Tagged: Catalysis Toggle Comment Threads | Keyboard Shortcuts

  • richardmitnick 11:38 am on September 29, 2018 Permalink | Reply
    Tags: Actinide chemistry, , , Catalysis, , Computational chemistry, , , Microsoft Quantum Development Kit, NWChem an open source high-performance computational chemistry tool funded by DOE, , Quantum Information Science   

    From Pacific Northwest National Lab: “PNNL’s capabilities in quantum information sciences get boost from DOE grant and new Microsoft partnership” 

    PNNL BLOC
    From Pacific Northwest National Lab

    September 28, 2018
    Susan Bauer, PNNL,
    susan.bauer@pnnl.gov
    (509) 372-6083

    1
    No image caption or credit

    On Monday, September 24, the U.S. Department of Energy announced $218 million in funding for dozens of research awards in the field of Quantum Information Science. Nearly $2 million was awarded to DOE’s Pacific Northwest National Laboratory for a new quantum computing chemistry project.

    “This award will be used to create novel computational chemistry tools to help solve fundamental problems in catalysis, actinide chemistry, and materials science,” said principal investigator Karol Kowalski. “By collaborating with the quantum computing experts at Lawrence Berkeley National Laboratory, Oak Ridge National Laboratory, and the University of Michigan, we believe we can help reshape the landscape of computational chemistry.”

    Kowalski’s proposal was chosen along with 84 others to further the nation’s research in QIS and lay the foundation for the next generation of computing and information processing as well as an array of other innovative technologies.

    While Kowalski’s work will take place over the next three years, computational chemists everywhere will experience a more immediate upgrade to their capabilities in computational chemistry made possible by a new PNNL-Microsoft partnership.

    “We are working with Microsoft to combine their quantum computing software stack with our expertise on high-performance computing approaches to quantum chemistry,” said Sriram Krishnamoorthy who leads PNNL’s side of this collaboration.

    Microsoft will soon release an update to the Microsoft Quantum Development Kit which will include a new chemical simulation library developed in collaboration with PNNL. The library is used in conjunction with NWChem, an open source, high-performance computational chemistry tool funded by DOE. Together, the chemistry library and NWChem will help enable quantum solutions and allow researchers and developers a higher level of study and discovery.

    “Researchers everywhere will be able to tackle chemistry challenges with an accuracy and at a scale we haven’t experienced before,” said Nathan Baker, director of PNNL’s Advanced Computing, Mathematics, and Data Division. Wendy Shaw, the lab’s division director for physical sciences, agrees with Baker. “Development and applications of quantum computing to catalysis problems has the ability to revolutionize our ability to predict robust catalysts that mimic features of naturally occurring, high-performing catalysts, like nitrogenase,” said Shaw about the application of QIS to her team’s work.

    PNNL’s aggressive focus on quantum information science is driven by a research interest in the capability and by national priorities. In September, the White House published the National Strategic Overview for Quantum Information Science and hosted a summit on the topic. Through their efforts, researchers hope to unleash quantum’s unprecedented processing power and challenge traditional limits for scaling and performance.

    In addition to the new DOE funding, PNNL is also pushing work in quantum conversion through internal investments. Researchers are determining which software architectures allow for efficient use of QIS platforms, designing QIS systems for specific technologies, imagining what scientific problems can best be solved using QIS systems, and identifying materials and properties to build quantum systems. The effort is cross-disciplinary; PNNL scientists from its computing, chemistry, physics, and applied mathematics domains are all collaborating on quantum research and pushing to apply their discoveries. “The idea for this internal investment is that PNNL scientists will take that knowledge to build capabilities impacting catalysis, computational chemistry, materials science, and many other areas,” said Krishnamoorthy.

    Krishnamoorthy wants QIS to be among the priorities that researchers think about applying to all of PNNL’s mission areas. With continued investment from the DOE and partnerships with industry leaders like Microsoft, that just might happen.

    See the full article here .

    five-ways-keep-your-child-safe-school-shootings

    Please help promote STEM in your local schools.

    Stem Education Coalition

    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.

    i1

    Advertisements
     
  • richardmitnick 8:21 am on September 8, 2018 Permalink | Reply
    Tags: , , , Catalysis, , , , Hydrogenase is an enzyme present in algae that is capable of reducing protons into hydrogen, Natural photosynthesis, Photosystem II, Scientists pioneer a new way to turn sunlight into fuel, Solar energy conversion, St. Johns College at Cambridge,   

    From University of Cambridge: “Scientists pioneer a new way to turn sunlight into fuel” 

    U Cambridge bloc

    From University of Cambridge

    03 Sep 2018
    No writer credit

    The quest to find new ways to harness solar power has taken a step forward after researchers successfully split water into hydrogen and oxygen by altering the photosynthetic machinery in plants.

    1
    Experimental two-electrode setup showing the photoelectrochemical cell illuminated with simulated solar light. Credit: Katarzyna Sokół

    Photosynthesis is the process plants use to convert sunlight into energy. Oxygen is produced as a by-product of photosynthesis when the water absorbed by plants is ‘split’. It is one of the most important reactions on the planet because it is the source of nearly all of the world’s oxygen. Hydrogen which is produced when the water is split could potentially be a green and unlimited source of renewable energy.

    A new study led by academics at the University of Cambridge, used semi-artificial photosynthesis to explore new ways to produce and store solar energy. They used natural sunlight to convert water into hydrogen and oxygen using a mixture of biological components and manmade technologies.

    The research could now be used to revolutionise the systems used for renewable energy production. A new paper, published in [Nature Energy], outlines how academics at the Reisner Laboratory in Cambridge’s Department of Chemistry developed their platform to achieve unassisted solar-driven water-splitting.

    Their method also managed to absorb more solar light than natural photosynthesis.

    Katarzyna Sokół, first author and PhD student at St John’s College, said: “Natural photosynthesis is not efficient because it has evolved merely to survive so it makes the bare minimum amount of energy needed – around 1-2 per cent of what it could potentially convert and store.”

    Artificial photosynthesis has been around for decades but it has not yet been successfully used to create renewable energy because it relies on the use of catalysts, which are often expensive and toxic. This means it can’t yet be used to scale up findings to an industrial level.

    The Cambridge research is part of the emerging field of semi-artificial photosynthesis which aims to overcome the limitations of fully artificial photosynthesis by using enzymes to create the desired reaction.

    Sokół and the team of researchers not only improved on the amount of energy produced and stored, they managed to reactivate a process in the algae that has been dormant for millennia.

    She explained: “Hydrogenase is an enzyme present in algae that is capable of reducing protons into hydrogen. During evolution, this process has been deactivated because it wasn’t necessary for survival but we successfully managed to bypass the inactivity to achieve the reaction we wanted – splitting water into hydrogen and oxygen.”

    Sokół hopes the findings will enable new innovative model systems for solar energy conversion to be developed.

