Graphene-based materials, primarily graphene oxide (GO), have shown excellent separation and purification characteristics. Precise molecular sieving is potentially possible using graphene oxide-based membranes, if the porosity can be matched with the kinetic diameters of the gas molecules, which is possible via the tuning of graphene oxide interlayer spacing to take advantage of gas species interactions with graphene oxide channels. Here, highly effective separation of gases from their mixtures by using uniquely tailored porosity in mildly reduced graphene oxide (rGO) based membranes is reported. The gas permeation experiments, adsorption measurement, and density functional theory calculations show that this membrane preparation method allows tuning the selectivity for targeted molecules via the intercalation of specific transition metal ions. In particular, rGO membranes intercalated with Fe ions that offer ordered porosity, show excellent reproducible N2/CO2 selectivity of ≈97 at 110 mbar, which is an unprecedented value for graphene-based membranes. By exploring the impact of Fe intercalated rGO membranes, it is revealed that the increasing transmembrane pressure leads to a transition of N2 diffusion mode from Maxwell–Stefan type to Knudsen type. This study will lead to new avenues for the applications of graphene for efficiently separating CO2 from N2 and other gases.
Bibliographical noteFunding Information:
This work was supported by UNSW SMaRT Centre facilities. R.J. and X.J. thank Dr. Irshad Mansuri for providing technical help for their research. X.J. acknowledges Dr. Emma Lovell for her support in adsorption measurements. X.J. acknowledges the Ph.D. scholarship from Tyre Stewardship Australia. The authors would like to acknowledge the facilities at Mark Wainwright Analytical Centre. G-H.L. acknowledges the support from the Korea Institute of Energy Technology Evaluation and Planning (KETEP) and the Ministry of Trade, Industry & Energy (20173010013340) and the National Research Foundation of Korea (NRF) funded by the Ministry of Science, ICT & Future Planning (2018M3D1A1058794 and 2016M3A7B4910940) of the Republic of Korea. ARC Centre of Excellence in Future Low-Energy Electronics Technologies (CE170100038).
All Science Journal Classification (ASJC) codes
- Materials Science(all)
- Mechanics of Materials
- Mechanical Engineering