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  1. Chemistry Department Seminar

    "Methane reforming with CO2 over Ni-Co/CeZrO2 catalysts"

    Presented by Dr. Petar Djinovic, Department for Environmental Sciences and Engineering, Slovenia

    Tuesday, November 28, 2017, 11 am
    Chemistry Bldg, 555, Room 300

    Hosted by: 'Dr. Jose Rodriguez'

    Methane reforming with CO2 presents a possible pathway for valorization of natural gas or biogas to syngas (H2 and CO). Transition metal catalysts suffer from fast deactivation, mainly due to carbon accumulation. This lecture will focus on systematic development of bimetallic NiCo catalysts dispersed over CeZrO2 supports with the final realized aim of enabling long-term stable operation in a wide range of feed compositions. The role of bimetallic cluster size and amount of labile oxygen species in the CeZrO2 support on preventing the carbon accumulation will be discussed. Catalytic tests with isotopically labeled 13CO2, enabled us to identify the contribution of each reactant to the accumulated carbon pool and to distinguish between their reactivity. By replacing lattice oxygen contained in NiCo/CeZrO2 catalysts with isotopically labelled 18O, we were able to monitor transient changes of the catalyst's behavior during methane dry reforming reaction and identify the destination of lattice oxygen in the reaction products.

  2. Chemistry Department Seminar

    "Ambient Pressure XPS as a Tool to Probe Metal-Oxide Catalyst Behaviour"

    Presented by David Grinter, Diamond Light Source Ltd, Diamond House, Harwell Science & Innovation Campus, Didcot, Oxfordshire

    Monday, November 13, 2017, 11 am
    Room 300 - Chemistry Bldg. 555

    Hosted by: 'Sanjaya Senanayake'

    Ambient Pressure X-ray Photoelectron Spectroscopy (AP-XPS) has provided numerous important insights into the behaviour of materials under conditions out of reach of traditional surface science experiments. In the first part of this talk I will highlight the application of AP-XPS to a number of model heterogeneous catalyst systems based on TiO2 and CeO2. Catalysts composed of metal-oxide supported nanoparticles have wide ranging industrial uses with particular energy-related applications including alternative fuel synthesis. I will demonstrate how AP-XPS plays a vital role as part of a multi-technique approach into investigating the reactions that occur at the surface of such materials. Figure 1. Cartoon depiction of the interrogation of a model supported catalyst by AP-XPS, and C1s AP-XPS spectra from a Ni/CeO2 catalyst under methane dry reforming conditions. The second part of my talk will cover the development and recent science commissioning experiments at the newest beamline at Diamond Light Source (UK) – B07 VERSOX (Versatile Soft X-ray). The VERSOX beamline is designed to provide synchrotron radiation soft X-rays between 50 and 2800 eV for studying atomic structures and the electronic/chemical properties of surfaces and interfaces by Photoelectron Spectroscopy (XPS) and Near-Edge X-ray Absorption Spectroscopy (NEXAFS) under wide-ranging pressures (10-10 to 1000 mbar) and temperatures (100-1200 K). The beamline is designed to have separate sources and optical components that will allow independent and parallel operation of two soft X-ray branch lines; B07-C (Ambient Pressure) and B07-B (High Throughput). Figure 2. Beamline layout of B07 VERSOX, and C K-edge XAS spectra from a diamond (001) surface

  3. Chemistry Department Colloquium

    "Can Coherence Enhance Function in Chemical and Biophysical Systems?"

    Presented by Professor Gregory D. Scholes, Dept. of Chemistry, Princeton University

    Monday, September 25, 2017, 11 am
    Hamilton Seminar Room, Bldg. 555

    Hosted by: 'Matt Bird'

