THE ELECTROCHEMICAL REDUCTION OF CO2 TO CH4 AND C2H4 AT Cu/NAFION ELECTRODES (SOLID POLYMER ELECTROLYTE STRUCTURES)

The construction of copper/Nation electrodes (solid polymer electrolyte structures) by an electroless plating method is described. These electrodes were used for the gas phase electrochemical reduction of CO2 to hydrocarbon products, including CH4 and C2H4. The faradaic efficiencies of the electrodes under ambient conditions with a counter solution of 1 mM H2SO4 at a potential of -2.00 V vs. SCE reached a steady-state value of about 20% after 30 rain of electrolysis. This corresponded to a rate of total hydrocarbon production of approximately 9.8 x 10(-7) mole h(-1) cm(-2). Increasing the potential of the electrode to more negative potentials, or increasing the proton concentration of the counter solution, caused a decrease in the faradaic efticiencies due to a relative increase in the rate of proton reduction vs. that of CO2 reduction. If the proton concentration of the counter solution was decreased to an alkaline pH, hydrocarbon production quickly ceased because of proton starvation.