skip to main content

DOE PAGESDOE PAGES

Title: Ion-Gated Gas Separation through Porous Graphene

Porous graphene holds great promise as an atom-thin, high-permeance membrane for gas separation, but to precisely control the pore size at three to five angstroms proves challenging. Here we propose an ion-gated graphene membrane comprising a monolayer of ionic liquid coated porous graphene to dynamically modulate the pore size to achieve selective gas separation. This approach enables the otherwise non-selective large pores on the order of 1 nm in size to be selective for gases whose diameters range from three to four angstroms. We show from molecular dynamics simulations that CO 2, N 2 and CH 4 all can permeate through a 1-nm pore in graphene without any selectivity. But when a monolayer of [emim][BF 4] is deposited on the porous graphene, CO 2 has much higher permeance than the other two gases. We find that the anion dynamically modulates the pore size by hovering above the pore and provides affinity for CO 2 while the larger cation (which cannot go through the pore) holds the anion in place via electrostatic attraction. This composite membrane is especially promising for CO 2/CH 4 separation, with a CO 2/CH 4 selectivity of about 42 and CO 2 permeance ~105 GPU (gas permeationmore » unit). We further demonstrate that selectivity and permeance can be tuned by the anion size. The present work points toward a promising direction of using the atom-thin ionic-liquid/porous-graphene hybrid membrane for high-permeance, selective gas separation that allows a greater flexibility in substrate pore size control.« less
Authors:
 [1] ;  [2] ; ORCiD logo [3] ; ORCiD logo [1]
  1. Univ. of California, Riverside, CA (United States)
  2. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
  3. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Univ. of Tennessee, Knoxville, TN (United States)
Publication Date:
Grant/Contract Number:
AC05-00OR22725
Type:
Accepted Manuscript
Journal Name:
Nano Letters
Additional Journal Information:
Journal Volume: 17; Journal Issue: 3; Journal ID: ISSN 1530-6984
Publisher:
American Chemical Society
Research Org:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
OSTI Identifier:
1348344