Synergy of Oxygen Vacancies and Ni Single Atoms Toward Efficient Urea Photosynthesis from CO ₂ and N ₂

Abstract

Abstract The direct photochemical synthesis of urea under mild conditions presents considerable promise. Nevertheless, the photocatalytic urea synthesis is severely restricted by the co‐adsorption and activation of inert CO 2 and N 2 molecules. Herein, an ingenious design of a high‐performance Ni 1 /TiO 2‐ X catalyst by strategically coupling Ni single atoms (Ni SAs) and oxygen vacancies (Ov) onto urchin‐like TiO 2 architecture. By virtue of the unique synergistic catalysis between atomically dispersed Ni species and precisely engineered Ov sites, the Ni 1 /TiO 2‐ X catalyst achieves a remarkable urea production rate of 15.73 µmol g cat. −1 h −1 . Further mechanistic studies reveal that the atomically dispersed Ni sites facilitate N 2 adsorption and activation, generating *N 2 species, while the adjacent Ov sites activate CO 2 to form *CO intermediates. More intriguingly, the *CO species can migrate from the Ov site to the nearby Ni active centers, where they spontaneously undergo thermodynamic coupling with *N 2 to form a “tower‐like” urea precursor (*NCON* intermediate), subsequently converting to urea. The present work establishes a dual‐active‐site mechanism, comprising isolated Ni centers and adjacent Ov sites, which synergistically lowers the activation barrier for urea photosynthesis and accelerates reaction kinetics, and pioneers a transition strategy for the environmentally friendly and efficient synthesis of high‐value products.