Excess Cations Alter *CO Intermediate Configuration and Product Selectivity of Cu in Acidic Electrochemical CO2 Reduction Reaction

High Resolution Image Download MS PowerPoint Slide Concentrated cations are often employed to promote electrochemical CO 2 reduction reaction (CO 2 RR) selectivity in acidic electrolytes. Here, we investigate the influence of excess cations on the *CO adsorption configuration and the product distribution of the CO 2 RR. Operando attenuated total reflectance surface-enhanced infrared absorption spectroscopy (ATR-SEIRAS) reveals that increasing the Cs + concentration shifts the preference of the *CO intermediate on the Cu surface from the atop (*CO atop ) to the bridge (*CO bridge ) configuration. This transition leads to a sharp decline in C–C coupling and an increase in the hydrogen evolution reaction at high Cs + concentrations (0.7 and 1.0 M) under acidic conditions. Time-resolved SEIRAS scans show that *CO atop is kinetically dominant and the proportion of *CO bridge increases gradual…