Graphene atomic structure illustration

Graphene to gold? Moving beyond the lab

Five years after Andre Geim and Konstantin Novoselov won the Nobel Prize for their work on graphene, what progress have we made to turn the wonder-material’s promise into profit?

It began as dirt on a piece of sticky tape thrown in the lab bin. Now it’s one of the most feted materials in the world. Graphene has blazed an impressive trail since Konstantin Novoselov and Andre Geim first isolated it at Manchester University in 2004. The city is home to the gleaming National Graphene Institute (NGI), which opened in March 2015. A second centre of excellence is scheduled to open nearby in 2017, the Graphene Engineering Innovation Centre (GEIC), which will have the task of commercialising graphene research.

Graphene has even begun to figure in our cultural consciousness. Artist Cornelia Parker worked with Novoselov on a graphene-themed launch for the award-winning recent refurbishment of Manchester’s Whitworth Art Gallery. Graphene and 2D materials are also the subject of a ground-breaking exhibition next year at the city’s Museum of Science and Industry (MSI).

New research constantly fans the flames of graphene’s potential. The tenth international Graphene Week conference in May drew a record 600 speakers and delegates from 37 countries. Novoselov commented: “Luckily, the same as ten years ago, the results keep coming. There is a good stream of new data on graphene and other 2D materials.” At the conference he presented his latest research on light-emitting diodes based on two-dimensional materials.

However, as the fundamental science flourishes, is anyone ready to announce graphene’s breakout application? What are the barriers to commercial success? Are there lessons from history in how to turn graphene into gold?

Building bridges

Dr Cinzia Casiraghi works at the heart of the graphene research community as a reader in graphene and carbon nanostructures in Manchester University’s School of Chemistry. She pursued a post in the city after collaborating as a post-doc with Geim and Novoselov before their Nobel prize award, helping contribute to graphene’s identification using Raman spectroscopy.

She also chaired the 2015 Graphene Week conference, part of the European Commission’s billion-euro Graphene Flagship research initiative. Casiraghi explains: “Graphene Week is structured in order to maximise the synergy between industry and academia, and to improve communication.”

Dr Nigel Salter agrees this is a vital step in the pursuit of graphene’s potential. He advises engineering and manufacturing companies and until recently, headed 2-DTech, a Manchester University spin-out 85 per cent owned by materials company Versarien. “Graphene was essentially created from a thought experiment,” he says, “and now some of the exciting possibilities we’ve talked about for some time are beginning to emerge. The big question is how you then get them into commercial applications.”

Over 200 years ago, in the vanguard of the industrial revolution, leading thinkers were grappling with the same questions, just down the road. Manchester was at the forefront of the technological change that overtook Britain in the 18th century. In 1781, the Manchester Literary and Philosophical Society, known as the Lit and Phil, formed and met in Cross Street, not a mile from today’s NGI. Its members pursued knowledge, profit and progress, and they included scientists James Joule and John Dalton, industrialists including Samuel Greg, the social reformer Robert Owen, and the author Peter Roget - all of whose ideas have had a lasting impact.

Discussions must sometimes have been heated at the Lit and Phil’s debates and it’s no different today. Salter says scientists and engineers often have different expectations.

“One of the things I’ve found is that researchers emphasise the potential properties: we can cure energy shortages, make fuel cells, and support an elephant on the head of a pin! But a lot of the breakthroughs with graphene may have been done theoretically or on a small scale. We’re still waiting to see them on a larger scale.” Salter hopes that the GEIC will develop a commercially-minded ethos in which graphene’s potential will flourish.

Graphene supply

From the academic side, Cinzia Casiraghi emphasises that hurrying is hard. “In the current scenario, there is often the pressure to solve problems quickly, while forgetting what we learned from previous materials such as silicon or diamond-like carbons, which it took 20-30 years to implement in products and technologies. I do hope that the funding agencies will give us enough time to understand and overcome the fundamental issues in graphene-based technology.”

A reliable commercial supply of graphene is vital for the field to grow. In theory, graphene production would mean creating single-layer planes of carbon atoms - but in practice this has proved virtually impossible. Salter explains the approach: “2D-Tech makes monolayer graphene using chemical vapour deposition, using methane, hydrogen and a copper catalyst - but it’s only for one-off research projects. It’s not going to be the way forward yet.”

Even Samsung, which has poured money into researching graphene screen technologies, has not got far with large sheets of monatomic graphene.

So 2-DTech also takes a top down approach. The firm makes graphene nanoplatelets, starting with graphite and breaking it down layer by layer until it has about five atomic layers. Salter says: “These tiny graphene pieces still have graphene-like properties and work well when incorporated into inks, pastes and plastics.”

This is a promising area for higher-volume applications. “If you use nanoplatelets to reinforce thermoplastics such as polypropylene, you can make it up to 30 per cent stronger and stiffer,” says Salter. Other applications include lighter and thinner composites for aircraft interiors or car bodies.

Historical parallels

For Sarah Baines, a curator at MSI, graphene is certainly a revolutionary material, but it’s also strangely contradictory. She has been scouring the Nobel laureates’ offices for items to display in a 2D materials exhibition that will open in 2016 at the museum, part of the national Science Museum Group. “To a scientist it makes perfect sense to say graphene is strong, but in fact it’s so diaphanous and delicate you couldn’t just put a layer of it on display,” says Baines. “The strength is on the nano-scale, so if you had a piece of steel as thin as a piece of graphene, it would be much weaker.”

