Game-changing graphene: the amazing properties of a single-atom layer of carbon

By Catherine

Written by Catherine Bolgar

 

Step aside, silicon. There’s a new substance that promises to revolutionize medicine, industry, water treatment, electronics and much more. That substance is graphene—a single-atom-thick layer of carbon, a millionth of the width of a human hair.Graphene1

The world’s first two-dimensional material, graphene is potentially plentiful (carbon being the sixth most abundant element in the universe) and cheap. And it possesses amazing qualities and potential uses:

It’s transparent, but conducts electricity and heat. Most good conductors are metals such as copper, which is opaque and quick to heat when electricity passes through. But they are prone to hot spots, which form around defects and cause electronic devices to fail. Graphene, by contrast, transfers heat efficiently. “It’s a good alternative to copper,” says Nai-Chang Yeh, professor of physics at California Institute of Technology. Indeed, electronic equipment may in future use graphene-coated copper interconnections to prevent overheating or wear and tear.

It’s light and flexible, but 200 time stronger than steel. The carbon-to-carbon bond is very strong, says Rahul Nair, Royal Society fellow at the University of Manchester. In addition, graphene’s carbon atoms are arranged in a tight, uniform honeycomb structure, which is able to bear loads and resist tearing. A membrane of graphene could withstand strong force without breaking, says Dr. Yeh. It may someday be used in aerospace, transportation, construction and defense.

Graphene_2683650b

It’s a superlubricant. “If you take one piece of flawless graphene and put it on top of another, and slide one against the other, there’s almost no friction,” says Dr. Yeh. Coating machines parts with graphene could minimize unwanted friction, providing industry with countless applications.

It’s impermeable…  Graphene’s honeycomb structure is too tight for any molecules to squeeze through. “If you have graphene on metal, it’s perfect protection, because other molecules in the air cannot penetrate that honeycomb hole,” says Dr. Yeh. Indeed, Dr. Nair has dissolved graphene oxide in water to create a paint-like film that can protect any surface from corrosion. This graphene paint could be used by the oil and gas industry to protect equipment against saltwater, or by pharmaceutical and food packaging firms to block out oxygen and moisture, thereby extending their products’ shelf life, says Dr. Nair.

…but can also be permeable. A single-micrometer-thick film containing thousands of layers of graphene oxide has nanosize capillaries between its layers, which expand when exposed to water. However, those capillaries don’t expand when exposed to other substances. This is unusual because a water molecule is bigger than a helium or hydrogen molecule. However, water behaves differently when it’s within the confined space of a nanometer, moving rapidly through the graphene oxide nanocapillary. By contrast, salt that is dissolved in the water is blocked. One use for this, says Dr. Nair, could be water or molecular filtration.

It’s a chemical contradiction. A sheet of graphene is inert, but its edges are chemically reactive, says Dr. Yeh. A little graphene flake has a large perimeter relative to its area, allowing for more reaction. These flakes could be used to remove toxins from water.

It can be magnetic.  The zigzag-shaped edges of graphene have magnetic properties.f08f1905-624f-4530-846a-ddb2e635fac7-1422539141242“People imagine that you will be able to use graphene sheets as a magnet that can pick up iron at room temperature,” explains Dr. Yeh. That something all-carbon can be magnetic is “amazing,” she adds. Coupled with its electric conductivity, graphene’s magnetic properties may open up all sorts of applications in spintronics and semiconductors.

Graphene’s potential may be extraordinary, but how easy is it to create? It was first isolated in 2004 at Manchester University by Andre Geim and Konstantin Novoselov who won the 2010 physics Nobel Prize for their work. They arrived at graphene by using adhesive tape to peel off ever-thinner layers from graphite, a process subject to continual improvement. In one common method, copper is heated to 1,000 degrees Celsius, near its melting point. Methane gas, comprising carbon and hydrogen molecules, is then added, and the copper rips off the bond between the two molecules, dissolving the carbon into the copper and letting the carbon “grow” on the surface, Dr. Yeh explains. The result is a sheet of graphene.

David Boyd and Wei-Hsiang Lin, working with Dr. Yeh at Caltech, however, found that what counts most is not heat but clean copper.  Copper oxidizes quickly in air and so has a thin layer of carbon oxide on its surface. They use hydrogen plasma, which has “gas radicals that behave like erasers and clean up the surface of the copper,” Dr. Yeh explains. The process allows graphene to grow in five minutes at room temperature.

