# Tuning Pore Size in Porous Graphene Membrane for O2/N2 Separation

## TL;DR

Researchers developed a way to adjust graphene pores to efficiently separate oxygen from nitrogen, which could lead to more energy-efficient oxygen production.

## Contribution

A dynamic strategy to tune pore size in N-functionalized graphene for selective O2/N2 separation is introduced.

## Key findings

- O2 permeance reaches 2500 GPU with O2/N2 selectivity above 10.
- The method outperforms state-of-the-art membranes for gas separation.
- The approach enables energy-efficient oxygen production from air.

## Abstract

Graphene with angstrom‐scale, zero‐dimensional pores offers a promising platform for gas separations due to its exceptional permeance and potential for molecular sieving. Herein, we demonstrate a dynamic strategy to tune N‐functionalized graphene pores, achieving selective oxygen (O2) separation from nitrogen (N2), a particularly challenging separation due to their similar kinetic diameters. We exploit the heterogeneity of functional groups at the pore edge to tune the pore limiting diameter (PLD). By facile thermal annealing, we convert primary amine groups at the pore edge to lattice‐incorporated nitrogen. Temperature‐dependent extent of conversion allows to tune the steric hindrance from amine‐CO2 complex, and therefore, PLD for O2/N2 separation in favor of O2 permeation. The resulting membranes exhibit attractive O2/N2 separation performance, with O2 permeance near 2500 GPU with O2/N2 selectivity above 10, significantly outperforming the state‐of‐the‐art membranes. This is attractive for energy‐efficient and modular production of O2 from air and can cut down fuel consumption in natural gas‐fired furnaces in the chemical industry by 60%.

Single‐layer graphene membranes featuring N‐functionalized, 0D pores offer a promising platform for O2/N2 separation. The heterogeneity of functional groups at the pore edge is dynamically tunable, enabling precise tuning of the pore limiting diameter and gas transport. This strategy achieves attractive performance, with O2 permeance approaching 2500 GPU and O2/N2 selectivity exceeding 10, highlighting the potential for energy‐efficient air separation.