Graphene is a proven supermaterial, but manufacturing the versatile form of carbon at usable scales remains a challenge

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Pure graphene is a uniform, single-atom-thick crystal of carbon arranged in a hexagonal pattern, as seen in this electron microscope image. M.H. Gass/Wikimedia Commons, CC BY

“Future chips may be 10 times faster, all thanks to graphene“; “Graphene may be used in COVID-19 detection“; and “Graphene allows batteries to charge 5x faster“—those are just a handful of recent dramatic headlines lauding the possibilities of graphene. Graphene is an incredibly light, strong and durable material made of a single layer of carbon atoms. With these properties, it is no wonder researchers have been studying ways that graphene could advance material science and technology for decades.

I never know what to expect when I tell people I study graphene—some have never heard of it, while others have seen some version of these headlines and inevitably ask, “So what’s the holdup?”

Graphene is a fascinating material, just as the sensational headlines suggest, but it is only just starting be used in real-world applications. The problem lies not in graphene’s properties, but in the fact that it is still incredibly difficult and expensive to manufacture at commercial scales.

What is graphene?

Graphene is most simply defined as a single layer of carbon atoms bonded together in a hexagonal, sheetlike structure. You can think of pure graphene as a one-layer-thick sheet of carbon tissue paper that happens to be the strongest material on Earth.

Graphene usually comes in the form of a powder made of small, individual sheets that are roughly the diameter of a grain of sand. An individual sheet of graphene is 200 times stronger than an equally thin piece of steel. Graphene is also extremely conductive, holds together at up to 1,300 degrees Fahrenheit (700 C), can withstand acids and is flexible and very lightweight.

Because of these properties, graphene could be extremely useful. The material can be used to create flexible electronics and to purify or desalinate water. And adding just 0.03 ounces (1 gram) of graphene to 11.5 pounds (5 kilograms) of cement increases the strength of the cement by 35%.

As of late 2022, Ford Motor Co., with which I worked as part of my doctoral research, is one of the the only companies to use graphene at industrial scales. Starting in 2018, Ford began making plastic for its vehicles that was 0.5% graphene—increasing the plastic’s strength by 20%.

How to make a supermaterial

Graphene is produced in two principal ways that can be described as either a top-down or bottom-up process.

The world’s first sheet of graphene was created in 2004 out of graphite. Graphite, commonly known as pencil lead, is composed of millions of graphene sheets stacked on top of one another. Top-down synthesis, also known as graphene exfoliation, works by peeling off the thinnest possible layers of carbon from graphite. Some of the earliest graphene sheets were made by using cellophane tape to peel off layers of carbon from a larger piece of graphite.

The problem is that the molecular forces holding graphene sheets together in graphite are very strong, and it’s hard to pull sheets apart. Because of this, graphene produced using top-down methods is often many layers thick, has holes or deformations, and can contain impurities. Factories can produce a few tons of mechanically or chemically exfoliated graphene per year, and for many applications—like mixing it into plastic—the lower-quality graphene works well.

Top-down, exfoliated graphene is far from perfect, and some applications do need that pristine single sheet of carbon.

Bottom-up synthesis builds the carbon sheets one atom at a time over a few hours. This process—called vapor deposition—allows researchers to produce high-quality graphene that is one atom thick and up to 30 inches across. This yields graphene with the best possible mechanical and electrical properties. The problem is that with a bottom-up synthesis, it can take hours to make even 0.00001 gram—not nearly fast enough for any large scale uses like in flexible touch-screen electronics or solar panels, for example.

So what’s the holdup?

Current production methods of graphene, both top-down and bottom-up, are expensive as well as energy and resource intensive, and simply produce too little product, too slowly.

Some companies do manufacture graphene and sell it for US$60,000 to $200,000 per ton. There are a limited number of uses that make sense at these .