Most importantly, this method could be scaled up to produce industrial amounts of high-quality graphene—a huge step towards realizing its true potential.

Catherine Bolgar is a former managing editor of The Wall Street Journal Europe. 

For more from Catherine Bolgar, contributors from the Economist Intelligence Unit along with industry experts, join the Future Realities discussion.

Test tube transport: the Hyperloop nears reality

By Catherine

Written by Catherine Bolgar, in association with WSJ custom studios

 

Source: Hyperloop Transportation Technologies

Source: Hyperloop Transportation Technologies

Imagine traveling in capsules sucked through a tube using low air pressure and magnetic acceleration to achieve speeds of up to 760 miles (1,223 km) per hour. That’s the idea of the California Hyperloop, which could eventually cut the travel time between Los Angeles and San Francisco to a mere 30 minutes, compared with today’s one-hour flight or six-hour car journey.

As soon as next year, a full-scale test track will begin construction in Quay Valley, a proposed sustainable community located between California’s two major metropolises.

The Hyperloop is a system that not only makes sense because it’s cheaper to construct, but it’s also sustainable so it’s cheaper to run,” says Dirk Ahlborn, chief executive officer of Hyperloop Transportation Technologies, Inc. “It changes the world.”

Tesla founder Elon Musk first laid out his Hyperloop vision in 2013 and invited others to take up the challenge. Turning the idea into a full-scale model in just three years may seem fast, but, as Mr. Ahlborn points out, it took a decade to get to the moon—“a way more difficult task,” he says. “The Hyperloop technology sounds like science fiction but, in the end, everything we’re doing already exists. The Quay Valley track is necessary to find out how to optimize the technology.”

The Hyperloop concept is similar to the pneumatic tubes used by banks to carry cash and documents, except that the passenger capsules would be sucked through the tube by controlled propulsion. A capsule (with large doors for speedy boarding) would enter a tightly sealed exterior shell. The tubes would probably be constructed from steel—although other materials, including fiberglass, are being considered—and covered with solar panels to supply the system’s energy. Low air pressure—of around 100 Pascals—would reduce air resistance inside the tube, while magnetic levitation and an air cushion would allow the capsule to hover above the tube’s surface. The straight track would further aid speed. As on a flight, passengers would sense how fast they are moving only when the capsule accelerates, slows or turns.

 

Hyperloop. Source: Forbes

Hyperloop. Source: Forbes

The Quay Valley track will allow engineers to work out optimum capsule size and boarding procedures. Each capsule is currently expected to seat 28 passengers and depart every 30 seconds during peak times, allowing a full-size Hyperloop to transport some 3,360 passengers an hour.

The Hyperloop would be elevated on pylons, making it possible to place the route above existing infrastructure such as highways, while also simplifying the process of obtaining right of way and minimizing the environmental impact.

More importantly, the pylons would be flexible enough to withstand earthquakes, in the way that pylons built in the 1970s to carry Alaska’s oil pipeline have proved resilient to such shocks, Mr. Ahlborn notes. As an enclosed system, the Hyperloop would also be impervious to harsh weather.

Perhaps more revolutionary than the technology is the way the Hyperloop team itself works. As well as partnering with companies and universities, more than 300 experts from 21 countries have been brought onto the team, working remotely online. Although they don’t get paid—most hold day jobs as engineers—they do get company stock options. “They’re driven by passion,” says Mr. Ahlborn.

The Hyperloop is groundbreaking in a commercial sense, too. It is expected to cost $16 billion to build, versus $68 billion for a comparable California high-speed rail line. Ticket prices for the Los Angeles-San Francisco stretch, at $20- $30, would be far cheaper than flying, and even that business model is open to disruption. “Do we need tickets?” asks Mr. Ahlborn. “Or are there other ways in which we can generate enough income.” Maybe the Hyperloop could “make more money having more people ride and we can say it’s free. Or maybe it’s free at certain times, and at peak times it costs a bit,” he adds.

The Hyperloop turns conventional infrastructure on its head, from its technology to its crowdsourcing. “Usually these things are done behind closed doors in a boardroom. We’re trying to be open. We’re using the community to do everything,” Mr. Ahlborn says. The Hyperloop “is a first for a lot of things.”

For more from Catherine, contributors from the Economist Intelligence Unit along with industry experts, join the Future Realities discussion.