    She added: “It’s exciting that we can selectively choose the processes we want, and achieve the reaction we want which is inaccessible in nature. This could be a great platform for developing solar technologies. The approach could be used to couple other reactions together to see what can be done, learn from these reactions and then build synthetic, more robust pieces of solar energy technology.”

    This model is the first to successfully use hydrogenase and photosystem II to create semi-artificial photosynthesis driven purely by solar power.

    Dr Erwin Reisner, Head of the Reisner Laboratory, a Fellow of St John’s College, University of Cambridge, and one of the paper’s authors described the research as a ‘milestone’.

    He explained: “This work overcomes many difficult challenges associated with the integration of biological and organic components into inorganic materials for the assembly of semi-artificial devices and opens up a toolbox for developing future systems for solar energy conversion.”

    See the full article here .

    five-ways-keep-your-child-safe-school-shootings

    Please help promote STEM in your local schools.

    Stem Education Coalition

    U Cambridge Campus

    The University of Cambridge (abbreviated as Cantab in post-nominal letters) is a collegiate public research university in Cambridge, England. Founded in 1209, Cambridge is the second-oldest university in the English-speaking world and the world’s fourth-oldest surviving university. It grew out of an association of scholars who left the University of Oxford after a dispute with townsfolk. The two ancient universities share many common features and are often jointly referred to as “Oxbridge”.

    Cambridge is formed from a variety of institutions which include 31 constituent colleges and over 100 academic departments organised into six schools. The university occupies buildings throughout the town, many of which are of historical importance. The colleges are self-governing institutions founded as integral parts of the university. In the year ended 31 July 2014, the university had a total income of £1.51 billion, of which £371 million was from research grants and contracts. The central university and colleges have a combined endowment of around £4.9 billion, the largest of any university outside the United States. Cambridge is a member of many associations and forms part of the “golden triangle” of leading English universities and Cambridge University Health Partners, an academic health science centre. The university is closely linked with the development of the high-tech business cluster known as “Silicon Fen”.

     
  • richardmitnick 2:47 pm on August 31, 2018 Permalink | Reply
    Tags: A Tiny Protein Like This May Have Kick-Started Life On Earth, Ambidoxin, , , , Catalysis, , Computer modeling, Ferredoxins, , Peptides, , Redox catalysis, , Rutgers' Environmental Biophysics and Molecular Ecology Laboratory   

    From Rutgers University via Forbes: “A Tiny Protein Like This May Have Kick-Started Life On Earth” 

    Rutgers smaller
    Our Great Seal.

    From Rutgers University

    via

    Forbes

    Aug 31, 2018
    Fiona McMillan

    1
    Ambidoxin is a synthetic small protein that wraps around a metal core composed of iron and sulfur. Vikas Nanda/Rutgers University-New Brunswick

    Researchers have reverse engineered a simple protein that may have helped kick start life on Earth.

    Their findings, published in the Journal of the American Chemical Society, provide strong new evidence that simple protein catalysts could have contributed to the development of life.

    A few decades ago, a chemist named Günter Wächtershäuser put forward a theory that life most likely began on volcanic rocks in the ocean that were rich in iron, sulfur and a variety of other minerals and elements useful for the kind of chemistry needed for simple life forms to emerge. He and others went on to surmise that this process would have been helped along by peptides — which are short proteins — that would have been capable of functioning as catalysts.

    A catalyst is anything that can speed up or increase the likelihood of a chemical reaction. Protein catalysts, or enzymes, are able to achieve this by bringing the reactants together in close proximity, and sometimes by also bringing other factors into the mix that help the reaction along, such as a metal ion, a water molecule, or some other type of molecule that gets things moving. In this way, enzymes are like really good party hosts.

    Of course, modern enzymes are often big bulky things comprising hundreds of amino acids. There are 20 amino acids to choose from, so countless combinations are possible. These big, complex enzymes are able fold into a stunning variety of elaborate shapes, enabling them to capture and hold reactants, and carry out reactions. They’re absolutely critical to the function of both simple and complex cellular life; we literally couldn’t live without them.

    However, such complex molecules took billions of years to evolve. Wächtershäuser and others have proposed that the earliest peptides would have had much simpler structures — perhaps just 10 or 20 amino acids — with just enough chemical complexity to enable them to carry out basic primordial chemistry.

    Yet exactly what such peptides may have looked like has been a mystery.

    3
    Underwater sulfur chimneys at Northwest Eifuku volcano. Life may have begun on volcanic underwater rocks like these.Credit: Pacific Ring of Fire 2004 Expedition. NOAA Office of Ocean Exploration; Dr. Bob Embley, NOAA PMEL, Chief Scientist; Public domain image

    Now Vikas Nanda and his colleagues at Rutgers University have used computer modeling to find out just how simple a peptide can get while still retaining the ability to function as a catalyst.

    In so doing, they have designed a peptide only 12 amino acids long that is able to wrap around a cluster of iron and sulfur atoms, which closely resemble iron-sulfur clusters that would have been found in ancient oceans.

    Interestingly, the peptide, which they named ambidoxin, doesn’t need the full variety of 20 amino acids available to modern proteins — it only requires two types of amino acid. Given its simplicity, the researchers suggest such a structure could have evolved spontaneously under the right conditions.

    Importantly, ambidoxin is able to carry out simple oxidation-reduction chemistry, also known as redox catalysis. Essentially it is able to be charged and discharged without falling apart, effectively enabling it to shuttle electrons from one place to another.

    “Modern proteins called ferredoxins do this, shuttling electrons around the cell to promote metabolism,” says senior author Paul G. Falkowski, who leads Rutgers’ Environmental Biophysics and Molecular Ecology Laboratory.

    “A primordial peptide like the one we studied may have served a similar function in the origins of life,” he says.

    By shuttling electrons around, ambidoxin (or something like it) may have contributed to early metabolic cycles, and could have served as a precursor to longer, more complex enzymes.

    See the full article here .


    five-ways-keep-your-child-safe-school-shootings

    Please help promote STEM in your local schools.

    Stem Education Coalition

    rutgers-campus

    Rutgers, The State University of New Jersey, is a leading national research university and the state’s preeminent, comprehensive public institution of higher education. Rutgers is dedicated to teaching that meets the highest standards of excellence; to conducting research that breaks new ground; and to providing services, solutions, and clinical care that help individuals and the local, national, and global communities where they live.

    Founded in 1766, Rutgers teaches across the full educational spectrum: preschool to precollege; undergraduate to graduate; postdoctoral fellowships to residencies; and continuing education for professional and personal advancement.

    As a ’67 graduate of University college, second in my class, I am proud to be a member of

    Alpha Sigma Lamda, National Honor Society of non-tradional students.

