Synergistic effects of COF and GO on high flux oil/water separation performance of superhydrophobic composites

Covalent organic frameworks (COFs) have been emerged as potential coating material because of their rigid porous structure and excellent chemical stability, however, the challenges of complicated preparation process and poor processability are still remained. As a widely used composite matrix, graphene oxide usually suffers from swells and poor acid/base resistance caused by the weakening of 7C-7C interaction between graphene sheets with large interlayer spacing in an aqueous environment. Currently, it is a trend to combine COFs and graphene oxide to utilize their synergistic effect in materials. In this study, a simple one-step method is developed to prepare hybrid materials based on COFs and GO without using any special device generally required for COFs fabrication. Significantly, synergistic effects of COFs and GO which can improve the acid /alkali resistance of GO in water as well as overcome the COFs' tendency to agglomeration further make the hybrid materials stable in separation process. The hybrid materials formed by COFs polymerization and parallel covalent linking to GO were translated into recyclable superhydrophobic composite coating by spraying onto filter paper. The fabricated coatings presented ultra-high oil/water permeation flux of 26,000 L m(-2)h(- 1) bar( -1) with > 98% separation efficiency. Moreover, the coating exhibited exceptional chemical stability in acid and basic environment with excellent cycling stability. The simple methodology presented here will be expected to open up a new route for the fabrication of COFs based hybrid materials for wide range of applications.

Automated summary

The hybrid materials of covalent organic frameworks (COFs) and graphene oxide (GO) combine the advantages of both, improving the acid/base resistance of GO in water while overcoming the agglomeration tendency of COFs, making the materials more stable. The coatings fabricated using a simple method exhibit ultra-high oil/water separation efficiency and exceptional chemical stability.