Cooperative Cu with defective MXene for enhanced nitrate electroreduction to ammonia

Abstract The electroreduction of nitrate (NO 3 RR) to ammonia (NH 3 ) provides a promising solution to enable environmental remediation caused by ‐containing waste and also allows for energy‐saving NH 3 generation. Adsorption of *NO 2 intermediate may be strengthened to decrease byproducts (e.g., ) and favor the eight‐electron NO 3 RR into NH 3 . In this work, copper‐incorporated O‐vacancy containing Ti 3 C 2 MXene (Cu@Ti 3 C 2 O v ) is reported, which cooperatively inhibits production and facilitates hydrogenation, leading to approximately 100% Faradaic efficiencies of NH 3 and high yield rates at various potentials. Density functional theory calculations show that and the *NO 2 intermediates have a significant interaction with the Cu@Ti 3 C 2 O v catalyst. Moreover, the formation of has a high energy barrier, which explains the appealing catalytic performance of the Cu@Ti 3 C 2 O v toward NO 3 RR with suppressed and elevated NH 3 selectivity. This work would motivate the prudent design of new catalysts for high‐performance NO 3 RR to NH 3 by elucidating the significance of stabilizing the *NO 2 intermediate.