Fabrication of electron–acceptor staggered AB Covalent triazine-based frameworks for enhanced visible-light-driven H2 evolution

Abstract

Covalent triazine-based frameworks (CTFs) have been emerged as a promising organic material for photocatalytic water splitting. However, all of the CTFs only are in the form of AA stacking model to participate in water splitting. Herein, two CTF-1 isomers with different stacking models (eclipsed AA, staggered AB) were obtained by modulating the reaction temperature. Interestingly, experimental and theoretical calculations showed that the crystalline AB stacking CTF-1 possessed a much higher activity for photochemical hydrogen evolution (362 μmol g−1 h−1) than AA stacking CTF-1 (70 µmol h−1 g−1) for the first time. The outstanding photochemical performance could be attributed to its distinct structural feature that allows more N atoms with higher electron-withdrawing property to be involved in the water reduction reaction. Notably, as a cathode material for PEC water reduction, AB stacking CTF-1 also demonstrated an excellent saturated photocurrent density up to 77 µA cm−2 at 0 V vs. RHE, which was superior to the AA stacking CTF-1 (47 µA cm−2). Furthermore, the correlation between stacking models and photocatalytic H2 evolution of CTF-1 were investigated. This study thus paves the path for designing optimal photocatalyst and extending the novel applications of CTF-based materials.