     
    • stewarthoughblog 6:08 pm on August 31, 2018 Permalink | Reply

      How to get this straight? Ambidoxin is a synthetic molecule? It took intelligent designers to reverse engineer a simple protein? A totally open system of underwater volcanic rocks supposed was the source for this molecular development? Protein enzymes also had to form to “capture, hold and carry out reactions? the complex molecular enzymes took billions of years to “evolve, when evolution only occurs to living reproductive organisms that did not exist yet? Regardless of this obstacle, the 10-20 amino acids proposed to make its simpler for the formation of the molecule must be homochiral, a condition that no naturalistic process can accomplish. Which “2 amino acids?” Only the simplest can form naturalistically.

      There is no way the full article can rectify the absurd propositions in this article. This is intellectually insulting in its preposterous and nonscientific speculation.

      Like

    • richardmitnick 1:12 pm on September 1, 2018 Permalink | Reply

      • stewarthoughblog 6:42 pm on September 1, 2018 Permalink | Reply

        Thank you for the reply and illumination of astrobiology.net’s beliefs. Nothing in their article answers the questions I posed.

        I can only offer my questions to them for serious response, as the astrobiology profession is motivated to pursue any and all aspects of potential life generation from a naturalistic worldview that is motivated to posit any and all mechanisms for the potential creation, development and sustaining of life. More cynically, their paycheck and funding depends on serious investigation and support of naturalistic processes, regardless of their viability.

        The second to last para of the article reveals an ostensible reliance on “evolution” for the formation of abiotic pre-assemblages of molecules that logically advocate abiogenetic assembly results. This, despite the well established disavowal by evolutionists of any evolution within abiogenesis. The astrobiologists are not so ideologically dogmatic if some origin of life milestone can be attained through evolutionary processes.

        Thank you. Regards.

        Like

  • richardmitnick 6:54 am on August 3, 2018 Permalink | Reply
    Tags: , Catalysis, , How synthetic diamonds grow, ,   

    From SLAC Lab: “In a first, scientists precisely measure how synthetic diamonds grow” 

    From SLAC Lab

    August 2, 2018
    Glennda Chui

    1
    A SLAC-Stanford study has precisely measured for the first time how synthetic diamonds grow from diamondoid seeds, like the one at left. (Greg Stewart, SLAC National Accelerator Laboratory)

    A SLAC-Stanford study reveals exactly what it takes for diamond to crystallize around a “seed” cluster of atoms. The results apply to industrial processes and to what happens in clouds overhead.

    Natural diamond is forged by tremendous pressures and temperatures deep underground. But synthetic diamond can be grown by nucleation, where tiny bits of diamond “seed” the growth of bigger diamond crystals. The same thing happens in clouds, where particles seed the growth of ice crystals that then melt into raindrops.

    Scientists have now observed for the first time how diamonds grow from seed at an atomic level, and discovered just how big the seeds need to be to kick the crystal growing process into overdrive.

    The results, published this week in Proceedings of the National Academy of Sciences, shed light on how nucleation proceeds not just in diamonds, but in the atmosphere, in silicon crystals used for computer chips and even in proteins that clump together in neurological diseases.

    “Nucleation growth is a core tenet of materials science, and there’s a theory and a formula that describes how this happens in every textbook,” says Nicholas Melosh, a professor at Stanford University and the Department of Energy’s SLAC National Accelerator Laboratory who led the research. “It’s how we describe going from one material phase to another, for example from liquid water to ice.”

    But interestingly, he says, “despite the widespread use of this process everywhere, the theory behind it had never been tested experimentally, because observing how crystal growth starts from atomic-scale seeds is extremely difficult.”

    2
    An illustration shows how diamondoids (left), the tiniest possible specks of diamond, were used to seed the growth of nanosized diamond crystals (right). Trillions of diamondoids were attached to the surface of a silicon wafer, which was then tipped on end and exposed to a hot plasma (purple) containing carbon and hydrogen, the two elements needed to form diamond. A new study found that diamond growth really took off when seeds contained at least 26 carbon atoms. (Greg Stewart/SLAC National Accelerator Laboratory)

    The smallest possible specks

    In fact, scientists have known for a long time that the current theory often overestimates how much energy it takes to kick off the nucleation process, and by quite a bit. They’ve come up with potential ways to reconcile the theory with reality, but until now those ideas have been tested only at a relatively large scale, for instance with protein molecules, rather than at the atomic scale where nucleation begins.

    To see how it works at the smallest scale, Melosh and his team turned to diamondoids, the tiniest possible bits of diamond. The smallest ones contain just 10 carbon atoms. These specks are the focus of a DOE-funded program at SLAC and Stanford where naturally occurring diamondoids are isolated from petroleum fluids, sorted by size and shape and studied. Recent experiments suggest they could be used as Lego-like blocks for assembling nanowires or “molecular anvils” for triggering chemical reactions, among other things.

    The latest round of experiments was led by Stanford postdoctoral researcher Matthew Gebbie. He’s interested in the chemistry of interfaces – places where one phase of matter encounters another, for instance the boundary between air and water. It turns out that interfaces are incredibly important in growing diamonds with a process called CVD, or chemical vapor deposition, that’s widely used to make synthetic diamond for industry and jewelry.

    “What I’m excited about is understanding how size and shape and molecular structure influence the properties of materials that are important for emerging technologies,” Gebbie says. “That includes nanoscale diamonds for use in sensors and in quantum computing. We need to make them reliably and with consistently high quality.”

    Diamond or pencil lead?

    To grow diamond in the lab with CVD, tiny bits of crushed diamond are seeded onto a surface and exposed to a plasma – a cloud of gas heated to such high temperatures that electrons are stripped away from their atoms. The plasma contains hydrogen and carbon, the two elements needed to form a diamond.

    This plasma can either dissolve the seeds or make them grow, Gebbie says, and the competition between the two determines whether bigger crystals form. Since there are many ways to pack carbon atoms into a solid, it all has to be done under just the right conditions; otherwise you can end up with graphite, commonly known as pencil lead, instead of the sparkly stuff you were after.

    Diamondoid seeds give scientists a much finer level of control over this process. Although they’re too small to see directly, even with the most powerful microscopes, they can be precisely sorted according to the number of carbon atoms they contain and then chemically attached to the surface of a silicon wafer so they’re pinned in place while being exposed to plasma. The crystals that grow around the seeds eventually get big enough to count under a microscope, and that’s what the researchers did.

    The magic number is 26

    Although diamondoids had been used to seed the growth of diamonds before, these were the first experiments to test the effects of using seeds of various sizes. The team discovered that crystal growth really took off with seeds that contain at least 26 carbon atoms.

    Even more important, Gebbie says, they were able to directly measure the energy barrier that diamondoid particles have to overcome in order to grow into crystals.

    “It was thought that this barrier must be like a gigantic mountain that the carbon atoms should not be able to cross – and, in fact, for decades there’s been an open question of why we could even make diamonds in the first place,” he says. “What we found was more like a mild hill.”

    Gebbie adds, “This is really fundamental research, but at the end of the day, what we’re really excited about and driving for is a predictable and reliable way to make diamond nanomaterials. Now that we’ve developed the underlying scientific knowledge needed to do that, we’ll be looking for ways to put these diamond nanomaterials to practical use.”

