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SFI Researcher of the Year 2011
Professor Jonathan Coleman wins SFI Researcher of the Year 2011
Adaptive Nanostructures and Nanodevices
Working with 21st century materials
When the European Research Council (ERC) announced the award of a €1.5 million ERC Starter Grant to Professor Jonathan Coleman of the School of Physics, Trinity College Dublin it was recognition for the ground breaking work he and his team have been doing on the development of next generation materials at the Science Foundation Ireland (SFI) funded Centre for Research on Adaptive Nanostructures and Nanodevices (CRANN).
The prestigious grants recognise scientists who are working on research with major potential and are awarded to only 300 top scientists across Europe, representing less than 10% of those who apply. More recently Prof Coleman work has been acknowledged with his announcement as the SFI Researcher of the Year 2011.
Prof Coleman’s main research theme is the study of one-dimensional nanostructures including carbon nanotubes and inorganic nanowires. The major breakthrough with which he has been associated is a new way of splitting layered materials to give atomically thin “nanosheets”.
This has led to a range of novel two-dimensional nanomaterials with chemical and electronic properties that have the potential to enable new electronic and energy storage technologies as well as new super-strong plastics. The collaborative international research project was led by CRANN and the School of Physics in TCD and the University of Oxford.
Coleman and his team invented a versatile method for creating these atomically thin nanosheets from a range of materials using common solvents and ultrasound, utilising devices similar to those used to clean jewellery. The new method is simple, fast, and inexpensive, and could be scaled up to work on an industrial scale.
The research has been compared to the work regarding the two-dimensional material graphene, which won the Nobel Prize in 2010. Graphene has generated significant interest because when separated into individual flakes, it has exceptional electronic and mechanical properties that are very different to those of its parent crystal, graphite. However, graphite is just one of hundreds of known layered materials, some of which may enable powerful new technologies.
“A nanomaterial is defined as a material that has a size in at least one dimension of less than 100 nm”, Prof Coleman explains. “For example, a nanotube made of carbon could be up to one centimetre long but its diameter would be incredibly small. It is a quasi-one-dimensional material. Quasi-two-dimensional materials are nanosheets which have a thickness of one nanometre and therefore might as well be two dimensional they are so thin. A human hair is 50,000 times as thick as a nanotube, for example.”
Graphene is one of these two-dimensional materials and it is its strength that makes it so interesting and useful. “It is the strongest material known to man”, Coleman points out. “It is 100 times stronger than steel.”
He explains that this is important for the development of new composite materials. Similar to the use of steel reinforced concrete in buildings or glass fibre reinforced plastics in other applications the immensely strong graphene sheets can be used to strengthen other existing materials.
“Take a polyester Coke bottle for instance”, he notes. “We make these by the hundreds of millions every year. If we were to add half of one percent of a current bottles weight in graphene we would triple its strength. That would enable us to use far less plastic in their manufacture. When you think about how much stuff is made of plastic and how much oil that consumes you get some idea of the potential importance of a material like graphene in terms of environmental savings.”
And the potential applications as a structural material only start there. “Why do cars have to be made of metal”, Coleman adds. “Once you start thinking about these things the possibilities are endless. You can strengthen a material considerably without adding to its weight at all.”
This high strength to weight ratio is due to the fact that it is made of carbon. “The carbon chemical bonding is pretty strong and it has a low atomic number meaning that it is not very heavy. Its density is about a quarter that of steel yet it is 100 times as strong.”
He points out that these properties have been known for some time, it has been a question of cost and availability. “People had known about carbon nanotubes for a long time but they cost tens of dollars per kilo to manufacture. Graphene costs just $5 now. It is manufactured from graphite which is a by-product of the steel industry and is a commodity material. Graphite is like sheets of graphene in a book and if you can separate those sheets you get the strongest material known to man. The Nobel prize in 2010 was awarded to a team who had developed a method to separate them one sheet at a time.”
Hardly economically viable but still the breakthrough that proved it could be done. What the team led by CRANN has done is to develop a method to separate the graphene sheets literally by the trillion. “We have now received EU funding to scale up the method and turn it into an industrial process.”
And graphite isn’t the only layered material out there which could enable powerful new technologies; nor is strength the only useful quality they possess. Coleman’s work in CRANN will open up over 150 similarly exotic layered materials – such as boron nitride, molybdenum disulfide, and bismuth telluride – that have the potential to be metallic, semiconducting or insulating, depending on their chemical composition and how their atoms are arranged. This new family of materials opens a whole range of new “super” materials.
Two of the materials that he is currently researching are bismuth telluride and molybdenum disulfide. Bismuth telluride is used to generate energy from waste heat, for example from car engines or nuclear plants and so on. Prof Coleman’s method of separating graphene using a liquid process could be applied to bismuth telluride, which could then be coated onto thin film substrates and attached to the side of a moving car or a nuclear plant to capture the lost heat energy and convert it into usable electrical energy.
These new materials are also suited for use in next generation batteries or supercapacitors which can deliver energy thousands of times faster than standard batteries, enabling new applications such as electric cars.
“There are many possible applications of these new nanosheets, including their use as thermoelectric materials. These materials, when fabricated into devices, can generate electricity from waste heat. For example, in gas-fired power plants approximately 50% of energy produced is lost as waste heat while for coal and oil plants the figure is up to 70%. However, the development of efficient thermoelectric devices would allow some of this waste heat to be recycled cheaply and easily, something that has been beyond us, up until now,” Coleman explains.
Indeed, these applications were seen as their most important use until recently. “A few years ago if you talked about graphene the discussion would have been around its use in transistors, sensors and other high tech applications”, he says. “There is a consensus building now that where it will change the world is its use in super-strong plastics. We could make planes or wind turbine blades out of plastic if we put in graphene.”
All of these new applications have been developed and breakthroughs achieved within six years of the initial work which won the Nobel Prize making these nanosheets true 21st century materials. For Coleman, he would like to see two things happening with these materials over the next few years. “I would like to see the processes developed which will manufacture the nanosheets in very large quantities and then I would like to see it demonstrated how graphene can be put in a wide range of plastics to increase their strength and reduce the amount of we use. If even a fraction of the potential uses comes to pass will all be using graphene and other nanomaterials in our daily lives in ten years from now.”
And that ubiquitous usage may well be almost entirely due to the research done by Jonathan Coleman and his team at CRANN in Trinity College Dublin.
