Pulse-mode electrochemical reduction of carbon dioxide using copper and copper oxide electrodes for selective ethylene formation

摘要

Although the electrochemical reduction of CO₂ at a copper electrode produces hydrocarbons, the activity for the conversion of CO₂ is significantly reduced after several tens of minutes by the deposition of poisoning species on the electrode. In order to solve the poisoning species problem, the electrochemical reduction of CO₂ was carried out using a copper electrode in the pulse electrolysis mode by anodic as well as cathodic polarization. The anodic polarization intervals suppressed the deposition of the poisoning species on the electrode, and the amount of two hydrocarbons produced, CH₄ and C₂H₆, decreased only slightly even after one hour. By choosing the appropriate anodic potential and time duration the selectivity for C₂H₆ formation was significantly enhanced. The enhancement was found to be due to the copper oxide formed on the copper electrode. The selectivity was further improved when the electrochemical reduction was carried out using a copper oxide electrode. The highest efficiency of about 28% was obtained at −3.15 V.