graphene research and technology faq

8/11/2019 Graphene Research and Technology FAQ

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GRAPHENEA

The silicon, plastic, and glass that make up much of our tech these days could soon be

replaced with something old, yet completely new: Graphene.

If graphene sounds like something that could fell a superhero, you're almost right. Its

the thinnest substance known to science, yet its 300 times stronger than steel and

harder than a diamond. High-quality graphene is also transparent and flexible, and its

an excellent conductor of heat and electricity.

Weve known of graphenes existence since the mid-1800s, but scientists have been

able to experiment with graphene only in the past decade. In 2004, two researchers at

the University of Manchester isolated graphene for the very first time, usingbelieve it

or nota chunk of graphite and a roll of adhesive tape.

Graphene is a crystalline structure composed entirely of carbon atoms, arranged in a

hexagonal, honeycomb-like pattern. Graphene's single-atom thinness (meaning it has

length and width, but no height) makes it as close to 2D as any substance can be.

Graphene is also a fundamental component of other allotropes (structurally different

forms of the element carbon). These include charcoal, carbon nanotubes, and other

fullerenes (molecules composed solely of carbon).

( https://cms-images.idgesg.net/images/article/2014/04/graphene_structure-

@MarcoChiappetta Apr 29, 2014 3:00 AM

hene research and technology FAQ http://www.pcworld.com/article/2147304/graphene-is-the-super-s

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MARCO CHIAPETTA

100263091-orig.png)

It is graphenes unique structure and composition that endows it with so many valuable

properties. Carbon atoms have four electrons in their outer shell, three of which form

strong covalent bonds with the electrons in neighboring carbon atoms. This gives

graphene its signature hexagonal shape. The fourth electron in each carbon atom, now

known to be fermions, behave l ike relativistic particles described by the Dirac equation

(which, in another sci-fi twist, also implies the existence of antimatter).

Getting back to graphene, it is those free electrons, in conjunction with the materials

relative uniformity, that make graphene such an excellent electrical and thermal

conductor, superior to copper and silver respectively. The strong covalent bonds

between the carbon atoms, meanwhile, give graphene its strength.

Layers of graphene are bonded by weak van der Waals forces (the sum of at tractive

forces between two surfaces, accounting for a lizards ability to climb vertical walls,

among other things). The bonds between the carbon atoms in each layer of graphene,

on the other hand, are incredibly strong; in fact, a hammock fabricated from a single-

atom-thick sheet of graphene could support a load of nearly 9 pounds.

High-quality graphene is also lightweight, flexible, impermeable to other elements, and

its virtually transparent. Thanks to the space between its atoms, the material absorbs

just 2.3 percent of white light, allowing 97 percent to pass through.

Potential applications for graphene are nearly limitless. Numerous projects are already

underway in industries ranging from consumer electronics to sporting goods. To date,

graphene-based consumer products have been limited to items that use a small

amount of the substance in protective coatings. Once the mysteries of graphene

manufacturing have been unlockedmore on that lateryou can expect to find the

material everywhere.


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IDGNS

One area where graphene is likely to have the most immediate impact is the

manufacture of flexible and transparent electronics, such as touchscreens. Graphene

could replace indium, which is one of the rarest elements on Earth. (Carbonthe

foundation of grapheneis one of the most abundantelements on the planet.)

Graphene is also lighter, thinner, and stronger than indium. Ultra-strong windshields

that double as display clusters are not out of the realm of possibility. Neither is Tony

Starks transparent smartphone.

Graphenes electrical properties also render it an ideal material for building integrated

circuits. During a Q&A session at the 2013 Intel Developers Forum, Intel CEO Brian

Krzanich said the company is evaluating graphenes potential use in chip

manufacturing, replacing silicon. Routine use, he said, would be a few generations

out, putting it roughly in the 2020 timeframe.

Graphene might also serve as the foundation for next-generation solid-state capacitors

that charge more quickly than todays offerings and hold a charge for much longer. And

graphene could usher in an age of ultra-powerful, lightweight batteries with far more

capacity than anything available today. By super-cooling graphene and surrounding it

in strong magnetic fields, researchers have also been able to alter the direction of the

flow of electrons along graphenes surface, based on the spin of the electrons, which

opens up possibilities for quantum computing (http://www.pcworld.com/article/2107700

/dwave-prepping-quantum-computers-to-outperform-conventional-servers.html).

Graphene wont be relegated solely to electronics and display technology. Its excellent

strength-to-weight ratio could also pave the way for strong, lightweight vehicles, while

its transparency and electrical conductivity make it a good candidate for future solar

panels. Punching nano-sized holes in a sheet of otherwise impermeable graphene

could be used in machines that pull a single strand of DNA through the hole, for rapid

DNA sequencing, or water purification or desalination.

Before those fantastical devices can become reality, however, industry must first

develop a reliable, cost-effective manufacturing process. That's where the majority of


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current graphene research effort is concentrated.

Graphene is being manufactured today using a number of methods: The Scotch tape

method (also known as mechanical exfoliation or the cleavage method), is the simplest.

This is how Andre Geim and Konstantin Novoselov isolated graphene from a larger

hunk of graphite in 2004research that led to their being awarded the Nobel Prize in

Physics in 2010.

( https://cms-images.idgesg.net/images/article/2014/04/graphene_tape-100263092-

orig.png)

The adhesive tape is used to extract small pieces of graphite from a larger chunk. A

layer of graphene is peeled away from the graphite by continually folding the tape over

the pieces and then separating the tape. The strength of the adhesive overcomes the

weak van der Walls forces holding the layers of graphite together until there is a single

layer, yielding graphene.

Mechanical exfoliation can be used only to isolate relatively small pieces of graphene,

however, so researchers are experimenting with other methods to produce larger

quantities.

Chemical vapor deposition (CVD) is one of the most promising. In this process,

chemical vapors are evaporated in a furnace, leaving a graphene deposit on a thin

metal substrate. A similar process has been used in the manufacture of very large

integrated circuits (VLSI) for many years. Graphene can also be isolated by

submerging graphite in a liquid and blasting it with ultrasonic waves to separate its

individual layers, or by slicing an edge of a cylinder formed from graphene (also known

as a carbon nanotube).

Using these methods, scientists have been able to produce pieces of graphene of

various qualities and sizes, including long graphene strands that have already been

used to make super-capacitors. While some companiesmost recently Samsung


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(http://global.samsungtomorrow.com/?p=35576)have claimed breakthrough

achievements in graphene manufacturing, most of the known work remains academic

and has not yet scaled to real-world industrial applications.

Were still a ways off from widespread availability of graphene-based microprocessors,

flexible touchscreens, and similarly exotic new devices. But when industry perfects a

practical and inexpensive means of manufacturing graphene, you can bet it will

become as ubiquitous as plastics are today.

Image credits: The image at the top of this page is courtesy of Graphenea

(http://www.graphenea.com/), a graphene manufacturer and supplier. The image of the

graphite, adhesive tape dispenser, and graphene transistors was released by the

copyright holder (http://en.wikipedia.org/wiki/File:Nobelpriset_i_fysik_2010.tif) into the

public domain.


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