EDITOR: | February 4th, 2016 | 11 Comments

Understanding Graphene – Part 1

The missing bond in graphene
| February 04, 2016 | 11 Comments
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Graphene is to Graphite as a playing card is to the pack.

There, that’s the short version, if you’d like to know more read on…

The building blocks:

Graphene and graphite are made of the same thing, carbon. The carbon atoms are arranged as hexagons in flat layers. Each atom is joined to three others.The structure of graphene

These graphene layers stack one on top of another to form graphite

How graphene layers stack forming graphite

The properties of graphite and graphene:

The bonds between carbon atoms are strong within the layer but much weaker between layers. These layers slide over one another quite easily and can shear off. This is why graphite has been used as a lubricant and also helps understand how a graphite pencil leaves the characteristic line on a sheet of paper.

This doesn’t explain some of the other properties that graphite and graphene display, to do that we need go a little further into the atomic structure and explore a mystery.

There is a puzzle at the heart of graphene; each carbon atom should be connected to four other atoms. These connections are made by shared electrons and called bonds. Look closely at the graphene layer and you’ll see that there are only three bonds. Where has the fourth bond gone?

The fourth bond is actually present, just not in the form you might expect. The fourth bond projects upward and downward from the plane of the layer. It becomes merged with the others in the ring structure creating an electron cloud called a pi system.

The missing bond in graphene

This electron cloud above each ring further merges with all the other rings in the graphene layer creating a continuous π orbital that stretches over the whole graphene sheet.

The source of graphene's properties

This free movement of electrons through the graphene layer is why it conducts electricity better than other materials for example electrons can move 100 times faster in graphene than the silicon used in computer chips.

In graphite the graphene is not continuous as it is broken up into crystal flakes, within these flakes are the layers of graphene. This means that while graphite does conduct electricity it is not as good an electrical conductor as graphene. Graphene has been reported to be 5000 times better than graphite as an electrical conductor.

When does graphite become graphene?

The obvious answer is that graphene is a single layer material and graphite is a multiple layer material. Things are not quite that simple. A global market has emerged that is selling multilayer graphene. Investorintel has been analysing this market and the report will be available in the near future.

Graphene multilayer graphene and graphite layers

The Royal Society of Chemistry reports that it takes about 10 layers before the electronic properties revert to those of graphite. This would be a clear place to draw the line between graphite and graphene and help understand the products out there in the market.

At the time of writing in 2016, in the global marketplace, graphene can be bought in kilogram quantities. This is usually as graphene powder or slurry of multi layer nano-flakes in a liquid in varying levels of quality.

True graphene is available in millimetre or centimetre scale quantities usually attached to a copper or silicon surface. As such true graphene is more a product for research organisations than an industrial raw material.

The reason why true graphene is available in such small quantities is because it is rather hard to create. There are a variety of methods used to manufacture graphene these, dear Investorintel reader, are the subject of the next column.


Editor:

Adrian Nixon began his career as a scientist and is a Chartered Chemist and Member of the Royal Society of Chemistry. As a scientist and ... <Read more about Adrian Nixon>


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Comments

  • Tim Ainsworth

    Brilliant Adrian, a very digestible summary.
    Look forward to Part 2.

    February 5, 2016 - 2:19 AM

  • Janet

    Agreed, very informative and easy to understand. Can’t wait for Part 2 Mr. Nixon.

    February 8, 2016 - 1:57 PM

  • Adrian Nixon

    Thanks Tim and Janet, I’m working on part 2 at the moment.
    Adrian

    February 8, 2016 - 3:09 PM

  • Sam Amamoo

    An excellent technical piece, Adrian. Thank you.

    Hope in Part 2 you can address the apparently simple concept of “commercial quantities” but which is far from clear when applied to the graphene/graphite space.

    Several companies have promised to produce “commercial quantities” of graphene of the order of 15-20 tonnes for customers during 2016.

    It is easy to understand “commercial quantities” when applied to graphene powder or slurry of multi layer nano-flakes in a liquid.

    Not so when you consider true graphene. It would seem that commercial quantities of true graphene are quite some way off.

    If there are two submarkets for graphene it would be helpful for potential customers and investors if producers state which graphene end product type they propose to offer for sale.

    Is it at all possible that the dramatic properties of graphene have been demonstrated in research labs only with the use of true graphene? If so it makes it important for “commercial quantities” of graphene to be clarified.

    February 8, 2016 - 9:02 PM

  • Adrian Nixon

    Thanks Sam, I appreciate your thoughtful posting. You are quite right that there is the potential for lots of misunderstanding in the graphene manufacturing world. There may be more than two submarkets derived from the way the stuff can be made. I’ll explain more in the next column. Thanks in advance for your patience I’m taking time to get the facts as right as I can rather than rush to print.
    Adrian

    February 9, 2016 - 3:51 AM

  • Philip Ford

    Hello Adrian, this is most interesting. Saying that, you always came up with the most interesting material when I worked with you many years ago. I look forward to part two of the Graphene story.
    Philip

    February 11, 2016 - 12:43 PM

  • Adrian Nixon

    Hello Philip, many years ago indeed , I remember you taking good care of me on my very first visit to the ‘States. I have fond memories of that. Glad you found this interesting, as someone with a good grasp of science I can tell that you appreciate the effort I made distilling down some of the research into graphene. More on the way. I’m juggling the writing with working on a couple of strategy projects at the moment so watch this space. Glad you said hello. Adrian

    February 11, 2016 - 4:19 PM

  • Understanding Graphene – Part 2 | InvestorIntel

    […] The starting material is graphite, which is made of layers of graphene rather like a pack of playing cards as described in part 1of this series. […]

    March 6, 2016 - 8:48 PM

  • Understanding Graphene – Part 3 | InvestorIntel

    […] Understanding Graphene – Part 1 Understanding Graphene – Part 2 […]

    March 25, 2016 - 12:44 PM

  • Sami Ullah

    Dear Adrian Nixon, Nice to meet you from Pakistan. I’m Sami Ullah currently working in China, my research area is mostly Graphene. I found your investigation on graphene very informative and looking forward to 2nd part soon. Take care and see you other time again.

    October 10, 2017 - 9:05 AM

  • Adrian Nixon

    Hello Sami Ullah, I’m pleased an expert like you finds this column informative. There are many more parts to the understanding graphene series on here. This is a link to part two
    https://investorintel.com/sectors/technology-metals/technology-metals-intel/understanding-graphene-part-2/
    Kind regards, Adrian

    October 10, 2017 - 10:37 AM

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