Photocatalytic Tandem Reaction for Urea Synthesis From Atmospheric CO₂ and N₂

Photocatalytic urea synthesis directly from atmospheric CO₂ and N₂ offers a sustainable route to bypass the energy-intensive Bosch-Meiser process, yet simultaneously achieving CO₂ capture and reduction, N₂ activation, and C─N coupling within a single system remains challenging. Herein, we report a two-step tandem platform combining ionic-liquid-modified metal-organic framework (IL@PCN-250-Fe₂Co) with a trinuclear copper-based covalent organic framework (HTP-Cu₃-imi-COF) for urea photosynthesis from air. The IL@MOF captures atmospheric CO₂ and photoreduces it to CO, while HTP-Cu₃-imi-COF couples the generated CO with ambient N₂ into urea. This synergistic tandem configuration delivers a urea production rate of 259.87 µg·g_cat ^-1·h^-1 under air, marking the first demonstration of photocatalytic urea synthesis from atmospheric CO₂ and N₂. In situ spectroscopic measurements and DFT calculations reveal that the imidazole-functionalized HTP segments act as hole-rich oxidation domains, promoting water oxidation to generate *OH species that oxidize locally enriched N₂ to *NO intermediates. Simultaneously, the Cu₃ clusters serve as electron-rich centers for CO adsorption and activation, forming *CO that couples with *NO via the critical *OCNO intermediate toward urea formation. This work not only showcases the first photocatalytic urea synthesis from air but also establishes a modular paradigm for cascade catalysts that integrate capture and conversion toward sustainable chemical transformations.