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  • richardmitnick 2:50 pm on December 14, 2017 Permalink | Reply
    Tags: , As cars become more fuel-efficient less heat is wasted in the exhaust which makes it harder to clean up the pollutants are being emitted, Catalyst technology, , , , Researchers have recently created a catalyst capable of reducing pollutants at the lower temperatures expected in advanced engines   

    From PNNL: “New catalyst meets challenge of cleaning exhaust from modern engines” 

    PNNL BLOC
    PNNL Lab

    EMSL

    EMSL

    December 14, 2017
    Susan Bauer
    susan.bauer@pnnl.gov
    (509) 372-6083

    Innovation also uses less platinum, expensive component of catalytic converters.

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    Researchers discovered a new type of active site (dashed green circles) which meets the dual challenge of achieving high activity and thermal stability in single-atom catalysts to improve vehicle emissions. No image credit.

    As cars become more fuel-efficient, less heat is wasted in the exhaust, which makes it harder to clean up the pollutants are being emitted. But researchers have recently created a catalyst capable of reducing pollutants at the lower temperatures expected in advanced engines. Their work, published this week in Science magazine, a leading peer-reviewed research journal, presents a new way to create a more powerful catalyst while using smaller amounts of platinum, the most expensive component of emission-control catalysts.

    The recent findings grew out of a collaboration between research groups led by Yong Wang, who holds a joint appointment at the Department of Energy’s Pacific Northwest National Laboratory and is a Voiland Distinguished Professor at Washington State University’s Gene and Linda Voiland School of Chemical Engineering and Bioengineering and Abhaya Datye, a distinguished professor at the University of New Mexico.

    Catalysts have been an integral part of the exhaust systems of diesel- and gasoline-powered engines since the mid-1970s when federal regulations called for reductions of carbon monoxide, hydrocarbons and nitrogen oxides. Catalytic converters transform the pollutants to nitrogen, carbon dioxide and water.

    The researchers addressed the daunting challenge of designing a catalyst that could endure engine exhaust temperatures of up to nearly 1,500 degrees Fahrenheit encountered under high engine loads. Yet the catalyst would still have to work when an engine is started cold and must clean up the exhaust before reaching 300 degrees Fahrenheit, significantly lower than current systems. The lower operating temperatures during cold start are due to increasing fuel efficiency in advanced combustion engines, which leaves less energy in the tailpipe exhaust, said Datye, a study co-author.

    The recent findings build on research, published in Science last year, in which the Wang and Datye groups found a novel way to trap and stabilize individual platinum atoms on the surface of cerium oxide, a commonly used component in emissions control catalysts. The so-called single-atom catalyst uses platinum more efficiently while remaining stable at high temperatures. Platinum typically trades at prices close to or even greater than gold.

    For their latest paper [Science], the researchers steam-treated the catalyst at nearly 1,400 degrees Fahrenheit. This made the already stable catalyst become very active at the low cold-start temperatures.

    “We were able to meet the challenges of both the high-temperature stability and the low-temperature activity,” Wang said. “This demonstration of hydrothermal stability, along with high reactivity, makes it possible to bring single-atom catalysis closer to industrial application.”

    Multiple types of spectroscopy and electron microscopy capabilities available at EMSL, the Environmental Molecular Sciences Laboratory, a DOE Office of Science User Facility on the PNNL campus, allowed the scientists to understand the catalyst surface at the atomic level and provide mechanistic insight into how oxygen vacancies migrate to the surface of the cerium oxide, creating pathways for highly active carbon monoxide conversion.

    The work was funded by DOE’s Office of Science and Office of Energy Efficiency and Renewable Energy’s Vehicle Technologies Office.

    See the full article here .

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    Pacific Northwest National Laboratory (PNNL) is one of the United States Department of Energy National Laboratories, managed by the Department of Energy’s Office of Science. The main campus of the laboratory is in Richland, Washington.

    PNNL scientists conduct basic and applied research and development to strengthen U.S. scientific foundations for fundamental research and innovation; prevent and counter acts of terrorism through applied research in information analysis, cyber security, and the nonproliferation of weapons of mass destruction; increase the U.S. energy capacity and reduce dependence on imported oil; and reduce the effects of human activity on the environment. PNNL has been operated by Battelle Memorial Institute since 1965.

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  • richardmitnick 11:05 am on November 29, 2017 Permalink | Reply
    Tags: , Catalyst technology, , , Professor Xile Hu, , Swiss National Latsis Prize, Swiss National Science Foundation, Synthesis of high-added-value molecules   

    From EPFL: “The key to chemical transformations” 

    EPFL bloc

    École Polytechnique Fédérale de Lausanne EPFL

    29.11.17
    Nik Papageorgiou


    Professor Xile Hu, an expert in catalysis at EPFL’s Institute of Chemical Sciences and Engineering, has been awarded the 2017 National Latsis Prize.

    The National Latsis Prize is among the most important scientific distinctions in Switzerland, and includes a monetary award of CHF 100,000. It is awarded by the Swiss National Science Foundation (SNSF) on behalf of the International Latsis Foundation to recognize “researchers up to the age of 40 for exceptional scientific work conducted in Switzerland.”

    This is the 34th award of the Latsis National Prize, and will be presented to Professor Hu by the SNSF on 11 January 2018, during a ceremony at Bern’s Hôtel de ville.

    Professor Xile Hu is recognized “for his impressive scientific career and his excellent research on the fundamental understanding of catalysis.” Catalysis is a branch of chemistry focused on substances that accelerate reactions or transform molecules. Professor Hu has distinguished himself by his pioneering research on the production of solar fuels, as well as on the synthesis of molecules with high added value.

    “I have decided to not worry too much about the barriers between fields, as long as it works and gives interesting results,” he says. “I try to always bring something new or unpredictable into my research, but that is not necessarily obvious. In science, we want things to happen in a logical way – so when we suggest something unprecedented or not deemed to be feasible, we can look a bit crazy.”

    Official press release

    29/Nov/2017

    Contact

    Prof. Xile HU
    Ecole polytechnique fédérale de Lausanne
    EPFL SB ISIC LSCI
    BCH 3305 (Bât. BCH)
    CH-1015 Lausanne
    Tel.: +41 21 693 97 81
    E-mail: xile.hu@epfl.ch

    2
    Swiss National Science Foundation
    3
    Chemist Xile Hu is the winner of the National Latsis Prize for 2017. Hu, a professor at the École Polytechnique Fédérale de Lausanne, was recognised for his outstanding scientific career and his original contributions to the fundamental understanding of catalysis.

    Catalysis is a field of chemistry that studies materials that can accelerate or bring about chemical transformations. Hu has distinguished himself through his pioneering work on the production of solar fuels and the synthesis of high-added-value molecules. The prize is awarded each year by the Swiss National Science Foundation (SNSF) on behalf of the International Latsis Foundation.

