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In Situ, Time-Resolved Reflectance Spectroscopy in the Microsecond Domain:  Oxidation of Adsorbed Carbon Monoxide on Polycrystalline Pt Microelectrodes in Aqueous Solutions

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journal contribution
posted on 05.12.2006, 00:00 by Ping Shi, Iosif Fromondi, Daniel A. Scherson
The dynamics of the electrooxidation of adsorbed CO, COads, on polycrystalline Pt microelectrodes has been examined in CO-saturated 0.5 M H2SO4 and 0.5 M HClO4 aqueous solutions, using in situ, time-resolved, normalized differential reflectance spectroscopy (λ = 633 nm). Attention was focused on the unique dependence of COads oxidation on the potential at which the adsorbed full CO monolayer is assembled (i.e., hydrogen adsorption/desorption vs the double-layer region) using both fast linear scan voltammetry and potential step techniques. As evidenced from the data collected, COads oxidation at a fixed potential proceeds at slower rates when the monolayer is formed in the double- layer region compared to when it is formed in the hydrogen adsorption/desorption region. Possible explanations for this effect are discussed.