Electrooxidation of ethanol and acetaldehyde in neutral electrolyte, an infrared study

Abstract

• EOR in neutral electrolyte takes place via C1 and C2 pathways. • In situ FTIR reveal the formation of CO adsorbed on the Pt surface at low potentials. • The scission of the C-C bond of ethanol takes place at ca. 300 mv. • Acetic acid is the main reaction product of the EOR or AOR at high potentials. The electrooxidation of ethanol (EOR) in neutral media is attracting a great deal of attention, especially in the area of micro devices and microbial fuel cells. In this work we study the EOR with Pt/C in neutral electrolyte and followed the evolution of the species formed with the potential by in situ FTIR. The EOR in neutral electrolyte displays higher overpotentials than in acid electrolyte but follows a similar reaction pathway, producing mainly C1 species (CO ad , CO 2 ) and C2 species (acetaldehyde, and acetic acid). The scission of the C C bond of ethanol takes place at 200 mV, a potential higher than in acid electrolyte. According to the FTIR experiments, the production of acetaldehyde during the EOR is higher than that of acetic acid. We have also studied the electrooxidation of acetaldehyde (AOR) in a neutral medium with FTIR. We observed the production of CO ad at 300 mV which is oxidized to CO 2 from E ≥ 700 mV.