Pulsed-Potential Electrolysis Enhances Electrochemical C-N Coupling by Reorienting Interfacial Ions

The electrochemical processing of anthropogenic CO2 is an emerging technology aimed at utilizing renewable energies to synthesize valuable chemicals. Recently, developments in broadening the scope of the CO2 reduction reaction (CO2RR) by enabling heteroatom coupling have surged with a focus on C-N bond formation. Herein, we investigate the factors that govern the selectivity and activity in synthesizing urea from environmentally malignant chemical feedstocks (CO2 and NO3-). Through a combination of electrolyte optimization and pulsed potential electrolysis, electrochemical urea production was optimized to a Faradaic efficiency of 60.4% with current densities reaching as high as 310 mu A cm(-2). This work was further supported by in situ surface enhanced infrared absorbance spectroscopy that reveals the formation of C-N-related species at low overpotentials. Density functional theory calculations revealed that the reaction progresses between early reduction intermediates for the CO2RR and NO3RR and offered insights into the impacts of pulsed-potential on substrate transport.