Electrochemical oxidation of 2-propanol over platinum and palladium electrodes in alkaline media studied by in situ attenuated total reflection infrared spectroscopy

Abstract

The electrochemical oxidation of 2-propanol over Pt and Pd electrodes was evaluated in alkaline media. Linear sweep voltammograms (LSVs), chronoamperograms (CAs), and simultaneous time-resolved attenuated total reflection infrared (ATR-IR) spectra of both electrodes were obtained in a 0.25 M KOH solution containing 1 M 2-propanol. The onset potential of 2-propanol oxidation for Pt was lower than that for Pd in LSVs while the degree of performance degradation observed for Pd was significantly smaller than that observed for Pt in CAs. The main product of 2-propanol oxidation was acetone over both electrodes and, over Pt only, acetone produced was catalytically oxidized to the enolate ion, which was accumulated on the Pt surface, leading to significant performance degradation. Carbon dioxide and carbonate species (CO₃²⁻, HCO₃⁻) were not observed during 2-propanol oxidation over both electrodes, indicating that the complete oxidation of 2-propanol to CO₂ will be a minor reaction.