Upgrading structural conjugation in covalent organic framework with spatial dual sites enables boosting solar-to-H2O2-to-•OH for environmental remediation

Abstract

Designing photocatalysts with well-defined structure-function relationships is imperative for propelling the progression of desired photocatalytic oxidation. Herein, the efficient conversion of solar energy to H2O2 and subsequently to hydroxyl radicals (•OH) is achieved through a synergistic interplay between olefin linkage (-CC-) and spatially separated benzene-triazine dual reaction sites within covalent organic frameworks (COFs). The upgraded -CC- can increase the conjugation degree of COFs, which establishes an expanded superstructure for boosting charge separation/transfer and stability. This precise modulation renders more opportunities for the hot electrons to migrate to the benzene site for solar-to-H2O2 generation, and to the triazine site for H2O2-to-•OH, separately. The optimized •OH generation pathway enables remarkable oxidation performances against recalcitrant organic pollutants, and pathogenic microorganisms under visible light irradiation. This work provides new insights for tuning the synergistic interactions of various building blocks within the COFs for the selective generation of highly reactive •OH for environmental remediation.