Comparative study of CO adsorbed on Pt, Pd, Au and Ag electrodes in neutral solution by IR reflection absorption spectroscopy

Abstract

The vibrational spectra of carbon monoxide adsorbed on Pt, Pd, Au and Ag electrodes were investigated in the double-layer region in a solution of 0.1 M NaC1O 4 using in situ polarization modulated infrared reflection absorption spectroscopy. Linearly adsorbed CO on the Ag electrode was observed with a relatively strong band intensity. For the Au electrode, three absorption bands were observed in the CO-stretching frequency region, and these were assigned to linearly adsorbed CO, two-fold bonded CO and three-fold bonded CO at increasingly higher frequencies. The band intensities and band positions of CO adsorbed on the Pt and Pd electrodes were similar to those in acidic solution (K. Kunimatsu, W.O. Golden, H. Seki and M.R. Philpott, Langmuir, 1 (1985) 245: K. Kunimatsu, H. Seki, W.G. Golden, J.G. Golden II and M.R. Philpott, Surf. Sci. 158 (1985) 596). All of the frequency shifts in the band of the linear CO adsorbed on these electrodes were about 50 cm −1/V. For the Pt electrode, the bridged CO was transformed reversibly into linear CO with a change of the electrode potential.