Graphene is an atomic-scale honeycomb lattice made of single layers of carbon atoms. First isolated and produced by Andre Geim and Konstantin Novoselov at the Univ. of Manchester, U.K., in 2003, the researchers won the Nobel Prize in Physics in 2010 “for their groundbreaking experiments regarding 2-D graphene.” Graphene had been theorized for many years before Geim-Novoselov’s production discovery. It was imaged on a transmission electron microscope (TEM) in 1961 by chemist Hanns-Peter Boehm at Ludwig-Maximilians Univ., and identified and named in an IUPAC report in 1994.
The material’s extraordinary physical properties made it an immediate target for researchers attempting to find ways to produce the material in commercial quantities. In terms of physical properties, graphene has 200 times the strength of steel by weight, with the highest tensile strength of any material ever tested. It also has nearly three times the surface area of carbon nanotubes (CNTs); it’s a zero gap semiconductor with numerous electronic properties, exceeding those of silicon; it’s resistivity is lower than silver’s; it has unique optical properties; and it has more than twice the thermal conductivity of pyrolytic graphite.
The market for graphene in 2014 was estimated by Future Markets at $15 to $20 million, with a forecast of 40% CAGR through 2020 to $140 to $160 million, according to market research firms Yole Developments, Lux Research and IDTechEx. Research use for graphene over the next five years is split equally in composite materials, conductive inks and coatings, energy storage (batteries) and basic research applications. Minor uses for these materials include high-performance electronics, transparent conductive films and water filtration applications.
With all its strong properties, the continuing challenge for graphene researchers has been to find a way to produce it in commercial quantities, while maintaining its desired properties. “There are many diverse methodologies being investigated for large-scale production of graphene,” says Felix Miranda, Chief, Advanced High Frequency Branch at NASA Glenn Research Center, Cleveland. “Some of the methods, while simple, have limitations regarding large surface area coverage, as well as control of the numbers of layers of graphene (as the number of atomic layers increase, the properties decline). Nonetheless, mechanical exfoliation is appropriate for small-scale, research-type physics, biology and chemical experiments.”
Despite the lack of significant process successes, nor the emergence of a “killer” application, current interest in graphene remains strong. In 2013, the European Union (EU) committed more than $1 billion over the next decade for research on graphene and other 2-D materials. South Korea and the U.K. governments have similarly committed $40 and $27 million, respectively, over the past two years. And market research firm IDTechEx estimates that more than $60 million in private investments have been made in graphene R&D over the past several years.
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