Linker Engineering of Covalent Organic Frameworks for Efficient Photocatalytic Hydrogen Evolution

Abstract

Interfacial charge transfer and active sites play the important role in the performance of heterogeneous photocatalysts. Reticular chemistry in covalent organic frameworks (COFs) ensures the construction of isomeric architectures made up of different donor and acceptor monomers for tuning the charge transfer dynamics and active sites. Herein, five D-A dual-pore COFs have been prepared from the reaction of naphthalene-2,6-diamine donor with different tetraaldehyde acceptor. The experimental results disclose that the linker engineering, by changing the heteroatoms and conjugation systems from benzooxadiazole, benzothiadiazole, benzoselenadiazole, naphthothiadiazole, to naphthoselenadiazole, tunes the electron-accepting capacity of corresponding D-A COFs. Among five samples, the naphthothiadiazole-derived COF has the optimal charge transfer and active sites, exhibiting the highest hydrogen evolution rate of ca. 35 mmol g−1 h−1 with the help of 3 wt % Pt under visible-light irradiation (˃ 420 nm). This work illustrates the linker engineering strategy with the simultaneous adjustment of interfacial charge transfer and active sites enables the enhancement of hydrogen generation effciency, inputting new vigor to develop the COF photocatalysts one the basis of the reticular synthesis toolkit.