Almost everyone uses the first 2D material graphene extensively, without knowing the wonders of the material. This material is admired by the scientific community because of its properties. However other, commercial application of graphene are moving slow. In this column, Sahasranaman discusses the history, applications, recent developments and the prob¬lems faced in commercialising this wonder material.
Many of us play with the touchscreen of our smartphones without realising that it is made from the first 2D material of the world. Though hypothesised many years ago, Graphene was accidentally discovered in 2004 by Andre Geim and Konstantin Novoselov at the University of Manchester. Following its discovery, the scien¬tific community went into hyperbolic diarrhoea singing paeans of the properties of the wonder material – strength, electrical and thermal conductivity, magnetism, etc. A Utopian world with its myriad applications was conceived. But 13 years later, the commercialisation of graphene is still painfully slow. Much of its potential remains unrealised.
The most exciting prospect for graphene, following its discovery, was touted to be in the semiconductor industry, where the famous Moore’s Law was beginning to run out of steam. It was only in 2014 that IBM could succeed in knocking silicon off the chip throne and replace it with Graphene. Because Graphene is only one atom thick, it is order of magnitudes faster than silicon. But there are still technical hurdles, difficult according to some, to be overcome before it displaces silicon forever from the chip. And there is the powerful silicon lobby to contend with.
According to The Graphene Council, the largest global community of those interested in this wonder material, there are 142 graphene producers around the world as of January this year. China has the most number (33), followed closely by USA (30), with UK (12) a distant third. Together these 3 countries account for slightly more than half of global production of graphene. India’s share is a little less than 5%. China also has the most installed capacity in the world, as much as 67%.
The jury is still out on whether graphene was patentable, as it is derived from carbon, a naturally occurring material. Many experts believe that University of Manchester missed out on patenting the process by which the invention was made. The commercialisation arm of the university felt that “it was too early to know what to do with it and too much of a rudimentary approach to be a useful manufacturing technique”. The interest in graphene exploded only when the inventors were recognised in 2010 with the Nobel Prize for Physics; but even before that a significant number of patents had been filed by many countries for the application of graphene. As of September last year, more than 50000 graphene patents have been filed. China accounts for more than half of them, followed by USA, South Korea and Japan. But everybody is unanimous that commercialisation of Graphene is very slow. A seminal essay in Nature (October 2014) benchmarks graphene against carbon fibre and Carbon Nanotubes and points out the significantly slower growth in demand and production of graphene. The estimated production of graphene in 2019 is 1200 tpa.
The major reason for graphene’s slow uptake is that nobody was looking for it; it arrived accidentally as a serendipitous discovery. We need to figure out what we want to use it for. The only significant graphene-based commercial products so far are tennis rackets, smartphone touchscreens and conductive ink for printed electronics. Among future applications, one that holds out most promise is energy storage. A Spanish company claims it is close to offering graphene batteries with 5 times more energy density than Lithium-ion batteries. Others say that graphene can double the output of photovoltaic cells. Medical imaging is another promising area. But these are in future and depend on volumes, purity and cost.
A major challenge of nano-manu¬facturing is to produce graphene in industrial volumes in a cost-effective way. At Manchester, Geim and Novoselov used adhesive tape to peel off graphene layers from a block of graphite. Though this exfoliation technique still produces graphene of the highest purity, it is unviable on an industrial scale. Among numerous other methods, the most proven for large scale production of graphene is Chemical Vapour Deposition (CVD), a technique in which methane gas is brought in contact with a heated copper substrate. The problem is to peel off the graphene film deposited on the substrate without contaminating it. The traditional method is to dissolve the copper and redeposit the graphene layer on another medium, an intricate process full of contaminating possibilities. Purity is extremely important for graphene, as contaminants will significantly take away its phenomenal physical properties. Recently researchers at Kansas University claim to have serendipitously discovered a new technique for mass production of graphene. This involves controlled detonation of ethylene or acetylene in a chamber. This patented process holds out a promise of easy scale-up to industrial scale production.
With incredible physical properties graphene is indeed a dream material. It is super flexible and yet tougher than diamond. It conducts electricity faster than any other known substance and conducts heat 10 times faster than copper. It also exhibits high degree of bio-compatibility. And it is incredibly durable.
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