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Physical Sciences and Mathematics

2012

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Articles 1 - 30 of 80

Full-Text Articles in Engineering Science and Materials

Ternary Alloy Electrocatalysts For Oxygen Reduction Reaction, Jin Luo, Lefu Yang, Binghui Chen, Chuanjian Zhong Dec 2012

Ternary Alloy Electrocatalysts For Oxygen Reduction Reaction, Jin Luo, Lefu Yang, Binghui Chen, Chuanjian Zhong

Journal of Electrochemistry

Proton exchange membrane fuel cell represents an important electrochemical energy conversion device with many attractive features in terms of efficiency of energy conversion and minimization of environmental pollution. However, the large overpotential for oxygen reduction reaction at the cathode and the low activity, poor durability and high cost of platinum-based catalysts in the fuel cells constitute a focal point of major barriers to the commercialization of fuel cells. The development of nanostructured catalysts shows promises to addresses some of the challenging problems. The ability to engineer the composition and nanostructure of nanoalloy catalysts is important for developing active, robust and …

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Electrocatalytic Activity Of Palladium Nanocatalysts Supported On Carbon Nanoparticles In Formic Acid Oxidation, Jie Huang, Zhiyou Zhou, Yang Song, Xiongwu Kang, Ke Liu, Wancheng Zhou, Shaowei Chen Dec 2012

Electrocatalytic Activity Of Palladium Nanocatalysts Supported On Carbon Nanoparticles In Formic Acid Oxidation, Jie Huang, Zhiyou Zhou, Yang Song, Xiongwu Kang, Ke Liu, Wancheng Zhou, Shaowei Chen

Journal of Electrochemistry

Palladium nanostructures were deposited onto carbon nanoparticle surface by a chemical reduction method. Transmission electron microscopic studies showed that whereas the resulting metal-carbon (Pd-CNP) nanocomposites exhibited a diameter of 20 to 30 nm, the metal components actually showed a cauliflower-like surface morphology that consisted of numerous smaller Pd nanoparticles (3 to 8 nm). Electrochemical studies showed that the effective surface area of the Pd-CNP nanoparticles was about 40% less than that of Pd black, possibly because the Pd nanoparticles were coated with a layer of carbon nanoparticles; yet, the Pd-CNP nanocomposites exhibited marked enhancement of the electrocatalytic activity in formic …

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Electrochemical Performance Of Screen-Printed Composite Coatings Of Conducting Polymers And Carbon Nanotubes On Titanium Bipolar Plates In Aqueous Asymmetrical Supercapacitors, Xiaohang Zhou, George Z. Chen Dec 2012

Electrochemical Performance Of Screen-Printed Composite Coatings Of Conducting Polymers And Carbon Nanotubes On Titanium Bipolar Plates In Aqueous Asymmetrical Supercapacitors, Xiaohang Zhou, George Z. Chen

Journal of Electrochemistry

Composites of conducting polymers (polypyrrole and polyaniline) with acid treated multi-walled carbon nanotubes were formulated into printable aqueous inks, with the aid of functional additives (benzethonium chloride as a surfactant with or without polyvinyl alcohol as a binder). The inks were screen-printed as fairly uniform coatings of various mass loading densities and areas (up to 75 mg cm-2 and 100 cm2) on thin titanium plates (0.1 mm in thickness). These screen-printed plates were used to fabricate both unit cell and multi-cell stack of asymmetrical supercapacitors with screen-printed negative electrodes of activated carbon (pigment black) in aqueous electrolytes …

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Advances And Challenges Of Intermediate Temperature Solid Oxide Fuel Cells: A Concise Review, Sanping Jiang Dec 2012

Advances And Challenges Of Intermediate Temperature Solid Oxide Fuel Cells: A Concise Review, Sanping Jiang

Journal of Electrochemistry

Fuel cell is an electrochemical energy conversion device to directly convert the chemical energy of fuels to electricity. Among all types of fuel cells, solid oxide fuel cells (SOFCs) operating at intermediate temperatures of 600~800 oC offer an attractive option that is much more fuel flexible than low temperature fuel cells such as proton exchange membrane fuel cells, and is suitable for a wide range of applications. However, two main challenges remain towards the commercial viability and acceptance of the SOFC technologies: the cost and durability. Both are critically dependent on the process, fabrication, performance, chemical and microstructural stability …

