Kinetics of Electrochemical Reduction of Carbon Dioxide on a Gold Electrode in Phosphate Buffer Solutions

The kinetics of the CO formation by electrochemical reduction of carbon dioxide on a gold electrode investigated in a series of potassium phosphate buffer solutions. CO is the principal product under the above condition. Small amounts of hydrocarbons, such as CH4, C2H4, and C2H6, are detected in the solutions of pH 5.2, 6.2, and 6.8. The Tafel slopes of the partial current density for the CO formation, ICO, at different pH are all ca. −120 mV/decade. The reaction mechanism has been proposed on the basis of the relationships between ICO and the electrode potential and between ICO and the reaction order with respect to CO2, which is ca. 1.