Interfaces of Ionic Liquid Systems

• Applicant: Professor Dr. Hans-Peter Steinrück
• Subject Area: Physical Chemistry of Molecules, Liquids and Interfaces, Biophysical Chemistry ; Solid State and Surface Chemistry, Material Synthesis ; Physical Chemistry of Solids and Surfaces, Material Characterisation
• Term: from 2013 to 2017
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 238017235

• Final Report Year: 2017

Final Report Abstract

Ionic liquids (ILs) are molten salts with a melting point below 100 °C. Their structural diversity results into nearly unlimited possibilities to combine cations and anions with different properties. This allows tailoring their physico-chemical properties over a wide range and adapting them to specific applications. The interface of an IL with its environment has been recognized for a large number of application areas, in particular also for new concepts in catalysis. Due to their low vapour pressure, ILs can be investigated by ultrahigh vacuum-based methods and the area of Ionic Liquid Surface Science has started to establish itself within the last years. The applicants group has significantly contributed to this development, in particular using angle-resolved X-ray photoelectron spectroscopy. At the beginning of the project, the available studies mainly contained information on properties of particular systems, but a more general picture of the underlying mechanisms and driving forces was still missing. In this project, four specific topics were investigated: (1) the temperature-dependence of surface composition, orientation and enrichment effects of pure ILs and binary IL mixtures, (2) dissolution of metal complexes in ILs, (3) the properties of ionic liquid/support interactions, and (4) following chemical reactions in ionic liquid-based systems to exploit the potential of X-ray photoelectron spectroscopy for in situ monitoring. In all four areas significant new insights were obtained. Specific highlights are - Influence of substituents and functional groups on the surface composition of ionic liquids - Electrospray ionization deposition of ultrathin ionic liquid films on Au(111) - The interfaces of ionic liquids and carbon: ultrathin IL films on graphite and graphene - Switching adsorption and growth behavior of ultrathin films on Au(111) by Pd deposition - Carbon Dioxide Capture by an Amine Functionalized Ionic Liquid - Dehydrogenation of a liquid organic hydrogen carrier in the liquid state Altogether, a large number of important results have been obtained and published in altogether 17 project-related publications, 2 PhD theses and 2 MSc theses within the project period. The success earned the group of the applicant high international recognitions, as evidenced by more than 20 invited talks on IL-related topics at international conferences. In 2017 Prof. Steinrück was awarded the AVS Medard Welch Award for "For pioneering studies on the properties and reactivity of the surfaces of ionic liquids employing the methods of surface science". The obtained results and visibility also set the grounds for the Advanced ERC Grant on "Ionic liquid interface Dynamics" granted to Prof. Steinrück in 2016.

Publications

• Carbon Dioxide Capture by an Amine Functionalized Ionic Liquid: Fundamental Differences of Surface and Bulk Behavior. J. Am. Chem. Soc. 136 (2014) 436-441
  I. Niedermaier, M. Bahlmann, C. Papp, C. Kolbeck, W. Wei, S.Krick Calderón, M. Grabau, P. S. Schulz, P. Wasserscheid, H.-P. Steinrück, F. Maier
  
• Electrospray Ionization Deposition of Ultrathin Ionic Liquid Films: [C8C1Im]Cl and [C8C1Im][Tf2N] on Au(111). Langmuir 30 (2014) 1063–1071
  F. Rietzler, M. Piermaier, A. Deyko, H.-P. Steinrück, and F. Maier
  
• Influence of substituents and functional groups on the surface composition of ionic liquids. Chem. Eur. J. 20 (2014) 3954-3965
  C. Kolbeck, I. Niedermaier, A. Deyko, K. R. J. Lovelock, N. Taccardi, W. Wei, P.Wasserscheid, F. Maier, H.-P. Steinrück
  
• The Interface of Ionic Liquids and Carbon: Ultrathin [C1C1Im][Tf2N] Films on Graphite and Graphene. J. Phys. Chem. C 119 (2015) 28068−28076
  F. Rietzler, J. Nagengast, H.-P. Steinrück, F. Maier
  
• Vacuum surface science meets heterogeneous catalysis: Dehydrogenation of a liquid organic hydrogen carrier in the liquid state. ChemPhysChem 16 (2015) 1790-1790
  T. Matsuda, N. Taccardi, J. Schwegler, P. Wasserscheid, H.-P. Steinrück, F. Maier
  
• Dual Analyzer System for Surface Analysis (DASSA), a UHV system dedicated for angle resolved photoelectron spectroscopy at liquid surfaces and interfaces. Rev. Sci. Instrum. 87 (2016) 045105, p.1-14. Erratum: Rev. Sci. Instrum. 88 (2017) 059902
  I. Niedermaier, C. Kolbeck, H.-P. Steinrück, F. Maier
  
• Switching Adsorption and Growth Behavior of Ultrathin [C2C1Im][OTf] Films on Au(111) by Pd Deposition. Phys. Chem. Chem. Phys. 18 (2016) 25143-25150
  F. Rietzler, B. May, H.-P. Steinrück, F. Maier