Improved electrochemical conversion of CO2 to multicarbon products by using molecular doping

Abstract The conversion of CO2 into desirable multicarbon products such as ethylene and ethanol via the carbon dioxide reduction reaction (CO2RR) hold promise to achieve a circular carbon economy. The develop of such a technology is currently hampered by the lack of catalysts, which can drive the reaction at industrially relevant current densities with high efficiency and selectivity. Here, we report a novel strategy for increasing the conversion of CO2 into hydrocarbon molecules with two or more carbon atoms (C2+) by modifying the surface of bimetallic silver-copper (Ag-Cu) catalyst with aromatic heterocycles such as thiadiazole and triazole derivatives. By combining operando Raman and X-ray absorption spectroscopy with electrocatalytic measurements and analysis of the reaction products, we identified that the electron withdrawing nature of functional groups orients the reaction pathway towards the production of C2+ species such as ethanol and ethylene and enhances the reaction rates on the surface of the catalyst. As a result, we achieve a maximum Faradaic efficiency for the formation of C2+ of ≈ 80% and full-cell energy efficiency of 20.3% with a specific current density of 261.4 mA cm-2 for C2+ using functionalized Ag-Cu electrodes, compared to only 33.8% and 70.6 mA cm-2 for the pristine Ag-Cu electrodes. We anticipate that our strategy can further be extended in order to improve the selectivity of the reaction towards the production of specific multicarbon molecules.