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July 2015
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  1. Center for Functional Nanomaterials Seminar

    11 am, CFN, Building 735, conference room A, 1st fl.

    Hosted by: Qin Wu

    Center for Functional Nanomaterials Seminar Cu-CHA in Emission Control Dr. Xiaofan Yang BASF Corporation Friday, July 10, 2015 11:00 a.m. Building, 735, Conference Room A Chabazite supported Cu is the most promising catalyst platform for implementing a NH3/urea-based Selective Catalytic Reduction (SCR) system to remove hazardous NOx gases from the lean-burn engine exhaust. Whereas in-depth spectroscopic and other studies have attempted to identify key features of the catalytic cycle previously, a deep understanding of the SCR mechanism amenable for a systematic improvement of the catalyst performance continues to be elusive. To establish a more rational approach to catalyst optimization and identify chemically sound design principles based on the thermodynamics and kinetics of the key steps of the underlying NOx-transformations we developed a quantum chemical model and benchmarked it to match vibrational data from Diffuse Reflectance Infrared Fourier Transform spectroscopy resulting in plausible assignments of each observable intermediate to specific oxidation states of Cu and NO-binding properties. This approach allows for making a much more precise assignment of the experimental vibrational data to key intermediates potentially involved in the catalytic cycle of the SCR reaction and provides a high-resolution model that can be examined to develop a micromechanistic proposal for the catalytic reaction cycle that is chemically meaningful and is logically consistent. In addition, the presentation also covers industrial application utilizing Cu-CHA in emission control. Host: Qin Wu

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  1. CFN Summer Sunday

    10 am, Berkner Hall Auditorium

    Hosted by: CFN

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  1. Center for Functional Nanomaterials Seminar

    11 am, CFN, Building 735, 1st floor conference room A

    Hosted by: Deyu Lu

    Center for Functional Nanomaterials Seminar Configurational Sampling for Problems in Energy Storage, Photovoltaics, and Force Field Fitting Maria Chan Center for Nanoscale Materials, Argonne National Laboratory, Argonne IL USA Wednesday, July 22, 2015 11:00 a.m. Bldg. 735, Conf. Rm. A, first floor Abstract Atomistic modeling, whether in conjunction with classical or quantum mechanical Hamiltonians, depends heavily on the determination of actual or probable atomistic structures. A large variety of approaches towards such determination have been developed for global minimum structures as well as equilibrium thermal fluctuations, including Monte Carlo, basin hopping, simulated annealing, molecular dynamics etc. In this talk, we will discuss the determination of atomistic structures outside of thermodynamic ground state or typical thermal situations, including the modeling of nonequilibrium solid-state amorphization and experiment-guided atomistic structure determination. We will also discuss the importance of appropriate configurational sampling for force field development. Biography Maria Chan obtained her BSc in Physics and Applied Mathematics from UCLA and PhD in Physics in MIT. Dr. Chan has been a staff scientist at the Center of Nanoscale Materials, Argonne National Laboratory, since 2012. Dr. Chan's research focuses on the computational prediction of materials properties, using first principles, atomistic, and data mining methods, particularly in applications towards materials relevant to energy technologies, such as photovoltaics, energy storage, and thermoelectrics. Examples include development of methods for high-throughput screening of photovoltaic and photocatalytic materials, prediction of thermal conductivity in nanostructured thermoelectric materials, modeling of point and extended defects in inorganic photovoltaics, and modeling o

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  1. AUG

    11

    Tuesday

    Center for Functional Nanomaterials Seminar

    "Photoresponses in Vanadium Dioxide Nanowires"

    Presented by Prof. Hanwei Gao, Department of Physics, Florida State University

    2 pm, CFN, Bldg. 735, Conference Rm. A - 1st fl.

    Tuesday, August 11, 2015, 2:00 pm

    Hosted by: Mingzhao Liu

    Center for Functional Nanomaterials Seminar Photoresponses in Vanadium Dioxide Nanowires Prof. Hanwei Gao Department of Physics, Florida State University Tuesday, August 11, 2015 2:00 p.m. Bldg. 735 " Conf. Rm. A, 1st floor Abstract: Vanadium dioxide (VO2) has drawn much attention for its unique metal-insulator transition near the room temperature. The high electrical resistivity below the transition temperature (about 64 °C) is a result of the strong electron-electron correlation. Such interactions can potentially lead to remarkable charge carrier multiplication under optical excitation, a process desirable for efficient optoelectronics and photovoltaics. However, because the resistivity is highly temperature-dependent, the observed light-induced conductivity in VO2 was often attributed to photothermal effects. By varying the chopping frequency of the optical illumination, we have distinguished the photothermal and photoconductive effects in VO2 nanowires. The frequency dependent measurements indicated that the relatively slow photothermal processes can be well suppressed with high chopping frequency, whereas the fast photo-excitation of charge carrier results in a frequency-independent photoconductivity in VO2. Resolving these coexisting processes paves the way for further studies of carrier dynamics under optical excitations in strong electron correlated materials. . Host: Mingzhao Liu Joann Tesoriero Center for Functional Nanomaterials P.O. Box 5000 Upton, NY 11973 Tel. (631) 344-7791 Tax: (631) 344-3093 Tesoriero@bnl.gov

  2. AUG

    21

    Friday

    Center for Functional Nanomaterials Seminar

    "Caught in the Act! Live Observations of Catalysts Using High-pressure Scanning Probe Microscopy"

    Presented by Irene M. N. Groot, Leiden Institute of Physics and Leiden Institute of Chemistry, the Netherlands

    10 am, CFN, Bldg. 735, first fl. conference room A

    Friday, August 21, 2015, 10:00 am

    Hosted by: Anibal Boscoboinik

    Center for Functional Nanomaterials Seminar Caught in the Act! Live Observations of Catalysts Using High-pressure Scanning Probe Microscopy Irene M. N. Groot Leiden Institute of Physics and Leiden Institute of Chemistry, the Netherlands Friday, August 21, 2015 10:00 am Bldg. 735 " Conf. Rm. A Recently it has become clear that essential differences can exist between the behavior of catalysts under industrial conditions (high pressure and temperature) and the (ultra) high vacuum conditions of traditional laboratory experiments. Differences in structure, composition, reaction mechanism, activity, and selectivity have been observed. These observations indicated the presence of the so-called pressure gap, and made it clear that meaningful results can only be obtained at high pressures and temperatures. However, most of the techniques traditionally used to study catalysts and their reactions were designed to operate under (ultra) high vacuum conditions. To bridge the pressure gap, the last years have seen a tremendous effort in designing new instruments and adapting existing ones to be able to investigate catalysts in situ under industrially relevant conditions. This talk focuses on the development of scanning probe microscopy for operando observations of active model catalysts. In our group, we have developed set-ups that combine an ultrahigh vacuum environment for model catalyst preparation and characterization with a high-pressure flow reactor cell, integrated with either a scanning tunneling microscope or an atomic force microscope. With these set-ups we are able to perform atomic-scale investigations of well-defined model catalysts under industrial conditions. Additionally, we combine the structural information from scanning probe microscopy with time-resolved mass spectrometry measurements on the gas mixture that leaves the re

  3. SEP

    30

    Wednesday

    CFN Proposal Deadline

    "CFN Proposal Deadline for January-April Cycle 2016"

    11:45 pm, CFN

    Wednesday, September 30, 2015, 11:45 pm