Construction of COF–COF heterojunctions for visible-light driven alcohol oxidation

Covalent organic framework (COF) as a novel type of photocatalysts has attracted great attentions in artificial photosynthesis. However, the photocatalytic activity of COFs is still not satisfied, due to the difficulty in exciton dissociation. Herein, we report the promotion of exciton dissociation with a COF–COF heterojunction prepared by deposition of nanoTp-TTA COF colloids on tetrahydroquinoline-linked QH-COF. The COF–COF heterojunction exhibits significantly enhanced transition photocurrent and conductivity as compared with individual COFs, implying the promotion of charge separation efficiency by the formation of COF–COF heterojunction. In the selective oxidation of benzyl alcohol, the turnover frequency (TOF) of Tp-TTA/QH heterojunction is 2.2 and 3.9 times higher than that of QH-COF and Tp-TTA COF, which is superior to most of COFs and MOFs in recent reports. This study provides an efficient strategy to facilitate the charge separation efficiency of COF-based photocatalysts.