    Novel approach

    Hu, who was born in China and came to Switzerland in 2007, founded the Laboratory of Inorganic Synthesis and Catalysis at the École Polytechnique Fédérale de Lausanne (EPFL). He is known for his innovative approach, which consists of combining the concepts and methods associated with three different types of catalysis (homogeneous, heterogeneous and enzymatic), which traditionally have remained separate. This approach has led to unprecedented understanding of fundamental catalysis and enabled the discovery of new catalysts with properties superior to those of previous materials.

    “I decided not to worry too much about barriers between the types, as long as they work and give interesting results”, says Hu, a professor at the EPFL’s Institute of Chemical Sciences and Engineering. “I always try to introduce something new or unpredictable to my research, but that’s not necessarily obvious. Scientists like things to happen logically, so when you suggest something unfamiliar or that’s believed to be impossible, you may sound a little crazy.”

    Accordingly, the 39-year-old Hu sought to model enzymes (enzymatic catalysis) as part of his research on solar fuels (heterogeneous catalysis). “It didn’t work, but we discovered a very good, new type of catalyst”, explains Hu. Half of his research team is working on solar fuels. “We use solar energy to split water into oxygen and hydrogen, because hydrogen is an excellent source of energy”, says Hu, who received his undergraduate degree in chemistry from Peking University. “We would like to use catalytic materials to store this energy in the form of chemical products.” Hu estimates that such a technology could become reality in 15 to 20 years.

    At the heart of chemistry

    Research on high-value-added molecules for chemical products is Hu’s other major area of research. “We are focusing on catalysis based on elements that are abundant on Earth, like iron, copper and nickel”, says Hu, who did his postdoctoral research at the California Institute of Technology. “Until now, the chemical industry has mostly been working with precious metals like platinum, but these are rare and expensive. Abundant Earth elements are cheaper and have good potential, seeing as how they have been very little studied from that vantage.” These new molecules could later find use in the pharmaceutical, food-processing or even cosmetic industries.

    Hu has amassed a remarkable number of publications for someone his age. “Scientific articles are really collaborative efforts”, he says. “I have been fortunate in finding students who are motivated and excited by the idea of investigating areas that are still relatively undiscovered.”

    “I find it fascinating to be able to create new materials and to work in a field that has an impact on both nature and the living world”, says Hu. “Catalysis is at the heart of chemistry, but it goes unnoticed because it is so much a part of everyday life. Yet today it is more important than ever, especially for dealing with the energy challenges that humanity faces.”

    _________________________________________________________________________
    Global chemist

    Xile Hu was born in Putian, in south-eastern China, on 7 August 1978. He is a professor at the Institute of Chemical Sciences and Engineering at the École Polytechnique Fédérale de Lausanne (EPFL). After receiving his bachelor’s degree in chemistry at Peking University in 2000, he left for the University of California, San Diego, where he received his master’s degree in 2002 and his PhD in 2004. He then did postdoctoral research at the California Institute of Technology in Pasadena from 2005 to 2007. That same year, he accepted a position at EPFL, where he went on to found the Laboratory of Inorganic Synthesis and Catalysis. He has received numerous prizes and distinctions, including the Werner Prize from the Swiss Chemical Society.

    Hu says he is “sometimes embarrassed that I don’t fit the cliché of the scientist who spends all his free time in the laboratory”. He enjoys skiing and hiking in the mountains. Hu is married to a Swiss acupuncturist, with whom he has a three-month-old daughter.

    Little noticed, but vital

    Catalysis refers to the use of a substance to accelerate chemical transformations, or to bring about transformations that would not have occurred naturally. “Nearly 90% of chemical processes rely on catalysis at some point”, says Xile Hu, professor of chemistry at the École Polytechnique Fédérale de Lausanne (EPFL) and winner of the National Latsis Prize for 2017. “We would like them to enjoy even more widespread use, because a good catalyst makes it possible to avoid needless steps, in terms of cost as well as of time and energy.” Although catalysis is mainly employed in the chemical industry, it is equally important for humans and in nature. “Plants use biological catalysts for photosynthesis, whereas humans rely on enzymatic catalysis to metabolise the oxygen that they breathe”, says Hu. Moreover, anything to do with fermentation, such as the making of beer, yogurt or bread, depends on catalysis. Finally, the best-known catalysts are those used in cars. These catalysts transform engine emissions into non-toxic components that are then released into the air.

    National Latsis Prize

    Since 1983, the National Latsis Prize has been conferred annually by the Swiss National Science Foundation (SNSF) on behalf of the International Latsis Foundation, a non-profit organisation founded in 1975 and based in Geneva. It is awarded for outstanding scientific work by a Switzerland-based researcher under 40. With CHF 100,000 in prize money, the National Latsis Prize is one of Switzerland’s most prestigous scientific awards. There are also four University Latsis Prizes, each worth CHF 25,000, awarded by the Universities of Geneva and St, Gallen, and the Swiss Federal Institute of Technology in Zurich (ETHZ) and Lausanne (EPFL).

    The award ceremony for the 34th National Latsis Prize will be held at Berne Town Hall on 11 January 2018. Journalists can register by sending an email to: com@snf.ch.
    _________________________________________________________________________

    See the full article here .

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    EPFL campus

    EPFL is Europe’s most cosmopolitan technical university with students, professors and staff from over 120 nations. A dynamic environment, open to Switzerland and the world, EPFL is centered on its three missions: teaching, research and technology transfer. EPFL works together with an extensive network of partners including other universities and institutes of technology, developing and emerging countries, secondary schools and colleges, industry and economy, political circles and the general public, to bring about real impact for society.

     
  • richardmitnick 4:20 pm on October 6, 2017 Permalink | Reply
    Tags: , , , Catalyst technology, The end goal is to break out those molecular building blocks—the protons and electrons—to make fuels such as hydrogen   

    From BNL: “New Efficient Catalyst for Key Step in Artificial Photosynthesis” 

    Brookhaven Lab

    October 3, 2017
    Karen McNulty Walsh
    kmcnulty@bnl.gov
    (631) 344-8350

    Peter Genzer,
    genzer@bnl.gov
    (631) 344-3174

    Process sets free protons and electrons that can be used to make fuels.

    1
    Research team leader Javier Concepcion (standing, left) with Yan Xie, David Shaffer, and David Szalda

    Chemists at the U.S. Department of Energy’s Brookhaven National Laboratory have designed a new catalyst that speeds up the rate of a key step in “artificial photosynthesis”—an effort to mimic how plants, algae, and some bacteria harness sunlight to convert water and carbon dioxide into energy-rich fuels. This step—called water oxidation—releases protons and electrons from water molecules, producing oxygen as a byproduct.

    This “single-site” catalyst—meaning the entire reaction sequence takes place on a single catalytic site of one molecule—is the first to match the efficiency of the catalytic sites that drive this reaction in nature. The single-site design and high efficiency greatly improve the potential for making efficient solar-to-fuel conversion devices.

    “The end goal is to break out those molecular building blocks—the protons and electrons—to make fuels such as hydrogen,” said David Shaffer, a Brookhaven research associate and lead author on a paper describing the work in the Journal of the American Chemical Society. “The more efficient the water oxidation cycle is, the more energy we can store.”

