Graphene Improves Oil Exploration

carbon-nanotube(Nanowerk News) Graphene holds potential for diverse applications, including battery materials, electrodes, high-speed electronics, water filtration, and solar energy harvesting. We’ve discussed most of those applications in earlier blog posts, and not a day passes without some progress in one of those directions hitting the world headlines. Little media attention, however, has been paid to a young and exciting application of graphene – oil exploration.
Most of the world’s growing energy demand is fulfilled from some form of fossil fuel, like coal and oil. It is well known that oil exploration and the energy sector are big business, but also potentially damaging to the environment. Oil spills and uncontrolled oil well explosions form just a part of the risk involved in oil exploration. Another cause for concern is the efficiency of extraction, and potential losses, or leaks of oil into the environment. Graphene is being explored for its use in various stages of the exploration and extraction process.
Much of the research on graphene for oil has come out of the lab of Prof. James Tour at Rice University. In their early work (published in 2012: “Graphene Oxide as a High-Performance Fluid-Loss-Control Additive in Water-Based Drilling Fluids”), the group first showed that adding platelets of graphene oxide to a common water-based drilling fluid decreased the losses of the fluid to the surrounding rock, as compared to a standard mixture of clays and polymers used in the drilling industry today.
Graphene platelet plugging a nanopore
Graphene platelet plugging a nanopore (from ACS Applied Materials and Interfaces 4, 222 (2012))
These fluids are pumped downhole as part of the process to keep drill bits clean and remove cuttings. With traditional clay-enhanced fluids, differential pressure forms a layer on the wellbore called a filter cake, which both keeps the oil from flowing out and drilling fluids from invading the tiny, oil-producing pores.
When the drill bit is removed and drilling fluid displaced, the formation oil forces remnants of the filter cake out of the pores as the well begins to produce. But sometimes the clay won’t budge, and the well’s productivity is reduced.
The Tour Group discovered that microscopic, pliable flakes of graphene can form a thinner, lighter filter cake (“Functionalized graphene oxide plays part in next-generation oil-well drilling fluids”). When they encounter a pore, the flakes fold in upon themselves and look something like starfish sucked into a hole. But when well pressure is relieved, the flakes are pushed back out by the oil. The thinner graphene layer budged much more easily than the the layer which would remain after a traditional clay-enhanced liquid was used. A drilling fluid with 2 percent functionalized graphene oxide formed a filter cake an average of 22 micrometers wide — substantially smaller than the 278-micrometer cake formed by traditional drilling fluids. GO blocked pores many times smaller than the flakes’ original diameter by folding.
Graphene can also be put to use for well logging. Well logging techniques provide data on the geological properties of reservoirs of interest to the oil and gas exploration industry. A commonly used logging technique uses wirelines to provide information about an oil or gas well. Wirelines are long wires with sensors attached to them, which are lowered into an exploration hole to provide information about the hole and its contents. An extension of wireline logging is logging-while-drilling, which relies on sensors at the end of the drill itself. Both methods utilize oil-based fluids for drilling and lubrication. Oil-based fluids, however, are not very good conductors of electricity, which is where graphene enters the scene. The group of Tour developed a solution that contains magnetic graphene nanoribbons (MGNRs). The MGNRs form part of a conductive coating in oil-based drilling fluids, improving the reliability of the information that is sent back up the hole by the sensors. Furthermore, the magnetic properties of the ribbons could also be exploited for using the ribbons themselves as advanced sensors. The Tour group filed a patent for this application.
Finally, since graphene nanoribbons can be made small enough to pass into tiny crevices of the rock which holds precious oil, some envision little graphene-based robots creeping through rocks, sending wireless data which contains information on oil location and concentration.
Source: By  Marko Spasenovic, Graphenea

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Quantum Dots from a Familiar Energy Source, Coal: Video

201306047919620The prospect of turning coal into fluorescent particles may sound too good to be true, but the possibility exists, thanks to scientists at Rice University.

The Rice lab of chemist James Tour found simple methods to reduce three kinds of coal into graphene quantum dots (GQDs), microscopic discs of atom-thick graphene oxide that could be used in medical imaging as well as sensing, electronic and photovoltaic applications.

