Investigating Enhanced Ethanol Selectivity on Sulfurized Au@Ag NPs for CO₂ Electroreduction by Operando EC‐SERS

Abstract Electrochemical CO 2 reduction powered by sustainable electricity is a strategic pathway for energy conversion and Carbon Neutrality. However, it is still difficult to achieve CO 2 conversion to C 2+ products such as ethanol with high selectivity by electroreduction, while investigating the mechanisms is even difficult. Herein, the enhanced ethanol selectivity on the sulfurized Au core Ag shell nanoparticles (Au@Ag‐S NPs) for CO 2 electroreduction by operando electrochemical surface enhanced Raman spectroscopy (EC‐SERS) is investigated. A high ethanol Faradaic efficiency (FE) of 60% is achieved at a high potential of −0.75 V versus reversible hydrogen electrode (RHE) on Au@Ag‐S NPs for CO 2 electroreduction. The electron transfer from Au core to Ag shell at the Au@Ag‐S NPs interface is proved by X‐ray photoelectron spectroscopy (XPS), which facilitates the CO 2 electroreduction to ethanol. Operando EC‐SERS provides convincing spectral evidence of the *CO intermediates adsorbed and interface water at the surface of Au@Ag‐S NPs, which facilitates subsequent CO‐CO coupling and the formation of ethanol. Density functional theory (DFT) found that ethanol production at the Au@Ag‐S interface is facilitated by the reduced energy barrier of CO‐CO coupling following the sulfurization of Au@Ag NPs. This research provides a practical approach to the efficient design of highly selective catalysts for CO 2 electroreduction to ethanol.