From SLAC National Accelerator Lab: “Study shows a much cheaper catalyst can generate hydrogen in a commercial device”

From SLAC National Accelerator Lab

October 14, 2019
Glennda Chui
(650) 926-4897
glennda@slac.stanford.edu

Replacing today’s expensive catalysts could bring down the cost of producing the gas for fuel, fertilizer and clean energy storage.

Researchers at the Department of Energy’s SLAC National Accelerator Laboratory and Stanford University have shown for the first time that a cheap catalyst can split water and generate hydrogen gas for hours on end in the harsh environment of a commercial device.

The electrolyzer technology, which is based on a polymer electrolyte membrane (PEM), has potential for large-scale hydrogen production powered by renewable energy, but it has been held back in part by the high cost of the precious metal catalysts, like platinum and iridium, needed to boost the efficiency of the chemical reactions.

This study points the way toward a cheaper solution, the researchers reported today in Nature Nanotechnology.

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(Greg Stewart/SLAC National Accelerator Laboratory)

“Hydrogen gas is a massively important industrial chemical for making fuel and fertilizer, among other things,” said Thomas Jaramillo, director of the SUNCAT Center for Interface Science and Catalysis, who led the research team. “It’s also a clean, high-energy-content molecule that can be used in fuel cells or to store energy generated by variable power sources like solar and wind. But most of the hydrogen produced today is made with fossil fuels, adding to the level of CO2 in the atmosphere. We need a cost-effective way to produce it with clean energy.”

From pricey metal to cheap, abundant materials

There’s been extensive work over the years to develop alternatives to precious metal catalysts for PEM systems. Many have been shown to work in a laboratory setting, but Jaramillo said that to his knowledge this is the first to demonstrate high performance in a commercial electrolyzer. The device was manufactured by a PEM electrolysis research site and factory in Connecticut for Nel Hydrogen, the world’s oldest and biggest manufacturer of electrolyzer equipment.

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A commercial electrolyzer used in the experiments. Electrodes sprayed with catalyst powder are stacked inside the central metal plates and compressed with bolts and washers. Water flows in through a tube on the right, and hydrogen and oxygen gases flow out through tubes at left. (Nel Hydrogen)

Electrolysis works much like a battery in reverse: Rather than generating electricity, it uses electrical current to split water into hydrogen and oxygen. The reactions that generate hydrogen and oxygen gas take place on different electrodes using different precious metal catalysts. In this case, the Nel Hydrogen team replaced the platinum catalyst on the hydrogen-generating side with a catalyst consisting of cobalt phosphide nanoparticles deposited on carbon to form a fine black powder, which was produced by the researchers at SLAC and Stanford. Like other catalysts, it brings other chemicals together and encourages them to react.

The cobalt phosphide catalyst operated extremely well for the entire duration of the test, more than 1,700 hours – an indication that it may be hardy enough for everyday use in reactions that can take place at elevated temperatures, pressures and current densities and in extremely acidic conditions over extended lengths of time, said McKenzie Hubert, a graduate student in Jaramillo’s group who led the experiments with Laurie King, a SUNCAT research engineer who has since joined the faculty of Manchester Metropolitan University.

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Stanford graduate student McKenzie Hubert with equipment used to test a cheap alternative to an expensive catalyst in the lab. A team led by Thomas Jaramillo, director of the SUNCAT center at SLAC and Stanford, went on to show for the first time that this cheap material could achieve high performance in a commercial electrolyzer. (Jacqueline Orrell/SLAC National Accelerator Laboratory)

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Stanford graduate student McKenzie Hubert watches a catalyst produce bubbles of hydrogen in a small, lab-scale electrolyzer. The catalyst, cobalt phosphide, is much cheaper than the platinum catalyst used today and could reduce the cost of a process for making hydrogen – an important fuel and industrial chemical – on a large scale with clean, renewable energy. (Jacqueline Orrell/SLAC National Accelerator Laboratory)

“Our group has been studying this catalyst and related materials for a while,” Hubert said, “and we took it from a fundamental lab-scale, experimental stage through testing it under industrial operating conditions, where you need to cover a much larger surface area with the catalyst and it has to function under much more challenging conditions.”

One of the most important elements of the study was scaling up the production of the cobalt phosphide catalyst while keeping it very uniform – a process that involved synthesizing the starting material at the lab bench, grinding with a mortar and pestle, baking in a furnace and finally turning the fine black powder into an ink that could be sprayed onto sheets of porous carbon paper. The resulting large-format electrodes were loaded into the electrolyzer for the hydrogen production tests.

Producing hydrogen gas at scale

While the electrolyzer development was funded by the Defense Department, which is interested in the oxygen-generating side of electrolysis for use in submarines, Jaramillo said the work also aligns with the goals of DOE’s H2@Scale initiative, which brings DOE labs and industry together to advance the affordable production, transport, storage and use of hydrogen for a number of applications. The fundamental catalyst research was funded by the DOE Office of Science.

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(Greg Stewart/SLAC National Accelerator Laboratory)

Katherine Ayers, vice president for research and development at Nel and a co-author of the paper, said, “Working with Tom gave us an opportunity to see whether these catalysts could be stable for a long time and gave us a chance to see how their performance compared to that of platinum.

