Talk:Graphene/Archive 1

Archive 1

Archive 2

Allotrope?

From the article:

"It is not an allotrope of carbon because the sheet is of finite size and other elements appear at the edge"

For that matter, the same occurs for diamond and graphite. Diamond is merely a matrix of carbon atoms bonded in a tetrahedral shape. Graphite is series of benzene rings. In both allotropes, each carbon atom has a total of four bonds, assuming that the matrix is unbounded (in graphite, there are two single bonds and one double bond per atom). When the matrix ends, the carbon atoms typically bond to hydrogen atoms at their surface to terminate the extra loose bonds. And yet, the two are still considered allotropes.

It is not, then, for this reason that graphene is not a new allotrope.

From my reading, graphene is similar to graphite in that it is a single layer of a graphite matrix. See here (IUPAC). Note that graphene is a singular sheet of graphite, just as goose is the singular of geese. For this reason, graphene is not an allotrope, because graphene and graphite are the same.

Also, note that graphite is a 'quasi-infinite' matrix.

Kris Kerwin

Graphene is chemically and structurally quite different from graphite. For example, it is a semi-conductor and it is prevented from melting by micrometer-scale random corrugations. Whether it is different enough to be an allotrope is tricky, but I'd say it is. I completely agree that the finiteness of graphene is irrelevant and should not be mentioned. Even other allotropes of carbon are finite in some or all dimensions, including nanotubes and buckyballs. --Alistair

A quick search on Google for "graphene allotope" seems to point to classification of graphene as a carbon allotrope. These include pages from the University of Conneticut (http://www.phys.uconn.edu/Seminars/2007Spring/20070319hsc.html), a peer-reviewed article in Nature Physics (http://www.nature.com/nphys/journal/v2/n9/full/nphys384.html - Nature Physics 2, 620 - 625 (2006)), and an article in C&E News (The news magazine of the American Chemical Society - http://pubs.acs.org/cen/science/84/8416sci1a.html) On the minus column is an article in The Hindu (http://www.hindu.com/seta/2006/04/06/stories/2006040600971700.htm - "It is however not an allotrope because (a) the sheet is finite in size and (b) it contains at least one more element, namely hydrogen at the edges."), and an entry in nanoscienceworks.org's Nanopedia (http://www.nanoscienceworks.org/nanopedia/graphene - "It is not an allotrope of carbon because the sheet is of finite size and other elements appear at the edge in nonvanishing stoichiometric ratios"). Those are just the results from the first 30 entries. At any rate, the current claim that it is not an allotrope is inconsistent with the WP page on allotropes, because the latter does not refer to thickness as a criteria. One or the other page should be fixed. -- 14:27, 26 July 2007 (UTC)

2D Crystal?

Is graphene really a 2D crystal???, graphene is not , strictly speaking, a crystal in the full sense of the word, since I don't think you can speak of "translational symmetry" because that would mean you could consider its dimentions to be much , much larger than the unit cell , which is definitely not the case for graphene. --85.138.18.55 18:07, 12 April 2006 (UTC) Pedro

It certainly makes sense to say graphene is a 2D crystal - it has two distinct translation symmetries. Similarly, a carbon nanotube is a 1D crystal. --Alistair

Electron Transport

In the section on electron transport, it might be more accurate to say that the "charge carriers" obey a Dirac equation, not the electrons. That way, the statement includes holes too, but excludes non-conduction electrons. However, this should be checked with somebody who actually knows about the electronic structure! --Alistair

I would second the amendment of "electrons" to "charge carriers": this is the terminology used in Novoselov et al. Science 306 2004. The discussion of whether or not graphene is an allotrope of carbon is flawed (the 'thickness' of a material is irrelevant, an allotrope is a structurally different form of the same element) and boils down to semantics in the end; more importantly I don't believe that this is the best way to start what is supposed to be an informative article. When we give talks we normally start with the dimensionality aspects: i.e. 0D = quantum dots, atoms etc., 1D = nanowires, nanotubes, 3D = diamond, graphite etc., and now 2D = monolayer graphene, monolayer hexagonal boron nitride etc. which places the discovery in context (note that dimensionality in this sense refers to electronic transport properties and not the structure itself). Graphene is not just a singular noun, Kris, and graphene and graphite are most definitely not the same - they differ in terms of band structure (graphene is a zero-gap semimetal), transport properties (ballistic conduction at room temperature in graphene), crystal structure (graphite has a c unit cell parameter) etc. The discussion of defects is interesting, but again not necessarily the best way to start the article in my opinion. - T. Booth Mbcx0tjb 13:19, 24 March 2007 (UTC)

Properties

Any details of graphene's melting point, breaking strength, stretchability, electrical conductivity and heat conductivity? If they direction dependent please give all values. Andrew Swallow 22:30, 11 July 2007 (UTC)

Minimal conductivity

Should the minimal conductivity mentioned in the article not be e²/h instead of e²/ hbar ? Sorry I am not quite sure. Can someone please correct the entry and delete this from discussion?

Minimal conductivity in Novoselov et al. work is 4e²/h - 4 coming from the two pseudospins times two valley indices. However, recently there have been indications that this value is not universal, i.e., it depends on the actual strength of disorder in the material. For ballistic samples, the theoretical prediction for the conductivity is rather 4e<up>2/π. Anyway - I did not find a mentioning of this minimal conductivity in the main article, and as it is still a bit controversial, it should probably be left out. --80.220.143.51 19:41, 9 August 2007 (UTC)

Finite thickness

The article says "It is not an allotrope of carbon because the sheet is of finite thickness." How does that follow? Any sheet of any material is of "finite thickness". Matt 00:42, 8 August 2007 (UTC).

• I see now that this sentence was also queried above by others. I've removed it. It makes no sense as written, and if it's supposed to mean something then it needs to be explained better. Matt 13:56, 8 August 2007 (UTC).

Graphene's thickness

Hi you all! Perhaps there's an error at the end of "Chemical modification" paragraph: it's written that graphene's layers are 5,3 angstroms thick. But in Princeton's PDF, at page 16, it's written that a graphene's flake is 3,34 angstroms thick. I think you should write 3,5 instead of 5,3 angstroms in the article. What do you think? Let me know on [1]. Bye.--87.2.174.81 21:20, 1 September 2007 (UTC)

Developments happening quickly

Graphene Gazing Gives Glimpse Of Foundations Of Universe

"I was rather pessimistic about graphene-based technologies coming out of research labs any time soon. I have to admit I was wrong. They are coming sooner rather than later."

Shenme (talk) 08:16, 4 April 2008 (UTC)

Translation into english?

Alot of the material, especially in the subsections under "properties", are deeply techincal and seem to make no attempt to reahc a reader who is not a qunatum physiscist and would probably know all this stuff anyway. For example, under electronic properties, there is a statement: "Thus, the Hall conductivity is [some martian giberish], where N is the Landau level index and the double valley and double spin degeneracies give the factor of 4. This remarkable behavior can even be measured at room temperature." If you don't happen to know what Hall conductiviy and Landau level indices are the only thing "remarkable" about this is that anyone believes more than 2% of the Wikipedia readers will understand it at all ;-)

But serioulsy, if anyone really does understand what all this means, it would be nice to ADD some statements saying something like "this means such and such" without actually dumbing down the article or removing any of the important facts and figures. A good example, under the mechanical properties, is the statement "These high values make Graphene very strong and rigid." I may not know what the Mermin-Wagner theorem is but, I do know what strong and rigid mean. Rich.lewis (talk) 17:14, 7 April 2008 (UTC)

You are right, the incriminated paragraph on the quantum Hall effect is a special example for extreme non-understandability, and not easily understandable even for solid-state physicists. I have tried to improve the text somewhat in the direction you are considering. - Regards! 87.160.73.252 (talk) 07:52, 26 June 2009 (UTC)

who should be credited for the discovery of graphene?

If Iijima is often considered as the discoverer of carbon nanotubes, would not then it be fair to give the credit for graphene as it was suggested by Carbophiliac?

"This discovery should be attributed to Andre Geim who is the corresponding author in the first few graphene papers. His priority seems to cause no controversy, unlike the hotly-debated discovery of carbon nanotubes. Indeed, there have been a number of earlier efforts to make very thin films of graphite by mechanical exfoliation (just like the Manchester group did) but nothing thinner than 50 to 100 layers came out, and no proof for the existence of free-standing layers of 2D crystals was given before 2004.

Further credits for the discovery of graphene go to Kostya Novoselov (Geim's associate; the first author in most of the Manchester papers) and Philip Kim from Columbia University whose group was first to confirm and extend Geim's discovery."

Let me add that I followed refs given by UMDNANO and found that Geim was one of the two corresponding authors of Nature 2007 that was first to report graphene in the suspended state. In my opinion, it is actually not important as the area took off after his Science 2004 and the back-to-back Nature papers in 2005.

YZhangfirst (talk) 21:59, 24 April 2008 (UTC)

Two points that might help here:

(i) I'm not sure about benchmarks in the manufacture of large free-standing sheets, although electron microscopists have I think had methods for making very thin supports for transmission study of single heavy atoms for some time. It might be worthwhile to check further into that literature on that, and in that context I will ask around.

(ii) Concerning the existence of atom-thick graphene sheets in bulk, we've known now since the mid 1990's that unlayered graphene (density near 2g/cc) is manufactured in abundance in the atmosphere of late-stage red giant stars. Laboratory samples of presolar materials show this clearly by more than one analysis technique. How asymptotic giant branch stars pull it off, and how in turn we might similarly make composites of unlayered graphene on earth, is still a mystery and the subject of ongoing research. Thermochap (talk) 22:38, 24 April 2008 (UTC)

Thanks for this. I do not really know about graphene around red giants but, surely, so-called nanographenes (a few nm large sheets of graphene) should be there too, next to a plenty of buckyballs and carbon nanotubes. I also read that chemists can make graphene molecules consisting of up to 222 atoms (10 or so benzene rings in diameter). Still, there is a sea of difference between nanocrystals and macroscopic crystals that you can touch, measure and even look through. 81.104.93.72 (talk) 23:01, 24 April 2008 (UTC)

Thank you both for your thoughtful comments. I agree there seems to be nothing new under the sun. But I do believe that the size does matter (at least, my girlfriend says so ;-).

YZhangfirst (talk) 23:11, 24 April 2008 (UTC)

I do not really understand why UMDNANO argues against Geim. Someone has to be credited for the discovery of graphene and he is a single focal point for this. Of course, there were bits and pieces known before but the breakthrough came from his group, as even UMDNANO agrees. In any case, this is a done deal. Geim got the Mott prize for "the discovery of graphene" (I just added this to Andre Geim page). One can of course argue that this is a British prize and they can be biased (but probably less than one guy called UMDNANO). I googled further and found that Geim's associate Kostya Novoselov got a young scientist European prize (Kurti or something) for "his part in the discovery of graphene". Novoselov also listed as a 2008 prize winner from "International Union of Applied and Pure Physics". I did not find the citation line there but it is probably similar.

So whom should we trust? British, Europeans, Internationals or UMDNANO? Let us return the Discovery page to the original state of Carbophiliac (I have no time now - please do).

DrWhoever (talk) 11:54, 25 April 2008 (UTC)

I'll comment on this. It is abundantly clear that Andre Geim has discovered something, but this is science, so we should be careful about defining what he discovered. Certainly Geim made the first electrical transport measurements on graphene, and these measurements were instrumental in showing that graphene's electronic properties were those described by Wallace in 1947 (i.e. massless Fermions). Geim's 2004 paper is also incontrovertably the work that started the explosion of interest in graphene. However, Geim no more "discovered graphene" than Bednorz and Müller discovered superconductivity. Bednorz and Müller still won the Nobel prize, and Andre Geim still might.

It is clear that the concept "graphene" existed theoretically and experimentally well before 2004. The IUPAC definition of "graphene" dates to 1995! And surface scientists were studying graphene for years (there are literally dozens of paper on this, by some very prominent scientists, this is not some obscure stuff that no one knows about). Also, Walt de Heer's group has shown that graphene on silicon carbide, which has been studied since 1975, has the same massless Dirac Fermion properties as Geim's graphene. So, is graphene on SiC still "graphene"? Did Geim discover it? I think the answer to the first has to be yes, and the second, no. Yet, Geim was the first to show that graphene on SiO2 really behaves like graphene, by doing electrical measurements, and he beat de Heer to this.

It appears to me that the Mott prize committee tried to solve this problem by awarding Geim the prize for "For his discovery of a new class of materials: free-standing two-dimensional crystals, in particular graphene." The key word is "free-standing". What does it mean? It seems to refer to graphene free of any substrate, which Geim could possibly get the credit for, but only in 2007 (and the prize was announced in October, 2006!) So "free-standing" graphene needs a definition, and none is provided by the Mott prize citation. I would say "free-standing" graphene is graphene that is only weakly bound to a substrate, such that its electrical properties are similar to the isolated 2D crystal. Within this definition, Geim be be properly said to have "discovered free-standing graphene".

I'd be happy with any changes to the History/Discovery section that reflect this.

Umdnano (talk) 14:14, 25 April 2008 (UTC)

This is much better. Sounds like a genuine disagreement rather than a grudge.

Let me comment on this. I wrote a thesis on graphene, and it contained a long section on history of graphene and I continue to be interested in who, why and how in this story. It might be biased as most information comes from the articles Geim co-authored (Geim&Novoslov, Nature Mat 2007; Geim&McDonald, Physics Today 2007; Geim&Kim, Scientific American this year; one can download the copies from www.graphene.org as I did). But all the papers should have been refereed I believe, MacDonald is a famous theorist and Kim is Geim's arch-competitor. There is also Physics World by Neto, Guinea and Peres. I know Paco Guinea, and he is not a guy who would compliment everyone.

Those articles clearly say that graphene was known before as 1) an idealized system for theorists (like Wallace and Semenoff); 2) within chemically exfoliated soot/sludge; 3) as large molecules (PAH) or nano-graphenes; 4) as epitaxial layers. However, no one ISOLATED individual graphene layers (either microscopic or macroscopic); they all remained in bulk or on top and frankly no one was bothered at all about THOSE graphene layers. If people bother about them now and revisit the earlier studies (sometimes claiming hindsightedly how clever they are), then only because graphene has become interesting, AFTER Geim showed that it was a beautiful system.

