Covalent organic frameworks and their composites as high-performance photocatalysts for organic pollutant removal

Covalent organic frameworks (COFs) are a new class of porous polymers completely connected by covalent bonds, which have been favored by many researchers due to their admirable physicochemical properties, such as large specific surface area, tunability, high versatility, and admirable stability. In order to further improve the photocatalytic performance of COF materials, the construction of composite materials is undoubtedly an effective strategy. Numerous studies have shown that COFs exhibit unique properties when combined with other materials and can serve as efficient photocatalysts for the removal of organic pollutants from water. This article reviews the construction strategies of COF-based catalysts and recent research progress on composite materials such as metal-nanoparticles, semiconductor-, metal-organic framework (MOF)-based composites, along with their removal mechanisms for certain organic pollutants in water. In addition, this review also provides some new perspectives on significant challenges, opportunities, and promising prospects for future research. In summary, significant progress has been made in the development of state-of-the-art COF-based composite photocatalysts for pollutant removal.