Functional group-directed self-installing doors in porous graphene: a theoretical study

Abstract

The pores in porous graphene sheets are usually passivated by atoms and functional groups including H, N, F, and OH. It is expected that some small molecules can adsorb with sufficient strength to the functionalized pores to change their properties, which can be undone by heating. We have employed the density functional theory simulations to verify that CF3CH2OH molecules can strongly adsorb to pores passivated by both N and H atoms (e.g. the pore16-1N1 model). Actually, the CF3CH2OH molecule can be used as a self-mounting “gate” to reversibly adjust the shape, size, and separation property of the pore. For example, the gas mixture (H2, CH4, n-C4H10, and i-C4H10) passing freely through a pore with diameter of 7–8 A can now be separated by pre-adsorbing a CF3CH2OH molecule. Larger components such as n-C4H10, and i-C4H10 are completely blocked, and the small mixture of H2/CH4 can be well separated with a selectivity of 1011:1. The “self-installing door” mechanism opens up a new way to flexibly transform large pores according to the needs.