LAUSR

Abstract New catalysts are needed to achieve lower overpotentials and higher faradaic efficiency for desirable products during the electroreduction of CO 2 . In this study, we explore the size-dependence of monodisperse gold-copper alloy nanoparticles (NPs) synthesized by inverse micelle encapsulation as catalysts for CO 2 electroreduction. X-ray spectroscopy revealed that gold-copper alloys were formed and were heavily oxidized in their initial as prepared state. Current density was found to increase significantly for smaller NPs due to the increasing population of strongly binding low coordinated sites on NPs below 5 nm. Product analysis showed formation of H 2 , CO, and CH 4 , with faradaic selectivity showing a minor dependence on size. The selectivity trends observed are assigned to reaction-induced segregation of gold atoms to the particle surface and altered electronic or geometric properties due to alloying.