Electrochemical Reduction of CO2 at Cu Nanocluster/(10(1)over-bar0) ZnO Electrodes

The electrochemical reduction of CO2 in aqueous bicarbonate electrolytes is studied using Cu nanoclusters on single crystal 10 (1) over bar0 ZnO electrodes. Cu is known to generate methane as a primary product in electrochemical reduction reactions while the combination of Cu and ZnO produces methanol in gas-phase synthesis reactions. In reduction experiments at -1.4 V versus Ag/AgCl, gas phase products include hydrogen, carbon monoxide, methane and ethylene and liquid phase products include methanol, ethanol, formate, methyl formate and trace levels of propanol. faradaic efficiencies of Cu/ZnO electrodes are similar relative to Cu electrodes with the exception of alcohols where selectivity is improved by an order or magnitude. In-situ FTIR analysis shows several liquid-phase products along with methoxy and formate adsorbates. The nature of the improved alcohol selectivity and intermediates are considered relative to proposed mechanisms and results from this work. (C) 2013 The Electrochemical Society. All rights reserved.