Electrochemical Reduction of Carbon Dioxide at Various Metal Electrodes in Aqueous Potassium Hydrogen Carbonate Solution

Abstract The electrochemical reduction of carbon dioxide at various metallic electrodes was carried out potentiostatically at 298 K in aqueous potassium hydrogen carbonate solution in order to make clear the electrocatalysis of metals in reduction of CO2. It was found that metals used as electrodes are classified into four groups according to their main products from CO2, i. e., metallic In, Sn, Hg, and Pb are selective for the production of formic acid; metallic Ag and Au are selective for the formation of carbon monoxide; metallic copper has the highest electrocatalytic activities in formation of hydrocarbons, aldehydes, and alcohols; and metallic Al, Ga, Group a, and Group VIII elements except Pd have scarce electrocatalytic activity in reduction of CO2. Effects of the reduction potential on products from CO2 were also examined in detail for Zn, In, and Au electrodes which have some interesting properties.