Electronic Isolation Wall Engineering in Covalent Organic Frameworks for Enhancing Overall H2O2 Photosynthesis

Abstract

Covalent organic frameworks (COFs) hold promises for overall H2O2 photosynthesis. However, their efficiency is constrained by rapid charge recombination at the universal C=N linkages due to the nitrogen lone pairs acting as efficient hole traps. Here, we report a molecular-level electronic isolation strategy through the rational incorporation of C=N–N motifs into the COF backbone. This built-in energetic barrier effectively localizes electron density and directs charge flow along a preferential pathway, which collectively stabilizes the non-equilibrium charge-separated state and suppresses interfacial recombination. The resulting prolonged carrier lifetime enables efficient multi-electron overall H2O2 photosynthesis. Simultaneously, the molecular partition creates a spatially synergistic catalytic interface, which facilitates dual-site activation, promotes reactant adsorption and polarization, and significantly lowers the reaction energy barrier. In pure water and without sacrificial agents, the optimized TMN-COF achieves a H2O2 production rate of 4080 μmol g–1 h–1 with a solar-to-chemical conversion efficiency of 2.17% and sustains a production rate of 1330 μmol g–1 h–1 under ambient air conditions. When scaled up, the material retains catalytic activity (8.1 mmol L–1) and demonstrates broad-spectrum antimicrobial efficacy and efficient degradation of organic pollutants under visible-light irradiation. This work provides a foundational blueprint for spatially engineering interface charge behavior in COF photocatalysts.