Researchers find simple and cheap way to mass-produce graphene nanosheets

Mar 26, 2012
Made of a single sheet of carbon atoms, graphene can be spun at the fastest rate of any known macroscopic object. Image credit: Wikimedia Commons.

Mixing a little dry ice and a simple industrial process cheaply mass-produces high-quality graphene nanosheets, researchers in South Korea and Case Western Reserve University report.

Graphene, which is made from , the same stuff as "lead" in pencils, has been hailed as the most important in a century. Sheets conduct electricity better than copper, heat better than any material known, are harder than yet stretch.

Scientists worldwide speculate graphene will revolutionize computing, electronics and medicine but the inability to mass-produce sheets has blocked widespread use.

A description of the new research will be published the week of March 26 in the online Early Edition of the .

Jong-Beom Baek, professor and director of the Interdisciplinary School of /Advanced Materials & Devices, Ulsan National Institute of Science and Technology, Ulsan, , led the effort.

"We have developed a low-cost, easier way to mass produce better graphene sheets than the current, widely-used method of acid oxidation, which requires the tedious application of toxic chemicals," said Liming Dai, professor of macromolecular science and engineering at Case Western Reserve and a co-author of the paper.

Here's how:

Researchers placed graphite and frozen carbon dioxide in a ball miller, which is a canister filled with stainless steel balls. The canister was turned for two days and the mechanical force produced flakes of graphite with edges essentially opened up to chemical interaction by carboxylic acid formed during the milling.

The carboxylated edges make the graphite soluble in a class of solvents called protic solvents, which include water and methanol, and another class called polar aprotic solvents, which includes dimethyl sulfoxide.

Once dispersed in a solvent, the flakes separate into graphene naonsheets of five or fewer layers.

To test whether the material would work in direct formation of molded objects for electronic applications, samples were compressed into pellets. In a comparison, these pellets were 688 times better at conducting than pellets yielded from the acid oxidation of graphite.

After heating the pellets at 900 degrees Celsius for two hours, the edges of the ball-mill–derived sheets were decarboxylated, that is, the edges of the nanosheets became linked with strong hydrogen bonding to neighboring sheets, remaining cohesive. The compressed acid-oxidation pellet shattered during heating.

To form large-area graphene nanosheet films, a solution of solvent and the edge-carboxylated graphene nanosheets was cast on silicon wafers 3.5 centimeters by 5 centimeters, and heated to 900 degrees Celsius. Again, the heat decarboxylated the edges, which then bonded with edges of neighboring pieces. The researchers say this process is limited only by the size of the wafer. The electrical conductivity of the resultant large-area films, even at a high optical transmittance, was still much higher than that of their counterparts from the acid oxidation.

By using ammonia or sulfur trioxide as substitutes for and by using different solvents, "you can customize the edges for different applications," Baek said. "You can customize for electronics, supercapacitors, metal-free catalysts to replace platinum in fuel cells. You can customize the edges to assemble in two-dimensional and three-dimensional structures."

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User comments : 22

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CapitalismPrevails
3.7 / 5 (9) Mar 26, 2012
I'm still waiting for a 500 ghz graphene processor to be made available for purchase on TigerDirect or NewEgg.
Husky
not rated yet Mar 26, 2012
a sheet of pressed flakes, not exactly a pristine single layer sheet of macroscopic proportions with ultmate properties, but getting there...
tgoldman
5 / 5 (1) Mar 26, 2012
half the size (46 percent) -- radius or volume?
not specifying is very poor science reporting
Kinedryl
1 / 5 (5) Mar 26, 2012
Researchers placed graphite and frozen carbon dioxide in a ball miller, which is a canister filled with stainless steel balls. The canister was turned for two days and the mechanical force produced flakes of graphite with edges
How large and flat the largest graphene flake can be after such a cruel treatment? For purpose of electronic only large sheets of graphene are of practical significance, the small ones are just graphite dust.

The "graphene" word apparently became a hype, which is opening the doors for another grants - so it's used even under situations, when the individual graphite flakes weren't handled at all. It's example of positive synergy: the research based on popular research becomes popular too.
El_Nose
not rated yet Mar 26, 2012
@Kinedryl

To form large-area graphene nanosheet films, a solution of solvent and the edge-carboxylated graphene nanosheets was cast on silicon wafers 3.5 centimeters by 5 centimeters, and heated to 900 degrees Celsius. Again, the heat decarboxylated the edges, which then bonded with edges of neighboring pieces. The researchers say this process is limited only by the size of the wafer.

mmead
1 / 5 (4) Mar 26, 2012
half the size (46 percent) -- radius or volume?
not specifying is very poor science reporting


Of course it is, it came from Korea....
PhotonX
3 / 5 (2) Mar 26, 2012
Researchers placed graphite and frozen carbon dioxide in a ball miller, which is a canister filled with stainless steel balls. The canister was turned for two days and the mechanical force produced flakes of graphite with edges
How large and flat the largest graphene flake can be after such a cruel treatment? For purpose of electronic only large sheets of graphene are of practical significance, the small ones are just graphite dust.

The "graphene" word apparently became a hype, which is opening the doors for another grants - so it's used even under situations, when the individual graphite flakes weren't handled at all. It's example of positive synergy: the research based on popular research becomes popular too.

