Tagged: Catalyst technology Toggle Comment Threads | Keyboard Shortcuts

  • 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 .

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    NC State campus

    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 .

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition
    BNL Campus

    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.
    i1

     
  • 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 .

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    SLAC Campus
    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.
    i1

     
  • 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 .

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    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 .

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    SLAC Campus
    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.
    i1

     
  • richardmitnick 1:08 pm on November 30, 2015 Permalink | Reply
    Tags: , Catalyst technology,   

    From EMSL: “Scarcity Drives Efficiency” 

    EMSL

    EMSL

    September 28, 2015 [This just became available.]
    Tim Scheibe tim.scheibe@pnnl.gov at EMSL
    Younan Xia younan.xia@bme.gatech.edu

    Platinum can be an efficient fuel cell catalyst

    1
    Researchers developed a new class of catalysts by putting essentially all of the platinum atoms on the surface material and minimized the use of atoms in the core, thereby increasing the utilization efficiency of precious metals for fuel cells.

    The Science

    Platinum is an excellent catalyst for reactions in fuel cells, but its scarcity and cost have driven scientists to look for more efficient ways to use the precious metal. In a recent study, researchers developed a new class of catalysts by putting essentially all of the platinum atoms on the surface and minimizing the use of atoms in the core, thereby increasing efficient utilization of platinum for fuel cells.

    The Impact

    The novel nanocage catalyst will help promote the sustainable use of platinum and other precious metals for energy and other industrial applications. The reduced costs associated with the novel nanostructures will encourage commercialization of this technology for the development of zero-emission energy sources.

    Summary

    Researchers from Georgia Institute of Technology and Emory University, Xiamen University, University of Wisconsin–Madison, Oak Ridge National Laboratory and Arizona State University fabricated cubic and octahedral nanocages by depositing a few atomic layers of platinum on palladium nanocrystals, and then completely etching away the palladium core. Density functional theory (DFT) calculations suggested the etching process was initiated by the formation of vacancies through the removal of palladium atoms incorporated into the outermost layer during the deposition of platinum. Some of the computational work was performed using computer resources at EMSL, the Environmental Molecular Sciences Laboratory, a Department of Energy Office of Biological and Environmental Research user facility. DFT calculations were performed at supercomputing centers at EMSL, Argonne National Laboratory and the National Energy Research Scientific Computing Center.

    Based on the findings, researchers propose that during platinum deposition, some palladium atoms are incorporated into the outermost platinum layers. Upon contact with the etchant—an acid or corrosive chemical—the palladium atoms in the outermost layer of the platinum shell are oxidized to generate vacancies in the surface of the nanostructure. The underlying palladium atoms then diffuse to these vacancies and are continuously etched away, leaving behind atom-wide channels. Over time, the channels grow in size to allow direct corrosion of palladium from the core. This process leads to a nanocage with a few layers of platinum atoms in the shell and a hollow interior.

    Compared to a commercial platinum/carbon catalyst, the nanocages showed enhanced catalytic activity and durability. The findings demonstrate it is possible to design fuel cell catalysts with efficient use of precious metals without sacrificing performance. Moreover, it is possible to tailor the arrangement of atoms or the surface structure of catalytic particles to optimize their catalytic performance for a specific type of chemical reaction. The researchers are testing these catalysts in fuel cell devices to determine how to further improve their design for clean energy applications.

    See the full article here .

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    EMSL campus

    Welcome to EMSL. 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.

    Team’s in Our DNA. We approach science differently than many institutions. We believe in – and have proven – the value of drawing together members of the scientific community and assembling the people, resources and facilities to solve problems. It’s in our DNA, since our founder Dr. Wiley’s initial call to create a user facility that would facilitate “synergism between the physical, mathematical, and life sciences.” We integrate experts across disciplines; experiment with theory; and our user program proposal calls with other user facilities.

    We proudly provide an enriched, customized experience that allows users to connect with our people and capabilities in an environment where we focus on solving problems. We collaborate with researchers from academia, government labs and industry, and from nearly all 50 states and from other countries.

     
  • richardmitnick 1:35 am on November 24, 2015 Permalink | Reply
    Tags: , Catalyst technology, ,   

    From SLAC: “Atom-sized Craters Make a Catalyst Much More Active” 


    SLAC Lab

    November 23, 2015

    SLAC, Stanford Discovery Could Speed Important Chemical Reactions, Such As Making Hydrogen Fuel

    1
    Illustration of a catalyst being bombarded with argon atoms to create holes where chemical reactions can take place. The catalyst is molybdenum disulfide, or MoS2. The bombardment removed about one-tenth of the sulfur atoms (yellow) on its surface. Researchers then draped the holey catalyst over microscopic bumps to change the spacing of the atoms in a way that made the catalyst even more active. (Charlie Tsai/ Stanford University)

    2
    This electron microscope image of a molybdenum sulfide catalyst shows “holes” left by removing sulfur atoms. Creating these holes and stretching the catalyst to change the spacing of its atoms made the catalyst much more active in promoting chemical reactions. The bright dots are molybdenum atoms; the lighter ones are sulfur. The image measures 4 nanometers on a side. (Hong Li/Stanford Nanocharacterizaton Laboratory)

    Bombarding and stretching an important industrial catalyst opens up tiny holes on its surface where atoms can attach and react, greatly increasing its activity as a promoter of chemical reactions, according to a study by scientists at Stanford University and the Department of Energy’s SLAC National Accelerator Laboratory.

