“In situ” infrared reflectance spectroscopic study of the early stages of ethanol adsorption at a platinum electrode in acid medium

Abstract

The early stages of ethanol adsorption at a platinum electrode in acid medium are investigated using electrochemically modulated infrared reflectance spectroscopy (EMIRS). The superficial concentration of the different types of adsorbed species depends on the concentration of ethanol in the bulk, on the electrode potential and on the adsorption time. At low concentrations of C 2H 5OH, where the formation of CO ads appears to be slow, the observation of vibrational bands due to weakly adsorbed species becomes possible. Thus, enol-type species, like =CHOH, or adsorbed products, like CH 3COOH or CH 3CHO (bands at ≈ 1720 cm −1), are likely to be present at the electrode surface. Depending on the experimental conditions, other bands (sometimes complex) at 1200, 1305, 1380, 1620, 1825, 2350 and 3000 cm −1 are also detected. Their assignments are discussed.