Molecular Scale Interfacial Water Management Switching Reaction Pathway of Carbon Dioxide Electroreduction.

The electrochemical carbon dioxide reduction reaction (eCO2RR) involves numerous intermediates and simultaneous interactions between these intermediates and water (H2O) molecules. Although extensive research has focused on stabilizing the carbon-related intermediates, limited attention has been paid to investigating the local regulations of H2O molecules at molecular level. Considering the electrocatalytic interface, H2O is critical during CO2RR process, as H2O molecules are directly involved in CO2 reduction process or indirectly modify the solid-liquid interfacial structure, thereby impacting the reaction process. In this study, we use a model copper-based catalyst, containing palladium and indium dopants that have different hydrogen and oxygen adsorption capabilities, to investigate the influence of H2O molecules on CO2 electroreduction selectivity. We find, by enhancing the participation of isolated H2O molecules, instead of asymmetric H-bonded H2O or ice-like H2O, in the local electrocatalytic microenvironment during CO2 reduction process, that the cathodic products remarkably change from 95% C1 FE to 70% C2 FE. We unveil, via in-situ ATR-SEIRAS measurement, that the H2O microenvironment regulation can promote the formation of key intermediates, thus tuning the CO2 reduction pathways.