Membrane-free Electrocatalysis of CO₂ to C₂ on CuO/CeO₂ Nanocomposites

Carbon dioxide electroreduction (CO₂RR) with renewable energy is of great significance to realize carbon neutralization. Traditional electrolysis devices usually need an ion exchange membrane to eliminate the interference of oxygen generated on the anode. Herein, the novel CuO/CeO₂ composite was facilely prepared by anchoring small CuO nanoparticles on the surface of CeO₂ nanocubes. In addition, CuO(002) crystal planes were induced to grow on CeO₂(200), which was preferable for CO₂ adsorption and C-C bond formation. As the catalyst in a membrane-free cell for CO₂RR, the Cu⁺ was stabilized due to strong interactions between copper and ceria to resist the reduction of negative potentials and the oxidation of oxygen from the counter electrode. As a result, a high Faradaic efficiency of 62.2% toward C₂ products (ethylene and ethanol) was achieved for the first time in the membrane-free conditions. This work may set off a new upsurge to drive the industrial application of CO₂RR through membrane-free electrocatalysis.