“The performance of the cobalt phosphide catalyst needs to get a little bit better, and its synthesis would need to be scaled up,” she said. “But I was quite surprised at how stable these materials were. Even though their efficiency in generating hydrogen was lower than platinum’s, it was constant. A lot of things would degrade in that environment.”

While the platinum catalyst represents only about 8 percent of the total cost of manufacturing hydrogen with PEM, the fact that the market for the precious metal is so volatile, with prices swinging up and down, could hold back development of the technology, Ayers said. Reducing and stabilizing that cost will become increasingly important as other aspects of PEM electrolysis are improved to meet the increasing demand for hydrogen in fuel cells and other applications.

SUNCAT is a partnership between SLAC and the Stanford School of Engineering. Funding for this study came from a Small Business Innovation Research (SBIR) grant from the Department of Defense. Funding for fundamental catalyst development at SUNCAT, which provided the platform for this research, is provided by the DOE Office of Science.

See the full article here .


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SLAC/LCLS II projected view


SLAC is a multi-program laboratory exploring frontier questions in photon science, astrophysics, particle physics and accelerator research. Located in Menlo Park, California, SLAC is operated by Stanford University for the DOE’s Office of Science.

#applied-research-technology, #catalysis, #chemistry, #nanotechnology, #slac-national-accelerator-laboratory, #suncat-center-for-interface-science-and-catalysis

From Stanford University and SLAC: “Stanford developing a radio that searches for dark matter”

Stanford University Name
From Stanford University

and

SLAC National Accelerator Lab

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The dark matter radio is a tabletop device that could explain the mysterious matter that makes up 85 percent of the mass of our universe. (Image credit: Harrison Truong)

September 25, 2019
Taylor Kubota

A team of Stanford University researchers are on a mission to identify dark matter once and for all. But first, they’ll need to build the world’s most sensitive radio.

“Dark matter is most of the matter in our universe. We don’t know what it is but we know it’s there because we can see its gravitational effects,” explained Peter Graham, an associate professor of physics in Stanford’s School of Humanities and Sciences and one of the leaders of this search for dark matter. “We also know it has to be made out of a totally different particle with different properties than anything we’ve ever found.”

Graham and Savas Dimopoulos, the Hamamoto Family Professor in physics at Stanford, have developed theories about dark matter that advocate for high-precision experiments focused on finding axions, theorized particles that are among the most likely candidates for dark matter. Their theories – once considered “interesting but out there,” according to Graham – are gaining popularity as other candidates for dark matter get ruled out and new technologies are making their exacting experiments possible. Now the Gordon and Betty Moore Foundation have granted Stanford researchers roughly $2.5 million to prototype a new kind of dark matter sensor.

Guided by Graham and Dimopoulos’ theories, Kent Irwin, a professor of physics, of particle physics and astrophysics and of photon science at Stanford and SLAC National Accelerator Laboratory, is building the Dark Matter Radio, which will search for the signal of axions the same way a standard AM radio picks up a broadcast. Like an AM radio station, axion dark matter has a precise frequency, but this frequency is unknown. Due to advances in quantum sensors, the radio will be much more sensitive than past dark matter experiments, and able to scan a large swath of the frequencies that are most likely to reveal axions.

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Peter Graham and Kent Irwin are building a tabletop-sized device to detect dark matter. (Image credit: Harrison Truong)

“This project is a really beautiful example of people with very different expertise coming together to solve a hard problem,” said Risa Wechsler, director of the Kavli Institute for Particle Astrophysics and Cosmology (KIPAC) and professor of physics and of particle physics and astrophysics.

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Risa Wechsler, professor of physics and of particle physics and astrophysics. (Image credit: Holly Hernandez)

“Dark matter is 85 percent of the mass in the universe and I think it’s very unlikely that we would exist without it. The exciting thing about this experiment is that it opens up so much discovery space that was previously inaccessible.”

Even if the researchers don’t find the axion, their work would have the distinction of searching a significant fraction of its possible frequency range. The researchers are also excited to see how their sensor development will contribute to spinoff applications in various fields.

The Dark Matter Radio

Dark matter makes up most of the mass in the universe, but each axion is theorized to have such a low mass – falling in the category of ultra-light dark matter – that it might spread out over kilometers. Quantum mechanics, which is the study of behavior of extremely small particles, contends that every particle also behaves like a wave. So, if axions do exist, they’re rippling all around us like a radio signal. The Dark Matter Radio team will scan for the frequency that carries the signal from the wave-like undulations of this ocean of overlapping axions.

The first trick is to convert axion waves into radio waves – carried out by a strong magnetic field inside the Dark Matter Radio. The Dark Matter Radio is also surrounded by a superconducting shield of niobium that blocks out regular radio signals, but will let axions through.

Even with all these enhancements, axions will give off a very weak signal. So, the radio’s tuning has to be incredibly sharp – the equivalent of a car radio that can detect stations separated by one one-millionth of a decimal place. As part of achieving this level of sensitivity and precision, Irwin is working with a new type of quantum sensor that is capable of picking up magnetic signals a hundred million trillion times smaller than what is produced by a typical refrigerator magnet.

