From MIT News: “SMART discovers nondisruptive way to characterize the surface of nanoparticles”

MIT News

From MIT News

November 12, 2019
Singapore-MIT Alliance for Research and Technology

New method overcomes limitations of existing chemical procedures and may accelerate nanoengineering of materials.

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Schematic illustration of probe adsorption influenced by an attractive interaction within the corona.

Researchers from the Singapore-MIT Alliance for Research and Technology (SMART) have made a discovery that allows scientists to “look” at the surface density of dispersed nanoparticles. This technique enables researchers to understand the properties of nanoparticles without disturbing them, at a much lower cost and far more quickly than with existing methods.

The new process is explained in a paper entitled “Measuring the Accessible Surface Area within the Nanoparticle Corona using Molecular Probe Adsorption,” published in the academic journal Nano Letters. It was led by Michael Strano, co-lead principal investigator of the Disruptive and Sustainable Technologies for Agricultural Precision (DiSTAP) research group at SMART and the Carbon P. Dubbs Professor at MIT, and MIT graduate student Minkyung Park. DiSTAP is a part of SMART, MIT’s research enterprise in Singapore, and develops new technologies to enable Singapore, a city-state which is dependent upon imported food and produce, to improve its agriculture yield to reduce external dependencies.

The molecular probe adsorption (MPA) method is based on a noninvasive adsorption of a fluorescent probe on the surface of colloidal nanoparticles in an aqueous phase. Researchers are able to calculate the surface coverage of dispersants on the nanoparticle surface — which are used to make it stable at room temperature — by the physical interaction between the probe and nanoparticle surface.

“We can now characterize the surface of the nanoparticle through its adsorption of the fluorescent probe. This allows us to understand the surface of the nanoparticle without damaging it, which is, unfortunately, the case with chemical processes widely used today,” says Park. “This new method also uses machines that are readily available in labs today, opening up a new, easy method for the scientific community to develop nanoparticles that can help revolutionize different sectors and disciplines.”

The MPA method is also able to characterize a nanoparticle within minutes compared to several hours that the best chemical methods require today. Because it uses only fluorescent light, it is also substantially cheaper.

DiSTAP has started to use this method for nanoparticle sensors in plants and nanocarriers for delivery of molecular cargo into plants.

“We are already using the new MPA method within DiSTAP to aid us in creating sensors and nanocarriers for plants,” says Strano. “It has enabled us to discover and optimize more sensitive sensors and understand the surface chemistry, which in turn allows for greater precision when monitoring plants. With higher-quality data and insight into plant biochemistry, we can ultimately provide optimal nutrient levels or beneficial hormones for healthier plants and higher yields.”

See the full article here .


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The mission of MIT is to advance knowledge and educate students in science, technology, and other areas of scholarship that will best serve the nation and the world in the twenty-first century. We seek to develop in each member of the MIT community the ability and passion to work wisely, creatively, and effectively for the betterment of humankind.

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#smart-discovers-nondisruptive-way-to-characterize-the-surface-of-nanoparticles, #agriculture, #applied-research-technology, #chemical-engineering, #mit, #nanotechnology

From UCLA and From Arizona State University via Science Alert: “Engineers Create Tiny ‘Artificial Sunflowers’ That Bend Towards The Light”

UCLA bloc

From UCLA

and

ASU Bloc

From Arizona State University

via

ScienceAlert

Science Alert

6 NOV 2019
MIKE MCRAE

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(Qian et al., Nature Nanotechnology, 2019)

When it comes to squeezing maximum amounts of energy out of the daylight hours, plants have a head start thanks to evolution.

Now, engineers have designed solar panels that mimic the sunflower’s sun-chasing talent, through clever use of nanotechnology.

By moulding temperature-sensitive materials into thin, supportive structures, scientists have come up with tiny ‘stems’ that bend towards a bright light source, providing a moving platform that could dramatically improve the efficiency of a range of solar technologies.

Researchers from the University of California Los Angeles and Arizona State University refer to their system as a sunflower-like biomimetic omnidirectional tracker. Or ‘SunBOT’, if you like your acronyms.

In biological terms, any general movement in response to specific changes in the environment is described as a nastic behaviour. Flowers that open at dawn and close at dusk are a good example of this.

