Monday, December 28, 2020

When pattern of work targeted by hostile takeovers, enable long LSTM guards.

If you purchased this blog without a cover, be aware that the author has not received payment for her work on these (and other) publications.

Wednesday, April 1, 2015

Graphene Makes Quick-Charge Super Capacitors

The most annoying problem with re-chargeable electric batteries is that they can take a long time to charge.  From electronic devices to electric car batteries... nobody likes waiting for the juice to be re-filled.

But one of graphene's more interesting properties is its ability to conduct electrons in such a way that very few electrons are "lost" in the process of charging.   As I wrote about a while ago, its conductive properties are powerful.  Now imagine all that power being conducted mega-efficiently into a very strong capacitor.  Capacitors are essentially miniature silos of energy storage.  A "super" capacitor is a stronger capacitor1, and a micro-supercapacitor is next.
"...Researchers at UCLA's California NanoSystems Institute have successfully combined two nanomaterials to create a new energy storage medium that combines the best qualities of batteries and supercapacitors.
The new hybrid supercapacitor stores large amounts of energy, recharges quickly and can last for more than 10,000 recharge cycles. The CNSI scientists also created a microsupercapacitor that is small enough to fit in wearable or implantable devices. Just one-fifth the thickness of a sheet of paper, it is capable of holding more than twice as much charge as a typical thin-film .  
"The microsupercapacitor is a new evolving configuration, a very small rechargeable power source with a much higher capacity than previous lithium thin-film microbatteries," El-Kady said.
The new components combine laser-scribed graphene, or LSG—a material that can hold an , is very conductive, and charges and recharges very quickly—with manganese dioxide, which is currently used in alkaline batteries because it holds a lot of charge and is cheap and plentiful. They can be fabricated without the need for extreme temperatures or the expensive "dry rooms" required to produce today's supercapacitors."   - Source:  Phys.org

1.  The difference between Capacitors and Super-capacitors:
• Super-capacitors have a very high energy density than normal capacitors.
• Super-capacitors use two layers of the dielectric material separated by a very thin insulator surface as the dielectric medium, whereas normal capacitors use only a single layer of dielectric material.
• Normal capacitors are much cheaper than the super-capacitors in general.
 

Tuesday, January 14, 2014

Sugar String Graphene Balloons

A recent article discussing an innovative technique for creating a 3D strutted framework for graphene mentions some inspiration came from blown sugar art:
The research group succeeded for the first time in the world in making 3-D graphene products, by applying an innovative, never-before-published method inspired by the blown sugar art,
which they call the "chemical blowing method" or uniquely name as "sugar-blowing method".   In this method, glucose and ammonium salt are mixed and heated at around 250 C, through which glucose-deriving polymers can be obtained. The released ammonia gases "blow" polymers by creating pressure from the inside, generating a number of small polymer bubbles of tens of microns. Concurrently, a framework for stabilizing the structure is formed and a product with a strutted 3-D structure is made.

So I looked up sugar art, and it  got me thinking back to my childhood days.  Maybe there's something similar that could possibly produce results better suited to graphene's unique properties . .  something better than the pure sugar method . . .

Sugar string-wrapped balloons!
image credit: http://i562.photobucket.com/albums/ss66/abentleylarsen/IMG_0001.jpg
When I was a little girl between first and third grades, my grandmother would have me over to her house every year where we'd make these ridiculously messy, but very fun and cool Easter baskets.

These Easter baskets were very simple and crafty, made out of sugar-water soaked yarn and balloons.  After dipping the yarn into sugar water, you "wrap" the balloon in swaddles of this messy gooey yarn, and tie it somewhere outside dry.  After the water dissolves and the sugar hardens, the shape of the balloon remains via the crystallized structure.  After a few hours, it stiffens pretty hard and becomes surprisingly sturdy.  Sturdy enough to be an Easter basket and lightweight as can be.   

This seems like it has some interesting implications, and could be an even better method of creating a sturdy lattice for graphene to have an amazingly large surface area in what generally amounts to small space -- all the while retaining the "hollow" and therefore lightweight property that makes graphene so special and amazing.

Graphene-oxide + water + dissolved sugar-soaked balloons? 

Presuming that this technique can be patented and used with graphene, I shall pre-emptively call patents and trademarks and copyrights and whatever else for the "sugar string graphene balloon" method of producing 3D graphene.