    But breaking apart water molecules isn’t easy.

    “Water is very stable,” said Brookhaven chemist Javier Concepcion, who led the research team. “Water can undergo many boiling/condensing cycles and it stays as H2O. To get the protons and electrons out, we need to make the water molecules react with each other.”

    The catalyst acts as a chemical handler, shuffling around the water molecules’ assets—electrons, hydrogen ions (protons), and oxygen atoms—to get the reaction to happen.


    Bubbles indicate the rapid production of oxygen (O2) when the catalyst is added to the solution. For each O2 molecule produced, four protons (H+) and four electrons are released—enough to make two hydrogen (H2) molecules. No video credit.

    The new catalyst design builds on one the group developed last year, led by graduate student Yan Xie, which was also a single-site catalyst, with all the components needed for the reaction on a single molecule. This approach is attractive because the scientists can optimize how the various parts are arranged so that reacting molecules come together in just the right way. Such catalysts don’t depend on the free diffusion of molecules in a solution to achieve reactions, so they tend to continue functioning even when fixed to a surface, as they would be in real-world devices.

    “We used computer modeling to study the reactions at the theoretical level to help us design our molecules,” Concepcion said. “From the calculations we have an idea of what will work or not, which saves time before we get into the lab.”

    In both Xie’s design and the new improvement, there’s a metal at the core of the molecule, surrounded by other components the scientists can choose to give the catalyst particular properties. The reaction starts by oxidizing the metal, which pulls electrons away from the oxygen on a water molecule. That leaves behind a “positively charged,” or “activated,” oxygen and two positively charged hydrogens (protons).

    “Taking electrons away makes the protons easier to release. But you need those protons to go somewhere. And it’s more efficient if you remove the electrons and protons at the same time to prevent the build-up of excess charges,” Concepcion said. “So Xie added phosphonate groups as ligands on the metal to act as a base that would accept those protons,” he explained. Those phosphonate groups also made it easier to oxidize the metal to remove the electrons in the first place.

    But there was still a problem. In order to activate the H2O molecule, you first need it to bind to the metal atom at the center of the catalyst.

    In the first design, the phosphonate groups were so strongly bound to the metal that they were preventing the water molecule from binding to the catalyst early enough to keep the process running smoothly. That slowed the catalytic cycle down.

    So the team made a substitution. They kept one phosphonate group to act as the base, but swapped out the other for a less-tightly-bound carboxylate.

    “The carboxylate group can more easily adjust its coordination to the metal center to allow the water molecule to come in and react at an earlier stage,” Shaffer said.

    “When we are trying to design better catalysts, we first try to figure out what is the slowest step. Then we redesign the catalyst to make that step faster,” he said. “Yan’s work made one step faster, and that made one of the other steps end up being the slowest step. So in the current work we accelerated that second step while keeping the first one fast.”

    The improvement transformed a catalyst that created two or three oxygen molecules per second to one that produces more than 100 per second—with a corresponding increase in the production of protons and electrons that can be used to create hydrogen fuel.

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    The new catalyst has a ruthenium (Ru) atom at its core, a “pendant” phosphonate group to act as a base that accepts protons (H+) from water, and a more flexible, or “labile,” carboxylate group that facilitates the interaction of the catalyst with water. No image credit.

    “That’s a rate that is comparable to the rate of this reaction in natural photosynthesis, per catalytic site,” Concepcion said. “The natural photosynthesis catalyst has four metal centers and ours only has one,” he explained. “But the natural system is very complex with thousands and thousands of atoms. It would be extremely hard to replicate something like that in the lab. This is a single molecule and it does the same function as that very complex system.”

    The next step is to test the new catalyst in devices incorporating electrodes and other components for converting the protons and electrons to hydrogen fuel—and then later, with light-absorbing compounds to provide energy to drive the whole reaction.

    “We have now systems that are working quite well, so we are very hopeful,” Concepcion said.

    This work was supported by the DOE Office of Science.

    Scientific paper: Lability and Basicity of Bipyridine-Carboxylate-Phosphonate Ligand Accelerate Single-Site Water Oxidation by Ruthenium-Based Molecular Catalysts JACS

    See the full article here .

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    One of ten national laboratories overseen and primarily funded by the Office of Science of the U.S. Department of Energy (DOE), Brookhaven National Laboratory conducts research in the physical, biomedical, and environmental sciences, as well as in energy technologies and national security. Brookhaven Lab also builds and operates major scientific facilities available to university, industry and government researchers. The Laboratory’s almost 3,000 scientists, engineers, and support staff are joined each year by more than 5,000 visiting researchers from around the world. Brookhaven is operated and managed for DOE’s Office of Science by Brookhaven Science Associates, a limited-liability company founded by Stony Brook University, the largest academic user of Laboratory facilities, and Battelle, a nonprofit, applied science and technology organization.
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  • richardmitnick 7:38 am on June 20, 2017 Permalink | Reply
    Tags: , Catalyst technology, Copper catalysts, Copper is one of the few catalysts that can produce ethanol at room temperature, Discovery could lead to sustainable ethanol made from carbon dioxide, Ethanol and propanol, , , SUNCAT Center for Interface Science and Catalysis   

    From Stanford: “Discovery could lead to sustainable ethanol made from carbon dioxide” 

    Stanford University Name
    Stanford University

    June 19, 2017
    Mark Shwartz

    1
    Thomas Jaramillo (left) & Christopher Hahn (credit: Mark Shwartz).

    “Copper is one of the few catalysts that can produce ethanol at room temperature,” he said. “You just feed it electricity, water and carbon dioxide, and it makes ethanol. The problem is that it also makes 15 other compounds simultaneously, including lower-value products like methane and carbon monoxide. Separating those products would be an expensive process and require a lot of energy.”

    Scientists would like to design copper catalysts that selectively convert carbon dioxide into higher-value chemicals and fuels, like ethanol and propanol, with few or no byproducts. But first they need a clear understanding of how these catalysts actually work. That’s where the recent findings come in.

    Copper crystals

    For the PNAS study, the Stanford team chose three samples of crystalline copper, known as copper (100), copper (111) and copper (751). Scientists use these numbers to describe the surface geometries of single crystals.

    “Copper (100), (111) and (751) look virtually identical but have major differences in the way their atoms are arranged on the surface,” said Christopher Hahn, an associate staff scientist at SLAC and co-lead lead author of the study. “The essence of our work is to understand how these different facets of copper affect electrocatalytic performance.”

    2
    Atoms aligned on the surface of copper (751) crystal. (Illustration: Christopher Hahn/SLAC National Accelerator Laboratory).

    In previous studies, scientists had created single-crystal copper electrodes just 1-square millimeter in size.

    “With such a small crystal, it’s hard to identify and quantify the molecules that are produced on the surface,” Hahn explained. “This leads to difficulties in understanding the chemical reactions, so our goal was to make larger copper electrodes with the surface quality of a single crystal.”

