Approaching 100% Selectivity at Low Potential on Ag for Electrochemical CO₂ Reduction to CO Using a Surface Additive

We report the discovery of a quaternary ammonium surface additive for CO2 reduction on Ag surfaces that changes Faradaic efficiency CO from 25% foil to 97%, while increasing current density production by factor 9 0.14 1.21 mA/cm2 and reducing H2 440 0.44 0.001 mA/cm2. Using ReaxFF reactive molecular dynamics, we find with highest selectivity, dihexadecyldimethylammonium bromide, promotes substantial population near along sufficient H2O activate CO2. While critical number water molecules is required in CO, trend selectivity strongly correlates availability molecules. demonstrate ordering cationic modifiers plays significant role around active site, thus determining reaction selectivity. The dramatic improvement addition simple suggests an additional strategy electrocatalysis.