Electrochemical CO2 Reduction on Copper in Propylene Carbonate: Influence of Water Content and Temperature on the Product Distribution

Aqueous electrolytes are most commonly used for the CO2 reduction reaction (CO2RR), but suffer from a low CO2 solubility that limits the reaction. Electrochemical CO2 reduction in nonaqueous electrolytes can provide a solution, due to the higher CO2 solubility of organic solvent-based electrolytes. Herein, the product distribution of the electrochemical CO2 reduction on polycrystalline Cu in 0.7 m tetraethylammonium chloride in propylene carbonate with different water additions (0, 10, and 90 v%), and for different operating conditions (10, 25, 40, and 60 degrees C), is investigated. It is found that CO2 reduction on Cu in a propylene carbonate solution results in H-2, CO, and formic acid formation only, even though Cu is known to produce C2+ products such as ethylene and ethanol in aqueous electrolytes. Increasing the operating temperature increases the CO2RR kinetics and shows an improvement in CO formation and decrease in H-2 formation. However, increasing the operating temperature also increases water transport through the membrane, resulting in an increase of H-2 formation over time when operating at 60 degrees C.