Abstract
Producing valuable chemicals like ethylene via catalytic carbon monoxide conversion is an important nonpetroleum route. Here we demonstrate an electrochemical route for highly efficient synthesis of multicarbon (C2+) chemicals from CO. We achieve a C2+ partial current density as high as 4.35 ± 0.07 A cm-2 at a low cell voltage of 2.78 ± 0.01 V over a grain boundary-rich Cu nanoparticle catalyst in an alkaline membrane electrode assembly (MEA) electrolyzer, with a C2+ Faradaic efficiency of 87 ± 1% and a CO conversion of 85 ± 3%. Operando Raman spectroscopy and density functional theory calculations reveal that the grain boundaries of Cu nanoparticles facilitate CO adsorption and C - C coupling, thus rationalizing a qualitative trend between C2+ production and grain boundary density. A scale-up demonstration using an electrolyzer stack with five 100 cm2 MEAs achieves high C2+ and ethylene formation rates of 118.9 mmol min-1 and 1.2 L min-1, respectively, at a total current of 400 A (4 A cm-2) with a C2+ Faradaic efficiency of 64%.