Quaternary D-π-A Covalent Organic Frameworks for High-Performance H₂O₂ Photosynthesis

The development of multicomponent covalent organic frameworks (COFs) photocatalysts capable of overcoming limitations in photogenerated charge carrier mobility and suppressing charge recombination remains a significant challenge. Herein, a series of quaternary donor-π-bridge-acceptor (D-π-A) COFs with quinoline-based π bridges are constructed for efficient photocatalytic hydrogen peroxide (H₂O₂) production. Through a multicomponent assembly strategy integrating Schiff base, Povarov, and Doebner reactions, the resulting COFs exhibited enhanced light absorption, optimized band structures, and superior charge separation efficiency. Impressively, COF-ABC1D2 achieved an excellent photocatalytic H₂O₂ production rate as high as 5 836 µmol g^-1 h^-1 in pure water condition, outperforming its ternary and binary counterparts by 3-fold and 8-fold, respectively. Comprehensive mechanistic investigations revealed that the quinoline π bridges not only reduce exciton binding energy but also promote directional charge transfer and facilitate a two-electron oxygen reduction pathway for H₂O₂ production. This work establishes a new paradigm for designing high-performance multicomponent COFs for sustainable photocatalysts.