Abstract
Membrane separation technology plays an important role in various fields including water treatment, chemicals and gas separation for numerous industrial fields, and food processing. There has been a renewed focus on two-dimensional(2D) materials for membrane application since their atomic thicknessand confined interlayer spacing could theoretically lead to enhanced separative performances. Either the single nanosheets themselves, or the stackingof multiple sheets can form selective membranes. The multilayer assembly of single nanosheets – forming nanolaminate membranes – creates 2D capillaries(or nanochannels) that can efficiently sieve chemical species depending ontheir size.Recent examples have been reported in the literature demonstrating the potential of 2D materials as multi- or single-layer membranes for molecular sieving(222; 260; 466; 204), gas separation (219; 246; 190), energy harvesting (467)and water desalination (198; 194).Among the different building blocks of nanolaminate membranes made of two-dimensional materials (2D), graphene oxide (GO) has been studied as a candidate for molecular sieving via size-limited diffusion in the 2D capillaries (222). Unfortunately the high hydrophilicity of GO nanosheets makes GO membranes unstable in water, while the poor control of the capillary width between the nanosheets limits the water permeance of the membranes. Other 2D materials such as exfoliated nanosheets of transition metal dichalcogenides (TMDs)constitute attractive platforms for the realization of nanolaminate membranes.Recent works carried out on nanolaminate membranes made of molybdenum disulfide (MoS2) have demonstrated improved stability (3). Within this thesis we have studied the performance of a novel type of MoS2 nanolaminate membranes with well-controlled surface chemistry of the nanosheets (14). Inorder to assess the role of surface chemistry, we explored the impact of covalent functionalization on molecular sieving toward water purification (i.e. desalination and micropollutant removal) (14). Our results open novel directions to finely tune the sieving behavior of membranes based on 2D materials.