For the record:  to-date (prior to the publishing of this post) there are no results for "sugar string graphene" .. dibs!
 


Awesome.  Remember you read it here first, and if you're so inclined -- please buy your graphene hacking materials smartly.   Collaboration and shared credit really are going to be the way to usher in the new generation of conceptualized science.  

Lowering the Cost of Solar Power

A collaboration between James I University in Spain and Oxford University has achieved a new record in efficiency for solar cells.  And not only is the solar energy more efficiently captured with titanium oxide (rather than silicon), but the techniques used to produce them require less energy, and are thus lower cost.

The high efficiency solar cell, consisting of several layers, can be manufactured at rather low temperatures of about 150 degrees Celsius. The low temperature requirements combined with its high

efficiency, the researchers believe, make the device a suitable candidate for large-scale manufacturing. Lower energy demands mean lower cost of production compared with conventional solar cells. The low temperatures during production would also enable the graphene-petrovskite-based solar cells to be combined with devices based on flexible plastics

sources: 
http://eandt.theiet.org/news/2014/jan/graphene-solar-cell.cfm
http://universe-review.ca/I12-22-solarpower.gif

Monday, December 23, 2013

Graphene Hacking -- A Recipe for Graphene

How to make graphene at home for various uses of experimentation and invention?

First, some clarifications:
  • Graphene is technically only "flat" like a lattice wire one atom thick.  Ten or more layers one atom thick ar Graphite. Layers of graphene one on top of the other are graphite AKA #2 pencil lead1
  • Graphite is available in various forms and can be used to produce graphene.
  • Graphene oxide is a water-soluble "flaked" form of graphene that has a spongelike quality and the ability to adsorb and absorb molecules according to the chemical properties of graphene, H2O, and whatever else.
  • Graphene aerogel (pictured below) is a mixture of carbon nanotubes and graphite; the end result is an extraordinarily lightweight and strong substance that has unique thermal properties.
photo credit: extremetech.com

 

The first method of producing graphene in actual "sheets" not bound to any tape surface (see article below) requires graphene oxide.  There are several ways to get graphene oxide:  one is to purchase prepared vials of graphene oxide -- which can be expensive, but easy.  The other is to make it yourself from various industrial suppliers  -- to hack the composition of the graphene yourself using chemistry and a recipe of ingredients -- sulfuric acid, sodium nitrate, potassium permanganate, etc.   


Graphene oxide can be a bit complicated to pull off, but not impossible to do at home for the amateur chemist.  The original paper from 1958 defining the technique can be found here; the recipe below has been derived from some of the academic research discussed here.

A Recipe for Graphene Oxide

Materials needed (can be obtained via Amazon):
* Not recommended to double this recipe unless you're a certified lab with professionals, or in a very safe preparation space. 
  • 50 grams graphite, pre-powdered or shaved into powder form
  • 25 grams sodium nitrate (NaNO3)
  • 150 grams potassium permanganate (KMnO4)
  • 1.15 liters sulfuric acid (H2SO4)
  • 2.4 liters of water  (H2O)
  • Hydrogen Peroxide (H2O2)
  • large chemical-reaction-friendly container (capable of holding 8 - 10 liters)
  • larger leakproof bowl for "ice bath"
  • stirring stick
  • enough ice for an ice bath around the chemical-reaction friendly container
  • thermometer
  • safety equipment:  (goggles, gloves, etc)   

Directions:

1.  In the leak-proof bowl prepare the ice bath and place the chemical-reaction-friendly container in it. The production of graphene oxide releases a lot of thermal energy and the ice bath is imperative!

2.  Pour the sulfuric acid into the chemical-reaction-friendly container.

3.  Mix the powdered graphite and sodium nitrate slowly into the sulfuric acid, stirring continually.

4.  Add the potassium permanganate to the mixture in a very slow drizzle. 
 WARNING -- Potassium permanganate is a powerful oxidizer that can burn or stain skin and other organic materials such as clothing upon contact. When mixed with sulfuric acid, it produces a highly explosive manganese oxide, so every safety measure should be taken.   Make sure the maximum temperature is not exceeded.
5.  After the potassium permanganate has been slowly and carefully dissolved into the mixture, remove the ice-bath and allow the temperature to come up to 35 degrees Celsius.  Maintain this temperature for ~ 30 minutes, and watch as the solution thickens and gases reduce.  At around the 20 minute mark, expect the solution to be brownish-gray and beginning to thicken to a more pasty consistency.

