Converting CO2 to ethanol on Ag nanowires with high selectivity investigated by operando Raman spectroscopy

Electrochemical conversion of CO2 into liquid fuels provides an efficient way to store the renewable energy in the production of fuels and chemicals. However, effectively converting CO2 to ethanol remains extremely challenging due to the low activity and selectivity. Herein, we achieve a high ethanol Faradaic efficiency (FE) as high as 85% on Ag nanowires (NWs) for CO2 electroreduction at -0.95 V. X-ray photoelectron spectroscopy and electrochemical experiments prove that such Ag NWs are partially oxidized. Operando Raman spectroscopy finds the important CO intermediate adsorbed on partially oxidized Ag NWs, facilitating the ethanol formation. Density functional theory calculations prove that the reaction energy of CO coupling with the *CHO to *COCHO intermediate on the partially oxidized Ag NWs is smaller than that on the surface of Cu, which explains why the ethanol FE of such partially oxidized Ag NWs can exceed that of Cu, and therefore is the most favorable pathway for the formation of C-2 products on partially oxidized Ag NWs. This study provides a new insight to design efficient catalysts and investigate the mechanisms to improve the selectivity.

Automated summary

Electrochemical conversion of CO2 into liquid fuels is an efficient way to store renewable energy, but converting CO2 to ethanol remains challenging due to low activity and selectivity. This study demonstrates that partially oxidized Ag nanowires can achieve a high Faradaic efficiency of 85% for CO2 electroreduction, surpassing Cu. The presence of CO intermediates on the partially oxidized Ag nanowires promotes ethanol formation.