Constructing Substituted-Pyridine-Linked Conjugated Porous Polymers via Multicomponent Hantzsch-Type Reaction for Efficient Hydrogen Peroxide Photosynthesis from Real Seawater and Air.

Conjugated porous polymers (CPPs) have emerged as promising organo-based semiconducting materials for solar-to-chemical energy conversion due to their customizable structures and functionalities. Exploring diverse synthetic routes provides a strong driving force to promote the development of this intriguing class of photocatalysts. Herein, we report a multicomponent reaction (MCR)-based strategy to construct photoactive CPPs with precisely engineered donor-acceptor architectures. Utilizing a Hantzsch-type three-component condensation, a new family of pyridine-3,5-dicarbonitrile-linked CPPs (HCPPs) was synthesized, wherein β-ketonitrile-derived building units are strategically incorporated to generate electron-deficient heterocyclic linkages that serve as intrinsic acceptors. The resulting materials exhibit exceptional photophysical properties and enable efficient non-sacrificial hydrogen peroxide (H2O2) photosynthesis. Notably, HCPP-1, bearing a thiophene-based donor, achieves a remarkable H2O2 production rate of 5230 µmol g-1 h-1 under visible light in pure water/oxygen, and maintains high performance (4850 µmol g-1 h-1) even under simulated sunlight using real seawater and ambient air, outperforming the vast majority of reported photocatalysts. Mechanistic studies reveal spatially separated redox centers that synergistically drive an indirect two-electron oxygen reduction reaction (ORR) and a four-electron water oxidation reaction (WOR). This MCR-enabled design opens a general avenue to functional porous semiconductors for advanced solar fuel applications.