Ethanol Oxidation on Pt Single-Crystal Electrodes: Surface-Structure Effects in Alkaline Medium

• Published in: Chemphyschem Vol. 15; no. 10; pp. 2019 - 2028
• Main Authors: Busó-Rogero, Carlos, Herrero, Enrique, Feliu, Juan M.
• Format: Journal Article
• Language: English
• Published: Weinheim WILEY-VCH Verlag 21.07.2014; WILEY‐VCH Verlag; Wiley; Wiley Subscription Services, Inc
• Subjects: alkaline solutions; Chemistry; Electrochemistry; Electrodes; Exact sciences and technology; General and physical chemistry; IR spectroscopy; Kinetics and mechanism of reactions; Oxidation; platinum; single-crystal electrodes; Spectrum analysis; Structure effect; Ethanol; Alcohol; Transition metal; IR spectroscopy; Single crystal; Surface structure; Surface effect; Electrodes; Infrared spectrometry; Platinum; Alkanol; Oxidation; alkaline solutions; single-crystal electrodes; oxidation; platinum
• ISSN: 1439-4235; 1439-7641
• DOI: 10.1002/cphc.201402044

Ethanol oxidation in 0.1 M NaOH on single‐crystal electrodes has been studied using electrochemical and FTIR techniques. The results show that the activity order is the opposite of that found in acidic solutions. The Pt(111) electrode displays the highest currents and also the highest onset potential of all the electrodes. The onset potential for the oxidation of ethanol is linked to the adsorption of OH on the electrode surface. However, small (or even negligible) amounts of COads and carbonate are detected by FTIR, which implies that cleavage of the CC bond is not favored in this medium. The activity of the electrodes diminishes quickly upon cycling. The diminution of the activity is proportional to the measured currents and is linked to the formation and polymerization of acetaldehyde, which adsorbs onto the electrode surface and prevents further oxidation. Inverted reactivity order: Ethanol oxidation on platinum single‐crystal electrodes in alkaline solutions produces mainly acetate and the activity order is the opposite of that found in acid solutions. The formation of acetaldehyde deactivates the surface (see picture).