Anthraquinone sites engineering of covalent organic frameworks enables efficient and selective ¹O₂ generation via...

Singlet oxygen (¹O₂) is one of the most important pivotal reactive oxygen species (ROSs) in environmental remediation; however, the selective formation of ¹O₂ in Fenton-like reactions is severely hindered by the disordered redox reactions of oxidants. Here, by microenvironment engineering of the anthraquinone site in covalent organic frameworks (COFs), we present a facile approach for the directed oxidation of peroxymonosulfate (PMS) to produce ¹O₂ efficiently and selectively. Under visible light irradiation, anthraquinone-based COFs with β-ketoenamine units (DQTp COFs) deliver efficient ¹O₂ generation with near 100 % selectivity, outperforming most reported systems, while its counterpart with imine linkage (DQTb COFs) produces mixed ROSs with much lower efficiency. Hence, the DQTp COFs/PMS photocatalytic system can selectively degrade various emerging pollutants with boosted performance. A DQTp COFs-based membrane reactor (20 × 30 × 2 cm) exerts long-lasting pollutants degradation under natural sunlight, demonstrating great application potential. Experiments and theoretical results reveal that β-ketoenamine units facilitate the separation of charge pairs, facilitate the hole aggregation, and PMS adsorption simultaneously on the adjacent anthraquinone sites. Therefore, the adsorbed PMS is oxidized to SO₅^•- intermediates, which can then dimerize to produce ¹O₂. This work provides atomic-level insights for precisely controlling the formation of ROSs in Fenton-like reactions by site engineering of COFs.