BNL Home
April 2017
Sunday Monday Tuesday Wednesday Thursday Friday Saturday

1

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  1. Chemistry Department Seminar

    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.

7

  1. Chemistry Department Colloquium

    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.

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17

  1. Chemistry Department Seminar

    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.

18

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26

  1. APR

    26

    Wednesday

    Chemistry Department Colloquium

    11 am, Hamilton Seminar Room, Bldg. 555

    Wednesday, April 26, 2017, 11:00 am

    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.

27

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  1. APR

    26

    Wednesday

    Chemistry Department Colloquium

    "Designing Catalysts Using Atomic Layer Deposition"

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

    11 am, Hamilton Seminar Room, Bldg. 555

    Wednesday, April 26, 2017, 11:00 am

    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.

  2. MAY

    8

    Monday

    Computational Science Initiative Event

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

    Presented by Wibe deJong, Lawrence Berkeley Nat. Lab

    11 am, Seminar Room, Bldg. 725

    Monday, May 8, 2017, 11:00 am

    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.

  3. MAY

    30

    Tuesday

    Chemistry Department Colloquium

    "Adsorption and oxidation reactions on RuO2 and IrO2 surfaces"

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

    11 am, Hamilton Seminar Room, Bldg. 555

    Tuesday, May 30, 2017, 11:00 am

    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.

  4. JUN

    1

    Thursday

    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

    4 pm, CFN, Bldg 735, 2nd Floor Seminar Room

    Thursday, June 1, 2017, 4:00 pm

    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.

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. 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

  6. 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.

  7. Biology Department Seminar

    "Blueprints for Photosynthesis: The genetics and biochemistry of photosystem II assembly"

    Presented by Robert Calderon, University of California, Berkley

    Friday, November 18, 2016, 11 am
    John Dunn Seminar Room, Bldg. 463

    Hosted by: ''Ian Blaby''

    Photosystem II (PSII) is the protein-pigment complex in oxygenic photosynthesis that uses light energy to catalyze the oxidation of water. How the subunits and cofactors that make up this enzyme are properly assembled into a functional photosystem remains unknown. To uncover new components in this process, I undertook a chlorophyll fluorescence-based mutant screen in the unicellular green alga Chlamydomonas reinhardtii. One isolated mutant had no detectable PSII activity, whereas other components of the photosynthetic electron transport chain were still functional. This defect was shown to be due specifically to the absence of a gene, RBD1, encoding a thylakoid membrane-bound iron-sulfur protein known as a rubredoxin. Examination of cyanobacterial (Synechocystis) and plant (Arabidopsis) mutants lacking the homolog of RBD1 revealed PSII-specific phenotypes, supporting the hypothesis that this rubredoxin has a conserved role in PSII-containing organisms. The phylogenetic profile of the RBD1 gene led us to hypothesize that other genes involved in PSII assembly or function might show a similar phylogenetic distribution. We devised a computational approach to find these genes and preliminary results indicate that some genes found through this method might indeed be associated with PSII function or assembly.

  8. PubSci

    "The Cutting Edge of Chemistry and the Reactions Powering the World"

    Tuesday, November 15, 2016, 7 pm
    Brewology Gastropub, 201 Main St., Port Jefferson,

    PubSci, a science café presented by Brookhaven National Laboratory, is back with its seventh installment of casual conversations about the Lab's world-class research. Invite your friends and colleagues to a lively discussion for the science-interested (or just plain curious) and chat with scientists in an informal and friendly way. No stuffy lectures – just a dynamic talk with a diverse audience and a lot of good cheer. Next up: "The Cutting Edge of Chemistry and the Reactions Powering the World." Join Brookhaven scientists to discuss some of the grand energy challenges of the 21st century and the role of fundamental research in energy generation. How does understanding chemical conversion help us design advanced fuels? How much energy can we squeeze out of the periodic table? How do we study catalysts in real time?

  9. Chemistry Department Colloquium

    "In Situ and Operando Electron Microscopy Imaging and Spectroscopy of Thermal and Light Driven Catalysts"

    Presented by Peter A. Crozier,, School for the Engineering of Matter, Transport and Energy,

    Friday, August 26, 2016, 11 am
    Hamilton Seminar Room, Bldg. 555

    Hosted by: 'Sanjaya Senanayake'

