Regulating the electronic effects of phenylquinoline-functionalized COFs for effective photocatalytic destruction of chemical warfare agent simulants

Chemical warfare agents (CWAs) pose great threats to human life and require efficient remediation methods. Photocatalytic degradation by covalent-organic frameworks (COFs) provides an environmentally friendly disposal method for CWAs, but it is challenging to precisely regulate the electronic effects of COFs to enhance their photocatalytic degradation performance. Here, a series of phenylquinoline-based COFs were constructed via a one-pot, three-component self-assembly strategy using 1,3,5-tris(p-formylphenyl)benzene (TFPB), 1,3,5-tris(4-aminophenyl)benzene (TAPB), and phenylacetylene as building blocks. Functionalizing the phenylquinoline group at the para (p) position using –OCH3, –CH3, and –NO2 regulated the electron distribution of the resulting COFs. The experimental results showed that the phenylquinoline-based COF with –OCH3 group, TFPB-TAPB-p-OCH3-QL, in the oxidation of mustard gas simulant 2-chloroethyl ethyl sulfide under visible light demonstrated the best photocatalytic performance, followed by TFPB-TAPB-p-CH3-QL, while TFPB-TAPB-p-NO2-QL did not react. Theoretical calculations indicated that TFPB-TAPB-p-OCH3-QL with an electron-donating substituent had the smallest positive conduction band minimum of 0.24 eV and a moderate band gap. Excited electrons readily transferred to O2 to form 1O2, leading to superior photocatalytic oxidation activity. This study offers a new method to control the electronic effects and photocatalytic activity of COFs, providing a reference for improving COF-based photocatalysts for the decomposition of toxic chemicals.