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Electrocatalytic Oxidation Of Formic Acid On Pd/Ni Heterostructured Catalyst, Mingjun Ren, Liangliang Zou, Ju Chen, Ting Yuan, Qinghong Huang, Haifeng Zhang, Hui Yang, Songlin Feng Dec 2012

Electrocatalytic Oxidation Of Formic Acid On Pd/Ni Heterostructured Catalyst, Mingjun Ren, Liangliang Zou, Ju Chen, Ting Yuan, Qinghong Huang, Haifeng Zhang, Hui Yang, Songlin Feng

Journal of Electrochemistry

A Pd/Ni bimetallic nanostructured electrocatalyst was fabricated via a two-step reduction route. Owing to an epitaxial growth of Pd atoms on the surface of Ni nanoparticles, heterostructured Pd/Ni nanocomposites were formed and verified by high resolution transmission electron microscopy combined with energy-dispersion X-ray spectroscopy. X-ray diffraction confirmed that the as-prepared Pd/Ni nanocomposites possessed a single face-centered-cubic (fcc) Pd structure, probably due to a weaker diffraction intensity of metallic Ni and/or overlapping by that of Pd. The intrinsic catalytic activity on the Pd/Ni is higher than that on the Pd. Moreover, the durability of formic acid oxidation on the Pd/Ni was …

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Adsorption And Electrooxidation Of Carbon Monoxide On Platinum Surfaces Modified With Sulfur, A. Mattox Mathew, W. Henney Matthew, Johnson Adam, Zou Shouzhong Dec 2012

Adsorption And Electrooxidation Of Carbon Monoxide On Platinum Surfaces Modified With Sulfur, A. Mattox Mathew, W. Henney Matthew, Johnson Adam, Zou Shouzhong

Journal of Electrochemistry

Adsorbed sulfur is commonly considered as a reaction poison. However, small amounts of sulfur on platinum significantly increase the surface reactivity toward carbon monoxide (CO) electrooxidation. For the solution CO oxidation, the onset potential was shifted up to over 300 mV negative to that on S-free surface, and the extent of the negative potential shift increases with the sulfur coverage (Xs) up to about 0.6. The enhanced CO oxidation also depends on the solution pH. For the adsorbed CO, at low sulfur coverages (Xs < 0.3), the oxidation peak potential is about 40 mV negative to that of the corresponding clean Pt. However, at higher coverages, the peak potential is about 30 mV more positive. Surface-enhanced Raman spectra show that the adsorption of sulfur significantly redshifts the Pt-CO stretching frequency. These observations are explained by the weakening of the Pt-CO bond and the hindrance of CO diffusion by Sads.

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Kinetic Study Of Photoelectrochemical Oxidation Of Lignin Model Compounds On Tio2 Nanotubes, Min Tian, Daniel Liba, Aicheng Chen Dec 2012

Kinetic Study Of Photoelectrochemical Oxidation Of Lignin Model Compounds On Tio2 Nanotubes, Min Tian, Daniel Liba, Aicheng Chen

Journal of Electrochemistry

In this study, TiO2 nanotubes were prepared via the electrochemical oxidation of titanium substrates in a non-aqueous electrolyte and their morphology and microstructures were examined by scanning electron microscopy (SEM) and X-ray diffraction (XRD). The photoelectrochemical oxidation of two lignin model compounds, 1-(3,4-dimethoxyphenoxy)-2-(2-methoxyphenoxy)-1,3-propanediol (DMP) and 3-hydroxy-1-(3,4-dimethoxyphenoxy)-2-(2-methoxyphenoxy)-1,3-propanone (HDM), was investigated. A new band appeared at ~304 nm during the photoelectrochemical oxidation of DMP. The rate of DMP intermediate formation was amplified with the increase of initial concentrations, while it was diminished with increased temperature. Despite the similarity in structure between HDM and DMP, there are only small increases in absorbance …

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Validation Of Weak Form Thermal Analysis Algorithms Supporting Thermal Signature Generation, Elton Lewis Freeman Dec 2012