    CHEMISTRY COLLOQUIUM Friday, August 26th, 2016 11:00am – Hamilton Seminar Room Chemistry Building, 555 Understanding the fundamental relationships between catalyst activity and structure at the nanoscale will enable the improved design of catalysts. In-situ and operando environmental transmission electron microscopy (ETEM) are powerful techniques for the investigation of structure-reactivity relationships in high surface area catalysts under reaction conditions. With new instruments, atomic resolution imaging and spectroscopy can be carried out in the presence of gas, liquid, light and thermal stimuli. The combination of mass spectrometry and electron energy-loss spectroscopy (EELS) allows catalytic products to be detected and quantified directly in the electron microscope. With aberration corrected TEM, the positions of atomic columns on nanoparticles surfaces can be observed and correlated with changes in conversion. New developments in monochromated EELS allow the electronic and vibrational structure of catalyst surfaces to be probed with focused electron beams. Using the so-called "aloof beam" approach to EELS, radiation damage is minimized potentially allowing electronic surface and defect states to be observed and correlated with catalytic properties. Examples will be shown which illustrate the information that can be obtained with modern electron imaging and spectroscopy. In situ observations of the structural and chemical changes during activation of reforming catalysts consisting of Ni or NiRu nanoparticles on non-reducible (SiO2) and reducible (CeO2 or doped CeO2) supports will be described. The evolution of the metal and bimetallic structures can be correlated with conversion and selectivity to provide an understanding of nanoscale structure-reactivity relations for partial oxidation and steam reforming. Recent advances in the development of operando methods will be illustrated for CO oxidation on Ru where correlating reactio

  10. Chemistry Department Colloquium

    "LIGHT INDUCED REDOX CATALYSIS FOR ARTIFICIAL PHOTOSYNTHESIS"

    Presented by Antoni Llobet, Institute of Chemical Research of Catalonia (ICIQ), Barcelona Institute of Science and Technology, Avinguda Països Catalans 16, E-43007 Tarragona, Spain., Spain

    Friday, August 19, 2016, 10 am
    Hamilton Seminar Room, Bldg. 555

    Hosted by: 'Dmitry Polyansky'

    Abstract The replacement of fossil fuels by a clean and renewable energy source is one of the most urgent and challenging issues our society is facing today, which is why intense research is devoted to this topic today. Nature has been using sunlight as the primary energy input to oxidize water and generate carbohydrates (a solar fuel) for over a billion years. Inspired, but not constrained, by nature, artificial systems[1] can be designed to carry out redox catalysis induced by light for instance to oxidize water and reduce protons or other organic compounds to generate useful chemical fuels. In this context this contribution will present a variety of molecular water oxidation and proton reduction catalysts[2] based on first row and second row transition metal complexes. Their capacity to carry out these reactions induced by light will be analyzed and discussed.[3] References [1] Berardi, S.; Drouet, S.; Francàs, L.; Gimbert-Suriñach, C.; Guttentag, M.; Richmond, C.; Stoll, T.; Llobet, A. Chem. Soc. Rev., 2014, 43, 7501-7519. [2] (a) Neudeck, S.; Maji, S.; López, I.; Meyer, S.; Meyer, F.; Llobet, A. J. Am. Chem. Soc. 2014, 136, 24-27. (b) López, I.; Ertem, M. Z.; Maji, S.; Benet-Buchholz, J.; Keidel, A.; Kuhlmann, U.; Hildebrandt, P.; Cramer, C. J.; Batista, V. S.; Llobet, A. Angew. Chem. Int. Ed. 2014, 53, 205-210. (c) Garrido-Barros, P.; Funes-Ardoiz, I.; Drouet, S.; Benet-Buchholz, J.; Maseras, F.; Llobet, A. J. Am. Chem. Soc. 2015, 137, 6758-6761. (d) Matheu, R.; Ertem, M.Z.; Benet-Buchholz, J.; Coronado, E.; Batista, V. S.; Sala, X.; Llobet, A. J. Am. Chem. Soc. 2015, 137, 10786-10795. [3] (a) Farras, P.; Di Giovanni, C.; Clifford, J. N.; Garrido-Barros, P.; Palomares, E.; Llobet, A. Green Chem., 2016, 18, 255-260. b) Moonshiram, D.; Gimbert-Suriñach, C.; Guda, A.; Picon, A.; Lehmann, C. S.; Zhang, X.; Doumy, G.; March, A. M.; Benet-Buchholz, J.; Soldatov, A.; Llobet, A.; Southworth, S. H. J. Am. Chem. Soc. 2016, 138

  11. Chemistry Department Seminar

    "Application of X-ray Absorption Spectroscopy to Electrocatalysts"

    Presented by Nebojsa Marinkovic, Synchrotron Catalysis Consortium and Department of Chemical Engineering, Columbia University, NY

    Monday, July 25, 2016, 10 am
    Room 300, Chemistry Bldg. 555 - 3rd Floor

    Hosted by: ''Miomir Vukmirovic''