“There’s been a breakthrough in the ability to control, create and manipulate quantum states in ways that allow us to take advantage of theory that’s been around for many decades,” said Irwin. “These are some of the same techniques that are being used to develop quantum computers. Instead of using them to compute, we can measure things much more sensitively and precisely than we could before, and the techniques we’re using will have broad applications.”

The same quantum sensors that the researchers are building into the radio could also enhance the precision of medical scanning techniques that measure the properties of magnetic and electric fields in the human body.

Beyond the whiteboard

So far, the researchers have successfully built a soda-can-sized prototype of the dark matter radio that works as an extra-sensitive AM radio. They are currently working on a larger version that will be able to scan all the frequencies of interest with enough sensitivity to measure axion dark matter.

“Most of the ideas that we theorists have fail before they ever get anywhere, so it was a big deal to see this crazy idea that we had on a whiteboard become a physical thing,” said Graham. “The experimentalists, like Kent, still have a lot of work ahead of them but for me, it feels like the culmination of so many years of work. The Dark Matter Radio is going to be real. It’s going to happen.”

See the full article here .


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SLAC/LCLS II projected view


SLAC is a multi-program laboratory exploring frontier questions in photon science, astrophysics, particle physics and accelerator research. Located in Menlo Park, California, SLAC is operated by Stanford University for the DOE’s Office of Science.

Stanford University campus. No image credit

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Leland and Jane Stanford founded the University to “promote the public welfare by exercising an influence on behalf of humanity and civilization.” Stanford opened its doors in 1891, and more than a century later, it remains dedicated to finding solutions to the great challenges of the day and to preparing our students for leadership in today’s complex world. Stanford, is an American private research university located in Stanford, California on an 8,180-acre (3,310 ha) campus near Palo Alto. Since 1952, more than 54 Stanford faculty, staff, and alumni have won the Nobel Prize, including 19 current faculty members

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From SLAC National Accelerator Lab: “Scientists finally find superconductivity in exactly the place they’ve been looking for decades”

From SLAC National Accelerator Lab

September 26, 2019
Glennda Chui

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Computer simulations at SLAC and Stanford suggest a way to turn superconductivity on and off in copper-based materials called cuprates: Tweak the chemistry of the materials so electrons hop from atom to atom in a particular pattern – as if hopping to the atom diagonally across the street rather than to the one next door. This grid of simulated atoms illustrates the idea. Copper atoms are in orange, oxygen atoms are in red and electrons are in blue. (Greg Stewart/SLAC National Accelerator Laboratory)

The Hubbard model, used to understand electron behavior in numerous quantum materials, now shows us its stripes, and superconductivity too, in simulations for cuprate superconductors.

Researchers at Stanford University and the Department of Energy’s SLAC National Accelerator Laboratory say they have found the first, long-sought proof that a decades-old scientific model of material behavior can be used to simulate and understand high-temperature superconductivity ­– an important step toward producing and controlling this puzzling phenomenon at will.

The simulations they ran, published in Science today, suggest that researchers might be able to toggle superconductivity on and off in copper-based materials called cuprates by tweaking their chemistry so electrons hop from atom to atom in a particular pattern – as if hopping to the atom diagonally across the street rather than to the one next door.

“The big thing you want to know is how to make superconductors operate at higher temperatures and how to make superconductivity more robust,” said study co-author Thomas Devereaux, director of the Stanford Institute for Materials and Energy Sciences (SIMES) at SLAC. “It’s about finding the knobs you can turn to tip the balance in your favor.”

The biggest obstacle to doing that, he said, has been the lack of a model – a mathematical representation of how a system behaves – that describes this type of superconductivity, whose discovery in 1986 raised hopes that electricity might someday be transmitted with no loss for perfectly efficient power lines and maglev trains.

While scientists thought the Hubbard model, used for decades to represent electron behavior in numerous materials, might apply to cuprate high-temperature superconductors, until now they had no proof, said Hong-Chen Jiang, a SIMES staff scientist and co-author of the report.

“This has been a major unsolved problem in the field – does the Hubbard model describe high-temperature superconductivity in the cuprates, or is it missing some key ingredient?” he said. “Because there are a number of competing states in these materials, we have to rely on unbiased simulations to answer these questions, but the computational problems are very difficult, and so progress has been slow.”

The many faces of quantum materials

Why so difficult?

While many materials behave in very predictable ways – copper is always a metal, and when you bust up a magnet the bits are still magnetic – high-temperature superconductors are quantum materials, where electrons cooperate to produce unexpected properties. In this case, they pair up to conduct electricity with no resistance or loss at much higher temperatures than established theories of superconductivity can explain.

Unlike everyday materials, quantum materials can host a number of phases, or states of matter, at once, Devereaux said. For instance, a quantum material might be metallic under one set of conditions, but insulating under slightly different conditions. Scientists can tip the balance between phases by tinkering with the material’s chemistry or the way its electrons move around, for instance, and the goal is to do this in a deliberate way to create new materials with useful properties.

One of the most powerful algorithms for modeling situations like this is known as density matrix renormalization group, or DMRG. But because these coexisting phases are so complex, using the DMRG to simulate them requires a lot of computation time and memory and typically takes quite a while, Jiang said.

