Electrochemical Reduction Of Carbon Dioxide Using Gas Diffusion Electrodes Loaded With Fine Catalysts

Gas diffusion electrodes (GDEs) promising to use electrochemical reaction of gases at higher rates such as in fuel cells were used for CO2 electro-reduction. Cu powder, Cu and ZnO mixed powder, and CuO/ZnO mixed oxides were examined as the catalysts. The reduction products with Cu-GDEs in K2SO4 aq. soln. were CH4, C2H4, C2H5OH, CO, HCOO-, etc. The purer and the smaller particle size of the Cu powder, it shows the higher activity and efficiency for CO and hydrocarbons formation. CO2 reduction can be carried out ca. 100 times greater rate using a GDE than that with a Cu-foil electrode. With GDEs of CuO/ZnO = 3/7, the main product was C2H5OH with an efficiency of 17% with selectivity of 88% at -1.32 V. With GDEs of Cu/ZnO = 3/7 reduced by H-2, the selectivity became poorer due to additional production of n-C3H7OH and C2H4, although the total efficiencies for CO2 reduction became 41% at -1.30 V.