The defective C3N monolayers as high-efficient hydrogen purification membranes: DFT calculations and MD simulations

Abstract

The design of new high-performance membranes for separation and purification of hydrogen remains highly desirable for industrial applications. Herein, using the density functional theory calculations along with MD simulations, we demonstrated firstly a new 2D membrane based C3N monolayer (D-C3N) with intrinsic pores and then investigated its potential as gas separation membranes for H2 purification. The cohesive energy and ab initio MD simulations confirmed that the D-C3N monolayer is structurally and thermodynamically stable under 1800 K. All considered gas molecules are physisorbed on the D-C3N monolayer with small interaction energy. At room temperature, the D-C3N membrane for H2 gas has high selectivity over other gases such as 1.5 × 103, 1.8 × 105, 8.8 × 109, 1.4 × 1012, and 1.3 × 1019 for H2/N2, H2/CO2, H2/O2, H2/H2O, and H2/CH4 at 300 K, respectively, and the H2 permeance is as high as 2.2 × 10−5 mol·m−2·s−1·Pa−1, exceeding the industrially acceptable value and most of the carbon-based separation membranes. In addition, MD simulations further confirmed that the defective porous C3N monolayer has ideal selectivity and permeation as a promising separation membrane for H2 purification from other gases for industrial applications.