To reduce the computing time and reach a deeper level of analysis than would have been practical before, Jiang looked for ways to optimize the details of the simulation. “We have to carefully streamline each step,” he said, “making it as efficient as possible and even finding ways to do two separate things at once.” These efficiencies allowed the team to run DMRG simulations of the Hubbard model significantly faster than before, with about a year of computing time at Stanford’s Sherlock computing cluster and other facilities on the SLAC campus.

Hopping electron neighbors

This study focused on the delicate interplay between two phases that are known to exist in cuprates – high-temperature superconductivity and charge stripes, which are like a wave pattern of higher and lower electron density in the material. The relationship between these states is not clear, with some studies suggesting that charge stripes promote superconductivity and others suggesting they compete with it.

For their analysis, Jiang and Devereaux created a virtual version of a cuprate on a square lattice, like a wire fence with square holes. The copper and oxygen atoms are confined to planes in the real material, but in the virtual version they become single, virtual atoms that sit at each of the intersections where wires meet. Each of these virtual atoms can accommodate at most two electrons that are free to jump or hop – either to their immediate neighbors on the square lattice or diagonally across each square.

When the researchers used DMRG to simulate the Hubbard model as applied to this system, they discovered that changes in the electrons’ hopping patterns had a noticeable effect on the relationship between charge stripes and superconductivity.

When electrons hopped only to their immediate neighbors on the square lattice, the pattern of charge stripes got stronger and the superconducting state never appeared. When electrons were allowed to hop diagonally, charge stripes eventually weakened, but did not go away, and the superconducting state finally emerged.

“Until now we could not push far enough in our modeling to see if charge stripes and superconductivity can coexist when this material is in its lowest energy state. Now we know they do, at least for systems of this size,” Devereaux said.

It’s still an open question whether the Hubbard model describes all of the incredibly complex behavior of real cuprates, he added. Even a small increase in the complexity of the system would require a huge leap in the power of the algorithm used to model it. “The time it takes to do your simulation goes up exponentially fast with the width of the system you want to study,” Devereaux said. “It’s exponentially more complicated and demanding.”

But with these results, he said, “We now have a fully interacting model that describes high temperature superconductivity, at least for systems at the sizes we can study, and that’s a big step forward.”

Funding for the study came from the DOE Office of Science.

See the full article here .


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SLAC/LCLS


SLAC/LCLS II projected view


SLAC is a multi-program laboratory exploring frontier questions in photon science, astrophysics, particle physics and accelerator research. Located in Menlo Park, California, SLAC is operated by Stanford University for the DOE’s Office of Science.

#cuprates, #dmrg-density-matrix-renormalization-group, #slac-national-accelerator-laboratory, #superconductivity, #the-hubbard-model

From SLAC and DESY: “Breaking up buckyballs is hard to do”

From SLAC National Accelerator Lab

DESY
From DESY

4

September 23, 2019
Ali Sundermier

How molecular footballs burst in an X-ray laser beam.

As reported in Nature Physics, an international research team observed how soccer ball-shaped molecules made of carbon atoms burst in the beam of an X-ray laser. The molecules, called buckminsterfullerenes – buckyballs for short ­– consist of 60 carbon atoms arranged in alternating pentagons and hexagons like the leather coat of a soccer ball. These molecules were expected to break into fragments after being bombarded with photons, but the researchers watched in real time as buckyballs resisted the attack and delayed their break-up.

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An illustration shows how soccer ball-shaped molecules called buckyballs ionize and break up when blasted with an X-ray laser. A team of experimentalists and theorists identified chemical bonds and charge transfers as crucial factors that significantly delayed the fragmentation process by about 600 millionths of a billionth of a second. (Greg Stewart/SLAC National Accelerator Laboratory)

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Computer simulated evolution of a C60 molecule at 0, 60 and 240 femto seconds after the X-ray flash. Credit: DESY, Zoltan Jurek

“Buckyballs are well suited as a simple model system for biomolecules,” explains Robin Santra, who is a lead scientist at DESY at the Center for Free-Electron Laser Science (CFEL) and a physics professor at the Universität Hamburg. “Since they consist of only one type of atom and have a symmetrical structure, they can be well represented in theory and experiment. This is a first step before the investigation of molecules from different types of atoms.”

The team was led by Nora Berrah, a professor at the University of Connecticut, and included researchers from the Department of Energy’s SLAC National Accelerator Laboratory and the Deutsches Elektronen-Synchrotron (DESY) in Germany. The researchers focused their attention on examining the role of chemical effects, such as chemical bonds and charge transfer, on the buckyball’s fragmentation.

Using X-ray laser pulses from SLAC’s Linac Coherent Light Source (LCLS) [below], the team showed how the bursting process, which takes only a few hundred femtoseconds, or millionths of a billionth of a second, unfolds over time. The results will be important for the analysis of sensitive proteins and other biomolecules, which are also frequently studied using bright X-ray laser flashes, and they also strengthen confidence in protein analysis with X-ray free-electron lasers (XFELs).

“This investigation uncovered for the first time the persistence of the molecular structure, which thwarted fragmentation over a timescale of hundreds of femtoseconds” Berrah says. “With the dawn of several new XFELs in the world, the findings lay the foundation for a deeper understanding of XFEL-induced radiation damage, which will have a strong impact on biomolecular imaging.”