    This research took place at SIMES, the Stanford Institute for Materials and Energy Sciences, with major funding from the DOE Office of Science. In addition to SLAC and Stanford, researchers contributing to this study came from the Institute of Physics of the Czech Academy of Sciences, University Hasselt in Belgium and the Institute of Organic Chemistry at Justus-Liebig University in Germany.

    See the full article here .


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

    Stem Education Coalition

    SLAC 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.

     
  • richardmitnick 3:36 pm on December 29, 2017 Permalink | Reply
    Tags: -ray photoelectron and infrared reflection absorption spectroscopy, , , , , Catalysis, , , We are the first team to trap a noble gas in a 2D porous structure at room temperature,   

    From BNL: “Studying Argon Gas Trapped in Two-Dimensional Array of Tiny ‘Cages'” 

    Brookhaven Lab

    July 17, 2017
    Ariana Tantillo
    atantillo@bnl.gov
    (631) 344-2347

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

    Understanding how individual atoms enter and exit the nanoporous frameworks could help scientists design new materials for gas separation and nuclear waste remediation.

    1
    (Left to right) Anibal Boscoboinik, Jian-Qiang Zhong, Dario Stacchiola, Nusnin Akter, Taejin Kim, Deyu Lu, and Mengen Wang at Brookhaven Lab’s Center for Functional Nanomaterials (CFN). The team of scientists (including John Kestell and Alejandro Boscoboinik) carried out experiments at CFN, at Brookhaven’s National Synchrotron Light Source I and II, and in the Lab’s Chemistry Division to study the trapping of individual argon gas atoms (blue prop in Stacchiola’s hand) in two-dimensional (2D) nanoporous frameworks like the one Boscoboinik and Zhong are holding. They had been using these 2D frameworks as analogues to study catalysis in 3D porous materials called zeolites (structural model on the table), which speed up many important reactions such as the conversion of nitrogen-oxide emissions into nitrogen.

    Scientists at the U.S. Department of Energy’s (DOE) Brookhaven National Laboratory had just finished an experiment with a two-dimensional (2D) structure they synthesized for catalysis research when, to their surprise, they discovered that atoms of argon gas had gotten trapped inside the structure’s nanosized pores. Argon and other noble gases have previously been trapped in three-dimensional (3D) porous materials, but immobilizing them on surfaces had only been achieved by either cooling the gases to very low temperatures to condense them, or by accelerating gas ions to implant them directly into materials.

    “We are the first team to trap a noble gas in a 2D porous structure at room temperature,” said Anibal Boscoboinik, a materials scientist at Brookhaven Lab’s Center for Functional Nanomaterials (CFN), a DOE Office of Science User Facility where part of the research was conducted.

    This achievement, reported in a paper published today in Nature Communications, will enable scientists to use traditional surface-science tools—such as x-ray photoelectron and infrared reflection absorption spectroscopy—to perform detailed studies of single gas atoms in confinement. The knowledge gained from such research could inform the design, selection, and improvement of adsorbent materials and membranes for capturing gases such as radioactive krypton and xenon generated by nuclear power plants.

    The team of scientists from Brookhaven Lab, Stony Brook University, and the National University of San Luis in Argentina synthesized 2D aluminosilicate (composed of aluminum, silicon, and oxygen) films on top of a ruthenium metal surface. The scientists created this 2D model catalyst material to study the chemical processes happening in the industrially used 3D catalyst (called a zeolite), which has a cage-like structure with open pores and channels the size of small molecules. Because the catalytically active surface is enclosed within these cavities, it is difficult to probe with traditional surface-science tools. The 2D analogue material has the same chemical composition and active site as the 3D porous zeolite but its active site is exposed on a flat surface, which is easier to access with such tools.

    2
    An artistic rendering of an argon (Ar) atom trapped in a nanocage that has a silicon (Si)-oxygen (O) framework.

    To confirm that the argon atoms were trapped in these “nanocages,” the scientists exposed the 2D material to argon gas and measured the kinetic energy and number of electrons ejected from the surface after striking it with an x-ray beam. They performed these studies at the former National Synchrotron Light Source I (NSLS-I) and its successor facility, NSLS-II (both DOE Office of Science User Facilities at Brookhaven), with an instrument developed and operated by the CFN.

    BNL NSLS

    BNL NSLS-II

    BNL NSLS II

    Because the binding energies of core electrons are unique to each chemical element, the resulting spectra reveal the presence and concentration of elements on the surface. In a separate experiment conducted at the CFN, they grazed a beam of infrared light over the surface while introducing argon gas. When atoms absorb light of a specific wavelength, they undergo changes in their vibrational motions that are specific to that element’s molecular structure and chemical bonds.

    To get a better understanding of how the framework itself contributes to caging, the scientists investigated the trapping mechanism with silicate films, which are similar in structure to the aluminosilicates but contain no aluminum. In this case, they discovered that not all of the argon gets trapped in the cages—a small amount goes to the interface between the framework and ruthenium surface. This interface is too compressed in the aluminosilicate films for argon to squeeze in.

    After studying adsorption, the scientists examined the reverse process of desorption by incrementally increasing the temperature until the argon atoms completely released from the surface at 350 degrees Fahrenheit. They corroborated their experimental spectra with theoretical calculations of the amount of energy associated with argon entering and leaving the cages.

    In another infrared spectroscopy experiment conducted in Brookhaven’s Chemistry Division, they explored how the presence of argon in the cages affects the passage of carbon monoxide molecules through the framework. They found that argon restricts the number of molecules that adsorb onto the ruthenium surface.

    “In addition to trapping small atoms, the cages could be used as molecular sieves for filtering carbon monoxide and other small molecules, such as hydrogen and oxygen,” said first author Jian-Qiang Zhong, a CFN research associate.

    While their main goal going forward will be to continue investigating zeolite catalytic processes on the 2D material, the scientists are interested in learning the impact of different pore sizes on the materials’ ability to trap and filter gas molecules.

    “As we seek to better understand the material, interesting and unexpected findings keep coming up,” said Boscoboinik. “The ability to use surface-science methods to understand how a single atom of gas behaves when it is confined in a very small space opens up lots of interesting questions for researchers to answer.”

    This research used resources of the National Energy Research Scientific Computing Center, a DOE Office of Science User Facility at Lawrence Berkeley National Laboratory, and was supported by Brookhaven’s Laboratory Directed Research and Development program and the National Scientific and Technical Research Council (CONICET) of Argentina.

    NERSC Cray XC40 Cori II supercomputer

    LBL NERSC Cray XC30 Edison supercomputer


    The Genepool system is a cluster dedicated to the DOE Joint Genome Institute’s computing needs. Denovo is a smaller test system for Genepool that is primarily used by NERSC staff to test new system configurations and software.

    NERSC PDSF


    PDSF is a networked distributed computing cluster designed primarily to meet the detector simulation and data analysis requirements of physics, astrophysics and nuclear science collaborations.

