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  • richardmitnick 11:06 am on October 9, 2015 Permalink | Reply
    Tags: , Catalyst technology,   

    From TUM: “Faster design – better catalysts” 

    Techniche Universitat Munchen

    Techniche Universitat Munchen

    Prof. Dr. Aliaksandr S. Bandarenka
    Technical University of Munich
    Physics of Energy Conversion and Storage
    James-Franck-Str. 1, 85748 Garching, Germany
    Tel.: +49 89 289 12531

    New method facilitates research on fuel cell catalysts

    The different number of similar neighbors has an important influence on the catalytic activity of surface atoms of a nanoparticle – Image: David Loffreda, CNRS, Lyon

    While the cleaning of car exhausts is among the best known applications of catalytic processes, it is only the tip of the iceberg. Practically the entire chemical industry relies on catalytic reactions. Catalyst design plays a key role in improving these processes. An international team of scientists has now developed a concept that elegantly correlates geometric and adsorption properties. They validated their approach by designing a new platinum-based catalyst for fuel cell applications.

    Hydrogen would be an ideal energy carrier: Surplus wind power could split water into its elements. The hydrogen could power fuel cell-driven electric cars with great efficiency. While the only exhaust would be water, the range could be as usual. But fuel cell vehicles are still a rare exception. The required platinum (Pt) is extremely expensive and the world’s annual output would not suffice for all cars.

    A key component of the fuel cell is the platinum catalyst that is used to reduce oxygen. It is well known that not the entire surface but only a few particularly exposed areas of the platinum, the so-called active centers, are catalytically active.

    A team of scientists from Technical University of Munich and Ruhr University Bochum (Germany), the Ecole normale superieure (ENS) de Lyon, Centre national de la recherche scientifique (CNRS), Universite Claude Bernard Lyon 1 (France) and Leiden University (Netherlands) have set out to determine what constitutes an active center.

    Studying the model

    A common method used in developing catalysts and in modeling the processes that take place on their surfaces is computer simulation. But as the number of atoms increases, quantum chemical calculations quickly become extremely complex.

    With their new methodology called “coordination-activity plots” the research team presents an alternative solution that elegantly correlates geometric and adsorption properties. It is based on the generalized coordination number (GCN) , which counts the immediate neighbors of an atom and the coordination numbers of its neighbors.

    Calculated with the new approach, a typical Pt (111) surface has a GCN value of 7.5. According to the coordination-activity plot, the optimal catalyst should, however, achieve a value of 8.3. The required larger number of neighbors can be obtained by inducing atomic-size cavities into the platinum surface, for example.

    Successful practical test

    In order to validate the accuracy of their new methodology, the researchers computationally designed a new type of platinum catalyst for fuel cell applications. The model catalysts were prepared experimentally using three different synthesis methods. In all three cases, the catalysts showed up to three and a half times greater catalytic activity.

    “This work opens up an entirely new way for catalyst development: the design of materials based on geometric rationales which are more insightful than their energetic equivalents,” says Federico Calle-Vallejo. “Another advantage of the method is that it is based clearly on one of the basic principles of chemistry: coordination numbers. This significantly facilitates the experimental implementation of computational designs.”

    “With this knowledge, we might be able to develop nanoparticles that contain significantly less platinum or even include other catalytically active metals,” says Professor Aliaksandr S. Bandarenka, tenure track professor at Technical University of Munich. “And in future we might be able to extend our method to other catalysts and processes, as well.”


    Finding optimal surface sites on heterogeneous catalysts by counting nearest neighbors, Federico Calle-Vallejo, Jakub Tymoczko, Viktor Colic, Quang Huy Vu, Marcus D. Pohl, Karina Morgenstern, David Loffreda, Philippe Sautet, Wolfgang Schuhmann, Aliaksandr S. Bandarenka. Science, october 9., 2015; DOI : 10.1126/science.aab3501

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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 8:25 am on September 15, 2015 Permalink | Reply
    Tags: , Catalyst technology,   

    From Wisconsin: “Discovery of a highly efficient catalyst eases way to hydrogen economy” 

    U Wisconsin

    University of Wisconsin

    Sept. 14, 2015
    David Tenenbaum

    Bathed in simulated sunlight, this photoelectrolysis cell in the lab of Song Jin splits water into hydrogen and oxygen using a catalyst made of the abundant elements cobalt, phosphorus and sulfur. Photos: David Tenenbaum

    Hydrogen could be the ideal fuel: Whether used to make electricity in a fuel cell or burned to make heat, the only byproduct is water; there is no climate-altering carbon dioxide.

    Like gasoline, hydrogen could also be used to store energy.

    Hydrogen is usually produced by separating water with electrical power. And although the water supply is essentially limitless, a major roadblock to a future “hydrogen economy” is the need for platinum or other expensive noble metals in the water-splitting devices.

    Noble metals resist oxidation and include many of the precious metals, such as platinum, palladium, iridium and gold.

    Song Jin

    “In the hydrogen evolution reaction, the whole game is coming up with inexpensive alternatives to platinum and the other noble metals,” says Song Jin, a professor of chemistry at the University of Wisconsin-Madison.

    In the online edition of Nature Materials that appears today, Jin’s research team reports a hydrogen-making catalyst containing phosphorus and sulfur — both common elements — and cobalt, a metal that is 1,000 times cheaper than platinum.

