Molecular Dynamics Study of the Gold/Ionic Liquids Interface

Abstract

The results of a systematic molecular dynamics study of the interfacial structure between the gold (100) surface and two room-temperature ionic liquids, namely, 1-butyl-3-methylimidazolium hexafluorophosphate ([BMIm][PF6]) and 1-butyl-3-methylimadazolium bis(trifluoromethylsulfonyl)imide ([BMIm][NTf2]), are herein reported. It is found that near an uncharged surface the IL structure differs from its bulk, having an enhanced density extended until the two first layers. Interfacial layering is clearly observed at the gold surface, with a higher effect for the [BMIm][NTf2] IL but a higher packing for [BMIm][PF6]. In both ILs the alkyl side chains are oriented parallel to the interface while the imidazolium rings tend to be parallel to the interface in about 60% of the cases. The presence of the interface has a higher impact on the orientation of the cations than on the chemical properties of the counterion. The surface potential drop across the interface is more pronounced toward a negative value for ([BMIm][PF6]) than for ([BMIm][NTf2]), due to relatively larger local density of the anions for ([BMIm][PF6]) near the gold surface.

From Water Solutions to Ionic Liquids with Solid State Nanopores as a Perspective to Study Transport and Translocation Phenomena

“…[ 115 ] The same trends we observed also on hydroxylated alumina as shown for the [EMim] + and [HMim] + on the right panel of Figure 5a, a result that could be confirmed by infra‐red [ 116 ] or X‐ray photoelectron spectroscopy. [ 117 ] The simulations on the metal interfaces (Au(111)) yielded similar organization of the ions as on metal‐oxides surfaces, [ 103,118,119 ] again in agreement with experiments. [ 120,121 ] Regarding long range ordering, as shown with X‐ray reflectivity, the strongest effects are observed for small ions as shown in number density profiles of [EMim][NTf 2 ] (see Figure 5b), while the structural complexity of large cations introduces disorder already 4–5 nm from the surface.…”

Elimination of Interionic Hydrogen Bonding in The Imidazolium-Based Ionic Liquids

“…The imidazolium-based ionic liquids [8][9][10][11] hold promise for application in the eld of energy storage. For instance, they can be used as robust electrolytes in electric double-layer capacitors because the imidazolium-based RTILs possess a much wider potential window, better thermal stabilities, higher power densities, and lower saturated vapor pressures as compared to most of the conventional organic and aqueous electrolyte systems.…”

Solvation of the morpholinium cation in acetonitrile. Effect of an anion

“…Ionic liquids (ILs) constitute an established class of compounds with unique physical chemical properties. [1][2][3][4][5][6][7][8][9][10][11][12][13] These properties include negligible vapor pressure, high electrical conductivity, electrochemical stability, non-flammability, tunability and unusually large temperature range of the liquid state. ILs of current research interest 1 can be constructed out of cations, representing imidazolium, pyridinium, pyrrolidinium, ammonium, phosphonium, cholinium, and morpholinium families.…”