期刊
ACS NANO
卷 6, 期 11, 页码 9818-9827出版社
AMER CHEMICAL SOC
DOI: 10.1021/nn303355b
关键词
Room temperature ionic liquid; densification; epitaxial graphene; mica; charge overscreening; interfacial structure; X-ray reflectivity
类别
资金
- Fluid Interface Reactions, Structures and Transport (FIRST) Center, an Energy Frontier Research Center
- U.S. Department of Energy (DOE), Office of Science (SC), Office of Basic Energy Sciences (BES)
- DOE-SC-BES [DE-AC02-06CH11357]
- DOE-SC [DE-AC02-05CH11231]
- Alexander von Humboldt Foundation
The nanoscale interactions of room temperature ionic liquids (Rills) 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 pi-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.
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