  Graphyne-4 sheet exhibits promising potential for nanoscale desalination to
achieve both high water permeability and salt rejection rate. Extensive
molecular dynamics simulations on pore-size effects suggest that graphyne-4,
with 4 acetylene bonds between two adjacent phenyl rings, has the best
performance with 100% salt rejection and an unprecedented water permeability,
to our knowledge, of ~13L/cm2/day/MPa, about 10 times higher than the
state-of-the-art nanoporous graphene reported previously (Nano Lett.s 2012, 12,
3602-3608). In addition, the membrane entails very low energy consumption for
producing 1m3 of fresh water, i.e., 3.6e-3 kWh/m3, three orders of magnitude
less than the prevailing commercial membranes based on reverse osmosis. Water
flow rate across the graphyne-4 sheet exhibits intriguing nonlinear dependence
on the pore size owing to the quantized nature of water flow at the nanoscale.
Such novel transport behavior has important implications to the design of
highly effective and efficient desalination membranes.