Look at "graphene oxide" papers. Now it seems so straighforward to take graphite oxide known for more than 100 years and dissolve it in water to get monolayers. I doubt that the several groups now studying graphene oxide papers, films, etc. would be bothered to search for monolayers without being prompted by Geim's research.

It is not important whether graphene is suspended (as in references UMDNANO cites) or placed on another substrate. In both cases, it is isolated. This was not the case of (1),(2) and (3). I argue that it is not the case of (4) either. Graphene is chemically bound to either Ni, Ir or SiC. In the latter case, there is so-called first or dead layer which is not s-p^2 bonded and not conductive. Next layers resemble graphene or, maybe, graphite, I do not know. It is still debated, despite 4 years after Geim's Science paper. I doubt that anyone would be inteested in debating this without knowing how good graphene could be.

I also want to mention that in the case of Geim it seems to be not a straightforward, incremental step (this is why I agree with Carbophiliac who gave the guy such a nice credit). Both Geim and Kim previously referred to several efforts of mechanical splitting of graphite into thin layers. If I remember correctly, it was a Japanese group who first reported 100 layers in 1996 (in some very obscured journal). In their latest paper in Scientific American 2008, Geim&Kim apparently found a German group who did the same even earlier (1990 or so - there is no reference and I did not look for the paper yet). In any case, if you compare this with both Kim's PRL 2005 and McEuen's Nanoletter 2005, you find that there was little progress during the 15 years. Moreover, when Geim found the way of isolating graphene, he did not sit on the technology but disclose it widely. I doubt that this is common. My former boss would certainly kill all PhD students just in case they might leak a word (;-) I know first hand that Geim invited people to visit his lab for "tutorials on making graphene". Many groups did learn the trick directly in Manchester. This fact remains unacknowledged anywhere in literature (not everyone is as generous). This is why I vote for the Nobel for Geim. He deserves it, especially for "human reasons" (;-).

However, "discover" is indeed a very contentious word. I do understand the problems of UMDNANO with this word. Remember Columbus who discovered America, didn't he? Or was it discovered before him? or it was never discovered as natives lived there all the time. Technically, Geim was first to isolate graphene. "the isolator of graphene" (;-) - does not sound right. I would be also careful with word "discoverer" but in this particular case I feel the guy deserved it.

This is probably all I know and can add to the discussion. Pity that this "memoir" cannot be added to the graphene article. All the best to you guys who can be bothered to read this.

DrWhoever (talk) 20:51, 25 April 2008 (UTC)

This was interesting to read. I am located in Manchester and know people from the group of Prof Geim. As for me, Dr Who? is more or less right. And indeed the graphene tutorials still go on.81.104.93.72 (talk) 23:00, 25 April 2008 (UTC)

I tried my best to accommodate this discussion in the main article.

YZhangfirst (talk) 15:09, 27 April 2008 (UTC)

• I think the "Occurrence" and "History" sections should be combined into one section: there is a significant overlap. "Occurrence" is the wrong word anyway; this section is about the discovery/isolation/fabrication, whatever you want to call it. 81.157.196.227 (talk) 02:12, 28 April 2008 (UTC)

I agree but because Carbophiliac's entry caused such a negative reaction of Umdnano, I would rather wait for a few weeks for the dust to settle. I feel that Carbophiliac writes better than me, and maybe he could do this eventually. —Preceding unsigned comment added by YZhangfirst (talk • contribs) 09:56, 28 April 2008 (UTC)

I am more-or-less fine with the way this is shaping up, but there's one thing that still bothers me. I believe that the argument against 2D crystals being possible was put forth ex post facto. That is, I don't think anyone expressed the idea that the impossibility of 2D crystals was responsible for the failure to isolate graphene before 2004, and there is ample evidence that many groups were working on this (McEuen, Ruoff, Kim, de Heer, etc.). (As an aside, several groups were inspired by the successful isolation of single-layer crystals of transition metal dichalcogenides, though this work never gained much attention, and probably can't be used to discount the 2D argument, since these crystals are three atoms thick.) This sounds like a rewrite of history to match a cliche: "..the lone scientist doesn't heed the skeptics who say it can't be done, and succeeds to do the impossible..."

So, can anyone produce evidence that isolated graphene was thought impossible before 2004?

Umdnano (talk) 13:47, 28 April 2008 (UTC)

Let me try to answer this.

There is so-called Mermin-Wagner theorem that rigorously forbids the existence of perfect 2D matter (see section Mechanical properties). It goes even further back in history to Landau and Peierls in 30th. Thermal fluctuations are too powerful in 2D and induce defects at a finite temperature. This is it, from the point of view of theory.

People still argue why graphene exists. I witnessed a confrontation at a 2006 conference when a speaker (theorist) told that graphene would be unstable without a Si substrate, referring to the theorem. When someone from the audience mentioned then-unpublished results by Meyer et al (Nature 2007), the speaker answered that they should be wrong. In this paper, Meyer and Geim argue that ripples help to stabilize graphene crystals because not completely flat 2D matter becomes more stable (see section Mechanical properties). Another line of thinking (which sounds more reasonable for me)is that the crystals used in experiments are too small for the theorem to work at room temperature (there should be a critical size at which dislocations start appear). However, graphene should become unstable at higher temperatures, well below the melting temperature of bulk graphite. No one has studied this physics so far.

I will comment on the earlier experimental efforts, and the cliche tomorrow.

DrWhoever (talk) 10:41, 29 April 2008 (UTC)

I am quite familiar with Mermin's result and previous work, and the argument against the existence of 2D crystals. My point (which is illustrated nicely by your anecdote of the conference speaker) is that the Mermin's result has nothing to say about graphene on a SiO2 substrate as discovered by Geim in 2004. There is a reasonable argument to be made that many expected graphene without a substrate not to exist on the basis of the Mermin-Wagner theorem, but I cannot see how this can be applied to graphene on a substrate, which was already known to exist in 1975, and is what was reported by Geim in 2004.

I agree that the graphene crystals studied this far are quite possibly too small for the Mermin-Wagner theorem to apply. Mermin states in Phys. Rev. 176, 250 (1968) "Note that the exact bound (26) may well be so weak as to allow two-dimensional systems of less than astronomic size to display crystalline order."

Umdnano (talk) 19:50, 29 April 2008 (UTC)

In my opinion, the argument against 2D crystals is slightly more than ex post facto as you put it. First, the theory indeed has never argued against the existence of isolated (free-standing) graphene but it argues against its growth. The latter requires high temperatures at which the Mermin-Wagner theorem is quite valid without "astronomic sizes" involved. This is why the 222 carbon structure seems to be the very limit for graphene molecules. Anything much larger is simply impossible to grow. Second, the growth on metallic substrates and SiC is 3D and requires a matching crystal lattice. In my opinion, graphene cannot be called isolated in this case. Certainly not for the metal subsrates. SiC is a bit special, more complicated case but anyway graphene is isolated much less than in Geim's case. There is this "dead" layer that looks like graphene but 100% bound to the SiC substrate. "Epitaxial graphene" is what is grown on top of the dead layer, like new graphene layers can be grown on top of graphite. In this sense, "isolated graphene" was also found on bulk graphite (see A. M. Affoune et al, Chem Phys Lett 348, 17 (2001)). Third, Meyer et al referred to the Mermin-Wagner theorem in order to explain the observed non-flatness of suspended graphene. I know that it is hotly debated whether this non-flatness is intrinsic but if it is this would prove the impossibility of strictly 2D matter post ex post facto, which would be interesting. Enough for today.

I believe that most people assume term graphene to be 100 years old (or at least 50). The ref to the 1987 paper is very helpful.

DrWhoever (talk) 09:49, 30 April 2008 (UTC)

Here is my final word in defence of Geim who discovered graphene, at least from an experimentalist's point of view. Umdnano refers to Bednorz and Müller who "discovered high-Tc superconductors". Of course, those compounds were known and even electrically studied earlier but no one put them in a helium cryostat before. Similarly, de Heer took graphitized SiC (the technique known since 1975) and measured for the first time its electrical properties. An incremental step one may say but it was important and would probably bring him fame if the graphitic layers showed as nice properties as those of Geim's graphene. No one would notice de Heer's "epitaxial graphene", if not for real graphene.

Geim's group did much much more than just measured electrical properties of a previously known material (as Umdnano implies). They introduced a new experimental system from scratch. Although no one seems to have argued that a single atomic plane of graphite is impossible to exist (there are many things impossible - why bother?), no one isolated graphene or was even close (leaving aside studies of graphene).

The first cited report of micromechanically thinned graphite was in 1990 (Seibert et al, PRB 42, 2842). It was a film of ~ 100 layers in thickness (optical studies). Then came a Japanese experimentalist Y Ohashi in Tanso 180, 235 (1997). The graphite films were even thicker but those were the first electrical measurements of thin graphite. There were also many observations of thin graphitic films on top of graphite. The one that stands out is by Ebessen & Hiura, Adv. Mater. 7, 582, 1995 (~10 layers) and the one that does not (but often cited) is by Ruoff's group who showed a few SEM images of very thick graphite pancakes (APL 75, 193, 1999). In 2005, Kim's and McEuen's groups reported electrical measurements on graphite films of ~30 layers in thickness (they were not aware yet of Geim's work). As one can clearly see, there was little progress during the two decades until Geim's group came up single-handedly with monolayer graphene in 2004 and not only observed but measured it too.

There is nothing new under the sun but in this case Geim's step was not as incremental as by say Iijima or, for the matter, Bednorz and Müller and many other Nobel winners.

DrWhoever (talk) 11:13, 4 May 2008 (UTC)

This probably won't get noticed, but I should point out that I actually said that saying Geim "discovered graphene" was like saying Bednorz and Müller "discovered superconductivity", not "high-Tc superconductors", which they did, in fact, discover.

Umdnano (talk) 21:43, 19 May 2008 (UTC)

There is a difference between discovering something and discovering a way to isolate it. Geim should be credited with developing the method of extracting graphene, but I and probably many others learned in school that graphite is made of layers of carbon (which werent called graphene but were exactly the same thing) and it was also explained how the layers are not bound to themselves and how they slide against one another and leave chunks (not graphen) behind when you write with graphite. Not only it sounds silly It makes the scientists look bad for overstating his achievement (which is a serious crime for a scientists) although he might not be the one who propagates this.

I removed the part of the quote which said Geim managed to "fool" nature, people who think they can fool nature are only fooling themselves, lets not propagate their childish way of thinking.195.242.255.83 (talk) 11:38, 4 May 2008 (UTC)

My intention has been to defend people like Geim (and de Heer too) against other people who have a strong hindsight bias and, after being explained, start thinking that they actually knew everything from school.

DrWhoever (talk) 14:18, 4 May 2008 (UTC)

Wow! People were busy during the last 2 weeks - it took time to read all this. Why so much agression?! Relax - it is not your discovery anyway ... even if it is a discovery. Actually, in their review article (Nature Materials 2007) Novoselov and Geim called it "experimental discovery of graphene" (first page). Of course, you would not expect from them to diminish their own achievements, would you? So, there is no point for Dr Whoever to go further than Geim suggests. In my opinion, "experimental discovery" sounds fair and, nota bene, this notion passed through referees and editors who I admit should probably understand more than at least I do. Carbophiliac (talk) 14:57, 4 May 2008 (UTC)

Actually, the full phrase that you quote from Geim's article is "2D materials were presumed not to exist, until 2004, when the common wisdom was flaunted by the experimental discovery of graphene7 and other free-standing 2D atomic crystals (for example, single-layer boron nitride and half-layer BSCCO)8." It is clear that "free-standing" must also modify graphene here. This is further clarified in the same article later: "On the other hand, single- and few-layer graphene have been grown epitaxially by chemical vapour deposition of hydrocarbons on metal substrates28,29 and by thermal decomposition of SiC (refs 30–34)... Epitaxial growth of graphene offers probably the only viable route towards electronic applications and, with so much at stake, rapid progress in this direction is expected." This makes it clear that epitaxial graphene is graphene. So Geim should be credited with the "experimental discovery of free-standing graphene", which is in accordance with his citation for the Mott Medal in 2007. "Free-standing graphene" is defined as graphene isolated electronically to a degree that its electronic properties are well described by those of a single graphene sheet.

In any case, to maintain a neutral point of view, an authoritative source written by other than Geim should be used to reference the acceptance by the scientific community that Geim is the discoverer of whatever it is he discovered. The Mott Medal citation should be sufficient, and hence Geim should be credited with the "experimental discovery of free-standing graphene". Note that publication in a scientific journal is not enough; please see the discovery of carbon nanotubes. In that case, hundreds of papers have referred (incorrectly) to Iijima as the discoverer of carbon nanotubes.

Umdnano (talk) 16:24, 13 May 2008 (UTC)

Is there any fairness in this world? Iijima is often credited with "the discovery of carbon nanotubes", but he can maybe argue that he saw a single-wall nanotube first. Nothing else! Geim has done much more. Can one argue against his discovery of graphene being conductive and high quality? He was certainly first there. About the anomalous quantum Hall effect and non-vanishing conductivity in graphene? About the [experimental] discovery of Dirac fermions in graphene? The discovery of chiral quasiparticles with mass in a bilayer? What about the fine structure constant seen through graphene using a microscope? Come on, guys.

Whatever you say, Geim is a single focus point in the whole area and he opened it single-handedly. It is a human nature to lessen other people's achievements [as well as exaggerate your personal achievements]. Don't be like lawyers. Someone has to be credited with the discovery of graphene, and I cannot see anyone else who would even marginally deserve such a credit. —Preceding unsigned comment added by 213.174.113.122 (talk) 09:46, 17 May 2008 (UTC)

By your logic, Richard Smalley discovered the single-walled carbon nanotube, and Stuart Parkin discovered GMR, and Donald Eigler invented the scanning tunneling microscope.

