The vibrational spectrum of carbon monoxide at the Pt/acetonitrile interface as a function of applied potential has been investigated using the surface-enhancedRamanspectroscopy technique. The electrolyte is 0.1 M LiClO4. The bands observed at ca. 506 and 2055 cm-1 are attributed to the platinum-CO (Pt-C) and intramolecular C-O (C-O) stretching vibrations, respectively, suggesting linearly adsorbed CO on platinum. The (Pt-C) band has an experimental Stark tuning rate of-4 cm-1/V, while the slope of (C-O) band frequency versus potential approaches zero before the onset of electro-oxidation ofCOads, possibly resulting from low surface coverage ofCOon platinum. The roughened Pt electrode surface has a high electrocatalytic activity, on whichCOelectro-oxidation occurs at ca.-0.7V(vs Ag/Ag+). The main product ofCOads oxidation is confirmed to be carbonate due to the existence of trace water in the double-layer region as a source of oxygen for the reaction. It has also been found that the solvent acetonitrile can exert a chemisorbed decomposition reaction on the roughened Pt surface, while the adsorption of CO can significantly inhibit this reaction.

Surface-enhanced Raman scattering (SERS) spectra of pyridine adsorbed onto bare platinum and nickel electrodes in nonaqueous solutions are reported in this Letter. There are similarities and differences between the SERS from aqueous and nonaqueous solutions. The surface enhancement factor for platinum in acetonitrile solution has been calculated to decrease by a factor of ca. 10 compared with that in the aqueous media. The double-band character for the ring breathing mode is observed at 1009 and 1019cm-1. Two adsorption modes of pyridine on the platinum surface were assumed. Part of the pyridine molecules may be chemisorbed onto the surface, with the ring plane oriented vertical to the surface; other pyridine molecules may co-adsorb with lithium cations onto the surface.

Surface-enhanced Raman scattering from a silver electrode in solution of 0.1 M LiClO4 in acetonitrile has been analyzed as a function of applied potential. Three m (O-H) bands associated with the interfacial water and two m (O-H) bands associated with the OH ion species were observed depending on the electrode potential. The band at 3487cm 1 is favored at relatively positive potentials and assigned to H2O molecules interacting with the electrode surface via the oxygen atoms. Another band at 3586cm 1 appears in a wider potential region and is assigned to the H2O molecules with one or both of the hydrogen atoms facing the electrode surface. Additionally, evidence for the possible surface ion pair, Li

The vibrational spectrum of carbon monoxide, exerted by dissociation of formic aid, has been investigated at the platinum electrode as a function of applied potential by using the surface-enhanced Raman spectroscopy (SERS) technique. The electrolyte is 0.1M LiClO4. Two typical SERS features observed at 475-490 and 2055-2080 cm-1 are attributed to the platinum-CO (Pt-C) and intramolecular C-O (C-O) stretching vibration, respectively, indicating linearly adsorbed CO on platinum. Comparisons of the present data with previous studies in aqueous solutions show that solution components, particularly the dielectric in the inner double layer, may significantly influence the interaction of CO with platinum, especially the CO intramolecular mode. Electrooxidation of CO was observed to occur at potentials more positive than 0.6 V, being slightly negative relative to previous studies for CO on smooth platinum, suggestive of a higher electrocatalytic activity for the present highly roughened platinum surface. At positive and moderately negative potentials (-0.2 to 0.6 V), the Pt-C and CO intramolecular bands exhibit opposite frequency changes with decreasing potential, with Stark tuning rate being -6 and 24 cm-1/V, respectively. At more negative potentials, both

Using confocal Raman microscopy, potential dependent surface-enhanced Raman spectra (SERS) of pyridine adsorbed on a bare zinc (Zn) bulk electrode were observed for the first time, and the adsorption behavior of pyridine on zinc was discussed. An electrochemical oxidation-reduction method was employed to roughen Zn electrodes for creating SERS. Related SEM measurement was performed to obtain the morphological information of the roughened electrode for understanding the SERS mechanism on it. An enhancement factor of around two orders of magnitude for pyridine adsorbed on a roughened Zn electrode was estimated.