气态储氢和低温液态储氢相比，固态储氢技术因具有存储密度高、安全、可移动等优点，被认为是最具前景的储氢技术。然而，现已开发的LaNi和TiMn合金，其储氢量都低于2 wt.%，难以满足容量车载储氢材料>5.5 wt.%的容量需求。因此，亟需开发高容量轻质固态储氢材料。

镁（Mg）基储氢材料具有较高的理论含氢量（7.6 wt.%）、可逆性好和来源丰富等优势，但其存在的热力学和动力学难题阻碍了实际应用。于是，人们提出了催化掺杂策略来改善上述储氢性能。如原位掺杂MgNiH和RH（R：稀土元素）颗粒对MgH的吸/放氢反应具有明显的催化作用。最近，研究发现球磨82MgH–3PrH–15Al复合材料具有优越的吸放氢性能，这是因为原位形成的PrAl纳米颗粒均匀地分散于样品中发挥催化作用。……