Selective Molecular Sieving through Porous Graphene

TL;DR

This paper demonstrates that UV-induced oxidative etching can create nanopores in graphene membranes, enabling selective molecular sieving for gases based on size, with measurements aligning with theoretical models.

Contribution

It introduces a novel method for fabricating size-selective pores in graphene membranes using UV-induced oxidative etching, advancing membrane technology.

Findings

Pores created by UV etching allow selective gas permeation.

Leak rates and separation factors match effusion models.

Graphene membranes are mechanically robust and highly selective.

Abstract

Membranes act as selective barriers and play an important role in processes such as cellular compartmentalization and industrial-scale chemical and gas purification. The ideal membrane should be as thin as possible to maximize flux, mechanically robust to prevent fracture, and have well-defined pore sizes to increase selectivity. Graphene is an excellent starting point for developing size selective membranes because of its atomic thickness, high mechanical strength, relative inertness, and impermeability to all standard gases. However, pores that can exclude larger molecules, but allow smaller molecules to pass through have to be introduced into the material. Here we show UV-induced oxidative etching can create pores in micrometre-sized graphene membranes and the resulting membranes used as molecular sieves. A pressurized blister test and mechanical resonance is used to measure the transport of a variety of gases (H2, CO2, Ar, N2, CH4, and SF6) through the pores. The experimentally measured leak rates, separation factors, and Raman spectrum agree well with models based on effusion through a small number of angstrom-sized pores.