    Catalysts reduce the energy needed to start a chemical reaction. The new catalyst is almost as efficient as platinum and likely shows the highest catalytic performance among the non-noble metal catalysts reported so far, Jin reports.

    The advance emerges from a long line of research in Jin’s lab that has focused on the use of iron pyrite (fool’s gold) and other inexpensive, abundant materials for energy transformation. Jin and his students Miguel Cabán-Acevedo and Michael Stone discovered the new high-performance catalyst by replacing iron to make cobalt pyrite, and then added phosphorus.

    Although electricity is the usual energy source for splitting water into hydrogen and oxygen, “there is a lot of interest in using sunlight to split water directly,” Jin says.

    The new catalyst can also work with the energy from sunlight, Jin says. “We have demonstrated a proof-of-concept device for using this cobalt catalyst and solar energy to drive hydrogen generation, which also has the best reported efficiency for systems that rely only on inexpensive catalysts and materials to convert directly from sunlight to hydrogen.”

    Many researchers are looking to find a cheaper replacement for platinum, Jin says. “Because this new catalyst is so much better and so close to the performance of platinum, we immediately asked WARF (the Wisconsin Alumni Research Foundation) to file a provisional patent, which they did in just two weeks.”

    Many questions remain about a catalyst that has only been tested in the lab, Jin says. “One needs to consider the cost of the catalyst compared to the whole system. There’s always a tradeoff: If you want to build the best electrolyzer, you still want to use platinum. If you are able to sacrifice a bit of performance and are more concerned about the cost and scalability, you may use this new cobalt catalyst.”

    Strategies to replace a significant portion of fossil fuels with renewable solar energy must be carried out on a huge scale if they are to affect the climate crisis, Jin says. “If you want to make a dent in the global warming problem, you have to think big. Whether we imagine making hydrogen from electricity, or directly from sunlight, we need square miles of devices to evolve that much hydrogen. And there might not be enough platinum to do that.”

    The collaborative team included Professor J.R. Schmidt, a theoretical chemist at UW-Madison, and electrical engineering Professor Jr-Hau He and his students from King Abdullah University of Science and Technology in Saudi Arabia. The U.S. Department of Energy provided major funding for the study.

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    In achievement and prestige, the University of Wisconsin–Madison has long been recognized as one of America’s great universities. A public, land-grant institution, UW–Madison offers a complete spectrum of liberal arts studies, professional programs and student activities. Spanning 936 acres along the southern shore of Lake Mendota, the campus is located in the city of Madison.

  • richardmitnick 10:08 pm on September 14, 2015 Permalink | Reply
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    From ORNL: “New ORNL catalyst addresses engine efficiency, emissions quandary” 


    Oak Ridge National Laboratory

    September 14, 2015
    Ron Walli, Communications
    wallira@ornl.gov, 865.576.0226

    Researcher Andrew Binder and colleagues discovered that by mixing three components they could create an innovative catalyst that performs well at low temperatures without the use of precious metals.

    A catalyst being developed by researchers at the Department of Energy’s Oak Ridge National Laboratory could overcome one of the key obstacles still preventing automobile engines from running more cleanly and efficiently.

    The mixed oxide catalyst could solve the longstanding problem of inhibition, in which nitrogen oxides, carbon monoxide and hydrocarbons effectively clog the catalyst designed to cleanse a vehicle’s exhaust stream. This happens as these three pollutants compete for active surface sites on the catalyst. Now, however, ORNL’s low-cost catalyst composed of copper oxide, cobalt oxide and cerium oxide shows considerable promise when tested in simulated exhaust streams.

    “Our catalyst potentially fixes the inhibition problem without precious metals and could help more efficient engines meet upcoming stricter emission regulations,” said Todd Toops of ORNL’s Energy and Transportation Science Division. Toops noted that the unique formulation builds on previous work by colleagues Andrew Binder and Sheng Dai, who varied the composition of the three catalyst components in search of improved oxidation activity under simple conditions.

    Researchers also emphasized that the lower exhaust temperatures associated with efficiency gains pose additional challenges because conventional catalysts perform more efficiently at high temperatures. Hydrocarbons – and there are hundreds of species – pose perhaps the biggest challenge.

    “As we make engines more efficient, less wasted heat exits the engine into the exhaust system where catalysts clean up the pollutant emissions,” said Jim Parks, a member of the Energy and Transportation Science Division. “The lower temperatures in the exhaust from the more efficient engines are lower than the typical operating range of catalysts, so we need innovations like this catalyst to lower the operating range and control the engine pollutants.”

    This finding, published in the journal Angewandte Chemie, is encouraging, the authors note, as “vehicles with internal combustion engines will likely remain a dominant fraction of the light-duty fleet in both hybrid and conventional drivetrains.”

    Binder, Toops, Parks and Dai performed extensive tests using different ratios of copper oxide, cobalt oxide and ceria to determine the optimum ratio, which was initially evaluated at an atomic ratio of 1:5:5, respectively. Next, researchers will determine scalability of this approach and perform cost-benefit analyses. The paper, titled “Low Temperature CO Oxidation over Ternary Oxide with High Resistance to Hydrocarbon Inhibition,” is available at http://onlinelibrary.wiley.com/doi/10.1002/ange.201506093/abstract.

