Chemical Resistance and Catalytic Activity of Copper in the Process of Electrooxidation of Ethanol in Strong Alkaline Media

Abstract

The possibility of using copper (Cu) as a catalyst in nonflowing membraneless alkaline fuel cells was investigated. In the present study, the interface between two immiscible liquids served as a virtual membrane. We studied two immiscible liquid systems: Ethanol+K3PO4+H2O (No. 1 electrolyte) and Ethanol+KOH+H2O (No. 2 electrolyte). Cyclic voltammetry, pulse chronoamperometry, and gas-liquid chromatography were used to study the corrosion resistance and catalytic activity of ethanol oxidation on Cu. Analyses of chromatograms obtained after charging and discharging the fuel cells revealed the presence of ethanol oxidation products, mainly in the form of acetaldehyde, which indicates the predominant mechanism of C2 oxidation of ethanol in the studied system. That is, with the release of two and four electrons during the oxidation of alcohol and the formation of acetaldehyde and acetic acid. Anodic currents of Cu dissolution in No. 1 electrolyte were an order of magnitude lower than in the No. 2 electrolyte. The catalytic activity of Cu during the oxidation of ethyl alcohol EtOH in the electrolyte with potassium hydroxide was at least five times higher than in the electrolyte with potassium phosphates, at almost the same pH values. The surface compounds on the Cu electrode in the first electrolyte were composed mainly of monovalent and bivalent Cu compounds, whereas they were composed of trivalent Cu compounds in the second electrolyte. Thus, the possibility of using Cu as a catalyst for the oxidation of EtOH in alkaline nonflowing membraneless fuel cells has been established. To further increase the catalytic activity of Cu and expand its commercial attractiveness as a catalyst, further research is needed to optimize its composition and structure and create bimetallic and multimetallic Cu-based electrodes, including nanostructured ones.

Keywords

• copper
• ethanol fuel cells
• membraneless