Tandem Electrocatalytic CO₂ Reduction inside a Membrane with Enhanced Selectivity for Ethylene

In this study, electrochemical reduction of carbon dioxide (CO 2 ) is carried out on tandem electrodes consisting of Ag- and Cu-based nanoparticles and a proton-permeable membrane to selectively produce ethylene (C 2 H 4 ) with Faradaic efficiencies up to 80%. We demonstrate that the origin of this high selectivity arises from the tandem architecture utilized. In particular, CO 2 is first reduced to CO on Ag, and the CO is subsequently reduced to C 2 H 4 on the surface of the Cu-based nanoparticles. CO 2 reduction products were quantified, and experiments were carried out as a function of voltage, the membrane overlayer thickness, and the oxidation state of Cu in the nanoparticles. Together, these results lay a framework for the selective production of value-added products from CO 2 reduction using membrane-modified tandem electrocatalysis.