Graphene oxide membranes with an enlarged interlaminar nanochannel through functionalized quantum dots for pervaporative water-selective transport

Abstract

Graphene oxide (GO) lamellar membranes, featuring ultrafast water transport character, have attracted great attention in the water-selective molecular separations. The incorporation of intercalators into GO has been recognized as an effective strategy to construct favorable physicochemical properties of interlaminar nanochannels. General intercalators have been used to acquire narrowed interlaminar nanochannels with sieving effects, which is not conducive to permeation. The creation of well-defined interlaminar nanochannels for precise molecular separations without the compromise of the permeation is still a great challenge. Herein, the functionalized quantum dots (FQDs) were incorporated to regulate the physicochemical properties of interlaminar nanochannels for the high-efficient molecular separation. FQDs serving as rigid nano-wedges could enlarge the interlaminar nanochannels for ultrafast molecular transport. The hydrophilic functional groups in FQDs facilitate the selective transport of water molecules in the interlaminar nanochannels. The optimized GO-FQDs/PTFE membrane realizes an outstanding permeation flux of 8877.8 g/(m2 h) and a desirable separation factor of 3763 when processing 90 wt% n-butanol aqueous solution at 80 °C, demonstrating a performance superior to the GO-based laminar membranes ever reported. Additionally, the cross-linking interaction induced by FQDs exhibits improved swelling resistance, and the separation performance remains stable over 144 h under the long-term operation test. This study provides a promising prospect of using versatile nanomaterials as intercalators to construct appropriate interlaminar nanochannel microenvironments to achieve the ultra-permeable and selective molecular separations.