Umdnano (talk) 21:34, 19 May 2008 (UTC)

It seems to me that who discovered graphene should be a matter of fact, not of fairness. I agree with many of the statements by 213.174.113.122 above. All of the following seem reasonable to add to the history section in some form or another:

"Geim made the first electrical transport measurements on graphene, showing it to have high carrier mobility"

"Geim and Kim discovered the anomalous quantum Hall effect in graphene"

"Geim and Kim discovered massless Dirac Fermions in graphene"

"Geim discovered massive chiral quasiparticles and an anomalous quantum Hall effect in bilayer graphene"

"Geim discovered that the transparency of graphene measures the fine structure constant"

But I don't understand the argument that because Geim has done so much pioneering work in the field, we should decide "out of fairness" that he discovered the material. I also don't agree that "someone has to be credited with the discovery of graphene", certainly there are plenty of materials for which no one is particularly honored for the discovery. I think that its quite clear that (without cooking up an extremely tortured definition of "graphene") that graphene was already around and being studied before Geim, but it was Geim that showed how interesting it is. For that, he quite possibly deserves to win a Nobel prize. But I don't see why we need to rewrite history. I mean, there were review articles written on the subject of graphene before Geim, for heaven's sake! Idosp2 (talk) 02:28, 22 May 2008 (UTC)

What reviews? There were no such reviews. You probably mean Dresselhauses' review on graphite or several others on carbon nanotubes or a couple on aromatic molecules? Nothing closer than this. Please do not confuse people.

As for the above statements that graphene is well known to children to exist within graphite, we also know that all crystals consist of atomic planes. Say, NaCl crystals can be cleaved along crystallographic directions. We do learn this at school. However, does anyone around dare to predict that a monolayer of NaCl can be isolated similar to graphene? Can SiC be cleaved to one atomic plane? It may be harder but is this possible? As already commented by someone, people can predict many things with the benefit of hindsight. I have recently read an article from a Berkeley group who doubt that Geim made a monolayer of BN in his 2005 PNAS paper. They could not make it and hence doubted. Graphite and BN are very similar materials with respect to their crystal structures. I do not care about electronic properties but

"Geim was first to prove that individual atomic planes can exist outside bulk crystals"

Carbophiliac (talk) 17:45, 22 May 2008 (UTC)

For a review, see Oshima and Nagashima, J. Phys.: Condens. Matter 9, 1 (1997). Epitaxial graphene is graphene (even Geim calls it graphene in his Nature Materials review article). In many cases, it was shown by ARPES (well before 2004) to have the electronic structure of graphene (i.e. massless dispersion relation). There is simply no definition of graphene except the most tortured that can include graphene bound to a silicon dioxide substrate but exclude graphene bound to, say, titanium carbide, where it has been shown that the electronic structure of the carbon monolayer is that of graphene.

The statement "Geim was first to prove that individual atomic planes can exist outside bulk crystals" could only be true by a technicality, i.e. Geim showed that graphene could exist tied to an amorphous substrate (SiO2) rather than a crystalline substrate. This was the state of things until 2007, when possibly two groups could claim to have been the first to make graphene free of any substrate (Siegmar Roth's group, and Paul McEuen's group).

As I pointed out above, there are many well-defined firsts to which Geim can claim credit. I think rather than coming up with some tortured definition of graphene so that Geim can lay claim to discovering it, it would be more appropriate to use language such as "Geim is the father of modern graphene research" or somesuch to describe Geim's role.

Idosp2 (talk) 23:47, 22 May 2008 (UTC)

NB As I mentioned above, it was NOT the work by "Siegmar Roth's group". Geim is a corresponding author on this paper, and Roth is not. Geim was in exactly the same position on the author list in Science 2004. But this is really a technicality. Even if he was not, it is more than obvious that this paper as well as McEuen's one were initiated by Geim's earlier findings. In my opinion, suspended graphene was an obvious next step after finding it on SiO2, and both mentioned papers used the cleavage technique. YZhangfirst (talk) 09:52, 25 May 2008 (UTC)

The first author of the paper (Meyer) was a graduate student in Roth's group. The last author is Roth. The technique was pioneered by Roth's group, to suspend carbon nanotubes. All the experiments were carried out in Roth's group by Meyer. My statement that Roth's group could lay claim to being the first to suspend graphene is correct.

And, are you really suggesting that Geim should get the credit for McEuen's nanomechanical resonator work, on which Geim is not even a co-author?

Idosp2 (talk) 02:03, 26 May 2008 (UTC)

First, I cannot trust the anonym who claims that all the work was done by Meyer. I would like to know what the 5 other authors think about this claim. Second, I rely on facts rather than rumors. And the fact is that the first 2 authors in Nature 2007 are both corresponding. This normally means that they contributed equally or at least comparably. If Geim only supplied samples to Meyer, his student would be the second author. If for a moment we believe the statement that Meyer did all the experiments, this would mean that Geim approached him with the idea to do them. This would explain the author list. I have also noticed that Geim is not always a corresponding author even in the papers coming from his own group. He would certainly have an opportunity to fix his place as desired. This means that he tries to keep things fair (NB much more fair than many professors). Third, in Science 2004 someone called Firsov is the last author. Does this mean that the experiments were done in his group? And finally, I did not try to take away any credit from McEuen's group. It s a great group. All I said was that for people dealing with suspended nanotubes it was reasonably obvious to apply the developed techniques to graphene after it was discovered. If McEuen did not do those experiments, Zettl, Roukes or others would have eventually done. It is like with the fractional quantum Hall effect, someone will surely report it in graphene soon. It is a too obvious direction, without taking any credit from the person who will see it first. YZhangfirst (talk) 13:09, 1 June 2008 (UTC)

Let me point out that recently Geim and Novesolev have received the 2008 EuroPhysics Prize, and it cites "for discovering and isolating a single free-standing atomic layer of carbon (graphene) and elucidating its remarkable electronic properties". Experts are more generous in their credits than some contributors to this page.

—Preceding unsigned comment added by DrWhoever (talk • contribs) 00:01, 21 October 2008 (UTC)

References

When did Wikipedia discover graphene?

Apparently the first Wikipedia entry for graphene is dated 19 August 2004, before the publication of Geim's paper in Science. (OK, so Wikipedia didn't discover graphene, but my point is that there is an interest in having an encyclopedic entry regarding graphene even as it existed before Geim's work.)

Umdnano (talk) 16:09, 6 May 2008 (UTC)

To be fair. The first entry defines graphene as "a typical graphene would have the chemical formula C₆₂H₂₀. Graphenes are aromatic". How many people agree with this definition? The second entry on Oct 22 2004 adds a link to the BBC World article[2] which tells us that "a new class of material ... has been discovered by scientists", referring many times to Prof Geim who "leads the research team". —Preceding unsigned comment added by Absolutef (talk • contribs) 23:07, 7 May 2008 (UTC)

Lowest Resistivity?

(Moved from top of page to new section)

Is there any reference to the mentioned value of resistivity (caliming that is less than the resistivy of Silver) in the article? If yes, the reference should be provided. —Preceding unsigned comment added by 192.174.37.51 (talk) 20:58, 14 May 2008 (UTC)

This is in the press release at https://newsdesk.umd.edu/scitech/release.cfm?ArticleID=1621, but can be calculated from the information in the article itself: the sheet resistivity due to acoustic phonon scattering in graphene at room temperature is 30 Ohms/square. This is a 3D resistivity of 30 Ohms/square*3.4 Angstroms = 1.02x10^-6 Ohm-cm, compared to about 1.62x10^-6 Ohm-cm for silver. 3.4 Angstroms is the thickness of the graphene sheet.

I will update the reference on the main page.

Umdnano (talk) 14:54, 27 May 2008 (UTC)

Graphene by liquid-phase exfoliation

There is a report posted on ArXiv.org of production of graphene from graphite with 12% yield by mass using a liquid-phase technique[3]. (They have obtained single suspended sheets of graphene as imaged directly by TEM.) This is unpublished (for now) and hence probably shouldn't be part of the Wikipedia entry yet, but it points out a problem with the current organization of the "graphene" page: the Occurrence and History and Discovery sections are redundant, and don't really reflect their titles. I believe Occurrence should be renamed Synthesis and Occurrence, and list the current techniques for producing graphene (mechanical exfoliation, epitaxial growth, solution techniques) as well as the natural occurrences of graphene (in soot, in presolar onions and red-giant stars, etc.). These should probably have individual sub-heads. The historical information in Occurrence is already reflected in the History and Discovery section.

Opinions?

Umdnano (talk) 15:18, 27 May 2008 (UTC)

I noticed this too. In my opinion, it is the same micromechanical cleavage but on industrial scale (ultrasound instead of scotch tape). What puzzles me is that no one did it before, despite 100 years of intercalation. Someone should have done this and, because it is so important, we will soon hear claims that it was well known ;-) I cannot believe that it remained undiscovered before the snowball started by Geim's group. Occurrrence is an ugly word in my opinion. YZhangfirst (talk) 13:44, 1 June 2008 (UTC)

I hate to defend the Manchester group again but I try keep this discussion fair. They reported the same ultrasound exfoliation technique in organic liquids earlier[4]. Already published as I saw a press release too. —Preceding unsigned comment added by Absolutef (talk • contribs) 20:20, 1 June 2008 (UTC)

Graphene Nanoribbons

Graphene nanoribbons are distinct from Graphene. There are serious changes in the electronic structure such as a finite bandgap, excitonic effects, and chiral dependence to properties. Therefore, this class of materials deserves its own page.

I moved the above unsigned comment (from History, it was written by Tm2008 on 14:57, 14 June 2007) from the top of the page to this new section, rather than simply delete it. It seems to be orphaned.

The point is apparently now moot, since there is a Wikipedia page for Graphene nanoribbons.

Idosp2 (talk) 02:03, 28 May 2008 (UTC)

Hardness

Is pure graphene harder than diamond?

Referenence: [5]

David (talk) 00:17, 15 August 2008 (UTC)

No, I don't believe it is meaningful to talk about 'hardness' with respect to a material which is only one atom thick. You must be careful, as 'hardness' and 'strength' are not the same thing - in the reference article you linked, they did not actually measure hardness (I believe) though their methodology was similar to that of a hardness test. Andipi (talk) 09:51, 11 October 2008 (UTC)

Potential Applications

I noticed that despite references to its incredible strength, the "potential applications" sections gives no relevant suggestions. I recall reading in New Scientist something about a few sheets being able to support the weight of a person, and a few mm supporting a car, or something along those lines. I shall try to find the issue and give it as a source, but i appear to have misplaced it :(

User:Taxi4dave (talk) 01:03, 23 September 2008 (UTC)

Ultracapacitors

Just added a little subsection on ultracapacitors to the 'potential applications' section of the article. It's fairly brief, does anyone think more detail should be added? I heard somewhere that it's believed that graphene ultracapacitors may well double the energy density of current ultracapacitors, but can't yet find a good reference to back this up. The reference I have added comes directly from the website of University of Texas, Austin, and not a journal, though I believe it has been published somewhere (not sure where). Is this acceptable? Andipi (talk) 19:09, 29 September 2008 (UTC)

No reference anywhere in the article to double bonds

Incredibly, there is no mention anywhere in the article that each carbon atom in graphene has two single bonds and one double bonds. Nor does the "chicken wire" diagram show the pattern of double bonds. It's this lack of elementary (but useful) information that makes Wikipedia science articles like this one so daunting for the non-technical reader. Ross Fraser (talk) 21:14, 25 November 2008 (UTC)

In chemistry language, graphene is aromatic, like benzene, and there is no distinction between single and double bonds. Each pair of carbon atoms is bonded by a single sigma bond. The pi bonds are delocalized, and do not belong to individual pairs of atoms. The delocalized pi bonds are responsible for electrical conduction of graphene. The degeneracy of the bonding and anti-bonding pi bands at the K point in momentum space is what gives rise to graphene's unique "massless" electronic structure.

Umdnano (talk) 17:49, 24 December 2008 (UTC)

In fact, the chemist's distinction between single and double bonds seems secondary at this place (not only because of the above-mentioned delocalization, but because one is dealing with intrinsically physical phenomena, going back to primary phenomena of quantum mechanics). In fact, what is more important is that one gets a realization of the pseudo-relativistic quantum mechanics, the Dirac theory. —Preceding unsigned comment added by 132.199.38.133 (talk) 13:01, 16 March 2009 (UTC)

Removal of rapid DNA sequencing section

I removed the section "Rapid DNA Sequencing". The claim that graphene can be used for rapid DNA sequencing is not verifiable, and appears to be original research. This section referenced an unpublished article by Henk Postma, and an interview with same. (Note: The interview verifies that Dr. Postma made the claim that graphene could be used for rapid DNA sequencing, but does not verify the claim itself.)

The article by Kyaw et al. is published, but doesn't merit an entry on this page.

Note that nanopore sequencing has a Wikipedia page if you would like to read about it. The technique is still an unproven concept. An unproven concept for improving an unproven concept is not an application of graphene.

129.2.99.25 (talk) 16:35, 24 February 2009 (UTC)

Bonding with amino acids?

Can graphene be bonded to an amino acid in much the same way as C60 buckminsterfullerene can? C60 + R1 amino acid + R2 aldehyde --microwave heating--> 5-member amine ring with R1 and R2 adjacent to the amine terminal? (see "Microwaves: a new tool for an ancient element?" "Chemistry Today" Vol 25 nr 2 March/April 2007). If so, what are the limits on the size of the graphene sheet (a sufficiently large conducting sheet interacts with microwaves in its own ways)?Zaphraud (talk) 06:45, 14 March 2009 (UTC)

Transition to graphite

I am moving out of the article the statement

"The onset of graphene properties, as compared to those of a PAH are not known. PAHs of 60, 78, and 120 carbon atoms have UV absorbance spectra that show a discrete PAH electronic structure, but a PAH of 222 carbon atoms has Raman bands similar to those in graphite."

