Electro-oxidation of ethanol on gold: analysis of the reaction products and mechanism

Although the electrocatalytic properties of gold are not as good as those of platinum, the oxidation of small alcohol molecules, such as ethanol, is possible at gold both in acid and alkaline media. By using programmed potential electrolysis coupled with chromatographic analysis of the products formed, the nature and the variation of their concentrations as a function of pH and time have been determined. In alkaline medium, the only product detected was acetic acid. On the other hand, in perchloric acid medium, the reaction products are highly dependent on the value of the oxidation potential, with the following successive steps: ethanol --> acetaldehyde --> acetic acid. A general tentative mechanism is proposed and discussed. (C) 1998 Elsevier Science S.A. All rights reserved.