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

Abstract

Direct conversion of carbon dioxide into multicarbon liquid fuels by the CO ₂ electrochemical reduction reaction (CO ₂RR) can contribute to the decarbonization of the global economy. Here, well‐defined Cu ₂O nanocubes (NCs, 35 nm) uniformly covered with Ag nanoparticles (5 nm) were synthesized. When compared to bare Cu ₂O NCs, the catalyst with 5 at % Ag on Cu ₂O 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 ₂O during CO ₂RR, 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 ₂RR that appear crucial for the C−C coupling and the enhanced yield of liquid products.

Abstract

Cu ₂O nanocubes showed a remarkable increase (30 %) in the Faradaic efficiency for C ₂₊ liquid products after the decoration with Ag nanoparticles. Operando spectroscopy revealed a reaction‐driven redispersion of Ag on CuO _x as well as a certain Cu–Ag miscibility. These changes were coupled with significant variations in the binding of CO to Cu that favored the enhancement of the liquid product yields.