    To create bigger samples, Hahn and his co-workers at SLAC developed a novel way to grow single crystal-like copper on top of large wafers of silicon and sapphire.

    “What Chris did was amazing,” Jaramillo said. “He made films of copper (100), (111) and (751) with 6-square centimeter surfaces. That’s 600 times bigger than typical single crystals.

    Catalytic performance

    To compare electrocatalytic performance, the researchers placed the three large electrodes in water, exposed them to carbon dioxide gas and applied a potential to generate an electric current.

    The results were clear. When a specific voltage was applied, the electrodes made of copper (751) were far more selective to liquid products, such as ethanol and propanol, than those made of copper (100) or (111). The explanation may lie in the different ways that copper atoms are aligned on the three surfaces.

    3
    Photo: Christopher Hahn sees his reflection on the shiny surface of a copper (751) sample. (credit: Mark Shwartz).

    “In copper (100) and (111), the surface atoms are packed close together, like a square grid and a honeycomb, respectively” Hahn said. “As a result, each atom is bonded to many other atoms around it, and that tends to make the surface more inert.”

    But in copper (751), the surface atoms are further apart.

    “An atom of copper (751) only has two nearest neighbors,” Hahn said. “But an atom that isn’t bonded to other atoms is quite unhappy, and that makes it want to bind stronger to incoming reactants like carbon dioxide. We believe this is one of the key factors that lead to better selectivity to higher-value products, like ethanol and propanol.”

    Ultimately, the Stanford team would like to develop a technology capable of selectively producing carbon-neutral fuels and chemicals at an industrial scale.

    “The eye on the prize is to create better catalysts that have game-changing potential by taking carbon dioxide as a feedstock and converting it into much more valuable products using renewable electricity or sunlight directly,” Jaramillo said. “We plan to use this method on nickel and other metals to further understand the chemistry at the surface. We think this study is an important piece of the puzzle and will open up whole new avenues of research for the community.”

    Jaramillo also serves at deputy director of the SUNCAT Center for Interface Science and Catalysis, a partnership of the Stanford School of Engineering and SLAC.

    The study was also written by co-lead author Toru Hatsukade, Drew Higgins and Stephanie Nitopi at Stanford; Youn-Geun Kim at SLAC; and Jack Baricuatro and Manuel Soriaga at the California Institute of Technology.

    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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  • richardmitnick 7:09 am on April 25, 2017 Permalink | Reply
    Tags: 4-in-1 catalyst, , , Catalyst technology, Researchers develop eco-friendly   

    From Brown: “Researchers develop eco-friendly, 4-in-1 catalyst” 

    Brown University
    Brown University

    April 24, 2017
    Kevin Stacey
    kevin_stacey@brown.edu
    401-863-3766

    1
    More reactions, less waste. Catalysts like this new one developed at Brown University might help make industrial chemistry more sustainable. Sun lab / Seto lab / Brown University

    Brown University researchers have developed a new composite catalyst that can perform four separate chemical reactions in sequential order and in one container to produce compounds useful in making a wide range of pharmaceutical products.

    “It normally takes multiple catalysts to carry out all of the steps of this reaction,” said Chao Yu, a post-doctoral researcher at Brown who co-led the work with graduate student Xuefeng Guo. “But we found a single nanocatalyst that can perform this multistep reaction by itself.”

    The research, described in the Journal of the American Chemical Society, was a collaboration between the labs of Brown professors Christopher Seto and Shouheng Sun, who are coauthors of the paper.

    The work was done, the researchers said, with an eye toward finding ways of making the chemical industry more environmentally sustainable. Multi-reaction catalysts like this one are a step toward that goal.

    “If you’re running four different reactions separately, then you’ve got four different steps that require solvents and starting materials, and they each leave behind waste contaminated with byproducts from the reaction,” Seto said. “But if you can do it all in one pot, you can use less solvent and reduce waste.”

    The team made their new catalyst by growing silver-palladium nanoparticles on the surface of nanorods made of oxygen-deficient tungsten-oxide (tungsten-oxide with a few of its oxygen atoms missing). The researchers showed that it could catalyze the series of reactions needed to convert common starting materials formic acid, nitrobenzene and an aldehyde into a benzoxazole, which can be used to make antibacterials, antifungals and NSAID painkillers. The researchers showed that the catalyst could also be used to create another compound, quinazoline, which is used in a variety of anti-cancer drugs.

    Experiments showed that the catalyst could perform the four reactions with a nearly quantitative yield — meaning it produces the maximum possible amount of product for a given amount of starting materials. The reactions were performed at a lower temperature, in a shorter amount of time, and using solvents that are more environmentally friendly than those normally used for these reactions.

    “The temperature we used to synthesize this product is around 80 degrees Celsius,” Guo said. “Normally the reaction happens around 130 degrees and you need to run the reaction for one or two days. But we can get a similar yield at 80 degrees in eight hours.”

    The new catalyst also is able to make the benzoxazole compounds using starting materials that are more environmentally benign than those generally used. The reaction chain requires a hydrogen source for its initial step. That source could be pure hydrogen gas, which is difficult to store and transport, or it could be extracted from a chemical compound. A compound called ammonia borane is often used for this purpose, but the new catalyst enables formic acid to be used instead, which is “cheaper, greener and less toxic,” Yu said.

    And while many catalysts tested in these reactions cannot be used more than once without severely damaging their efficiency, the researchers were able to use the new catalyst up to five times with little drop-off in reaction yield.

    Sun says that studies like this one represents an emerging line of research in greener chemistry.

    “Normally in catalysis we’re doing one reaction at a time, with a different catalyst for each reaction” said Shouheng Sun, a professor of chemistry at Brown. “But there’s growing interest in coming up with catalysts that can perform multiple reactions in one pot, and that’s what we’ve done here.”

    The work was supported in part by the U.S. Army Research Laboratory and the U.S. Army Research Office (W911NF-15-1-0147).

    See the full article here .

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    Welcome to Brown

    Brown U Robinson Hall
    Located in historic Providence, Rhode Island and founded in 1764, Brown University is the seventh-oldest college in the United States. Brown is an independent, coeducational Ivy League institution comprising undergraduate and graduate programs, plus the Alpert Medical School, School of Public Health, School of Engineering, and the School of Professional Studies.

    With its talented and motivated student body and accomplished faculty, Brown is a leading research university that maintains a particular commitment to exceptional undergraduate instruction.

    Brown’s vibrant, diverse community consists of 6,000 undergraduates, 2,000 graduate students, 400 medical school students, more than 5,000 summer, visiting and online students, and nearly 700 faculty members. Brown students come from all 50 states and more than 100 countries.

    Undergraduates pursue bachelor’s degrees in more than 70 concentrations, ranging from Egyptology to cognitive neuroscience. Anything’s possible at Brown—the university’s commitment to undergraduate freedom means students must take responsibility as architects of their courses of study.

