Dynamic electrochemical impedance study of methanol oxidation at Pt at elevated temperatures
Date
2019
Authors
Holm, Thomas
Dahlstrøm, Per Kristian
Sunde, Svein
Seland, Frode
Harrington, David A.
Journal Title
Journal ISSN
Volume Title
Publisher
Electrochimica Acta
Abstract
The methanol oxidation reaction (MOR) is studied at temperatures up to 140 °C by a combination of cyclic voltammetry, chronoamperometry, and dynamic electrochemical impedance spectroscopy (dEIS). A mechanistic analysis of the reaction is done based on the Tafel relation, the calculated activation energy, and the fitting of dEIS data. At the fuel cell relevant potentials, 0–0.80 V vs RHE, the MOR mechanism is similar at all temperatures. The rate-determining step is the adsorption of water at low overpotentials (< 0.50 V vs RHE), a combination of the methanol adsorption reaction and the surface reaction between adsorbed CO and OH at intermediate potentials (0.50–0.65 V vs RHE), and the methanol adsorption reaction at high potentials (> 0.65 V vs RHE). The shoulder on the oxidation peak at 0.60–0.65 V vs RHE corresponds well with where the CO coverage approaches zero.
Description
Keywords
Electrochemical impedance spectroscopy, Methanol oxidation, Temperature, Reaction mechanism
Citation
Holm, T., Dahlstrøm, R.K., Sunde, S., Seland, F. & Harrington, D.A. (2019). Dynamic electrochemical impedance study of methanol oxidation at Pt at elevated temperatures. Electrochimica Acta, 295, 139-147. https://doi.org/10.1016/j.electacta.2018.10.071