    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 2:16 pm on December 22, 2017 Permalink | Reply
    Tags: , , , Catalysis,   

    From ANL: “A catalytic balancing act “ 

    Argonne Lab
    News from Argonne National Laboratory

    1
    Argonne scientists and their collaborators have used a new and counterintuitive approach to balance three important factors — activity, stability and conductivity — in a new catalyst designed for splitting water. (Image by Argonne National Laboratory.)

    Balance forms the foundation for a happy life or a healthy diet. For scientists working to design new catalysts to create renewable energy, balancing different materials and their properties is equally important. (Catalysts help accelerate chemical reactions.)

    In a new study Nature Communications, researchers from the U.S. Department of Energy’s (DOE) Argonne National Laboratory, Johns Hopkins University, Drexel University and several universities in South Korea used a new and counterintuitive approach to create a better catalyst that supports one of the reactions involved in splitting water into hydrogen and oxygen. Scientists plan to use the generated hydrogen as a clean fuel.

    ______________________________________________________
    “Finding a material that works well for energy conversion or storage is like creating a happy marriage.” – Nenad Markovic, Argonne materials scientist and study author.
    ______________________________________________________

    By first creating an alloy of two of the densest naturally occurring elements and then removing one, the scientists reshaped the remaining material’s structure so that it better balanced three factors important for chemical reactions: activity, stability and conductivity.

    “Finding a material that works well for energy conversion or storage is like creating a happy marriage,” said Nenad Markovic, an Argonne materials scientist and author of the study. “In our case, we found that a dynamic partnership between two different materials helped us integrate competing concerns.”

    Scientists searching for new catalysts have scoured the periodic table to find the right elements or combinations of elements to maximize a catalyst’s activity in water-splitting reactions, as well as the durability of the active sites on its surface. Finding materials that are both stable and active, however, has been a challenge.

    “More active catalysts tend to be less stable,” Markovic said. “Those that seem to work twice as well usually work only half as long. It is becoming obvious that designing active catalysts is not enough — we need to have not only active, but also stable, materials.”

    For the new catalyst, Markovic and his colleagues turned to iridium, a metal most commonly associated with meteorites. As a thin film, iridium is catalytically active, but as it reacts over time with an electrolyte environment, iridium atoms become oxidized. During this process, some of them leave the catalyst’s surface through corrosion, increasingly impairing its performance.

    The research team worked to prevent the oxidation by reorganizing the iridium’s structure. To help stabilize and activate iridium, they alloyed it with its neighbor on the periodic table, osmium.

    Unlike iridium, osmium is neither catalytically active nor stable, but it did offer a key benefit. After alloying the osmium and iridium together, the researchers then de-alloyed the two metals, leaving behind only a reconfigured structure of three-dimensional iridium nanopores.

    “Without the osmium, the iridium would never achieve this state,” Markovic said. “We needed to introduce and then remove the osmium to get a form of iridium that was both active and stable.”

    Markovic said each nanopore’s enhanced catalytic stability is due to the small volume of electrolyte within a pore becoming quickly saturated with iridium ions so that surface atoms stop dissolving, in much the same way that it is easier to saturate a teacup of water with sugar than a 10-gallon jug.

    While the nanopore’s structure addressed the need for a stable, active catalyst, it was another facet of the iridium’s reconfiguration that helped boost the material’s electron conductivity. Under operational conditions, the porous catalyst actually forms a unique shell of less-conductive iridium oxide around its highly conductive iridium metal interior. This way, electrons can move easily through most of the catalyst to reach the surface, where the water molecule waits on electrons to initiate the water-splitting reaction.

    “Essentially, we’re trying to find a way to send electrons through on the ‘expressway,’ rather than making them take the side roads,” Markovic said. “This core-shell configuration [of the nanoporous material] allows us to do that.”

    See the full article here .

    Please help promote STEM in your local schools.
    STEM Icon
    Stem Education Coalition
    Argonne National Laboratory seeks solutions to pressing national problems in science and technology. The nation’s first national laboratory, Argonne conducts leading-edge basic and applied scientific research in virtually every scientific discipline. Argonne researchers work closely with researchers from hundreds of companies, universities, and federal, state and municipal agencies to help them solve their specific problems, advance America’s scientific leadership and prepare the nation for a better future. With employees from more than 60 nations, Argonne is managed by UChicago Argonne, LLC for the U.S. Department of Energy’s Office of Science. For more visit http://www.anl.gov.

    The Advanced Photon Source at Argonne National Laboratory is one of five national synchrotron radiation light sources supported by the U.S. Department of Energy’s Office of Science to carry out applied and basic research to understand, predict, and ultimately control matter and energy at the electronic, atomic, and molecular levels, provide the foundations for new energy technologies, and support DOE missions in energy, environment, and national security. To learn more about the Office of Science X-ray user facilities, visit http://science.energy.gov/user-facilities/basic-energy-sciences/.

    Argonne is managed by UChicago Argonne, LLC for the U.S. Department of Energy’s Office of Science

    Argonne Lab Campus

     
  • richardmitnick 10:06 am on June 23, 2017 Permalink | Reply
    Tags: , , , Catalysis, , Improve the performance of fuel cells that run on hydrogen fuel but can be poisoned by CO, , Peking University, Taiyuan University of Technology China   

    From BNL: “New Efficient, Low-Temperature Catalyst for Converting Water and CO to Hydrogen Gas and CO2” 

    Brookhaven Lab

    June 22, 2017
    Karen McNulty Walsh
    kmcnulty@bnl.gov
    (631) 344-8350

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

    Low-temperature “water gas shift” reaction produces high levels of pure hydrogen for potential applications, including fuel cells.

    1
    Brookhaven Lab chemists Ping Liu and José Rodriguez helped to characterize structural and mechanistic details of a new low-temperature catalyst for producing high-purity hydrogen gas from water and carbon monoxide. No image credit.

    Scientists have developed a new low-temperature catalyst for producing high-purity hydrogen gas while simultaneously using up carbon monoxide (CO). The discovery—described in a paper set to publish online in the journal Science on Thursday, June 22, 2017—could improve the performance of fuel cells that run on hydrogen fuel but can be poisoned by CO.

    “This catalyst produces a purer form of hydrogen to feed into the fuel cell,” said José Rodriguez, a chemist at the U.S. Department of Energy’s (DOE) Brookhaven National Laboratory. Rodriguez and colleagues in Brookhaven’s Chemistry Division—Ping Liu and Wenqian Xu—were among the team of scientists who helped to characterize the structural and mechanistic details of the catalyst, which was synthesized and tested by collaborators at Peking University in an effort led by Chemistry Professor Ding Ma.

    Because the catalyst operates at low temperature and low pressure to convert water (H2O) and carbon monoxide (CO) to hydrogen gas (H2) and carbon dioxide (CO2), it could also lower the cost of running this so-called “water gas shift” reaction.

