Boosting Electroreduction of Nitrate and CO to Urea on a Tandem Fe/MoS Catalyst.

Urea electrosynthesis by coelectrolysis of NO and CO (UENC) holds enormous promise for sustainable urea production, while the efficient UENC process relies on the rational design of high-performance catalysts to facilitate the electrocatalytic C-N coupling efficiency and the hydrogenation reaction process. Herein, Fe single atoms supported on MoS (Fe/MoS) are developed as a highly effective and robust catalyst for UENC. Theoretical calculations and operando spectroscopic measurements reveal a tandem catalysis mechanism of the Fe-S motif and MoS-edge to jointly promote the UENC process, where the Fe-S motif drives the early C-N coupling and subsequent *CONO-to-*CONH step. The generated *CONH is then migrated from the Fe-S motif to the nearby MoS-edge, which facilitates the *CONH → *COOHNH step for urea formation. Noticeably, Fe/MoS assembled in a flow cell reaches a maximum urea Faraday efficiency of 54.98% with a corresponding urea yield rate of 18.98 mmol h g, performing at the top level among all of the UENC catalysts reported to date.