The question is fundamental and interesting, but must be justified with proper references before inserting into the article. All I could find on Raman is this article, which shows no difference between C114H34 and C222, and this one, which does not seem published, and does not show clear transition for C60, C132 and C222. NIMSoffice (talk) 00:21, 24 April 2009 (UTC)

citation style

It seems to me that this is a promotion article for A. Geim's Group and partners and not am objectiv view on this topic. All authors from non-Geim articles are abbreviated with "et. al." and only the articles with Geim's name in the authors list are written out totally. So it seems to me that somebody wants to increase A. Geims hitlist. A comment to "SiC-Reduction": It is not right that SiC is reduced. Silicon atoms sublimate form the material and Carbon atoms are left. Graphen is formed by reorderimg the Carbon atoms. It is rigt that SiC is very expensiv, but this approach is as good as forming graphen with other production methods, and actually I dont know why it should not be possible making good devices out of it. At the beginnig Silicon was also expensiv, so please don't bash it, be objective. It is also not right that you can't use SiC substrate is not compatible with most fabrication techniques needed to create electronic devices. You can use standard techniques, because i did it and some others, like SIEMENS, also did it. So, please be objective and create a consistent citation style where nobody is emphasized, talk objective on each topic and do not make an "A. Geim-promotion-article". Never the less, have a nice day.--84.181.181.25 (talk) 07:08, 25 April 2009 (UTC)

I have fixed SiC growth. Regarding the names, ideally, they should contain all authors. 1st author et al. is a standard omission originating from reluctance to tedious typing. There is no any prejudice to Geim's group in this practice, just some references were typed by more diligent editors :) NIMSoffice (talk) 07:39, 25 April 2009 (UTC)

I was interested in this observation and considered changing my paper's citation. But now I am confused. I see many Geim's articles (starting with Novoselov, Morozov, Schedin, Nair -- probably more) which are all abbreviated with et al. His name is only on those with one or two authors. Sounds OK. —Preceding unsigned comment added by 208.54.90.28 (talk) 00:27, 2 December 2009 (UTC)

note

this was in headlines today. --Steve, Sm8900 (talk) 16:42, 9 July 2009 (UTC)

example: [6] Powers ^T 16:55, 9 July 2009 (UTC)

Largest PAH

I don't understand the following:

"In this regard, graphene has been referred to as an infinite alternant (only six-member carbon ring) polycyclic aromatic hydrocarbon (PAH). The largest molecule of this type consists of 222 atoms and is 10 benzene rings across."

Can't arbitrarily large molecules of this type exist? And aren't a whole mixture of them created during the production of graphene fragments? I think the second sentence needs some conditions attached, along the lines of "intentional synthesis of a 'reasonable quantity' of identical molecules", but I don't know what the exact wording should be. 86.133.48.238 (talk) 02:43, 21 November 2009 (UTC).

Effective mass

In the articles it's written that : " It was realized early on that the E-k relation is linear for low energies near the six corners of the two-dimensional hexagonal Brillouin zone, leading to zero effective mass for electrons and holes " . So it seems that the linear dispersion leads to zero effective mass. On the other hand if one has a look on the definition of effective mass it's possible to see that a linear dispersion would lead to an infinite effective mass.

The reason why the graphene has zero effective mass is the following. The graphene has linear dispersion near the Dirac points and the conduction and valence bands cross exactly at the Fermi level. This relation is the same as the relation among energy and momentum for relativistic particles of zero mass , E=sqrt(m2c4+p2c2)=pc=hkc , and the conduction and valence bands can be identified as particles and anti-particles of a massless Dirac theory. On the other hand the usual definition of effective mass holds for particles which are described by the Schroedinger equation and so should not hold here. I think this point could be better explained in the article. Dave (talk) 13:40, 7 January 2010 (UTC)

"presumed not to exist"

I would like a reference for this claim, or it should be removed. The reference provided to Geim, A. K. & MacDonald, A. H. Physics Today 60, 35-41 (2007) is inadequate. It does not address this claim, and even if it did, the article is published after the Geim's isolation of graphene in 2004 (so it cannot be an original source of evidence that graphene was presumed not to exist before 2004). There is already much evidence to the contrary, that it was presumed possible to make graphene before 2004. Several research groups (Rodney Ruoff, Paul McEuen, Philip Kim) were working on making isolated graphene by one technique or another before 2004. Ruoff published his effort in 1999 in a paper titled "Tailoring graphite with the goal of achieving single sheets" (Nanotechnology 10, 269 (1999)). These researchers may have failed, but it is clear they at least thought they could succeed. Furthermore, since single-layer graphene on SiC was first produced in 1975, and is now known to be "isolated graphene" (i.e. shows 1/2 integer quantum Hall effect), the claim is possibly nonsense on its face. Idosp2 (talk) 16:13, 11 January 2010 (UTC)

Indeed the statement may now sound strange. But trying to be objective, I also remember that 10 years ago speakers at every CNT conference claimed that graphene sheets should roll up to “minimize their energy”. It is easy to find references.

Do free monolayers of boron nitride or mica exist? Geim’s group claimed that they observed those. I have not seen any confirmation yet. I doubt. Maybe, few layer thick. If by chance other monolayers are also possible I am sure that people will appear soon to claim that they knew this all along and observed earlier (-;.

Don’t we suffer from hindsight bias? Absolutef (talk) 13:40, 12 January 2010 (UTC)

This isn't hindsight. The "presumed not to exist" statement was not justified in 2004. The references cited in the 2004 paper do not support it. There's a difference between a graphene sheet in free space, which would likely roll/crumple, and the same on a substrate, such as SiO2. Interaction with the SiO2 stabilizes the sheet just as on the materials mentioned above.

The statement slipped through in 2004 and has been self-propagating since then. --Googolit (talk) 16:20, 12 January 2010 (UTC)

OK, man. I do not really want to defend this statement … but I read the 2004 paper only last year including! its SI. Indeed, there are many errors which slipped through as you said. The shown spectra are obviously wrong, no Dirac particles, no Berry phase and so on. There were no single layer measurements either. Monolayers came online later.

However, I do not accept the argument about the silicon oxide needed for not crumpling. This is wrong. Neither of the graphene contributors seem to have noticed that the 2004 technique was rather different. Geim and Co deposited graphene from acetone or something, not mechanically. Therefore, graphene was floating in liquid before falling down on the substrate. Ruoff and others showed that one could make concentrated suspensions of such flakes. They obviously do not roll up. Geim should have levitated them (-; Somebody will.

Should I put “presumed by most researchers not to exist” (?) Fair? Absolutef (talk) 17:01, 13 January 2010 (UTC)

I attended the same conferences on nanotubes. I discussed the possibility of obtaining graphene sheets with many researchers. I never met anyone who thought graphene could not exist. But this is just hearsay, and your claim is also hearsay. Could you please provide a reference showing that "most researchers" presumed graphene could not exist before 2004?

Idosp2 (talk) 03:18, 17 January 2010 (UTC)

Does not this statement simply refer to the Mermin Wagner theorem? No long range order in low dimensions ...

Of course, the theorem does not forbid small 1 or 2 D crystals at temperatures much lower than the melting temperature. Rippling of graphene also helps. These points are discussed in the Physics Today article and are certainly correct. Antonsince (talk) 14:08, 17 January 2010 (UTC)

Do you have a pre-2004 reference that states that micron-sized graphene crystallites at room temperature should be forbidden by the Mermin-Wagner theorem? I think most physicists pre-2004 would have found this conjecture silly, and at the least would have asked for an analysis such as the one done in arXiv:0807.2938, which shows that the Mermin-Wagner theorem applies to graphene crystals larger than the size of the known universe. This analysis was done post-2004, however that is sensible, because the Mermin-Wagner theorem was invoked only after the 2004 isolation of graphene. Do you have a reference to the Mermin-Wagner theorem as applied to graphene pre-2004?

Idosp2 (talk) 14:47, 18 January 2010 (UTC)

This is getting silly. The WM theorem is for all low-D structures. Of course, there were no pre-2004 papers discussing this theorem for graphene. Neither were/are there any papers about the stability of free standing monolayer of say Au and Si. No one discusses things irrelevant at the time. I presume that the former structures do not exist as macroscopic pieces at room temperature. I am not so sure about Si … but only with hindsight as absolutef said. I give up – you may have the last word.Antonsince (talk) 09:57, 19 January 2010 (UTC)

I concur completely that this is silly. Either M-W forbids the existence of graphene, or it does not. Graphene exists, hence the M-W theorem does not forbid it. It is not enough to say that "people believed in M-W, therefore people believed graphene could not exist." This is not true, because the contrapositive "graphene exists, therefore people do not believe M-W" is not true; M-W still holds. So, you must show that people believed that M-W forbid finite-sized two-dimensional atomic crystals existing in three dimensional space (which it of course does not).

Idosp2 (talk) 16:15, 19 January 2010 (UTC)

Book ‘’Nonexistent Compounds’’ by Dasent 1965 (Dekker) includes flat molecules larger than few benzene rings. Graphenephd (talk) 13:52, 22 January 2010 (UTC)

Thanks for this.

People who wrote, even in passing, that graphene could exit had already come forward. Would you be able to find those 2 or 3 papers yourself?

I looked through a couple of those references that according to Googolit did not support the statement. In fact, Ref 7 states the following: “There are several studies that investigated the stability of nanotubes relative to graphene. For example, graphene is the least stable structure until about 6000 atoms.” The review shows that various 3D shapes are more stable than graphene (for sizes <10 nm). Of course, if you know how to jump directly to macroscopic graphene without passing the stage of smaller sizes …

Absolutef (talk) 10:39, 23 January 2010 (UTC)

Please read this reference more carefully [Shenderova, Zhirnov and Brenner, Critical Reviews in Solid State and Materials Sciences, 27, 227 –356 (2002), Ref. 7 in Geim's 2004 paper]. The passage you cite refers to the thermodynamic stability of graphene relative to other forms of carbon. A material does not have to be the most thermodynamically stable form to exist! The histories of chemistry and material science are essentially methods to make metastable compounds and materials. You and I are metastable. Diamond is metastable relative to graphite. Trinitrotoluene can be synthesized, and it is most certainly not at its minimum energy state!

Furthermore, the graphene sheet is the thermodynamically most stable configuration in the limit of large numbers of carbon atoms. This is indicated in Ref. 7 and the references therein. The reason that it is less stable for small numbers of carbon atoms is the dangling bonds at the edge, more easily satisfied in a nanotube or fullerene, at the cost of curvature energy. For e.g. long nanotubes vs. large areas of graphene, every atom in the nanotube pays the curvature energy cost, but the graphene edge to volume ratio gets smaller and smaller. This explains the fact that a small transition-metal cluster will catalyze the growth of a nanotube, but a metal surface will grow graphene.

Reference 7 says nothing about graphene being impossible to synthesize in principle. If this were the commonly-accepted belief in the scientific community, one might think it would be mentioned in this 130-page article that discusses in detail the synthesis of different forms of nano-carbon. To the contrary, "single graphene sheet" is listed in Table 3 along with other forms of carbon, with a reference to its experimental existence. We can argue about whether this is "really" graphene, but this is strong evidence that graphene was presumed to exist in 2002 by the scientific community.

Idosp2 (talk) 13:26, 26 January 2010 (UTC)

I undid the edit by Urianway on 12:33, 26 January 2010 which implied that the thermodynamic stability of graphene relative to fullerenes and nanotubes prevents bottom-up synthesis of macroscopic graphene. This is incorrect. (The rational synthesis of a 222-carbon graphene fragment, mentioned in the same paragraph, proves that this is incorrect; a 222-carbon graphene fragment is already thermodynamically unstable relative to nanotubes and fullerenes, and adding more carbons makes it more stable, not less.)

Idosp2 (talk) 15:25, 26 January 2010 (UTC)

Please do not delete my work. I read the article after it was mentioned above. Because your opinion contradicts this review, you should add another literature source saying that >222 atom molecules should be stable. —Preceding unsigned comment added by Urianway (talk • contribs) 17:51, 26 January 2010 (UTC)

The section as written is incorrect, contains claims that are unsupported and unverifiable, and is not relevant to the rest of the section. Specifically:

"It has proven difficult to synthesize even slightly bigger molecules" is unverifiable. Synthesis of larger molecules has not been reported, but it is not clear that this is even being pursued. Add a reference, or remove this sentence.

"macroscopic graphene molecules might be impossible to synthesize from a bottom-up approach" is unsupported by any reference. It is true of course, since it contains the weasel words "might be". But this makes the statement meaningless. Remove the weasel words and add a reference, or remove this sentence.

"Indeed, ab initio calculations show that a graphene sheet is thermodynamicly (sic) unstable with respect to forming various 3D structures (fullerenes) if its size is less than ≈10 nm (“graphene is the least stable structure until about 6000 atoms”)." This is irrelevant and misleading for two reasons: (1) Thermodynamic stability has very little to do with the possibility of synthesizing a substance (see what I wrote above). (2) The statement applies to graphene fragments, but not polycyclic aromatic hydrocarbons (i.e. graphene fragments terminated by hydrogen. I suspect that PAHs are indeed thermodynamically stable compared to fullerenes, since they do not suffer the curvature energy of fullerenes, yet all their bonds are saturated. This sentence should be removed completely.

Lastly, these sentences are not relevant to the overall section (description of graphene). Personally I would like to remove these sentences as well as the preceding sentence ("The largest molecule of this type consists of 222 atoms and is 10 benzene rings across"). None of this has much to do with graphene.

Idosp2 (talk) 02:02, 27 January 2010 (UTC)

I added an improper synthesis tag to this section as well. The improper synthesis is schematically "PAHs greater than 222 carbons have not been synthesized" plus "graphene fragments less than 6000 atoms are unstable" equals "macroscopic graphene molecules might be impossible to synthesize from a bottom-up approach". Besides the fact that this is logically problematic (222 is also less than 6000, so the argument implies that PAHs smaller than 222 carbon atoms also cannot be synthesized, which is contradictory), the synthesis is improper because thermodynamic stability does not determine whether a compound can be synthesized .

Idosp2 (talk) 02:29, 27 January 2010 (UTC)

Life on the moon? If found, surely we will find many smart ones to claim that they never presumed it not to exist … ;-t —Preceding unsigned comment added by 68.230.199.107 (talk) 16:58, 27 January 2010 (UTC)

I don't quite understand the analogy. Graphene has existed in the laboratory for at least 35 years, and there are review articles written about the subject which date to pre-2004. The claim that it was presumed not to exist before 2004 is certainly the more fantastical claim. At least one can find written statements claiming that there is no life on the moon, if graphene's non-existence was a commonly-held belief, where is the evidence of this?

Idosp2 (talk) 22:49, 27 January 2010 (UTC)

I can also add [citation needed] to any sentence of idosp2.Urianway (talk) 22:26, 27 January 2010 (UTC)

Please do. Unverifiable claims shouldn't be allowed to stand; if I've made any, please tell me.