Chemists have had little trouble making synthetic nastic materials [International Journal of Smart and Nano Materials] and structures that open and close, or bend and twist in response to changes in light intensity or fluctuating temperatures.

But nature has another, slightly more complicated behaviour that directs the movements of organisms towards good things and away from threats.

These tropic behaviours are what we see when sunflowers tilt their flowers to face the Sun, warming their reproductive bits [Science ABC] in order to attract pollinators.

Sun-chasing actions, or heliotropism, would be mighty handy for things like photovoltaics, which are most efficient when bathed in a dense glow of radiation hitting their surface straight-on, rather than from a more shallow angle.

In practical terms, compared to rays from an overhead illumination source, light coming in at an angle of around 75 degrees carries as much as 75 percent less energy.

To solve this problem of oblique-incidence energy-density loss, the research team looked to gels and polymers that respond predictably to light or heat.

A handful of different materials were selected as candidates worth closer investigation, including a hydrogel containing gold nanoparticles, a tangle of light-sensitive polymers, and a type of liquid crystalline elastomer embedded with a light-absorbing dye.

Each arrangement was shaped into a millimetre-wide thread several centimetres in length. When targeted by a laser, the tiny artificial stalks responded rapidly to the light’s warmth, shrinking on one side and expanding on the other to cause the thread to kink and lean towards the laser.

To put their synthetic sunflowers to the test, the researchers assembled an array of SunBOTs and submerged them in water, letting them sit right at the water-air boundary.

To detect the harvesting capabilities of their invention, the team then determined how much light was converted to heat by measuring the water vapour their setup generated.

Changes in the amount of vapour indicated that the SunBOTs were up to four times better at harvesting energy at steep angles than a boring old flat, static surface.

By demonstrating that a variety of materials could serve as a synthetic tropic material, the researchers argue their devices could potentially be a solution for just about any system that experiences a loss of efficiency due to a moving energy source.

For example, lawns of these miniature sun-worshippers could theoretically be used to tilt just about any solar process towards the light, from itty-bitty solar cells to evaporation devices that can purify water.

According to the SunBOTs’ designers, the sky (if not beyond!) seems to be the limit for this kind of technology.

“This work may be useful for enhanced solar harvesters, adaptive signal receivers, smart windows, self-contained robotics, solar sails for spaceships, guided surgery, self-regulating optical devices, and intelligent energy generation (for example, solar cells and biofuels), as well as energetic emission detection and tracking with telescopes, radars and hydrophones,” they write in their report.

Even if just a handful of those predictions eventuates into real-world use, the future of synthetic tropic materials is certainly looking brighter.

This research was published in Nature Nanotechnology.

See the full article here .

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ASU is the largest public university by enrollment in the United States. Founded in 1885 as the Territorial Normal School at Tempe, the school underwent a series of changes in name and curriculum. In 1945 it was placed under control of the Arizona Board of Regents and was renamed Arizona State College. A 1958 statewide ballot measure gave the university its present name.
ASU is classified as a research university with very high research activity (RU/VH) by the Carnegie Classification of Institutions of Higher Education, one of 78 U.S. public universities with that designation. Since 2005 ASU has been ranked among the Top 50 research universities, public and private, in the U.S. based on research output, innovation, development, research expenditures, number of awarded.

UC LA Campus

For nearly 100 years, UCLA has been a pioneer, persevering through impossibility, turning the futile into the attainable.

We doubt the critics, reject the status quo and see opportunity in dissatisfaction. Our campus, faculty and students are driven by optimism. It is not naïve; it is essential. And it has fueled every accomplishment, allowing us to redefine what’s possible, time after time.

This can-do perspective has brought us 12 Nobel Prizes, 12 Rhodes Scholarships, more NCAA titles than any university and more Olympic medals than most nations. Our faculty and alumni helped create the Internet and pioneered reverse osmosis. And more than 100 companies have been created based on technology developed at UCLA.

