The influence of surface defects in methanol dissociative adsorption and CO oxidation on Pt(110) probed by nonlinear vibrational SFG spectroscopy

• Published in: Journal of electroanalytical chemistry (Lausanne, Switzerland) Vol. 672; pp. 1 - 6
• Main Authors: Vidal, F., Tadjeddine, A., Humbert, C., Dreesen, L., Peremans, A., Thiry, P.A., Busson, B.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01-05-2012; Elsevier
• Subjects: adsorption; Carbon monoxide; Chemical Physics; Chemical Sciences; Condensed Matter; electrodes; Methanol; Optics; or physical chemistry; oxidation; Physics; Platinum; SFG; spectroscopy; terraces; Theoretical and; Carbon monoxide; Platinum; SFG; Methanol
• ISSN: 1572-6657; 1873-2569
• DOI: 10.1016/j.jelechem.2012.03.004

► Methanol oxidation on ordered and defective Pt(110) surfaces was studied using SFG spectroscopy. ► Comparison of spectral data allows to evidence the role of surface defects. ► CO oxidation occurs preferentially at defects sites.
We report the study of methanol electro-oxidation on ordered and defective Pt(110) surfaces using infrared-visible sum-frequency generation vibrational spectroscopy in the COads internal stretch spectral region (1700–2150cm−1). Comparison of the spectra as a function of the structural quality of the electrodes and of the applied potential shows that: (i) dissociative chemisorption occurs primarily at low potentials on defect sites such as steps and (ii) the signal of CO adsorbed on terraces decreases more sharply at higher potentials than the signal of CO adsorbed on defects. This latter behavior appears to contradict the fact that dense CO adlayers on terraces block the oxidation process. This apparent paradox is solved by considering the interplay of preferential oxidation of CO at defects sites and transfer of adsorbed CO from terraces reservoir to defects.