Asymmetric N, S‐Coordinated Cu Single‐Atom Catalysts for High‐Performance Electrocatalytic Nitrate‐to‐Ammonia

Abstract The electrochemical nitrate reduction reaction (NO 3 RR) to ammonia conversion provides a sustainable solution for simultaneous nitrate wastewater remediation and value‐added ammonia production. Despite its potential, the NO 3 RR process is fundamentally constrained by slow eight‐electron transfer kinetics and numerous side reactions, while existing studies on single‐atom catalysts (SACs) have predominantly investigated symmetrical coordination structures. Herein, an asymmetrically coordinated Cu‐SNC‐2 SAC is engineered by introducing low‐electronegativity S atoms to construct the microstructure of Cu‐S 1 N 2 active sites. The as‐synthesized catalyst demonstrates exceptional activity in the NO 3 RR, exhibiting a remarkable NH 3 Faradaic efficiency (FE) of 98.2% (−0.3 V vs RHE) and an impressive NH 3 yield rate of 1.18 mmol h −1 cm −2 (−0.6 V vs RHE), significantly outperforming the majority of reported Cu‐catalyzed NO 3 RR systems. Combined with the in situ spectroscopy and theoretical calculations, the outstanding performance is ascribed to an asymmetric atomic interface configuration, which optimizes the free energy of NO 3 RR intermediates and the electron density distribution. Notably, the Zn‐NO 3 – battery featuring a Cu‐SNC‐2 cathode exhibits excellent performance with a power density reaching 7.60 mW cm −2 . This work establishes a novel strategy for atomic‐scale asymmetric electrocatalyst design and demonstrates significant potential for practical implementation in energy conversion and storage.