Small Solutions for the World’s Biggest Challenges

By Catherine

Nano molecule structureWritten by Catherine Bolgar*

Nanotechnology is one of the biggest trends for the future, bringing new materials and new understanding of the world at the smallest scale: that of molecules and atoms.

Ten or 15 years ago, nanotechnology was seen as hype,” or a passing trend, says Andrei Khlobystov, professor of nanomaterials and director of the Nottingham University’s Nanoscience and Nanotechnology Centre in the U.K. “But as time goes on, nanotechnology is becoming much more a part of our life. It doesn’t go away because there are still a lot of opportunities, still huge scope to contribute to economy and society.”

Nanotechnology can contribute solutions to help address the grand challenges in the world—energy , health care, sustainability —he says.

Carbon nanotubes, for example, conduct electricity better than most metals, offering a way to replace metals, such as gold, platinum and palladium, which are in increasingly short supply. Their electronic properties make them ideal for use in transistors, while their size—80,000 times smaller than a human hair—opens new opportunities for miniaturization. The sum of such properties holds promise for smaller, more powerful, faster computers.

Carbon nanotubes also are extremely strong—and already used for certain components in cars—but light in weight. And they’re made of cheap, plentiful carbon. You could almost make them from trees and grass, Prof. Khlobystov says.

“It’s never just one thing that nanomaterials offer; it’s always a whole set of different properties,” he says. “That’s what makes nanotechnology so exciting.”

Some of the biggest advances have been in medicine, with early diagnostics and other tools. Already, nanomedicine is being used for blood and breath analysis and to precisely measure the quantity of medicine in the blood in order to adjust the amount a patient needs to take.

Tumors might be detected more quickly, via blood tests. “It’s possible to use nanoparticles to make imaging technology much better, to image tumors,” says Dave H.A. Blank, scientific director of MESA+ Institute for Nanotechnology at the University of Twente in the Netherlands. “This is really growing fast.”

See Dave Blank’s fantastic TEDx Talk about nanotechnology:

YouTube Preview Image

A new approach includes a lab-on-a-chip that has tiny channels etched on it, so that 1/1000th of a drop of blood is enough to analyze.

“We can measure how the liver or heart responds to medicine,” he says. “The advantage is you can easily go through the body,” because of the small size.

In three or four years, a nanopill, containing a complete laboratory, could look for colon cancer. It would pump in material from the colon and could measure if there’s cancer, whether it’s at an early stage, and send information to a smart phone. The pill itself would be made of organic materials, and the electronic parts are silicon—which is just sand, Prof. Blank says, so there’s no damage to the body or the environment. “I expect that in five years there will be regulations that everyone take such a pill,” he adds.

An organ-on-a-chip is the next goal. “You take tissue from the lung, grow it and put it on the lab-on-a-chip or organ-on-a-chip,” Prof. Blank says. “You can look at oxygen behavior in the lung or blood in the liver or how the heart muscle responds to electric impulses. We can watch how cells communicate with each other.”

Nanotechnology also can make new materials. One of the most exciting is graphene, which is a two-dimensional substance made up of a single layer of carbon atoms. It’s flexible, durable and an excellent conductor of electricity.

Rubber bands coated with graphene could be used in medicine as cheap, flexible sensors. Graphene ribbons could act as semiconductors. Graphene and carbon nanotubes could lead to mobile phones so tiny and flexible they could be printed on clothing. Graphene oxide could reinforce concrete or be applied like paint to stop corrosion.

Why are we only now starting to discover so many new properties in something as common as carbon?

One reason is that matter at an atomic level has its own rules, which until recently were unknown to us. The discovery of atoms came from observations about them in large numbers, not as individuals. Advances in equipment—such as electron microscopy, scanning tunneling microscopy or atomic force microscopy—allowed researchers to see actual atoms, which are smaller than the wavelength of light .

Now we find that certain things may not be as we thought,” Prof. Khlobystov says. We once thought that a piece of gold was made of gold atoms and that all those atoms were the same. “They are the same if you look on the macroscopic level,” he says. “But as you start zooming in, you see that not all the atoms are the same. And there are defects, edges and faults.”

Beyond how atoms look is how they act on an individual level. “When you make things smaller, new physics and new properties kick in,” Prof. Khlobystov says.

The next challenge is to control chemical reactions between individual atoms, using carbon nanotubes as tiny test tubes. “They can produce new chemical products in a sustainable way and can produce entirely new materials,” he says.

*For more from Catherine, contributors from the Economist Intelligence Unit along with industry experts, join The Future Realities discussion.



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