Validation Of Weak Form Thermal Analysis Algorithms Supporting Thermal Signature Generation, Elton Lewis Freeman

Masters Theses

Extremization of a weak form for the continuum energy conservation principle differential equation naturally implements fluid convection and radiation as flux Robin boundary conditions associated with unsteady heat transfer. Combining a spatial semi-discretization via finite element trial space basis functions with time-accurate integration generates a totally node-based algebraic statement for computing. Closure for gray body radiation is a newly derived node-based radiosity formulation generating piecewise discontinuous solutions, while that for natural-forced-mixed convection heat transfer is extracted from the literature. Algorithm performance, mathematically predicted by asymptotic convergence theory, is subsequently validated with data obtained in 24 hour diurnal field experiments for …

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In Situ Pm-Irras Studies Of A Floating Bilayer Lipid Membrane At Au(111) Electrode Surface, Su Zhangfei, Kycia Annia, Jay Leitch J., Lipkowski Jacek Oct 2012

In Situ Pm-Irras Studies Of A Floating Bilayer Lipid Membrane At Au(111) Electrode Surface, Su Zhangfei, Kycia Annia, Jay Leitch J., Lipkowski Jacek

Journal of Electrochemistry

In situ Polarization modulation infrared reflection absorption spectroscopy (PM-IRRAS) was used to study the structure of a DMPC + cholesterol + GM1 floating bilayer lipid membrane (fBLM) at a Au(111) surface. 1-thio-beta-D-glucose (beta-Tg) was self-assembled onto the Au electrode to increase the overall hydrophilicity of the surface. The fBLM was deposited on the beta-Tg self-assembled monolayer (SAM) using a combination of Langmuir-Blodgett/Langmuir-Schaefer (LB/LS) techniques. The carbohydrate headgroups of the GM1 molecules were physically adsorbed to the beta-Tg SAM forming a water rich cushion between the fBLM and the modified gold substrate. The PM-IRRAS spectra indicate that the DMPC molecules within …

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The Oxidation Of Hydrogen Peroxide On Nanostructured Rhodium Microelectrodes, N. Bartlett Philip, F. Esterle Thomas Oct 2012

The Oxidation Of Hydrogen Peroxide On Nanostructured Rhodium Microelectrodes, N. Bartlett Philip, F. Esterle Thomas

Journal of Electrochemistry

Mesoporous Rh films were deposited onto platinum microelectrodes from the H1 lyotropic liquid crystalline phase of C12EO8 (octaethyleneglycol monododecyl ether). The electrodes show well defined voltammetry for the oxidation and the reduction of hydrogen peroxide at low concentrations (<10 mmol•L-1) with excellent stability for operation at neutral pH. Based on the hysteresis in the current and the potential dependence the oxidation of hydrogen peroxide occurs through a CEE mechanism involving Rh(OH)3 on the mesoporous Rh electrode surface. At higher hydrogen peroxide concentrations the current reaches a plateau that is due to either saturation of the binding sites for hydrogen peroxide or limitation of the reaction due to acidification of the solution within the pores. For the thin films (below 200 nm) the hydrogen peroxide calibration curves we …

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Electrochemical Synthesis Of Silver-Tetracyanoquinodimethane Nanorods At Agar Supported Water/1,2-Dichloroethane Interface, Li Huang, Yixian Wang, Michael V. Mirkin, Bin Ren, Dongping Zhan Oct 2012

Electrochemical Synthesis Of Silver-Tetracyanoquinodimethane Nanorods At Agar Supported Water/1,2-Dichloroethane Interface, Li Huang, Yixian Wang, Michael V. Mirkin, Bin Ren, Dongping Zhan

Journal of Electrochemistry

Silver-tetracyanoquinodimethane (AgTCNQ) is an important charge transfer salt due to its high conductivity and other electronic properties. In this communication, we report the synthesis of AgTCNQ at the liquid/liquid interface. Agar was used as a gelling agent to support water/1,2-dichloroethane (DCE) interface. Silver ions were transferred from the hydrogel into DCE phase, where they combined with TCNQ- to form AgTCNQ nanorods. The developed method can provide a new route for synthesis of functional materials based on the electrochemistry at the liquid/liquid interface.

