Covalent organic frameworks (COFs) for environmental applications

Covalent organic frameworks (COFs) is a type of newly developed crystals known for chemical stability, ordered porous structure, and tunable skeleton, as well as luminescence in some cases. By virtue of their advantages, stable COFs play diverse roles in the field of environmental applications, such as adsorbing, separating, sensing and catalytically degrading pollutants. This review mainly focused on the state-of-the-art development of stable COFs in environmental applications, such as adsorption, membrane separation and detection of various environmental pollutants, including heavy metals and radionuclides (Hg2+, UO22+, I2, Nd3+ and TcO4−), toxic organic pollutants (organic dyes, pharmaceuticals, organophosphorus flame retardants, per- and poly-fluorinated alkyl substances and endocrine-disrupting chemicals), as well as the catalytic degradation/conversion and CO2 capture. Their structural characteristics, functional design approaches and specific environmental applications were introduced, and concluding remarks and future research directions were proposed.