2017 Symposium on Functional Nanomaterials: Emerging Nanomaterials and Nanotechnology: Materials Design
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

Tuesday 8:30 AM
February 28, 2017
Room: Pacific 26
Location: Marriott Marquis Hotel

Session Chair: Vinu Unnikrishnan, University of Alabama; KyeongJae Cho, University of Texas at Dallas

8:30 AM  
Tribological Properties of Carbyne on Nickel Surface: Scott Muller1; Arun Nair1; 1University of Arkansas
    Carbyne is a one-dimensional material, and is among the strongest known carbon allotropes. Recent research has shown that the synthesis of long carbyne chains is viable, and it has opened the door for the study of nanocomposites that can utilize this mechanically superior material. In this research, a multiscale approach is used to study the tribological behavior of carbyne on a nickel surface. We use density functional theory (DFT) to study the fundamental interaction between Ni (111) surface and carbyne. Based on DFT studies, molecular dynamics simulations are preformed to predict the tribological properties of carbyne as a function of the chain length. The commensurability of one or more carbyne chains on a Ni (111) surface will also be discussed. This research will indicate the bonding behavior of carbyne with Ni, and the importance of chain length, which will be useful for future Ni-carbyne nanocomposite design.

8:50 AM  
A Screening of Transition Metal Nitrides with Dopants as Electrocatalysts for Oxygen Reduction Reaction: Doosun Hong1; Soonho Kwon1; Hyuck Mo Lee1; 1KAIST
    Recently, many research groups have studied transition metal nitrides (TMNs) as new candidates of alternatives to Pt-based catalyst in oxygen reduction reaction (ORR) because they are highly electrical conductive and have corrosion resistance under harsh condition. Also, they have similar electronic structure to noble metals. In this study, we performed high-throughput screening of TMNs and doped ones to determine their suitability as electrocatalysts for ORR. We calculated the adsorption energies of the intermediates of ORR using the density functional theory. Using these data, we obtained the free energy diagram and the rate-determining step of each material. Through these results, we calculated overpotential and we investigated the performance of electrocatalyst candidates for ORR.

9:10 AM  
Atomic and Electronic Structures of Stabilized Metal Monolayer: Kyeongjae Cho1; 1University of Texas at Dallas
    Electrons confined in a small structure in vacuum are strongly correlated through Coulomb interaction weakly screened via vacuum. In a spatially isolated condensed matter system (e.g., free nanoparticles, nanowires, and atomically thin 2D materials), the quasi-particle renormalization of electrons is known to be large. Recently research on 2D materials has been focused van der Waals materials such as graphene, and TMDs. An alternative approach to 2D material is based on well-controlled atomic metal layer deposition on oxide substrate, followed by an additional stabilizing oxide layer. The substrate oxide interacts strongly with metal atomic layer facilitating uniform atomic layer formation as well as modifying the atomic and electronic structures of the metal layer. The DFT modeling study has been performed to examine the stability, atomic structures and the corresponding electronic structures of the oxide-stabilized metal layers. This work was supported by Creative Materials Discovery Program (2015M3D1A1068062) through the NRF of Korea.

9:30 AM  Invited
Theory and Applications for Two-dimensional Phase Change Materials: Yao Li1; Karel-Alexander Duerloo1; Yao Zhou1; Evan Reed1; 1Stanford University
    Single-layers of some transition metal dichalcogenide compounds have the potential to exist in more than one crystal structure. I will discuss our theoretical work combined with DFT-based calculations to identify several single layer materials and their alloys including MoxW1-xTe2 that have potential to exhibit structural phase changes under stress and strain states, temperature changes, and electrostatic gating conditions. Our calculations indicate that phase boundaries of MoxW1-xTe2 can be tuned from hundreds of degrees C to room temperature and below by adjusting the composition. The use of electrostatic gating to induce a phase structural phase change is a new mechanism that may have advantages over typically employed thermal mechanisms. I will discuss the conditions under which mixed phases are expected to be thermodynamically stable. Some monolayer phase changes exhibit large electronic contrast, bringing an exciting new application space to monolayer materials ranging from information storage to electronic and optical devices.

