Transition Metal Dichalcogenide (TMD) Membranes with Ultrasmall Nanosheets for Ultrafast Molecule Separation

Two-dimensional (2D) transition metal dichalcogenide membranes have entered the spotlight for nanofiltration application owing to the novel mass transport properties in nanochannels. However, further improving the water permeability with high molecular separation rate simultaneously is challenging. In this work, to achieve ultrafast molecule separation, MoS2 and WS2 nanosheets with ultrasmall lateral size (<100 nm) are fabricated by sucrose-assisted mechanochemical exfoliation. Ultrasmall nanosheets in the membranes cut down average length of water-transporting paths and create more nanochannels and nanocapillaries for water molecules to pass through membranes. The water flux of these kinds of MoS2 and WS2 membranes are significantly enhanced to 918 and 828 L/m2 h bar, respectively, which is four and two times higher than those of previously reported MoS2 and WS2 membranes with larger lateral size nanosheets. In addition, MoS2 and WS2 membranes display excellent rejection performance for rhodamine B and Evans blue with a high rejection rate (∼99%). This study provides a promising method to improve the performance of 2D laminar membranes for nanofiltration application by using ultrasmall 2D nanosheets.