计算物理 ›› 2017, Vol. 34 ›› Issue (6): 705-712.

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元素替代对MgH2储氢材料释氢影响机理的第一原理研究

麻洪吉, 张国英, 方戈亮   

  1. 沈阳师范大学物理科学与技术学院, 沈阳 110034
  • 收稿日期:2016-09-05 修回日期:2017-03-02 出版日期:2017-11-25 发布日期:2017-11-25
  • 通讯作者: 张国英,E-mail:gyzhang1965@sina.com
  • 作者简介:麻洪吉(1989-),女,内蒙古赤峰市人,硕士生,从事凝聚态物理研究,E-mail:1654192252@qq.com
  • 基金资助:
    国家自然科学基金(51371049);国家高技术研究发展计划(2009AA05Z105)资助项目

First-Principles Study on Dehydrogenation Ability of MgH2 Hydrogen Storage Materials with Component Element Substitution

MA Hongji, ZHANG Guoying, FANG Geliang   

  1. College of Physics Science and Technology, Shenyang Normal University, Shenyang 110034, China
  • Received:2016-09-05 Revised:2017-03-02 Online:2017-11-25 Published:2017-11-25

摘要: 用基于密度泛函理论的赝势平面波第一原理方法研究金属元素替代对MgH2释氢的影响机理.结果表明:带隙的宽窄和带隙中是否存在杂质能级是影响MgH2储氢材料释氢性能的关键因素,Nb,Fe,Ti,V在能隙近中央引入杂质能级,使得MgH2的H-Mg键键强减弱,有利于放氢.La在导带底引入杂质能级,降低带隙宽度,晶体中结合最弱的键断裂变得容易,也有利于放氢.Nb,Fe,Ti,V,La与近邻氢原子间形成共价键,形成金属氢化物,对释氢起到催化作用.La与H间的共价作用较弱,其金属氢化物的催化作用相对较弱.掺杂元素使Mg与周围H的静电作用力不对称,与Mg作用力小的H容易释放出来,起到提高MgH2释氢的作用.比较发现V,Fe明显降低Mg-H间的离子键强度.

关键词: 储氢材料, 元素替代, 密度泛函理论, 释氢机理

Abstract: Pseudopotential plane-wave method based on density functional theory was used to study influences of metal elements substitution on dehydrogenation of MgH2. It shows that width of band gap and impurity energy levels are key factors. Impurity energy levels introduced by Fe, V, Nb, Ti are in the middle of energy gap, while those introduced by La are in the bottom of conduction band. Energy gap becomes narrower. The weakest Mg-H bond breaks easier, which is helpful to MgH2 dehydrogenation. Covalent bonds formed between Nb, Fe, Ti, V, La and neighboring hydrogen lead to metal hydrides formation, which plays a catalytic role to dehydrogenation of MgH2. Electrostatic forces between Mg1 and surround hydrogens are no longer symmetrical duo to doping. H with weaker force to Mg releases easier, which improves dehydrogenation properties of MgH2.

Key words: hydrogen storage materials, substituting behavior, density functional theory, dehydrogenating mechanism

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