    DOE’s Office of Energy Efficiency and Renewable Energy, Vehicle Technologies Program, funded this research.

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    ORNL is managed by UT-Battelle for the Department of Energy’s Office of Science. DOE’s Office of Science is the single largest supporter of basic research in the physical sciences in the United States, and is working to address some of the most pressing challenges of our time.


  • richardmitnick 4:11 pm on September 10, 2015 Permalink | Reply
    Tags: , , Catalyst technology, , SLAC UED   

    From SLAC: “SLAC’s Ultrafast ‘Electron Camera’ Visualizes Ripples in 2-D Material” 

    SLAC Lab

    September 10, 2015

    Researchers have used SLAC’s experiment for ultrafast electron diffraction (UED), one of the world’s fastest “electron cameras,” to take snapshots of a three-atom-thick layer of a promising material as it wrinkles in response to a laser pulse. Understanding these dynamic ripples could provide crucial clues for the development of next-generation solar cells, electronics and catalysts. (SLAC National Accelerator Laboratory)

    Illustrations (each showing a top and two side views) of a single layer of molybdenum disulfide (atoms shown as spheres). Top left: In a hypothetical world without motions, the “ideal” monolayer would be flat. Top right: In reality, the monolayer is wrinkled as shown in this room-temperature simulation. Bottom: If a laser pulse heats the monolayer up, it sends ripples through the layer. These wrinkles, which researchers have now observed for the first time, have large amplitudes and develop on ultrafast timescales. (SLAC National Accelerator Laboratory)

    SLAC Electron Camera UED
    SLAC’s electron Camera

    SLAC electron camera schematic
    SLAC’s electron Camera schematic

    New research led by scientists from the Department of Energy’s SLAC National Accelerator Laboratory and Stanford University shows how individual atoms move in trillionths of a second to form wrinkles on a three-atom-thick material. Revealed by a brand new “electron camera,” one of the world’s speediest, this unprecedented level of detail could guide researchers in the development of efficient solar cells, fast and flexible electronics and high-performance chemical catalysts.

    The breakthrough, accepted for publication Aug. 31 in Nano Letters, could take materials science to a whole new level. It was made possible with SLAC’s instrument for ultrafast electron diffraction (UED), which uses energetic electrons to take snapshots of atoms and molecules on timescales as fast as 100 quadrillionths of a second.

    “This is the first published scientific result with our new instrument,” said scientist Xijie Wang, SLAC’s UED team lead. “It showcases the method’s outstanding combination of atomic resolution, speed and sensitivity.”

    SLAC Director Chi-Chang Kao said, “Together with complementary data from SLAC’s X-ray laser Linac Coherent Light Source, UED creates unprecedented opportunities for ultrafast science in a broad range of disciplines, from materials science to chemistry to the biosciences.” LCLS is a DOE Office of Science User Facility.

    SLAC LCLS Inside

    download mp4 here.

    Extraordinary Material Properties in Two Dimensions

    Monolayers, or 2-D materials, contain just a single layer of molecules. In this form they can take on new and exciting properties such as superior mechanical strength and an extraordinary ability to conduct electricity and heat. But how do these monolayers acquire their unique characteristics? Until now, researchers only had a limited view of the underlying mechanisms.

    “The functionality of 2-D materials critically depends on how their atoms move,” said SLAC and Stanford researcher Aaron Lindenberg, who led the research team. “However, no one has ever been able to study these motions on the atomic level and in real time before. Our results are an important step toward engineering next-generation devices from single-layer materials.” The research team looked at molybdenum disulfide, or MoS2, which is widely used as a lubricant but takes on a number of interesting behaviors when in single-layer form – more than 150,000 times thinner than a human hair.

    For example, the monolayer form is normally an insulator, but when stretched, it can become electrically conductive. This switching behavior could be used in thin, flexible electronics and to encode information in data storage devices. Thin films of MoS2 are also under study as possible catalysts that facilitate chemical reactions. In addition, they capture light very efficiently and could be used in future solar cells.

    Because of this strong interaction with light, researchers also think they may be able to manipulate the material’s properties with light pulses.

    “To engineer future devices, control them with light and create new properties through systematic modifications, we first need to understand the structural transformations of monolayers on the atomic level,” said Stanford researcher Ehren Mannebach, the study’s lead author.

    Visualization of laser-induced motions of atoms (black and yellow spheres) in a molybdenum disulfide monolayer: The laser pulse creates wrinkles with large amplitudes – more than 15 percent of the layer’s thickness – that develop in a trillionth of a second. (K.-A. Duerloo/Stanford)

    Electron Camera Reveals Ultrafast Motions

    Previous analyses showed that single layers of molybdenum disulfide have a wrinkled surface. However, these studies only provided a static picture. The new study reveals for the first time how surface ripples form and evolve in response to laser light.

    Researchers at SLAC placed their monolayer samples, which were prepared by Linyou Cao’s group at North Carolina State University, into a beam of very energetic electrons. The electrons, which come bundled in ultrashort pulses, scatter off the sample’s atoms and produce a signal on a detector that scientists use to determine where atoms are located in the monolayer. This technique is called ultrafast electron diffraction.

