A Crystalline Partially Fluorinated Triazine Covalent Organic Framework for Efficient Photosynthesis of Hydrogen Peroxide.

A partially fluorinated, metal-free, imine-linked two-dimensional triazine covalent organic framework (TF -COF) photocatalyst was developed. Fluorine (F)-substituted and nonsubstituted units were integrated in equimolar amounts on the edge aromatic units, where they mediated two-electron O photoreduction. F-substitution created an abundance of Lewis acid sites, which regulated the electronic distribution of adjacent carbon atoms and provided highly active sites for O adsorption, and widened the visible-light-responsive range of the catalyst, while enhancing charge separation. Varying the proportion of F maximized the interlayer interactions of TF -COF, resulting in improved crystallinity with faster carrier transfer and robust photostability. The TF -COF catalyst demonstrates high selectivity and stability in O photoreduction into H O , with a high H O yield rate of 1739 μmol h  g and a remarkable apparent quantum efficiency of 5.1 % at 400 nm, exceeding the performance of previously reported nonmetal COF-based photocatalysts.