While small amounts of top-down or bottom-up graphene can satisfy the needs of researchers, for companies even just the process of prototyping a , application or requires many pounds of graphene powder or hundreds of graphene sheets and a lot of time and effort. It took significant investment and more than four years of study, development and optimization before graphene hit the at Ford.

Current production can barely cover experimentation, much less widespread use.

Improving manufacturing

For a material that has been around since only 2004, a lot of progress has been made in scaling up the production and implementation of graphene.

There are hints that graphene is starting to break through at a commercial level. There are a huge number of graphene-related startups looking at a wide range of uses ranging from energy storage to composites to nerve stimulation. Major companies—such as Tesla, LG and chemical giant BASF—are also investigating how graphene could be used, in rechargeable batteries, flexible or wearable electronics and next-generation materials.

Graphene is ripe for a breakthrough that will bring down the cost and increase the scale of production, and this is an area of intense academic research. One new technique discovered in 2020, called flash joule heating, is especially promising. Researchers have shown that passing large amounts of electricity through any carbon source reorganizes the carbon-carbon bonds into a graphene structure. Using this process, it is possible to make many pounds of high-quality graphene for a relatively low cost out of any carbon-containing material like coal or even trash. A company called Universal Matter Inc. is already commercializing the process.

Once the cost of comes down, the commercial applications will follow. The appetite for graphene is huge, but it is going to take some time before this material lives up to its potential.

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Graphene is a proven supermaterial, but manufacturing the versatile form of carbon at usable scales remains a challenge (2022, November 29)
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Skateboarding continues to be subversive despite mainstream competitions such as the Olympics, researchers say

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Credit: Pixabay/CC0 Public Domain

Skateboarding continues to be unkempt, subversive and tacitly political despite inclusion in mainstream competitions like the Olympics, experts have said.

The “discordance” between skateboarding’s ethos and capitalism raises questions about its continued incorporation into , a new study says.

The also shows how in times of disaster, such as the coronavirus epidemic, skateboarding allows opportunities for play and supports people’s physical and mental health.

Academics observed skateboarders and spoke to those in the community. They found an “arrythmia” which meant skateboarding’s unkempt iconoclast status has largely been preserved despite the fact the sport is part of lucrative business models, institutionalized regimes, and attempts to “contain” it within skateparks.

Dr. Paul O’Connor, from the University of Exeter, who carried out the research with Dr. Brian Glenney, from Norwich University in Vermont said: “Even though it is now an Olympic sport and attracts multimillion dollar endorsements, skateboarding is still subversive and that’s what makes it so exciting.”

“Skateboarding is discordant with other rhythms and interacts when disruption and disaster occurs. It is a type of disaster leisure. Disruption is an intrinsic element of how people practice, and later understand skateboarding. We also find that there is something revolutionary in skateboarding, a latent political orientation that is tacit. It becomes evocative in bodily action, in bursts of energy exacted in urban space.”

The study, published in the journal Sport, Ethics and Philosophy, says this arrhythmic beat is caused by the way skaters move through cities prepared for interruption by pedestrians, vehicles and security guards.

The study is based on prior research on how following earthquakes in New Zealand, skateboarding thrived. New spots were created by ruptured roads, and access became possible to locations previously un-skateable as the parts of the city were closed and were directed towards more urgent concerns than skateboarders.

The approach fits with a growing dialogue on leisure in catastrophic and polluted times. The Coronavirus pandemic adversely impacted many sports, but skaters also took advantage of reduced pedestrian and security activity. The authors highlight that skateboarding is adaptive to disaster.

Dr. O’Connor said, “The early months of the pandemic coincided with a dearth in skateboarding equipment as many China made products could not be delivered to skate shops and retailers through the world. This became even more acute as the lockdown proceeded and individuals sought skateboards with increasing passion and interest.

“While skateboarding was always destined to be topical in 2020 with its debut as a sport in the Olympics, remarkably the canceling of the games was a further unpredicted boon to skateboarding as a sport and industry. The sport boomed in popularity during the pandemic just as slowness and slow sports with meditative and sensory qualities began to rise in popularity.

