Electrocatalytic CO2 Reduction in Acetonitrile Enhanced by the Local Environment and Mass Transport of H2O

Understanding and engineering electrochemical environments often come secondary to electrocatalyst design when optimizing the activity and selectivity of electrocatalytic molecular transformations. In this study, we employ electrocatalytic CO2 reduction in acetonitrile on nanoscale-roughened Ag catalysts as a model system and operando surfaceenhanced Raman scattering spectroscopy to demonstrate that the local environment of H2O affects proton-coupled electrochemical reactions. We show that an electrolyte that has absorbed ca. 4.3 wt % H2O from air provides a unique environment for H2O which alters the electrochemical activity and enhances the production of CO surface intermediates at potentials as low as -1.0 V vs Ag/Ag+. We also provide evidence that electrolytes can act as a carrier for H2O molecules, enhancing the mass transport of H2O to the electrode surface in this unique environment. Our results highlight that the local environment of H2O can be used to improve the activity and selectivity of proton-coupled electrochemical reactions.

Automated summary

In this study, the influence of the local environment of H2O on proton-coupled electrochemical reactions was investigated using electrocatalytic CO2 reduction on nanoscale-roughened Ag catalysts as a model system. The results showed that an electrolyte with absorbed H2O could alter the electrochemical activity and enhance the production of CO surface intermediates. It was also found that electrolytes could act as carriers for H2O molecules, enhancing the mass transport of H2O to the electrode surface. These findings highlight the importance of the local environment of H2O in improving the activity and selectivity of proton-coupled electrochemical reactions.