     
  • richardmitnick 5:31 pm on December 1, 2016 Permalink | Reply
    Tags: , Catalyst technology, MoS2,   

    From NC State: “New Findings Boost Promise of Molybdenum Sulfide for Hydrogen Catalysis” 

    NC State bloc

    North Carolina State University

    December 1, 2016
    Linyou Cao
    919.515.5407
    linyou_cao@ncsu.edu

    Matt Shipman
    919.515.6386
    matt_shipman@ncsu.edu

    1

    Researchers from North Carolina State University, Duke University and Brookhaven National Laboratory have found that molybdenum sulfide (MoS2) holds more promise than previously thought as a catalyst for producing hydrogen to use as a clean energy source. Specifically, the researchers found that the entire surface of MoS2 can be used as a catalyst, not just the edges of the material.

    “The key finding here is that the intrinsic catalytic performance of MoS2 is much better than the research community thought,” says Linyou Cao, an associate professor of materials science and engineering at NC State and senior author of a paper describing the work. “We’re optimistic that this can be a step toward making hydrogen a larger part of our energy portfolio.”

    Hydrogen promises clean energy, producing only water as a byproduct. But to create hydrogen for use as a clean energy source, ideally you’d be able to isolate the hydrogen gas from water – with the only byproduct being oxygen.

    However, the key to creating hydrogen from water – a process called hydrogen evolution – is an efficient catalyst. Currently, the best catalyst is platinum, which is too expensive for widespread use.

    Another candidate for a hydrogen evolution catalyst is MoS2, which is both inexpensive and abundant. But it has long been thought that MoS2 is of limited utility, based on the conventional wisdom that only the edges of MoS2 act as catalysts – leaving the bulk of the material inactive.

    But the new findings from NC State, Duke and Brookhaven show that the surface of MoS2 can be engineered to maximize the catalytic efficiency of the material. And the key to this efficiency is the number of sulfur vacancies in the MoS2.

    If you think of the crystalline structure of MoS2 as a grid of regularly spaced molybdenum and sulfur atoms, a sulfur vacancy is what happens when one of those sulfur atoms is missing.

    “We found that these sulfur vacancies attract the hydrogen atoms in water at just the right strength: the attraction is strong enough pull the hydrogen out of the water molecule, but is then weak enough to let the hydrogen go,” says Cao.

    The researchers also found that the grain boundaries of MoS2 , which have been speculated by the research community to be catalytically active for hydrogen evolution, may only provide trivial activity. Grain boundaries are the boundaries between crystalline domains.

    The findings point to a new direction for improving the catalytic performance of MoS2 . Currently, the most common way is to increase the number of edge sites, because of the conventional wisdom that only the edge sites are catalytically active.

    “Our result indicates that grain boundaries should not be the factor to consider when thinking about improving catalytic activity,” Cao says. “The best way to improve the catalytic activities is to engineer sulfur vacancies. The edges of MoS2 are still twice as efficient at removing hydrogen atoms compared to the sulfur vacancies. But it’s difficult to create a high density of edges in MoS2 – a lot of the material’s area is wasted – whereas a large number of sulfur vacancies can be engineered uniformly across the material.”

    The researchers have also found that there is a “sweet spot” for maximizing the catalytic efficiency of MoS2 .

    “We get the best results when between 7 and 10 percent of the sulfur sites in MoS2 are vacant,” Cao says. “If you go higher or lower than that range, catalytic efficiency drops off significantly.”

    Additionally, the researchers found that the crystalline quality of MoS2 is important to optimize the catalytic activity of the sulfur vacancies. The sulfur vacancies in high crystalline quality MoS2 showed better efficiency than those in low crystalline quality MoS2 , even when the densities of the vacancies are the same.

    “In order to get the best output from sulfur vacancies, the crystalline quality of MoS2 needs to be very high,” says Guoqing Li, a Ph.D. student at NC State and lead author of the paper. “The ideal scenario would be 7 to 10 percent sulfur vacancies uniformly distributed in a single crystalline MoS2 film.”

    The work was done using MoS2 thin films that are only three atoms thick. Using these engineered thin films, the researchers were able to achieve catalytic efficiency comparable to previous MoS2 technologies that relied on having two or three orders of magnitude more surface area.

    “We now know that MoS2 is a more promising catalyst than we anticipated, and are fine-tuning additional techniques to further improve its efficiency,” Cao says. “Hopefully, this moves us closer to making a low-cost catalyst that is at least as good as platinum.”

    The paper, All the Catalytic Active Sites of MoS2 for Hydrogen Evolution,” is published in the Journal of the American Chemical Society. The paper was co-authored by Yifei Yu, David Peterson, Abdullah Zafar, Raj Kumar, Frank Hunte and Steve Shannon of NC State; Du Zhang, Stefano Curtarolo and Weitao Yang of Duke; and Qiao Qiao and Yimei Zhu of Brookhaven National Lab.

    The work was done with support from the Department of Energy’s Office of Science, under grants DE-SC0012575 and DE-SC0012704, as well as by the National Science Foundation under grant PHY1338917.

    See the full article here .

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    NC State was founded with a purpose: to create economic, societal and intellectual prosperity for the people of North Carolina and the country. We began as a land-grant institution teaching the agricultural and mechanical arts. Today, we’re a pre-eminent research enterprise that excels in science, technology, engineering, math, design, the humanities and social sciences, textiles and veterinary medicine.

    NC State students, faculty and staff take problems in hand and work with industry, government and nonprofit partners to solve them. Our 34,000-plus high-performing students apply what they learn in the real world by conducting research, working in internships and co-ops, and performing acts of world-changing service. That experiential education ensures they leave here ready to lead the workforce, confident in the knowledge that NC State consistently rates as one of the best values in higher education.

     
  • richardmitnick 11:59 am on September 9, 2016 Permalink | Reply
    Tags: , , Catalyst technology, Catalytically active gold nanoparticles,   

    From BNL: “Collaboration Strikes Gold Pioneering a New Method for Catalyst Production” 

    Brookhaven Lab

    September 7, 2016
    Alexander Orlov
    Karen McNulty Walsh

    1
    Stony Brook University graduate student Qiyuan Wu and Brookhaven Lab Center for Functional Nanomaterials (CFN) staff scientist Dmitri Zakharov studying samples at the Titan Environmental Transmission Electron Microscope at the CFN. No image credit.

    An ultra-high-vacuum chamber with temperatures approaching absolute zero—the coldest anything can get—may be the last place you would expect to find gold. But a group of researchers from Stony Brook University (SBU) in collaboration with scientists at the Air Force Research Lab (AFRL) and the U.S. Department of Energy’s (DOE) Brookhaven National Laboratory have just demonstrated that such a desolate place is ideal for producing catalytically active gold nanoparticles. A paper describing the first catalyst ever produced using their new method, called Helium Nanodroplet Deposition (HND), was recently published in the Journal of Physical Chemistry Letters.

