A Study of Adsorption and Oxidation of Carbon Monoxide on Platinum Using Constant Current Pulses

Abstract

Using single anodic constant‐current pulses, the steady‐state concentration of carbon monoxide already adsorbed on the surface of a bright Pt electrode in and the additional amount of adsorbed during the application of the pulse has been determined. At potentials of 0.3–0.4v (NHE), surface coverage of one molecule of per surface Pt atom was observed at very low partial pressures; for partial pressures up to 1 atm the coverage increased to about 1.06 molecules per Pt atom, indicating that additional physically adsorbs on the base chemisorbed layer. At 1.0–1.3v the rate of adsorption of was slower than the rate of diffusion (25°C), and indirect evidence suggests that is not adsorbed at potentials above 1.3v. The mechanism of oxidation of appears to be an electrochemical oxidation of water to form chemisorbed oxygen atoms, which then rapidly react with chemisorbed to form .