2017 Symposium on Functional Nanomaterials: Emerging Nanomaterials and Nanotechnology: Nanomaterials for ET Applications
Sponsored by: TMS Functional Materials Division, TMS: Nanomaterials Committee
Program Organizers: Jiyoung Kim, University of Texas; Stephen McDonnell, University of Virginia; Chang-Yong Nam, Brookhaven National Laboratory; V. U. Unnikrishnan, The University of Alabama; Nitin Chopra, The University of Alabama

Wednesday 8:30 AM
March 1, 2017
Room: Pacific 26
Location: Marriott Marquis Hotel

Session Chair: Jung-Kun Lee, Univ. of Pittsburgh; Seungbum Hong, Argonne National Lab

8:30 AM  
Synthesis and Characterization of Ag/CFO@PANI Core-shell Nanocomposite for Photocatalytic Application: Venkata Sai Sriram Mosali1; Mohd Qasim1; Bhanu Mullamuri2; Basavaiah Chandu3; Dibakar Das1; 1University of Hyderabad; 2Acharya Nagarjuna University ; 3Acharya Nagarjuna University
    Photocatalytic dye degradation has been widely studied in recent years because of increasing global pollution resulting from toxic colouring dyes. In this work we report on the synthesis of a novel recyclable core-shell nanocomposite consisting of CoFeČ2O4 (CFO) as magnetic core and polyaniline (PANI) as shell with silver nanoparticles embedded in it for photocatalytic dye degradation application. Co-precipitation method has been employed for the synthesis of CFO followed by oxidative polymerization of aniline monomer. Freshly prepared Ag nanoparticles have been added during polymerization. Core-shell nanoparticles of 10-15 nm size were obtained which was confirmed by XRD and TEM analysis. EDAX confirms the respective elemental compositions of CFO, PANI, and Ag. The photocatalytic efficiency of the obtained nanocomposite has been tested on methylene blue dye under sun light. The composite shows an efficiency of ~ 90% which shows promise to be a good catalyst for photocatalytic dye degradation.

8:50 AM  
Anodic Synthesis, Functionalization, and Applications of Metal Oxide Nanotube Arrays: York Smith1; 1University of Utah
    Electrochemical anodization is a robust and scalable method to obtain highly ordered 1D metal oxide nanotubular structures from metal or alloy films with high morphological control. Criteria for obtaining highly ordered nanoporous films using electrochemical anodization techniques will be discussed, along with methods of synthesis, functionalization, and device integration. Focusing namely on titania and iron oxide anodic nanotubes, we will review some of the energy conversion and storage (photo/electro-catalytic and supercapacitor) and sensing (health and environmental diagnostics) applications demonstrated by these materials. Current and future challenges associated with the development and large-scale synthesis of these materials will be discussed.

9:10 AM  
Diffusion Kinetics of Gold in TiO2 Nanotube Arrays for Formation of Au@TiO2 Nanotube Arrays: Wanggang Zhang1; Wei Liang1; Fuqian Yang2; 1Taiyuan University of Technology; 2University of Kentucky
    A simple approach is developed to form Au@TiO2 nanotube arrays. This approach consists of the formation of pure TiO2 nanotube arrays by a two-step anodization process, the coating of Au nanofilm on the top of the pure TiO2 nanotube arrays, and the heat treatment of the TiO2 nanotube arrays with the coating of Au nanofilm. The heat treatment leads to the diffusion of Au atoms into the TiO2 nanotube arrays, resulting in the formation of Au nanocrystals on the outer surface of TiO2 nanotubes. The diffusivity for the diffusion of Au atoms on the outer surface of the TiO2 nanotubes is in the range of 4.14-19.410-18 m2/s for the temperature in the range of 400-500 ║C. The activation energy for the migration/diffusion of Au on the outer surface of the TiO2 nanotubes in the temperature range of 400 to 500 ║C is 67.2 kJ/mol.

9:30 AM  
Graphene Oxide Added Encapsulation Coating for Highly Stable Perovskite Solar Cells: Gill Sang Han1; Jin Sun Yoo2; Fangda Yu1; Matthew Lawrence Duff1; Hyun Suk Jung2; Jung-Kun Lee1; 1University of Pittsburgh; 2Sungkyunkwan University
    Organic-inorganic hybrid perovskite semiconductor is a promising light absorber for high efficiency solar cells. Despite these advantages, commercialization of PSCs is still challenging, due to the poor long-term stability of the halide perovskite materials. Herein, we present a simple fabrication method of highly efficient PSCs exhibiting the outstanding stability under humid environment and/or high temperature. This presentation shows that a graphene oxide (rGO) added encapsulation layer significantly improves the water resistance and thermal conductivity of PSCs. Implementation of the rGO added passivation layer suppresses the penetration of H2O, O2 and other gas molecules. Furthermore, high thermal conductivity of rGO promotes heat dissipation during high temperature operation and reduces thermal aging of PSCs. When the rGO added encapsulation layer is coated, the aging of PSCs is significantly prevented at extremely humid environment (100%) or high temperature (85oC).

