Gas-fed zero-gap electrolyzers have recently emerged as attractive systems for limiting ohmic losses and costs associated with electrolytes and for optimizing energy efficiencies. Here, we report that using a dendritic Cu oxide (D-CuO) material deposited on a gas diffusion layer as the cathode of a gas-fed zero-gap membrane electrode assembly (MEA) system results in a very selective conversion of CO to ethylene. More specifically, CO reduction yielded ethylene with an FE up to 68% at 100-125 mA·cm-2 with H2 as the only other gaseous product and the electrolysis could be carried out for several hours with good stability. Ethylene was also the major product during CO2 electrolysis (FE = 41%) at 125-150 mA·cm-2, reflecting the high selectivity of D-CuO for ethylene production. Such systems are relevant for tandem CO2 electroreduction processes, allowing energy efficiencies above 30%.
Keywords: CO reduction; CO2 reduction; dendritic Cu oxide; electrocatalysis; membrane electrode assembly.