Side-Chain-Dependent Functional Intercalations in Graphene Oxide Membranes for Selective Water and Ion Transport

Subnanometer interlayer space in graphene oxide (GO) laminates is desirable for use as permselective membrane nanochannels. Although the facile modification of the local structure of GO enables various nanochannel functionalizations, precisely controlling nanochannel space is still a challenge, and the roles of confined nanochannel chemistry in selective water/ion separation have not been clearly defined. In this study, macrocyclic molecules with consistent basal plane but varying side groups were used to conjunct with GO for modified nanochannels in laminates. We demonstrated the side-group dependence of both the angstrom-precision tunability for channel free space and the energy barrier setting for ion transport, which challenges the permeability–selectivity trade-off with a slightly decreased permeance from 1.1 to 0.9 L m^–2 h^–1 bar^–1 but an increased salt rejection from 85% to 95%. This study provides insights into the functional-group-dependent intercalation modifications of GO laminates for understanding laminate structural control and nanochannel design.