Interfacial Water on Ag/Ag₂S Nanowires Enhancing the Ethanol Selectivity for CO₂ Electroreduction.

Abstract

The electrochemical conversion of CO₂ into multicarbon products represents a pivotal yet challenging target, particularly for metal catalysts that predominantly yield C₁ products. Herein, this challenge is addressed through sulfur-induced electronic modulation of Ag-based catalysts, steering the CO₂ reduction pathway toward ethanol production. By constructing atomically engineered Ag/Ag₂S nanowires (NWs) via a controlled sulfurization strategy, a remarkable Faradaic efficiency (FE) of 75% for ethanol at -0.95 V, along with exceptional stability over 14 h of high-performance metrics surpassing most reported Ag-based systems is achieved. Operando electrochemical surface-enhanced Raman spectroscopy (EC-SERS) and density functional theory (DFT) calculations unveil that the Ag/Ag₂S heterointerface synergistically regulates interfacial water networks and stabilizes key ^*CO intermediates, thereby accelerating CO₂ activation, proton-coupled electron transfer, and asymmetric C-C coupling. Furthermore, sulfurization-induced dual effects-optimized hydrogen-bond interactions and enriched K⁺ confinement are identified as critical drivers for tailoring the local microenvironment to favor ethanol selectivity. This work not only demonstrates a rational atomic interface design for C₂ product orientation but also deciphers the dynamic interplay between catalyst electronic structure and interfacial species, offering a molecular-level roadmap for advanced CO₂ conversion systems.