Ultralight covalent organic framework/graphene aerogels with hierarchical porosity

The fabrication of macroscopic objects from covalent organic frameworks (COFs) is challenging but of great significance to fully exploit their chemical functionality and porosity. Herein, COF/reduced graphene oxide (rGO) aerogels synthesized by a hydrothermal approach are presented. The COFs grow in situ along the surface of the 2D graphene sheets, which are stacked in a 3D fashion, forming an ultralight aerogel with a hierarchical porous structure after freeze-drying, which can be compressed and expanded several times without breaking. The COF/rGO aerogels show excellent absorption capacity (uptake of >200 g organic solvent/g aerogel), which can be used for removal of various organic liquids from water. Moreover, as active material of supercapacitor devices, the aerogel delivers a high capacitance of 269 F g −1 at 0.5 A g −1 and cycling stability over 5000 cycles. Macroscopic architectures of covalent organic frameworks (COF) allow to fully exploit their chemical functionality and porosity but achieving three-dimensional hierarchical porous COF architectures remains challenging. Here, the authors present a COF/reduced graphene oxide aerogel which is synthesized by growing COF during a hydrothermal process along the surface of graphene sheets.