BNL Home
March 2017
Sunday Monday Tuesday Wednesday Thursday Friday Saturday

1

  1. No events scheduled

2

  1. No events scheduled

3

  1. No events scheduled

4

  1. No events scheduled

5

  1. No events scheduled

6

  1. No events scheduled

7

  1. No events scheduled

8

  1. No events scheduled

9

  1. No events scheduled

10

  1. No events scheduled

11

  1. No events scheduled

12

  1. No events scheduled

13

  1. No events scheduled

14

  1. No events scheduled

15

  1. No events scheduled

16

  1. CFN Colloquium

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

    Hosted by: 'Oleg Gang'

    Block copolymer self-assembly allows the rapid formation of nanostructures over wide areas. Yet, the range of possible patterns is fairly limited. I will present emerging strategies for constructing three-dimensional nanostructures whose shapes and symmetries go beyond those of the bulk equilibrium diblock copolymer phase diagram. Photo-thermal methods are used to accelerate assembly, and control block copolymer ordering and orientation. Self-assembly is known to be pathway-dependent, which can be exploited to select a particular nano-pattern. Ordered layers can be stacked to yield new lattice symmetries. This multi-layered ordering can be performed in a responsive mode, where each self-assembled layer templates the ones that follow. Taken together, these new motifs point towards the ability to construct designed, multi-functional 3D nanostructures.

17

  1. No events scheduled

18

  1. No events scheduled

19

  1. No events scheduled

20

  1. No events scheduled

21

  1. No events scheduled

22

  1. No events scheduled

23

  1. Center for Functional Nanomaterials Seminar

    11 am, CFN, Bldg 735, Conference Room A, 1st Floor

    Hosted by: ''Mircea Cotlet''

    Semiconductor quantum dots (QDs) have been used extensively for applications in cellular imaging, biosensing, photovoltaics, and solid-state lighting. Despite successes with traditional cadmium selenide QDs, limitations persist because of the fluorescence intermittency (or blinking) of the QD emission, concerns about toxicity, and cross-talk due to broad, overlapping absorption spectra. Thick-shelled QDs, also known as 'giant' nanocrystal quantum dots (g-NQDs) exhibit emission and absorption spectra that can be tailored based on semiconductor composition, core size, and shell thickness. Through these advanced chemistries, we customize the QDs to applications including QD-QD fluorescence resonance energy transfer (FRET)-based biosensors and cadmium-free NIR emitters for multiplexed tissue-depth imaging.

24

  1. Center for Functional Nanomaterials Seminar

    9:30 am, CFN, Bldg 735, Conference Room A, 1st Floor

    Hosted by: ''Mark S. Hybertsen''

    TiO2 is an important technological material with widespread applications in photocatalysis, photovoltaics, and self-cleaning surfaces. Behavior of the photoexcited electrons, particularly near its surfaces, as well as the surface structure of the material itself are two crucial constituents of its scientifically interesting properties. In this work, we focus on the excess and photoexcited electrons in anatase, the TiO2 polymorph most relevant to photocatalysis and solar energy conversion. Our results provide a bridge between the surface science experiments under vacuum conditions and the observations of crystal-face-dependent photocatalysis on anatase and support the idea that optimization of the ratio between different anatase facets can help enhance the photocatalytic activity of this material. Furthermore, we use a combined first principles and classical approach to study the reduction of anatase under H2 atmosphere. Experiments done in a similar setup yields a black TiO2 powder which shows a superior photocatalytic efficiency. This material is characterized to have an amorphous TiO2-x shell covering the anatase core. However, a detailed structural understanding of the material and the origins of its superior activity remains a mystery to date. We identify the main pathways of TiO2 reduction by H2 and explore the initial stages of surface amorphization in a spherical nanoparticle.

  2. Center for Functional Nanomaterials Seminar

    11 am, Bldg 735, Conference Room A

    Hosted by: 'Dong Su'

    Dynamic materials processes (phase transformations, interfacial reactions, mechanical degradation, etc.) play major roles in determining the lifetime and performance of next-generation electrochemical energy storage systems. To develop batteries with improved safety, energy density, and lifetime, it is critical to understand transformation mechanisms and degradation processes within these devices. In my group, multiscale in situ techniques are used to reveal reaction mechanisms and interfacial transformations in energy storage materials to guide the development of better batteries. Our recent work has used a combination of in situ transmission electron microscopy (TEM) and in situ x-ray diffraction (XRD) to elucidate transformation pathways when high capacity electrode materials react with lithium vs. sodium for Li-ion and Na-ion batteries. Cu2S-based electrodes, for instance, show similar global transformations during reactions with lithium and sodium, but the nanoscale reaction pathways differ significantly, which influences the electrochemical performance. Other work to be presented is focused on using X-ray spectroscopy and imaging methods to understand reaction mechanisms at nanoscale interfaces, as well as strain evolution within individual nano-to-micro particles. Together, these results demonstrate the importance of developing in situ techniques to understand atomic-to-macroscale dynamic processes in energy materials.

