A study of the permeation barrier of nanoporous Graphene

Abstract

Nanoporous Graphene, due to its single atom thickness and good mechanical strength is an emerging candidate for efficient and reliable gas separation applications. The permeation of the gas molecules through the pores can be seen as an activated process, whereby the gas molecules have to overcome a threshold barrier before it can pass through the pore. Here, we study and compare the Single Point Energy of the CO2 molecule as it approaches a nanoporous Graphene sheet comprising of 6 Carbon atoms removed contiguously to create what is known as the Type A nanopore. The distance of the single molecule from the pore is varied continuously for 2 configurations of the gas molecule, one parallel and other perpendicular to the nanopore, positioned vertically above the centre of the 6-pore, by means of ab-initio simulations based on Density Functional Theory. The permeation barrier of the CO2 molecule is estimated. It is found that orientation of incident molecule along with the pore geometry, plays an important role in gas permeation and penetration barriers, and thereby in all applications that crucially depend upon the rate of gas permeation, like gas separation for example.