Think thin and flat for strong and energy-efficient materials

3 May 20131 Share

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Prof Valeria Nicolosi, ERC research professor at Trinity College Dublin's School of Chemistry, School of Physics and CRANN

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Ultra-thin materials could open the way for lighter electronics and more efficient batteries. Prof Valeria Nicolosi is on the case, looking at the thinnest materials in the world, just one atom thick. Claire O’Connell finds out more.

Size matters. Or, maybe to put it another way, surface area matters to the properties of a material. The greater the surface area, in general the more reactive it can potentially be.

Prof Valeria Nicolosi, ERC research professor at Trinity College Dublin’s School of Chemistry, School of Physics and CRANN, likes to help explain the concept using cheese – yes, the humble block of cheddar you might throw into your supermarket trolley. 

That block has a particular surface area in contact with the outside environment, but cut it in half and you increase the surface area for the same volume of cheese. Dice it up for a party and the surface area increases even more. Chop it up into nanocubes and your surface area for that total volume now soars, explains Nicolosi.

What does this have to do with everyday life – apart from being a handy conversation starter at the party? Nanomaterials with large surface areas have interesting properties, and Nicolosi is looking to harness those properties for more efficient storage of energy.

Thin and flexible

Nicolosi’s work focuses mainly on ‘two-dimensional’ layered materials. Probably the best known of this class is graphene – it was discovered in 2004 when researchers peeled atom-thick layers of carbon from graphite, the cheap stuff in your pencil tip, and the researchers then went on to win a Nobel Prize

Graphene, which is like a nanosheet of carbon atoms arranged like chicken wire, soon became celebrated as one of the strongest materials known, and its thinness and enormous surface area opened up exciting new possibilities. Why? Having a thin layer of a material rather than a big block of it is like dealing with a page of a book instead of the whole tome – the properties change, explains Nicolosi.  

“A book is not very flexible, it is mechanically not very robust, you can’t do much with it,” she says. “But if you have one page of that book, you would be able to fold it, wrinkle it and mechanically it will still be there, it is way more robust.”

Kitchen chemistry

But first you need to get those layers. Peeling individual, atom-thick layers from a larger material is a cumbersome and time-consuming process, so Nicolosi and Prof Jonathan Coleman at CRANN developed a deceptively simple way of making literally buckets of ultra-thin layers using what she describes as ‘kitchen chemistry’. The approach uses a soapy solution to exfoliate the two-dimensional layers so that they disperse into the liquid in their billions. “We did that with graphene and we were able to extend it to the other layered materials out in nature,” she explains, adding that she and Coleman are continuing to work together on the materials. “Collaboration is at the heart of science.” 

Layers of success

Nicolosi now has a European Research Council grant to look at how these materials could help improve devices for energy storage. “When you go down to this nanoscale, for the same volume of material you have a lot more surface area and the material will get more reactive, as well,” she explains. 

“And the final applications would be to use these materials for energy storage, to produce batteries and other systems that can store energy more efficiently than other systems on the market.” 

Nicolosi already has preliminary results to show that the materials can withstand a good deal of wear and tear in devices made in the lab, and this augurs well for making light products that go easy on the energy consumption, according to Nicolosi, who last year delivered the RDS/Intel Prize Lecture for Nanoscience. “Given the mechanical robustness of the material you could end up with devices that last much longer than the current devices out there on the market now,” she says. 

From Oxford to Dublin

Originally from Italy, Nicolosi came to Dublin via the University of Oxford, where she was working on nanomaterials. She chose to move to Trinity to be able to access the facilities and collaborate with other researchers in the field, she explains. 

“Being a lecturer in Oxford might be the dream of many other scientists, but for nanoscience, for what I do, Ireland has got a lot to offer,” she says. “The fact that Ireland has recently been ranked sixth for nanoscience in the world and eighth for materials science, that tells you about the quality of science that comes out of this country.”

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