Effects of surface step density on the electrochemical oxidation of ethanol to acetic acid

David J. Tarnowski, Carol Korzeniewski

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105 Scopus citations

Abstract

The electrochemical oxidation of ethanol (0.3 M in 0.1 M HClO4) was studied at Pt(111), Pt(557) ≡ Pt(s) - [6(111) × (100)], and Pt(335) ≡ Pt(s)-[4(111) × (100)] single crystal electrodes. The oxidation pathway leading to acetic acid showed a marked dependence on electrode surface structure; acetic acid formation decreased as the surface step density increased. On the stepped surfaces, facile C-C bond cleavage and high surface poisoning appear to account for the low acetic acid production. Isolation and quantification of acetic acid was achieved with ion chromatography. Oxidation products were generated in a small (∼40 μL) drop of electrolyte solution in contact with a single crystal electrode and analyzed following a short (60 s) electrolysis period. This approach enabled the specific and quantitative determination of soluble reaction products. For Pt(111), results were compared with acetic acid yields determined by in-situ infrared spectroscopy. Agreement between the two methods is within the uncertainty of the techniques. The results support unanticipated findings of earlier infrared spectroscopy studies, which indicate ethanol oxidation to acetic acid is inhibited on platinum surfaces that contain high surface step densities. Additionally, the percent of charge due to acetic acid formation was obtained by comparing the total anodic charge passed with the moles of acetate detected.

Original languageEnglish
Pages (from-to)253-258
Number of pages6
JournalJournal of Physical Chemistry B
Volume101
Issue number2
DOIs
StatePublished - Jan 9 1997

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