Infrared spectra of CO adsorbed on palladium and platinum electrodes co-existing with another adsorbed species in acidic solution

Abstract

The reflection absorption IR spectra of adsorbed CO on palladium and platinum electrodes were measured to determine the effect of another adsorbate (CS 2 or CCl 4 at 0.4 V (SHE) in perchloric acid solution). For the palladium electrode, the band intensity and frequency of the C-O stretching mode of the adsorbed bridge-type CO changed with the concentration of the other adsorbate, but those of the linear-type CO were independent of the other adsorbate. For the platinum electrode, the band intensity and frequency of the linear-type CO changed with the concentration of the other adsorbate. The frequency shift in the bridge-type CO caused by the adsorption of another species on the palladium electrode could be explained partially by the change in the dipole-dipole coupling between the adsorbed molecules of the bridge-type CO and partially by the shift in the potential of zero charge.