#engineers-create-tiny-artificial-sunflowers-that-bend-towards-the-light, #applied-research-technology, #asu, #heliotropism, #nanotechnology, #science-alert, #sunbots, #the-research-team-looked-to-gels-and-polymers-that-respond-predictably-to-light-or-heat, #ucla

From JHU HUB: “Copper could help unlock the clean-energy potential of hydrogen fuel cells”

Johns Hopkins

From JHU HUB

11.1.19
Lisa Ercolano
Matthew Chin

Hydrogen fuel cells may someday power automobiles and trucks, offering a source of energy that’s free of carbon emissions and pollutants. But their potential has been limited thus far by the high cost and instability of the platinum-nickel catalyst needed to spark the chemical reaction that produces clean electricity.

Using experiments and computer simulations, materials scientists from Johns Hopkins University and the University of California, Los Angeles have taken a major leap toward making that future possible. Their study, published in Matter, sheds new light on a method of stabilizing catalysts by adding copper and provides details on why the method works.

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Copper in the Periodic Table

The UCLA team was led by Yu Huang, a professor of materials science and engineering. The Hopkins team was led by Tim Mueller, assistant professor of materials science and engineering.

“The problem is that platinum-nickel catalysts, which are very promising for use in fuel cells, degrade over time as the nickel dissolves,” explains Mueller, whose research focuses on developing and applying computational methods to allow researchers to understand the real-world behavior of materials and to develop new materials for advanced technologies. “Professor Huang’s group discovered that adding copper to the catalysts helped reduce the amount of nickel dissolution, and our group helped them figure out why, which is important for people who want to build on this research.”

In experiments, the UCLA researchers found that introducing copper atoms into specially shaped nanoparticles of platinum-nickel resulted in durability that proved to be 40% better, in terms of catalyst efficiency, than those without copper. These new catalysts were very stable—that is, more transition metals were retained in the platinum-nickel-copper particles, despite the corrosive condition that could leach them out. They were also more efficient in catalyzing the chemical reaction, compared to alloys of platinum-nickel and commercially used platinum-carbon.

To figure out why this was happening, Mueller’s team at Hopkins devised a model based on experimental data and performed computer simulations that revealed how individual atoms moved around the nanoparticles in the type of environment that the catalysts would encounter in a fuel cell.

“We ran simulations of the particles, both with and without copper, to see how the addition of copper affected the degradation of the particles,” said Liang Cao, a Johns Hopkins postdoctoral scholar of materials science and engineering, and a co-lead author of the study. “We were able to track the particles’ evolution on an atomic scale, and our simulations indicated that the particles that contained copper were more stable because they initially had more platinum on the surface, which protected the nickel and copper atoms from dissolving.”

According to Huang, the new study is a milestone in understanding the “atomistic structure-function relations in nanoscale materials and opens the door to new design strategies for high-performing nanoscale catalysts.”

See the full article here .


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About the Hub
We’ve been doing some thinking — quite a bit, actually — about all the things that go on at Johns Hopkins. Discovering the glue that holds the universe together, for example. Or unraveling the mysteries of Alzheimer’s disease. Or studying butterflies in flight to fine-tune the construction of aerial surveillance robots. Heady stuff, and a lot of it.

In fact, Johns Hopkins does so much, in so many places, that it’s hard to wrap your brain around it all. It’s too big, too disparate, too far-flung.

We created the Hub to be the news center for all this diverse, decentralized activity, a place where you can see what’s new, what’s important, what Johns Hopkins is up to that’s worth sharing. It’s where smart people (like you) can learn about all the smart stuff going on here.

At the Hub, you might read about cutting-edge cancer research or deep-trench diving vehicles or bionic arms. About the psychology of hoarders or the delicate work of restoring ancient manuscripts or the mad motor-skills brilliance of a guy who can solve a Rubik’s Cube in under eight seconds.

There’s no telling what you’ll find here because there’s no way of knowing what Johns Hopkins will do next. But when it happens, this is where you’ll find it.

Johns Hopkins Campus
The Johns Hopkins University opened in 1876, with the inauguration of its first president, Daniel Coit Gilman. “What are we aiming at?” Gilman asked in his installation address. “The encouragement of research … and the advancement of individual scholars, who by their excellence will advance the sciences they pursue, and the society where they dwell.”

The mission laid out by Gilman remains the university’s mission today, summed up in a simple but powerful restatement of Gilman’s own words: “Knowledge for the world.”

