Since graphene was
first isolated from graphite by researchers at the University
of Manchester, UK, in 2003 and their findings were published in
2004, scientific interest in this space has snowballed.
While much of the excitement rests on graphenes
apparently endless list of potentially revolutionary uses, on
the production side, an intriguing question has emerged over
which is a better source material natural or synthetic
|In the decade since its discovery, graphene has
billions of dollars' worth of research into the best ways
use it and make it (source: Festival della
Speaking in the opening session at
Graphene 2014 in Toulouse this week, Rod Ruoff, from the
Ulsan National Institute of Science and Technology (UNIST) in
Korea, noted that
graphite-route graphene has the advantage of lower raw
material costs when compared to chemical vapour deposition
(CVD) growth of graphene on substrates such as copper.
CVD is currently the most commonly used way of producing the
atomic layer of carbon, however it is not the only graphene
synthesis method in use.
Some of these
alternative synthetic routes could be more cost effective
than the graphite-route and, in some cases, could also be
preferable in terms of application properties.
One company championing a novel synthetic route is Applied
Graphene Materials (AGM), a spin-out company from the UKs
Durham University, which floated on the London Stock Exchange
AIM in November 2013, raising £11m ($18.6m*).
Claudio Marinelli, AGMs business development director,
told IM that the company is currently capable
of producing 1m tpa synthetic graphene, but hopes to scale up
to 8m tpa within 24 months, highlighting the increased demand
from customers, which he says come to us not the
other way around.
Different types of graphene
There are two main ways of producing graphene, either by
exfoliating carbon layers from a graphite source, or using a
substrate, such as nickel or copper, to deposit a precursor
that contains carbon through CVD.
The latter method produces an almost continuous film of the
same size as the substrate, whereas the exfoliation of graphite
provides nanoplatelets graphene flakes, varying in size
from less than a micron to few tenths of microns.
CVD graphene is a very effective electrical conductor,
meaning it can be applied as an electronic device transistor,
or as a functionalised sensing surface as well as transparent
and conductive layers as a replacement of indium tin oxide
(ITO) for touch-screen displays.
However, while both natural and synthetic films can be used
in a number of applications, there are some advantages
associated with the use of synthetic over graphite-route
Through CVD, you promote the assembly of carbon atoms
using a template in such a way that you end up forming a single
or bilayer film of high quality graphene, which is very close
[to an] ideal, infinite continuum layer of carbon atoms that we
call graphene, Marinelli told IM.
This material is very high quality in terms of being
close to the ideal definition of graphene and there is this
continuity in play that allows for good application
especially in electronics, he explained.
In addition, CVD graphene is free of the impurities often
left behind by the process of exfoliating graphite.
Equally, however, there are limitations associated with
using CVD material. For example, this type of graphene can only
be manufactured in quantities limited by the extent of the
substrate and several steps are required to lift the graphene
film from the substrate for application.
By contrast, graphene nanoplatelets, which take the form of
a black powder, can be produced in volume and can be readily
incorporated in dispersions.
Yet, production of graphene nanoplatelets through graphite
exfoliation is essentially a batch process and relies on
To exploit the application advantages of the nanoplatelets
and improve over the graphite-based manufacturing method, AGM
has developed a proprietary process for the synthesis of
graphene that does not require graphite as a starting
Combining some of the benefits of CVD synthesis and the
graphite-route, AGMs method allows for large volumes of
graphene nanoplatelets to be produced free of graphitic
impurities in a scalable and very green process,
Marinelli told IM.
This delivers a highly dispersible powder suitable for a
number of volume applications, where AGM nanoplatelets can
bring the desired material multifunctionality in terms of
for instance enhanced mechanical, electrical and
By virtue of being a small, fine powder, it is very
much like an additive. We are all familiar with additives in
polymers, solvents and paints, so it enters a range of
applications through dispersion in a polymer or in a solvent.
It can also be used in batteries or supercapacitors alongside
activated carbon, Marinelli said.
Again, however, there might be disadvantages of using
graphene in a nanoplatelet format, as the material no longer
exhibits the continuous properties of the CVD-produced
This means that, for example, electrical conductivity
is no longer continuous but [travels] through islands, so
conductivity takes a bit of a knock back when using
powders, Marinelli said.
Depending on how you produce your graphene, you will
notice different properties and hence benefits, once you deploy
that graphene in an application, he added.
As a result of this, competition in the market is more
complementary than competitive, as there are some
applications where other materials might be better than ours
and vice versa, Marinelli admitted.
What about price?
One of the most talked-about points when it comes to
graphene is price. Not just production costs, which until mass
manufacturing methods are optimised will continue to be
expensive, but also end-market prices, which will remain high
until production costs come down.
Marinelli told IM that, in terms of natural
versus synthetic graphene, he does not see much of a difference
In the long term, methods for producing powders are
intrinsically scalable, so I can see less constraint in terms
of process, scaling up and reducing the cost of flakes, rather
than continuous films, he said.
However, Marinelli also admitted that the question of price
is the most difficult to answer in relation to graphene.
If the material delivers the advantages that we all
hope it will, price will become irrelevant because the material
is only used in very small quantities, he said.
Secondly, I would rather not set a price that limits
the range of applications. Rather, I would like to try and
explore an application that can redefine the price point for
the final product, which provides advantages for the customer
as well as for the supplier, he added.
Marinelli also noted that, realistically, graphene is going
to make its way onto the commercial landscape via high value
products, at least to begin with.
While the different and as yet
unstandardised types of graphene each have their own
advantages and disadvantages, Marinelli believes that the
future of this material will contain both graphite-route and
To an extent, we have a degree of overlap even among
platelets applications, he said.
Perhaps graphite-derived graphene, because of the
presence of graphite and transition metals, might be more
suitable for electrical conductivity applications and other
uses, such as inks and plastic electronics.
AGMs synthetic graphene platelets might find
greater acceptance in polymer composites, paints and coatings,
lubricants and functional fluids, whereas other end markets are
more suited to the film-type of graphene, he told
I do believe that both [types of producer] will be
very busy filling the requirements of customers in these
areas, he added.
To conclude, Marinelli stated that while no killer
application for graphene has yet been rolled out, commercial
production of the material is
not far off.
Purely from a statistical point of view, there are so
many potential applications that have been proposed to us that
some of these are going to come to fruition, Marinelli
In addition, the diversity of these applications,
combined with the multi-functionality of graphene, gives me a
lot of hope that we will pretty soon find a home in the shape
of a killer application, he said.
*Conversion made May 2014