Coal yields production of graphene quantum dots

Band gaps determine how a semiconducting material carries an electric current. In quantum dots, band gaps are responsible for their fluorescence and can be tuned by changing the dots’ size. The process by Tour and company allows a measure of control over their size, generally from 2 to 20 nanometers, depending on the source of the coal.


An illustration shows the nanostructure of bituminous coal before separation into graphene quantum dots. Courtesy of the Tour Group

There are many ways to make GQDs now, but most are expensive and produce very small quantities, Tour said. Though another Rice lab found a way last year to make GQDs from relatively cheap carbon fiber, coal promises greater quantities of GQDs made even cheaper in one chemical step, he said.

“We wanted to see what’s there in coal that might be interesting, so we put it through a very simple oxidation procedure,” Tour explained. That involved crushing the coal and bathing it in acid solutions to break the bonds that hold the tiny graphene domains together.

“You can’t just take a piece of graphene and easily chop it up this small,” he said.

Tour depended on the lab of Rice chemist and co-author Angel Martí to help characterize the product. It turned out different types of coal produced different types of dots. GQDs were derived from bituminous coalanthracite and coke, a byproduct of oil refining.

Graphene quantum dots

An electron microscope image shows the stacking layer structure of graphene quantum dots extracted from anthracite. The scale bar equals 100 nanometers. Courtesy of the Tour Group.

The coals were each sonicated in nitric and sulfuric acids and heated for 24 hours. Bituminous coal produced GQDs between 2 and 4 nanometers wide. Coke produced GQDs between 4 and 8 nanometers, and anthracite made stacked structures from 18 to 40 nanometers, with small round layers atop larger, thinner layers. (Just to see what would happen, the researchers treated graphite flakes with the same process and got mostly smaller graphite flakes.)

Tour said the dots are water-soluble, and early tests have shown them to be nontoxic. That offers the promise that GQDs may serve as effective antioxidants, he said.

Medical imaging could also benefit greatly, as the dots show robust performance as fluorescent agents.

“One of the problems with standard probes in fluorescent spectroscopy is that when you load them into a cell and hit them with high-powered lasers, you see them for a fraction of a second to upwards of a few seconds, and that’s it,” Martí said. “They’re still there, but they have been photo-bleached. They don’t fluoresce anymore.”

Testing in the Martí lab showed GQDs resist bleaching. After hours of excitation, Martí said, the photoluminescent response of the coal-sourced GQDs was barely affected.

Rice University chemist James Tour, left, and graduate student Ruquan Ye show the source and destination of graphene quantum dots extracted from coal in a process developed at Rice. Tour said the fluorescent particles can be drawn in bulk from coal in a one-step process. Photo by Jeff Fitlow

That could make them suitable for use in living organisms. “Because they’re so stable, they could theoretically make imaging more efficient,” he said.

A small change in the size of a quantum dot – as little as a fraction of a nanometer – changes its fluorescent wavelengths by a measurable factor, and that proved true for the coal-sourced GQDs, Martí said.

Low cost will also be a draw, according to Tour. “Graphite is $2,000 a ton for the best there is, from the U.K.,” he said. “Cheaper graphite is $800 a ton from China. And coal is $10 to $60 a ton.

“Coal is the cheapest material you can get for producing GQDs, and we found we can get a 20 percent yield. So this discovery can really change the quantum dot industry. It’s going to show the world that inside of coal are these very interesting structures that have real value.”

Co-authors of the work include graduate students Ruquan Ye, Changsheng Xiang, Zhiwei Peng, Kewei Huang, Zheng Yan, Nathan Cook, Errol Samuel, Chih-Chau Hwang, Gedeng Ruan, Gabriel Ceriotti and Abdul-Rahman Raji and postdoctoral research associate Jian Lin, all of Rice. Martí is an assistant professor of chemistry and bioengineering. Tour is the T.T. and W.F. Chao Chair in Chemistry as well as a professor of mechanical engineering and materials science and of computer science.

