Scientists have succeeded in controlling chirality by more than 50 per cent in carbon nanotubes, thereby bringing much closer the possibility of using nanotubes in commercial manufacture of electronic applications.
Specifically, single-walled carbon nanotubes with controlled chiralities of more than 50 per cent were grown during chemical vapour deposition synthesis by scientists from Aalto University in Finland, in collaboration with Russian and Danish scientists.
Controlling chirality has long been a central goal in carbon nanotube (CNT) research, because it is considered key to enabling the commercial exploitation of CNTs for a whole myriad of practical applications.
Indeed, CNTs are tipped to one day outstrip silicon use in the production of integrated circuit computer chips, due to the technology’s more advanced properties of being smaller, faster and more power efficient than silicon transistors.
But a big limitation which held back development for the past decade was the lack of the ability to control chirality
Chirality defines the optical and electronic properties of carbon nanotubes, and can be thought of in the way you would roll up a sheet of A4 paper - if you rolled it straight up into a tube, it would have a certain chirality. If you rolled it up at an angle, it would have a different chirality.
“Yes, this is how we explain the SWNT structure, by rolling the graphene sheet in varying manner with respect to sheet orientation and width,” says Prof. Dr. Esko Kauppinen, Chair, Aalto University School of Science, Department of Applied Physics.
Up until now it has proven difficult to control the manufacture of CNTs in a predictable way, to the correct diameter, type and ultimately chirality needed for use in, for example, computers.
Scientists all over the globe have been busy trying to invent a system that consistently produces carbon nanotubes of a predictable diameter and chirality.
“There are so many methods to synthesise single-walled carbon nanotubes (SWNTs) that no time, space and need to report all of those here,” says Kauppinen. But what his team has managed is “control of tube chirality which is better than published earlier,” with more than 50 per cent of the semiconducting tubes being the same, one kind.
CNTs have been referred to as the wonder material of the 21st century, because there are so many applications of the technology. These include as supercapacitors (replacing batteries in cars for example), or as efficiency-enablers for materials like solar cells, plastics, fuel cells or electric generators.
CNTs can also be used for water and oil purification, in synthetic muscles and bone scaffolding, for cell therapy and to create better displays in flat screens, LEDs and flexible displays.