Unlocking Electronic Confinement in Phenanthroline-π-Bridged Covalent Organic Frameworks Enables Efficient Photocatalytic H2O2 Generation and Oxidation of Sulfides

Abstract

The development of solar-active materials for efficient hydrogen peroxide (H₂O₂) production remains a critical challenge in artificial photosynthesis. Covalent organic frameworks (COFs) offer a versatile molecular platform for photocatalysis, while constructing efficient charge transfer pathways in COFs to achieve directional transport of photoexcited electrons and enhance photocatalytic performance remains highly challenging. Here, to address this limitation, a new strategy are proposed by incorporating phenanthroline motifs with rigid, conjugated skeletons into 2D triazine-based COFs to enhance charge transfer pathways. Structural and spectroscopic analyses reveal that benzene π-bridges in COF structures activate confined π-electrons in the phenanthroline core, establishing a directional π_D-π-A electron transfer pathway. This engineered charge transport system significantly accelerates photocurrent generation and markedly enhances electron mobility. The optimized material achieves an exceptional H₂O₂ production rate of 40.1 mmol g^-1 h^-1 under sacrificial conditions, representing a 4.8-fold enhancement over the original COF. The system's versatility is further demonstrated through the complete oxidation of methyl phenyl sulfide within 2 h, with similar efficiency across diverse sulfide derivatives. These findings establish phenanthroline-incorporated COFs as a promising class of photocatalysts for both photocatalytic H₂O₂ production and organic transformations.

Keywords: covalent organic frameworks; phenanthroline motifs; photocatalysts; photocatalytic production of H2O2; sulfide oxidation.