The nano-material graphene could prove to be the most important synthetic material since plastic, but producing it is cost-prohibitive. However, several teams of researchers around the world are trying to crack the code to produce industrial quantities of the super material.
Graphene is flexible, transparent, strong, and electrically and thermally conductive. Researchers and engineers are confident that the material can be used to produce high-tech components for smart phones, touch displays, and solar panels. In fact, some researchers claim it's the most important substance to be created since the first synthetic plastic more than a century ago.
Unfortunately, novelty doesn't come cheap. Graphene is prohibitively expensive to make - as recently as 2008, it cost $100 million to produce a single cubic centimeter of graphene, according to Daily Tech
But researchers have just found a method that could bring that cost down and make graphene a ubiquitous fabrication material.
Graphene is only one atom thick and composed of carbon, one of the most abundant elements. However, its shape, which resembles a chain link fence, makes it very difficult to manufacture. One method developed to cut costs involves epitaxial growth on sheets of silicon, which deposits graphene atop a silicon substrate. However, this process limits the flexibility of the material, reducing its usefulness.
Another method is based on chemical vapor deposition, which relies on misting hydrocarbon vapor along a copper or other metal catalyst. Unfortunately, this method degrades the copper and requires a vacuum, which also keeps costs high.
Researchers at Tennessee's Oak Ridge National Laboratory recently developed a new method of creating graphene via chemical vapor deposition at atmospheric pressure, which could allow them to produce greater quantities for production use. Whereas "[m]ost labs in the universities prepare pieces of one to three inches in size at most," as physical chemist Ivan Vlassiouk told Txchnologist
, the Oak Ridge team is capable of producing sheets that measure 40 inches in the diagonal.
Oak Ridge is not the only lab focusing on the graphene. Researchers around the world have realized that whoever invents the best method of producing large quantities of graphene will be able to dominate the fledgling market.
Scientists in South Korea and Case Western Reserve University claim to have discovered that method via dry ice and a turning operation. The researchers placed graphite and frozen carbon dioxide into a ball miller, a small container of stainless steel balls, and spent two days turning it. The cumulative force produced small flakes of graphite, which were then placed in a protic solvent of water and methanol. In the solvent, the graphite flakes combined and formed larger sheets of layered graphene.
"We have developed a low-cost, easier way to mass produce better graphene sheets than the current, widely-used method of acid oxidation, which requires the tedious application of toxic chemicals," Liming Dai, professor of macromolecular science and engineering at Case Western Reserve and a co-author of the paper announcing the findings, told Science Daily
Elsewhere, Northern Illinois University (NIU) researchers are also using dry ice, but coupled with magnesium. The NIU team was attempting to create single-wall carbon nanotubes, but instead discovered that by burning pure magnesium in frozen carbon dioxide, they could create layered sheets of graphene approximately 10 atoms thick.
"It is scientifically proven that burning magnesium metal in carbon dioxide produces carbon, but the formation of this carbon with few-layer graphene as the major product has neither been identified nor proven as such until our current report," NIU chemistry professor and project head Narayan Hosmane told GizMag
. "The synthetic process can be used to potentially produce few-layer graphene in large quantities. Up until now, graphene has been synthesized by various methods utilizing hazardous chemicals and tedious techniques. This new method is simple, green, and cost-effective."
While these processes all show promise, no research team has yet been able to consistently produce large quantities of high-quality graphene ready for production. However, it's evident that researchers are drawing closer to a solution each year, and one of the methods emerging today may provide a lasting, affordable source of graphene tomorrow.