    Coherence phenomena arise from interference, or the addition, of wave-like amplitudes in phase. While coherence has been shown to yield transformative new ways for improving function, advances have been limited to pristine matter, as quantum coherence is considered fragile. Recent evidence of coherence in chemical and biological systems, however, concludes that the phenomena is robust and can survive in the face of disorder and noise. I will present the state of recent discoveries. For example, two-dimensional electronic spectroscopy data allow quantitative analysis of vibronic coherence in the photosynthetic light harvesting complexes [1]. I will show how vibronic coherence plays a special role in downhill energy transfer, increasing energy transfer rates remarkably—even when electronic coupling is weak [2]. I will discuss how coherence might be found in electron transfer reactions. I will conclude with a forecast for the role of function as a design element in realizing coherence [3]. [1] Scholes, et al. "Lessons from nature about solar light harvesting" Nature Chem. 3, 763–774 (2011). [2] Dean et al. "Vibronic Enhancement of Algae Light Harvesting" Chem (Cell Press) 1, 858–872 (2016). [3] Scholes, et al. "Optimal Coherence in Chemical and Biophysical Dynamics" Nature 543, 647–656 (2017).

  4. Chemistry Department Colloquium

    ""Taking Snapshots of Reaction Intermediates in Metalloenzymes and Catalysts with X-ray Techniques""

    Presented by Junko Tano, Ph.D., Joint Center for Artificial Photosynthesis, Lawrence Berkeley National Laboratory

    Monday, September 11, 2017, 11 am
    Hamilton Seminar Room, Bldg. 555

    Hosted by: '''Javier Concepcion'''

    Our group is interested in the mechanisms of the catalytic reactions in both natural and inorganic systems. Using various X-ray techniques as tools, we are studying how the catalysts modulate and control multielectron reactions by following the reaction under functional conditions. We have developed spectroscopy and diffraction techniques necessary to fully utilize the capability of the XFELs for a wide variety of metalloenzymes, and to study their chemistry under functional conditions. One of such methods is simultaneous data collection for X-ray crystallography and X-ray spectroscopy, to determine the overall structural changes of proteins and the chemical changes at metal catalytic sites. In parallel to the detection techniques, we have developed an efficient sample delivery method that involves deposition of droplets on a conveyor belt. This 'Droplet on Tape' (DOT) method, delivers a single drop of the crystal suspension or solution sample onto a tape, which then can be transported to the X ray intersection point with a variable delay in time. In the process, the sample is photochemically or chemically activated at various time delays to capture reaction intermediates with crystallography and spectroscopy. In the field of inorganic catalysts, improved catalysts for electroreduction of carbon dioxide are highly important for promoting the generation of carbon-based reduction products. To gain a fundamental understanding needed to tailor novel catalysts, in particular for the selectivity of the products, the information of the early steps of the electroreduction process on catalyst surfaces is important. We have optimized and utilized surface-sensitive soft and hard X-ray techniques, including grazing incident X-ray absorption spectroscopy, X-ray diffraction, and ambient pressure X-ray photoemission spectroscopy to investigate the interaction of metal catalytic surfaces with electrolytes and/or gases (CO2 and/or H2O) under in situ/operando conditions.

  5. Chemistry Department Colloquium

    "Chemical Kinetics and Tunneling on Interstellar Dust Grains"

    Presented by Professor Gunnar Nyman, Dept. of Chemistry and Molecular Biology, University of Gothenburg, Goteborg, Sweden, Sweden

    Monday, August 28, 2017, 11 am
    Hamilton Seminar Room, Bldg. 555

    Hosted by: 'Greg Hall'

    Dust can be important for the interstellar chemistry in the gas phase. The process where an atom or molecule lands on a dust grain, diffuses on the grain and meets another atom or molecule to form a new species, which can then desorb from the grain is essentially a description of how heterogeneous catalysis occurs. The importance of this process would depend on the diffusion rate of at least one of the adsorbed species and the products desorbing from the grain. This is particularly relevant for H2 formation in interstellar space. Atoms and molecules adsorbed on grains may be modeled as sitting in a local potential energy minimum. Diffusion can then be thought of as occurring through consecutive jumps from one minimum to another. The transition rate constants between adjacent minima can be estimated by for instance transition state theory. Such rate constants can in turn be used in Kinetic Monte Carlo simulation to obtain diffusion rates. Light atoms, particularly hydrogen atoms can tunnel through potential energy barriers. Tunneling may therefore substantially increase the rate of transition from one minimum to the next and thus the diffusion rate. Deuterium tunnels less efficiently than the lighter isotope and kinetic isotope effects (KIEs) are thus expected. Laboratory experiments have been carried out where either H atoms or D atoms diffuse on amorphous or polycrystalline ice at 10 K. Interesting KIEs were obtained.

