Multiscale Simulation Of Two-dimensional Materials（C₂N And Ti₃C₂） For Gas Mixtures Separation

Due to the prominent energy and environmental problems nowadays,gas separation has become an important research project in the field of chemical industry and environment.Gas membrane separation technology has the advantages of high separation efficiency,low energy consumption,low investment,small area of equipment and simple process,and the development of new membrane materials with high selectivity and permeability is the key to the wide application of this technology.Especially in recent years,the new two-dimensional membrane material is expected to become an efficient separation membrane material.In this work,by combining density functional theory and molecular dynamics simulation,the separation performance of C₂N（different tensile strength）materials with natural nanopores and multilayer Ti₃C₂two-dimensional material is studied.In the simulation,a new idea of single film with biaxial stretching is adopted to separate the gas mixture,and for the multilayer system,the diffusion rate of gas molecules is changed by the surface modification with functional groups on Ti₃C₂,thus the effective diffusion separation of the gas is realized.The simulation results are in good agreement with experimental or theoretical results,providing theoretical guidance for experiments.The research contents are mainly divided into two parts:（1）We use porous C₂N two-dimensional membrane under ditensile strength to separate O₂/CO₂/CO gas mixture.The results indicate that the permeability of the gas increases with the increase of the tensile degree of the porous C₂N-h2D.When the strain tension is controlled at 10%,the porous C₂N can efficiently separate CO and maintain the high permeability of O₂.This material is likely to be applied to the cathode of PEMFC.Importantly,this strain control strategy can be applied to various 2D membrane materials in gas separation.（2）This paper also use multi-layer MXenes material to separate H₂/N₂/NH₃ gas mixture,it reaches the efficient separation of NH₃ by regulating the surface structure and the interval of the MXenes.We found that-COOH and-O modified MXenes strongly adsorb NH₃,and it can achieve better separation effect.At the same time,this paper also uses multi-layer MXenes material to separate CO₂/N₂ gas mixture,it achievese efficient separation of CO₂ by regulating the surface modified functional groups and interlayer spacing of the MXenes.