10:00 AM Break

10:20 AM  Invited
New 2-D Material Recipes from Scratch: Susan Sinnott1; 1Penn State University
    Two-dimensional (2D) materials show promise as a scalable approach to shrink transistors and other nanoscale devices to meet rising technological needs. A combination of density functional theory (DFT) and thermodynamic calculations are used to map the thermodynamic stability and electronic properties of 2D materials as a function of their composition and structural ordering, and then extract design principles which can be experimentally tested on alloys of other compositions. 2D materials of interest are MXenes, a class of 2D transition metal carbides and nitrides, and chalcogenides.

10:50 AM  
Controlling Topological Phase Transition in Van Der Waals Stacked 2-D Materials for Topological Device Applications: Xiaofeng Qian1; 1Texas A&M University
    Materials with nontrivial electronic and photonic band topology are crucial for realizing novel devices with low power consumption and heat dissipation, and quantum computing free of decoherence. In this talk we will highlight our first-principles predictions on topological phase transition in three classes of 2D materials, including binary[1] and ternary[2] transition metal dichalcogenides and multilayer germanane[3]. The first two exhibit quantum spin Hall effect owing to nontrivial topology, while multilayer germanane is simply trivial. Remarkably, one can introduce topological phase transition by electrical gating, strain engineering, and van der Waals stacking, implying great potentials for topological devices. Excellent thermodynamic stability and weak interlayer binding make them promising for synthesis, exfoliation and vdW heterostacking. Finally, we will discuss some recent experimental progresses. Our findings may open up a variety of new opportunities for 2D materials and topological materials research. (References: [1] Science 346,1344-1347 (2014); [2] arXiv:1605.03903; and [3] APL 108,253107 (2016)).

11:10 AM  Invited
Cu-based Nanoparticles and Nanowires for Applications in Printed Electronics and Transparent Electrode: Changsoo Lee1; Na Rae Kim1; Jahyun Koo1; Cho Rong Chu1; Hyuck Mo Lee1; 1KAIST
    Cu-based nanoparticles and nanowires are promising conductive materials with low cost compared to Ag. The undesirable oxidation tendency of Cu-based nanomaterials is the main issue for conductive electrodes. Alloying and coating strategies with Ag were suggested to protect the Cu nanoparticles from oxdiation. The simple oleylamine-based synthesis followed by galvanic displacement was used to fabricate the Ag-Cu bimetallic nanoparticles with alloy and core-shell structures. The anti-oxidation properties were confirmed through density functional theory(DFT) and X-ray photoelectron spectroscopy(XPS). After the nanoparticles made into conductive inks, the electrical resistivities of the thin films coated with the inks were examined. Also, Cu nanowires were synthesized using both water-based and oleylamine-based synthesis. Ethylenediamine(EDA) and polymethyl methacrylate(PMMA) were used to protect Cu nanowires from oxidation. The effect of EDA concentration on surface oxidatoin was studied using DFT and XPS. Furthermore, we fabricatied Cu nanowire/PMMA composite transparent electrode showing excellent optoelectronic performance and oxidation stability.

11:40 AM  Invited
Correlation between Morphology and Field Emission Behavior of Various CuO Nanostructures: Gurjinder Kaur1; Krishna Saini1; Narasimha Pulagara1; Indranil Lahiri1; 1Indian Institute of Technology Roorkee
    CuO nanostructures have received ample attention because of their excellent electrical, optical and catalytic properties. A variety of CuO nanostructures have been synthesized on copper foils through a very simple wet chemical method. pH of the solution, reaction time and temperature were selected as the process parameters. Evolution of morphologies of the phases formed was characterized by X-ray diffraction and scanning electron microscopy, leading to elucidation of the growth mechanism. Different types of CuO nanostructures such as nanorods, nanotubes, nanoflakes, nanospheres, nanoneedes were observed to be formed at different process parameters. Field emission characteristics of these various CuO nanostructures were also investigated. Huge difference in the emission current density showed that field emission properties of CuO nanostructures are strongly affected by their morphology.