Surface-Enhanced Infrared Spectroscopic Study of a CO-Covered Pt Electrode in Room-Temperature Ionic Liquid.

ATR-SEIRAS is extended for the first time to study potential-induced surface and interface structure variation of a CO-covered Pt electrode in a room-temperature ionic liquid of N-butyl-N-methyl-piperidinium bis((trifluoromethyl)sulfonyl)imide (or [Pip14][TNf2]). Owing to a wide effective potential window of [Pip14][TNf2], a gradual conversion from bridged COad (COB) to terminal COad (COL) is observed in response to positively going potentials, suggesting that [Pip14](+) may be involved in a strong electrostatic interaction with the COad. This site conversion enables the ratio of the apparent absorption coefficient of COL to that of COB to be determined. Also, the spectral results reveal the potential-dependent COad frequency variations as well as the potential-induced interfacial ionic reorientation and movement at the Pt/CO/[Pip14][TNf2] interface.