Physical Sciences and Mathematics Commons^™

High Performance Pure Sulfur Honeycomb-Like Architectures Synthesized By A Cooperative Self-Assembly Strategy For Lithium Sulfur Batteries, Xin Liang, Mohammad Kaiser, Konstantin Konstantinov, Richard Tandiono, Zhaoxiang Prof Zhaoxiang Wang, Hua-Kun Liu, S X. Dou, Jiazhao Wang

Shi Xue Dou

Honeycomb-like pure sulfur architectures were synthesized by a cooperative self-assembly strategy, in which a soft template is used to form the porous structure. Their electrochemical performance is significantly improved comparing with the commercial sulfur powder and the as-prepared sulfur without honeycomb morphology. There has been no report on using a soft template to prepare honeycomb-like sulfur particles.

Thermoelectric Performance Of N-Type (Pbte)0.75(Pbs)0.15(Pbse)0.1 Composites, Sima Aminorroaya Yamini, Heng Wang, Dianta Ginting, David R. G Mitchell, S X. Dou, G. Jeffrey Snyder

Shi Xue Dou

Lead chalcogenides (PbQ, Q = Te, Se, S) have proved to possess high thermoelectric efficiency for both n-type and p-type compounds. Recent success in tuning of electronic band structure, including manipulating the band gap, multiple bands, or introducing resonant states, has led to a significant improvement in the thermoelectric performance of p-type lead chalcogenides compared to the n-type ones. Here, the n-type quaternary composites of (PbTe)0.75(PbS)0.15(PbSe)0.1 are studied to evaluate the effects of nanostructuring on lattice thermal conductivity, carrier mobility, and effective mass variation. The results are compared with the similar ternary systems of (PbTe)1-x(PbSe)x, (PbSe) 1-x(PbS)x, and (PbS)1-x(PbTe)x. The …

Thermoelectric Performance Of Tellurium-Reduced Quaternary P-Type Lead-Chalcogenide Composites, Sima Aminorroaya Yamini, Heng Wang, Zachary M. Gibbs, Yanzhong Pei, David R. G Mitchell, S X. Dou, G. Jeffrey Snyder

Shi Xue Dou

A long-standing technological challenge to the widespread application of thermoelectric generators is obtaining high-performance thermoelectric materials from abundant elements. Intensive study on PbTe alloys has resulted in a high figure of merit for the single-phase ternary PbTe-PbSe system through band structure engineering, and the low thermal conductivity achieved due to nanostructuring leads to high thermoelectric performance for ternary PbTe-PbS compounds. Recently, the single-phase p-type quaternary PbTe-PbSe-PbS alloys have been shown to provide thermoelectric performance superior to the binary and ternary lead chalcogenides. This occurs via tuning of the band structure and from an extraordinary low thermal conductivity resulting from high-contrast …

High-Performance Sodium-Ion Batteries And Sodium-Ion Pseudocapacitors Based On Mos2/Graphene Composites, Yunxiao Wang, Shulei Chou, David Wexler, Hua-Kun Liu, S X. Dou

Shi Xue Dou

Sodium-ion energy storage, including sodium-ion batteries (NIBs) and electrochemical capacitive storage (NICs), is considered as a promising alternative to lithium-ion energy storage. It is an intriguing prospect, especially for large-scale applications, owing to its low cost and abundance. MoS2 sodiation/desodiation with Na ions is based on the conversion reaction, which is not only able to deliver higher capacity than the intercalation reaction, but can also be applied in capacitive storage owing to its typically sloping charge/discharge curves. Here, NIBs and NICs based on a graphene composite (MoS2/G) were constructed. The enlarged d-spacing, a contribution of the graphene matrix, and the …

Ultra-High Performance, High-Temperature Superconducting Wires Via Cost-Effective, Scalable, Co-Evaporation Process, Ho-Sup Kim, Sang-Soo Oh, Hong-Soo Ha, Dojun Youm, Seung-Hyun Moon, Jung Ho Kim, S X. Dou, Yoon-Uk Heo, Sung-Hun Wee, Amit Goyal

Shi Xue Dou

Long-length, high-temperature superconducting (HTS) wires capable of carrying high critical current, Ic, are required for a wide range of applications. Here, we report extremely high performance HTS wires based on 5 μm thick SmBa2Cu3O7 − δ (SmBCO) single layer films on textured metallic templates. SmBCO layer wires over 20 meters long were deposited by a cost-effective, scalable co-evaporation process using a batch-type drum in a dual chamber. All deposition parameters influencing the composition, phase, and texture of the films were optimized via a unique combinatorial method that is broadly applicable for co-evaporation of other promising complex materials containing several cations. …

