Atomically Dispersed Sn Confined in FeS2 for Nitrate‐to‐Ammonia Electroreduction

Abstract Electrocatalytic NO 3 − reduction to NH 3 (NO 3 RR) is an efficient strategy to simultaneously mitigate NO 3 − contamination and produce sustainable NH 3 . Herein, atomically dispersed Sn confined in FeS 2 (Sn‐FeS 2 ) is reported as an effective and robust NO 3 RR catalyst, achieving a maximum NH 3 ‐Faradaic efficiency of 96.7% with a corresponding NH 3 yield rate of 15.8 mg h −1 cm −2 , along with an excellent catalytic stability. Atomic coordination characterizations of Sn‐FeS 2 unravel that single‐atomic Sn bonds with the surrounding Fe atoms to construct the unique p‐d hybridized Sn‐Fe pair sites. Combining theoretical investigations and operando spectroscopic measurements unveil that Sn‐Fe pair sites can synergistically promote the NO 3 − activation and N═O bond dissociation, accelerate the protonation energetics of NO 3 − ‐to‐NH 3 pathway and suppress the competing hydrogen evolution, eventually drastically enhancing the NO 3 RR activity and selectivity.