Programmable Atomic Neighborhoods in Copper Rewire the Oxygenate Pathway to Ethanol

Abstract

Selectively steering the electrochemical CO2 reduction reaction (CO2RR) toward ethanol is an attractive route to sustainable liquid fuels and chemicals, given ethanol’s high volumetric energy density, established logistics, and compatibility with existing value chains. In Cu-based CO2RR, ethanol and ethylene diverge within the multicarbon network, where product routing is jointly governed by active-site arrangement, adsorbate-layer behavior, and the accessibility of partially hydrogenated intermediates, which complicates stable endpoint biasing over broad operating windows. Here, we regulate the local atomic arrangement on a Cu nanowire platform by installing dilute Au–Ag dual-single-atom sites at the Cu surface to construct an asymmetric local coordination field, using a high-loading Au/Ag cluster analogue as the connected-ensemble control. The dual-single-atom configuration delivers ~30% ethanol Faradaic efficiency with ~60% C2+ selectivity and shows a clear shift from ethylene-dominant to ethanol-favored behavior relative to the cluster control. Operando Raman spectroscopy probes the interfacial *CO adlayer through the P2/P1 descriptor from low-frequency Cu–CO modes, indicating a preference for a high-coverage, laterally coupled CO adlayer with increased nearest-neighbor co-occupation. First-principles free-energy profiles further support reduced thermodynamic penalties for water activation and *CO partial hydrogenation to *CHO, together with improved accessibility of oxygenated C2 intermediates. These results establish a structure–selectivity correlation between isolated Au–Ag atomic-neighborhood sites and ethanol-favored CO2RR, providing an atomic-neighborhood engineering strategy for tuning the ethylene–ethanol product balance on Cu-based catalysts.