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In situ infrared spectroscopy of well-defined single-crystal electrodes: adsorption and electrooxidation of CO on Pt(111)

Journal Article · · J. Phys. Chem.; (United States)
DOI:https://doi.org/10.1021/j100335a029· OSTI ID:6186699
; ;
Surface infrared spectra have been obtained for carbon monoxide adsorbed on an ordered Pt(111) crystal in 0.1 M HClO/sub 4/ and other acidic electrolytes as a function of CO coverage as well as electrode potential. Variations in the CO coverage, theta, were made by partial electrooxidation; theta was evaluated from the quantity of CO/sub 2/ product produced as measured from the 2343-cm/sup /minus/-1/ infrared band absorbance combined with the anodic voltammetric charge. The potential-dependent surface infrared spectra exhibited a major ..nu../sub CO/ band at 2050-2075 cm/sup /minus/1/ due to linearly bound CO, the peak frequency increasing approximately linearly with both increasing coverage and potential. An additional band at 1830-1850 cm/sup /minus/1/, due to bridge-bound CO, was also observed. The relative intensities of the bridged and linear ..nu../sub CO/ forms, I/sub b/, I/sub l/, depend somewhat on theta, the largest intensity ratios, I/sub b//I/sub l/ /approximately/ 0.2-0.3, being observed for 0.4 /approx lt/ theta /approx lt/ 0.5. In contrast to the behavior of the analogous gas-phase system, the integrated intensity of the linear ..nu../sub CO/ band is proportional to theta throughout the accessible coverage range (theta less than or equal to 0.62). The disordered Pt(111) surface formed by repeated voltammetric cycling into the anodic oxide region yielded a linear ..nu../sub CO/ band upshifted by ca. 10 cm/sup /minus/1/. While the changes in the ..nu../sub CO/ frequency during potentiostatic CO electrooxidation on ordered Pt(111) are independent of the oxidation rates, the disordered surface (as well as polycrystalline Pt) exhibited ..nu../sub CO/ frequency decreases under these conditions that were substantially more pronounced for longer oxidation time scales (/approx gt/ 20 s).
Research Organization:
Purdue Univ., West Lafayette, IN (USA)
OSTI ID:
6186699
Journal Information:
J. Phys. Chem.; (United States), Journal Name: J. Phys. Chem.; (United States) Vol. 92:24; ISSN JPCHA
Country of Publication:
United States
Language:
English

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Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400400* -- Electrochemistry
ABSORPTION SPECTROSCOPY
ADSORPTION
CARBON COMPOUNDS
CARBON MONOXIDE
CARBON OXIDES
CHALCOGENIDES
CHEMICAL REACTIONS
CHEMISTRY
CRYSTALS
DATA
ELECTROCHEMISTRY
ELECTRODES
ELEMENTS
ENERGY LEVELS
EXCITED STATES
EXPERIMENTAL DATA
INFORMATION
INFRARED SPECTRA
METALS
MILLER INDICES
MONOCRYSTALS
NUMERICAL DATA
OXIDATION
OXIDES
OXYGEN COMPOUNDS
PLATINUM
PLATINUM METALS
SORPTION
SPECTRA
SPECTROSCOPY
TRANSITION ELEMENTS
VIBRATIONAL STATES