Enhancement in dehydriding performance of magnesium hydride by iron incorporation: A combined experimental and theoretical investigation
Enhancement in dehydriding performance of magnesium hydride by iron incorporation: A combined experimental and theoretical investigation
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DOI：
10.1016/j.jpowsour.2016.05.031
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发表时间：
2016-08-01
影响因子：
9.2
通讯作者：
Zhou, Shixue
中科院分区：
文献类型：
--
作者：
Chen, Haipeng;Yu, Hao;Zhou, Shixue
采用第一性原理计算，对反应球磨过程中引入Fe原子后MgH 2的结构变化和放氢机理进行了表征和模拟。以经过预处理的无烟煤为助磨剂，Mg粉在氢气气氛下球磨3.0h，生成β-和γ-MgH 2两种产物。实验研究表明，Fe基球磨球对Mg/MgH 2颗粒的剪切作用可使Fe原子嵌入MgH 2表面。Fe在MgH 2表面具有很高的分散性，并能与H阴离子结合形成FeH 4/FeH 2原子团簇。Mg H2的放氢反应从氢化物表面开始，表现出明显的放氢活性，其表观活化能为110.3kJ mol（-1）。理论研究表明，在H-2分子形成之前，Fe的引入起到了电子从H阴离子向Mg阳离子转移的桥梁作用。Fe原子催化MgH_2脱氢反应的内在原因在于其中等的电子吸引力。(C)© 2016 Elsevier B. V.版权所有。
Structural change and dehydriding mechanism of MgH2 with atomic Fe incorporation from reactive ball milling are characterized and simulated by first-principles calculation. Two kinds of hydrides beta- and gamma-MgH2 are formed from Mg powders under hydrogen atmosphere by 3.0 h of milling with pretreated anthracite as milling aid. Experimental studies suggest that the atomic Fe can be incorporated onto MgH2 surface by the shearing effect of Fe-based milling balls on Mg/MgH2 particles. The incorporated Fe has a high dispersity on MgH2 surface and can form atomic clusters FeH4/FeH2 by combining with H anions. The dehydriding reaction of the Fe-incorporated MgH2 begins at hydride surface and shows an enhanced performance with apparent activation energy of 110.3 kJ mol(-1). Theoretical studies suggest that the incorporated Fe can act as a bridge that contributes to electron transfer from H anion to Mg cation before H-2 molecule formation. The intrinsic reason of atomic Fe in catalyzing dehydriding reaction of MgH2 lies in its moderate strength of electron attraction. (C) 2016 Elsevier B.V. All rights reserved.