Stephan Régis, Hanf Marie-Christine, Sonnet Philippe
Université de Haute-Alsace, IS2M UMR 7361 CNRS-UHA, 15 rue Jean Starcky, 68057 Mulhouse, France.
Phys Chem Chem Phys. 2015 Jun 14;17(22):14495-501. doi: 10.1039/c5cp00613a.
Among the 2D crystals, silicene, which forms sp(2)-sp(3) bonds, is expected to present a higher reactivity than graphene, characterized by sp(2) bonds only. However, silicene functionalization, in particular with organic molecules, remains an open question. By means of density functional theory, we study the adsorption of benzene, a model organic molecule, on (3 × 3) silicene on the (4 × 4) Ag(111) surface. Our calculations show that the dispersion interactions must be taken into account in order to describe this system properly. The adsorption energy is calculated by means of the semi-empirical dispersion-corrected density functional theory (DFT-D2) and the optB86b-vdW density functional. The charge density and electron localization function maps indicate that the molecule is chemisorbed on the silicene surface by means of two Si-C covalent bonds. In agreement with charge density difference calculations, two C-C double bonds are formed in the benzene molecule, which adopts a butterfly configuration. The silicene lattice is slightly deformed upon benzene adsorption, but the Si-Si distance remains the same as in bare silicene/Ag(111). Bader analysis shows a charge transfer from top Si atoms to both molecules and Ag substrates. Finally, we show that the covalent functionalization of silicene is possible.
在二维晶体中，形成sp(2)-sp(3)键的硅烯预计比仅以sp(2)键为特征的石墨烯具有更高的反应活性。然而，硅烯功能化，特别是与有机分子的功能化，仍然是一个悬而未决的问题。借助密度泛函理论，我们研究了模型有机分子苯在(4×4)Ag(111)表面上的(3×3)硅烯上的吸附。我们的计算表明，为了恰当地描述这个体系，必须考虑色散相互作用。吸附能通过半经验色散校正密度泛函理论(DFT-D2)和optB86b-vdW密度泛函来计算。电荷密度和电子定域函数图表明，该分子通过两个Si-C共价键化学吸附在硅烯表面。与电荷密度差计算结果一致，苯分子中形成了两个C-C双键，其采用蝶形构型。苯吸附后硅烯晶格略有变形，但Si-Si距离与裸硅烯/Ag(111)中的相同。Bader分析表明存在从顶部Si原子到分子和Ag衬底的电荷转移。最后，我们表明硅烯的共价功能化是可能的。
