Effect of Temperature on Electrochemical Reduction of High-Pressure CO₂with In, Sn, and Pb Electrodes

Abstract Electrochemical reduction of high-pressure carbon dioxide with an indium, a tin, and a lead electrode at a potential of −1·8 V versus Ag /AgCl saturated KCl was investigated in the range of 20–100°C. Under optimum experimental conditions, with the indium electrode, about 100% Faraday efficiency formic acid was selectively obtained at 20−60°C, and at 100°C the formation efficiency was 44·5%. With the tin electrode, 99·2% Faraday efficiency formic acid was obtained at 20°C. With increasing temperature, the Faraday efficiency of formic acid decreased and that of hydrogen increased. In the case of the lead electrode, Faraday efficiencies of formic acid and hydrogen were both about 50% at 20°C. A maximum Faraday efficiency of formic acid (91·2%) was obtained at 60°C. Hydrogen formation was lowest at that temperature. For the electrodes, the formation of carbon monoxide was minimal at the temperatures tested.