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Abstract

Direct conversion of carbon dioxide into multicarbon liquid fuels by the CO₂ electrochemical reduction reaction (CO₂RR) can contribute to the decarbonization of the global economy. Here, well‐defined Cu₂O nanocubes (NCs, 35 nm) uniformly covered with Ag nanoparticles (5 nm) were synthesized. When compared to bare Cu₂O NCs, the catalyst with 5 at% Ag on Cu₂O NCs displayed a two‐fold increase in the Faradaic efficiency for C₂₊ liquid products (30% at ‐1.0 V_RHE), including ethanol, 1‐propanol, and acetaldehyde, while formate and hydrogen were suppressed. Operando X‐ray absorption spectroscopy revealed the partial reduction of Cu₂O during CO₂RR, accompanied by a reaction‐driven redispersion of Ag on the CuO_x NCs. Operando surface‐enhanced Raman spectroscopy data further uncovered significant variations in the CO binding to Cu, which were assigned to Ag‐Cu sites formed during CO₂RR that appear crucial for the C‐C coupling and the enhanced yield of liquid products.