Stable construction of covalent organic framework/copper sulfide heterojunction on cellulose fibers with hyperbranched polyamide-amine for efficient photocatalytic degradation of organic dyes

In this work, 2,6-diaminoanthraquinone (DAAQ)-1,3,5-triformylphloroglucinol (TFP) COF/CuS heterojunction was supported on cellulose fibers with hyperbranched polyamide-amine (HPAMAM) as growth template and stabilizer to prepare composite paper for photocatalytic degradation of organic dyes in water. HPAMAM was grafted onto dialdehyde cellulose fibers (DACF) via Schiff base reaction. The intramolecular cavities of HPAMAM provided suitable sites for the growth of COF/CuS heterojunction, and the flexible polymer chains of HPAMAM were used to disperse and stabilize the COF/CuS heterojunction. COF provided an ideal framework for the adsorption, diffusion, and activation of organic dyes in water. And the photogenerated electron transfer path in the COF/CuS heterojunction formed a Z scheme model, which enhanced the separation efficiency of photogenerated electrons and maximized the redox potential for high photocatalytic activity. The DACF/HPAMAM/COF/CuS paper exhibited the highest photocatalytic reaction rate (k = 0.5549 min−1), 7.4 times higher than that of DACF/HPAMAM/COF paper and 6.2 times higher than that of DACF/HPAMAM/CuS paper. To the best of our knowledge, this is one of the best performances for photocatalytic degradation of organic dyes. The DACF/HPAMAM/COF/CuS paper also showed good photocatalytic cycling stability and structural stability. This study provides a strategy for constructing COF/inorganic semiconductor Z scheme heterojunction on cellulose fibers to prepare photocatalytic paper and demonstrates a breakthrough in the field of photocatalytic degradation of organic dyes in water.