Formation of carbon–nitrogen bonds in carbon monoxide electrolysis

The electroreduction of CO₂ is a promising technology for carbon utilization. Although electrolysis of CO₂ or CO₂-derived CO can generate important industrial multicarbon feedstocks such as ethylene, ethanol, n-propanol and acetate, most efforts have been devoted to promoting C–C bond formation. Here, we demonstrate that C–N bonds can be formed through co-electrolysis of CO and NH₃ with acetamide selectivity of nearly 40% at industrially relevant reaction rates. Full-solvent quantum mechanical calculations show that acetamide forms through nucleophilic addition of NH₃ to a surface-bound ketene intermediate, a step that is in competition with OH^– addition, which leads to acetate. The C–N formation mechanism was successfully extended to a series of amide products through amine nucleophilic attack on the ketene intermediate. This strategy enables us to form carbon–heteroatom bonds through the electroreduction of CO, expanding the scope of products available from CO₂ reduction.