    As lead researcher Alexander Orlov of SBU explains, HND works by boiling gold atoms in a vacuum to produce a vapor. The vaporized gold is then “picked up” by an extremely cold jet stream of liquid helium droplets that act to literally strike gold clusters against a solid collector downstream. Upon striking the collector, the liquid helium droplets instantly evaporate releasing helium gas and leaving behind unprecedentedly pure and stable gold nanoparticles.

    2
    This atomic-resolution image shows how single-nanometer-scale gold particles (round features at the top of the image), created by a “helium nandroplet deposition” method, sit on top of a single-crystal titanium dioxide support substrate (bottom portion of the image). The image was made using a scanning transmission electron microscope at the Center for Functional Nanomaterials at Brookhaven National Laboratory. No image credit.

    “This new method to produce active nanoparticles offers unique opportunities to create materials with unprecedented properties to solve energy and environmental problems,” Orlov said. “Our Brookhaven and AFRL collaborators made it possible for our students to access the most unique facilities in the world, which made all the difference in our research.”

    Qiyuan Wu, a graduate student working in Orlov’s laboratory and first author on the paper, performed much of the work to develop the method. Michael Lindsay and Claron Ridge of AFRL provided state-of-the-art facilities at Eglin Air Force Base, one of only a few places in the world with the capabilities required to generate the gold nanoparticles using the new technique. And a team at the Center for Functional Nanomaterials (CFN), a DOE Office of Science User Facility at Brookhaven Lab, used advanced imaging and characterization tools to study the nanoparticles’ catalytic activity.

    Specifically, Brookhaven scientists Eric Stach and Dmitri Zakharov of the CFN and Shen Zhao, then a postdoctoral fellow working under Stach, developed a method to deposit the gold nanoparticles onto a “catalyst support” structure they use for characterizing the stability of other nanomaterials. They then studied the characteristics of the nanoparticles, including their stability under reaction conditions, using the Titan Environmental Transmission Electron Microscope at the CFN. Further characterization by Zhao and CFN staff member Dong Su using aberration-corrected Scanning Transmission Electron Microscopy allowed the SBU researchers to understand how the droplets form.

    “This was part of a User project, that morphed into a collaboration,” said Stach, who leads the electron microscopy group at CFN. “It was a very nice study”—and an example of how the Office of Science User Facilities offer not just unique scientific equipment but also scientific expertise that can be essential to the success of a research project.

    Nanoparticles are of high research interest due to their improved properties compared to bulk materials. They have revolutionized technologies aimed at improving sustainability such as fuel cells, photocatalysts, and solar panels. The gold nanoparticle catalysts produced in this study are capable of converting poisonous carbon monoxide gas into carbon dioxide gas, an essential reaction that occurs in the catalytic converters of cars to reduce pollution and lower impacts on the environment.

    According to Orlov, the HND method is not limited to the production of gold nanoparticles, but can be applied to nearly all metals and can even produce challenging multi-metallic nanoparticles. The technique’s versatility and ability to produce clean and well-defined samples make it a powerful tool for the discovery of new catalysts and studying factors that affect catalyst performance.

    3
    Schematic of the Helium Nanodroplet Deposition method: A temperature-controlled nozzle produces an extremely cold jet stream of liquid helium droplets (blue bubbles) that pick up vaporized gold atoms (produced by boiling gold in a vacuum chamber). When the liquid helium droplets containing the gold vapor strike a solid collector downstream, the helium evaporates leaving behind unprecedentedly pure and stable gold nanoparticles. No image credit.

    The collaboration is currently researching how the parameters of HND can be adjusted to control catalyst performance.

    This research was funded by the Division of Materials Research at the National Science Foundation and the Air Force Office of Scientific Research. The work at CFN was funded by the DOE Office of Science.

    See the full article here .

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    One of ten national laboratories overseen and primarily funded by the Office of Science of the U.S. Department of Energy (DOE), Brookhaven National Laboratory conducts research in the physical, biomedical, and environmental sciences, as well as in energy technologies and national security. Brookhaven Lab also builds and operates major scientific facilities available to university, industry and government researchers. The Laboratory’s almost 3,000 scientists, engineers, and support staff are joined each year by more than 5,000 visiting researchers from around the world.Brookhaven is operated and managed for DOE’s Office of Science by Brookhaven Science Associates, a limited-liability company founded by Stony Brook University, the largest academic user of Laboratory facilities, and Battelle, a nonprofit, applied science and technology organization.
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  • richardmitnick 7:06 am on September 2, 2016 Permalink | Reply
    Tags: , Catalyst technology, , Linsey Seitz, SIMES, , ,   

    From SLAC: Women in STEM – “SLAC, Stanford Team Finds a Tough New Catalyst for Use in Renewable Fuels Production” Linsey Seitz 


    SLAC Lab

    September 1, 2016

    Discovery Could Make Water-splitting Reaction Cheaper, More Efficient

    Researchers at Stanford University and the Department of Energy’s SLAC National Accelerator Laboratory have developed a tough new catalyst that carries out a solar-powered reaction 100 times faster than ever before, works better as time goes on and stands up to acid.

    And because it requires less of the rare and costly metal iridium, it could bring down the cost of a process that mimics photosynthesis by using sunlight to split water molecules – a key step in a renewable, sustainable pathway to produce hydrogen or carbon-based fuels that can power a broad range of energy technologies.

    The team published their results today in the journal Science.

    1
    A simulation shows one possible way that a highly active iridium oxide layer could form on the surface of a strontium iridium oxide catalyst. Experiments by SLAC and Stanford researchers showed that strontium atoms (green spheres) left the top layer through a corrosion process during the catalyst’s first two hours of operation. The top layer then rearranged itself and became much better at accelerating chemical reactions. Follow-up X-ray studies at SLAC will examine these surface changes in more detail. (C.F. Dickens/Stanford University)

    A Multi-pronged Search

    The discovery of the catalyst – a very thin film of iridium oxide layered on top of strontium iridium oxide – was the result of an extensive search by three groups of experts for a more efficient way to accelerate the oxygen evolution reaction, or OER, which is half of a two-step process for splitting water with sunlight.

    “The OER has been a real bottleneck, particularly in acidic conditions,” said Thomas Jaramillo, an associate professor at SLAC and Stanford and deputy director of the SUNCAT Center for Interface Science and Catalysis. “The only reasonably active catalysts we know that can survive those harsh conditions are based on iridium, which is one of the rarest metals on Earth. If we want to bring down the cost of such a pathway for making fuels from renewable sources and carry it out on a much larger scale, we need to develop catalyst materials that are more active and that use little or no iridium.”

    The search started with SUNCAT theorists, who used computers to explore a database of materials and find the ones with the most potential to do exactly what was needed. Catalysts accelerate chemical reactions without being used up in the process, and databases like this one have become an important tool for designing catalysts to order, rather than testing thousands of materials in a time-consuming, trial-and-error approach.

    Based on the results, a team led by SLAC Staff Scientist Yasuyuki Hikita and SLAC/Stanford Professor Harold Hwang, both investigators with the Stanford Institute for Materials and Energy Sciences (SIMES), synthesized one of the catalyst candidates, strontium iridium oxide. Linsey Seitz, a PhD student in Jaramillo’s group and first author of the report, investigated the material’s properties.

