|Graphene structure. / Photo by: UCL Mathematical & Physical Sciences via Flickr|
Graphene is a layer of carbon that is one atom thick and is considered to be one of the strongest materials on Earth. It is also highly conductive and flexible compared to most materials. Now, it can be used for separating mixed gases in the air.
A team of researchers at the Ecole Polytechnique Federale de Lausanne refer to graphene as an ultimate membrane to separate gases. Their breakthrough study dealt with two major problems in making graphene as a gas separating membrane – the lack of effective methods for incorporating molecular-sized pores in the material’s layer and the lack of correct of techniques to produce robust, crack-free, and tear-free large area membranes.
Artificial membranes like polymers are employed for gas separation. When these membranes separate gases, toxic elements are removed from natural gas, recover hydrogen from ammonia plants, and enrich the quality of air in metal industries.
In the study, the graphene membrane was made with nanopores that enabled hydrogen to spread through in a process called gas-sieving. The membrane was found stable in industrial pressures and temperatures. The team was able to produce a membrane with a surface of one square millimeter without cracks and tears, which is larger compared to other graphene membranes produced.
"The novel technique to produce crack-free graphene layer will go a long way in realizing the ultimate performance of the atom-thick graphene membranes for a number of important chemical separations including carbon capture, hydrogen recovery, and the purification of clean drinking water," explained Kumar Varoon Agrawal, lead author of the study at EPFL.
The team is now improving the graphene membrane and incorporating higher density of nanopores into the material to increase its potential for gas separation. A successful commercial variant of this membrane may help combat air pollution.