What follows then is not an actual explosion,” explains the scientist. “Instead, the buckyballs dissolve comparatively slowly. Carbon atoms gradually evaporate – with many more neutral ones than electrically charged ones, which was surprising.” Since the fragmentation of the buckyballs on this time scale is not explosive but happens gradually, the researchers speak of the evaporation of the atoms. The experimental data could only be meaningfully interpreted with the help of theoretical modelling of the process.

“Typically, about 25 neutral and only 15 electrically charged carbon atoms fly out of the molecule,” Santra explains. “The rest form fragments of several atoms.” The whole process takes about 600 femtoseconds. This is still unimaginably short by human standards, but extremely long for structural analysis with X-ray lasers. “In the typically 20 femtoseconds of an X-ray laser flash, the atoms move a maximum of 0.1 nanometers – that is in the range of individual atom diameters and smaller than the measurement accuracy of structural analysis.” One nanometer is one millionth of a millimeter.

For the structural analysis of proteins, researchers usually grow small crystals from the biomolecules. The bright X-ray laser flash is then diffracted at the crystal lattice and generates a typical diffraction pattern from which the crystal structure and with it the spatial structure of the individual proteins can be calculated. The spatial structure of a protein reveals details about its exact function. The protein crystals are very sensitive and evaporate through the X-ray laser flash. However, previous investigations had shown that the crystal remains intact long enough to generate the diffraction image before evaporation and thus to reveal its spatial structure.

The new study now confirms that this is also the case with individual molecules that are not bound in a crystal lattice. “Our findings with buckyballs are likely to play a role in most other molecules,” Santra emphasises. Since many biomolecules are notoriously difficult to crystallise, researchers hope to be able to determine the structure of ensembles of non-crystallised proteins or even individual biomolecules with X-ray lasers in the future. The results obtained now lay the foundation for a deeper understanding and quantitative modelling of the radiation damage in biomolecules induced by X-ray laser flashes, the scientists write.

The study also involved researchers from Imperial College London; University of Gothenburg in Sweden; University of Texas; Synchrotron SOLEIL in France; Kansas State University; Tohoku University in Japan; State University of New York at Potsdam; and Max Planck Institute for Nuclear Physics, Max Born Institute and University of Hamburg, all in Germany.

See the full article here .
See the full DESY article here .


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DESY is one of the world’s leading accelerator centres. Researchers use the large-scale facilities at DESY to explore the microcosm in all its variety – from the interactions of tiny elementary particles and the behaviour of new types of nanomaterials to biomolecular processes that are essential to life. The accelerators and detectors that DESY develops and builds are unique research tools. The facilities generate the world’s most intense X-ray light, accelerate particles to record energies and open completely new windows onto the universe. 
That makes DESY not only a magnet for more than 3000 guest researchers from over 40 countries every year, but also a coveted partner for national and international cooperations. Committed young researchers find an exciting interdisciplinary setting at DESY. The research centre offers specialized training for a large number of professions. DESY cooperates with industry and business to promote new technologies that will benefit society and encourage innovations. This also benefits the metropolitan regions of the two DESY locations, Hamburg and Zeuthen near Berlin.

DESY Petra III interior


DESY Petra III

DESY/FLASH

H1 detector at DESY HERA ring

DESY DORIS III

SLAC/LCLS


SLAC/LCLS II projected view


SLAC is a multi-program laboratory exploring frontier questions in photon science, astrophysics, particle physics and accelerator research. Located in Menlo Park, California, SLAC is operated by Stanford University for the DOE’s Office of Science.

#buckminsterfullerenes-buckyballs, #desy, #slac-national-accelerator-laboratory

From SLAC National Accelerator Lab: “Plastics, fuels and chemical feedstocks from CO2? They’re working on it.”

From SLAC National Accelerator Lab

September 9, 2019
Glennda Chui

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Researchers at Stanford and SLAC are working on ways to convert waste carbon dioxide (CO2) into chemical feedstocks and fuels, turning a potent greenhouse gas into valuable products. The process is called electrochemical conversion. When powered by renewable energy sources (far left), it could reduce levels of carbon dioxide in the air and store energy from these intermittent sources in a form that can be used any time. (Greg Stewart/SLAC National Accelerator Laboratory)

One way to reduce the level of carbon dioxide in the atmosphere, which is now at its highest point in 800,000 years, would be to capture the potent greenhouse gas from the smokestacks of factories and power plants and use renewable energy to turn it into things we need, says Thomas Jaramillo.

As director of SUNCAT Center for Interface Science and Catalysis, a joint institute of Stanford University and the Department of Energy’s SLAC National Accelerator Laboratory, he’s in a position to help make that happen.

A major focus of SUNCAT research is finding ways to transform CO2 into chemicals, fuels, and other products, from methanol to plastics, detergents and synthetic natural gas. The production of these chemicals and materials from fossil fuel ingredients now accounts for 10% of global carbon emissions; the production of gasoline, diesel, and jet fuel accounts for much, much more.

“We have already emitted too much CO2, and we’re on track to continue emitting it for years, since 80% of the energy consumed worldwide today comes from fossil fuels,” says Stephanie Nitopi, whose SUNCAT research is the basis of her newly acquired Stanford PhD.

“You could capture CO2 from smokestacks and store it underground,” she says. “That’s one technology currently in play. An alternative is to use it as a feedstock to make fuels, plastics, and specialty chemicals, which shifts the financial paradigm. Waste CO2 emissions now become something you can recycle into valuable products, providing a new incentive to reduce the amount of CO2 released into the atmosphere. That’s a win-win.”

We asked Nitopi, Jaramillo, SUNCAT staff scientist Christopher Hahn and postdoctoral researcher Lei Wang to tell us what they’re working on and why it matters.

Q. First the basics: How do you convert CO2 into these other products?

Tom: It’s essentially a form of artificial photosynthesis, which is why DOE’s Joint Center for Artificial Photosynthesis funds our work. Plants use solar energy to convert CO2 from the air into carbon in their tissues. Similarly, we want to develop technologies that use renewable energy, like solar or wind, to convert CO2 from industrial emissions into carbon-based products.

Chris: One way to do this is called electrochemical CO2 reduction, where you bubble CO2 gas up through water and it reacts with the water on the surface of a copper-based electrode. The copper acts as a catalyst, bringing the chemical ingredients together in a way that encourages them to react. Put very simply, the initial reaction strips an oxygen atom from CO2 to form carbon monoxide, or CO, which is an important industrial chemical in its own right. Then other electrochemical reactions turn CO into important molecules such as alcohols, fuels and other things.

Today this process requires a copper-based catalyst. It’s the only one known to do the job. But these reactions can produce numerous products, and separating out the one you want is costly, so we need to identify new catalysts that are able to guide the reaction toward making only the desired product.

How so?

Lei: When it comes to improving a catalyst’s performance, one of the key things we look at is how to make them more selective, so they generate just one product and nothing else. About 90 percent of fuel and chemical manufacturing depends on catalysts, and getting rid of unwanted byproducts is a big part of the cost.

We also look at how to make catalysts more efficient by increasing their surface area, so there are a lot more places in a given volume of material where reactions can occur simultaneously. This increases the production rate.

Recently we discovered something surprising [Nature Catalysis]: When we increased the surface area of a copper-based catalyst by forming it into a flaky “nanoflower” shape, it made the reaction both more efficient and more selective. In fact, it produced virtually no byproduct hydrogen gas that we could measure. So this could offer a way to tune reactions to make them more selective and cost-competitive.

Stephanie: This was so surprising that we decided to revisit all the research we could find [Chem. Rev.] on catalyzing electrochemical CO2 conversion with copper, and the many ways people have tried to understand and fine-tune the process, using both theory and experiments, going back four decades. There’s been an explosion of research on this – about 60 papers had been published as of 2006, versus more than 430 out there today – and analyzing all the studies with our collaborators at the Technical University of Denmark took two years.

We were trying to figure out what makes copper special, why it’s the only catalyst that can make some of these interesting products, and how we can make it even more efficient and selective – what techniques have actually pushed the needle forward? We also offered our perspectives on promising research directions.

One of our conclusions confirms the results of the earlier study: The copper catalyst’s surface area can be used to improve both the selectivity and overall efficiency of reactions. So this is well worth considering as a chemical production strategy.

Does this approach have other benefits?

Tom: Absolutely. If we use clean, renewable energy, like wind or solar, to power the controlled conversion of waste CO2 to a wide range of other products, this could actually draw down levels of CO2 in the atmosphere, which we will need to do to stave off the worst effects of global climate change.

Chris: And when we use renewable energy to convert CO2 to fuels, we’re storing the variable energy from those renewables in a form that can be used any time. In addition, with the right catalyst, these reactions could take place at close to room temperature, instead of the high temperatures and pressures often needed today, making them much more energy efficient.

How close are we to making it happen?

Tom: Chris and I explored this question in a recent Perspective article in Science, written with researchers from the University of Toronto and TOTAL American Services, which is an oil and gas exploration and production services firm.

We concluded that renewable energy prices would have to fall below 4 cents per kilowatt hour, and systems would need to convert incoming electricity to chemical products with at least 60% efficiency, to make the approach economically competitive with today’s methods.

Chris: This switch couldn’t happen all at once; the chemical industry is too big and complex for that. So one approach would be to start with making high-value, high-volume products like ethylene, which is used to make alcohols, polyester, antifreeze, plastics and synthetic rubber. It’s a $230 billion global market today. Switching from fossil fuels to CO2 as a starting ingredient for ethylene in a process powered by renewables could potentially save the equivalent of about 860 million metric tons of CO2 emissions per year.

The same step-by-step approach applies to sources of CO2. Industry could initially use relatively pure CO2 emissions from cement plants, breweries or distilleries, for instance, and this would have the side benefit of decentralizing manufacturing. Every country could provide for itself, develop the technology it needs, and give its people a better quality of life.

Tom: Once you enter certain markets and start scaling up the technology, you can attack other products that are tougher to make competitively today. What this paper concludes is that these new processes have a chance to change the world.

See the full article here .


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SLAC is a multi-program laboratory exploring frontier questions in photon science, astrophysics, particle physics and accelerator research. Located in Menlo Park, California, SLAC is operated by Stanford University for the DOE’s Office of Science.

