Operando Investigation of Ag‐Decorated Cu(2)O Nanocube Catalysts with Enhanced CO(2) Electroreduction toward Liquid Products

Direct conversion of carbon dioxide into multicarbon liquid fuels by the CO(2) electrochemical reduction reaction (CO(2)RR) can contribute to the decarbonization of the global economy. Here, well‐defined Cu(2)O nanocubes (NCs, 35 nm) uniformly covered with Ag nanoparticles (5 nm) were synthesized. When compared to bare Cu(2)O NCs, the catalyst with 5 at % Ag on Cu(2)O NCs displayed a two‐fold increase in the Faradaic efficiency for C(2+) 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 Cu(2)O during CO(2)RR, accompanied by a reaction‐driven redispersion of Ag on the CuO(x) NCs. Data from operando surface‐enhanced Raman spectroscopy further uncovered significant variations in the CO binding to Cu, which were assigned to Ag−Cu sites formed during CO(2)RR that appear crucial for the C−C coupling and the enhanced yield of liquid products.