B、N掺杂对钠在石墨烯上吸附性能的影响

采用基于密度泛函理论的第一性原理方法，研究了本征石墨烯及缺陷石墨烯对Na原子的吸附行为。主要研究了三种石墨烯：本征石墨烯、B掺杂的石墨烯和N掺杂的石墨烯。结果表明，与本征石墨烯相比，B掺杂的石墨烯和N掺杂的石墨烯在吸附能、电荷密度、态密度和储钠量方面表现出很大的差异。B掺杂的石墨烯对Na原子的吸附能是-1.93 eV，约为本征石墨烯对Na原子吸附能的2.7倍；与本征石墨烯相比，N掺杂的石墨烯对Na原子的吸附能明显增大。态密度计算结果表明，Na原子与B掺杂的石墨烯中的B原子发生轨道杂化，而本征石墨烯和N掺杂的石墨烯中不存在轨道杂化现象。B掺杂的石墨烯对Na原子的吸附量是3个，与本征石墨烯相比显著提高。因此，B掺杂的石墨烯有望成为一种新型的储钠材料。

Effects of Boron and Nitrogen doping on Na Adsorption on Graphene

We investigate the adsorption properties of Na atoms on graphenes using the first-principles method of density functional theory combined with the pseudopotential approximation. Three types of graphenes have been mainly considered: intrinsic graphene, B-doped graphene and N-doped graphene. The results indicate that two types of graphenes, i.e. doped with B and N to replace C atoms, exhibit prodigious differences from the intrinsic graphene in terms of the adsorption energy, charge density, density of states and Na storage capacity on graphenes. The adsorption energy of Na on B-doped graphene is -1.93 eV, which is over 2.7 times that of Na on the intrinsic graphene, while the N-doped graphene has a higher adsorption energy than the intrinsic graphene. Moreover, the orbital hybridizations can be observed in the B-doped graphene, while there is no evidence of orbital hybridization in the intrinsic or N-doped graphenes. Each B atom can adsorb up to three Na atoms, which is larger than that of intrinsic and N-doped graphenes. Therefore, B-doped graphene is expected to be novel materials for storing Na.