Idosp2 (talk) 22:51, 27 January 2010 (UTC)

P.S. I stop looking at these pages. idosp2 - have a free run with your opinion.Urianway (talk) 22:32, 27 January 2010 (UTC)

Take a look at the history page for graphene - quite a few authors contributed to this page and I can lay no claim to being more than a minor contributor!

Idosp2 (talk) 22:54, 27 January 2010 (UTC)

Interesting discussion but I am puzzled that it is still goes on after the reference to thermo. stability was put in. "Presumed not to exist" comes from on of the earlier papers from Manchester (doesn't it?) and then repeated many times by other groups. No one said "proved not to exist" or something like this. It is an assessment, and it is OK. Thermodynamic instability is a good argument for most people to think this way. The others of course could have their reservations. I guess idosp2 and his/her supporters would not argue that most people presumed graphene to exist. (NB I refer to free-standing graphene of course). KlausMn (talk) 09:44, 28 January 2010 (UTC)

I think you make my point for me: "'Presumed not to exist' comes from on of the earlier papers from Manchester". I agree completely. It is an ex post facto argument. The vast majority of scientists had not thought about this one way or another. Of the few dozen people I talked to about the possible existence of graphene pre-2004, not one ever said that he/she presumed it could not be synthesized. Quite a few said it had already been synthesized. This is anecdotal evidence, however there is also no evidence for the Manchester group's claim in 2004 that graphene was "presumed not to exist". As I have discussed above, the references in the Manchester group's 2004 paper do not support this claim.

Idosp2 (talk) 14:51, 29 January 2010 (UTC)

I'll provide some references to papers where authors expressed the belief that isolated graphene could exist before 2004.

Charrier et al. Journal of Applied Physics 92, 2479 (2002) state the following:

"The possibility to isolate a unique graphene plane over macroscopic dimensions has been inferred from the very flat out-of-plane diffraction profile, corresponding to the ‘‘ideal’’ 1D diffraction rods of a purely 2D crystal."

Lu et al., Nanotechnology 10 (1999) 269–272 state the following:

"To tailor graphite and obtain tailored graphene for further manipulation an appropriate sample stock is needed. One method of obtaining graphene is to grow it on an appropriate substrate, such as crystal surfaces of transition metals and metal carbides, by decomposing hydrocarbon gases at high temperature (Oshima and Nagashima 1997); it has been shown that a single-layer-thick sheet can be grown on such surfaces, but the average domain size is only several tens of nm (Oshima 1998). Another method is to use existing graphene in graphitic materials. HOPG is a suitable starting material for getting graphene, not only because of its availability in large quantity and in large-size pieces, but also because of its unique structure. It is polycrystalline with highly oriented graphene sheets; the typical domain size in HOPG is 1 to 10 μm in the basal plane and >0.1 μm perpendicular to basal plane (Moore 1973). The domain size in the basal planewas confirmed in our experiments described below." [emphasis is mine]

These authors clearly believed, pre-2004, that isolated graphene was a possibility.

Idosp2 (talk) 17:03, 29 January 2010 (UTC)

Oh yes, this "great" paper by Ruoff et al. Nanotechnology 1999 … It is promoted ad nauseum by himself. Ruoff "believed" in graphene. Fine. But did he substantiate his belief by any data? His thinnest flake was 100 nm thick! This is as far from graphene as a brick. If you believe in something, go and prove it. Ruoff just wrote a few phrases. Speculations in passing. Now he claims to be a graphene prophet. Ruoff also believes in various conspiracies. Ask anyone who worked with him. Should we presume them to exist? Why do you promote such unsubstantiated statements and argue so fiercely against the statement only mildly incorrect? 67.166.79.150 (talk) 10:46, 30 January 2010 (UTC)

Thanks to KlausMn for the nice reference on difficulty of rational synthesis of 2D polymers. Idosp2 (talk) 14:51, 29 January 2010 (UTC)

OK. Let me try to reconcile the two positions.

One side (idosp2 et al) probably reads the statement “presumed not to exist” as an exact, mathematical theorem. The other side reads it as a general assessment.

The latter side should probably agree that the statement is inaccurate. Clearly there were people who believed that graphene could exist. Thomas Ebbessen told in private that he isolated graphene well before Geim (using a similar technique) but he could not confirm the thickness and left the story unpublished. On the other hand, the idosp2 side should probably agree that the phrase is OK as an assessment of the situation before 2004 (see my previous note). We cannot be sure what Geim and colleagues meant when this phrase was written but it seems that they referred to the thermodynamic stability and nanoscroling. I am not sure that this phrase was put as a claim. This seems to be a later interpretation.

In my view, the human nature is very much behind this discussion. One side thinks that Geim and colleagues are given too much credit. The other side probably believes that people who announced their claims lately do not deserve credit for their hindsights. We like underdogs and dislike hotshots. But even more, we dislike pretenders. This is a delicate balancing act.

KlausMn (talk) 14:35, 30 January 2010 (UTC)

KlausMm, do you have alternate language to propose? I would really like to remove this statement for the page since it can't be verified, but maybe there is some alternative that would satisfy the proponents.

I should remind everyone that as it currently stands, the page says: "...purely two-dimensional crystals were unknown before and even presumed not to exist". I would think "...purely two-dimensional crystals were unknown before" would be sufficient. (Some would even argue with that...)

Idosp2 (talk) 02:34, 31 January 2010 (UTC)

The more original a discovery, the more obvious it seems afterwards. - Arthur Koestler (British-Hungarian Writer). I come across with this today on Quotes of Day in Goggle.

—Preceding unsigned comment added by 118.97.67.227 (talk) 12:12, 31 January 2010 (UTC)

Can I then conclude that the more obvious a discovery, the more original it seems afterwards? —Preceding unsigned comment added by 70.17.91.17 (talk) 13:59, 31 January 2010 (UTC)

Spot on! Think of the fractional quantum Hall effect then. Wasn't it obvious to try higher quality samples in increasingly stronger magnetic fields? Urianway (talk) 20:25, 31 January 2010 (UTC)

P.S. Klaus, please go ahead with a moderated version. Please incorporate new info in the discussion, if possible. Hopefully, you do not like "pretenders" ;-) Urianway (talk) 21:26, 31 January 2010 (UTC)

Don’t forget --- even Geim has finally accepted that Walt de Heer pioneered graphene research!

See his letter http://www.aps.org/publications/apsnews/201001/letters.cfm

Gasupporter (talk) 18:32, 4 February 2010 (UTC)

I was skiing and, also, doing some extra reading. A couple of comments about the new version. Because of the arguments above, I left “presumed not to exist” as a quotation. In my opinion, this was not the mistake that "slipped through". Rather, this statement referred to the specific phenomena, as discussed above and added in the text. The new version gives a narrower interpretation to the "exist" statement and, hopefully, will satisfy both sides of the argument.

I have also given a lot of credit to the previous efforts but, at the same time, I tried to emphasize their limited impact and explain why the 2004 paper was special. More references could be added to the earlier but I feel that the article has too many references already. More importantly, I do not want to support those who had little success previously but now demand to be considered visionaries. So I added no new references. Shoot me but I tried my best to fulfill this "public duty" as fair as possible. KlausMn (talk) 19:52, 6 February 2010 (UTC)

I am happy with the new version. The new version retains the "presumed not to exist" language (with the caveat "often") but explains its fairly narrow basis. I was not actually advocating for a thorough coverage of the previous attempts to make graphene, though including them allows the reader to draw his own conclusion about whether graphene was universally presumed not to exist.

Idosp2 (talk) 19:23, 16 February 2010 (UTC)

I am likely to be too late for this nice and long argument. However, maybe some of you will be interested that graphene was and is {in some vague sense} "presumed not to exist" by many theorists {molecular dynamics community}. MD simulations show that it is unstable relatively to rolling into cylinders. All these papers are strictly correct because graphene is indeed metastable in the flat configuration if its size is larger than ~10 nm. This' the opposite limit to the instability when it reconfigures for small sizes. No contradiction with Geim's work because his graphene has to be metastable and has a large barrier relatively to become rolled up. There are many papers. For instance, 1) D Tomanek Physica B 323 86 (2002) 2) R Setton Carbon 34 69 (1996) 3) J Lavin, S Subramoney, R Ruoff, S Berber, D Tomanek Carbon 40 1123 (2002)

I strongly recommend to read S Braga and others Nano Letters 4 881 (2004). (Moledynamo (talk) 21:39, 6 March 2010 (UTC))

This instability of the flat sheet is very important. Why did no one amend the main article?! I waited and waited. Urianway (talk) 21:04, 6 May 2010 (UTC)

It is interesting to note

It is interesting to note (see Talk:Graphene) that there were a number of previous attempts ...

I removed the above self reference (in bold) as I believe it is outside Wikipedia's usual style. -84user (talk) 16:09, 5 October 2010 (UTC)

Kingsford Charcoal?

Um, Kingsford Charcoal? This is a joke I think? Or not? —Preceding unsigned comment added by 64.132.226.5 (talk) 17:53, 5 October 2010 (UTC)

I think it's either spam/CoI editing, or somebody who thinks only the Kingsford brand of charcoal briquets contains graphene. Either explanation is silly at best, so I say it's a good thing that 99.233.73.144 edited out the brand name. But the Charcoal article doesn't even mention graphite, let alone graphene, so I'm not convinced that it's meaningful to talk about charcoal at all. Thoughts? (Btw, the Kingsford page here seems almost entirely copied verbatim from the company's home page, so the odor of advertising is pretty strong around Charcoal.) 70.89.112.185 (talk) 18:18, 5 October 2010 (UTC)

Problems with the article

It seems to me that there are technical problems with this article. Trying to get a PDF copy ("Download as PDF") the resulting PDF file starts wit the following message: WARNING: Article could not be rendered 84.206.43.2 (talk) 07:29, 6 October 2010 (UTC)

Needs a complete re-write for non-physicists

It's lovely that all you physicists have had fun putting together this page and discussing its intricacies. For the non-physicist, however, it makes no sense whatsoever, from start to finish. This page is about to get a lot of hits - the 2010 Nobel Prize in Physics was announced ten minutes ago - and no one who isn't a physicist is going to understand a single word. That's a shame. This page could explain why graphene is important enough to merit a Nobel Prize, and it probably does, but only to people who probably know it all already. 94.7.74.242 (talk) 09:56, 5 October 2010 (UTC)

It's chemistry, not physics :-D. And also, since when did we explain things in "laymans terms"? As I understand it, technical knowledge is part and parcel with encylopaedias... look at Mass-energy equivalence or Lead(II) nitrate. The latter probably makes no sense to a non-chemist, and yet it is a featured article. The former makes no sense to me, or non-undergraduate physicists... it's gobbledegook as far I'm concerned. However, that does not nullify its encyclopaedic value, nor its ability to convey ideas. They're just not ideas that I understand. I agree somewhat to your point about explaining the usefulness of graphine however I would purport that the usefulness is inherent within the article itself. I would also say that while the article is written with technical vocabulary, the concepts themselves are fairly simple ones, and indeed GCSE and A-Level students should in theory be able to grasp most of the article. Anikin3 _Help!!! ^Messages? 14:53, 5 October 2010 (UTC)

I agree. Most of the terms makes no sense to readers than the field of chemistry, which reduces the usefulness of the article. —Preceding unsigned comment added by 200.189.118.10 (talk) 16:55, 5 October 2010 (UTC)

There is an easy solution that is hopefully agreeable to both parties which would be to have the introduction and the first half of the description be mostly in laymen's terms. These two parts should really serve the purpose of being a 30 second explanation of "What is it" from a laymen's perspective. There can also be technical terms, for example calling a kangaroo a marsupial in the first sentience is appropriate. Most people don't know what a marsupial is, but can click through and read the first sentience which is probably all they need to know to go back and continue reading the kangaroo. Or they can disregard it as a technical term and keep reading without losing much understanding. The goal of adding technical terms is to add more value for further reading and also help make sure that the "What is it" question is answer for chemists as well as laymen's. They just shouldn't be so overwhelming that a laymen can't understand the intro. I do NOT agree that the whole article should be in laymen's terms, as the laymen should be able to read the first couple of paragraphs and get all that he is going to understand about the subject and then can stop reading. Anythingapplied (talk) 18:44, 5 October 2010 (UTC)

I would also suggest someone change the STRUCTURE of the article. It consists of many, many very short pieces. It is difficult to read it as a whole. Zould some one please have a look? Thanks! 213.47.144.254 (talk) 07:11, 6 October 2010 (UTC)

Ok, how's this for a reword of the introduction?

Graphene is a one-atom-thick sheet of carbon atoms that are densely packed in a honeycomb pattern. It is most easily visualized as an atomic-scale chicken wire made of carbon atoms and their bonds. The name comes from graphite + -ene; graphite itself is made of many graphene sheets stacked together.

The bond length between carbon atoms in graphene is about 0.142 nm. It makes up several different allotropes of carbon including graphite, charcoal, carbon nanotubes and fullerenes. It can also be considered as an infinitely large, exeptionally stable molecule, the largest version of the family of flat polycyclic aromatic hydrocarbons called graphenes. The Nobel Prize in Physics for 2010 was awarded to Russian-born Andre Geim and Konstantin Novoselov "for groundbreaking experiments regarding the two-dimensional material graphene".Anikin3 _Help!!! ^Messages? 14:55, 6 October 2010 (UTC)

Showing the Conjugated Structure

While the second paragraph refers to the atomic structure as being “an infinitely large aromatic molecule”, the illustration shows all the bonds to be single bonds. One can imagine the illustration with all the bonds running away from the viewer as being double bonds. Imagine all the diagonal bonds, both angled to the left and to the right, as being single bonds. This allows all the atoms to have the usual tetrahedral bonding. The conjugated structure also allows the plane to be electrically conductive, with the bonds shifting back and forth between double and single as needed to carry the electrons. It might be easier for the reader to imagine the structure as a vast version of benzene. The illustration was done using Accelrys Materials Studio, if anyone would like to redo it. My Flatley (talk) 21:05, 6 October 2010 (UTC)

2D

If it's 1 atom thick, then how can it be 2 dimensional matter? 75.150.245.242 (talk) 20:21, 6 October 2010 (UTC)

As it's not possible to have a material thinner than one atom thick. Thus, it's as close to 2-dimentional as we're going to get. Theoretically, a planar hydrogen sheet, similar to graphene, would be the thinnest material, however to my knowledge such a thing is a physical impossibility. Anikin3 _Help!!! ^Messages? 14:43, 8 October 2010 (UTC)

Non- physicists

i am not a physicists. to be fair i am a long way away, i study physics at AS level but i can understand most of this and i dont want people coming on here saying that they want to change it cause it makes no sense, if you just read through and dont just skim through it, it makes a lot of sense and is easy to understand so dont bother changing it, cause this is a very informative page and i have found this very interesting. —Preceding unsigned comment added by 89.241.5.99 (talk) 20:01, 13 October 2010 (UTC)

What about armor?