    The method could offer a much cheaper way to rev up the production of clean hydrogen fuel from water, the researchers said, and should also apply to other catalysts that promote useful chemical reactions. The study was published Nov. 9 in Nature Materials.

    “This is just the first indication of a new effect, very much in the research stage,” said Xiaolin Zheng, an associate professor of mechanical engineering at Stanford who led the study. “But it opens up totally new possibilities yet to be explored.”

    Finding a Cheap, Abundant Substitute

    Catalysts are substances that promote chemical reactions without being consumed themselves, so they can be used over and over again. Natural catalysts are endlessly at work in plants, animals and our bodies. Industrial catalysts are used to make fuel, fertilizer and consumer products; they’re a multi-billion-dollar industry in their own right.

    The catalyst studied here, molybdenum disulfide or MoS2, helps remove sulfur from petroleum in refineries. But scientists think it might also be a good alternative to platinum as a catalyst for a reaction that joins hydrogen atoms together to make hydrogen gas for fuel.

    “We know platinum is very good at catalyzing this reaction,” said study co-author Jens Nørskov, director of the SUNCAT Center for Interface Science and Catalysis, a joint Stanford/SLAC institute. “But it’s a non-starter because of its rarity. There isn’t enough of it on Earth for large-scale hydrogen fuel production.”

    MoS2 is much cheaper and made of abundant ingredients, and it comes in flexible sheets just one molecule thick, which are stacked together to make catalyst particles, Zheng said. All the catalytic action takes place on the edges of those sheets, where dangling chemical bonds can grab passing atoms and hold them together until they react.

    Researchers have tried all sorts of schemes to increase the active area where this atomic matchmaking goes on. Most of them involve engineering the catalyst sheets to expose more edges, or adding chemicals to make the edges more active.

    A Holey, Stretchy Solution

    In the new approach, Stanford postdoctoral researcher Hong Li used an instrument in the Stanford Nanocharacterization Laboratory to bombard a sheet of MoS2 with argon atoms. This knocked about 1 out of 10 sulfur atoms out of the surface of the sheet, leaving holes surrounded by dangling bonds.

    Then he stretched the holey sheet over microscopic bumps made of silicon dioxide coated with gold. He wet the sheet with a solvent, and when it dried the sheet was permanently deformed: The spacing of the atoms had changed in a way that made the holes much more chemically reactive.

    “Before, the top surface of the sheet was not reactive. It was inert – zero, almost,” Zheng said. “Now the surface is more catalytically active than the edges. And we can tune this activity so the bonds that form on the catalyst are just right – strong enough to hold the reacting atoms in place, but weak enough so they’ll let go of the finished product once the atoms have joined together.”

    SUNCAT theorists, including graduate student Charlie Tsai, played an important role in predicting which combinations of bombarding and stretching would produce the best results, using calculations made with SLAC supercomputers. The researchers said a combination of computation and experiment will be important in finding completely new kinds of active catalytic sites in the future.

    Going forward, Zheng said, “We need to figure out how to do this in the layered catalytic particles that are used in industry, and whether we can apply the same idea to other catalytic materials.”

    They’ll also need to find a better way to make the atom-sized holes, Tsai said. “Bombarding with argon is not practical,” he said. “The procedure is expensive, and it can’t really be scaled up for things like fuel production. So we’ve been working on a follow-up study where we try to replicate the results using a simpler process.”

    Scientists from the Stanford Institute for Materials and Energy Research (SIMES) also played a key role in these experiments. The research was supported by the Samsung Advanced Institute of Technology (SAIT) and Samsung R&D Center America, Silicon Valley, and by SUNCAT and the Center on Nanostructuring for Efficient Energy Conversion at Stanford, both funded by the DOE Office of Science.

    Citation: H. Li et al., Nature Materials, 9 November 2015 (10.1038/nmat4465)

    See the full article here .

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    SLAC Campus
    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.
    i1

     
  • 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

    08.10.2015
    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
    bandarenka@ph.tum.de

    New method facilitates research on fuel cell catalysts

    1
    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.”

    Publication

    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

    See the full article here .

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    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

    1
    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.

    2
    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.

    See the full article here .

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    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
    Tags: , Catalyst technology,   

    From ORNL: “New ORNL catalyst addresses engine efficiency, emissions quandary” 

    i1

    Oak Ridge National Laboratory

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

    1
    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.

    See the full article here .

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    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.

    i2

     
c
Compose new post
j
Next post/Next comment
k
Previous post/Previous comment
r
Reply
e
Edit
o
Show/Hide comments
t
Go to top
l
Go to login
h
Show/Hide help
shift + esc
Cancel
%d bloggers like this: