REACTIVE AND INHIBITING ADSORBATES FOR THE CATALYTIC ELECTROOXIDATION OF CARBON-MONOXIDE ON GOLD (210) AS CHARACTERIZED BY SURFACE INFRARED-SPECTROSCOPY

Potential-dependent sequences of surface infrared spectra have been obtained during the voltammetric electrooxidation of solution carbon monoxide on ordered Au(210), in acidic, neutral, and alkaline aqueous media. Under optimal catalytic conditions, only a reactive form of adsorbed CO is detected, yielding a C-O stretching frequency (upsilon-CO) at 2100-2115 cm-1. The occurrence of reaction inhibition is accompanied by the displacement of this adsorbate by a lower upsilon-CO form, located at 1900-2000 cm-1, its appearance being favored by increasing surface exposure time and more negative dosing potentials. The mechanistic implications of such combined real-time infrared/voltammetric results are noted.