What Gilman created was a research university, dedicated to advancing both students’ knowledge and the state of human knowledge through research and scholarship. Gilman believed that teaching and research are interdependent, that success in one depends on success in the other. A modern university, he believed, must do both well. The realization of Gilman’s philosophy at Johns Hopkins, and at other institutions that later attracted Johns Hopkins-trained scholars, revolutionized higher education in America, leading to the research university system as it exists today.

#copper-could-help-unlock-the-clean-energy-potential-of-hydrogen-fuel-cells, #applied-research-technology, #catalysis, #chemistry, #jhu-hub, #material-sciences-2, #nanotechnology

From Sandia Lab: “Advanced microscopy reveals unusual DNA structure”

From Sandia Lab

October 30, 2019
Melissae Fellet
mfellet@sandia.gov
505-845-7478

Sandia scientist pushes technology’s limits to see fundamental feature of stretched S-DNA.

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Adam Backer, an optical scientist at Sandia National Laboratories, helped develop an advanced microscopy technique that revealed highly tilted base pairs in a stretched form of DNA. (Photo by Randy Montoya).

An advanced imaging technique reveals new structural details of S-DNA, ladder-like DNA that forms when the molecule experiences extreme tension. This work conducted at Sandia National Laboratories and Vrije University in the Netherlands provides the first experimental evidence that S-DNA contains highly tilted base pairs.

The predictable pairing and stacking of the DNA base pairs help to define the molecule’s double-helical shape. Understanding how the base pairs realign when DNA is stretched might provide insight into a range of biological processes and improve the design and performance of nanodevices built with DNA. Tilted base pairs in stretched S-DNA have been previously predicted using computer simulations, but never conclusively demonstrated in experiments until now, according to a recent article in Science Advances.

DNA is most commonly known as the molecular carrier of genetic information. However, in research labs around the world, it also has another use: construction material for nanoscale devices. To do this, scientists prepare computer-generated sequences of single-stranded DNA so that certain sections form base pairs with other sections. This forces the strand to bend and fold like origami. Researchers have used this principle to fold DNA into microscopic smiley faces, nanomachines with moving hinges and pistons and “smart” materials that spontaneously adjust to changes in the surrounding chemical environment.

“To build an airplane or a bridge, it’s important to know the structure, strength and stretchiness of every material that went into it,” said Adam Backer, an optical scientist at Sandia and lead author of the study. “The same thing is true when designing nanostructures with DNA.”

While much is known about the mechanical properties of DNA’s double helix, mysteries remain about the details of its shape when the molecule is stretched in a laboratory to form the ladder-like structure of S-DNA. Standard ways of visualizing DNA structure cannot track structural changes while the molecule untwists.

Seeing stretched DNA

To characterize the structure and stretchiness of S-DNA, Backer worked with colleagues in the Physics of Living Systems research group at LaserLaB Amsterdam at Vrije University. The researchers described their process in the journal article. Using instrumentation developed by his colleagues, Backer first attached a microscopic bead to each end of a short piece of viral DNA. These beads served as handles to manipulate a single molecule of DNA.

Next, the researchers trapped the beaded DNA in a narrow fluid-filled chamber using two tightly focused laser beams. Because the beads stay trapped inside the laser beams, the researchers could move the beads in the chamber by redirecting the laser beams. This enabled them to stretch the attached DNA to form S-DNA. This technique for manipulating microscopic particles, called optical tweezers, also provided precise control over the amount of stretching force applied to a single DNA molecule.

However, the structural changes occurring within the stretched DNA molecule were too small to be directly observed with a standard optical microscope. To address this challenge, Backer helped his colleagues combine an imaging method called fluorescence polarization microscopy with the optical tweezers instrument. First, they added small, rod-like fluorescent dye molecules to the solution containing optically trapped DNA. In unstretched DNA, the dye molecules sandwich themselves between neighboring sets of base pairs and align perpendicular to the central axis of the double helix. If a stretching force causes the DNA base pairs to tilt, the dyes would also tilt.

Next, the researchers used the fluorescent signals from the dyes to determine if the base pairs in stretched DNA tilted. The fluorescent dyes emit green fluorescent light when they interact with light waves from a laser beam pointing along the same axis as the dye molecules. The researchers changed the orientation of the light waves by rotating the polarization of a laser beam through various angles. Then, they stretched the DNA and watched for green fluorescent signals to appear under the microscope. From these measurements, and computational analysis methods developed at Sandia, the researchers determined that the dyes, and thus the base pairs, aligned at a 54-degree angle relative to the DNA’s central axis.

