Open Circuit Interaction Between Ethanol or 2-Propanol and Oxidized Platinum Surfaces.

Abstract

The interaction between organic molecules and oxidized catalyst surfaces has been used to study the fuel crossover from the anode to the cathode in direct liquid fuel cells. In such experiments, the oxidized surface is put in contact with the fuel under open circuit conditions, and the potential is registered. The open circuit potential (OCP)can then inform on the reactivity of the fuel with the oxidized surface and provide valuable information.Hereinwe present an experimental investigation of the OC interaction between ethanol or 2-propanol with oxidized platinum surfaces. Besides the OCP, we have also employed cyclic voltammetry and fast oxide reduction sweep in the presence of the alcohols. Comparable reaction currents are obtained in the voltammogram, but the electro-oxidation of 2-propanol sets in at considerably lower overpotentials than that of ethanol. At the high potential region, both the magnitude and the potential of the current peak are nearly identical in both cases. Under open circuit conditions, the interaction of ethanol with the oxidized platinum surface is more pronounced than that found for 2-propanol, and these results are corroborated by the facile reduction of the platinum oxides along the fast backward sweep for the latter.