The Air Force Office of Scientific Research and the Office of Naval Research funded the work through their Multidisciplinary University Research Initiatives.

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ONE Box Girl Scout Cookies = $15 Billion (Converting Carbon Sources to Graphene)

mix-id328072.jpgRice University lab shows troop how any carbon source can become valuable graphene.
Scientists can make graphene out of just about anything with carbon — even Girl Scout cookies.

Graduate students in the Rice University lab of chemist James Tour proved it when they invited a troop of Houston Girl Scouts to their lab to show them how it’s done.


*** WOW! Team GNT KNEW we should have bought more Girl Scout Cookies in this year’s annual ‘cookie drive’!  – Cheers!

Rice Universitiy’s James Tour Creates “Graphene NanoRibbons” for ‘NG Tank Applications’ .. Even Food and Beverage Packaging

Rice University mix of graphene nanoribbons, polymer has potential for cars, soda, beer 

Nanotubes imagesHOUSTON – (Oct. 10, 2013) – A discovery at Rice University aims to make vehicles that run on compressed natural gas more practical. It might also prolong the shelf life of bottled beer and soda.

The Rice lab of chemist James Tour has enhanced a polymer material to make it far more impermeable to pressurized gas and far lighter than the metal in tanks now used to contain the gas.

The combination could be a boon for an auto industry under pressure to market consumer cars that use cheaper natural gas. It could also find a market in food and beverage packaging.

Tour and his colleagues at Rice and in Hungary, Slovenia and India reported their results this week in the online edition of the American Chemistry Society journal ACS Nano.

By adding modified, single-atom-thick graphene nanoribbons (GNRs) to thermoplastic polyurethane (TPU), the Rice lab made it 1,000 times harder for gas molecules to escape, Tour said. That’s due to the ribbons’ even dispersion through the material. Because gas molecules cannot penetrate GNRs, they are faced with a “tortuous path” to freedom, he said.

The researchers acknowledged that a solid, two-dimensional sheet of graphene might be the perfect barrier to gas, but the production of graphene in such bulk quantities is not yet practical, Tour said.

But graphene nanoribbons are already there. Tour’s breakthrough “unzipping” technique for turning multiwalled carbon nanotubes into GNRs, first revealed in Nature in 2009, has been licensed for industrial production. “These are being produced in bulk, which should also make containers cheaper,” he said.

The researchers led by Rice graduate student Changsheng Xiang produced thin films of the composite material by solution casting GNRs treated with hexadecane and TPU, a block copolymer of polyurethane that combines hard and soft materials. The tiny amount of treated GNRs accounted for no more than 0.5 percent of the composite’s weight. But the overlapping 200- to 300-nanometer-wide ribbons dispersed so well that they were nearly as effective as large-sheet graphene in containing gas molecules. The GNRs’ geometry makes them far better than graphene sheets for processing into composites, Tour said.

They tested GNR/TPU films by putting pressurized nitrogen on one side and a vacuum on the other side. For films with no GNRs, the pressure dropped to zero in about 100 seconds as nitrogen escaped into the vacuum chamber. With GNRs at 0.5 percent, the pressure didn’t budge over 1,000 seconds, and it dropped only slightly over more than 18 hours.

Stress and strain tests also found that the 0.5 percent ratio was optimal for enhancing the polymer’s strength.

“The idea is to increase the toughness of the tank and make it impermeable to gas,” Tour said. “This becomes increasingly important as automakers think about powering cars with natural gas. Metal tanks that can handle natural gas under pressure are often much heavier than the automakers would like.”

He said the material could help to solve long-standing problems in food packaging, too.

“Remember when you were a kid, you’d get a balloon and it would be wilted the next day? That’s because gas molecules go through rubber or plastic,” Tour said. “It took years for scientists to figure out how to make a plastic bottle for soda. Once, you couldn’t get a carbonated drink in anything but a glass bottle, until they figured out how to modify plastic to contain the carbon dioxide bubbles. And even now, bottled soda goes flat after a period of months.