“This experiment provides the most direct evidence to date supporting the hypothesis that S-DNA contains tilted base pairs,” said Backer. “To gain this fundamentally new understanding of DNA, it was necessary to combine a number of cutting-edge technologies and bring scientists from a range of different technical disciplines together to work toward a common goal.”

There is widespread speculation among scientists that structures resembling S-DNA may form during the daily activities of human cells, but, at present, the biological purpose of S-DNA is still unknown. S-DNA might facilitate the repair of damaged or broken DNA, helping to guard against cell death and cancer. Backer hopes this clearer understanding of the physical principles governing DNA deformation will guide further research into the role of S-DNA in cells.

When Backer joined Sandia as a Truman Fellow in November 2016, he had the opportunity to start an independent research program of his own design. He had developed a method for polarization microscopy during graduate school at Stanford University and thought the technique had potential. Said Backer: “At Sandia I wanted to push this technique as far as it could go. The fact that this work has led to results with potential relevance to fields such as biology and nanotechnology has been extraordinary.”

See the full article here .


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Sandia Campus
Sandia National Laboratory

Sandia National Laboratories is a multiprogram laboratory operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy’s National Nuclear Security Administration. With main facilities in Albuquerque, N.M., and Livermore, Calif., Sandia has major R&D responsibilities in national security, energy and environmental technologies, and economic competitiveness.
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#applied-research-technology, #biology, #microscopy, #nanotechnology, #sandia-lab, #stretched-s-dna

From UC Riverside: “Small magnets reveal big secrets”

UC Riverside bloc

From UC Riverside

October 24, 2019
Iqbal Pittalwala

Work by international research team could have wide-ranging impact on information technology applications.

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An international research team led by a physicist at the University of California, Riverside, has identified a microscopic process of electron spin dynamics in nanoparticles that could impact the design of applications in medicine, quantum computation, and spintronics.

Magnetic nanoparticles and nanodevices have several applications in medicine — such as drug delivery and MRI — and information technology. Controlling spin dynamics — the movement of electron spins — is key to improving the performance of such nanomagnet-based applications.

“This work advances our understanding of spin dynamics in nanomagnets,” said Igor Barsukov, an assistant professor in the Department of Physics and Astronomy and lead author of the study that appears today in Science Advances.

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Physicist Igor Barsukov is an assistant professor at UC Riverside. (UCR/Barsukov lab)

Electron spins, which precess like spinning tops, are linked to each other. When one spin begins to precess, the precession propagates to neighboring spins, which sets a wave going. Spin waves, which are thus collective excitations of spins, behave differently in nanoscale magnets than they do in large or extended magnets. In nanomagnets, the spin waves are confined by the size of the magnet, typically around 50 nanometers, and therefore present unusual phenomena.

In particular, one spin wave can transform into another through a process called “three magnon scattering,” a magnon being a quantum unit of a spin wave. In nanomagnets, this process is resonantly enhanced, meaning it is amplified for specific magnetic fields.

In collaboration with researchers at UC Irvine and Western Digital in San Jose, as well as theory colleagues in Ukraine and Chile, Barsukov demonstrated how three magnon scattering, and thus the dimensions of nanomagnets, determines how these magnets respond to spin currents. This development could lead to paradigm-shifting advancements.

“Spintronics is leading the way for faster and energy-efficient information technology,” Barsukov said. “For such technology, nanomagnets are the building blocks, which need to be controlled by spin currents.”

Barsukov explained that despite its technological importance, a fundamental understanding of energy dissipation in nanomagnets has been elusive. The research team’s work provides insights into the principles of energy dissipation in nanomagnets and could enable engineers who work on spintronics and information technology to build better devices.

“Microscopic processes explored in our study may also be of significance in the context of quantum computation where researchers currently are attempting to address individual magnons,” Barsukov said. “Our work can potentially impact multiple areas of research.”

