Fast water transmission of zigzag graphyne-3 nanotubes

Abstract

We report the molecular dynamics simulation of water molecules permeating quickly through the wall of zigzag graphyne-3 nanotubes (G3NT (N, N) (N = 2, 3, 4, and 6)), the water fluxes are about 5 orders of magnitude higher than that of the commercial forward osmosis membranes. High water fluxes are attributed to the capillarity of G3NT (N, N) nanotubes and the huge osmotic pressure difference between feed solution and draw solution. Furthermore, the nanotube walls can highly intercept salt ions. The counter diffusion phenomenon, where water molecules permeate through the nanotube wall from draw solution side (inside) to feed solution side (outside) of G3NT (N, N) nanotubes, is much weaker than that of two-dimensional monolayer graphyne-3, so higher net water fluxes can be achieved. Besides, the diffusion rates of water molecules along the axis of G3NT (N, N) nanotubes are about 2 orders of magnitude higher than that of water molecules without limited space owing to the formation of a hydrogen bonding network. G3NT (N, N) nanotubes are promising to be used in water treatment or controlled drug release.