Triggering C‒N Coupling on Metal Oxide Nanocomposite for the Electrochemical Reduction of CO₂ and NO_x⁻ to Formamide

The co-electroreduction of CO₂ and NO_x⁻ (NO₃⁻/NO₂⁻) to generate formamide (HCONH₂) offers an opportunity for downstream chemical and polymer manufacturing decarbonization; however, significant challenges lie in the C‒N coupling and the associated low product selectivity. Herein, p-block metal oxides are incorporated in copper oxides to provide more accessible active sites for reactant adsorption and activation, tuning the reaction selectivity toward the formamide production. Through in situ Raman and synchrotron-based infrared spectroscopy measurements, C─N bond formation is demonstrated in real-time with the CuO_x/BiO_x catalyst, where the C─N bond is detected via a *CHO and *NH₂ intermediates formation, in agreement with the density functional theory calculations. When tested in a flow electrolyzer, a formamide yield rate of 134 ± 11 mmol h⁻¹ g_cat⁻¹ is reported, the first report of co-electroreduction of CO₂ and NO_x⁻ to formamide beyond conventional H-cell measurements. These new insights on the C‒N coupling mechanisms and scale-up capability provide directions for further development of electrocatalysts for the formamide production.