Tunable, strain-controlled nanoporous phosphorene membrane for highly efficient and selective H2/CH4 and H2/CO2 sieving: A combined molecular dynamics simulation and density functional theory study

Abstract

Using a combined approach of molecular dynamics simulation and density functional theory, we develop a phosphorene nanopore to realize the tunable H2 sieving from mixtures with CH4 or CO2 via introducing the in-plane tensile strain. Our results show that 0%–10% strains exerted on the phosphorene membrane ensures a fast permeation of H2 while completely prohibiting the passage of CH4, demonstrating high efficiency and selectivity. Thanks to the outstanding mechanical flexibility of phosphorene, the strain tension can be utilized to easily control the pore size by which the permeance speed of H2 can be controlled in real time. However, all strained pores allow the passage of CO2, indicating a weaker strain regulation for H2/CO2 sieving by the phosphorene pore. Density functional theory calculations further confirm that the transport of H2 is energetically more favorable than CH4 and CO2 to traverse all phosphorene pores. Our findings exploit a flexible phosphorene membrane for real-time tunable H2/CH4 separation by controlling the in-plane strain.