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Electrochemical Corrosion And Protection Of Copper Foil Treated By Surface Siloxane Filming, Wei-Jun Miao, Yu-Bao Zhang, Ning-Yu Gu, Feng Liu Aug 2012

Electrochemical Corrosion And Protection Of Copper Foil Treated By Surface Siloxane Filming, Wei-Jun Miao, Yu-Bao Zhang, Ning-Yu Gu, Feng Liu

Journal of Electrochemistry

Copper foil specimens were immersed in hydro-alcoholic solution of 3-amino-propyl-trimethoxy-silane (γ-APS) to prepare a protective self-assembled siloxane membrane on the surface. Potentiodynamic polarization and electrochemical impedance spectroscopic tests were performed in 0.1 mol.L-1 NaCl to evaluate the effects of the self-assembled siloxane membranes prepared at different pH of γ-APS on corrosion of copper foil. The surface morphology of siloxane membrane was studied by SEM. Experimental results revealed that the γ-APS self-assembled siloxane membranes effectively inhibited the corrosion of copper foil and the optimum anti-corrosion effect was found when the pH value of the silane solution was 7.

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Poly(Aniline/O-Nitroaniline): A High Capacity Cathode Material For Lithium Ion Batteries, Rui-Rui Zhao, Li-Min Zhu, Jiang-Feng Qian, Han-Xi Yang Aug 2012

Poly(Aniline/O-Nitroaniline): A High Capacity Cathode Material For Lithium Ion Batteries, Rui-Rui Zhao, Li-Min Zhu, Jiang-Feng Qian, Han-Xi Yang

Journal of Electrochemistry

Polyaniline can be used as a high capacity cathode material due to the advantages of material abundance and synthetic simplicity. However, its practical application in battery has been hindered by poor electrochemical utilization and cycling instability. To solve these problems, we synthesized the poly(aniline/o-Nitroaniline) (P(AN-oNA)) by introducing the electron-drawing group-nitroaniline onto the polyaniline chains, so as to enhance electrochemical utilization and stability of the polyaniline derivative. The as-prepared Li/P(AN-oNA) copolymer shows a greatly enhanced discharge capacities of 186 mAh.g-1 at initial cycles, about 37% higher than its parent PAN, and remains 168 mAh.g-1 after 60th cycle. Also, the …

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Synthesis And Electrochemical Characterization Of Li3V2(Po4)3/C Cathode Material By Ball-Milling Assisted Microwave Method, Zhi-Yuan Tang, Wen-Feng Mao, Ji Yan, Wei Yuan, Xin-He Zhang Aug 2012

Synthesis And Electrochemical Characterization Of Li3V2(Po4)3/C Cathode Material By Ball-Milling Assisted Microwave Method, Zhi-Yuan Tang, Wen-Feng Mao, Ji Yan, Wei Yuan, Xin-He Zhang

Journal of Electrochemistry

The cathode materials of Li3V2(PO4)3/C were successfully synthesized by ball-milling assisted microwave method and the microwave irradiation time was also optimized. It is found that the Li3V2(PO4)3/C material obtained at a microwave power of 640 W for 18 min showed the best electrochemical performance with the initial reversible capacity of 101.3 mAh.g-1 and the remained 100.8 mAh.g-1 at 5C rate after 300 cycles. This excellent electrochemical capability may be resulted from good crystallinity, smaller and uniform particle size of the material, showing …

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Electrochemical Performance Of Yf3-Coated Li(Li0.22Ni0.17Mn0.61)O2 Cathode Material For Li-Ion Batteries, Xin Feng, Guo-Ran Li, Shi-Hai Ye, Xue-Ping Gao Aug 2012

Electrochemical Performance Of Yf3-Coated Li(Li0.22Ni0.17Mn0.61)O2 Cathode Material For Li-Ion Batteries, Xin Feng, Guo-Ran Li, Shi-Hai Ye, Xue-Ping Gao

