Electrochemical reduction of CO2 in an aqueous electrolyte employing an iridium/ruthenium‐oxide electrode

Electrochemical reduction of CO2 in an aqueous electrolyte (Briton Robinson buffer, pH = 5.82) was investigated using an Ir/Ru-oxide coating deposited on a titanium substrate, as a function of electrode potential and temperature. The results demonstrated that the Ir/Ru-oxide electrode can efficiently be used for the electrochemical conversion of CO2 into different valuable organic molecules at high faradaic efficiency, 85 % and 96 % at 295 K and 277 K, respectively. Ethanol was found to be the major electrochemical reduction product remained in the liquid phase, with a minor contribution of methanol, acetone and acetaldehyde. The amount of formed products and the corresponding faradaic efficiency were found to be strongly dependent on electrode potential. A maximum in both was obtained at −1.7 V (vs. MSE). At this potential, lowering the reaction temperature from 295 K to 277 K was found to increase the CO2 reduction kinetics only at short electrolysis times, while the corresponding faradaic efficiency increased significantly. The presented work demonstrates that the Ir/Ru-oxide electrode can be considered as a good electrode candidate for the electrochemical conversion of CO2 into usable organic molecules at atmospheric pressure and in aqueous electrolytes.