Study on the behavior of halide ions contained in ionic liquids on Au(111) electrode surface

Tamura, Kazuhisa   ; Nishihata, Yasuo

Ionic liquids have been recognized as a brand-new solvent since they have quite unique properties. Ionic liquids are "salts" but organic compounds; thus, ionic liquids can be tuned by altering their molecular structure. One of the problem in using ionic liquids is "impurity". Typical impurities contained in ionic liquids are water and halide ions, and it has been known that the impurities affect electrochemical reactions. However, it has not been uncleared that how the impurities exist at the ionic liquid/electrode interface and affect the interface structure. We investigated the structure of Au(111) electrode surface in ionic liquids containing halide ions using surface X-ray scattering. Our results suggest that halide ions were co-adsorbed with ionic liquid molecules and they affect the kinetics of phase transition of surface structure.