“Skateboarding, seldom framed as slow or quiet, thrived in the slow times and quiet places quarried by the pandemic. Many people picked up a skateboard for the first time recognizing the potential it held for play and exercise in small and informal spaces. Yet, efforts to limit and control skateboarders persisted with many public skateparks locked or made unusable with skatestoppers and dumped sand.”

More information:
Brian Glenney et al, Skateboarding as Discordant: A Rhythmanalysis of Disaster Leisure, Sport, Ethics and Philosophy (2022). DOI: 10.1080/17511321.2022.2139858

Skateboarding continues to be subversive despite mainstream competitions such as the Olympics, researchers say (2022, November 29)

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Astrophysicists hunt for second-closest supermassive black hole

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The ultra-faint Milky Way companion galaxy Leo I appears as a faint patch to the right of the bright star, Regulus. Credit: Scott Anttila Anttler

Two astrophysicists at the Harvard-Smithsonian Center for Astrophysics have suggested a way to observe what could be the second-closest supermassive black hole to Earth: a behemoth 3 million times the mass of the Sun, hosted by the dwarf galaxy Leo I.

The , labeled Leo I*, was first proposed by an independent team of astronomers in late 2021. The team noticed picking up speed as they approached the center of the galaxy—evidence for a black hole—but directly imaging emission from the black hole was not possible.

Now, CfA astrophysicists Fabio Pacucci and Avi Loeb suggest a new way to verify the supermassive black hole’s existence; their work is described in a study published today in the Astrophysical Journal Letters.

“Black holes are very elusive objects, and sometimes they enjoy playing hide-and-seek with us,” says Fabio Pacucci, lead author of the ApJ Letters study. “Rays of light cannot escape their event horizons, but the environment around them can be extremely bright—if enough material falls into their gravitational well. But if a black hole is not accreting , instead, it emits no light and becomes impossible to find with our telescopes.”

This is the challenge with Leo I—a dwarf galaxy so devoid of gas available to accrete that it is often described as a “fossil.” So, shall we relinquish any hope of observing it? Perhaps not, the astronomers say.

“In our study, we suggested that a small amount of mass lost from stars wandering around the black hole could provide the accretion rate needed to observe it,” Pacucci explains. “Old stars become very big and red—we call them . Red giants typically have that carry a fraction of their mass to the environment. The space around Leo I* seems to contain enough of these ancient stars to make it observable.”

“Observing Leo I* could be groundbreaking,” says Avi Loeb, the co-author of the study. “It would be the second-closest supermassive black hole after the one at the center of our galaxy, with a very similar mass but hosted by a galaxy that is a thousand times less massive than the Milky Way. This fact challenges everything we know about how galaxies and their central supermassive co-evolve. How did such an oversized baby end up being born from a slim parent?”

Decades of studies show that most massive galaxies host a supermassive black hole at their center, and the mass of the black hole is a tenth of a percent of the total mass of the spheroid of stars surrounding it.

“In the case of Leo I,” Loeb continues, “we would expect a much smaller black hole. Instead, Leo I appears to contain a black hole a few million times the mass of the Sun, similar to that hosted by the Milky Way. This is exciting because science usually advances the most when the unexpected happens.”

So, when can we expect an image of the black hole?

“We are not there yet,” Pacucci says.

The team has obtained telescope time on the -borne Chandra X-ray Observatory and the Very Large Array radio telescope in New Mexico and is currently analyzing the new data.

Pacucci says, “Leo I* is playing hide-and-seek, but it emits too much radiation to remain undetected for long.”

More information:
Accretion from Winds of RGB Stars May Reveal the Supermassive Black Hole in Leo I, The Astrophysical Journal Letters (2022). DOI: 10.3847/2041-8213/ac9b21

Astrophysicists hunt for second-closest supermassive black hole (2022, November 28)
retrieved 28 November 2022

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