Ultrafast permeation of seawater pervaporation using single-layered C2N via strain engineering

Abstract

Emerging two-dimensional (2D) ultra-thin nanomaterials are ideal candidates for next-generation high-throughput membranes. 2D carbon nitride C₂N possesses intrinsic regular and uniformly distributed sub-nanometer pores which probably allow a high permeation flux. This work reports on the investigation of seawater pervaporation through a single-layered C₂N membrane via a combined approach of first-principles calculations and molecular dynamics simulations. The C₂N layer remains stable when the strain is less than a threshold point of 12% at which the pore size is enlarged by 50%. The strained C₂N membrane only allows water molecules from seawater to permeate, and the water flux in C₂N is enhanced by one to four orders of magnitude compared to that in other membranes. The water flux exhibits an Arrhenius-type relation with temperature. The hydrogen-bonding interaction among water molecules in C₂N is weaker and decays faster than that in bulk water, which is because it is energetically unfavorable for water molecules to enter C₂N. This proof-of-concept study suggests that C₂N might be an appealing membrane material for seawater pervaporation.