Characterizing electrocatalytic surfaces: Electrochemical and NMR studies of methanol and carbon monoxide on Pt/C

Characterizing electrocatalytic surfaces: Electrochemical and NMR studies of methanol and carbon monoxide on Pt/C

TitleCharacterizing electrocatalytic surfaces: Electrochemical and NMR studies of methanol and carbon monoxide on Pt/C
Publication TypeJournal Article
Year of Publication2007
AuthorsPatrick McGrath, Aurora Marie Fojas, Benjamin M Rush, Jeffrey A Reimer, Elton J Cairns
JournalElectrochimica Acta
Volume53
1365
Issue3
Pagination1365-1371
Date Published12/2007
Keywordsadsorption, carbon monoxide, electrocatalysis, methanol, pt/c electrocatalyst
Abstract

We use cyclic voltammetry (CV) on fuel cell electrodes to elucidate the important differences between adsorbates resulting from carbon monoxide adsorption and methanol adsorption onto commercial Pt/C electrocatalysts in a sulfuric acid electrolyte. Under open circuit conditions, methanol was found to adsorb preferentially onto the Pt sites associated with “strongly bound” hydrogen. The sites associated with “weakly bound” hydrogen adsorbed methanol more slowly. In the case of CO adsorption, which requires no adsorbate dehydrogenation, all adsorption sites showed similar affinity towards the adsorbate. Electrochemical oxidation of the adsorbates derived from both methanol and CO exposure exhibit slower oxidation when the adsorbate is associated with cubic-packed-like sites than from close-packed-steps and other sites. NMR of a 13CO-adlayer prepared by electrochemical adsorption from low concentration 13CH3OH shows a lower NMR shift and smaller linewidth than the previously reported values for electrochemically adsorbed 13CO gas. These results are interpreted in terms of adsorbate motion on the electrocatalyst surface.

DOI10.1016/j.electacta.2007.05.035