    2
    Stanford PhD student Linsey Seitz investigated the properties of a tough new catalyst material that carries out a key water-splitting reaction in acid. She is now a Helmholtz postdoctoral fellow at the Karlsruhe Institute of Technology in Germany. (Jesse D. Benck/Stanford University)

    3
    Sample of a new catalyst material created by SLAC and Stanford researchers. It’s 100 times better than previous catalysts at accelerating the oxygen-evolving reaction in acid, a key step in a pathway for making sustainable fuels. (Linsey Seitz/Stanford University)

    4
    Images made with an atomic force microscope show variations in the height of the catalyst’s surface before (left) and after its first 30 hours of operation. The observed changes in surface texture reflect strontium atoms leaving the top layers of the material during operation, forming a very catalytically active thin film of iridium oxide. (L. Seitz et. al., Science)

    A Surprising Improvement

    To the team’s surprise, this catalyst worked even better than expected, and kept improving over the first two hours of operation. Experiments probing the surface of the material indicated that a corrosion process released strontium atoms into the surrounding fluid during this initial period. This left a film of iridium oxide just a few atomic layers thick that was much more active than the original material, and 100 times more efficient at promoting the OER than any other acid-stable catalyst known to date.

    “A lot of materials do this type of thing – surfaces can be very dynamic, changing during the course of a reaction – but in this case the catalyst changes in a way that gives you excellent performance in acid,” Jaramillo said. “This is unusual, because under these conditions most materials are either poor catalysts or they completely fall apart, or both.”

    The researchers still don’t know exactly why this surface layer is so active, although the theorists, including SUNCAT graduate students Colin Dickens and Charlotte Kirk, have provided some ideas. Jaramillo’s group will be taking a closer look at the catalyst with X-ray beams at SLAC’s Stanford Synchrotron Radiation Lightsource, a DOE Office of Science User Facility, to determine exactly how the atoms on the surface rearrange themselves and why this boosts the catalyst’s performance.

    SLAC SSRL Tunnel
    SLAC SSRL

    “To make a commercially viable catalyst we will need to reduce the amount of iridium in the material even more,” said Jens Nørskov, director of SUNCAT and a professor at SLAC and Stanford. “But there are many possibilities, and this gives us some very good leads.”

    SUNCAT and SIMES are joint institutes of Stanford and SLAC. Major funding for the project came from the DOE Office of Science.

    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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  • richardmitnick 9:16 am on May 9, 2016 Permalink | Reply
    Tags: , Catalyst technology, , TUM opens central institute for catalysis research   

    From TUM: “TUM opens central institute for catalysis research” 

    Techniche Universitat Munchen

    Techniche Universitat Munchen

    09.05.2016
    Dr. Andreas Battenberg

    1
    The TUM Catalysis Research Center seen from the east – Photo: Andreas Heddergott / TUM

    New research facility inaugurated in Garching

    With the inauguration of the TUM Catalysis Research Center (CRC), the Technical University of Munich (TUM) sets an international highlight in the field of catalysis research. Scientists from five departments, as well as industrial cooperation partners, will collaborate on research under one roof to meet the challenges of energy and resource saving production of chemical raw materials, fine chemicals and pharmaceutical products. Due to the supra-regional significance of the center, the German Federal Ministry of Education and Research (BMBF) contributed to the total construction cost of 84.5 million euro for the newly erected facility.

    Catalysts are the key to sustainable, energy and resource conserving chemical conversion of materials. The use of biogenic raw materials in the future, as well as the extraction, storage and conversion of energy depends on advances in applied catalyst research. The global market for catalysts has topped 18 billion euros and continues to grow. Yet, even fundamental problems like the catalytic utilization of natural gas (methane) to produce refined intermediary chemical products remain unsolved.

    In its new research facility, the TU Munich will tackle the interdisciplinary challenges of modern catalysis as a systems science, bundling available competency from the Departments of Chemistry and Physics and augmenting them with approaches from engineering, computer science and mathematics.

    “In this kind of research, there are no longer borders between the classical disciplines of engineering and natural sciences. Under the shared roof of the Catalysis Research Center we bring widely divergent methodological approaches to convergence,” says TUM President Prof. Wolfgang A. Hermann, who, himself a catalysis researcher, initiated the new research facility. “The product diversity of our technological society will be feasible in the future only if valuable products are produced, excess products decomposed and harmful products avoided through the use of specific catalysts.”

    One of a kind research infrastructure

    The Catalyst Research Center is tightly linked methodically and thematically with existing campus facilities like the Departments of Chemistry, Physics, Mechanical Engineering, Mathematics, and Computer Science, as well as the research center for white biotechnology and the TUM International Graduate School of Science and Engineering (IGSSE), a result of the Excellence Initiative 2006. This is flanked by the newly founded research center for synthetic biotechnology (supported by the Werner Siemens-Stiftung) and various infrastructure facilities, in particular the research neutron source of the Bavarian NMR Center and the supercomputers of the Leibniz Computing Center.

    The center is also home to the strategic research alliance “Munich Catalysis” (MuniCat). In the vein of the “Industry on Campus” concept, TUM scientists work here in collaboration with researchers of Clariant AG to answer important questions in basic and applied research in the field of chemical catalysis. The Wacker Institute of Silicon Technology is a further topically integrated partner in the research program.

    New professorships

    TUM used the planning and construction phases to establish new catalysis-relevant professorships. It extended the spectrum with professorships of bio-organic chemistry, computer-aided biocatalysis, industrial biocatalysis, technical electrochemistry, physical chemistry/catalysis, silicon chemistry, solid body NMR spectroscopy, biomolecular NMR spectroscopy, selective separation technology and systems biology.

    Associated with the CRC are research activities of the Competence Center for Renewable Raw Materials in Straubing where, among other things, ethanol is produced biocatalytically from agricultural products. “The completed expansion of the biochemical and biophysical research facilities at TUM – also with multiple new professorships – strengthens the catalysis focus in the biopharmaceutical domain,” said TUM President Wolfgang A. Hermann. Shortly a new building dedicated to protein research will be erected next to the Catalysis Research Center. “Thus, TUM is now positioned as an international leader with a coherent overall concept.”

    Research center with supraregional significance

    “Hardly any product of the chemical industry would be economically and ecologically feasible without catalysts. Catalysis research is thus a key technology – especially in a raw material poor country like Germany,” said Stefan Müller, parliamentary state secretary in the German Federal Ministry of Education and Research (BMBF). “The TU München is already doing world-class catalysis research. The new center will bolster this position significantly. The construction, which was supported with funding of almost 29 million euro from the BMBF, will thus make an important contribution to strengthening the research location Germany.”

