SEMANTICS: Exfoliating monolayers: opening a gateway to industrial solutions
Prof. Coleman first demonstrated how to create nanomaterials in this way by producing graphene – one atom thick monolayers of carbon with unique electronic properties. He showed that subjecting bulk graphite to sonic energy while suspended in a liquid causes carbon monolayers to ‘exfoliate’ from the graphite. This produces a liquid dispersion of graphene monolayer flakes. In 2010, he received an ERC Starting Grant to expand his award-winning research and demonstrate its wider potential. Indeed, it would take the weight of an elephant balanced on a pencil to break through a sheet of graphene the thickness of cling film. Prof. Coleman’s team is now applying this technology to many other industrially important materials, for example by exfoliating monolayers of tantalum sulphide, a metallic conductor; boron nitride, an insulator; and molybdenum disulphide (MoS2), a semiconductor. These form the building blocks for nanoelectronics applications – but the significant element is that it is done in the liquid phase. So by allowing the suspended monolayers to settle out onto a surface and form a continuous film, the team are producing stacked layers of conducting, insulating and semiconducting films, of controlled thickness and with well-defined electrical and optical properties – from which a host of devices such as semiconductors and detectors can be manufactured in bulk. And the potential of this research is not only in electronics. Monolayers of molybdenum disulphide are 20 times stronger than steel, so it can be used to strengthen other materials, such as plastics, which are also processed in liquid solvents. Prof. Coleman’s team have demonstrated exactly this by co-depositing a small amount of MoS2 with an everyday polymer plastic – which more than doubled its strength! Plastics are ubiquitous in structural applications – for example as car components. So doubling the strength means that half the material is needed – reducing the amount of oil required to produce plastics in the first place, and reducing the weight, and thus the emissions from cars. This is why Prof Coleman’s research is described as a ‘gateway technology’ – if they can demonstrate industrially tractable applications, then the potential take-up is enormous. In advance of his TEDx talk, Prof. Coleman said: "I am very much looking forward to sharing the latest developments in material science with the audience at TEDx. The discovery of graphene has opened a door to countless potential real-world applications and I think the people at TEDx will find the prospect of creating two-dimensional monolayers of a variety of materials as exciting as I do!" Listen to Prof. Coleman discuss these developments during the TEDx Brussels ERC session at 2.15 pm.
Keywords
SEMANTICS, exfoliation, monolayers, nanomaterials, graphene