Journal of Electrochemistry

The Li(Li0.22Ni0.17Mn0.61)O2 was prepared with oxalic co-precipitation and coated with an YF3 layer by a chemical deposition method. The as-prepared and YF3-coated Li-rich materials were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS). The results demonstrate that the as-prepared and YF3-coated Li(Li0.22Ni0.17Mn0.61)O2 materials have a typical layered structure and are composed of sphere-like particles with a diameter of 100~200 nm. Galvanostatic charge-discharge tests show that the discharge capacity of the YF3-coated Li(Li0.22 …

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Synthesis And Electrochemical Properties Of High-Capacity Cathode Material 0.08lico0.75Al0.25O2-0.92linio2, Ru-Ying Wang, Tian Qiu, Chong Mao, Wen-Sheng Yang Aug 2012

Synthesis And Electrochemical Properties Of High-Capacity Cathode Material 0.08lico0.75Al0.25O2-0.92linio2, Ru-Ying Wang, Tian Qiu, Chong Mao, Wen-Sheng Yang

Journal of Electrochemistry

CoAl-LDH or Co(OH)2 coated spherical Ni(OH)2 precursors were obtained via a co-precipitation method at a constant pH. The mixtures of the precursors and LiOH.H2O were annealed at high temperature in O2 atmosphere, and then the cathode materials of 0.08LiCo0.75Al0.25O2-0.92LiNiO2, 0.08LiCoO2-0.92LiNiO2 and LiNiO2 were synthesized. Effects of the coating layer were also studied. The results showed that the 0.08LiCo0.75Al0.25O2-0.92LiNiO2 material possessed the best rate and cycle life performance. The discharging capacities at 0.1C, 0.5C and 3C were …

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Influences Of Particle Size And Sulfuric Acid Treatment On The Electrochemical Performance Of Bamboo Charcoal, Yu Yao, Ai-Shui Yu Aug 2012

Influences Of Particle Size And Sulfuric Acid Treatment On The Electrochemical Performance Of Bamboo Charcoal, Yu Yao, Ai-Shui Yu

Journal of Electrochemistry

The bamboo charcoal had been milled and treated by sulfuric acid. The influences of as-prepared material particle size and sulfuric acid treatment on the electrochemical performance had been studied. The result displays that the bamboo charcoal with mean particle size about 5 μm has the best first coulombic efficiency. Sulfuric acid treatment could raise the discharge capacity of bamboo charcoal, and the first discharge capacity of 328.2 mAh.g-1 was obtained with the bamboo charcoal treated by sulfuric acid for 18 h. Furthermore, the capacity of 302.3 mAh.g-1 could be maintained for 50 cycles, showing good cycle performance.

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Preparation And Performance Of Sn-Co-M-C（M = Zn, Fe）Composites As An Anode Material, Guo-Qing Fang, Wei-Wei Liu, Shi-Ci He, Qian Zhang, Jun-Wei Zheng, De-Cheng Li Aug 2012

Preparation And Performance Of Sn-Co-M-C（M = Zn, Fe）Composites As An Anode Material, Guo-Qing Fang, Wei-Wei Liu, Shi-Ci He, Qian Zhang, Jun-Wei Zheng, De-Cheng Li

Journal of Electrochemistry

The anode materials of Sn-Co-M-C (M = Zn, Fe) composites were prepared by carbothermal reduction method from metal oxides and sucrose in N2 atmosphere. Their structural and electrochemical properties were studied by XRD, SEM and charge-discharge test. Among them, the Sn-Co-Zn-C composite showed higher specific capacity and good cycle performance. The initial specific discharge capacity of 571 mAh.g-1 could be obtained, while 369 mAh.g-1 was still kept after 45 cycles.

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Electrochemical Sensing Of Guanine And Adenine Based On The Boron-Doped Carbon Nanotubes Modified Electrode, Ya-Lin Xia, Chun-Yan Deng, Juan Xiang Aug 2012

Electrochemical Sensing Of Guanine And Adenine Based On The Boron-Doped Carbon Nanotubes Modified Electrode, Ya-Lin Xia, Chun-Yan Deng, Juan Xiang