  6. Nuclear Theory/RIKEN Seminar

    "Better fitting through (fictitious) chemistry"

    Presented by Pasi Huovinen, Uniwersytet Wroclawski

    Monday, June 19, 2017, 10 am
    Small Seminar Room, Bldg. 510

    Hosted by: ''Heikki Mantysaari''

    One of the puzzles we have faced at the LHC is why the thermal models apparently cannot properly fit the yield of protons. I will explore how the fit improves if we assume that nucleon-antinucleon annihilations freeze-out way later than all other number changing processes or if strange particles freeze-out before non-strange particles, and how this affects the final particle distributions in hydrodynamical calculations.

  7. Chemistry Department Seminar

    "Modeling of the synergistic behavior of adjacent Pt{111}"

    Presented by Thobani Gambu, Catalysis Institute, Department of Chemical Engineering,, South Africa

    Wednesday, June 14, 2017, 4 pm
    Room 300 - Chemistry Bldg. 555

    Hosted by: 'Miomir Vukmirovic'

    Abstract The oxygen reduction reaction (ORR) is particularly interesting, especially in the context of fuel cells and metal-air batteries [1,2]. The loss in cell potential at low current densities accounts for over 67% of the total potential loss and is primarily attributed to slow ORR kinetics [3]. When modelling the overall ORR activity over multifaceted Pt nanocrystallites, it is generally assumed that the different surface regions, i.e. terraces, edges and corners, are kinetically isolated and can therefore be modelled independently [4-5]. A range of ORR mechanisms have been proposed and the corresponding energetics, i.e. reaction and activation energies, have been calculated and reported [6-8]. A closer look at the reaction mechanisms and energetics shows that (1) O and OH removal over a Pt(111) and Pt(100) surface, respectively, is the most energetically hindered step, [6-8] and (2) facilitating an OH/O exchange between the Pt{111} and Pt{100} facets may result in improved ORR specific activity. Therefore, this study investigates the extent of O and OH cross-surface diffusion between the Pt{111} and Pt{100} facets of a pure Pt nanorod model. Furthermore, the cross-surface diffusion of OH on modified Pt nanorod models is reported. References 1. Gewirth, A. A. and Thorum, M. S. Inorg. Chem. 49, 3557 (2010). 2. Nie, Y., Li, L. and Wei, Z. Chem. Soc. Rev. 44, 2168 (2015). 3. Gasteiger, H. A., Kocha, S. S. et al. Appl. Catal. B Environ. 56, 9 (2005). 4. Tripkovic, V., Cerri, I. et al. Catal. Letters. 144, 380 (2014). 5. Nesselberger, M., Ashton, S. et al. J. Am. Chem. Soc. 133, 17428 (2011). 6. Li, K., Li, Y. et al. J. Mater. Chem. A. 3, 11444 (2015). 7. Duan, Z. and Wang, G. J. Phys. Chem. C. 117, 6284 (2013). 8. Ford, D. C., Nilekar, A. U. et al. Surf. Sci. 604, 1565 (2010).

  8. CFN Colloquium

    "Materials Chemistry via Electrochemistry: Electrochemical Synthesis of Semiconductor Electrodes and Catalysts for Use in Solar Energy Conversion"

    Presented by Kyoung-Shin Choi, Department of Chemistry, University of Wisconsin-Madison, Madison, WI 53796

    Thursday, June 1, 2017, 4 pm
    CFN, Bldg 735, 2nd Floor Seminar Room

    Hosted by: 'Mingzhao Lu'

