Infrared spectra of carbon monoxide adsorbed on a smooth gold electrode

• DOI: 10.1016/0022-0728(86)87078-4
• Publication Date: 2002-07-25T10:25:47Z
• Authors: K. Kunimatsu; A. Aramata; N. Nakajima; H. Kita
• Keywords: 01 natural sciences; 0104 chemical sciences

Infrared spectra of CO adsorbed on a gold electrode in 1 M HClo4, 0.2 M NaOH and 0.2 M (CH3)4NOH have confirmed that the adsorption is greatly enhanced in the alkaline solutions compared to the acidic solution. The enhanced adsorption is apparently assisted by OH− ions while there is little effect from the alkali metal ions. The adsorption reaches a maximum around −0.1 V (RHE). The CO stretching frequency at a constant potential shifts to lower frequencies by ca. 50–60 cm −1 with the decrease of CO coverage. The observed frequency shift with coverage is opposite in nature to that found in the gas phase for the Au/CO system. Oxidation of the CO layer established initially at –0.1 V, proceeds randomly in the adsorbed layer from ca. 0.7 V, giving rise to a steep decrease of the intensity of the CO stretching band with a concomitant large shift of the CO stretching frequency to lower wavenumbers. The potential dependence of the CO stretching frequency is linear, 64 cm−1/V, both in the acidic and alkaline solutions, between −1.1 V and +0.7 V(SHE). The infrared frequencies of the CO stretching vibration are lower that the frequencies observed by SERS (surface-enhanced Raman spectroscopy) by more than 50 cm−1