I heard this thing is extremely hard to penetrate, so I was wondering if we put few sheets of these into the Tank armor, or make helms, cloaks etc, to protect army. Who knows! may be russians are already doing this. —Preceding unsigned comment added by 221.222.13.118 (talk) 14:42, 3 November 2010 (UTC)

actually three dimensional lattice? really?

"Note that the dimensionality in this article is generally shorthand for "a single atom" or "flat"; for example, a "two-dimensional" graphene lattice technically does have a slight thickness and is therefore actually a very thin three-dimensional lattice."

Really? I mean, sure, a sheet of graphene is not a geometric plane with no thickness. It's one atom thick. But it's actually a three dimensional lattice? That's simply false. To be a three dimensional lattice, it has to repeat in three independent directions. This lattice is definitely 2 dimensional.

Since this dubious claim is not sourced, I'm removing it.

If I'm incorrect, and someone wants to argue that it is actually a 3d lattice, please revert me.

Oh, also? hexagonal lattice is not a lattice by mathematical def? That can't be right. Also removing. -lethe ^{talk +} 16:20, 11 December 2010 (UTC)

Since Lattice (mathematics) has its own dab page... Rich Farmbrough, 22:39, 23 December 2010 (UTC).

optoelectronic devices

Jan 10th research paper worthwhile?

http://www.sciencedaily.com/releases/2011/01/110110103735.htm Light Can Control Electrical Properties of Graphene

Hcobb (talk) 05:44, 13 January 2011 (UTC)

When did the term grapheme first appear?

The article contains these two seemingly contradictory statements:

"The term graphene was coined as a combination of graphite and the suffix -ene by Hanns-Peter Boehm,[1][2] who described single-layer carbon foils in 1962."

"The term graphene first appeared in 1987."

Which (if either) is correct?

tripbeetle talk, 07:26, 13 January 2011 (UTC)

Casimir effect

Graphene shares its electrical conductivity and electron cloud with metals, so it probably shares the Casimir effect as well. It is even inpenetrable to atoms. —Preceding unsigned comment added by 95.209.88.105 (talk) 20:17, 16 January 2011 (UTC)

Optical illusion

Has anyone noticed that there is an optical illusion. When reading the intro, the image on the right appears to go downwards. Weird. —Preceding unsigned comment added by 90.36.232.20 (talk) 10:40, 10 February 2011 (UTC)

Casimir effect section wrong and irrelevant

The section entitled "Casimir effect" is wrong and not very relevant. One does not need thin sheets to have a Casimir effect (which is nothing but the generalisation of the van der Waals force) -- there is a Casimir effect between all things that scatter light, although it's normally too small to be interesting (see Wiki article on Casimir effect). Naturally there is a Casimir force between sheets of graphene, nanotubes, etc., but you could say the same about bags of pears or radio talk show hosts. The only difference is that, since they are microscopic, in graphene systems it may be interesting to know how big the Casimir force is, so people have made calculations. That could be an appropriate subsection in the article on the Casimir effect, but hardly in that on graphene. Suggest to remove the whole sub-section.

129.241.62.166 (talk) 09:08, 23 February 2011 (UTC)

• [7] c.f. e.g. Bordag et al., Phys. Rev. B 80, 245406 (2009).

References

thanks for the picture

Dear Wikipedia, Thank you so much for the Creative Commons license on the graphene picture! We were able to use it on the Triple Helix blog: http://triplehelixblog.com/2011/05/paving-the-way-for-moores-law/ —Preceding unsigned comment added by 128.135.100.102 (talk) 01:51, 9 May 2011 (UTC)

Bilayer graphene?

I'm tempted to add a section about Bilayer graphene (including applications), but I'm quite new to wikipedia and I'm wondering if it should instead be its own article, like carbon nanotubes or GNRs. Thoughts? Zak.estrada (talk) 16:35, 1 July 2011 (UTC)

It is already mentioned at this article a couple times, but I would there is plenty of sourcing to support a separate article on the arrangement. I would say add a new subsection under Properties briefly explaining why it is an exciting arrangement instead of just a step towards becoming graphite. Add {{main|Bilayer graphene}} at the start of the section and write the full treatment at the dedicated article. Just my 2¢, really - there is pretty much nothing you can do that cannot be fixed quickly and easily, so be bold. - 2/0 (cont.) 02:45, 2 July 2011 (UTC)

Health effects

I am surprised to see no mention of concerns regarding the possible health effects of exposure to graphene. Can anyone add a section on this?Jimjamjak (talk) 09:40, 7 October 2011 (UTC)

Actually there currently none for graphene and carbon nanotube other than the normal health risks of dust. Afterall carbon nanotubes are in as well as buckyballs. However, the main reason there are none is unlike gold colliod nanochains or silver nanoparticle neither graphene does have any major biochemical or medicinal uses. In fact scifi has really jumped shark, so to speak by the recent games and books that have come out with medical technology is going to be nanotechnologies primary contribution to even first big contribution to society. In reality, graphene is actually going to first help revolutionize chemical, smoke, light based detectors through FETs like Georgia Tech's Dr. Tech James Gole developed, which is the same FET discovery mentioned on this wiki page. Ironically Dr. Gole's inspiration was to develop a better asmatha attack detector that could warn users at least an hour before an attack occurs.Physics16 (talk) 22:44, 27 October 2011 (UTC)

I believe this should be fixed

After the definitions, in the 'Definition' paragraph: "The IUPAC compendium of technology states: "previously, descriptions such as graphite layers, carbon layers, or carbon sheets have been used for the term graphene... it is correct to use for a single layer a term which includes the term graphite" It should be INcorrect. The whole point of the sentence is that Graphite is 3D, and Graphene 2D.

— Preceding unsigned comment added by 71.160.51.209 (talk) 20:46, 16 November 2011 (UTC)

GA Review

The following discussion is closed. Please do not modify it. Subsequent comments should be made on the appropriate discussion page. No further edits should be made to this discussion.

---

This review is transcluded from Talk:Graphene/GA1. The edit link for this section can be used to add comments to the review.

Reviewer: Jezhotwells (talk · contribs) 18:17, 3 December 2011 (UTC)

I shall be reviewing this article against the Good Article criteria, following its nomination for Good Article status.

Disambiguations: none found.

Linkrot: ten found, six repaired and four tagged.[8] Jezhotwells (talk) 18:34, 3 December 2011 (UTC)

Checking against GA criteria

GA review (see here for what the criteria are, and here for what they are not)

1. It is reasonably well written.

   a (prose): b (MoS for lead, layout, word choice, fiction, and lists):

   One definition given in a recent review on graphene is: recent is a vague word, be more specific, attribute the athour and date.

   Likewise with A previous definition is:

   The earliest TEM images needs explanation

2. It is factually accurate and verifiable.

   a (references): b (citations to reliable sources): c (OR):

   The IUPAC compendium of technology states: "previously, descriptions such as graphite layers, carbon layers, or carbon sheets have been used for the term graphene... it is incorrect to use for a single layer a term which includes the term graphite, which would imply a three-dimensional structure. The term graphene should be used only when the reactions, structural relations or other properties of individual layers are discussed." Citations needed for all quotes

3. It is broad in its coverage.

   a (major aspects): b (focused):

4. It follows the neutral point of view policy.

   Fair representation without bias:

5. It is stable.

   No edit wars, etc.:

6. It is illustrated by images, where possible and appropriate.

   a (images are tagged and non-free images have fair use rationales): b (appropriate use with suitable captions):

7. Overall:

   Pass/Fail:

   After a complete read through, I concur with the addition of the "too technical" template, which was added last month. There are a number of uncited statements, some tagged from September 2010. The organization is poor and a number of dead links. The article has potential, but is not near GA standard at present. The nomination is by an IP with no other contribution history - I judge this as C class at best. Quickfail. Jezhotwells (talk) 18:55, 3 December 2011 (UTC)

The discussion above is closed. Please do not modify it. Subsequent comments should be made on the appropriate discussion page. No further edits should be made to this discussion.

Reversing bad edits

I have undone all edits by 108.215.23.165 and Jmyers2011. I recommend that someone take a closer look at 98.228.176.118 as well. — Preceding unsigned comment added by Ruinia (talk • contribs) 01:34, 12 December 2011 (UTC)

Graphene quantum dots - for consideration

For consideration for inclusion -- http://www.media.rice.edu/media/NewsBot.asp?MODE=VIEW&ID=16612&SnID=1949071651 and http://pubs.acs.org/doi/abs/10.1021/nl2038979 --User:Ceyockey (talk to me) 15:39, 16 January 2012 (UTC)

SI Units Pleeaaassseeee

Can this article be edited so as to represent all quantities in SI units ? This will make the quantitative data more useable by a wider readership. Most scientists and engineers use SI units nowadays (and have done so for many decades).

I would also like to comment on the inappropriate metaphor 'honey comb'. A honey-comb is a 3 dimensional structure, while the graphene structure is 2-dimensional. This makes the metaphore misleading. The use of a metaphor is anyway unnecessary since a straight-forwardly factual description is readily available; simply describe the structure as a planar array of interlocking hexagons (benzene rings).

Andrew Smith — Preceding unsigned comment added by 82.32.48.177 (talk) 09:03, 28 January 2012 (UTC)

• Chicken wire? V8rik (talk) 23:13, 28 January 2012 (UTC)

Graphyne not Graphene

Graphyne redirects to Graphene, but they are not the same thing, though both are allotropes of carbon. A knowledgeable author should be urged to produce a treatment of the former. 98.218.227.35 (talk) 18:17, 5 March 2012 (UTC)

New method of graphene production

Could someone properly add it to the description page? http://arstechnica.com/science/news/2012/03/a-supercapacitor-in-your-optical-drive-dvd-rw-used-to-burn-graphene-capacitors.ars http://www.sciencemag.org/content/335/6074/1326

— Preceding unsigned comment added by 170.66.1.235 (talk) 18:30, 16 March 2012 (UTC)

References

Two possible errors

In the section Description, I found a possible wrong citation [7] ─C. D. Simpson et al. "Synthesis of a Giant 222 Carbon Graphite Sheet" Chemistry - A European Journal, 61424 (2002)]─, which in turn, in the Abstract, contains an error about that giant 222 aromatic polycyclic hydrocarbon. In the Spanish Wikipedia, I already did both changes, besides an explanation.--Francisco Valdez Mendoza (talk) 02:35, 6 September 2012 (UTC)

Infobox

How it this infobox? Danielj2705 (talk) 20:18, 13 December 2012 (UTC)

Graphene
General
Category	Mineral
Formula (repeating unit)	C
Strunz classification	1/B.02-10
Crystal system	Hexagonal
Space group	Hexagonal
Unit cell	one lattice point and a two atom basis.
Identification
Formula mass	Carbon
Color	Iron black to steel grey
Twinning	{1121}
Cleavage	Perfect {0001}
Fracture	Micaceous
Tenacity	Flexible
Mohs scale hardness	>10
Luster	Sub-metallic
Streak	Black to steel grey
Diaphaneity	Opaque
Density	2.09–2.23 g/cm3
References

References

External link

I wondered whether a link to the Graphene collection on IOPscience (IOP Publishing) - http://iopscience.iop.org/page/graphene could be added? This webpage has lots of free to read articles which may be helpful for Wikiepedia users wishing to find out more about graphene. Physics114 (talk) 09:27, 12 December 2012 (UTC)

• Added! It was a very interesting website with lots of good articles Danielj2705 (talk) 20:21, 13 December 2012 (UTC)

I can't understand this

I'm looking at this in school and this is incomprehensible for me. Please help! — Preceding unsigned comment added by 2.98.232.137 (talk) 20:28, 28 January 2013 (UTC)

Does simple:Graphene help? Neo Poz (talk) 03:10, 24 February 2013 (UTC)

Article's complexity

This is a complex article but nevertheless very clear and well-written with many references and links. I don't think it is "too complex" at all and offer my thanks to the editors who made this admittedly difficult subject mater understandable and an excellent springboard for further reading and for gaining valuable insight into some of what is happening with graphene research and development. So, please don't dumb down this article. Calicocat (talk) 15:47, 15 March 2013 (UTC)

don't touch my stuff!

I truly disagree with Materialscientist's idea of a good encyclopedic introduction. Like it says in big letters at the beginning...This article may be too technical for most readers to understand. Please help improve this article to make it understandable to non-experts, without removing the technical details. This should tell the writer that this article will scare most learners away, but if Materialscientist can delete any effort to simplify this article because in hi/her expert eyes the intro is already simple (see view history: "too much useful and easy to understand information was removed") what's the use? This is no joke, right? You actually believe that what you put back in was needed in an introduction, and was "easy to understand"? If so, you are truly out of touch.

Materialscientist knows materials, but he/she missed out on an ability to communicate with people outside his/her narrow specialty. Hasn't anyone with your education ever talked to you about how good writing must be aimed at a particular audience? Your audience in an encyclopedia should be learners, but this article's only possible audience is other materials scientists. If you think what I deleted needs to be in the article, so be it, but certainly not in the intro.

If everyone who looked up graphene knew enough background to understand this article, there would be no need for the article. Don't get me wrong, what is there should stay there, it's good for completeness. But this article is a perfect example of how not to introduce a technical subject.

When I first saw this I wondered how an article that is so ungainly had survived as long as it has. I think Materialscientist has answered my question. Is there anyone with any authority listening out there? Pb8bije6a7b6a3w (talk) 23:30, 2 May 2013 (UTC)

Whew. At first I thought you were talking about my changes. I agree that the article is overwhelming in its current state. I have no more authority than anyone else, but support dramatically simplifying things. This should probably be split into multiple articles. Given the hypothetical nature of most of the apps stuff, that seems like a good candidate. In the sections I hit, I removed the text that identifies the researchers. This article is not here to burnish reputations. Lfstevens (talk) 00:14, 3 May 2013 (UTC)

Ahh, the voice of reason! Thanks, LFstevens! How frustrating! I feel like I've been dealing with that out of touch particle physicist on the show The Big Bang Theory. Did you look at the change I suggested? Do you think it's a turn in the right, or wrong direction?

