Chemically Bonded Graphene Oxide/Covalent Organic Framework Nanosheets as Robust Membranes for Fast Desalination

Graphene oxide (GO) is widely used to prepare 2D laminar separation membranes because of its single atomic thickness and good processability. However, due to the tortuous transport path and excessive swelling effect, it is difficult to improve permeability, salt rejection, and stability of GO membranes simultaneously. Herein, we chemically laminated GO with covalent organic framework nanosheets (CONs) to fabricate membranes for fast and stable desalination. GO and CONs are first vacuum-filtrated and then heated, obtaining chemically bonded GO/CON (c-GO/CON) laminar membranes. CONs provide additional short transport pathways through intrinsic in-plane pores and stabilize interlayer channels by forming chemically cross-linked networks with GO. As a result, rapid transmembrane water permeation and improved desalination performances are achieved. Moreover, the prepared c-GO/CON membranes show excellent stabilities in filtration processes with complex environments, such as acidic and basic conditions, elevated pressures, concentrated salinities, and long-term operations. This study provides a new idea for the preparation of high-performance graphene-based nanofiltration membranes.