Regensburg 2013 – scientific programme
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O: Fachverband Oberflächenphysik
O 52: Organic/bio Molecules on Metal Surfaces V
O 52.9: Talk
Wednesday, March 13, 2013, 18:00–18:15, H38
The metal | ionic liquid interface: Comparison of the adsorption behavior of different ionic liquids on Ag(111) — •Florian Buchner1,2, Benedikt Uhl1,2, Dorothea Alwast1,2, Hsinhui Huang1,2, and Rolf-Jürgen Behm1,2 — 1Helmholtz-Institute Ulm (HIU) Electrochemical Energy Storage, D-89069 Ulm, Germany — 2Ulm University, Institute of Surface Chemistry and Catalysis, D-89069 Ulm, Germany
Ionic liquids are promising candidates as electrolytes in Li-ion batteries, which play a key role in energy storage devices. In this model approach, we aim towards a molecular understanding of the processes at the metal electrode | ionic liquid interface. 1-butyl-1-methylpyrrolidinium-bis(trifluoromethylsulfonyl)imide [BMP]+[TFSA]− and 1-ethyl-3-methylimidazolium-bis(trifluoromethylsulfonyl)imide [EMIM]+[TFSA]− on Ag(111) are studied at mono- and submonolayer coverages by scanning tunneling microscopy (STM) under UHV conditions in the temperature range between 100 K and room temperature. [BMP]+[TFSA]− exists in a highly mobile 2D gas phase in the range between 300 K and 100 K, i.e., it exhibits a low diffusion barrier. Additionally, at 100 K a long-range ordered and homogeneous 2D solid phase fills up large terraces, and a 2D disordered phase is found close to steps. Dynamic STM measurements highlight exchange of adspecies at the phase boundary between 2D solid and 2D gas phase. The adsorption behavior of [BMP]+[TFSA]− and [EMIM]+[TFSA]− on Ag(111) is discussed, focusing on ordering aspects, diffusion properties and 2D melting.