Encapsulation of Single‐Atoms into Covalent Organic Frameworks for Highly Efficient and Persistent H ₂ O ₂ Photosynthesis via Biphasic Flow Chemistry

Abstract Covalent organic frameworks (COFs) metallization offers a potent protocol for augmenting the efficacy of artificial photosynthesis of H ₂ O ₂ . However, hurdles like the intractable short exciton lifetime and the precarious metal coordination of metallo‐COFs impede their photocatalytic proficiency. Herein, a facile and universal single‐atom encapsulation strategy is proposed, through which Fe atoms are precisely anchored in the pincer structure to achieve the planar locking of the PP‐COF and enhance its π‐conjugation effect. The Fe/PP‐COF with extremely high single‐atom stability exhibits remarkable exciton migration distance (6.48–53.20 nm) and exciton lifetime (296.75 ps), representing the state‐of‐the‐art single‐atom COF hitherto. In a brand‐new biphasic flow reactor, within 60 h the reaction allows continuous photosynthesis of H ₂ O ₂ at a rate of 1556 µmol h ⁻¹ and an unprecedented concentration of 100 m m , with no single‐atom leakage. This work offers valuable insights into developing single‐atom COFs and precise regulation of single‐atoms to achieve high space‐time continuous H ₂ O ₂ production.