    The team then used ultrashort laser pulses to excite motions in the material, which cause the scattering pattern to change over time.

    “Combined with theoretical calculations, these data show how the light pulses generate wrinkles that have large amplitudes – more than 15 percent of the layer’s thickness – and develop extremely quickly, in about a trillionth of a second. This is the first time someone has visualized these ultrafast atomic motions,” Lindenberg said.

    Once scientists better understand monolayers of different materials, they could begin putting them together and engineer mixed materials with completely new optical, mechanical, electronic and chemical properties.

    The research was supported by DOE’s Office of Science, the SLAC UED/UEM program development fund, the German National Academy of Sciences, and the U.S. National Science Foundation.


    To study ultrafast atomic motions in a single layer of molybdenum disulfide, researchers followed a pump-probe approach: They excited motions with a laser pulse (pump pulse, red) and probed the laser-induced structural changes with a subsequent electron pulse (probe pulse, blue). The electrons of the probe pulse scatter off the monolayer’s atoms (blue and yellow spheres) and form a scattering pattern on the detector – a signal the team used to determine the monolayer structure. By recording patterns at different time delays between the pump and probe pulses, the scientists were able to determine how the atomic structure of the molybdenum disulfide film changed over time. (SLAC National Accelerator Laboratory)

    Citation: E. M. Mannebach et al., Nano Letters, 31 August 2015 (10.1021/acs.nanolett.5b02805)

    Press Office Contact: Andrew Gordon, agordon@slac.stanford.edu, (650) 926-2282

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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.

  • richardmitnick 2:30 pm on August 26, 2015 Permalink | Reply
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    From PNNL: “Scientists Discover Precise Location of Active Sites on Popular Catalyst” 

    PNNL Lab

    August 2015
    No Writer Credit

    Experimental work with vanadium oxide catalysts relied on sophisticated spectroscopy and chemical structure calculations to establish a relationship between specific sites on the catalysts and the degree of activity they bring out in a reaction. The work was published in the July 2, 2015, issue of ACS Catalysis and featured on the cover. Posted with permission from ACS Catalysis, July 2, 2015, 5(7). Copyright 2015 American Chemical Society.

    Results: If you want to change a situation, it’s often best to get to the heart of the matter. For chemists, this often means delving into the active sites of catalysts, which speed the reactions behind billions of dollars worth of chemicals and other products. Active sites are where the reaction actually happens. If active sites work slowly or fail quickly, the result is higher costs and lower production rates. To make better active sites, scientists need to see the sites. For the first time, a team led by researchers at Pacific Northwest National Laboratory saw the active sites on a well-known vanadium-based catalyst.

    In addition to the PNNL staff, the team included experts from Washington State University, the University of Alabama, and the Dalian Institute of Chemical Physics, Chinese Academy of Sciences.

    Why It Matters: Fast. Stable. Efficient. These are the hallmarks of a good catalyst, one that can produce needed products without excessive costs or wastes. The results from this study could help researchers design such catalysts. How? By finding ways to create more active sites or protect existing sites from degrading during such reactions — or both.

    Methods: In the experiments, the researchers dispersed or spread the vanadium oxide catalyst on a support of titanium dioxide to create a relatively large surface area with more reactive sites. They used a magic angle spinning (MAS) nuclear magnetic resonance (NMR) spectroscopy technology at EMSL, the Department of Energy’s Environmental Molecular Sciences Laboratory, to obtain detailed information about the structures of active species as they exist on the titanium dioxide support.

    “Using an ultra-high magnetic field with fast spinning enabled the team to observe five types of surface vanadium oxide structures that exist when supported on the surfaces of titanium dioxide,” said Dr. Jian Zhi Hu, a PNNL scientist and the team’s lead.

    The scientists correlated the various peaks observed in the NMR spectra with the catalysts’ reactivity for an oxidation reaction that removes a hydrogen atom from methanol. Next, using computational methods, they predicted which peaks in the NMR spectra corresponded with the specific vanadium oxide geometries. In this way, the scientists determined which structures on the vanadium oxide surface do the best job of initiating and sustaining reactions.

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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.


  • richardmitnick 10:40 am on July 30, 2015 Permalink | Reply
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    From MIT: “How to look for a few good catalysts” 

    MIT News

    July 30, 2015
    David L. Chandler

    New research shows non-wetting surfaces promote chemical reaction rates.

    Materials that have good wetting properties, as illustrated on the left, where droplets spread out flat, tend to have hydroxyl groups attached to the surface, which inhibits catalytic activity. Materials that repel water, as shown at right, where droplets form sharp, steep boundaries, are more conducive to catalytic activity, as shown by the reactions among small orange molecules. Illustration: Xiao Renshaw Wang

    Two key physical phenomena take place at the surfaces of materials: catalysis and wetting. A catalyst enhances the rate of chemical reactions; wetting refers to how liquids spread across a surface.

    Now researchers at MIT and other institutions have found that these two processes, which had been considered unrelated, are in fact closely linked. The discovery could make it easier to find new catalysts for particular applications, among other potential benefits.