Barsukov was joined in the research by H. K. Lee, A. A. Jara, Y.-J. Chen, A. M. Gonçalves, C. Sha, and I. N. Krivorotov of UC Irvine; J. A. Katine of Western Digital in San Jose; R. E. Arias of the University of Chile in Santiago; and B. A. Ivanov of the National Academy of Sciences of Ukraine and the National University of Science and Technology in Russia.

The collaborative study was primarily funded by the U.S. Army Research Office, Defense Threat Reduction Agency, and National Science Foundation, or NSF, as well as by agencies in Chile, Brazil, Ukraine, and Russia. Barsukov was funded by the NSF.

See the full article here .

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UC Riverside Campus

The University of California, Riverside is one of 10 universities within the prestigious University of California system, and the only UC located in Inland Southern California.

Widely recognized as one of the most ethnically diverse research universities in the nation, UCR’s current enrollment is more than 21,000 students, with a goal of 25,000 students by 2020. The campus is in the midst of a tremendous growth spurt with new and remodeled facilities coming on-line on a regular basis.

We are located approximately 50 miles east of downtown Los Angeles. UCR is also within easy driving distance of dozens of major cultural and recreational sites, as well as desert, mountain and coastal destinations.

#applied-research-technology, #controlling-spin-dynamics-the-movement-of-electron-spins-is-key-to-improving-the-performance-of-nanomagnet-based-applications, #magnet-technology, #medicine, #nanotechnology, #quantum-computing, #spintronics, #uc-riverside

From MIT News: “MIT engineers develop a new way to remove carbon dioxide from air”

MIT News

From MIT News

October 24, 2019
David Chandler

The process could work on the gas at any concentrations, from power plant emissions to open air.

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In this diagram of the new system, air entering from top right passes to one of two chambers (the gray rectangular structures) containing battery electrodes that attract the carbon dioxide. Then the airflow is switched to the other chamber, while the accumulated carbon dioxide in the first chamber is flushed into a separate storage tank (at right). These alternating flows allow for continuous operation of the two-step process. Image courtesy of the researchers.

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A flow of air or flue gas (blue) containing carbon dioxide (red) enters the system from the left. As it passes between the thin battery electrode plates, carbon dioxide attaches to the charged plates while the cleaned airstream passes on through and exits at right. Image courtesy of the researchers.

A new way of removing carbon dioxide from a stream of air could provide a significant tool in the battle against climate change. The new system can work on the gas at virtually any concentration level, even down to the roughly 400 parts per million currently found in the atmosphere.

Most methods of removing carbon dioxide from a stream of gas require higher concentrations, such as those found in the flue emissions from fossil fuel-based power plants. A few variations have been developed that can work with the low concentrations found in air, but the new method is significantly less energy-intensive and expensive, the researchers say.

The technique, based on passing air through a stack of charged electrochemical plates, is described in a new paper in the journal Energy and Environmental Science, by MIT postdoc Sahag Voskian, who developed the work during his PhD, and T. Alan Hatton, the Ralph Landau Professor of Chemical Engineering.

The device is essentially a large, specialized battery that absorbs carbon dioxide from the air (or other gas stream) passing over its electrodes as it is being charged up, and then releases the gas as it is being discharged. In operation, the device would simply alternate between charging and discharging, with fresh air or feed gas being blown through the system during the charging cycle, and then the pure, concentrated carbon dioxide being blown out during the discharging.

As the battery charges, an electrochemical reaction takes place at the surface of each of a stack of electrodes. These are coated with a compound called polyanthraquinone, which is composited with carbon nanotubes. The electrodes have a natural affinity for carbon dioxide and readily react with its molecules in the airstream or feed gas, even when it is present at very low concentrations. The reverse reaction takes place when the battery is discharged — during which the device can provide part of the power needed for the whole system — and in the process ejects a stream of pure carbon dioxide. The whole system operates at room temperature and normal air pressure.

“The greatest advantage of this technology over most other carbon capture or carbon absorbing technologies is the binary nature of the adsorbent’s affinity to carbon dioxide,” explains Voskian. In other words, the electrode material, by its nature, “has either a high affinity or no affinity whatsoever,” depending on the battery’s state of charging or discharging. Other reactions used for carbon capture require intermediate chemical processing steps or the input of significant energy such as heat, or pressure differences.

