Rational Design and Strain Engineering of Nanoporous Boron Nitride Nanosheet Membranes for Water Desalination

Through systematic molecular dynamics simulations we theoretically investigate the potential applications of hexagonal boron nitride (h-BN) for seawater desalination. Our results indicate that the rationally designed h-BN membranes have great permeability, selectivity, and controllability for water desalination. The size and chemistry of the pores are shown to play an important role in regulating the water flux and salt rejection. Pores with only nitrogen atoms on the edges have higher fluxes than the boron-lined pores. In particular, two-dimensional h-BN with medium-sized N4 pores show 100% salt rejection with outstanding water permeability, which is several orders of magnitude higher than that of conventional reverse osmosis membranes. Furthermore, we study the mechanical strain effect on the desalination performance of monolayer h-BN with relatively small N3 pores, suggesting that water flux and salt rejection can be precisely tuned by tensile strain. The findings in the present work unambiguously propose that porous boron nitride nanosheets are quite promising as new functional membranes for water desalination.