Journal of Electrochemistry

In this work, the boron-doped carbon nanotubes (BCNTs) modified glassy carbon (GC) electrode was simply fabricated, and the electrochemical oxidation behaviors of guanine and adenine at the BCNTs/GC electrode were investigated. Compared with the bare GC and CNTs/GC electrodes, the BCNTs-modified electrode exhibited extraordinary electrocatalytic activity towards the oxidations of guanine and adenine as indicated by the obvious increase in current responses. Moreover, the peak separation between guanine and adenine was large enough for their potential recognition in mixture without any separation or pretreatment. Therefore, the simultaneous determination of guanine and adenine was successfully achieved. The BCNTs/GC electrode showed high …

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Electrochemical Immunosensor Based On Polycalconcarboxylic Acid Modified Electrode For The Determination Of Alpha-Fetoprotein, Xiao Lin, Shao-Huang Weng, Jian-Zhang Zhou, Ai-Lin Liu, Xin-Hua Lin, Yong-Ji You Aug 2012

Electrochemical Immunosensor Based On Polycalconcarboxylic Acid Modified Electrode For The Determination Of Alpha-Fetoprotein, Xiao Lin, Shao-Huang Weng, Jian-Zhang Zhou, Ai-Lin Liu, Xin-Hua Lin, Yong-Ji You

Journal of Electrochemistry

A highly sensitive electrochemical immunosensor based on novel electropolymerized polycalconcarboxylic acid modified electrode (poly-CCA/GC) has been fabricated for the detection of alpha-fetoprotein (AFP). The differences of the poly-CCA/GC electrodes before and after the immobilization of AFP antibody were characterized via scanning electron microscopy (SEM) and electrochemical impedance spectroscopy (EIS). The immobilization of antibody/antigen/antibody-HRP sandwich was formed on the poly-CCA modified electrode for the determination of special AFP concentrations. The electrochemical signals generated from the HRP which catalyzed the TMB substrate were measured. Experiment results indicated that the developed immunosensor showed a good sensitivity and precision.

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Electrocatalytic Activities Of Mb/Aunps/Mwnts/Gc Electrode For Hydrogen Peroxide Reduction, Zheng-Juan Huang, Hua-Ping Peng, Dai-Jun Cha, Ai-Lin Liu, Wei Chen, Xin-Hua Lin, Yong-Ji You Aug 2012

Electrocatalytic Activities Of Mb/Aunps/Mwnts/Gc Electrode For Hydrogen Peroxide Reduction, Zheng-Juan Huang, Hua-Ping Peng, Dai-Jun Cha, Ai-Lin Liu, Wei Chen, Xin-Hua Lin, Yong-Ji You

Journal of Electrochemistry

A novel matrix, multiwalled carbon nanotubes supported Au nanoparticles composite nanomaterial (AuNPs/MWNTs), for immobilization of protein and biosensing was designed using a simple and effective one-step in situ synthesis route. Using myoglobin (Mb) as a model, the direct electrochemistry of the immobilized proteins on the AuNPs/MWNTs composite was studied. The results showed that the AuNPs/MWNTs composite can maintain the bioactivity and facilitate the direct electrochemistry of Mb in the Mb/AuNPs/MWNTs/GC electrode. Based on the direct electron transfer of the immobilized Mb, the protein electrode exhibited excellent electrocatalytic activity to the reduction of H2O2 with a linear range …

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Preparation And Modification Of Li4Ti5O12 As Anode Materials For Lithium-Ion Batteries, Jin-Long Liu, Zhou-Guang Lu, Yang Ren, Ya-Jie Zhu, Shan-Shan Hu, Zhong Peng, Dong Qian, You-Gen Tang Aug 2012

Preparation And Modification Of Li4Ti5O12 As Anode Materials For Lithium-Ion Batteries, Jin-Long Liu, Zhou-Guang Lu, Yang Ren, Ya-Jie Zhu, Shan-Shan Hu, Zhong Peng, Dong Qian, You-Gen Tang

Journal of Electrochemistry

Anode Material Li4Ti5O12 for lithium-ion batteries was successfully prepared using half-solid-state method. Furthermore, carbon coating modification of Li4Ti5O12 was also carried out. The phase structure and morphology were analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and high resolution transmission electron microscopy (HRTEM). The electrochemical properties were investigated by constant current discharge-charge tests, cyclic voltammetry and electrochemical impedance techniques. The results indicated that the electrochemical performance of Li4Ti5O12 without modification declined seriously due to the aggregation of Li4Ti …