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From Stanford University and SLAC: “New coating developed by Stanford researchers brings lithium metal battery closer to reality”

Stanford University Name
From Stanford University

August 26, 2019
Mark Golden

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A new coating could make lightweight lithium metal batteries safe and long lasting, a boon for development of next-generation electric vehicles. (Image credit: Shutterstock)

Hope has been restored for the rechargeable lithium metal battery – a potential battery powerhouse relegated for decades to the laboratory by its short life expectancy and occasional fiery demise while its rechargeable sibling, the lithium-ion battery, now rakes in more than $30 billion a year.

A team of researchers at Stanford University and SLAC National Accelerator Laboratory has invented a coating that overcomes some of the battery’s defects, described in a paper published Aug. 26 in Joule.

In laboratory tests, the coating significantly extended the battery’s life. It also dealt with the combustion issue by greatly limiting the tiny needlelike structures – or dendrites – that pierce the separator between the battery’s positive and negative sides. In addition to ruining the battery, dendrites can create a short circuit within the battery’s flammable liquid. Lithium-ion batteries occasionally have the same problem, but dendrites have been a non-starter for lithium metal rechargeable batteries to date.

“We’re addressing the holy grail of lithium metal batteries,” said Zhenan Bao, a professor of chemical engineering, who is senior author of the paper along with Yi Cui, professor of materials science and engineering and of photon science at SLAC. Bao added that dendrites had prevented lithium metal batteries from being used in what may be the next generation of electric vehicles.

The promise

Lithium metal batteries can hold at least a third more power per pound as lithium-ion batteries do and are significantly lighter because they use lightweight lithium for the positively charged end rather than heavier graphite. If they were more reliable, these batteries could benefit portable electronics from notebook computers to cell phones, but the real pay dirt, Cui said, would be for cars. The biggest drag on electric vehicles is that their batteries spend about a fourth of their energy carrying themselves around. That gets to the heart of EV range and cost.

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Lead authors and PhD students David Mackanic, left, and Zhiao Yu in front of their battery tester. Yu is holding a dish of already tested cells that they call the “battery graveyard.” (Image credit: Mark Golden)

“The capacity of conventional lithium-ion batteries has been developed almost as far as it can go,” said Stanford PhD student David Mackanic, co-lead author of the study. “So, it’s crucial to develop new kinds of batteries to fulfill the aggressive energy density requirements of modern electronic devices.”

The team from Stanford and SLAC tested their coating on the positively charged end – called the anode – of a standard lithium metal battery, which is where dendrites typically form. Ultimately, they combined their specially coated anodes with other commercially available components to create a fully operational battery. After 160 cycles, their lithium metal cells still delivered 85 percent of the power that they did in their first cycle. Regular lithium metal cells deliver about 30 percent after that many cycles, rendering them nearly useless even if they don’t explode.

The new coating prevents dendrites from forming by creating a network of molecules that deliver charged lithium ions to the electrode uniformly. It prevents unwanted chemical reactions typical for these batteries and also reduces a chemical buildup on the anode, which quickly devastates the battery’s ability to deliver power.

“Our new coating design makes lithium metal batteries stable and promising for further development,” said the other co-lead author, Stanford PhD student Zhiao Yu.

The group is now refining their coating design to increase capacity retention and testing cells over more cycles.

“While use in electric vehicles may be the ultimate goal,” said Cui, “commercialization would likely start with consumer electronics to demonstrate the battery’s safety first.”

Zhenan Bao and Yi Cui are also senior fellows at Stanford’s Precourt Institute for Energy. Other Stanford researchers include Jian Qin, assistant professor of chemical engineering; postdoctoral scholars Dawei Feng, Jiheong James Kang, Minah Lee, Chibueze Amanchukwu, Xuzhou Yan, Hansen Wang and Kai Liu; students Wesley Michaels, Allen Pei, Shucheng Chen and Yuchi Tsao; and visiting scholar Qiuhong Zhang from Nanjing University.

This work was supported by the U.S. Department of Energy Office of Energy Efficiency & Renewable Energy. The facility used at Stanford is supported by the National Science Foundation.

See the full article here .


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Leland and Jane Stanford founded the University to “promote the public welfare by exercising an influence on behalf of humanity and civilization.” Stanford opened its doors in 1891, and more than a century later, it remains dedicated to finding solutions to the great challenges of the day and to preparing our students for leadership in today’s complex world. Stanford, is an American private research university located in Stanford, California on an 8,180-acre (3,310 ha) campus near Palo Alto. Since 1952, more than 54 Stanford faculty, staff, and alumni have won the Nobel Prize, including 19 current faculty members

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From SLAC National Accelerator Lab: “First report of superconductivity in a nickel oxide material”

August 28, 2019
Glennda Chui
glennda@slac.stanford.edu
(650) 926-4897

Made with ‘Jenga chemistry,’ the discovery could help crack the mystery of how high-temperature superconductors work.

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An illustration depicts a key step in creating a new type of superconducting material: Much like pulling blocks from a tower in a Jenga game, scientists used chemistry to neatly remove a layer of oxygen atoms. This flipped the material into a new atomic structure – a nickelate – that can conduct electricity with 100 percent efficiency. (Greg Stewart/SLAC National Accelerator Laboratory)

Scientists at the Department of Energy’s SLAC National Accelerator Laboratory and Stanford University have made the first nickel oxide material that shows clear signs of superconductivity – the ability to transmit electrical current with no loss.

