Electronic Asymmetry in Dual-Acceptor COFs Drives Site-Specific Cooperative 2e^- ORR for Efficient H₂O₂...

Covalent organic frameworks (COFs) hold promise for photocatalytic H₂O₂ production, yet the multistep 2e^- oxygen reduction reaction (ORR) presents a fundamental contradiction: O₂ activation demands a strongly electron-deficient site, while *OOH conversion requires a moderately electron-rich environment, a trade-off unresolvable in single-acceptor COFs. Herein, we report a dual-acceptor COF (BDZ-BFA-ETP) that integrates benzothiadiazole (BDZ) and pyridinium-based ETP units to create pronounced acceptor-side electronic asymmetry. This electronic reconstruction drives site-specific functional differentiation: the electron-deficient BDZ preferentially activates O₂, while the relatively electron-rich ETP facilitates *OOH conversion and H₂O₂ release, cooperatively optimizing the entire 2e^- ORR pathway. Consequently, BDZ-BFA-ETP achieves an exceptional H₂O₂ production rate of 7976.9 µmol g^-1 h^-1 in pure water under visible light without sacrificial agents, outperforming single-acceptor COFs by factors of 1.5 and 3.4, with an apparent quantum yield of 2.84% at 400 nm and robust stability across a wide pH range. Theoretical and in situ spectroscopic investigations confirm that this electronic asymmetry not only promotes charge separation but, crucially, enables the two distinct acceptor regions to perform separate elementary steps cooperatively. This work establishes a design concept linking electronic asymmetry, site-specific functional differentiation, and cooperative catalysis, offering a roadmap for efficient solar-driven H₂O₂ synthesis.