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An in Situ FTIR Study of Ethanol Oxidation at Polycrystalline Platinum in 0.1 M KOH at 25 and 50 degrees C

Lookup NU author(s): Professor Paul Christensen, Steven Jones

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This work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License (CC BY-NC 4.0).


Abstract

The electrochemical oxidation of ethanol at a polycrystalline Pt electrode was studied using in situ Fourier transform infrared (FTIR) spectroscopy in 0.1 M KOH at 25 and 50 degrees C. It was found that the equilibrium between Pt and reversibly adsorbed OH shifts to favor the latter at 50 degrees C compared to 25 degrees C, and this was reflected in the higher oxidation currents observed in the voltammetry as well as increased production of acetate in the FTIR spectra. Acetate is the only product observed at lower potentials. Above the transition potential, where at least some of the areas of the thin layer in the spectroelectrochemical cell become acidic, acetaldehyde, acetic acid, and a small amount of CO2 are produced. This transition potential depends strongly on temperature: -0.1 V at 25 degrees C and -0.4 V at 50 degrees C. The temperature dependence of the production of acetaldehyde and acetic acid strongly suggests that the rate-determining step is the removal of the first proton from the initially adsorbed ethoxide species, and we tentatively suggest that this is also the rate-determining step under alkaline conditions. Overall, our data provide additional support for the mechanism we have developed over a number of publications concerning the oxidation of small alcohols at polycrystalline Pt in alkaline electrolyte.


Publication metadata

Author(s): Christensen PA, Jones SWM

Publication type: Article

Publication status: Published

Journal: Journal of Physical Chemistry C

Year: 2014

Volume: 118

Issue: 51

Pages: 29760-29769

Print publication date: 26/12/2014

Online publication date: 24/11/2014

Acceptance date: 21/11/2014

Date deposited: 11/02/2015

ISSN (print): 1932-7447

ISSN (electronic): 1932-7455

Publisher: American Chemical Society

URL: http://dx.doi.org/10.1021/jp507689d

DOI: 10.1021/jp507689d


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