One small disagreement with you, I DO think that what's in the article should stay. In fact I think that what is there may be the PERFECT body to an article on graphene - but let's not scare off all of those potential material scientist children out there with an article that makes them draw a blank right off the bat. I'm curious about your remark about splitting the subject up. What did you have in mind? But my real question is, can Materialscientist balk any attempt to change things? Is there no recourse? Pb8bije6a7b6a3w (talk) 00:35, 3 May 2013 (UTC)

SIMPLIFY THE INTRO!

Good article nomination? You must be kidding! Don't get me wrong, there is a lot of good in the current article, I don't think anything should be taken away, but the technical place it starts on will scare most readers away. This should definitely not be held up as an example of a good ecyclopedia article. If anything, it's a great example of why many wiki technical articles are really bad. Pb8bije6a7b6a3w (talk) 22:05, 2 May 2013 (UTC)

I've made some minor changes to the layout of the beginning of the article, and also reworded the first paragraph a little to try to make it easier to understand. Some of the introduction section contained complex descriptions of the structure of graphene, which I moved to the description section. Hopefully this will make it easier to swallow. TehBen1 — Preceding unsigned comment added by Tehben1 (talk • contribs) 04:30, 4 May 2013 (UTC)

Graphene#Solar_cells

Mention this at Graphene#Solar_cells Appearantly, it's possible to make the solar panels compeletely from graphene (carbon) instead of silicium making them very cheap. KVDP (talk) 17:25, 5 June 2013 (UTC)

Applying graffite to sudstraight

PROCESS GRAPHITE TO FINEST DUST. Build a box with tight lid, a hole in unit to blow dust inside. with a small air pump attached the box add a small amount dust with substraight in place turn on time to be calculated. After the alotted time reverse air clean dust.Remove substraight. check repeat — Preceding unsigned comment added by 69.21.106.140 (talk) 05:32, 11 June 2013 (UTC)

Manufacturers and suppliers

According to http://www.marketoracle.co.uk/Article35259.html,

China controls roughly 70% of the market, much as it dominates more than 95% of the world's "rare earths" market, and Beijing is both limiting exports and charging a 20% export duty on graphene. That's one reason its price has more than tripled in the past five years.

It would be nice if the article provided information that would allow readers to ascertain whether there is any truth to this claim. 199.46.245.232 (talk) 00:27, 6 July 2013 (UTC)

Time to split?

This thing is getting to be too big, lately crossing the dreaded 10k line. It's time to rethink how to communicate this information. I'd like to see a less-technical article that is under 5k, with links to subarticles that contain more info. As part of the problem (I've added lots of minutiae) I'd like to contribute. Here's a possible outline (revisions encouraged!):

Characteristics

Structure

Properties

Forms (summary with links to Graphene forms

Pseudo-relativistic theory

Applications (summary that emphasizes actual and links to Graphene applications)

Potential applications (a simple list to demonstrate the breadth that is out there)

Production methods (summary with link to Graphene production, as many more such methods are to be expected)

History

See also

Refs

Links

Thanks for your attention! Lfstevens (talk) 17:43, 24 August 2013 (UTC)

Cite doi/pmid

Anybody care if I replace the cumbersome full refs with the bot-aided/site consistent cite templates? Thanks. Lfstevens (talk) 00:11, 2 December 2013 (UTC)

White light transmittance figure

While probably this photo showing a round area sectored into 0-, 1-, and 2-atom thick regions is likely to have been important and convincing in the original report, I find it confusing here. Perhaps the accompanying description needs changing? What exactly am I to look for in the three sectors to convince me that graphene is remarkably absorptive of white light? — Preceding unsigned comment added by 74.192.47.171 (talk) 17:38, 21 December 2013 (UTC)

Translation

I believe this topic would be of considerable interest to those in the English-speaking world. Are there any plans to translate it into English?

I am not sure who posted this, but this article is in fact in english. Actually graphene is orginally an English/Germanic word. In fact, the majority references in this article are from universities, journalists, or businessmen in English-language countries such as the United States and England. As for other languages, I am not 100% sure how good the translation to other languages is. Please let me know the first few specific terms that you feel are "Non-english" or "not grammatically" correct. I and others would be happy to clarify the meaning of any words in this article. So, which words or phrases do you have a problem with? Physics16 (talk) 23:13, 2 March 2014 (UTC)

Can I help make this article more understandable?

So, for a long time, I have noticed that there have been many unanswered questions in the graphene talk page, it has become more and more cluttered. Being a student who graduated under Walt DeHeer and Howey Physics, I could answer some of these talk questions; however, I am worried because every time, I post I seem to get referencing and how to cite reliable sources wrong. All the editing wars and warning messages scared be off back in 2011) Recently, I felt like I cannot sit idley by while seeing the lost names of important people and "outdated information" label (Dec 2013). So if you guys are willing to be patient help me, I would be happy to help make this article less technical and easier to read. (I actually have written broad series of objectives based on what you guys have said in past talks that I was going to share with you guys.) Physics16 (talk) 21:19, 23 February 2014 (UTC)

I have asked for the help of people who design tagging template against the continued drive-by tagging. Hopefully they can help us consolidate some of the problems people are having with this article and get people to explain what they feel is too technical. Physics16 (talk) 00:11, 3 March 2014 (UTC)

What do you guys think? Physics16 (talk) 22:35, 2 March 2014 (UTC)

Applications

The potential apps section is getting very long. I've collected a bunch of articles about new apps for graphene that will make it even longer. Should we break apps, especially potential apps, into a separate article with highlights here? This article would likely become much more stable. I haven't made that change, yet. Lfstevens (talk) 07:20, 2 April 2014 (UTC)queestions

Lfstevens, I saw your post (and I would have seen it sooner if it was not for CluebotIII ... sigh) . As thought I mentioned earlier, I am fully ok with your proposal, and I am very grateful for your hardwork. If you willing to make some more changes, I did have a following comments about the changes you have made so far: --Physics16 (talk) 02:15, 16 April 2014 (UTC)

1. I know the Scientific American article, "Carbon Wonderland", is very vague about the $1,000 and $100,000,000/cm^2 cost comes from, but its actually the cost of Scotch tape exfoliation first done by Geim and Novosolev. This cost calculation was originally done as a way to challenge Geim and Novosolev's work because their Nobel Prize was actually more controversial than people realize. Thanks to research into improvements, the other exfoliation production methods, especially graphene oxide, are orders of magnitude cheaper than $1,000 range be closer to the $100/cm^2 level of epitaxial graphene. If don't mind, you could either edit Adhesive tape or beginning of applications, to reflect that the $1,000 cost just applies to the adhesive tape production method. Physics16 (talk) 02:15, 16 April 2014 (UTC)

Happy to cover the new techniques if you can provide a secondary source. The big secondaries used so far are 5 years old. Lfstevens (talk) 03:37, 16 April 2014 (UTC)

1. In Graphene_(potential_applications), there a "citation needed" in the transistors section. Looking way back in 2004, the paper that line comes from is actually the original 2004 article by Geim and is listed as Graphene#cite_note-Nov_04-30 in original graphene article. Physics16 (talk) 02:15, 16 April 2014 (UTC)

I'll work on it. Lfstevens (talk) 03:37, 16 April 2014 (UTC)

1. I am not sure if this 100% necessary to mention, but the current method of exfoliation from graphene oxide is done with a massively powerful CO2 laser, while back in the 1960s I believe they use used shavings produced by a carbon arc wielder. Also back then it was graphite oxide, while today its graphene oxide. Physics16 (talk) 02:15, 16 April 2014 (UTC)

Again need a secondary.

1. When you moved applications from Graphene to Graphene_(potential_applications), you accidentally orphaned the picture in Graphene applications found here. Not a lot of people realize the picture is actually a picture based or rather of Pseudo-relativistic theory. So the picture needs to also be in Pseudo-relativistic theory section. Pseudo-relativistic theory was designed to help explain why those little X or double V shaped wedges in the orbital structure of graphene even exist. It is actually the center of the X or the singularity that electrons pass through when graphene conducts. The center's singularity like nature is why graphene is so conductive. Now I would have moved that picture myself back in 2010; however, the original creator of the picture posted with in Biodevice section. I was never really sure what they thought Psuedo-relativistic theory had to do with Biodevices, but I didn't want to challenge them because I knew nothing about the bio-device applications of graphene. Does this make sense? Physics16 (talk) 02:15, 16 April 2014 (UTC)

Seems ok to shift. Lfstevens (talk) 03:37, 16 April 2014 (UTC)

Translation

I believe this topic would be of considerable interest to those in the English-speaking world. Are there any plans to translate it into English?

I am not sure who posted this, but this article is in fact in english. Actually graphene is orginally an English/Germanic word. In fact, the majority references in this article are from universities, journalists, or businessmen in English-language countries such as the United States and England. As for other languages, I am not 100% sure how good the translation to other languages is. Please let me know the first few specific terms that you feel are "Non-english" or "not grammatically" correct. I and others would be happy to clarify the meaning of any words in this article. So, which words or phrases do you have a problem with? Physics16 (talk) 23:13, 2 March 2014 (UTC)

Hi Physics. I think the proposal was a joke about the poor prose. Lfstevens (talk) 00:35, 17 April 2014 (UTC)

Can I help make this article more understandable?

So, for a long time, I have noticed that there have been many unanswered questions in the graphene talk page, it has become more and more cluttered. Being a student who graduated under Walt DeHeer and Howey Physics, I could answer some of these talk questions; however, I am worried because every time, I post I seem to get referencing and how to cite reliable sources wrong. All the editing wars and warning messages scared be off back in 2011) Recently, I felt like I cannot sit idley by while seeing the lost names of important people and "outdated information" label (Dec 2013). So if you guys are willing to be patient help me, I would be happy to help make this article less technical and easier to read. (I actually have written broad series of objectives based on what you guys have said in past talks that I was going to share with you guys.) Physics16 (talk) 21:19, 23 February 2014 (UTC)

I have asked for the help of people who design tagging template against the continued drive-by tagging. Hopefully they can help us consolidate some of the problems people are having with this article and get people to explain what they feel is too technical. Physics16 (talk) 00:11, 3 March 2014 (UTC)

What do you guys think? Physics16 (talk) 22:35, 2 March 2014 (UTC)

Your help is most welcome. Lfstevens (talk) 03:39, 16 April 2014 (UTC)

I like to make complicated things understandable, and have sometimes done that sort of thing professionally. I especially like to work on leads, and I'll start there. Leadwind (talk) 23:53, 22 April 2014 (UTC)

Welcome aboard! Lfstevens (talk) 02:47, 23 April 2014 (UTC)

Regarding the close paraphrasing of Electronic section

So, on March 2, 2014 Josedr87 pointed out that part of Electronics section look like its directly quoting the article reference. Now Joseder87 did forget to post in the talk page before adding a major "Warning/Review" tag, so I am going to give him precautionary words about forgetting to do so. However, I will give Josedr87 a pat on the back because I feel that he not only points of a instance where the paraphrasing is to close, but also an instance where the non-wikipedia article actually paraphrased and mistakenly "plagiarized" Wikipedia instead of the normal other way around. A close cross-examination of the Duplication Detector and the history of the graphene article (between Feb 5 and Feb 27) reveals that only the phrases between "approximately 40 nanometers wide..." and "graphene changes in discrete steps" are direct duplications and close paraphrasing. From my initially examination, the rest of the detected duplication are words added to wikipedia BEFORE the article existed!

In simple terms, author actually quoted wikipedia/graphene in his “non-free copyrighted” article and forgot to tell anyone. We should be proud that nanotechnology experts and academics are quoting wikipedia to explain things. After all imitation of the highest level of flattery. It really shows how far we have gone in making this article notable and easier to read.

Now, there are still those phrases that Josedr87 pointed out where the article is too closely following the article it references. So I would like some help looking over duplicated sections and perhaps paraphrasing some of them or even highlighting worst offenders. Perhaps Josedr87 and other people working on the article could comment below? Physics16 (talk) 22:37, 2 March 2014 (UTC)

@Josedr87:, if are still willing can help looking over the listed duplicated sections and perhaps highlight what you feel are the worst offenders of "close paraphrasing? Physics16 (talk) 21:26, 1 April 2014 (UTC)

I'm attempting a rewrite of the section, so feel free to wait until that's complete. It may fix the problem. Lfstevens (talk) 00:01, 16 April 2014 (UTC)

My rewrite is complete, so I removed the tag. Lfstevens (talk) 02:48, 23 April 2014 (UTC)

Nonsensical property

Graphene-based membranes are impermeable to all gases and liquids (vacuum-tight). However, water evaporates through them as quickly as if the membrane was not present So how is the water passing through the membrane, if not as a gas or liquid? Qemist (talk) 05:35, 20 April 2014 (UTC)

Finally get around to answering this. Short ELI5 Answer: Water passes through thanks to serendipitous discovered capillaries (very small holes) that are made from in single-layer graphene or stacked graphene of (or rather from) graphene oxide. You can read about in graphene oxide's water filter applications Long Answer: Honestly, I sympathize with you that the idea of something impermeable allowing water (liquid or gas) to flow throw is bizarre nonsense. However, let me tell you a story... Back in 2012, I think the Dr. Nair and Dr. Giem accidentally got an error while reconfirming graphene's unique lack of Permeability that paralleled some of its magnetic. Before this we had thought that pure graphene only had to be intentionally doped into Field Effect Transistors (FET) to be a porous medium or have permeation of gases. In fact, it was turned specialized (in porority) graphene FET called porous GNRFET, which operated like ppb-version ChemFET (ChemFET's detect in units of ppm). To summarize, Graphene was hydrophobic and pretty much anything-phobic, resisting all gases that tried to pass through. So, when Dr. Giem and Nair accidentally discovered that water vapor coming out of a graphene batch, it blew their minds. It would take them two years to realize their graphene had formed tiny capillaries into what they would call a graphene membrane. They would realize that "Graphene is hydrophobic – it repels water – but narrow capillaries made from graphene vigorously suck in water allowing its rapid permeation, if the water layer is only one atom thick – that is, as thin as graphene itself. e-atom-wide graphene capillaries can now be made easily and cheaply by piling layers of graphene oxide – a derivative of graphene – on top of each other. The resulting multi-layer stacks (laminates) have a structure similar to nacre (mother of pearl), which makes them also mechanically strong." Back in 2012, these graphene "membranes made from such laminates were impermeable to all gases and vapors, except for water. This means that even helium, the hardest gas to block off, cannot pass through the membranes whereas water vapor went through with no resistance." Helium, if you didn't know, is in size at least 5 smaller than water vapor. Dr. Giem and Nair realized that Graphene while hydrophobic can (through graphene oxide) gain not this permeability but this permeability like cell walls. So of course, they then tested it on liquid water, which then worked. Now their research is focused on refining the capillaries so that no single element salt ions pass through so they can finally develop the worlds first truly simple non-electric mechanical pump that gives you fresh water from salt water. Hope this answers your question. So, the following sentence should read like this:

