Mg空位缺陷对MgH2解氢性能影响的赝势平面波法研究

摘要

采用基于密度泛函理论的第一性原理赝势平面波方法.考察了Mg空位缺陷对MgH<,2>体系解氢性能的影响及微观机理.结果表明:Mg空位缺陷的出现使MgH<,2>晶胞发生收缩,晶格产生畸变,且极大地降低了体系的结构稳定性,显著提高了体系的解氢动力学;电子结构分析表明:Mg空位缺陷改善MgH<,2>体系解氢性能的微观机理在于体系在费米能级以下成键电子数的减少以及费米能级附近能隙的变窄.%Using the first-principles pseudopotential plane-wave method based on density functional theory, the influences and micro-mechanisms of Mg atom vacancy defect on the dehydrogenation properties of MgH2 system were investigated. The results show that the appearance of Mg atom vacancy results in the shrinkage of crystal cell and distortion of MgH2 lattice, which significantly decreases the structural stability and remarkably improves the dehydrogenation kinetics of this system. Further analysis on electronic structures shows that the mico-mechanisms for Mg atom vacancy improving the dehydrogenation properties of MgH2 attribute to the decreasing bonding electrons number below Fermi energy level and the narrowing energy gap near Fermi energy level of MgH2 system with Mg atom vacancy.