    “With low temperature and pressure, the energy consumption will be lower and the experimental setup will be less expensive and easier to use in small settings, like fuel cells for cars,” Rodriguez said.

    The gold-carbide connection

    The catalyst consists of clusters of gold nanoparticles layered on a molybdenum-carbide substrate. This chemical combination is quite different from the oxide-based catalysts used to power the water gas shift reaction in large-scale industrial hydrogen production facilities.

    “Carbides are more chemically reactive than oxides,” said Rodriguez, “and the gold-carbide interface has good properties for the water gas shift reaction; it interacts better with water than pure metals.”

    2
    Wenqian Xu and José Rodriguez of Brookhaven Lab and Siyu Yao, then a student at Peking University but now a postdoctoral research fellow at Brookhaven, conducted operando x-ray diffraction studies of the gold-molybdenum-carbide catalyst over a range of temperatures (423 Kelvin to 623K) at the National Synchrotron Light Source (NSLS) at Brookhaven Lab. The study revealed that at temperatures above 500K, molybdenum-carbide transforms to molybdenum oxide, with a reduction in catalytic activity. No image credit

    “The group at Peking University discovered a new synthetic method, and that was a real breakthrough,” Rodriguez said. “They found a way to get a specific phase—or configuration of the atoms—that is highly active for this reaction.”

    Brookhaven scientists played a key role in deciphering the reasons for the high catalytic activity of this configuration. Rodriguez, Wenqian Xu, and Siyu Yao (then a student at Peking University but now a postdoctoral research fellow at Brookhaven) conducted structural studies using x-ray diffraction at the National Synchrotron Light Source (NSLS) while the catalyst was operating under industrial or technical conditions.

    BNL NSLS

    These operando experiments revealed crucial details about how the structure changed under different operating conditions, including at different temperatures.

    With those structural details in hand, Zhijun Zuo, a visiting professor at Brookhaven from Taiyuan University of Technology, China, and Brookhaven chemist Ping Liu helped to develop models and a theoretical framework to explain why the catalyst works the way it does, using computational resources at Brookhaven’s Center for Functional Nanomaterials (CFN).

    “We modeled different interfaces of gold and molybdenum carbide and studied the reaction mechanism to identify exactly where the reactions take place—the active sites where atoms are binding, and how bonds are breaking and reforming,” she said.

    Additional studies at Oak Ridge National Laboratory’s Center for Nanophase Materials Sciences (CNMS), the Advanced Light Source (ALS) at Lawrence Berkeley National Laboratory, and two synchrotron research facilities in China added to the scientists’ understanding.

    “This is a multipart complex reaction,” said Liu, but she noted one essential factor: “The interaction between the gold and the carbide substrate is very important. Gold usually bonds things very weakly. With this synthesis method we get stronger adherence of gold to molybdenum carbide in a controlled way.”

    That configuration stabilizes the key intermediate that forms as the reaction proceeds, and the stability of that intermediate determines the rate of hydrogen production, she said.

    The Brookhaven team will continue to study this and other carbide catalysts with new capabilities at the National Synchrotron Light Source II (NSLS-II), a new facility that opened at Brookhaven Lab in 2014, replacing NSLS and producing x-rays that are 10,000 times brighter.

    BNL NSLS-II

    With these brighter x-rays, the scientists hope to capture more details of the chemistry in action, including details of the intermediates that form throughout the reaction process to validate the theoretical predictions made in this study.

    The work at Brookhaven Lab was funded by the U.S. DOE Office of Science.

    Additional funders for the overall research project include: the National Basic Research Program of China, the Chinese Academy of Sciences, National Natural Science Foundation of China, Fundamental Research Funds for the Central Universities of China, and the U.S. National Science Foundation.

    NSLS, NSLS-II, CFN, CNMS, and ALS are all DOE Office of Science User Facilities.

    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 8:22 am on June 23, 2017 Permalink | Reply
    Tags: , Catalysis, , How a Single Chemical Bond Balances Cells Between Life and Death, Protein cytochrome c, , , ,   

    From SLAC: “How a Single Chemical Bond Balances Cells Between Life and Death” 


    SLAC Lab

    June 22, 2017
    Amanda Solliday

    1
    An optical laser (green) excites the iron-containing active site of the protein cytochrome c, and then an X-ray laser (white) probes the iron a few femtoseconds to picoseconds later. The critical iron-sulfur bond is broken as the optical laser heats the protein, and rebinds as the system cools. (Greg Stewart/SLAC National Accelerator Laboratory)

    Slight changes in the machinery of a cell determine whether it lives or begins a natural process known as programmed cell death. In many forms of life—from bacteria to humans—a single chemical bond in a protein called cytochrome c can make this call. As long as the bond is intact, the protein transfers electrons needed to produce energy through respiration. When the bond breaks, the protein switches gear and triggers the breakdown of mitochondria, the structures that power the cell’s activities.

    For the first time, scientists have measured exactly how much energy cytochrome c puts into maintaining that bond in a state where it’s strong enough to endure, but easy enough to break when the cell’s life span is ending.

    They used intense X-rays from two facilities, the Linac Coherent Light Source (LCLS) X-ray free-electron laser and the Stanford Synchrotron Radiation Lightsource (SSRL) at the Department of Energy’s SLAC National Accelerator Laboratory.

    SLAC/LCLS

    SLAC/SSRL

    The collaboration, led by Edward Solomon, professor of chemistry at Stanford University and of photon science at SLAC, published their results today in Science.

    “This is a very general yet extremely important process in biochemistry, and with an X-ray laser we now have insight into how this regulation works,” says Roberto Alonso-Mori, LCLS staff scientist and a co-author of the study. “These are processes that are going on a million-fold in our bodies and everywhere there is life.”

    The study marks the first time that anyone has been able to experimentally quantify how the rigid structure of the cytochrome c molecule supports this crucial bond between iron and sulfur atoms in what’s known as an entatic state, where the protein maintains a bond that is just strong enough to perform both of its jobs, says Michael Mara, lead author of the study and a former postdoctoral researcher at Stanford University, now at University of California, Berkeley.

    “This was important because we had shown the bond is weak and shouldn’t be present at room temperature in the absence of the protein constraints,” says Solomon. “But the protein is able to contribute energy to keep this bond intact for electron transfer. In this LCLS experiment, we determined exactly how much energy the rest of the protein contributes to maintaining the bond: about 4 kcal/mol that is derived from an adjacent hydrogen bond network.”

    “We were able to show how nature tunes this system to change the properties on a fundamental level and perform two very different functions,” Mara says. “The energy contribution by cytochrome c is really at a sweet spot. It makes me wonder what sort of similar effects you might see in other protein systems, and it makes us realize that there is exciting new science on the horizon.”

    Ultrafast Changes

    Cytochrome c is present in a wide range of life forms and contributes to both cellular respiration and programmed cell death, the pathway to the natural end of a cell’s life cycle. How exactly the state of the bond relates to these two functions had not yet been demonstrated or quantified.

