Extending Asymmetric π-Conjugation of Vinylene-Linked Covalent Organic Frameworks with Remodeled Redox Active Sites for H ₂ O ₂ Photosynthesis and Aerobic Oxidations

Covalent organic frameworks (COFs) exhibit considerable potential in artificial photosynthesis, notably for photoreductive generation of hydrogen peroxide (H₂O₂) and related aerobic oxidative synthesis of value-added chemicals. However, their widespread application is hindered by limited chemical stability, suboptimal redox active sites, and inefficient exciton dissociation. To address these challenges, we report the design of a vinylene-linked sp²-COF by introducing an electron-withdrawing and polar -CN group (sp²-COF-CN) to extend asymmetric π-conjugation and remodel the redox active sites for achieving superior H₂O₂ photosynthesis and aerobic oxidation reactions. Comprehensive characterization indicates that the introduction of sp-hybridized C≡N units reshapes the donor-π-acceptor configuration, promotes charge delocalization, and boosts electron density with pronounced asymmetry. These effects collectively yield a remarkable H₂O₂ production rate of 17,768.4 μmol g⁻¹ h⁻¹ using benzyl alcohol as a sacrificial agent, exceeding those of most recently reported organic and inorganic photocatalysts. Furthermore, sp²-COF-CN demonstrates high efficiency in diverse aerobic oxidation reactions, including the oxidation of furfuryl alcohol in water and the benzylamine- and thiophenol-based coupling reactions in organic solvents. This work demonstrates that extending asymmetric π-conjugation of sp²-COFs, combined with redox active site remodeling, can be an effective strategy for designing high-performance heterogeneous photocatalysts for the selective synthesis of value-added chemicals.