Nanoporous two-dimensional MoS2 membranes for fast saline solution purification

Abstract

Finding a membrane with both high permeability and high salt rejection is very important for saline solution purification. Here, we report the performance of molybdenum disulfide (MoS₂) membranes with nanoscale pores for saline solution purification via all-atom molecular dynamics simulations. It was found that the nanoporous two-dimensional MoS₂ membrane can impede salt ions, while allowing highly efficient permeation of water molecules. By engineering the appropriate sizes of the nanopores within two-dimensional MoS₂ membranes, their water permeability can be tens of times as high as that of conventional reverse osmosis membranes, while still maintaining a high salt rejection rate. These remarkable water permeability and salt rejection properties of the nanoporous monolayer MoS₂ membranes are attributed to the formation of single chain hydrogen bonds, which link the water molecules within the nanopores and those at the immediate exteriors of the nanopores, causing significant reduction in the resistance of water molecules passing through the nanopores, which are small enough for any salt ions to pass through. Therefore such nanoporous monolayer MoS₂ membranes have great potential for saline solution purification.