卟啉基共价有机框架的光催化研究进展

Research Progress of Porphyrin-Based Covalent Organic Frameworks in Photocatalysis

共价有机框架(COFs)因其比表面积大、稳定性高和可设计性强等优点而引起了人们的广泛关注.卟啉是一种具有大π共轭体系、易于修饰和良好吸光性能的功能基元.卟啉基COFs吸光范围广,活性位点多,电子-空穴分离能力强,在光催化领域应用广泛.综述了卟啉基COFs在光催化还原二氧化碳、光催化分解水、光催化有机转化和光催化还原六价铀的研究进展,最后讨论了卟啉基COFs在光催化领域的前景和面临的挑战.

Covalent organic frameworks(COFs)are a class of crystalline organic porous materials formed by molecular building blocks via covalent bonds.According to the dimensions of the framework extended in space,COFs can be divided into two-dimensional and three-dimensional COFs.Owing to their high specific surface area,good stability and strong designability,COFs have broad prospects in the fields of gas adsorption and separation,catalysis,sensing,optoelectronics,and energy storage.In the field of photocatalysis,COFs have the following advantages.First,COFs are highly designable,which can achieve efficient photocatalysis by introducing different functional units to adjust the band gap energy and light absorption range.Secondly,the ordered structure of COFs improves the electron-hole separation efficiency.In addition,the high specific surface area and abundant active sites of COFs can promote the photocatalytic reaction and improve the reaction rate.Finally,COFs are connected by covalent bonds,which make them highly stable and facilitate the maintenance of catalytic activity in the photocatalytic process.Porphyrins are a class of 18π-electron conjugated macrocyclic compounds formed by the interconnection of four pyrroles,which can be involved in photosynthesis as the core part of chlorophyll and other biomolecules.As a kind of functional units with largeπ-conjugated structure and good photophysical properties,porphyrins usually have strong absorption in the 400~450 nm(Soret band)and 500~700 nm(Q band)regions,and their photocatalytic properties can be regulated by coordination with metal ions and modification of functional groups,which has unique advantages in the field of photocatalysis.By introducing porphyrins into COFs,combined with their unique advantages,porphyrin-based COFs have been found great potential in the field of photocatalysis due to the exceptional optical absorption in a broad spectral range,multiple active sites and effective electron-hole separation ability.As a new type of photocatalyst,porphyrin-based COFs have attracted much interest and have been rapidly developed in the field of photocatalysis.In this review,we focus on the discussion of porphyrin-based COFs in the photocatalytic CO_(2) reduction,photocatalytic water splitting,photocatalytic organic transformation,and photocatalytic reduction of hexavalent uranium.Finally,the prospects and challenges of porphyrin-based COFs in photocatalysis are discussed.