“This binary affinity allows capture of carbon dioxide from any concentration, including 400 parts per million, and allows its release into any carrier stream, including 100 percent CO2,” Voskian says. That is, as any gas flows through the stack of these flat electrochemical cells, during the release step the captured carbon dioxide will be carried along with it. For example, if the desired end-product is pure carbon dioxide to be used in the carbonation of beverages, then a stream of the pure gas can be blown through the plates. The captured gas is then released from the plates and joins the stream.

In some soft-drink bottling plants, fossil fuel is burned to generate the carbon dioxide needed to give the drinks their fizz. Similarly, some farmers burn natural gas to produce carbon dioxide to feed their plants in greenhouses. The new system could eliminate that need for fossil fuels in these applications, and in the process actually be taking the greenhouse gas right out of the air, Voskian says. Alternatively, the pure carbon dioxide stream could be compressed and injected underground for long-term disposal, or even made into fuel through a series of chemical and electrochemical processes.

The process this system uses for capturing and releasing carbon dioxide “is revolutionary” he says. “All of this is at ambient conditions — there’s no need for thermal, pressure, or chemical input. It’s just these very thin sheets, with both surfaces active, that can be stacked in a box and connected to a source of electricity.”

“In my laboratories, we have been striving to develop new technologies to tackle a range of environmental issues that avoid the need for thermal energy sources, changes in system pressure, or addition of chemicals to complete the separation and release cycles,” Hatton says. “This carbon dioxide capture technology is a clear demonstration of the power of electrochemical approaches that require only small swings in voltage to drive the separations.”​

In a working plant — for example, in a power plant where exhaust gas is being produced continuously — two sets of such stacks of the electrochemical cells could be set up side by side to operate in parallel, with flue gas being directed first at one set for carbon capture, then diverted to the second set while the first set goes into its discharge cycle. By alternating back and forth, the system could always be both capturing and discharging the gas. In the lab, the team has proven the system can withstand at least 7,000 charging-discharging cycles, with a 30 percent loss in efficiency over that time. The researchers estimate that they can readily improve that to 20,000 to 50,000 cycles.

The electrodes themselves can be manufactured by standard chemical processing methods. While today this is done in a laboratory setting, it can be adapted so that ultimately they could be made in large quantities through a roll-to-roll manufacturing process similar to a newspaper printing press, Voskian says. “We have developed very cost-effective techniques,” he says, estimating that it could be produced for something like tens of dollars per square meter of electrode.

Compared to other existing carbon capture technologies, this system is quite energy efficient, using about one gigajoule of energy per ton of carbon dioxide captured, consistently. Other existing methods have energy consumption which vary between 1 to 10 gigajoules per ton, depending on the inlet carbon dioxide concentration, Voskian says.

The researchers have set up a company called Verdox to commercialize the process, and hope to develop a pilot-scale plant within the next few years, he says. And the system is very easy to scale up, he says: “If you want more capacity, you just need to make more electrodes.”

See the full article here .


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Please help promote STEM in your local schools.


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MIT Seal

The mission of MIT is to advance knowledge and educate students in science, technology, and other areas of scholarship that will best serve the nation and the world in the twenty-first century. We seek to develop in each member of the MIT community the ability and passion to work wisely, creatively, and effectively for the betterment of humankind.

MIT Campus

#mit-engineers-develop-a-new-way-to-remove-carbon-dioxide-from-air, #applied-research-technology, #chemistry, #mit, #nanotechnology

From Lawrence Berkeley National Lab: “Living on the Edge: How a 2D Material Got Its Shape”

Berkeley Logo

From Lawrence Berkeley National Lab

October 24, 2019
Theresa Duque
tnduque@lbl.gov
(510) 495-2418

Scientists at Berkeley Lab discover that nanoparticles’ ‘edge energy’ gets them in 2D shape for energy storage applications.

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Illustration of a 3D cobalt-oxide nanoparticle growing into a 2D nanosheet. (Credit: Haimei Zheng/Berkeley Lab)

Ever since its discovery in 2004, graphene – an atomically thin material with amazing strength and electrical properties – has inspired scientists around the world to design new 2D materials to serve a broad range of applications, from renewable energy and catalysts to microelectronics.

