Electrocatalytic activity of Cu electrode in electroreduction of CO2

The electrocatalytic activity of Cu electrode in the electrochemical reduct ion of carbon dioxide (CO2) was investigated. Electroreduction mechanism of CO2 was studied by the adsorption/desorption behaviors of reacting species by using an in-situ electrochemical quartz crystal microbalance. (EQCM) an d the surface changes measured by ex-situ SEM, AES, and XRD analysis. Durin g cathodic reduction of CO2 on Cu, the adsorption of amorphous carbon was o bserved. After electrolysis time of 1 h at constant cathodic potential, the poisoning of amorphous carbon resulted in the decrease of the faradaic eff iciency for the formation of hydrocarbons such as CH4 and C2H4. On the othe r hand, the potential modulation method caused the change of the surface st ructure of copper, i.e. the formation of cuprous oxide (Cu2O). This structu ral change prevented the adsorption of amorphous graphite and the constant production rate of methane was obtained in long-term electrolysis. (C) 2001 Elsevier Science Ltd. All rights reserved.