Tang Fujie, Ohto Tatsuhiko, Hasegawa Taisuke, Bonn Mischa, Nagata Yuki
International Center for Quantum Materials, Peking University, 5 Yiheyuan Road, Haidian, Beijing 100871, China and Max-Planck Institute for Polymer Research, Ackermannweg 10, D-55128, Mainz, Germany.
Graduate School of Engineering Science, Osaka University, 1-3 Machikaneyama, Toyonaka, Osaka 560-8531, Japan.
Phys Chem Chem Phys. 2017 Jan 25;19(4):2850-2856. doi: 10.1039/c6cp07034e.
The interfacial structure of room temperature ionic liquids (RTILs) controls many of the unique properties of RTILs, such as the high capacitance of RTILs and the efficiency of charge transport between RTILs and electrodes. RTILs have been experimentally shown to exhibit interfacial molecular layering structures over a 10 Å length scale. However, the driving force behind the formation of these layered structures has not been resolved. Here, we report ab initio molecular dynamics simulations of imidazolium RTIL/air and RTIL/graphene interfaces along with force field molecular dynamics simulations. We find that the π-π interaction of imidazolium cations enhances the layering structure of RTILs, despite the electrostatic repulsion. The length scales of the molecular layering at the RTIL/air and RTIL/graphene interfaces are very similar, manifesting the limited effect of the substrate on the interfacial organization of RTILs.
室温离子液体（RTILs）的界面结构控制着RTILs的许多独特性质，例如RTILs的高电容以及RTILs与电极之间的电荷传输效率。实验表明，RTILs在10 Å的长度尺度上呈现出界面分子分层结构。然而，这些分层结构形成背后的驱动力尚未得到解决。在此，我们报告了咪唑鎓RTIL/空气和RTIL/石墨烯界面的从头算分子动力学模拟以及力场分子动力学模拟。我们发现，尽管存在静电排斥作用，但咪唑鎓阳离子的π-π相互作用增强了RTILs的分层结构。RTIL/空气和RTIL/石墨烯界面处分子分层的长度尺度非常相似，这表明基底对RTILs界面组织的影响有限。