    “With the Departments of Chemistry, Physics, Mechanical Engineering and Computer Science, the TUM neutron research source and the super computers of the Leibniz Computing Center, the research campus Garching has a one of a kind infrastructure worldwide,” said the Bavarian Economic Minister Dr. Ludwig Spaenle. “With the new Catalysis Research Center we have now created a site at which the existing synergies can converge and become effective. We are strengthening the international competitiveness of the scientific and economic regions of Bavaria and Germany with the new Catalysis Research Center.”

    Address: Ernst Otto Fischer-Str. 1

    The street address of new building is Ernst Otto Fischer-Str. 1. Fischer (1918 – 2007) pioneered in organometallic chemistry and was awarded the Nobel Prize in Chemistry in 1973. He held the Chair of Inorganic Chemistry at TUM from 1964 to 1984.

    See the full article here .

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    Techniche Universitat Munchin Campus

    Technische Universität München (TUM) is one of Europe’s top universities. It is committed to excellence in research and teaching, interdisciplinary education and the active promotion of promising young scientists. The university also forges strong links with companies and scientific institutions across the world. TUM was one of the first universities in Germany to be named a University of Excellence. Moreover, TUM regularly ranks among the best European universities in international rankings.

     
  • richardmitnick 7:20 pm on March 24, 2016 Permalink | Reply
    Tags: , Catalyst technology,   

    From SLAC: “New Catalyst is Three Times Better at Splitting Water” 


    SLAC Lab

    March 24, 2016

    With a combination of theory and clever, meticulous gel-making, scientists from the Department of Energy’s SLAC National Accelerator Laboratory and the University of Toronto have developed a new type of catalyst that’s three times better than the previous record-holder at splitting water into hydrogen and oxygen – the vital first step in making fuels from renewable solar and wind power.

    The research, published today in the journal Science, outlines a potential way to make a future generation of water-splitting catalysts from three abundant metals – iron, cobalt and tungsten – rather than the rare, costly metals that many of today’s catalysts rely on.

    1
    One way to store intermittent sun and wind energy is to use it to split water into oxygen and hydrogen, and then use the hydrogen as fuel. Now scientists at SLAC and the University of Toronto have invented a new type of catalyst that makes this process three times more efficient. In this water-splitting device on the Toronto campus, hydrogen is bubbling up from the left electrode and oxygen is bubbling up from the right one. (Marit Mitchell/University of Toronto)

    “The good things about this catalyst are that it’s easy to make, its production can be very easily scaled up without any super-advanced tools, it’s consistent, and it’s very robust,” said Aleksandra Vojvodic, a SLAC staff scientist with the SUNCAT Center for Interface Science and Catalysis who led the theoretical side of the work.
    Storing Sun and Wind Power

    Scientists have been searching for an efficient way to store electricity generated by solar and wind power so it can be used any time – not just when the sun shines and breezes blow. One way to do that is to use the electrical current to split water molecules into hydrogen and oxygen, and store the hydrogen to use later as fuel.

    This reaction takes place in several steps, each requiring a catalyst – a substance that promotes chemical reactions without being consumed itself – to move it briskly along. In this case the scientists focused on a step where oxygen atoms pair up to form a gas that bubbles away, which has been a bottleneck in the process.

    In previous work, Vojvodic and her SUNCAT colleagues had used theory and computation to look at water-splitting oxide catalysts that contain one or two metals and predict ways to make them more active. For this study, Edward H. Sargent, a professor of electrical and computer engineering at the University of Toronto, asked them to look at the effect of adding tungsten – a heavy, dense metal used in light bulb filaments and radiation shielding – to an iron-cobalt catalyst that worked, but not very efficiently.

    With the aid of powerful computers at SLAC and elsewhere and state-of-the-art computational tools, the SUNCAT team determined that adding tungsten should dramatically increase the catalyst’s activity – especially if the three metals could be mixed so thoroughly that their atoms were uniformly distributed near the active site of the catalyst, where the reaction takes place, rather than separating into individual clusters as they normally tend to do.

    “Tungsten is quite a large atom compared to the other two, and when you add a little bit of it, it expands the atomic lattice, and this affects the reaction not only geometrically but also electronically,” Vojvodic said. “We were able to understand, on the atomic scale, why it works, and then that was verified experimentally.”

    2
    Images of the tiny catalyst particles, made with electron energy loss spectroscopy, show how evenly metal atoms are distributed within the oxide material (Fe=iron, Co=cobalt, W=tungsten and O=oxygen). This extremely uniform distribution helps make the catalyst three times more efficient at splitting water than any previous one. Each frame here is about 4 nanometers wide, which is roughly the width of 40 hydrogen atoms. (B. Zhang et al./Science)

    Add Metal Atoms, Mix and Gel

    Based on that information, Sargent’s team developed a novel way to distribute the three metals uniformly within the catalyst: They dissolved the metals and other ingredients in a solution and then slowly turned the solution into a gel at room temperature, tweaking the process so the metal atoms did not clump together. The gel was then dried into a white powder whose particles were riddled with tiny pores, increasing the surface area where chemicals can attach and react with each other.

    In tests, the catalyst was able to generate oxygen gas three times faster, per unit weight, than the previous record-holder, Sargent said, and it also proved to be stable through hundreds of reaction cycles.

    “It’s a big advance, although there’s still more room to improve,” he said. “”And we will need to make catalysts and electrolysis systems even more efficient, cost effective and high intensity in their operation in order to drive down the cost of producing renewable hydrogen fuels to an even more competitive level.”

    Sargent said the researchers hope to use the same method to develop other three-metal catalysts for splitting water and also for splitting carbon dioxide, a greenhouse gas released by burning fossil fuels, to make renewable fuels and chemical feed stocks. He and five other members of the University of Toronto team have filed for a provisional patent on the technique for preparing the catalyst.

    Future Directions

    “There are a lot of things we further need to understand,” Vojvodic said. “Are there other abundant metals we can test as mixtures in oxides? What are the optimal mixtures of the components? How stable is the catalyst, and how can we scale up its production? It needs to be tested at the device level, really.”

    Jeffrey C. Grossman, a professor of materials science and engineering at MIT who was not involved in the study, said, “The work impressively highlights the power of tightly coupled computational materials science with advanced experimental techniques, and sets a high bar for such a combined approach. It opens new avenues to speed progress in efficient materials for energy conversion and storage.”

    SLAC research associate Michal Bajdich and Stanford postdoctoral researcher Max García-Melchor also contributed to this work, along with researchers from the DOE’s Brookhaven National Laboratory; East China University of Science & Technology, Tianjin University and the Beijing Synchrotron Radiation Facility in China; and the Canadian Light Source. The research was funded by a number of sources, including the Ontario Research Fund – Research Excellence Program, Natural Sciences and Engineering Research Council of Canada and the CIFAR Bio-Inspired Solar Energy Program, as well as the DOE Office of Science, which funds SUNCAT, and the SLAC Laboratory Directed Research and Development program.

    Citation: B. Zhang et al., Homogeneously dispersed, multimetal oxygen-evolving catalysts,Science, 24 March 2016 (10.1126/science.aaf1525)

    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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