While 2D structures form naturally in materials like graphene, some scientists have sought to make 2D materials from semiconductors called transition metal oxides: compounds composed of oxygen atoms bound to a transition metal such as cobalt. But while scientists have long known how to make nanoparticles of transition metal oxides, no one has found a controllable way to grow these 3D nanoparticles into nanosheets, which are thin 2D materials just a few atoms thick.

Now, a team of scientists led by the Department of Energy’s Lawrence Berkeley National Laboratory (Berkeley Lab) has gained valuable insight into 3D transition metal oxide nanoparticles’ natural “edge” for 2D growth. Their findings were reported in Nature Materials.

Using a liquid-phase transmission electron microscope (TEM) at Berkeley Lab’s Molecular Foundry for the experiments, co-corresponding author Haimei Zheng and her team directly observed the dynamic growth of cobalt-oxide nanoparticles in a solution, and their subsequent transformation into a flat 2D nanosheet.

“Such a 3D to 2D transformation is much like the white of an egg spreading as it fries in a pan,” said Zheng, a senior staff scientist in Berkeley Lab’s Materials Sciences Division who led the study.


VIDEO: Cobalt-oxide nanoparticles in a solution transform into flat 2D nanosheets; video plays 15 times faster than real time. 3D to 2D growth observed using liquid-phase transmission electron microscopy at Berkeley Lab’s Molecular Foundry. (Credit: Haimei Zheng/Berkeley Lab)

In previous studies, scientists had assumed that only two major factors – bulk energy from the volume of the nanoparticles, and the nanoparticles’ surface energy – would drive the nanoparticles’ growth into a 3D shape, Zheng explained.

New energy comes to light

But calculations led by co-corresponding author Lin-Wang Wang revealed another energy that had been previously overlooked – edge energy. In a faceted, rectangular nanoparticle such as a transition metal oxide nanoparticle, the edge of a facet also contributes energy – in this case, positive energy – toward the nanoparticle’s growth and shape. But in order for a transition metal oxide nanoparticle to grow into a 2D nanosheet, the surface energy must be negative.

“And it’s the balance between these two energies, one negative and one positive, which determines the shape change,” Wang said. For smaller nanoparticles, positive edge energy wins, which leads to a compact 3D shape. But when the cobalt oxide nanoparticles grow larger, they ultimately reach a critical point where negative surface energy wins, resulting in a 2D nanosheet, he explained. Wang, a senior staff scientist in Berkeley Lab’s Materials Sciences Division, performed the calculations for the study on supercomputers at Berkeley Lab’s National Energy Research Scientific Computing Center (NERSC).

Uncovering these growth pathways, including the 3D-to-2D transition, Zheng added, provides new opportunities for the streamlined design of exotic new materials from compounds whose irregular atomic structures, such as transition metal oxides, are more challenging than graphene to synthesize into multilayered 2D devices.

3
Schematic illustrating the growth of 3D nanoparticles from a solution, and the 3D nanoparticles transformation into 2D nanosheets. (Credit: Haimei Zheng/Berkeley Lab)

Zheng and her team concluded that the study could not have been possible with a conventional electron microscope. By using liquid-phase TEM at the Molecular Foundry, the researchers were able to study the growth of atomically thin materials in solution by encapsulating the liquid sample in a specially designed liquid cell. The cell prevented the sample from collapsing in the high vacuum of the electron microscope.

“It would be impossible to know such a growth path without this in situ observation,” said first author Juan Yang, who was a visiting doctoral researcher at Berkeley Lab from Dalian University of Technology of China at the time of the study. “This discovery may transform our future design of materials with surface-enhanced properties for catalysis and sensing applications of the future.”

Next steps

The researchers next plan to focus on using liquid-cell TEM to grow more complex 2D materials such as heterostructures, which are like sandwiches of layered materials with different properties.

“Like an architect who is inspired by the way in which an ancient giant redwood has grown, materials scientists are inspired to design ever more complex structures for energy storage,” said Zheng, who pioneered liquid-cell TEM at Berkeley Lab in 2009. “But why do they grow that way? Our strength at Berkeley Lab is that we can study them at the atomic level and watch them grow in real time and figure out the mechanisms that would contribute to the design of better materials.”

This work was supported by the DOE Office of Science’s Basic Energy Sciences program and included research at the Molecular Foundry and National Energy Research Scientific Computing Center, which are DOE Office of Science User Facilities.

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