(1. 湖南大学 汽车车身先进设计制造国家重点实验室，长沙 410082；
2. 湖南大学 材料科学与工程学院，长沙 410082)
摘 要: 采用基于密度泛函理论的Dmol 4.1程序包，通过计算移走H原子所需能量及几何、电子结构的改变，对Ni掺杂MgH2体系解氢性能的机理进行探讨。结果表明：Ni替代Mg和创造Mg空位对MgH2体系解氢而言，均发挥有益作用，而形成Mg空位所需能量(6.51 eV)高于Ni替代Mg所需能量(2.12 eV)，表明低温下Ni替代Mg对MgH2体系解氢而言更有利，至此NiF2中的Ni替代MgH2中的Mg，有利于加速化学反应NiF2+3MgH2=MgF2+Mg2NiH4向右进行，使结构稳定的MgH2发生转变，生成结构不稳定的Mg2NiH4，这样体系解氢过程不是通过MgH2，而是转变为通过Mg2NiH4进行，因此，Ni掺杂提高了MgH2体系的解氢性能。
关键字: MgH2；Ni掺杂；密度泛函理论；解氢性能
Ni doped MgH2 systems
（1. State Key Laboratory of Advanced Design and Manufacturing for Vehicle Body, Hunan University,
Changsha 410082, China;
2. School of Materials Science and Engineering, Hunan University, Changsha 410082, China）
Abstract:According to experimental results in which the dehydrogenating properties of MgH2 systems were improved by addition of NiF2 as catalyst, the energy to remove H atoms, the geometry and electronic structure of MgH2 systems were calculated by using Dmol 4.1 program based on the density functional theory, and the mechanism of improved properties on Ni doped MgH2 systems were also analyzed. The results show that although both Ni substitution and Mg vacancies are effective in desorbing hydrogen at lower temperatures, the substitution of Ni at the Mg site is energetically more favorable than the formation of Mg vacancies. The Ni atoms of NiF2 can replace some Mg atoms of MgH2 systems, the reaction of NiF2+3MgH2=MgF2+Mg2NiH4 during mill process is accelerated, thus, MgH2 with the higher stability can be changed into Mg2NiH4. Because of a ternary hydride Mg2NiH4 with lower stability forming, the dehydrogenating properties on Ni doped MgH2 systems are improved.
Key words: MgH2; Ni doping; density functional theory; dehydrogenating properties