9:50 AM  
Embedded Chip-scale Electrochemical Double Layer Capacitors with Novel Functionalized Architecture and Tailored Ionic Liquid-based Electrolyte: Jud Ready1; Stephan Turano1; Tyler Colling1; Valerie Scott2; 1Georgia Institute of Technology; 2NASA-JPL
    Energy storage and delivery is a topic of high interest, especially in applications demanding high energy, low mass, and low volume energy storage devices. Supercapacitors have been drawing significant interest in fields such as space exploration, computer technology, and the automotive industry due to their high power densities and cyclability. This research focused on the development of ‘chip scale’ carbon nanotube-based electrochemical double layer (ECDL) supercapacitors that feature a novel graphenated and pseudocapacitively-functionalized architecture accompanied by a tailored room temperature ionic liquid (RTIL) electrolyte.

10:10 AM Break

10:30 AM  Invited
Visualization of Polarization and Screening Charges Using Charge Gradient Microscopy: Seungbum Hong1; Andreas Roelofs2; 1Argonne National Laboratory; KAIST; 2Argonne National Laboratory
    Recently, we showed that scraping, collecting and quantifying the screening charges reveals the underlying polarization domain structure at high speed, a technique we call Charge Gradient Microscopy. The scraped charge, measured as a current that scales with scraping rate, induces a charge gradient that leads to the immediate relocation or refill of the screen charges from the vicinity of the probe. Furthermore, we investigated the kinetics behind the mechanical removal of externally bonded screening charges and the kinetics of rescreening in ambient conditions. We found that a minimum pressure needs to be applied to initiate mechanical removal of screening charges, and increasing the pressure leads to further removal of charges until a critical pressure is reached, when all screening charges are removed. In addition, the rescreening showed an exponential recovery, implying that the screening charge degree on ferroelectric surfaces can be controlled by mechanical means without affecting the polarization underneath.

11:00 AM  
Multilayer Graphene-coated Silicon Photoanodes: Keren Freedy1; Yin Xu1; Giovanni Zangari1; Stephen McDonnell1; 1University of Virginia
    The performance of silicon anodes for photoelectrochemical cells is hindered by the oxidation of the silicon surface during the oxygen evolution reaction. Thin coatings of various metals and oxide materials have been proposed to function as protective oxidation barriers. Graphene has previously been reported to effectively stabilize Si(111) electrodes (Nielander et al, 10.1021/ja407462g). The ease of processing and the high carrier mobility and optical transmission of this 2D material make it an appealing option for this application. In this study, we investigate the performance and stability of Si photoanodes coated with different numbers of graphene layers. Preliminary photoelectrochemical measurements in an aqueous electrolyte of monolayer, bilayer, and trilayer graphene-coated n-Si(100) photoanodes suggest improved stability with increasing number of layers. Presented will be a comparative study of photoanode performance as a function of the number of graphene layers.

11:20 AM  
High-performance Supercapacitors Based on Hierarchical VOx Microspheres Forming from Hyperbranched Nanoribbons: Chuang Wei1; Hong-Yi Li1; Zhao Yang1; Bing Xie1; 1Chongqing University
    Novel VOx nanomaterials as high performance electrode materials of supercapacitors were successfully synthesized by solvothermal method using V2O5, H2O2, (NH4)2SO4 and EG (Ethylene Glycol). These as-prepared nanomaterials are hierarchical microspheres with diameter of ~5 μm, which formed from hyperbranched growth of nanoribbons. According to XRD and TEM, these hierarchical VOx microspheres consist of V6O13 with metallic conductivity and VO2. These materials exhibited a tremendous specific capacitance of 581 F/g, with corresponding volumetric specific capacitance of 3.94 F/cm3, at 0.6 A/g in the potential range of 0 to 1.2 V when used as supercapacitor electrodes in a solution of 1 M LiNO3. The energy density is as high as 29 Wh/kg, which is much higher than those of many other symmetrical supercapacitors. In addition, the capacity retention of 65% was achieved even after 2000 cycles, demonstrating high performance of vanadium oxide nanomaterials used in supercapacitors.

11:40 AM  
Highly Porous Interconnected Carbon Nanosheets Derived from Jute Fibres for Supercapacitors and Li-ion Batteries: Arghya Patra1; Srijan Sengupta1; Arijit Mitra1; Karabi Das1; Siddhartha Das1; 1Indian Institute of Technology, Kharagpur
    For the first time, multilayered lignocellulosic Jute (Corchorus olitorius) fibers were exploited as precursor to synthesize unique 2D partially graphitised (IG/ID = 0.79) carbon nanosheets (8-14 nm in thickness) having interconnected porosities (~80 nm pore diameter) and high BET surface area (up to 1600 m2/g) by hydrothermal carbonization (200oC) and chemical activation with KOH under Argon atmosphere (600, 800 and 1000oC). The electrochemical performances of the synthesised materials were tested by cyclic voltammetry, electrochemical impedance spectroscopy and galvanostatic charge-discharge tests. The material exhibits a remarkable specific capacitance of 294 Fg-1 in 6 M KOH aqueous electrolyte, at 25oC and voltage sweep rate of 50 mVs-1 with 95% capacitance retention after 1000 cycles. The same material depicts exceptional discharge capacity of 895 mAh/g (Li3C8 on lithiation) after 2nd cycle under Li half cell configuration and can also act as a promising high capacity anode for Li ion batteries.