Graphene is normally hydrophobic and impermeable to all gases and liquids (vacuum-tight). However when formed into Graphene-oxide-based capillary membrane, both liquid water and water vapor flow through as quickly as if the membrane was not present

P.S. In case I forgot to message Lfstevens about this, Lfstevens, I in general agree with many of changes made in April and think they are awesome!! I will try to examine them in more detail sooner when I get a chance :) Thanks man!) Physics16 (talk) 23:26, 16 June 2014 (UTC)

Thanks for noticing. Cheers! Lfstevens (talk) 01:12, 19 June 2014 (UTC)

I found a typo as follows:

"graphene's longitudinal esistance shows maxima…"

so I am changing esistance to resistance. — Preceding unsigned comment added by Avid0g (talk • contribs) 23:19, 20 June 2014 (UTC)

Graphene - a low tech summary

Please note that I did this section in response to the request for a less scientific summary of the the excellent information already submitted on the Graphene page. I hope my summary is useful to those non-techies/semi-techies looking in? Other contributors will no doubt improve it. Gairderek (talk) 11:27, 24 July 2014 (UTC)

You did a huge amount of work! However, I don't think putting a mini-article inside the main article is the right strategy. Perhaps the lede could be somewhat expanded and we can look to find more straightforward language in the other sections. Happy to work in that direction. Lfstevens (talk) 04:48, 12 August 2014 (UTC)

I am OK with that strategy too Gairderek (talk) 12:38, 14 August 2014 (UTC)

I will move the applications stuff into the Potential applications of graphene article and redistribute the rest. I also started a new article, Single layer materials which might serve as a home for summary level info.Lfstevens (talk) 17:56, 21 August 2014 (UTC)

By the way I named this a "low tech summary" but was never sure the title was good enough. I am sure that can be improved too Gairderek (talk) 12:16, 22 August 2014 (UTC)

The whole article is incredibly promotional, e.g. work out of Manchester. Clean-up to get rid of opinions, e.g. "easy to manufacture". Stick to facts, retain objectivity, and simply an otherwise wordy, redundant sentenced, and effusive document. Also, various items are miscategorized, e.g. things under definitions are properties or about manufacturing. InTheZone (talk) 17:18, 3 November 2014 (UTC)InTheZone

Speculation

However, the market is set to rapidly grow to ~$100 billion -- this is a statement about the future, at the very least it needs to be given a spaeker or asserter. "Projected"" perhaps? 84.227.241.98 (talk) 20:29, 8 September 2014 (UTC)

Good observation. I've removed the speculative bits per WP:SPECULATION. —Waldhorn (talk) 20:41, 9 September 2014 (UTC)

Coincides with my observation about sticking to facts, and avoiding opinions, especially promotional ones. InTheZone (talk) 17:20, 3 November 2014 (UTC)InTheZone

Semimetal/Zero band gap semiconductor

In the Properties, Electronic section it is said that "Graphene is a semi-metal or zero-gap semiconductor" I think these definitions are mutually exclusive and that it is in fact a zero-gap semiconductor. Quogle (talk) 12:26, 14 October 2014 (UTC) I believe that by definition semimetals have to have an overlap between the conduction and valence bands which graphene does not have and that the term zero gap semiconductor is most correct Quogle (talk) 10:29, 15 October 2014 (UTC)

Hashtag university of manchester — Preceding unsigned comment added by 130.88.99.225 (talk) 10:26, 4 November 2014 (UTC)

Tetravalency?

Doesn't carbon have a valency of four? The chicken-wire structure shows three equal bonds per atom. Where is the fourth? 101.161.64.172 (talk) 12:07, 1 December 2014 (UTC)

In graphene you have sp hybridisation giving you a pi bond along with the expected in-plane sigma bonds. Valency isn't always as simple as a single number!

Ezrado (talk) 23:17, 1 December 2014 (UTC)

Penta-graphene discovered. Any place I can stick this?

penta-graphene discovered. Any place I can stick this in this article?Septagram (talk) 18:33, 5 February 2015 (UTC)

• Done: Penta-graphene V8rik (talk) 19:56, 5 February 2015 (UTC)

Is the specific surface area correct?

If I calculate it with pen and paper, I get half the value -- which would be in line with http://www.graphenea.com/pages/graphene-properties — Preceding unsigned comment added by 129.187.179.90 (talk) 10:30, 26 March 2015 (UTC)

10 or 10 million

Would someone please check my edit which corrected the syntax of {{val}} in two places (replacing "exp=number" with "e=number"). The two changes are:

• mobility ... 10 times greater than copper → 10×10⁶ times greater than copper
• shear rates greater than 10 → shear rates greater than 10×10⁴

This looks plausible, and assuming it is correct, a similar edit is needed at Potential applications of graphene. Johnuniq (talk) 11:26, 8 July 2015 (UTC)

I changed the other article, and it also needs a check: diff. Johnuniq (talk) 11:00, 11 July 2015 (UTC)

Preparation -> Exfoliation -> Sonication

The text in this paragraph is describing a way to reduce graphene oxide (by laser scribing) and has nothing to do with sonication imho. Sonication is using ultrasound to exfoliate.: Chem. Soc. Rev., 2014,43, 381-398 DOI: 10.1039/C3CS60217F — Preceding unsigned comment added by 2A02:810A:913F:EEA8:B0BD:2331:9E4D:203F (talk) 15:53, 18 September 2015 (UTC)

Who discovered graphene?

In the history section two patents related to the production of graphene are noted as having been filed prior to Geim's and Novosolev's discovery. Does this mean that those two weren't really the discoverers of graphene and should that title really go to whoever was the first to file a patent? — Preceding unsigned comment added by 164.39.227.235 (talk) 16:48, 12 October 2015 (UTC)

Split Production

This beast is pushing up against 10k words again. Is it time to split out the production stuff into another article? Note that most readers are finding this on their phones... Production is by far the most volatile part of the piece, because new methods pop up all the time. Feedback encouraged! Lfstevens (talk) 07:21, 13 October 2015 (UTC)

Absent feedback, I'm proceeding Lfstevens (talk) 18:10, 15 October 2015 (UTC)

History error..

" to achieve a graphite thickness of 0.00001" (one thousandth) of an inch." States the current article in its history section. Either some text is omitted between parentheses or there are too many zeroes. AnnaComnemna (talk) 17:05, 26 November 2015 (UTC)

x Stronger than steel by weight?

When 207x stronger than steel by weight is claimed in the article, the source (http://news.yahoo.com/5-ways-graphene-change-gadgets-155243022.html) claims 100x steel by weight. However, a different source (http://www.graphenea.com/pages/graphene-properties) claims 130gPa for graphene and 400kPa for structural steel, which works out to about 325x that of steel. Thoughts? OC39648 (talk) 13:11, 26 October 2015 (UTC)

Layman's explanation: "Magic!" Lynxx2 (talk) 18:21, 18 December 2015 (UTC)

Hydrocarbon

• "Graphene can be considered an "infinite alternant" (only six-member carbon ring) polycyclic aromatic hydrocarbon (PAH)."
• = Graphene = polycyclic aromatic hydrocarbon (PAH).

Where does the "Hydro" (Hydrogen involved) come in? Play It Again, SPAM (talk) 07:43, 23 February 2016 (UTC)

Graphene Crumpling

A new study by Brown University has shown that 'crumpling' graphene makes the material more hydrophobic and grants it 'enhanced electrochemical properties', with as much as a 400% increase in electrochemical current density over flat graphene sheets. Does this deserve it's own section, or merely an addendum or a current one? Sources: https://news.brown.edu/articles/2016/03/wrinkles http://onlinelibrary.wiley.com/doi/10.1002/adma.201506194/abstract OC39648 (talk) 20:39, 24 March 2016 (UTC)

External links modified

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epileptic gif

Hello, can we not find a way to stop that epileptic gif about the energy momentum relation?Klinfran (talk) 12:00, 10 October 2016 (UTC)

SPAM

rm a lengthy block describing a commercial effort. Suggest author consider an article about that thing... if it meets guidelines. This article is about the physical material. — Xiong熊talk* 06:26, 28 January 2017 (UTC)

strength of a monolayer

Measurement of the Elastic Properties and Intrinsic Strength of Monolayer Graphene says "The breaking strength is 42 N m–1 and represents the intrinsic strength of a defect-free sheet" Could mention under Mechanical properties ? - Seems to imply each C-C bond can bear ~10 nanonewtons ! - Rod57 (talk) 02:09, 12 March 2017 (UTC)

Transparency

The article seems to be saying that it is both remarkable by its transparency and also one of the most opaque substances known, with an atomic monolayer blocking about 2.5% of the incident light. I wonder if the transparency is that for useful thicknesses, not relativel to the same thickness of other materials. David Woolley (talk) 10:21, 31 March 2017 (UTC)

Meaningless Sentence?

Article says, "The onset temperature of reaction between the basal plane of single-layer graphene and oxygen gas is below 260 °C . . . ." A temperature BELOW 260 could be anything down to absolute zero. Does the author mean to say that the onset temperature of reaction could be as low as absolute zero & that to prevent reaction one must maintain graphene above 260? Is this a typo for "above"? (PeacePeace (talk) 14:44, 9 April 2017 (UTC))

THAT MUSIC VIDEO IS AWESOME

Just want to say whoever added that crazy video of graphene, it was incredible. I even started dancing near the end! — Preceding unsigned comment added by 128.100.148.114 (talk) 15:35, 12 April 2017 (UTC)

Contradiction in first use of term in definition section

"Graphene" is a combination of "graphite" and the suffix -ene, named by Hanns-Peter Boehm,[10] who described single-layer carbon foils in 1962.

The term graphene first appeared in 1987

The first sentence implies the appearance of the term in 1962, while the second sentence says it occurred in 1987. Galobtter (talk) 16:33, 14 October 2017 (UTC)

The first sentence implies that Hanns-Peter Boehm described single-layer carbon foils in 1962, not that the term appeared in 1962. Headbomb {t · c · p · b} 00:24, 24 October 2017 (UTC)

The 1st sentence does state "...named by Hanns-Peter Boehm" -- it is confusing and/or ambiguous. — Preceding unsigned comment added by 2606:A000:4C0C:E200:5185:4DF6:26CE:3290 (talk) 18:00, 14 November 2017 (UTC)

Graphene as a potential source of energy

Source. Should we include this in the article? Rehman 00:53, 14 January 2018 (UTC)

The Future of Graphene

Despite its vast array of desirable qualities, graphene has uses in water purification, mobile phones, to electric cars and battery tech this wonder material looks set to revolutionize future industries. The only thing is that as yet nobody has been able to scale it up by, for example stacking it into layers, retaining its fantastic properties on a large scale still remains a battle of more than a decade of experimentation from the initial discovery of graphene.

Currently graphene sheets are a meager one atom thick but a bright spark named Markus Buehler and a team at MIT were able to create a sponge from graphene, its properties were that it was incredibly buoyant and could sit onto of a bubble of soap as well as being super absorbent.

A team of scientists discovered something truly incredible when they tried to cut graphene sponge into different shapes with a laser - it moved! not just a minuscule degree but a whopping 40 centimeters. It is so full of electrons that when focused light is fired at the sponge some manage to escape. The remarkable thing about this reaction, not only being totally unexpected, is that the electrons all fire in the same direction. Any type of light from xenon bulbs to focused sunlight can cause the graphene sponge to jump around.

For many decades it has been a highly regarded theory to use focused light to assist spaceships with fuel demands and send energy from a ground source to ships in space, this new discovery could be a part of the answer to that question. It is also the first major sizable contribution in terms of the scale of graphene. These types of graphene structures could lead to further metallurgical innovations for the future uses of graphene on a larger scale to build space ships. It is about two hundred times stronger than steel and has many desirable properties over aluminum.

This type of material, graphene sponge, is mentioned earlier and also referred to as graphene honeycomb. It can be found in its sections under 'forms' and contains more of a detailed analysis of its physical properties.

Spgsamuel (talk) 18:35, 10 March 2018 (UTC)Spgsamuel

References

Double bonds?

Can graphene be seen as having periodic double bonds like Buckminsterfullerene? Tom Ruen (talk) 22:36, 21 August 2018 (UTC)

Geothermal power application

https://www.youtube.com/watch?v=jD-_ACt7Q1U suggests geothermal power as an application, but our current articles don't mention it.

The person behind it appears to be Manoj Bhargava. There's an interesting article on him from 2015 at National Geographic News but I haven't found any mentions in sources I'd consider reliable on this use of graphene... plenty of left-wing environmental sites but nothing else.

Leading edge or beat-up? It has probably had enough coverage to be encyclopedic either way! Andrewa (talk) 03:07, 9 October 2018 (UTC)

In which direction is 20 nm calculated?

Perpendicular to the sheet, or parallel? Alfa-ketosav (talk) 19:21, 18 November 2018 (UTC)

Why is archive 2 so small -

Why is archive 2 so small (only 3 entries) ? Why was it even made - this talk page is still small. Are the automatic archive parameters set strangely ? (Archive 1 is perhaps too long) Could archive 2 be moved into the start of this talk page (to save people wasting time checking it) ? - Rod57 (talk) 12:36, 1 October 2021 (UTC)