Interface of Ionic Liquids and Carbon: Ultrathin [C₁C₁Im][Tf₂N] Films on Graphite and Graphene

Abstract

We investigated the initial adsorption behavior and growth of thin films of ionic liquid (IL) [C 1 C 1 Im][Tf 2 N] on highly ordered pyrolytic graphite (HOPG) and on a full and a fractional graphene layer on Ni(111). We found that the initial adsorption behavior and growth strongly depended on the underlying substrate. On HOPG, the IL forms an initial wetting layer with a coverage of 0.5 ML and anions and cations next to each other in direct contact with the substrate. On a complete graphene layer on Ni(111), the wetting layer has twice the thickness with alternately oriented ion pairs next to each other. On top of these wetting layers, further IL growth occurs in 3D islands, with the island formation being less pronounced on the graphene layer. On the fractional graphene layer on Ni(111), initial IL adsorption preferentially occurs on bare Ni surface areas, with anions on top of cations, followed by 3D island growth on both the bare and the graphenecovered surface regions.

Adsorption and Electron‐Transfer Mechanisms of Ferrocene Carboxylates and Sulfonates at Highly Oriented Pyrolytic Graphite

“…The − RTg ' values of FcCH 2 OH and FcCH 2 CO 2 − are similar to each other despite different origins, i. e., hydrogen bonding and triple ion formation, respectively. Ion pairing has been reported for the HOPG surface in aqueous electrolyte solutions as well as in ionic liquids …”

“…Ion pairing has been reported for the HOPG surface in aqueous electrolyte solutions [38] as well as in ionic liquids. [39] It should be noted that À RTlnβ values depend on the strength of not only ferrocene-HOPG interactions but also ferrocene-water interactions in the solution. Accordingly, the lack of adsorption of oxidized ferrocene derivatives on HOPG is attributed at least partially to the stronger hydration of a positively charged ferrocenium group than a neutral ferrocene group in the aqueous solution.…”

Morphology of Imidazolium‐Based Ionic Liquids as Deposited by Vapor Deposition: Micro‐/Nanodroplets and Thin Films

“…The PVD techniques are more environmentally friendly than traditional coating methods, with several applications from scientific and industrial points of view.Infact, thin films produced by PVD are being developed and applied in electrical and semiconductor manufactories, for example, in organic electronics and optoelectronics (OLEDs, OPVs, OFETs), andu sed for energy conservation and/or generation. [26][27][28] The trend shifts observed fort he thermodynamic properties of vaporization of the [C n C 1 im][Ntf 2 ] IL series, which occur at [C 6 C 1 im][Ntf 2 ]( the CAS, or criticala lkyl size), are evidenceo ft he nanostructuration of ILs. [21] High-accuracyv apor-pressure data for the extended[ C n C 1 im] [Ntf 2 ]i onic liquid series were determined by Santos et al by using aK nudsen effusion apparatus combined with aQ CM and the authors contributed for ab etter understanding of the relationship between cohesive energies, volatilities, and liquid structures of ILs.…”

“…[27,[30][31][32][33] Due to their low vapor pressure, ILs are candidates for precursor film studies and the first study of precursor films spreading ahead of macroscopic droplets of imidazolium-based ILs (on smooth mica surfaces) was carriedo ut by Beattie et al [34] Additionally,i nr ecent literature reports there are several publications dedicated to interfacial tension studies, including the measuremento fc ontact anglesf ormed by various ILs on different solid substrates. [27,[30][31][32][33] Due to their low vapor pressure, ILs are candidates for precursor film studies and the first study of precursor films spreading ahead of macroscopic droplets of imidazolium-based ILs (on smooth mica surfaces) was carriedo ut by Beattie et al [34] Additionally,i nr ecent literature reports there are several publications dedicated to interfacial tension studies, including the measuremento fc ontact anglesf ormed by various ILs on different solid substrates.…”

Ionic Liquid Ordering at an Oxide Surface

“…The (101) surface is the most thermodynamically stable anatase surfacea nd is therefore the dominant surface exposed in nanoparticulate TiO 2 . [14] Although there is agrowing body of work on the surface chemistry of bulk ILs and thin films of ILs on metal surfaces studied by photoelectrons pectroscopy, [15][16][17][18][19][20][21][22][23][24][25][26][27] their interaction withm etal oxide solid surfaces is less well studied. [15][16][17][18]28] In this work we employacombination of X-ray photoelectrons pectroscopy (XPS) and near-edge X-ray absorption fine structure (NEXAFS) spectroscopy to shed light onto the interaction of 1-butyl-3-methylimidazolium tetrafuloroborate ([C 4 C 1 Im][BF 4 ]) with the anataseT iO 2 (101) surface.…”