    “What’s really exciting is that we’ve been able to connect atomic-level interactions of water and oxides on the surface to macroscopic measurements of wetting, whether a surface is hydrophobic or hydrophilic, and connect that directly with catalytic properties,” says Yang Shao-Horn, the W.M. Keck Professor of Energy at MIT and a senior author of a paper describing the findings in the Journal of Physical Chemistry C. The research focused on a class of oxides called perovskites that are of interest for applications such as gas sensing, water purification, batteries, and fuel cells.

    Since determining a surface’s wettability is “trivially easy,” says senior author Kripa Varanasi, an associate professor of mechanical engineering, that determination can now be used to predict a material’s suitability as a catalyst. Since researchers tend to specialize in either wettability or catalysis, this produces a framework for researchers in both fields to work together to advance understanding, says Varanasi, whose research focuses primarily on wettability; Shao-Horn is an expert on catalytic reactions.

    “We show how wetting and catalysis, which are both surface phenomena, are related,” Varanasi says, “and how electronic structure forms a link between both.”

    While both effects are important in a variety of industrial processes and have been the subject of much empirical research, “at the molecular level, we understand very little about what’s happening at the interface,” Shao-Horn says. “This is a step forward, providing a molecular-level understanding.”

    “It’s primarily an experimental technique” that made the new understanding possible, explains Kelsey Stoerzinger, an MIT graduate student and the paper’s lead author. While most attempts to study such surface science use instruments requiring a vacuum, this team used a device that could study the reactions in humid air, at room temperature, and with varying degrees of water vapor present. Experiments using this system, called ambient pressure X-ray photoelectron spectroscopy, revealed that the reactivity with water is key to the whole process, she says.

    The water molecules break apart to form hydroxyl groups — an atom of oxygen bound to an atom of hydrogen — bonded to the material’s surface. These reactive compounds, in turn, are responsible for increasing the wetting properties of the surface, while simultaneously inhibiting its ability to catalyze chemical reactions. Therefore, for applications requiring high catalytic activity, the team found, a key requirement is that the surface be hydrophobic, or non-wetting.

    “Ideally, this understanding helps us design new catalysts,” Stoerzinger says. If a given material “has a lower affinity for water, it has a higher affinity for catalytic activity.”

    Shao-Horn notes that this is an initial finding, and that “extension of these trends to broader classes of materials and ranges of hydroxyl affinity requires further investigation.” The team has already begun further exploration of these areas. This research, she says, “opens up the space of materials and surfaces we might think about” for both catalysis and wetting.

    The research team also included graduate student Wesley Hong, visiting scientist Livia Giordano, and postdocs Yueh-Lin Lee and Gisele Azimi at MIT; Ethan Crumlin and Hendrik Bluhm at Lawrence Berkeley National Laboratory; and Michael Biegalski at Oak Ridge National Laboratory. The work was supported by the National Science Foundation and the U.S. Department of Energy.

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  • richardmitnick 8:49 am on April 2, 2015 Permalink | Reply
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    From SLAC: “Scientists Track Ultrafast Creation of a Catalyst with X-ray Laser” 

    SLAC Lab

    April 1, 2015

    Chemical Transformations Driven by Light Provide Key Insight to Steps in Solar-energy Conversion

    This artistic rendering shows an iron-centered molecule that is severed by laser light (upper left). Within hundreds of femtoseconds, or quadrillionths of a second, a molecule of ethanol from a solvent rushes in (bottom right) to bond with the iron-centered molecule. (SLAC National Accelerator Laboratory)

    An international team has for the first time precisely tracked the surprisingly rapid process by which light rearranges the outermost electrons of a metal compound and turns it into an active catalyst – a substance that promotes chemical reactions.

    The results, published April 1 in Nature, could help in the effort to develop novel catalysts to efficiently produce fuel using sunlight. The research was performed with an X-ray laser at the Department of Energy’s SLAC National Accelerator Laboratory.

    “We were able to determine how light rearranges the outermost electrons of the compound on timescales down to a few hundred femtoseconds, or quadrillionths of a second,” said Philippe Wernet, a scientist at Helmholtz-Zentrum Berlin for Materials and Energy who led the experiment.

    Researchers hope that learning these details will allow them to develop rules for predicting and controlling the short-lived early steps in important reactions, including the ones plants use to turn sunlight and water into fuel during photosynthesis. Scientists are seeking to replicate these natural processes to produce hydrogen fuel from sunlight and water, for example, and to master the chemistry required to produce other renewable fuels.

    “The eventual goal is to design chemical reactions that behave exactly the way you want them to,” Wernet said.

    In the experiment at SLAC’s Linac Coherent Light Source, a DOE Office of Science User Facility, the scientists studied a yellowish fluid called iron pentacarbonyl, which consists of carbon monoxide “spurs” surrounding a central iron atom. It is a basic building block for more complex compounds and also provides a simple model for studying light-induced chemical reactions.

    SLAC LCLS Inside

    Researchers had known that exposing this iron compound to light can cleave off one of the five carbon monoxide spurs, causing the molecule’s remaining electrons to rearrange. The arrangement of the outermost electrons determines the molecule’s reactivity – including whether it might make a good catalyst – and also informs how reactions unfold.

    What wasn’t well understood was just how quickly this light-triggered transformation occurs and which short-lived intermediate states the molecule goes through on its way to becoming a stable product.

