The effect of the oxidation level of the graphene oxide substrate on in situ growth of COF-300†

Abstract

The synthesis of covalent organic framework (COF) based hybrid materials is highly important for society as it provides materials with a large variety of beneficial properties. However, the COFs in graphene–COF and reduced graphene oxide (rGO)–COF hybrids are mostly two-dimensional (2D) due to the challenge in the design and synthesis of three-dimensional (3D) COFs. rGO-3D COF composites were here synthesized using several different graphene oxide (GO) substrates via a simple ventilation-vial protocol. These composites, as well as the starting materials of GO, were characterized by XRD, Raman spectroscopy, XPS, FT-IR, TG, SEM and EDS. The mechanism of in situ growth of COF-300 on graphene is proposed, where the oxygen-containing functional groups on GO are assumed to play a leading role in anchoring COF-300. Interestingly, a change in the morphology of COF-300 particles on the GO substrate was observed. It is found that GO acts as not only the substrate but also a structure-directing agent for modulating the morphology of COF-300. The high oxidation level and the large interlayer distance of GO are beneficial for growing COF-300 with smaller length, higher loading and more uniform distribution. This finding opens an avenue to control the morphology of COFs just by regulating the GO substrate. This work also covers GO prepared from natural coaly graphite, which promotes the high-value utilization of natural coaly graphite resources.