6.   After 30 minutes have passed, slowly and carefully add 2.4 liters of water into the mixture while stirring.  Adding H2O at this point should create an exothermic reaction, increasing the temperature of the mixture to close to 100 degrees Celsius; a large volume of gas will be released in a violent reaction! Maintain the temperature at 98 degrees Celsius for another 15 minutes.  At this point the solution should be a murky brown.

7.  After maintaining the temperature for 15 minutes, further dilute the mixture to a total of 7 liters of fluid with warm water.  Add 3% hydrogen peroxide in order to reduce the leftover permanganate. With the addition of hydrogen peroxide, the mixture should turn bright yellow.

8.   Filter the mixture while still warm. The filter will take a yellow-brown color. Wash the filter cake three times with a total of 10 liters of warm water.

9.  Disperse the resulting graphite oxide in at least 12 liters of water.  The quickest way produce dry graphite oxide is by using a centrifuge to "dry" the mixture; but for the average at-home experimenter, a centrifuge is likely not practical.  As an alternative means, the water containing graphite oxide may be heated to 40 degrees Celsius and left to evaporate.  A large, flat and thin "pool" of water for evaporation works best since the rate of evaporation is correlated to the surface area upon which it is allowed to evaporate. 

That's it! After the water has been centrifuged-away or evaporated the remaining substance should be pure flakes of graphene oxide -- capable of cleaning up radioactive waste.  Higher grades can be distinguished by brighter yellow flakes.  If you messed something up, the end result may be dark green or black.  This is not "useless" oxide but simply less effective at screening pollutants; the "percent Hydrogen Peroxide" can be altered slightly to obtain more "pure" graphene oxide flakes, but -- of course -- extra precautions should be taken when repeating the experiment any variables altered.



Recipe for Graphene (using the Graphene Oxide we just made)

DVD burner - LightScribe technology approach

Graphite oxide is water-soluble, so after mixing it with water, carefully pour it on a DVD drive. Make sure the graphite oxide solution is evenly distributed on the plastic surface of the disc. After the solution has dried and created a film of graphite oxide on the disc, place the disc into the DVD drive, film-side down. Use the LightScribe software to burn in the layer of oxide. The areas of the film which come into contact with the laser beam will be turned into graphene. What actually happens is a reduction reaction which reduces graphite oxide back into graphene. The resulting graphene layer should be carefully removed from the disc and cut into appropriate sized pieces.




Recipe for Graphene 

Pencil & Tape Method (for electrical circuitry hacking)

Believe it or not, it is possible to create graphene with some pencils and simple Scotch tape.  Graphene in this form isn't quite as useful as pure sheets, but can be used to demonstrate some of the electrical properties of nanoscale graphene.
Materials needed:
  • 2 pencils, sharpened
  • any kind of transparent tape

Directions:
1.  Lay a piece of tape flat on a surface such that the sticky side faces up.  You may wish to fold over each end of the tape to adhere to a base surface.   

2.  Rub together the two sharpened pencils' sharpened tips with enough pressure to make it "snow" graphite on the tape.   

3.  Repeat the process until a thin gray powder of graphite is barely discernible.

4.  Take a piece of "clean" tape and place it sticky-side face-down on the layer of graphite snow, and pull apart gently

5.  Repeat the process a few times -- until you're pretty sure that you're just sticking and un-sticking bare tape. 

That's it.  Your final "peel" of tape should have a fine layer of graphene atoms bound along the tape. 

  1. Some time before 1565 (some sources say as early as 1500), a large deposit of graphite was discovered on the approach to Grey Knotts from the hamlet of Seathwaite in Borrowdale parish, Cumbria, England. Chemistry was in its infancy and the substance was thought to be a form of lead. Consequently, it was called plumbago (Latin for "lead ore").The black core of pencils is still referred to as lead, even though it never contained the element lead. The words for pencil in German (Bleistift), Irish (Peann Luaidhe), Arabic (قلم رصاص qalam raṣāṣ), and other languages literally mean lead pen.

