Nanoscale Perturbations of Room Temperature Ionic Liquid Structure at Charged and Uncharged Interfaces

The nanoscale interactions of room temperature ionic liquids (RTILs) at uncharged (graphene) and charged (muscovite mica) solid surfaces were evaluated with high resolution X-ray interface scattering and fully atomistic molecular dynamics simulations. At uncharged graphene surfaces, the imidazolium-...

Full description

Saved in:
Bibliographic Details
Published in:ACS nano 2012-11, Vol.6 (11), p.9818-9827
Main Authors: Zhou, Hua, Rouha, Michael, Feng, Guang, Lee, Sang Soo, Docherty, Hugh, Fenter, Paul, Cummings, Peter T, Fulvio, Pasquale F, Dai, Sheng, McDonough, John, Presser, Volker, Gogotsi, Yury
Format: Article
Language:English
Subjects:
Cations
Charge density
Charging
Computer Simulation
Electromagnetic Fields
Graphene
Ionic liquids
Ionic Liquids - chemistry
Layering
Materials Testing
Mica
Models, Chemical
Molecular Conformation
Molecular Dynamics Simulation
Nanostructure
Nanostructures - chemistry
Nanostructures - ultrastructure
Particle Size
Phase Transition
Simulation
Surface Properties
Temperature
Citations: Items that this one cites
Items that cite this one
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:The nanoscale interactions of room temperature ionic liquids (RTILs) at uncharged (graphene) and charged (muscovite mica) solid surfaces were evaluated with high resolution X-ray interface scattering and fully atomistic molecular dynamics simulations. At uncharged graphene surfaces, the imidazolium-based RTIL ([bmim+][Tf2N–]) exhibits a mixed cation/anion layering with a strong interfacial densification of the first RTIL layer. The first layer density observed via experiment is larger than that predicted by simulation and the apparent discrepancy can be understood with the inclusion of, dominantly, image charge and π-stacking interactions between the RTIL and the graphene sheet. In contrast, the RTIL structure adjacent to the charged mica surface exhibits an alternating cation–anion layering extending 3.5 nm into the bulk fluid. The associated charge density profile demonstrates a pronounced charge overscreening (i.e., excess first-layer counterions with respect to the adjacent surface charge), highlighting the critical role of charge-induced nanoscale correlations of the RTIL. These observations confirm key aspects of a predicted electric double layer structure from an analytical Landau–Ginzburg-type continuum theory incorporating ion correlation effects, and provide a new baseline for understanding the fundamental nanoscale response of RTILs at charged interfaces.
ISSN:1936-0851
1936-086X
DOI:10.1021/nn303355b