    Scientists knew from earlier studies that a particular iron-sulfur bond is key. When iron in the protein binds to sulfur contained in one of the protein’s amino-acid building blocks, cytochrome c participates in electron transfer. By transferring electrons, the protein helps generate energy needed for biological processes that maintain life.

    But when cytochrome c encounters cardiolipin, a lipid present in the membrane of the cell’s mitochondria, the iron-sulfur bond breaks, and the protein becomes an enzyme that creates holes in the mitochondria’s outer membrane – the first step in programmed cell death.

    These changes occur incredibly fast, in less than 20 picoseconds, so the experiment required ultrafast pulses of X-rays generated by LCLS to take snapshots of the process.

    “We photoexcited the iron atoms in the protein’s active site—which contains an iron-rich compound known as heme—with an ultrafast laser before probing it with the LCLS X-ray pulses at different time delays,” says Alonso-Mori.

    Each 50-femtosecond laser pulse heated the heme by a couple of hundred degrees. X-ray pulses from LCLS took images of what happened as the heat traveled from the iron to other parts of the protein. After 100 femtoseconds, the iron-sulfur bond would break, only to form again once the sample cooled. Watching this process allowed the scientists to measure energy fluctuations in real time and better understand how this critical bond forms and breaks.

    “The entatic state concept is really interesting, but you have to come up with creative ways to demonstrate and quantify it,” says Ryan Hadt, a former Stanford University doctoral student on an Enrico Fermi Fellowship at Argonne National Laboratory who together with his advisor, Professor Solomon, came up with the idea for the experiment and co-wrote the initial proposal around the time LCLS first came online in 2009.

    “Our research group was excited about this new instrument and wanted to use it to do a definitive experiment,” Hadt adds.

    A Question Raised by Earlier Work

    This experiment builds on an earlier study [JACS] conducted at SSRL that found that the iron-sulfur bond was quite weak, says Thomas Kroll, staff scientist at SSRL and lead author of this prior study.

    In the latest study, spectroscopy at SSRL also built the framework for the LCLS pump-probe experiment. It allowed the scientists to compare what the molecule originally looked like to how it changed when the temperature rose.

    “It’s important to understand how these proteins actually work,” Kroll says. “Because if you don’t understand how they work, how can we create better medicines in an informed and controlled way?”

    Knowledge of cytochrome c’s function is also valuable to the fields of bioenergy and environmental science, since it is a critically important protein in bacteria and plants.

    The DOE Office of Science and the National Institute of General Medical Sciences of the National Institutes of Health supported this research. The Structural Molecular Biology program at SSRL is funded by DOE Office of Science and the National Institutes of Health, National Institute of General Medical Sciences. LCLS and SSRL are DOE Office of Science User Facilities.

    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 11:15 am on March 31, 2017 Permalink | Reply
    Tags: , Catalysis, Methanol, ,   

    From BNL: “Chemists ID Catalytic ‘Key’ for Converting CO2 to Methanol” 

    Brookhaven Lab

    March 23, 2017
    Karen McNulty Walsh,
    (631) 344-8350
    kmcnulty@bnl.gov

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

    Results will guide design of improved catalysts for transforming pollutant to useful chemicals.

    1
    Jingguang Chen and Jose Rodriguez (standing) discuss the catalytic mechanism with Ping Liu and Shyam Kattel (seated).

    Capturing carbon dioxide (CO2) and converting it to useful chemicals such as methanol could reduce both pollution and our dependence on petroleum products. So scientists are intensely interested in the catalysts that facilitate such chemical conversions. Like molecular dealmakers, catalysts bring the reacting chemicals together in a way that makes it easier for them to break and rearrange their chemical bonds. Understanding details of these molecular interactions could point to strategies to improve the catalysts for more energy-efficient reactions.

    With that goal in mind, chemists from the U.S. Department of Energy’s Brookhaven National Laboratory and their collaborators just released results from experiments and computational modeling studies that definitively identify the “active site” of a catalyst commonly used for making methanol from CO2. The results, published in the journal Science, resolve a longstanding debate about exactly which catalytic components take part in the chemical reactions—and should be the focus of efforts to boost performance.

    “This catalyst—made of copper, zinc oxide, and aluminum oxide—is used in industry, but it’s not very efficient or selective,” said Brookhaven chemist Ping Liu, the study’s lead author, who also holds an adjunct position at nearby Stony Brook University (SBU). “We want to improve it, and get it to operate at lower temperatures and lower pressures, which would save energy,” she said.

    But prior to this study, different groups of scientists had proposed two different active sites for the catalyst—a portion of the system with just copper and zinc atoms, or a portion with copper zinc oxide.

    “We wanted to know which part of the molecular structure binds and breaks and makes bonds to convert reactants to product—and how it does that,” said co-author Jose Rodriguez, another Brookhaven chemist associated with SBU.

    To find out, Rodriguez performed a series of laboratory experiments using well-defined model catalysts, including one made of zinc nanoparticles supported on a copper surface, and another with zinc oxide nanoparticles on copper. To tell the two apart, he used an energetic x-ray beam to zap the samples, and measured the properties of electrons emitted. These electronic “signatures” contain information about the oxidation state of the atoms the electrons came from—whether zinc or zinc oxide.

    2
    Brookhaven chemist Ping Liu

    Meanwhile Liu, Jingguang Chen of Brookhaven Lab and Columbia University, and Shyam Kattel, the first author of the paper and a postdoctoral fellow co-advised by Liu and Chen, used computational resources at Brookhaven’s Center for Functional Nanomaterials (CFN) and the National Energy Research Scientific Computing Center (NERSC)—two DOE Office of Science User Facilities—to model how these two types of catalysts would engage in the CO2-to-methanol transformations. These theoretical studies use calculations that take into account the basic principles of breaking and making chemical bonds, including the energy required, the electronic states of the atoms, and the reaction conditions, allowing scientists to derive the reaction rates and determine which catalyst will give the best rate of conversion.

    “We found that copper zinc oxide should give the best results, and that copper zinc is not even stable under reaction conditions,” said Liu. “In fact, it reacts with oxygen and transforms to copper zinc oxide.”

    Those predictions matched what Rodriguez observed in the laboratory. “We found that all the sites participating in these reactions were copper zinc oxide,” he said.

    But don’t forget the copper.

    “In our simulations, all the reaction intermediates—the chemicals that form on the pathway from CO2 to methanol—bind at both the copper and zinc oxide,” Kattel said. “So there’s a synergy between the copper and zinc oxide that accelerates the chemical transformation. You need both the copper and the zinc oxide.”

    3
    Ping Liu and Shyam Kattel with the x-ray source used in this study.

    Optimizing the copper/zinc oxide interface will become the driving principal for designing a new catalyst, the scientists say.

    “This work clearly demonstrates the synergy from combining theoretical and experimental efforts for studying catalytic systems of industrial importance,” said Chen. “We will continue to utilize the same combined approaches in future studies.”

