Use of gas-diffusion electrodes for high-rate electrochemical reduction of carbon dioxide. I. Reduction at lead, indium- and tin-impregnated electrodes

Abstract

The use of metal-impregnated polytetrafluoroethylene-bonded carbon gas-diffusion electrodes for the electrochemical reduction of carbon dioxide in aqueous solution has been investigated over a wide range of pH (1 to 5). High rates of reduction of carbon dioxide to formic acid were demonstrated. Lead-impregnated electrodes operated at 115 mA cm−2 in an aqueous acidic electrolyte (pH 2) selectively produced formic acid with a current efficiency of nearly 100% at aniR-corrected potential of approximately −1.8V versus saturated calomel electrode. Electrodes impregnated with either indium or tin produced formic acid at rates comparable with those containing lead. However, in addition to formic acid, small quantities of carbon monoxide were also produced and the simultaneous production of hydrogen by the reduction of water was more significant. Thus, it appears that the electrocatalytic activity for the electrochemical reduction of carbon dioxide to formic acid is lead>indium∼tin.