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Electrochemical Performances Of Layered Polypyrrole/Chemically Reduced Graphene Oxide Nanocomposites As Supercapacitor Electrodes, Si-Zhe Xu, Xue-Jiao Zhou, Kun Wu, Yong-Qiang Yang, Hai-Xia Wu Aug 2012

Electrochemical Performances Of Layered Polypyrrole/Chemically Reduced Graphene Oxide Nanocomposites As Supercapacitor Electrodes, Si-Zhe Xu, Xue-Jiao Zhou, Kun Wu, Yong-Qiang Yang, Hai-Xia Wu

Journal of Electrochemistry

Nanocomposites of polypyrrole (Ppy) and chemically reduced graphene oxide (CRGO), Ppy/CRGO, have been fabricated through in-situ polymerization of pyrrole on graphene oxide (GO) sheets. The as-synthesized Ppy/CRGO composites were characterized complementarily using scanning electron microscopy (SEM), thermogravimetric analysis (TGA), and Fourier transformed infrared spectroscopy (FT-IR). By controlling the initial ratio of the GO to pyrrole, the layered composites could be obtained and their thickness could be tuned properly. The Ppy/CRGO electrodes were prepared using a mechanical compressing technique and their electrical conductivity and electrochemical properties were characterized systematically. We demonstrated that as electrodes for supercapacitor, the Ppy/CRGO composites with Ppy …

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Naf-M (M = Fe, Cu) Nanocomposites As Conversion Cathode Materials For Sodium Ion Batteries, Ting Li, Zhong-Xue Chen, Yu-Liang Cao, Han-Xi Yang Aug 2012

Naf-M (M = Fe, Cu) Nanocomposites As Conversion Cathode Materials For Sodium Ion Batteries, Ting Li, Zhong-Xue Chen, Yu-Liang Cao, Han-Xi Yang

Journal of Electrochemistry

The NaF-M (M = Fe, Cu) nanocomposites were prepared by high-energy ball milling using TiN grinding nanoparticles and investigated as cathode materials for sodium ion batteries. The experimental results demonstrated that NaF-Fe and NaF-Cu nanocomposites can go through electrochemical conversion reaction with Na+ uptake or removal, delivering a reversible capacity of ~ 150 mAh.g-1, even through a reversed conversion from initial discharged state to a charged state. These results reveal the possibility to realize a conversion reaction as long as NaF and elemental metal particles are intimately contacted to form active nanocomposites at nanodomain, which suggests a …

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Carbon Nanotubes With Ni2P Nanoparticles As A Counter Electrode In Dye-Sensitized Solar Cells, Yan-Ye Dou, Nan-Fu Yan, Guo-Ran Li, Xue-Ping Gao Aug 2012

Carbon Nanotubes With Ni2P Nanoparticles As A Counter Electrode In Dye-Sensitized Solar Cells, Yan-Ye Dou, Nan-Fu Yan, Guo-Ran Li, Xue-Ping Gao

Journal of Electrochemistry

Carbon nanotubes (CNTs) supported by Ni2P nanoparticles are prepared and used as a counter electrode in dye-sensitized solar cells (DSSCs) for the first time. The CNTs-Ni2P composite was prepared by the heat treatment of a mixed precursor including nickel chloride, sodium hypophosphite and CNTs in argon atmosphere. The X-Ray diffraction (XRD) results indicate that the as-prepared sample consists of hexagonal Ni2P and carbon nanotubes. No peaks of other nickel phosphides are observed in the XRD pattern. Microstructure of the Ni2P-CNTs composite was investigated using transmission electron microscopy (TEM). It is shown that the Ni …

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A Facile Approach To Prepare Lifepo4/C Composite With High-Rate Performance, Peng Zhang, Ling-Bin Kong, Yong-Chun Luo, Long Kang Aug 2012

A Facile Approach To Prepare Lifepo4/C Composite With High-Rate Performance, Peng Zhang, Ling-Bin Kong, Yong-Chun Luo, Long Kang