    At LCLS, the scientists struck a thin stream of the iron compound, which was mixed into an ethanol solvent, with pulses of optical laser light to break up the iron-centered molecules. Just hundreds of femtoseconds later, an ultrabright X-ray pulse probed the molecules’ transformation, which was recorded with sensitive detectors.

    By varying the arrival time of the X-ray pulses, they tracked the rearrangements of the outermost electrons during the molecular transformations.

    Roughly half of the severed molecules enter a chemically reactive state in which their outermost electrons are prone to binding other molecules. As a consequence, they either reconnect with the severed part or bond with an ethanol molecule to form a new compound. In other cases the outermost electrons in the molecule stabilize themselves in a configuration that makes the molecule non-reactive. All of these changes were observed within the time it takes light to travel a few thousandths of an inch.

    “To see this happen so quickly was extremely surprising,” Wernet said.

    Several years’ worth of data analysis and theoretical work were integral to the study, he said. The next step is to move on from model compounds to LCLS studies of the actual molecules used to make solar fuels.

    “This was a really exciting experiment, as it was the first time we used the LCLS to study chemistry in a liquid compound,” said Josh Turner, a SLAC staff scientist who participated in the experiment. “The LCLS is unique in the world in its ability to resolve these types of ultrafast processes in the right energy range for this compound.”

    SLAC’s Kelly Gaffney, a chemist who contributed expertise in how the changing arrangement of electrons steered the chemical reactions, said, “This work helps set the stage for future studies at LCLS and shows how cooperation across different research areas at SLAC enables broader and better science.”

    In addition to researchers from Helmholtz-Zentrum Berlin for Materials and Energy and LCLS, other scientists who assisted in the study were from: SLAC’s Stanford Synchrotron Radiation Lightsource; the SLAC and Stanford PULSE Institute; University of Potsdam, Max Planck Institute for Biophysical Chemistry, Goettingen University and DESY lab in Germany; Stockholm University and MAX-lab in in Sweden; Utrecht University in the Netherlands; Paul Scherrer Institute in Switzerland; and the University of Pennsylvania.

    This work was supported by the Volkswagen Foundation, the Swedish Research Council, the Carl Tryggers Foundation, the Magnus Bergvall Foundation, Collaborative Research Centers of the German Science Foundation and the Helmholtz Virtual Institute “Dynamic Pathways in Multidimensional Landscapes,” and the U.S. Department of Energy Office of Science.

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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.

  • richardmitnick 6:53 am on January 20, 2015 Permalink | Reply
    Tags: , Catalyst technology,   

    From Stanford: “Stanford engineers use brilliant X-rays to illuminate catalysis, revise theories” 

    Stanford University Name
    Stanford University

    January 19, 2015
    Andrew Myers

    Many of today’s most promising renewable energy technologies – fuel cells, water splitters and artificial photosynthesis – rely upon catalysts to expedite the chemical reactions at the heart of their potential. Catalysts are materials that enhance chemical reactions without being consumed in the process. For over a century, engineers across the world have engaged in a near-continual search for ways to improve catalysts for their devices and processes.

    Against this backdrop, a team of researchers at Stanford has used high-brilliance X-rays in a new way to peer into active reactions using metal oxides as the catalyst. Ceramic-like metal oxides, such as iron oxide, a material similar to rust, are desirable as catalysts because they are more abundant and more stable than typical catalysts made of rare metals like platinum, ruthenium and rhodium.

    Lead author Dr. David Mueller using brilliant X-rays to characterize working fuel cells at the Advanced Light Source at the Lawrence Berkeley National Laboratory. He is a staff scientist at the Juelich, Germany, research center.

    Although they may be more abundant, metal oxides are also less scientifically understood than their metallic counterparts.

    The Stanford engineers were able to use enhanced X-ray technology in a novel way to observe the behavior of individual electrons during these important chemical processes. What they learned has upended long-held scientific understanding of how metal oxide catalysts work.

    “A freshman chemistry student would tell you, by intuition, that in a material made up of iron and oxygen – as iron oxide is – it is the iron, the metal ion, that is the catalytically active component. We discovered exactly the opposite. Oxygen ions are the ones gaining and losing electrons most actively. Iron is almost completely inactive,” explained William Chueh, an assistant professor of materials science and engineering and senior author of the study published in the journal Nature Communications.

    The results are a 180-degree shift from what went before, assert Chueh and colleagues – postdoctoral scholar David N. Mueller and graduate student Michael L. Machala, both of whom work in Chueh’s lab, and Hendrik Bluhm, a staff scientist at Lawrence Berkeley National Laboratory. The findings could reshape the search for new and better catalysts.

    “We’ve been looking in the wrong place. We thought oxygen was the spectator, but it’s the protagonist, and we can now look to develop new catalysts by modifying the oxygen ions in these systems,” Chueh said.

    Redox redux

    In reality, the catalyst is consumed and then recreated during the reaction, but the net result is the same: zero effect on the catalyst, but profound implications for humanity.

    Catalysts play a fundamental role in our lives, though few outside the community of researchers and engineers who study them know much about how they work. Metal oxides, in particular, are leading candidates for use as catalysts at the heart of a basic chemical reaction known as reduction-oxidation, or “redox” for short. Redox reactions are key to renewable energy uses.

