碱金属在石墨烯表面吸附,迁移行为的第一性原理研究

摘要

The adsorption and diffusion behavior of three different alkali metal adatoms (Li, Na and K) at three high symmetry sites on graphene were systematically investigated by the first principle method based on density functional theory (DFT).Electronic properties were calculated.All the three alkali adatoms (Li, Na and K) prefer to be adsorbed at the H site of graphene.The charge transfers from alkali metal adatoms to graphene when adatoms are adsorbed on graphene.Li→Na→K, the adsorption energy initially decreases and then increases with increasing atomic number of alkali metal atom along the group series.The adsorption of Li-graphene system is stronger than those of Na-graphene system and K-graphene system.The degree of ionic property of alkali metal-graphene system increases.The decrease in diffusion energy indicates that diffusion behavior of alkali metal adatoms on the surface of graphene is increasingly easy to take place.%利用基于密度泛函理论的第一性原理方法计算了3种碱金属(Li,Na,K)在石墨烯表面的吸附性质,迁移行为和电学性质.结果表明: 3种碱金属在石墨烯表面的最稳定吸附位都是H位;吸附过程中电荷由碱金属原子向石墨烯片层转移.Li→Na→K,吸附能先减小再增大,吸附的强弱顺序为Li-石墨烯体系>K-石墨烯体系>Na-石墨烯体系;体系的离子性逐渐增强;碱金属原子在石墨烯表面的迁移激活能逐渐降低,迁移行为更容易实现.