In terms of graphene’s significance, Baines sees a historical correlation with another breakthrough: the discovery of atomic structure by John Dalton. He first presented much of his atomic theory in 1803 at Manchester’s Lit and Phil. When Dalton made his imaginative leap, proposing for the first time that atoms of different elements were distinguished by their weight, it opened up enormous new fields of thought. “He looked beneath the surface,” says Baines. “The concept changed everything in physics. His ideas about atomic structure were eventually taken up internationally and models of the atomic nucleus surrounded by electrons came shortly after that, because of him.”

Dalton was the first person to use ball-and-stick models of atoms, now familiar in every chemical diagram. The incredibly simple-seeming diagrams of graphene’s structure, still represented as balls and sticks, perhaps gives us a false sense that the science must also be simple, the material’s properties easily attainable. Yet it took many years for the full implications of Dalton’s work to be realised - as well as for the incorrect parts of his ideas to be ironed out.

Even materials we thought we understood well are revealing new properties at a 2D scale. Baines and her team at MSI have widened the original scope of their exhibition as the science has developed. “Graphene was just the starting point for 2D materials,” she says. “Scientists are currently isolating and creating other super-thin films of atoms, from silicon (silicene) to tin (stanene). Theoretically, electrons may be able to travel along the edge of the sheet of tin atoms, which means that stanene might be able to conduct electricity without wasting any energy in the form of heat.”

Can we predict where the step-change in applying 2D materials may come first? “I’m very excited about how graphene could apply to areas like photovoltaics and energy storage,” says Salter. Graphene’s electrical conductivity, low resistance and mechanical strength make it a good candidate for rapidly-recharging batteries. “I think the first applications we’ll see will be for bulk energy storage of power from solar arrays or wind farms. Then we might see it in consumer products.”

Green graphene

Renewable energy would be a fitting application for graphene. The world is still coming to terms with the environmental effects of carbon-guzzling 18th-century industries, and graphene production itself is currently not as green as it could be. This is a problem that concerns Professor Ester Vazquez of the Microwave and Sustainable Organic Chemistry Department at the University of Castilla-La Mancha in Spain.

“Industrially viable applications require large-scale and cost-effective production methods,” says Vazquez, another speaker at this year’s Graphene Week conference. The most economical way to produce graphene in quantity is by removing layers from bulk graphite, a process called exfoliation. “Most of the time, very harsh reaction conditions are needed,” Vazquez explains, “so we have explored the use of alternative, non-conventional ways for manipulating carbon structures, avoiding the use of large quantities of toxic solvents and long procedures.”

Professor Vazquez’s group hopes these non-toxic methods will lead to smart medical materials that could deliver drugs within a patient’s body in response to an electrical stimulus.

3D printing is proving a useful technique for building devices from 2D materials, including graphene. 2-DTech is sponsoring a university project on conductive inks. “You load one ink with graphene and another with a material such as boron nitride, which has different properties, and then you can print multilayer devices,” explains Salter.

Companies like IBM have enormous programmes investigating graphene as an alternative to silicon in transistors, although there has so far been no breakthrough in getting graphene to behave like a semiconductor.

Biggest barrier

However, there is a big barrier to commercialising graphene at the moment. Casiraghi explains: “One of the biggest challenges when dealing with new materials is related to the lack of methods for making controlled products.”

Salter adds: “What’s stopping progress at the moment is the Catch-22 of getting enough investment so that we can increase our capacity to produce graphene to a realistic volume.” He hopes the GEIC will provide more opportunity for this.

Scaled-up production techniques can’t come too soon, he argues. “This is an area that really needs to catch up,” says Salter. “We desperately need to find techniques to characterise and grade graphene so we can make standardised, reliable products for market.”

Baines points out that in the early history of industrial engineering, standardisation had a revolutionary impact. “It is a great example of the relationship between science and industry,” she says, referring to the work of another name familiar in Manchester, Joseph Whitworth. After perfecting the micrometer, Whitworth devised a standard for screw threads that soon spread nationwide as the first universal standard system, following its adoption by the burgeoning railway industry.

“If a commercial company can do for graphene what Whitworth did for screw threads, engineers will have a reliable product they can work with”, says Baines. “The universities are working on the science, but it is the companies that are working to create a reliable, standardised supply of graphene.”

The new exhibition at MSI will emphasise how much there is still to play for in the world of graphene. “That’s why we’re aiming the exhibition at secondary school groups as well as curious young adults,” explains Baines. Far from being a cut-and-dried story, 2D materials are a live issue in chemistry, physics and engineering alike. “One of the strong aspects of graphene’s discovery is the idea that once you become expert in something, you can be more playful in it,” she adds. “With expertise comes opportunity.”

MSI and its supporters across the graphene community will be hoping to inspire the next generation of scientists and engineers to join the ever-expanding field of graphene research. Dalton and Whitworth alike certainly would approve. They left considerable legacies to support technical education in Manchester. They would surely hope that through effective collaboration and crossover, their successors will turn graphene to gold.

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