What are you talking about? Graphene is trendy now in the same way that transistors were in 1960, and represents a sea change that will reach much farther than simple electronic displays.
Deadbolt
5 / 5 (1) Mar 26, 2012
Harder than diamonds?

Their tensile strength is higher, but I don't know about hardness.

Callippo
2 / 5 (3) Mar 27, 2012
What are you talking about? Graphene is trendy now in the same way that transistors were in 1960, and represents a sea change that will reach much farther than simple electronic displays.
But the transistors were trendy in 60's because of their wide industrial applications, whereas graphene is trendy because of number of grant applications. This is a difference. We should always distinguish the findings, which are hyped because they do serve the human society as a whole and the findings, which do serve only close community of researchers. I'm afraid, the cold fusion belongs into first category, but the graphene into later one. There is a huge community of researchers, who just seek the job opportunity and it doesn't care about practical applications.
Callippo
1 / 5 (2) Mar 27, 2012
The graphene manifests its miraculous properties only under situation, when you succeed with preparation of as large, compact and defect-free sheets, as possible. I'm afraid, the grinding of graphene two days in ball miller goes against the very spirit of graphene technology. It's like the preparation of carbon nanotubes for space elevator - we can prepare them with milling in cheap way, but these nanotubes will be so short and eroded, they will become unusable for production of strong rope.
Graeme
5 / 5 (1) Mar 27, 2012
By adding different edges to the little flakes they could customise the diffferent kind of flakes o different properties and then link them together using the edge functional groups to tie the different bits together, into planned assemblages. You could probably tag the edges with sulfide, metals such as iron or zinc. By making these in a pattern you coudl make it bind with something in the recipricaol pattern, eg Zn with sulfur, with a binary pattern of Zn and S along an edge could basically give the fragment a barcode to allow routing or combination with its correct connecting part.
Graeme
not rated yet Mar 27, 2012
Calippo> Eventuyally someone will get the technology to fix the defects, what you need is soemthing that can fill in the holes with carbon, or trim off the extra bits that should not be there that may make a bump, eg a carbon with 4 bonds.
Callippo
1 / 5 (2) Mar 27, 2012
It's not just about defects. I cannot imagine, how you could prepare defined monolayer of graphite with using of milled graphite dust. The graphene works only if you have just one layer of graphite: no less, no more.
MarkyMark
4 / 5 (4) Mar 27, 2012
I cannot imagine,

not supprising this! I expect real scientists CAN imagine, and above all imagine things that are possable rather than in myths like the E-CAT that actually works or 'Cold' Fusion.
Skepticus
3.7 / 5 (3) Mar 27, 2012
If they can perfect this graphene from CO2 into mass production by the millions of ton, perhaps there would be no need for carbon sequestration. There would be literally thousands of uses for the stuff.
Bret_Bowlby
not rated yet Mar 27, 2012
Now I'm curious as to the effect graphene sheets could be used in air batteries. By using three layers consisting of graphene, maganese oxide and zinc powdered anode with an electrolyte. Any thoughts on this?
sirchick
5 / 5 (1) Mar 27, 2012
I cannot imagine,

not supprising this! I expect real scientists CAN imagine, and above all imagine things that are possable rather than in myths like the E-CAT that actually works or 'Cold' Fusion.


WHY! Why did you have to mention cold fusion, you're risking a really off topic discussion on a subject most people don't care about! lol
Bret_Bowlby
not rated yet Mar 27, 2012
I cannot imagine,

not supprising this! I expect real scientists CAN imagine, and above all imagine things that are possable rather than in myths like the E-CAT that actually works or 'Cold' Fusion.


WHY! Why did you have to mention cold fusion, you're risking a really off topic discussion on a subject most people don't care about! lol


LOL so true; well with the exception about the caring part.
PhotonX
not rated yet Mar 27, 2012
But the transistors were trendy in 60's because of their wide industrial applications, whereas graphene is trendy because of number of grant applications. This is a difference.


I should have said that graphene research now is like the creation and evaluation of the properties and behaviors of doped silicon then, the basic prerequisite foundation upon which transistors stand. That said, it's absurd to assert that graphene research is only a manifestation of trendy grant applications. Can you say that transistor research was any different? And if it was different, then it's a biased comparison to begin with.
PhotonX
1 / 5 (1) Mar 27, 2012
We should always distinguish the findings, which are hyped because they do serve the human society as a whole and the findings, which do serve only close community of researchers. ... There is a huge community of researchers, who just seek the job opportunity and it doesn't care about practical applications.

.
And how can you know this difference in advance? Are you claming to be prescient? I'll concede that the grant money scramble is detrimental to science, given research funds falling short of the needs. (See current related article http://www.physor...al.html) I'm won't concede it for nanotechnology research given the immense rewards this research promises. It's not the fault of the scientists that this lottery mentality exists based on dollar$ granted per article published.
PhotonX
1 / 5 (1) Mar 27, 2012
I'm still waiting for a 500 ghz graphene processor to be made available for purchase on TigerDirect or NewEgg.

You're talking about the clocked-down 16-core mobile version, right?
sender
not rated yet Mar 31, 2012
Looks like the IMF needs to conduct some business manifesto's to improve the resource utility cost difference to foundries between silicene and graphene.

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