Effect of KHCO₃Concentration on Electrochemical Reduction of CO₂on Copper Electrode

Recently, extensive investigations have been carried out on the electrochemical and photoelectrochemical reductions of CO 2 into hydrocarbons to convert renewable energies into chemical fuels. In these researches, aqueous solutions of bicarbonate salts, such as NaHCO 3 and KHCO 3 , are widely used as the supporting electrolyte. However, the effects of HCO 3 − on the CO 2 reduction have not been studied in detail. In this research, the effects of KHCO 3 concentration on CO 2 reduction were studied at different applied potentials on a Cu working electrode using a potentiostatic method. The concentration of dissolved CO 2 ([CO 2 ]) and ratio of [CO 2 ]/[K + ] in the KHCO 3 solution after bubbling with CO 2 were studied to determine the relationship between KHCO 3 concentration and CO 2 reduction faradaic efficiency. The results suggest that high [CO 2 ]/[K + ] ratio in solutions with low KHCO 3 concentration is probably a key factor to promote CO 2 reduction faradaic efficiency. A model for the effect of [CO 2 ]/[K + ] ratio on CO 2 reduction efficiency was also proposed.