    One of the best examples is water splitting. Electricity generated from the sun via solar panels is passed through water. The electric current separates (“splits”) the water into its two constituent elements: environmentally beneficial oxygen and clean-burning hydrogen. The hydrogen can then be stored and later burned as fuel to generate electricity when the sun is not shining.
    A fundamental search

    One of the major hurdles on the path to these renewable energy applications has been the catalyst. The Chueh team’s research represents one of the first times science has used high-brilliance X-rays to look so closely at these reactions. The experiments were performed at the Advanced Light Source at the Lawrence Berkeley National Laboratory. Until recently the reactions under such surveillance had to be done in a vacuum, but no longer.

    “It simply wasn’t possible to study how gas molecules, particularly oxygen, interacted with the catalyst because we couldn’t include them in the experiments. Thanks to these new techniques, we can study oxygen in the reactions,” Chueh said.

    The advance allowed the researchers to observe and follow the electrons as they do their work and to better understand how they behave during the reactions. What they have learned is “extremely critical” to fundamental-level understanding of catalysts and could lead in exciting new directions in catalyst design, Chueh added. Research like this provides a glimpse of a future in which metal oxides will become more competitive with traditional catalysts.

    “We’re working at the most basic levels of science to understand what makes a material tick, and what limits its performance and why. This is fundamental work, but it is inspiring, as well,” Chueh said, adding: “It will help us design better technologies from the atomic level up, to someday have great commercial impact.”

    Media Contact

    Tom Abate, Stanford Engineering: tabate@stanford.edu, (650) 735-2245
    Dan Stober, Stanford News Service: (650) 721-6965, dstober@stanford.edu

    See the full article here.

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  • richardmitnick 6:11 pm on August 8, 2014 Permalink | Reply
    Tags: , Catalyst technology,   

    From EMSL: “Improving catalysts” 

    Environmental Molecular Sciences Laboratory (EMSL)

    No Date
    No Writer Credit

    Better bimetallic catalysts for fuel and chemical industries

    The Science

    Nanocatalysts consisting of two metals can offer superior performance compared with those made up of only one metal, so they are widely used for industrial processes that generate fuels and chemicals from natural gas, coal or plant biomass. However, complex interactions between the two metals during catalytic reactions can lower catalytic efficiency. This study addresses this issue by directly observing the changes of platinum-cobalt nanoparticles in operating conditions. Such particles are used as catalysts to convert carbon dioxide and hydrogen into long-chain carbon fuels and are important to the operation of low-temperature fuel cells.

    No image credit

    The Impact

    The new insights on the transformations of multiple component catalysts will allow researchers to optimally design similar catalysts to improve their performance, extend their lifetime, and reduce their environmental impact. Moreover, this research could guide efforts to minimize the use of precious metal components such as platinum and therefore reduce the cost of catalysts and lead to a more economical product for consumers.


    In a multi-national lab effort led by Haimei Zheng from Lawrence Berkeley National Laboratory, researchers from DOE’s Pacific Northwest National Laboratory and collaborators examined real-time changes in the atomic structure of nanoparticles consisting of platinum and cobalt during reactions with oxygen and hydrogen using environmental transmission electron microscopy (ETEM), a specialized instrument housed in the Quiet Wing at the Environmental Molecular Sciences Laboratory (EMSL), a DOE national scientific user facility. The work was supported by the Chemical Imaging Initiative at PNNL.

    During oxidation in an oxygen gas environment, cobalt migrated to the nanoparticle surface, where it formed a cobalt oxide film that covered the platinum. Within ten seconds, this oxide film broke apart to form distinct islands and created voids in the interior of the particle, which can impair catalyst performance. This process was reversed during reduction in a hydrogen gas environment, which caused the cobalt oxide patches to decrease and the cobalt to migrate back to the bulk of the particle. Reduction with hydrogen also caused a layer of platinum to form on the particle surface, which is expected to improve catalyst performance.

    These new insights into the atomic scale behavior of nanoparticles consisting of multiple metals in reactive environments pave the way for a deeper understanding of the properties of multi-component catalysts and will guide efforts to improve their performance. In particular, the findings can be used to design multi-component catalysts that do not form oxide islands on the nanoparticle surface, but rather retain the material with higher catalytic performance on the nanoparticle surface during catalytic reactions.


    This research was supported by DOE’s Office of Science and the Office of Basic Energy Sciences’ Chemical Science Division, as well as the Chemical Imaging Initiative at PNNL through the

    Laboratory Directed Research and Development Programs at PNNL and LBNL.

    See the full article here.

    EMSL is a national scientific user facility that is funded and sponsored by DOE’s Office of Biological & Environmental Research. As a user facility, our scientific capabilities – people, instruments and facilities – are available for use by the global research community. We support BER’s mission to provide innovative solutions to the nation’s environmental and energy production challenges in areas such as atmospheric aerosols, feedstocks, global carbon cycling, biogeochemistry, subsurface science and energy materials.

    A deep understanding of molecular-level processes is critical to gaining a predictive, systems-level understanding of the impacts of aerosols and terrestrial systems on climate change; making clean, affordable, abundant energy; and cleaning up our legacy wastes. Visit our Science page to learn how EMSL leads in these areas, through our Science Themes.

