The paradoxical observation “less is more” applies perfectly to carbon, for if you think coal and diamonds are valuable, just wait to get your hands on a little bit of graphene. Ideally, this material consists of a single atomic layer of carbon atoms arranged with symmetrical bonds to form sheets. In their purest form, such sheets are light, flexible and stronger than steel, so that a mere gram might be spread out over the better part of a hectare.
At the same time, graphene is highly conductive, demonstrating quantum electric field effects at room temperature that previously had only been observed under cryogenic conditions. This behaviour lends itself to a wide range of applications that could take advantage of an ability to store and move electrical charge. The list includes cell phone batteries that could be fully charged in minutes and run for a week, as well as paper-thin LED displays you could wear on your clothes. Its non-electrical properties are equally impressive; for example, when immersed in water it can react to form graphene oxide, a remarkable sieve capable of filtering out even the tiniest impurities. In this way, the economics of desalination could finally become favourable.
Above all, such innovations would be rooted in one of the universe’s ubiquitous building-block elements. Just as humble silicon has driven the development of contemporary electronics, so too could equally humble carbon point the way forward to even more sophisticated forms of information technology.
Gary Economo, CEO of Grafoid Inc. Photo Credit: Grafoid, Inc.
Yet this bright carbon future will remain out of reach until researchers can find a way to produce graphene consistently and in industrial amounts. Current methods offer yields on the order of grams, at least for products that display some of the extraordinary qualities associated with this material. Some manufacturing techniques can turn out as much as a kilogram, but in layers far thicker than a single atom, so that many of these qualities are diminished.
Those amounts would be dwarfed by even a modest use of graphene to replace the semiconducting silicon currently used in microelectronics. The annual global demand for that silicon comes to around 2,500 tonnes. If even a fraction of that total is to be supplanted by printing graphene into computer circuitry, it will be necessary to ramp up the output of this material in a big way.
Gary Economo has dubbed the development of this production capability “the global graphene race,” so strategic does he believe this commodity will become. Economo is the CEO of Ottawa-based Grafoid Inc., a privately held company that is shepherding its own method of refining graphene from graphite taken from a mine at Lac Knife, Que., deep in Canadian Shield country. “It is the first two-dimensional organic crystal discovered with electronic, optical, mechanical and thermal properties,” Economo recently wrote in a financial newsletter, where he describes graphene as the focus of growing international competition. “Today, it is the subject of investigation and experimentation by nearly every Tier 1 university in the world and by those leading multinational corporations with a vision to capture and dominate future markets.”
Economo says that of the thousands of patents associated with graphene, most are held by interests in China, followed closely by those in the United States and Korea. Speaking from a Canadian perspective, he sees this country moving much less aggressively in the field, an attitude he is lobbying to change. Grafoid is advancing Canada’s position on the world stage; incorporated in 2012, it upholds “a vision of establishing a global standard for single, bilayer and trilayer graphene in terms of purity, low costs, scalability, reproducibility and environmental sustainability,” Economo says.
The discovery of graphene, when samples were found stuck to office tape, adds yet another story of fortunate accident to the history of science. Photo credit: Gabriel Hildebrand
In light of the global nature of graphene research, Grafoid has been striking up partnerships around the world, assembling teams that work in Singapore and Japan as well as Canada. A cornerstone of the company’s technology is a system that extracts graphene directly from graphite, which was originally developed by University of Alberta chemical and materials engineering professor Hani Henein.
Earlier this year, Grafoid acquired exclusive right to Henein’s approach, which the company describes as a “novel chemical exfoliation and transformation process” leading to bilayer and trilayer graphene that goes by the commercial name MesoGraf. Among the first applications for this product has been a composite with carbon-coated lithium metal phosphate, patented jointly with HydroQuebec, which holds a number of similar patents on advanced electricity storage materials.
Grafoid touts itself as defining the cutting edge of graphene production, with the ultimate goal of standardizing the product and reducing its cost with a complete mine-to-market model. Potential investors, for their part, remain optimistic, but most are waiting to see significant milestones in the use of this exotic commodity. An analysis in Forbes last year pointed to the flurry of activity at Grafoid, but noted that much of this work is still pushing the limits of laboratory science.
That is certainly the case for University of Waterloo chemical engineering professor Aiping Yu, who began studying graphene within a year of its official discovery being published in Science in 2004. Yu is now collaborating with Grafoid to help the company refine its method for extracting graphene from graphite, including the removal of impurities such as aluminum oxide and silica oxide. “When my first paper came out in 2007, we were still debating how to define graphene,” Yu says. “People were saying it should be just one atomic layer, but we found that to be really challenging.”
In practice, Yu notes, researchers like her are dealing with graphene that is not a single, double, or even triple layer; instead, samples might be 25 nanometers thick, which is about 60 atomic layers. This compromise is necessary in order to reduce the effort and cost of having any sample at all, but it means the conductivity and other remarkable features of the material are far less pronounced.
While she is familiar with Grafoid’s approach, Yu employs her own patented method for obtaining such samples. Starting with graphitic oxide, a precursor to graphene discovered more than 50 years ago, Yu inserts this material in a surfactant and subjects it to sound energy in order to form thin sheets. Her surfactant of choice is the widely used food additive gum arabic, but otherwise this technique requires few chemicals and generates no heat, making it easy to scale up.
This is the starting point for Yu’s exploration of graphene as the basis for energy storage devices called supercapacitors, which could eventually supplant batteries as the preferred means of powering equipment large and small. Designed in a similar way to traditional capacitors, which hold charges between two metal plates, supercapacitors incorporate carbon-based materials to retain those charges electrochemically in the form of ions. The extent of this capability is determined by the surface area of the carbon and graphene offers the most outstanding choice for this purpose.
If this design proves to be feasible, it would be just one more example of graphene’s potential, which continues to excite scientists and entrepreneurs alike. It is all the more marvellous for a field that is just a decade old, which began with one of science’s happier accidents, when two investigators at The University of Manchester, Andre Geim and Kostya Novoselov, started spending their Friday nights on more unusual experiments with graphite. It was only after samples that had clung to pieces of Scotch tape were recovered that the first evidence of graphene was found, an insight that earned them the Nobel Prize in Physics six years later.
Physicists still used this “Scotch tape” method to obtain pure samples for their work, even though dozens of attempts are necessary to obtain a single specimen. It is hardly a strong basis for laboratory science, much less commercial output, but it is a faithful measure of graphene’s compelling allure.
Geim captured a sense of that appeal in his Nobel Prize lecture, where he compared the unorthodox traits of carbon in the form of graphene to the important distinction between planets and stars in the night sky. The unusual movements of the former set the stage for a new understanding of celestial mechanics and became the foundation of classical physics. Similarly, Geim insists, graphene opened up a new vista of carbon chemistry.
“Our Science paper offered the first glimpse of graphene in its new avatar as a high quality 2D electronic system and beyond,” Geim says. “For me, 2004 was only the starting point for the unveiling of many unique properties of graphene.”