Vacancy Functionalized MoS2 Nanolaminated Membranes for Efficient Sieving in Forward Osmosis

Abstract 2D transition‐metal dichalcogenides (TMDs) based nanolaminates are promising candidates for water purification. However, fabricating nanochannels with tunable capillary widths remain a challenge. This study proposed a sulfur vacancy functionalization strategy for fabricating high performance nanolaminate membranes by grafting three kinds of thiol (S‐H) containing molecules (Cysteine, 3‐Mercapto‐1,2‐propanediol, 1‐Propanethiol) on MoS 2 nanosheets, in which propanethiol functionalized MoS 2 membrane exhibited best salt rejection (99.3%) and water/salt selectivity (800 bar −1 ) in forward osmosis (draw solution: sucrose solution). It is found the capillary width increased from 0.2 Å in pristine MoS 2 to ≈5 Å in propanethiol functionalized MoS 2 membranes. Numerical simulations suggest that nanofluidic properties of the functionalized membranes are governed by the fundamental interaction between water and the corresponding S‐H functional group, and the interlayer distance. Importantly, since the S‐H containing molecules can repair MoS 2 nanosheets by fitting into the sulfur vacancies, the stability of the membranes is also improved with minimal swelling, which is promising for their practical applications.