Frustration inspires new form of graphene
They're the building block of graphite ultra-thin sheets of carbon, just one atom thick, whose discovery was lauded in 2010 with a Nobel Prize in Physics.
The seemingly simple material is graphene, and many researchers believe it has great potential for many applications, from electronic devices to high-performance composite materials.
Graphene is extremely strong, an excellent conductor, and with no internal structure at all, it offers an abundance of surface area much like a sheet of paper.
When it comes to producing and utilizing graphene on a large scale, however, researchers have come upon a major problem: the material's tendency to aggregate. Like paper, graphene sheets easily stack into piles, thus greatly reducing their surface area and making them unprocessable.
Researchers at Northwestern University have now developed a new form of graphene that does not stack. The new material inspired by a trash can full of crumpled-up papers is made by crumpling the graphene sheets into balls.
A paper describing the findings, "Compression and Aggregation-resistant Particles of Crumpled Soft Sheets," was published October 13 in the journal ACS Nano.
Graphene-based materials are very easily aggregated due to the strong interaction between the sheets, called "Van der Waals attraction." Therefore, common steps in materials processing, such as heating, solvent washing, compression, and mixing with other materials, can greatly affect how the sheets are stacked. When the paper-like sheets band together picture a deck of cards their surface area is lost; with just a fraction of its original surface area available, the material becomes less effective. Stacked graphene sheets also become rigid and lose their processability.
Some scientists have tried to physically keep the sheets apart by inserting non-carbon "spacers" between them, but that changes the chemical composition of the material. When graphene is crumpled into balls, however, its surface area remains available and the material remains pure.
"If you imagine a trash can filled with paper crumples, you really get the idea," says Jiaxing Huang, Morris E. Fine Junior Professor in Materials and Manufacturing, the lead researcher of the study. "The balls can stack up into a tight structure. You can crumple them as hard as you want, but their surface area won't be eliminated, unlike face-to-face stacking."
"Crumpled paper balls usually express an emotion of frustration, a quite common experience in research," Huang says, "However, here 'frustration' quite appropriately describes why these particles are resistant to aggregation because their uneven surface frustrates or prevents tight face-to-face packing no matter how you process them."
To make crumpled graphene balls, Huang and his team created freely suspended water droplets containing graphene-based sheets, then used a carrier gas to blow the aerosol droplets through a furnace. As the water quickly evaporated, the thin sheets were compressed by capillary force into near-spherical particles.
The resulting crumpled graphene particles have the same electrical properties as the flat sheets but are more useful for applications that require large amounts of the material. The ridges formed in the crumpling process render the particles a strain-hardening property; the harder you compress them, the stronger they become. Therefore, the crumpled graphene balls are remarkably stable against mechanical deformation, Huang said.
"We expect this to serve as a new graphene platform to investigate application in energy storage and energy conversion," Huang said.
Provided by
Northwestern University
-
From lemons to lemonade: Reaction uses carbon dioxide to make carbon-based semiconductor,
32 comments
-
Thioridazine kills cancer stem cells in human while avoiding toxic side-effects of conventional cancer treatments,
3 comments
-
SpaceX private rocket blasts off for space station (Update),
42 comments
-
Climate scientists say they have solved riddle of rising sea,
31 comments
-
SpaceX capsule has 'new car' smell, astronauts say (Update),
3 comments
-
microstructure of titanium
22 hours ago
-
Steam in My Espresso Machine
May 26, 2012
-
Density question
May 24, 2012
-
Mass transport originating from a point source at a solid gas interface
May 22, 2012
-
Ammonia dispersion in Air
May 22, 2012
-
Multi Choice Help
May 21, 2012
- More from Physics Forums - Materials & Chemical Engineering
More news stories
'Unzipped' carbon nanotubes could help energize fuel cells, batteries
Multi-walled carbon nanotubes riddled with defects and impurities on the outside could replace some of the expensive platinum catalysts used in fuel cells and metal-air batteries, according to scientists at ...
Nanotechnology / Nanomaterials
1 hour ago |
not rated yet |
0
|
In nanorod crystal growth, nanoparticles seen as artificial atoms
In the growth of crystals, do nanoparticles act as "artificial atoms" forming molecular-type building blocks that can assemble into complex structures? This is the contention of a major but controversial theory ...
May 24, 2012 |
4.8 / 5 (6) |
0
|
Dopant gives graphene solar cells highest efficiency yet
(Phys.org) -- By taking advantage of graphenes favorable electrical and optical properties, and then adding an organic dopant, researchers have achieved the highest power conversion efficiency yet for ...
First direct observation of oriented attachment in nanocrystal growth
Berkeley Lab researchers have reported the first direct observation of nanoparticles undergoing oriented attachment, the critical step in biomineralization and the growth of nanocrystals. A better understanding ...
May 24, 2012 |
4.7 / 5 (3) |
0
|
Synthetic nano-waste does not disappear
(Phys.org) -- Tiny particles of cerium oxide do not burn or change in the heat of a waste incineration plant. They remain intact on combustion residues or in the incineration system, as a new study by Swiss ...
Nanotechnology / Bio & Medicine
May 25, 2012 |
5 / 5 (2) |
1
|
Computer model used to pinpoint prime materials for efficient carbon capture
When power plants begin capturing their carbon emissions to reduce greenhouse gases and to most in the electric power industry, it's a question of when, not if it will be an expensive undertaking.
T cells 'hunt' parasites like animal predators seek prey, study shows
By pairing an intimate knowledge of immune-system function with a deep understanding of statistical physics, a cross-disciplinary team at the University of Pennsylvania has arrived at a surprising finding: T cells use a movement ...
Yale study concludes public apathy over climate change unrelated to science literacy
Are members of the public divided about climate change because they don't understand the science behind it? If Americans knew more basic science and were more proficient in technical reasoning, would public consensus match ...
Same gene that stunts infants' growth also makes them grow too big: research
UCLA geneticists have identified the mutation responsible for IMAGe* syndrome, a rare disorder that stunts infants' growth. The twist? The mutation occurs on the same gene that causes Beckwith-Wiedemann syndrome, which makes ...
Change in developmental timing was crucial in the evolutionary shift from dinosaurs to birds: study
At first glance, it's hard to see how a common house sparrow and a Tyrannosaurus Rex might have anything in common. After all, one is a bird that weighs less than an ounce, and the other is a dinosaur that ...
Scientists develop ultra-sensitive test that detects diseases in their earliest stages
Scientists have developed an ultra-sensitive test that should enable them to detect signs of a disease in its earliest stages, in research published today in the journal Nature Materials.
Oct 14, 2011
Rank: 5 / 5 (1)
Oct 15, 2011
Rank: not rated yet
Oct 15, 2011
Rank: 1 / 5 (1)
I wonder how mutagenic this new form of graphene is, since nano tubes of carbon are pretty bad it would be nice to find a safe form of the stuff.
Oct 15, 2011
Rank: not rated yet
Why not try for a corrugated structure based on the carbon cups used for " cup-stacked " carbon nanotubes, ie, for spacers between multiple sheets ?
Oct 15, 2011
Rank: 5 / 5 (1)