FORMATION OF HYDROCARBONS IN ELECTROCHEMICAL REDUCTION OF CARBON-MONOXIDE AT AN FE ELECTRODE IN CONNECTION WITH ELECTROCHEMICAL REDUCTION OF CARBON-DIOXIDE

Electrochemical reduction of carbon dioxide and carbon monoxide was studied by coulometric and voltammetric measurements at an Fe electrode. Carbon dioxide was not reduced at Fe, whereas carbon monoxide was reduced to methane, ethylene, and ethane. The current efficiency of hydrocarbon formation amounted to 10%. Voltammetric measurements showed that carbon monoxide is adsorbed on the electrode, and prevents oxidation of Fe. The adsorbed CO is apparently accumulated on the electrode during electrolysis. The adsorbed CO greatly interferes with hydrogen formation, and brings the electrode potential negatively in the constant current electrolysis. The adsorbed CO may be further reduced to hydrocarbons. The adsorbed CO at Fe is partially desorbed by sparging Ar in the electrolyte. Adsorption strength of CO on Fe is partially desorbed by sparging Ar in the electrolyte. Adsorption strength of CO on Fe is intermediate between Cu and Ni, as discussed in connection with the extent of carbon monoxide reduction.