“Beer has a bigger problem and, in some ways, it’s the reverse problem,” he said. “Oxygen molecules get in through plastic and make the beer go bad.” Bottles that are effectively impermeable could lead to brew that stays fresh on the shelf for far longer, Tour said.

Co-authors of the paper are Rice graduate students Daniel Hashim, Zheng Yan, Zhiwei Peng, Chih-Chau Hwang, Gedeng Ruan and Errol Samuel; Rice alumnus Paris Cox; Bostjan Genorio, a former postdoctoral researcher at Rice and now an assistant professor at the University of Ljubljana, Slovenia; Akos Kukovecz, an associate professor of chemistry, and Zóltan Kónya, a researcher, both at the University of Szeged, Hungary; Parambath Sudeep, a research scholar at Cochin University of Science and Technology, India; Rice senior faculty fellow Robert Vajtai; and Pulickel Ajayan, the Benjamin M. and Mary Greenwood Anderson Professor in Mechanical Engineering and Materials Science and of chemistry at Rice. Tour is the T.T. and W.F. Chao Chair in Chemistry as well as a professor of mechanical engineering and materials science and of computer science at Rice.

The Air Force Research Laboratory through the University Technology Corp., the Office of Naval Research MURI graphene program and the Air Force Office of Scientific Research MURI program supported the research.


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New advance could help soldiers, athletes, others rebound from traumatic brain injuries

October 17, 2012

New advance could help soldiers, athletes, others rebound from traumatic brain injuries







A potential new treatment for traumatic brain injury (TBI), which affects thousands of soldiers, auto accident victims, athletes and others each year, has shown promise in laboratory research, scientists are reporting. TBI can occur in individuals who experience a violent blow to the head that makes the brain collide with the inside of the skull, a gunshot injury or exposure to a nearby explosion. The report on TBI, which currently cannot be treated and may result in permanent brain damage or death, appears in the journal ACS Nano.

Thomas Kent, James Tour and colleagues explain that TBI disrupts the supply of oxygen-rich blood to the brain. With the brain so oxygen-needy—accounting for only 2 percent of a person’s weight, but claiming 20 percent of the body’s oxygen supply—even a mild injury, such as a concussion, can have serious consequences. Reduced blood flow and resuscitation result in a build-up of free-radicals, which can kill brain cells. Despite years of far-ranging efforts, no effective treatment has emerged for TBI. That’s why the scientists tried a new approach, based on nanoparticles so small that 1000 would fit across the width of a human hair. They describe development and successful laboratory tests of nanoparticles, called PEG-HCCs.

In laboratory rats, the nanoparticles acted like antioxidants, rapidly restoring blood flow to the brain following resuscitation after TBI. “This finding is of major importance for improving patient health under clinically relevant conditions during resuscitative care, and it has direct implications for the current [TBI] war-fighter victims in the Afghanistan and Middle East theaters,” they say. More information: “Antioxidant Carbon Particles Improve Cerebrovascular Dysfunction Following Traumatic Brain Injury”, ACS Nano, 2012, 6 (9), pp 8007–8014. DOI: 10.1021/nn302615f Abstract Injury to the neurovasculature is a feature of brain injury and must be addressed to maximize opportunity for improvement. Cerebrovascular dysfunction, manifested by reduction in cerebral blood flow (CBF), is a key factor that worsens outcome after traumatic brain injury (TBI), most notably under conditions of hypotension.

We report here that a new class of antioxidants, poly(ethylene glycol)-functionalized hydrophilic carbon clusters (PEG-HCCs), which are nontoxic carbon particles, rapidly restore CBF in a mild TBI/hypotension/resuscitation rat model when administered during resuscitation—a clinically relevant time point. Along with restoration of CBF, there is a concomitant normalization of superoxide and nitric oxide levels. Given the role of poor CBF in determining outcome, this finding is of major importance for improving patient health under clinically relevant conditions during resuscitative care, and it has direct implications for the current TBI/hypotension war-fighter victims in the Afghanistan and Middle East theaters. The results also have relevancy in other related acute circumstances such as stroke and organ transplantation. Journal reference: ACS Nano

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