    The synchrotron-based X-ray absorption spectroscopy (XAS) is a non-destructive technique that measures the changes in the x-ray absorption coefficient of a material as the function of energy. The X-rays are highly penetrating and allow studies of gases, solids or liquid at concentrations of as low as a few ppm. As an element-specific technique, XAS can resolve the oxidation state of the element, as well as its coordination environment and subtle changes within. Its unique power is found in application to metal clusters, particularly in nanomaterials. It can resolve the inner structure of a nanoparticle composed of two or more elements, i.e. solid solution, aggregate mixtures, or core-shell particles in which one metal is present mostly in the center of the particle (core), and the other forms a shell around it. The latter nanoparticle systems are of a special interest for electrocatalysts composed of expensive noble metals because minimizing the noble metal content is the goal of the present technology development. The lecture focuses on in-situ characterization of electrochemical systems composed of two or more metal atoms for fuel cell technology. Selected examples show the changes in the inner structure of the catalyst during the oxidation of fuels on anode systems, or oxygen reduction on cathodes, including size, shape and partial oxidation state, and correlate them to the catalyst's activity and stability.

  12. Chemistry Department Seminar

    "Artificial Photosynthesis on III-Nitride Nanowire Arrays"

    Presented by Zetian Mi, Department of Electrical and Computer Engineering, McGill University, Canada

    Tuesday, June 21, 2016, 11 am
    Room 300, 3rd Floor, Chemistry Bldg. 555

    Hosted by: ''Jim Muckerman''

    Abstract: High efficiency artificial photosynthesis, that can convert solar energy directly into chemical fuels, has been extensively investigated. Critical to this development is the stable and efficient generation of H2 from water under direct sunlight irradiation. To date, however, success in finding abundant visible-light active photocatalyst has been very limited. Recently, metal-nitrides have attracted considerable attention for applications in artificial photosynthesis, due to their extraordinary stability and tunable energy bandgap across nearly the entire solar spectrum. Moreover, III-nitrides are the only known material whose energy bandgap can straddle the redox potential of water under deep visible and near-infrared light irradiation. In 2011, we have demonstrated, for the first time, spontaneous overall water splitting on GaN nanowire arrays. We have discovered that the quantum efficiency for overall water splitting and hydrogen generation on the emerging nanostructured photocatalysts can be dramatically enhanced by precisely tuning the surface Fermi-level. We have further developed InGaN/GaN nanowire photoanodes and photocathodes, which are monolithically integrated on Si solar cell wafer through a polarization-enhanced tunnel junction. The devices exhibit highly stable hydrogen generation under simulated sunlight illumination. Such high efficiency photocatalysts also offer an entirely new avenue for recycling anthropogenic carbon dioxide to renewable fuels and for reducing nitrogen to ammonia. Zetian Mi is an Associate Professor in the Department of Electrical and Computer Engineering at McGill University. He received the Ph.D. degree in Applied Physics from the University of Michigan, Ann Arbor in 2006. Prof. Mi's teaching and research interests are in the areas of III-nitride semiconductors, solid state lighting, nanophotonics, and solar fuels. He has published 7 book chapters and more than 150 refereed journal papers. He has received ma

  13. Center for Functional Nanomaterials Seminar

    "Molecular Cluster as Superatoms in Solid-State Chemistry"

    Presented by Xavier Roy, Columbia University

    Thursday, June 9, 2016, 1:30 pm
    CFN, Bldg 735, Conference Room A, 1st Floor

    Hosted by: ''''Matthew Sfeir''''

    Traditional solid-state compounds are infinite crystalline arrays of densely packed atoms. The emergence of collective properties in structured clusters of atoms, which we term "superatoms", offers a new class of fundamental building blocks for assembling materials. The superatom concept has the potential to usher in a new era where materials are designed to have a specific function, rather than discovered by trial and error. To realize this concept, we are exploring the use of molecular clusters as superatomic building blocks, designing and synthesizing not only the molecular clusters but also the means by which they interact. In this presentation, I will show how the atomic control and the diversity afforded by our superatoms allows us to dictate the structure of the solids and control the interactions between the building blocks. I will discuss how collective properties emerge from these interactions by providing examples of magnetic phase transition, electrical transport and thermal energy transport.

  14. Chemistry Department Seminar

    "Singlet O2 Oxidation of Guanine Nucleobase, Nucleoside and Guanine-Cytosine Base Pair: Ion-Beam Scattering Experiment Combined with Molecular Potential, Kinetic and Dynamics Simulations"

    Presented by Jianbo Liu, Dept. of Chemistry & Biochemistry, Queens College of the City University of NY

    Monday, June 6, 2016, 11 am
    Room 300, 3rd floor, Chemistry Building 555

    Hosted by: ''Trevor Sears''

    Research focuses on using various instrumental analysis approaches (e.g., mass spectrometry, spectroscopy, and ion-molecule reactions) to probe biologically relevant processes in a spectrum of systems ranging from isolated biomolecules, through micelles and aerosols containing biomolecules, to biomolecule solution.

