Construction of Azobenzene Covalent Organic Frameworks as High-Performance Heterogeneous Photocatalyst

Photocatalytic performances of covalent organic frameworks (COFs) have attracted intensive attention by virtue of their regular pore structure, high specific surface area, excellent crystallinity and periodic π bonds. Herein, COF Tp-Azo was simply synthesized from 2,4,6-triformylphloroglucinol (Tp) and 4,4′-diaminoazobenzene (Azo); and incorporation of copper salt into Tp-Azo yielded a novel COF Cu-Tp-Azo. XRD, SEM and TEM results indicated that the skeleton structure of Tp-Azo was retained in Cu-Tp-Azo. Subsequently, they were applied in the photocatalytic degradation of tetracycline, the results showed that both COFs exhibited excellent photocatalytic performance and Cu-Tp-Azo showed better degradation efficiency compared with Tp-Azo, indicating that the advantages of azo-based COFs with great potential for photocatalytic applications, and the modification of copper ions did make a difference as it can not only facilitate the separation and migration of photo-generated electron–hole pairs, but decrease their recombination, further improved the photocatalytic activity of Tp-Azo. Graphical Abstract COF Tp-Azo was simply synthesized from 2,4,6-triformylphloroglucinol (Tp) and 4,4′-diaminoazobenzene (Azo); and incorporation of copper salt into Tp-Azo yielded a novel COF Cu-Tp-Azo. Both COFs exhibited excellent photocatalytic performance and Cu-Tp-Azo was even better compared with Tp-Azo, indicating that the advantages of azo-based COFs with great potential for photocatalytic applications, and the modification of copper ions can not only facilitate the separation and migration of photo-generated electron-hole pairs, but decrease their recombination, further improved the photocatalytic activity of Tp-Azo.