On-Surface Metathesis of an Ionic Liquid on Ag(111).

ABSTRACT: We investigated the adsorption, surface enrichment, ion exchange, and on-surface metathesis of ultrathin mixed IL films on Ag(111). We stepwise deposited 0.5 ML of the protic IL diethylmethylammonium trifluoromethanesulfonate ([dema][TfO]) and 1.0 ML of the aprotic IL 1-methyl-3-octylimidazolium hexafluorophosphate ([C₈ C₁ Im][PF₆ ]) at around 90 K. Thereafter, the resulting layered frozen film was heated to 550 K, and the thermally induced phenomena were monitored in situ by angle-resolved X-ray photoelectron spectroscopy. Between 135 and 200 K, [TfO]^- anions at the Ag(111) surface are exchanged by [PF₆ ]^- anions and enriched together with [C₈ C₁ Im]⁺ cations at the IL/vacuum interface. Upon further heating, [dema][PF₆ ] and [OMIm][PF₆ ] desorb selectively at ∼235 and ∼380 K, respectively. Hereby, a wetting layer of pure [C₈ C₁ Im][TfO] is formed by on-surface metathesis at the IL/metal interface, which completely desorbs at ∼480 K. For comparison, ion enrichment at the vacuum/IL interface was also studied in macroscopic IL mixtures, where no influence of the solid support is expected.

SUBMITTER: Massicot S 

PROVIDER: S-EPMC9321566 | biostudies-literature | 2022 May

REPOSITORIES: biostudies-literature