Condensation Center Regulation in Donor-Acceptor Polymers Enables Dynamic Proton Reservoirs for Efficient H₂O₂...

Photocatalytic hydrogen peroxide production offers a sustainable route for solar-to-chemical energy conversion, yet precise control over structure-reactivity relationships in organic photocatalysts remains limited. Here, we report diazine-based donor-acceptor (D-A) imine-linked covalent organic polymers (COPs) designed for efficient H₂O₂ generation. By regulating the condensation centers (para, meta, and ortho), we find that para-regulated polymers exhibit the highest structural stability and photocatalytic reactivity. Mechanistic and theoretical analyses reveal that H₂O₂ photosynthesis is dominated by indirect 2e^- oxygen reduction reaction (ORR) and complemented by a 4e^- water oxidation reaction (WOR), alleviating the dependence on O₂-rich environments. Importantly, localized protonation is shown to be essential for O₂ adsorption and activation, with Pauling-type end-on binding favoring selective 2e^- ORR. In addition, -CN incorporation and para-regulation effectively lower the rate-limiting energy barriers, strengthening interfacial electron transfer. Dynamic proton reservoir behavior further endows the system with broad pH adaptability, maintaining stable local proton levels throughout the reaction. This work highlights the importance of condensation center regulation in programming reactant activation and charge transfer behavior, providing a design principle for advanced COPs in artificial photosynthesis.