Also known as a nickelate, it’s the first in a potential new family of unconventional superconductors that’s very similar to the copper oxides, or cuprates, whose discovery in 1986 raised hopes that superconductors could someday operate at close to room temperature and revolutionize electronic devices, power transmission and other technologies. Those similarities have scientists wondering if nickelates could also superconduct at relatively high temperatures.

At the same time, the new material seems different from the cuprates in fundamental ways – for instance, it may not contain a type of magnetism that all the superconducting cuprates have – and this could overturn leading theories of how these unconventional superconductors work. After more than three decades of research, no one has pinned that down.

The experiments were led by Danfeng Li, a postdoctoral researcher with the Stanford Institute for Materials and Energy Sciences (SIMES) at SLAC, and described today in Nature.

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“This is a very important discovery that requires us to rethink the details of the electronic structure and possible mechanisms of superconductivity in these materials,” said George Sawatzky, a professor of physics and chemistry at the University of British Columbia who was not involved in the study but wrote a commentary that accompanied the paper in Nature. “This is going to cause an awful lot of people to jump into investigating this new class of materials, and all sorts of experimental and theoretical work will be done.”

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To create a new type of superconducting material, scientists at SLAC and Stanford first made a thin film of a common material known as perovskite, left; “doped” it with strontium; and then exposed it to a chemical that yanked out a layer of oxygen atoms, much like removing a stick from a tower of Jenga blocks. This made the film flip into a different atomic structure known as a nickelate, right. Tests showed that this nickelate can conduct electricity with no resistance. (Danfeng Li/SLAC National Accelerator Laboratory and Stanford University)

A difficult path

Ever since the cuprate superconductors were discovered, scientists have dreamed of making similar oxide materials based on nickel, which is right next to copper on the periodic table of the elements.

But making nickelates with an atomic structure that’s conducive to superconductivity turned out to be unexpectedly hard.

“As far as we know, the nickelate we were trying to make is not stable at the very high temperatures – about 600 degrees Celsius – where these materials are normally grown,” Li said. “So we needed to start out with something we can stably grow at high temperatures and then transform it at lower temperatures into the form we wanted.”

He started with a perovskite – a material defined by its unique, double-pyramid atomic structure – that contained neodymium, nickel and oxygen. Then he doped the perovskite by adding strontium; this is a common process that adds chemicals to a material to make more of its electrons flow freely.

This stole electrons away from nickel atoms, leaving vacant “holes,” and the nickel atoms were not happy about it, Li said. The material was now unstable, making the next step – growing a thin film of it on a surface – really challenging; it took him half a year to get it to work.

‘Jenga chemistry’

Once that was done, Li cut the film into tiny pieces, loosely wrapped it in aluminum foil and sealed it in a test tube with a chemical that neatly snatched away a layer of its oxygen atoms – much like removing a stick from a wobbly tower of Jenga blocks. This flipped the film into an entirely new atomic structure – a strontium-doped nickelate.


SIMES researcher Danfeng Li explains the delicate ‘Jenga chemistry’ behind making a new nickel oxide material, the first in a potential new family of unconventional superconductors. (Linda McCulloch, SLAC National Accelerator Laboratory)

“Each of these steps had been demonstrated before,” Li said, “but not in this combination.”

He remembers the exact moment in the laboratory, around 2 a.m., when tests indicated that the doped nickelate might be superconducting. Li was so excited that he stayed up all night, and in the morning co-opted the regular meeting of his research group to show them what he’d found. Soon, many of the group members joined him in a round-the-clock effort to improve and study this material.

Further testing would reveal that the nickelate was indeed superconducting in a temperature range from 9-15 kelvins – incredibly cold, but a first start, with possibilities of higher temperatures ahead.

More work ahead

Research on the new material is in a “very, very early stage, and there’s a lot of work ahead,” cautioned Harold Hwang, a SIMES investigator, professor at SLAC and Stanford and senior author of the report. “We have just seen the first basic experiments, and now we need to do the whole battery of investigations that are still going on with cuprates.”

Among other things, he said, scientists will want to dope the nickelate material in various ways to see how this affects its superconductivity across a range of temperatures, and determine whether other nickelates can become superconducting. Other studies will explore the material’s magnetic structure and its relationship to superconductivity.

SIMES researchers from the Stanford departments of Physics, Applied Physics and Materials Science and Engineering also contributed to the study, which was funded by the DOE Office of Science and the Gordon and Betty Moore Foundation’s Emergent Phenomena in Quantum Systems Initiative.

See the full article here .


five-ways-keep-your-child-safe-school-shootings
Please help promote STEM in your local schools.

Stem Education Coalition

SLAC/LCLS


SLAC/LCLS II projected view


SLAC is a multi-program laboratory exploring frontier questions in photon science, astrophysics, particle physics and accelerator research. Located in Menlo Park, California, SLAC is operated by Stanford University for the DOE’s Office of Science.

#condenced-matter-physics, #jenga-chemistry, #material-sciences-2, #simes-stanford-institute-for-materials-energy-sciences, #slac-national-accelerator-laboratory, #superconductivity