Constructing 2D ultrathin graphene oxide membranes with supramolecular-assembled nano-adhesives for enhancing water stability

Atomic-thick two-dimensional (2D) graphene oxide (GO) has emerged as an ideal building block in developing ultrathin 2D membranes for separating substances. However, due to the negative charge of GO sheets when hydrated, electrostatic repulsion causes GO membranes to disintegrate easily in water, limiting their wide application in aqueous solutions. Here, we introduce and apply the concept of localized gluing by designing ultra-small supramolecular-assembled nanoparticles as nano-adhesives (NPA) to construct robust GO membranes with a thickness of only 24 nm. The supramolecular-assembled NPA were synthesized by cyclodextrin (CD) and tannic acid (TA) with a uniform size distribution of about 4.5 nm, and exposed surface pyrogallols that could strongly interact with GO sheets. The physical sizing of the NPA confines the interlayer spacing and maintains the nanochannel, while the natural molecular properties of the NPA enhance the connection between adjacent layers and inhibit swelling detachment. The fabricated ultrathin 2D membranes show a remarkable two times enhancement of water permeance over pristine GO membranes and exhibit excellent durability with record-breaking stability for 720 h immersion in water. This strategy provides meaningful insights into the design and fabrication of robust ultrathin membranes for practical application.