Electrochemical Carbon Dioxide Reduction in Methanol at Cu and Cu2O-Deposited Carbon Black Electrodes

The electrochemical reduction of carbon dioxide in methanol was investigated with Cu and Cu2O-supported carbon black (Vulcan XC-72) nanoparticle electrodes. Herein, Cu or a Cu2O-deposited carbon black catalyst has been synthesized by the reduction method for a Cu ion, and the drop-casting method was applied for the fabrication of a modified carbon black electrode. A catalyst ink solution was fabricated by dispersing the catalyst particles, and the catalyst ink was added onto the carbon plate. The pH of suspension was effective for controlling the Cu species for the metallic copper and the Cu2O species deposited on the carbon black. Without the deposition of Cu, only CO and methyl formate were produced in the electrochemical CO2 reduction, and the production of hydrocarbons could be scarcely observed. In contrast, hydrocarbons were formed by using Cu or Cu2O-deposited carbon black electrodes. The maximum Faraday efficiency of hydrocarbons was 40.3% (26.9% of methane and 13.4% of ethylene) at -1.9 V on the Cu2O-deposited carbon black catalyst. On the contrary, hydrogen evolution could be depressed to 34.7% under the condition.