Preparation of functional material layers of TT-COFs with built-in formyl groups for efficient dyes removal.

There is no doubt that the wide application of COFs depends on the diversity and complexity of their structure and composition, as well as the feasibility and convenience of use. Herein, large area defect-free continuous functional material layers have been fabricated by compounding sub-stoichiometric tetratopic-tritopic covalent organic frameworks (TT-COFs) on graphene oxide (GO) via simply hot pressing. The one-step synthesis of TT-COFs with built-in formyl groups endowed the robust material layers with extraordinary host-guest interactions, so they can specifically reject cations dyes according to adsorption effect, molecular sieving and Donnan effect. Owing to the through-plane molecular transfer channels, large amounts of water molecules can pass through the internal channel rapidly. As a result, high rejection of 99.5% and large flux of 309.99 L·m-2·h-1·bar-1 for dye molecules have been realized. This simple and effective method provided more extensive practicality and greater convenience in recycling and reuse, and demonstrated the utility and high efficiency of TT-COFs with built-in formyl groups as an advanced material platform for dyes removal.