    Harvesting energy directly from sunlight as nature accomplishes through photosynthesis is a very attractive and desirable way to solve the energy challenge. Many efforts have been made to find appropriate materials and systems that can utilize solar energy to produce chemical fuels. One of the most viable options is the construction of a photoelectrochemical cell that can directly utilize solar energy to drive chemical reactions (e.g. reduction of water to H2, reduction of CO2 to carbon-based molecules). For successful construction of photoelectrochemical cells, simultaneous developments of photoelectrodes, which will efficiently capture photons to generate and separate electron-hole pairs, and catalysts, which will facilitate the use of photogenerated electrons and holes for desired interfacial charge transfer reactions, are necessary. Furthermore, optimally interfacing photoelectrodes and catalysts is critical because the photoelectrode/catalyst interface can govern the overall efficiency of the integrated photoelectrode system. Our research group has been developing new electrochemical synthesis conditions to produce semiconductor electrodes and catalysts with precisely controlled compositions and architectures. In this seminar, we will discuss synthesis and properties of a few promising photoelectrode and catalyst systems for use in solar energy conversion. New synthesis strategies to improve photon absorption, charge transport properties, and catalytic properties will be presented. We will also discuss various strategies to increase the overall utility and efficiency of the photoelectrochemical cells, which include our new results on electrochemical and photoelectrochemical biomass conversion.

  9. Chemistry Department Colloquium

    "Adsorption and oxidation reactions on RuO2 and IrO2 surfaces"

    Presented by Jason F. Weaver, University of Florida, Dept. of Chemical Engineering

    Tuesday, May 30, 2017, 11 am
    Hamilton Seminar Room, Bldg. 555

    Hosted by: 'Sanjaya Senanayake'

    Interest in the surface chemistry of late transition-metal oxides has been stimulated by observations that the formation of metal oxide layers tends to dramatically alter the catalytic performance of transition metals in applications of oxidation catalysis. In this talk, I will discuss our recent investigations of the growth and chemical properties of rutile RuO2 and IrO2 surfaces. Our interest in these oxides derives mainly from computational predictions that CH4 binds strongly and should undergo C-H bond activation at low temperature on certain facets of IrO2. I will discuss our investigations of the oxidation of metallic Ir surfaces by O-atom beams as well as O2 at pressures above 1 Torr. We find that stoichiometrically-terminated IrO2(110) layers could only be formed by oxidizing Ir(111) and Ir(100) at sufficiently high temperature and O2 pressure. I will discuss the binding characteristics of small molecules, and our recent discovery of highly facile CH4 activation on the IrO2(110) surface at temperatures as low as 150 K. We show that CH4 activation occurs by a mechanism wherein a molecularly-adsorbed ?-complex serves as the precursor for CH4 dissociation on the IrO2(110) surface and that the barrier for C-H bond cleavage is nearly 10 kJ/mol less than the molecular binding energy. Lastly, I will discuss results showing how the partial replacement of surface O-atoms with Cl-atoms alters the oxidation chemistry of methanol on RuO2(110), and may provide an approach for modifying the selectivity of RuO2 and IrO2 surfaces for other oxidation chemistries.

  10. Chemistry Department Colloquium

    "Electrocatalysts for Oxygen Reduction Reaction"

    Presented by Minhua Shao, The Hong Kong University of Science and Technology, Department of Chemical and Biomolecular Engineering, Hong Kong

    Friday, May 26, 2017, 11 am
    Hamilton Seminar Room, Bldg. 555

    Hosted by: 'Alex Harris'

    Low temperature fuel cells are electrochemical devices that convert chemical energy directly to electricity. They have great potential for both stationary and transportation applications and are expected to help address the energy and environmental problems that have become prevalent in our society. Despite their great promise, commercialization has been hindered by lower than predicted efficiencies and high loading of Pt-based electrocatalysts in the electrodes. For more than five decades, extensive work has being focused on the development of novel electrocatalysts for fuel cell reactions. In this talk, I will present recent progress in developing advanced electrocatalysts mainly for oxygen reduction reaction in my group, with an emphasis on core-shell and shape controlled nanocrystals. Fuel cell testing results on these advanced catalysts will be shared. The mechanisms for activity enhancement will also be discussed based on the results of density functional theory calculations.

