Synergy of Oxygen Vacancies and Ni Single Atoms Toward Efficient Urea Photosynthesis from CO <sub>2</sub> and N <sub>2</sub>
Bo Ding, Tianren Liu, Wensheng Zhang, Zhishan Liang, Youlin Huang, Dongdong Qin, Yingying Fan, Dongxue Han
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.