掺杂Fe对VH_2解氢性能影响的第一性原理研究

摘要

采用密度泛函理论（DFT）的第一性原理的平面波超软赝势方法,研究了Fe掺杂对VH2的电子结构和解氢性能的影响.通过计算Fe掺杂VH2前后体系的合金形成热、V-H之间的重叠布居数、电子态密度、电子密度,发现Fe掺杂VH2后,随着Fe含量增加,合金体系的晶胞参数和晶胞体积逐渐减少;体系的负合金形成热逐渐减少,且掺杂后体系的负合金形成热都比VH2的负合金形成热小,体系的稳定性降低;电子态密度计算也显示Fe掺杂后费米能级处的电子浓度增加,体系稳定性降低;重叠布居数和电子密度计算表明掺杂后V-H之间的重叠布居数由0.1减小为0.08或0.09,V-H之间的电子密度减少,说明V和H原子之间的相互作用减弱,提高了VH2的解氢性能.计算结果解释了实验现象.%In this paper,the influence of doping Fe on the electronic structure and the dehydrogenation property of VH2 is investigated by using the plane wave ultrasofi pseudopotential method which is base on the first principles of density functional theory （DFT）.The calculated results are as follows：（1）the unit cell volume,the cell parameter,and the alloy formation heat of VH2 gradually decrease with the increase of Fe;（2） the fermi level electron density increases by dopping Fe;（3）the population the and electron density of V-H bond both decrease with doped Fe.These results indicate that the stability is declined and the interaction between V and H atom is weakened by adding Fe into the VH2 system.So it comes to the conclusion that the hydrogen desorption property of VH2 can be improved by adding Fe.