Mechanistic Insights into the CO ₂ ‐Assisted NO Electrochemical Deoxygenation and Hydrogenation

Abstract Electrocatalytic NO reduction to NH 3 holds significant potential for pollutant treatment and resource recovery. Herein, we report that the introduction of CO 2 on octahedral oxide‐derived copper (o‐OD‐Cu) significantly enhances the electrochemical reduction of NO to NH 3 . With 10% NO in a CO 2 environment, the Faradaic efficiency for NH 3 production in a flow cell remains around 80% over a wide current density range from 20 to 250 mA cm −2 . At a current density of 250 mA cm −2 , the yield can reach up to 1403.9 µmol cm −2 h −1 , which is 3.71 times higher than without CO 2 and surpasses the performance reported in similar literature. Moreover, even at a low concentration of 1% NO, the Faradaic efficiency can reach a maximum of 70.11% at a current density of 20 mA cm −2 . In situ investigations and theoretical calculations revealed that, in the coexistence of NO and CO 2 , the NO reduction pathway involves a unique route wherein *CO and *COOH, produced from CO 2 reduction, can respectively promote the deoxygenation of *NO and hydrogenation of *N by acquiring O atoms from *NO and providing H atoms for the sustained hydrogenation of *N, thereby accelerating the conversion process of NO to NH 3 .