A highly fluorine-functionalized 2D covalent organic framework for promoting photocatalytic hydrogen evolution

In search of novel semiconductor photocatalysts is one of the important topics in photocatalytic solar fuel production. Here, we report a novel highly fluorinated covalent organic framework (denoted as TFA-COF) constructed via Schiff-base condensation of 2,3,5,6-tetrafluoroterephthaldehyde and 2,4,6-tris(4-aminophenyl)-1,3,5-triazine for photocatalytic H2 production from water. Introducing fluorine atoms with electron-withdrawing ability into the framework of COF can not only significantly increase its specific surface area to 2490.3 m2/g, but also reduce its band gap, and bring about the efficient separation of photogenerated electrons and holes. As a result, the TFA-COF exhibits a continuous and stable photocatalytic H2 production rate of 80 μmol·g−1·h−1 under full wavelength irradiation, which is much higher than that of the similar one without fluorine (TA-COF, 10 μmol·g−1·h−1). Our results illustrate that the introduction of fluorine atoms can effectively increase the photocatalytic performance of COFs.