Yuwadee Suwan, Sirichok Jungthawan, and Sukit Limpijumnong
1 School of Physics and NANOTEC-SUT Center of Excellence on Advanced Functional Nanomaterials, Suranaree University of Technology, Nakhon Ratchasima 30000, Thailand 2 Synchrotron Light Research Institute, Nakhon Ratchasima 30000, Thailand 3 Thailand Center of Excellence in Physics (ThEP), Commission on Higher Education, Bangkok 10400, Thailand
The gas separation properties of porous graphene (PG) membrane on SiO2 substrate for simple molecules (H2, O2, and CO2) under pressure have been investigated by using first-principles density functional theory. The van der Waals interaction was taken into account by using Grimme’s force field (PBE-D2) approach . For the clamped circular membrane subjected to a pressure difference between both sides of the membrane, the deformation of the membrane can be described by Hencky’s solution . The deformation of the membranes lowers the diffusion barriers for H2, O2 and CO2 but by different amounts. This effectively increases the diffusion rate of H2, O2, and CO2 by up to 4, 8, and 12 orders of magnitude, respectively (in the pressure range of 0-5 MPa). The selectivity or relative diffusion rate of PG for the diffusion of H2, O2, and CO2 molecules at
Deltap = 5 MPa relative to the CO2 diffusion rate at Delta p = 0 MPa are 1024, 1019, and 1012, respectively. The results suggest that the gas separation properties of PG can be tuned by applying a pressure different across the membrane.
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