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  • richardmitnick 9:13 am on August 1, 2014 Permalink | Reply
    Tags: , Catalyst technology,   

    From Brookhaven Lab: “Nanostructured Metal-Oxide Catalyst Efficiently Converts CO2 to Methanol” 

    Brookhaven Lab

    July 31, 2014
    Karen McNulty Walsh, (631) 344-8350 or Peter Genzer, (631) 344-3174printer iconPrint

    Highly reactive sites at interface of two nanoscale components could help overcome hurdle of using CO2 as a starting point in producing useful products

    Dario Stacchiola and Kumudu Mudiyanselage make notes in the data log while Fang Xu (seated) and Jose Rodriguez view microscopic images of the catalyst and Ping Liu and Sanjaya Senanayake adjust the ambient-pressure scanning tunneling microscope. No image credit

    Scientists at the U.S. Department of Energy’s (DOE) Brookhaven National Laboratory have discovered a new catalytic system for converting carbon dioxide (CO2) to methanol—a key commodity used to create a wide range of industrial chemicals and fuels. With significantly higher activity than other catalysts now in use, the new system could make it easier to get normally unreactive CO2 to participate in these reactions.

    “Developing an effective catalyst for synthesizing methanol from CO2 could greatly expand the use of this abundant gas as an economical feedstock,” said Brookhaven chemist Jose Rodriguez, who led the research. It’s even possible to imagine a future in which such catalysts help mitigate the accumulation of this greenhouse gas, by capturing CO2 emitted from methanol-powered combustion engines and fuel cells, and recycling it to synthesize new fuel.

    That future, of course, will be determined by a variety of factors, including economics. “Our basic research studies are focused on the science—the discovery of how such catalysts work, and the use of this knowledge to improve their activity and selectivity,” Rodriguez emphasized.

    The research team, which included scientists from Brookhaven, the University of Seville in Spain, and Central University of Venezuela, describes their results in the August 1, 2014, issue of the journal Science.

    New tools for discovery

    Fang Xu, a Stony Brook University PhD student working with the Brookhaven Lab team on studies to identify more effective catalysts for industrial processes, peers into the ambient-pressure scanning tunneling microscope used in these experiments.

    Because CO2 is normally such a reluctant participant in chemical reactions, interacting weakly with most catalysts, it’s also rather difficult to study. These studies required the use of newly developed in-situ (or on-site, meaning under reaction conditions) imaging and chemical “fingerprinting” techniques. These techniques allowed the scientists to peer into the dynamic evolution of a variety of catalysts as they operated in real time. The scientists also used computational modeling at the University of Seville and the Barcelona Supercomputing Center to provide a molecular description of the methanol synthesis mechanism.

    The team was particularly interested in exploring a catalyst composed of copper and ceria (cerium-oxide) nanoparticles, sometimes also mixed with titania. The scientists’ previous studies with such metal-oxide nanoparticle catalysts have demonstrated their exceptional reactivity in a variety of reactions. In those studies, the interfaces of the two types of nanoparticles turned out to be critical to the reactivity of the catalysts, with highly reactive sites forming at regions where the two phases meet.

    To explore the reactivity of such dual particle catalytic systems in converting CO2 to methanol, the scientists used spectroscopic techniques to investigate the interaction of CO2 with plain copper, plain cerium-oxide, and cerium-oxide/copper surfaces at a range of reaction temperatures and pressures. Chemical fingerprinting was combined with computational modeling to reveal the most probable progression of intermediates as the reaction from CO2 to methanol proceeded.

    These studies revealed that the metal component of the catalysts alone could not carry out all the chemical steps necessary for the production of methanol. The most effective binding and activation of CO2 occurred at the interfaces between metal and oxide nanoparticles in the cerium-oxide/copper catalytic system.

    “The key active sites for the chemical transformations involved atoms from the metal [copper] and oxide [ceria or ceria/titania] phases,” said Jesus Graciani, a chemist from the University of Seville and first author on the paper. The resulting catalyst converts CO2 to methanol more than a thousand times faster than plain copper particles, and almost 90 times faster than a common copper/zinc-oxide catalyst currently in industrial use.

    Scanning tunneling microscope image of a cerium-oxide and copper catalyst (CeOx-Cu) used in the transformation of carbon dioxide (CO2) and hydrogen (H2) gases to methanol (CH3OH) and water (H2O). In the presence of hydrogen, the Ce4+ and Cu+1 are reduced to Ce3+ and Cu0 with a change in the structure of the catalyst surface.

    This study illustrates the substantial benefits that can be obtained by properly tuning the properties of a metal-oxide interface in catalysts for methanol synthesis.

    “It is a very interesting step, and appears to create a new strategy for the design of highly active catalysts for the synthesis of alcohols and related molecules,” said Brookhaven Lab Chemistry Department Chair Alex Harris.

    The work at Brookhaven Lab was supported by the DOE Office of Science. The studies performed at the University of Seville were funded by the Ministerio de Economía y Competitividad of Spain and the European Regional Development Fund. The Instituto de Tecnologia Venezolana para el Petroleo supported part of the work carried out at the Central University of Venezuela.

    Brookhaven National Laboratory is supported by the Office of Science of the U.S. Department of Energy. The Office of Science is the single largest supporter of basic research in the physical sciences in the United States, and is working to address some of the most pressing challenges of our time. For more information, please visit science.energy.gov.

    See the full article, with video, here.

    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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