Surface-Enhanced Infrared Spectroscopic Study of a
CO-Covered Pt Electrode in Room-Temperature Ionic Liquid
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Abstract
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 <i>N</i>-butyl-<i>N</i>-methyl-piperidinium bis((trifluoromethyl)sulfonyl)imide
(or [Pip<sub>14</sub>][TNf<sub>2</sub>]). Owing to a wide effective
potential window of [Pip<sub>14</sub>][TNf<sub>2</sub>], a gradual
conversion from bridged CO<sub>ad</sub> (CO<sub>B</sub>) to terminal
CO<sub>ad</sub> (CO<sub>L</sub>) is observed in response to positively
going potentials, suggesting that [Pip<sub>14</sub>]<sup>+</sup> may
be involved in a strong electrostatic interaction with the CO<sub>ad</sub>. This site conversion enables the ratio of the apparent
absorption coefficient of CO<sub>L</sub> to that of CO<sub>B</sub> to be determined. Also, the spectral results reveal the potential-dependent
CO<sub>ad</sub> frequency variations as well as the potential-induced
interfacial ionic reorientation and movement at the Pt/CO/[Pip<sub>14</sub>][TNf<sub>2</sub>] interface