Atomically Dispersed Copper Electrocatalysts with Proton‐feeding Centers for Efficient Ammonia Synthesis by Nitrate Electroreduction

Abstract Electrocatalytic conversion of nitrate pollutants into ammonia (NH 3 ) is promising for high‐value chemical production while mitigating environmental pollution. Catalysts play a crucial role in facilitating the necessary chemical reactions, but despite substantial advancements, their efficiency and selectivity remain limited due to the high energy barriers associated with proton transfer. Herein, a unique electrocatalyst system is engineered with isolated copper sites embedded within nitrogen and oxygen co‐doped porous carbon (Cu SA ‐NO/C). This strategically designed electrocatalyst achieves an impressive NH 3 Faradaic efficiency of 92.7% and a yield rate of 24.9 mg h −1 mgCu −1 at a low potential of −0.2 V vs RHE, outperformed most of all previously‐reported atomically dispersed metal‐nitrogen carbon (M‐N‐C) catalysts. The catalytically active site in this electrocatalyst is identified as Cu atom coordinated with two N atoms and two O atoms (CuN 2 O 2 ). In situ infrared absorption spectroscopy and kinetics isotope experiments revealed that the intrinsic CuN 2 O 2 dramatically enhances the water dissociation process and accelerates the protonation kinetics during nitrate reduction. Furthermore, the first principles calculations show that CuN 2 O 2 catalytic sites also promote the adsorption of NO 3 − and desorption of NH 3 , along with the significantly facilitated water dissociation kinetics for proton feeding.