Journal of Electrochemistry

The LiFePO4/C composite electrode material was synthesized by a moderate in situ carbothermal reduction method at 600 °C using FeCl3.6H2O, LiOH.H2O, and NH4H2PO4 as starting materials, soluble starch sol as a carbon source and a reducing agent. This method is readily reproducible and possibly feasible to carry out large-scale synthesis. The structure and morphology of the LiFePO4/C samples were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The synthesized LiFePO4/C composite was in pure phase of olivine-type, …

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Dynamical Properties Of Ferroelectric Perovskites (Ba,Sr)Tio3 And Pb(Zr,Ti)O3 Systems From First Principles, Jeevaka Weerasinghe Aug 2012

Dynamical Properties Of Ferroelectric Perovskites (Ba,Sr)Tio3 And Pb(Zr,Ti)O3 Systems From First Principles, Jeevaka Weerasinghe

Graduate Theses and Dissertations

A first-principles-based effective Hamiltonian scheme which incorporates coupling between ferroelectric (FE) and antiferrodistortive (AFD) motions is applied to Pb(Zr,Ti)O3 alloys. It validates the existence of two modes of E symmetry (rather than the single E(1TO) soft mode) in the 50-75 cm-1 range for temperatures smaller than 200 K and for compositions falling within the Rhombohedral R3c phase. Coupling between long-range-ordered FE and AFD motions is shown to be the cause of the additional mode and more insight into its nature is provided. This scheme is further used to reveal a field-induced anticrossing involving FE and AFD degrees of …

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Switch Yard Operation In Thermal Power Plant(Katpp Jhalawar Rajasthan), Radhey Shyam Meena Er. Jul 2012

Switch Yard Operation In Thermal Power Plant(Katpp Jhalawar Rajasthan), Radhey Shyam Meena Er.

Radhey Shyam Meena

Switchyard Provides the facilities for switching ,protection & Control of electric power. To handle high Voltage power with proper Safety measures. To isolate the noises coming from the grid with true 50Hz power SWITCH YARD IS IMPORTANT PART IN THERMAL PLANT. IN KALISINDH THERMAL 400KV AND 220KV SWITCH YARD LOCATED.

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Propagation Of Ultrasound Through Freshly Excised Human Calvarium, Armando Garcia Noguera Jul 2012

Propagation Of Ultrasound Through Freshly Excised Human Calvarium, Armando Garcia Noguera

Department of Engineering Mechanics: Dissertations, Theses, and Student Research

The propagation of ultrasound through complex biological media, such as the human calvarium, poses a great challenge for modern medicine. Several ultrasonic techniques commonly used for treatment and diagnosis in most of the human body are still difficult to apply to the human brain, in part, because of the properties of the skull. Moreover, an understanding of the biomechanics of transcranial ultrasound may provide needed insight into the problem of blast wave induced traumatic brain injury (TBI). In the present study, the spatial variability of ultrasonic properties was evaluated for relevant frequencies of 0.5, 1, and 2.25 MHz. A total …

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Synthesis Of Spherical Ni3S4 By Solvothermal Method As Supercapacitor Electrodes, Qing-Na Huan, Li-Fang Jiao, Qing-Hong Wang, Hong-Mei Du, Jia-Qin Yang, Wen-Xiu Peng, Yi-Jing Wang, Hua-Tang Yuan Jun 2012

Synthesis Of Spherical Ni3S4 By Solvothermal Method As Supercapacitor Electrodes, Qing-Na Huan, Li-Fang Jiao, Qing-Hong Wang, Hong-Mei Du, Jia-Qin Yang, Wen-Xiu Peng, Yi-Jing Wang, Hua-Tang Yuan

Journal of Electrochemistry

The Ni3S4 microspheres have been synthesized via a facile solvothermal method. The crystal structure and surface morphology are characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). Microspherical Ni3S4 exhibits good electrochemical capacitance validated by electrochemical measurements. The specific capacities of 1120.6 F.g-1 at 0.5 A.g-1 and 433.4 F.g-1 at 4 A.g-1 with the capacitance retention of 89.37 % and 84.88 % were obtained after 1000 cycles, respectively. The electrochemical reaction is expected due to the transformation of Ni(OH)2 and NiOOH based on the XRD, XPS and CV analysis results.

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