LAUSR

Silver (Ag) catalysts enable high selectivity (>90%) in CO2-to-CO conversion at >100 mA cm −2; gold (Au) catalysts are active at lower overpotential, but with lower selectivity (<80%). Here we present an adparticle-functionalized catalyst that combines the benefits of each by uniting Au adparticles on the AgAu interface. Au adparticles modify the lattice and electronic structure of Ag and lower the free energy change required to form *COOH. We demonstrate selective and low-overpotential CO2-toCO conversion at >490 mA cm−2 in a flow cell. In a membrane electrode assembly, the catalyst achieves 90% CO selectivity and 33% CO energy efficiency over 60 h.