title: Ionic Liquid Ordering at an Oxide Surface.
abstract: The interaction of the ionic liquid [C4C1Im][BF4] with anatase TiO2, a model photoanode material, has been studied using a combination of synchrotron radiation photoelectron spectroscopy and near-edge X-ray absorption fine structure spectroscopy. The system is of interest as a model for fundamental electrolyte-electrode and dye-sensitized solar cells. The initial interaction involves degradation of the [BF4]-anion, resulting in incorporation of F into O vacancies in the anatase surface. At low coverages, [C4C1Im][BF4] is found to order at the anatase(101) surface via electrostatic attraction, with the imidazolium ring oriented 32±4° from the anatase TiO2surface. As the coverage of ionic liquid increases, the influence of the oxide surface on the topmost layers is reduced and the ordering is lost.
authors.affiliation: School of Physics and Astronomy, The University of Manchester, Oxford Road, Manchester, M139PL, UK.
authors.forename: Michael
authors.initials: M
authors.lastname: Wagstaffe
authors.affiliation: School of Physics and Astronomy, The University of Manchester, Oxford Road, Manchester, M139PL, UK.
authors.forename: Mark J
authors.initials: MJ
authors.lastname: Jackman
authors.affiliation: Jeremiah Horrocks Institute, The University of Central Lancashire, Fylde Road, Preston, PR1 2HE, UK.
authors.forename: Karen L
authors.initials: KL
authors.lastname: Syres
authors.affiliation: MAX IV Laboratory, Fotongatan 2, 225 94, Lund, Sweden.
authors.forename: Alexander
authors.initials: A
authors.lastname: Generalov
authors.affiliation: School of Materials and Photon Science Institute, The University of Manchester, Oxford Road, Manchester, M139PL, UK.
authors.forename: Andrew G
authors.identifier: http://orcid.org/0000-0002-1900-6686
authors.initials: AG
authors.lastname: Thomas
keywords: X-ray spectroscopy; adsorption; ionic liquids; photoelectron spectroscopy; titanium dioxide