  11. Computational Science Initiative Event

    "Enabling Computational Chemistry With New Algorithms on Next-Generation Platform"

    Presented by Wibe deJong, Lawrence Berkeley Nat. Lab

    Monday, May 8, 2017, 11 am
    Seminar Room, Bldg. 725

    Hosted by: 'Kerstin Kleese van Dam'

    With the advent of exascale computing the field of computational chemistry is on the verge of entering a new era of modeling. Large computing resources can enable researchers to tackle scientific problems that are larger and more realistic than ever before, and to include more of the complex dynamical behavior of nature. However, the future exascale architectures will be significantly different and require advances in algorithms and new programming paradigms. We will discuss some of the work on developing scalable algorithms for strongly correlated systems, simulations of complexes in dynamical environments, and complex spectra. Significant improvements will be reported in our development efforts of a full threaded plane wave ab initio molecular dynamics code in NWChem on Intel Phi platforms. Finally, we will demonstrate advances in the parallel communication layer Global Arrays utlizing LBNL's GasNET and barrier elision techniques. Bio: Bert de Jong leads the Computational Chemistry, Materials, and Climate Group at LBNL. He has a background in general chemistry, chemical engineering and high performance computational chemistry, with specialization and strong capabilities in modeling heavy element chemistry. He is a main developer of the NWChem software at the EMSL, one of four developers of the unique fully relativistic software MOLFDIR for quantum chemistry. Prior to joining Berkeley Lab, de Jong was at PNNL, where he lead the High Performance Software Development Group responsible for NWChem. He has published 89 journal papers, 14 conference papers and 7 book chapters and has given over 65 invited presentations and lectures at international conferences and universities.De Jong earned his doctorate in theoretical chemistry in 1998 from the University of Groningen in the Netherlands. He was a postdoctoral fellow at PNNL before transitioning to a staff member in 2000.

  12. Chemistry Department Seminar

    "The Representation of Photosynthesis in Earth System Models"

    Presented by Alistair Rogers, Department of Environmental & Climate Sciences, Brookhaven National Laboratory

    Monday, May 1, 2017, 11 am
    Hamilton Seminar Room, Bldg. 555

    Hosted by: 'Sanjaya Senanayake'

    The primary goal of Earth System Models is to improve understanding and projection of global change which is driven principally by the elevation of atmospheric carbon dioxide concentration resulting from the use of fossil energy. Many of the observed and projected impacts of global change portend increasing environmental and economic risk, yet the uncertainty surrounding the projection of our future climate remains unacceptably high. Although annual carbon dioxide emissions associated with anthropogenic activity are notable, they are a fraction of the size of the carbon fluxes associated with the global carbon cycle. Terrestrial photosynthesis (gross primary productivity) is the largest of these carbon fluxes and is the gatekeeper process for the uncertain subsidy of fossil fuel use provided by the terrestrial carbon sink. Therefore, increasing confidence in model representation of photosynthesis - particularly the response of photosynthesis to rising carbon dioxide concentration and temperature - is an essential part of reducing uncertainty in projections of global change. Focusing on leaf level physiology, I will discuss the how parametric and structural representation of photosynthesis impacts model responses to key environmental drivers and show how data from recent field work in the Arctic and the tropics is aiming to inform model parameterization and representation of photosynthesis in next generation models.

  13. Chemistry Department Colloquium

    "Designing Catalysts Using Atomic Layer Deposition"

    Presented by Stacey F. Bent, Stanford University, Department of Chemical Engineering

    Wednesday, April 26, 2017, 11 am
    Hamilton Seminar Room, Bldg. 555

    Hosted by: ''Alex Harris''

    With the intensifying global need for alternative energy and fuels, there is strong interest in the development of efficient catalysts that can drive the chemical conversion of renewable resources into useful products. This talk will describe the use of an emerging synthetic strategy, atomic layer deposition (ALD), to generate nanoscale catalyst materials with a high level of control over composition, structure, and thickness. Two catalytic applications will be described. The first example is the conversion of synthesis gas (CO + H2) to synthetic liquid fuels and high-value chemicals using supported metal, heterogeneous catalysts. The promotion of rhodium-based catalysts, which have intrinsic selectivity towards desirable higher oxygenate production, is explored using various metal oxides deposited by ALD. The interactions between catalyst and promoter are studied using a variety of experimental techniques complemented by theory and the promoted catalysts are shown to have an increase in activity and higher oxygenate selectivity relative to unpromoted Rh nanoparticles. The second application is electrocatalysis for water splitting to produce hydrogen for fuel. We show that nanometer thick electrocatalyst layers of earth abundant materials deposited by ALD are active for the oxygen evolution reaction, an important reaction in the conversion of sunlight to fuels. We also demonstrate use of this layer-by-layer synthetic strategy to explore other metal oxides for electrocatalysis, to study charge transport limitations in the catalysts, and to achieve compositional control over ternary metal oxide and doped metal oxide thin films. The potential of atomic layer deposition to synthesize nanoscale materials for catalytic applications will be discussed.

