A Solution For Graphene Production | Hacker News Reader

A Solution For Graphene Production

cen.acs.org

42 pointselleferrer17 comments

Some graphene facts that I've found after a few minutes of research:

- One million times thinner than paper, one atom thick, it's considered a 2D material. http://www.chemistryviews.org/details/ezine/4976821/Is_Graph...

- Strongest material, stronger than diamond. http://engineering.columbia.edu/even-defects-graphene-strong...

- Scotch tape was used to create a piece of graphene only 10 layers thick (I'm guessing that means ~10 atoms thick? wow)

- Moves electrons ~200 times faster than silicon: http://www.samsungvillage.com/blog/2012/05/18/samsungblog-sa...

- Transparent, only absorbs 2.3% of light. http://arxiv.org/pdf/1201.3071.pdf

- Can't switch flow of electricity off? https://gigaom.com/2013/04/19/you-can-pluck-graphene-from-th...

- Can repair itself if you dump carbon atoms on the hole, they snap into place. http://arxiv.org/abs/1207.1487

http://en.wikipedia.org/wiki/Graphene

I don't understand how it can be described as '2D'.

If it were 2D you would be able to stack an infinite amount without the stack getting higher.

My guess is that the people describing it as 2D are focusing on different properties of 2-dimensional space than you are and would agree with you that stacking it would increase the height.

I think there is a different definition of 2D in the materials science field.

http://www.mri.psu.edu/centers/2dlm/

http://www.chemistryviews.org/details/ezine/4976821/Is_Graph...

http://gigaom.com/2013/07/19/graphene-isnt-the-only-2d-mater...

http://www.mrs.org/s13-cfp-o/

Loosely, it refers to the degrees of freedom an electron has in the material. For example, if you consider the 'density of states' – a quantity which can be thought of as the number of electrons at a given energy level – it has a different characteristic shape depending on whether the material is '1D', '2D', '3D' or even '0D':

http://britneyspears.ac/physics/dos/images/Image441.gif

[As an aside, britneyspears.ac is a surprisingly good resource for a lot of basic solid state physics. You can find a full derivation of the above graph on there.]

Edit: To illustrate, this next graph is the density of states for three different Carbon-based materials: graphite which is '3D', graphene which is '2D' and a nanotube which is '1D'.

http://me3007.wdfiles.com/local--resized-images/thermal-and-... [Source: Hone, J., Quantized Phonon Spectrum of Single-Wall Carbon Nanotubes, Science, 289, 1730, 2000 via http://me3007.wikidot.com/thermal-and-electronic-properties-...]

You can see how these curves are similar to the theoretically-derived curves in the previous graph.

"2D" describes the freedom of the electrons. They can move in X and Y, but not Z. This restricted freedom causes all sorts of unique electronic behavior never seen in 3D systems. You are certainly correct that graphene has height.

Source: I am getting a PhD in 2D electron physics

I think a combination of Graphene and superconductivity would be even more wonderous than each one of them!

In fact, superconductivity can be induced in graphene by a proximity effect: http://journals.aps.org/prl/abstract/10.1103/PhysRevLett.111...

Nice list of facts. I would point out that although 2.3% absorption looks small, it's actually huge for just a single layer of atoms! So it's true that graphene is mostly transparent, but it's actually less transparent than almost any other single layer of atoms. That's why the title of your source is "high optical absorption in graphene." :)

Graphene is pretty cool stuff but just flakes of it are not as useful as sheets are. That said, for experimental purposes this may be an excellent laboratory technique for acquiring samples. Not sure why the anode needs to be platinum though. It seems like any conductor would work there. Given that a common "D" sized Dry Cell (aka a non-alkaline battery) will give you a graphite rod (the center core is pure graphite) everything but the platinum should be available off the shelf. If it really does need a platinum anode you'd have to raid a catalytic converter for that.

Platinum is one of the best conductors while being less reactive than most, while being tougher than gold and silver. Platinum (and platinized titanium or other cores) anodes are common in industry.

A home experimenter could just try copper, expecting a much faster consumption and reaction rate, and see what happens. I agree that it's not obvious that it would ruin basic experiments immediately.

Like DougMerritt said, it's probably because platinum is not very reactive. The problem with copper is than in some solutions copper electrodes will start to dissolve or break apart.

If anyone is interested in making graphene yourself, Robert Murray Smith, a chemist in the UK with an amazing Youtube channel, posts some tutorial videos on making graphene at home. He describes this specific method here: http://youtu.be/QMp-RP8DcOc

How likely is to make graphene in your own house? Expensive? Dangerous? Requiere high skillset?

I'm very naive about this, so in my wild imagination: What will need to happend to have a "Rasperry/Arduino" set for graphene?

You can make it in your own house with a pencil and Scotch tape. (not exactly but use a big block of graphite)

http://phys.org/news/2010-12-graphene-pencil-sticky-tape-vid...

You can also follow the electrolysis method described in the original posts paper or the silicon method or Scotch tape method in the article above.

Don't breathe it though, I've heard that's not good for your lungs.

Is graphene a long term risk (like say plastic...or even asbestos)? The benefits are obvious and we'll clearly mass produce it sooner or later, but is this something we can safely throw at all kinds of problems?

Not really; or rather, I should say, the issue isn't nearly as clear-cut as some of the anti-nanotech groups that have been screaming about it would have you believe. They usually point to research by Ken Donaldson, showing similar pathogenic effects between asbestos and nanotubes longer than 20 μm, but fail to acknowledge that there's a difference between nanotubes (and graphene) in general and long nanotubes in particular, as Donaldson's study clearly points out. In brief:

> The basis of toxicity of asbestos and other fibrous materials is now reasonably well understood; their toxicity is based on the physical nature of the materials, rather than their chemical composition. In particular, fibres are expected to be toxic if they are long – longer than about 20 µm – and rigid. The mechanism of this pathogenicity is believed to be related to frustrated phagocytosis. Phagocytes are the cells whose job it is to engulf and destroy intruders – when they detect a foreign body like a fibre, they attempt to engulf it, but are unable to complete this process if the fibre is too long and rigid. Instead they release a burst of toxic products, which have no effect on the fibre but instead cause damage to the surrounding tissues. There is every reason to expect this mechanism to be active for nanotubes which are sufficiently long and rigid. [1]

Donaldson's research doesn't somehow negate the benefits--or even the possibility--of nanotubes; on the contrary, he's rather upbeat:

> There is a silver lining to this research. According to Donaldson, "Short or curly carbon nanotubes did not behave like asbestos, and by knowing the possible dangers of long, thin carbon nanotubes, we can work to control them. It's a good news story, not a bad one. It shows that carbon nanotubes and their products could be made to be safe." [2]

[1] http://www.softmachines.org/wordpress/?p=409 [2] http://www.sciencedaily.com/releases/2008/05/080520144004.ht... [3] http://spectrum.ieee.org/nanoclast/semiconductors/nanotechno... [4] http://spectrum.ieee.org/tech-talk/semiconductors/devices/th...

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