Insight into Photocatalytic C─N Coupling for Urea Synthesis on Ru Single Atom Modified CeO ₂

Abstract Currently, the production of urea by photochemical routes holds significant potential. However, photocatalytic urea synthesis is significantly limited by the co‐sorption and activation of CO ₂ , H ₂ O, and N ₂ as well as C─N coupling process. Herein, Ru ₁ (single atom)/CeO ₂ ‐V _O (containing oxygen vacancies) is synthesized by a room‐temperature photochemical strategy. Benefiting from the synergistic effect of Ce ³⁺ ‐V _O and single atoms, Ru ₁ /CeO ₂ ‐V _O nanosheets delivered the highest urea yield rate of 13.73 µmol g ⁻¹ h ⁻¹ . Ultrafast transient absorption spectroscopy demonstrated that the localized asymmetric structure formed by oxygen vacancies and Ru single atoms on CeO ₂ can generate a stronger locally polarized electric field, thereby extending the photogenerated carrier lifetime. Experimental and theoretical calculations showed that Ru site promoted N ₂ adsorption and optimized water dissociation, which ensured the formation of N‐containing intermediates and the supply of protons to synthesize urea. The Ce‐ V _O site activated CO ₂ to generate *CO, and the formed *CO migrated from the site to the adjacent Ru‐V _O site. Further, the synergistic action of the dual sites promotes *CO couples with *NNH to form *NCONH, eventually converting to urea. Accordingly, this work sheds insight into the design of dual sites for effective photocatalytic C─N bond coupling to synthesize urea.