Visible‐Light Driven Oxygen Evolution From Water With a Donor–Acceptor Covalent Organic Framework Photocatalyst

The oxygen evolution reaction (OER) presents a significant kinetic bottleneck in photocatalytic water splitting and solar fuel production. To address this challenge, we designed and synthesized a donor–acceptor covalent organic framework (COF) with a cationic, electron‐deficient pyrylium derivative monomer and an electron‐rich 2,4,6‐trihydroxybenzene‐1,3,5‐tricarbaldehyde monomer to maximize potential donor–acceptor effect, extending the absorption and photon utilization to the red end of the visible region. Using a postsynthetic modification strategy, atomically dispersed Co 2+ sites were precisely anchored onto the framework to construct Co‐TTN‐COF, a composite that integrates efficient light‐harvesting and catalytic functions. Under visible‐light irradiation, this catalyst demonstrates superior performance for water oxidation, achieving an average oxygen evolution rate of 249 μmol h −1 g −1 . This work establishes a new strategy for the development of efficient and stable COF‐based integrated photocatalytic systems.