Nanocomposites IV: Nanoscience for Renewable Energy: NanoScience Part II
Sponsored by: TMS Structural Materials Division, TMS: Composite Materials Committee
Program Organizers: Changsoo Kim, University of Wisconsin-Milwaukee; Simona Murph, Savannah River National Laboratories; Muralidharan Paramsothy, NanoWorld Innovations (NWI); Meisha Shofner, Georgia Institute of Technology

Monday 2:00 PM
February 27, 2017
Room: Pacific 25
Location: Marriott Marquis Hotel

Session Chair: Changsoo Kim, University of Wisconsin-Milwaukee; Meisha Shofner, Georgia Institute of Technology

2:00 PM  Invited
Combinatorial Fabrication of Composite Photocatalytic Nanostructures by Oblique Angle Co-Deposition: Steven Larson1; Weijie Huang1; Yiping Zhao1; 1University of Georgia
    A new and versatile combinatory nanofabrication technique called the oblique angle co-deposition is developed to generate a library of nanomaterials with different morphology and structure. Using the Cu-Fe2O3 system as an example, by carefully characterizing the vapor plumes of the source materials, a composition map can be generated to design the locations of different substrate holders. The resulting nanostructures at different locations show different thickness, morphology, crystallinity, and composition. In addition, maps of different structural parameters are established, which can be used to correlate their properties. By further oxidizing or reducing the composite nanostructures, the properties of the nanostructures such as band gap, photocatalytic performance, and magnetic properties can be easily linked to their composition and other structural parameters. Optimal materials for photocatalytic and magnetic applications are efficiently identified. It is expected that the oblique angle co-deposition and its variations could become a powerful combinatory nanofabrication technique for nanomaterial survey.

2:40 PM  
Introducing Dislocation Lines for Controlled Thermal Conductivity in Si-based Nanocomposites by Liquid-phase Sintering: Jun Xie1; Yuji Ohishi1; Satoshi Ichikawa1; Aikebaier Yusufu2; Hiroaki Muta1; Ken Kurosaki1; Shinsuke Yamanaka1; 1Osaka University; 2University of Fukui
    The performance of bulk thermoelectrics can be improved by effective scattering of phonons with a wide range frequency. Many studies have focused on grain boundary and point-defect scattering in Si-based thermoelectric materials, which target low- and high-frequency phonons, while phonons with mid-frequency remain largely unaffected. In this study, high density of intragranular dislocations were formed in (Si0.97P0.03)95Co5 nanocomposites synthesized by melt-spinning technique and liquid-phase sintering. These dislocations may effectively scatter mid-frequency phonons, leading to a 50% reduction of κlat compared with a normally sintered sample without high density of dislocations. Stronger phonon scattering with minimal carrier scattering achieved a peak ZT of 0.39 at 1070 K without alloying any expensive and rare Ge. The morphology and formation mechanism of dislocations were investigated by utilizing X-ray diffraction, scanning electron microscopy and transmission electron microscopy observations. The influences on the thermoelectric properties of the dislocation lines will be discussed in detail.

3:00 PM  
Fabrication of Silicon/Graphite Nanocomposite as Promising Anode Material for Lithium-ion Battery Applications: Maziar Ashuri1; Qianran He1; Leon Shaw1; 1Illinois Institute of Technology (IIT)
    Silicon with more than 4000 mA h g-1 theoretical capacity is one of the most promising candidates among other anode materials for Li-ion batteries. However, it suffer from huge volume change during charge/discharge process. Several strategies have been proposed to overcome this issue such as core-shell and yolk-shell nanostructures, Si nanotubes, etc. However, most of them requires expensive equipment, long time synthesis, and special set up. In this study, we try to look at the old silicon/graphite composite with the new approach of etching. To fabricate the composite, silicon and graphite were ball-milled together. Then, the obtained nanocomposite was coated with a thin carbon shell. The last step was etching the carbon-coated nanocomposite. The etchant used was 0.5 M sodium hydroxide solution. The product was washed with deionized waster and applied as active material for half cells. The electrochemical results showed improved performance comparing to crystalline silicon.

3:20 PM Break

3:40 PM  Invited
Photonic Curing for Advanced Thin Film and Device Development: Pooran Joshi1; Teja Kuruganti1; Tolga Aytug1; 1Oak Ridge National Laboratory
    Thermal processing is an integral part of material and device development. Low thermal budget processing of materials is critical to exploit their unique properties for highly functional device development on unconventional substrates such as paper and plastic. Extensive R&D efforts are focused on the low-temperature development of a wide range of discrete and integrated devices for electronic applications, such as thin film transistors, energy harvesting and storage devices, organic electronics, RFIDs, interconnects, and sensors The present talk highlights the role of temperature in defining the device technology and R&D challenges. The impact of the roll-to-roll compatible photonic pulse thermal processing technique in the development of cost-effective, high yield, and high quality integrated thin films and devices with optimum performance/cost tradeoff on low-temperature substrates is discussed. Advances in the thin film processing, direct-write printing techniques, and low-thermal budget curing technology offer new opportunities for flexible electronics combined with the Internet of Things (IoT). Specific examples from our research work on multifunctional sensor platform development, and diverse nanomaterials and thin film integration are included in the presentation.

4:20 PM  
Surface-Functionalized Nanoporous Carbons for Kinetically Stabilized Complex Hydrides through Lewis acid-Lewis base Chemistry: Christopher Carr1; Eric Majzoub1; 1University of Missouri St. Louis
    Complex metal hydrides are an attractive hydrogen storage option due to their high gravimetric capacities, but the re/de-hydriding reactions generally possess unfavorable thermodynamics and kinetics. Recent studies have attempted to alter these properties through confinement of complex hydrides in nanoporous substrates (e.g. LiBH4 melt-infiltrated into a nanoporous carbon). We present results of the surface functionality displayed by incorporation of electron-donating nitrogen into a nanoporous carbon. Pyridinic nitrogen in the substrate, confirmed by XPS, acts as a Lewis base. Our results indicate partial decomposition on melt-infiltration of LiBH4 may produce electron-accepting BH3 defects at the surface of the hydride forming a stabilizing capping layer. Although LiBH4 is already too stable for on-board hydrogen storage applications, it provides a well-characterized system for application of our concept. This ‘kinetic stabilization’ may provide a useful approach to using a wide class of complex hydrides with enthalpies below 15 kJ/mol H2.

4:40 PM  
Polypyrrole Coated Silver Nanowire Supercapacitors: Recep Yuksel1; Husnu Unalan1; 1Middle East Technical University
    We report on supercapacitors with a core shell architecture using silver nanowires and polypyrrole. Highly conductive silver nanowires were utilized as templates for the polypyrrole deposition and in-situ chemical polymerization of polypyrrole resulted in the formation of coaxial nanocomposites. A specific capacitance of 91 F/g and 92 % capacity retention upon 10000 cycles was obtained for silver nanowire/polypyrrole nanocomposite supercapacitor devices, which was higher than that of bulk polypyrrole control devices. The effects of polypyrrole thickness on the electrochemical properties of silver nanowire/polypyrrole nanocomposites were systematically investigated. We will present a detailed analysis on the charge transfer properties of the fabricated supercapacitors to underline their capacitive behavior. Our obtained results show the potential of the use of silver nanowire/polypyrrole nanocomposites in energy storage devices and the structure presented in this work is highly plausible and can be easily extended to other metal nanowire-conducting polymer systems.