Electrooxidation of ethanol on Pt in the absence of water

Abstract

It is well accepted that the electrooxidation of ethanol on Pt in aqueous solution proceeds via two parallel pathways: C1-pathway, which is the complete oxidation of ethanol to CO2 via COad intermediate, and C2-pathway, which produces acetaldehyde and also acetic acid with further oxidation. Water plays important roles for the oxidation, i.e., for the oxidative removal of COad in the C1-pathway and for the oxidation of acetaldehyde to acetic acid in the C2-pathway. In the present work, however, we show that the ethanol oxidation proceeds in the absence of water. Detailed study using surface-enhanced infrared absorption spectroscopy and high-performance liquid chromatography reveals that COad reacts with ethanol to form ethyl formate, which is designated as C3-pathway, and also that the ethanol oxidation produces ethyl acetate, which is designated as C4-pathway.