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 Co²⁺ 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.