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

Abstract

Electrochemical CO₂ reduction powered by sustainable electricity is a strategic pathway for energy conversion and Carbon Neutrality. However, it is still difficult to achieve CO₂ conversion to C₂₊ 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 CO₂ 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 CO₂ 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 CO₂ 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 CO₂ electroreduction to ethanol.