25

  1. No events scheduled

26

  1. No events scheduled

27

  1. No events scheduled

28

  1. No events scheduled

29

  1. No events scheduled

30

  1. No events scheduled

31

  1. No events scheduled

  1. APR

    6

    Thursday

    CFN Colloquium

    "Catalysis at Shell - Challenges & Opportunities for Energy"

    Presented by Carl Mesters, Shell, Shell Technology Center in Houston

    3 pm, Bldg 735, Seminar Room, 2nd Floor

    Thursday, April 6, 2017, 3:00 pm

    Hosted by: '''''Dario Stacchiola'''''

    Energy is vital to our daily lives. It helps us produce food, fuel transport and power communication channels across the world. Over the coming decades, more people will gain access to energy and enjoy higher standards of living. But these developments could place greater pressure on our world's resources, such as energy, fresh water and food. At the same time, climate change remains a serious concern. At Shell, we use human ingenuity, innovation and technology to unlock the energy our customers need to power their lives in the years ahead, while aiming to limit our impact on the environment. In this seminar we will discuss examples in the area of catalysis that are relevant to meet these challenges in energy. C.V: Carl Mesters joined Shell in 1984 and currently works from the Shell Technology Center in Houston. He has been active in catalysis and process R&D across many areas, including selective catalytic reduction of NOx, ethylene oxide, gas-to-liquids, catalytic dewaxing, aromatic hydrogenation, xylene isomerization, etc. resulting in more than 70 patents filed. In 2005 he was appointed Shell's Chief Scientist for Chemistry & Catalysis. Today's main topics are in 'Gas to Chemicals' and 'long range R&D'. Carl has been Chairman of the Catalysis Society of the Royal Dutch Chemical Society. He holds a degree in Physical and Inorganic Chemistry from the University of Utrecht, the Netherlands, where he also completed a research Ph.D.

  2. APR

    27

    Thursday

    CFN Colloquium

    "Darkening Pt Nanocrystals for Photocatalysis"

    Presented by Yugang Sun, Department of Chemistry, Temple University

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

    Thursday, April 27, 2017, 4:00 pm

    Hosted by: '''''Fang Lu'''''

    Platinum (Pt) nanocrystals are commonly used in chemical reactions because of their unusual catalytic activity, for example, photocatalytic water splitting of water. In a typical design, Pt nanocrystals can accept photo-excited electrons from light absorbers such as semiconductor quantum dots (QDs) to catalyze hydrogen evolution reaction (HER) [1]. Charge transfer from QDs to Pt nanocrystals is very inefficient, and shuttle molecules (e.g., methyl viologen) or other shuttle species are necessary to facilitate the charge transfer [2]. In addition to receiving energetic electrons from semiconductor QDs, Pt nanocrystal can also absorb visible light to generate energetic electrons (or hot electrons), which can directly reduce reactive species or migrate across a metal/semiconductor Schottky barrier to the conduction band of a semiconductor. Different from the widely studied plasmonic metal nanocrystals (e.g., Au, Ag), the efficiency of generating hot electrons in the weakly absorbing Pt nanocrystals is very low. We found that depositing Pt nanocrystals on spherical glass beads (i.e., SiO2 particles) could significantly enhance the visible absorption coefficient of the Pt nanocrystals. For example, in SiO2@Pt nanocrystals@TiO2 core-shell nanostructures, the enhancement in visible absorption enables the efficient generation of energetic electrons in photoexcited Pt nanocrystals, which can easily transfer to the TiO2 surface layer to drive HER and many other chemical reactions [3].

  3. MAY

    11

    Thursday

    CFN Colloquium

    "TBD"

    Presented by TBD

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

    Thursday, May 11, 2017, 4:00 pm

    Hosted by: ''TBD''

  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.

  5. JUL

    6

    Thursday

    CFN Colloquium

    "TBD"

    Presented by TBD

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

    Thursday, July 6, 2017, 4:00 pm

    Hosted by: 'TBD'