Friday, November 29, 2013

Tin + Graphene -- Stanene is a conductive material theorized for nearly 100 percent efficiency

Stanford Linear Accelerator researchers have developed a material that may be the holy grail of conductivity -- a material that permits almost 100 percent conductivity between a power source and destination.

Tin (Sn) is a " dull-gray powdery material with no common uses"1, but as an alloy is known for its anti-corrosive properties.2  Combined with the flexible structural integrity of graphene, it creates a nearly-perfect medium for tin's diamond-shaped and inherently covalent nature to "bridge the gap".    The covalent bonding is so strong that electricity can flow literally without losing electrons.

graphic from Wikipedia: The diamond-lattice covalent atomic structure of Sn

Coined "Stanene", this material may soon be replacing copper as the relay of choice for newer-generation electronic circuits.  Copper, while inexpensive and ductile, is susceptible to overheating.   Legacy chips, such as the "POWER3-II chip — about the size of a thumbnail — contains a quarter mile of copper wiring." 3.

More modern electronic circuits may contain several miles of copper "wire" -- sometimes just an atom thick.  High-voltage electricity pushed through such narrow channels may cause the wires to melt and cause electronic components to catch fire.   Stanene would overcome such constraints by allowing the flow to distribute through the "channel of least resistance" more efficiently.

At present, Stanene is but a theoretical, though franchisable "wonder material"; as reported by The Independent,
there are many obstacles standing between stanene and mainstream use (not limited to the difficulties of manufacturing one-atom thick wires on an industrial scale) and without working samples of the material available it is perhaps a little early to get excited.

Sunday, August 11, 2013

Making the Internet go faster with graphene-enhanced switches

Just how tough is graphene?  Researchers have theorized that it'd require an elephant, balanced on a pencil, to break through a single sheet.  Every industry, it seems, has been grazed by graphene's wondrous potential -- the strength, light-weight nature (a single sheet of carbon atoms so thin it's actually transparent), flexibility and conductivity can be replicated at a relatively low cost and applied to a plethora of materials.




The latest industry it may soon help -- telecom.   How?  Enhancing switches to increase speed of data transfer rates. 
"Ordinarily optical switches respond at rate of a few picoseconds – around a trillionth of a second. Through this study physicists have observed the response rate of an optical switch using ‘few layer graphene’ to be around one hundred femtoseconds – nearly a hundred times quicker than current materials."
How would this technology be implemented?  Commenting on the report’s main findings, lead researcher Dr Enrico Da Como noted:

"Right now the capacity for data transfer in fibre optics is below a terabit per second,” he says. “But graphene will allow us to reach the one terabit per second rate ... It will take some years and there is engineering development to be done, but I think it will be in about four or five years. We are working on the first prototypes now." 

sources:  

“Right now the capacity for data transfer in fibre optics is below a terabit per second,” he says. “But graphene will allow us to reach the one terabit per second rate.
“It will take some years and there is engineering development to be done, but I think it will be in about four or five years. We are working on the first prototypes now.”
- See more at: http://www.information-age.com/technology/mobile-and-networking/123457194/graphene-based-optical-switches-promise-lightning-fast-networks--#sthash.SP1VkbfO.dpuf
“Right now the capacity for data transfer in fibre optics is below a terabit per second,” he says. “But graphene will allow us to reach the one terabit per second rate.
“It will take some years and there is engineering development to be done, but I think it will be in about four or five years. We are working on the first prototypes now.”
- See more at: http://www.information-age.com/technology/mobile-and-networking/123457194/graphene-based-optical-switches-promise-lightning-fast-networks--#sthash.SP1VkbfO.dpuf
“Right now the capacity for data transfer in fibre optics is below a terabit per second,” he says. “But graphene will allow us to reach the one terabit per second rate.
“It will take some years and there is engineering development to be done, but I think it will be in about four or five years. We are working on the first prototypes now.”
- See more at: http://www.information-age.com/technology/mobile-and-networking/123457194/graphene-based-optical-switches-promise-lightning-fast-networks--#sthash.SP1VkbfO.dpuf

Wednesday, May 22, 2013

'Printable' Graphene ink writes circuits

CleanTechnica is reporting that a new method of "exfoliating" graphene from blocks of graphite has been developed. "The graphene is being used to develop a low cost, highly conductive ink that can be used to print electronic circuits on flexible material, leading to the next generation of tiny, foldable, mobile electronic devices."


