Atomic-Level Dipole Engineering in Covalent Organic Frameworks for Enhancement of Photocatalytic Hydrogen Peroxide...

Overcoming the fundamental challenge of rapid exciton recombination is paramount for advancing photocatalysis. Here, we introduce a paradigm-shifting strategy based on atomic-scale dipole engineering within covalent organic frameworks (COFs) to master charge separation. We have designed and synthesized a series of isostructural COFs incorporating different chalcogen heteroatoms (O, S, Se), systematically elucidating how electronegativity-driven dipole polarization governs photocatalytic oxygen reduction. Under the demanding conditions of sacrificial-agent-free H₂O₂ synthesis, the oxygen-endowed COF (HFPB-BO) demonstrated unparalleled performance. Attributed to its immense calculated dipole moment of 6.53 D, broad visible-light harvesting, and the longest fluorescence lifetime in the series, HFPB-BO achieved a remarkable H₂O₂ generation rate of 2963 µmol h^-1 g^-1. This rate surpasses its sulfur (HFPB-BS) and selenium (HFPB-BSe) analogues by factors of 1.2 and 3.1, respectively. This work establishes, for the first time, a direct and quantifiable correlation between heteroatom-tuned dipole polarization and photocatalytic activity, presenting a rational and powerful design principle for the next generation of advanced COF photocatalysts.