| Autor: |
Chen Z; McKetta Department of Chemical Engineering, The University of Texas at Austin, Austin, Texas 78712, United States., Li Z; Texas Materials Institute, The University of Texas at Austin, Austin, Texas 78712, United States.; Materials Science and Engineering Program, The University of Texas at Austin, Austin, Texas 78712, United States., Zhao W; Department of Chemical and Biomolecular Engineering, Vanderbilt University, Nashville, Tennessee 37235, United States., Matsumoto RA; Department of Chemical and Biomolecular Engineering, Vanderbilt University, Nashville, Tennessee 37235, United States., Thompson MW; Department of Chemical and Biomolecular Engineering, Vanderbilt University, Nashville, Tennessee 37235, United States., Morales-Collazo O; McKetta Department of Chemical Engineering, The University of Texas at Austin, Austin, Texas 78712, United States., Cummings PT; Department of Chemical and Biomolecular Engineering, Vanderbilt University, Nashville, Tennessee 37235, United States., Mangolini F; Texas Materials Institute, The University of Texas at Austin, Austin, Texas 78712, United States.; Walker Department of Mechanical Engineering, The University of Texas at Austin, Austin, Texas 78712, United States., Brennecke JF; McKetta Department of Chemical Engineering, The University of Texas at Austin, Austin, Texas 78712, United States. |
| Abstrakt: |
The molecular-level orientation and structure of ionic liquids (ILs) at liquid-solid interfaces are significantly different than in the bulk. The interfacial ordering influences both IL properties, such as dielectric constants and viscosity, and their efficacy in devices, such as fuel cells and electrical capacitors. Here, we report the layered structures of four ILs on unbiased, highly ordered pyrolytic graphite (HOPG) and Pt(111) surfaces, as determined by atomic force microscopy. The ILs investigated are 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([emim][Tf 2 N]), 1-ethyl-3-methylimidazolium perfluorobutylsulfonate ([emim][C 4 F 9 SO 3 ]), 7-methyl-1,5,7-triazabicyclo[4.4.0]dec-5-ene bis(trifluoromethylsulfonyl)imide ([MTBD][Tf 2 N]), and 7-methyl-1,5,7-triazabicyclo[4.4.0]dec-5-ene perfluorobutylsulfonate ([MTBD][C 4 F 9 SO 3 ]). Molecular dynamics simulations provide complementary information on the position and orientation of the ions. These ILs form a cation layer at the IL-solid interface, followed by a layer of anions. [Emim] + and [MTBD] + have similar orientations at the surface, but [MTBD] + forms a thinner layer compared to [emim] + on both HOPG and Pt(111). In addition, [Tf 2 N] - shows stronger interactions with Pt(111) surfaces than [C 4 F 9 SO 3 ] - . |