Friday, January 25, 2013

Graphene, interrupted

One of the biggest challenges in working with a material whose chemical-binding properties are contingent upon physical construction is getting that material to "stay put" in its physical form long enough to get the material to do its chemical thing.

crinkled graphene
Graphene's physical construction is often likened to chicken wire, one atom thick; but when it is "unrolled" it can easily contract and constrict in upon itself,  "crumpling" like the skin of a grape into a raisin that has been left in the heat and sun too long.    In its crumpled form, graphene behaves differently, and is significantly more difficult to handle.  

But new research by Duke University offers a new technique for getting the graphene to un-crumple itself.   By adhering the graphene to a rubber film, the chicken wire lattice's crumpling can be controlled and flexed on demand: 
"Duke engineers attached the graphene on a rubber film that had been pre-stretched multiple times of its original size. Once the pre-stretch in the rubber film was relaxed, part of the graphene detached from the rubber while other part kept adhering on the rubber, forming an attached-detached pattern with a size of a few nanometers. As the rubber was relaxed, the detached graphene was compressed to crumple. Once the rubber film was stretched back, the adhered graphene will pull on the crumpled graphene to unfold it."  source: http://www.sciencedaily.com/releases/2013/01/130123165042.htm
This process opens up new frontiers for application such as artificial muscle, which needs a large surface area that can be "deformed" as the muscles constrict and relax naturally.

Xuanhe Zhao, one of the engineers researching this application said, "In particular, they promise to greatly improve the quality of life for millions of disabled people by providing affordable devices such as lightweight prostheses and full-page Braille displays. The broad impact of new artificial muscles is potentially analogous to the impact of piezoelectric materials on the global society."    

Tuesday, January 8, 2013

A sponge to soak up radioactive waste

Flakes of graphene oxide have a "spongelike" quality that can be used to bind to and solidify radioactive waste.  Once in solid form, the contaminated material can be easily collected and cleaned up.

"Capturing radionuclides does not make them less radioactive, just easier to handle. Where you have huge pools of radioactive material, like at Fukushima, you add graphene oxide and get back a solid material from what were just ions in a solution," said chemist James Tour of Rice University. "Then you can skim it off and burn it. Graphene oxide burns very rapidly and leaves a cake of radioactive material you can then reuse."

The large surface area of graphene oxide particles means that they have an increased ability to adsorb and bond with other materials, specifically those with toxic quality which tend to have volatile chemical properties.  The honeycomb lattice of graphene can bond to and essentially stabilize them.     

source: http://www.sciencedaily.com/releases/2013/01/130108112459.htm
Scientists at Rice University and Lomonosov Moscow State University have developed the new method for removing radioactive material. In the flask on the left, the solution contains the particles of graphene oxide (atom thick flakes);  on the right the particles have bonded to simulated radioactive material.

Practical applications range from cleanup of sites such as the Fukushima nuclear power plant to fracking -- or using graphene to filter out contaminants from the water.  "Hot" radioactive water normally needs to be shipped to various containment facilities around the country, which is done so at great expense.

Monday, December 3, 2012

Nanotubular awesomeness

Single-walled carbon nanotubes (SWCNT) are vertical hollow structures comprised of carbon atoms enjoined via industrial-strength hexagonal lattice.  Scientists at Rice University have published research  into a method of "gluing" the SWCNTs to sheets of graphene that maintain the ohmic properties of the bond.

Picture chicken wire that is stronger than steel, yet able to conduct electricity.  Comparatively, copper (Cu) and gold (Au) -- two traditionally "conductive" materials are soft and would never be able to support comparative structures of these relative heights.  Just as an ant is able to lift ~50 times their body weight, these carbon nanotube structures are able to scale to heights beyond imagination -- "up to a distance of 120 microns (0.12mm), which is really rather impressive at this scale. If we scaled it up to actual trees, they would rise into outer space," reports ExtremeTech.

This microcosm of tubular awesomeness is significant because it means that the surface area of a base can actually support much more "storage" power.    That is, supercapacitors, lithium-ion batteries, and other kinds of energy storage may  be able do do more with less. Denser energy storage structures mean longer-life batteries in a smaller space.