Unravelling intercalation-regulated nanoconfinement for durably ultrafast sieving graphene oxide membranes

Graphene oxide (GO) membranes with unique sieving channels composing of galleries in stacked GO nanosheets, are promising for advanced separations towards environmental and energy remediation. Although GO membranes can be bridged by molecules to enhance the stability as well as separation capacity, the subtle alterations of GO stacking and the resulting changes of sieving channel structures induced by molecular intercalation failed to be delicately revealed. Herein, molecular intercalations are employed to generate spatial confinement on GO assembling and thus the structures of sieving channels are regulated. Moreover, different-sized intercalants are demonstrated display significant effects on GO stacking. Small-sized molecules facilitate in-plane orientation while large-sized molecules are inclined to inhibit the overlap, leading to a lower degree of alignment and a shorter transmembrane pathway and eventually a higher permeability. On this basis, the deliberately nanostructured GO membrane with both the superior robustness even under ultrasonication and an ultrafast water permeance surpassing 5 times than pristine GO membrane, is built by intercalation with optimal-sized molecules. This study provides the practical insights on realizing 2D GO material for cutting-edge separations.