Photosynthesis of urea from N₂ and CO₂ using dual active site SiW₆Mo₆@MIL-101(Cr) at room temperature

The one-step synthesis of urea at room temperature and pressure from N-2 and CO2 has enormous economic and environmental benefits. In this study, a SiW6Mo6@MIL-101(Cr) photocatalyst was synthesized employing a dual active site regulation strategy, reaching 1148 mu g h(-1) g(cat)(-1) and 100% selectivity for urea under optimal experimental conditions. Both performance tests and DFT calculations unequivocally establish that SiW6Mo6@MIL-101(Cr) serves as a bifunctional photocatalyst, offering dual active sites for the proficient adsorption and activation of N-2 and CO2. MIL-101(Cr) immobilizes SiW6Mo6, enhances dispersion and gas adsorption capacity, and supplies additional electrons through light absorption for reduction reactions. Importantly, the W site in SiW6Mo6 is assigned for the activation of nitrogen, whereas the Mo site is assigned for the activation of CO2. The rate-limiting step of urea synthesis involves the interaction of *CO and *N-2, forming a tower-like intermediate *NCON*, where the dual active sites play a crucial role in reducing the reaction barrier.