Aqueous Dispersions Of Reduced Graphene Oxide And Multi Wall Carbon Nanotubes For Enhanced Glucose Oxidase Bioelectrode Performance, Willo Grosse, Joffrey Champavert, Sanjeev Gambhir, Gordon G. Wallace, Simon E. Moulton

Gordon Wallace

Aqueous dispersions of reduced graphene oxide (rGO) and multi walled carbon nanotubes (MWCNT) were fabricated through a modified chemical reduction method. The significant advantage of the method developed here is the omission of any stabilising compound or organic solvent to obtain stable rGO-MWCNT dispersions. Significantly biological entities, in this case the enzyme glucose oxidase (GOx), can be successfully incorporated into the dispersion. These dispersions were characterised using XPS, SEM, zeta potential and particle size measurements which showed that the dispersion stability is not sacrificed with the addition of GOx, and significantly, the electrical properties of the rGO and MWCNTs are …

Evaluation Of Encapsulating Coatings On The Performance Of Polypyrrole Actuators, Sina Naficy, Nicholas Stoboi, Philip G. Whitten, Geoffrey M. Spinks, Gordon G. Wallace

Gordon Wallace

Conjugated polymer actuators are electroactive materials capable of generating force and movement in response to an applied external voltage. Many potential biomedical and industrial applications require these actuators to operate in a liquid environment. However, immersion of uncoated conducting polymer actuators in non-electrolyte liquids greatly reduces their operating lifetime. Here, we demonstrate the use of spray coating as an effective and simple method to encapsulate polypyrrole (PPy) tri-layer bending actuators. Poly(styrene-b-isobutylene-b-styrene) (SIBS) was used as an encapsulating, compliant spray coating on PPy actuators. A significant enhancement in actuator lifetime in both air and water was observed by encapsulating the actuators. …

Cation Exchange At Semiconducting Oxide Surfaces: Origin Of Light-Induced Performance Increases In Porphyrin Dye-Sensitized Solar Cells, Matthew J. Griffith, Kenji Sunahara, Akihiro Furube, Attila J. Mozer, David L. Officer, Pawel Wagner, Gordon G. Wallace, Shogo Mori

Gordon Wallace

The origin of simultaneous improvements in the short-circuit current density (Jsc) and open-circuit voltage (Voc) of porphyrin dye-sensitized TiO2 solar cells following white light illumination was studied by systematic variation of several different device parameters. Reduction of the dye surface loading resulted in greater relative performance enhancements, suggesting open space at the TiO2 surface expedites the process. Variation of the electrolyte composition and subsequent analysis of the conduction band potential shifts suggested that a light-induced replacement of surface-adsorbed lithium (Li+) ions with dimethylpropylimidazolium (DMPIm+) ions was responsible for an increased electron lifetime by decreasing the recombination with the redox mediator. …

A Facile Route To Synthesize Transition Metal Oxide/Reduced Graphene Oxide Composites And Their Lithium Storage Performance, Chongjun Zhao, Shulei Chou, Yunxiao Wang, Cuifeng Zhou, Hua-Kun Liu, S X. Dou

Shi Xue Dou

Transition metal oxide (Mn3O4, Fe2O3, Co3O4, and ZnO) and reduced graphene oxide (RGO) composites were successfully synthesized via a hydrothermal method using the direct reaction between the corresponding metal powder and graphene oxide (GO). In this process, the GO can be reduced by transition metal powder in water, and the nanosized metal oxide can be obtained, and homogeneously mixed with and wrapped by RGO to form a metal oxide/RGO composite at the same time. X-ray diffraction, Raman spectroscopy, X-ray photoelectron spectroscopy, and scanning and transmission electron microscopy were used to characterize the as-prepared materials. The different experimental parameters, including reactants, …

Synergetic Combination Of Limd With Chpd For The Production Of Economical And High Performance Mgb2 Wires, Minoru Maeda, Md Shahriar Ai Hossain, Ashkan Motaman, Jung Ho Kim, Anna Kario, Matt Rindfleisch, Mike Tomsic, S X. Dou

Shi Xue Dou

We propose an economical fabrication concept, the localized internal magnesium diffusion (IMD) method. Instead of using a single magnesium (Mg) rod in the center of a metal sheath tube, we use large-sized Mg particles (20-50 mesh) mixed well with cheap 97% crystalline boron powder to fill the metal sheath tube. After a repeated drawing process, the coarse Mg is elongated along the core wire axis of the metal sheath tube. Textured MgB2 grains are then formed during the sintering process. In the localized IMD process, however, there is still a need to improve the overall density. In order to increase …

A Regression Model To Investigate The Performance Of Black-Scholes Using Macroeconomic Predictors, Timothy A. Smith, Ersoy Subasi, Aliraza M. Rattansi

Timothy Smith