Potential oscillations in galvanostatic electrooxidation of formic acid on platinum: A time-resolved surface-enhanced infrared study

Gabor Samjeské, Atsushi Miki, Shen Ye, Akira Yamakata, Yoshiharu Mukouyama, Hiroshi Okamoto, Masatoshi Osawa

Research output: Contribution to journalArticlepeer-review

137 Citations (Scopus)

Abstract

The mechanism of temporal potential oscillations that occur during galvanostatic formic acid oxidation on a Pt electrode has been investigated by time-resolved surface-enhanced infrared absorption spectroscopy (SEIRAS). Carbon monoxide (CO) and formate were found to adsorb on the surface and change their coverages synchronously with the temporal potential oscillations. Isotopic solution exchange (from H13COOH to H12COOH) and potential step experiments revealed that the oxidation of formic acid proceeds dominantly through adsorbed formate and the decomposition of formate to CO 2 is the rate-determining step of the reaction. Adsorbed CO blocks the adsorption of formate and also suppresses the decomposition of formate to CO2, which raises the potential to maintain the applied current. The oxidative removal of CO at a high limiting potential increases the coverage of formate and accelerates the decomposition of formate, resulting in a potential drop and leading to the formation of CO. This cycle repeats itself to give the sustained temporal potential oscillations. The oscillatory dynamics can be explained by using a nonlinear rate equation originally proposed to explain the decomposition of formate and acetate on transition metal surfaces in UHV.

Original languageEnglish
Pages (from-to)23509-23516
Number of pages8
JournalJournal of Physical Chemistry B
Volume109
Issue number49
DOIs
Publication statusPublished - 2005 Dec 15
Externally publishedYes

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry
  • Surfaces, Coatings and Films
  • Materials Chemistry

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