Boosting Electroreduction of Nitrate and CO2 to Urea on a Tandem Fe1/MoS2 Catalyst

Urea electrosynthesis by coelectrolysis of NO₃^- and CO₂ (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 MoS₂ (Fe₁/MoS₂) are developed as a highly effective and robust catalyst for UENC. Theoretical calculations and operando spectroscopic measurements reveal a tandem catalysis mechanism of the Fe₁-S₃ motif and MoS₂-edge to jointly promote the UENC process, where the Fe₁-S₃ motif drives the early C-N coupling and subsequent *CO₂NO₂-to-*CO₂NH₂ step. The generated *CO₂NH₂ is then migrated from the Fe₁-S₃ motif to the nearby MoS₂-edge, which facilitates the *CO₂NH₂ → *COOHNH₂ step for urea formation. Noticeably, Fe₁/MoS₂ 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^-1 g^-1, performing at the top level among all of the UENC catalysts reported to date.