  14. Chemistry Department Seminar

    "Experimental and computational approaches to divine gene function in plants"

    Presented by Dr. Ian Blaby, Brookhaven National Laboratory, Biology Department

    Monday, April 17, 2017, 11 am
    Hamilton Seminar Room, Bldg. 555

    Hosted by: ''Sanjaya Senanayake''

    The availability of whole-genome sequences has ushered in a new era of biological research. While these resources are invaluable, the data serve to underscore the extent of biological complexity, and have provided the framework by which our lack of knowledge and progress can be measured. For instance, even in very well studied model organisms, over 40% of genes are of unknown function. In less characterized complex organisms, such as bioenergy crops, up to 80% of all genes in a given genome are of unknown or very limited function. Indeed, a complete functional understanding (i.e. combined knowledge of biochemical activity, biological role and compartmentalization) is missing for ~95% of plant genes. This fundamental knowledge gap undermines the ability of systems scientists to realize the potential of genomic science and impedes our ability to leverage photosynthetic organisms to meet national energy needs. To remove this obstacle, we are addressing the function of plant proteins at the cellular and subcellular levels by integrating multi-dimensional dataypes: in vivo analyses employing single-celled plants and photosynthetic bacteria, high-throughput automation, in vitro protein characterization and structure, and computation. Modern sequencing, functional genomics and genome-editing technologies coupled with high-throughput approaches accelerate the gathering of informative data; our group specializes in utilizing multi-sourced data types in combination with targeted molecular approaches to reduce the knowledge gap in foundational plant research.

  15. Chemistry Department Colloquium

    "Excitons, Charge-Transfer states, Charge-Separated states, and Carriers: the importance of charge delocalization"

    Presented by Dr. Garry Rumbles, National Renewable Energy Laboratory, Golden Colorado

    Friday, April 7, 2017, 11 am
    Hamilton Seminar Room, Bldg. 555

    Hosted by: ''Alex Harris''

    Although organic photovoltaic (OPV) devices have increased in solar harvesting efficiency, there remains much debate surrounding the mechanism by which the active medium absorbs solar radiation and creates high yields of free, mobile carriers that do not immediately recombine. The uncertainty arises from the low dielectric constant of the active material, normally a conjugated polymer and a fullerene, which lack the ability to screen the coulombic interaction between charges. This presentation will discuss the role of charge delocalization on producing a charge-separated state, where the electron and hole are created at a larger distance than that found in a charge- transfer state. It will examine the important role of the solid-state microstructure of the polymer and its impact on delocalizing the hole, and also on the aggregation properties of the electron acceptor and its role on delocalizing the electrons. In addition, the role that time-resolved microwave conductivity (fp-TRMC) plays in helping to unravel this story will be explained.

  16. Chemistry Department Seminar

    "Reactions of the Simplest Criegee Intermediate with Inorganic Acids and Alcohols"

    Presented by Professor Craig Murray, Department of Chemistry, University of California, Irvine

    Thursday, April 6, 2017, 11 am
    Room 300, Chemistry Bldg. 555

    Hosted by: 'Trevor Sears'

    Carbonyl oxides, known as Criegee intermediates, are reactive radicals formed via alkene ozonolysis that are thought to play an important role in tropospheric chemistry, including reactions that lead to aerosol particle formation. Globally, reaction with water (or water dimer) is thought to be the major sink for formaldehyde oxide (CH2OO), while larger species tend to undergo thermal unimolecular decomposition (Osborn and Taatjes, 2015). However, reactions of CH2OO with trace atmospheric species can be locally competitive under certain conditions. We have applied broadband transient absorption spectroscopy (Foreman et al., 2015) to probe CH2OO via the B-1A′–X-1A′ transition in the near UV to directly measure rate constants for the reactions of CH2OO with inorganic acids and alcohols. Reaction with nitric acid (HNO3) in particular is exceptionally fast, indicating that it may be competitive with water in polluted urban areas, particularly under conditions of lower relative humidity and lower temperature (Foreman et al., 2016). The experimental measurements are supported by complementary ab initio that identify likely products and elucidate mechanistic details.