  15. Chemistry Department Colloquium

    "TBA"

    Presented by Francisco Zaera, University of California, Riverside

    Monday, May 9, 2016, 10 am
    Hamilton Seminar Room, Bldg. 555

    TBA

  16. Chemistry Department Colloquium

    "The Route to Better Catalysts; From Surface Science to Nanotechnology"

    Presented by Prof. Francisco Zaera, Dept. of Chemistry, University of California, Riverside

    Monday, May 9, 2016, 10 am
    Hamilton Seminar Room, Bldg. 555

    Hosted by: 'Sanjaya Senanayake'

    One of the major challenges in heterogeneous catalysis is the preparation of highly selective and robust catalysts. The goal is to be able to synthesize solids with stable surfaces containing a large number of specific surface sites designed for the promotion of a particular reaction. New synergies between surface-science studies and novel nanosynthesis methodology promise to afford new ways to design such highly selective catalysts in a controlled way. Here we will provide a progress report on several projects ongoing in our laboratory based on this approach. First, we will offer a general discussion on the unresolved issues associated with olefin- conversion reactions promoted by metal surfaces. In a specific project, platinum-based catalysts were designed for the selective trans-to-cis conversion of olefins based on early surface-science work with model single-crystal surfaces and quantum mechanical calculations that indicated a particular preference for (111) facets in promoting the formation of the cis isomers. A metal- nanoparticle encapsulation procedure was also developed to increase catalyst stability and to prevent sintering. In a second example, new metal@TiO2 yolk-shell nanomaterials were conceived for both regular and photo-induced catalytic applications. These catalysts can promote CO oxidation at cryogenic temperatures, and suggest that in photocatalysis the role of the metal may not be to scavenge the excited electrons produced in the semiconductor upon absorption of light, as commonly believed, but rather to promote the recombination of the adsorbed atomic hydrogen initially produced by reduction of H+ on the surface of that semiconductor. Additional examples will be briefly introduced, including the use of "click" chemistry to tether molecular functionality on porous solid materials and the use of self-assembly and sol-gel chemistry to prepare catalysts with well-defined structural characteristics.

  17. Center for Functional Nanomaterials Seminar

    "Superoxide Solvation-Mediated Electrochemistry in Metal-Oxygen Batteries"

    Presented by Naga Phani B. Aetukuri, IBM Research-Almaden, San Jose, CA.

    Thursday, April 28, 2016, 11 am
    Building 735, Conf. Rm. A.

    Hosted by: 'Gregory Doerk'

    Center for Functional Nanomaterials Seminar Batteries with high specific energy and energy density higher than that of state-of-the-art Li-ion batteries are considered critical for mass adoption of electric automobiles. Metal-oxygen batteries, Li- and Na-O2 batteries in particular, offer the highest theoretical specific energy among all known battery types. Li2O2 and NaO2, the discharge products in Li- and Na-O2 batteries respectively, are both electronic insulators. Therefore, electrochemical deposition of Li2O2 and NaO2 might lead to battery electrode passivation and to low actual specific energy. I will present experimental results backed by theoretical calculations that suggest the capacity limitations in these batteries can be overcome by enabling solution-mediated electrochemical deposition of Li2O2 and NaO2. This mechanism leads to a higher specific energy than that limited by electrode passivation. We have identified design rules for selecting electrolyte solvents that favor this alternate pathway and enable high specific energy metal-air batteries. I will also discuss our work on dendrite-resistant composite Li-ion conducting membranes which find applications in Li-ion and other lithium battery chemistries that would benefit from using a lithium anode.

  18. Chemistry Department Colloquium

    "Structure of Room-Temperature Ionic-Liquids as it Relates to Anomalous Transport"

    Presented by Claudio J. Margulis, University of Iowa

    Monday, April 25, 2016, 10 am
    Hamilton Seminar Room, Bldg. 555

    Ionic Liquids are defined by phenomena on different length scales. During this talk I will describe our most recent efforts to correlate their heterogeneous nanoscale structure as derived from X-ray scattering experiments with anomalous solute dynamics. Our work has contributed to the development of guidelines to interpret scattering results, however the connection, if any, between structure and dynamics is still unclear. Inroads to this extent will be discussed in the context of translational and rotational diffusion of smaller solutes.

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