Fluorine-Containing Covalent Organic Frameworks: Synthesis and Application.

Covalent organic frameworks (COFs) are a type of crystalline porous polymers and possess ordered structures and eternal pores. Because of the unique structural characters and diverse functional groups, COFs have been used in various application fields, such as adsorption, catalysis, separation, ion conduction, and energy storage. Among COFs, the fluorine-containing COFs (fCOFs) have been developed for special applications by virtue of special physical and chemical properties resulted by fluorine element, which is a nonmetallic halogen element and possesses strong electronegativity. In organic chemistry field, introducing fluorine into chemicals enables chemicals to exhibit many interesting properties, and fluorine chemistry increasingly plays an important role in the history of chemical development. The introduction of fluorine in COFs can enhance the crystallinity, porosity, and stability of COFs, making COFs show superior performances and some new applications. In this review, the synthesis and application of fCOFs are systematically summarized. The application involves photocatalytic production of hydrogen peroxide, photocatalytic water splitting, electrocatalytic CO 2 reduction, adsorption for different substances (H 2 , pesticides, per-/polyfluoroalkyl substances, polybrominated diphenyl ethers, bisphenols, and positively charged organic dye molecules), oil-water separation, energy storage (e.g., zinc-ion batteries, lithium-sulfur batteries), and proton conduction. Perspectives of remaining challenges and possible directions for fCOFs are also discussed. This article is protected by copyright. All rights reserved.