Tuning the Transport Properties of Gases in Porous Graphene Membranes with Controlled Pore Size and Thickness. Issue 5 (12th December 2021)

• Record Type: Journal Article
• Authors: Ashirov, Timur; Yazaydin, A. Ozgur; Coskun, Ali
• Is Part Of: Advanced materials. Volume 34:Issue 5(2022)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2021-12-12
• Subjects: graphene membranes -- H 2 permeation -- H 2/CO 2 separation -- pore tuning; Materials -- Periodicals; Chemical vapor deposition -- Periodicals; 620.11
• DOI: 10.1002/adma.202106785
• Languages: English
• ISSNs: 0935-9648

Abstract

Abstract: Porous graphene membranes have emerged as promising alternatives for gas‐separation applications due to their atomic thickness enabling ultrahigh permeance, but they suffer from low gas selectivity. Whereas decreasing the pore size below 3 nm is expected to increase the gas selectivity due to molecular sieving, it is rather challenging to generate a large number of uniform small pores on the graphene surface. Here, a pore‐narrowing approach via gold deposition onto porous graphene surface is introduced to tune the pore size and thickness of the membrane to achieve a large number of small pores. Through the systematic approach, the ideal combination is determined as pore size below 3 nm, obtained at the thickness of 100 nm, to attain high selectivity and high permeance. The resulting membrane shows a H2 /CO2 separation factor of 31.3 at H2 permeance of 2.23 × 10 5 GPU (1 GPU = 3.35 × 10 −10 mol s −1 m −2 Pa −1 ), which is the highest value reported to date in the 10 5 GPU permeance range. This result is explained by comparing the predicted binding energies of gas molecules with the Au surface, −5.3 versus −21 kJ mol −1 for H2 and CO2, respectively, increased surface–gas interactions and molecular‐sieving effect with decreasing pore size. Abstract : Gas‐separation membranes based on porous graphene (PG) offer ultimate permeance; however, they show low selectivity. The pore‐narrowing approach, via gold deposition onto PG, allows both the thickness and the pore size of the membrane to be tuned to obtain a high number of pores below 3 nm, enabling increased gas–surface interactions and molecular sieving for high gas selectivity and permeance.