  17. Chemistry Department Seminar

    "How Can the Hard X-ray Spectroscopy Program Contribute to the Operando Field"

    Presented by Dr. Klaus Attenkofer, Photo Sciences - Brookhaven National Laboratory

    Monday, March 27, 2017, 11 am
    Room 300, Chemistry Bldg. 555

    Hosted by: 'Sanjaya Senanayake'

    With the transition from NSLS to NSLS-II the landscape of hard x-ray spectroscopy has dramatically changed. Resulting from the needs to understand not only a material but also its behavior within a complex device structure and ultimately to demonstrate its contributions to the functional characteristics of the device, the experimental demands are driving the development of the facilities, their operation and access conditions, and their embedding in a larger characterization and computation network at NSLS-II, the laboratory, and collaborators on the national and international level. The talk will give a short overview on the status and plans of the facilities; it will also show on examples how the program focuses on specific areas in which future leadership is targeted. An important aspect of these discussions is a requirement-analysis describing the essential components allowing to use the developed tools in applied and industrial science.

  18. Chemistry Department Colloquium

    "Computational Design of Bimetallic Nanocrystals"

    Presented by Konstantin M. Neyman, Universtat de Barcelona, Spain

    Monday, March 20, 2017, 11 am
    Hamilton Seminar Room, Bldg. 555

    Hosted by: 'Jose Rodriguez'

    Metal nanoparticles are key components of various functional materials, including catalysts. However, properties of monometallic particles are often insufficiently versatile, which limits their applications. Properties of mixed-metal nanoparticles (nanoalloys) can be tailored for a given application much easier. Yet, it is very laborious to determine the atomically resolved composition (chemical ordering) in nanoalloys, which is required for rationalizing their reactivity. We developed a method to optimize chemical ordering in nanoalloys using density functional calculations [1,2], which is applicable to various combinations of transition metals with each other and with s,p-elements [1-5]. The method allows one to predict energetically stable atomically resolved structures of nanoalloys, which can be then manufactured. I will outline the method and illustrate its applications to nanoalloys of Pd [1,2], Pt [3,4] and Ni [5]. Our new method enables generating databases of structures and energies of bimetallic nanoalloys spanning the Periodic Table. Its simplicity and reliability allows to provide researchers with unique opportunity to efficiently perform simulations of various nanoalloys with thousands of atoms. Applications of the method can radically accelerate design of tailor- made nanoalloys and deepen the general understanding of chemical bonding in nanoalloys. In the beginning of the talk I will also highlight some of my other other studies related to approaching complexity of nanomaterials for catalysis by density functional modelling [6-10]. References [1] S.M. Kozlov, G. Kovács, R. Ferrando, K.M. Neyman. How to determine accurate chemical ordering in several nanometer large bimetallic crystallites from electronic structure calculations. Chemical Science 6 (2015) 3868 [2] G. Kovács, S.M. Kozlov, K.M. Neyman. Versatile optimization of chemical ordering in bimetallic nanoparticles. J. Phys. Chem. C 121 (2017), doi: 10.1021/acs.jpcc.6b11923

  19. Center for Functional Nanomaterials Colloquium

    "Materials Chemistry of Carbon Nanomaterials and their Integration in Electronic Devices"

    Presented by George Tulevski, IBM

    Thursday, January 12, 2017, 4 pm
    CFN, Bldg 735, 2nd Floor Seminar Room

    Hosted by: ''Matt Sfeir''

    The exceptional electronic properties of carbon nanotubes (CNTs) make them promising candidates for integration into a variety of future technologies. The key technical bottlenecks to progress on this front are mainly materials and chemistry related. How do we get the exact type of CNTs we want? How do we quantify the purity of these materials? How do we organize and place them on substrates? The solutions to these problems can enable a wide range of applications in the electronics industry. In this talk, I will present recent progress in trying to solve these problems. I will also discuss how these results have enabled the fabrication of transparent conducting electrodes (along with their integration in photovoltaic cells and OLEDs), high performance thin-film transistors on both rigid and flexible substrates and progress towards a CNT-based logic technology.

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