Ionic liquid-functionalized isomeric covalent organic frameworks for enhanced photocatalytic hydrogen peroxide...

Photocatalytic H₂O₂ production has emerged as a promising and environmentally friendly alternative to the energy-intensive anthraquinone process. However, developing photocatalysts that achieve both efficient charge separation and effective O₂ activation remains a significant challenge. In this study, two isomeric covalent organic frameworks (COFs), S-TB-COF and D-TB-COF, were synthesized and then functionalized with ionic liquids (ILs) to yield S-TB-ILs-COF and D-TB-ILs-COF. Under visible-light irradiation, ILs modification significantly enhanced photocatalytic H₂O₂ production. Specifically, S-TB-ILs-COF achieved a H₂O₂ generation rate of up to 1420 μmol g^-1 h^-1, which was 5.55 and 1.4 times those of pristine S-TB-COF and D-TB-ILs-COF, respectively. Combined experimental characterization and density-functional theory calculations revealed that IL modification optimized the electronic structure of COFs, facilitated photogenerated charge separation, promoted O₂ activation, and reduced the energy barrier for O₂-to-^•O₂^- conversion. These findings provide a novel strategy for enhancing charge separation and regulating the oxygen reduction reaction pathway in photocatalysts.