Electrochemical reduction of carbon dioxide at Cu electrode under ultrasonic irradiation

The electrochemical reduction of carbon dioxide under ultrasonic irradiation was investigated with copper electrode in 0.5 M KHCO3 electrolyte. The main products by the electroreduction of CO2 under ultrasonic irradiation were methane, formic acid, and carbon monoxide. The faradaic efficiencies for these products formation under ultrasonic irradiation were better than those without ultrasonic irradiation. In contrast, hydrogen formation was depressed by ultrasonic irradiation. Maximum formation efficiencies for methane, formic acid, CO, and ethylene formations were 40% at -1.9 V and 0 degrees C, 27% at -1.5 V and 0 degrees C, 7.7% at -1.9 V and 15 degrees C, and 3.0% at -1.9 V and 15 degrees C under ultrasonic irradiation, respectively. The formations of methane and CO increased as potential decreased with the decreasing potential. The efficiency curve for ethylene formation had a peak at -1.9 V vs. SCE. The formation efficiencies of methane and CO increased as temperature decreased, but the efficiency for hydrogen formation decreased with temperature decreasing under ultrasonic irradiation. (C) 2000 The Electrochemical Society. S0013-4651(98)11-082-0. All rights reserved.