Nanoporous MoS₂ Membrane for Water Desalination: A Molecular Dynamics Study

Molybdenum disulfide (MoS₂), a two-dimensional (2D) material, promises better desalination efficiency, benefiting from the small diffusion length. While the monolayer nanoporous MoS₂ membrane has great potential in the reverse osmosis (RO) desalination membrane, multilayer MoS₂ membranes are more feasible to synthesize and economical than the monolayer MoS₂ membrane. Building on the monolayer MoS₂ membrane knowledge, the effects of the multilayer MoS₂ membrane in water desalination were explored, and the results showed that increasing the pore size from 3 to 6 Å resulted in higher permeability but with lower salt rejection. The salt rejection increases from 85% in a monolayer MoS₂ membrane to about 98% in a trilayer MoS₂ membrane. When averaged over all three types of membranes studied, the ions rejection follows the trend of trilayer > bilayer > monolayer. Besides, a narrow layer separation was found to play an important role in the successful rejection of salt ions in bilayer and trilayer membranes. This study aims to provide a collective understanding of this high permiselective MoS₂ membrane's realization for water desalination, and the findings showed that the water permeability of the MoS₂ monolayer membrane was in the order of magnitude greater than that of the conventional RO membrane and the nanoporous MoS₂ membrane can have an important place in the purification of water.