Electrochemical Reduction Behavior of Carbon Dioxide on Sintered Zinc Oxide Electrode in Aqueous Solution

• Published in: Denki kagaku oyobi kōgyō butsuri kagaku 2000/04/05, Vol.68(4), pp.257-261
• Main Authors: IKEDA, Shoichiro, HATTORI, Atsushi, MAEDA, Masunobu, ITO, Kaname, NODA, Hidetomo
• Format: Article
• Language: English
• Subjects: Carbon Dioxide; Electroreduction; Potassium Salts; Zinc Oxide
• ISSN: 1344-3542; 2186-2451
• DOI: 10.5796/electrochemistry.68.257

The electrocatalytic properties of a sintered ZnO electrode in electroreduction of CO2 were investigated in aqueous solutions of several potassium salts. The reduction product from CO2 was only CO (faradaic efficiency = 70% at −1.4 V vs. Ag-AgCl in 0.1 mol/dm3 KHCO3 solution) with a considerable amount of H2 as a byproduct. The ZnO was found to have a higher electrocatalytic activity for CO formation than metallic Zn, since the potential showing a maximal faradaic efficiency for CO formation was nobler by 200–250 mV than that of the Zn electrode. The partial current density for CO formation on the ZnO electrode in 0.1 mol/dm3 KH2PO4 solution was 10 to 50 times higher than that on a Zn foil electrode. The sum of the faradaic efficiencies for CO and H2 formation did not reach 100%, the difference from which was attributed to the faradaic efficiency for the reduction of the electrode itself. The metallic Zn thus formed on the electrode surface played no significant role in the electroreduction of CO2.