    For example, said Rodriguez, “We’ll try different configurations of the atoms at the copper/zinc oxide interface to see how that affects the reaction rate. Also, we’ll be going from studying the model system to systems that would be more practical for use by industry.”

    An essential tool for this next step will be Brookhaven’s National Synchrotron Light Source II (NSLS-II), another Office of Science User Facility. NSLS-II produces extremely bright beams of x-rays—about 10,000 times brighter than the broad-beam laboratory x-ray source used in this study. Those intense x-ray beams will allow the scientists to take high-resolution snapshots that reveal both structural and chemical information about the catalyst, the reactants, and the chemical intermediates that form as the reaction occurs.

    3
    Brookhaven scientists identified how a zinc/copper (Zn/Cu) catalyst transforms carbon dioxide (two red and one grey balls) and hydrogen (two white balls) to methanol (one grey, one red, and four white balls), a potential fuel. Under reaction conditions, Zn/Cu transforms to ZnO/Cu, where the interface between the ZnO and Cu provides the active sites that allow the formation of methanol.

    “And we’ll continue to expand the theory,” said Liu. “The theory points to the mechanistic details. We want to modify interactions at the copper/zinc oxide interface to see how that affects the activity and efficiency of the catalyst, and we’ll need the theory to move forward with that as well.”

    An additional co-author, Pedro Ramírez of Universidad Central de Venezuela, made important contributions to this study by helping to test the activity of the copper zinc and copper zinc oxide catalysts.

    This research was supported 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 9:02 am on February 23, 2017 Permalink | Reply
    Tags: , Catalysis, , Light-driven reaction converts carbon dioxide into fuel, , , Rhodium nanoparticles   

    From Duke via phys.org: “Light-driven reaction converts carbon dioxide into fuel” 

    Duke Bloc
    Duke Crest

    Duke University

    phys.org

    phys.org

    February 23, 2017

    1
    Duke University researchers have engineered rhodium nanoparticles (blue) that can harness the energy in ultraviolet light and use it to catalyze the conversion of carbon dioxide to methane, a key building block for many types of fuels. Credit: Chad Scales

    Duke University researchers have developed tiny nanoparticles that help convert carbon dioxide into methane using only ultraviolet light as an energy source.

    Having found a catalyst that can do this important chemistry using ultraviolet light, the team now hopes to develop a version that would run on natural sunlight, a potential boon to alternative energy.

    Chemists have long sought an efficient, light-driven catalyst to power this reaction, which could help reduce the growing levels of carbon dioxide in our atmosphere by converting it into methane, a key building block for many types of fuels.

    Not only are the rhodium nanoparticles made more efficient when illuminated by light, they have the advantage of strongly favoring the formation of methane rather than an equal mix of methane and undesirable side-products like carbon monoxide. This strong “selectivity” of the light-driven catalysis may also extend to other important chemical reactions, the researchers say.

    “The fact that you can use light to influence a specific reaction pathway is very exciting,” said Jie Liu, the George B. Geller professor of chemistry at Duke University. “This discovery will really advance the understanding of catalysis.”

    The paper appears online Feb. 23 in Nature Communications.

    Despite being one of the rarest elements on Earth, rhodium plays a surprisingly important role in our everyday lives. Small amounts of the silvery grey metal are used to speed up or “catalyze” a number of key industrial processes, including those that make drugs, detergents and nitrogen fertilizer, and they even play a major role breaking down toxic pollutants in the catalytic converters of our cars.

    Rhodium accelerates these reactions with an added boost of energy, which usually comes in the form of heat because it is easily produced and absorbed. However, high temperatures also cause problems, like shortened catalyst lifetimes and the unwanted synthesis of undesired products.

    2
    Rhodium nanocubes were observed under a transmission electron microscope. Credit: Xiao Zhang

    In the past two decades, scientists have explored new and useful ways that light can be used to add energy to bits of metal shrunk down to the nanoscale, a field called plasmonics.

    “Effectively, plasmonic metal nanoparticles act like little antennas that absorb visible or ultraviolet light very efficiently and can do a number of things like generate strong electric fields,” said Henry Everitt, an adjunct professor of physics at Duke and senior research scientist at the Army’s Aviation and Missile RD&E Center at Redstone Arsenal, AL. “For the last few years there has been a recognition that this property might be applied to catalysis.”

    Xiao Zhang, a graduate student in Jie Liu’s lab, synthesized rhodium nanocubes that were the optimal size for absorbing near-ultraviolet light. He then placed small amounts of the charcoal-colored nanoparticles into a reaction chamber and passed mixtures of carbon dioxide and hydrogen through the powdery material.

    When Zhang heated the nanoparticles to 300 degrees Celsius, the reaction generated an equal mix of methane and carbon monoxide, a poisonous gas. When he turned off the heat and instead illuminated them with a high-powered ultraviolet LED lamp, Zhang was not only surprised to find that carbon dioxide and hydrogen reacted at room temperature, but that the reaction almost exclusively produced methane.

    “We discovered that when we shine light on rhodium nanostructures, we can force the chemical reaction to go in one direction more than another,” Everitt said. “So we get to choose how the reaction goes with light in a way that we can’t do with heat.”

    This selectivity—the ability to control the chemical reaction so that it generates the desired product with little or no side-products—is an important factor in determining the cost and feasibility of industrial-scale reactions, Zhang says.

    “If the reaction has only 50 percent selectivity, then the cost will be double what it would be if the selectively is nearly 100 percent,” Zhang said. “And if the selectivity is very high, you can also save time and energy by not having to purify the product.”

    Now the team plans to test whether their light-powered technique might drive other reactions that are currently catalyzed with heated rhodium metal. By tweaking the size of the rhodium nanoparticles, they also hope to develop a version of the catalyst that is powered by sunlight, creating a solar-powered reaction that could be integrated into renewable energy systems.

    “Our discovery of the unique way light can efficiently, selectively influence catalysis came as a result of an on-going collaboration between experimentalists and theorists,” Liu said. “Professor Weitao Yang’s group in the Duke chemistry department provided critical theoretical insights that helped us understand what was happening. This sort of analysis can be applied to many important chemical reactions, and we have only just begun to explore this exciting new approach to catalysis.”

    Read more at: https://phys.org/news/2017-02-light-driven-reaction-carbon-dioxide-fuel.html#jCp

    See the full article here .

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition
    Duke Campus

    Younger than most other prestigious U.S. research universities, Duke University consistently ranks among the very best. Duke’s graduate and professional schools — in business, divinity, engineering, the environment, law, medicine, nursing and public policy — are among the leaders in their fields. Duke’s home campus is situated on nearly 9,000 acres in Durham, N.C, a city of more than 200,000 people. Duke also is active internationally through the Duke-NUS Graduate Medical School in Singapore, Duke Kunshan University in China and numerous research and education programs across the globe. More than 75 percent of Duke students pursue service-learning opportunities in Durham and around the world through DukeEngage and other programs that advance the university’s mission of “knowledge in service to society.”

     
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: