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Sample records for acid doped polybenzimidazole

  1. Physicochemical properties of phosphoric acid doped polybenzimidazole membranes for fuel cells

    DEFF Research Database (Denmark)

    He, Ronghuan; Li, Qingfeng; Bach, Anders;

    2006-01-01

    Polybenzimidazole (PBI) membranes have been prepared with different molecular weights. The water and acid swelling, mechanical strength,gas permeability and proton conductivity were studied for the pristine and acid doped PBI membranes. When doped with 5 mol of phosphoric acid per mole repeat uni...

  2. Water Uptake and Acid Doping of Polybenzimidazoles as Electrolyte Membranes for Fuel Cells

    DEFF Research Database (Denmark)

    Qingfeng, Li; He, R.; Berg, Rolf W.

    2004-01-01

    Acid-doped polybenzimidazole (PBI) membranes have been demonstrated for fuel cell applications with advanced features such as high operating temperatures, little humidification, excellent CO tolerance, and promising durability. The water uptake and acid doping of PBI membranes have been studied...

  3. Proton conductivity of phosphoric acid doped polybenzimidazole and its composites with inorganic proton conductors

    DEFF Research Database (Denmark)

    He, Ronghuan; Qingfeng, Li; Gang, Xiao

    2003-01-01

    Phosphoric acid doped polybenzimidazole (PBI) and PBI composite membranes have been prepared in the present work. The PBI composites contain inorganic proton conductors including zirconium phosphate (ZrP), (Zr(HPO4)2·nH2O), phosphotungstic acid (PWA), (H3PW12O40·nH2O) and silicotungstic acid (Si...

  4. Doping phosphoric acid in polybenzimidazole membranes for high temperature proton exchange membrane fuel cells

    DEFF Research Database (Denmark)

    He, Ronghuan; Li, Qingfeng; Jensen, Jens Oluf;

    2007-01-01

    Polybenzimidazole (PBI) membranes were doped in phosphoric acid solutions of different concentrations at room temperature. The doping chemistry was studied using the Scatchard method. The energy distribution of the acid complexation in polymer membranes is heterogeneous, that is, there are two...... different types of sites in PBI for the acid doping. The protonation constants of PBI by phosphoric acid are found to be 12.7 L mol(-1) (K-1) for acid complexing sites with higher affinity, and 0.19 L mol(-1) (K-2) for the sites with lower affinity. The dissociation constants for the complexing acid onto...... these two types of PBI sites are found to be 5.4 X 10(-4) and 3.6 X 10(-2), respectively, that is, about 10 times smaller than that of aqueous phosphoric acid in the first case but 5 times higher in the second. The proton conducting mechanism is also discussed....

  5. Lowering the platinum loading of high temperature polymer electrolyte membrane fuel cells with acid doped polybenzimidazole membranes

    DEFF Research Database (Denmark)

    Fernandez, Santiago Martin; Li, Qingfeng; Jensen, Jens Oluf

    2015-01-01

    Membrane electrode assemblies (MEAs) with ultra-low Pt loading electrodes were prepared for high temperature polymer electrolyte membrane fuel cells (HT-PEMFCs) based on acid doped polybenzimidazole. With no electrode binders or ionomers, the triple phase boundary of the catalyst layer...

  6. Durability Issues of High Temperature Proton Exchange Membrane Fuel Cells Based on Acid Doped Polybenzimidazole Membranes

    DEFF Research Database (Denmark)

    To achieve high temperature operation of proton exchange membrane fuel cells (PEMFC), preferably under ambient pressure, phosphoric acid doped polybenzimidazole (PBI) membrane represents an effective approach, which in recent years has motivated extensive research activities with great progress....... As a critical concern, issues of long term durability of PBI based fuel cells are addressed in this talk, including oxidative degradation of the polymer, mechanical failures of the membrane, acid leaching out, corrosion of carbon support and sintering of catalysts particles. Excellent polymer durability has...... observed under continuous operation with hydrogen and air at 150-160oC, with a fuel cell performance degradation rate of 5-10 µV/h. Improvement of the membrane performance such as mechanical strength, swelling and oxidative stability has achieved by exploring the polymer chemistry, i.e. covalently...

  7. Catalyst Degradation in High Temperature Proton Exchange Membrane Fuel Cells Based on Acid Doped Polybenzimidazole Membranes

    DEFF Research Database (Denmark)

    Cleemann, Lars Nilausen; Buazar, F.; Li, Qingfeng;

    2013-01-01

    Degradation of carbon supported platinum catalysts is a major failure mode for the long term durability of high temperature proton exchange membrane fuel cells based on phosphoric acid doped polybenzimidazole membranes. With Vulcan carbon black as a reference, thermally treated carbon black...... and multi‐walled carbon nanotubes were used as supports for electrode catalysts and evaluated in accelerated durability tests under potential cycling at 150 °C. Measurements of open circuit voltage, area specific resistance and hydrogen permeation through the membrane were carried out, indicating little...... contribution of the membrane degradation to the performance losses during the potential cycling tests. As the major mechanism of the fuel cell performance degradation, the electrochemical active area of the cathodic catalysts showed a steady decrease in the cyclic voltammetric measurements, which was also...

  8. Development and characterization of acid-doped polybenzimidazole/sulfonated polysulfone blend polymer electrolytes for fuel cells

    DEFF Research Database (Denmark)

    Hasiotis, C.; Li, Qingfeng; Deimede, V.

    2001-01-01

    Polymeric membranes from blends of sulfonated polysulfones (SPSF) and polybenzimidazole (PBI) doped with phosphoric acid were developed as potential high-temperature polymer electrolytes for fuel cells and other electrochemical applications. The water uptake and acid doping of these polymeric...... it was found to be higher than 10/sup -2/ S cm/sup -1/. Much improvement in the mechanical strength is observed for the blend polymer membranes, especially at higher temperatures. Preliminary work has demonstrated the feasibility of these polymeric membranes for fuel-cell applications...

  9. Oxidative degradation of acid doped polybenzimidazole membranes and fuel cell durability in the presence of ferrous ions

    DEFF Research Database (Denmark)

    Liao, Jianhui; Yang, Jingshuai; Li, Qingfeng;

    2013-01-01

    . In this study effects of phosphoric acid and ferrous ions were investigated by measurements of the weight loss, intrinsic viscosity and size exclusion chromatography (SEC) of the polymer membranes. Ferrous ions resulted in, as expected, catalytic formation of peroxide radicals and hence the accelerated polymer......Phosphoric acid doped polybenzimidazole membranes have been explored as proton exchange membranes for high temperature polymer electrolyte membrane fuel cells. Long-term durability of the membrane is of critical concern and has been evaluated by accelerated degradation tests under Fenton conditions...... degradation in terms of weight loss and molecular weight decrease. The presence of phosphoric acid as an inevitable dopant of the membranes, on the other hand, significantly impeded the membrane degradation by means of metal ion complexing, decreased pH, and acid–base interactions with the amino groups...

  10. Dimensionally-stable phosphoric acid-doped polybenzimidazoles for high-temperature proton exchange membrane fuel cells

    Science.gov (United States)

    Li, Xiaobai; Ma, Hongwei; Shen, Yanchao; Hu, Wei; Jiang, Zhenhua; Liu, Baijun; Guiver, Michael D.

    2016-12-01

    Phosphoric acid-doped polybenzimidazole (PA-m-PBI) membranes are widely investigated for high temperature proton exchange membrane fuel cells because of their low cost and high performance. For this system, a major challenge is in achieving a good compromise between the phosphoric acid doping level and the membrane dimensional-mechanical stability. Different from the established PA-m-PBI system, the present work investigates two types of PA-PBI membranes incorporating flexible ether linkages and asymmetric bulky pendants (phenyl and methylphenyl), which exhibit much better dimensional-mechanical stability after immersing in PA solution, even at high temperature for an extended period. This superior stability allowed higher acid doping levels (20.6 and 24.6) to be achieved, thus increasing proton conductivity (165 and 217 mS cm-1 at 200 °C under anhydrous conditions) as well as significantly improving fuel cell performance. The peak power densities in hydrogen/air fuel cell were 279 and 320 mW cm-2 at 160 °C, without humidification. Molecular simulation, density and fractional free volume, and wide-angle X-ray diffraction were used to investigate their structure-property relationships.

  11. The effect of porosity on performance of phosphoric acid doped polybenzimidazole polymer electrolyte membrane fuel cell

    Directory of Open Access Journals (Sweden)

    Celik Muhammet

    2016-01-01

    Full Text Available A polybenzimidazole (PBI based polymer electrolyte fuel cells, which called high temperature polymer electrolyte fuel cells (HT-PEMS, operate at higher temperatures (120-200°C than conventional PEM fuel cells. Although it is known that HT-PEMS have some of the significant advantages as non-humidification requirements for membrane and the lack of liquid water at high temperature in the fuel cell, the generated water as a result of oxygen reduction reaction causes in the degradation of these systems. The generated water absorbed into membrane side interacts with the hydrophilic PBI matrix and it can cause swelling of membrane, so water transport mechanism in a membrane electrode assembly (MEA needs to be well understood and water balance must be calculated in MEA. Therefore, the water diffusion transport across the electrolyte should be determined. In this study, various porosity values of gas diffusion layers are considered in order to investigate the effects of porosity on the water management for two phase flow in fuel cell. Two-dimensional fuel cell with interdigitated flow-field is modelled using COMSOL Multiphysics 4.2a software. The operating temperature and doping level is selected as 160°C and 6.75mol H3PO4/PBI, respectively.

  12. The effect of porosity on performance of phosphoric acid doped polybenzimidazole polymer electrolyte membrane fuel cell

    Science.gov (United States)

    Celik, Muhammet; Genc, Gamze; Elden, Gulsah; Yapici, Huseyin

    2016-03-01

    A polybenzimidazole (PBI) based polymer electrolyte fuel cells, which called high temperature polymer electrolyte fuel cells (HT-PEMS), operate at higher temperatures (120-200°C) than conventional PEM fuel cells. Although it is known that HT-PEMS have some of the significant advantages as non-humidification requirements for membrane and the lack of liquid water at high temperature in the fuel cell, the generated water as a result of oxygen reduction reaction causes in the degradation of these systems. The generated water absorbed into membrane side interacts with the hydrophilic PBI matrix and it can cause swelling of membrane, so water transport mechanism in a membrane electrode assembly (MEA) needs to be well understood and water balance must be calculated in MEA. Therefore, the water diffusion transport across the electrolyte should be determined. In this study, various porosity values of gas diffusion layers are considered in order to investigate the effects of porosity on the water management for two phase flow in fuel cell. Two-dimensional fuel cell with interdigitated flow-field is modelled using COMSOL Multiphysics 4.2a software. The operating temperature and doping level is selected as 160°C and 6.75mol H3PO4/PBI, respectively.

  13. Proton conductivity of phosphoric acid doped polybenzimidazole and its composites with inorganic protontic conductors

    DEFF Research Database (Denmark)

    Li, Qingfeng

    2003-01-01

    contain inorganic protonic conductors including zirconium phosphate (ZrP), (Zr(HPO4)2. nH2O); phosphotungstic acid (PWA), (H3PW12O40. nH2O); and silicotungstic acid (SiWA), (H4SiW12O40 . nH2O). The conductivity of phosphoric acid doped PBI and PBI composite membranes was found to be dependent on the acid...

  14. Acid-doped Polybenzimidazole Membranes as Electrolyte for Fuel Cells Operating Above 100°C

    DEFF Research Database (Denmark)

    Qingfeng, Li; Jensen, Jens Oluf; He, Ronhuan

    2003-01-01

    The technical achievement and challenges for the PEMFC technology based on perfluorosulfonic acid (PFSA) polymer membranes (e.g. Nafion®) are briefly discussed. The newest development in the field is alternative polymer electrolytes for operation above 100°C. As one of the successful approaches...... to high operational temperatures, the development and evaluation of acid doped PBI membranes are reviewed, covering polymer synthesis, membrane casting, acid doping, physiochemical characterization and fuel cell tests. A high temperature PEMFC system operational at up to 200°C is demonstrated with no gas...... humidification and high CO-tolerance up to 10 vol%. This high CO tolerance allows for a direct use of reformed hydrogen without further CO removal, which opens the possibility for an integrated reformer-fuel cell system. The content of this review is to a large extent based on research performed by the authors...

  15. Thermal properties of phosphoric acid-doped polybenzimidazole membranes in water and methanol-water mixtures

    Energy Technology Data Exchange (ETDEWEB)

    Nores-Pondal, Federico J.; Corti, Horacio R. [Grupo de Pilas de Combustible, Departamento de Fisica de la Materia Condensada, Centro Atomico Constituyentes, Comision Nacional de Energia Atomica (CNEA), Av. General Paz 1499, B1650KNA San Martin, Buenos Aires (Argentina); Consejo Nacional de Investigaciones Cientificas y Tecnicas (Argentina); Buera, M. Pilar [Consejo Nacional de Investigaciones Cientificas y Tecnicas (Argentina); Departamento de Industrias, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Av. Cantilo s/n, Ciudad Universitaria (1428) Buenos Aires (Argentina)

    2010-10-01

    The thermal properties of phosphoric acid-doped poly[2-2'-(m-phenylene)-5-5' bi-benzimidazole] (PBI) and poly[2,5-benzimidazole] (ABPBI) membranes, ionomeric materials with promising properties to be used as electrolytes in direct methanol and in high temperature polymer electrolyte membrane (PEM) fuel cells, were studied by means of differential scanning calorimetry (DSC) technique in the temperature range from -145 C to 200 C. The DSC scans of samples equilibrated in water at different relative humidities (RH) and in liquid water-methanol mixtures were analyzed in relation to glass transition, water crystallization/melting and solvent desorption in different temperature regions. The thermal relaxation observed in the very low temperature region could be ascribed to the glass transition of the H{sub 3}PO{sub 4}-H{sub 2}O mixture confined in the polymeric matrix. After cooling the samples up to -145 C, frozen water was detected in PBI and ABPBI at different RH, although at 100% RH less amount of water had crystallized than that observed in Nafion membranes under the same conditions. Even more important is the fact that the freezing degree of water is much lower in ABPBI membranes equilibrated in liquid water-methanol mixtures than that observed for PBI and, in a previous study, for Nafion. Thus, apart from other well known properties, acid-doped ABPBI emerges as an excellent ionomer for applications in direct methanol fuel cells working in cold environments. (author)

  16. Performance Degradation Tests of Phosphoric Acid Doped Polybenzimidazole Membrane Based High Temperature Polymer Electrolyte Membrane Fuel Cells

    DEFF Research Database (Denmark)

    Zhou, Fan; Araya, Samuel Simon; Grigoras, Ionela

    2015-01-01

    Degradation tests of two phosphoric acid (PA) doped PBI membrane based HT-PEM fuel cells were reported in this paper to investigate the effects of start/stop and the presence of methanol in the fuel to the performance degradation of the HT-PEM fuel cell. Continuous tests with pure dry H2...... and methanol containing H2 which was composed of H2, steam and methanol as the fuel were performed on both single cells. After the continuous tests, 12-h-startup/12-h-shutdown dynamic tests were performed on the first single cell with H2 as the fuel and on the second single cell with methanol containing H2...... as the fuel. Along with the degradation tests, electrochemical techniques such as polarization curves and electrochemical impedance spectroscopy (EIS) were employed to study the degradation mechanisms of the fuel cells. The results of the tests showed that both single cells experienced an increase...

  17. Amino-Functional Polybenzimidazole Blends with Enhanced Phosphoric Acid Mediated Proton Conductivity as Fuel Cell Electrolytes

    DEFF Research Database (Denmark)

    Aili, David; Javakhishvili, Irakli; Han, Junyoung;

    2016-01-01

    A new amino-functional polybenzimidazole copolymer is synthesized by homogeneous solution condensation polymerization from a novel monomer, N,N′-bis (2,4-diaminophenyl)-1,3-diaminopropane. The copolymer readily dissolves in organic solvents and shows good film forming characteristics. To balance...... the phosphoric acid uptake and to obtain mechanically robust membranes, the amino-functional polybenzimidazole derivative is blended with high molecular weight poly [2,2′-(m-phenylene)-5,5′-bisbenzimidazole] at different ratios. Due to the high acid uptake, the homogenous blend membranes show enhanced proton...

  18. Cross-linked polybenzimidazole membranes for high temperature proton exchange membrane fuel cells with dichloromethyl phosphinic acid as a cross-linker

    DEFF Research Database (Denmark)

    Noye, Pernille; Li, Qingfeng; Pan, Chao;

    2008-01-01

    . The produced cross-linked membranes show increased mechanical strength, making it possible to achieve higher phosphoric acid doping levels and therefore higher proton conductivity. Oxidative stability is significantly improved and thermal stability is sufficient in a temperature range of up to 250 degrees C, i......Phosphoric acid doped polybenzimidazole (PBI) membranes have been covalently cross-linked with dichloromethyl phosphinic acid (DCMP). FT-IR measurements showed new bands originating from bonds between the hydrogen bearing nitrogen in the imidazole group of PBI and the CH2 group in DCMP...

  19. Heterogeneous anion conducting membranes based on linear and crosslinked KOH doped polybenzimidazole for alkaline water electrolysis

    DEFF Research Database (Denmark)

    Aili, David; Hansen, Martin Kalmar; Renzaho, Richard Fulgence

    2013-01-01

    polymer, however, with limitations with respect to hydrolytic stability. The gradual decay of the average molecular weight resulted in a severe deterioration of the mechanical properties over time. Membranes based on crosslinked polybenzimidazole showed better stability than the membranes based...

  20. Benzimidazole grafted polybenzimidazoles for proton exchange membrane fuel cells

    DEFF Research Database (Denmark)

    Yang, Jingshuai; Aili, David; Li, Qingfeng

    2013-01-01

    High molecular weight polybenzimidazole (PBI) was synthesized and grafted with benzimidazole pendant groups. The high molecular weight of PBI resulted in good film-forming properties and superior tensile strength. With a phosphoric acid doping level (ADL) of 13.1, a tensile strength of 16 MPa was...

  1. New Membranes Based on Polybenzimidazole for Polymer Fuel Cells

    Institute of Scientific and Technical Information of China (English)

    P.Mustarelli; E.Quartarone; S; Grandi; A.Carollo; S.Leonardi; A.Magistris

    2007-01-01

    1 Results Acid-doped polybenzimidazoles[1] are particularly appealing because of high proton conductivity with no or low humidification and promising fuel cells performances. PBI, in fact, contains basic functional groups which can easily interact with strong oxo-acids, such as H3PO4 and H2SO4. The acid partially protonates the polymer and partially is freely dispersed in the polymer backbone, so allowing proton migration via Grotthuss mechanism along the anionic chains[2]. Anyway, a technological limit...

  2. A novel amperometric sensor for peracetic acid based on a polybenzimidazole-modified gold electrode

    Energy Technology Data Exchange (ETDEWEB)

    Hua, Mu-Yi, E-mail: huamy@mail.cgu.edu.t [Green Research Center, Department of Chemical and Materials Engineering, Chang Gung University, 259 Wen-Hwa 1st Rd., Kuei-Shan, Tao-Yuan 33302, Taiwan (China); Biosensor Group, Biomedical Engineering Research Center, Chang Gung University, 259 Wen-Hwa 1st Rd., Kuei-Shan, Tao-Yuan 33302, Taiwan (China); Chen, Hsiao-Chien [Green Research Center, Department of Chemical and Materials Engineering, Chang Gung University, 259 Wen-Hwa 1st Rd., Kuei-Shan, Tao-Yuan 33302, Taiwan (China); Biosensor Group, Biomedical Engineering Research Center, Chang Gung University, 259 Wen-Hwa 1st Rd., Kuei-Shan, Tao-Yuan 33302, Taiwan (China); Tsai, Rung-Ywan [Electronics and Optoelectronics Research Laboratories, Industrial Technology Research Institute, 195, Sec. 4, Chung Hsing Rd., Hsinchu 31040, Taiwan (China); Lin, Yu-Chen [Green Research Center, Department of Chemical and Materials Engineering, Chang Gung University, 259 Wen-Hwa 1st Rd., Kuei-Shan, Tao-Yuan 33302, Taiwan (China); Biosensor Group, Biomedical Engineering Research Center, Chang Gung University, 259 Wen-Hwa 1st Rd., Kuei-Shan, Tao-Yuan 33302, Taiwan (China)

    2011-04-30

    We have developed a peracetic acid (PAA) sensor based on a polybenzimidazole-modified gold (PBI/Au) electrode. Fourier transform infrared and X-ray photoelectron spectroscopy indicated that PAA oxidized 69.4% of the imine in PBI to form PBI N-oxide, increasing the electrochemical reduction current during cyclic voltammetry. The chemical oxidation of the PBI/Au electrode by PAA, followed by its electrochemical reduction, allowed PAA to be detected directly and consecutively by assessing its reduction current. The PAA sensor had a broad linear detection range (3.1 {mu}M-1.5 mM) and a rapid response time (3.9 s) at an applied potential of -0.3 V. Potentially interfering substances, such as hydrogen peroxide, acetic acid, and oxygen, had no effect on the ability of the probe to detect PAA, indicating high selectivity of the probe. Furthermore, the detection range, response time, and sensitivity of the sensor could all be improved by modification of the smooth planar electrode surface to a porous three-dimensional configuration. When compared to the analytical characteristics of other PAA sensors operating under optimal conditions, the three-dimensional PBI/Au electrode offers a rapid detection time, a usable linear range, and a relatively low detection limit.

  3. Performance of a direct glycerol fuel cell using KOH doped polybenzimidazole as electrolyte

    Energy Technology Data Exchange (ETDEWEB)

    Nascimento, Ana P.; Linares, Jose J., E-mail: joselinares@unb.br [Universidade de Brasilia (UnB), Brasilia, DF (Brazil). Instituto de Quimica

    2014-03-15

    This paper studies the influence of the operating variables (glycerol concentration, temperature and feed rate) for a direct glycerol fuel cell fed with glycerol using polybenzimidazole (PBI) impregnated with KOH as electrolyte and Pt/C as catalyst. Temperature displays a beneficial effect up to 75 °C due to the enhanced conductivity and kinetics of the electrochemical reactions. The optimum cell feed corresponds to 1 mol L{sup -1} glycerol and 4 mol L{sup -1} KOH, supplying sufficient quantities of fuel and electrolyte without massive crossover nor mass transfer limitations. The feed rate increases the performance up to a limit of 2 mL min{sup -1}, high enough to guarantee the access of the glycerol and the exit of the products. Finally, the use of binary catalysts (PtRu/C and Pt{sub 3}Sn/C) is beneficial for increasing the cell performance. (author)

  4. Polybenzimidazole Membranes Containing Benzimidazole Side Groups for High Temprature Polymer Electrolyte Membrane Fuel Cells

    DEFF Research Database (Denmark)

    Yang, Jingshuai; Li, Xueyuan; Xu, Yizin

    2013-01-01

    Polybenzimidazole (PBI) with a high molecular weight of 69,000 was first synthesized. It was afterwards grafted with benzimidazole pendant groups on the backbones. The acid doped benzimidaozle grafted PBI membranes were investigated and characterized including fuel cell tests at elevated temperat......Polybenzimidazole (PBI) with a high molecular weight of 69,000 was first synthesized. It was afterwards grafted with benzimidazole pendant groups on the backbones. The acid doped benzimidaozle grafted PBI membranes were investigated and characterized including fuel cell tests at elevated...... temperatures without humidification. At an acid doping level of 13.1 mol H3PO4 per average molar repeat unit, the PBI membranes with a benzimidazole grafting degree of 10.6% demonstrated a conductivity of 0.15 S cm-1 and a H2-air fuel cell peak power density of 378 mW cm-2 at 180 oC at ambient pressure without...

  5. meta-PBI/methylated PBI-OO blend membranes for acid doped HT PEMFC

    DEFF Research Database (Denmark)

    Cho, Hyeongrae; Hur, Eun; Henkensmeier, Dirk

    2014-01-01

    Methylation of polybenzimidazole leads to positively charged polymer backbones, and moveable anions. Ion exchange of methylated PBI-OO in phosphoric acid (PA) shows that the resulting polymers dissolve. meta-PBI, however, absorbs about 400wt% PA while remaining a self supported membrane. We...... membranes of 60–63% is reached by doping in 60% PA (blend; 6.3PA/repeat unit) and 70% PA (meta-PBI; 4.6PA/r.u.). This suggests that blends absorb PA more strongly. Both membranes show similar conductivity between rt and 140°C, indicating that PA concentration describes these membranes better than PA...

  6. Phosphoric acid doped membranes based on Nafion®, PBI and their blends – Membrane preparation, characterization and steam electrolysis testing

    DEFF Research Database (Denmark)

    Aili, David; Hansen, Martin Kalmar; Pan, Chao;

    2011-01-01

    . An MEA based on phosphoric acid doped Nafion® was operated at 130 °C at ambient pressure with a current density of 300 mA cm−2 at 1.75 V, with no membrane degradation observed during a test of 90 h. The PBI based MEAs showed better polarization curves (500 mA cm−2 at 1.75 V) but poor durability.......® and polybenzimidazole blend membranes was developed. Homogeneous binary membranes covering the whole composition range were prepared and characterized with respect to chemical and physiochemical properties such as water uptake, phosphoric acid doping, oxidative stability, mechanical strength and proton conductivity...

  7. High Molecular Weight Polybenzimidazole Membranes for High Temperature PEMFC

    DEFF Research Database (Denmark)

    Yang, Jingshuai; Cleemann, Lars Nilausen; Steenberg, T.;

    2014-01-01

    High temperature operation of proton exchange membrane fuel cells under ambient pressure has been achieved by using phosphoric acid doped polybenzimidazole (PBI) membranes. To optimize the membrane and fuel cells, high performance polymers were synthesized of molecular weights from 30 to 94 k...... showed enhanced chemical stability towards radical attacks under the Fenton test, reduced volume swelling upon the acid doping and improved mechanical strength at acid doping levels of as high as about 11 mol H3PO4 per molar repeat polymer unit. The PBI‐78kDa/10.8PA membrane, for example, exhibited...... tensile strength of 30.3 MPa at room temperature or 7.3 MPa at 130 °C and a proton conductivity of 0.14 S cm–1 at 160 °C. Fuel cell tests with H2 and air at 160 °C showed high open circuit voltage, power density and a low degradation rate of 1.5 μV h–1 at a constant load of 300 mA cm–2....

  8. Ionic conducting poly-benzimidazoles; Polybenzimidazoles conducteurs ioniques

    Energy Technology Data Exchange (ETDEWEB)

    Jouanneau, J

    2006-11-15

    Over the last years, many research works have been focused on new clean energy systems. Hydrogen fuel cell seems to be the most promising one. However, the large scale development of this technology is still limited by some key elements. One of them is the polymer electrolyte membrane 'Nafion' currently used, for which the ratio performance/cost is too low. The investigations we carried out during this thesis work are related to a new class of ionic conducting polymer, the sulfonated poly-benzimidazoles (sPBI). Poly-benzimidazoles (PBI) are aromatic heterocyclic polymers well-known for their excellent thermal and chemical stability. Ionic conduction properties are obtained by having strong acid groups (sulfonic acid SO{sub 3}H) on the macromolecular structure. For that purpose, we first synthesized sulfonated monomers. Their poly-condensation with an appropriate non-sulfonated co-monomer yields to sPBI with sulfonation range from 0 to 100 per cent. Three different sPBI structures were obtained, and verified by appropriate analytical techniques. We also showed that the protocol used for the synthesis resulted in high molecular weights polymers. We prepared ionic conducting membrane by casting sPBI solutions on glass plates. Their properties of stability, water swelling and ionic conductivity were investigated. Surprisingly, the behaviour of sPBI was quite different from the other sulfonated aromatic polymers with same amount of SO{sub 3}H, their stability was much higher, but their water swelling and ionic conductivity were quite low. We attributed these differences to strong ionic interactions between the sulfonic acid groups and the basic benzimidazole groups of our polymers. However, we managed to solve this problem synthesizing very highly sulfonated PBI, obtaining membranes with a good balance between all the properties necessary. (author)

  9. POLYCAPROLACTAM MODIFIED BY POLYBENZIMIDAZOLE

    Institute of Scientific and Technical Information of China (English)

    YANG Guisheng; LU Fengcai

    1990-01-01

    Three polycaprolactam samples modified by 0.05 - 0.50% polybenzimidazole (PBI) by weight were prepared. Their structure and mechanical properties were characterized by means of FT- IR, SEM, DTA,density tensile,impact and viscoelastic method. PBI delayed the superimposed polymerization-crystallization process of the activated anionic polymerization of caprolactam. The monomer casting (MC) nylons modified by PBI had lower crystallinities,lower Tg and more nearly perfect spherulites than MCnylon itself, and showed a typical toughening effect.

  10. Oxidative degradation of polybenzimidazole membranes as electrolytes for high temperature proton exchange membrane fuel cells

    DEFF Research Database (Denmark)

    Liao, J.H.; Li, Qingfeng; Rudbeck, H.C.

    2011-01-01

    Polybenzimidazole membranes imbibed with acid are emerging as a suitable electrolyte material for high-temperature polymer electrolyte fuel cells. The oxidative stability of polybenzimidazole has been identified as an important issue for the long-term durability of such cells. In this paper...

  11. Oxidative degradation of polybenzimidazole membranes as electrolytes for high temperature proton exchange membrane fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Liao, J.H. [The State Key Laboratory of Electroanalytical Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, 5625 Renmin Street, Changchun, Jilin 130022 (China); Energy and Materials Science Group, Department of Chemistry, Kemitorvet 207, Technical University of Denmark, DK-2800 Kgs. Lyngby (Denmark); Li, Q.F.; Jensen, J.O.; Bjerrum, N.J. [Energy and Materials Science Group, Department of Chemistry, Kemitorvet 207, Technical University of Denmark, DK-2800 Kgs. Lyngby (Denmark); Rudbeck, H.C. [Danish Power Systems ApS, Raadhusvej 59, DK 2920 Charlottenlund (Denmark); Chromik, A.; Kerres, J. [Institute for Chemical Process Engineering, University of Stuttgart, D-70199 Stuttgart (Germany); Xing, W. [The State Key Laboratory of Electroanalytical Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, 5625 Renmin Street, Changchun, Jilin 130022 (China)

    2011-12-15

    Polybenzimidazole membranes imbibed with acid are emerging as a suitable electrolyte material for high-temperature polymer electrolyte fuel cells. The oxidative stability of polybenzimidazole has been identified as an important issue for the long-term durability of such cells. In this paper the oxidative degradation of the polymer membrane was studied under the Fenton test conditions by the weight loss, intrinsic viscosity, size exclusion chromatography, scanning electron microscopy and Fourier transform infrared spectroscopy. During the Fenton test, significant weight losses depending on the initial molecular weight of the polymer were observed. At the same time, viscosity and SEC measurements revealed a steady decrease in molecular weight. The degradation of acid doped PBI membranes under Fenton test conditions is proposed to start by the attack of hydroxyl radicals at the carbon atom linking imidazole ring and benzenoid ring, which may eventually lead to the imidazole ring opening and formation of small molecules and terminal groups for further oxidation by an endpoint oxidation. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  12. High temperature proton exchange membranes based on polybenzimidazoles for fuel cells

    DEFF Research Database (Denmark)

    Li, Qingfeng; Jensen, Jens Oluf; Savinell, Robert F

    2009-01-01

    To achieve high temperature operation of proton exchange membrane fuel cells (PEMFC), preferably under ambient pressure, acid–base polymer membranes represent an effective approach. The phosphoric acid-doped polybenzimidazole membrane seems so far the most successful system in the field. It has...... in recent years motivated extensive research activities with great progress. This treatise is devoted to updating the development, covering polymer synthesis, membrane casting, physicochemical characterizations and fuel cell technologies. To optimize the membrane properties, high molecular weight polymers...... with synthetically modified or N-substituted structures have been synthesized. Techniques for membrane casting from organic solutions and directly from acid solutions have been developed. Ionic and covalent cross-linking as well as inorganic–organic composites has been explored. Membrane characterizations...

  13. Durability of symmetrically and asymmetrically porous polybenzimidazole membranes for high temperature proton exchange membrane fuel cells

    Science.gov (United States)

    Jheng, Li-Cheng; Chang, Wesley Jen-Yang; Hsu, Steve Lien-Chung; Cheng, Po-Yang

    2016-08-01

    Two types of porous polybenzimidazole (PBI) membranes with symmetric and asymmetric morphologies were fabricated by the template-leaching method and characterized by scanning electron microscope (SEM). Their physicochemical properties were compared in terms of acid-doping level, proton conductivity, mechanical strength, and oxidative stability. The durability of fuel cell operation is one of the most challenging for the PBI based membrane electrode assembly (MEA) used in high-temperature proton exchange membrane fuel cells (HT-PEMFCs). In the present work, we carried out a long-term steady-state fuel cell test to compare the effect of membrane structure on the cell voltage degradation. It has also been demonstrated that the asymmetrically porous PBI could bring some notable improvements on the durability of fuel cell operation, the fuel crossover problem, and the phosphoric acid leakage.

  14. Precursor polymer compositions comprising polybenzimidazole

    Energy Technology Data Exchange (ETDEWEB)

    Klaehn, John R.; Peterson, Eric S.; Orme, Christopher J.

    2015-07-14

    Stable, high performance polymer compositions including polybenzimidazole (PBI) and a melamine-formaldehyde polymer, such as methylated, poly(melamine-co-formaldehyde), for forming structures such as films, fibers and bulky structures. The polymer compositions may be formed by combining polybenzimidazole with the melamine-formaldehyde polymer to form a precursor. The polybenzimidazole may be reacted and/or intertwined with the melamine-formaldehyde polymer to form the polymer composition. For example, a stable, free-standing film having a thickness of, for example, between about 5 .mu.m and about 30 .mu.m may be formed from the polymer composition. Such films may be used as gas separation membranes and may be submerged into water for extended periods without crazing and cracking. The polymer composition may also be used as a coating on substrates, such as metal and ceramics, or may be used for spinning fibers. Precursors for forming such polymer compositions are also disclosed.

  15. Why do proton conducting polybenzimidazole phosphoric acid membranes perform well in high-temperature PEM fuel cells?

    Science.gov (United States)

    Melchior, Jan-Patrick; Majer, Günter; Kreuer, Klaus-Dieter

    2016-12-21

    Transport properties and hydration behavior of phosphoric acid/(benz)imidazole mixtures are investigated by diverse NMR techniques, thermogravimetric analysis (TGA) and conductivity measurements. The monomeric systems can serve as models for phosphoric acid/poly-benzimidazole membranes which are known for their exceptional performance in high temperature PEM fuel cells. (1)H- and (31)P-NMR data show benzimidazole acting as a strong Brønsted base with respect to neat phosphoric acid. Since benzimidazole's nitrogens are fully protonated with a low rate for proton exchange with phosphate species, proton diffusion and conduction processes must take place within the hydrogen bond network of phosphoric acid only. The proton exchange dynamics between phosphate and benzimidazole species pass through the intermediate exchange regime (with respect to NMR line separations) with exchange times being close to typical diffusion times chosen in PFG-NMR diffusion measurements (ms regime). The resulting effects, as described by the Kärger equation, are included into the evaluation of PFG-NMR data for obtaining precise proton diffusion coefficients. The highly reduced proton diffusion coefficient within the phosphoric acid part of the model systems compared to neat phosphoric acid is suggested to be the immediate consequence of proton subtraction from phosphoric acid. This reduces hydrogen bond network frustration (imbalance of the number of proton donors and acceptors) and therefore also the rate of structural proton diffusion, phosphoric acid's acidity and hygroscopicity. Reduced water uptake, shown by TGA, goes along with reduced electroosmotic water drag which is suggested to be the reason for PBI-phosphoric acid membranes performing better in fuel cells than other phosphoric-acid-containing electrolytes with higher protonic conductivity.

  16. Synthesis and properties of random copolymers of functionalised polybenzimidazoles for high temperature fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Mader, J.A.; Benicewicz, B.C. [Department of Chemistry and Biochemistry and USC Nanocenter, University of South Carolina, 631 Sumter St., Columbia, SC 29208 (United States)

    2011-04-15

    A series of polybenzimidazoles (PBIs) incorporating main chain sulphonic acid groups were synthesised as random copolymers with p-PBI in varying ratios using polyphosphoric acid (PPA) as both the polymerisation solvent and polycondensation reagent. The PPA process was used to produce high molecular weight phosphoric acid (PA) doped PBI gel membranes in a one-step procedure. These membranes exhibit excellent mechanical properties (0.528-2.51 MPa tensile stress and 130-300% tensile strain) even at high acid doping levels [20-40 mol PA/PRU (polymer repeat unit)] and high conductivities (0.148-0.291 S cm{sup -1}) at elevated temperatures (>100 C) with no external humidification, depending on copolymer composition. Fuel cell testing was conducted with hydrogen fuel and air or oxygen oxidants for all membrane compositions at temperatures greater than 100 C without external feed gas humidification. Initial studies showed a maximum fuel performance of 0.675 V for the 25 mol% s-PBI/75 mol% p-PBI random copolymer at 180 C and 0.2 A cm{sup -2} with hydrogen and air, and 0.747 V for the same copolymer at 180 C and 0.2 A cm{sup -2} with hydrogen and oxygen. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  17. Acid-doped polymer nanofiber framework: Three-dimensional proton conductive network for high-performance fuel cells

    Science.gov (United States)

    Tanaka, Manabu; Takeda, Yasushi; Wakiya, Takeru; Wakamoto, Yuta; Harigaya, Kaori; Ito, Tatsunori; Tarao, Takashi; Kawakami, Hiroyoshi

    2017-02-01

    High-performance polymer electrolyte membranes (PEMs) with excellent proton conductivity, gas barrier property, and membrane stability are desired for future fuel cells. Here we report the development of PEMs based on our proposed new concept "Nanofiber Framework (NfF)." The NfF composite membranes composed of phytic acid-doped polybenzimidazole nanofibers (PBINf) and Nafion matrix show higher proton conductivity than the recast-Nafion membrane without nanofibers. A series of analyses reveal the formation of three-dimensional network nanostructures to conduct protons and water effectively through acid-condensed layers at the interface of PBINf and Nafion matrix. In addition, the NfF composite membrane achieves high gas barrier property and distinguished membrane stability. The fuel cell performance by the NfF composite membrane, which enables ultra-thin membranes with their thickness less than 5 μm, is superior to that by the recast-Nafion membrane, especially at low relative humidity. Such NfF-based high-performance PEM will be accomplished not only by the Nafion matrix used in this study but also by other polymer electrolyte matrices for future PEFCs.

  18. A Quaternary Polybenzimidazole Membrane for Intermediate Temperature Polymer Electrolyte Membrane Fuel Cells

    DEFF Research Database (Denmark)

    Xu, C.; Scott, K.; Li, Qingfeng

    2013-01-01

    A quaternary ammonium polybenzimidazole (QPBI) membrane was synthesized for applications in intermediate temperature (100–200 °C) hydrogen fuel cells. The QPBI membrane was imbibed with phosphoric acid to provide suitable proton conductivity. The proton conductivity of the membrane was 0.051 S cm–1...... at 150 °C with the PA acid loading level of 3.5 PRU (amount of H3PO4 per repeat unit of polymer QPBI). The QPBI membrane was characterized in terms of composition, structure and morphology by NMR, FTIR, SEM, and EDX. The fuel cell performance with the membrane gave peak power densities of 440 and 240 m...

  19. A polybenzimidazole/ionic-liquid-graphite-oxide composite membrane for high temperature polymer electrolyte membrane fuel cells

    Science.gov (United States)

    Xu, Chenxi; Liu, Xiaoteng; Cheng, Jigui; Scott, Keith

    2015-01-01

    Graphite oxide is successfully functionalised by 3-aminopropyltriethoxysilane ionic liquid and used as a filler material in a polybenzimidazole (PBI) membrane for high temperature proton exchange membrane fuel cells. The ionic-liquid-graphite-oxide/polybenzimidazole (ILGO/PBI) composite membrane exhibits an appropriate level of proton conductivity when imbibed with phosphoric acid at low phosphoric acid loading, which promotes its use in fuel cells by avoiding acid leakage and materials corrosion. The ionic conductivities of the ILGO/PBI membranes at 175 °C are 0.035 S cm-1 and 0.025 S cm-1 at per repeat units of 3.5 and 2.0, respectively. The fuel cell performance of ILGO/PBI membranes exhibits a maximum power density of 320 mW cm-2 at 175 °C, which is higher than that of a pristine PBI membrane.

  20. Vacuum thermal evaporation of polyaniline doped with camphor sulfonic acid

    Energy Technology Data Exchange (ETDEWEB)

    Boyne, Devon; Menegazzo, Nicola; Pupillo, Rachel C.; Rosenthal, Joel; Booksh, Karl S., E-mail: kbooksh@udel.edu [Department of Chemistry and Biochemistry, University of Delaware, Newark, Delaware 19716 (United States)

    2015-05-15

    Intrinsically conducting polymers belong to a class of organic polymers with intriguing electronic and physical properties specifically for electro-optical applications. Significant interest into doped polyaniline (PAni) can be attributed to its high conductivity and environmental stability. Poor dissolution in most solvents has thus far hindered the successful integration of PAni into commercial applications, which in turn, has led to the investigations of various deposition and acidic doping methods. Physical vapor deposition methods, including D.C. magnetron sputtering and vacuum thermal evaporation, have shown exceptional control over physical film properties (thickness and morphology). However, resulting films are less conductive than films deposited by conventional methods (i.e., spin and drop casting) due to interruption of the hyperconjugation of polymer chains. Specifically, vacuum thermal evaporation requires a postdoping process, which results in incorporation of impurities and oxidation of surface moieties. In this contribution, thermally evaporated films, sequentially doped by vacuum evaporation of an organic acid (camphorsulfonic acid, CSA) is explored. Spectroscopic evidence confirms the successful doping of PAni with CSA while physical characterization (atomic force microscopy) suggests films retain good morphology and are not damaged by the doping process. The procedure presented herein also combines other postpreparation methods in an attempt to improve conductivity and/or substrate adhesion.

  1. Long-term durability of HT-PEM fuel cells based on thermally cross-linked polybenzimidazole

    Science.gov (United States)

    Søndergaard, Tonny; Cleemann, Lars Nilausen; Becker, Hans; Aili, David; Steenberg, Thomas; Hjuler, Hans Aage; Seerup, Larisa; Li, Qingfeng; Jensen, Jens Oluf

    2017-02-01

    Long-term durability of high temperature polymer electrolyte membrane fuel cells based on thermally cross-linked polybenzimidazole membranes was studied and compared with reference membranes based on linear polybenzimidazole. The test was conducted at 160 °C under constant load currents of 200 mA cm-2 for periods of 1000, 4400, and 13,000 h. Extensive beginning-of-life (BoL) and end-of-test (EoT) characterisation was carried out, and disturbance of the steady state operated cells was minimised by limiting in-line diagnostics to the low-invasive technique of electrochemical impedance spectroscopy (EIS). Up until the operating time of 9200 h, the cell equipped with the cross-linked membrane showed an average degradation rate of 0.5 μV h-1, compared to 2.6 μV h-1 for the reference membrane, though parallel tests for a shorter period of time showed deviations, likely due to malfunctioning contact between layers or cell components. For the full test period of 13,000 h, the average voltage decay rate was about 1.4 and 4.6 μV h-1 for cells equipped with cross-linked and linear polybenzimidazole membranes, respectively. EIS and post-test analysis revealed that the cross-linked membrane showed better stability in terms of area specific resistance due to improved acid retention characteristics.

  2. Performance Evaluation of Polybenzimidazole for Potential Aerospace Applications

    NARCIS (Netherlands)

    Iqbal, H.M.S.

    2014-01-01

    With the increasing use of polymer based composite materials, there is an increasing demand of polymeric resins with high glass transition temperature, high thermal stability and excellent mechanical properties at high temperature. Polybenzimidazole (PBI) is a recently emerged high performance polym

  3. Multicolored Polyanilines Doped by Different Acid Dyes and Their Electrochromic Property

    Directory of Open Access Journals (Sweden)

    Li Xin

    2016-01-01

    Full Text Available Multicolored polyanilines (PANIs are synthesized by using different acid dyes containing sulfonic acid group as the functional dopant. It is found that the FTIR spectra of the acid dye doped PANI and pure PANI are similar with each other, which are all doped state PANI, and the new arising peaks indicate the acid dyes existing in the PANI molecular. The UV-Visible spectra show that the different acid dye doped PANI present different colors as the effect of the chromophore of the acid dye. From the CV curves, it is clear that all the acid dye doped PANIs exist two pairs of oxidation and reduction peaks with vivid reversibly multicolor changes from light color (-0.5~0V to dark color (0~0.8V. It is shown that acid dye doping is an effective method to broaden the color change range of the electrochromic mateials.

  4. Iontophoresis of Salicylic Acid From Salicylic Acid Doped Poly(p-phynylene vinylene)/ Polyacrylamide Hydrogels

    Science.gov (United States)

    Niamlang, Sumonman

    2009-03-01

    The apparent diffusion coefficients, Dapp, and the release mechanisms of salicylic acid from salicylic acid-loaded polyacrylamide hydrogels, SA-loaded PAAM, and salicylic acid-doped poly(phenylene vinylene)/polyacrylamide hydrogels, SA-doped PPV/PAAM, were investigated. In the absence of an electric field, the diffusion of SA from the SA-doped PPV/PAAM hydrogel is delayed in the first 3 hr due to the ionic interaction between the anionic drug and PPV. Beyond this period, SA can diffuse continuously into the buffer solution through the PAAM matrix. Dapp of SA-doped PPV/PAAM is higher than that of the SA-loaded PAAM, and the former increases with increasing electric field strength due to the combined mechanisms: the expansion of PPV chains inside the hydrogel; iontophoresis; and the electroporation of the matrix pore. Thus, the presence of the conductive polymer and the applied electric field can be combined to control the drug release rate at an optimal desired level.

  5. Charge transport in conducting polyaniline co-doped with sulfosalicylic acid and dodecylbenzoyl sulfonic acid

    Institute of Scientific and Technical Information of China (English)

    MA Li; YAN Jun; GAN Meng-Yu; HE Ling; LI Jian-Feng

    2009-01-01

    We prepared conducting polyaniline (PAn) co-doped with sulfosalicylic acid (SSA) and dodecylbenzoyl sulfonic acid (DBSA) in micro-emulsive polymerization, and studied its charge transport behaviors based on the measurement of its electrical conductivity in the temperature range between 203 K and 298 K. The conductivity was found to increase with temperature, similar to the case in semiconductors. Analyzing the experimental data with three models, namely the charge-energy-limited-tunneling model, Kivelson model and the three-dimensional variable range hopping (3D-VRH) model demonstrated that these models all describe well the charge transport behaviors of PAn co-doped with SSA and DBSA within the mentioned temperature range. From calculation with the 3D-VRH model, the hopping distance of the conducting PAn is obviously larger than its localization length. The PAn doped with SSA and DBSA enjoys desirable crystallinity due to the co-doping of two functional sulfonic acids. The macroscopic conductivity may correspond to three-dimensional transport in the network of the bundles, and the metallic islands may be attributed to quasi-one-dimensional bundles.

  6. Scale-up of a high temperature polymer electrolyte membrane fuel cell based on polybenzimidazole

    Science.gov (United States)

    Pinar, F. Javier; Cañizares, Pablo; Rodrigo, Manuel A.; Úbeda, Diego; Lobato, Justo

    A high temperature PEM fuel cell stack with a total active area 150 cm 2 has been studied. The PEM technology is based on a polybenzimidazole (PBI) membrane. Cast from a PBI polymer synthesised in our lab, the performance of a three-cell stack was analysed in static and dynamic modes. In static mode, operating at high constant oxygen flow rate (QO2 > 1105 ml O2 / min) produces a small decrease on the stack performance. High constant oxygen stoichiometry (λO2 > 3) does not produce a decrease on the performance of the stack. There are not differences between operating at constant flow rate of oxygen and constant stoichiometry of oxygen in the stack performance. The effect of operating at high temperature with a pressurization system and operating at higher temperatures are beneficial since the performance of the fuel cell is enhanced. A large shut-down stage produces important performance losses due to the loss of catalyst activity and the loss of membrane conductivity. After 150 h of operation at 0.2 A cm -2, it is observed a very high voltage drop. The phosphoric acid leached from the stack was also evaluated and did not exceed 2% (w/w). This fact suggests that the main degradation mechanism of a fuel cell stack based on polybenzimidazole is not the electrolyte loss. In dynamic test mode, it was observed a rapid response of power and current output even at the lower step-time (10 s). In the static mode at 125 °C and 1 atm, the stack reached a power density peak of 0.29 W cm -2 (43.5 W) at 1 V.

  7. Growth and characterization of KDP crystals doped with L-aspartic acid

    Science.gov (United States)

    Krishnamurthy, R.; Rajasekaran, R.; Samuel, Bincy Susan

    2013-03-01

    Potassium Dihydrogen Phosphate (KDP) doped with L-aspartic acid has been grown by solvent slow evaporation technique from a mixture of aqueous solution of KDP and 0.7% of L-aspartic acid at room temperature. The grown crystals were characterized by powder X-ray diffraction, UV-visible, FTIR analysis. The doping of aspartic acid was confirmed by FTIR spectrum. The Nonlinear optical property (SHG) of L-aspartic acid doped KDP has been confirmed. Microhardness studies were carried out on the grown crystal.

  8. Highly efficient sulfonated polybenzimidazole as a proton exchange membrane for microbial fuel cells

    Science.gov (United States)

    Singha, Shuvra; Jana, Tushar; Modestra, J. Annie; Naresh Kumar, A.; Mohan, S. Venkata

    2016-06-01

    Although microbial fuel cells (MFCs) represent a promising bio-energy technology with a dual advantage (i.e., electricity production and waste-water treatment), their low power densities and high installation costs are major impediments. To address these bottlenecks and replace highly expensive Nafion, which is a proton exchange membrane (PEM), the current study focuses for the first time on membranes made from an easily synthesizable and more economical oxy-polybenzimidazole (OPBI) and its sulfonated analogue (S-OPBI) as alternate PEMs in single-chambered MFCs. The S-OPBI membrane exhibits better properties, with high water uptake, ion exchange capacity (IEC) and proton conductivity and a comparatively smaller degree of swelling compared to Nafion. The membrane morphology is characterized by atomic force microscopy, and the bright and dark regions of the S-OPBI membrane reveals the formation of ionic domains in the matrix, forming continuous water nanochannels when doped with water. These water-filled nanochannels are responsible for faster proton conduction in S-OPBI than in Nafion; therefore, the power output in the MFC with S-OPBI as the PEM is higher than in other MFCs. The open circuit voltage (460 mV), current generation (2.27 mA) and power density profile (110 mW/m2) as a function of time, as well as the polarization curves, exhibits higher current and power density (87.8 mW/m2) with S-OPBI compared to Nafion as the PEM.

  9. Porous poly(benzimidazole) membrane for all vanadium redox flow battery

    Science.gov (United States)

    Luo, Tao; David, Oana; Gendel, Youri; Wessling, Matthias

    2016-04-01

    Porous poly(benzimidazole) (PBI) membranes of low vanadium ions permeability are described for an all vanadium redox flow battery (VRFB). The PBI membrane was prepared by a water vapour induced phase inversion process of a PBI polymer solution. The membrane has a symmetrical cross-sectional morphology. A low water permeability of 16.5 L (m2 h bar)-1 indicates the high hydraulic resistance stemming from a closed cell morphology with nanoporous characteristics. The PBI membrane doped with 2.5 M H2SO4 shows a proton conductivity of 16.6 mS cm-1 and VO2+ permeability as low as 4.5 × 10-8 cm2 min-1. The stability test of dense PBI membrane in VO2+ solution indicates good chemical stability. An all vanadium redox flow battery (VRFB) operated with the porous PBI membrane shows 98% coulombic efficiency and more than 10% higher energy efficiency compared to VRFB operated with Nafion 112 at applied current densities of 20-40 mA cm-2. High in situ stability of the porous PBI membrane was confirmed by about 50 cycles of continuous charge and discharge operation of the battery.

  10. Doping optimization of polypyrrole with toluenesulfonic acid using Box-Behnken design

    Science.gov (United States)

    Syed Draman, Sarifah Fauziah; Daik, Rusli; El-Sheikh, Said M.; Latif, Famiza Abdul

    2013-11-01

    A three-level Box-Behnken design was employed in doping optimization of polypyrrole with toluenesulfonic acid (TSA-doped PPy). The material was synthesized via chemical oxidative polymerization using pyrrole, toluenesulfonic acid (TSA) and ammonium persulfate (APS) as monomer, dopant and oxidant, respectively. The critical factors selected for this study were concentration of dopant, molar ratio between dopant to monomer (pyrrole) and concentration of oxidant. Obtaining adequate doping level of TSA-doped PPy is crucial because it affects the charge carriers for doped PPy and usually be responsible for electronic mobility along polymeric chain. Furthermore, the doping level also affects other properties such as electrical and thermal conductivity. Doping level was calculated using elemental analysis. SEM images shows that the prepared TSA-doped PPy particles are spherical in shape with the diameters of about. The range of nanoparticles size is around 80-100 nm. The statistical analysis based on a Box-Behnken design showed that 0.01 mol of TSA, 1:1 mole ratio TSA to pyrrole and 0.25 M APS were the optimum conditions for sufficient doping level.

  11. Doping optimization of polypyrrole with toluenesulfonic acid using Box-Behnken design

    Energy Technology Data Exchange (ETDEWEB)

    Syed Draman, Sarifah Fauziah; Daik, Rusli [School of Chemical Sciences and Food Technology, Faculty of Science and Technology, Universiti Kebangsaan Malaysia, 43600 Bangi, Selangor (Malaysia); El-Sheikh, Said M. [Nanostructured Materials and Nanotechnology Division, Central Metallurgical Research and Development Institute,11421 Cairo (Egypt); Latif, Famiza Abdul [Faculty of Applied Sciences, Universiti Teknologi MARA Malaysia 40450 Shah Alam, Selangor (Malaysia)

    2013-11-27

    A three-level Box-Behnken design was employed in doping optimization of polypyrrole with toluenesulfonic acid (TSA-doped PPy). The material was synthesized via chemical oxidative polymerization using pyrrole, toluenesulfonic acid (TSA) and ammonium persulfate (APS) as monomer, dopant and oxidant, respectively. The critical factors selected for this study were concentration of dopant, molar ratio between dopant to monomer (pyrrole) and concentration of oxidant. Obtaining adequate doping level of TSA-doped PPy is crucial because it affects the charge carriers for doped PPy and usually be responsible for electronic mobility along polymeric chain. Furthermore, the doping level also affects other properties such as electrical and thermal conductivity. Doping level was calculated using elemental analysis. SEM images shows that the prepared TSA-doped PPy particles are spherical in shape with the diameters of about. The range of nanoparticles size is around 80-100 nm. The statistical analysis based on a Box–Behnken design showed that 0.01 mol of TSA, 1:1 mole ratio TSA to pyrrole and 0.25 M APS were the optimum conditions for sufficient doping level.

  12. Synthesis, Characterization, and Thermal and Proton Conductivity Evaluation of 2,5-Polybenzimidazole Composite Membranes

    Directory of Open Access Journals (Sweden)

    Jin-Woo Lee

    2014-01-01

    Full Text Available In this contribution, composite membranes (CM-D and CM-S of 2,5-polybenzimidazole (PBI were synthesized by adding inorganic heteropoly acids (IHA-D and IHA-S. IHA-D and IHA-S were synthesized by condensation reaction of silicotungstic acid with tetraethyl orthosilicate (TEOS in the absence and presence of mesoporous silica (SiO2, respectively. The synthesized composites were structurally and morphologically characterized and further investigated the functional relationships between the materials structure and proton conductivity. The proton conductivity as well as thermal stability was found to be higher for composite membranes which suggest that both properties are highly contingent on mesoporous silica. The composite membrane with mesoporous silica shows high thermal properties and proton conductivity. IHA-D shows proton conductivity of almost 1.48×10-1 Scm−1 while IHA-S exhibited 2.06×10-1 Scm−1 in nonhumidity imposing condition (150°C which is higher than pure PBI. Thus introduction of inorganic heteropoly acid to PBI is functionally preferable as it results in increase of ion conductivity of PBI and can be better candidates for high temperature PEMFC.

  13. Exceptionally crystalline and conducting acid doped polyaniline films by level surface assisted solution casting approach

    Science.gov (United States)

    Puthirath, Anand B.; Methattel Raman, Shijeesh; Varma, Sreekanth J.; Jayalekshmi, S.

    2016-04-01

    Emeraldine salt form of polyaniline (PANI) was synthesized by chemical oxidative polymerisation method using ammonium persulfate as oxidant. Resultant emeraldine salt form of PANI was dedoped using ammonia solution and then re-doped with camphor sulphonic acid (CSA), naphthaline sulphonic acid (NSA), hydrochloric acid (HCl), and m-cresol. Thin films of these doped PANI samples were deposited on glass substrates using solution casting method with m-cresol as solvent. A level surface was employed to get homogeneous thin films of uniform thickness. Detailed X-ray diffraction studies have shown that the films are exceptionally crystalline. The crystalline peaks observed in the XRD spectra can be indexed to simple monoclinic structure. FTIR and Raman spectroscopy studies provide convincing explanation for the exceptional crystallinity observed in these polymer films. FESEM and AFM images give better details of surface morphology of doped PANI films. The DC electrical conductivity of the samples was measured using four point probe technique. It is seen that the samples also exhibit quite high DC electrical conductivity, about 287 S/cm for CSA doped PANI, 67 S/cm for NSA doped PANI 65 S/cm for HCl doped PANI, and just below 1 S/cm for m-cresol doped PANI. Effect of using the level surface for solution casting is studied and correlated with the observed crystallinity.

  14. Invited: A Stability Study of Alkali Doped PBI Membranes for Alkaline Electrolyzer Cells

    DEFF Research Database (Denmark)

    Jensen, Jens Oluf; Aili, David; Hansen, Martin Kalmar;

    2014-01-01

    Alkaline fuel cells and electrolyzers are attracting increasing interest. This is to a large extent due to the broad selection of catalyst materials not based on resource limited and expensive noble metals. The first fuel cells in practical use were Francis Thomas Bacon’s based on an alkaline...... or a porous diaphragm is used instead in direct contact with both electrodes (zero gap). In proton exchange membrane (PEM) electrolyzers proton conducting membranes like in PEM fuel cells have been very successful, but for the equivalent anion exchange membranes a similar conductivity has not yet been...... demonstrated; in contrast it is typically about an order of magnitude lower, which is insufficient [1]. The aromatic fluorine free polymer polybenzimidazole (PBI) has been very successful as a high temperature fuel cell membrane when doped with phosphoric acid [2] and it has been shown by Xing and Savadogo [3...

  15. Molecular modeling of protonic acid doping of emeraldine base polyaniline for chemical sensors

    NARCIS (Netherlands)

    Chen, X.; Yuan, C.A.; Wong, C.K.Y.; Ye, H.; Leung, S.Y.Y.; Zhang, G.

    2012-01-01

    We proposed a molecular modeling methodology to study the protonic acid doping of emeraldine base polyaniline which can used in gas detection. The commercial forcefield COMPASS was used for the polymer and protonic acid molecules. The molecular model, which is capable of representing the polyaniline

  16. Photoelectrocatalytic degradation of benzoic acid using Au doped TiO2 thin films.

    Science.gov (United States)

    Mohite, V S; Mahadik, M A; Kumbhar, S S; Hunge, Y M; Kim, J H; Moholkar, A V; Rajpure, K Y; Bhosale, C H

    2015-01-01

    Highly transparent pure and Au doped TiO2 thin films are successfully deposited by using simple chemical spray pyrolysis technique. The effect of Au doping onto the structural and physicochemical properties has been investigated. The PEC study shows that, both short circuit current (Isc) and open circuit voltage (Voc) are (Isc=1.81mA and Voc=890mV) relatively higher at 3at.% Au doping percentage. XRD study shows that the films are nanocrystalline in nature with tetragonal crystal structure. FESEM images show that the film surface covered with a smooth, uniform, compact and rice shaped nanoparticles. The Au doped thin films exhibit indirect band gap, decreases from 3.23 to 3.09eV with increase in Au doping. The chemical composition and valence states of pure and Au doped TiO2 films are studied by using X-ray photoelectron spectroscopy. The photocatalytic degradation effect is 49% higher in case 3at.% Au doped TiO2 than the pure TiO2 thin film photoelectrodes in the degradation of benzoic acid. It is revealed that Au doped TiO2 can be reused for five cycles of experiments without a requirement of post-treatment while the degradation efficiency was retained.

  17. Spatially electrodeposited platinum in polyaniline doped with poly(styrene sulfonic acid) for methanol oxidation

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Li-Ming; Tang, Wang-Rung; Wen, Ten-Chin [Department of Chemical Engineering, National Cheng Kung University, Tainan 70101 (Taiwan)

    2007-02-10

    Polyaniline (PANI) can be doped with poly(styrene sulfonic acid) (PSS) via doping-dedoping-redoping process. The specific characteristics of PANI doped with PSS (PANI-PSS) were checked by UV-vis spectroscopy, cyclic voltammetry, scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). PANI-PSS was found to have spatial structure with minimum degradation products. Platinum can be potentiostatically deposited in a spatial layer of the PANI-PSS as evidenced by electron dispersive element analysis (EDS) and Auger electron spectroscopy (AES). The electrochemical measurements demonstrated that PANI-PSS-Pt exhibited a much higher electrocatalytic activity for methanol oxidation than PANI-Pt. (author)

  18. Studies on biphenyl disulphonic acid doped polyanilines: Synthesis, characterization and electrochemistry

    Indian Academy of Sciences (India)

    Chepuri R K Rao; R Muthukannan; M Vijayan

    2012-06-01

    In this article, we report on the results obtained for the efforts we made to bring processability to the conducting polyaniline and substituted polyanilines by designing and synthesizing a new disulphonic acid with a biphenyl moiety as spacer group, viz. 4,4'-biphenyldisulphonic acid (BPSA). When doped, the disulphonic acid acts as a spacer group between the polyaniline chains and facilitates increase in solubility and conductivity. The spacing effect is maximized when BPSA is used as doping agent in in situ polymerization reactions. The conductivity of polyaniline doped by BPSA is 4 S/cm and for the substituted polyanilines it ranged from 2 × 10-5 to 8 × 10-4 S/cm.

  19. Electrochemical characteristics of dodecylbenzene sulfonic acid-doped polyaniline in aqueous solutions

    Energy Technology Data Exchange (ETDEWEB)

    Choi, B.Y. [Korea Electr. Power Res. Inst., Taejon (Korea, Republic of). Power Utilization Group; Chung, I.J. [Department of Chemical Engineering, Korea Advanced Institute of Science and Technology, 373-1 Kusong Yusong, Taejon 305-701 (Korea, Republic of); Chun, J.H.; Ko, J.M. [Department of Industrial Chemistry, Taejon National University of Technology, 305-3, Samsung-2 dong, Dong-gu, Taejon 300-717 (Korea, Republic of)

    1999-02-26

    The electrochemical characteristics of the polyaniline (PAn) films doped with dodecylbenzene sulfonic acid (DBSA) were investigated in aqueous solutions by means of cyclic voltammetry. The PAn-DBSAs film showed a good electrochemical activity in a weak acid solution as well as in a strong acid solution due to the incorporation of small cation instead of DBSA trapped in the film for charge neutralization of polymer matrix. (orig.) 39 refs.

  20. Effect of NaCl and KCl doping on the growth of sulphamic acid crystals

    Science.gov (United States)

    Thaila, T.; Kumararaman, S.

    2011-11-01

    The nonlinear optical single crystals of doped sulphamic acid (SA) were grown from aqueous solution by doping with NaCl and KCl using slow evaporation method. Powder X-ray diffraction studies confirm that the grown crystals belong to orthorhombic system. The density and melting point measurements of the grown crystals were determined by floatation technique and capillary tube method, respectively. The range of optical transmittance was ascertained by recording the UV-Vis-NIR spectrum. Atomic absorption study reveals the presence of dopants in the doped crystals. The thermal analyses indicated that the doped SA crystals are more stable than pure crystals. The Vicker's microhardness studies revealed that the dopants increased the hardness of the crystals. SHG efficiency studies of the crystals are found to be increased in the presence of NaCl and KCl dopants.

  1. Hydroxyl pyridine containing polybenzimidazole membranes for proton exchange membrane fuel cells

    DEFF Research Database (Denmark)

    Yang, Jingshuai; Xu, Yixin; Zhou, Lu;

    2013-01-01

    -phenylene)-5,5'-bibenzimidazole] (mPBI) according to the TGA data. The hydroxyl pyridine groups in the OHPyPBI structure resulted in high proton conductivities of the phosphoric acid doped OHPyPBI membranes. This is because the hydroxyl pyridine groups not only increased the acid doping level of the membranes......, but also benefited the proton conduction, which was proved by the results of acid conductivities of the membranes with comparable acid doping levels. At an acid doping level of 8.6, i.e. 8.6mol acids per molar repeat unit of the polymer, the OHPyPBI membrane exhibited a proton conductivity of 0.102Scm-1...... at 180°C without humidifying. In addition, an improved tensile modulus at elevated temperatures was observed for acid doped OHPyPBI membranes. Fuel cell tests demonstrated the technical feasibility of acid doped OHPyPBI membranes for high temperature proton exchange membrane fuel cells. © 2013 Elsevier B.V....

  2. Sterically Stabilized Poly(3,4-ethylenedioxythiophene) Colloidal Dispersions Doped with Different Sulfonic Acids

    Institute of Scientific and Technical Information of China (English)

    Tie Jun WANG; Ping CHEN; Xiu Jie HU; Shu Yun ZHOU

    2006-01-01

    The preparation of sterically stabilized poly(3, 4-ethylenedioxythiophene)(PEDOT)colloidal dispersions doped with different sulfonic acids is described. Three different sulfonic acids, i.e., p-toluenesulfonic acid, β-naphthalenesuffonic acid and D-camphor-10-sulfonic acid are used, facilitating the preparation of sterically stable PEDOT colloidal particles. The influences of the dopants and concentration of polymeric stabilizer on the yields, morphologies and electrical properties of the resultant colloidal particles were investigated. The colloidal particles with the size ranging from 172 to 334 nm have been obtained in good yields. The compressed pellet conductivity was as high as 4.5 Scm-1.

  3. New Polymer Electrolyte Membranes Based on Acid Doped PBI For Fuel Cells Operating above 100°C

    DEFF Research Database (Denmark)

    Li, Qingfeng

    2003-01-01

    The technical achievement and challenges for the PEMFC technology based on perfluorosulfonic acid (PFSA) polymer membranes (e.g. Nafion®) are briefly discussed. The newest development for alternative polymer electrolytes for operation above 100°C. As one of the successful approaches to high...... operational temperatures, the development and evaluation of acid doped PBI membranes are reviewed, covering polymer synthesis, membrane casting, acid doping, physiochemical characterization and fuel cell tests....

  4. Mechanism of proton transport in ionic-liquid-doped perfluorosulfonic acid membranes.

    Science.gov (United States)

    Kumar, Milan; Venkatnathan, Arun

    2013-11-21

    Ionic-liquid-doped perfluorosulfonic acid membranes (PFSA) are promising electrolytes for intermediate/high-temperature fuel cell applications. In the present study, we examine proton-transport pathways in a triethylammonium-triflate (TEATF) ionic liquid (IL)-doped Nafion membrane using quantum chemistry calculations. The IL-doped membrane matrix contains triflic acid (TFA), triflate anions (TFA(-)), triethylamine (TEA), and triethylammonium cations (TEAH(+)). Results show that proton abstraction from the sulfonic acid end groups in the membrane by TFA(-) facilitates TEAH(+) interaction with the side-chains. In the IL-doped PFSA membrane matrix, proton transfer from TFA to TEA and TFA to TFA(-) occurs. However, proton transfer from a tertiary amine cation (TEAH(+)) to a tertiary amine (TEA) does not occur without an interaction with an anion (TFA(-)). An anion interaction with the amine increases its basicity, and as a consequence, it takes a proton from a cation either instantly (if the cation is freely moving) or with a small activation energy barrier of 2.62 kcal/mol (if the cation is interacting with another anion). The quantum chemistry calculations predict that anions are responsible for proton-exchange between cations and neutral molecules of a tertiary amine. Results from this study can assist the experimental choice of IL to provide enhanced proton conduction in PFSA membrane environments.

  5. Effect of magnetic field on property and structure of polyaniline doped with multiple sulfonic acids

    Institute of Scientific and Technical Information of China (English)

    MA Li; HUANG Ke-long; CHEN Chao; GAN Meng-yu; LU Wei; CHEN Feng-qiang

    2008-01-01

    Polyaniline(PAn) doped with multiple sulfonic acid system of dodecylbenzenesulfonic acid(DBSA) and sulfosalicylic acid(SSA) was synthesized by emulsion polymerization using ammonium persulfate(APS) as an oxidizing agent in the presence and the absence of a constant magnetic field(MF)of 0.8 T. The structure and properties of the PAn were characterized by X-ray diffractometer(XRD), thermogravimetric apparatus(TGA), FT-IR spectroscope(FT-IR) and four probe digital multimeter. The results indicate that, when the molar ratio of DBSA to SSA is 1/3, that of dopant to An is 3/2, that of APS to An is 4/5 in the synthesizing media, and the doping time is 3 h, the conductivity of the PAn synthesized in the presence of the MF of 0.8 T reaches 5.88 S/cm,which is higher than that of the PAn synthesized in the absence of the MF. The thermal stability, the crystallinity and the doping degree of the PAn synthesized in the presence of the MF are also improved. MF not only enhances the conductivity, but also reduces the doping time, the dosage of the dopant and the oxidizing agent when the conductivity reaches the maximum.

  6. High temperature proton exchange membranes based on polybenzimidazole and clay composites for fuel cells

    DEFF Research Database (Denmark)

    Plackett, David; Siu, Ana; Li, Qingfeng

    2011-01-01

    dispersion of modified laponite clay was achieved in polybenzimidazole (PBI) solutions which, when cast and allowed to dry, resulted in homogeneous and transparent composite membranes containing up to 20 wt% clay in the polymer. The clay was organically modified using a series of ammonium...

  7. The Research on the Stability of TiO2,MoO3,PEO Doped Four-member Tungstic Acid Sols

    Institute of Scientific and Technical Information of China (English)

    Kai RAO; Xiang Kai FU; Xiao Ping RAO

    2004-01-01

    The TiO2, MoO3, PEO doped four-member tungstic acid sols were prepared for the first time.The stability of different doped content sols were investigated and optimized with rotational viscometer.The four-member doped tungstic acid sol was very stable which could be stored more than two months at room temperature.The WO3 electrochromic film prepared from this doped four- member tungstic acid sol had excellent performance and longevity of service.

  8. Poly (acrylic acid)-capped lanthanide-doped BaFCl nanocrystals: synthesis and optical properties.

    Science.gov (United States)

    Ju, Qiang; Luo, Wenqin; Liu, Yongsheng; Zhu, Haomiao; Li, Renfu; Chen, Xueyuan

    2010-07-01

    Water-soluble lanthanide-doped BaFCl nanophosphors with the surface functionalized by a layer of poly (acrylic acid) are synthesized via a facile one-step solvothermal method. Intense long-lived luminescence is realized from visible to near-infrared (NIR) by doping with different lanthanide ions. The emission and excitation spectra of Eu(3+) indicate that the doped lanthanide ions occupy a site close to the surface of the nanoparticles. Strong NIR emissions of Nd(3+) and green luminescence of Tb(3+) using Ce(3+) as sensitizers are also achieved in BaFCl nanoparticles. The synthesized nanoparticles featuring long-lived luminescence in either visible or NIR regions may have potential applications as luminescent labels for biological applications.

  9. Structural, optical, thermal, mechanical and dielectric studies of Sulfamic acid single crystals: An influence of dysprosium (Dy3+) doping

    Science.gov (United States)

    Singh, Budhendra; Shkir, Mohd.; AlFaify, S.; Kaushal, Ajay; Nasani, Narendar; Bdikin, Igor; Shoukry, H.; Yahia, I. S.; Algarni, H.

    2016-09-01

    Sulfamic acid is a potential material that exhibits excellent optical properties. A good quality, pure and dysprosium (Dy3+) doped (2.5 and 5 mol %) Sulfamic acid (SA) single crystals were grown successfully by slow cooling method. Structural study revealed a slight change in its lattice parameters and volume, suggesting the successful incorporation of Dy3+ in crystal system. The existence of dysprosium in the system was also confirmed. Presence of various vibrational modes was confirmed. Optical transparency was found to have a significant effect with variation in the doping concentration. Furthermore, a marked enhancement in its mechanical parameters with doping was also identified by nanoindentation technique. Etching study was also performed on the grown crystals to study the etch-pit formation and growth mechanism. Effect of doping on the thermal stability was analysed. All the results were compared and discussed in detail to get insight of the effect of doping concentration on Sulfamic acid crystal.

  10. 3D Polyaniline Architecture by Concurrent Inorganic and Organic Acid Doping for Superior and Robust High Rate Supercapacitor Performance

    Science.gov (United States)

    Gawli, Yogesh; Banerjee, Abhik; Dhakras, Dipti; Deo, Meenal; Bulani, Dinesh; Wadgaonkar, Prakash; Shelke, Manjusha; Ogale, Satishchandra

    2016-02-01

    A good high rate supercapacitor performance requires a fine control of morphological (surface area and pore size distribution) and electrical properties of the electrode materials. Polyaniline (PANI) is an interesting material in supercapacitor context because it stores energy Faradaically. However in conventional inorganic (e.g. HCl) acid doping, the conductivity is high but the morphological features are undesirable. On the other hand, in weak organic acid (e.g. phytic acid) doping, interesting and desirable 3D connected morphological features are attained but the conductivity is poorer. Here the synergy of the positive quality factors of these two acid doping approaches is realized by concurrent and optimized strong-inorganic (HCl) and weak-organic (phytic) acid doping, resulting in a molecular composite material that renders impressive and robust supercapacitor performance. Thus, a nearly constant high specific capacitance of 350 F g‑1 is realized for the optimised case of binary doping over the entire range of 1 A g‑1 to 40 A g‑1 with stability of 500 cycles at 40 A g‑1. Frequency dependant conductivity measurements show that the optimized co-doped case is more metallic than separately doped materials. This transport property emanates from the unique 3D single molecular character of such system.

  11. 3D Polyaniline Architecture by Concurrent Inorganic and Organic Acid Doping for Superior and Robust High Rate Supercapacitor Performance.

    Science.gov (United States)

    Gawli, Yogesh; Banerjee, Abhik; Dhakras, Dipti; Deo, Meenal; Bulani, Dinesh; Wadgaonkar, Prakash; Shelke, Manjusha; Ogale, Satishchandra

    2016-02-12

    A good high rate supercapacitor performance requires a fine control of morphological (surface area and pore size distribution) and electrical properties of the electrode materials. Polyaniline (PANI) is an interesting material in supercapacitor context because it stores energy Faradaically. However in conventional inorganic (e.g. HCl) acid doping, the conductivity is high but the morphological features are undesirable. On the other hand, in weak organic acid (e.g. phytic acid) doping, interesting and desirable 3D connected morphological features are attained but the conductivity is poorer. Here the synergy of the positive quality factors of these two acid doping approaches is realized by concurrent and optimized strong-inorganic (HCl) and weak-organic (phytic) acid doping, resulting in a molecular composite material that renders impressive and robust supercapacitor performance. Thus, a nearly constant high specific capacitance of 350 F g(-1) is realized for the optimised case of binary doping over the entire range of 1 A g(-1) to 40 A g(-1) with stability of 500 cycles at 40 A g(-1). Frequency dependant conductivity measurements show that the optimized co-doped case is more metallic than separately doped materials. This transport property emanates from the unique 3D single molecular character of such system.

  12. Eu-doped Mg-Al layered double hydroxide as a responsive fluorescent material and its interaction with glutamic acid.

    Science.gov (United States)

    Chen, Yufeng; Li, Fei; Yu, Gensheng; Wei, Junchao

    2012-10-01

    The paper describes a study on the fluorescence of a Eu-doped Mg-Al layered double hydroxide (Eu-doped LDH) response to glutamic acid (Glu). Various characterizations (UV-Vis transmittance, TG-DTA and IR-spectrum) indicated that there is an interaction between the Eu-doped LDH and Glu. Fluorescent study was found that the red emissions resulted from (5)D(0)-(7)F(J) transition (J=1, 2) of Eu(3+) markedly decreased, while the blue emission at 440 nm contributed to Glu shifted to low energy after the addition of Glu to the Eu-doped LDH. The fluorescent changes may be relevant to the hydrogen-bond interaction between the Eu-doped LDH and Glu, and the mechanism of the interaction between Eu-doped LDH and Glu was discussed.

  13. PHOTO-INDUCED DOPED POLYANILINE BY THE VINYLIDENE CHLORIDE AND METHYL ACRYLATE COPOLYMER AS PHOTO ACID GENERATOR

    Institute of Scientific and Technical Information of China (English)

    LI Suzhen; WAN Meixiang

    1997-01-01

    The emeraldine base form of polyaniline (PANI) can be doped by a photo-induced doping method. In this method a copolymer of vinylidene chloride and methyl acrylate (VCMAC) was used as photo acid generator which can release proton when it is exposed to ultraviolet light (λ = 254 nm). The structure of PANI-VCMAC system before and after irradiation was characterized by elemental analysis, IR, XPS, and SEM images. Results obtained indicate that the photo-induced doping characteristics, such as doping position and type of charge carriers, are similar to that of PANI doped with HCl. The poor roomtemperature conductivity (~ 10-5S/cm) of PANI-VCMAC system after irradiation may be due to low doping degree (~pH= 3) and the difference in morphology as compared with PANI-HCl film.

  14. Investigations on the electrical and structural properties of polyaniline doped with camphor sulphonic acid

    Science.gov (United States)

    Saravanan, S.; Joseph Mathai, C.; Anantharaman, M. R.; Venkatachalam, S.; Prabhakaran, P. V.

    2006-07-01

    Polyaniline is chemically synthesised and doped with camphor sulphonic acid. FTIR studies carried out on these samples indicate that the aromatic rings are retained after polymerisation. The percentage of crystallinity for polyaniline doped with camphor sulphonic acid has been estimated from the X-ray diffraction studies and is around 56% with respect to polyaniline emeraldine base. The change in dielectric permittivity with respect to temperature and frequency is explained on the basis of interfacial polarisation. AC conductivity is evaluated from the observed dielectric permittivity. The values of AC and DC conductivity and activation energy are calculated. The activation energy values suggested that the hopping conduction is the prominent conduction mechanism in this system.

  15. Phosphoric acid doped imidazolium polysulfone membranes for high temperature proton exchange membrane fuel cells

    DEFF Research Database (Denmark)

    Yang, Jingshuai; Li, Qingfeng; Jensen, Jens Oluf;

    2012-01-01

    A novel acid–base polymer membrane is prepared by doping of imidazolium polysulfone with phosphoric acid for high temperature proton exchange membrane fuel cells. Polysulfone is first chloromethylated, followed by functionalization of the chloromethylated polysulfone with alkyl imidazoles i.......e. methyl (MePSU), ethyl (EtPSU) and butyl (BuPSU) imidazoliums, as revealed by 1H NMR spectra. The imidazolium polysulfone membranes are then doped with phosphoric acid and used as a proton exchange membrane electrolyte in fuel cells. An acid doping level of about 10–11mol H3PO4 per mole of the imidazolium...... group is achieved in 85wt% H3PO4 at room temperature. The membranes exhibit a proton conductivity of 0.015–0.022Scm−1 at 130–150°C under 15mol% water vapor in air, and a tensile strength of 5–6MPa at 130°C under ambient humidity. Fuel cell tests show an open circuit voltage as high as 0.96V and a peak...

  16. Doping Polypyrrole Films with 4-N-Pentylphenylboronic Acid to Enhance Affinity towards Bacteria and Dopamine.

    Science.gov (United States)

    Golabi, Mohsen; Padiolleau, Laurence; Chen, Xi; Jafari, Mohammad Javad; Sheikhzadeh, Elham; Turner, Anthony P F; Jager, Edwin W H; Beni, Valerio

    2016-01-01

    Here we demonstrate the use of a functional dopant as a fast and simple way to tune the chemical affinity and selectivity of polypyrrole films. More specifically, a boronic-functionalised dopant, 4-N-Pentylphenylboronic Acid (PBA), was used to provide to polypyrrole films with enhanced affinity towards diols. In order to prove the proposed concept, two model systems were explored: (i) the capture and the electrochemical detection of dopamine and (ii) the adhesion of bacteria onto surfaces. The chemisensor, based on overoxidised polypyrrole boronic doped film, was shown to have the ability to capture and retain dopamine, thus improving its detection; furthermore the chemisensor showed better sensitivity in comparison with overoxidised perchlorate doped films. The adhesion of bacteria, Deinococcus proteolyticus, Escherichia coli, Streptococcus pneumoniae and Klebsiella pneumoniae, onto the boric doped polypyrrole film was also tested. The presence of the boronic group in the polypyrrole film was shown to favour the adhesion of sugar-rich bacterial cells when compared with a control film (Dodecyl benzenesulfonate (DBS) doped film) with similar morphological and physical properties. The presented single step synthesis approach is simple and fast, does not require the development and synthesis of functional monomers, and can be easily expanded to the electrochemical, and possibly chemical, fabrication of novel functional surfaces and interfaces with inherent pre-defined sensing and chemical properties.

  17. PEM steam electrolysis at 130 °C using a phosphoric acid doped short side chain PFSA membrane

    DEFF Research Database (Denmark)

    Hansen, Martin Kalmar; Aili, David; Christensen, Erik;

    2012-01-01

    Steam electrolysis test with a phosphoric acid doped Aquivion™ membrane was successfully conducted and current densities up to 775 mA cm-2 at 1.8 V was reached at 130 ºC and ambient pressure. A new composite membrane system using a perfluorosulfonic acid membrane (Aquivion™) as matrix and phospho......Steam electrolysis test with a phosphoric acid doped Aquivion™ membrane was successfully conducted and current densities up to 775 mA cm-2 at 1.8 V was reached at 130 ºC and ambient pressure. A new composite membrane system using a perfluorosulfonic acid membrane (Aquivion™) as matrix...

  18. Electrochemical promotion of oxidative coupling of methane on platinum/polybenzimidazole catalyst

    DEFF Research Database (Denmark)

    Petrushina, Irina; Bandur, Viktor; Bjerrum, Niels

    2002-01-01

    The electrochemical promotion of catalytic methane oxidation was studied using a (CH4,O-2,Ar), Pt\\polybenzimidazole (PBI)-H3PO4\\Pt,(H-2,Ar) fuel cell at 135degreesC. It has been found that C2H2, CO2, and water are the main oxidation products. Without polarization the yield of C2H2 was 0.9% and th......The electrochemical promotion of catalytic methane oxidation was studied using a (CH4,O-2,Ar), Pt\\polybenzimidazole (PBI)-H3PO4\\Pt,(H-2,Ar) fuel cell at 135degreesC. It has been found that C2H2, CO2, and water are the main oxidation products. Without polarization the yield of C2H2 was 0...

  19. Polybenzimidazole-decorated carbon nanotube: A high-performance proton conductor

    Energy Technology Data Exchange (ETDEWEB)

    Majedi, Fatemeh Sadat [Laboratoire de Microsystemes (LMIS4), Ecole Polytechnique Federale de Lausanne (EPFL), Lausanne (Switzerland); Department of Biomedical Engineering, Amirkabir University of Technology, Tehran (Iran, Islamic Republic of); Hasani-Sadrabadi, Mohammad Mahdi [Laboratoire de Microsystemes (LMIS4), Ecole Polytechnique Federale de Lausanne (EPFL), Lausanne (Switzerland); Department of Polymer Engineering and Color Technology, Amirkabir University of Technology, Tehran (Iran, Islamic Republic of); Dashtimoghadam, Erfan [Department of Polymer Engineering and Color Technology, Amirkabir University of Technology, Tehran (Iran, Islamic Republic of); Haghighi, Amir Hossein [Faculty of Engineering, Islamic Azad University, Shiraz Branch, Shiraz, Fars (Iran, Islamic Republic of); Bertsch, Arnaud; Renaud, Philippe [Laboratoire de Microsystemes (LMIS4), Ecole Polytechnique Federale de Lausanne (EPFL), Lausanne (Switzerland); Moaddel, Homayoun [Hydrogen and Fuel Cell Inc., Arcadia, CA (United States)

    2012-07-15

    Interaction between negatively charged Nafion {sup registered} and a positively charged polybenzimidazole-decorated carbon nanotube leads to the formation of an ionic complex with high charge density for proton conduction, which can lead to an improvement in transport properties. Here we investigate the high-temperature and low-humidity proton conductivity of this nanocomposite membrane as a potential membrane for fuel cell applications. (copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  20. Dielectric properties of solution-grown-undoped and acrylic-acid-doped ethyl cellulose

    Indian Academy of Sciences (India)

    P K Khare; Sandeep K Jain

    2000-02-01

    Dielectric capacities and losses were measured, in the temperature (50–170°C) and frequency (01–100 kHz range), for undoped and acrylic acid (AA) doped ethyl cellulose (EC) films (thickness about 20 m) with progressive increase in the concentration of dopant in the polymer matrix. The variation of capacity with temperature is attributed to thermal expansion in the lower temperature region to the orientation of dipolar molecules in the neighbourhood of glass transition temperature () and random thermal motion of molecules above . The dielectric losses exhibit a broad peak. Doping with AA is found to affect the magnitude and position of the peak. AA is found to have a two-fold action. Firstly, it enhances the chain mobility and secondly, it increases the dielectric loss by forming charge transfer complexes.

  1. Fluorescence Properties of Eu3+/Gd3+/Citric Acid Mixed Complexes Doping in Silicon Rubber Matrix

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Series of doped rare earth complexes-EuxGd(1-x)(CA)3·nH2O (CA=citric acid) were synthesized. Some characterizations were taken for these complexes. The experimental results shows that the doped rare earth complexes have the best fluorescence property when the ratio of Eu and Gd is from 0.7 to 0.3. Silicon rubber-based composites were prepared by mechanical blending the EuxGd(1-x)(CA)3·nH2O and silicon rubber. Then, the fluorescent property of the composites was studied. It is found that the fluorescence intensity of the composites increase linearly with the contents of the rare earth complexes increasing.

  2. Polypyrrole electrodes doped with sulfanilic acid azochromotrop for electrochemical supercapacitors

    Science.gov (United States)

    Chen, S.; Zhitomirsky, I.

    2013-12-01

    In this work we demonstrate the feasibility of deposition of polypyrrole (PPy) films by electropolymerization on stainless steel substrates and fabrication of PPy powders by chemical polymerization using sulfanilic acid azochromotrop (SPADNS) as a new anionic dopant. The problem of low adhesion of PPy films to stainless steel substrates is addressed by the use of SPADNS, which exhibits chelating properties, promoting film formation. The use of fine particles, prepared by the chemical polymerization method, allows impregnation of Ni foams and fabrication of porous electrodes with high materials loading for electrochemical supercapacitors (ES). PPy films and Ni foam based PPy electrodes show capacitive behaviour in Na2SO4 electrolyte. The electron microscopy studies, impedance spectroscopy data and analysis of the SPADNS structure provide an insight into the factors, controlling capacitive behaviour. The Ni foam based electrodes offer advantages of improved capacitive behaviour at high materials loadings and good cycling stability. The area normalized and volume normalized specific capacitances are as high as 5.43 F cm-2 and 93.6 F cm-3, respectively, for materials loading of 35.4 mg cm-2. The capacitance retention of Ni foam based electrodes is 91.5% after 1000 cycles. The Ni foam based PPy electrodes are promising for application in ES.

  3. Preparation of a Novel Acid Doped Polyaniline Adsorbent for Removal of Anionic Pollutant from Wastewater

    Institute of Scientific and Technical Information of China (English)

    LI Jiajia; WANG Qizhao; BAI Yan; JIA Yongming; SHANG Pan; HUANG Haohao; WANG Fangping

    2015-01-01

    Polyaniline (PANI) was one of the most extensively studied adsorbents due to its low cost and good environmental stability. The objective of the current study was to improve the selective capabilities of PANI for anionic dyes. We found that the acid doped PANI prepared with hydrochloric acid and p-toluenesulfonic acid (PTSA) could selectively adsorb anionic dyes. It exhibited very good selectivity for OG dye, the mechanism was proposed based on the chemical interaction of PANI with the sulfonate group of the dyes. The effects of solution pH, initial dye concentration, and different HCl/PTSA mole ratios on the adsorption capacity of OG have been investigated. Kinetic simulations indicated that the adsorption process could be well represented by pseudo-second-order kinetic plots. The isothermal adsorption curve iftting also showed that the adsorption process could be well described by the Langmuir isothermal equation. The results showed that acid doped PANI could be employed as a promising adsorbent for anion removal from dye wastewater.

  4. Photocatalytic degradation of acid orange 7 in aqueous solution with La3+-doped TiO2 photocatalysts

    Institute of Scientific and Technical Information of China (English)

    XIA Changbin; ZHOU Yi; LI Xun; ZENG Jing; XU Ruiyin

    2005-01-01

    Nanocrystalline La3+-doped TiO2 of 20-30 nm in size was prepared by a sol-gel technique. The photocatalytic activities of the samples were evaluated by the degradation of harmful acid orange 7(AO7) azo-dye in aqueous solution. The effects of La3+ ion implantation on the photocatalytic activity of TiO2 were also discussed. The results show that the La3+content plays an essential role in affecting the photocatalytic activity of the La3+-doped TiO2 and the optimum content of La3+-doped is 1.0 wt.%. The photocatalytic activity of the samples with La3+-doped TiO2 is higher than that of pure TiO2 in the treatment of AO7 wastewater. The photodegradation effect of AO7 effluent is the best by means of La3+-doped TiO2 with 1.0% La3+.

  5. Electrochemical incineration of sulfanilic acid at a boron-doped diamond anode.

    Science.gov (United States)

    El-Ghenymy, Abdellatif; Arias, Conchita; Cabot, Pere Lluís; Centellas, Francesc; Garrido, José Antonio; Rodríguez, Rosa María; Brillas, Enric

    2012-06-01

    The anodic oxidation of sulfanilic acid solutions has been studied in acidic medium using a divided cell with a boron-doped diamond (BDD) anode and a stainless steel cathode. Overall mineralization was achieved under all experimental conditions tested due to the efficient destruction of sulfanilic acid and all its by-products with hydroxyl radicals generated at the BDD anode from water oxidation. The alternative use of an undivided cell with the same electrodes gave rise to the coating of the cathode with polymeric compounds, thus preventing the complete electrochemical incineration of sulfanilic acid. The solutions treated in the anodic compartment of the divided cell were degraded at similar rate under pH regulation within the pH interval 2.0-6.0. The mineralization current efficiency was enhanced when the applied current decreased and the initial substrate concentration increased. The decay of sulfanilic acid was followed by reversed-phase HPLC, showing a pseudo first-order kinetics. Hydroquinone and p-benzoquinone were identified as aromatic intermediates by gas chromatography-mass spectrometry and/or reversed-phase HPLC. Maleic, acetic, formic, oxalic and oxamic acids were detected as generated carboxylic acids by ion-exclusion HPLC. Ionic chromatographic analysis of electrolyzed solutions revealed that the N content of sulfanilic acid was mainly released as NH(4)(+) ion and in much smaller proportion as NO(3)(-) ion.

  6. 新型砜基聚苯并咪唑的合成%Synthesis of Novel Sulfoned-polybenzimidazole

    Institute of Scientific and Technical Information of China (English)

    徐艺; 常冠军; 张林

    2012-01-01

    Adopted novel synthesis routine, a novel sulfoned-polybenzimidazole was synthesized in sulfolane from monomers of bifluoride and di(benzimidazolyl) benzenes which was prepared by the reaction of 4,4'-dicarboxyl-diphenylsulfone with o-phenylenediamine using polyphosphoric acid(PPA) as the catalysis. The structure was characterized by 'H NMR, IR, MS and elemental analysis.%采用新的合成路线,以多聚磷酸催化4,4′-二羧基二苯砜与邻苯二胺反应制得双苯并咪唑二苯砜(3);以3和4,4′-二氟二苯砜为单体,环丁砜为溶剂,在无水碳酸钾存在下合成了新型砜基聚苯并咪唑,其结构经1H NMR,IR,MS和元素分析表征.

  7. Copper- or manganese-doped ZnS quantum dots as fluorescent probes for detecting folic acid in aqueous media

    Energy Technology Data Exchange (ETDEWEB)

    Geszke-Moritz, Malgorzata [Laboratoire Reactions et Genie des Procedes (LRGP), Nancy-University, CNRS, 1 rue Grandville, 54001 Nancy Cedex (France); Department of Pharmaceutical Technology, Poznan University of Medical Sciences, Grunwaldzka 6, 60-780 Poznan (Poland); Clavier, Gilles [PPSM, ENS Cachan, CNRS, UniverSud, 61 avenue President Wilson, 94230 Cachan (France); Lulek, Janina [Department of Pharmaceutical Technology, Poznan University of Medical Sciences, Grunwaldzka 6, 60-780 Poznan (Poland); Schneider, Raphaeel, E-mail: raphael.schneider@ensic.inpl-nancy.fr [Laboratoire Reactions et Genie des Procedes (LRGP), Nancy-University, CNRS, 1 rue Grandville, 54001 Nancy Cedex (France)

    2012-04-15

    3-Mercaptopropionic acid-capped core/shell ZnS:Cu/ZnS and ZnS:Mn/ZnS doped quantum dots (QDs) prepared through hydrothermal methods exhibit high photoluminescence intensity as well as good photostability. These water-dispersible nanoparticles exhibit high fluorescence sensitivity to folic acid due to the high affinity of the carboxylate groups and nitrogen atoms of folic acid towards the Zn surface atoms of the doped dots. Quenching of the fluorescence intensity of the QDs allows the detection of folic acid concentrations as low as 11 {mu}M, thus affording a very sensitive system for the sensing of this biologically active molecule in aqueous solution. The possible quenching mechanism is discussed. - Graphical abstract: A sensitive method for the detection of folic acid based on the fluorescence quenching of Mn- or Cu-doped ZnS quantum dots was developed. Highlights: Black-Right-Pointing-Pointer Quenching of the fluorescence intensity of doped ZnS QDs in the presence of folic acid. Black-Right-Pointing-Pointer New fluorescent sensors for folic acid. Black-Right-Pointing-Pointer Detection of folic acid concentrations as low as 11 {mu}M in aqueous solution. Black-Right-Pointing-Pointer The Perrin model and fluorescence lifetimes of ZnS:Mn QDs demonstrate a static quenching mechanism. Black-Right-Pointing-Pointer Quenching efficiency of ZnS:Cu QDs correlates with the Stern-Volmer model.

  8. Development of materials consisting of conjugated polymer doped with folic acid

    Directory of Open Access Journals (Sweden)

    Vicente Kupfer

    2012-06-01

    Full Text Available The development of new materials made from the combination between conjugated polymers and new dopants is the objective of various researches groups around the world. This work presented the synthesis and characterization of Polyaniline (PAni doped with folic acid. The material was synthesized through oxidative polymerization of the previously prepared emulsion of aniline in different concentrations with adding of the folic acid. The materials were characterized by spectroscopic techniques (infrared and UV-Vis, thermogravimetric analysis and electrochemical impedance spectroscopy. The infrared results suggested the effective formation of the materials and the results of the UV-Vis corroborate with this hypothesis. The thermogravimetric curves showed an intermediate behavior of the resulting materials coming from the starting materials (folic acid and PANi. By measuring the conductivity could be affirmed that the material behaved as semiconductors.

  9. A Study on Tannic Acid-doped Polypyrrole Films on Gold Electrodes for Selective Electrochemical Detection of Dopamine

    OpenAIRE

    Shouzhuo Yao; Yunlong Li; Zhili Li; Qingji Xie; Ling Jiang

    2005-01-01

    Tannic acid-doped polypyrrole (PPY/TA) films have been grown on gold electrodes for selective electrochemical detection of dopamine (DA). Electrochemical quartz crystal microbalance (EQCM) studies revealed that, in vivid contrast to perchlorate-doped polypyrrole films (PPY/ClO4 -), the redox switching of PPY/TA films in aqueous solutions involved only cation transport if the solution pH was greater than 3∼4. The PPY/TA Au electrodes also exhibited attractive permselectivity for electroactive ...

  10. Activation procedures characterization of MEA based on phosphoric acid doped PBI membranes

    Energy Technology Data Exchange (ETDEWEB)

    Boaventura, M.; Mendes, A. [Laboratorio de Engenharia de Processos, Ambiente e Energia (LEPAE), Faculdade de Engenharia da Universidade do Porto, Rua Roberto Frias, 4200-465 Porto (Portugal)

    2010-10-15

    This work aims at better understanding the activation process of phosphoric acid doped PBI-based MEA. The phenomena involved in the activation of Celtec {sup registered} - P1000 MEA were studied based on polarization curves, AC impedance spectroscopy combined with equivalent circuit modelling and cyclic voltammetry analysis. It was concluded that galvanostatic activation procedure enhanced Celtec {sup registered} - P1000 MEA performance by increasing the catalyst activity and by decreasing the ohmic resistance. Also, galvanostatic and potential cycling procedures were applied to an in-house prepared MEA; for the same activation time, the galvanostatic allowed a deeper activation of the in-house prepared MEA than the potential cycling activation method. It is accepted that the humidification of the reactants is not necessary for high temperature PEMFC based on phosphoric acid doped PBI membrane, since water production at the cathode should be enough to ensure high performance of the fuel cell. In this work it is described the behavior of a PEMFC based on an in-house prepared MEA, after activation at different temperatures and relative humidities. It is shown that water has an enhanced effect on ohmic resistance during the PEMFC operation but can also have a detrimental effect on the cathode resistance due to migration of phosphoric acid outside MEA. (author)

  11. Magnetic resonance and electrical properties of p-toluene sulphonic acid doped polyaniline

    Science.gov (United States)

    Arora, Manju; Arya, S. K.; Barala, Sunil Kumar; Saini, Parveen

    2013-06-01

    p-Toluene Sulphonic Acid (PTSA) doped polyaniline (PANI) analogues were synthesized by oxidative chemical polymerization method and characterized by TGA FTIR and EPR spectroscopic techniques. FTIR spectra indicates the formation of PTSA doped PANI and also revealed the dopant ions mediated interactions between polymeric chain through weak hydrogen bonding. TGA plots revealed that there is systematic variation in the weight loss at ˜300 °C from ˜4% to ˜38% with increase in dopant concentration from 0.01 N to 1.0 N. Magnetic resonance spectra of polaron charge carriers exhibit the single Lorentzian line signal with the Dysonian contribution indicating formation of metal-like domains. The polarons are localized in these domains by strong interaction between the neighboring conducting chains, in which the charge is transferred by quasi-three-dimensional (Q3D) delocalized electron. In higher concentration analogue some of polarons merge into diamagnetic bipolarons and this reduces intensity of EPR signal. The electrical conductivity of the 1.0 N PTSA doped sample was ˜4.5 S/cm which satisfies the EMI shielding criteri.

  12. Polybenzimidazole membranes for zero gap alkaline electrolysis cells

    DEFF Research Database (Denmark)

    Kraglund, Mikkel Rykær; Aili, David; Christensen, Erik;

    Membranes of m-PBI doped in KOH (aq), 15-35 wt%, show high ionic conductivity in the temperature range 20-80 ºC. In electrolysis cells with nickel foam electrodes m-PBI membranesprovide low internal resistance. With a 60 µm membraneat 80ºC in 20 wt% KOH,1000 mA/cm2 is achieved at 2.25....

  13. Fabrication of folic acid sensor based on the Cu doped SnO2 nanoparticles modified glassy carbon electrode

    Science.gov (United States)

    Lavanya, N.; Radhakrishnan, S.; Sudhan, N.; Sekar, C.; Leonardi, S. G.; Cannilla, C.; Neri, G.

    2014-07-01

    A novel folic acid biosensor has been fabricated using Cu doped SnO2 nanoparticles (NPs) synthesized by a simple microwave irradiation method. Powder XRD and TEM studies confirmed that both the pure and Cu doped SnO2 (Cu: 0, 10, 20wt%) crystallized in tetragonal rutile-type structure with spherical morphology. The average crystallite size of pure SnO2 was estimated to be around 16 nm. Upon doping, the crystallite sizes decreased to 9 nm and 5 nm for 10 and 20wt% Cu doped SnO2 respectively. XPS studies confirmed the electronic state of Sn and Cu to be 4+ and 2+ respectively. Cu (20wt%) doped SnO2 NPs are proved to be a good sensing element for the determination of folic acid (FA). Cu-SnO2 NPs (20wt%) modified glassy carbon electrode (GCE) exhibited the lowest detection limit of 0.024 nM over a wide folic acid concentration range of 1.0 × 10-10 to 6.7 × 10-5 M at physiological pH of 7.0. The fabricated sensor is highly selective towards the determination of FA even in the presence of a 100 fold excess of common interferent ascorbic acid. The sensor proved to be useful for the estimation of FA content in pharmaceutical sample with satisfactory recovery.

  14. Preparation and reactivity of carboxylic acid-terminated boron-doped diamond electrodes

    Energy Technology Data Exchange (ETDEWEB)

    Niedziolka-Joensson, Joanna [Institut de Recherche Interdisciplinaire (IRI, USR 3078), Parc de la Haute Borne, 50 Avenue de Halley, BP 70478, 59658 Villeneuve d' Ascq (France); Institut d' Electronique, de Microelectronique et de Nanotechnologie (IEMN, UMR 8520), Cite Scientifique, Avenue Poincare, BP 60069, 59652 Villeneuve d' Ascq (France); Boland, Susan; Leech, Donal [School of Chemistry, National University of Irland, Galway (Ireland); Boukherroub, Rabah [Institut de Recherche Interdisciplinaire (IRI, USR 3078), Parc de la Haute Borne, 50 Avenue de Halley, BP 70478, 59658 Villeneuve d' Ascq (France); Institut d' Electronique, de Microelectronique et de Nanotechnologie (IEMN, UMR 8520), Cite Scientifique, Avenue Poincare, BP 60069, 59652 Villeneuve d' Ascq (France); Szunerits, Sabine, E-mail: sabine.szunerits@iri.univ-lille1.f [Institut de Recherche Interdisciplinaire (IRI, USR 3078), Parc de la Haute Borne, 50 Avenue de Halley, BP 70478, 59658 Villeneuve d' Ascq (France); Institut d' Electronique, de Microelectronique et de Nanotechnologie (IEMN, UMR 8520), Cite Scientifique, Avenue Poincare, BP 60069, 59652 Villeneuve d' Ascq (France)

    2010-01-01

    The paper reports on the formation of carboxy-terminated boron-doped diamond (BDD) electrodes. The carboxylic acid termination was prepared in a controlled way by reacting photochemically oxidized BDD with succinic anhydride. The resulting interface was readily employed for the linking of an amine-terminated ligand such as an osmium complex bearing an amine terminal group. The interfaces were characterized using X-ray photoelectron spectroscopy (XPS) and cyclic voltammetry (CV). Contact angle measurements were used to follow the changes in surface wetting properties due to surface functionalization. The chemical reactivity of the carboxyl-terminated BDD was investigated by covalent coupling of the acid groups to an amine-terminated osmium complex.

  15. Synthesis and Characteristic Study on Complexes of Europium(Ⅲ) and Maleic Acid Doped with Non-Fluorescent Ions

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Complex of europium (Ⅲ) with maleic acid, and binuclear complexes of europium(Ⅲ)with maleic acid doped with non-fluorescent ions gadolinium, lanthanum and yttrium, were synthesized. The compositions and structures of complexes were characterized with elemental analysis, single crystal X-ray diffraction, IR and DSC-TG. Fluorescent properties were studied with fluorescence spectrum. The results indicated that the strongest fluorescent complexes were obtained when the ratio of europium and non-fluorescent ion was 8: 2. The order of Eu3+ fluorescence strengthened by three doped rare earths was Gd3+>La3+>Y3+.

  16. Characterization of nano-lead-doped active carbon and its application in lead-acid battery

    Science.gov (United States)

    Hong, Bo; Jiang, Liangxing; Xue, Haitao; Liu, Fangyang; Jia, Ming; Li, Jie; Liu, Yexiang

    2014-12-01

    In this paper, nano-lead-doped active carbon (nano-Pb/AC) composite with low hydrogen evolution current for lead-acid battery was prepared by ultrasonic-absorption and chemical-precipitate method. The nano-Pb/AC composite was characterized by SEM, EDS and TEM. The electrochemical characterizations are performed by linear sweep voltammetry (LSV), electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV) in a three-electrode system. Since intermediate adsorption is the rate-determining step, the hydrogen evolution reaction (HER) is markedly inhibited as the intermediate adsorption impedance of nano-Pb/AC increased. Meanwhile, the working potential of nano-Pb/AC is widened to the whole potential region of Pb negative plate (from -1.36 V to -0.86 V vs. Hg/HgSO4) in lead-acid battery. In addition, nano-Pb can improve the interfacial compatibility between AC and Pb paste, accordingly relieve the symptoms of carbon floatation. Finally, 2.0 V single-cell flooded lead-acid batteries with 1.0 wt.% nano-Pb/AC or 1.0 wt.% AC addition in negative active materials are assembled. The cell performances test results show that the 3 h rate capacity, quick charging performance, high current discharging performance and cycling performance of nano-Pb/AC modified battery are all improved compared with regular lead-acid battery and AC modified lead-acid battery.

  17. N, S co-doped carbon dots with orange luminescence synthesized through polymerization and carbonization reaction of amino acids

    Energy Technology Data Exchange (ETDEWEB)

    Zeng, Ya-Wen [Nanomaterials and Chemistry Key Laboratory, Wenzhou University, Wenzhou, Zhejiang 325027 (China); Ma, De-Kun, E-mail: dkma@wzu.edu.cn [Nanomaterials and Chemistry Key Laboratory, Wenzhou University, Wenzhou, Zhejiang 325027 (China); Wang, Wei; Chen, Jing-Jing; Zhou, Lin; Zheng, Yi-Zhou [Department of Hematology, The First Affiliated Hospital of Wenzhou Medical University, Wenzhou, Zhejiang 325027 (China); Yu, Kang, E-mail: yukang62@126.com [Department of Hematology, The First Affiliated Hospital of Wenzhou Medical University, Wenzhou, Zhejiang 325027 (China); Huang, Shao-Ming, E-mail: smhuang@wzu.edu.cn [Nanomaterials and Chemistry Key Laboratory, Wenzhou University, Wenzhou, Zhejiang 325027 (China)

    2015-07-01

    Graphical abstract: N, S co-doped CDs with orange luminescence were synthesized through one-pot polymerization and carbonization reactions under hydrothermal conditions, using two different amino acids as raw materials. - Highlights: • N, S co-doped CDs were synthesized by one-pot carbonization reactions, using two different amino acids as raw materials. • The as-obtained N, S co-doped CDs showed unique orange fluorescence under excitation at room temperature. • The products could be applied in the imaging of peritoneal macrophages of mice without any functionalization. - Abstract: For practical application, it is highly desirable to obtain carbon dots (CDs) through environmentally benign synthetic route, using green raw materials. On the other hand, at present, most of CDs reported in the literature showed blue, green and yellow emission. Therefore it is still necessary to develop new strategy to obtain CDs with longer wavelength emission in order to expand their application range. Toward this end, in this study, N, S co-doped CDs were synthesized through one-pot condensation polymerization and carbonization reactions under hydrothermal conditions, using two different amino acids as raw materials. Taking the reaction of L-serine with L-cystine as an example, the as-obtained products were characterized by various techniques such as transmission electron microscopy, elemental analysis, Fourier-transform infrared spectrum, X-ray photoelectron spectra, and so on. Interestingly, N, S co-doped CDs displayed unique orange emission at room temperature. The possible photoluminescence mechanism of N, S co-doped CDs was proposed. Furthermore, the as-synthesized N, S co-doped CDs were directly applied in the imaging of peritoneal macrophages of mice.

  18. Hydrophilic and blue fluorescent N-doped carbon dots from tartaric acid and various alkylol amines under microwave irradiation

    Science.gov (United States)

    Xu, Minghan; Xu, Shusheng; Yang, Zhi; Shu, Mengjun; He, Guili; Huang, Da; Zhang, Liling; Li, Li; Cui, Daxiang; Zhang, Yafei

    2015-09-01

    The desired control of particle size, doping element composition, and surface structure of carbon dots (CDs) are vital for understanding the fluorescence mechanism and exploring their potential applications. Herein, nitrogen-doped CDs (N-doped CDs) have been synthesized with tartaric acid and various alkylol amines (monoethanolamine, biethanolamine and triethanolamine) under microwave irradiation. A systematic investigation was performed to characterize the N-doped CDs. It is found that with increasing nitrogen proportion, the fluorescent quantum yield and lifetime of N-doped CDs increases, whereas cell toxicity decreases. In other words, N-doped CDs synthesized by tartaric acid and monoethanolamine have the highest nitrogen content, the highest fluorescent quantum yield, the longest lifetime and the lowest cell toxicity. A corresponding mechanism has been proposed. Moreover, as-synthesized N-doped CDs have been applied for selectively detecting the Fe3+ ion and writing letters as a fluorescent ink.The desired control of particle size, doping element composition, and surface structure of carbon dots (CDs) are vital for understanding the fluorescence mechanism and exploring their potential applications. Herein, nitrogen-doped CDs (N-doped CDs) have been synthesized with tartaric acid and various alkylol amines (monoethanolamine, biethanolamine and triethanolamine) under microwave irradiation. A systematic investigation was performed to characterize the N-doped CDs. It is found that with increasing nitrogen proportion, the fluorescent quantum yield and lifetime of N-doped CDs increases, whereas cell toxicity decreases. In other words, N-doped CDs synthesized by tartaric acid and monoethanolamine have the highest nitrogen content, the highest fluorescent quantum yield, the longest lifetime and the lowest cell toxicity. A corresponding mechanism has been proposed. Moreover, as-synthesized N-doped CDs have been applied for selectively detecting the Fe3+ ion and writing

  19. Inhibitive Effect of Hydrofluoric Acid Doped Poly Aniline (HFPANI on Corrosion of Iron in 1N Phosphoric Acid Solution

    Directory of Open Access Journals (Sweden)

    G.Maheswari

    2015-03-01

    Full Text Available The inhibition effect of Hydrofluoric acid doped poly aniline HF-PANI on mild steel corrosion in 1N phosphoric acid has been studied by mass loss and polarization techniques and AC impedance measurements methods between 303 K and 333K.The inhibition efficiency increased with increase in concentration of HF PANI. The corrosion rate increased with increase in temperature and decreased with increase in concentration of inhibitor compared to blank. Potentiostatic polarization results revealed that HF-PANI act as mixed type inhibitor. The inhibitor of HF-PANI was chemically adsorbed and spontaneous adsorption on the mild steel surface .The values of activation energy (Ea, free energy of adsorption (ΔGads, heat of adsorption (Qads, enthalpy of adsorption (ΔH and entropy of adsorption (ΔS were calculated. The adsorption of inhibitor on mild steel surface has been found to obey Temkin’s adsorption isotherm. SEM analysis was agreed to establish the mechanism of corrosion inhibitor on mild steel corrosion in phosphoric acid medium.

  20. Comparative NH 3-sensing characteristic studies of PANI/TiO II nanocomposite thin films doped with different acids

    Science.gov (United States)

    Tai, Huiling; Jiang, Yadong; Xie, Guangzhong; Yu, Junsheng; Ying, Zhihua; Chen, Xuan

    2008-02-01

    Polyaniline/titanium dioxide (PANI/TiO II) nanocomposite thin films were synthesized by in-situ self-assembly method, which were doped with p-toluene sulphonic acid (p-TSA) and hydrochloric acid (HCl), respectively. The thin films were characterized by using UV-Vis absorption spectroscopy and scanning electron microscope (SEM), and the NH 3 gas sensitive properties of the thin films were investigated at room temperature. The results showed that the PANI/TiO II thin film doped with HCl was superior to that doped with p-TSA in terms of response-recovery characteristics. The surface morphology characterization of the thin films were performed to explain the different gas-sensing properties.

  1. Coaxially Aligned Polyaniline Nanofibers Doped with 3-Thiopheneacetic Acid through Interfacial Polymerization

    Directory of Open Access Journals (Sweden)

    Lixia Zhang

    2011-01-01

    Full Text Available Coaxially aligned polyaniline (PANI nanofibers doped with 3-thiopheneacetic acid (TAA were chemically synthesized by the interfacial polymerization of aniline in the presence of TAA, using iron (III chloride hexahydrate (FeCl3·6H2O as the oxidant. The morphology, crystallinity, room temperature conductivity, and coaxial alignment of the PANI-TAA nanofibers were highly dependent on the organic solvent used for the interfacial polymerization, the oxidant, and also the molar ratio of the aniline to TAA. Hexane, diethyl ether, dichloromethane, chloroform, and acetone were used as the organic solvents, and chloroform proved to be the best solvent for the formation of PANI-TAA nanofibers. The redox potential of the oxidant is the key to controlling the morphology and diameter of the PANI-TAA nanofibers. The use of FeCl3 as the oxidant leads to the formation of thin (∼50 nm PANI-TAA nanofibers, which increased in length, crystallinity, conductivity, and coaxial alignment as the molar ratio of TAA to aniline was increased from 0.1 : 1 to 1 : 1. By comparison, only granular PANI was obtained when ammonium persulfate (APS, which has a higher redox potential, was used as the oxidant. The doping function of TAA in the PANI-TAA nanofibers was confirmed by means of FTIR and UV-Visible spectroscopy.

  2. High temperature proton exchange membranes based on polybenzimidazoles for fuel cells

    DEFF Research Database (Denmark)

    Li, Qingfeng; Jensen, Jens Oluf; Savinell, Robert F;

    2009-01-01

    in recent years motivated extensive research activities with great progress. This treatise is devoted to updating the development, covering polymer synthesis, membrane casting, physicochemical characterizations and fuel cell technologies. To optimize the membrane properties, high molecular weight polymers...... havebeenmadeincluding spectroscopy,wateruptake and acid doping, thermal and oxidative stability, conductivity, electro-osmoticwater drag, methanol crossover, solubility and permeability of gases, and oxygen reduction kinetics. Related fuel cell technologies such as electrode and MEA fabrication have been developed...

  3. Performance Degradation Tests of Phosphoric Acid Doped PBI Membrane Based High Temperature PEM Fuel Cells

    DEFF Research Database (Denmark)

    Zhou, Fan; Araya, Samuel Simon; Grigoras, Ionela

    2014-01-01

    Degradation tests of two phosphoric acid (PA) doped PBI membrane based HT-PEM fuel cells were reported in this paper to investigate the effects of start/stop and the presence of methanol in the fuel to the performance degradation. Continuous tests with H2 and simulated reformate which was composed...... of H2, water steam and methanol as the fuel were performed on both single cells. 12-h-startup/12-h-shutdown dynamic tests were performed on the first single cell with pure dry H2 as the fuel and on the second single cell with simulated reformate as the fuel. Along with the tests electrochemical...... techniques such as polarization curves and electrochemical impedance spectroscopy (EIS) were employed to study the degradation mechanisms of the fuel cells. Both single cells showed an increase in the performance in the H2 continuous tests, because of a decrease in the ORR kinetic resistance probably due...

  4. Fulx-pinning mechanism and activation energy in malic acid-doped MgB2

    Directory of Open Access Journals (Sweden)

    SR Ghorbani

    2010-09-01

    Full Text Available Fulx-pinning mechanism and activation energy of MgB2 doped with 10 wt % malic- acid has been investigated by measurement of critical current density and resistivity as a function of magnetic fields and temperatures. The field dependence of the critical current density, Jc(B, was analyzed within the collective pinning model. A crossover field, Bsb, from the single vortex to the small vortex bundle-pinning regime was observed. For sintered sample, the temperature dependence of Bsb(T at low temperature is in good agreement with the δℓ pinning mechanism, i.e., pinning associated with charge-carrier mean free path fluctuation. The activation energy was decreased linearly by increasing magnetic field.

  5. Flexible, all-organic ammonia sensor based on dodecylbenzene sulfonic acid-doped polyaniline films

    Energy Technology Data Exchange (ETDEWEB)

    Rizzo, G. [Dipartimento di Chimica Industriale e Ingegneria dei Materiali, Universita degli Studi di Messina (Italy); Arena, A.; Donato, N.; Latino, M.; Saitta, G. [Dipartimento di Fisica della Materia e Ingegneria Elettronica, Universita degli Studi di Messina (Italy); Bonavita, A. [Dipartimento di Chimica Industriale e Ingegneria dei Materiali, Universita degli Studi di Messina (Italy); Neri, G., E-mail: neri@ingegneria.unime.i [Dipartimento di Chimica Industriale e Ingegneria dei Materiali, Universita degli Studi di Messina (Italy)

    2010-09-30

    A stable chlorobenzene dispersion of conducting polyaniline (PANI) has been obtained by doping emeraldine base with dodecylbenzene sulfonic acid (DBSA) and studied by spectrophotometric measurements in the UV-vis-IR range. The electrical properties of PANI: DBSA films obtained from the above dispersion have been investigated under different temperature and relative humidity conditions. All-organic chemoresistive devices have been developed by spin-coating the PANI: DBSA dispersion on flexible substrates, and then by depositing electrodes on the top, from a carbon nanotube conducting ink. Sensing tests performed under exposition to calibrated amounts of ammonia reveal that these simple and inexpensive sensors are able to detect ammonia at room temperature in a reliable way, with a sensitivity linearly related to concentration in the range between 5 ppm and 70 ppm.

  6. Effect of chloride impurities on the performance and durability of polybenzimidazole-based high temperature proton exchange membrane fuel cells

    DEFF Research Database (Denmark)

    Ali, Syed Talat; Li, Qingfeng; Pan, Chao;

    2011-01-01

    The effect of chloride as an air impurity and as a catalyst contaminant on the performance and durability of polybenzimidazole (PBI)-based high temperature proton exchange membrane fuel cell (HT-PEMFC) was studied. The ion chromatographic analysis reveals the existence of chloride contaminations...

  7. Ammonia Gas Sensing Behavior of Tanninsulfonic Acid Doped Polyaniline-TiO2 Composite

    Directory of Open Access Journals (Sweden)

    Venu Gopal Bairi

    2015-10-01

    Full Text Available A highly active tannin doped polyaniline-TiO2 composite ammonia gas sensor was developed and the mechanism behind the gas sensing activity was reported for the first time. A tanninsulfonic acid doped polyaniline (TANIPANI-titanium dioxide nanocomposite was synthesized by an in situ polymerization of aniline in the presence of tanninsulfonic acid and titanium dioxide nanoparticles. X-ray diffraction and thermogravimetric analysis were utilized to determine the incorporation of TiO2 in TANIPANI matrix. UV-Visible and infrared spectroscopy studies provided information about the electronic interactions among tannin, polyaniline, and TiO2. Scanning electron microscopy (SEM along with energy dispersive X-ray spectroscopy (EDS and atomic force microscopy (AFM surface analysis techniques were used to investigate the metal oxide dispersions inside polyaniline matrix. Gas sensors were prepared by spin coating solutions of TANIPANI-TiO2 and TANIPANI composites onto glass slides. Sensors were tested at three different concentrations (20 ppm, 40 ppm, and 60 ppm of ammonia gas at ambient temperature conditions by measuring the changes in surface resistivity of the films with respect to time. Ammonia gas sensing plots are presented showing the response values, response times and recovery times. The TANIPANI-TiO2 composite exhibited better response and shorter recovery times when compared to TANIPANI control and other polyaniline composites that have been reported in the literature. For the first time a proposed mechanism of gas sensing basing on the polaron band localization and its effects on the gas sensing behavior of polyaniline are reported.

  8. N-doped carbon nanomaterials are durable catalysts for oxygen reduction reaction in acidic fuel cells

    Science.gov (United States)

    Shui, Jianglan; Wang, Min; Du, Feng; Dai, Liming

    2015-01-01

    The availability of low-cost, efficient, and durable catalysts for oxygen reduction reaction (ORR) is a prerequisite for commercialization of the fuel cell technology. Along with intensive research efforts of more than half a century in developing nonprecious metal catalysts (NPMCs) to replace the expensive and scarce platinum-based catalysts, a new class of carbon-based, low-cost, metal-free ORR catalysts was demonstrated to show superior ORR performance to commercial platinum catalysts, particularly in alkaline electrolytes. However, their large-scale practical application in more popular acidic polymer electrolyte membrane (PEM) fuel cells remained elusive because they are often found to be less effective in acidic electrolytes, and no attempt has been made for a single PEM cell test. We demonstrated that rationally designed, metal-free, nitrogen-doped carbon nanotubes and their graphene composites exhibited significantly better long-term operational stabilities and comparable gravimetric power densities with respect to the best NPMC in acidic PEM cells. This work represents a major breakthrough in removing the bottlenecks to translate low-cost, metal-free, carbon-based ORR catalysts to commercial reality, and opens avenues for clean energy generation from affordable and durable fuel cells. PMID:26601132

  9. N-doped carbon nanomaterials are durable catalysts for oxygen reduction reaction in acidic fuel cells.

    Science.gov (United States)

    Shui, Jianglan; Wang, Min; Du, Feng; Dai, Liming

    2015-02-01

    The availability of low-cost, efficient, and durable catalysts for oxygen reduction reaction (ORR) is a prerequisite for commercialization of the fuel cell technology. Along with intensive research efforts of more than half a century in developing nonprecious metal catalysts (NPMCs) to replace the expensive and scarce platinum-based catalysts, a new class of carbon-based, low-cost, metal-free ORR catalysts was demonstrated to show superior ORR performance to commercial platinum catalysts, particularly in alkaline electrolytes. However, their large-scale practical application in more popular acidic polymer electrolyte membrane (PEM) fuel cells remained elusive because they are often found to be less effective in acidic electrolytes, and no attempt has been made for a single PEM cell test. We demonstrated that rationally designed, metal-free, nitrogen-doped carbon nanotubes and their graphene composites exhibited significantly better long-term operational stabilities and comparable gravimetric power densities with respect to the best NPMC in acidic PEM cells. This work represents a major breakthrough in removing the bottlenecks to translate low-cost, metal-free, carbon-based ORR catalysts to commercial reality, and opens avenues for clean energy generation from affordable and durable fuel cells.

  10. Dual responsive dysprosium-doped hydroxyapatite particles and toxicity reduction after functionalization with folic and glucuronic acids

    Energy Technology Data Exchange (ETDEWEB)

    Sánchez Lafarga, Ana Karen; Pacheco Moisés, Fermín P. [Departamento de Química, Universidad de Guadalajara, Marcelino García Barragán 1421, C.P. 44430, Guadalajara, Jalisco (Mexico); Gurinov, Andrey [Research Resources Center for Magnetic Resonance, Saint Petersburg State University, Universitetskij pr. 26, 198504 St. Petersburg (Russian Federation); Ortiz, Genaro Gabriel [Laboratorio Desarrollo-Envejecimiento, Enfermedades Neurodegenerativas, Centro de Investigación Biomédica de Occidente (CIBO), Instituto Mexicano de Seguro Social (IMSS), Guadalajara, Jalisco (Mexico); Carbajal Arízaga, Gregorio Guadalupe, E-mail: gregoriocarbajal@yahoo.com.mx [Departamento de Química, Universidad de Guadalajara, Marcelino García Barragán 1421, C.P. 44430, Guadalajara, Jalisco (Mexico)

    2015-03-01

    The development of probes for biomedical applications demands materials with low toxicity levels besides fluorescence or magnetic properties to be detected by confocal microscopes or MRI resonators. Several drug delivery systems or other biomedical materials prepared with hydroxyapatite have been proposed, however, toxicity effects might arise when the size of particles is nanometric. In this study, hydroxyapatite functionalized with glucuronic or folic acids presented lower oxidative stress, measured from lipoperoxides and nitric oxide indicators in rats than pure hydroxyapatite. In separated experiments, hydroxyapatite was doped with dysprosium cations by coprecipitation producing a single crystal phase with fluorescent properties easily visualized by confocal microscopy when excited at 488 nm. These particles also presented the ability to modify the proton relaxation time in T1 maps collected by magnetic resonance imaging. These modified hydroxyapatite nanoparticles could be candidates to design bimodal probes with low toxicity. - Highlights: • Hydroxyapatite functionalized with glucuronic acid reduced oxidative stress in rats. • Functionalization with folic acid reduced oxidative stress in rats. • Dysprosium doping does not affect the crystalline structure of hydroxyapatite. • Dysprosium doped particles are visible in fluorescent microscope. • Dysprosium doped particles act as MRI contrast agents.

  11. An efficient hydrogenation catalyst in sulfuric acid for the conversion of nitrobenzene to p-aminophenol: N-doped carbon with encapsulated molybdenum carbide.

    Science.gov (United States)

    Wang, Tao; Dong, Zhen; Cai, Weimeng; Wang, Yongzheng; Fu, Teng; Zhao, Bin; Peng, Luming; Ding, Weiping; Chen, Yi

    2016-08-23

    The transfer of catalytic function from molybdenum carbide to N-doped carbon has been tested by encapsulating molybdenum carbide with N-doped carbon using a one-pot preparation process. The outer layer of N-doped carbon, inert itself, exhibits high activity and excellent selectivity with molybdenum carbide as the catalyst for the hydrogenation of nitrobenzene to p-aminophenol in sulfuric acid.

  12. Enhancement in the critical current density of C-doped MgB2 wire using a polyacrylic acid dopant.

    Science.gov (United States)

    Lee, Seung Muk; Hwang, Soo Min; Lee, Chang Min; Kim, Won; Joo, Jinho; Lim, Jun Hyung; Kim, Chan-Joong; Hong, Gye-Won

    2012-02-01

    C-doped MgB2 wires were fabricated from a polyacrylic acid (PAA) using a conventional in-situ PIT technique. The effects of the PAA content on the lattice parameter, microstructure, critical temperature (Tc) and critical current density (Jc) were examined. With increasing PAA content, the amount of MgO in the sample increased but the crystallinity, a-axis lattice parameter, and Tc of MgB2 wires decreased, indicating that the C that decomposed from PAA during heat treatment had substituted for B. All doped samples exhibited a higher Jc than the undoped sample at high magnetic field, and the Jc(B) property improved with increasing PAA content: for the 7 wt% doped sample, the Jc was approximately 3-times higher than that of the pristine sample (1.28 kA/cm2 vs. 3.43 kA/cm2) at 5 K and 6.6 T. The improved Jc(B) of the doped sample was attributed to the decreased grain size, enlarged lattice distortion and increased C doping level.

  13. Construction and Study of Hetreojunction Solar Cell Based on Dodecylbenzene Sulfonic Acid-Doped Polyaniline/n-Si

    OpenAIRE

    Morsi, I.; Sh. Ebrahim; Soliman, M

    2012-01-01

    Polyaniline/n-type Si heterojunctions solar cell are fabricated by spin coating of soluble dodecylbenzene sulfonic acid (DBSA)-doped polyaniline onto n-type Si substrate. The electrical characterization of the Al/n-type Si/polyaniline/Au (Ag) structure was investigated by using current-voltage (I-V), capacitance-voltage (C-V), and impedance spectroscopy under darkness and illumination. The photovoltaic cell parameters, that is, open-circuit voltage (oc), short-circuit current density (sc), ...

  14. Thermoluminescence, optical absorption, photoluminescence, FT-IR and XRD studies on L-arginine doped orthophosphoric acid

    Energy Technology Data Exchange (ETDEWEB)

    Saradha, K. [Department of Physics, Selvamm Arts and Science College, Namakkal-637002, TN (India); Bangaru, S., E-mail: ssbangaru@yahoo.co.in [Department of Physics, Arignar Anna Government Arts College, Namakkal-637002, TN (India); Muralidharan, G. [Department of Physics, Gandhigram Rural University, Gandhigram-624302, TN (India)

    2013-10-15

    A paper report on the thermoluminescence (TL) optical absorption, photoluminescence (PL), single crystal XRD studies on L-arginine doped orthophosphoric acid confirm that a crystal belongs to the orthorhombic system with space group p2{sub 1}2{sub 1}2{sub 1}. The lattice of most of these crystals forming the composite, in spite of whatever the phase it belongs to, it is spatially coherent to each other with in the crystalline bulk. The functional groups present in the crystal confirms that using FT-IR technique optical absorbance shows meagre absorption from the entire visible region. The TL glow curve of L-arginine doped orthophosphoric acid sample marked a prominent peak at 125, 254 and 303 °C along with small peak at around 218 °C. Correlation with changes in optical absorption suggest that a peak at 125 °C to be related to process involving Z{sub 1} center. The peak follows first order kinetics with an activation energy of 0.033 eV and a frequency factor of 7.45×10{sup 2} and FWHM 61 nm. -- Highlights: • L-Arginine doped orthophosphoric acid has not been adequately studied. • A defect centre formed in L-arginine doped orthophosphoric acid system is assigned to F and Z{sub 1} centres. • The glow peaks are found to obey first order kinetics. • The Lattice parameter a=10.89 Å, b=7.91 Å, C=7.34 Å are in good agreement with the reported values. • The formation of a characteristic F- and centered at 520 nm is found. Such a detailed study and obtained results.

  15. Experimental characterization and modeling of commercial polybenzimidazole-based MEA performance

    DEFF Research Database (Denmark)

    Korsgaard, Anders; Refshauge, R. H.; Nielsen, Mads Pagh;

    2006-01-01

    High temperature polymer fuel cells based on polybenzimidazole membranes (PBI) operated at 100-200 °C are currently receiving much attention in relation to fuel cell reforming systems due to two main reasons. At first they have proven to have excellent resistance to high CO concentrations, which...... decreases the number of system components in the fuel processing system. The preferential oxidation reactors can be left out and in addition a water condenser is not required. These system simplifications additionally decrease the parasitic losses associated with the components.  However, insufficient data...... are currently published to enable good system design and modeling. In this paper the influence of operation on synthesis gas and the variation of the cathode stoichiometry are investigated based on a generic commercial membrane electrode assembly (MEA). The CO content in the anode gas was varied from 0 to 5...

  16. Electrochemical promotion of NO reduction by hydrogen on a platinum/polybenzimidazole catalyst

    DEFF Research Database (Denmark)

    Petrushina, Irina; Bandur, Viktor; Cappeln, Frederik Vilhelm;

    2003-01-01

    The electrochemical promotion of catalytic NO reduction by hydrogen was studied using a (NO, H-2, Ar), Pt polybenzimidazole (PBI)-H3PO4\\Pt, (H-2, Ar) fuel cell at 135degreesC. A mixture of NO/H-2/Ar was used as the working mixture at one electrode and a mixture of H-2/Ar was used as reference...... and 140 mL/min, respectively), NO reduction increased 20 times even without polarization compared to the high gas flow rate. The electrochemical promotion effect occurs at positive polarization with a maximum increase at approximately 0.08 V and with 1.5 times the zero polarization value. The promotion...... at the negative polarization can be attributed to the electrochemical production of the promoters. At low gas flow rates, a charge-induced change of the strength of chemisorptive bonds can take place....

  17. Polybenzimidazoles based on high temperature polymer electrolyte fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Linares Leon, Jose Joaquin; Camargo, Ana Paula M.; Ashino, Natalia M.; Morgado, Daniella L.; Frollini, Elisabeth; Paganin, Valdecir A.; Gonzalez, Ernesto Rafael [Universidade de Sao Paulo (IQSC/USP), Sao Carlos, SP (Brazil); Bajo, Justo Lobato [University of Castilla-La Mancha, Ciudad Real (Spain). Dept. of Chemical Engineering

    2010-07-01

    This work presents an interesting approach in order to enhance the performance of Polymer Electrolyte Membrane Fuel Cells (PEMFC) by means of an increase in the operational temperature. For this, two polymeric materials, Poly(2,5-bibenzimidazole) (ABPBI) and Poly[2,2'-(m-phenyl en)-5,5' bib enzimidazol] (PBI), impregnated with phosphoric acid have been utilized. These have shown excellent properties, such as thermal stability above 500 deg C, reasonably high conductivity when impregnated with H{sub 3}PO{sub 4} and a low permeability to alcohols compared to Nafion. Preliminary fuel cells measurements on hydrogen based Polymer Electrolyte Membrane Fuel Cell (PEMFC) displayed an interestingly reasonable good fuel cell performance, a quite reduced loss when the hydrogen stream was polluted with carbon monoxide, and finally, when the system was tested with an ethanol/water (E/W) fuel, it displayed quite promising results that allows placing this system as an attractive option in order to increase the cell performance and deal with the typical limitations of low temperature Nafion-based PEMFC. (author)

  18. Formation of core (polystyrene)-shell (polybenzimidazole) nanoparticles using sulfonated polystyrene as template.

    Science.gov (United States)

    Hazarika, Mousumi; Arunbabu, Dhamodaran; Jana, Tushar

    2010-11-15

    We report formation of core (polystyrene)-shell (polybenzimidazole) nanoparticles from a new blend system consisting of an amorphous polymer polybenzimidazole (PBI) and an ionomer sodium salt of sulfonated polystyrene (SPS-Na). The ionomer used for the blending is spherical in shape with sulfonate groups on the surface of the particles. An in depth investigation of the blends at various sulfonation degrees and compositions using Fourier transform infrared (FT-IR) spectroscopy provides direct evidence of specific hydrogen bonding interactions between the N-H groups of PBI and the sulfonate groups of SPS-Na. The disruption of PBI chains self association owing to the interaction between the functional groups of these polymer pairs is the driving force for the blending. Thermodynamical studies carried out by using differential scanning calorimeter (DSC) establish partially miscible phase separated blending of these polymers in a wider composition range. The two distinguishable glass transition temperatures (T(g)) which are different from the neat components and unaltered with the blends composition attribute that the domain size of heterogeneity (d(d)) of the blends is >20 nm since one of the blend component (SPS-Na particle) diameter is ∼70 nm. The diminish of PBI chains self association upon blending with SPS-Na particles and the presence of invariant T(g)'s of the blends suggest the wrapping of PBI chains over the SPS-Na spherical particle surface and hence resulting a core-shell morphology. Transmission electron microscopy (TEM) study provides direct evidence of core-shell nanoparticle formation; where core is the polystyrene and shell is the PBI. The sulfonation degree affects the blends phase separations. The higher degree of sulfonation favors the disruption of PBI self association and thus forms partially miscible two phases blends with core-shell morphology.

  19. Nitrogen doped graphene quantum dots based long-persistent chemiluminescence system for ascorbic acid imaging.

    Science.gov (United States)

    Chen, Hongjun; Wang, Qin; Shen, Qinpeng; Liu, Xin; Li, Wang; Nie, Zhou; Yao, Shouzhuo

    2017-05-15

    High photo-intensity and sluggish flight attenuation are important to highly sensitive chemluminescence imaging. Herein, we present a copper ion catalyzed long-persistent chemiluminescent imaging system of nitrogen-doped graphene quantum dots (NGQDs) for ascorbic acid detection in fruit. NGQDs as luminescent probe are fabricated, emitting out chemluminescence with the direct oxidation by H2O2. In addition, Cu(2+) ion enlarges over two order magnitudes of NGQDs CL intensity (214 times) due to its catalyzed Fenton-like reaction for H2O2 decomposition, and displaying unique specificity against other metal ions. As a result, the twinkling luminescence of NGQDs is boosted and changes to hold persistent with small decay in the presence of copper ion exhibiting potential for CL imaging. As an imaging model, a visual sensor based on Cu(2+)/NGQDs/H2O2 is developed for AA quantitative monitoring with a limit of detection (LOD) of 0.5μM (S/N=3) and applied in real AA detection in fruit. The CL imaging method demonstrated with high stability and proper sensitivity would provide a convenient and visual tool for AA determination, displaying promising candidates for imaging sensing.

  20. Simultaneous Chronoamperometric Sensing of Ascorbic Acid and Acetaminophen at a Boron-Doped Diamond Electrode

    Directory of Open Access Journals (Sweden)

    Ciprian Radovan

    2008-06-01

    Full Text Available Cyclic voltammetry (CV and chronoamperometry (CA have been used to sense and determine simultaneously L-ascorbic acid (AA and acetaminophen (AC at a boron-doped diamond electrode (BDDE in a Britton-Robinson buffer solution. The calibration plots of anodic current peak versus concentration obtained from CV and CA data for both investigated compounds in single and di-component solutions over the concentration range 0.01 mM – 0.1 mM proved to be linear, with very good correlation parameters. Sensitivity values and RSD of 2-3% were obtained for various situations, involving both individual and simultaneous presence of AA and AC. The chronoamperometric technique associated with standard addition in sequential one step and/or two successive and continuous chronoamperograms at two characteristic potential levels represented a feasible option for the simultaneous determination of AA and AC in real sample systems such as pharmaceutical formulations. The average values indicated by the supplier were confirmed to a very close approximation from chronoamperomgrams by using several additions with the application of suitable current correction factors.

  1. Photophysical characterization of cumarin-doped poly (lactic acid) microparticles and visualization of the biodistribution

    Energy Technology Data Exchange (ETDEWEB)

    Abe, Shigeaki, E-mail: sabe@den.hokudai.ac.j [Department of Biomedical Materials and Engineering, Graduate School of Dental Medicine, Hokkaido University, Kita 13, Nishi 7, Sapporo 060-8586 (Japan); Kiba, Takayuki; Hosokawa, Kiyotada; Nitobe, Satoru; Hirota, Takashi; Kobayashi, Hirohisa [Division of Biotechnology and Macromolecular Chemistry, Graduate School of Hokkaido University, Sapporo 060-8628 (Japan); Akasaka, Tsukasa; Uo, Motohiro; Kuboki, Yoshinori [Department of Biomedical Materials and Engineering, Graduate School of Dental Medicine, Hokkaido University, Kita 13, Nishi 7, Sapporo 060-8586 (Japan); Sato, Shin-Ichiro [Division of Biotechnology and Macromolecular Chemistry, Graduate School of Hokkaido University, Sapporo 060-8628 (Japan); Watari, Fumio [Department of Biomedical Materials and Engineering, Graduate School of Dental Medicine, Hokkaido University, Kita 13, Nishi 7, Sapporo 060-8586 (Japan); Rosca, Iosif D. [Faculty of Engineering and Computer Science, Concordia University, 1455 de Maisonneuve Blvd. W, Montreal, QC H3G 1M8 (Canada)

    2010-08-15

    We prepared fluorescent coumarin dye-doped poly (acrylic acid) microparticles, which are well known as a biodegradable polyester, and the photophysical properties were characterized by scanning electron microscope, atomic force microscope and spectroscopic investigation. Spherical particles with diameters ranging from 0.5 to a few {mu}m were obtained. Based on spectroscopic investigation, the internal environment was close to that of a polar solvent such as methanol, and the dyes were dispersed without aggregation inside the particles. The obtained particles were administered to a mouse through the tail vein, and the biodistribution was then observed after some organs were excited at 1-day and 1-week post-injection. The particles were accumulated in the organs, especially in the lung and spleen. After injection, the particles were trapped temporally in the lung, and then seemed to be transported to other organs by blood circulation. This tendency is similar to the biodistribution of TiO{sub 2} microparticles that we have reported previously.

  2. Development of Polybenzimidazole-Based High-Temperature Membrane and Electrode Assemblies for Stationary and Automotive Applications

    Energy Technology Data Exchange (ETDEWEB)

    Vogel, John A.

    2008-09-03

    The program began on August 1, 2003 and ended on July 31, 2007. The goal of the project was to optimize a high-temperature polybenzimidazole (PBI) membrane to meet the performance, durability, and cost targets required for stationary fuel cell applications. These targets were identified in the Fuel Cell section (3.4) of DOE’s Hydrogen, Fuel Cells and Infrastructure Technologies Program Multi-Year Research, Development and Demonstration Plan. A membrane that operates at high temperatures is important to the fuel cell industry because it is insensitive to carbon monoxide (a poison to low-temperature fuel cells), and does not require complex water management strategies. Together, these two benefits greatly simplify the fuel cell system. As a result, the high-temperature fuel cell system realizes a cost benefit as the number of components is reduced by nearly 30%. There is also an inherent reliability benefit as components such as humidifiers and pumps for water management are unnecessary. Furthermore, combined heat and power (CHP) systems may be the best solution for a commercial, grid-connected, stationary product that must offer a cost benefit to the end user. For a low-temperature system, the quality of the heat supplied is insufficient to meet consumer needs and comfort requirements, so peak heaters or supplemental boilers are required. The higher operating temperature of PBI technology allows the fuel cell to meet the heat and comfort demand without the additional equipment. Plug Power, working with the Rensselaer Polytechnic Institute (RPI) Polymer Science Laboratory, made significant advances in optimizing the PBI membrane material for operation at temperatures greater than 160oC with a lifetime of 40,000 hours. Supporting hardware such as flow field plates and a novel sealing concept were explored to yield the lower-cost stack assembly and corresponding manufacturing process. Additional work was conducted on acid loss, flow field design and cathode electrode

  3. Low thermal budget n-type doping into Ge(001) surface using ultraviolet laser irradiation in phosphoric acid solution

    Energy Technology Data Exchange (ETDEWEB)

    Takahashi, Kouta, E-mail: ktakahas@alice.xtal.nagoya-u.ac.jp, E-mail: kurosawa@alice.xtal.nagoya-u.ac.jp; Sakashita, Mitsuo; Takeuchi, Wakana; Nakatsuka, Osamu [Graduate School of Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603 (Japan); Kurosawa, Masashi, E-mail: ktakahas@alice.xtal.nagoya-u.ac.jp, E-mail: kurosawa@alice.xtal.nagoya-u.ac.jp [Graduate School of Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603 (Japan); Institute of Materials and Systems for Sustainability, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603 (Japan); Institute for Advanced Research, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8601 (Japan); Ikenoue, Hiroshi [Graduate School of Information Science and Electrical Engineering, Kyushu University, 744 Motooka, Fukuoka 819-0395 (Japan); Zaima, Shigeaki [Graduate School of Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603 (Japan); Institute of Materials and Systems for Sustainability, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603 (Japan)

    2016-02-01

    We have investigated phosphorus (P) doping into Ge(001) surfaces by using ultraviolet laser irradiation in phosphoric acid solution at room temperature. We demonstrated that the diffusion depth of P in Ge and the concentration of electrically activated P can be controlled by the number of laser shots. Indeed, a high concentration of electrically activated P of 2.4 × 10{sup 19} cm{sup −3} was realized by 1000-times laser shots at a laser energy of 1.0 J/cm{sup 2}, which is comparable or better than the counterparts of conventional n-type doping using a high thermal budget over 600 °C. The generation current is dominant in the reverse bias condition for the laser-doped pn-junction diodes independent on the number of laser shots, thus indicating low-damage during the pn-junction formation. These results open up the possibility for applicable low thermal budget doping process for Ge-based devices fabricated on flexible substrates as well as Si electronics.

  4. Ab initio study of the binding of collagen amino acids to graphene and A-doped (A = H, Ca) graphene

    Energy Technology Data Exchange (ETDEWEB)

    Cazorla, Claudio, E-mail: c.silva@ucl.ac.u

    2010-09-30

    We present a theoretical study of the binding of collagen amino acids (AA, namely glycine, Gly; proline, Pro; and hydroxyproline, Hyp) to graphene (Gr), Ca-doped graphene and graphane (Gra) using density functional theory calculations and ab initio molecular dynamics (AIMD) simulations. It is found that binding of Gly, Pro and Hyp to Gr and Gra is thermodynamically favorable yet dependent on the amino acid orientation and always very weak (adsorption energies E{sub ads} range from -90 to -20 meV). AIMD simulations reveal that room-temperature thermal excitations are enough to induce detachment of Gly and Pro from Gr and of all three amino acids from Gra. Interestingly, we show that collagen AA binding to Gr is enhanced dramatically by doping the carbon surface with calcium atoms (corresponding E{sub ads} values decrease by practically two orders of magnitude with respect to the non-doped case). This effect is result of electronic charge transfers from the Ca impurity (donor) to Gr (acceptor) and the carboxyl group (COOH) of the amino acid (acceptor). The possibility of using Gr and Gra as nanoframes for sensing of collagen amino acids has also been investigated by performing electronic density of states analysis. It is found that, whether Gr is hardly sensitive, the electronic band gap of Gra can be modulated by attaching different number and species of AAs onto it. The results presented in this work provide fundamental insights on the quantum interactions of collagen protein components with carbon-based nanostructures and can be useful for developments in bio and nanotechnology fields.

  5. Fabrication and characterization of Sb-doped Sn02 thin films derived from methacrylic acid modified tin(IV)alkoxides

    Science.gov (United States)

    Kololuoma, Terho K.; Tolonen, Ari; Johansson, Leena-Sisko; Campbell, Joseph M.; Karkkainen, Ari H. O.; Hiltunen, Marianne; Haatainen, Tomi; Rantala, Juha T.

    2002-10-01

    We report on the fabrication of transparent, conductive and directly photopatternable, pure and Sb-doped tin dioxide thin films. Precursors used were antimony(III)isopropoxide and a photo-reactive tin alkoxide synthesized from tin(IV)isopropoxide and methacrylic acid. The synthesis of methacrylic acid modified tin alkoxide was monitored in-situ using IR- and ESI-TOF mass spectroscopic techniques. Sb-doped organo-tin films were deposited via single layer spin coating. After deposition the films were patterned via photopolymerization, using a mercury I-line UV-lamp. All investigated materials could be patterned with 3 μm features. After development in isopropanol, the films were annealed in air, in order to obtain crystalline and conductive films. The electrical conductivities of the annealed thin films with, and without, UV-irradiation were determined using a linear four-point method. The direct photopatterning process was found to increase the film conductivity for all the Sb-doping levels tested. The mechanisms for the increased conductivity were characterized using AFM, XPS and XRD techniques.

  6. Long-term testing of a high-temperature proton exchange membrane fuel cell short stack operated with improved polybenzimidazole-based composite membranes

    Science.gov (United States)

    Pinar, F. Javier; Cañizares, Pablo; Rodrigo, Manuel A.; Úbeda, Diego; Lobato, Justo

    2015-01-01

    In this work, the feasibility of a 150 cm2 high-temperature proton exchange membrane fuel cell (HT-PEMFC) stack operated with modified proton exchange membranes is demonstrated. The short fuel cell stack was manufactured using a total of three 50 cm2 membrane electrode assemblies (MEAs). The PEM technology is based on a polybenzimidazole (PBI) membrane. The obtained results were compared with those obtained using a HT-PEMFC stack with unmodified membranes. The membranes were cast from a PBI polymer synthesized in the laboratory, and the modified membranes contained 2 wt.% micro-sized TiO2 as a filler. Long-term tests were performed in both constant and dynamic loading modes. The fuel cell stack with 2 wt.% TiO2 composite PBI membranes exhibited an irreversible voltage loss of less than 2% after 1100 h of operation. In addition, the acid loss was reduced from 2% for the fuel cell stack with unmodified membranes to 0.6% for the fuel cell stack with modified membranes. The results demonstrate that introducing filler into the membranes enhances the durability and stability of this type of fuel cell technology. Moreover, the fuel cell stack system also exhibits very rapid and stable power and voltage output responses under dynamic load regimes.

  7. Synthesis of novel cobalt doped zinc oxide/carbon nano composite for the photocatalytic degradation of acid blue 113

    Directory of Open Access Journals (Sweden)

    S. Sunitha

    2015-03-01

    Full Text Available Cobalt doped Zinc Oxide/Carbon nano composite was synthesized by solution combustion method and characterized by X-ray diffractometer, field emission scanning electron microscope and energy dispersive X-ray spectroscopy analysis. This composite shows X-ray diffraction pattern that matched with nano particle of ZnO with wurtzite structure and average grain size was found to be 10.53 nm. . Further the presence of the elements like C, Co, Zn and O was confirmed by energy dispersive X-ray spectroscopy analysis. The effect of Co doping on the photocatalytic activity was investigated by photo degradation of the dye, acid blue 113. This nano composite exhibited better photocatalytic activity when compared to nano ZnO and nano ZnO/C composites.

  8. Nitrogen-doped carbon nanofoam derived from amino acid chelate complex for supercapacitor applications

    Science.gov (United States)

    Ramakrishnan, Prakash; Shanmugam, Sangaraju

    2016-06-01

    We report a novel strategy to fabricate the nitrogen-doped mesoporous carbon nanofoam structures (N-MCNF), derived from magnesium amino acid chelate complex (Mg-acc-complex) for its application towards high performance supercapacitor (SCs) system. A series of N-MCNF with well-connected carbon nanofoam structure have been developed by varying the synthesis temperature. The fabricated N-MCNF material possesses a high surface area (1564 m2 g-1) and pore volume (1.767 cm3 g-1) with nitrogen content of 3.42 wt%. A prototypical coin cell type symmetric N-MCNF SC device has been assembled with 1-ethyl-3-methylimidazolium tetrafluoroborate [EMIMBF4] ionic liquid electrolyte, and evaluated for SCs studies. The N-MCNF with high textural properties delivers unprecedented SC performance, such as high specific capacitance (204 Fg-1 at 0.25 Ag-1, 25 °C), high energy density (63.4 Wh kg-1), high power density (35.9 kW kg-1) and long-term cycle life (32,500 cycles). Significantly, N-MCNF materials exhibited high power rate performance, at 500 mV-1 (115 Fg-1) and 25 Ag-1 (166 Fg-1) owing to the uniform mesopore size distribution (∼4 nm). The N-MCNF SC device delivered maximum energy densities of 83.4 and 93.3 Wh kg-1 at 60 °C and 90 °C, respectively. Such outstanding N-MCNF SC device is successfully demonstrated in solar energy harvester applications.

  9. N-Co-O Triply Doped Highly Crystalline Porous Carbon: An Acid-Proof Nonprecious Metal Oxygen Evolution Catalyst.

    Science.gov (United States)

    Yang, Shiliu; Zhan, Yi; Li, Jingfa; Lee, Jim Yang

    2016-02-10

    In comparison with nonaqueous Li-air batteries, aqueous Li-air batteries are kinetically more facile and there is more variety of non-noble metal catalysts available for oxygen electrocatalysis, especially in alkaline solution. The alkaline battery environment is however vulnerable to electrolyte carbonation by atmospheric CO2 resulting in capacity loss over time. The acid aqueous solution is immune to carbonation but is limited by the lack of effective non-noble metal catalysts for the oxygen evolution reaction (OER). This is contrary to the oxygen reduction reaction (ORR) in acid solution where a few good candidates exist. We report here the development of a N-Co-O triply doped carbon catalyst with substantial OER activity in acid solution by the thermal codecomposition of polyaniline, cobalt salt and cyanamide in nitrogen. Cyanamide and the type of cobalt precursor salt were found to determine the structure, crystallinity, surface area, extent of Co doping and consequently the OER activity of the final carbon catalyst in acid solution. We have also put forward some hypotheses about the active sites that may be useful for guiding further work.

  10. Polybenzimidazole compounds

    Science.gov (United States)

    Klaehn, John R.; Peterson, Eric S.; Wertsching, Alan K.; Orme, Christopher J.; Luther, Thomas A.; Jones, Michael G.

    2010-08-10

    A PBI compound that includes imidazole nitrogens, at least a portion of which are substituted with an organic-inorganic hybrid moiety. At least 85% of the imidazole nitrogens may be substituted. The organic-inorganic hybrid moiety may be an organosilane moiety, for example, (R)Me.sub.2SiCH.sub.2--, where R is selected from among methyl, phenyl, vinyl, and allyl. The PBI compound may exhibit similar thermal properties in comparison to the unsubstituted PBI. The PBI compound may exhibit a solubility in an organic solvent greater than the solubility of the unsubstituted PBI. The PBI compound may be included in separatory media. A substituted PBI synthesis method may include providing a parent PBI in a less than 5 wt % solvent solution. Substituting may occur at about room temperature and/or at about atmospheric pressure. Substituting may use at least five equivalents in relation to the imidazole nitrogens to be substituted or, preferably, about fifteen equivalents.

  11. Raman scattering investigations of the interaction of a COV with pure and acid doped ice particles

    Science.gov (United States)

    Facq, S.; Oancea, A.; Focsa, C.; Chazallon, B.

    2009-04-01

    Ice present in polar stratosphere is as well a common component of the troposphere, particularly in cirrus clouds widespread in tropopause and upper troposphere region. With water droplets, ice constitutes the condensed matter that can interact with atmospheric trace gases via many different trapping processes (co-deposition i.e; incorporation during growing ice conditions, adsorption, freezing etc). The incorporation of trace gases in ice surface/volume can both affect the atmospheric chemistry and the ice structure and reactivity. This can therefore modify the nature and composition of the incorporated species in ice, or in the gas phase. Recently, field measurements have demonstrated the presence of nitric acid in ice particles from cirrus clouds(1,2) (concentration between 0.63 wt% and 2.5 wt %). Moreover, laboratory experiments have shown that the uptake of atmospheric trace gases can be enhanced up to 1 or 2 orders of magnitude in these doped ice particles. Among trace gases capable to interact with atmospheric condensed matter figure volatile organic compounds such as aldehydes, ketones and alcohols (ex: ethanol and methanol). They play an important role in the upper troposphere (3,4) and snowpack chemistry (5) as they can be easily photolysed, producing free radicals and so influence the oxidizing capacity and the ozone-budget of the atmosphere (3,4). The temperature range at which these physico-chemical processes occur extents between ~ 190 K and 273K. Interaction between ice and trace gases are therefore largely dependent on the ice surface properties as well as on the phase formation dynamic (crystalline or not). This study aims to examine and characterize the incorporation of a COV (ex: ethanol), at the surface or in the volume of ice formed by different growth mechanisms (vapour deposition or droplets freezing). Vibrational spectra of water OH and ethanol CH-spectral regions are analysed using confocal micro-Raman spectroscopy at different temperatures

  12. Lanthanum-doped mesostructured strontium titanates synthesized via sol–gel combustion route using citric acid as complexing agent

    Energy Technology Data Exchange (ETDEWEB)

    Sukpanish, Polthep [Department of Chemical Technology, Faculty of Science, Chulalongkorn University, Patumwan, Bangkok 10330 (Thailand); Center of Excellence on Petrochemical and Materials Technology (PETROMAT), Chulalongkorn University, Patumwan, Bangkok 10330 (Thailand); Lertpanyapornchai, Boontawee [Program in Petrochemistry, Faculty of Science, Chulalongkorn University, Patumwan, Bangkok 10330 (Thailand); Yokoi, Toshiyuki [Division of Catalytic Chemistry, Chemical Resources Laboratory, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, Yokohama 226-8503 (Japan); Ngamcharussrivichai, Chawalit, E-mail: Chawalit.Ng@chula.ac.th [Department of Chemical Technology, Faculty of Science, Chulalongkorn University, Patumwan, Bangkok 10330 (Thailand); Center of Excellence on Petrochemical and Materials Technology (PETROMAT), Chulalongkorn University, Patumwan, Bangkok 10330 (Thailand)

    2016-09-15

    In the present work, a series of lanthanum-doped mesostructured strontium titanate (LMST) materials with different La/Sr ratios were synthesized via a sol–gel combustion method in the presence of citric acid as a complexing agent and Pluronic P123 as a templating agent. The effects of the amount of doped La and calcination temperature on the physicochemical properties of the LMSTs were examined using various techniques. Powder X-ray diffraction confirmed the substitution of La{sup 3+} into the SrTiO{sub 3} lattice, generating cubic perovskite La{sub x}Sr{sub 1−x}TiO{sub 3}, for the LMST materials calcined at 600 °C. The purity and crystallinity of the desired perovskite phase were enhanced by citric acid addition. The solubility limit of La{sup 3+} substitution at an La/Sr ratio of 0.43 was determined by structural and morphological studies. Increasing the La doping amount decreased the crystallinity and compositional homogeneity, because an La-rich amorphous phase segregated on the surface, but improved the mesoporosity. N{sub 2} physisorption measurements indicated that the LMSTs had a bimodal pore size distribution, of which the larger one was characterized by the crystallite size of mixed oxides, and the specific surface area of 24.9–37.3 m{sup 2} g{sup −1}. The formation of mesopores in the LMST materials synthesized via sol–gel combustion was explained based on a combination of soft- and hard-templating chemistries. - Highlights: • La-doped mesoporous SrTiO{sub 3} (LMST) was prepared first time via sol-gel combustion. • Pluronic P123 triblock copolymer was used as a cheap templating agent. • Citric acid as a complexing agent enhanced the purity and crystallinity of SrTiO{sub 3}. • The textural properties of LMST were improved by increasing the La doping amount. • Mesopore formation was explained by a combined soft- and hard-templating route.

  13. Mineralization of the recalcitrant oxalic and oxamic acids by electrochemical advanced oxidation processes using a boron-doped diamond anode.

    Science.gov (United States)

    Garcia-Segura, Sergi; Brillas, Enric

    2011-04-01

    Oxalic and oxamic acids are the ultimate and more persistent by-products of the degradation of N-aromatics by electrochemical advanced oxidation processes (EAOPs). In this paper, the kinetics and oxidative paths of these acids have been studied for several EAOPs using a boron-doped diamond (BDD) anode and a stainless steel or an air-diffusion cathode. Anodic oxidation (AO-BDD) in the presence of Fe(2+) (AO-BDD-Fe(2+)) and under UVA irradiation (AO-BDD-Fe(2+)-UVA), along with electro-Fenton (EF-BDD), was tested. The oxidation of both acids and their iron complexes on BDD was clarified by cyclic voltammetry. AO-BDD allowed the overall mineralization of oxalic acid, but oxamic acid was removed much more slowly. Each acid underwent a similar decay in AO-BDD-Fe(2+) and EF-BDD, as expected if its iron complexes were not attacked by hydroxyl radicals in the bulk. The faster and total mineralization of both acids was achieved in AO-BDD-Fe(2+)-UVA due to the high photoactivity of their Fe(III) complexes that were continuously regenerated by oxidation of their Fe(II) complexes. Oxamic acid always released a larger proportion of NH(4)(+) than NO(3)(-) ion, as well as volatile NO(x) species. Both acids were independently oxidized at the anode in AO-BDD, but in AO-BDD-Fe(2+)-UVA oxamic acid was more slowly degraded as its content decreased, without significant effect on oxalic acid decay. The increase in current density enhanced the oxidation power of the latter method, with loss of efficiency. High Fe(2+) contents inhibited the oxidation of Fe(II) complexes by the competitive oxidation of Fe(2+) to Fe(3+). Low current densities and Fe(2+) contents are preferable to remove more efficiently these acids by the most potent AO-BDD-Fe(2+)-UVA method.

  14. Effect of sorbic acid doping on flux pinning in bulk MgB{sub 2} with the percolation model

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Y. [Key Laboratory of Advanced Technologies of Materials (Ministry of Education of China), Mail Stop 165, Southwest Jiaotong University, Chengdu, Sichuan 610031 (China); Key Laboratory of Magnetic Levitation and Maglev Train (Ministry of Education of China), Mail Stop 165, Southwest Jiaotong University, Chengdu, Sichuan 610031 (China); Superconductivity R and D Center (SRDC), Mail Stop 165, Southwest Jiaotong University, Chengdu, Sichuan 610031 (China); Cheng, C.H. [School of Materials Science and Engineering, University of New South Wales, Sydney, 2052 NSW (Australia); Wang, L.; Sun, H.H. [Key Laboratory of Advanced Technologies of Materials (Ministry of Education of China), Mail Stop 165, Southwest Jiaotong University, Chengdu, Sichuan 610031 (China); Key Laboratory of Magnetic Levitation and Maglev Train (Ministry of Education of China), Mail Stop 165, Southwest Jiaotong University, Chengdu, Sichuan 610031 (China); Superconductivity R and D Center (SRDC), Mail Stop 165, Southwest Jiaotong University, Chengdu, Sichuan 610031 (China); Zhao, Y., E-mail: yzhao@swjtu.edu.c [Key Laboratory of Advanced Technologies of Materials (Ministry of Education of China), Mail Stop 165, Southwest Jiaotong University, Chengdu, Sichuan 610031 (China); Key Laboratory of Magnetic Levitation and Maglev Train (Ministry of Education of China), Mail Stop 165, Southwest Jiaotong University, Chengdu, Sichuan 610031 (China); Superconductivity R and D Center (SRDC), Mail Stop 165, Southwest Jiaotong University, Chengdu, Sichuan 610031 (China); School of Materials Science and Engineering, University of New South Wales, Sydney, 2052 NSW (Australia)

    2010-11-01

    In this paper, we study the doping effect of sorbic acid (C{sub 6}H{sub 8}O{sub 2}), from 0 to 20 wt.% of the total MgB{sub 2}, on critical temperature (T{sub c}), critical current density (J{sub c}), irreversibility field (H{sub irr}) and crystalline structure. The XRD patterns of samples show a slightly decrease in a-axis lattice parameter for doped samples, due to the partial substitution of carbon at boron site. On the other hand, we investigate the influence of doping on the behavior of flux pinning and J{sub c}(B) in the framework of percolation theory and it is found that the J{sub c}(B) behavior could be well fitted in high field region. The two key parameters, anisotropy and percolation threshold, play very important roles. It is believed that the enhancement of J{sub c} is due to the reduction of anisotropy in high field region.

  15. Spatial self-phase modulation in the H2TPP(OH)4 doped in Boric Acid Glass

    CERN Document Server

    Allam, Srinivasa Rao; Venkatramaiah, N; Venkatesan, R; Sharan, Alok

    2015-01-01

    Self-diffraction rings or spatial self-phase modulation (SSPM) was observed in tetra-phenyl porphyrin derivative 5,10,15,20 - meso-tetrakis (4-hydroxyphenyl) porphyrin (H2TPP(OH)4) doped in boric acid glass (BAG) at 671 nm excitation wave-length lying within the absorption band of sample with TEM00 mode profile. Intensity modulated Z-scan was performed on these systems to study the thermal diffusion and to estimate the thermo-optic coefficients. The results obtained from self-diffraction rings experiment and modulated Z-scan are compared and analyzed for different concentration.

  16. Exceptional durability enhancement of PA/PBI based polymer electrolyte membrane fuel cells for high temperature operation at 200°C

    DEFF Research Database (Denmark)

    Aili, David; Zhang, Jin; Jakobsen, Mark Tonny Dalsgaard

    2016-01-01

    The incorporation of phosphotungstic acid functionalized mesoporous silica in phosphoric acid doped polybenzimidazole (PA/PBI) substantially enhances the durability of PA/PBI based polymer electrolyte membrane fuel cells for high temperature operation at 200°C.......The incorporation of phosphotungstic acid functionalized mesoporous silica in phosphoric acid doped polybenzimidazole (PA/PBI) substantially enhances the durability of PA/PBI based polymer electrolyte membrane fuel cells for high temperature operation at 200°C....

  17. Synthesis and Photophysical Properties of Dy3+ and Gd3+ Polymeric Complexes with Functionalized Polybenzimidazole Containing β-Diketone Side Group

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The polymeric ligand PBIa (functionalized polybenzimidazole containing β-diketone side group) was successfully synthesized via the reaction of polybenzimidazole (PBI) with 3-Br-acetylacetone in DMSO solvent using NaH as the deprotonation reagent. Its corresponding polymeric complexes of Dy3+ and Gd3+ were prepared and characterized by FT-IR, 1H NMR, molar conductance measurements, and thermal analysis. The photoluminescence properties and the probable mechanism of the Dy and Gd complexes were studied. The measurement and analysis of the thermal properties showed that these were thermal stable.

  18. Enhanced forward osmosis from chemically modified polybenzimidazole (PBI) nanofiltration hollow fiber membranes with a thin wall

    KAUST Repository

    Wang, Kai Yu

    2009-04-01

    To develop high-flux and high-rejection forward osmosis (FO) membranes for water reuses and seawater desalination, we have fabricated polybenzimidazole (PBI) nanofiltration (NF) hollow fiber membranes with a thin wall and a desired pore size via non-solvent induced phase inversion and chemically cross-linking modification. The cross-linking by p-xylylene dichloride can finely tune the mean pore size and enhance the salt selectivity. High water permeation flux and improved salt selectivity for water reuses were achieved by using the 2-h modified PBI NF membrane which has a narrow pore size distribution. Cross-linking at a longer time produces even a lower salt permeation flux potentially suitable for desalination but at the expense of permeation flux due to tightened pore sizes. It is found that draw solution concentration and membrane orientations are main factors determining the water permeation flux. In addition, effects of membrane morphology and operation conditions on water and salt transport through membrane have been investigated. © 2008 Elsevier Ltd. All rights reserved.

  19. Experimental characterization and modeling of commercial polybenzimidazole-based MEA performance

    Science.gov (United States)

    Korsgaard, Anders R.; Refshauge, Rasmus; Nielsen, Mads P.; Bang, Mads; Kær, Søren K.

    High temperature polymer fuel cells based on polybenzimidazole membranes (PBI) operated at 100-200 °C are currently receiving much attention in relation to fuel cell reforming systems due to two main reasons. At first they have proven to have excellent resistance to high CO concentrations, which decreases the number of system components in the fuel processing system. The preferential oxidation reactors can be left out and in addition a water condenser is not required. These system simplifications additionally decrease the parasitic losses associated with the components. However, insufficient data are currently published to enable good system design and modeling. In this paper the influence of operation on synthesis gas and the variation of the cathode stoichiometry are investigated based on a generic commercial membrane electrode assembly (MEA). The CO content in the anode gas was varied from 0 to 5%, with CO 2 contents ranging from 25 to 20% at temperatures ranging from 160 to 200 °C. The influence of the cathode stoichiometry was investigated in the interval of 2-5 at temperatures from 120 to 180 °C with pure hydrogen on the anode. A novel semi empirical model of the fuel cell voltage versus current density, cathode stoichiometry and temperature was derived. It shows excellent agreement with the experimental data. The simplicity and accuracy of the model makes it ideal for system modeling, control design and real-time applications.

  20. Catalytic reduction of NO by methane using a Pt/C/polybenzimidazole/Pt/C fuel cell

    DEFF Research Database (Denmark)

    Petrushina, Irina; Cleemann, Lars Nilausen; Refshauge, Rasmus;

    2007-01-01

    The catalytic NO reduction by methane was studied using a (NO,CH4,Ar),Pt|polybenzimidazole(PBI)–H3PO4|Pt,(H2,Ar) fuel cell at 135 and 165°C. It has been found that, without any reducing agent (like CH4), NO can be electrochemically reduced in the (NO, Ar), Pt/C|PBI–H3PO4|Pt/C, (H2,Ar) fuel cell...... with participation of H+ or electrochemically produced hydrogen. When added, methane partially suppresses the electrochemical reduction of NO. Methane outlet concentration monitoring has shown the CH4 participation in the chemical catalytic reduction, i.e., methane co-adsorption with NO inhibited the electrochemical...... NO reduction and introduced a dominant chemical path of the NO reduction. The products of the NO reduction with methane were N2, C2H4, and water. The catalytic NO reduction by methane was promoted when the catalyst was negatively polarized (−0.2 V). Repeated negative polarization of the catalyst increased...

  1. DEVELOPMENT AND SELECTION OF IONIC LIQUID ELECTROLYTES FOR HYDROXIDE CONDUCTING POLYBENZIMIDAZOLE MEMBRANES IN ALKALINE FUEL CELLS

    Energy Technology Data Exchange (ETDEWEB)

    Fox, E.

    2012-05-01

    Alkaline fuel cell (AFC) operation is currently limited to specialty applications such as low temperatures and pure HO due to the corrosive nature of the electrolyte and formation of carbonates. AFCs are the cheapest and potentially most efficient (approaching 70%) fuel cells. The fact that non-Pt catalysts can be used, makes them an ideal low cost alternative for power production. The anode and cathode are separated by and solid electrolyte or alkaline porous media saturated with KOH. However, CO from the atmosphere or fuel feed severely poisons the electrolyte by forming insoluble carbonates. The corrosivity of KOH (electrolyte) limits operating temperatures to no more than 80°C. This chapter examines the development of ionic liquids electrolytes that are less corrosive, have higher operating temperatures, do not chemically bond to CO and enable alternative fuels. Work is detailed on the IL selection and characterization as well as casting methods within the polybenzimidazole based solid membrane. This approach is novel as it targets the root of the problem (the electrolyte) unlike other current work in alkaline fuel cells which focus on making the fuel cell components more durable.

  2. Highly efficient electrochemical degradation of perfluorooctanoic acid (PFOA) by F-doped Ti/SnO2 electrode.

    Science.gov (United States)

    Yang, Bo; Jiang, Chaojin; Yu, Gang; Zhuo, Qiongfang; Deng, Shubo; Wu, Jinhua; Zhang, Hong

    2015-12-15

    The novel F-doped Ti/SnO2 electrode prepared by SnF4 as the single-source precursor was used for electrochemical degradation of aqueous perfluorooctanoic acid (PFOA). Higher oxidation reactivity and significantly longer service life were achieved for Ti/SnO2-F electrode than Ti/SnO2-X (X=Cl, Br, I, or Sb) electrode, which could decomposed over 99% of PFOA (50 mL of 100 mg L(-1)) within 30-min electrolysis. The property of Ti/SnO2-F electrode and its electrooxidation mechanism were investigated by XRD, SEM-EDX, EIS, LSV, and interfacial resistance measurements. We propose that the similar ionic radii of F and O as well as strong electronegativity of F caused its electrochemical stability with high oxygen evolution potential (OEP) and smooth surface to generate weakly adsorbed OH. The preparation conditions of electrode were also optimized including F doping amount, calcination temperature, and dip coating times, which revealed the formation process of electrode. Additionally, the major mineralization product, F(-), and low concentration of shorter chain perfluorocarboxylic acids (PFCAs) were detected in solution. So the reaction pathway of PFOA electrooxidation was proposed by intermediate analysis. These results demonstrate that Ti/SnO2-F electrode is promising for highly efficient treatment of PFOA in wastewater.

  3. A Study on Tannic Acid-doped Polypyrrole Films on Gold Electrodes for Selective Electrochemical Detection of Dopamine

    Directory of Open Access Journals (Sweden)

    Shouzhuo Yao

    2005-04-01

    Full Text Available Tannic acid-doped polypyrrole (PPY/TA films have been grown on goldelectrodes for selective electrochemical detection of dopamine (DA. Electrochemicalquartz crystal microbalance (EQCM studies revealed that, in vivid contrast toperchlorate-doped polypyrrole films (PPY/ClO4-, the redox switching of PPY/TA filmsin aqueous solutions involved only cation transport if the solution pH was greater than3~4. The PPY/TA Au electrodes also exhibited attractive permselectivity forelectroactive cations, namely, effectively blocking the electrochemical reactions ofanionic ferricyanide and ascorbic acid (AA while well retaining the electrochemicalactivities of hexaammineruthenium (III and dopamine as cationic species. A 500 HzPPY/TA film could effectively block the redox current of up to 5.0 mM AA. Thecoexistence of ascorbic acid in the measurement solution notably enhanced the currentsignal for dopamine oxidation, due probably to the chemical regeneration of dopaminethrough an ascorbic acid-catalyzed reduction of the electro-oxidation product ofdopamine (EC’ mechanism, and the greatest amplification was found at an ascorbic acidconcentration of 1.0 mM. The differential pulse voltammetry peak current for DAoxidation was linear with DA concentration in the range of 0 to 10 μM, with sensitivityof 0.125 and 0.268 μA/μM, as well as lower detection limit of 2.0 and 0.3 μM in a PBSsolution without AA and with 1.0 mM coexisting AA, respectively.

  4. Structural recovery of self-irradiated natural and {sup 238}Pu-doped zircon in an acidic solution at 175 deg. C

    Energy Technology Data Exchange (ETDEWEB)

    Geisler, Thorsten [Institut fuer Mineralogie, University of Muenster, Corrensstrasse 24, 48149 Muenster (Germany)]. E-mail: tgeisler@nwz.uni-muenster.de; Burakov, Boris [Laboratory of Applied Mineralogy and Radiogeochemistry, V.G. Khlopin Radium Institute, 28, 2nd Murinskiy ave., St. Petersburg, 194021 (Russian Federation); Yagovkina, Maria [Laboratory of Applied Mineralogy and Radiogeochemistry, V.G. Khlopin Radium Institute, 28, 2nd Murinskiy ave., St. Petersburg, 194021 (Russian Federation); Garbuzov, Vladimir [Laboratory of Applied Mineralogy and Radiogeochemistry, V.G. Khlopin Radium Institute, 28, 2nd Murinskiy ave., St. Petersburg, 194021 (Russian Federation); Zamoryanskaya, Maria [Laboratory of Applied Mineralogy and Radiogeochemistry, V.G. Khlopin Radium Institute, 28, 2nd Murinskiy ave., St. Petersburg, 194021 (Russian Federation); Zirlin, Vladimir [Laboratory of Applied Mineralogy and Radiogeochemistry, V.G. Khlopin Radium Institute, 28, 2nd Murinskiy ave., St. Petersburg, 194021 (Russian Federation); Nikolaeva, Larisa [Laboratory of Applied Mineralogy and Radiogeochemistry, V.G. Khlopin Radium Institute, 28, 2nd Murinskiy ave., St. Petersburg, 194021 (Russian Federation)

    2005-01-01

    We have investigated the aqueous stability of self-irradiated natural and synthetic {sup 238}Pu-doped zircon (4.7 wt% of {sup 238}Pu) in an acidic solution at 175 deg. C. Both zircon samples have suffered a similar deg.ree of self-irradiation damage, as given by their deg.ree of amorphization. X-ray diffraction measurements revealed that during the hydrothermal treatment only the disordered crystalline remnants recovered in the natural zircon, whereas in the {sup 238}Pu-doped zircon the amorphous phase strongly recrystallized. Such a different alteration behavior of natural and Pu-doped zircon is discussed in terms of two fundamentally different alteration mechanisms. Our results demonstrate that further experimental studies with Pu-doped zircon are required before any reliable prediction about the long-term aqueous stability of an actinide waste form based on zircon can be made.

  5. Anticorrosion property of polyaniline doped twice with functional acid%功能酸二次掺杂聚苯胺的防腐蚀性能

    Institute of Scientific and Technical Information of China (English)

    杨显; 杨小刚; 马新起

    2014-01-01

    As polyaniline (PANI) has unique doping and dedoping characteristics, good morphology nanofibers can be synthesized under specific reaction conditions and new nanomaterials with special anticorrosion functional groups can be prepared via the dedoping and twice doping process. PANI nanofibers doped with sulfuric acid were dedoped by ammonia solution, and based on this dedoped PANI, twice doped PANI were prepared in phosphoric acid, p-toluene sulfonic acid and tartaric acid system respectively. The structure of doped and twice doped PANI was characterized by FT-IR spectrometer and UV-Vis absorption spectrometer. An electrochemical workstation was used to record the open circuit potential (OCP) and the electrochemical impedance spectroscopy (EIS) of polyaniline/epoxy composite coatings, and their anticorrosion mechanism were investigated theoretically. FT-IR spectra and UV-Vis spectra indicated that the state of PANI was doped PANI in its emeraldine salt form. The electrochemical testing results showed that every coating had certain anticorrosion performance and the impedance value suffered a significant decrease at the beginning of immersion because the coating was permeated by the corrosive medium. The impedance value of twice doped PANI and doped PANI tended to stabilize after immersion for 22 d and 60 d respectively, the protection effect could be explained by the assumption that metallic cations formed a passivating complex with the dopant anion released from PANI, which improved the barrier property of PANI coating and slowed down the further corrosion of the metal. PANI doped twice with functional acid had better anticorrosion performance than doped state and twice doped PANI had higher impedance. PANI doped twice with tartaric acid had the highest impedance, the impedance value was 3.48×107Ω·cm2 after immersion for 120 d, an order of magnitude higher than its doped state.%聚苯胺具有独特的掺杂脱掺杂特性,能在特定的反应条件下合

  6. Mechanochemically assisted solid-state and citric acid complex syntheses of Cu-doped sodium cobaltite ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Pršić, S., E-mail: sanjaprsic@imsi.bg.ac.rs [Institute for Multidisciplinary Research, University of Belgrade, Kneza Višeslava 1, 11030 Belgrade (Serbia); Savić, S.M., E-mail: slavicas@imsi.bg.ac.rs [Institute for Multidisciplinary Research, University of Belgrade, Kneza Višeslava 1, 11030 Belgrade (Serbia); Branković, Z., E-mail: zorica.brankovic@imsi.bg.ac.rs [Institute for Multidisciplinary Research, University of Belgrade, Kneza Višeslava 1, 11030 Belgrade (Serbia); Vrtnik, S., E-mail: stane.vrtnik@ijs.si [Institute Jožef Stefan, Condensed Matter Physics, Jamova cesta 39, 1000 Ljubljana (Slovenia); Dapčević, A., E-mail: hadzi-tonic@tmf.bg.ac.rs [Department of General and Inorganic Chemistry, Faculty of Technology and Metallurgy, University of Belgrade, Karnegijeva 4, 11120 Belgrade (Serbia); Branković, G., E-mail: goran.brankovic@imsi.bg.ac.rs [Institute for Multidisciplinary Research, University of Belgrade, Kneza Višeslava 1, 11030 Belgrade (Serbia)

    2015-08-15

    Highlights: • Sodium cobaltite was synthesized by mechanochemically assisted solid-state reaction and citric acid complex (CAC) method. • We investigated effect of Cu-doping in NaCo{sub 2−x}Cu{sub x}O{sub 4} (x = 0, 0.01, 0.03, 0.05). • ICP analysis showed that the controlling of the samples composition is easier by the CAC method. • The Seebeck coefficient in Cu-doped samples was higher compared to the undoped one. • The highest figure of merit was observed in the sample with the lowest Cu concentration. - Abstract: In the last decade, the sodium cobaltite ceramic became a promising candidate for potential thermoelectric applications, because of its large thermopower and low resistivity. In this work, polycrystalline samples of NaCo{sub 2−x}Cu{sub x}O{sub 4} (x = 0, 0.01, 0.03, 0.05) were prepared using mechanochemically assisted solid-state reaction method (MASSR) and the citric acid complex method (CAC). Bulk samples were prepared by pressing into disc-shaped pellets and subsequently subjected to a thermal treatment at 880 °C in inert argon atmosphere. Changes in structural and microstructural characteristics of the samples, caused by the substitution of Cu for Co, were characterized using X-ray diffraction (XRD) analysis, and scanning electron microscopy (SEM), respectively. The results of inductively coupled plasma (ICP) analysis showed that the compositions of the final products correspond to γ-NaCo{sub 2}O{sub 4} and confirmed that desired compound was obtained in both syntheses procedures. The advantages and disadvantages of these two syntheses procedures have been observed and discussed: the CAC method enabled obtaining samples with higher density and fine microstructure compared to the MASSR method, thus better thermoelectric properties. The Cu{sup 2+} substitution led to the increase in Seebeck coefficient in both synthesis routes. The highest figure of merit of 0.022 at 300 K was observed for the sample doped with 1 mol% Cu, obtained by

  7. Au/ZnO hybrid nanocatalysts impregnated in N-doped graphene for simultaneous determination of ascorbic acid, acetaminophen and dopamine.

    Science.gov (United States)

    Chen, Xianlan; Zhang, Guowei; Shi, Ling; Pan, Shanqing; Liu, Wei; Pan, Hiabo

    2016-08-01

    The formation of nitrogen-doped (N-doped) graphene uses hydrothermal method with urea as reducing agent and nitrogen source. The surface elemental composition of the catalyst was analyzed through XPS, which showed a high content of a total N species (7.12at.%), indicative of the effective N-doping, present in the form of pyridinic N, pyrrolic N and graphitic N groups. Moreover, Au nanoparticles deposited on ZnO nanocrystals surface, forming Au/ZnO hybrid nanocatalysts, undergo a super-hydrophobic to super-hydrophilic conversion. Herein, we present Au/ZnO hybrid nanocatalysts impregnated in N-doped graphene sheets through sonication technique of the Au/ZnO/N-doped graphene hybrid nanostructures. The as-prepared Au/ZnO/N-doped graphene hybrid nanostructure modified glassy carbon electrode (Au/ZnO/N-doped graphene/GCE) was first employed for the simultaneous determination of ascorbic acid (AA), dopamine (DA) and acetaminophen (AC). The oxidation over-potentials of AA, DA and AC decreased dramatically, and their oxidation peak currents increased significantly at Au/ZnO/N-doped graphene/GCE compared to those obtained at the N-doped graphene/GCE and bare CCE. The peak separations between AA and DA, DA and AC, and AC and AA are large up to 195, 198 and 393mV, respectively. The calibration curves for AA, DA and AC were obtained in the range of 30.00-13.00×10(3), 2.00-0.18×10(3) and 5.00-3.10×10(3)μM, respectively. The detection limits (S/N=3) were 5.00, 0.40 and 0.80μM for AA, DA and AC, respectively.

  8. Photo-catalytic decolourisation of toxic dye with N-doped titania: A case study with Acid Blue 25

    Institute of Scientific and Technical Information of China (English)

    Dhruba Chakrabortty; Susmita Sen Gupta

    2013-01-01

    Dyes are one of the hazardous water pollutants.Toxic Acid Blue 25,an anthraquinonic dye,has been decolourised by photo-catalysing it with nitrogen doped titania in aqueous medium.The photo catalyst was prepared from 15% TiCl3 and 25% aqueous NH3 solution as precursor.XRD and TEM revealed the formation of well crystalline anatase phase having particle size in the nano-range.BET surface area of the sample was higher than that of pure anatase TiO2.DRS showed higher absorption of radiation in visible range compared to pure anatase TiO2.XPS revealed the presence of nitrogen in N-Ti-O environment.The experimental parameters,namely,photocatalyst dose,initial dye concentration as well as solution pH influence the decolourisation process.At pH 3.0,the N-TiO2 could decolourise almost 100% Acid Blue 25 within one hour.The influence of N-TiO2 dose,initial concentration of Acid Blue 25 and solution pH on adsorption-desorption equilibrium is also studied.The adsorption process follows Lagergren first order kinetics while the modified Langmuir-Hinselwood model is suitably fitted for photocatalytic decolourisation of Acid Blue 25.

  9. Thin film thermocouples for in situ membrane electrode assembly temperature measurements in a polybenzimidazole-based high temperature proton exchange membrane unit cell

    DEFF Research Database (Denmark)

    Ali, Syed Talat; Lebæk, Jesper; Nielsen, Lars Pleth

    2010-01-01

    This paper presents Type-T thin film thermocouples (TFTCs) fabricated on Kapton (polyimide) substrate for measuring the internal temperature of PBI(polybenzimidazole)-based high temperature proton exchange membrane fuel cell (HT-PEMFC). Magnetron sputtering technique was employed to deposit a 2 mu...

  10. Sonochemical synthesis of Pr-doped ZnO nanoparticles for sonocatalytic degradation of Acid Red 17.

    Science.gov (United States)

    Khataee, Alireza; Karimi, Atefeh; Arefi-Oskoui, Samira; Darvishi Cheshmeh Soltani, Reza; Hanifehpour, Younes; Soltani, Behzad; Joo, Sang Woo

    2015-01-01

    Undoped and Pr-doped ZnO nanoparticles were prepared using a simple sonochemical method, and their sonocatalytic activity was investigated toward degradation of Acid Red 17 (AR17) under ultrasonic (US) irradiation. Synthesized nanoparticles were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS) techniques. The extent of sonocatalytic degradation was higher compared with sonolysis alone. The decolorization efficiency of sonolysis alone, sonocatalysis with undoped ZnO and 5% Pr-doped ZnO was 24%, 46% and 100% within reaction time of 70min, respectively. Sonocatalytic degradation of AR17 increased with increasing the amount of dopant and catalyst dosage and decreasing initial dye concentration. Natural pH was favored the sonocatalytic degradation of AR17. With the addition of chloride, carbonate and sulfate as radical scavengers, the decolorization efficiency was decreased from 100% to 65%, 71% and 89% at the reaction time of 70min, respectively, indicating that the controlling mechanism of sonochemical degradation of AR17 is the free radicals (not pyrolysis). The addition of peroxydisulfate and hydrogen peroxide as enhancer improved the degradation efficiency from 79% to 85% and 93% at the reaction time of 50min, respectively. The result showed good reusability of the synthesized sonocatalyst.

  11. A first-principles study on the effect of phosphorus-doped palladium catalyst for formic acid dissociation

    Science.gov (United States)

    He, Feng; Li, Kai; Yin, Cong; Wang, Ying; Jiao, Menggai; Tang, Hao; Wu, Zhijian

    2016-11-01

    The effect of phosphorus-doped Pd(111) catalyst for the formic acid (HCOOH) dissociation has been investigated by using the density functional theory. The adsorption configurations and active sites of the intermediates involved in the HCOOH dissociation on the Pd/P(111) surface are studied. Our results showed that the doping of P on Pd catalyst could strengthen the adsorption of the intermediates. The Pd/P(111) catalyst exhibits higher catalytic activity by the easy formation of CO2 and H2 compared with the Pd(111) catalyst. The dominant HCOOH dissociation product on Pd/P(111) surface is CO2 rather than CO. Based on the computational hydrogen electrode (CHE) model, we found that CO formation is unfavorable on Pd/P(111) under the anode potential condition compared with the Pd(111) catalyst. Furthermore, the microkinetic analysis based on the DFT calculations showed that at high temperatures, the HCOOH dissociation is disfavored on the Pd/P(111) surface.

  12. Cyclic voltammetry and impedance studies of electrodeposited polypyrrole nanoparticles doped with 2-acrylamido-2-methyl-1-propanesulfonic acid sodium salt

    Energy Technology Data Exchange (ETDEWEB)

    Ebrahim, Sh. M., E-mail: shebrahim@igsr.alex.edu.e [Department of Materials Science, Institute of Graduate Studies and Research, Alexandria University, Postal Code 21526, Alexandria (Egypt); Latif, M.M. Abd-El [Mubarak City for Scientific Research and Technology Applications, Institute of Advanced Technology and New Materials, Borg El-Arab City, Alexandria (Egypt); Gad, A.M.; Soliman, M.M. [Department of Materials Science, Institute of Graduate Studies and Research, Alexandria University, Postal Code 21526, Alexandria (Egypt)

    2010-05-31

    Electrochemical synthesis of polypyrrole (PPY), doped with 2-acrylamido-2-methyl-1-propanesulfonic acid sodium salt (AMPSNa), was carried out using chronoamperometric technique. Cyclic voltammetry measurements showed that the electroactivity of PPY films, doped with AMPSNa, increases with the film thickness. Scanning electron microscopy photographs revealed that the PPY particles are in the nano-scale range and that their size depends on the potential at which the PPY has formed. Electrochemical impedance spectroscopy (EIS), in the potential range of + 1.0 and - 1.0 V, revealed in the PPY film charge transfer domination with a semicircle at high frequencies, and anion diffusion dominance at low frequencies. EIS also showed that the charge transfer resistance of PPY film at - 1.0 V is lower than what is expected and that on increasing the thickness of the PPY films, the overall impedance decreases. The proposed equivalent circuit model, based on the double layer capacity and the Warburg impedance, was replaced by two constant-phase elements to fit the experimental work of this study. The values of the fractional exponent of the first constant phase element at approximately 0.5 indicate that the processes have a diffusion-limited nature.

  13. Doping effect of dodecyl benzene sulphonic acid in poly(3-hexylthiophene)-P3HT-films

    Science.gov (United States)

    Alveroglu, Esra

    2015-04-01

    We demonstrated that how dodecyl benzene sulphonic acid (DBSA) as a small-molecular dopant, affects the spectroscopic, electronic and structural properties of poly(3-hexylthiophene) (P3HT). The DBSA volume ratio was varied from 0.001 μL to 30 μL per 1 mL P3HT solvent in p-xylene. DBSA doping reaction was confirmed by the emerging huge absorption peak at the wavelength of ∼800 nm while the ionization potential and nanostructure of P3HT films were highly affected. Additionally, conductivity of P3HT films increased nearly 1000 times at 30 μL DBSA. The crystallinity, as well as the conductivity and the UV-Vis absorption changed with the presence of P3HT. P3HT grain sized crystals seems to be disturbed by the addition of DBSA, but still remained even more DBSA was introduced. DBSA doping has interesting properties when incorporated in OFTs, OPVs and bioelectronics applications, so addition of DBSA can open new pathways for structural, spectroscopic and electronic control of organic semiconductor's blends.

  14. Effect of organic acids and nano-sized ceramic doping on PEO-based solid polymer electrolytes

    Science.gov (United States)

    Park, Jae Won; Jeong, Euh Duck; Won, Mi-Sook; Shim, Yoon-Bo

    Composite solid polymer electrolytes (CSPEs) consisting of polyethyleneoxide (PEO), LiClO 4, organic acids (malonic, maleic, and carboxylic acids), and/or Al 2O 3 were prepared in acetonitrile. CSPEs were characterized by Brewster Angle Microscopy (BAM), thermal analysis, ac impedance, cyclic voltammetry, and tested for charge-discharge capacity with the Li or LiNi 0.5Co 0.5O 2 electrodes coated on stainless steel (SS). The morphologies of the CSPE films were homogeneous and porous. The differential scanning calorimetric (DSC) results suggested that performance of the CSPE film was highly enhanced by the acid and inorganic additives. The composite membrane doped with organic acids and ceramic showed good conductivity and thermal stability. The ac impedance data, processed by non-linear least square (NLLS) fitting, showed good conducting properties of the composite films. The ionic conductivity of the film consisting of (PEO) 8LiClO 4:citric acid (99.95:0.05, w/w%) was 3.25 × 10 -4 S cm -1 and 1.81 × 10 -4 S cm -1 at 30 °C. The conductivity has further improved to 3.81 × 10 -4 S cm -1 at 20 °C by adding 20 w/w% Al 2O 3 filler to the (PEO) 8LiClO 4 + 0.05% carboxylic acid composite. The experimental data for the full cell showed an upper limit voltage window of 4.7 V versus Li/Li + for CSPE at room temperature.

  15. Proton conducting membranes based on benzimidazole sulfonic acid doped sulfonated poly(oxadiazole-triazole) copolymer for low humidity operation

    Energy Technology Data Exchange (ETDEWEB)

    Boaventura, M.; Mendes, A.; Madeira, L.M. [LEPAE - Laboratorio de Engenharia de Processos Ambiente e Energia, Faculdade de Engenharia da Universidade do Porto, Rua Dr. Roberto Frias s/n, 4200-465 Porto (Portugal); Gomes, D.; Nunes, S.P. [GKSS Research Centre Geesthacht GmbH, Max Planck Str. 1, D-21502, Geesthacht (Germany); Ponce, M.L.

    2008-07-15

    This work reports for the first time the preparation of sulphonated poly(oxadiazole-triazole) copolymer membranes doped with amphoteric molecule, 1H-benzimidazole-2-sulphonic acid and their characterisation as proton conductors at 120 C and low humidity. The membranes had not only high proton conductivities, up to 4 x 10{sup -3} S cm{sup -1} at 120 C and low relative humidity (5 and 10%), but also had good mechanical properties with a storage modulus of about 3 GPa at 300 C and high thermal stability with T{sub g} up to around 420 C. Because of their superior ion conducting and mechanical properties they have potential as a proton conducting membrane for fuel cell applications, in particular at high temperature and extremely low-humidity conditions. (Abstract Copyright [2008], Wiley Periodicals, Inc.)

  16. Antibacterial Property and Cytotoxicity of a Poly(lactic acid/Nanosilver-Doped Multiwall Carbon Nanotube Nanocomposite

    Directory of Open Access Journals (Sweden)

    Chi-Hui Tsou

    2017-03-01

    Full Text Available A novel method was used to synthesize a nanosilver-doped multiwall carbon nanotube (MWCNT-Ag, and subsequently, the novel poly(lactic acid (PLA- and MWCNT-Ag-based biocompatible and antimicrobial nanocomposites were prepared by melt blending. Based on energy dispersive X-ray spectrometry images, an MWCNT-Ag was successfully synthesized. The effect of the MWCNT-Ag on the PLA bionanocomposites was investigated by evaluating their thermal and mechanical properties, antifungal activity, and cytotoxicity. The nanocomposites exhibited a high degree of biocompatibility with the MWCNT-Ag content, which was less than 0.3 phr. Furthermore, tensile strength testing, thermogravimetric analysis, differential scanning calorimetry, and antibacterial evaluation revealed that the tensile strength, thermostability, glass transition temperature, and antibacterial properties were enhanced by increasing the MWCNT-Ag content. Finally, hydrolysis analysis indicated that the low MWCNT-Ag content could increase the packing density of PLA.

  17. Novel Proton Conducting Solid Bio-polymer Electrolytes Based on Carboxymethyl Cellulose Doped with Oleic Acid and Plasticized with Glycerol

    Science.gov (United States)

    Chai, M. N.; Isa, M. I. N.

    2016-06-01

    The plasticized solid bio-polymer electrolytes (SBEs) system has been formed by introducing glycerol (Gly) as the plasticizer into the carboxymethyl cellulose (CMC) doped with oleic acid (OA) via solution casting techniques. The ionic conductivity of the plasticized SBEs has been studied using Electrical Impedance Spectroscopy. The highest conductivity achieved is 1.64 × 10‑4 S cm‑1 for system containing 40 wt. % of glycerol. FTIR deconvolution technique had shown that the conductivity of CMC-OA-Gly SBEs is primarily influenced by the number density of mobile ions. Transference number measurement has shown that the cation diffusion coefficient and ionic mobility is higher than anion which proved the plasticized polymer system is a proton conductor.

  18. Enhanced selectivity of boron doped diamond electrodes for the detection of dopamine and ascorbic acid by increasing the film thickness

    Science.gov (United States)

    Qi, Yao; Long, Hangyu; Ma, Li; Wei, Quiping; Li, Site; Yu, Zhiming; Hu, Jingyuan; Liu, Peizhi; Wang, Yijia; Meng, Lingcong

    2016-12-01

    In this paper, boron doped diamond (BDD) with different thickness were prepared by hot filament chemical vapor deposition. The performance of BDD electrodes for detecting dopamine (DA) and ascorbic acid (AA) were investigated. Scanning electron microscopy and Raman spectra reveal the grain size increases and the film quality improves with the increase of film thickness. Electrochemical test show that the transfer coefficient in [Fe3 (CN) 6]3-/4- redox system increases with the increase of the film thickness. The results of selectivity and sensitivity for DA mixed with AA detection show that 8h-BDD and 12h-BDD electrodes possess well selective separated oxidation peaks of DA and AA, and the 12h-BDD electrode exhibits optimal sensitivity until the DA concentration drops to 1 μ M.

  19. Synthesis, characterization and visible light photocatalytic activity of Cr 3+ , Ce 3+ and N co-doped TiO 2 for the degradation of humic acid

    KAUST Repository

    Rashid, S. G.

    2015-01-01

    The synthesis, characterization and photocatalytic activity of Cr3+ and Ce3+ co-doped TiON (N-doped TiO2) for the degradation of humic acid with exposure to visible light is reported. The synthesized bimetal (Cr3+ + Ce3+) modified TiON (Cr-Ce/TiON), with an evaluated bandgap of 2.1 eV, exhibited an enhanced spectral response in the visible region as compared to pure and Ce3+ doped TiON (Ce/TiON). The XRD analysis revealed the insertion of Cr3+ and Ce3+ in the crystal lattice along with Ti4+ and N that resulted in the formation of a strained TiON anatase structure with an average crystallite size of ∼10 nm. Raman analysis also supported the formation of stressed rigid structures after bimetal doping. HRTEM confirmed the homogeneous distribution of both the doped metallic components in the crystal lattice of TiON without the formation of surface oxides of either Cr3+ or Ce3+. Electron energy loss spectroscopy (EELS) analysis revealed no change in the oxidation of either Cr or Ce during the synthesis. The synthesized Cr-Ce/TiON catalyst exhibited appreciable photocatalytic activity for the degradation of humic acid on exposure to visible light. Additionally, a noticeable mineralization of carbon rich humic acid was also witnessed. The photocatalytic activity of the synthesized catalyst was compared with pristine and Ce3+ doped TiON. © The Royal Society of Chemistry 2015.

  20. Hollow nitrogen-doped carbon microspheres pyrolyzed from self-polymerized dopamine and its application in simultaneous electrochemical determination of uric acid, ascorbic acid and dopamine.

    Science.gov (United States)

    Xiao, Chunhui; Chu, Xiaochen; Yang, Yan; Li, Xing; Zhang, Xiaohua; Chen, Jinhua

    2011-02-15

    Hollow nitrogen-doped carbon microspheres (HNCMS) as a novel carbon material have been prepared and the catalytic activities of HNCMS-modified glassy carbon (GC) electrode towards the electro-oxidation of uric acid (UA), ascorbic acid (AA) and dopamine (DA) have also been investigated. Comparing with the bare GC and carbon nanotubes (CNTs) modified GC (CNTs/GC) electrodes, the HNCMS modified GC (HNCMS/GC) electrode has higher catalytic activities towards the oxidation of UA, AA and DA. Moreover, the peak separations between AA and DA, and DA and UA at the HNCMS/GC electrode are up to 212 and 136 mV, respectively, which are superior to those at the CNTs/GC electrode (168 and 114 mV). Thus the simultaneous determination of UA, AA and DA was carried out successfully. In the co-existence system of UA, AA and DA, the linear response range for UA, AA and DA are 5-30 μM, 100-1000 μM and 3-75 μM, respectively and the detection limits (S/N = 3) are 0.04 μM, 0.91 μM and 0.02 μM, respectively. Meanwhile, the HNCMS/GC electrode can be applied to measure uric acid in human urine, and may be useful for measuring abnormally high concentration of AA or DA. The attractive features of HNCMS provide potential applications in the simultaneous determination of UA, AA and DA.

  1. Simultaneous voltammetric determination of paracetamol and ascorbic acid using a boron-doped diamond electrode modified with Nafion and lead films.

    Science.gov (United States)

    Tyszczuk-Rotko, Katarzyna; Bęczkowska, Ilona; Wójciak-Kosior, Magdalena; Sowa, Ireneusz

    2014-11-01

    The paper describes the fabrication and application of a novel sensor (a boron-doped diamond electrode modified with Nafion and lead films) for the simultaneous determination of paracetamol and ascorbic acid by differential pulse voltammetry. The main advantage of the lead film and polymer covered boron-doped diamond electrode is that the sensitivity of the stripping responses is increased and the separation of paracetamol and ascorbic acid signals is improved due to the modification of the boron-doped diamond surface by the lead layer. Additionally, the repeatability of paracetamol and ascorbic acid signals is improved by the application of the Nafion film coating. In the presence of oxygen, linear calibration curves were obtained in a wide concentration range from 5×10(-7) to 2×10(-4) mol L(-1) for paracetamol and from 1×10(-6) to 5×10(-4) mol L(-1) for ascorbic acid. The analytical utility of the differential pulse voltammetric method elaborated was tested in the assay of paracetamol and ascorbic acid in commercially available pharmaceutical formulations and the method was validated by high performance liquid chromatography coupled with diode array detector.

  2. Growth of thin, c-axis oriented Sr-doped LaP3O9 electrolyte membranes in condensed phosphoric acid solutions

    Science.gov (United States)

    Hatada, Naoyuki; Takahashi, Kota; Adachi, Yoshinobu; Uda, Tetsuya

    2016-08-01

    Proton-conducting Sr-doped LaP3O9 has potential application as electrolytes in intermediate temperature fuel cells, but reduction of the electrical resistance of the electrolyte membranes is necessary for practical applications. In this study, we focused on reducing the resistance by reducing the electrolyte thickness, while maintaining a preferable microstructure for proton conduction (c-axis orientation and absence of the small-crystal layer). Thin, c-axis oriented Sr-doped LaP3O9 membranes were successfully obtained in condensed phosphoric acid solutions by a novel "two-step precipitation method". In this method, Sr-doped LaP3O9 powder was artificially deposited on the surface of the carbon paper supports as seeds, and then columnar crystals were grown "downward" in the solutions. We expect that this method will be utilized to produce LaP3O9 electrolyte membranes with lower electrical resistance.

  3. Preparation and characterization of 5-sulphosalicylic acid doped tetraethoxysilane composite ion-exchange material by sol–gel method

    Energy Technology Data Exchange (ETDEWEB)

    Rehman, Suhail-ul; Islam, Nasarul; Ahad, Sozia; Fatima, Syed Zeeshan; Pandith, Altaf Hussain, E-mail: altafpandit23@gmail.com

    2013-09-15

    Highlights: • Sulphosalicylic acid doped tetraethoxysilane composite is prepared by sol–gel method. •Its X-ray diffraction studies suggest that it is crystalline in nature. • This material shows selectivity for Mg(II) and Ni(II) ions in aqueous solutions. • Separation of Ni(II) from binary mixtures was successfully achieved on this material. -- Abstract: In this manuscript, we report the preparation and characterization of sulphosalicylic doped tetraethoxysilane (SATEOS), composite material by sol–gel method as a new ion exchanger for the removal of Ni(II) from aqueous solution. The fine granular material was prepared by acid catalyzed condensation polymerization through sol–gel mechanism in the presence of cationic surfactant. The material has an ion exchange capacity of 0.64 mequiv./g(dry) for sodium ions, 0.60 mequiv./g(dry) for potassium ions, 1.84 mequiv./g(dry) for magnesium ions, 1.08 mequiv./g(dry) for calcium ions and 1.36 mequiv./g(dry) for strontium ions. Its X-ray diffraction studies suggest that it is crystalline in nature. The material has been characterized by SEM, IR, TGA and DTG so as to identify the various functional groups and ion exchange sites present in this material. Quantum chemical computations at DFT/B3LYP/6-311G (d,p) level on model systems were performed to substantiate the structural conclusions based ion instrumental techniques. Investigations into the elution behaviour, ion exchange reversibility and distribution capacities of this material towards certain environmentally hazardous metal ions are also performed. The material shows good chemical stability towards acidic conditions and exhibits fast elution of exchangeable H{sup +} ions under neutral conditions. This material shows remarkable selectivity for Ni(II) and on the basis of its K{sub d} value (4 × 10{sup 2} in 0.01 M HClO{sub 4}) some binary separations of Ni(II) from other metal ions are performed.

  4. Removal of aqueous Hg(II) and Cr(VI) using phytic acid doped polyaniline/cellulose acetate composite membrane.

    Science.gov (United States)

    Li, Renjie; Liu, Lifen; Yang, Fenglin

    2014-09-15

    Conductive composite membrane-phytic acid (PA) doped polyaniline (PANI)/cellulose acetate (CA) (PANI-PA/CA) was prepared in a simple and environmental-friendly method, in which aniline was blended with CA/PA solution and polymerized before the phase conversion. The resultant composite membranes were characterized by SEM, EDX, FTIR-ATR, BET and electrical resistance measurements. When used as adsorbent for Hg(II) and Cr(VI) ions, the prepared composite membrane exhibits excellent adsorption capability. The adsorption of Hg(II) and Cr(VI) follows a pseudo-second-order kinetic model and best fits the Langmuir isotherm model, with the maximum adsorption capacity reaching 280.11 and 94.34 mg g(-1), respectively. The heavy metal loaded composite membrane can be regenerated and reused after treatment with acid or alkali solution, making it a promising and practical adsorbent for Hg(II) and Cr(VI) removal. Tests with river water were also carried out, indicating good performance and application.

  5. Encapsulation of amoxicillin within laponite-doped poly(lactic-co-glycolic acid) nanofibers: preparation, characterization, and antibacterial activity.

    Science.gov (United States)

    Wang, Shige; Zheng, Fuyin; Huang, Yunpeng; Fang, Yuting; Shen, Mingwu; Zhu, Meifang; Shi, Xiangyang

    2012-11-01

    We report a facile approach to encapsulating amoxicillin (AMX) within laponite (LAP)-doped poly(lactic-co-glycolic acid) (PLGA) nanofibers for biomedical applications. In this study, a synthetic clay material, LAP nanodisks, was first used to encapsulate AMX. Then, the AMX-loaded LAP nanodisks with an optimized AMX loading efficiency of 9.76 ± 0.57% were incorporated within PLGA nanofibers through electrospinning to form hybrid PLGA/LAP/AMX nanofibers. The loading of AMX within LAP nanodisks and the loading of LAP/AMX within PLGA nanofibers were characterized via different techniques. In vitro drug release profile, antimicrobial activity, and cytocompatibility of the formed hybrid PLGA/LAP/AMX nanofibers were also investigated. We show that the loading of AMX within LAP nanodisks does not lead to the change of LAP morphology and crystalline structure and the incorporation of LAP/AMX nanodisks does not significantly change the morphology of the PLGA nanofibers. Importantly, the loading of AMX within LAP-doped PLGA nanofibers enables a sustained release of AMX, much slower than that within a single carrier of LAP nanodisks or PLGA nanofibers. Further antimicrobial activity and cytocompatibility assays demonstrate that the antimicrobial activity of AMX toward the growth inhibition of a model bacterium of Staphylococcus aureus is not compromised after being loaded into the hybrid nanofibers, and the PLGA/LAP/AMX nanofibers display good cytocompatibility, similar to pure PLGA nanofibers. With the sustained release profile and the reserved drug activity, the organic/inorganic hybrid nanofiber-based drug delivery system may find various applications in tissue engineering and pharmaceutical science.

  6. Novel electrochemical sensor based on N-doped carbon nanotubes and Fe3O4 nanoparticles: simultaneous voltammetric determination of ascorbic acid, dopamine and uric acid.

    Science.gov (United States)

    Fernandes, Diana M; Costa, Marta; Pereira, Clara; Bachiller-Baeza, Belén; Rodríguez-Ramos, Inmaculada; Guerrero-Ruiz, Antonio; Freire, Cristina

    2014-10-15

    A new modified electrode based on N-doped carbon nanotubes functionalized with Fe3O4 nanoparticles (Fe3O4@CNT-N) has been prepared and applied on the simultaneous electrochemical determination of small biomolecules such as dopamine (DA), uric acid (UA) and ascorbic acid (AA) using voltammetric methods. The unique properties of CNT-N and Fe3O4 nanoparticles individually and the synergetic effect between them led to an improved electrocatalytic activity toward the oxidation of AA, DA and UA. The overlapping anodic peaks of these three biomolecules could be resolved from each other due to their lower oxidation potentials and enhanced oxidation currents when using the Fe3O4@CNT-N modified electrode. The linear response ranges for the square wave voltammetric determination of AA, DA and UA were 5-235, 2.5-65 and 2.5-85μmoldm(-3) with detection limit (S/N=3) of 0.24, 0.050 and 0.047μmoldm(-3), respectively. These results show that Fe3O4@CNT-N nanocomposite is a promising candidate of cutting-edge electrode materials for electrocatalytic applications.

  7. Superior Thermally Stable and Nonflammable Porous Polybenzimidazole Membrane with High Wettability for High-Power Lithium-Ion Batteries.

    Science.gov (United States)

    Li, Dan; Shi, Dingqin; Xia, Yonggao; Qiao, Lin; Li, Xianfeng; Zhang, Huamin

    2017-02-28

    Separators with high security, reliability, and rate capacity are in urgent need for the advancement of high power lithium ion batteries. The currently used porous polyolefin membranes are critically hindered by their low thermal stability and poor electrolyte wettability, which further lead to low rate capacity. Here we present a novel promising porous polybenzimidazole (PBI) membrane with super high thermal stability and electrolyte wettability. The rigid structure and functional groups in the PBI chain enable membranes to be stable at temperature as high as 400 °C, and the unique flame resistance of PBI could ensure the high security of a battery as well. In particular, the prepared membrane owns 328% electrolyte uptake, which is more than two times higher than commercial Celgard 2325 separator. The unique combination of high thermal stability, high flame resistance and super high electrolyte wettability enable the PBI porous membranes to be highly promising for high power lithium battery.

  8. Selective interfacial synthesis of metal-organic frameworks on a polybenzimidazole hollow fiber membrane for gas separation.

    Science.gov (United States)

    Biswal, Bishnu P; Bhaskar, Anand; Banerjee, Rahul; Kharul, Ulhas K

    2015-04-28

    Metal-organic frameworks (MOFs) have gained immense attention as new age materials due to their tuneable properties and diverse applicability. However, efforts on developing promising materials for membrane based gas separation, and control over the crystal growth positions on polymeric hollow fiber membranes still remain key challenges. In this investigation, a new, convenient and scalable room temperature interfacial method for growing MOFs (ZIF-8 and CuBTC) on either the outer or inner side of a polybenzimidazole based hollow fiber (PBI-BuI-HF) membrane surface has been achieved in a controlled manner. This was made possible by the appropriate selection of an immiscible solvent pair and the synthetic conditions. The growth of MOFs on the PBI-BuI-HF membrane by the interfacial method was continuous and showed an appreciable gas separation performance, conveying promise for their applicability.

  9. New process for high temperature polybenzimidazole membrane production and its impact on the membrane and the membrane electrode assembly

    Science.gov (United States)

    Liu, Zhenyu; Tsou, Yu-Min; Calundann, Gordon; De Castro, Emory

    Water addition is a key step in the new process developed at BASF Fuel Cell Inc. (BFC) for polybenzimidazole (PBI) membrane production. The added water prevents further polymerization and controls the solution viscosity for easier membrane casting. For large-scale PBI membrane production, a certain amount of tension is necessary during membrane upwinding. The applied tension could affect the polymer orientation and result in anisotropic membrane mechanical properties and proton conductivity. The membrane prepared with tension shows higher elastic modulus and proton conductivity in machine direction, which might suggest some degree of polymer chain orientation. However, the membrane electrode assembly (MEA) performance is not affected by the membrane's apparent anisotropic character. However, we observed performance variation as a function of MEA break-in condition, which might be explained by the formation of a phosphate anion concentration gradient during MEA operation.

  10. New process for high temperature polybenzimidazole membrane production and its impact on the membrane and the membrane electrode assembly

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Zhenyu; Tsou, Yu-Min; Calundann, Gordon; De Castro, Emory [BASF Fuel Cell Inc., 39 Veronica Avenue, Somerset, NJ 08873 (United States)

    2011-02-01

    Water addition is a key step in the new process developed at BASF Fuel Cell Inc. (BFC) for polybenzimidazole (PBI) membrane production. The added water prevents further polymerization and controls the solution viscosity for easier membrane casting. For large-scale PBI membrane production, a certain amount of tension is necessary during membrane upwinding. The applied tension could affect the polymer orientation and result in anisotropic membrane mechanical properties and proton conductivity. The membrane prepared with tension shows higher elastic modulus and proton conductivity in machine direction, which might suggest some degree of polymer chain orientation. However, the membrane electrode assembly (MEA) performance is not affected by the membrane's apparent anisotropic character. However, we observed performance variation as a function of MEA break-in condition, which might be explained by the formation of a phosphate anion concentration gradient during MEA operation. (author)

  11. Voltammetric behaviour of levodopa and its quantification in pharmaceuticals using a -cyclodextrine doped poly (2,5-diaminobenzenesulfonic acid) modified electrode

    Indian Academy of Sciences (India)

    Mehmet Aslanoglu; Aysegul Kutluay; Sultan Goktas; Serpil Karabulut

    2009-03-01

    A cyclic voltammetric method based on a -cyclodextrine doped poly(2,5-diaminobenzenesulfonic acid) modified glassy carbon electrode (GCE) was developed for the determination of levodopa. Compared with bare GCE and poly(2,5-diaminobenzenesulfonic acid)/GCE, the poly(2,5-diaminobenzenesulfonic acid)--cyclodextrine/GCE exhibits a remarkable shift of the oxidation potentials of levodopa in the cathodic direction and a drastic enhancement of the anodic current response. The incorporation of -cyclodextrine into the polymer film exhibited that the electrode provides more stable and sensitive current responses for levodopa. Levodopa exhibited a single broad peak at about 0.6 V at bare GCE. However, at the -cyclodextrine doped poly(2,5-diaminobenzenesulfonic acid)/GCE, a well-defined redox wave of levodopa was obtained, with the oxidation and the reduction peak potential at 0.193 and 0.164 V, respectively. The separation of peak potentials was 29 mV. The linear current response was obtained in the range of 1.0 × 10-6 ∼ 2.0 ∼ 10-4 M with a detection limit of 4.18 ∼ 10-7 M for levodopa, The poly(2,5-diaminobenzenesulfonic acid)--cyclodextrine/GCE was also effective to simultaneously detect levodopa and ascorbic acid. The modified electrode has been successfully applied for the determination of levodopa in pharmaceuticals. The poly(2,5-diaminobenzenesulfonic acid)--cyclodextrine/GCE showed excellent stability and reproducibility.

  12. Phosphoric acid doped polysulfone membranes with aminopyridine pendant groups and imidazole cross-links

    DEFF Research Database (Denmark)

    Hink, Steffen; Elsøe, Katrine; Cleemann, Lars Nilausen;

    2015-01-01

    Udel polysulfone based membranes with 4-aminopyridine pendant groups and cross-linking imidazole units are synthesized in a simple two step reaction. The ratio of 4-aminopyridine and imidazole is varied and the materials are extensively characterized. The average phosphoric acid uptake (in 85 wt...

  13. A Doped Polyaniline Modified Electrode Amperometric Biosensor for Gluconic Acid Determination in Grapes

    Directory of Open Access Journals (Sweden)

    Donatella Albanese

    2014-06-01

    Full Text Available In winemaking gluconic acid is an important marker for quantitative evaluation of grape infection by Botrytis cinerea. A screen-printed amperometric bienzymatic sensor for the determination of gluconic acid based on gluconate kinase (GK and 6-phospho-D-gluconate dehydrogenase (6PGDH coimmobilized onto polyaniline/poly (2-acrylamido-2-methyl-1-propanesulfonic acid; PANI-PAAMPSA is reported in this study. The conductive polymer electrodeposed on the working electrode surface allowed the detection of NADH at low potential (0.1 V with a linear range from 4 × 10−3 to 1 mM (R2 = 0.99 and a sensitivity of 419.44 nA∙mM−1. The bienzymatic sensor has been optimized with regard to GK/6PGDH enzymatic unit ratio and ATP/NADP+ molar ratio which resulted equal to 0.33 and 1.2, respectively. Under these conditions a sensitivity of 255.2 nA∙mM−1, a limit of detection of 5 μM and a Relative Standard Deviation (RSD of 4.2% (n = 5 have been observed. Finally, the biosensor has been applied for gluconic acid measurements in must grape samples and the matrix effect has been taken into consideration. The results have been compared with those obtained on the same samples with a commercial kit based on a spectrophotometric enzyme assay and were in good agreement, showing the capability of the bienzymatic PANI-PAAMPSA biosensor for gluconic acid measurements and thus for the evaluation of Botrytis cinerea infection in grapes.

  14. Water-free Alkaline Polymer-inorganic Acid Complexes with High Conductivity at Ambient Temperature

    Institute of Scientific and Technical Information of China (English)

    O.V.Chervakov; M.V.Andriianova; V.V.Riabenko; A.V.Markevich; E.M.Shembel; D.Meshri

    2007-01-01

    1 Results Recently increased interest is shown to proton conducting materials based on the alkaline polymer-inorganic acid complexes that is caused by a possibility of their application as the high-temperature electrolyte systems for various electrochemical devices (fuel cells,sensors,lithium power sources etc.).Complexes of inorganic acids with the alkaline polymers (polybenzimidazoles[1],polyvinylpyridines[2]) are characterized by high ionic conductivity at ambient temperatures (up to 10-2 Ω-1·cm-1) a...

  15. Surface plasmon resonance based fiber optic trichloroacetic acid sensor utilizing layer of silver nanoparticles and chitosan doped hydrogel

    Science.gov (United States)

    Semwal, Vivek; Shrivastav, Anand M.; Gupta, Banshi D.

    2017-02-01

    In this study, we report a silver nanoparticles/chitosan doped hydrogel-based fiber optic sensor for the detection of trichloroacetic acid (TCA). The sensor is based on the combined phenomenon of localized and propagating surface plasmons. The sensing relies on the interaction of TCA with silver nanoparticles (AgNP) which results in the electron transfer between the negative group of TCA and positive amino group of AgNP stabilizer (chitosan). This alters the mechanical properties/refractive index of the AgNP embedded hydrogel matrix as well as the refractive index of the AgNP. The change in refractive index of both in turn changes the effective refractive index of the nanocomposite hydrogel layer which can be determined using the Maxwell-Garnet Theory. Four stage optimization of the probe fabrication parameters is performed to obtain the best performance of the sensing probe. The sensor operates in the TCA concentration range 0-120 μm which is harmful for the humans and environment. The shift in peak extinction wavelength observed for the same TCA concentration range is 42 nm. The sensor has the linearity range for the TCA concentration range of 40-100 μm. The sensor possesses high sensitivity, selectivity and numerous other advantages such as ease of handling, quick response, modest cost and capability of online monitoring and remote sensing.

  16. Construction and Study of Hetreojunction Solar Cell Based on Dodecylbenzene Sulfonic Acid-Doped Polyaniline/n-Si

    Directory of Open Access Journals (Sweden)

    I. Morsi

    2012-01-01

    Full Text Available Polyaniline/n-type Si heterojunctions solar cell are fabricated by spin coating of soluble dodecylbenzene sulfonic acid (DBSA-doped polyaniline onto n-type Si substrate. The electrical characterization of the Al/n-type Si/polyaniline/Au (Ag structure was investigated by using current-voltage (I-V, capacitance-voltage (C-V, and impedance spectroscopy under darkness and illumination. The photovoltaic cell parameters, that is, open-circuit voltage (oc, short-circuit current density (sc, fill factor (FF, and energy conversion efficiency (η were calculated. The highest sc, oc, and efficiency of these heterojunctions obtained using PANI-DBSA as a window layer (wideband gap and Au as front contact are 1.8 mA/cm2, 0.436 V, and 0.13%, respectively. From Mott-Schottky plots, it was found that order of charge carrier concentrations is 3.5×1014 and 1.0×1015/cm3 for the heterojunctions using Au as front contact under darknessness and illumination, respectively. Impedance study of this type of solar cell showed that the shunt resistance and series resistance decreased under illumination.

  17. Comparison of electronic transport properties of soluble polypyrrole and soluble polyaniline doped with dodecylbenzene-sulfonic acid

    Energy Technology Data Exchange (ETDEWEB)

    Aleshin, A.N.; Lee, K. [California Univ., Santa Barbara, CA (United States). Inst. for Polymers and Organic Solids; Lee, J.Y.; Kim, D.Y.; Kim, C.Y. [Polymer Materials Laboratory, Korea Institute of Science and Technology, Seoul 130-650 (Korea, Republic of)

    1999-01-29

    The temperature dependences of the conductivity of soluble polypyrrole (PPy) and soluble polyaniline (PANI) films doped with dodecylbenzene-sulfonic acid (DBSA) have been studied. The room temperature conductivities of samples were 1-8 and 95-100 S/cm, with resistivity ratio {rho}{sub r}={rho}(20 K)/{rho}(300 K){proportional_to}10{sup 4} and {rho}{sub r}={rho}(1.4 K)/{rho}(300 K){proportional_to}32 for PPy-DBSA and PANI-DBSA, respectively. At low temperatures, the temperature dependence follows the {sigma}(T)={sigma}{sub 0}exp[-(T{sub 0}/T){sup m}] law, which has been explained within the framework of granular metals model (m=0.5) for PPy-DBSA and Mott`s variable range hopping model (m=0.25) for PANI-DBSA. The magnetoresistance of PANI-DBSA is positive and follows H{sup 2} and H{sup 1/3} dependencies at low and high magnetic fields, respectively; the magnitude of the magnetoresistance is strongly temperature dependent. (orig.) 35 refs.

  18. Improvement in fingerprint detection using Tb(III)-dipicolinic acid complex doped nanobeads and time resolved imaging.

    Science.gov (United States)

    Hauser, Frank M; Knupp, Gerd; Officer, Simon

    2015-08-01

    This paper deals with the synthesis and application of lanthanide complex doped nanobeads used as a luminescent fingerprint powder. Due to their special optical properties, namely a long emission lifetime, sharp emission profiles and large Stokes shifts, luminescent lanthanide complexes are useful for discriminating against signals from background emissions. This is a big advantage because latent fingerprints placed on multicoloured fluorescent surfaces are difficult to develop with conventional powders. The complex of 2,6-dipicolinic acid (DPA) and terbium ([Tb(DPA)3](3-)) is used for this purpose. Using the Stöber process, this complex is incorporated into a silica matrix forming nanosized beads (230-630nm). It is shown that the [Tb(DPA)3](3-) is successfully incorporated into the beads and that these beads exhibit the wanted optical properties of the complex. A phenyl functionalisation is applied to increase the lipophilicity of the beads and finally the beads are used to develop latent fingerprints. A device for time resolved imaging was built to improve the contrast between developed fingerprint and different background signals, whilst still detecting the long lasting luminescence of the complex. The developed fingerprint powder is therefore promising to develop fingerprints on multicoloured fluorescent surfaces.

  19. EPR and optical studies of VO2+ doped potassium succinate-succinic acid single crystal - Substitutional incorporation

    Science.gov (United States)

    Juliet sheela, K.; Radha Krishnan, S.; Shanmugam, V. M.; Subramanian, P.

    2017-03-01

    EPR and optical absorption studies of VO2+ doped potassium succinate-succinic acid (KSSA) single crystal has been examined at room temperature. EPR spectrum shows that well resolved hyperfine lines. The angular variation of the EPR spectra has shown that two different VO2+ complexes are located in different chemical environments. Among the number of sites, two sites have been followed and reported here. From the EPR analysis, spin Hamiltonian parameters g and A tensors and their directional cosines are evaluated. Both the sites experience rhombic crystal field symmetry around the impurity ion. The VO2+ ion entering the site location of potassium ion has coordination of eight oxygen atoms in a distorted dodecahedral arrangement. The Optical absorption spectrum studied at room temperature shows bands corresponding to C4v symmetry. The crystal field parameter and tetragonal field parameters are calculated. From the Optical and EPR data various molecular orbital coefficients are evaluated and the nature of bonding in the crystal is discussed.

  20. Highly sensitive detection of influenza virus by boron-doped diamond electrode terminated with sialic acid-mimic peptide.

    Science.gov (United States)

    Matsubara, Teruhiko; Ujie, Michiko; Yamamoto, Takashi; Akahori, Miku; Einaga, Yasuaki; Sato, Toshinori

    2016-08-09

    The progression of influenza varies according to age and the presence of an underlying disease; appropriate treatment is therefore required to prevent severe disease. Anti-influenza therapy, such as with neuraminidase inhibitors, is effective, but diagnosis at an early phase of infection before viral propagation is critical. Here, we show that several dozen plaque-forming units (pfu) of influenza virus (IFV) can be detected using a boron-doped diamond (BDD) electrode terminated with a sialic acid-mimic peptide. The peptide was used instead of the sialyloligosaccharide receptor, which is the common receptor of influenza A and B viruses required during the early phase of infection, to capture IFV particles. The peptide, which was previously identified by phage-display technology, was immobilized by click chemistry on the BDD electrode, which has excellent electrochemical characteristics such as low background current and weak adsorption of biomolecules. Electrochemical impedance spectroscopy revealed that H1N1 and H3N2 IFVs were detectable in the range of 20-500 pfu by using the peptide-terminated BDD electrode. Our results demonstrate that the BDD device integrated with the receptor-mimic peptide has high sensitivity for detection of a low number of virus particles in the early phase of infection.

  1. Thermal stability and surface acidity of mesoporous silica doubly doped by incorporation of sulfate and zirconium ions

    Energy Technology Data Exchange (ETDEWEB)

    Salas, P. [Instituto Mexicano del Petroleo, Programa de Ingenieria Molecular, Eje Central Lazaro Cardenas No. 152, 07730 Mexico D.F. (Mexico)]. E-mail: psalas@imp.mx; Chen, L.F. [Departamento de Ingenieria Quimica, Universidad Autonoma Metropolitana-A, Av. San Pablo 180, Col. Reynosa-Tamaulipas, 02200 Mexico D.F. (Mexico); Wang, J.A. [Laboratorio de Catalisis y Materiales, ESIQIE, Instituto Politecnico Nacional, Col. Zacatenco, 07738 Mexico D.F. (Mexico); Armendariz, H. [Instituto Mexicano del Petroleo, Programa de Ingenieria Molecular, Eje Central Lazaro Cardenas No. 152, 07730 Mexico D.F. (Mexico); Guzman, M.L. [Instituto Mexicano del Petroleo, Programa de Ingenieria Molecular, Eje Central Lazaro Cardenas No. 152, 07730 Mexico D.F. (Mexico); Montoya, J.A. [Instituto Mexicano del Petroleo, Programa de Ingenieria Molecular, Eje Central Lazaro Cardenas No. 152, 07730 Mexico D.F. (Mexico); Acosta, D.R. [Instituto de Fisica, Universidad Nacional Autonoma de Mexico, A. P. 20-364, 01000 Mexico D.F. (Mexico)

    2005-11-15

    A sulfated Si-Zr-MCM-41 solid with highly ordered mesostructure was synthesized through a templated synthesis route where the CTAB surfactant was used as template. During the synthesis procedure, various amounts of (NH{sub 4}){sub 2}SO{sub 4} were added into the mixed solution of Zr and Si precursors to in situ sulfate the MCM-41 solids, aiming to enhance the acidity and thermal stability. The resultant materials showed a long-range ordered hexagonal arrangement with high surface area larger than 797 m{sup 2}/g and an average pore size distributed at approximate 2.5-2.8 nm. The high-resolution TEM observations confirmed that the order of the mesostructure gained when the molar ratio of SO{sub 4} {sup 2-}/(ZrO{sub 2} + SiO{sub 2}) increased from 0.1 to 0.3 but decreased as it reached 0.5, which is consistent with the results of {sup 29}Si MAS-NMR and XRD analysis. Compared to Si-MCM-41, the (Q{sup 2} + Q{sup 3})/Q{sup 4} ratio derived from the NMR spectra of the Zr-doped sample was higher, indicating that zirconium atoms were incorporated into the silica framework. Unexpectedly, in situ sulfation does not enhance the surface Broensted acidity, most likely due to the sulfur retained within the bulk of the materials; however, it indeed improved the thermal stability of the solid and long-range order of the structure.

  2. Influence of surfactant on dynamics of photoinduced motions in a dye-doped deoxyribonucleic acid

    Science.gov (United States)

    Mysliwiec, Jaroslaw; Parafiniuk, Kacper; Miniewicz, Andrzej; Rau, Ileana; Kajzar, Francois; Niziol, Jacek; Hebda, Edyta; Pielichowski, Jan; Sahraoui, Bouchta

    2012-10-01

    Pure deoxyribonucleic acid (DNA) is known to be soluble in water only and exhibits poor temperature stability. In contrary, it is well known that the complex of DNA - with cetyltrimethyl ammonium (CTMA) is soluble in alcohols and can be processed into very good optical quality thin films by solution casting and spin deposition. Despite the success of DNA-CTMA, there is still need for new cationic surfactants which would extend the range of available solvents for DNA complex. We test and present experimental results of influence of new surfactants based on benzalkonium chloride (BA), and didecyldimethylammonium chloride (DDCA) for applications in all optical switching.

  3. Investigations on the growth, optical, thermal, dielectric, and laser damage threshold properties of crystal violet dye-doped potassium acid phthalate single crystal

    Science.gov (United States)

    Rao, G. Babu; Rajesh, P.; Ramasamy, P.

    2016-03-01

    Influence of crystal violet dye with different concentration on potassium acid phthalate single crystal grown by conventional method has been studied. No change has been observed in the structure, whereas changes have been observed in the external morphology of the crystal when the dyes are incorporated in the crystal lattice. Thermogravimetric and differential thermal analyses show the onset decomposition temperatures to be at 302, 285, 284, and 285 °C for pure, 0.1, 0.3, and 0.5 mol% crystal violet-doped potassium acid phthalate crystals, respectively. The dielectric measurement was carried out on the grown crystals as a function of frequency at various temperatures. In addition, strong luminescent emission bands at 638, 648, and 640 nm were observed in which the relative intensity was found to be reversed as a result of doping concentration. The laser damage threshold value significantly increased for dye-doped crystal in comparison with pure crystal which may make it suitable for the solid-state dye laser applications.

  4. UV-A light-induced photodegradation of Acid Blue 113 in the presence of Sm-doped ZnO nanostructures

    Science.gov (United States)

    Pandiyarajan, Thangaraj; Mangalaraja, Ramalinga Viswanathan; Karthikeyan, Balasubramanian; Sathishkumar, Panneerselvam; Mansilla, Héctor D.; Contreras, David; Ruiz, José

    2015-05-01

    In this report, optical and photocatalytic degradation of Acid Blue 113 (AB 113) has been investigated in an aqueous heterogeneous media containing pure and Sm-doped ZnO nanostructures which were prepared by a simple wet chemical route. X-ray diffraction measurement confirmed that the prepared nanostructures were in hexagonal wurtzite structure and the dopant Sm ion was incorporated into the Zn lattice. Interesting morphological changes involving a nanosheet-star-spherical transition were observed upon Sm doping and annealing, which were identified through transmission electron microscope. Optical absorption measurements showed an exciton absorption band and a band gap narrowing with respect to the Sm concentrations. The photodegradation of Acid Blue 113 under UV-A radiation by using pure and Sm-doped ZnO nanostructures showed that samarium played an important role in the significant improvement of the photodegradation efficiency and the optimum amount of Sm ion was found to be 1 mmol %. Further, the possible degradation mechanism was proposed herein.

  5. Combination of cathodic reduction with adsorption for accelerated removal of Cr(VI) through reticulated vitreous carbon electrodes modified with sulfuric acid-glycine co-doped polyaniline.

    Science.gov (United States)

    Mo, Xi; Yang, Zhao-hui; Xu, Hai-yin; Zeng, Guang-ming; Huang, Jing; Yang, Xia; Song, Pei-pei; Wang, Li-ke

    2015-04-09

    Improving the reduction kinetics is crucial in the electroreduction process of Cr(VI). In this study, we developed a novel adsorption-electroreduction system for accelerated removal of Cr(VI) by employing reticulated vitreous carbon electrode modified with sulfuric acid-glycine co-doped polyaniline (RVC/PANI-SA-GLY). Firstly, response surface methodology confirmed the optimum polymerization condition of co-doped polyaniline for modifying electrodes (Aniline, sulfuric acid and glycine, respectively, of 0.2 mol/L, 0.85 mol/L, 0.93 mol/L) when untraditional dopant glycine was added. Subsequently, RVC/PANI-SA-GLY showed higher Cr(VI) removal percentages in electroreduction experiments over RVC electrode modified with sulfuric acid doped polyaniline (RVC/PANI-SA) and bare RVC electrode. In contrast to RVC/PANI-SA, the improvement by RVC/PANI-SA-GLY was more significant and especially obvious at more negative potential, lower initial Cr(VI) concentration, relatively less acidic solution and higher current densities, best achieving 7.84% higher removal efficiency with entire Cr(VI) eliminated after 900 s. Current efficiencies were likewise enhanced by RVC/PANI-SA-GLY under quite negative potentials. Fourier transform infrared (FTIR) and energy dispersive spectrometer (EDS) analysis revealed a possible adsorption-reduction mechanism of RVC/PANI-SA-GLY, which greatly contributed to the faster reduction kinetics and was probably relative to the absorption between protonated amine groups of glycine and HCrO4(-). Eventually, the stability of RVC/PANI-SA-GLY was proven relatively satisfactory.

  6. Au/ZnO hybrid nanocatalysts impregnated in N-doped graphene for simultaneous determination of ascorbic acid, acetaminophen and dopamine

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Xianlan [School of Science, Honghe University, Mengzi, Yunnan 661100 (China); Key Laboratory of Natural Pharmaceutical & Chemical Biology of Yunnan Province, Mengzi, Yunnan 661100 (China); Fujian Key Lab of Medical Instrument & Pharmaceutical Technology, Yishan Campus, Fuzhou University, Fuzhou, Fujian 350002 (China); Zhang, Guowei; Shi, Ling; Pan, Shanqing [School of Science, Honghe University, Mengzi, Yunnan 661100 (China); Key Laboratory of Natural Pharmaceutical & Chemical Biology of Yunnan Province, Mengzi, Yunnan 661100 (China); Liu, Wei, E-mail: liuwei4728@126.com [School of Science, Honghe University, Mengzi, Yunnan 661100 (China); Key Laboratory of Natural Pharmaceutical & Chemical Biology of Yunnan Province, Mengzi, Yunnan 661100 (China); Pan, Hiabo [Fujian Key Lab of Medical Instrument & Pharmaceutical Technology, Yishan Campus, Fuzhou University, Fuzhou, Fujian 350002 (China)

    2016-08-01

    The formation of nitrogen-doped (N-doped) graphene uses hydrothermal method with urea as reducing agent and nitrogen source. The surface elemental composition of the catalyst was analyzed through XPS, which showed a high content of a total N species (7.12 at.%), indicative of the effective N-doping, present in the form of pyridinic N, pyrrolic N and graphitic N groups. Moreover, Au nanoparticles deposited on ZnO nanocrystals surface, forming Au/ZnO hybrid nanocatalysts, undergo a super-hydrophobic to super-hydrophilic conversion. Herein, we present Au/ZnO hybrid nanocatalysts impregnated in N-doped graphene sheets through sonication technique of the Au/ZnO/N-doped graphene hybrid nanostructures. The as-prepared Au/ZnO/N-doped graphene hybrid nanostructure modified glassy carbon electrode (Au/ZnO/N-doped graphene/GCE) was first employed for the simultaneous determination of ascorbic acid (AA), dopamine (DA) and acetaminophen (AC). The oxidation over-potentials of AA, DA and AC decreased dramatically, and their oxidation peak currents increased significantly at Au/ZnO/N-doped graphene/GCE compared to those obtained at the N-doped graphene/GCE and bare CCE. The peak separations between AA and DA, DA and AC, and AC and AA are large up to 195, 198 and 393 mV, respectively. The calibration curves for AA, DA and AC were obtained in the range of 30.00–13.00 × 10{sup 3}, 2.00–0.18 × 10{sup 3} and 5.00–3.10 × 10{sup 3} μM, respectively. The detection limits (S/N = 3) were 5.00, 0.40 and 0.80 μM for AA, DA and AC, respectively. - Graphical abstract: A novel Au/ZnO/N-doped graphene hybrid nanostructure was synthesized for the electrochemical evaluation of AA, DA and AC. The formation of N-doped graphene uses hydrothermal method with urea as reducing agent and nitrogen source. Moreover, Au nanoparticles deposited on ZnO nanocrystals surface, forming Au/ZnO hybrid nanocatalysts, undergo a super-hydrophobic to superhydrophilic conversion. We present Au/ZnO hybrid

  7. Complete doping in solid-state by silica-supported perchloric acid as dopant solid acid: Synthesis and characterization of the novel chiral composite of poly [(±)-2-(sec-butyl) aniline

    Energy Technology Data Exchange (ETDEWEB)

    Farrokhzadeh, Abdolkarim; Modarresi-Alam, Ali Reza, E-mail: modaresi@chem.usb.ac.ir

    2016-05-15

    Poly [(±)-2-(sec-butyl) aniline]/silica-supported perchloric acid composites were synthesized by combination of poly[(±)-2-sec-butylaniline] base (PSBA) and the silica-supported perchloric acid (SSPA) as dopant solid acid in solid-state. The X-ray photoelectron spectroscopy (XPS) and CHNS results confirm nigraniline oxidation state and complete doping for composites (about 75%) and non-complete for the PSBA·HCl salt (about 49%). The conductivity of samples was (≈0.07 S/cm) in agreement with the percent of doping obtained of the XPS analysis. Also, contact resistance was determined by circular-TLM measurement. The morphology of samples by the scanning electron microscopy (SEM) and their coating were investigated by XPS, SEM-map and energy-dispersive X-ray spectroscopy (EDX). The key benefits of this work are the preparation of conductive chiral composite with the delocalized polaron structure under green chemistry and solid-state condition, the improvement of the processability by inclusion of the 2-sec-butyl group and the use of dopant solid acid (SSPA) as dopant. - Highlights: • The solid-state synthesis of the novel chiral composites of poly[(±)-2-(sec-butyl)aniline] (PSBA) and silica-supported perchloric acid (SSPA). • It takes 120 h for complete deprotonation of PSBA.HCl salt. • Use of SSPA as dopant solid acid for the first time to attain the complete doping of PSBA. • The coating of silica surface with PSBA.

  8. 不同质子酸二次掺杂聚苯胺的导电性能%Conductivity of Dual-doped Polyaniline Based on Different Protonic Acids

    Institute of Scientific and Technical Information of China (English)

    贾艺凡; 刘朝辉; 廖梓珺; 邓智平; 王飞; 叶圣天

    2016-01-01

    Eigenstate polyaniline was prepared by chemical oxidation method,and then was doped by four kinds of protonic acids (hydrochloric acid,phosphate acid,dodecylbenzene sulfonate acid and sulfosalicylic acid)to prepare dual-doped polyaniline (PANI).The most suitable doping conditions were obtained by studying the effects of protonic acids concentration,adopping time and temperature on conductivity of dual-doped PANI.Moreover,the structure and morphology of dual-doped PANI obtained under the most suitable conditions were investigated.The results indicate that the most suitable doping conditions were adoping condition of 1.0 mol•L-1 ,doping temperature of 25 ℃,doping time of 6 h.Dual-doped PANI obtained under the most suitable conditions had the highest conductivity,was 3.301 S•cm-1 .Compared with eigenstate polyaniline,the infrared characteristic peaks of dual doped PANI was wider and moved to low frequency.DBSA doped PANI had the highest crystallinity,and its microstructure was composed of scattered round particles.%首先通过化学氧化法制备本征态聚苯胺(EB),然后利用4种质子酸(DBSA、SSA、HCl、H 3 PO 4)对 EB 进行二次掺杂制备了二次掺杂聚苯胺(PANI),通过研究质子酸浓度、掺杂时间和掺杂温度对二次掺杂 PANI 电导率的影响,得到了最适宜的二次掺杂条件,并考察了最适宜掺杂条件下制备的二次掺杂 PANI 的结构和形貌.结果表明:最适宜的二次掺杂条件为掺杂剂浓度1.0 mol•L-1,掺杂时间6 h,掺杂温度为25℃,此时二次掺杂 PANI 的电导率最高,其中 DBSA 二次掺杂 PANI 的电导率最高,为3.301 S•cm-1;与 EB 相比,二次掺杂 PANI 的红外特征峰变宽且向低频移动;DBSA 二次掺杂 PANI 的结晶度最高,其微观结构由较为分散的圆形颗粒组成.

  9. Electrochemical polymerization and properties of polyaniline doped with different acids%不同酸掺杂聚苯胺的电化学聚合及性能

    Institute of Scientific and Technical Information of China (English)

    孙通; 李晓霞; 郭宇翔; 赵纪金; 马森; 赵楠

    2013-01-01

      采用循环伏安(CV)法在镀金PET膜上分别聚合了硫酸(H2SO4)、十二烷基苯磺酸(DBSA)、硫酸-十二烷基苯磺酸掺杂的聚苯胺(PANI)膜,对比研究了掺杂酸种类对PANI结构和性能的影响。结果表明,SO42−、DBSA−可以随聚合过程进入PANI分子链;H2SO4掺杂的PANI具有较高的电导率,但是在空气中的稳定性较差;大分子的DBSA使PANI优先产生单螺旋的纤维,提高了PANI在平行分子链方向上的结晶度和在空气中的稳定性;相对于单一酸掺杂,复合酸掺杂的PANI在酸溶液中电扫描表现出优良的循环伏安特性,在保持较高电导率的同时,提高了PANI在空气中的稳定性。%The effect of different types of acidic dopant namely,sulfuric acid (H2SO4),dodecyl benzene sulfonic acid (DBSA) and compounded acids (H2SO4+DBSA) on the morphology and properties of polyaniline (PANI) films polymerized on gold-plated PET substrates by cyclic voltammetry was investigated. SO42− and DBSA− could incorporate into PANI molecular chains in the polymerization progress. PANI doped with H2SO4 had high conductivity but poor stability in air,while PANI doped with macromolecules DBSA had high stability in air but poor conductivity. Compared with single acid,compounded acids doping could improve not only the characteristics of cyclic voltammogram of PANI in acid solution,but also its stability in air while maintaining high electrical conductivity of PANI.

  10. Layered Lithium-Rich Oxide Nanoparticles Doped with Spinel Phase: Acidic Sucrose-Assistant Synthesis and Excellent Performance as Cathode of Lithium Ion Battery.

    Science.gov (United States)

    Chen, Min; Chen, Dongrui; Liao, Youhao; Zhong, Xiaoxin; Li, Weishan; Zhang, Yuegang

    2016-02-01

    Nanolayered lithium-rich oxide doped with spinel phase is synthesized by acidic sucrose-assistant sol-gel combustion and evaluated as the cathode of a high-energy-density lithium ion battery. Physical characterizations indicate that the as-synthesized oxide (LR-SN) is composed of uniform and separated nanoparticles of about 200 nm, which are doped with about 7% spinel phase, compared to the large aggregated ones of the product (LR) synthesized under the same condition but without any assistance. Charge/discharge demonstrates that LR-SN exhibits excellent rate capability and cyclic stability: delivering an average discharge capacity of 246 mAh g(-1) at 0.2 C (1C = 250 mA g(-1)) and earning a capacity retention of 92% after 100 cycles at 4 C in the lithium anode-based half cell, compared to the 227 mA g(-1) and the 63% of LR, respectively. Even in the graphite anode-based full cell, LR-SN still delivers a capacity of as high as 253 mAh g(-1) at 0.1 C, corresponding to a specific energy density of 801 Wh kg(-1), which are the best among those that have been reported in the literature. The separated nanoparticles of the LR-SN provide large sites for charge transfer, while the spinel phase doped in the nanoparticles facilitates lithium ion diffusion and maintains the stability of the layered structure during cycling.

  11. Structural and optical study of spin-coated camphorsulfonic acid-doped polyaniline/titanium-di-oxide nanoparticles hybrid thin films

    Science.gov (United States)

    Geethalakshmi, D.; Muthukumarasamy, N.; Balasundaraprabhu, R.

    2015-06-01

    Polyaniline (PANI) doped with Camphorsulfonic acid (CSA) has been prepared by chemical oxidative polymerization and blend with titanium-di-oxide (TiO2) nanoparticles prepared by sol-gel method to form CSA-doped PANI/TiO2 hybrid thin films. The properties of as-deposited and heat-treated (100 °C) hybrid thin films having different PANI:TiO2 weight ratios (1:0.5, 1:1, and 1:2) have been compared. FTIR study indicated that chemical bonding between CSA-doped PANI and TiO2 has been formed. XRD studies reveal that the as-deposited hybrid thin films are of amorphous nature and heat-treatment of such films initiates crystallization. SEM study shows that as-deposited hybrid films are rough; increase in TiO2 ratio and heat-treatment increased the roughness due to coalescing and agglomeration. UV-visible absorbance of hybrid films shows its characteristic peak in the visible region along with a peak in UV range and its intensity increased with TiO2 ratio and heat-treatment due to agglomeration of TiO2 particles. Photoluminescence spectra revealed that emission occurs in visible region (495 nm) for as-deposited hybrid thin film and this emission increased with TiO2 ratio and heat-treatment of hybrid films.

  12. Metal-free N-doped carbon nanofibers as an efficient catalyst for oxygen reduction reactions in alkaline and acid media

    Science.gov (United States)

    Li, Ruchun; Shao, Xiaofeng; Li, Shuoshuo; Cheng, Pengpeng; Hu, Zhaoxia; Yuan, Dingsheng

    2016-12-01

    The development of metal-free catalysts to replace the use of Pt has played an important role in relation to its application to fuel cells. We report N-doped carbon nanofibers as the catalyst of an oxygen reduction reaction, which were synthesized via carbonizing bacterial cellulose-polypyrrole composites. The as-prepared material exhibited remarkable catalytic activity toward the oxygen reduction reaction with comparable onset potential and the ability to limit the current density of commercial Pt/C catalysts in both alkaline and acid media due to the unique porous three-dimensional network structure and the doped nitrogen atoms. The effect of N functionalities on catalytic behavior was systematically investigated. The results demonstrated that pyridinic-N was the dominating factor for catalytic performance toward the oxygen reduction reaction. Additionally, N-doped carbon nanofibers also demonstrated excellent cycling stability (93.2% and 89.4% retention of current density after chronoamperometry 20 000 s in alkaline and media, respectively), obviously superior to Pt/C.

  13. Fouling behaviors of polybenzimidazole (PBI)-polyhedral oligomeric silsesquioxane (POSS)/polyacrylonitrile (PAN) hollow fiber membranes for engineering osmosis processes

    KAUST Repository

    Chen, Sicong

    2014-02-01

    This paper investigated the individual effects of reverse salt flux and permeate flux on fouling behaviors of as-spun and annealed polybenzimidazole (PBI)-polyhedral oligomeric silsesquioxane (POSS)/polyacrylonitrile (PAN) hollow fiber membranes under forward osmosis (FO) and pressure retarded osmosis (PRO) processes. Two types of membrane fouling had been studied; namely, inorganic fouling (CaSO4·2H2O gypsum scaling) during FO operations and organic fouling (sodium alginate fouling) during PRO operations. It is found that gypsum scaling on the membrane surface may be inhibited and even eliminated with an increase in reverse MgCl2 flux due to competitive formations of MgSO4° and CaSO4·2H2O. In contrast, the increase of reverse NaCl flux exhibits a slight enhancement on alginate fouling in both FO and PRO processes. Comparing to the reverse salt flux, the permeate flux always plays a dominant role in fouling. Therefore, lesser fouling has been observed on the membrane surface under the pressurized PRO process than FO process because the reduced initial flux mitigates the fouling phenomena more significantly than the enhancement caused by an increase in reverse NaCl flux. © 2013 Elsevier B.V.

  14. Gypsum (CaSO42H2O) scaling on polybenzimidazole and cellulose acetate hollow fiber membranes under forward osmosis

    KAUST Repository

    Chen, Si Cong

    2013-11-08

    We have examined the gypsum (CaSO42H2O) scaling phenomena on membranes with different physicochemical properties in forward osmosis (FO) processes. Three hollow fiber membranes made of (1) cellulose acetate (CA), (2) polybenzimidazole (PBI)/polyethersulfone (PES) and (3) PBI-polyhedral oligomeric silsesquioxane (POSS)/polyacrylonitrile (PAN) were studied. For the first time in FO processes, we have found that surface ionic interactions dominate gypsum scaling on the membrane surface. A 70% flux reduction was observed on negatively charged CA and PBI membrane surfaces, due to strong attractive forces. The PBI membrane surface also showed a slightly positive charge at a low pH value of 3 and exhibited a 30% flux reduction. The atomic force microscopy (AFM) force measurements confirmed a strong repulsive force between gypsum and PBI at a pH value of 3. The newly developed PBI-POSS/PAN membrane had ridge morphology and a contact angle of 51.42 14.85 after the addition of hydrophilic POSS nanoparticles and 3 min thermal treatment at 95 C. Minimal scaling and an only 1.3% flux reduction were observed at a pH value of 3. Such a ridge structure may reduce scaling by not providing a locally flat surface to the crystallite at a pH value of 3; thus, gypsum would be easily washed away from the surface. 2013 by the authors; licensee MDPI, Basel, Switzerland.

  15. Improved Durability of Electrocatalyst Based on Coating of Carbon Black with Polybenzimidazole and their Application in Polymer Electrolyte Fuel Cells.

    Science.gov (United States)

    Fujigaya, Tsuyohiko; Hirata, Shinsuke; Berber, Mohamed R; Nakashima, Naotoshi

    2016-06-15

    Improvement of durability of the electrocatalyst has been the key issue to be solved for the practical application of polymer electrolyte membrane fuel cells. One of the promising strategies to improve the durability is to enhance the oxidation stability of the carbon-supporting materials. In this report, we describe in detail the mechanism of the stability improvement of carbon blacks (CBs; Vulcan and Ketjen) by coating with polybenzimidazole (PBI). Nitrogen adsorption experiments reveal that the PBI coating of CBs results in the capping of the gates of the CB-micropores by the PBI. Since the surface of the micropores inside the CBs are inherently highly oxidized, the capping of such pores effectively prevents the penetration of the electrolyte into the pore and works to avoid the further oxidation of interior of the micropore, which is proved by cyclic voltammogram measurements. Above mechanism agrees very well with the dramatic enhancement of the durability of the membrane electrode assembly fabricated using Pt on the PBI-coated CBs as an electrocatalyst compared to the conventional Pt/CB (PBI-non coated) catalyst.

  16. The neural networks based modeling of a polybenzimidazole-based polymer electrolyte membrane fuel cell: Effect of temperature

    Science.gov (United States)

    Lobato, Justo; Cañizares, Pablo; Rodrigo, Manuel A.; Linares, José J.; Piuleac, Ciprian-George; Curteanu, Silvia

    Neural network models represent an important tool of Artificial Intelligence for fuel cell researchers in order to help them to elucidate the processes within the cells, by allowing optimization of materials, cells, stacks, and systems and support control systems. In this work three types of neural networks, that have as common characteristic the supervised learning control (Multilayer Perceptron, Generalized Feedforward Network and Jordan and Elman Network), have been designed to model the performance of a polybenzimidazole-polymer electrolyte membrane fuel cells operating upon a temperature range of 100-175 °C. The influence of temperature of two periods was studied: the temperature in the conditioning period and temperature when the fuel cell was operating. Three inputs variables: the conditioning temperature, the operating temperature and current density were taken into account in order to evaluate their influence upon the potential, the cathode resistance and the ohmic resistance. The Multilayer Perceptron model provides good predictions for different values of operating temperatures and potential and, hence, it is the best choice among the study models, recommended to investigate the influence of process variables of PEMFCs.

  17. The neural networks based modeling of a polybenzimidazole-based polymer electrolyte membrane fuel cell: Effect of temperature

    Energy Technology Data Exchange (ETDEWEB)

    Lobato, Justo; Canizares, Pablo; Rodrigo, Manuel A.; Linares, Jose J. [Chemical Engineering Department, University of Castilla-La Mancha, Campus Universitario s/n. 13004, Ciudad Real (Spain); Piuleac, Ciprian-George; Curteanu, Silvia [Gh. Asachi Technical University Iasi, Department of Chemical Engineering (Romania)

    2009-07-01

    Neural network models represent an important tool of Artificial Intelligence for fuel cell researchers in order to help them to elucidate the processes within the cells, by allowing optimization of materials, cells, stacks, and systems and support control systems. In this work three types of neural networks, that have as common characteristic the supervised learning control (Multilayer Perceptron, Generalized Feedforward Network and Jordan and Elman Network), have been designed to model the performance of a polybenzimidazole-polymer electrolyte membrane fuel cells operating upon a temperature range of 100-175 C. The influence of temperature of two periods was studied: the temperature in the conditioning period and temperature when the fuel cell was operating. Three inputs variables: the conditioning temperature, the operating temperature and current density were taken into account in order to evaluate their influence upon the potential, the cathode resistance and the ohmic resistance. The Multilayer Perceptron model provides good predictions for different values of operating temperatures and potential and, hence, it is the best choice among the study models, recommended to investigate the influence of process variables of PEMFCs. (author)

  18. Study of the catalytic layer in polybenzimidazole-based high temperature PEMFC: effect of platinum content on the carbon support

    Energy Technology Data Exchange (ETDEWEB)

    Lobato, J.; Canizares, P.; Rodrigo, M.A.; Linares, J.J.; Ubeda, D.; Pinar, F.J. [Chemical Engineering Department, University of Castilla-La Mancha, Ciudad Real (Spain)

    2010-04-15

    In this work, the effect of platinum percentage on the carbon support of commercial catalyst for electrodes to be used in a Polybenzimidazole (PBI)-based PEMFC has been studied. Three percentages were studied (20, 40 and 60%). In all cases, the same quantity of PBI in the catalyst layer was added, which is required as a 'binder'. From Hg porosimetry analyses, pore size distribution, porosity, mean pore size and tortuosity of all electrodes were obtained. The amount of mesopores gets larger as the platinum percentage in the catalytic layer decreases, which reduces the overall porosity and the mean pore size and increases the tortuosity. The electrochemical characterisation was performed by voltamperometric studies, assessing the effective electrochemical surface area (ESA) of the electrodes, by impedance spectroscopy (IS), determining the polarisation resistance, and by the corresponding fuel cell measurements. The best results were obtained for the electrodes with a content of 40% Pt on carbon, as a result of an adequate combination of catalytic activity and mass transfer characteristics of the electrode. It has been demonstrated that the temperature favours the fuel cell performance, and the humidification does not have remarkable effects on the performance of a PBI-based polymer electrolyte membrane fuel cell (PEMFC). (Abstract Copyright [2010], Wiley Periodicals, Inc.)

  19. Effect of erbium-doped: yttrium, aluminium and garnet laser irradiation on the surface microstructure and roughness of sand-blasted, large grit, acid-etched implants

    OpenAIRE

    2011-01-01

    Purpose The present study was performed to evaluate the effect of erbium-doped: yttrium, aluminium and garnet (Er:YAG) laser irradiation on sand-blasted, large grit, acid-etched (SLA) implant surface microstructure according to varying energy levels and application times of the laser. Methods The implant surface was irradiated by the Er:YAG laser under combined conditions of 100, 140, or 180 mJ/pulse and an application time of 1 minute, 1.5 minutes, or 2 minutes. Scanning electron microscopy ...

  20. Effects of the sintering temperature on the flux-pinning mechanism and the activation energy of malic-acid doped MgB2

    Directory of Open Access Journals (Sweden)

    J Peleckis

    2012-12-01

    Full Text Available   The flux-pinning mechanism and activation energy of 10 wt % malic acid-doped MgB2 were investigated by measuring of the critical current density and resistivity as a function of magnetic field and temperature. A crossover field, Bsb, was observed from the single vortex to the small vortex bundle pinning regime. For the sintered sample, the temperature dependence of Bsb(T at low temperature is in good agreement with the δℓ pinning mechanism, i.e., pinning associated with charge-carrier mean free path fluctuation. The activation energy was decreased by increasing the magnetic field and increased by increasing sintering temperature.

  1. Nanocomposite membranes based on polybenzimidazole and ZrO2 for high-temperature proton exchange membrane fuel cells.

    Science.gov (United States)

    Nawn, Graeme; Pace, Giuseppe; Lavina, Sandra; Vezzù, Keti; Negro, Enrico; Bertasi, Federico; Polizzi, Stefano; Di Noto, Vito

    2015-04-24

    Owing to the numerous benefits obtained when operating proton exchange membrane fuel cells at elevated temperature (>100 °C), the development of thermally stable proton exchange membranes that demonstrate conductivity under anhydrous conditions remains a significant goal for fuel cell technology. This paper presents composite membranes consisting of poly[2,2'-(m-phenylene)-5,5'-bibenzimidazole] (PBI4N) impregnated with a ZrO2 nanofiller of varying content (ranging from 0 to 22 wt %). The structure-property relationships of the acid-doped and undoped composite membranes have been studied using thermogravimetric analysis, differential scanning calorimetry, dynamic mechanical analysis, wide-angle X-ray scattering, infrared spectroscopy, and broadband electrical spectroscopy. Results indicate that the level of nanofiller has a significant effect on the membrane properties. From 0 to 8 wt %, the acid uptake as well as the thermal and mechanical properties of the membrane increase. As the nanofiller level is increased from 8 to 22 wt % the opposite effect is observed. At 185 °C, the ionic conductivity of [PBI4N(ZrO2 )0.231 ](H3 PO4 )13 is found to be 1.04×10(-1)  S cm(-1) . This renders membranes of this type promising candidates for use in high-temperature proton exchange membrane fuel cells.

  2. The use of imidazolium ionic liquid/copper complex as novel and green catalyst for chemiluminescent detection of folic acid by Mn-doped ZnS nanocrystals

    Science.gov (United States)

    Azizi, Seyed Naser; Shakeri, Parmis; Chaichi, Mohammad Javad; Bekhradnia, Ahmadreza; Taghavi, Mehdi; Ghaemy, Mousa

    2014-03-01

    A novel chemiluminescence (CL) method using water-soluble Mn-doped ZnS quantum dots (QDs) as CL emitter is proposed for the chemiluminometric determination of folic acid in pharmaceutical formulation. Water-soluble Mn-doped ZnS QDs were synthesized by using L-cysteine as stabilizer in aqueous solutions. The nanoparticles were structurally and optically characterized by X-ray powder diffraction (XRD), dynamic light scattering (DLS), Fourier transform infrared spectroscopy (FTIR), UV-Vis absorption spectroscopy and photoluminescence (PL) emission spectroscopy. The CL of ZnS QDs induced by directly chemical oxidation and its ionic liquid-sensitized effect in aqueous solution were then investigated. It was found that oxidants, especially hydrogen peroxide, could directly oxidize ZnS QDs to produce weak CL emission in basic conditions. In the presence of 1,3-dipropylimidazolium bromide/copper a drastic light emission enhancement is observed, related to a strong interaction between Cu2+ and the imidazolium ring. Therefore, a new CL analysis system was developed for the determination of folic acid. Under the optimum conditions, there is a good linear relationship between the relative CL intensity and the concentration of folic acid in the range of 1 × 10-9-1 × 10-6 M of folic acid with a correlation coefficient (R2) of 0.9991. The limit of detection of this system was found to be 1 × 10-10 M. This method is not only simple, sensitive and low cost, but also reliable for practical applications.

  3. Electro-fenton and photoelectro-fenton degradation of sulfanilic acid using a boron-doped diamond anode and an air diffusion cathode.

    Science.gov (United States)

    El-Ghenymy, Abdellatif; Garrido, José Antonio; Centellas, Francesc; Arias, Conchita; Cabot, Pere Lluís; Rodríguez, Rosa María; Brillas, Enric

    2012-04-01

    The mineralization of sulfanilic acid has been studied by electro-Fenton (EF) and photoelectro-Fenton (PEF) reaction with UVA light using an undivided electrochemical cell with a boron-doped diamond (BDD) anode and an air diffusion cathode able to generate H(2)O(2). Organics were then oxidized by hydroxyl radicals formed at the anode surface from water oxidation and in the bulk from Fenton's reaction between generated H(2)O(2) and added Fe(2+). The UVA irradiation in PEF enhanced the production of hydroxyl radicals in the bulk, accelerating the removal of organics and photodecomposed intermediates like Fe(III)-carboxylate complexes. Partial decontamination of 1.39 mM sulfanilic acid solutions was achieved by EF until 100 mA cm(-2) at optimum conditions of 0.4 mM Fe(2+) and pH 3.0. The increase in current density and substrate content led to an almost total mineralization. In contrast, the PEF process was more powerful, yielding almost complete mineralization in less electrolysis time under comparable conditions. The kinetics for sulfanilic acid decay always followed a pseudo-first-order reaction. Hydroquinone and p-benzoquinone were detected as aromatic intermediates, whereas acetic, maleic, formic, oxalic, and oxamic acids were identified as generated carboxylic acids. NH(4)(+) ion was preferentially released in both treatments, along with NO(3)(-) ion in smaller proportion.

  4. Crosslinked Hexafluoropropylidene Polybenzimidazole Membranes with Chloromethyl Polysulfone for Fuel Cell Applications

    DEFF Research Database (Denmark)

    Yang, Jingshuai; Li, Qingfeng; Cleemann, Lars Nilausen;

    2013-01-01

    membranes with chloromethyl polysulfone as a polymeric crosslinker. Comparing with linear F6PBI and mPBI membranes, the polymer crosslinked F6PBI membranes exhibited little organo solubility, excellent stability towards the radical oxidation, high resistance to swelling in concentrated phosphoric acid...

  5. Effective role of trifluoroacetic acid (TFA) to enhance the photocatalytic activity of F-doped TiO{sub 2} prepared by modified sol–gel method

    Energy Technology Data Exchange (ETDEWEB)

    Samsudin, Emy Marlina [Nanotechnology and Catalysis Research Centre, University of Malaya, 50603 Kuala Lumpur (Malaysia); Hamid, Sharifah Bee Abd, E-mail: sharifahbee@um.edu.my [Nanotechnology and Catalysis Research Centre, University of Malaya, 50603 Kuala Lumpur (Malaysia); Juan, Joon Ching; Basirun, Wan Jefrey [Nanotechnology and Catalysis Research Centre, University of Malaya, 50603 Kuala Lumpur (Malaysia); Kandjani, Ahmad Esmaielzadeh; Bhargava, Suresh K. [Centre of Advanced Materials and Industrial Chemistry, RMIT University, Melbourne 3001 (Australia)

    2016-03-01

    Graphical abstract: - Highlights: • Surface-fluorinated TiO{sub 2} with superior properties. • Generation of free surface hydroxyl radicals. • Excellent photo-generated electron and holes separation. • Mixed morphologies of truncated and compressed bipyramids. • Superior photo-kinetics performance. - Abstract: Highly photoactive mesoporous F-doped TiO{sub 2} with improved physico-chemical characteristics is achieved using modified sol–gel method. The usage of trifluoroacetic as fluorine precursor significantly modifies the morphology, size, pore shape, crystal phase, crystal structure, surface chemical state and to a lesser extent, {1 0 1} and {0 0 1} facets. The accessibility of fluoride ions on Ti−O−Ti polymer chains during crystal growth during the sol–gel process remarkably influences the properties of catalyst. To the best of our knowledge, preparation of F-doped TiO{sub 2} using modified sol–gel and trifluoroacetic acid are limited, and still not enough. Thus this work provides additional insight by using an approach which is less hazardous, less costly and practical for large scale agile development in the photocatalysis industry.

  6. Increasing the Fill Factor of Inverted P3HT:PCBM Solar Cells Through Surface Modification of Al-Doped ZnO via Phosphonic Acid-Anchored C60 SAMs

    DEFF Research Database (Denmark)

    Stubhan, Tobias; Salinas, Michael; Ebel, Alexander;

    2012-01-01

    The influence of aluminum-doped zinc oxide (AZO) electron extraction layers modified with self-assembled monolayers (SAMs) on inverted polymer solar cells is investigated. It is found that AZO modification with phosphonic acid-anchored Fullerene–SAMs leads to a reduction of the series resistance,...

  7. Visbreaking of heavy petroleum oil catalyzed by SO42-/ZrO2 solid super-acid doped with Ni2+ or Sn2+

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    SO42-/ZrO2 solid super-acid catalysts (SZ)doped with Ni2+ or Sn2+ (Ni2+/SZ,Sn2+/SZ) were prepared for catalytic visbreaking of heavy petroleum oil from Shengli oil field.The visbreaking reactions were carried out at 240℃ and 3-4 MPa for 24 h using a heavy petroleum oil to catalyst mass ratio of 100 :0.05.The effect of water content on viscosity of heavy petroleum oil was also investigated.Both catalysts can promote thermolysis of heavy petroleum oil and the viscosity was reduced for (Sn2+/SZ) with visbreaking rates of 57.7% and 48.9%,respectively.After visbreaking,the saturated hydrocarbon content increased while aromatics,resin,asphaltene,sulfur and nitrogen content decreased.The presence of water was disadvantageous to visbreaking of heavy petroleum oil.

  8. An ultrasensitive electrochemical sensor for simultaneous determination of xanthine, hypoxanthine and uric acid based on Co doped CeO{sub 2} nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Lavanya, N. [Department of Bioelectronics and Biosensors, Alagappa University, Karaikudi 630003, Tamilnadu (India); Sekar, C., E-mail: Sekar2025@gmail.com [Department of Bioelectronics and Biosensors, Alagappa University, Karaikudi 630003, Tamilnadu (India); Murugan, R.; Ravi, G. [Department of Physics, Alagappa University, Karaikudi 630003, Tamilnadu (India)

    2016-08-01

    A novel electrochemical sensor has been fabricated using Co doped CeO{sub 2} nanoparticles for selective and simultaneous determination of xanthine (XA), hypoxanthine (HXA) and uric acid (UA) in a phosphate buffer solution (PBS, pH 5.0) for the first time. The Co-CeO{sub 2} NPs have been prepared by microwave irradiation method and characterized by Powder XRD, Raman spectroscopy, HRTEM and VSM measurements. The electrochemical behaviours of XA, HXA and UA at the Co-CeO{sub 2} NPs modified glassy carbon electrode (GCE) were studied by cyclic voltammetry and square wave voltammetry methods. The modified electrode exhibited remarkably well-separated anodic peaks corresponding to the oxidation of XA, HXA and UA over the concentration range of 0.1–1000, 1–600 and 1–2200 μM with detection limits of 0.096, 0.36, and 0.12 μM (S/N = 3), respectively. For simultaneous detection by synchronous change of the concentrations of XA, HXA and UA, the linear responses were in the range of 1–400 μM each with the detection limits of 0.47, 0.26, and 0.43 μM (S/N = 3), respectively. The fabricated sensor was further applied to the detection of XA, HXA and UA in human urine samples with good selectivity and high reproducibility. - Highlights: • A novel electrochemical sensor has been fabricated for simultaneous determination of purine metabolites xanthine, hypoxanthine, and uric acid based on Co doped CeO{sub 2} nanoparticles. • The Co-CeO{sub 2} modified glassy carbon electrode exhibited wide linear range towards the detection of XA, HXA and UA than ever reported in the literature. • The fabricated sensor was successfully applied for the analysis of human urine samples with satisfactory results.

  9. Nanocrystalline semiconductor doped rare earth oxide for the photocatalytic degradation studies on Acid Blue 113: A di-azo compound under UV slurry photoreactor.

    Science.gov (United States)

    Suganya Josephine, G A; Mary Nisha, U; Meenakshi, G; Sivasamy, A

    2015-11-01

    Preventive measures for the control of environmental pollution and its remediation has received much interest in recent years due to the world-wide increase in the contamination of water bodies. Contributions of these harmful effluents are caused by the leather processing, pharmaceutical, cosmetic, textile, agricultural and other chemical industries. Nowadays, advanced oxidation processes considered to be better option for the complete destruction of organic contaminants in water and wastewater. Acid Blue 113 is a most widely used di-azo compound in leather, textile, dying and food industry as a color rending compound. In the present study, we have reported the photo catalytic degradation of Acid Blue 113 using a nanocrystalline semiconductor doped rare earth oxide as a photo catalyst under UV light irradiation. The photocatalyst was prepared by a simple precipitation technique and were characterized by XRD, FT-IR, UV-DRS and FE-SEM analysis. The experimental results proved that the prepared photo catalyst was nanocrystalline and highly active in the UV region. The UV-DRS results showed the band gap energy was 3.15eV for the prepared photo catalyst. The photodegradation efficiency was analyzed by various experimental parameters such as pH, catalyst dosage, variation of substrate concentration and effect of electrolyte addition. The photo degradation process followed a pseudo first order kinetics and was continuously monitored by UV-visible spectrophotometer. The experimental results proved the efficacy of the nanocrystalline zinc oxide doped dysprosium oxide which are highly active under UV light irradiations. It is also suggested that the prepared material would find wider applications in environmental remediation technologies to remove the carcinogenic and toxic moieties present in the industrial effluents.

  10. Highly selective and effective solid phase microextraction of benzoic acid esters using ionic liquid functionalized multiwalled carbon nanotubes-doped polyaniline coating.

    Science.gov (United States)

    Ai, Youhong; Wu, Mian; Li, Lulu; Zhao, Faqiong; Zeng, Baizhao

    2016-03-11

    The present work reports the electrochemical fabrication of an ionic liquid functionalized multiwalled carbon nanotubes-polyaniline (MWCNT@IL/PANI) nanocomposite coating and its application in the headspace-solid phase microextraction (HS-SPME) and gas chromatography (GC) determination of benzoic acid esters (i.e., methyl benzoate, ethyl benzoate, propyl benzoate and butyl benzoate). The MWCNTs was firstly functionalized with amine-terminated IL (MWCNT@IL) through chemical reduction, and then was doped in PANI during the electropolymerization of aniline. The resulting coating was characterized by infrared spectroscopy, field emission scanning electron microscopy and thermo gravimetry. It showed net-like structure and had high thermal stability (up to 330°C). Furthermore, it presented high selectivity for the four benzoic acid esters and thus suited for their HS-SPME-GC determination. Results showed that under optimized extraction conditions, the detection limits were less than 6.1ngL(-1) (S/N=3) and the linear detection ranges were 0.012-50μgL(-1) (R≥0.9957) for these analytes. The relative standard deviations (RSDs) were lower than 6.4% for five successive measurements with one fiber, and the RSDs for fiber-to-fiber were 4.4-9.6% (n=5). The developed method was successfully applied to the determination of these benzoic acid esters in perfume samples.

  11. Self-doped anthranilic acid-pyrrole copolymer/gold electrodes for selective preconcentration and determination of Cu(I) by differential pulse anodic stripping voltammetry.

    Science.gov (United States)

    Nateghi, M R; Fallahian, M H

    2007-05-01

    Electropolymerization of anthranilic acid/pyrrole (AA/PY) at solid substrate electrodes (platinum, gold, and glassy carbon) gave stable and water-insoluble films under a wide range of pH. Combining high conductivity of the polypyrrole (PPY) and pH independence of the electrochemical activity of the self-doped carboxylic acid-substituted polyaniline allows us to prepare an improved functionalized PPY-modified electrode to collect and measure Cu(I) species. The differential pulse stripping analysis of the copper ions using a polyanthranilic acid-co-polypyrrole (PAA/PPY)-modified electrode consisted of three steps: accumulation, electrochemical reduction to the elemental copper and stripping step. Factors affecting these steps, including electropolymerization conditions, accumulation and stripping medium, reduction potential, reduction time and accumulation time, were systematically investigated. A detection limit of 5.3 x 10(-9) M Cu(I) was achieved for a 7.0 min accumulation. For 12 determinations of Cu(I) at concentrations of 1.0 x 10(-8) M, an RSD of 3.5% was obtained. The log I(p) was found to vary linearly with log[Cu(I)] in the concentration range from 7.0 x 10(-9) to 1.0 x 10(-5) M.

  12. Boronic acid functionalized N-doped carbon quantum dots as fluorescent probe for selective and sensitive glucose determination

    Science.gov (United States)

    Jiang, Guohua; Jiang, Tengteng; Li, Xia; Wei, Zheng; Du, Xiangxiang; Wang, Xiaohong

    2014-04-01

    Nitrogen doped carbon quantum dots (NCQDs) of about 10 nm in diameter have been obtained by hydrothermal reaction from collagen. Because of the superiority of water dispersion, low toxicity and ease of functionlization, the NCQDs were designed as a glucose sensor after covalent grafting by 3-aminophenylboronic (APBA) (APBA-NCQDs). The as-prepared APBA-NCQDs were imparted with glucose sensitivity and selectivity from other saccharides via fluorescence (FL) quenching effect at physiological pH and at room temperature, which show high sensitivity and specificity for glucose determination with a wide range from 1 mM to 14 mM. FL quenching mechanism of APBA-NCQDs was also investigated by adding an external quencher. The APBA-NCQDs-based platform is an environmentally friendly way to substitute inorganic quantum dots containing heavy metals which offer a facile and low cost detection method.

  13. Palladium Nanoparticles Supported on Nitrogen and Sulfur Dual-Doped Graphene as Highly Active Electrocatalysts for Formic Acid and Methanol Oxidation.

    Science.gov (United States)

    Zhang, Xin; Zhu, Jixin; Tiwary, Chandra Sekhar; Ma, Zhongyuan; Huang, Huajie; Zhang, Jianfeng; Lu, Zhiyong; Huang, Wei; Wu, Yuping

    2016-05-04

    Optimized designing of highly active electrocatalysts has been regarded as a critical point to the development of portable fuel cell systems with high power density. Here we report a facile and cost-effective strategy to synthesis of ultrafine Pd nanoparticles (NPs) supported on N and S dual-doped graphene (NS-G) nanosheets as multifunctional electrocatalysts for both direct formic acid fuel cell and direct methanol fuel cell. The incorporation of N and S atoms into graphene frameworks is achieved by a thermal treatment process, followed by the controlled growth of Pd NPs via a solvothermal approach. Owning to the unique structural features as well as the strong synergistic effects, the resulting Pd/NS-G hybrid exhibits outstanding electrocatalytic performance toward both formic acid and methanol electro-oxidation, such as higher anodic peak current densities and more exceptional catalytic stability than those of Pd/Vulcan XC-72R and Pd/undoped graphene catalysts. These findings open up new possibility in the construction of advanced Pd-based catalysts, which is conducive to solving the current bottlenecks of fuel cell technologies.

  14. Photoluminescence and thermoluminescence study of KCaSO{sub 4}Cl doped with Dy and Ce synthesized by acid distillation method

    Energy Technology Data Exchange (ETDEWEB)

    Kore, Bhushan P. [Department of Physics, RTM Nagpur University, Nagpur 440033 (India); Dhoble, N.S. [Department of Chemistry, Sevadal Mahila Mahavidyalaya, Nagpur 440009 (India); Lochab, S.P. [Inter-University Accelerator Center, Aruna Asaf Ali Marg, New Delhi 110067 (India); Dhoble, S.J., E-mail: sjdhoble@rediffmail.com [Department of Physics, RTM Nagpur University, Nagpur 440033 (India)

    2014-01-15

    Photoluminescence and thermoluminescence properties of KCaSO{sub 4}Cl doped with dysprosium and cerium have been studied. Dy/Ce doped KCaSO{sub 4}Cl phosphors were synthesized by the acid distillation method. The samples were characterized by XRD, SEM, PL and TL for structural, morphological and luminescence studies. The SEM image analysis of KCaSO{sub 4}Cl phosphor shows nearly spherical particles with diameter varying between 3–10 μm. In the present host Dy{sup 3+} emission at 482 and 573 nm is observed due to {sup 4}F{sub 9/2}→{sup 6}H{sub 15/2} and {sup 4}F{sub 9/2}→{sup 6}H{sub 13/2} transition, respectively, whereas the PL emission spectra of KCaSO{sub 4}Cl:Ce phosphor shows two luminescence bands at 307 nm and 326 nm and are attributed to the allowed inter configurational transitions from the 5d-level to the {sup 2}F{sub 5/2} and {sup 2}F{sub 7/2} levels of Ce{sup 3+} ion. Effect of annealing on the structure of the glow curve is investigated for KCaSO{sub 4}Cl:Dy phosphors. Thermoluminescence linearity has been studied for 0.1–9000 Gy dose of gamma rays. Linear behavior over a large dose range between 0.1 Gy and 170 Gy was found. In addition to this trap parameters of KCaSO{sub 4}Cl:Dy were studied using computerized glow curve deconvolution. -- Highlights: • The novel phosphor is first time prepared by acid distillation method. • This study reports the thermoluminescence properties of KCaSO{sub 4}Cl irradiated with gamma rays. • The trapping analysis was done by GCD function and Chen's peak shape method. • Its good photoluminescence property can be utilized in display devices as well. • The phosphor can be used as a good dosimeter for measuring the high doses of γ-rays.

  15. Kinetic study of formic acid degradation by Fe3+ doped TiO2 self-cleaning nanostructure surfaces prepared by cold spray

    Science.gov (United States)

    Sayyar, Zahra; Akbar Babaluo, Ali; Shahrouzi, Javad Rahbar

    2015-04-01

    A self-cleaning solution was introduced in this paper based on sol-gel and was applied for preparing self-cleaning TiO2. Fe3+ ions have been doped into the TiO2 crystal lattice. XRD analysis indicated that the obtained TiO2 powder contains mainly the anatase phase and TiO2 powder has a crystallite size distribution of 10-12 nm. SEM micrographs have also confirmed nanometric distribution of the obtained powder. A series of uniform and transparent TiO2 and Fe/TiO2 films were prepared by cold spray technique which may result in high uniformity in the final coated surfaces. Photocatalytic activity of the thin films was investigated through degradation of aqueous formic acid under UV-visible light. The Langmuir-Hinshelwood kinetic model was used to interpret quantitatively the observed kinetic experimental result. Comparative study of the obtained coated surfaces with those of uncoated surfaces, demonstrated a remarkable performance. The Fe/TiO2 films and their calcination at 650 °C demonstrated the highest photocatalytic activity.

  16. Lysine-doped polypyrrole/spider silk protein/poly(l-lactic) acid containing nerve growth factor composite fibers for neural application.

    Science.gov (United States)

    Zhang, Hong; Wang, Kefeng; Xing, Yiming; Yu, Qiaozhen

    2015-11-01

    Lysine-doped polypyrrole (PPy)/regenerated spider silk protein (RSSP)/poly(l-lactic) acid (PLLA)/nerve growth factor (NGF) (L-PRPN) composite scaffold was fabricated by co-axial electrospraying and electrospinning. This L-PRPN composite scaffold had a structure of microfibers with a core-shell structure as the stems and nanofibers as branches. Assessment in vitro demonstrated that the L-PRPN composite micro/nano-fibrous scaffold could maintain integrated structure for at least 4months and the pH value of PBS at about 7.28. It had good biocompatibility and cell adhesion and relatively stable conductivity. PC 12 cells cultured on this scaffold, anisotropic cell-neurite-cell-neurite or neurite-neurite sheets were formed after being cultured for 6days. Evaluations in vivo also showed that L-PRPN composite fibrous conduit was effective at bridging 2.0cm sciatic nerve gap in adult rat within 10months. This conduit and electrical stimulation (ES) through it promoted Schwann cell migration and axonal regrowth.

  17. Hyaluronic acid doped-poly(3,4-ethylenedioxythiophene)/chitosan/gelatin (PEDOT-HA/Cs/Gel) porous conductive scaffold for nerve regeneration.

    Science.gov (United States)

    Wang, Shuping; Guan, Shui; Zhu, Zhibo; Li, Wenfang; Liu, Tianqing; Ma, Xuehu

    2017-02-01

    Conducting polymer, as a "smart" biomaterial, has been increasingly used to construct tissue engineered scaffold for nerve tissue regeneration. In this study, a novel porous conductive scaffold was prepared by incorporating conductive hyaluronic acid (HA) doped-poly(3,4-ethylenedioxythiophene) (PEDOT-HA) nanoparticles into a chitosan/gelatin (Cs/Gel) matrix. The physicochemical characteristics of Cs/Gel scaffold with 0-10wt% PEDOT-HA were analyzed and the results indicated that the incorporation of PEDOT-HA into scaffold increased the electrical and mechanical properties while decreasing the porosity and water absorption. Moreover, in vitro biodegradation of scaffold displayed a declining trend with the PEDOT-HA content increased. About the biocompatibility of conductive scaffold, neuron-like rat phaeochromocytoma (PC12) cells were cultured in scaffold to evaluate cell adhesion and growth. 8% PEDOT-HA/Cs/Gel scaffold had a higher cell adhesive efficiency and cell viability than the other conductive scaffolds. Furthermore, cells in the scaffold with 8wt% PEDOT-HA expressed higher synapse growth gene of GAP43 and SYP compared with Cs/Gel control group. These results suggest that 8%PEDOT-HA/Cs/Gel scaffold is an attractive cell culture conductive substrate which could support cell adhesion, survival, proliferation, and synapse growth for the application in nerve tissue regeneration.

  18. Optical sensing of 3-phenoxybenzoic acid as a pyrethroid pesticides exposure marker by surface imprinting polymer capped on manganese-doped zinc sulfide quantum dots

    Directory of Open Access Journals (Sweden)

    Vivek Pandey

    2015-09-01

    Full Text Available The present communication deals with the synthesis of luminescent Mn-doped ZnS quantum dots (QDs anchored to surface imprinted polymer for the optical sensing of 3-phenoxy benzoic acid (3-PBA in urine samples. The combination of sensing and surface functionalization not only improves the selectivity of the method, but also increases the optosensing ability of the material for non-phosphorescent substances. The developed material was utilized for the selective and sensitive detection of 3-PBA in urine samples. The proposed method shows good linearity with a regression coefficient (R2 of 0.98. The limit of detection was found to be 0.117 μM. The method has an acceptable precision and accuracy which are found to be less than 8% and 80–90% respectively at three different concentrations. The quenching constant of quantum dot-molecular imprinted polymer was found to be 3.4 times higher to that of the quantum dot-non imprinted polymer (QD-NIP as calculated by Stern–Volmer equation. The sensing method developed has shown immense utility to detect 3-PBA in complex biological samples like urine.

  19. N-doped carbon dots derived from bovine serum albumin and formic acid with one- and two-photon fluorescence for live cell nuclear imaging.

    Science.gov (United States)

    Tan, Mingqian; Li, Xintong; Wu, Hao; Wang, Beibei; Wu, Jing

    2015-12-01

    Carbon dots with both one- and two-photon fluorescence have drawn great attention for biomedical imaging. Herein, nitrogen-doped carbon dots were facilely developed by one-pot hydrothermal method using bovine serum albumin and formic acid as carbon sources. They are highly water-soluble with strong fluorescence when excited with ultraviolet or near infrared light. The carbon dots have a diameter of ~8.32 nm and can emit strong two-photon induced fluorescence upon excitation at 750 nm with a femtosecond laser. X-ray photoelectron spectrometer analysis revealed that the carbon dots contained three components, C, N and O, corresponding to the peak at 285, 398 and 532 eV, respectively. The Fourier-transform infrared spectroscopy analysis revealed that there are carboxyl and carboxylic groups on the surface, which allowed further linking of functional molecules. pH stability study demonstrated that the carbon dots are able to be used in a wide range of pH values. The fluorescence mechanism is also discussed in this study. Importantly, these carbon dots are biocompatible and highly photostable, which can be directly applied for both one- and two-photon living cell imaging. After proper surface functionalization with TAT peptide, they can be used as fluorescent probes for live cell nuclear-targeted imaging.

  20. Fluorine doped zinc oxide thin films deposited by chemical spray, starting from zinc pentanedionate and hydrofluoric acid: Effect of the aging time of the solution

    Energy Technology Data Exchange (ETDEWEB)

    Biswal, R.R. [Amity Institute of Nanotechnology, Amity University, Sector-125, Super Express Highway, Noida 201301 (India); Departamento de Ingenieria Electrica, Centro de Investigacion y de Estudios Avanzados del Instituto Politecnico Nacional, CINVESTAV-IPN, SEES, Apartado Postal 14740, Mexico, D.F., 07000 (Mexico); Velumani, S.; Babu, B.J.; Maldonado, A. [Departamento de Ingenieria Electrica, Centro de Investigacion y de Estudios Avanzados del Instituto Politecnico Nacional, CINVESTAV-IPN, SEES, Apartado Postal 14740, Mexico, D.F., 07000 (Mexico); Tirado-Guerra, S. [Escuela Superior de Fisica y Matematicas, Instituto Politecnico Nacional, IPN, Apartado Postal 75-544, Mexico, D.F., 07300 (Mexico); Castaneda, L. [Instituto de Fisica, Universidad Autonoma de Puebla, Apartado Postal J-48, Puebla 72570 (Mexico); Olvera, M. de la L, E-mail: molvera@cinvestav.mx [Departamento de Ingenieria Electrica, Centro de Investigacion y de Estudios Avanzados del Instituto Politecnico Nacional, CINVESTAV-IPN, SEES, Apartado Postal 14740, Mexico, D.F., 07000 (Mexico)

    2010-10-25

    Fluorine doped zinc oxide thin films, ZnO:F, were deposited on sodocalcic glass substrates, starting from zinc pentanedionate and hydrofluoric acid, by the chemical spray technique. The effect of the aging time of the starting solution on the electrical, structural, morphological and optical characteristics of the ZnO thin films was studied. Uniform, adherent, and mirror-like films were deposited at different days. A high electrical resistivity, was found in the films deposited the first day. However, a decrease in the resistivity, until a minimum, in the order of 3 x 10{sup -2} {Omega} cm was reached for films deposited after the starting solution was aged for twelve days. The films fit well with the hexagonal, wurtzite-type ZnO structure, with a (0 0 2) preferential growth. Variation in the grain size was observed as a consequence of the aging of the solution. An average crystallite size varied between 17.3 and 22.8 nm due to aging effect, and some variations in surface morphology were encountered. All the films are highly transparent in the near UV-vis range, with an average transmittance oscillating between 83% and 90%.

  1. Enhancing the electrochemical oxidation of acid-yellow 36 azo dye using boron-doped diamond electrodes by addition of ferrous ion

    Energy Technology Data Exchange (ETDEWEB)

    Villanueva-Rodriguez, M.; Hernandez-Ramirez, A. [Universidad Autonoma de Nuevo Leon, Facultad de Ciencias Quimicas, Av. Universidad s/n, Cd. Universitaria, San Nicolas de los Garza, NL. 66400 (Mexico); Peralta-Hernandez, J.M., E-mail: jperalta@fcq.uanl.mx [Universidad Autonoma de Nuevo Leon, Facultad de Ciencias Quimicas, Av. Universidad s/n, Cd. Universitaria, San Nicolas de los Garza, NL. 66400 (Mexico); Bandala, Erick R.; Quiroz-Alfaro, Marco A. [Universidad de Las Americas - Puebla, Escuela de Ingenieria y Ciencias, Sta. Catarina Martir - Cholula, Puebla 72820 (Mexico)

    2009-08-15

    This work shows preliminary results on the electrochemical oxidation process (EOP) using boron-doped diamond (BDD) electrode for acidic yellow 36 oxidation, a common azo dye used in textile industry. The study is centred in the synergetic effect of ferrous ions and hydroxyl free radicals for improving discoloration of azo dye. The assays were carried out in a typical glass cell under potentiostatic conditions. On experimental conditions, the EOP was able to partially remove the dye from the reaction mixture. The reaction rate increased significantly by addition of Fe{sup 2+} (1 mM as ferrous sulphate) to the system and by (assumed) generation of ferrate ion [Fe(VI)] over BDD electrode. Ferrate is considered as a highly oxidizing reagent capable of removing the colorant from the reaction mixture, in synergistic action with the hydroxyl radicals produced on the BDD surface. Further increases in the Fe{sup 2+} concentration lead to depletion of the reaction rate probably due to the hydroxyl radical scavenging effect of Fe{sup 2+} excess in the system.

  2. Minimizing Unintentional Strain and Doping of Single-Layer Graphene on SiO2 in Aqueous Environments by Acid Treatments.

    Science.gov (United States)

    Masuda, Katsuya; Sano, Masahito

    2015-05-05

    The effects of treating SiO2/Si with either acidic or alkaline solutions on single-layer graphene were investigated using Raman microscopy. It is well-known that in air graphene on SiO2 is unintentionally strained and hole-doped to different degrees, varying widely by sample. It is also known that various amine compounds act as electron donors to graphitic materials. In this study, a SiO2/Si substrate was simply dipped in either a concentrated HCl solution or pH 9.0 NaOH solution and then rinsed, prior to transferring graphene on it. The G and 2D peaks were followed at a fixed position on a single-layer graphene flake in water and various concentrations of pH 7.4 tris(hydroxymethyl)aminomethane (Tris) buffer. The results demonstrate that these treatments reduce the sample variation, improve the stability against Tris, and even bring some graphene samples close to a freestanding state. The Raman analysis reveals that the main effect of dipping is to relieve strain. The undoping effect on some samples is explained by the HCl solution becoming trapped between the graphene and SiO2 surface.

  3. Folic acid-conjugated TiO2-doped mesoporous carbonaceous nanocomposites loaded with Mitoxantrone HCl for chemo-photodynamic therapy.

    Science.gov (United States)

    Li, Zhi; Ou-Yang, Ya; Liu, Yang; Wang, Yi-Qiu; Zhu, Xia-Li; Zhang, Zhen-Zhong

    2015-06-01

    Recently, porous carbons have showed great potential in many areas. In this study, TiO2-doped mesoporous carbonaceous (TiO2@C) nanoparticles were obtained by a simple one-pot hydrothermal treatment, folic acid (FA) was conjugated to TiO2@C through an amide bond, then Mitoxantrone HCl (MTX) was adsorbed onto TiO2@C-FA and a drug delivery system, TiO2@C-FA/MTX was obtained. TiO2@C-FA/MTX showed a much faster MTX release at pH 4.5 than at pH 6.0 and pH 7.4. Furthermore, compared with free MTX, this drug delivery system showed a dose-dependent cytotoxicity by varying the irradiance, and afforded higher antitumor efficacy in cultured PC3 cells in vitro. The ability of TiO2@C-FA/MTX to combine chemotherapy with photodynamic activity enhanced the cancer cell killing effect in vitro, demonstrating that TiO2@C-FA/MTX has a great potential for cancer therapy in the future.

  4. Photocatalytic degradation of humic acids using substrate-supported Fe³⁺-doped TiO₂ nanotubes under UV/O₃ for water purification.

    Science.gov (United States)

    Yuan, Rongfang; Zhou, Beihai; Zhang, Xuemin; Guan, Huanhuan

    2015-11-01

    In this paper, Fe(3+)-doped TiO2 nanotubes (Fe-TNTs) were successfully synthesized using hydrothermal method. Four different types of substrates, more specifically, ceramsite, zeolite, activated alumina, and activated carbon (AC), have been investigated in the study. The substrate-supported Fe-TNTs were used to effectively decompose humic acids (HAs) in water under O3/UV conditions. The experiment results show that the highest photocatalytic activity was obtained in the presence of AC-supported 1.0 atomic percent (at.%) Fe-TNTs calcined at 500 °C, as HAs was removed by 97.4%, with a pseudo-first-order rate constant of 0.126/min. The removal efficiencies of HAs reduced when the catalysts was repeatedly used, since the amount of adsorption sites of the supporting substrates decreased. However, even after the catalyst was repeatedly used for five times, the removal efficiency of HAs in the presence of AC-supported catalyst, which was 78.5%, was still sufficient in water treatment. The enhanced photocatalytic activity of AC-supported Fe-TNTs was related to a synergistic effect of AC adsorption and Fe-TNT photocatalytic ozonation.

  5. An investigation of proton conductivity of binary matrices sulfonated polysulfone/polyvinyltriazole after doping with inorganic acids

    Indian Academy of Sciences (India)

    Serkan Sevinç; Sevim Ünügür Çelik; Ayhan Bozkurt

    2015-04-01

    As anhydrous proton conductive membranes, sulfonated polysulfone (SPSU) and polyvinyl triazole were studied as binary matrices. The sulfonation of polysulfone was performed with trimethylsilylchlorosulfonate and high degree of sulfonation (140%) was obtained. Ion exchange capacity of SPSU was determined as 3.05 mmol−1/g. The polymer electrolyte membranes were prepared by blending of sulfonated polysulfone with polyvinyl triazole and phosphoric acid. Fourier transform infrared spectroscopy confirmed the sulfonation of the polysulfone and the ionic interaction between sulfonic acid and triazole units. Thermogravimetric analysis showed that the polymer electrolyte membranes are thermally stable up to at least 150° C. Scanning electron microscopy analysis indicated the homogeneity of the ternary composites. The maximum proton conductivity has been measured as 3.63 × 10−4S cm−1 at 150° C.

  6. p-toluene sulfonic acid doped polyaniline carbon nanotube composites: synthesis via different routes and modified properties

    OpenAIRE

    Sharma, Ashok K.; YASHPAL SHARMA

    2013-01-01

    Composites of polyaniline and carbon nanotube (CNT) were prepared by in-situ chemical polymerization method using various aniline concentrations in the initial polymerization solution with p-toluene sulfonic acid (PTS) as secondary dopant and mechanical mixing of the PANI and CNT using different weight ratios of PANI and CNTs. The structural characterizations of the composites were done by Fourier transform infrared (FTIR) and Ultra violet visible spectroscopy (UV-Visible). Scanning electron ...

  7. Multifunctional electroactive electrospun nanofiber structures from water solution blends of PVA/ODA-MMT and poly(maleic acid-alt-acrylic acid): effects of Ag, organoclay, structural rearrangement and NaOH doping factors

    Science.gov (United States)

    Şimşek, Murat; Rzayev, Zakir M. O.; Bunyatova, Ulviya

    2016-06-01

    Novel multifunctional colloidal polymer nanofiber electrolytes were fabricated by green reactive electrospinning nanotechnology from various water solution/dispersed blends of poly (vinyl alcohol-co-vinyl acetate) (PVA)/octadecyl amine-montmorillonite (ODA-MMT) as matrix polymer nanocomposite and poly(maleic acid-alt-acrylic acid) (poly(MAc-alt-AA) and/or its Ag-carrying complex as partner copolymers. Polymer nanofiber electrolytes were characterized using FTIR, XRD, thermal (DSC, TGA-DTG), SEM, and electrical analysis methods. Effects of partner copolymers, organoclay, in situ generated silver nanoparticles (AgNPs), and annealing procedure on physical and chemical properties of polymer composite nanofibers were investigated. The electrical properties (resistance, conductivity, activation energy) of nanofibers with/without NaOH doping agent were also evaluated. This work presented a structural rearrangement of nanofiber mats by annealing via decarboxylation of anhydride units with the formation of new conjugated double bond sites onto partner copolymer main chains. It was also found that the semiconductor behaviors of nanofiber structures were essentially improved with increasing temperature and fraction of partner copolymers as well as presence of organoclay and AgNPs in nanofiber composite.

  8. Structural, electronic and photoluminescence properties of Eu3+-doped CaYAlO4 obtained by using citric acid complexes as precursors

    Science.gov (United States)

    Perrella, R. V.; Júnior, C. S. Nascimento; Góes, M. S.; Pecoraro, E.; Schiavon, M. A.; Paiva-Santos, C. O.; Lima, H.; Couto dos Santos, M. A.; Ribeiro, S. J. L.; Ferrari, J. L.

    2016-07-01

    The search for new materials that meet the current technological demands for photonic applications, make the Rare Earth ions embedded in inorganic oxides as excellent candidates for several technological devices. This work presents the synthesis of Eu3+-doped CaYAlO4 using citric acid as ligand to form a complex precursor. The methodology used has big draw due to its easy handling and low cost of the materials. The thermal analysis of viscous solutions was evaluated and the obtained compounds show the formation of a polycrystalline tetragonal phase. Rietveld refinement was used to understand the structural and the cell parameters of the crystalline phase as a function of temperature of heat-treatment. Crystallite size and microstrain were determined and were shown to have a direct relationship with the temperature of the heat-treatment. The band-gap of the CaYAlO4 doped with 1 and 10 mol% of Eu3+ showed values close to 4.30 eV, resulting in their transparency in the visible region between 330 and 750 nm. Besides the intense photoluminescence from Eu3+, a study was conducted to evaluate the possible position of the Eu3+ in the CaYAlO4 as host lattice. Lifetime of the emission decay from Eu3+ excited state 5D0 show that CaYAlO4 is a good host to rare earth ions, once it can avoid clustering of these ions in concentration as high as 10 mol%. The predictions of the sublevels of the 7F1 crystal field level are discussed through the method of equivalent nearest neighbours (MENN). The intensity parameters (Ωλ, λ = 2 and 4) are reproduced with physically reasonable values of average polarizabilities. The set of charge factors used in both calculations are in good agreement with the charge of the europium ion described by the Batista-Longo improved model (BLIM). The quantum efficiencies of the materials were calculated based on Judd-Ofelt theory. Based on the results obtained in this work, the materials have potential use in photonic devices such as lasers and solid

  9. Boron doping a semiconductor particle

    Science.gov (United States)

    Stevens, Gary Don; Reynolds, Jeffrey Scott; Brown, Louanne Kay

    1998-06-09

    A method (10,30) of boron doping a semiconductor particle using boric acid to obtain a p-type doped particle. Either silicon spheres or silicon powder is mixed with a diluted solution of boric acid having a predetermined concentration. The spheres are dried (16), with the boron film then being driven (18) into the sphere. A melt procedure mixes the driven boron uniformly throughout the sphere. In the case of silicon powder, the powder is metered out (38) into piles and melted/fused (40) with an optical furnace. Both processes obtain a p-type doped silicon sphere with desired resistivity. Boric acid is not a restricted chemical, is inexpensive, and does not pose any special shipping, handling, or disposal requirements.

  10. Influence of surfactant on dynamics of photoinduced motions and light emission of a dye-doped deoxyribonucleic acid

    Science.gov (United States)

    Sznitko, Lech; Parafiniuk, Kacper; Miniewicz, Andrzej; Rau, Ileana; Kajzar, Francois; Niziol, Jacek; Hebda, Edyta; Pielichowski, Jan; Sahraoui, Bouchta; Mysliwiec, Jaroslaw

    2013-10-01

    Pure deoxyribonucleic acid (DNA) is known to be soluble in water only and exhibits poor temperature stability. In contrary, it is well known that the complex of DNA - with cetyltrimethyl ammonium (CTMA) is insoluble in water but soluble in alcohols and can be processed into very good optical quality thin films by solution casting or spin deposition. Despite the success of DNA-CTMA, there is still need for new cationic surfactants which would extend the range of available solvents for DNA complex. We test and present experimental results of influence of new surfactants replacing CTMA in the DNA complex and based on benzalkonium chloride (BA) and didecyldimethylammonium chloride (DDCA) on their optical properties. Particularly, we were interested in all optical switching and light generation in amplified spontaneous emission process in these materials.

  11. The effect of doping acid on the third-order nonlinearity of carboxymethyl cellulose by the Z-scan technique

    Science.gov (United States)

    Jafari, A.; Naderali, R.; Motiei, H.

    2017-02-01

    The studies on the third-order nonlinear optical properties of carboxymethyl cellulose nanocomposite in the absence and presence of inorganic acid as a dopant was reported. The Z-scan technique was used to measure the nonlinear refraction n2, and absorption β, indexes and the third-order nonlinear susceptibility χ3. Characterization of this nanocomposite was performed by using scanning electron microscopy and Ultraviolet-Visible absorption spectroscopy in two different solvents; Dimethylformamide and N-Methylpyrrolidone. Additionally X-ray diffraction was used to study their crystal structure. The measured values of the nonlinear refraction of each sample in both of the solutions were in the order of 10-9m2/w and the corresponding third-order nonlinear susceptibilities were in the order 10-4 esu.

  12. Enhanced catalytic activity of gold nanoparticles doped in a mesoporous organic gel based on polymeric phloroglucinol carboxylic acid-formaldehyde.

    Science.gov (United States)

    Yang, Han; Nagai, Keiji; Abe, Toshiyuki; Homma, Hirofumi; Norimatsu, Takayoshi; Ramaraj, Ramasamy

    2009-09-01

    Gold nanoparticles were supported by a phloroglucinolcarboxylic acid-formaldehyde (PF) gel, a new organic gel with a 30 nm spheroid-like structure. The surface area of the PF gel with gold nanoparticles was 550 m(2)/g. Gold nanoparticles supported on a PF gel exhibited catalytic activity in the reduction of 4-nitrophenol with a reaction rate constant of 7.4 x 10(-3) s(-1), which is high in the reported heterogeneous reaction system. The adsorption behavior of 4-nitrophenol into the gel support was observed by ultraviolet-visible absorption spectroscopy. Gold nanoparticles in the PF network were characterized by scanning electron microscopy, atomic force microscopy, and transmission electron microscopy observation. The high reduction rate would be attributed to the extraction and diffusion of the reactant through the pores of a PF gel support to encounter the highly dispersed gold nanoparticles on the surface and inside the material.

  13. p-toluene sulfonic acid doped polyaniline carbon nanotube composites: synthesis via different routes and modified properties

    Directory of Open Access Journals (Sweden)

    ASHOK K. SHARMA

    2013-04-01

    Full Text Available Composites of polyaniline and carbon nanotube (CNT were prepared by in-situ chemical polymerization method using various aniline concentrations in the initial polymerization solution with p-toluene sulfonic acid (PTS as secondary dopant and mechanical mixing of the PANI and CNT using different weight ratios of PANI and CNTs. The structural characterizations of the composites were done by Fourier transform infrared (FTIR and Ultra violet visible spectroscopy (UV-Visible. Scanning electron microscopy (SEM was used to characterize the surface morphology of the composites. It was found that the composites prepared by in-situ chemical polymerization had smoother surface morphology in comparison to the composites obtained by mechanical mixing. The capacitive studies reveal that the in-situ composite has synergistic effect and the specific capacitance of the composite calculated from cyclic voltammogram (CV was 385.1 F/g. Thermal studies indicate that the composites are stable as compared to PANI alone showing that the CNT contributes towards thermal stability in the PANI-CNT composites.

  14. Study of polyaniline doped with trifluoromethane sulfonic acid in gas-diffusion electrodes for proton-exchange membrane fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Gharibi, Hussein; Zhiani, Mohammad; Kheirmand, Mehdi; Kakaei, Karim [Department of Physical Chemistry, Faculty of Science, Tarbiat Modarres University, P.O. Box 14115-175, Tehran (Iran); Entezami, Ali Akbar [Faculty of Chemistry, Tabriz University, Tabriz (Iran); Mirzaie, Rasol Abdullah [Department of Chemistry, Faculty of Science, Shahid Rajaee University, Tehran (Iran)

    2006-04-21

    Polytetrafluoroethylene (PTFE)-bonded gas-diffusion electrodes (GDEs), modified with polyaniline as an electron and proton conductor in the catalyst layer, are prepared and evaluated for use in proton-exchange membrane fuel cells (PEMFCs). Polyaniline is coated on the GDE by electropolymerization of aniline and trifluoromethane sulfonic acid as the proton-conductive monomer. The electrodes are characterized by cyclic voltammetry, current-potential measurements, electrochemical impedance spectroscopy, and chronoamperometry. The polyaniline is found to be homogenously dispersed in the catalyst layer, making it a good candidate proton and electron conductor. Use of polyaniline instead of Nafion in the catalyst layer, increases the utility of the electrocatalyst by 18%. The results are consistent with the presence of polyaniline as a conductive polymer in the reaction layer reducing the polarization resistance of the electrode in comparison with that of a corresponding electrode containing Nafion. Thus, the present results indicate that PEMFCs using polyaniline-containing electrocatalysts should give superior performance to those using catalysts containing traditional ionomers. (author)

  15. Enhanced performance of Zn(II)-doped lead-acid batteries with electrochemical active carbon in negative mass

    Science.gov (United States)

    Xiang, Jiayuan; Hu, Chen; Chen, Liying; Zhang, Dong; Ding, Ping; Chen, Dong; Liu, Hao; Chen, Jian; Wu, Xianzhang; Lai, Xiaokang

    2016-10-01

    The effect and mechanism of Zn(II) on improving the performances of lead-acid cell with electrochemical active carbon (EAC) in negative mass is investigated. The hydrogen evolution of the cell is significantly reduced due to the deposition of Zn on carbon surface and the increased porosity of negative mass. Zn(II) additives can also improve the low-temperature and high-rate capacities of the cell with EAC in negative mass, which ascribes to the formation of Zn on lead and carbon surface that constructs a conductive bridge among the active mass. Under the co-contribution of EAC and Zn(II), the partial-state-of-charge cycle life is greatly prolonged. EAC optimizes the NAM structure and porosity to enhance the charge acceptance and retard the lead sulfate accumulation. Zn(II) additive reduces the hydrogen evolution during charge process and improves the electric conductivity of the negative electrode. The cell with 0.6 wt% EAC and 0.006 wt% ZnO in negative mass exhibits 90% reversible capacity of the initial capacity after 2100 cycles. In contrast, the cell with 0.6 wt% EAC exhibits 84% reversible capacity after 2100 cycles and the control cell with no EAC and Zn(II) exhibits less than 80% reversible capacity after 1350 cycles.

  16. Mn-doped ZnS quantum dot imbedded two-fragment imprinting silica for enhanced room temperature phosphorescence probing of domoic acid.

    Science.gov (United States)

    Dan, Li; Wang, He-Fang

    2013-05-21

    A novel strategy was presented to construct the enhanced molecularly imprinted polymer (MIP)-based room temperature phosphorescence (RTP) probe by combining the RTP of Mn-doped ZnS quantum dots (Mn-ZnS QDs) and two-fragment imprinting. Two fragments or structurally similar parts of the target analytes were used as the dummy templates. Polyethyleneimine capped Mn-ZnS (PEI-Mn-ZnS) QDs, offering the binding sites to interact with the carboxyl groups of templates, were imbedded into MIPs by the hydrolysis of tetraethoxysilane. The rebinding of the target analytes to their fragments' cavities (recognition sites) modulated the selective aggregation of Mn-ZnS QDs in QDs-MIPs and resulted in the RTP enhancement. This new method was suitable for the selective enhanced RTP detection of nonphosphorescent analytes without any derivatization and inducers. The proposed methodology was applied to construct the high selective enhanced MIP-based RTP probe for domoic acid (DA) detection. The RTP enhancement of two-fragment imprinting silica was about 2 times of one-fragment imprinting silica and 4 times of the nonimprinting silica. The two-fragment imprinting silica exhibited the linear RTP enhancement to DA in the range of 0.25-3.5 μM in buffer and 0.25-1.5 μM in shellfish sample. The precision for 11 replicate detections of 1.25 μM DA was 0.65% (RSD), and the limit of detection was 67 nM in buffer and 2.0 μg g(-1) wet weight (w/w) in shellfish sample.

  17. Electrochemical Performance of a Carbon Nanotube/La-Doped TiO2 Nanocomposite and its Use for Preparation of an Electrochemical Nicotinic Acid Sensor

    Directory of Open Access Journals (Sweden)

    Hanxing Liu

    2008-11-01

    Full Text Available A carbon nanotube/La-doped TiO2 (La-TiO2 nanocomposite (CLTN was prepared by a procedure similar to a complex/adsorption process. Scanning electron microscopy (SEM images show that the La-TiO2 distributes on the carbon nanotube walls. The CLTN was mixed with paraffin to form a CLTN paste for the CLTN paste electrode (CLTNPE. The electrochemical characteristics of CLTNPE were compared with that of conventional carbon electrodes such as the carbon paste electrode (CPE and glass carbon electrode (GC. The CLTNPE exhibits electrochemical activity and was used to investigate the electrochemistry of nicotinic acid (NA. The modified electrode has a strong electrocatalytic effect on the redox of NA. The cyclic voltammetry (CV redox potential of NA at the CLTNPE is 320 mV. The oxidation process of NA on the CLTNPE is pH dependent. A sensitive chronoamperometric response for NA was obtained covering a linear range from 1.0×10-6 mol·L-1 to 1.2×10-4 mol·L-1, with a detection limit of 2.7×10-7 mol·L-1. The NA sensor displays a remarkable sensitivity and stability. The mean recovery of NA in the human urine is 101.8%, with a mean variation coefficient (RSD of 2.6%.

  18. Gypsum (CaSO4·2H2O Scaling on Polybenzimidazole and Cellulose Acetate Hollow Fiber Membranes under Forward Osmosis

    Directory of Open Access Journals (Sweden)

    Tai-Shung Chung

    2013-11-01

    Full Text Available We have examined the gypsum (CaSO4·2H2O scaling phenomena on membranes with different physicochemical properties in forward osmosis (FO processes. Three hollow fiber membranes made of (1 cellulose acetate (CA, (2 polybenzimidazole (PBI/polyethersulfone (PES and (3 PBI-polyhedral oligomeric silsesquioxane (POSS/polyacrylonitrile (PAN were studied. For the first time in FO processes, we have found that surface ionic interactions dominate gypsum scaling on the membrane surface. A 70% flux reduction was observed on negatively charged CA and PBI membrane surfaces, due to strong attractive forces. The PBI membrane surface also showed a slightly positive charge at a low pH value of 3 and exhibited a 30% flux reduction. The atomic force microscopy (AFM force measurements confirmed a strong repulsive force between gypsum and PBI at a pH value of 3. The newly developed PBI-POSS/PAN membrane had ridge morphology and a contact angle of 51.42° ± 14.85° after the addition of hydrophilic POSS nanoparticles and 3 min thermal treatment at 95 °C. Minimal scaling and an only 1.3% flux reduction were observed at a pH value of 3. Such a ridge structure may reduce scaling by not providing a locally flat surface to the crystallite at a pH value of 3; thus, gypsum would be easily washed away from the surface.

  19. Method of operating a direct dme fuel cell system

    DEFF Research Database (Denmark)

    2011-01-01

    The present invention relates to a method of operating a fuel cell system comprising one or more fuel cells with a proton exchange membrane, wherein the membrane is composed of a polymeric material comprising acid-doped polybenzimidazole (PBI). The method comprises adjusting the operating...

  20. 掺氮石墨烯的溶剂热制备及对抗坏血酸氧化的电催化性能%Hydrothermal synthesis of amino-doped graphene and its electrochemical behavior on ascorbic acid

    Institute of Scientific and Technical Information of China (English)

    康辉; 罗民; 梁斌; 窦元运; 梁森; 丁肖怡

    2013-01-01

    以 Hummers 方法制备的氧化石墨烯为前驱体,在乙二胺和水的混合溶剂热条件下(150℃,8h)合成了掺氮石墨烯(NG)。通过 XRD、FT-IR、XPS 和电化学阻抗谱研究了掺氮石墨烯的结构和电化学性能。结果表明,通过溶剂热反应在石墨烯表面引入C-N,N-H 等含氮基团。乙二胺不仅能对氧化石墨烯进行部分还原,而且还能对其进行掺氮功能修饰。电化学阻抗谱研究表明,掺氮石墨烯(NG)的电子转移阻抗明显小于相同条件下水热还原制备的石墨烯,说明功能修饰石墨烯大大改善了电子转移速率。将掺氮石墨烯修饰电极应用于对抗坏血酸的电化学检测,检出限达1.0×10-5~2.8×10-2 mol/L,最低检测限(3σ/slope)为1.7×10-7 mol/L。%N-doped graphene was synthesized by on-pot hydrothermal process in the mixed solution using ethyl-enediamine and graphene oxide (GO)as precursors.X-ray diffraction (XRD),Fourier transform infrared (FT-IR)spectra,X-ray photoelectron spectroscopy (XPS)and electrochemical impedance spectroscopy (EIS)were utilized to characterize structure and electrochemical behavior of the as synthesized N-doped graphene.The or-ganic amine is not only as reductant to remove the oxygen-containing groups (OCGs)in the graphene oxide,but also as nitrogen sources to obtained the N-doped graphene.The EIS revealed the electron transfer impedance of the N-doped graphene was obviously lower than graphene,indicating that the introduction of nitrogen-contai-ning groups remarkably improve the electrical conductivity.The obtained N-doped graphene was also applied to electrochemical determination of ascorbic acid.The detection limit was found to be 1.7 × 10-7 mol/L.This demonstrated the material was of excellent electrocatalytic property.

  1. The effect of erbium-doped: yttrium, aluminium and garnet laser irradiation on the surface microstructure and roughness of double acid-etched implants

    OpenAIRE

    2011-01-01

    Purpose One of the most frequent complications related to dental implants is peri-implantitis, and the characteristics of implant surfaces are closely related to the progression and resolution of inflammation. Therefore, a technical modality that can effectively detoxify the implant surface without modification to the surface is needed. The purpose of this study was to evaluate the effect of erbium-doped: yttrium, aluminium and garnet (Er:YAG) laser irradiation on the microstructural changes ...

  2. Niobium (V) doped bioceramics: evaluation of the hydrothermal route modified with citric acid and urea to obtain modified hydroxyapatite; Bioceramicas aditivadas com niobio (V): avaliacao da rota hidrotermica modificada com acido citrico e ureia para obtencao de hidroxiapatitas modificadas

    Energy Technology Data Exchange (ETDEWEB)

    Simomukay, E.; Souza, E.C.F. de; Antunes, S.R.M.; Borges, C.P.F.; Michel, M.D.; Antunes, A.C. [Universidade Estadual de Ponta Grossa (UEPG), Ponta Grossa, PR (Brazil)

    2016-01-15

    Synthetic hydroxyapatite (Ca{sub 10}(PO{sub 4}){sub 6}(OH){sub 2}; HA) has become a widely used ceramic material for bone reconstruction due to its biocompatibility with the bone tissue. This biocompatibility as well as other physical and chemical properties of the hydroxyapatite can be modified by the addition of different ions to its structure. Niobium (V) ion has not been commonly used in the hydroxyapatite synthesis. The objective of this study was to evaluate the use of hydrothermal route in the niobium (V) doped hydroxyapatite synthesis. The route used the niobium ammonium oxalate (NH{sub 4}H{sub 2}[NbO(C{sub 2}O{sub 4}){sub 3}].3H{sub 2}O) complex as a niobium (V) ion precursor. The addition of citric acid and urea in the hydrothermal route is used for the control of synthesis pH and precipitation rate. Pure sample and sample added with 5.3 ppm of niobium (V) ion were prepared. The coexistence of other phases besides the hydroxyapatite was not observed in any of the samples through the use of X-ray diffraction and infrared spectroscopy (FTIR) techniques. The FTIR technique revealed the presence of hydroxyapatite characteristic functional groups. The scanning electron microscopy analysis showed the formation of agglomerates composed of round particles, confirmed by the transmission electron microscopy technique. The X-ray fluorescence spectroscopic analysis detected the presence of niobium in the doped sample. The results showed that niobium (V) doped hydroxyapatite can be synthesized by means of hydrothermal route, which may be considered as huge potential for future application in bioceramics. (author)

  3. Synthesis and characterization of Sn doped TiO{sub 2} photocatalysts: Effect of Sn concentration on the textural properties and on the photocatalytic degradation of 2,4-dichlorophenoxyacetic acid

    Energy Technology Data Exchange (ETDEWEB)

    Rangel-Vázquez, I.; Del Angel, G.; Bertin, V. [Departamento de Química, Universidad Autónoma Metropolitana-Iztapalapa, Av. San Rafael, Atlixco No 1865, México 09340 D.F. (Mexico); González, F. [Departamento de Ingeniería de Procesos e Hidráulica, Universidad Autónoma Metropolitana-Iztapalapa, Av. San Rafael, Atlixco No 1865, México 09340 D.F. (Mexico); Vázquez-Zavala, A.; Arrieta, A. [Departamento de Química, Universidad Autónoma Metropolitana-Iztapalapa, Av. San Rafael, Atlixco No 1865, México 09340 D.F. (Mexico); Padilla, J.M. [Universidad Tecnológica del Centro de Veracruz, Área de Tecnología, Av. Universidad Carretera Federal Cuitláhuac-La Tinaja No. 350, Cuitláhuac, Veracruz 94910 (Mexico); Barrera, A. [Universidad de Guadalajara, Centro Universitario de la Ciénega, Av. Universidad, Número 1115, Col. Linda Vista, Apdo. Postal 106, Ocotlán Jal. (Mexico); Ramos-Ramirez, E. [Departamento de Química, División de Ciencias Naturales y Exactas, Campus Guanajuato de la Universidad de Guanajuato Noria Alta S/N, Col. Noria Alta, Guanajuato, Gto. C.P. 36050 (Mexico)

    2015-09-15

    Abstract: TiO{sub 2} and Sn-doped TiO{sub 2} materials were prepared by sol–gel method using titanium and tin alkoxides at different Sn concentration (0.1 mol%, 0.5 mol%, 1 mol%, 3 mol% and 5 mol%). Samples were characterized by thermo gravimetric analyzer with differential scanning calorimeter (TGA–DSC), X-ray Rietveld refinement, N{sub 2} adsorption (BET), transmission electron microscopy (TEM), UV–vis spectroscopies technology and Raman spectroscopy. Only anatase phase was observed in pure TiO{sub 2}, whereas anatase and brookite were obtained in Sn-doped TiO{sub 2} samples. Sn dopant acts as a promoter in phase transformation of TiO{sub 2}. The Rietveld refinements method was used to determine the relative weight of anatase and brookite, and crystallite size as a function of Sn concentration after calcination of samples at 673 K. It was also demonstrated the incorporation of Sn{sup 4+} into the anatase TiO{sub 2} structure. Sn{sup 4+} inhibits the growth of TiO{sub 2} crystallite size, which leads to an increase of the specific surface area of TiO{sub 2}. From XRD analysis, the solid solution limit of Sn{sup 4+} into TiO{sub 2} is 5 mol% Sn. The photocatalytic activity on Sn{sup 4+} doped TiO{sub 2} was determined for the 2,4-dichlorophenoxyacetic acid reaction. The maximum in activity was attributed to the coexistence of anatase and brookite phases in the appropriate ratio and crystallite size.

  4. Effects of Zn/citric acid mole fraction on the structure and luminescence properties of the un-doped and 1.5% Pb{sup 2+} doped ZnAl{sub 2}O{sub 4} powders synthesized by citrate sol–gel method

    Energy Technology Data Exchange (ETDEWEB)

    Motloung, S.V., E-mail: motloungsv@qwa.ufs.ac.za [Department of Physics, University of the Free State (Qwaqwa Campus), Private Bag X13, Phuthaditjhaba 9866 (South Africa); Dejene, F.B. [Department of Physics, University of the Free State (Qwaqwa Campus), Private Bag X13, Phuthaditjhaba 9866 (South Africa); Swart, H.C.; Ntwaeaborwa, O.M. [Department of Physics, University of the Free State, P.O. Box 339, Bloemfontein 9300 (South Africa)

    2015-07-15

    Un-doped and 1.5% Pb{sup 2+}doped zinc aluminate (ZnAl{sub 2}O{sub 4}) was successfully prepared at a relatively low temperature (~80 °C) using the sol–gel process. The Zn/citric acid (CA) mole fraction was varied from 0.083 to 1.3. The X-ray diffraction (XRD) data revealed that most of the annealed samples consist of the cubic ZnAl{sub 2}O{sub 4} structure with ZnO impurities. The surface morphology of the phosphors was influenced by the Zn/CA mole fractions. The increase in the CA content lead to the morphological evolution and transformation from small particles to rods-like-needles. The nanopowder samples exhibited violet luminescence that varied from 400 to 410 nm, which suggested that the CA content affected the bandgap energy of the host. The results suggest that the emission originated either from the host, Pb{sup 2+} or ZnO impurities. Emission at 400 nm is attributed to the oxygen vacancies (V{sub 0}{sup *}) in the host and emission peak at 410 nm is attributed to the intrinsic defects emission of ZnO, while the emission at 552 nm is attributed to the second order emission of the excitation wavelength. The emission intensity was influenced by the Zn/CA mole fractions. The CIE colour coordinates of all samples are close to each other in the blue region. Two distinct peaks were observed at around 160 and 385 °C in thermo luminescence (TL) glow curve, which indicates that there are two set of traps. - Highlights: • Un-doped and 1.5% Pb{sup 2+}doped zinc aluminate (ZnAl{sub 2}O{sub 4}) was successfully prepared at a relatively low temperature (~80 °C) using the sol–gel process. • The increase in the catalyst content lead to the morphological evolution from small particles to rods-like-needles. • The catalyst content affected the band gap energy of the host. • Results showed that the emission can only arise from the host and ZnO impurities. • CIE colour coordinates of all samples is situated in the blue region of the chart.

  5. Gene doping : an overview and current implications for athletes

    NARCIS (Netherlands)

    van der Gronde, Toon; de Hon, Olivier; Haisma, Hidde J.; Pieters, Toine

    2013-01-01

    The possibility of gene doping, defined as the transfer of nucleic acid sequences and/or the use of normal or genetically modified cells to enhance sport performance, is a real concern in sports medicine. The abuse of knowledge and techniques gained in the area of gene therapy is a form of doping, a

  6. Structure of doped polyaniline - dielectric spectroscopy measurements

    OpenAIRE

    Diaz Calleja, R.; Matveeva, E.

    1993-01-01

    The role of doping reagents (residual water and acid anions) in determining the electric properties of a chemically synthesized polyaniline (PANI) was studied using a dielectric spectroscopy method. Dependencies of dielectric losses and susceptibility of PANI as the functions of temperature (-100 ÷ +100°C) and electric field frequency (0.3 ÷ 30000 Hz) were examined at it was shown that water acts as a doping impurity similar to acid anions. The model is proposed to explain the role of water i...

  7. Structure of doped polyaniline - dielectric spectroscopy measurements

    Energy Technology Data Exchange (ETDEWEB)

    Diaz Calleja, R. (Polytechnical Univ. of Valencia, Valencia (Spain)); Matveeva, E.S. (Polytechnical Univ. of Valencia, Valencia (Spain))

    1993-11-01

    The role of doping reagents (residual water and acid anions) in determining the electric properties of a chemically synthesized polyaniline (PANI) was studied using a dielectric spectroscopy method. Dependencies of dielectric losses and susceptibility of PANI as the functions of temperature (-100 / + 100 C) and electric field frequency (0.3 / 30000 Hz) were examined at it was shown that water acts as a doping impurity similar to acid anions. The model is proposed to explain the role of water in terms of adsorption of H[sub 2]O molecules at nitrogen cites of PANI chain and their dissociation. (orig.).

  8. One-pot environmentally friendly amino acid mediated synthesis of N-doped graphene-silver nanocomposites with an enhanced multifunctional behavior.

    Science.gov (United States)

    Khandelwal, Mahima; Kumar, Anil

    2016-03-28

    The present paper reports the one-pot synthesis of N-doped graphene-Ag nanocomposites (N-GrAg) involving the in situ generation of Ag nanoparticles (NPs). The simultaneous reduction of GO and Ag(+) to produce N-GrAg has been achieved under mild reaction conditions using an environmentally benign reducing agent, glycine, in aqueous medium without adding any external stabilizer. XRD and SAED analyses revealed the presence of Ag in the fcc structure. HRTEM analysis shows a 'd' spacing of 0.236 nm corresponding to the highest intensity (111) reflection of Ag which matches the fcc structure. The N-doping of graphene and its uniform decoration by Ag NPs (with an av. dia. of 17.5 nm) having a relatively low surface atomic % of Ag (0.309) are evidenced by TEM and XPS analyses. Raman spectroscopy has also revealed that the decoration of N-Gr with Ag NPs resulted in the enhancement of the D and G bands by about 365%. The presence of Ag in N-GrAg prevents the folding of the graphene sheet as was revealed by TEM analysis. The supramolecular interactions of Ag with different moieties of N in N-GrAg were evidenced by IR, (13)C NMR and XPS analyses, which resulted in the enhancement of its surface area and electrical conductivity as compared to that of N-Gr. The presence of Ag NPs on N-Gr increased the current response in cyclic voltammetry by more than seven fold as compared to that of N-Gr. These nanocomposites exhibited a fairly high SERS activity for 4-aminothiophenol, employed as the probe molecule, and allowed its detection at a 50 nM concentration even for the fairly small sized Ag NPs used in the present work.

  9. The Preparation and Antistatic Properties of Different Acid Doped Polyaniline Composite Polypropylene%不同酸掺杂聚苯胺复合聚丙烯的制备及抗静电性能

    Institute of Scientific and Technical Information of China (English)

    祖立武; 张晓宇; 王雅珍; 薛守成; 徐岽双

    2013-01-01

    Polymer antistatic agent polypropylene grafted styrene sulfonic acid to compounded polyaniline (PP-g-StS-PANI) was prepared by solution grafting polymerization to dodecylbenzene sulfonic acid, p-toluenesulfonic acid, acrylic acid as dopant and the polyaniline was compounded to the PP macromolecular chain by the sulfonic acid group adsorption. The polymer antistatic agent was characterized by FTIR. Influence factors of properties of polymer antistatic agent were studied. The results showed that the DBSA doped acid-prepared anti~static agent was the best. The complex efficient and antistatic effect of composite was the best when mdoped acid/mPP-g-StS=15:1,nAPS/nANI=2:1, and the volume resistivity of PP-g-StS-PANI/PP down to 1012Ω· cm. PP blend were tested by means of SEM and DSC, which showed that blends was good compatibility.%分别以十二烷基苯磺酸、对甲苯磺酸、丙烯酸为掺杂剂采用溶液聚合方法,通过磺酸基团作用将聚苯胺复合到PP大分子链上,制备了高分子永久型抗静电剂聚丙烯接枝苯乙烯磺酸复合聚苯胺(PP-g-StS-PANI).利用FTIR对高分子抗静电剂进行表征.研究了影响高分子抗静电剂制备及性能的因素.结果表明,以十二烷基苯磺酸为掺杂酸制备的抗静电剂效果最好,当m掺杂酸/mPP-g-StS=15/1,nAPs/nANI=2时,复合效率最高,抗静电效果最好,抗静电剂与PP共混物体积电阻率下降到1012Ω·cm.通过DSC分析及SEM对PP共混物界面进行分析,共混物具有良好的相容性.

  10. Synthesis and Characterization of Polyaniline Nanostubes Doped with Ethylenediaminetet Macetic Acid%乙二胺四乙酸掺杂聚苯胺纳米管的合成与性能

    Institute of Scientific and Technical Information of China (English)

    白雪莲; 李海红; 张万喜

    2011-01-01

    以乙二胺四乙酸为掺杂剂,过硫酸铵为氧化剂,采用自组装的方法合成了掺杂态的聚苯胺纳米管.通过扫描电镜(SEM),透射电镜(TEM),红外光谱(IR),X射线衍射(XRD),UV-Vis和四探针法等测试手段对产物的形貌、结构和性能进行了表征.分析了不同乙二胺四乙酸和苯胺的摩尔比对产物的形貌和导电性能的影响.结果表明,不同乙二胺四乙酸和苯胺的摩尔比对产物有一定的影响,随着摩尔比的增加,产物纳米管的直径增大;合成的聚苯胺纳米管具有一定的导电性.%Doped polyaniline (PANI) nanostructure has been prepared at room temperature using ethylenediaminetet macetic acid (EDTA) as dopant and ammonium persulfate (APS) as oxidant by a self-assembly method The morphology, structure and property of polyaniline nanostructure were characterized by scanning electron microscope (SEM), transmission electron microscope (TEM), infrared spectrum (IR), X-ray diffraction (XRD), UV-Vis and applying the 4 probes method. Effect of molar ratio of EDTA to AN on the morphology and electric conductivity was studied. It is found that the morphology and electric conductivity obtained product are affected by the different molar ratio of EDTA to AN. The diameters of polyaniline nanotubes at room-temperature increase with the increase of [EDTA]/[ AN] ratios. Doped polyaniline nanostubes possess electric conductivity.

  11. Poly(imide benzimidazole)s for high temperature polymer electrolyte membrane fuel cells

    DEFF Research Database (Denmark)

    Yuan, Sen; Guo, Xiaoxia; Aili, David

    2014-01-01

    is an order of magnitude higher than that of the common polybenzimidazole membranes with similar acid contents. A preliminary H2/air fuel cell test at 180°C showed a peak power density of 350mWcm-2 of the fuel cell equipped with the phosphoric acid doped PIBI-1/1 membrane with a 300wt% acid uptake......, demonstrating the technical feasibility of the novel electrolyte materials. © 2013 Elsevier B.V....

  12. Proton conductive membranes based on doped sulfonated polytriazole

    Energy Technology Data Exchange (ETDEWEB)

    Boaventura, M.; Brandao, L.; Mendes, A. [Laboratorio de Engenharia de Processos, Ambiente e Energia (LEPAE), Faculdade de Engenharia da Universidade do Porto, Rua Roberto Frias, 4200-465 Porto (Portugal); Ponce, M.L.; Nunes, S.P. [GKSS Research Centre Geesthacht GmbH, Max Planck Str. 1, D-21502, Geesthacht (Germany)

    2010-11-15

    This work reports the preparation and characterization of proton conducting sulfonated polytriazole membranes doped with three different agents: 1H-benzimidazole-2-sulfonic acid, benzimidazole and phosphoric acid. The modified membranes were characterized by scanning electron microscopy (SEM), infrared spectra, thermogravimetric analysis (TGA), dynamical mechanical thermal analysis (DMTA) and electrochemical impedance spectroscopy (EIS). The addition of doping agents resulted in a decrease of the glass transition temperature. For membranes doped with 85 wt.% phosphoric acid solution proton conductivity increased up to 2.10{sup -3} S cm{sup -1} at 120 C and at 5% relative humidity. The performance of the phosphoric acid doped membranes was evaluated in a fuel cell set-up at 120 C and 2.5% relative humidity. (author)

  13. Antibody-based donor-acceptor spatial reconfiguration in decorated lanthanide-doped nanoparticle colloids for the quantification of okadaic acid biotoxin.

    Science.gov (United States)

    Stipić, Filip; Burić, Petra; Jakšić, Željko; Pletikapić, Galja; Dutour Sikirić, Maja; Zgrablić, Goran; Frkanec, Leo; Lyons, Daniel M

    2015-11-01

    With the increasing movement away from the mouse bioassay for the detection of toxins in commercially harvested shellfish, there is a growing demand for the development of new and potentially field-deployable tests in its place. In this direction we report the development of a simple and sensitive nanoparticle-based luminescence technique for the detection of the marine biotoxin okadaic acid. Photoluminescent lanthanide nanoparticles were conjugated with fluorophore-labelled anti-okadaic acid antibodies which, upon binding to okadaic acid, gave rise to luminescence resonance energy transfer from the nanoparticle to the organic fluorophore dye deriving from a reduction in distance between the two. The intensity ratio of the fluorophore: nanoparticle emission peaks was found to correlate with okadaic acid concentration, and the sensor showed a linear response in the 0.37-3.97 μM okadaic acid range with a limit of detection of 0.25 μM. This work may have important implications for the development of new, cheap, and versatile biosensors for a range of biomolecules and that are sufficiently simple to be applied in the field or at point-of-care.

  14. Enhancement of CO2 Adsorption and Catalytic Properties by Fe-Doping of [Ga2(OH)2(L)] (H4L = Biphenyl-3,3',5,5'-tetracarboxylic Acid), MFM-300(Ga2).

    Science.gov (United States)

    Krap, Cristina P; Newby, Ruth; Dhakshinamoorthy, Amarajothi; García, Hermenegildo; Cebula, Izabela; Easun, Timothy L; Savage, Mathew; Eyley, Jennifer E; Gao, Shan; Blake, Alexander J; Lewis, William; Beton, Peter H; Warren, Mark R; Allan, David R; Frogley, Mark D; Tang, Chiu C; Cinque, Gianfelice; Yang, Sihai; Schröder, Martin

    2016-02-01

    Metal-organic frameworks (MOFs) are usually synthesized using a single type of metal ion, and MOFs containing mixtures of different metal ions are of great interest and represent a methodology to enhance and tune materials properties. We report the synthesis of [Ga2(OH)2(L)] (H4L = biphenyl-3,3',5,5'-tetracarboxylic acid), designated as MFM-300(Ga2), (MFM = Manchester Framework Material replacing NOTT designation), by solvothermal reaction of Ga(NO3)3 and H4L in a mixture of DMF, THF, and water containing HCl for 3 days. MFM-300(Ga2) crystallizes in the tetragonal space group I4122, a = b = 15.0174(7) Å and c = 11.9111(11) Å and is isostructural with the Al(III) analogue MFM-300(Al2) with pores decorated with -OH groups bridging Ga(III) centers. The isostructural Fe-doped material [Ga(1.87)Fe(0.13)(OH)2(L)], MFM-300(Ga(1.87)Fe(0.13)), can be prepared under similar conditions to MFM-300(Ga2) via reaction of a homogeneous mixture of Fe(NO3)3 and Ga(NO3)3 with biphenyl-3,3',5,5'-tetracarboxylic acid. An Fe(III)-based material [Fe3O(1.5)(OH)(HL)(L)(0.5)(H2O)(3.5)], MFM-310(Fe), was synthesized with Fe(NO3)3 and the same ligand via hydrothermal methods. [MFM-310(Fe)] crystallizes in the orthorhombic space group Pmn21 with a = 10.560(4) Å, b = 19.451(8) Å, and c = 11.773(5) Å and incorporates μ3-oxo-centered trinuclear iron cluster nodes connected by ligands to give a 3D nonporous framework that has a different structure to the MFM-300 series. Thus, Fe-doping can be used to monitor the effects of the heteroatom center within a parent Ga(III) framework without the requirement of synthesizing the isostructural Fe(III) analogue [Fe2(OH)2(L)], MFM-300(Fe2), which we have thus far been unable to prepare. Fe-doping of MFM-300(Ga2) affords positive effects on gas adsorption capacities, particularly for CO2 adsorption, whereby MFM-300(Ga(1.87)Fe(0.13)) shows a 49% enhancement of CO2 adsorption capacity in comparison to the homometallic parent material. We thus report

  15. Synthesis and Electrorheological Properties of p-Toluenesulfonic Acid Doped Poly(o-Toluidine)%对甲苯磺酸掺杂聚邻甲苯胺的合成及电流变性能

    Institute of Scientific and Technical Information of China (English)

    刘展鹏; 邱玉锐; 陈灵谦; 袁野; 张平

    2012-01-01

    With p-toluenesulfonic acid (TSA) as dopant and emulsifier, p-toluenesulfonic acid doped poly(o- toluidine) (TSA-POT) was synthesized by emulsion polymerization. The structure, thermal stability and morphology of the polymer were characterized by Fourier transform infrared spectrum(FT-IR), thermogravimetry (TG) and scanning electron microscope (SEM). Anhydrous electrorheological (ER) fluid of TSA-POT suspended in silicofie oil (SO) was prepared and the ER performance was measured. The ER properties based on electric field, antidoped condition and particle concentration were investigated. The results show that, the ER performances of TSA-POT are highly improved by doped with TSA to POT, which is attributed to the strong polarity of sulfonic group in the TSA connected to the conjugated chain of POT. The results also suggest that the yield stress of TSA- POT/SO ER fluid at low concentration is in line with square of electric field strength.%以对甲苯磺酸(TSA)作为掺杂剂和乳化剂,乳液聚合合成了对甲苯磺酸掺杂聚邻甲苯胺(TSA-POT)。采用红外光谱、热重分析和扫描电镜对聚合物的结构、热稳定性及形貌进行了表征。制备了TSA-POT/硅油(SO)无水型电流变流体(ER流体),测试了其电流变性能,考察了电场强度、反掺杂条件、粒子浓度等因素对TSA-POT/SO体系电流变性能的影响。结果表明,由于强极性的磺酸基团与聚邻甲苯胺的主链相连,极大地改善了聚合物粒子的极化性能,因此TSA-POT/SO体系的电流变性能显著改善。结果同时表明,低浓度的TSA-POT/SO体系的屈服应力与电场强度具有二次线性关系。

  16. Graphene doping methods and device applications.

    Science.gov (United States)

    Oh, Jong Sik; Kim, Kyong Nam; Yeom, Geun Young

    2014-02-01

    Graphene has recently been studied as a promising material to replace and enhance conventional electronic materials in various fields such as electronics, photovoltaics, sensors, etc. However, for the electronic applications of graphene prepared by various techniques such as chemical vapor deposition, chemical exfoliation, mechanical exfoliation, etc., critical limitations are found due to the defects in the graphene in addition to the absence of a semiconducting band gap. For that, many researchers have investigated the doped graphene which is effective to tailor its electronic property and chemical reactivity. This work presents a review of the various graphene doping methods and their device applications. As doping methods, direct synthesis method and post treatment method could be categorized. Because the latter case has been widely investigated and used in various electronic applications, we will focus on the post treatment method. Post treatment method could be further classified into wet and dry doping methods. In the case of wet doping, acid treatment, metal chloride, and organic material coating are the methods used to functionalize graphene by using dip-coating, spin coating, etc. Electron charge transfer achieved from graphene to dopants or from dopants to graphene makes p-type or n-type graphenes, respectively, with sheet resistance reduction effect. In the case of dry doping, it can be further categorized into electrostatic field method, evaporation method, thermal treatment method, plasma treatment method, etc. These doping techniques modify Fermi energy level of graphene and functionalize the property of graphene. Finally, some perspectives and device applications of doped graphene are also briefly discussed.

  17. Formation of indium-doped zinc oxide thin films using chemical spray techniques: The importance of acetic acid content in the aerosol solution and the substrate temperature for enhancing electrical transport

    Energy Technology Data Exchange (ETDEWEB)

    Castaneda, L. [Centro de Ciencias Aplicadas y Desarrollo Tecnologico, Universidad Nacional Autonoma de Mexico, Apartado Postal 70-186, 04510, D.F. (Mexico); Departamento de Fisica y Matematicas, Division de Estudios Disciplinares, Universidad Iberoamericana, Av. Prolongacion Paseo de la Reforma 880, Santa Fe 012100, D.F. (Mexico); Garcia-Valenzuela, A. [Centro de Ciencias Aplicadas y Desarrollo Tecnologico, Universidad Nacional Autonoma de Mexico, Apartado Postal 70-186, 04510, D.F. (Mexico); Zironi, E.P. [Instituto de Fisica, Universidad Nacional Autonoma de Mexico, Apartado Postal 20-364, 01000, D.F. (Mexico); Canetas-Ortega, J. [Instituto de Fisica, Universidad Nacional Autonoma de Mexico, Apartado Postal 20-364, 01000, D.F. (Mexico); Terrones, M. [Advanced Materials Department, IPICYT, Camino a la Presa San Jose 2055, Col. Lomas 4a. seccion, San Luis Potosi 78216 (Mexico) and Departamento de Fisica y Matematicas, Division de Estudios Disciplinares, Universidad Iberoamericana, Av. Prolongacion Paseo de la Reforma 880, Santa Fe 012100, D.F. (Mexico)]. E-mail: mterrones@ipicyt.edu.mx; Maldonado, A. [Depto. de Ing. Electrica, CINVESTAV IPN, SEES, Ap. Postal 14740, Mexico D.F. 07000 (Mexico)

    2006-05-01

    Indium-doped zinc oxide (ZnO:In) thin films were grown on glass substrates using the chemical spray technique. The effects of the acetic acid content in the starting solution (c {sub AA}), as well as the substrate temperature (T {sub S}), were studied. Our results demonstrate that when c {sub AA} is extremely low, the resistivity values of the zinc oxide (ZnO) thin films become relatively high (in the order of 4 x 10{sup -2} {omega} cm). When the c {sub AA} is increased at a fixed temperature, the resistivity of the films decreases, reaching values as low as 4 x 10{sup -3} {omega} cm for thin films deposited at 525 deg. C. The electron mobility could also increase to a maximum value of 10.5 cm{sup 2}/(V s) for films deposited at 500 deg. C. We also observed an enhancement in the electrical transport properties of the films by varying T {sub S}; the lowest resistivity values occurred in films deposited at T {sub S} between 475 and 525 deg. C. In addition, the relative intensity of the diffraction peaks associated with the crystallographic planes is strongly affected by the c {sub AA} concentration. X-ray diffraction studies reveal the polycrystalline nature of the films exhibiting a hexagonal wurtzite type, with a preferential orientation of the film depending on the acetic acid concentration. Film morphology was also affected by varying c {sub AA}, as grains with distinct geometrical shapes were observed. Finally, the optical transmittance of all these films was found to be higher than 85%.

  18. Electro-Fenton, UVA photoelectro-Fenton and solar photoelectro-Fenton degradation of the drug ibuprofen in acid aqueous medium using platinum and boron-doped diamond anodes

    Energy Technology Data Exchange (ETDEWEB)

    Skoumal, Marcel; Rodriguez, Rosa Maria; Cabot, Pere Lluis; Centellas, Francesc; Garrido, Jose Antonio; Arias, Conchita [Laboratori d' Electroquimica dels Materials i del Medi Ambient, Departament de Quimica Fisica, Facultat de Quimica, Universitat de Barcelona, Marti i Franques 1-11, 08028 Barcelona (Spain); Brillas, Enric [Laboratori d' Electroquimica dels Materials i del Medi Ambient, Departament de Quimica Fisica, Facultat de Quimica, Universitat de Barcelona, Marti i Franques 1-11, 08028 Barcelona (Spain)], E-mail: brillas@ub.edu

    2009-02-28

    The degradation of a 41 mg dm{sup -3} ibuprofen (2-(4-isobutylphenyl)propionic acid) solution of pH 3.0 has been comparatively studied by electrochemical advanced oxidation processes (EAOPs) like electro-Fenton, UVA photoelectro-Fenton and solar photoelectro-Fenton at constant current density. Experiments were performed in a one-compartment cell with a Pt or boron-doped diamond (BDD) anode and an O{sub 2}-diffusion cathode. Heterogeneous hydroxyl radical ({center_dot}OH) is generated at the anode surface from water oxidation, while homogeneous {center_dot}OH is formed from Fenton's reaction between Fe{sup 2+} and H{sub 2}O{sub 2} generated at the cathode, being its production strongly enhanced from photo-Fenton reaction induced by sunlight. Higher mineralization is attained in all methods using BDD instead Pt, because the former produces greater quantity of {center_dot}OH enhancing the oxidation of pollutants. The mineralization rate increases under UVA and solar irradiation by the rapid photodecomposition of complexes of Fe(III) with acidic intermediates. The most potent method is solar photoelectro-Fenton with BDD giving 92% mineralization due to the formation of a small proportion of highly persistent final by-products. The effect of Fe{sup 2+} content, pH and current density on photoelectro-Fenton degradation has been studied. The ibuprofen decay always follows a pseudo-first-order kinetics and its destruction rate is limited by current density and UV intensity. Aromatics such as 1-(1-hydroxyethyl)-4-isobutylbenzene, 4-isobutylacetophenone, 4-isobutylphenol and 4-ethylbenzaldehyde, and carboxylic acids such as pyruvic, acetic, formic and oxalic have been identified as oxidation by-products. Oxalic acid is the ultimate by-product and the fast photodecarboxylation of its complexes with Fe(III) under UVA or solar irradiation explains the higher oxidation power of photoelectro-Fenton methods in comparison to electro-Fenton procedures.

  19. The Anti-Doping Movement.

    Science.gov (United States)

    Willick, Stuart E; Miller, Geoffrey D; Eichner, Daniel

    2016-03-01

    Historical reports of doping in sports date as far back as the ancient Greek Olympic Games. The anti-doping community considers doping in sports to be cheating and a violation of the spirit of sport. During the past century, there has been an increasing awareness of the extent of doping in sports and the health risks of doping. In response, the anti-doping movement has endeavored to educate athletes and others about the health risks of doping and promote a level playing field. Doping control is now undertaken in most countries around the world and at most elite sports competitions. As athletes have found new ways to dope, however, the anti-doping community has endeavored to strengthen its educational and deterrence efforts. It is incumbent upon sports medicine professionals to understand the health risks of doping and all doping control processes.

  20. Polarization induced doped transistor

    Energy Technology Data Exchange (ETDEWEB)

    Xing, Huili (Grace); Jena, Debdeep; Nomoto, Kazuki; Song, Bo; Zhu, Mingda; Hu, Zongyang

    2016-06-07

    A nitride-based field effect transistor (FET) comprises a compositionally graded and polarization induced doped p-layer underlying at least one gate contact and a compositionally graded and doped n-channel underlying a source contact. The n-channel is converted from the p-layer to the n-channel by ion implantation, a buffer underlies the doped p-layer and the n-channel, and a drain underlies the buffer.

  1. Emission spectra of the sol-gel glass doped with europium(III) complexes of picolinic acid N-oxide-A new UV-light sensor

    Energy Technology Data Exchange (ETDEWEB)

    Godlewska, P. [Department of Bioorganic Chemistry, Institute of Chemistry and Food Technology, Faculty of Engineering and Economics, Lower Silesian University of Economics, Wroclaw (Poland); Macalik, L. [Institute of Low Temperature and Structure Research, Polish Academy of Sciences, Wroclaw (Poland); Hanuza, J. [Department of Bioorganic Chemistry, Institute of Chemistry and Food Technology, Faculty of Engineering and Economics, Lower Silesian University of Economics, Wroclaw (Poland); Institute of Low Temperature and Structure Research, Polish Academy of Sciences, Wroclaw (Poland)], E-mail: j.hanuza@int.pan.wroc.pl

    2008-02-28

    New europium complexes of picolinic acid N-oxides have been synthesised and introduced into sol-gel matrices. Their application as UV-light sensors has been considered. The sequence of the electronic levels for Eu{sup 3+} ions has been determined from the absorption and emission studies and assigned to the respective electron transitions. The lifetimes of the excited states have been detected and analysed. The role of the CT transition inside the picolinic ligand and its influence on the ligand to metal charge transfer (LMCT) have been discussed.

  2. The Dope Stops Here

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Beijing has been making preparations to present a dope-free Olympics next yearThe China Anti-Doping Agency,set up to replace the 17-year-old China Doping Control Center,was offi- cially unveiled in Beijing on November 12.Between July 27 next year,when the Olympic Village is opened to athletes,and August 24,the last day of the Olympic Games,a total of 4,500 doping tests will be conducted in the build- ing.This number is 25 percent higher than that of the Athens Olympic Games in 2004 and 63 percent higher than at the Sydney Olympics in 2000.

  3. Doping of Semi Conductors

    Directory of Open Access Journals (Sweden)

    V. V. Agashe

    1960-07-01

    Full Text Available Most of the semi-conductors are formed by addition of foreign substances in an insulator. This is called 'Doping'. These doped semi-conductors today are widely used in many electrical devices. Some of them are rectifiers, transistors, thermistors, oxides cathodes and photo-sensitive elements. This paper reviews the fundamental concept of impurity in semi-conductors and recent work on doping of the latter. Purification methods are described in the case of group IV elements and semi-conducting intermetallic compounds. Results of different physical measurements have been discussed in order to understand the role of 'doping'.

  4. YAlO3/Fe掺杂ZnO复合物的制备、表征及对酸性红B的降解%Synthesis and Characterization of YAlO3/Fe-doped ZnO and Its Photocatalytic Oxidation of Acid Red B

    Institute of Scientific and Technical Information of China (English)

    程春萍

    2012-01-01

    In this work,YAlO3/Fe -doped ZnO composite,a novel photocatalyst, was synthesized by ultrasonic disper-sion and liquid boiling method and characterized by X - ray diffraction ( XRD ) and scanning electron microscope ( SEM) , and its photocatalytic activities were evaluated through the degradation of acid red B under visible light irradiation. The effects of preparation conditions such as YAlO3 content, heat - treated temperature and heat - treated time on the photocatalytic activity of YAlO3/Fe - doped ZnO composite were examined. In addition,the influences of visible light irradiation time and YAlO3/Fe - doped ZnO amount as well as organic dyes on the photocatalytic degradation were also investigated by HPLC techniques. The experimental results indicated that the YAlO3/Fe - doped ZnO composite can effectively utilize visible energy to degrade acid red B and its photocatalytic activity was much superior to that of Fe - doped ZnO composite under the same condition. Results revealed that the AlO3/Fe - doped ZnO showed higher activity and the maximum conversion of acid red B could reach 97.7% within 40 min.%采用溶胶-凝胶、超声分散和溶液沸腾法制备YAlO3/Fe掺杂ZnO复合物,在可见光的照射下,考察了酸性红B降解效果,并利用x-射线衍射(XRD)和扫描电子显微镜(SEM)对光催化剂进行了表征,同时研究了YAlO3的包覆量、YAlO3/Fe掺杂ZnO的量、可见光照射时间、处理温度和处理时间等因素对酸性红B降解率的影响,其降解过程也用HPLC进一步进行验证.结果表明,YAlO3/Fe掺杂ZnO在40 min酸性红B的降解率达到97.7%,表现出更好的光催化活性.

  5. The effect of silicotungstic acid (STA) doping of TiO{sub 2} nanoparticles on the performance of TiO{sub 2}-based dye sensitized solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Li, M.; Savadogo, O. [Ecole Polytechnique de Montreal, PQ (Canada). Laboratory of New Materials for Electrochemistry and Energy

    2010-07-01

    In this study, the sol-gel method was used to prepare titanium oxide (Ti0{sub 2}) colloids with, and without silicotungstic acid (STA). The colloids were prepared by adding Ti isopropoxide into an acid glacial solution heated to 250 degrees C for 7 hours. The working electrodes and counter electrodes were prepared by depositing the TiO{sub 2} colloid into conduction glasses where they were sintered at 450 degrees C for 30 minutes. The electrodes were then dipped into a dye solution in order to form dye-sensitized solar cells (DSSCs). Variations in cell voltage and current density were investigated. Results of the study showed that DSSC performance was significantly influenced by the STA content in the TiO{sub 2}. Cell performance was influenced by the presence of tungsten oxide powder (WO{sub 3}). WO{sub 3} and silica dioxide (SiO{sub 2}) were inserted into the TiO{sub 2} matrix depending on STA concentrations. Cell performance depended on the presence of both WO{sub 3} and SiO{sub 2}. Impedance between the counter electrodes and electrolytes did not change significantly. A cell efficiency of between 1 to 10 per cent was obtained with variations in STA-TiO{sub 2} composition.

  6. Iron (III) chloride doping of CVD graphene.

    Science.gov (United States)

    Song, Yi; Fang, Wenjing; Hsu, Allen L; Kong, Jing

    2014-10-03

    Chemical doping has been shown as an effective method of reducing the sheet resistance of graphene. We present the results of our investigations into doping large area chemical vapor deposition graphene using Iron (III) Chloride (FeCl(3)). It is shown that evaporating FeCl(3) can increase the carrier concentration of monolayer graphene to greater than 10(14) cm(-2) and achieve resistances as low as 72 Ω sq(-1). We also evaluate other important properties of the doped graphene such as surface cleanliness, air stability, and solvent stability. Furthermore, we compare FeCl(3) to three other common dopants: Gold (III) Chloride (AuCl(3)), Nitric Acid (HNO(3)), and TFSA ((CF(3)SO(2))(2)NH). We show that compared to these dopants, FeCl(3) can not only achieve better sheet resistance but also has other key advantages including better solvent stability.

  7. Phosphate-Doped Carbon Black as Pt Catalyst Support: Co-catalytic Functionality for Dimethyl Ether and Methanol Electro-oxidation

    DEFF Research Database (Denmark)

    Yin, Min; Huang, Yunjie; Li, Qingfeng

    2014-01-01

    Niobium-phosphate-doped (NbP-doped) carbon blacks were prepared as the composite catalyst support for Pt nanoparticles. Functionalities of the composite include intrinsic proton conductivity, surface acidity, and interfacial synergistic interactions with methanol and dimethyl ether (DME). The sup......Niobium-phosphate-doped (NbP-doped) carbon blacks were prepared as the composite catalyst support for Pt nanoparticles. Functionalities of the composite include intrinsic proton conductivity, surface acidity, and interfacial synergistic interactions with methanol and dimethyl ether (DME...

  8. 不同磺酸掺杂聚苯胺的制备及在超级电容器中的应用%Preparation and Application of Polyaniline Doped with Different Sulfonic Acids for Supercapacitor

    Institute of Scientific and Technical Information of China (English)

    林有铖; 钟新仙; 黄寒星; 王红强; 冯崎鹏; 李庆余

    2016-01-01

    以MnO2为氧化剂,采用乳液聚合法,用三种不同的磺酸型表面活性剂制备掺杂聚苯胺(PANI)。通过扫描电子显微镜(SEM)、傅里叶变换红外(FTIR)光谱以及X射线衍射(XRD)等手段对其结构及形貌进行表征;用所得的掺杂聚苯胺制作电极,组装成对称扣式超级电容器,用循环伏安法(CV)、电化学阻抗(EIS)和恒电流充放电技术进行电化学性能研究。结果表明,磺酸表面活性剂的引入有利于PANI纳米纤维的形成和分散,掺杂Nafion的PANI纤维直径在30-40 nm之间,纤维交织成多孔的疏松结构;当放电电流为0.1 A∙g-1时,以PANI-Nafion、PANI-SDS(十二烷基磺酸钠)、PANI-SDBS(十二烷基苯磺酸钠)为电极材料的超级电容器比容量分别为385.3、359.7、401.6 F∙g-1,均高于未掺杂PANI的比容量(235.8 F∙g-1);其中,PANI-Nafion的循环稳定性最好,1000次循环后其比容量保持率高达70.7%。%Polyaniline (PANI) nanomaterials doped with three different sulfonic acid surfactants (perfluorinated sulfonic acid ion exchange resin (Nafion), sodium dodecyl sulfate (SDS), and sodium dodecyl benzene sulfonate (SDBS)) were prepared using an emulsion polymerization method with manganese dioxide (MnO2) as the oxidant. The structure and morphology of the products were studied by scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy, and X-ray diffraction (XRD). Symmetric redox supercapacitor was assembled with doped PANI as the active electrode material. The electrochemical performances of the materials were evaluated by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and galvanostatic charge-discharge tests. These results suggest that the introduction of surfactant is beneficial for the formation of a fiber structure and increases the dispersion of PANI. A PANI-Nafion network with distributed porosity and average diameters of 30-40 nm is obtained. The

  9. Molecularly doped metals.

    Science.gov (United States)

    Avnir, David

    2014-02-18

    The many millions of organic, inorganic, and bioorganic molecules represent a very rich library of chemical, biological, and physical properties that do not show up among the approximately 100 metals. The ability to imbue metals with any of these molecular properties would open up tremendous potential for the development of new materials. In addition to their traditional features and their traditional applications, metals would have new traits, which would merge their classical virtues such as conductivity and catalytic activity with the diverse properties of these molecules. In this Account, we describe a new materials methodology, which enables, for the first time, the incorporation and entrapment of small organic molecules, polymers, and biomolecules within metals. These new materials are denoted dopant@metal. The creation of dopant@metal yields new properties that are more than or different from the sum of the individual properties of the two components. So far we have developed methods for the doping of silver, copper, gold, iron, palladium, platinum, and some of their alloys, as well as Hg-Ag amalgams. We have successfully altered classical metal properties (such as conductivity), induced unorthodox properties (such as rendering a metal acidic or basic), used metals as heterogeneous matrices for homogeneous catalysts, and formed new metallic catalysts such as metals doped with organometallic complexes. In addition, we have created materials that straddle the border between polymers and metals, we have entrapped enzymes to form bioactive metals, we have induced chirality within metals, we have made corrosion-resistant iron, we formed efficient biocidal materials, and we demonstrated a new concept for batteries. We have developed a variety of methods for synthesizing dopant@metals including aqueous homogeneous and heterogeneous reductions of the metal cations, reductions in DMF, electrochemical entrapments, thermal decompositions of zerovalent metal carbonyls

  10. Photothermal ablation of cancer cells using self-doped polyaniline nanoparticles

    Science.gov (United States)

    Hong, Yoochan; Cho, Wonseok; Kim, Jeonghun; Hwng, Seungyeon; Lee, Eugene; Heo, Dan; Ku, Minhee; Suh, Jin-Suck; Yang, Jaemoon; Kim, Jung Hyun

    2016-05-01

    Water-stable confined self-doping polyaniline nanocomplexes are successfully fabricated by nano-assembly using lauric acid both as a stabilizer and as a localized dopant. In particular, the colloidal stability of the polyaniline nanocomplexes in neutral pH and the photothermal potential by near-infrared light irradiation are characterized. We demonstrate that confined self-doping polyaniline nanocomplexes as a photothermal nanoagent are preserved in the doped state even at a neutral pH. Finally, confined self-doping polyaniline nanocomplexes aided by lauric acid are successfully applied for the photothermal ablation of cancer cells.

  11. Polymer electrolyte membrane fuel cells based on Nafion and acid-doped PBI:state-of-the-art and recent progress

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Based on perfluorosulfonic acid polymer membranes (PFSA,e.g.Nafion),polymer electrolyte membrane fuel cells (PEMFC) operate with hydrogen or purified reformate gas due to the strong poisoning effect of fuel impurities.Consequently,a complicated fuel storage or fuel processing system is needed.Direct methanol fuel cells,on the other hand,suffer from slow anodic kinetics and therefore low power density.The newest technology in the field is the development of temperature-resistant polymer membranes for operation at temperatures higher than 100°C.The high temperature PEMFC exhibits performance compatible with PFSA-based PEM fuel cell but can tolerate up to 3 %(volume fraction) carbon monoxide.The high CO tolerance makes it possible to use the reformed hydrogen directly from a simple methanol reformer without further CO removal.This opens possibility for an integrated reformer-fuel cell system,which is expected to exhibit high power density and simple construction as well as efficient capital and operational cost.

  12. Doping and Public Health

    DEFF Research Database (Denmark)

    Christiansen, Ask Vest

    http://www.idrottsforum.org/features/aarhus_doping/chrask_doping2007.html INHDR - International Network for Humanistisc Doping Research, med den virtuella adressen www.doping.au.dk , höll sin andra konferens den 15-16 augusti på Aarhus Universitet, med dess Center for Idræt som värdinstitution. En...... rad av världens främsta idrottsvetare och dopningsexperter hade mött upp för att presentera papers till en intresserad och engagerad publik. Temat för konferensen var "Doping and Public Health", och den aspekten behandlades också; dock tolkade flera presentatörer temat på sina egna vis, och hela...

  13. Health-enhancing doping controls

    DEFF Research Database (Denmark)

    Christiansen, Ask Vest

    2010-01-01

    Editorial published at International Network of Humanistic Doping Research (INHDR) website: http://www.doping.au.dk/en/online-resources/editorials/......Editorial published at International Network of Humanistic Doping Research (INHDR) website: http://www.doping.au.dk/en/online-resources/editorials/...

  14. Study on photocatalytic degradation of weak acid dye with N-doped nano-TiO2%氮掺杂纳米TiO2光催化降解弱酸性染料的研究

    Institute of Scientific and Technical Information of China (English)

    冯亚明; 郭晓玲; 申国栋; 车恩涛; 李科

    2013-01-01

    N-doped nano-TiO2 photocatalyst was prepared by sol-gel method and characterized by X-ray diffraction (XRD) and ultraviolet visible light spectroscope (UV-Vis DRS). The visible light photocatalytic properties of the photocatalyst were investigated using Weak Acid Blue A dye solution as the target degrada-tion pol utant. The results showed that the particle size, content of anatase phase, and absorption band edge of photocatalysts were 16.5 nm, 98.7% and 618 nm, respectively, which had a higher absorption for ultraviolet and visible light. When the dosage of photocatalysts was 0.25 g, and the initial concentration and dosage of the weak Acid Blue A dye solution was 40 mg/L and 10.0 mL, the photodegradation rate of dye was 99.2%under 300 W metal halide lamp radiation for 240 min and the pH=2 or 12.%采用X射线衍射和紫外-可见光漫反射对用溶胶-凝胶法制备的氮掺杂纳米TiO2光催化剂进行了表征分析.以弱酸性艳蓝A染料溶液为目标净化物,研究了该催化剂的可见光催化性能.结果表明:氮掺杂纳米TiO2粉体的粒径为16.5 nm,锐钛矿相含量为98.7%,对紫外光和可见光均有较强吸收,其吸收边带达618 nm;催化剂用量为0.25 g,在300 W金卤灯下照射240 min,pH=2或12,对100 mL质量浓度为40 mg/L弱酸性艳蓝A染料溶液的净化率达99.2%.

  15. Gene doping in sports.

    Science.gov (United States)

    Unal, Mehmet; Ozer Unal, Durisehvar

    2004-01-01

    Gene or cell doping is defined by the World Anti-Doping Agency (WADA) as "the non-therapeutic use of genes, genetic elements and/or cells that have the capacity to enhance athletic performance". New research in genetics and genomics will be used not only to diagnose and treat disease, but also to attempt to enhance human performance. In recent years, gene therapy has shown progress and positive results that have highlighted the potential misuse of this technology and the debate of 'gene doping'. Gene therapies developed for the treatment of diseases such as anaemia (the gene for erythropoietin), muscular dystrophy (the gene for insulin-like growth factor-1) and peripheral vascular diseases (the gene for vascular endothelial growth factor) are potential doping methods. With progress in gene technology, many other genes with this potential will be discovered. For this reason, it is important to develop timely legal regulations and to research the field of gene doping in order to develop methods of detection. To protect the health of athletes and to ensure equal competitive conditions, the International Olympic Committee, WADA and International Sports Federations have accepted performance-enhancing substances and methods as being doping, and have forbidden them. Nevertheless, the desire to win causes athletes to misuse these drugs and methods. This paper reviews the current status of gene doping and candidate performance enhancement genes, and also the use of gene therapy in sports medicine and ethics of genetic enhancement.

  16. Doping of organic semiconductors

    Energy Technology Data Exchange (ETDEWEB)

    Luessem, B.; Riede, M.; Leo, K. [Institut fuer Angewandte Photophysik, TU Dresden (Germany)

    2013-01-15

    The understanding and applications of organic semiconductors have shown remarkable progress in recent years. This material class has been developed from being a lab curiosity to the basis of first successful products as small organic LED (OLED) displays; other areas of application such as OLED lighting and organic photovoltaics are on the verge of broad commercialization. Organic semiconductors are superior to inorganic ones for low-cost and large-area optoelectronics due to their flexibility, easy deposition, and broad variety, making tailor-made materials possible. However, electrical doping of organic semiconductors, i.e. the controlled adjustment of Fermi level that has been extremely important to the success of inorganic semiconductors, is still in its infancy. This review will discuss recent work on both fundamental principles and applications of doping, focused primarily to doping of evaporated organic layers with molecular dopants. Recently, both p- and n-type molecular dopants have been developed that lead to efficient and stable doping of organic thin films. Due to doping, the conductivity of the doped layers increases several orders of magnitude and allows for quasi-Ohmic contacts between organic layers and metal electrodes. Besides reducing voltage losses, doping thus also gives design freedom in terms of transport layer thickness and electrode choice. The use of doping in applications like OLEDs and organic solar cells is highlighted in this review. Overall, controlled molecular doping can be considered as key enabling technology for many different organic device types that can lead to significant improvements in efficiencies and lifetimes. (Copyright copyright 2013 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  17. To dope or not to dope

    DEFF Research Database (Denmark)

    Overbye, Marie Birch; Knudsen, Mette Lykke; Pfister, Gertrud Ursula

    2013-01-01

    tAim: This study aims to examine the circumstances which athletes say affect their (hypothetical) consid-erations of whether to dope or not and explore the differences between athletes of different gender, ageand sport type.Methods: 645 elite athletes (mean age: 22.12; response rate: 43%) represe...

  18. Thermal, FT–IR and SHG efficiency studies of L-arginine doped KDP crystals

    Indian Academy of Sciences (India)

    K D Parikh; D J Dave; B B Parekh; M J Joshi

    2007-04-01

    Potassium dihydrogen phosphate (KDP) is a well known nonlinear optical (NLO) material with different applications. Since most of the amino acids exhibit NLO property, it is of interest to dope them in KDP. In the present study, amino acid L-arginine was doped in KDP. The doping of L-arginine was confirmed by FT–IR and paper chromatography. Thermogravimetry suggested that as the amount of doping increases the thermal stability decreases as well as the value of thermodynamic and kinetic parameters decreases. The second harmonic generation (SHG) efficiency of L-arginine doped KDP crystals was found to be increasing with doping concentration of L-arginine. The results are discussed here.

  19. Isoelectronic co-doping

    Science.gov (United States)

    Mascarenhas, Angelo

    2004-11-09

    Isoelectronic co-doping of semiconductor compounds and alloys with deep acceptors and deep donors is used to decrease bandgap, to increase concentration of the dopant constituents in the resulting alloys, and to increase carrier mobilities lifetimes. Group III-V compounds and alloys, such as GaAs and GaP, are isoelectronically co-doped with, for example, N and Bi, to customize solar cells, thermal voltaic cells, light emitting diodes, photodetectors, and lasers on GaP, InP, GaAs, Ge, and Si substrates. Isoelectronically co-doped Group II-VI compounds and alloys are also included.

  20. Doping and Fair Play

    OpenAIRE

    Nicolas Eber

    2009-01-01

    The conventional approach to the economic analysis of doping in sport is that athletes are typically involved in a Prisoner’s Dilemma-type interaction (Breivik 1987, Bird and Wagner 1997, Eber and Thépot 1999, Haugen 2004).1 The idea is straightforward: doping being a dominant strategy (i.e., yielding a preferred outcome regardless of the strategy used by the competitor), each athlete finds it optimal to take drugs; this results in a situation of generalized doping although each athlete would...

  1. Characteristics of the Carbon Nanotube Coated with Polyaniline Doped with Hydrochloric Acid and Dodecylbenzene Sulfonic Acid%盐酸与DBSA共掺杂聚苯胺修饰碳纳米管性能的研究

    Institute of Scientific and Technical Information of China (English)

    张爱波; 刘刚; 薛艳丽; 郑亚萍; 赵纯颖

    2011-01-01

    The MWNTs/polyaniline composites were prepared via in-situ emulsion polymerization using hydrochloric acid and dodecylbenzene sulfonic acid as dopants. The FTIR spectra, TEM and TGA were used to characterize the morphology and performance of the composites. The TEM results show that the surface of MWNTs are coated by polyaniline composites and the thickness of the coating layer is 10~20nm. The solubility is increased in DMF, THF and chloroform. The thermal stability of the composite is highly improved at 520~750℃ and the encapsulation rate is 15.16%. The conductivity of the sample is increased from 10-7S/cm to 10-3S/cm.%采用原位乳液聚合法制备了盐酸与十二烷基苯磺酸(DBSA)共掺杂聚苯胺/MWNTs复合材料.利用FTIR、TEM和TG等对复合材料的形貌和性能进行了表征.TEM结果表明苯胺共聚物包覆于碳纳米管表面,包覆厚度为10~20nm.复合材料在DMF、THF和氯仿中的溶解性大幅度提高,在520~750℃的热稳定性明显提高,包覆率为15.16%,电导率从聚苯胺的10-7A/cm增大到10-3S/cm.

  2. Detonation nanodiamonds for doping Kevlar.

    Science.gov (United States)

    Comet, Marc; Pichot, Vincent; Siegert, Benny; Britz, Fabienne; Spitzer, Denis

    2010-07-01

    This paper reports on the first attempt to enclose diamond nanoparticles--produced by detonation--into a Kevlar matrix. A nanocomposite material (40 wt% diamond) was prepared by precipitation from an acidic solution of Kevlar containing dispersed nanodiamonds. In this material, the diamond nanoparticles (Ø = 4 nm) are entirely wrapped in a Kevlar layer about 1 nm thick. In order to understand the interactions between the nanodiamond surface and the polymer, the oxygenated surface functional groups of nanodiamond were identified and titrated by Boehm's method which revealed the exclusive presence of carboxyl groups (0.85 sites per nm2). The hydrogen interactions between these groups and the amide groups of Kevlar destroy the "rod-like" structure and the classical three-dimensional organization of this polymer. The distortion of Kevlar macromolecules allows the wrapping of nanodiamonds and leads to submicrometric assemblies, giving a cauliflower structure reminding a fractal object. Due to this structure, the macroscopic hardness of Kevlar doped by nanodiamonds (1.03 GPa) is smaller than the one of pure Kevlar (2.31 GPa). To our knowledge, this result is the first illustration of the change of the mechanical properties induced by doping the Kevlar with nanoparticles.

  3. [Doping: effectiveness, consequences, prevention].

    Science.gov (United States)

    Guezennec, C Y

    2001-02-01

    The use of doping is linked with the history of sports. Doping abuse escalated until the mid sixties when government and sports authorities responded with antidoping laws and drug testing. Today, the details of substances detected in controls give a good indication on the importance of doping use. Three classes of pharmaceuticals account for most of the positive controls. They are anabolic steroids, stimulants and narcotics. Their use can be related with the goal of the athletes. Anabolic steroids are mainly used in sports such as bodybuilding or weight lifting in order to develop strength. Stimulants are used in sports were speed favors performance. All the products that enhance blood oxygen transportation are used in endurance sports, their efficacy is not scientifically demonstrated, but their use does result in real risks. Several studies have evidenced the medical problems resulting from prolonged doping. Doping control is impaired by the fact that many products now used, e.g. EPO or rhGH, are not detectable. Regular medical examination of athletes could help prevent use of doping.

  4. Photocatalysis with chromium-doped TiO2: bulk and surface doping.

    Science.gov (United States)

    Ould-Chikh, Samy; Proux, Olivier; Afanasiev, Pavel; Khrouz, Lhoussain; Hedhili, Mohamed N; Anjum, Dalaver H; Harb, Moussab; Geantet, Christophe; Basset, Jean-Marie; Puzenat, Eric

    2014-05-01

    The photocatalytic properties of TiO2 modified by chromium are usually found to depend strongly on the preparation method. To clarify this problem, two series of chromium-doped titania with a chromium content of up to 1.56 wt % have been prepared under hydrothermal conditions: the first series (Cr:TiO2) is intended to dope the bulk of TiO2, whereas the second series (Cr/TiO2) is intended to load the surface of TiO2 with Cr. The catalytic properties have been compared in the photocatalytic oxidation of formic acid. Characterization data provides evidence that in the Cr/TiO2 catalysts chromium is located on the surface of TiO2 as amorphous CrOOH clusters. In contrast, in the Cr:TiO2 series, chromium is mostly dissolved in the titania lattice, although a minor part is still present on the surface. Photocatalytic tests show that both series of chromium-doped titania demonstrate visible-light-driven photo-oxidation activity. Surface-doped Cr/TiO2 solids appear to be more efficient photocatalysts than the bulk-doped Cr:TiO2 counterparts.

  5. Effect of doping on photovoltaic characteristics of graphene

    Science.gov (United States)

    Deepshikha

    2016-12-01

    Chemical doping of CVD grown graphene by introducing PTSA ( n-type) and NBD ( p-type) dopants is explored. This type of doping is key building block for photovoltaic and optoelectronic devices. Doped graphene samples display (1) high transmittance in the visible and near-infrared spectrum and (2) tunable graphene sheet resistance and work function. Large area and uniform graphene films were produced by chemical vapor deposition on copper foils and transferred onto quartz as transparent substrates. For n doping, a solution of p-toluenesulfonic acid (PTSA) was first dropped and spin-coated on the graphene/quartz and then annealed at 100°C for 10 min to make graphene uniformly n-type. Subsequently, a bare graphene was transferred on another quartz substrate, a solution of 4-nitrobenzenediazonium tetrafluoroborate (NBD) was dropped and spin-coated on the surface of graphene and similarly annealed. As a result, the graphene was p and n doped on the different quartz substrates. Doped graphene samples were characterized by different techniques. Experimental results suggested that doped graphene sheets with tunable electrical resistance and high optical transparency can be incorporated into photovoltaics and optoelectronics devices.

  6. Origin and structure of polar domains in doped molecular crystals

    Science.gov (United States)

    Meirzadeh, E.; Azuri, I.; Qi, Y.; Ehre, D.; Rappe, A. M.; Lahav, M.; Kronik, L.; Lubomirsky, I.

    2016-11-01

    Doping is a primary tool for the modification of the properties of materials. Occlusion of guest molecules in crystals generally reduces their symmetry by the creation of polar domains, which engender polarization and pyroelectricity in the doped crystals. Here we describe a molecular-level determination of the structure of such polar domains, as created by low dopant concentrations (<0.5%). The approach comprises crystal engineering and pyroelectric measurements, together with dispersion-corrected density functional theory and classical molecular dynamics calculations of the doped crystals, using neutron diffraction data of the host at different temperatures. This approach is illustrated using centrosymmetric α-glycine crystals doped with minute amounts of different L-amino acids. The experimentally determined pyroelectric coefficients are explained by the structure and polarization calculations, thus providing strong support for the local and global understanding of how different dopants influence the properties of molecular crystals.

  7. Nanocrystal diffusion doping.

    Science.gov (United States)

    Vlaskin, Vladimir A; Barrows, Charles J; Erickson, Christian S; Gamelin, Daniel R

    2013-09-25

    A diffusion-based synthesis of doped colloidal semiconductor nanocrystals is demonstrated. This approach involves thermodynamically controlled addition of both impurity cations and host anions to preformed seed nanocrystals under equilibrium conditions, rather than kinetically controlled doping during growth. This chemistry allows thermodynamic crystal compositions to be prepared without sacrificing other kinetically trapped properties such as shape, size, or crystallographic phase. This doping chemistry thus shares some similarities with cation-exchange reactions, but proceeds without the loss of host cations and excels at the introduction of relatively unreactive impurity ions that have not been previously accessible using cation exchange. Specifically, we demonstrate the preparation of Cd(1-x)Mn(x)Se (0 ≤ x ≤ ∼0.2) nanocrystals with narrow size distribution, unprecedentedly high Mn(2+) content, and very large magneto-optical effects by diffusion of Mn(2+) into seed CdSe nanocrystals grown by hot injection. Controlling the solution and lattice chemical potentials of Cd(2+) and Mn(2+) allows Mn(2+) diffusion into the internal volumes of the CdSe nanocrystals with negligible Ostwald ripening, while retaining the crystallographic phase (wurtzite or zinc blende), shape anisotropy, and ensemble size uniformity of the seed nanocrystals. Experimental results for diffusion doping of other nanocrystals with other cations are also presented that indicate this method may be generalized, providing access to a variety of new doped semiconductor nanostructures not previously attainable by kinetic routes or cation exchange.

  8. 纯MgB2和碳掺杂MgB2超导块材在酸浸过程中相成分和微观结构的演变%Investigation on Phase and Microstructure Compari-son of Pure and Carbon-Doped MgB2 Superconduct-ing Bulks during Acid Exposure

    Institute of Scientific and Technical Information of China (English)

    熊晓梅; 闫果; 刘国庆; 王庆阳; 冯勇

    2009-01-01

    采用X射线衍射仪和扫描电镜系统研究了纯MgB2和碳掺杂MgB2超导块材在的盐酸溶液中(pH=2)酸浸后的相成分和微观结构演变过程.XRD结果显示,纯MgB2和碳掺杂MgB2超导块材均迅速与盐酸反应而分解.分解反应在5 h后完全结束,主要的固态产物是B(OH)3和MgCl2(6H2O).SEM结果显示,纯MgB2和碳掺杂MgB2超导块材与酸反应都是从晶界处开始,与纯MgB2块材相比,碳掺杂MgB2块材在与酸反应后仍保持致密的结构特征.而对酸浸10 min后纯MgB2和碳掺杂MgB2块材的临界超导转变温度测定结果显示,碳掺杂MgB2块材的临界超导转变温度保持不变,说明碳掺杂可提高MgB2在酸中的稳定性.%The phase composition and microstructure evolution of pure and carbon-doped MgB2 bulks exposed to hydrochloric acid (pH=2) for different time were investigated by X-ray diffraction (XRD) and Scanning electron microscopy (SEM) systematically. XRD results show the decomposition of pure and carbon-doped MgB2 bulks exposed to acid is rapid decay with exposure time. The decomposition reaction will finish completely after 5 h exposure and the main solid products are B(OH)3 and MgCl2(6H2O). The SEM results demonstrate that the reaction among pure and carbon-doped MgB2 as well as HCl occurs at grain boundaries. But the grain connection of carbon-doped MgB2 is better than that of pure MgB2 after acid exposure. The Tc of MgB2 decreases after 10 min acid exposure, but Tc is almost unchanged in carbon-doped MgB2 after the same exposure. This result indicates that substitution of C for boron in MgB2 can improve of the resistance to the corrosion of acid.

  9. 水杨酸分子印迹掺氮TiO2粉末的制备及在可见光下的选择性光催化研究%Preparation of salicylic acid molecularly imprinted and N-doped TiO2 powders and their selective photocatalytic activity under visible light

    Institute of Scientific and Technical Information of China (English)

    魏声培; 安娅; 秦好丽

    2016-01-01

    【目的】改善TiO2在可见光下对污染物的选择性降解能力。【方法】采用改进的分子印迹溶胶-凝胶技术,以尿素、水杨酸分别为氮源和模板分子,制备水杨酸分子印迹掺氮TiO2粉末。通过X射线衍射( XRD)、透射电镜( TEM)、紫外-可见光漫反射吸收光谱( UV-Vis DRS)和低温N2物理吸附-脱附( BET)等技术对制备样品进行表征。【结果】样品均为锐钛矿相,氮掺杂致使TiO2光吸收带边红移,分子印迹使TiO2具有了更为发达的孔结构和孔型,掺杂和分子印迹均有效地增大了比表面积。可见光下,与催化降解苯甲酸及甲基橙相比,分子印迹掺氮TiO2对水杨酸的选择性降解率较高,达96.0%。【结论】水杨酸分子印迹和氮掺杂有效地改善了TiO2的选择性和可见光活性。%Objective]To improve selective degradation ability of catalyst ( TiO2 ) under visible light.[Method]Salicylic acid molecularly imprinted and N-doped TiO2 powders were synthesized by an im-proved molecularly imprinted sol-gel technique using urea as a nitrogen ( N) source and salicylic acid as a template molecule. The samples were characterized by XRD, TEM, UV-Vis diffuse reflectance spectro-photometer and N2 adsorption-desorption.[Result]All samples were anatase. The red-shift of absorption band was caused by doping nitrogen to TiO2. The better-developed pore structure and pass were due to molecular imprinting technique, and the enlarged specific surface area was generated by N-doping and molecularly imprinting. Compared to benzoic acid and methyl orange, TiO2 selective photodegradation rate of salicylic acid (96. 0%) was higher under visible light using molecularly imprinting and N-doping.[Conclusion]The selectivity and visible-light photoactivity of TiO2 can be effectively improved using sali-cylic acid molecularly imprinting and N-doping.

  10. Doped barium titanate nanoparticles

    Indian Academy of Sciences (India)

    T K Kundu; A Jana; P Barik

    2008-06-01

    We have synthesized nickel (Ni) and iron (Fe) ion doped BaTiO3 nanoparticles through a chemical route using polyvinyl alcohol (PVA). The concentration of dopant varies from 0 to 2 mole% in the specimens. The results from X-ray diffractograms and transmission electron micrographs show that the particle diameters in the specimen lie in the range 24–40 nm. It is seen that the dielectric permittivity in doped specimens is enhanced by an order of magnitude compared to undoped barium titanate ceramics. The dielectric permittivity shows maxima at 0.3 mole% doping of Fe ion and 0.6 mole% of Ni ion. The unusual dielectric behaviour of the specimens is explained in terms of the change in crystalline structure of the specimens.

  11. Nitrogen-Doped Carbon Dots for "green" Quantum Dot Solar Cells.

    Science.gov (United States)

    Wang, Hao; Sun, Pengfei; Cong, Shan; Wu, Jiang; Gao, Lijun; Wang, Yun; Dai, Xiao; Yi, Qinghua; Zou, Guifu

    2016-12-01

    Considering the environment protection, "green" materials are increasingly explored for photovoltaics. Here, we developed a kind of quantum dots solar cell based on nitrogen-doped carbon dots. The nitrogen-doped carbon dots were prepared by direct pyrolysis of citric acid and ammonia. The nitrogen-doped carbon dots' excitonic absorption depends on the N-doping content in the carbon dots. The N-doping can be readily modified by the mass ratio of reactants. The constructed "green" nitrogen-doped carbon dots solar cell achieves the best power conversion efficiency of 0.79 % under AM 1.5 G one full sun illumination, which is the highest efficiency for carbon dot-based solar cells.

  12. Exploring Knowledge, Attitudes and Abuse Concerning Doping in Sport among Syrian Pharmacy Students

    Directory of Open Access Journals (Sweden)

    Mazen El-Hammadi

    2013-09-01

    Full Text Available This study aimed to assess pharmacy students’ knowledge about doping substances used in sport, explore their attitudes toward doping and investigate their misuse of doping drugs. A questionnaire was developed and employed to collect data from bachelor of pharmacy (BPharm students at the International University for Science and Technology (IUST. Two-hundred and eighty students participated in this self-administrated, paper-based survey. Around 90% of the students did not appear to know that narcotics, β-blockers and diuretics were used in sport as doping agents. Additionally, proportions between 60% and 80% considered vitamins, energy drinks and amino acids as substances that possess performance-enhancing effects. The main reason for doping, based on students’ response, was to improve muscular body appearance. The vast majority of students agreed that pharmacists should play a major role in promoting awareness about risks of doping. While students showed negative attitudes toward doping, approximately 15% of them, primarily males, had already tried a doping drug or might do so in the future. More than 60% of the students believed that sports-mates and friends are the most influential in encouraging them to take a doping agent. The study highlights the need to provide pharmacy students with advanced theoretical background and practical training concerning doping. This can be achieved by adopting simple, but essential, changes to the current curricula.

  13. Photocatalysis with chromium-doped TiO2: Bulk and surface doping

    KAUST Repository

    Ould-Chikh, Samy

    2014-04-15

    The photocatalytic properties of TiO2 modified by chromium are usually found to depend strongly on the preparation method. To clarify this problem, two series of chromium-doped titania with a chromium content of up to 1.56 wt % have been prepared under hydrothermal conditions: the first series (Cr:TiO2) is intended to dope the bulk of TiO2, whereas the second series (Cr/TiO2) is intended to load the surface of TiO2 with Cr. The catalytic properties have been compared in the photocatalytic oxidation of formic acid. Characterization data provides evidence that in the Cr/TiO2 catalysts chromium is located on the surface of TiO2 as amorphous CrOOH clusters. In contrast, in the Cr:TiO 2 series, chromium is mostly dissolved in the titania lattice, although a minor part is still present on the surface. Photocatalytic tests show that both series of chromium-doped titania demonstrate visible-light-driven photo-oxidation activity. Surface-doped Cr/TiO2 solids appear to be more efficient photocatalysts than the bulk-doped Cr:TiO2 counterparts. It\\'s classified! The photocatalytic properties of TiO2 modified by chromium depend strongly on the preparation method. To clarify this problem, two types of modified titania are discussed: one with CrIII doped in the bulk and one with CrOOH clusters on the TiO2 surface (see picture). Both series show visible-light-driven photo-oxidation activity. However, surface modification appears to be a more efficient strategy. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  14. Electrochemical sensing behaviour of Ni doped Fe{sub 3}O{sub 4} nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Suresh, R.; Giribabu, K.; Manigandan, R.; Narayanan, V., E-mail: vnnara@yahoo.co.in [Department of Inorganic Chemistry, University of Madras, Guindy Campus, Chennai 600 025 (India); Vijayalakshmi, L. [Annai Veilankanni' s College for Women (Arts and Science), Saidapet, Chennai 600015 (India); Stephen, A. [Department of Nuclear Physics, University of Madras, Guindy Campus, Chennai 600 025 (India)

    2014-01-28

    Ni doped Fe{sub 3}O{sub 4} nanoparticles were synthesized by simple hydrothermal method. The prepared nanomaterials were characterized by X-ray diffraction analysis, DRS-UV-Visible spectroscopy and field emission scanning electron microscopy. The XRD confirms the phase purity of the synthesized Ni doped Fe{sub 3}O{sub 4} nanoparticles. The optical property of Ni doped Fe{sub 3}O{sub 4} nanoparticles were studied by DRS UV-Visible analysis. The electrochemical sensing property of pure and Ni doped Fe{sub 3}O{sub 4} nanoparticles were examined using uric acid as an analyte. The obtained results indicated that the Ni doped Fe{sub 3}O{sub 4} nanoparticles exhibited higher electrocatalytic activity towards uric acid.

  15. Doped zinc oxide microspheres

    Science.gov (United States)

    Arnold, Jr., Wesley D.; Bond, Walter D.; Lauf, Robert J.

    1993-01-01

    A new composition and method of making same for a doped zinc oxide microsphere and articles made therefrom for use in an electrical surge arrestor which has increased solid content, uniform grain size and is in the form of a gel.

  16. Role Models on Dope

    DEFF Research Database (Denmark)

    Christiansen, Ask Vest; Gleaves, John

    2014-01-01

    Compared to football-players cyclists are virtuous role models. Yes, Lance Armstrong, Michael Rasmussen and other riders have doped, and because of this they have received the predicate as the most immoral athletes in the sporting world. But if morality is not only a question of whether a person...

  17. Gene doping: an overview and current implications for athletes.

    Science.gov (United States)

    van der Gronde, Toon; de Hon, Olivier; Haisma, Hidde J; Pieters, Toine

    2013-07-01

    The possibility of gene doping, defined as the transfer of nucleic acid sequences and/or the use of normal or genetically modified cells to enhance sport performance, is a real concern in sports medicine. The abuse of knowledge and techniques gained in the area of gene therapy is a form of doping, and is prohibited for competitive athletes. As yet there is no conclusive evidence that that gene doping has been practiced in sport. However, given that gene therapy techniques improve continuously, the likelihood of abuse will increase. A literature search was conducted to identify the most relevant proteins based on their current gene doping potential using articles from Pubmed, Scopus and Embase published between 2006 and 2011. The final list of selected proteins were erythropoietin, insulin-like growth factor, growth hormone, myostatin, vascular endothelial growth factor, fibroblast growth factor, endorphin and enkephalin, α actinin 3, peroxisome proliferator-activated receptor-delta (PPARδ) and cytosolic phosphoenolpyruvate carboxykinase (PEPCK-C). We discuss these proteins with respect to their potential benefits, existing gene therapy experience in humans, potential risks, and chances of detection in current and future anti-doping controls. We have identified PPARδ and PEPCK-C as having high potential for abuse. But we expect that for efficiency reasons, there will be a preference for inserting gene target combinations rather than single gene doping products. This will also further complicate detection.

  18. CSA doped polypyrrole-zinc oxide thin film sensor

    Science.gov (United States)

    Chougule, M. A.; Jundale, D. M.; Raut, B. T.; Sen, Shashwati; Patil, V. B.

    2013-02-01

    The polypyrrole-zinc oxide (PPy-ZnO) hybrid sensor doped with different weight ratios of camphor sulphonic acid (CSA) were prepared by spin coating technique. These CSA doped PPy-ZnO hybrids were characterized by field emission scanning electron microscope (FESEM) and fourier transform infrared (FTIR) which proved the formation of polypyrrole, PPy-ZnO and the interaction between polypyrrole - ZnO (PPy-ZnO) hybrid with CSA doping. The gas sensing properties of the PPy-ZnO hybrid films doped with CSA have been studied for oxidizing (NO2) as well as reducing (H2S, NH3, CH4OH and CH3OH) gases at room temperature. We demonstrate that CSA doped PPy-ZnO hybrid films are highly selective to NO2 along with high-sensitivity at low concentration (80% to 100 ppm) and better stability, which suggested that the CSA doped PPy-ZnO hybrid films are potential candidate for NO2 detection at room temperature.

  19. Fitness Doping and Body Management

    DEFF Research Database (Denmark)

    Thualagant, Nicole

    This PhD thesis examines in a first paper the conceptualization of fitness doping and its current limitations. Based on a review of studies on bodywork and fitness doping it is emphasised that the definition of doping does not provide insights into bodywork of both men and women. Moreover......, it is argued that the social and a cultural context are missing in the many epidemiological studies on the prevalence of doping. The second paper explores the difficulties of implementing an anti-doping policy, which was originally formulated in an elite sport context, in a fitness context and more...... specifically in a sport-for-all context. It is questioned whether the anti-doping policy contradicts some of the national sport-for-all organisation, DGI’s values of fostering fellowship, challenge and health. Last but not least, this thesis examines in a third paper the bodywork of the users’ of the club...

  20. Enhancement of the fuel cell performance of a high temperature proton exchange membrane fuel cell running with titanium composite polybenzimidazole-based membranes

    Science.gov (United States)

    Lobato, Justo; Cañizares, Pablo; Rodrigo, Manuel A.; Úbeda, Diego; Pinar, F. Javier

    2011-10-01

    The fuel cell performance of a composite PBI-based membrane with TiO2 has been studied. The behaviour of the membrane has been evaluated by comparison with the fuel cell performance of other PBI-based membranes, all of which were cast from the same polymer with the same molecular weight. The PBI composite membrane incorporating TiO2 showed the best performance and reached 1000 mW cm-2 at 175 °C. Moreover, this new titanium composite PBI-based membrane also showed the best stability during the preliminary long-term test under our operation conditions. Thus, the slope of the increase in the ohmic resistance of the composite membrane was 0.041 mΩ cm2 h-1 and this is five times lower than that of the standard PBI membrane. The increased stability was due to the high phosphoric acid retention capacity - as confirmed during leaching tests, in which the Ti-based composite PBI membrane retained 5 mol of H3PO4/PBI r.u. whereas the PBI standard membrane only retained 1 mol H3PO4/PBI r.u. Taking into account the results obtained in this study, the TiO2-PBI based membranes are good candidates as electrolytes for high temperature PEMFCs.

  1. Doping of carbon foams for use in energy storage devices

    Science.gov (United States)

    Mayer, Steven T.; Pekala, Richard W.; Morrison, Robert L.; Kaschmitter, James L.

    1994-01-01

    A polymeric foam precursor, wetted with phosphoric acid, is pyrolyzed in an inert atmosphere to produce an open-cell doped carbon foam, which is utilized as a lithium intercalation anode in a secondary, organic electrolyte battery. Tests were conducted in a cell containing an organic electrolyte and using lithium metal counter and reference electrodes, with the anode located therebetween. Results after charge and discharge cycling, for a total of 6 cycles, indicated a substantial increase in the energy storage capability of the phosphorus doped carbon foam relative to the undoped carbon foam, when used as a rechargeable lithium ion battery.

  2. [Doping and urologic tumors].

    Science.gov (United States)

    Pinto, F; Sacco, E; Volpe, A; Gardi, M; Totaro, A; Calarco, A; Racioppi, M; Gulino, G; D'Addessi, A; Bassi, P F

    2010-01-01

    Several substances such as growth hormone (GH), erythropoietin (Epo), and anabolic steroids (AS) are improperly utilized to increase the performance of athletes. Evaluating the potential cancer risk associated with doping agents is difficult since these drugs are often used at very high doses and in combination with other licit or illicit drugs. The GH, via its mediator, the insulin-like growth factor 1 (IGF-1), is involved in the development and progression of cancer. Animal studies suggested that high levels of GH/IGF-1 increase progression of androgen-independent prostate cancer. Clinical data regarding prostate cancer are mostly based on epidemiological studies or indirect data such as IGF-1 high levels in patients with prostate cancer. Even if experimental studies showed a correlation between Epo and cancer, no clinical data are currently available on cancer development related to Epo as a doping agent. Androgens are involved in prostate carcinogenesis modulating genes that regulate cell proliferation, apoptosis and angiogenesis. Most information on AS is anecdotal (case reports on prostate, kidney and testicular cancers). Prospective epidemiologic studies failed to support the hypothesis that circulating androgens are positively associated with prostate cancer risk. Currently, clinical and epidemiological studies supporting association between doping and urological neoplasias are not available. Nowadays, exposure to doping agents starts more prematurely with a consequent longer exposition period; drugs are often used at very high doses and in combination with other licit or illicit drugs. Due to all these elements it is impossible to predict all the side effects, including cancer; more detailed studies are therefore necessary.

  3. Highly conductive and thermally stable self-doping propylthiosulfonated polyanilines

    Institute of Scientific and Technical Information of China (English)

    Han Chien-Chung

    2004-01-01

    A new type of highly conductive self-doping polyaniline, MPS-Pan, containing a sulfonic acid moiety covalently bonded to the polymer backbone through an electron-donating propylthio linkage has been successfully prepared via a novel concurrent reduction and substitution route. At a similar self-doping level, the resultant MPS-Pans displayed much higher conductivity than the corresponding sulfonated-polyaniline (S-Pan). Furthermore, for fully doped samples, contrary to the trend of decreasing conductivity with the sulfonation degree in S-Pan, the conductivity of MPS-Pan was found to increase with its substitution degree. These results agreed with the expectation that electron-deficient charge carriers (e.g. semiquinone radical cations) on acid-doped polyaniline chains will be better stabilized by the electron-donating alkylthio-substituent. Surprisingly, TG and XPS studies showed that MPS-Pan was thermally much more stable than S-Pan, with S-Pan started to lose its sulfonic acid dopant at 185 ℃, while MPS-Pan remained intact up to ca. 260 ℃.

  4. Doped Chiral Polymer Metamaterials Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Doped Chiral Polymer Metamaterials (DCPM) with tunable resonance frequencies have been developed by adding plasmonic inclusions into chiral polymers with variable...

  5. Simultaneous determination of dopamine and uric acid at copper doped poly(L-aspartic acid) modified electrode%铜掺杂聚 L-天冬氨酸修饰电极同时测定多巴胺和尿酸

    Institute of Scientific and Technical Information of China (English)

    王金梅; 马伟; 孙登明

    2012-01-01

      用循环伏安法制备了铜掺杂聚 L-天冬氨酸修饰玻碳电极,研究了多巴胺(DA)和尿酸(UA)在该修饰电极上的电化学行为,建立了同时测定 DA 和 UA 的新方法.在 pH3.5的磷酸盐缓冲溶液中,扫描速率为120 mV/s 时, DA 和 UA 在该电极上产生氧化还原峰,峰电位分别为 Epa=0.429 V、Epc=0.336 V(DA)和 Epa=0.617 V(UA),DA 和 UA 的氧化峰分开达0.188 V.采用循环伏安法(CV 法)和示差脉冲伏安法(DPVs 法)同时测定 DA 和 UA 的线性范围分别为:DA:3.00×10-6~4.00×10-5 mol/L、4.00×10-5~1.00×10-4 mol/L (CV)、3.00×10-7~3.00×10-6 mol/L、3.00×10-6~1.00×10-5 mol/L (DPVs),UA:8.00×10-6~5.00×10-5 mol/L、5.00×10-5~2.00×10-4 mol/L (CV)、3.00×10-7~5.00×10-5 mol/L、5.00×10-5~2.00×10-4 mol/L (DPVs);检出限分别为8.0×10-7 mol/L、1.0×10-6 mol/L (CV)和3.0×10-7 mol/L、3.0×10-7 mol/L(DPVs).用于人体尿液中 DA 和 UA 的同时测定,结果满意%  The copper doped poly (L-aspartic acid) modified electrode was prepared using cyclic voltammetric method. The voltammetric behavior of dopamine (DA), uric acid (UA) and electrochemical method for simultaneous determination of DA and UA were studied at the copper doped poly (L-aspartic acid) modified electrode. In pH3.5 phosphate buffer solution, the modified electrode gave a pair of redox peaks at Epa=0.429 V, Epc=0.336 V for DA, one oxdition peak at Epa=0.617 V for UA at the scan rate of 120 mV/s. The separated oxidation peaks of DA and UA was divided 0.188 V. The linear response were obtained in the range of 3.00 ×10-6~4.00 ×10-5 mol/L、4.00 ×10-5~1.00×10-4 mol/L(CV) and 3.00×10-7~3.00×10-6 mol/L、3.00×10-6~1.00×10-5 mol/L(DPVs) for DA ; 8.00 ×10-6~5.00×10-5 mol/L、5.00×10-5~2.00×10-4 mol/L (CV) and 3.00×10-7~5.00×10-5 mol/L、5.00×10-5~2.00×10-4 mol/L (DPVs) for UA, respectively. The detection limits of DA and UA were 8.0 ×10-7 mol/L, 1.0 ×10 -6 mol/L (CV) and 3.0 ×10 -7 mol/L, 3.0×10 -7

  6. Role of mesoscopic morphology in charge transport of doped polyaniline

    Indian Academy of Sciences (India)

    A K Mukherjee; Reghu Menon

    2002-02-01

    In doped polyaniline (PANI), the charge transport properties are determined by mesoscopic morphology, which in turn is controlled by the molecular recognition interactions among polymer chain, dopant and solvent. Molecular recognition plays a significant role in chain conformation and charge delocalization. The resistivity of PANI doped by camphor sulfonic acid (CSA)/2-acrylo-amido-1-propane sulfonic acid (AMPSA)/dodecyl benzene sulfonic acid (DBSA) is around 0.02 cm. PANI-CSA and PANI-AMPSA show a metallic positive temperature coefficient of resistivity above 150 K, with a finite value of conductivity at 1.4 K; whereas, PANI-DBSA shows hopping transport at low temperatures. The magnetoresistance is positive (negative) for PANI-CSA (PANIAMPSA); and PANI-DBSA has a large positive MR. The behavior of MR suggests subtle variations in mesoscopic morphology between PANI-CSA and PANI-AMPSA.

  7. Comparison of Soy Protein Dope with Yeast Protein Dope on the Rheological Properties

    OpenAIRE

    Hayakawa, Isao; Chang, Hung Min; Katoh, Tatsuo

    1984-01-01

    Rheological properties of isolated soybean protein dopes were compared with those of yeart protein dopes in order to find out their application and processing. The elastic properties of soybean protein dope were better than those of yeast protein dope prepared with high protein concentrates because the viscoelastic absorption of soybean protein dope was smaller than that of yeast protein dope and the capacity of water holding was higher than that of yeast protein dope. On the other hand, yeas...

  8. Electrochemical synthesis and characterization of chloride doped polyaniline

    Indian Academy of Sciences (India)

    A M Pharhad Hussain; A Kumar

    2003-04-01

    Chloride doped polyaniline conducting polymer films have been prepared in a protic acid medium (HCl) by potentiodynamic method in an electrochemical cell and studied by cyclic voltammetry and FTIR techniques. The FTIR spectra confirmed Cl– ion doping in the polymers. The polymerization rate was found to increase with increasing concentration of aniline monomer. But the films obtained at high monomer concentration were rough having a nonuniform flaky polyaniline distribution. Results showed that the polymerization rate did not increase beyond a critical HCl concentration. Cyclic voltammetry suggested that, the oxidation-reduction current increased with an increase in scan rate and that the undoped polyaniline films were not hygroscopic whereas chloride doped polyaniline films were found to be highly hygroscopic.

  9. Hydrothermal synthesis, characterization and luminescent properties of lanthanide-doped NaLaF$_4$ nanoparticles

    Indian Academy of Sciences (India)

    JIGMET LADOL; HEENA KHAJURIA; SONIKA KHAJURIA; HAQ NAWAZ SHEIKH

    2016-08-01

    Nanoparticles of sodium lanthanum (III) fluoride-doped and co-doped with Eu$^{3+}/Tb$^{3+}$ were prepared by the hydrothermal method using citric acid as structure-directing agent. Structural aspects and optical properties of synthesized nanoparticles were studied by powder X-ray diffraction (XRPD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), selected area electron diffraction (SAED), energy-dispersive X-ray spectra (EDS), particle size by dynamic light scattering (DLS), Fourier transform infrared (FTIR) spectrum and photoluminescence (PL) techniques. Nanoparticles consist of well-crystallized hexagonal phase and the average crystallite size for undoped and doped-NaLaF$_4$ nanoparticles are in the range of 20–22 nm. TEM images show that nanoparticles have cylindrical shape and crystalline nature of nanoparticles was confirmed by SAED patterns. Downconversion(DC) luminescent properties of doped NaLaF4 were also investigated and impact of co-doping has been explored.

  10. Dielectric parameters and a.c. conductivity of pure and doped poly (methyl methacrylate) films at microwave frequencies

    Indian Academy of Sciences (India)

    Anju Tanwar; K K Gupta; P J Singh; Y K Vijay

    2006-08-01

    Dielectric properties of pure and doped poly (methyl methacrylate) (PMMA) films at microwave frequency, 8.92 GHz, have been studied at 35°C. Iodine, benzoic acid and FeCl3 have been used as dopants. The losses in doped films are found to be larger than in pure PMMA films. The increased losses account for increased a.c. conductivity in doped films. The increase in conductivity is accounted due to creation of additional hopping sites for the charge carriers in doped samples. The dielectric data has also been used to evaluate optical constants, absorption index () and refractive index () of the films.

  11. 燃料电池用纳米改性聚苯并咪唑阴离子交换膜的制备%Synthesis of Polybenzimidazole/Nano-Particles Hybrid Anion Conducting Membranes Used for Fuel Cell

    Institute of Scientific and Technical Information of China (English)

    汪称宇; 储富强; 林本才; 冯天英; 袁宁一; 丁建宁

    2016-01-01

    Imidazolium-based ionic liquid (IL) was synthesized from epichlorohydrin and 1 –methyl imidazole,and ionic liquid functionalized graphene oxide (IL–GO) was obtained from IL and graphene oxide (GO). Different content of IL–GO was incorporated into polybenzimidazole (FPBI) to investigate the content effect on the properties of composite membranes. The effect of content of IL–GO on the thermal stability,mechanical strength,ionic conductivity,ion exchange capacity (IEC),water absorption, swelling degree and alkali resistance performance of composite film were investigated. The results show that as the content of IL–GO increases,the properties of the composite membranes,such as proton conductivity,IEC and tensile properties present an increase variation. When IL–GO content is 30%,its tensile stress and tensile elastic modulus reach 77.5 MPa and 1.95 GPa respectively. Under 80℃,its maximum ionic conductivity reach up to 72.3 mS/cm. However,the thermal stability of the composite membranes don’t dramatically change,and the composite membranes show an excellent alkaline stability. This investigation demonstrates that FPBI/IL–GO composite membranes may be promising for alkaline anion exchange membrane fuel cell applications.%以环氧氯丙烷和1–甲基咪唑为原料制备新型离子液体(IL),以IL为原料对氧化石墨烯(GO)进行表面修饰制备离子液体功能化氧化石墨烯(IL–GO),以IL–GO为添加剂制备基于含氟聚苯并咪唑(FPBI)复合膜。研究了IL–GO的含量对复合膜的热稳定性、力学强度、离子电导率、离子交换容量(IEC)、吸水率、溶胀度和耐碱性等性能的影响。研究结果表明,复合膜的IEC、离子电导率和拉伸性能都随着IL–GO含量的增加而增大,当IL–GO含量为30%时其拉伸应力和拉伸弹性模量分别达到77.5 MPa和1.95 GPa,在80℃下,其最大离子电导率可达72.3 mS/cm,然而复合膜的热稳定性并没随着IL–GO含

  12. Gene doping in modern sport.

    Directory of Open Access Journals (Sweden)

    MAREK SAWCZUK

    2009-01-01

    Full Text Available Background: The subject of this paper is gene doping, which should be understood as "he non-therapeutic use of cells, genes, genetic elements, or of the modulation of gene expression, having the capacity to improve athletic performance". The authors of this work, based on the review of literature and previous research, make an attempt at wider characterization of gene doping and the discussion of related potential threats.Methods: This is a comprehensive survey of literature on the latest applications of molecular biology in medicine. The analysis involves a dozen scientific databases examined in order to find genes used in gene therapy and potentially useful in gene doping. Results: The obtained results enable better recognition of gene doping and indicate genes used in medicine that could be used in gene doping. This paper describes potential effects of their use and associated risk, and predicts the possible developments of gene doping in the future. Conclusion: Gene doping is undoubtedly a part of modern sport. Although WADA included gene doping on the list of banned methods as early as 2004, as previously stated above, it has not managed to develop efficient methods of detection.

  13. Fullerene-doped porous glasses

    Science.gov (United States)

    Joshi, M. P.; Kukreja, L. M.; Rustagi, K. C.

    We report the doping of C60 in porous glass by diffusion in solution phase at room temperature. The presence of C60 in the doped porous glass was confirmed spectroscopically. We also report the changes in optical absorption spectrum and intensity-dependent transmission of 30 ns laser pulses at 527 nm in these materials.

  14. Fullerene-doped porous glasses

    Energy Technology Data Exchange (ETDEWEB)

    Joshi, M.P. [Center for Adv. Technol., Indore (India). Nonlinear Optics Group; Kukreja, L.M. [Center for Adv. Technol., Indore (India). Nonlinear Optics Group; Rustagi, K.C. [Center for Adv. Technol., Indore (India). Nonlinear Optics Group

    1997-07-01

    We report the doping of C{sub 60} in porous glass by diffusion in solution phase at room temperature. The presence of C{sub 60} in the doped porous glass was confirmed spectroscopically. We also report the changes in optical absorption spectrum and intensity-dependent transmission of 30 ns laser pulses at 527 nm in these materials. (orig.)

  15. Nitrogen doping in carbon nanotubes.

    Science.gov (United States)

    Ewels, C P; Glerup, M

    2005-09-01

    Nitrogen doping of single and multi-walled carbon nanotubes is of great interest both fundamentally, to explore the effect of dopants on quasi-1D electrical conductors, and for applications such as field emission tips, lithium storage, composites and nanoelectronic devices. We present an extensive review of the current state of the art in nitrogen doping of carbon nanotubes, including synthesis techniques, and comparison with nitrogen doped carbon thin films and azofullerenes. Nitrogen doping significantly alters nanotube morphology, leading to compartmentalised 'bamboo' nanotube structures. We review spectroscopic studies of nitrogen dopants using techniques such as X-ray photoemission spectroscopy, electron energy loss spectroscopy and Raman studies, and associated theoretical models. We discuss the role of nanotube curvature and chirality (notably whether the nanotubes are metallic or semiconducting), and the effect of doping on nanotube surface chemistry. Finally we review the effect of nitrogen on the transport properties of carbon nanotubes, notably its ability to induce negative differential resistance in semiconducting tubes.

  16. Study of the growth and pyroelectric properties of TGS crystals doped with aniline-family dipolar molecules

    Science.gov (United States)

    Zhang, Kecong; Song, Jiancheng; Wang, Min; Fang, Changshui; Lu, Mengkai

    1987-04-01

    TGS crystals doped with aniline-family dipolar molecules (aniline, 2-aminobenzoic acid, 3-aminobenzoic acid, 3-aminobenzene-sulphonic acid, 4-aminobenzenesulphonic acid and 4-nitroraniline) have been grown by the slow-cooling solution method. The influence of these dopants on the growth habits, crystal morphology pyroelectric properties, and structure parameters of TGS crystals has been systematically investigated. The effects of the domain structure of the seed crystal on the pyroelectric properties of the doped crystals have been studied. It is found that the spontaneous polarization (P), pyroelectric coefficient (lambda), and internal bias field of the doped crystals are slightly higher than those of the pure TGS, and the larger the dipole moment of the dopant molecule, the higher the P and lambda of the doped TGS crystal.

  17. The effect of preparation method on the proton conductivity of indium doped tin pyrophosphates

    DEFF Research Database (Denmark)

    Anfimova, Tatiana; Lie-Andersen, T.; Jensen, E. Pristed

    2015-01-01

    Indium doped tin pyrophosphates were prepared by three synthetic routes. A heterogeneous synthesis from metal oxides with excess phosphoric acid produces crystalline phosphate particles with a phosphorus rich amorphous phase along the grain boundaries. The amorphous phase prevents the agglomeration...... phosphates from the chloride synthesis but no improvement for the acid treated phosphates from the acetate synthesis was observed....

  18. Effect of doping on TSD relaxation in cellulose acetate films

    Indian Academy of Sciences (India)

    P K Khare; P L Jain; R K Pandey

    2000-12-01

    Thermally stimulated depolarization current (TSDC) studies have been performed on solution grown cellulose acetate films doped with different concentrations of acrylic acid (AA) prepared at the poling temperatures (40–75°C) with poling fields (10–50 kV/cm). The TSDC spectra of pure and AA doped CA films reveal two relaxation peaks at 80°C and 180 ± 2°C, having activation energies centred around 0.25 and 0.55 eV. The phenomena of the existence of these current maxima have been analyzed and discussed in terms of the molecular motion of the polar side groups and release of the remaining part of the frozen dipoles by their cooperative motion with adjoining segments of the main polymer chain. The peak currents, released charge and activation energies associated with the peaks are affected by AA doping. The effect of doping with acrylic acid on the discharge current indicates the formation of molecular aggregates.

  19. Room temperature ferromagnetism in Fe-doped CuO nanoparticles.

    Science.gov (United States)

    Layek, Samar; Verma, H C

    2013-03-01

    The pure and Fe-doped CuO nanoparticles of the series Cu(1-x)Fe(x)O (x = 0.00, 0.02, 0.04, 0.06 and 0.08) were successfully prepared by a simple low temperature sol-gel method using metal nitrates and citric acid. Rietveld refinement of the X-ray diffraction data showed that all the samples were single phase crystallized in monoclinic structure of space group C2/c with average crystallite size of about 25 nm and unit cell volume decreases with increasing iron doping concentration. TEM micrograph showed nearly spherical shaped agglomerated particles of 4% Fe-doped CuO with average diameter 26 nm. Pure CuO showed weak ferromagnetic behavior at room temperature with coercive field of 67 Oe. The ferromagnetic properties were greatly enhanced with Fe-doping in the CuO matrix. All the doped samples showed ferromagnetism at room temperature with a noticeable coercive field. Saturation magnetization increases with increasing Fe-doping, becomes highest for 4% doping then decreases for further doping which confirms that the ferromagnetism in these nanoparticles are intrinsic and are not resulting from any impurity phases. The ZFC and FC branches of the temperature dependent magnetization (measured in the range of 10-350 K by SQUID magnetometer) look like typical ferromagnetic nanoparticles and indicates that the ferromagnetic Curie temperature is above 350 K.

  20. Synthesis and characterization of gadolinium-doped nanotubular titania for enhanced photocatalysis

    Energy Technology Data Exchange (ETDEWEB)

    Shi, Liang [College of Chemistry and Chemical Engineering, Ocean University of China, Qingdao 266100 (China); Cao, Lixin, E-mail: caolixin@ouc.edu.cn [College of Chemistry and Chemical Engineering, Ocean University of China, Qingdao 266100 (China); Institute of Materials Science and Engineering, Ocean University of China, Qingdao 266100 (China); Gao, Rongjie; Zhao, Yanling [Institute of Materials Science and Engineering, Ocean University of China, Qingdao 266100 (China); Zhang, Huibin; Xia, Chenghui [College of Chemistry and Chemical Engineering, Ocean University of China, Qingdao 266100 (China)

    2014-12-25

    Graphical abstract: The Gd-doped titania nanotubes showed an increase in photocatalytic activity together with Gd/Ti ratio increase up 0.5%, followed by a rapid fall above 1.0%. - Highlights: • Enhanced Gd-doped titania nanotube photocatalysts have been synthesized. • Uniform Gd-doped titania nanoparticles were employed as raw materials. • Actual gadolinium contents in titania were precisely characterized by ICP-AES. • The distribution of Gd dopant was marked using element mapping. - Abstract: Gadolinium-doped titanium dioxide nanotubes were fabricated with a facile two-step route. Precursors Gd-doped titania nanoparticles were synthesized by a traditional sol–gel method. Hydrothermal process and acid treatment were employed afterwards, and Gd-doped titania nanotubes were finally obtained after calcination. The nominal doping concentration was expressed by Gd/Ti atomic ratio, ranged from 0% to 5.0%. Both the precursors and nanotubes were characterized by X-ray photoelectron spectra, inductively coupled plasma-atomic emission spectrometry, transmission electron microscopy, scanning electron microscopy, X-ray diffraction, energy dispersive X-ray spectrometer, UV–vis diffusion reflection spectra and N{sub 2} absorption–desorption experiment. The photocatalytic activities were investigated using methyl orange as the model pollutant. The results indicated that Gd-doped titania nanotubes with nominal Gd/Ti of 0.5% possessed the optimal photocatalytic activity in our study.

  1. Superconducting doped topological materials

    Energy Technology Data Exchange (ETDEWEB)

    Sasaki, Satoshi, E-mail: sasaki@sanken.osaka-u.ac.jp [Institute of Scientific and Industrial Research, Osaka University, Ibaraki, Osaka 567-0047 (Japan); Mizushima, Takeshi, E-mail: mizushima@mp.es.osaka-u.ac.jp [Department of Materials Engineering Science, Osaka University, Toyonaka, Osaka 560-8531 (Japan); Department of Physics, Okayama University, Okayama 700-8530 (Japan)

    2015-07-15

    Highlights: • Studies on both normal- and SC-state properties of doped topological materials. • Odd-parity pairing systems with the time-reversal-invariance. • Robust superconductivity in the presence of nonmagnetic impurity scattering. • We propose experiments to identify the existence of Majorana fermions in these SCs. - Abstract: Recently, the search for Majorana fermions (MFs) has become one of the most important and exciting issues in condensed matter physics since such an exotic quasiparticle is expected to potentially give rise to unprecedented quantum phenomena whose functional properties will be used to develop future quantum technology. Theoretically, the MFs may reside in various types of topological superconductor materials that is characterized by the topologically protected gapless surface state which are essentially an Andreev bound state. Superconducting doped topological insulators and topological crystalline insulators are promising candidates to harbor the MFs. In this review, we discuss recent progress and understanding on the research of MFs based on time-reversal-invariant superconducting topological materials to deepen our understanding and have a better outlook on both the search for and realization of MFs in these systems. We also discuss some advantages of these bulk systems to realize MFs including remarkable superconducting robustness against nonmagnetic impurities.

  2. Doped semiconductor nanocrystal junctions

    Energy Technology Data Exchange (ETDEWEB)

    Borowik, Ł.; Mélin, T., E-mail: thierry.melin@isen.iemn.univ-lille1.fr [Institut d’Electronique, de Microélectronique et de Nanotechnologie, CNRS-UMR8520, Avenue Poincaré, F-59652 Villeneuve d’Ascq (France); Nguyen-Tran, T.; Roca i Cabarrocas, P. [Laboratoire de Physique des Interfaces et des Couches Minces, CNRS-UMR7647, Ecole Polytechnique, F-91128 Palaiseau (France)

    2013-11-28

    Semiconductor junctions are the basis of electronic and photovoltaic devices. Here, we investigate junctions formed from highly doped (N{sub D}≈10{sup 20}−10{sup 21}cm{sup −3}) silicon nanocrystals (NCs) in the 2–50 nm size range, using Kelvin probe force microscopy experiments with single charge sensitivity. We show that the charge transfer from doped NCs towards a two-dimensional layer experimentally follows a simple phenomenological law, corresponding to formation of an interface dipole linearly increasing with the NC diameter. This feature leads to analytically predictable junction properties down to quantum size regimes: NC depletion width independent of the NC size and varying as N{sub D}{sup −1/3}, and depleted charge linearly increasing with the NC diameter and varying as N{sub D}{sup 1/3}. We thus establish a “nanocrystal counterpart” of conventional semiconductor planar junctions, here however valid in regimes of strong electrostatic and quantum confinements.

  3. Optical phase-conjugation in erioglaucine dye-doped thin film

    Indian Academy of Sciences (India)

    T Geethakrishnan; P K Palanisamy

    2006-02-01

    Optical phase-conjugation (OPC) has been demonstrated in erioglaucine (acid blue 9) dye-doped gelatin films via continuous-wave degenerate four-wave mixing (DFWM) using a low-power He-Ne laser at 633 nm. DFWM and holographic processes are found to contribute to the observed phase-conjugate signal. A maximum phase-conjugate beam reflectivity of about 0.24% has been observed in these dye-doped gelatin films.

  4. The Ethics of Doping and Anti-Doping

    DEFF Research Database (Denmark)

    Møller, Verner

    With every positive drugs test the credibility and veracity of modern elite sport is diminished. In this radical and provocative critique of current anti-doping policy and practice, Verner Møller argues that the fight against doping – promoted as an initiative to cleanse sport of cheats...... – is at heart nothing less than a battle to save sport from itself, located on the fault-line between the will to purity and the will to win. Drawing on extensive and detailed case studies of doping in sport, and using a highly original blend of conceptual ideas from philosophy and sociology, Møller strongly...... criticises current anti-doping regimes and challenges our commonly held ideas about the nature of sport and the risks posed by drugs to health and fair play. He argues forcefully that we must understand the precarious position of the athlete and that only by containing coaches, doctors and drug companies...

  5. Facile hydrothermal preparation of recyclable S-doped graphene sponge for Cu{sup 2+} adsorption

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Lianqin; Yu, Baowei [College of Chemistry and Environment Protection Engineering, Southwest University for Nationalities, Chengdu 610041 (China); Xue, Fumin [Shandong Provincial Analysis and Tester Center, Shandong Academy of Science, Jinan 250014 (China); Xie, Jingru; Zhang, Xiaoliang; Wu, Ruihan; Wang, Ruijue; Hu, Zhiyan [College of Chemistry and Environment Protection Engineering, Southwest University for Nationalities, Chengdu 610041 (China); Yang, Sheng-Tao, E-mail: yangst@pku.edu.cn [College of Chemistry and Environment Protection Engineering, Southwest University for Nationalities, Chengdu 610041 (China); Luo, Jianbin, E-mail: luojb1971@163.com [College of Chemistry and Environment Protection Engineering, Southwest University for Nationalities, Chengdu 610041 (China)

    2015-04-09

    Graphical abstract: S-doped graphene sponge was prepared via hydrothermal treatment, where S-doped graphene sponge had an adsorption capacity of 228 mg/g for Cu{sup 2+}. - Highlights: • S-doped graphene sponge was prepared by hydrothermal treatment for heavy metal adsorption. • S-doped graphene sponge had a huge adsorption capacity for Cu{sup 2+}, which was 40 times higher than that of active carbon. • S-doped graphene sponge could be easily regenerated by washing with acidic thiourea. - Abstract: Graphene sponge (GS) has been widely employed for water purification, but adsorption capacity loss frequently occurs during the formation of spongy structure. In this study, we reported the hydrothermal preparation of S-doped GS for the removal of Cu{sup 2+} with a huge adsorption capacity of 228 mg/g, 40 times higher than that of active carbon. The adsorption isotherm could be well fitted into the Freundlich model with a K{sub F} value of 36.309 (L/mg){sup 1/n}. The equilibrium adsorption could be fully achieved in the first 5 min. In the thermodynamics study, the negative ΔG indicated that the adsorption was spontaneous and physisorption in nature. The positive ΔH implied that the adsorption was endothermic. The changes of both pH and ionic strength had no apparent influence on the adsorption. S-doped GS could be easily regenerated by washing with acidic thiourea. Moreover, S-doped GS could be used for the adsorption of other heavy metal ions, too. The implication to the applications of S-doped GS in water treatment is discussed.

  6. Glycolic acid modulates the mechanical property and degradation of poly(glycerol, sebacate, glycolic acid).

    Science.gov (United States)

    Sun, Zhi-Jie; Wu, Lan; Huang, Wei; Chen, Chang; Chen, Yan; Lu, Xi-Li; Zhang, Xiao-Lan; Yang, Bao-Feng; Dong, De-Li

    2010-01-01

    The development of biodegradable materials with controllable degradation properties is beneficial for a variety of applications. Poly(glycerol-sebacate) (PGS) is a promising candidate of biomaterials; so we synthesize a series of poly(glycerol, sebacate, glycolic acid) (PGSG) with 1:2:0, 1:2:0.2, 1:2:0.4, 1:2:0.6, 1:2:1 mole ratio of glycerol, sebacate, and glycolic acid to elucidate the relation of doped glycolic acid to the degradation rate and mechanical properties. The microstructures of the polymers with different doping of glycolic acid were dissimilar. PGSG with glycolic acid in the ratio of 0.2 displayed an integral degree of ordering, different to those with glycolic acid in the ratio of 0, 0.4, 0.6, and 1, which showed mild phase separation structure. The number, DeltaH(m), and temperature of the PGSG melting peaks tended to decrease with the increasing ratio of doped glycolic acid. In vitro and in vivo degradation tests showed that the degradation rate of PGSG with glycolic acid in the ratio of 0.2 was slowest, but in the ratio range of 0, 0.4, and 0.6, the degradation rate increased with the increase of glycolic acid. All PGSG samples displayed good tissue response and anticoagulant effects. Our data suggest that doping glycolic acid can modulate the microstructure and degree of crosslinking of PGS, thereby control the degradation rate of PGS.

  7. Hybrid proton-conducting membranes for polymer electrolyte fuel cells. Phosphomolybdic acid doped poly(2,5-benzimidazole) - (ABPBI-H{sub 3}PMo{sub 12}O{sub 40})

    Energy Technology Data Exchange (ETDEWEB)

    Gomez-Romero, Pedro [Institut de Ciencia de Materials de Barcelona (CSIC), Campus UAB, E-08193 Bellaterra (Barcelona) (Spain); Asensio, Juan Antonio [Institut de Ciencia de Materials de Barcelona (CSIC), Campus UAB, E-08193 Bellaterra (Barcelona) (Spain); Institut Quimic de Sarria, Universitat Ramon Llull, Via Augusta 390, E-08017 Barcelona (Spain); Borros, Salvador [Institut Quimic de Sarria, Universitat Ramon Llull, Via Augusta 390, E-08017 Barcelona (Spain)

    2005-08-30

    The synthesis and characterization of a novel hybrid organic-inorganic material formed by phosphomolybdic acid H{sub 3}PMo{sub 12}O{sub 40} (PMo{sub 12}) and poly(2,5-benzimidazole) (ABPBI) is reported. This material, composed of two proton-conducting components, can be cast in the form of membranes from methanesulfonic acid (MSA) solutions. Upon impregnation with phosphoric acid, the hybrid membranes present higher conductivity than the best ABPBI polymer membranes impregnated in the same conditions. These electrolyte membranes are proposed. (author). An equivalproton conductivity of 3 x 10{sup -2} S cm{sup -1} at 185 C without humidification. These properties make them very good candidates as membranes for polymer electrolyte membrane fuel cells (PEMFC) at temperatures of 100-200 C. (author)

  8. Preparation of Fe Doped SiO2/TiO2 Photocatalytic Material Response to Visible Light and Degradation of Humic Acid in Water%可见光响应型Fe掺杂SiO2/TiO2光催化材料的制备及降解水中腐殖酸的研究

    Institute of Scientific and Technical Information of China (English)

    王韵芳; 樊彩梅; 孙彦平

    2011-01-01

    Photocatalytic material of SiO2/TiO2 doped with Fe responded to visible light was prepared by solgel process and characterized using TG-DTA, XRD, UV-vis, TEM and XPS analysis methods in detail. The degradation of humic acid in water was chosen as a probe reaction to study the photocatalytic activity of FeSiO2/TiO2 under visible light irradiation. XRD results showed that Fe doping inhibited the catalyst grain size,with Fe-SiO2/TiO2 remaining in the anatase phase at 600 ℃. UV-Vis absorption spectra clearly indicated that Fe doping enhanced the visible hght absorption ability of the catalyst and resulted in a red shift of the absorption edge. XPS spectra indicated that Fe2+ and Fe3+ were existed on catalyst surface. Experimental results showed that the photocatalytic degradation rate of HA of Fe-SiO2/TiO2 sample was better than that of SiO2/TiO2 and TiO2 under visible light irradiation. The main reasons for high photocatalytic activity of FeSiO2/TiO2 may be reduce of grain size, the enhance of visible absorption strength, and existent of circular electronic Fe3+/Fe2+ in favor of separation the e-h+ pairs by doping Fe ion.%采用溶胶凝胶法制备了可见光响应型Fe掺杂SiO2/TiO2光催化材料,并采用TG-DTA、XRD、UV-vis、TEM及XPS等手段对其进行了表征.以水中腐殖酸的降解为探针反应,考察了可见光照射下Fe-SiO2/TiO2的光催化活性.XRD结果表明,Fe离子掺杂可抑制催化剂晶粒尺寸,600℃焙烧后的Fe-SiO2/TiO2为锐钛矿相结构.Ur-vis吸收光谱分析可看出Fe离子掺杂提高了催化剂对可见光的吸收能力,并使催化剂的吸收带边产生了红移.XPS光谱表明,催化剂表面存在着Fe2+和Fe3+.实验结果表明,Fe-SiO2/TiO2在可见光下对腐殖酸的光催化降解率优于SiO2/TiO2和TiO2.Fe-SiO2/TiO2具有较高光催化活性的主要原因为:Fe离子掺杂不仅使SiO2/TiO2催化剂的粒径减小和对可见光的吸收增强,而且在催化剂表面产生了有利

  9. Color stable manganese-doped phosphors

    Science.gov (United States)

    Lyons, Robert Joseph [Burnt Hills, NY; Setlur, Anant Achyut [Niskayuna, NY; Deshpande, Anirudha Rajendra [Twinsburg, OH; Grigorov, Ljudmil Slavchev [Sofia, BG

    2012-08-28

    A process for preparing color stable Mn.sup.+4 doped phosphors includes providing a phosphor of formula I; A.sub.x[MF.sub.y]:Mn.sup.+4 I and contacting the phosphor in particulate form with a saturated solution of a composition of formula II in aqueous hydrofluoric acid; A.sub.x[MF.sub.y]; II wherein A is Li, Na, K, Rb, Cs, NR.sub.4 or a combination thereof; M is Si, Ge, Sn, Ti, Zr, Al, Ga, In, Sc, Y, La, Nb, Ta, Bi, Gd, or a combination thereof; R is H, lower alkyl, or a combination thereof; x is the absolute value of the charge of the [MF.sub.y] ion; and y is 5, 6 or 7. In particular embodiments, M is Si, Ge, Sn, Ti, Zr, or a combination thereof. A lighting apparatus capable of emitting white light includes a semiconductor light source; and a phosphor composition radiationally coupled to the light source, and which includes a color stable Mn.sup.+4 doped phosphor.

  10. Genetic Doping and Health Damages

    Directory of Open Access Journals (Sweden)

    AA Fallahi Fallahi

    2011-03-01

    Full Text Available "nBackground: Use of genetic doping or gene transfer technology will be the newest and the lethal method of doping in fu­ture and have some unpleasant consequences for sports, athletes, and outcomes of competitions. The World Anti-Doping Agency (WADA defines genetic doping as "the non-therapeutic use of genes, genetic elements, and/or cells that have the capac­ity to enhance athletic performance". The purpose of this review is to consider genetic doping, health damages and risks of new genes if delivered in athletes."nMethods: This review, which is carried out by reviewing relevant publications, is primarily based on the journals available in GOOGLE, ELSEVIER, PUBMED in fields of genetic technology, and health using a combination of keywords (e.g., ge­netic doping, genes, exercise, performance, athletes until July 2010."nConclusion: There are several genes related to sport performance and if they are used, they will have health risks and sever dam­ages such as cancer, autoimmunization, and heart attack.

  11. Physically Cross-linked Polymer Binder Induced by Reversible Acid-Base Interaction for High-Performance Silicon Composite Anodes.

    Science.gov (United States)

    Lim, Sanghyun; Chu, Hodong; Lee, Kukjoo; Yim, Taeeun; Kim, Young-Jun; Mun, Junyoung; Kim, Tae-Hyun

    2015-10-28

    Silicon is greatly promising for high-capacity anode materials in lithium-ion batteries (LIBs) due to their exceptionally high theoretical capacity. However, it has a big challenge of severe volume changes during charge and discharge, resulting in substantial deterioration of the electrode and restricting its practical application. This conflict requires a novel binder system enabling reliable cyclability to hold silicon particles without severe disintegration of the electrode. Here, a physically cross-linked polymer binder induced by reversible acid-base interaction is reported for high performance silicon-anodes. Chemical cross-linking of polymer binders, mainly based on acidic polymers including poly(acrylic acid) (PAA), have been suggested as effective ways to accommodate the volume expansion of Si-based electrodes. Unlike the common chemical cross-linking, which causes a gradual and nonreversible fracturing of the cross-linked network, a physically cross-linked binder based on PAA-PBI (poly(benzimidazole)) efficiently holds the Si particles even after the large volume changes due to its ability to reversibly reconstruct ionic bonds. The PBI-containing binder, PAA-PBI-2, exhibited large capacity (1376.7 mAh g(-1)), high Coulombic efficiency (99.1%) and excellent cyclability (751.0 mAh g(-1) after 100 cycles). This simple yet efficient method is promising to solve the failures relating with pulverization and isolation from the severe volume changes of the Si electrode, and advance the realization of high-capacity LIBs.

  12. Structural, optical, magnetic and photocatalytic properties of Co doped CuS diluted magnetic semiconductor nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Sreelekha, N.; Subramanyam, K. [Department of Physics, Sri Venkateswara University, Tirupati 517502 (India); Department of Physics, Raghu Engineering College, Visakhapatnam, Andrapradesh 531162 (India); Amaranatha Reddy, D. [Department of Chemistry and Chemical Institute for Functional Materials, Pusan National University, Busan 609735 (Korea, Republic of); Murali, G. [Department of BIN Fusion Technology & Department of Polymer-Nano Science and Technology, Chonbuk National University, Jeonju, Jeonbuk (Korea, Republic of); Ramu, S. [Department of Physics, Sri Venkateswara University, Tirupati 517502 (India); Rahul Varma, K. [Department of Mechanical Engineering, University of California, Berkeley (United States); Vijayalakshmi, R.P., E-mail: vijayaraguru@gmail.com [Department of Physics, Sri Venkateswara University, Tirupati 517502 (India)

    2016-08-15

    Highlights: • Cu{sub 1−x}Co{sub x}S nanoparticles were synthesized via chemical co-precipitation method. • Structural, band gap, magnetization and photocatalysis studies were carried out. • All the doped samples exhibited intrinsic room temperature ferromagnetism. • Effect of magnetic properties on photocatalytic activity was analyzed. • CuS:Co nanoparticles may find applications in photocatalytic and spintronic devices. - Abstract: Pristine and Co doped covellite CuS nanoparticles were synthesized in aqueous solution by facile chemical co-precipitation method with Ethylene Diamine Tetra Acetic Acid (EDTA) as a stabilizing agent. EDAX measurements confirmed the presence of Co in the CuS host lattice. Hexagonal crystal structure of pure and Co doped CuS nanoparticles were authenticated by XRD patterns. TEM images indicated that sphere-shape of nanoparticles through a size ranging from 5 to 8 nm. The optical absorption edge moved to higher energies with increase in Co concentration as indicated by UV–vis spectroscopy. Magnetic measurements revealed that bare CuS sample show sign of diamagnetic character where as in Co doped nanoparticles augmentation of room temperature ferromagnetism was observed with increasing doping precursor concentrations. Photocatalytic performance of the pure and Co doped CuS nanoparticles were assessed by evaluating the degradation rate of rhodamine B solution under sun light irradiation. The 5% Co doped CuS nanoparticles provide evidence for high-quality photocatalytic activity.

  13. XPS analysis of boron doped heterofullerenes

    Energy Technology Data Exchange (ETDEWEB)

    Schnyder, B.; Koetz, R. [Paul Scherrer Inst. (PSI), Villigen (Switzerland); Muhr, H.J.; Nesper, R. [ETH Zurich, Zurich (Switzerland)

    1997-06-01

    Boron heterofullerenes were generated through arc-evaporation of doped graphite rods in a helium atmosphere. According to mass spectrometric analysis only mono-substituted fullerenes like C{sub 59}B, C{sub 69}B and higher homologues together with a large fraction of higher undoped fullerenes were extracted and enriched when pyridine was used as the solvent. XPS analysis of the extracts indicated the presence of two boron species with significantly different binding energies. One peak was assigned to borid acid. The second one corresponds to boron in the fullerene cage, which is mainly C{sub 59}B, according to the mass spectrum. This boron is in a somewhat higher oxidation state than that of ordinary boron-carbon compounds. The reported synthesis and extraction procedure opens a viable route for production of macroscopic amounts of these compounds. (author) 2 figs., 1 tab., 7 refs.

  14. High deuteron polarization in trityl radical doped deuterated polystyrene

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Li, E-mail: wang_li@dhu.edu.cn [Institut für Experimentalpysik I, Ruhr-Universität Bochum, 44780 Bochum (Germany); Physics Department, School of Science, Donghua University, Shanghai 200051 (China); Berlin, A. [Institut für Experimentalpysik I, Ruhr-Universität Bochum, 44780 Bochum (Germany); Doshita, N. [Physics Department, Faculty of Science, Yamagata University, Yamagata 990-8560 (Japan); Herick, J.; Hess, C. [Institut für Experimentalpysik I, Ruhr-Universität Bochum, 44780 Bochum (Germany); Iwata, T.; Kondo, K. [Physics Department, Faculty of Science, Yamagata University, Yamagata 990-8560 (Japan); Meyer, W.; Reicherz, G. [Institut für Experimentalpysik I, Ruhr-Universität Bochum, 44780 Bochum (Germany)

    2013-11-21

    Deuterated polystyrene for polarized solid targets has been prepared by chemical doping with the trityl radical ‘Finland D36’ (AH 110 355 deutero acid form). Thin foils doped with various radical densities have been produced using tetrahydrofuran as solvent. Dynamic nuclear polarization technique has been applied to polarize deuterons in the samples (98%-D) at the temperature range of about 1 K and magnetic fields of 2.5 T and 5.0 T. A maximum deuteron polarization of −61.5% with a build-up time of 100 min has been achieved at 5.0 T and about 500 mK at a radical density of 1.16×10{sup 19} spins/g. -- Highlights: •Deuterated polystyrene has been prepared by chemical doping with the trityl radical. •Thin foils doped with various radical densities have been produced. •Deuterons are polarized in the samples (98%-D) at about 1 K and 2.5 T and 5.0 T. •Maximum D-polarization of −61.5% with a T{sub bu} of 100 min has been achieved.

  15. Influence of cysteine doping on photoluminescence intensity from semiconducting single-walled carbon nanotubes

    Science.gov (United States)

    Kurnosov, N. V.; Leontiev, V. S.; Linnik, A. S.; Karachevtsev, V. A.

    2015-03-01

    Photoluminescence (PL) from semiconducting single-walled carbon nanotubes can be applied for detection of cysteine. It is shown that cysteine doping (from 10-8 to 10-3 M) into aqueous suspension of nanotubes with adsorbed DNA leads to increase of PL intensity. The PL intensity was enhanced by 27% at 10-3 M cysteine concentration in suspension. Most likely, the PL intensity increases due to the passivation of p-defects on the nanotube by the cysteine containing reactive thiol group. The effect of doping with other amino acids without this group (methionine, serine, aspartic acid, lysine, proline) on the PL intensity is essentially weaker.

  16. Nickel-doped ceria nanoparticles for promoting catalytic activity of Pt/C for ethanol electrooxidation

    Science.gov (United States)

    Tan, Qiang; Du, Chunyu; Sun, Yongrong; Du, Lei; Yin, Geping; Gao, Yunzhi

    2014-10-01

    This paper reports the facile synthesis of monodispersed nickel-doped ceria nanoparticles by a thermal decomposition method, which is used to promote catalytic properties of Pt/C. The Pt/Ni-doped CeO2/C catalyst obtained exhibits remarkably high activity and stability towards the ethanol electrooxidation in acidic media. This is attributed to higher oxygen releasing capacity and stronger interaction of Ni-doped CeO2 with Pt than pure CeO2 nanoparticles that contribute positively to the removal of poisoning intermediates. We believe that the design concept and synthetic strategy of metal doped oxides used for fuel cell catalysts can be potentially extended to other catalytic fields.

  17. U.S. Anti-Doping Agency

    Science.gov (United States)

    ... 7, 2016 View All News Releases Our Anti-Doping Programs What does USADA do? What elements make ... symposium topic. More Information Spirit of Sport – Anti-Doping News USADA’s Spirit of Sport news hub contains ...

  18. Cu-Doped-CdS/In-Doped-CdS Cosensitized Quantum Dot Solar Cells

    Directory of Open Access Journals (Sweden)

    Lin Li

    2014-01-01

    Full Text Available Cu-doped-CdS and In-doped-CdS cosensitized (Cu-doped-CdS/In-doped-CdS quantum dot solar cells (QDSCs are introduced here. Different cosensitized sequences, doping ratios, and the thickness (SILAR cycles of Cu-doped-CdS and In-doped-CdS are discussed. Compared with undoped CdS QDSCs, the short circuit current density, UV-Vis absorption spectra, IPCE (monochromatic incident photon-to-electron conversion, open circuit voltage, and so on are all improved. The photoelectric conversion efficiency has obviously improved from 0.71% to 1.28%.

  19. Doping and thrombosis in sports.

    Science.gov (United States)

    Lippi, Giuseppe; Banfi, Giuseppe

    2011-11-01

    Historically, humans have long sought to enhance their "athletic" performance to increase body weight, aggressiveness, mental concentration and physical strength, contextually reducing fatigue, pain, and improving recovery. Although regular training is the mainstay for achieving these targets, the ancillary use of ergogenic aids has become commonplace in all sports. The demarcation between ergogenic aids and doping substances or practices is continuously challenging and mostly based on perceptions regarding the corruption of the fairness of competition and the potential side effects or adverse events arising from the use of otherwise unnecessary ergogenic substances. A kaleidoscope of side effects has been associated with the use of doping agents, including behavioral, skeletal, endocrinologic, metabolic, hemodynamic, and cardiovascular imbalances. Among the various doping substances, the most striking association with thrombotic complications has been reported for androgenic anabolic steroids (i.e., cardiomyopathy, fatal and nonfatal arrhythmias, myocardial infarction [MI], intracardiac thrombosis, stroke, venous thromboembolism [VTE], limb arterial thrombosis, branch retinal vein occlusion, cerebral venous sinus thrombosis) and blood boosting (i.e., VTE and MI, especially for epoetin and analogs). The potential thrombotic complication arising from misuse of other doping agents such as the administration of cortisol, growth hormone, prolactin, cocaine, and platelet-derived preparations is instead speculative or anecdotal at best. The present article provides an overview on the epidemiological association as well as the underlying biochemical and biological mechanisms linking the practice of doping in sports with the development of thrombosis.

  20. Enhancing charge storage of conjugated polymer electrodes with phenolic acids

    Science.gov (United States)

    Wagner, Michal; Rębiś, Tomasz; Inganäs, Olle

    2016-01-01

    We here present studies of electrochemical doping of poly(1-aminoanthraquinone) (PAAQ) films with three structurally different phenolic acids. The examined phenolic acids (sinapic, ferulic and syringic acid) were selected due to their resemblance to redox active groups, which can be found in lignin. The outstanding electrochemical stability of PAAQ films synthesized for this work enabled extensive cycling of phenolic acid-doped PAAQ films. Potentiodynamic and charge-discharge studies revealed that phenolic acid-doped PAAQ films exhibited enhanced capacitance in comparison to undoped PAAQ films, together with appearance of redox activity characteristics specific for each dopant. Electrochemical kinetic studies performed on microelectrodes affirmed the fast electron transfer for hydroquinone-to-quinone reactions with these phenolic compounds. These results imply the potential application of phenolic acids in cheap and degradable energy storage devices.

  1. Progress on erbium-doped waveguide components

    DEFF Research Database (Denmark)

    Bjarklev, Anders Overgaard; Berendt, Martin Ole; Broeng, Jes;

    1997-01-01

    The recent development in erbium-doped fiber amplifiers, and fiber lasers is reviewed. Also the latest results on planar erbium-doped waveguide amplifiers and high erbium concentration characterisation methods are presented......The recent development in erbium-doped fiber amplifiers, and fiber lasers is reviewed. Also the latest results on planar erbium-doped waveguide amplifiers and high erbium concentration characterisation methods are presented...

  2. Aspartic acid

    Science.gov (United States)

    Aspartic acid is a nonessential amino acids . Amino acids are building blocks of proteins. "Nonessential" means that our ... this amino acid from the food we eat. Aspartic acid is also called asparaginic acid. Aspartic acid helps ...

  3. Development of Doped Lanthanum Gallate Solid Electrolytes

    Institute of Scientific and Technical Information of China (English)

    蒋凯; 王海霞; 郑立庆; 杨林; 孟健; 苏锵

    2003-01-01

    Development of the doped lanthanum gallate solid electrolytes in the recent years was reviewed. The structure and oxygen ion transference mechanism were discussed. Effects of alkali earths, transition metals, and impurities on electrical conductivity of the doped lanthanum gallates were also discussed. The applications of doped lanthanum gallate were described. The current problems and corresponding strategies were explored.

  4. A Quarter Century of Doping Scandals

    DEFF Research Database (Denmark)

    Gleaves, John; Christiansen, Ask Vest

    2013-01-01

    With the ongoing doping scandals, revelations, and confessions, it was likely that few celebrated this autumn’s significant anniversary in doping history. Twenty-five years ago—September 26, 1988—news broke of the first major doping scandal in the Olympic Games. Canadian sprinter Ben Johnson, who...

  5. Nitrogen-doped hydrothermal carbons

    Energy Technology Data Exchange (ETDEWEB)

    Titirici, Maria-Magdalena; White, Robin J. [Max-Planck-Institute of Colloids and Interfaces, Potsdam (Germany). Dept. of Colloid Chemistry; Zhao, Li [Max-Planck-Institute of Colloids and Interfaces, Potsdam (Germany). Dept. of Colloid Chemistry; National Center for Nanoscience and Technology, Beijing (China)

    2012-07-01

    Nitrogen doped carbon materials are now playing an important role in cutting edge innovations for energy conversion and storage technologies such as supercapacitors and proton exchange membrane fuel cells as well as in catalytic applications, adsorption and CO{sub 2} capture. The production of such materials using benign aqueous based processes, mild temperatures and renewable precursors is of great promise in addressing growing environmental concerns for cleaner power sources at a time of increasing global demand for energy. In this perspective, we show that nitrogen doped carbons prepared using sustainable processes such as ''Hydrothermal Carbonisation'' has advantages in many applications over the conventional carbons. We also summarize an array of synthetic strategies used to create such nitrogen doped carbons, and discuss the application of these novel materials. (orig.)

  6. Effect of Magnetite Nano Particles on p-n-Alkyl Benzoic Acid Mesogens

    Directory of Open Access Journals (Sweden)

    S. Sreehari Sastry

    2012-01-01

    Full Text Available The magnetite (Fe3O4 nanoparticles (0.5 wt% of size less than 20 nm doped in p-n-alkyl benzoic acids where n varies from heptyl (7 to nonyl (9 are prepared and the presence of Fe+3 is confirmed through UV-Visible spectrophotometer. Textural and phase transition temperature studies are carried out using polarizing optical microscopy on pure and nano doped p-n-alkyl benzoic acids. These results are further confirmed by DSC at a scan rate of 5ºC/min and dielectric studies. Dielectric studies are carried out, in which the variation of dielectric constant, loss and the conductivity are analyzed with respect to temperatures and frequencies. Increment of relaxation times for nano doped heptyl and nonyl benzoic acids are observed which implies that the dielectric nature is strengthened for the nano doped mesogens. The preference of nano doped p-n-alkyl benzoic acids is discussed.

  7. Ce-MCM-41分子筛用于臭氧氧化对氯苯甲酸的活性评价%Synthesis of cerium-doped MCM-41 for ozonation of p-chlorobenzoic acid

    Institute of Scientific and Technical Information of China (English)

    邴吉帅; 曾俊喻; 廖高祖; 李旭凯; 蓝冰燕; 张秋云; 李来胜

    2012-01-01

    Cerium-doped MCM-41(Ce-MCM-41) was prepared by a hydrothermal method and its catalytic activity for ozonation of p-chlorobenzoic acid(p-CBA) in aqueous solution was studied.Ce-MCM-41 was characterized by low angle X-ray powder diffraction(XRD),nitrogen adsorption-desorption(BET),ultraviolet-visible diffuse reflection spectrum(UV-Vis DRS) and transmission electron microscopy(TEM).The results showed that the material retained a highly ordered mesopore structure of pure silica MCM-41 and had a high surface area.Cerium was incorporated into the framework of MCM-41,locating at tetrahedrally coordinated sites.Ce-MCM-41 significantly improved the effect of ozone oxidation.After 60 min reaction time,TOC removal rate was 63% with MCM-41,86% with Ce-MCM-41(Si/Ce=60),while only 52% with O3 alone.Besides,Ce-MCM-41 had much less cerium leaching(0.085 mg·L-1) compared with that of Ce/MCM-41(0.44 mg·L-1).After being used for three times,TOC removal rate decreased only by 5%,while p-CBA removal rate kept nearly constant.Ce-MCM-41 is a promising catalyst for ozonation process.%通过水热法合成了铈掺杂MCM-41(Ce-MCM-41)介孔分子筛,并将其用于臭氧氧化水中对氯苯甲酸(p-CBA).小角X射线衍射(XRD)、氮气吸附-脱附(BET)、紫外可见漫反射光谱(UV-Vis DRS)、透射电镜(TEM)表征结果表明,铈成功进入MCM-41分子筛骨架,以正四面体形式存在,且Ce-MCM-41保持了纯硅MCM-41有序的介孔结构,具有较高的比表面积;铈的掺杂显著提高MCM-41催化臭氧氧化对氯苯甲酸的活性,反应60 min后,TOC去除率由MCM-41的63%提高到86%(Si/Ce=60),而单独臭氧氧化仅为52%;铈的溶出仅为0.085 mg.L-1,较同样负载量的铈负载Ce/MCM-41的溶出(0.44 mg.L-1)有较大减少.催化剂重复使用3次后仍保持较高的活性,这表明Ce-MCM-41具有较好的活性和稳定性,是一种有前景的臭氧氧化催化剂.

  8. Extrinsic doping in silicon revisited

    Energy Technology Data Exchange (ETDEWEB)

    Schwingenschloegl, Udo [PSE Division, KAUST, Thuwal, Kingdom of Saudi Arabia (Saudi Arabia); Chroneos, Alexander; Grimes, Robin [Department of Materials, Imperial College London, London SW7 2BP (United Kingdom); Schuster, Cosima [Institut fuer Physik, Universitaet Augsburg, 86135 Augsburg (Germany)

    2011-07-01

    Both n-type and p-type doping of silicon is at odds with the charge transfer predicted by Pauling electronegativities and can only be reconciled if we no longer regard dopant species as isolated atoms but rather consider them as clusters consisting of the dopant and its four nearest neighbor silicon atoms. The process that gives rise to n-type and p-type effects is the charge redistribution that occurs between the dopant and its neighbors, as we illustrate here using electronic structure calculations. This view point is able to explain why conventional substitutional n-type doping of carbon has been so difficult.

  9. Extrinsic doping in silicon revisited

    KAUST Repository

    Schwingenschlögl, Udo

    2010-06-17

    Both n-type and p-type doping of silicon is at odds with the charge transfer predicted by Pauling electronegativities and can only be reconciled if we no longer regarding dopant species as isolated atoms but rather consider them as clusters consisting of the dopant and its four nearest neighbor silicon atoms. The process that gives rise to n-type and p-type effects is the charge redistribution that occurs between the dopant and its neighbors, as we illustrate here using electronic structure calculations. This view point is able to explain why conventional substitutional n-type doping of carbon has been so difficult.

  10. Electronegativity and doping in semiconductors

    KAUST Repository

    Schwingenschlögl, Udo

    2012-08-23

    Charge transfer predicted by standard models is at odds with Pauling’s electronegativities but can be reconciled by the introduction of a cluster formation model [Schwingenschlögl et al., Appl. Phys. Lett. 96, 242107 (2010)]. Using electronic structure calculations, we investigate p- and n-type doping in silicon and diamond in order to facilitate comparison as C has a higher electronegativity compared to Si. All doping conditions considered can be explained in the framework of the cluster formation model. The implications for codoping strategies and dopant-defect interactions are discussed.

  11. Method of doping a semiconductor

    Science.gov (United States)

    Yang, Chiang Y.; Rapp, Robert A.

    1983-01-01

    A method for doping semiconductor material. An interface is established between a solid electrolyte and a semiconductor to be doped. The electrolyte is chosen to be an ionic conductor of the selected impurity and the semiconductor material and electrolyte are jointly chosen so that any compound formed from the impurity and the semiconductor will have a free energy no lower than the electrolyte. A potential is then established across the interface so as to allow the impurity ions to diffuse into the semiconductor. In one embodiment the semiconductor and electrolyte may be heated so as to increase the diffusion coefficient.

  12. Controlled doping by self-assembled dendrimer-like macromolecules

    Science.gov (United States)

    Wu, Haigang; Guan, Bin; Sun, Yingri; Zhu, Yiping; Dan, Yaping

    2017-02-01

    Doping via self-assembled macromolecules might offer a solution for developing single atom electronics by precisely placing individual dopants at arbitrary location to meet the requirement for circuit design. Here we synthesize dendrimer-like polyglycerol macromolecules with each carrying one phosphorus atom in the core. The macromolecules are immobilized by the coupling reagent onto silicon surfaces that are pre-modified with a monolayer of undecylenic acid. Nuclear magnetic resonance (NMR) and X-ray photoelectron spectroscopy (XPS) are employed to characterize the synthesized macromolecules and the modified silicon surfaces, respectively. After rapid thermal annealing, the phosphorus atoms carried by the macromolecules diffuse into the silicon substrate, forming dopants at a concentration of 1017 cm‑3. Low-temperature Hall effect measurements reveal that the ionization process is rather complicated. Unlike the widely reported simple ionization of phosphorus dopants, nitrogen and carbon are also involved in the electronic activities in the monolayer doped silicon.

  13. Secondary doping in polyaniline layers coated on multi-walled carbon nanotubes

    Directory of Open Access Journals (Sweden)

    Zhou Yi

    2015-01-01

    Full Text Available HC1 doped coaxial polyaniline/multiwalled carbon nanotubes (MWCNTs nanocomposites were first prepared by in–situ chemical polymerization of aniline monomers in the presence of MWCNTs with less structural defects. P-toluene sulfonic acid (TSA and 5-sulfosalicylic acid dihydrate (SSA redoped PANI/MWCNT nanocomposites were achieved after the as-prepared nanocomposites were treated by ammonia respectively. The redoped nanocomposites were characterized by field emission scanning electron microscopy, transmission electron microscopy, fourier transform infrared spectroscopy, Raman, X–ray diffraction, thermogravimetric analysis and cyclic voltammetry, respectively. The results indicated that the thermal stability and electrochemical behaviour of TSA doped PANI/MWCNT nanocomposites were better than that of SSA doped PANI/MWCNT nanocomposites.

  14. Sn-doped hydroxylated MgF₂ catalysts for the fast and selective saccharification of cellulose to glucose.

    Science.gov (United States)

    Wuttke, Stefan; Negoi, Alina; Gheorghe, Nicoleta; Kuncser, Victor; Kemnitz, Erhard; Parvulescu, Vasile; Coman, Simona M

    2012-09-01

    TIN, TAILORED, NOT SOLDER, BUT CAT: Doped hydroxylated fluorides, prepared by a modified sol-gel method, offer enhanced acidity and improved stability against water, and efficiency in the degradation of cellulose. These materials extend the portfolio of acid catalysts for fast and selective hydrolysis of biomass to glucose, which offers a feedstock for bioethanol production.

  15. New electrocatalyst support for high temperature PEM fuel cells (HT-PEMFC)

    Energy Technology Data Exchange (ETDEWEB)

    Boaventura, M.; Brandao, L.; Mendes, A. [Porto Univ. (PT). Lab. de Engenharia de Processos, Ambiente e Energia (LEPAE)

    2010-07-01

    This work compares the performance of electrocatalysts based on platinum supported in single-wall carbon nanohorns (Pt-SWNH) and supported in carbon black (Pt-carbon black) during high temperature PEM fuel operation. MEAs made of phosphoric acid doped polybenzimidazole (PBI/H{sub 3}PO{sub 4}) were characterized by polarization curves, electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV), at 160 C. The Pt-SWNH electrocatalyst presented a higher electrochemical surface area (ESA) when compared to Pt-carbon black. However, electrochemical experiments showed a higher ohmic resistance of the Pt-SWNH electrode related to a higher hydrophobic character of the SWNH carbon. (orig.)

  16. High temperature polymer electrolyte membrane fuel cells

    DEFF Research Database (Denmark)

    This book is a comprehensive review of high-temperature polymer electrolyte membrane fuel cells (PEMFCs). PEMFCs are the preferred fuel cells for a variety of applications such as automobiles, cogeneration of heat and power units, emergency power and portable electronics. The first 5 chapters...... of the book describe rationalization and illustration of approaches to high temperature PEM systems. Chapters 6 - 13 are devoted to fabrication, optimization and characterization of phosphoric acid-doped polybenzimidazole membranes, the very first electrolyte system that has demonstrated the concept...

  17. Oxygen reduction on carbon supported platinum catalysts in high temperature polymer electrolytes

    DEFF Research Database (Denmark)

    Qingfeng, Li; Hjuler, Hans Aage; Bjerrum, Niels

    2000-01-01

    improve the oxygen reduction kinetics due to increased oxygen solubility and suppressed adsorption of phosphoric acid anions. Further enhancement of the catalytic activity can be obtained by operating the polymer electrolytes at higher temperatures. Efforts have been made to develop a polymer electrolyte......Oxygen reduction on carbon supported platinum catalysts has been investigated in H3PO4, H3PO4-doped Nafion and polybenzimidazole (PBI) polymer electrolytes in a temperature range up to 190 degrees C. Compared with pure H3PO4, the combination of H3PO4 and polymer electrolytes can significantly...

  18. Crosslinking of polybenzimidazolemembranes by divinylsulfone post-treatment for high-temperature proton exchange membrane fuel cell applications

    DEFF Research Database (Denmark)

    Aili, David; Li, Qingfeng; Christensen, Erik;

    2011-01-01

    Phosphoric acid-doped polybenzimidazole (PBI) has been suggested as a promising electrolyte for proton exchangemembrane fuel cells operating at temperatures up to 200 ◦C. This paper describes the development of a crosslinking procedure for PBI membranes by post-treatment with divinylsulfone....... The crosslinking chemistry was studied and optimized on a low-molecularweight model system and the results were used to optimize the crosslinking conditions of PBI membranes. The crosslinked membraneswere characterized with respect to chemical and physiochemical properties, showing improved mechanical strength...... and oxidative stability compared with their linear analogues. Fuel cell tests were further conducted in order to demonstrate the feasibility of the crosslinked membranes....

  19. Blue to Yellow Photoluminescence Emission and Photocatalytic Activity of Nitrogen Doping in TiO2 Powders

    Directory of Open Access Journals (Sweden)

    Gabriela Byzynski

    2015-01-01

    Full Text Available The defects caused by doping are important for understanding the increased photocatalytic activities of TiO2:N in organic reactions and in the evaluation of OH radical production after doping. TiO2:N was therefore synthesized using a modified polymeric method and N doping was performed by calcination with urea. The resulting powders were characterized using field emission scanning electron microscopy, X-ray diffraction, diffuse reflectance spectroscopy, Raman spectroscopy, Fourier transformation infrared spectroscopy, and photoluminescence emission spectroscopy (PL. N doping did not alter the morphology of the nanoparticles, and the anatase phase predominated, with the retention of the rutile phase. The band gap values, superficial areas, and crystallite sizes of the powders decreased after doping. The PL results showed an additional energy level in the TiO2:N band gap structure as a result of TiO2 lattice defects caused by doping. At low N contents, the powders showed continuous emissions from the blue region to the yellow region and a high N content shifted the PL emissions to the red region. These results suggest that the use of these powders could increase the efficiencies of solar cells and water-splitting processes. The photocatalytic activity of the powders under UVC illumination was confirmed for different organic dye molecules. The OH radical production did not change extensively after doping, as shown by experiments with terephthalic acid, and higher photocatalytic efficiencies in Rhodamine-B degradation under UVC illumination were achieved using the doped samples.

  20. Photocatalytic Degradation of Dicofol and Pyrethrum with Boric and Cerous Co-doped TiO2 under Light Irradiation

    Institute of Scientific and Technical Information of China (English)

    GONG Lifen; ZOU Jing; ZENG Jinbin; CHEN Wenfeng; CHEN Xi; WANG Xiaoru

    2009-01-01

    Boric and cerous co-doped nano titanium dioxide (B/Ce co-doped TiO2) was synthesized using a sol-gel tech-nique, which involved the hydrolyzation of tetrabutyl titanate with the addition of boric acid and cerous nitrate. The B/Ce co-doped TiO2 was employed for the photocatalytic degradation of dicofol, cyfluthrin and fenvalerate under light irradiation. XRD, TEM, Fr-IR and UV-Vis DRS methods were used to characterize the crystalline structure. Experimental results showed that only the anatase signal phase was found for B/Ce co-doped TiO2, but multiplicate phases, including anatase, rutile and less brookite phases, were identified both in the pure TiO2 nanoparticles and Ce-doped TiO2 nanoparticles. The band gap value of B/Ce co-doped nano TiO2 was narrower than that of undoped nano TiO2. Compared to undoped TiO2, a stronger absorption in the range of 420 to 850 nm was found for B/Ce co-doped nano TiO2, which presented a higher photocatalytic activity in the degradation of dicofol, cyfluthrin and fenvalerate than both Ce doped nano TiO2 and pure nano TiO2 under the same light irradiation.

  1. Electronic Structure of Doped Trans-Polyacetylene

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The behavior of electronic structures of doped trans-polyacetylene is revealed by a simplemethod. (C24H26)+n is used to simulate p-type doped trans-polyacetylene at various doping concentrations.The electronic structure is calculated by CNDO/2 method. These calculations show that at low doping lev-el, the decrease of electronic energy compensates the increase of elastic energy, thus the bond alternationexists, and the charge carriers are solitons. When doping level is high, the increase of elastic energy islarger than the decrease of electronic energy, the bond alternation disappears, solitons no longer exist,and polyacetylene is in a metalic state.

  2. The moral disengagement in doping scale

    DEFF Research Database (Denmark)

    Kavussanu, Maria; Hatzigeorgiadis, Antonis; Elbe, Anne-Marie

    2016-01-01

    from a variety of team sports (N = 398) completed the Moral Disengagement in Doping Scale (MDDS). In Study 2, team sport athletes (N = 232) completed the MDDS and questionnaires measuring moral disengagement in sport, doping attitudes, moral identity, antisocial sport behavior, situational doping......, as well as test-rest reliability, of the scale. In Study 3, doping moral disengagement was positively related with reported likelihood and temptation to use a banned substance. The scale exhibited very good internal consistency across the three studies. Conclusions In conclusion, the MDDS can be used...... to measure moral disengagement in doping in team and individual sports....

  3. Doping silver nanoparticles in AOT lyotropic lamellarphases

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The organic lyotropic liquid crystal with long-range structural order is used as templateto assemble inorganic/organic hybrid by doping pre-fabricated Ag nanoparticles. The lamellar hy-brid with both hydrophilic and hydrophobic particles doped simultaneously is realized for the firsttime. The change of template structure after doping and the stability origin of dual-doped systemare characterized by small angle X-ray scattering and polarized optical microscopy. Results showthat the interaction and space matching between surfactant bilayers and doped particles are

  4. DOPING IN SPORT: GLOBAL ETHICAL ISSUES

    Directory of Open Access Journals (Sweden)

    Angela J. Schneider

    2007-09-01

    Full Text Available DESCRIPTION In this book the question of "How ethical is using performance improving drugs in sport?" is argued in global perspective. PURPOSE The ethical questions in sport are discussed comprehensively. Particularly, different cultures and approach of various countries to that issue were examined. FEATURES The book composed of 10 chapters following a thorough introduction from the editors in 194 pages. The titles are: 1.Fair is Fair, Or Is It? : A Moral Consideration of the Doping Wars in American Sport; 2.Are Doping Sanctions Justified? A Moral Relativistic View; 3.Cultural Nuances: Doping, Cycling and the Tour de France; 4.On Transgendered Athletes, Fairness and Doping: An International Challenge; 5.Creating a Corporate Anti-doping Culture: The Role of Bulgarian Sports Governing Bodies; 6. Doping in the UK: Alain and Dwain, Rio and Greg - Not Guilty?; 7.The Japanese Debate Surrounding the Doping Ban: The Application of the Harm Principle; 8. Doping and Anti-doping in Sport in China: An Analysis of Recent and Present Attitudes and Actions; 9.Anti-doping in Sport: The Norwegian Perspective; 10.Ethics in Sport: The Greek Educational Perspective on Anti-doping. AUDIENCE Given that this book is about a popular topic in sport, it is a great interest to the sport public as well as students, researchers and practitioners in the sport and exercise disciplines.

  5. Method of doping organic semiconductors

    Science.gov (United States)

    Kloc, Christian Leo [Constance, DE; Ramirez, Arthur Penn [Summit, NJ; So, Woo-Young [New Providence, NJ

    2012-02-28

    A method includes the steps of forming a contiguous semiconducting region and heating the region. The semiconducting region includes polyaromatic molecules. The heating raises the semiconducting region to a temperature above room temperature. The heating is performed in the presence of a dopant gas and the absence of light to form a doped organic semiconducting region.

  6. Hormones as doping in sports.

    Science.gov (United States)

    Duntas, Leonidas H; Popovic, Vera

    2013-04-01

    Though we may still sing today, as did Pindar in his eighth Olympian Victory Ode, "… of no contest greater than Olympia, Mother of Games, gold-wreathed Olympia…", we must sadly admit that today, besides blatant over-commercialization, there is no more ominous threat to the Olympic games than doping. Drug-use methods are steadily becoming more sophisticated and ever harder to detect, increasingly demanding the use of complex analytical procedures of biotechnology and molecular medicine. Special emphasis is thus given to anabolic androgenic steroids, recombinant growth hormone and erythropoietin as well as to gene doping, the newly developed mode of hormones abuse which, for its detection, necessitates high-tech methodology but also multidisciplinary individual measures incorporating educational and psychological methods. In this Olympic year, the present review offers an update on the current technologically advanced endocrine methods of doping while outlining the latest procedures applied-including both the successes and pitfalls of proteomics and metabolomics-to detect doping while contributing to combating this scourge.

  7. Impurity doping processes in silicon

    CERN Document Server

    Wang, FFY

    1981-01-01

    This book introduces to non-experts several important processes of impurity doping in silicon and goes on to discuss the methods of determination of the concentration of dopants in silicon. The conventional method used is the discussion process, but, since it has been sufficiently covered in many texts, this work describes the double-diffusion method.

  8. Steroid profiling in doping analysis

    NARCIS (Netherlands)

    Kerkhof, Daniël Henri van de

    2002-01-01

    Profiling androgens in urine samples is used in doping analysis for the detection of abused steroids of endogenous origin. These profiling techniques were originally developed for the analysis of testosterone, mostly by means of the ratio of testosterone to epitestosterone (T/E ratio). A study was p

  9. Boron-Doped Diamond Electrodes for the Electrochemical Oxidation and Cleavage of Peptides

    NARCIS (Netherlands)

    Roeser, Julien; Alting, Niels F. A.; Permentier, Hjalmar P.; Bruins, Andries P.; Bischoff, Rainer

    2013-01-01

    Electrochemical oxidation of peptides and proteins is traditionally performed on carbon-based electrodes. Adsorption caused by the affinity of hydrophobic and aromatic amino acids toward these surfaces leads to electrode fouling. We compared the performance of boron-doped diamond (BDD) and glassy ca

  10. Analysis of High-Performance PTSA-DOPED Polyaniline-Speek Nanocomposites

    Science.gov (United States)

    Misra, R. K.; Sandeep, K.; Nigam, V.

    2016-03-01

    The mechanical properties and phase morphology of a nanocomposite plate made from sulphonated poly (ether ether ketone) and p-toluene sulphonic acid-doped polyaniline nanoparticles were investigated. To study the static and dynamic response of the plate to transverse loads, the method of multiquadric radial basis functions is developed. The numerical results obtained are compared with those found by other analytical methods.

  11. Hydrothermal Synthesis of Nitrogen-Doped Titanium Dioxide and Evaluation of Its Visible Light Photocatalytic Activity

    Directory of Open Access Journals (Sweden)

    Junjie Qian

    2012-01-01

    Full Text Available Nitrogen-doped titanium dioxide (N-doped TiO2 photocatalyst was synthesized from nanotube titanic acid (denoted as NTA; molecular formula H2Ti2O5·H2O precursor via a hydrothermal route in ammonia solution. As-synthesized N-doped TiO2 catalysts were characterized by means of X-ray diffraction, transmission electron microscopy, diffuse reflectance spectrometry, X-ray photoelectron spectroscopy, electron spin resonance spectrometry and Fourier transform infrared spectrometry. It was found that nanotube ammonium titanate (NAT was produced as an intermediate during the preparation of N-doped TiO2 from NTA, as evidenced by the N1s X-ray photoelectron spectroscopic peak of NH4 + at 401.7 eV. The catalyst showed much higher activities to the degradation of methylene blue and p-chlorophenol under visible light irradiation than Degussa P25. This could be attributed to the enhanced absorption of N-doped TiO2 in visible light region associated with the formation of single-electron-trapped oxygen vacancies and the inhibition of recombination of photo-generated electron-hole pair by doped nitrogen.

  12. Structural, optical, magnetic and photocatalytic properties of Co doped CuS diluted magnetic semiconductor nanoparticles

    Science.gov (United States)

    Sreelekha, N.; Subramanyam, K.; Amaranatha Reddy, D.; Murali, G.; Ramu, S.; Rahul Varma, K.; Vijayalakshmi, R. P.

    2016-08-01

    Pristine and Co doped covellite CuS nanoparticles were synthesized in aqueous solution by facile chemical co-precipitation method with Ethylene Diamine Tetra Acetic Acid (EDTA) as a stabilizing agent. EDAX measurements confirmed the presence of Co in the CuS host lattice. Hexagonal crystal structure of pure and Co doped CuS nanoparticles were authenticated by XRD patterns. TEM images indicated that sphere-shape of nanoparticles through a size ranging from 5 to 8 nm. The optical absorption edge moved to higher energies with increase in Co concentration as indicated by UV-vis spectroscopy. Magnetic measurements revealed that bare CuS sample show sign of diamagnetic character where as in Co doped nanoparticles augmentation of room temperature ferromagnetism was observed with increasing doping precursor concentrations. Photocatalytic performance of the pure and Co doped CuS nanoparticles were assessed by evaluating the degradation rate of rhodamine B solution under sun light irradiation. The 5% Co doped CuS nanoparticles provide evidence for high-quality photocatalytic activity.

  13. Effect of Ho-doping on photocatalytic activity of nanosized TiO2 catalyst

    Institute of Scientific and Technical Information of China (English)

    CAI Heshan; LIU Guoguang; Lü Wenying; LI Xiaoxia; YU Lin; LI Daguang

    2008-01-01

    Ho-doped TiO2 nanoparticles with higher photocatalytic activity were prepared by an acid-catalyzed sol-gel method. The photocatalytic decomposition of methyl orange in aqueous solution was used as a probe reaction to evaluate their photocatalytic activities. The effects of Ho doping on the crystallite sizes, crystal pattern, surface composition, and optical property of the catalysts were investigated by means of techniques such as X-Ray Diffraction (XRD), Transmission Electron Microscopy (TEM), Diffuse Reflectance UV-Vis Spectroscopy (UV-Vis DRS), Fourier Transform Infrared (FT-IR), and Photo-Luminiscence (PL) spectra. Moreover, the modification mechanism of Ho doping was also discussed. The results showed that Ho doping could inhibit phase transformation from anatase to ruffle, suppress the growth of TiO2 grains, cause blue shift of the absorption spectrum edge, accelerate surface hydroxylation, and enhance the separation efficiency of photoinduced electron-hole pairs, which resulted in a significant improvement in the photoreactivity of Ho-doped TiO2. Among them, the Ho-doped TiO2 calcined at 500 ℃ achieved the highest photocatalytic activity.

  14. Preparation and characterization of Ce-doped HfO{sub 2} nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Gálvez-Barboza, S. [Centro de Investigación en Química Aplicada, Departamento de Materiales Avanzados, Blvd. Enrique Reyna Hermosillo #140, C.P. 25294 Saltillo, Coahuila (Mexico); Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, Av. Industria Metalúrgica # 1062 Parque Industrial, C.P. 25900 Ramos Arizpe, Coahuila (Mexico); González, L.A. [Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, Av. Industria Metalúrgica # 1062 Parque Industrial, C.P. 25900 Ramos Arizpe, Coahuila (Mexico); Puente-Urbina, B.A.; Saucedo-Salazar, E.M. [Centro de Investigación en Química Aplicada, Departamento de Materiales Avanzados, Blvd. Enrique Reyna Hermosillo #140, C.P. 25294 Saltillo, Coahuila (Mexico); García-Cerda, L.A., E-mail: luis.garcia@ciqa.edu.mx [Centro de Investigación en Química Aplicada, Departamento de Materiales Avanzados, Blvd. Enrique Reyna Hermosillo #140, C.P. 25294 Saltillo, Coahuila (Mexico)

    2015-09-15

    Highlights: • Ce-doped HfO{sub 2} nanoparticles were prepared by a modified solgel method. • Ce-doped HfO{sub 2} nanoparticles have a semispherical shape with sizes between 6 and 11.5 nm. • The samples doped with 10% in weight of Ce directly crystallized in a cubic structure. • A quick, straightforward and effective route for the preparation of Ce-doped nanoparticles. - Abstract: A modified solgel method to synthesize Ce-doped HfO{sub 2} nanoparticles was carried out using a precursor material prepared with cerium nitrate, hafnium chloride, citric acid and ethylene glycol. The obtained precursor material was calcined at 500 and 700 °C for 2 h in air. The influence of the concentration of Ce and the calcination temperature was studied to observe the structural and morphological changes of the obtained materials. For the characterization, X-ray diffraction (XRD), transmission electron microscopy (TEM) and Raman scattering (RS) were employed. The XRD patterns shown that the Ce-doped HfO{sub 2} undergoes a structural transformation from monoclinic to cubic phase, which is significantly dependent on the Ce content and calcination temperature. TEM images have also confirmed the existence of semispherical nanoparticles with sizes between 6 and 11.5 nm.

  15. Striking the Right Balance : Effectiveness of Anti-Doping Policies

    NARCIS (Netherlands)

    de Hon, O.M.

    2016-01-01

    Doping, and anti-doping, is in the news on a continuous basis. At the core of these stories and discussions is the question how effective anti-doping policies are to curb the use of doping in sports. Anti-doping policies are based on ethical values, a juridical framework, laboratory analyses, educat

  16. Preparation and characterization of polyaniline microrods synthesized by using dodecylbenzene sulfonic acid and periodic acid

    OpenAIRE

    TAŞ, RECEP; Can, Muzaffer; Sönmezoğlu, Savaş

    2015-01-01

    The preparation of polyaniline (PANI) microrod arrays in the presence of dodecylbenzene sulfonic acid (DBSAH), a structure-directing agent, and in the presence of periodic acid (H$_{5}$IO$_{6})$, an oxidant in aqua-acidic media, was investigated. DBSAH was performed to distinguish the roles of both surfactant and dopant. The method of preparation of DBSAH and H$_{5}$IO$_{6}$ doped PANI (DBSAH-PANI) microrods in a reversed micelle had previously not been reported. The characterizations of the ...

  17. Iron-Doped Carbon Aerogels: Novel Porous Substrates for Direct Growth of Carbon Nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Steiner, S A; Baumann, T F; Kong, J; Satcher, J H; Dresselhaus, M S

    2007-02-15

    We present the synthesis and characterization of Fe-doped carbon aerogels (CAs) and demonstrate the ability to grow carbon nanotubes directly on monoliths of these materials to afford novel carbon aerogel-carbon nanotube composites. Preparation of the Fe-doped CAs begins with the sol-gel polymerization of the potassium salt of 2,4-dihydroxybenzoic acid with formaldehyde, affording K{sup +}-doped gels that can then be converted to Fe{sup 2+}- or Fe{sup 3+}-doped gels through an ion exchange process, dried with supercritical CO{sub 2} and subsequently carbonized under an inert atmosphere. Analysis of the Fe-doped CAs by TEM, XRD and XPS revealed that the doped iron species are reduced during carbonization to form metallic iron and iron carbide nanoparticles. The sizes and chemical composition of the reduced Fe species were related to pyrolysis temperature as well as the type of iron salt used in the ion exchange process. Raman spectroscopy and XRD analysis further reveal that, despite the presence of the Fe species, the CA framework is not significantly graphitized during pyrolysis. The Fe-doped CAs were subsequently placed in a thermal CVD reactor and exposed to a mixture of CH{sub 4} (1000 sccm), H{sub 2} (500 sccm), and C{sub 2}H{sub 4} (20 sccm) at temperatures ranging from 600 to 800 C for 10 minutes, resulting in direct growth of carbon nanotubes on the aerogel monoliths. Carbon nanotubes grown by this method appear to be multiwalled ({approx}25 nm in diameter and up to 4 mm long) and grow through a tip-growth mechanism that pushes catalytic iron particles out of the aerogel framework. The highest yield of CNTs were grown on Fe-doped CAs pyrolyzed at 800 C treated at CVD temperatures of 700 C.

  18. Iron-Doped Carbon Aerogels: Novel Porous Substrates for Direct Growth of Carbon Nanotubes

    Science.gov (United States)

    Steiner, S. A.; Baumann, T. F.; Kong, J.; Satcher, J. H.; Dresselhaus, M. S.

    2007-02-20

    We present the synthesis and characterization of Fe-doped carbon aerogels (CAs) and demonstrate the ability to grow carbon nanotubes directly on monoliths of these materials to afford novel carbon aerogel-carbon nanotube composites. Preparation of the Fe-doped CAs begins with the sol-gel polymerization of the potassium salt of 2,4-dihydroxybenzoic acid with formaldehyde, affording K{sup +}-doped gels that can then be converted to Fe{sup 2+}- or Fe{sup 3+}-doped gels through an ion exchange process, dried with supercritical CO{sub 2} and subsequently carbonized under an inert atmosphere. Analysis of the Fe-doped CAs by TEM, XRD and XPS revealed that the doped iron species are reduced during carbonization to form metallic iron and iron carbide nanoparticles. The sizes and chemical composition of the reduced Fe species were related to pyrolysis temperature as well as the type of iron salt used in the ion exchange process. Raman spectroscopy and XRD analysis further reveal that, despite the presence of the Fe species, the CA framework is not significantly graphitized during pyrolysis. The Fe-doped CAs were subsequently placed in a thermal CVD reactor and exposed to a mixture of CH{sub 4} (1000 sccm), H{sub 2} (500 sccm), and C{sub 2}H{sub 4} (20 sccm) at temperatures ranging from 600 to 800 C for 10 minutes, resulting in direct growth of carbon nanotubes on the aerogel monoliths. Carbon nanotubes grown by this method appear to be multiwalled ({approx}25 nm in diameter and up to 4 mm long) and grow through a tip-growth mechanism that pushes catalytic iron particles out of the aerogel framework. The highest yield of CNTs were grown on Fe-doped CAs pyrolyzed at 800 C treated at CVD temperatures of 700 C.

  19. Photocatalytic degradation of phenol in Aqueous Solutions by Fe(III-doped TiO2/UV Process

    Directory of Open Access Journals (Sweden)

    R Nabizadeh Nodehi

    2011-01-01

    Full Text Available "n "nBackgrounds and Objectives: Phenol and phenolic compounds are widely used in industry and daily liFe, and are of high interest due to stability in the environment, dissolution ability in water and health problems. In this regard, phenol removal from water is of high importance. The purpose of this study was to investigate the efficiency of photodegradation process for removal of phenol from aqueous system by use of Fe-doped TiO2 nanoparticles prepared by sol-gel method."nMaterials and Methods: Phenol concentrations of 5, 10, 50 and 100 mg/L were prepared and exposed to UV and Fe-doped TiO2, separately and simultaneously. Also the effect of initial phenol concentration, Fe-doped TiO2 loading and pH were studied. Various doses of photocatalist investigated for Fe- doped TiO2 were 0.25, 0.5 and 1 g/L. pH was studied at three ranges, acidic (pH=3, neutral (pH=7 and alkaline (pH=11."nResults: Maximum degradation was obtained at acidic pH, 0.5 g/L of Fe-doped TiO2 for all of phenol concentrations. With increasing initial concentration of phenol, photocatalytic degradation decreased. In comparison with Fe-doped TiO2/UV process, efficiency of UV radiation alone was low in phenol degradation (% 64.5 at 100 mg/l of phenol concentration. Also the amount of phenol adsorbed on the Fe-doped TiO2 was negligible at dark conditions."nConclusion: Results of this study showed that Fe(III- doped TiO2 nanoparticles had an important effect on photocatalytic degradation of high initial phenol concentration when Fe(III-doped TiO2/ UV process applied.

  20. Doped Chiral Polymer Metamaterials

    Science.gov (United States)

    Park, Cheol (Inventor); Kang, Jin Ho (Inventor); Gordon, Keith L. (Inventor); Sauti, Godfrey (Inventor); Lowther, Sharon E. (Inventor); Bryant, Robert G. (Inventor)

    2017-01-01

    Some implementations provide a composite material that includes a first material and a second material. In some implementations, the composite material is a metamaterial. The first material includes a chiral polymer (e.g., crystalline chiral helical polymer, poly-.gamma.-benzyl-L-glutamate (PBLG), poly-L-lactic acid (PLA), polypeptide, and/or polyacetylene). The second material is within the chiral polymer. The first material and the second material are configured to provide an effective index of refraction value for the composite material of 1 or less. In some implementations, the effective index of refraction value for the composite material is negative. In some implementations, the effective index of refraction value for the composite material of 1 or less is at least in a wavelength of one of at least a visible spectrum, an infrared spectrum, a microwave spectrum, and/or an ultraviolet spectrum.

  1. Synthesis, structure, magnetic, electrical and electrochemical properties of Al, Cu and Mg doped MnO{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Hashem, Ahmed M., E-mail: ahmedh242@yahoo.com [National Research Centre, Inorganic Chemistry Department, Behoes St., Dokki, Cairo (Egypt); Institute for Complex Materials, IFW Dresden, Helmholtzstr. 20, D-01069 Dresden (Germany); Abuzeid, Hanaa M. [National Research Centre, Inorganic Chemistry Department, Behoes St., Dokki, Cairo (Egypt); Narayanan, N. [Institute for Complex Materials, IFW Dresden, Helmholtzstr. 20, D-01069 Dresden (Germany); Ehrenberg, Helmut [Institute for Complex Materials, IFW Dresden, Helmholtzstr. 20, D-01069 Dresden (Germany); Materials Science, Technische Universitaet Darmstadt, Petersenstr. 23, D-64287 Darmstadt (Germany); Julien, C.M. [Universite Pierre et Marie Curie, Physicochimie des Electrolytes, Colloides et Sciences Analytiques (PECSA), 4 place Jussieu, 75005 Paris (France)

    2011-10-17

    Highlights: {yields} Al, Mg and Cu doped MnO{sub 2} as cathode in Li-ion batteries. {yields} Pure phase MnO{sub 2} for virgin and doped MnO{sub 2} were obtained. {yields} Doping elements improve the electrical conductivity of MnO{sub 2}. {yields} Electrochemical behaviour of MnO{sub 2} improved after doping by Al, Mg and Cu. - Abstract: Pure and doped manganese dioxides were prepared by wet-chemical method using fumaric acid and potassium permanganate as raw materials. X-ray diffraction patterns show that pure and Al, Cu and Mg doped manganese dioxides (d-MnO{sub 2}) crystallized in the cryptomelane-MnO{sub 2} structure. Thermal analysis show that, with the assistance of potassium ions inside the 2 x 2 tunnel, the presence of Al, Cu and Mg doping elements increases the thermal stability of d-MnO{sub 2}. The electrical conductivity of d-MnO{sub 2} increases in comparison with pure MnO{sub 2}, while Al-doped MnO{sub 2} exhibits the lower resistivity. As shown in the magnetic measurements, the value of the experimental effective magnetic moment of Mn ions decreases with introduction of dopants, which is attributed to the presence of a mixed valency of high-spin state Mn{sup 4+}/Mn{sup 3+}. Doped MnO{sub 2} materials show good capacity retention in comparison with virgin MnO{sub 2}. Al-doped MnO{sub 2} shows the best electrochemical results in terms of capacity retention and recharge efficiency.

  2. 具有强酸性锆掺杂有序介孔硅材料的合成%Synthesis and Characterization of Ordered Mesoporous Zirconium-doped Silica with Strong Acidity

    Institute of Scientific and Technical Information of China (English)

    邓军; 张洪升; 付文升

    2011-01-01

    通过三嵌段的共聚物做模板制备了一系列具有不同锆含量、强酸性的介孔硅材料,获得的样品通过x射线衍射分析、透射电镜分析、氮气吸附脱附、紫外可见光谱、热重分析等技术进行了表征.研究结果发现,当样品中硅和锆的物质的量比大于4时,锆物种能被完全引入到有序介孔硅结构的骨架中;然而,当样品中硅和锆的物质的量比小于4时,会出现一个由无定形硫化氧化锆组成的分离相.另外,透射电镜照片揭示了这些材料有着有序的介孔结构,氮气吸附-脱附等温线给出了属于介孔材料的IV型吸附-脱附等温线及较窄的介孔分布,异丙苯和1,3,5-三异丙基苯的裂化反应出示了它们有着非常好的催化活性,尤其适合涉及大分子的催化裂化反应.%A series of mesoporous sulfated silica-zirconia materials with various Si/Zr molar ratios ( 2.0 ~ 5.0) have been prepared using tri-hlock copolymer as a template, which was characterized by X-ray diffraction, TEM, nitrogen adsorption-desorption, UV-Vis diffuse reflectance spectroscopy, infrared spectroscopy, thermal gravimetric analysis, and catalytic reactions. XRD patterns displayed that ordered mesoporous sulfated silica-zirconia materials were obtained when the molar ratio of Si/Zr was more than 4.0. When the molar ratio of Si/Zr was less than 4.0, the samples had a separated phase of amorphous sulfated zirconia. Furthermore, TEM images revealed that the mesostructure of these materials were highly ordered. N2 adsorption exhibited typical Ⅳ adsorption-desorption isotherms and uniform pore distribution. UV-Vis reflectance and IR spectra suggested that Zr atoms were incorporated into the walls of mesoporous silica. Cracking reactions of cumene and 1,3,5-triisopropylbenzene (TIPB) showed that, the ordered mesoporous sulfated silica-zirconia materials were very active in acidic catalytic reactions, especially for the cracking of large molecules.

  3. Sulphur mustard degradation on zirconium doped Ti-Fe oxides.

    Science.gov (United States)

    Štengla, Václav; Grygar, Tomáš Matys; Opluštil, František; Němec, Tomáš

    2011-09-15

    Zirconium doped mixed nanodispersive oxides of Ti and Fe were prepared by homogeneous hydrolysis of sulphate salts with urea in aqueous solutions. Synthesized nanodispersive metal oxide hydroxides were characterised as the Brunauer-Emmett-Teller (BET) surface area and Barrett-Joiner-Halenda porosity (BJH), X-ray diffraction (XRD), infrared (IR) spectroscopy, scanning electron microscopy (SEM) with energy-dispersive X-ray (EDX) microanalysis, and acid-base titration. These oxides were taken for an experimental evaluation of their reactivity with sulphur mustard (chemical warfare agent HD or bis(2-chloroethyl)sulphide). The presence of Zr(4+) dopant tends to increase both the surface area and the surface hydroxylation of the resulting doped oxides in such a manner that it can contribute to enabling the substrate adsorption at the oxide surface and thus accelerate the rate of degradation of warfare agents. The addition of Zr(4+) to the hydrolysis of ferric sulphate with urea shifts the reaction route and promotes formation of goethite at the expense of ferrihydrite. We discovered that Zr(4+) doped oxo-hydroxides of Ti and Fe exhibit a higher degradation activity towards sulphur mustard than any other yet reported reactive sorbents. The reaction rate constant of the slower parallel reaction of the most efficient reactive sorbents is increased with the increasing amount of surface base sites.

  4. Biomarker monitoring in sports doping control.

    Science.gov (United States)

    Pottgiesser, Torben; Schumacher, Yorck Olaf

    2012-06-01

    Biomarker monitoring can be considered a new era in the effort against doping. Opposed to the old concept in doping control of direct detection of a prohibited substance in a biological sample such as urine or blood, the new paradigm allows a personalized longitudinal monitoring of biomarkers that indicate non-physiological responses independently of the used doping technique or substance, and may cause sanctioning of illicit practices. This review presents the development of biomarker monitoring in sports doping control and focuses on the implementation of the Athlete Biological Passport as the current concept of the World Anti Doping Agency for the detection of blood doping (hematological module). The scope of the article extends to the description of novel biomarkers and future concepts of application.

  5. A brief review of co-doping

    Science.gov (United States)

    Zhang, Jingzhao; Tse, Kinfai; Wong, Manhoi; Zhang, Yiou; Zhu, Junyi

    2016-12-01

    Dopants and defects are important in semiconductor and magnetic devices. Strategies for controlling doping and defects have been the focus of semiconductor physics research during the past decades and remain critical even today. Co-doping is a promising strategy that can be used for effectively tuning the dopant populations, electronic properties, and magnetic properties. It can enhance the solubility of dopants and improve the stability of desired defects. During the past 20 years, significant experimental and theoretical efforts have been devoted to studying the characteristics of co-doping. In this article, we first review the historical development of co-doping. Then, we review a variety of research performed on co-doping, based on the compensating nature of co-dopants. Finally, we review the effects of contamination and surfactants that can explain the general mechanisms of co-doping.

  6. Degenerate doping of metallic anodes

    Science.gov (United States)

    Friesen, Cody A; Zeller, Robert A; Johnson, Paul B; Switzer, Elise E

    2015-05-12

    Embodiments of the invention relate to an electrochemical cell comprising: (i) a fuel electrode comprising a metal fuel, (ii) a positive electrode, (iii) an ionically conductive medium, and (iv) a dopant; the electrodes being operable in a discharge mode wherein the metal fuel is oxidized at the fuel electrode and the dopant increases the conductivity of the metal fuel oxidation product. In an embodiment, the oxidation product comprises an oxide of the metal fuel which is doped degenerately. In an embodiment, the positive electrode is an air electrode that absorbs gaseous oxygen, wherein during discharge mode, oxygen is reduced at the air electrode. Embodiments of the invention also relate to methods of producing an electrode comprising a metal and a doped metal oxidation product.

  7. Phosphorous doping a semiconductor particle

    Science.gov (United States)

    Stevens, Gary Don; Reynolds, Jeffrey Scott

    1999-07-20

    A method (10) of phosphorus doping a semiconductor particle using ammonium phosphate. A p-doped silicon sphere is mixed with a diluted solution of ammonium phosphate having a predetermined concentration. These spheres are dried (16, 18), with the phosphorus then being diffused (20) into the sphere to create either a shallow or deep p-n junction. A good PSG glass layer is formed on the surface of the sphere during the diffusion process. A subsequent segregation anneal process is utilized to strip metal impurities from near the p-n junction into the glass layer. A subsequent HF strip procedure is then utilized to removed the PSG layer. Ammonium phosphate is not a restricted chemical, is inexpensive, and does not pose any special shipping, handling, or disposal requirement.

  8. Phosphorus doping a semiconductor particle

    Science.gov (United States)

    Stevens, G.D.; Reynolds, J.S.

    1999-07-20

    A method of phosphorus doping a semiconductor particle using ammonium phosphate is disclosed. A p-doped silicon sphere is mixed with a diluted solution of ammonium phosphate having a predetermined concentration. These spheres are dried with the phosphorus then being diffused into the sphere to create either a shallow or deep p-n junction. A good PSG glass layer is formed on the surface of the sphere during the diffusion process. A subsequent segregation anneal process is utilized to strip metal impurities from near the p-n junction into the glass layer. A subsequent HF strip procedure is then utilized to removed the PSG layer. Ammonium phosphate is not a restricted chemical, is inexpensive, and does not pose any special shipping, handling, or disposal requirement. 1 fig.

  9. Fabrication of photonic crystals with nigrosine-doped poly(MMA-co-DVB-co-MAA) particles.

    Science.gov (United States)

    Zhang, Shuai; Zhao, Xiang-Wei; Xu, Hua; Zhu, Rong; Gu, Zhong-Ze

    2007-12-01

    A convenient approach was developed to fabricate monodisperse nigrosine-doped poly(methyl methacrylate-co-divinylbenzene-co-methacrylic acid) nanoparticles with different cross-linkage by soap-free emulsion polymerization at boiling status and swelling process. The dye-doped nanoparticles were used for the fabrication of colloidal crystal films and beads. It was found that nigrosine dye in the nanoparticles can efficiently depress the light scattering inside the colloidal crystal films and eliminate the iridescent effect in the photonic beads. These results make the colloidal crystals useful in photonic paper, bioassay, and so on.

  10. Main modern problems of doping in sport

    Directory of Open Access Journals (Sweden)

    Rudenko V.P.

    2014-04-01

    Full Text Available Purpose : to identify and substantiate medico-biological, psychological and social problems of doping in sport. Material: Theoretical study is based on analysis of more than 50 scientific and methodical literatures. Results : it was shown that doping is one of the serious problems of modern sport and society in general. Defines important questions regarding anti-doping rules and the anti-doping control in sport. Installed the use of performance enhancing drugs in professional sports for children and youth. Given the promising solutions to the problems of doping in Ukraine. Conclusions: Among the problems of modern sport is becoming increasingly important issue of doping. It is an extremely complex because it involves the interrelated medical, legal, political, moral, organizational, social and pedagogical aspects. Socio-pedagogical factors of anti-doping policy in sports scientists comprehensively still not addressed. Certain aspects of anti-doping policy presented in scientific papers, which can be divided into two groups. The first group of papers is devoted to doping in sport as a social event. The second group of papers devoted to the problems of doping control. Today there is a need and objective preconditions for the development and adoption of a General concept, which would be generalized numerical amount of data received and served as a basis for developing an effective anti-doping control at the expense of improvement of legislative and normative-legal base and infrastructure of the anti-doping policy in Ukraine, which should be brought in line with modern international standards.

  11. Psychogenic urine retention during doping controls

    DEFF Research Database (Denmark)

    Elbe, Anne-Marie; Schlegel, Marius M.; Brand, Ralf

    2012-01-01

    Psychogenic urine retention during doping controls (PURD) refers to an athlete's inability to urinate during a doping control. This paper reports PURD to occur quite frequently in elite athletes, investigates the relationship to the clinical disorder of paruresis (PAR), and investigates its...... and pencil study involving 222 German-speaking athletes from various sports. The results indicate that 60% of these athletes have experienced psychogenic urine retention during doping controls, with only 39% of them showing symptoms of paruresis. PURD impacts athlete recovery and self......-perception of professionalism and athletic excellence. Suggestions for psychological interventions and recommendations for improving the doping control system are given....

  12. Comparison of various organic compounds destruction on rare earths doped Ti/Sb-SnO{sub 2} electrodes

    Energy Technology Data Exchange (ETDEWEB)

    Cui, Yu-Hong [School of Environmental Science and Engineering, Huazhong University of Science and Technology, No. 1037 Luoyu Road, Hongshan District, Wuhan 430074 (China); State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology, No. 73 Huanghe Road, Nangang District, Harbin 150090 (China); Feng, Yu-Jie, E-mail: yujief@hit.edu.cn [State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology, No. 73 Huanghe Road, Nangang District, Harbin 150090 (China); Liu, Junfeng; Ren, Nanqi [State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology, No. 73 Huanghe Road, Nangang District, Harbin 150090 (China)

    2012-11-15

    Highlights: Black-Right-Pointing-Pointer Different REs doping has distinct effect on the Ti/Sb-SnO{sub 2} electrode performance. Black-Right-Pointing-Pointer Gd or Eu improves the performance of Ti/Sb-SnO{sub 2} on aromatic ring cleavage. Black-Right-Pointing-Pointer Catechol is more refractory to be degraded than benzoquinone and hydroquinone. Black-Right-Pointing-Pointer The molecular structure of organic compound influences its degradation rate. - Abstract: Ti/Sb-SnO{sub 2} and three kinds of rare earths (REs), namely Ce, Gd, and Eu doped Ti/Sb-SnO{sub 2} electrodes were prepared and tested for their capacity on electrocatalytic degradation of three kinds of basal aromatic compounds (benzoquinone, hydroquinone and catechol) and six kinds of aliphatic acids (maleic acid, fumaric acid, succinic acid, malonic acid, oxalic acid and acetic acid). The elimination of selected organics as well as their TOC removal with different doped Ti/Sb-SnO{sub 2} electrodes was described by first-order kinetics. Compared with Ti/Sb-SnO{sub 2}, the Gd and Eu doped electrodes show better performance on the degradation of most of the selected organics, while Ce doped electrode shows either closely or lower efficiency on the degradation of these selected organics. Besides electrode material, the molecular structure of organic compound has obvious effect on its degradation in the electrocatalytic process. Catechol is more resistant to the electrophilic attack by hydroxyl radicals than benzoquinone and hydroquinone. The compound with more complicate molecular structure or longer carbon chain is more difficult to be mineralized. The aliphatic acid with higher oxygen content or more double bonds is more readily to be oxidized in the electrocatalytic process.

  13. Highly luminescent S, N co-doped graphene quantum dots with broad visible absorption bands for visible light photocatalysts

    Science.gov (United States)

    Qu, Dan; Zheng, Min; Du, Peng; Zhou, Yue; Zhang, Ligong; Li, Di; Tan, Huaqiao; Zhao, Zhao; Xie, Zhigang; Sun, Zaicheng

    2013-11-01

    A facile hydrothermal synthesis route to N and S, N co-doped graphene quantum dots (GQDs) was developed by using citric acid as the C source and urea or thiourea as N and S sources. Both N and S, N doped GQDs showed high quantum yield (78% and 71%), excitation independent under excitation of 340-400 nm and single exponential decay under UV excitation. A broad absorption band in the visible region appeared in S, N co-doped GQDs due to doping with sulfur, which alters the surface state of GQDs. However, S, N co-doped GQDs show different color emission under excitation of 420-520 nm due to their absorption in the visible region. The excellent photocatalytic performance of the S, N co-doped GQD/TiO2 composites was demonstrated by degradation of rhodamine B under visible light. The apparent rate of S, N:GQD/TiO2 is 3 and 10 times higher than that of N:GQD/TiO2 and P25 TiO2 under visible light irradiation, respectively.A facile hydrothermal synthesis route to N and S, N co-doped graphene quantum dots (GQDs) was developed by using citric acid as the C source and urea or thiourea as N and S sources. Both N and S, N doped GQDs showed high quantum yield (78% and 71%), excitation independent under excitation of 340-400 nm and single exponential decay under UV excitation. A broad absorption band in the visible region appeared in S, N co-doped GQDs due to doping with sulfur, which alters the surface state of GQDs. However, S, N co-doped GQDs show different color emission under excitation of 420-520 nm due to their absorption in the visible region. The excellent photocatalytic performance of the S, N co-doped GQD/TiO2 composites was demonstrated by degradation of rhodamine B under visible light. The apparent rate of S, N:GQD/TiO2 is 3 and 10 times higher than that of N:GQD/TiO2 and P25 TiO2 under visible light irradiation, respectively. Electronic supplementary information (ESI) available: More XPS and UV-Vis spectra. See DOI: 10.1039/c3nr04402e

  14. Photocatalytic degradation of selected herbicides in aqueous suspensions of doped titania under visible light irradiation.

    Science.gov (United States)

    Sojić, Daniela V; Despotović, Vesna N; Abazović, Nadica D; Comor, Mirjana I; Abramović, Biljana F

    2010-07-15

    The aim of this work was to study the efficiency of Fe- and N-doped titania suspensions in the photocatalytic degradation of the herbicides RS-2-(4-chloro-o-tolyloxy)propionic acid (mecoprop, MCPP), (4-chloro-2-methylphenoxy)acetic acid (MCPA), and 3,6-dichloropyridine-2-carboxylic acid (clopyralid, CP) under the visible light (lambda > or = 400 nm) irradiation. The obtained results were compared with those of the corresponding undoped TiO(2) (rutile/anatase) and of the most frequently used TiO(2) Degussa P25. Computational modeling procedures were used to optimize geometry and molecular electrostatic potentials of MCPP, MCPA and CP and discuss the obtained results. The results indicate that the efficiency of photocatalytic degradation is greatly influenced by the molecular structure of the compound. Lowering of the band gap of titanium dioxide by doping is not always favorable for increasing photocatalytic efficiency of degradation.

  15. Photocatalytic degradation of selected herbicides in aqueous suspensions of doped titania under visible light irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Sojic, Daniela V., E-mail: daniela.sojic@dh.uns.ac.rs [Department of Chemistry, Biochemistry and Environmental Protection, Faculty of Sciences, University of Novi Sad, Trg D. Obradovica 3, 21000 Novi Sad (Serbia); Despotovic, Vesna N., E-mail: vesna.despotovic@dh.uns.ac.rs [Department of Chemistry, Biochemistry and Environmental Protection, Faculty of Sciences, University of Novi Sad, Trg D. Obradovica 3, 21000 Novi Sad (Serbia); Abazovic, Nadica D., E-mail: kiki@vinca.rs [Vinca Institute of Nuclear Sciences, 11001 Beograd, PO Box 522 (Serbia); Comor, Mirjana I., E-mail: mirjanac@vinca.rs [Vinca Institute of Nuclear Sciences, 11001 Beograd, PO Box 522 (Serbia); Abramovic, Biljana F., E-mail: biljana.abramovic@dh.uns.ac.rs [Department of Chemistry, Biochemistry and Environmental Protection, Faculty of Sciences, University of Novi Sad, Trg D. Obradovica 3, 21000 Novi Sad (Serbia)

    2010-07-15

    The aim of this work was to study the efficiency of Fe- and N-doped titania suspensions in the photocatalytic degradation of the herbicides RS-2-(4-chloro-o-tolyloxy)propionic acid (mecoprop, MCPP), (4-chloro-2-methylphenoxy)acetic acid (MCPA), and 3,6-dichloropyridine-2-carboxylic acid (clopyralid, CP) under the visible light ({lambda} {>=} 400 nm) irradiation. The obtained results were compared with those of the corresponding undoped TiO{sub 2} (rutile/anatase) and of the most frequently used TiO{sub 2} Degussa P25. Computational modeling procedures were used to optimize geometry and molecular electrostatic potentials of MCPP, MCPA and CP and discuss the obtained results. The results indicate that the efficiency of photocatalytic degradation is greatly influenced by the molecular structure of the compound. Lowering of the band gap of titanium dioxide by doping is not always favorable for increasing photocatalytic efficiency of degradation.

  16. Effect of amino acid additives on the growth and physical properties of potassium acid phthalate (KAP) crystals

    Science.gov (United States)

    Kumaran, A. Elakkina; Kanchana, P.; Sekar, C.

    2012-06-01

    Single crystals of potassium acid phthalate (KAP) have been grown from aqueous solution by slow evaporation technique by adding L-alanine (LA), glycine (Gly) and L-tyrosine (LT) as additives. Powder X-ray diffraction studies confirmed the phase formation and amino acids doping into KAP crystals. The optical absorption studies reveal that the LA doped crystals possess less absorption of visible ray than the pristine, Gly and LT doped KAP crystals. Optical transmission is found to be low in LT doped KAP than in all the other crystals. TG-DTA studies show the decomposition temperatures to be 255 °C, 232 °C, 258 °C and 264 °C for pure, LA, Gly and LT doped KAP crystals respectively. SHG efficiency of LA doped KAP crystal was found to be 1.1 times (31 mV for KDP and 34 mV for LA doped KAP) that of potassium dihydrogen phosphate (KDP) crystal. This is much higher when compared to that of undoped KAP crystal (12 mV). The grown crystals were also subjected to FTIR, microhardness and dielectric studies.

  17. Photodegradation of ibuprofen by TiO2 co-doping with urea and functionalized CNT irradiated with visible light - Effect of doping content and pH.

    Science.gov (United States)

    Yuan, Ching; Hung, Chung-Hsuang; Li, Huei-Wen; Chang, Wei-Hsian

    2016-07-01

    Ibuprofen (IBP) is one kind of non-steroidal anti-inflammatory drugs (NSAIDs), which are classified as Pharmaceuticals and Personal Care Products (PPCPs). IBP possesses bioactive property and the substantial use of IBP results in a harmful impact on bioreceptors even in small concentrations. Accordingly, the treatment of these wastewaters is important before discharging them into the ecosystem. The photodegradation of IBP with TiO2 co-doped with functionalized CNTs (CNT-COOH and CNT-COCl) and urea, named as N-doping CNT/TiO2, irradiated with visible light of 410 nm was investigated in this study. The titanium tetrachloride was used as the precursor of Ti. The N-doping CNT-COCl/TiO2 photocatalysts exhibited a better crystalline structure and smaller crystal size than the N-doping CNT-COOH/TiO2 photocatalyst. It might largely ascribe to strong binding between acyl chloride functional group and TiO2. About 85.0%-86.0% of IBP was degraded with N-doping CNT/TiO2 within 120 min at natural condition, which obeyed the pseudo first order reaction and the rate constant was 4.45 × 10(-3)-1.22 × 10(-2) min(-1) and 5.03 × 10(-3)-1.47 × 10(-2) min(-1) for N-doping CNT-COOH/TiO2 and N-doping CNT-COCl/TiO2, respectively. The best IBP degradation of 87.9%-89.0% was found at pH 5, which indicated superoxide radicals (O2(-)) played a key role. The optimal pH was majorly dominated by the nature of IBP and N-doping CNT/TiO2. A successful synergy effect of TiO2 and dopants was exhibited and this mainly attributed to the strong binding strength by functional group of acyl chloride (COCl) and carboxylic acid (COOH). In summary, IBP could be effectively photodegraded by the fabricated N-doping CNT/TiO2 photocatalysts.

  18. Transmittance and Reflectance Spectra of Doped-Polyanisidine-Derived Film in the Visible Light Region

    Energy Technology Data Exchange (ETDEWEB)

    Tapia, A K G [Physics Divisio, Institute of Mathematical Sciences and Physics and University of the Philippines Los Banos, College, Laguna, Philippines, 4031 (Philippines); Catedral, M D [Physics Divisio, Institute of Mathematical Sciences and Physics and University of the Philippines Los Banos, College, Laguna, Philippines, 4031 (Philippines); Herrera, M U [Physics Divisio, Institute of Mathematical Sciences and Physics and University of the Philippines Los Banos, College, Laguna, Philippines, 4031 (Philippines); Tamayo, J P [Institute of Chemistry, University of the Philippines Los Banos, College, Laguna, Philippines, 4031 (Philippines); Rosario, E J R del [Institute of Chemistry, University of the Philippines Los Banos, College, Laguna, Philippines, 4031 (Philippines)

    2006-01-01

    Polyanisidine (PAnis) powder was synthesized using a standard procedure. It was doped with Hydrochloric (HCl) and Perchloric (HClO{sub 4}) Acids. The air-dried PAnis powder was then diluted using Dimethyl Formamide (DMF) as solvent and was spread out in a SiOx transparent glass substrate. An amorphous and semi-transparent film was fabricated seen in a polarizing microscope. The spectral analysis was carried out in the visible region from 400 nm to 700 nm. For HCl-doped sample, the high intensity region in the transmittance spectra occurred at the green portion while the high intensity region for the reflectance spectra was seen at the violet portion. Lastly, for the HClO4-doped sample, the peak intensities are at 536 nm and 516 nm for the transmittance and the reflectance spectra, respectively.

  19. Crystal structure analysis and first principle investigation of F doping in LiFePO4

    Science.gov (United States)

    Milović, Miloš; Jugović, Dragana; Cvjetićanin, Nikola; Uskoković, Dragan; Milošević, Aleksandar S.; Popović, Zoran S.; Vukajlović, Filip R.

    2013-11-01

    This work presents the synthesis of F-doped LiFePO4/C composite by the specific modification of the recently suggested synthesis procedure based on an aqueous precipitation of precursor material in molten stearic acid, followed by a high temperature treatment. Besides the lattice parameters and the primitive cell volume reductions, compared to the undoped sample synthesized under the same conditions, the Rietveld refinement also shows that fluorine ions preferably occupy specific oxygen sites. Particularly, the best refinement is accomplished when fluorine ions occupy O(2) sites exclusively. By means of up-to-date electronic structure and total energy calculations this experimental finding is theoretically confirmed. Such fluorine doping also produces closing of the gap in the electronic structure and consequently better conductivity properties of the doped compound. In addition, the morphological and electrochemical performances of the synthesized powder are fully characterized.

  20. DC Electrical Conductivity Retention, Optical Properties and Ammonia Sensing Analysis of Naturally Degraded CSA-Doped Graphene/polyaniline Composite Nanofibers Prepared with CTAB

    Science.gov (United States)

    Ghazali, Sayyed; Hossain, Muhammad M.; Khan, Abuzar; Khan, Mohd Y.; Hasan, Mudassir

    2017-01-01

    In this paper, we report surfactant-mediated synthesis of camphor sulfonic acid (CSA)-doped polyaniline/graphene (PANI/GN) composite nanofibers as an electrical conductor and excellent ammonia sensor. The synthesis was mediated by cetyltrimethylammonium bromide as surfactant. The as-synthesized composite nanofibers were characterized by Raman spectroscopy, scanning electron microscopy, tunneling electron microscopy, x-ray diffraction, diffused reflectance spectroscopy and differential scanning calorimetry. The electrical conductivity of the CSA-doped PANI/GN composite nanofibers was found to be remarkably enhanced as compared to the CSA-doped PANI. The boost in electronic conductivity could be attributed to an improved electronic interaction between CSA-doped PANI backbone and GN present in the composite system. The naturally degraded CSA-doped PANI/GN composite nanofibers showed a decrease in electrical conductivity but worked as a good ammonia sensor in open atmospheric conditions.

  1. DC Electrical Conductivity Retention, Optical Properties and Ammonia Sensing Analysis of Naturally Degraded CSA-Doped Graphene/polyaniline Composite Nanofibers Prepared with CTAB

    Science.gov (United States)

    Ghazali, Sayyed; Hossain, Muhammad M.; Khan, Abuzar; Khan, Mohd Y.; Hasan, Mudassir

    2016-09-01

    In this paper, we report surfactant-mediated synthesis of camphor sulfonic acid (CSA)-doped polyaniline/graphene (PANI/GN) composite nanofibers as an electrical conductor and excellent ammonia sensor. The synthesis was mediated by cetyltrimethylammonium bromide as surfactant. The as-synthesized composite nanofibers were characterized by Raman spectroscopy, scanning electron microscopy, tunneling electron microscopy, x-ray diffraction, diffused reflectance spectroscopy and differential scanning calorimetry. The electrical conductivity of the CSA-doped PANI/GN composite nanofibers was found to be remarkably enhanced as compared to the CSA-doped PANI. The boost in electronic conductivity could be attributed to an improved electronic interaction between CSA-doped PANI backbone and GN present in the composite system. The naturally degraded CSA-doped PANI/GN composite nanofibers showed a decrease in electrical conductivity but worked as a good ammonia sensor in open atmospheric conditions.

  2. Boron-doped cadmium oxide composite structures and their electrochemical measurements

    Energy Technology Data Exchange (ETDEWEB)

    Lokhande, B.J., E-mail: bjlokhande@yahoo.com [Lab of Smart Mtrls Supercapacitive and Energy Studies, School of Physical Sciences, Solapur University, Solapur 413255, Maharashtra (India); Ambare, R.C. [Lab of Smart Mtrls Supercapacitive and Energy Studies, School of Physical Sciences, Solapur University, Solapur 413255, Maharashtra (India); Mane, R.S. [School of Physical Sciences, Swami Ramanand Teerth Marathwada University, Nanded 431606 (India); Bharadwaj, S.R. [Chemistry Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400085 (India)

    2013-08-01

    Graphical abstract: Conducting nano-fibrous 3% boron doped cadmium oxide thin films were prepared by SILAR and its super capacitive properties were studied. - Highlights: • Samples are of nanofibrous nature. • All samples shows pseudocapacitive behavior. • 3% B doped CdO shows good specific capacitance. • 3% B doped CdO shows maximum 74.93% efficiency at 14 mA/cm{sup 2}. • 3% B doped CdO shows 0.8 Ω internal resistance. - Abstract: Boron-doped and undoped cadmium oxide composite nanostructures in thin film form were prepared onto stainless steel substrates by a successive ionic layer adsorption and reaction method using aqueous solutions of cadmium nitrate, boric acid and 1% H{sub 2}O{sub 2}. As-deposited films were annealed at 623 K for 1 h. The X-ray diffraction study shows crystalline behavior for both doped and undoped films with a porous topography and nano-wires type architecture, as observed in SEM image. Wettability test confirms the hydrophilic surface with 58° contact angle value. Estimated band gap energy is around 1.9 eV. Electrochemical behavior of the deposited films is attempted in 1 M KOH electrolyte using cyclic voltammetry (CV), electrochemical impedance spectroscopy and galvanostatic charge–discharge tests. Maximum values of the specific capacitance, specific energy and specific power obtained for 3% B doped CdO film at 2 mV/s scan rate are 20.05 F/g, 1.22 Wh/kg and 3.25 kW/kg, respectively.

  3. Structural and vibrational investigations of Nb-doped TiO{sub 2} thin films

    Energy Technology Data Exchange (ETDEWEB)

    Uyanga, E., E-mail: uyanga.enkhnaran@gmail.com [Institute of Physics and Technology, Mongolian Academy of Sciences, Enkhtaivan Avenue 54B, Ulaanbaatar 13330 (Mongolia); Frank Laboratory of Neutron Physics, JINR, Dubna 141980 (Russian Federation); Gibaud, A.; Daniel, P. [LUNAM Université, Université du Maine, CNRS UMR 6283, Institut des molécules et matériaux et du Mans–IMMM, Avenue Olivier Messiaen, Le Mans 72085 Cedex 9 (France); Sangaa, D.; Sevjidsuren, G.; Altantsog, P. [Institute of Physics and Technology, Mongolian Academy of Sciences, Enkhtaivan Avenue 54B, Ulaanbaatar 13330 (Mongolia); Beuvier, T. [LUNAM Université, Université du Maine, CNRS UMR 6283, Institut des molécules et matériaux et du Mans–IMMM, Avenue Olivier Messiaen, Le Mans 72085 Cedex 9 (France); Lee, Chih Hao [Department of Engineering and System Science, National Tsing Hua University, Hsinchu 30013, Taiwan (China); Balagurov, A.M. [Frank Laboratory of Neutron Physics, JINR, Dubna 141980 (Russian Federation)

    2014-12-15

    Highlights: • We studied the evolutions of structure for TiO{sub 2} thin film as changes with Nb doping and temperatures. • Up to 800 °C, the grain size of Nb{sub 0.1}Ti{sub 0.9}O{sub 2} is smaller than for pure TiO{sub 2} because doped Nb hinders the growth of the TiO{sub 2} grains. • There was no formation of the rutile phase at high temperature. • Nb doped TiO{sub 2} films have high electron densities at 400–700 °C. • Nb dope extends the absorbance spectra of TiO{sub 2} which leads to the band gap reduce. - Abstract: Acid-catalyzed sol–gel and spin-coating methods were used to prepare Nb-doped TiO{sub 2} thin film. In this work, we studied the effect of niobium doping on the structure, surface, and absorption properties of TiO{sub 2} by energy-dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), X-ray reflectometry (XRR), X-ray photoelectron spectroscopy (XPS), Raman, and UV–vis absorption spectroscopy at various annealing temperatures. EDX spectra show that the Nb:Ti atomic ratios of the niobium-doped titania films are in good agreement with the nominal values (5 and 10%). XPS results suggest that charge compensation is achieved by the formation of Ti vacancies. Specific niobium phases are not observed, thus confirming that niobium is well incorporated into the titania crystal lattice. Thin films are amorphous at room temperature and the formation of anatase phase appeared at an annealing temperature close to 400 °C. The rutile phase was not observed even at 900 °C (XRD and Raman spectroscopy). Grain sizes and electron densities increased when the temperature was raised. Nb-doped films have higher electron densities and lower grain sizes due to niobium doping. Grain size inhibition can be explained by lattice stress induced by the incorporation of larger Nb{sup 5+} ions into the lattice. The band gap energy of indirect transition of the TiO{sub 2} thin films was calculated to be about 3.03 eV. After niobium doping, it decreased to 2

  4. Synthesis, spectroscopy and simulation of doped nanocrystals

    NARCIS (Netherlands)

    Suyver, Jan Frederik

    2003-01-01

    This thesis deals with the properties of semiconductor nanocrystals (ZnS or ZnSe) in the size range (diameter) of 2 nm to 10 nm. The nanocrystals under investigation are doped with the transition metal ions manganese or copper. The goal is to study photoluminescence and electroluminescence from dope

  5. Moral entrepreneurship and doping cultures in sport

    NARCIS (Netherlands)

    Stokvis, R.

    2003-01-01

    In this article, the fight against doping has been analyzed as an ongoing process of social definition. It is dependent on the development of power relations within and outside the world of sport. To analyze these dependencies, I identified a variety of important doping cultures in sport and studied

  6. Probing Photocatalytic Characteristics of Sb-Doped TiO2 under Visible Light Irradiation

    Directory of Open Access Journals (Sweden)

    Lingjing Luo

    2014-01-01

    Full Text Available Sb-doped TiO2 nanoparticle with varied dopant concentrations was synthesized using titanium tetrachloride (TiCl4 and antimony chloride (SbCl3 as the precursors. The properties of Sb-doped TiO2 nanoparticles were characterized by X-ray diffraction (XRD, scanning electron microscope (SEM, fluorescence spectrophotometer, and Uv-vis spectrophotometer. The absorption edge of TiO2 nanoparticles could be extended to visible region after doping with antimony, in contrast to the UV absorption of pure TiO2. The results showed that the photocatalytic activity of Sb-doped TiO2 nanoparticles was much more active than pure TiO2. The 0.1% Sb-doped TiO2 nanoparticles demonstrated the best photocatalytic activity which was better than that of the Degussa P25 under visible light irradiation using terephthalic acid as fluorescent probe. The effects of Sb dopant on the photocatalytic activity and the involved mechanism were extensively investigated in this work as well.

  7. Study on A.C. electrical properties of pure and L-serine doped ADP crystals

    Science.gov (United States)

    Joshi, J. H.; Dixit, K. P.; Joshi, M. J.; Parikh, K. D.

    2016-05-01

    Ammonium Dihydrogen Phosphate (ADP) crystals have a wide range of applications in integrated and nonlinear optics. Amino acids having significant properties like molecular chirality, zwitter ionic nature, etc. attracted many researchers to dope them in various NLO crystals. In the present study, pure and different weight percentage L-serine doped ADP crystals were grown by slow solvent evaporation technique at room temperature. The A.C. electrical study was carried out for palletized samples at room temperature. The Nyquist plot showed two semi circles for pure ADP indicated the effect of grain and grain boundary, whereas the doped ADP samples exhibited the single semi circle suggesting the effect of grain. The values resistance and capacitance for grain and grain boundary were calculated. The effect of doping was clearly seen in the grain capacitance and resistance values. The dielectric constant and dielectric loss decreased with increase in frequency for all samples. The Jonscher power law was applied for A.C. conductivity for pure and doped ADP samples. The imaginary part of modulus and impedance versus frequency were drawn and the value of stretch exponent (β) was calculated for all the samples.

  8. Photoelectrochemical performance of W-doped BiVO4 thin films deposited by spray pyrolysis

    Science.gov (United States)

    Holland, S. Keith; Dutter, Melissa R.; Lawrence, David J.; Reisner, Barbara A.; DeVore, Thomas C.

    2014-01-01

    The effects of tungsten doping and hydrogen annealing on the photoelectrochemical (PEC) performance of bismuth vanadate (BiVO4) photoanodes for solar water splitting were studied. Thin films of BiVO were deposited on indium tin oxide-coated glass slides by ultrasonic spray pyrolysis of an aqueous solution containing bismuth nitrate and vanadium oxysulfate. Tungsten doping was achieved by adding either silicotungstic acid (STA) or ammonium metatungstate (AMT) to the precursor. The 1.7- to 2.2-μm-thick films exhibited a highly porous microstructure. Undoped films that were reduced at 375°C in 3% H exhibited the largest photocurrent densities under 0.1 W cm-2 AM1.5 illumination, where photocurrent densities of up to 1.3 mA cm-2 at 0.5 V with respect to Ag/AgCl were achieved. Films doped with 1% or 5% (atomic percent) tungsten from either STA or AMT exhibited reduced PEC performance and greater sample-to-sample performance variations. Powder x-ray diffraction data indicated that the films continue to crystallize in the monoclinic polymorph at low doping levels but crystallize in the tetragonal scheelite structure at higher doping. It is surmised that the phase and morphology differences promoted by the addition of W during the deposition process reduced the PEC performance as measured by photovoltammetry.

  9. Boron-doped MnO{sub 2}/carbon fiber composite electrode for supercapacitor

    Energy Technology Data Exchange (ETDEWEB)

    Chi, Hong Zhong, E-mail: hzchi@hdu.edu.cn [College of Materials and Environmental Engineering, Hangzhou Dianzi University, Hangzhou 310018 (China); Zhu, Hongjie [College of Materials and Environmental Engineering, Hangzhou Dianzi University, Hangzhou 310018 (China); Gao, Linhui [Center of Materials Engineering, Zhejiang Sci-Tech University, Hangzhou 310018 (China)

    2015-10-05

    Highlights: • Interstitial ion in MnO{sub 2} lattice. • Porous film composed by interlocking worm-like nanostructure. • Boron-doped birnessite-type MnO{sub 2}/carbon fiber composite electrode. • Enhanced capacitive properties through nonmetal element doping. - Abstract: The boron-doped MnO{sub 2}/carbon fiber composite electrode has been prepared via in situ redox reaction between potassium permanganate and carbon fibers in the presence of boric acid. The addition of boron as dopant results in the increase of growth-rate of MnO{sub 2} crystal and the formation of worm-like nanostructure. Based on the analysis of binding energy, element boron incorporates into the MnO{sub 2} lattice through interstitial mode. The doped electrode with porous framework is beneficial to pseudocapacitive reaction and surface charge storage, leading to higher specific capacitance and superior rate capability. After experienced 1000 cycles, the boron-doped MnO{sub 2} still retain a higher specific capacitance by about 80% of its initial value. The fall in capacitance is blamed to be the combination of the formation of soluble Mn{sup 2+} and the absence of active site on the outer surface.

  10. [Doping, sport and addiction--any links?].

    Science.gov (United States)

    Foucart, J; Verbanck, P; Lebrun, P

    2015-01-01

    Sport is widely encouraged as it is beneficial for health. However, high-performance sport is more and more associated to rather suspicious practices; doping is one of the best example. From a physician point of view, the use of doping agents is obviously a major concern because taking such products often induce serious adverse effects on health. The present manuscript aims to inform physicians about the most frequent doping practices. It also points out that intensive sport can generate an "addictive" behavior sharing with "common"addictions a loss of practice control, a lack of interest in other activities and even a sport's practice detrimental to athlete's health. Analysis of the doping issue needs to take this reality into account as some doping products display an established " addictive" effect.

  11. CO tolerance by the PEMFC operational at temperatures up to 200°C

    DEFF Research Database (Denmark)

    Li, Qingfeng; He, Ronghuan; Gao, Ji-An;

    2003-01-01

    The CO poisoning effect on carbon-supported platinum catalysts in polymer electrolyte membrane fuel cells has been investigated in a temperature range from 125 to 200°C with the phosphoric acid-doped polybenzimidazole membranes as electrolyte. The effect is very temperature-dependent and can be s...... densities lower than 0.25 A/cm2. For comparison, the tolerance is only 0.0025 % CO (25 ppm) at 80°C at current densities up to 0.15 A/cm². The effect of CO2 in hydrogen was also studied. At 175°C, 25% CO2 in the fuel stream showed only the dilution effect.......The CO poisoning effect on carbon-supported platinum catalysts in polymer electrolyte membrane fuel cells has been investigated in a temperature range from 125 to 200°C with the phosphoric acid-doped polybenzimidazole membranes as electrolyte. The effect is very temperature-dependent and can...

  12. Effects of doping concentration on properties of Mn-doped ZnO thin films

    Institute of Scientific and Technical Information of China (English)

    Gao Li; Zhang Jian-Min

    2009-01-01

    This paper reports that the radio frequency magnetron sputtering is used to fabricate ZnO and Mn-doped ZnO thin films on glass substrates at 500 ℃. The Mn-doped ZnO thin films present wurtzite structure of ZnO and have a smoother surface, better conductivity but no ferromagnetism. The x-ray photoelectron spectroscopy results show that the binding energy of Mn_(2p3/2) increases with increasing Mn content slightly, and the state of Mn in the Mn-doped ZnO thin films is divalent. The chemisorbed oxygen in the Mn-doped ZnO thin films increases with increasing Mn doping concentration. The photoluminescence spectra of ZnO and Mn-doped ZnO thin films have a similar ultraviolet emission. The yellow green emissions of 4 wt. % and 10 wt. % Mn-doped thin films are quenched, whereas the yellow green emission occurs because of abundant oxygen vacancies in the Mn-doped ZnO thin films after 20 wt. % Mn doping. Compared with pure ZnO thin film, the bandgap of the Mn-doped ZnO thin films increases with increasing Mn content.

  13. Photocatalytic degradation of phenol by iodine doped tin oxide nanoparticles under UV and sunlight irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Al-Hamdi, Abdullah M.; Sillanpää, Mika [Laboratory of Green Chemistry, Lappeenranta University of Technology, Sammonkatu 12, 50130 Mikkeli (Finland); Dutta, Joydeep, E-mail: dutta@squ.edu.om [Chair in Nanotechnology, Water Research Center, Sultan Qaboos University, P.O. Box 17, 123 Al-Khoudh (Oman)

    2015-01-05

    Highlights: • A sol–gel method used to synthesize tin oxide nanoparticles. • Nanoparticles of tin oxide doped with different iodine concentrations. • Degradation studies carried up with UV–vis, TOC, HPLC and GC instruments. • 1% iodine doped tin dioxide showed maximum photodegradation efficiency. - Abstract: Iodine doped tin oxide (SnO{sub 2}:I) nanoparticles were prepared by sol–gel synthesis and their photocatalytic activities with phenol as a test contaminant were studied. In the presence of the catalysts, phenol degradation under direct sunlight was comparable to what was achieved under laboratory conditions. Photocatalytic oxidation reactions were studied by varying the catalyst loading, light intensity, illumination time, pH of the reactant and phenol concentration. Upon UV irradiation in the presence of SnO{sub 2}:I nanoparticles, phenol degrades very rapidly within 30 min, forming carboxylic acid which turns the solution acidic. Phenol degradation rate with 1% iodine doped SnO{sub 2} nanoparticles is at least an order of magnitude higher compared to the degradation achieved through undoped SnO{sub 2} nanoparticles under similar illumination conditions.

  14. Effect of reaction temperature on structure and fluorescence properties of nitrogen-doped carbon dots

    Science.gov (United States)

    Zhang, Yi; Wang, Yaling; Feng, Xiaoting; Zhang, Feng; Yang, Yongzhen; Liu, Xuguang

    2016-11-01

    To investigate the effect of reaction temperature and nitrogen doping on the structure and fluorescence properties of carbon dots (CDs), six kinds of nitrogen-doped CDs (NCDs) were synthesized at reaction temperatures of 120, 140, 160, 180, 200 and 220 °C, separately, by using citric acid as carbon source and ammonia solution as nitrogen source. Nitrogen-free CDs (N-free CDs-180) was also prepared at 180 °C by using citric acid as the only carbon source for comparison. Results show that reaction temperature has obvious effect on carbonization degree, quantum yield (QY), ultraviolet-visible (UV-vis) absorption and photoluminescence (PL) spectra but less effect on functional groups, nitrogen doping degree and fluorescence lifetime of NCDs. Compared with N-free CDs-180, NCDs-180 possesses enchanced QY and longer fluorescence lifetime. Doping nitrogen has obvious effect on UV-vis absorption and PL spectra but less effect on particles sizes and carbonization degree. The formation mechanism of NCDs is explored: QY of NCDs depends largely on the number of fluorescent polymer chains (FPC), the competition between FPC formation on the surface of NCDs and carbon core growth leads to the change in number of FPC, and consequently to the NCDs with highest QY at appropriate hydrothermal temperature.

  15. Photoinduced hydroxyl radical and photocatalytic activity of samarium-doped TiO(2) nanocrystalline.

    Science.gov (United States)

    Xiao, Qi; Si, Zhichun; Zhang, Jiang; Xiao, Chong; Tan, Xiaoke

    2008-01-15

    Sm(3+)-doped TiO(2) nanocrystalline has been prepared by sol-gel auto-combustion technique and characterized by X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET) method, and also UV-vis diffuse reflectance spectroscopy (DRS). These Sm(3+)-doped TiO(2) samples were tested for methylene blue (MB) decomposition and *OH radical formation. The analysis of *OH radical formation on the sample surface under UV irradiation was performed by fluorescence technique with using terephthalic acid, which readily reacted with *OH radical to produce highly fluorescent product, 2-hydroxyterephthalic acid. It was observed that the presence of Sm(3+) ion as a dopant significantly enhanced the photocatalytic activity for MB degradation under UV light irradiation because both the larger specific surface area and the greater the formation rate of *OH radical were simultaneously obtained for Sm(3+)-doped TiO(2) nanocrystalline. The adsorption experimental demonstrated that Sm(3+)-TiO(2) had a higher MB adsorption capacity than undoped TiO(2) and the adsorption capacity of MB increased with the increase of samarium ion content. The results also indicated that the greater the formation rate of *OH radical was, the higher photocatalytic activity was achieved. In this study, the optimum amount of Sm(3+) doping was 0.5 mol%, at which the recombination of photo-induced electrons and holes could be effectively inhibited, the highest formation rate of *OH radicals was, and thereby the highest photocatalytic activity was achieved.

  16. Hydrothermal fabrication of selectively doped organic assisted advanced ZnO nanomaterial for solar driven photocatalysis.

    Science.gov (United States)

    Namratha, K; Byrappa, K; Byrappa, S; Venkateswarlu, P; Rajasekhar, D; Deepthi, B K

    2015-08-01

    Hydrothermal fabrication of selectively doped (Ag(+)+Pd(3+)) advanced ZnO nanomaterial has been carried out under mild pressure temperature conditions (autogeneous; 150°C). Gluconic acid has been used as a surface modifier to effectively control the particle size and morphology of these ZnO nanoparticles. The experimental parameters were tuned to achieve optimum conditions for the synthesis of selectively doped ZnO nanomaterials with an experimental duration of 4 hr. These selectively doped ZnO nanoparticles were characterized using powder X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), UV-Vis spectroscopy and scanning electron microscopy (SEM). The solar driven photocatalytic studies have been carried out for organic dyes, i.e., Procion MX-5B dye, Cibacron Brilliant Yellow dye, Indigo Carmine dye, separately and all three mixed, by using gluconic acid modified selectively doped advanced ZnO nanomaterial. The influence of catalyst, its concentration and initial dye concentration resulted in the photocatalytic efficiency of 89% under daylight.

  17. The importance of cooling of urine samples for doping analysis

    NARCIS (Netherlands)

    Kuenen, J. Gijs; Konings, Wil N.

    2010-01-01

    Storing and transporting of urine samples for doping analysis, as performed by the anti-doping organizations associated with the World Anti-Doping Agency, does not include a specific protocol for cooled transport from the place of urine sampling to the doping laboratory, although low cost cooling fa

  18. The importance of cooling of urine samples for doping analysis

    NARCIS (Netherlands)

    Kuenen, J.G.; Konings, W.N.

    2009-01-01

    Storing and transporting of urine samples for doping analysis, as performed by the anti-doping organizations associated with the World Anti-Doping Agency, does not include a specific protocol for cooled transport from the place of urine sampling to the doping laboratory, although low cost cooling fa

  19. Carbon doping of GaAs NWs

    Science.gov (United States)

    Salehzadeh Einabad, Omid

    Nanowires (NWs) have been proposed and demonstrated as the building blocks for nanoscale electronic and photonic devices such as NW field effect transistors and NW solar cells which rely on doping and trap-free carrier transport. Controlled doping of NWs and a high degree of structure and morphology control are required for device applications. However, doping of III-V nanowires such as GaAs nanowires has not been reported extensively in the literature. Carbon is a well known p-type dopant in planar GaAs due to its low diffusivity and high solubility in bulk GaAs; however its use as an intentional dopant in NW growth has not yet been investigated. In this work we studied the carbon doping of GaAs nanowires using CBr4 as the dopant source. Gold nanoparticles (NP) at the tip ofthe NWs have been used to drive the NW growth. We show that carbon doping suppresses the migration ofthe gold NPs from the tip of the NWs. In addition, we show that the carbon doping of GaAs NWs is accompanied by an increase of the axial growth rate and decrease of the lateral growth rate ofthe NWs. Carbon-doped GaAs NWs, unlike the undoped ones which are highly tapered, are rod-like. The origin of the observed morphological changes is attributed to the carbon adsorbates on the sidewalls ofthe nanowires which suppress the lateral growth of the nanowires and increase the diffusion length of the gallium adatoms on the sidewalls. Stacking fault formation consisting of alternating regIOns of zincblende and wurtzite structures has been commonly observed in NWs grown along the (111) direction. In this work, based on transmission electron microscopy (TEM) analysis, we show that carbon doping ofGaAs NWs eliminates the stacking fault formation. Raman spectroscopy was used to investigate the effects of carbon doping on the vibrational properties of the carbon-doped GaAs nanowires. Carbon doping shows a strong impact on the intrinsic longitudinal and transverse optical (La and TO) modes of the Ga

  20. Planar doped barrier subharmonic mixers

    Science.gov (United States)

    Lee, T. H.; East, J. R.; Haddad, G. I.

    1992-01-01

    The Planar Doped Barrier (PDB) diode is a device consisting of a p(+) doping spike between two intrinsic layers and n(+) ohmic contacts. This device has the advantages of controllable barrier height, diode capacitance and forward to reverse current ratio. A symmetrically designed PDB has an anti-symmetric current vs. voltage characteristic and is ideal for use as millimeter wave subharmonic mixers. We have fabricated such devices with barrier heights of 0.3, 0.5 and 0.7 volts from GaAs and InGaAs using a multijunction honeycomb structure with junction diameters between one and ten microns. Initial RF measurements are encouraging. The 0.7 volt barrier height 4 micron GaAs devices were tested as subharmonic mixers at 202 GHz with an IF frequency of 1 GHz and had 18 dB of conversion loss. The estimated mismatch loss was 7 dB and was due to higher diode capacitance. The LO frequency was 100.5 GHz and the pump power was 8 mW.

  1. A Stability Study of Alkali Doped PBI Membranes for Alkaline Electrolyzer Cells

    DEFF Research Database (Denmark)

    Jensen, Jens Oluf; Aili, David; Hansen, Martin Kalmar;

    2014-01-01

    Polybenzimidazole membranes in a linear, a crosslinked and a thermally cured form were subjected to aging in 6 M aqueous KOH at 85 ºC for periods of up to 176 days. The aged membranes were characterized with respect to weight loss, mechanical properties and ionic conductivity. The area specific...... conductivity was similar to a commercial Zirfon membrane and suitable for a water electrolyzer. Some chemical degradation was seen during the aging period, but the crosslinked and the cured materials were both integral after 176 days of aging. A simplified electrolyzer test cell was operated successfully....

  2. Ce-doped titania nanoparticles: The effects of doped amount and calcination temperature on photocatalytic activity

    Science.gov (United States)

    Shi, Jianwen; Zou, Yajun; Ma, Dandan

    2017-01-01

    A series of Ce-doped TiO2 nanoparticles with different doped amount and calcination temperature were prepared by sol-gel method. These obtained samples were characterized with X-ray diffraction (XRD), transmission electron microscope (TEM) and ultraviolet-visible diffuse reflectance spectra (DRS), and their photocatalytic activities were evaluated by the photocatalytic degradation of methyl orange. Results showed that Ce doping inhibits the growth of crystal size and the phase transformation from anatase to rutile, leads to lattice distortion and expansion of TiO2. Furthermore, Ce doping brings the red-shift of absorption profile and the increase of photons absorption in the range of 400-600 nm. Photocatalytic degradation of methyl orange shows that Ce doping improves the photocatalytic activity of TiO2. The optimal doped amount is 0.05 mol% and the optimal calcined temperature is 600 °C for the maximum photocatalytic degradation efficiency in our experiment.

  3. Preparation and improved electrical performance of the Pr-doped CaMnO3-δ thermoelectric compound

    Science.gov (United States)

    Zhang, F. P.; Lu, Q. M.; Zhang, X.; Zhang, J. X.

    2013-09-01

    The rare earth Pr-doped Ca1-xPrxMnO3-δ (0 ⩽ x ⩽ 0.14) compound bulk samples are fabricated by citrate acid sol-gel combined with the ceramic preparation method. The effects of Pr doping on the structural and electrical transport properties of CaMnO3-δ within the high-temperature region are investigated in detail. The results show that single orthorhombic compounds can be formed in the experimental doping region. The remarkably reduced electrical resistivity is observed for the doped samples with the minimum value 3.90 mΩ cm at 373 K for the x = 0.14 sample; the absolute value of the Seebeck coefficient is decreased due to electron carrier concentration enhancement. The electrical properties of the doped samples are optimized compared with that of the parent sample, and the x = 0.08 sample is found to have the largest power factor value of 0.334 mW m-1 K-2 at 873 K. It is confirmed from the investigation that the electrical performance could be improved remarkably by rare earth Pr doping at a lower content.

  4. Photocatalytic degradation of humic substances in aqueous solution using Cu-doped ZnO nanoparticles under natural sunlight irradiation.

    Science.gov (United States)

    Maleki, Afshin; Safari, Mahdi; Shahmoradi, Behzad; Zandsalimi, Yahya; Daraei, Hiua; Gharibi, Fardin

    2015-11-01

    In this study, Cu-doped ZnO nanoparticles were investigated as an efficient synthesized catalyst for photodegradation of humic substances in aqueous solution under natural sunlight irradiation. Cu-doped ZnO nanocatalyst was prepared through mild hydrothermal method and was characterized using FT-IR, powder XRD and SEM techniques. The effect of operating parameters such as doping ratio, initial pH, catalyst dosage, initial concentrations of humic substances and sunlight illuminance were studied on humic substances degradation efficiency. The results of characterization analyses of samples confirmed the proper synthesis of Cu-doped ZnO nanocatalyst. The experimental results indicated the highest degradation efficiency of HS (99.2%) observed using 1.5% Cu-doped ZnO nanoparticles at reaction time of 120 min. Photocatalytic degradation efficiency of HS in a neutral and acidic pH was much higher than that at alkaline pH. Photocatalytic degradation of HS was enhanced with increasing the catalyst dosage and sunlight illuminance, while increasing the initial HS concentration led to decrease in the degradation efficiency of HS. Conclusively, Cu-doped ZnO nanoparticles can be used as a promising and efficient catalyst for degradation of HS under natural sunlight irradiation.

  5. Phosphorus doped TiO{sub 2} as oxygen sensor with low operating temperature and sensing mechanism

    Energy Technology Data Exchange (ETDEWEB)

    Han, Zhizhong; Wang, Jiejie; Liao, Lan [Institute of Research on the Functional Materials, Yishan Campus, Fuzhou University, Fuzhou, Fujian 350002 (China); College of Chemistry and Chemical Engineering, Qishan Campus, Fuzhou University, Fuzhou, Fujian 350108 (China); Pan, Haibo, E-mail: hbpan@fzu.edu.cn [Institute of Research on the Functional Materials, Yishan Campus, Fuzhou University, Fuzhou, Fujian 350002 (China); College of Chemistry and Chemical Engineering, Qishan Campus, Fuzhou University, Fuzhou, Fujian 350108 (China); Shen, Shuifa [Institute of Research on the Functional Materials, Yishan Campus, Fuzhou University, Fuzhou, Fujian 350002 (China); College of Chemistry and Chemical Engineering, Qishan Campus, Fuzhou University, Fuzhou, Fujian 350108 (China); Chen, Jianzhong, E-mail: j.z.chen@fzu.edu.cn [College of Chemistry and Chemical Engineering, Qishan Campus, Fuzhou University, Fuzhou, Fujian 350108 (China)

    2013-05-15

    Nano-scale TiO{sub 2} powders doped with phosphorus were prepared by sol–gel method. The characterization of the materials was performed by XRD, BET, FT-IR spectroscopy, Zeta potential measurement and XPS analysis. The results indicate that the phosphorus suppresses the crystal growth and phase transformation and, at the same time, increases the surface area and enhances the sensitivity and selectivity for the P-doped TiO{sub 2} oxygen sensors. In this system, the operating temperature is low, only 116 °C, and the response time is short. The spectra of FT-IR and XPS show that the phosphorus dopant presents as the pentavalent-oxidation state in TiO{sub 2}, further phosphorus can connect with Ti{sup 4+} through the bond of Ti-O-P. The positive shifts of XPS peaks indicate that electron depleted layer of P-doped TiO{sub 2} is narrowed compared with that of pure TiO{sub 2}, and the results of Zeta potential illuminate that the density of surface charge carrier is intensified. The adsorptive active site and Lewis acid characteristics of the surface are reinforced by phosphorus doping, where phosphorus ions act as a new active site. Thus, the sensitivity of P-doped TiO{sub 2} is improved, and the 5 mol% P-doped sample has the optimal oxygen sensing properties.

  6. Conversion of ethanol to 1,3-butadiene over Na doped ZnxZryOz mixed metal oxides

    Energy Technology Data Exchange (ETDEWEB)

    Baylon, Rebecca A.; Sun, Junming; Wang, Yong

    2016-01-01

    Despite numerous studies on different oxide catalysts for the ethanol to 1,3-butadiene reaction, few have identified active sites (i.e., type of acidity) correlated to the catalytic performances. In this work, the type of acidity needed for ethanol to 1,3-butadiene conversion has been studied over Zn/Zr mixed oxide catalysts. Specifically, synthesis method, Zn/Zr ratio, and Na doping have been used to control the surface acid-base properties, as confirmed by characterizations such as NH3-TPD and IR-Py techniques. The 2000 ppm Na doped Zn1Zr10Oz-H with balanced base and weak Bronsted acid sites was found to give not only high selectivity to 1,3-butadiene (47%) at near complete ethanol conversion (97%), but also exhibited a much higher 1,3-butadiene productivity than other mixed oxides studied.

  7. Nanosized alkali-metal-doped ethoxotitanate clusters.

    Science.gov (United States)

    Chen, Yang; Trzop, Elzbieta; Makal, Anna; Sokolow, Jesse D; Coppens, Philip

    2013-05-06

    The synthesis and crystallographic characterization of alkali-metal-doped ethoxotitanate clusters with 28 and 29 Ti atoms as well as a new dopant-free Ti28 cluster are presented. The light-metal-doped polyoxotitanate clusters in which the alkali-metal atom is the critical structure-determining component are the largest synthesized so far. Calculations show that doping with light alkali atoms narrows the band gap compared with the nondoped crystals but does not introduce additional energy levels within the band gap.

  8. Double Clad Er-doped Fiber Amplifier

    Institute of Scientific and Technical Information of China (English)

    FU Yong-jun; MAO Xiang-qiao; WEI Huai; LI jian

    2007-01-01

    Presented is a theoretical study of double-clad Er-doped fiber power amplifier(EDFA). Two kinds of double clad fibers(DCF) with rectangular and "flower" inner clad shapes are studied, and these fibers have different coupling constants and propagation losses. We calculate the effective pump power absorption ratio along the fiber with different coupling constants from the first cladding to the doped core and with different propagation losses for the power in the inner cladding. Then the gains of the double clad Er-doped fiber amplifiers versus fiber lengths are calculated using the EDFA model based on propagation and rate equations of a homogeneous, two-level medium.

  9. Alternative medicine and doping in sports.

    Science.gov (United States)

    Koh, Benjamin; Freeman, Lynne; Zaslawski, Christopher

    2012-01-01

    Athletes are high achievers who may seek creative or unconventional methods to improve performance. The literature indicates that athletes are among the heaviest users of complementary and alternative medicine (CAM) and thus may pioneer population trends in CAM use. Unlike non-athletes, athletes may use CAM not just for prevention, treatment or rehabilitation from illness or injuries, but also for performance enhancement. Assuming that athletes' creative use of anything unconventional is aimed at "legally" improving performance, CAM may be used because it is perceived as more "natural" and erroneously assumed as not potentially doping. This failure to recognise CAMs as pharmacological agents puts athletes at risk of inadvertent doping.The general position of the World Anti-Doping Authority (WADA) is one of strict liability, an application of the legal proposition that ignorance is no excuse and the ultimate responsibility is on the athlete to ensure at all times whatever is swallowed, injected or applied to the athlete is both safe and legal for use. This means that a violation occurs whether or not the athlete intentionally or unintentionally, knowingly or unknowingly, used a prohibited substance/method or was negligent or otherwise at fault. Athletes are therefore expected to understand not only what is prohibited, but also what might potentially cause an inadvertent doping violation. Yet, as will be discussed, athlete knowledge on doping is deficient and WADA itself sometimes changes its position on prohibited methods or substances. The situation is further confounded by the conflicting stance of anti-doping experts in the media. These highly publicised disagreements may further portray inconsistencies in anti-doping guidelines and suggest to athletes that what is considered doping is dependent on the dominant political zeitgeist. Taken together, athletes may believe that unless a specific and explicit ruling is made, guidelines are open to interpretation

  10. Gas Immersion Laser Doping for superconducting nanodevices

    Energy Technology Data Exchange (ETDEWEB)

    Chiodi, F. [Institut d’Electronique Fondamentale, CNRS-Université Paris-Sud, F-91405 Orsay (France); Grockowiak, A. [Institut Néel, CNRS, BP 166, F-38042 Grenoble (France); CEA, INAC, UMR-E9001/UJF, LATEQS, 17 Rue des Martyrs, F-38054 Grenoble (France); Duvauchelle, J.E. [CEA, INAC, UMR-E9001/UJF, LATEQS, 17 Rue des Martyrs, F-38054 Grenoble (France); Fossard, F. [Institut d’Electronique Fondamentale, CNRS-Université Paris-Sud, F-91405 Orsay (France); Lefloch, F. [CEA, INAC, UMR-E9001/UJF, LATEQS, 17 Rue des Martyrs, F-38054 Grenoble (France); Klein, T. [Institut Néel, CNRS, BP 166, F-38042 Grenoble (France); Marcenat, C. [CEA, INAC, UMR-E9001/UJF, LATEQS, 17 Rue des Martyrs, F-38054 Grenoble (France); Institut Néel, CNRS, BP 166, F-38042 Grenoble (France); Débarre, D. [Institut d’Electronique Fondamentale, CNRS-Université Paris-Sud, F-91405 Orsay (France)

    2014-05-01

    We have conceived and fabricated Superconductor/Normal metal/Superconductor Josephson junctions made entirely of boron doped Silicon. We have used Gas Immersion Laser Doping to fabricate SN bilayers with good ohmic interfaces and well controlled concentration and doping depth. Standard fabrication processes, optimised for silicon, were employed to nanostructure the bilayers without affecting their transport properties. The junctions thus fabricated are proximity superconducting and show well understood I–V characteristics. This research opens the road to all-silicon, non-dissipative, Josephson Field Effect Transistors.

  11. Gene doping: the hype and the harm.

    Science.gov (United States)

    McKanna, Trudy A; Toriello, Helga V

    2010-06-01

    "Gene doping" is the term used to describe the potential abuse of gene therapy as a performance-enhancing agent. Gene doping would apply the techniques used in gene therapy to provide altered expression of genes that would promote physical superiority. For example, insulin-like growth factor 1 (IGF-1) is a primary target for growth hormone; overexpression of IGF-1 can lead to increased muscle mass and power. Although gene doping is still largely theoretical, its implications for sports, health, ethics, and medical genetics are significant.

  12. Alternative medicine and doping in sports

    Directory of Open Access Journals (Sweden)

    Benjamin Koh

    2012-01-01

    Full Text Available Athletes are high achievers who may seek creative or unconventional methods to improve performance. The literature indicates that athletes are among the heaviest users of complementary and alternative medicine (CAM and thus may pioneer population trends in CAM use. Unlike non-athletes, athletes may use CAM not just for prevention, treatment or rehabilitation from illness or injuries, but also for performance enhancement. Assuming that athletes’ creative use of anything unconventional is aimed at “legally” improving performance, CAM may be used because it is perceived as more “natural” and erroneously assumed as not potentially doping. This failure to recognise CAMs as pharmacological agents puts athletes at risk of inadvertent doping.The general position of the World Anti-Doping Authority (WADA is one of strict liability, an application of the legal proposition that ignorance is no excuse and the ultimate responsibility is on the athlete to ensure at all times whatever is swallowed, injected or applied to the athlete is both safe and legal for use. This means that a violation occurs whether or not the athlete intentionally or unintentionally, knowingly or unknowingly, used a prohibited substance/method or was negligent or otherwise at fault. Athletes are therefore expected to understand not only what is prohibited, but also what might potentially cause an inadvertent doping violation. Yet, as will be discussed, athlete knowledge on doping is deficient and WADA itself sometimes changes its position on prohibited methods or substances. The situation is further confounded by the conflicting stance of anti-doping experts in the media. These highly publicised disagreements may further portray inconsistencies in anti-doping guidelines and suggest to athletes that what is considered doping is dependent on the dominant political zeitgeist. Taken together, athletes may believe that unless a specific and explicit ruling is made, guidelines are

  13. Anodic oxidation with doped diamond electrodes: a new advanced oxidation process

    Energy Technology Data Exchange (ETDEWEB)

    Kraft, Alexander; Stadelmann, Manuela; Blaschke, Manfred

    2003-10-31

    Boron-doped diamond anodes allow to directly produce OH{center_dot} radicals from water electrolysis with very high current efficiencies. This has been explained by the very high overvoltage for oxygen production and many other anodic electrode processes on diamond anodes. Additionally, the boron-doped diamond electrodes exhibit a high mechanical and chemical stability. Anodic oxidation with diamond anodes is a new advanced oxidation process (AOP) with many advantages compared to other known chemical and photochemical AOPs. The present work reports on the use of diamond anodes for the chemical oxygen demand (COD) removal from several industrial wastewaters and from two synthetic wastewaters with malic acid and ethylenediaminetetraacetic (EDTA) acid. Current efficiencies for the COD removal between 85 and 100% have been found. The formation and subsequent removal of by-products of the COD oxidation has been investigated for the first time. Economical considerations of this new AOP are included.

  14. Green synthesis of boron doped graphene and its application as high performance anode material in Li ion battery

    Energy Technology Data Exchange (ETDEWEB)

    Sahoo, Madhumita; Sreena, K.P.; Vinayan, B.P.; Ramaprabhu, S., E-mail: ramp@iitm.ac.in

    2015-01-15

    Graphical abstract: Boron doped graphene (B-G), synthesized by simple hydrogen induced reduction technique using boric acid as boron precursor, have more uneven surface as a result of smaller bonding distance of boron compared to carbon, showed high capacity and high rate capability compared to pristine graphene as an anode material for Li ion battery application. - Abstract: The present work demonstrates a facile route for the large-scale, catalyst free, and green synthesis approach of boron doped graphene (B-G) and its use as high performance anode material for Li ion battery (LIB) application. Boron atoms were doped into graphene framework with an atomic percentage of 5.93% via hydrogen induced thermal reduction technique using graphite oxide and boric acid as precursors. Various characterization techniques were used to confirm the boron doping in graphene sheets. B-G as anode material shows a discharge capacity of 548 mAh g{sup −1} at 100 mA g{sup −1} after 30th cycles. At high current density value of 1 A g{sup −1}, B-G as anode material enhances the specific capacity by about 1.7 times compared to pristine graphene. The present study shows a simplistic way of boron doping in graphene leading to an enhanced Li ion adsorption due to the change in electronic states.

  15. Borohydride electro-oxidation by Ag-doped lanthanum chromites

    Indian Academy of Sciences (India)

    S Suresh Balaji; A Usha; V V Giridhar

    2014-05-01

    The electrocatalytic activity of Ag-doped lanthanum chromites electrode materials viz., LaCr0.4Ag0.6O3 and LaCr0.7Ag0.3O3 prepared by decomposing the precursor complex is studied. Pure LaCrO3 is synthesized by combustion route using oxalic acid as a fuel. The decomposition behaviour of the assynthesized powder obtained in the latter method is characterized by TGA-DTA and XRD. Both the precursor complex and the as-synthesized powder are calcined at 900°C for 7 and 10 h, respectively. XRD of the final product after calcinations indicated the formation of perovskite phase with minor amounts of impurity phases of component oxides in the Ag-doped lanthanum chromites and pure perovskite phase in the undoped one. The surface morphology of the perovskites is studied by SEM. The electrocatalytic activity of the perovskite powders for borohydride oxidation is studied by using cyclic voltammetry (CV) at a catalyst loading of 0.7 mgcm−2 for both Ag-doped and undoped LaCrO3 coated on glassy carbon substrate. Calibration plots are obtained by plotting the anodic peak current versus concentration of borohydride in the range of 20-100 mM. The sensitivities of the three perovskites towards borohydride oxidation indicated that LaCr0.4Ag0.6O3 is the best among all the perovskites studied giving a value of 1.395 A/mM.

  16. Sulphur mustard degradation on zirconium doped Ti-Fe oxides

    Energy Technology Data Exchange (ETDEWEB)

    Stengl, Vaclav, E-mail: stengl@iic.cas.cz [Department of Solid State Chemistry, Institute of Inorganic Chemistry AS CR v.v.i 250 68 Husinec-Rez (Czech Republic); Grygar, Tomas Matys [Department of Solid State Chemistry, Institute of Inorganic Chemistry AS CR v.v.i 250 68 Husinec-Rez (Czech Republic); Oplustil, Frantisek; Nemec, Tomas [Military Technical Institute of Protection Brno Veslarska 230, 628 00 Brno (Czech Republic)

    2011-09-15

    Highlights: {yields} New stechiometric materials for sulphur mustard degradation. {yields} High degree of degradation, more then 95% h{sup -1}. {yields} One-pot synthesis procedure. - Abstract: Zirconium doped mixed nanodispersive oxides of Ti and Fe were prepared by homogeneous hydrolysis of sulphate salts with urea in aqueous solutions. Synthesized nanodispersive metal oxide hydroxides were characterised as the Brunauer-Emmett-Teller (BET) surface area and Barrett-Joiner-Halenda porosity (BJH), X-ray diffraction (XRD), infrared (IR) spectroscopy, scanning electron microscopy (SEM) with energy-dispersive X-ray (EDX) microanalysis, and acid-base titration. These oxides were taken for an experimental evaluation of their reactivity with sulphur mustard (chemical warfare agent HD or bis(2-chloroethyl)sulphide). The presence of Zr{sup 4+} dopant tends to increase both the surface area and the surface hydroxylation of the resulting doped oxides in such a manner that it can contribute to enabling the substrate adsorption at the oxide surface and thus accelerate the rate of degradation of warfare agents. The addition of Zr{sup 4+} to the hydrolysis of ferric sulphate with urea shifts the reaction route and promotes formation of goethite at the expense of ferrihydrite. We discovered that Zr{sup 4+} doped oxo-hydroxides of Ti and Fe exhibit a higher degradation activity towards sulphur mustard than any other yet reported reactive sorbents. The reaction rate constant of the slower parallel reaction of the most efficient reactive sorbents is increased with the increasing amount of surface base sites.

  17. Piezoresistive boron doped diamond nanowire

    Science.gov (United States)

    Sumant, Anirudha V.; Wang, Xinpeng

    2016-09-13

    A UNCD nanowire comprises a first end electrically coupled to a first contact pad which is disposed on a substrate. A second end is electrically coupled to a second contact pad also disposed on the substrate. The UNCD nanowire is doped with a dopant and disposed over the substrate. The UNCD nanowire is movable between a first configuration in which no force is exerted on the UNCD nanowire and a second configuration in which the UNCD nanowire bends about the first end and the second end in response to a force. The UNCD nanowire has a first resistance in the first configuration and a second resistance in the second configuration which is different from the first resistance. The UNCD nanowire is structured to have a gauge factor of at least about 70, for example, in the range of about 70 to about 1,800.

  18. Ion Doped Quantum Well Lasers

    Science.gov (United States)

    1993-04-01

    5 3 TGA analysis of {N[Si(CH3)312)3Er ................................. 5 4 Spectroscopic analysis of {N[Si(CH3)3]2)3Er...40o 56o 6oo TEMPERATURE (-C) Figure 3 TGA analysis of Er{NISi(CH3)3J]J 3 . CHEMICAL VAPOR DEPOSITION As the objective of this work is to dope A1GaAs...laO0 23633 47.870C 99.37% 1,14.84*C s00, • 95.212 173.75C 90.622 EI 800.77C 20- 60- 2o256. tC 0 i9o 360 460 560 600 TEMPERATURE (’C) Figure 3 TGA

  19. Photoelectrochemical reduction of carbon dioxide using Ge doped GaN nanowire photoanodes

    Directory of Open Access Journals (Sweden)

    Yichen Wang

    2015-11-01

    Full Text Available We report on the direct conversion of carbon dioxide (CO2 in a photoelectrochemical cell consisting of germanium doped gallium nitride nanowire anode and copper (Cu cathode. Various products including methane (CH4, carbon monoxide (CO, and formic acid (HCOOH were observed under light illumination. A Faradaic efficiency of ∼10% was measured for HCOOH. Furthermore, this photoelectrochemical system showed enhanced stability for 6 h CO2 reduction reaction on low cost, large area Si substrates.

  20. Amperometric Determination of Sulfite by Gas Diffusion-Sequential Injection with Boron-Doped Diamond Electrode

    OpenAIRE

    Orawon Chailapakul; Toshihiko Imato; Narong Praphairaksit; Kulwadee Pinwattana; Chakorn Chinvongamorn

    2008-01-01

    A gas diffusion sequential injection system with amperometric detection using aboron-doped diamond electrode was developed for the determination of sulfite. A gasdiffusion unit (GDU) was used to prevent interference from sample matrices for theelectrochemical measurement. The sample was mixed with an acid solution to generategaseous sulfur dioxide prior to its passage through the donor channel of the GDU. Thesulfur dioxide diffused through the PTFE hydrophobic membrane into a carrier solution...

  1. Design and Synthesis of Cross-Linked Copolymer Membranes Based on Poly(benzoxazine and Polybenzimidazole and Their Application to an Electrolyte Membrane for a High-Temperature PEM Fuel Cell

    Directory of Open Access Journals (Sweden)

    Hyuk Chang

    2013-01-01

    Full Text Available Elevated-temperature (100~200 °C polymer electrolyte membrane (PEM fuel cells have many features, such as their high efficiency and simple system design, that make them ideal for residential micro-combined heat and power systems and as a power source for fuel cell electric vehicles. A proton-conducting solid-electrolyte membrane having high conductivity and durability at elevated temperatures is essential, and phosphoric-acid-containing polymeric material synthesized from cross-linked polybenzoxazine has demonstrated feasible characteristics. This paper reviews the design rules, synthesis schemes, and characteristics of this unique polymeric material. Additionally, a membrane electrode assembly (MEA utilizing this polymer membrane is evaluated in terms of its power density and lifecycle by an in situ accelerated lifetime test. This paper also covers an in-depth discussion ranging from the polymer material design to the cell performance in consideration of commercialization requirements.

  2. Screening dynamics in doped titanates

    Energy Technology Data Exchange (ETDEWEB)

    Rubensson, J.E.; Luening, J.; Eisebitt, S. [Forschungszentrum Juelich (Germany)] [and others

    1997-04-01

    The time scale for carrier relaxation in semiconductors is on the same order of magnitude as the life time of shallow core hole states (a few femtoseconds). Resonant Inelastic soft X-ray scattering (RIXS) which involves (virtual) excitations of core levels consequently contains information about the time development of the electronic structure on this time scale. In many cases one can treat the scattering in an absorption (SXA) followed-by-emission (SXE) picture, where simply the rates for various processes can be compared with the intermediate core hole state decay rate as an internal {open_quotes}clock{close_quotes}. By variation of x (0 < x < 1) in La{sub x}Sr{sub 1{minus}x}TiO{sub 3}, the amount of Ti d electrons in the system can be controlled. SrTiO{sub 3} (x=0) is an insulator with an empty Ti d band. With increasing x, electrons are doped into the Ti d-band, and LaTiO{sub 3} (x=1) is a Mott Hubbard insulator with a Ti 3d{sup 1} configuration. In this work the authors demonstrate that the rate for Ti 2p core hole screening in La{sub x}Sr{sub 1{minus}x}TiO{sub 3} is doping dependent. The screening rate increases with the availability of Ti 3d electrons, and they estimate it to be 3.8 x 10{sup 13}/sec in La{sub 0.05}Sr{sub 0.95}TiO{sub 3}.

  3. Active Optical Fibers Doped with Ceramic Nanocrystals

    Directory of Open Access Journals (Sweden)

    Jan Mrazek

    2014-01-01

    Full Text Available Erbium-doped active optical fiber was successfully prepared by incorporation of ceramic nanocrystals inside a core of optical fiber. Modified chemical vapor deposition was combined with solution-doping approach to preparing preform. Instead of inorganic salts erbium-doped yttrium-aluminium garnet nanocrystals were used in the solution-doping process. Prepared preform was drawn into single-mode optical fiber with a numerical aperture 0.167. Optical and luminescence properties of the fiber were analyzed. Lasing ability of prepared fiber was proofed in a fiber-ring set-up. Optimal laser properties were achieved for a fiber length of 20~m. The slope efficiency of the fiber-laser was about 15%. Presented method can be simply extended to the deposition of other ceramic nanomaterials.

  4. Sprayed lanthanum doped zinc oxide thin films

    Energy Technology Data Exchange (ETDEWEB)

    Bouznit, Y., E-mail: Bouznit80@gmail.com [Laboratory of Materials Study, Jijel University, Jijel 18000 (Algeria); Beggah, Y. [Laboratory of Materials Study, Jijel University, Jijel 18000 (Algeria); Ynineb, F. [Laboratory of Thin Films and Interface, University Mentouri, Constantine 25000 (Algeria)

    2012-01-15

    Lanthanum doped zinc oxide thin films were deposited on soda-lime glass substrates using a pneumatic spray pyrolysis technique. The films were prepared using different lanthanum concentrations at optimum deposition parameters. We studied the variations in structural, morphological and optical properties of the samples due to the change of doping concentration in precursor solutions. X-ray diffraction (XRD) patterns show that pure and La-doped ZnO thin films are highly textured along c-axis perpendicular to the surface of the substrate. Scanning electron micrographs show that surface morphology of ZnO films undergoes a significant change according to lanthanum doping. All films exhibit a transmittance higher than 80% in the visible region.

  5. Sprayed lanthanum doped zinc oxide thin films

    Science.gov (United States)

    Bouznit, Y.; Beggah, Y.; Ynineb, F.

    2012-01-01

    Lanthanum doped zinc oxide thin films were deposited on soda-lime glass substrates using a pneumatic spray pyrolysis technique. The films were prepared using different lanthanum concentrations at optimum deposition parameters. We studied the variations in structural, morphological and optical properties of the samples due to the change of doping concentration in precursor solutions. X-ray diffraction (XRD) patterns show that pure and La-doped ZnO thin films are highly textured along c-axis perpendicular to the surface of the substrate. Scanning electron micrographs show that surface morphology of ZnO films undergoes a significant change according to lanthanum doping. All films exhibit a transmittance higher than 80% in the visible region.

  6. Doped Colloidal ZnO Nanocrystals

    Directory of Open Access Journals (Sweden)

    Yizheng Jin

    2012-01-01

    Full Text Available Colloidal ZnO nanocrystals are promising for a wide range of applications due to the combination of unique multifunctional nature and remarkable solution processability. Doping is an effective approach of enhancing the properties of colloidal ZnO nanocrystals in well-controlled manners. In this paper, we analyzed two synthetic strategies for the doped colloidal ZnO nanocrystals, emphasizing our understanding on the critical factors associated with the high temperature and nonaqueous approach. Latest advances of three topics, bandgap engineering, n-type doping, and dilute magnetic semiconductors related to doped ZnO nanocrystals were discussed to reveal the effects of dopants on the properties of the nanocrystalline materials.

  7. Doping Scheme of Semiconducting Atomic Chains

    Science.gov (United States)

    Toshishige, Yamada; Saini, Subhash (Technical Monitor)

    1998-01-01

    Atomic chains, precise structures of atomic scale created on an atomically regulated substrate surface, are candidates for future electronics. A doping scheme for intrinsic semiconducting Mg chains is considered. In order to suppress the unwanted Anderson localization and minimize the deformation of the original band shape, atomic modulation doping is considered, which is to place dopant atoms beside the chain periodically. Group I atoms are donors, and group VI or VII atoms are acceptors. As long as the lattice constant is long so that the s-p band crossing has not occurred, whether dopant atoms behave as donors or acceptors is closely related to the energy level alignment of isolated atomic levels. Band structures are calculated for Br-doped (p-type) and Cs-doped (n-type) Mg chains using the tight-binding theory with universal parameters, and it is shown that the band deformation is minimized and only the Fermi energy position is modified.

  8. A Quarter Century of Doping Scandals

    DEFF Research Database (Denmark)

    Gleaves, John; Christiansen, Ask Vest

    2013-01-01

    With the ongoing doping scandals, revelations, and confessions, it was likely that few celebrated this autumn’s significant anniversary in doping history. Twenty-five years ago—September 26, 1988—news broke of the first major doping scandal in the Olympic Games. Canadian sprinter Ben Johnson, who...... just two days previously had won the 100 meter dash in a world record clip, had tested positive for the banned anabolic steroid stanozolol at the Seoul Olympics. Johnson was neither the first to use prohibited “doping” substances at the Olympics nor the first to get caught. Johnson’s case is notable...... because it marked the first time a high-profile athlete was unceremoniously stripped of his medal rather than having his results covered up or ignored. Johnson’s case is also useful for framing the ongoing issue with doping in elite sports while providing some insight into the current problem sport faces....

  9. Stabilization of boron carbide via silicon doping.

    Science.gov (United States)

    Proctor, J E; Bhakhri, V; Hao, R; Prior, T J; Scheler, T; Gregoryanz, E; Chhowalla, M; Giulani, F

    2015-01-14

    Boron carbide is one of the lightest and hardest ceramics, but its applications are limited by its poor stability against a partial phase separation into separate boron and carbon. Phase separation is observed under high non-hydrostatic stress (both static and dynamic), resulting in amorphization. The phase separation is thought to occur in just one of the many naturally occurring polytypes in the material, and this raises the possibility of doping the boron carbide to eliminate this polytype. In this work, we have synthesized boron carbide doped with silicon. We have conducted a series of characterizations (transmission electron microscopy, scanning electron microscopy, Raman spectroscopy and x-ray diffraction) on pure and silicon-doped boron carbide following static compression to 50 GPa non-hydrostatic pressure. We find that the level of amorphization under static non-hydrostatic pressure is drastically reduced by the silicon doping.

  10. Superconductivity in carrier-doped silicon carbide

    Directory of Open Access Journals (Sweden)

    Takahiro Muranaka, Yoshitake Kikuchi, Taku Yoshizawa, Naoki Shirakawa and Jun Akimitsu

    2008-01-01

    Full Text Available We report growth and characterization of heavily boron-doped 3C-SiC and 6H-SiC and Al-doped 3C-SiC. Both 3C-SiC:B and 6H-SiC:B reveal type-I superconductivity with a critical temperature Tc=1.5 K. On the other hand, Al-doped 3C-SiC (3C-SiC:Al shows type-II superconductivity with Tc=1.4 K. Both SiC:Al and SiC:B exhibit zero resistivity and diamagnetic susceptibility below Tc with effective hole-carrier concentration n higher than 1020 cm−3. We interpret the different superconducting behavior in carrier-doped p-type semiconductors SiC:Al, SiC:B, Si:B and C:B in terms of the different ionization energies of their acceptors.

  11. [High-performance society and doping].

    Science.gov (United States)

    Gallien, C L

    2002-09-01

    Doping is not limited to high-level athletes. Likewise it is not limited to the field of sports activities. The doping phenomenon observed in sports actually reveals an underlying question concerning the notion of sports itself, and more widely, the society's conception of sports. In a high-performance society, which is also a high-risk society, doping behavior is observed in a large number of persons who may or may not participate in sports activities. The motivation is the search for individual success or profit. The fight against doping must therefore focus on individual responsibility and prevention in order to preserve athlete's health and maintain the ethical and educational value of sports activities.

  12. Electrical transport and EPR investigations: A comparative study for d.c. conduction mechanism in monovalent and multivalent ions doped polyaniline

    Indian Academy of Sciences (India)

    Suresh Kumar Gupta; Vandna Luthra; Ramadhar Singh

    2012-10-01

    A detailed comparative study of electron paramagnetic resonance (EPR) in conjunction with d.c. electrical conductivity has been undertaken to know about the charge transport mechanism in polyaniline (PANI) doped with monovalent and multivalent protonic acids. This work is in continuation of our previous work for further understanding the conduction mechanism in conducting polymers. The results reveal that the polarons and bipolarons are the main charge carriers formed during doping process and these cause increase in electrical conductivity not only by increase in their concentration but also because of their enhanced mobility due to increased inter-chain transport in polyaniline at high doping levels. EPR line asymmetry having Dysonian line shape for highly doped samples shows a marked deviation of amplitudes / ratio from values close to one to much high values as usually observed in metals, thereby support the idea of high conductivity at higher doping levels. The nature of dopant ions and their doping levels control the charge carriers concentration as well as electrical conductivity of polyaniline. The electrical conductivity has also been studied as a function of temperature to know the thermally assisted transport process of these charge carriers at different doping levels which has been found to follow the Mott’s variable range hopping (VRH) conduction model for all the three dopants used. The charge carriers show a change over from 3D VRH to quasi 1D VRH hopping process for multivalent ions at higher doping levels whereas 1D VRH has been followed by monovalent ion for full doping range. These studies collectively give evidence of inter-chain percolation at higher doping levels causing increase in effective mobility of the charge carriers which mainly seems to govern the electrical conduction behaviour in this system.

  13. Luminescent dye-doped or rare-earth-doped monodisperse silica nanospheres as efficient labels in DNA microarrays

    Science.gov (United States)

    Enrichi, F.; Riccò, R.; Meneghello, A.; Pierobon, R.; Marinello, F.; Schiavuta, P.

    2009-08-01

    Luminescent nanoparticles are gaining more and more interest in bio-labeling and bio-imaging applications, like for example DNA microarray. This is a high-throughput technology used for detection and quantification of nucleic acid molecules and other ones of biological interest. The analysis is resulting by specific hybridization between probe sequences deposited in array and a target ss-DNA usually expressed by PCR and functionalized by a fluorescent dye. These organic labels have well known disadvantages like photobleaching and limited sensitivity. Quantum dots may be used as alternatives, but they present troubles like blinking, toxicity and excitation wavelengths out of the usual range of commercial instruments, lowering their efficiency. Therefore in this work we investigate a different strategy, based on the use of inorganic silica nanospheres incorporating standard luminescent dyes or rare earth doped nanocrystals. In the first case it is possible to obtain a high luminescence emission signal, due to the high number of dye molecules that can be accommodated into each nanoparticle, reduced photobleaching and environmental protection of the dye molecules thanks to the encapsulation in the silica matrix. In the second case, rare earths exhibit narrow emission bands (easy identification), large Stokes shifts (efficient discrimination of excitation and emission) and long luminescence lifetimes (possibility to perform time-delayed analysis) which can be efficiently used for the improvement of signal to noise ratio. The synthesis and characterization of good luminescent silica spheres either by organic dye-doping or by rare-earth-doping are investigated and reported. Moreover, their application in the DNA microarray technology in comparison to the use of standard molecular fluorophores or commercial quantum dots is discussed. The cheap and easy synthesis of these luminescent particles, the stability in water, the surface functionalization and bio

  14. Gene doping: gene delivery for olympic victory

    OpenAIRE

    2012-01-01

    With one recently recommended gene therapy in Europe and a number of other gene therapy treatments now proving effective in clinical trials it is feasible that the same technologies will soon be adopted in the world of sport by unscrupulous athletes and their trainers in so called ‘gene doping’. In this article an overview of the successful gene therapy clinical trials is provided and the potential targets for gene doping are highlighted. Depending on whether a doping gene product is secreted...

  15. Ultrafast THz Saturable Absorption in Doped Semiconductors

    DEFF Research Database (Denmark)

    Turchinovich, Dmitry; Hoffmann, Matthias C.

    2011-01-01

    We demonstrate ultrafast THz saturable absorption in n-doped semiconductors by nonlinear THz time-domain spectroscopy. This effect is caused by the semiconductor conductivity modulation due to electron heating and satellite-valley scattering in strong THz fields.......We demonstrate ultrafast THz saturable absorption in n-doped semiconductors by nonlinear THz time-domain spectroscopy. This effect is caused by the semiconductor conductivity modulation due to electron heating and satellite-valley scattering in strong THz fields....

  16. Detection of Doping with rhGH

    Institute of Scientific and Technical Information of China (English)

    Wu Mou-tian

    2009-01-01

    This presentation reviewed most articles recently pub lished in peer reviewed international scientific journals related to detection doping with rhGH. Four parts were in it: First part was the brief introduction about the background of do ping,special doping with rhGH. Second part summarized the development of "indirect method", markers approach. Third was focused on the development of "direct method", isoform approach. Finally, some potential alternatives have been discussed.

  17. Hole transport in pure and doped hematite

    Science.gov (United States)

    Liao, Peilin; Carter, Emily A.

    2012-07-01

    Hematite (α-Fe2O3) is a promising candidate for use in photovoltaic (PV) and photoelectrochemical devices. Its poor conductivity is one major drawback. Doping hematite either p-type or n-type greatly enhances its measured conductivity and is required for potential p-n junctions in PVs. Here, we study hole transport in pure and doped hematite using an electrostatically embedded cluster model with ab initio quantum mechanics (unrestricted Hartree-Fock theory). Consistent with previous work, the model suggests that hole hopping is via oxygen anions for pure hematite. The activation energy for hole mobility is predicted to be at least 0.1 eV higher than the activation energy for electron mobility, consistent with the trend observed in experiments. We examine four dopants—magnesium(II), nickel(II), copper(II), and manganese(II/III) in direct cation substitution sites—to gain insight into the mechanism by which conductivity is improved. The activation energies are used to assess qualitative effects of different dopants. The hole carriers are predicted to be attracted to O anions near the dopants. The magnitude of the trapping effect is similar among the four dopants in their +2 oxidation states. The multivalent character of Mn doping facilitates local hole transport around Mn centers via a low-barrier O-Mn-O pathway, which suggests that higher hole mobility can be achieved with increasing Mn doping concentration, especially when a network of these low-barrier pathways is produced. Our results suggest that the experimentally observed conductivity increase in Mg-, Ni-, and Cu-doped p-type hematite is mostly due to an increase in hole carriers rather than improved mobility, and that Mg-, Ni-, and Cu-doping perform similarly, while the conductivity of Mn-doped hematite might be significantly improved in the high doping concentration limit.

  18. Porous allograft bone scaffolds: doping with strontium.

    Directory of Open Access Journals (Sweden)

    Yantao Zhao

    Full Text Available Strontium (Sr can promote the process of bone formation. To improve bioactivity, porous allograft bone scaffolds (ABS were doped with Sr and the mechanical strength and bioactivity of the scaffolds were evaluated. Sr-doped ABS were prepared using the ion exchange method. The density and distribution of Sr in bone scaffolds were investigated by inductively coupled plasma optical emission spectrometry (ICP-OES, X-ray photoelectron spectroscopy (XPS, and energy-dispersive X-ray spectroscopy (EDS. Controlled release of strontium ions was measured and mechanical strength was evaluated by a compressive strength test. The bioactivity of Sr-doped ABS was investigated by a simulated body fluid (SBF assay, cytotoxicity testing, and an in vivo implantation experiment. The Sr molar concentration [Sr/(Sr+Ca] in ABS surpassed 5% and Sr was distributed nearly evenly. XPS analyses suggest that Sr combined with oxygen and carbonate radicals. Released Sr ions were detected in the immersion solution at higher concentration than calcium ions until day 30. The compressive strength of the Sr-doped ABS did not change significantly. The bioactivity of Sr-doped material, as measured by the in vitro SBF immersion method, was superior to that of the Sr-free freeze-dried bone and the Sr-doped material did not show cytotoxicity compared with Sr-free culture medium. The rate of bone mineral deposition for Sr-doped ABS was faster than that of the control at 4 weeks (3.28 ± 0.23 µm/day vs. 2.60 ± 0.20 µm/day; p<0.05. Sr can be evenly doped into porous ABS at relevant concentrations to create highly active bone substitutes.

  19. Strontium adsorption on tantalum-doped hexagonal tungsten oxide.

    Science.gov (United States)

    Li, Xingliang; Mu, Wanjun; Xie, Xiang; Liu, Bijun; Tang, Hui; Zhou, Guanhong; Wei, Hongyuan; Jian, Yuan; Luo, Shunzhong

    2014-01-15

    Hexagonal tungsten oxide (hex-WO3) has the potential to separate (137)Cs and (90)Sr from nuclear power plant or fission (99)Mo production waste. This study aims to increase the capacity of hex-WO3 to adsorb Sr(2+). Ta-doped hex-WO3 was synthesized by the hydrothermal treatment of sodium tungstate dihydrate and tantalum chloride in concentrated HCl, in the presence of ammonium sulfate. Incorporating Ta into the WO3 framework caused the interlayer spacing to expand, and the band gap to shift to higher energy. The Sr(2+) adsorption capacity of Ta-doped hex-WO3 was significantly higher than that of hex-WO3. Sr(2+) adsorption reached equilibrium within 2h in acidic solution. Maximum Sr(2+) removal occurred at pH 4. Sr(2+) uptake by hex-WO3 was described better by the Freundlich model than by the Langmuir model. Sr(2+) adsorption on hex-WO3 was spontaneous under the studied conditions.

  20. Folic acid

    Science.gov (United States)

    ... taking folic acid by itself, or with L-carnitine a compound similar to an amino acid from ... levels. It is not clear if folic acid supplementation reduces hearing loss in people with normal folate ...

  1. Doping in sport: effects, harm and misconceptions.

    Science.gov (United States)

    Birzniece, V

    2015-03-01

    Doping in sport is a widespread problem not just among elite athletes, but even more so in recreational sports. In scientific literature, major emphasis is placed on doping detection, whereas detrimental effects of doping agents on athletes' health are seldom discussed. Androgenic anabolic steroids are well known for their positive effects on muscle mass and strength. Human growth hormone also increases muscle mass, although the majority of that is an increase in extracellular fluid and not the functional muscle mass. In recreational athletes, growth hormone does not have major effect on muscle strength, power or aerobic capacity, but stimulates anaerobic exercise capacity. Erythropoietin administration increases oxygen-carrying capacity of blood improving endurance measures, whereas systemic administration of beta-adrenergic agonists may have positive effect on sprint capacity, and beta-adrenergic antagonists reduce muscle tremor. Thus, there are certain drugs that can improve selective aspects of physical performance. However, most of the doping agents exert serious side-effects, especially when used in combination, at high doses and for a long duration. The extent of long-term health consequences is difficult to predict, but likely to be substantial, especially when gene doping is considered. This review summarises the main groups of doping agents used by athletes, with the main focus on their effects on athletic performance and adverse effects.

  2. Preparation of luminescent CdTe quantum dots doped core-shell nanoparticles and their application in cell recognition

    Institute of Scientific and Technical Information of China (English)

    LI Zhaohui; WANG Kemin; TAN Weihong; LI Jun; FU Zhiying; WANG Yilin; LIU Jianbo; YANG Xiaohai

    2005-01-01

    Based on the reverse microemulsion technique, luminescent quantum dots doped core-shell nanoparticles have been prepared by employing silica as the shell and CdTe quantum dots as the core of the nanoparticles, which have an excellent solubility and dispersibility, especially amine and phosphonate groups have been modified on their surface synchronously. In comparison with CdTe quantum dots, these nanoparticles show superiority in chemical and photochemical stability. The quantum dots doped core-shell nanoparticles were successfully linked with lactobionic acid by amine group on it, which was used to recognize living liver cells.

  3. Field Evaporation of Grounded Arsenic Doped Silicon Clusters

    CERN Document Server

    Deng, Zexiang; Li, Zhibing; WeiliangWang,

    2014-01-01

    We have investigated field evaporation of grounded arsenic (As) doped silicon (Si) clusters consist of 52 atoms with density functional theory to mimic Si nano structures of hundreds of nanometers long standing on a substrate. Six cluster structures with different As doping concentrations and dopant locations are studied. The critical evaporation electric fields are found to be lower for clusters with higher doping concentrations and doping sites closer to the surface. We attribute the difference to the difference in binding energies corresponding to the different As-doping concentrations and to the doping locations. Our theoretical study could shed light on the stability of nano apexs under high electric field.

  4. Reporting doping in sport: national level athletes' perceptions of their role in doping prevention.

    Science.gov (United States)

    Whitaker, L; Backhouse, S H; Long, J

    2014-12-01

    This paper qualitatively explores national level athletes' willingness to report doping in sport. Following ethical approval, semi-structured interviews were conducted with nine national level athletes from rugby league (n = 5) and track and field athletics (n = 4). Thematic analysis established the main themes within the data. Contextual differences existed around the role that athletes perceived they would play if they became aware of doping. Specifically, track and field athletes would adopt the role of a whistle-blower and report individuals who were doping in their sport. In comparison, the rugby league players highlighted a moral dilemma. Despite disagreeing with their teammates' actions, the players would adhere to a code of silence and refrain from reporting doping. Taking these findings into account, prevention programs might focus on changing broader group and community norms around doping. In doing so, community members' receptivity to prevention messages may increase. Moreover, developing skills to intervene (e.g., speaking out against social norms that support doping behavior) or increasing awareness of reporting lines could enhance community responsibility for doping prevention. In sum, the findings highlight the need to consider the context of sport and emphasize that a one-size-fits-all approach to anti-doping is problematic.

  5. Al-doped and in-doped ZnO thin films in heterojunctions with silicon

    Energy Technology Data Exchange (ETDEWEB)

    Chabane, L.; Zebbar, N.; Kechouane, M. [LCMS, Faculty of Physics, University of Sciences and Technology (USTHB), BP 32-16111, Algiers (Algeria); Aida, M.S. [LCMet Interface, Faculty of Sciences, University of Constantine, 25000 (Algeria); Trari, M. [Laboratory of Storage and Valorization of Renewable Energies, Faculty of Chemistry (USTHB), BP 32-16111 Algiers (Algeria)

    2016-04-30

    The undoped, Al-doped and In-doped ZnO thin films were deposited by ultrasonic spray pyrolysis technique, onto glass and p-Si substrates and the physical properties of the films were investigated. The X-ray diffraction, optical analysis and electrical characterisations, indicate that the films were polycrystalline with hexagonal würtzite type structure and revealed that the aluminium doping deteriorates the crystalline and optical properties and enhances the electrical conductivity whereas indium doping improves all properties. The transport mechanism controlling the conduction through the heterojunctions was studied. For the heterostructures, the temperature dependent current–voltage characteristics showed rectifying behaviour in the dark, but current transport mechanism is not the same for all heterojunctions. Therefore, the presence of the interface states and volume defects are identified as limiting factors for obtaining a high quality heterojunction interface. - Highlights: • Al-doped and In-doped ZnO thin films have been deposited onto Si. • In-doped ZnO/p-Si heterojunction showed poor rectifying behaviour. • Al-doped ZnO/p-Si heterojunction showed a good rectifying at room temperature. • The carriers transport mechanisms was controlled by interfacial and volume defects.

  6. Preparation of Ca Doped Lanthanum Chromite by Sol-Gel Process

    Institute of Scientific and Technical Information of China (English)

    Zang Bangqiang; Ao Qing; Li Dehui; Sun Liangcheng; Liu Ruwei

    2004-01-01

    Super fine particles of calcium-doped lanthanum chromites were prepared by the sol-gel process in which the chelating agent was citric acid and the dispersant agent was ethylene glycol. The phase of fine particles was analyzed by XRD and the size and shape of the particles were investigated by TEM. The result shows that the nano-particles of La1-xCaxCrO3 can be obtained by the way of Ca2+ complex singly with citric acid and being calcined at 700 ℃.

  7. Magnesium-doped zinc oxide electrochemically grown on fluorine-doped tin oxide substrate.

    Science.gov (United States)

    Han, Q F; Jeong, Y I; Heo, J H; Shin, C M; Ryu, H; Park, M S; Lee, W J; Yoon, J H; Yang, J E; Choi, H

    2012-04-01

    Nanostructures of magnesium (Mg) doped Zinc oxide (ZnO) were successfully deposited on conducting fluorine-doped tin oxide (FTO) coated glass plates by cathodic electrochemical deposition method at different potentials and temperature conditions. The deposited samples were characterized by XRD and SEM techniques to confirm their structures, morphologies and optical properties. These measurements show that Mg doped ZnO has a wurtzite structure and that the strongest intensity of the (002) peak is found at 60 degrees C and -1.0 V. Tunable transmittance of Mg doped ZnO has a band gap energy from 3.45 eV to 3.82 eV, which is the direct evidence of doping.

  8. Rapid solid-phase microwave synthesis of highly photoluminescent nitrogen-doped carbon dots for Fe3+ detection and cellular bioimaging

    Science.gov (United States)

    He, Guili; Xu, Minghan; Shu, Mengjun; Li, Xiaolin; Yang, Zhi; Zhang, Liling; Su, Yanjie; Hu, Nantao; Zhang, Yafei

    2016-09-01

    Recently, carbon dots (CDs) have been playing an increasingly important role in industrial production and biomedical field because of their excellent properties. As such, finding an efficient method to quickly synthesize a large scale of relatively high purity CDs is of great interest. Herein, a facile and novel microwave method has been applied to prepare nitrogen doped CDs (N-doped CDs) within 8 min using L-glutamic acid as the sole reaction precursor in the solid phase condition. The as-prepared N-doped CDs with an average size of 1.64 nm are well dispersed in aqueous solution. The photoluminescence of N-doped CDs is pH-sensitive and excitation-dependent. The N-doped CDs show a strong blue fluorescence with relatively high fluorescent quantum yield of 41.2%, which remains stable even under high ionic strength. Since the surface is rich in oxygen-containing functional groups, N-doped CDs can be applied to selectively detect Fe3+ with the limit of detection of 10-5 M. In addition, they are also used for cellular bioimaging because of their high fluorescent intensity and nearly zero cytotoxicity. The solid-phase microwave method seems to be an effective strategy to rapidly obtain high quality N-doped CDs and expands their applications in ion detection and cellular bioimaging.

  9. Improvement of the electrochemical performance of nanosized {alpha}-MnO{sub 2} used as cathode material for Li-batteries by Sn-doping

    Energy Technology Data Exchange (ETDEWEB)

    Hashem, A.M., E-mail: ahmedh242@yahoo.com [National Research Centre, Inorganic Chemistry Department, Behoes St., Dokki, Cairo (Egypt); Abdel-Latif, A.M.; Abuzeid, H.M. [National Research Centre, Inorganic Chemistry Department, Behoes St., Dokki, Cairo (Egypt); Abbas, H.M. [National Research Centre, Physical Chemistry Department, Behoes St., Dokki, Cairo (Egypt); Ehrenberg, H. [Institute for Complex Materials, IFW Dresden, Helmholtzstr. 20, D-01069 Dresden (Germany); Materials Science, Technische Universitaet Darmstadt, Petersenstr. 23, D-64287 Darmstadt (Germany); Farag, R.S. [Department of Chemistry, Faculty of Science, Al-Azhar University, Cairo (Egypt); Mauger, A. [Universite Pierre et Marie Curie, Institut de Mineralogie et Physique de la Matiere Condensee (IMPMC), 4 Place Jussieu, 75005 Paris (France); Julien, C.M. [Universite Pierre et Marie Curie, Physicochimie des Electrolytes, Colloides et Sciences Analytiques (PECSA), 4 Place Jussieu, 75005 Paris (France)

    2011-10-06

    Highlights: > Doping MnO{sub 2} with Sn improved properties of {alpha}-MnO{sub 2}. > Thermal stabilization and electrochemical performances were improved. > Doping affected also the morphology feature of {alpha}-MnO{sub 2}. - Abstract: Sn-doped MnO{sub 2} was prepared by hydrothermal reaction between KMnO{sub 4} as oxidant, fumaric acid C{sub 4}H{sub 4}O{sub 4} as reductant and SnCl{sub 2} as doping agent. XRD analysis indicates the cryptomelane {alpha}-MnO{sub 2} crystal structure for pure and doped samples. Thermal stabilization was observed for both oxides as detected from thermogravimetric analysis. SEM and TEM images show changes in the morphology of the materials from spherical-like particles for pristine P-MnO{sub 2} to rod-like structure for Sn-MnO{sub 2}. Electrochemical properties of the electrode materials have been tested in lithium cells. Improvement in capacity retention and cycling ability is observed for doped oxide at the expense of initial capacity. After 35 cycles, the Li//Sn doped MnO{sub 2} cell display lower capacity loss.

  10. Boron-Doped Diamond Electrode in Sodium Sulphate Medium

    Directory of Open Access Journals (Sweden)

    Codruţa Cofan

    2011-01-01

    Full Text Available Differential pulse voltammetry (DPV and chronoamperometry (CA were used to detect and determine acetylsalicylic acid (ASA at a mildly oxidized boron-doped diamond (BDD electrode in a neutral sodium sulphate solution as supporting electrolyte. ASA determination in unbuffered medium was achieved using neutralized standard and real samples. Over the concentration range of 0.01 mM–0.1 mM, linear calibration plots of anodic current peaks in DPV and anodic currents in CA experiments versus concentration were obtained with very high correlation coefficients and good sensitivity values. The limits of detection were situated around 1 μM. The association of DPV and CA techniques with standard addition method represented a suitable option for the determination of ASA in real samples such as pharmaceutical formulations.

  11. Fabrication of Pd Doped WO3 Nanofiber as Hydrogen Sensor

    Directory of Open Access Journals (Sweden)

    Alireza Nikfarjam

    2013-01-01

    Full Text Available Pd doped WO3 fibers were synthesized by electro-spinning. The sol gel method was employed to prepare peroxopolytungstic acid (P-PTA. Palladium chloride and Polyvinyl pyrrolidone (PVP was dissolved in the sol Pd:WO3 = 10% molar ratio. The prepared sol was loaded into a syringe connected to a high voltage of 18.3 kV and electrospun fibers were collected on the alumina substrates. Scanning electron microscope (SEM, X-ray powder diffraction (XRD and X-ray photoelectron spectroscopy (XPS techniques were used to analyze the crystal structure and chemical composition of the fibers after heat treatment at 500 °C. Resistance-sensing measurements exhibited a sensitivity of about 30 at 500 ppm hydrogen in air, and the response and recovery times were about 20 and 30 s, respectively, at 300 °C. Hydrogen gas sensing mechanism of the sensor was also studied.

  12. Understanding the doping effects on the structural and electrical properties of ultrathin carbon nanotube networks

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Ying, E-mail: y-shuu@aist.go.jp; Shimada, Satoru; Azumi, Reiko [Electronics and Photonics Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1 Higashi, 305-8565 Tsukuba (Japan); Saito, Takeshi [Nanomaterials Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1 Higashi, 305-8565 Tsukuba (Japan)

    2015-12-07

    Similar to other semiconductor technology, doping of carbon nanotube (CNT) thin film is of great significance for performance improvement or modification. However, it still remains a challenge to seek a stable and effective dopant. In this paper, we unitize several spectroscopic techniques and electrical characterizations under various conditions to investigate the effects of typical dopants and related methods. Nitric acid (HNO{sub 3}) solution, I{sub 2} vapor, and CuI nanoparticles are used to modify a series of ultrathin CNT networks. Although efficient charge transfer is achieved initially after doping, HNO{sub 3} is not applicable because it suffers from severe reliability problems in structural and electrical properties, and it also causes a number of undesired structural defects. I{sub 2} vapor doping at 150 °C can form some stable C-I bonding structures, resulting in relatively more stable but less efficient electrical performances. CuI nanoparticles seem to be an ideal dopant. Photonic curing enables the manipulation of CuI, which not only results in the construction of novel CNT-CuI hybrid structures but also encourages the deepest level of charge transfer doping. The excellent reliability as well as processing feasibility identify the bright perspective of CNT-CuI hybrid film for practical applications.

  13. pH-indicators doped polysaccharide LbL coatings for hazardous gases optical sensing.

    Science.gov (United States)

    Mironenko, A Yu; Sergeev, A A; Voznesenskiy, S S; Marinin, D V; Bratskaya, S Yu

    2013-01-30

    Sensitive layer-by-layer (LbL) coatings for optical detection of gaseous NH(3) and HCl were prepared by self-assembly of oppositely charged polysaccharides (chitosan and λ-carrageenan) followed by doping LbLs with pH-sensitive dyes - bromothymol blue (BTB) and Congo red (CR). It has been shown that CR, being an amphoteric dye, diffuses into LbL films regardless of the charge of the outermost polyelectrolyte layer, and the dye loading increases linearly with the LbL film thickness, whereas BTB diffuses into LbL films only when the outermost layer is positively charged, and linearity between dye loading and film thickness holds only up to 8-12 double layers (DLs) deposited. Formation of dye-doped LbL coatings at the surface of K(+)/Na(+) ion-exchanged glass has allowed fabrication of composite optical waveguide (OWG) gas sensor for detection of ammonia and hydrochloric acid vapors. The response time of BTB-doped composite OWG for ammonia detection was below 1s, and the detection limit was below 1 ppm. CR-doped OWG sensors have shown high sensitivity to HCl vapor but slow relaxation time (up to several hours for 12 DL LbL films).

  14. Rapidly Thermal Annealed Si-Doped In2O3 Films for Organic Photovoltaics.

    Science.gov (United States)

    Lee, Hye-Min; Kim, Han-Ki

    2015-10-01

    We report the electrical, optical, and structural properties of Si-doped In2O3 (ISO) films prepared using co-sputtering system with multi cathode guns for use in organic photovoltaics (OPVs). We investigated the effect of Si doping power on the electrical, optical, and structural properties of ISO film that was rapidly thermally annealed at a temperature of 400 °C. Due to the high Lewis acid strength (8.096) of the Si dopant, the ISO films showed high mobility and low resistivity despite the low Si doping concentration. Low resistivity of the annealed ISO films indicated that Si(4+) acts as an effective dopant of an In2O3 matrix by substitution with the In(3+) site. At a Si doping power of 50 W, ISO film showed a sheet resistance of 19.7 Ohm/square and optical transparency of 76.7%, which are acceptable values for fabrication of OPVs. Successful operation of OPV cells fabricated on transparent ISO film indicates that ISO is a promising high mobility transparent electrode material and alternative to conventional ITO films.

  15. Effects of Doping on Thermal Conductivity of Pyrochlore Oxides for Advanced Thermal Barrier Coatings

    Science.gov (United States)

    Bansal, Narottam P.; Zhu, Dongming; Eslamloo-Grami, Maryam

    2006-01-01

    Pyrochlore oxides of general composition, A2B2O7, where A is a 3(+) cation (La to Lu) and B is a 4(+) cation (Zr, Hf, Ti, etc.) have high melting point, relatively high coefficient of thermal expansion, and low thermal conductivity which make them suitable for applications as high-temperature thermal barrier coatings. The effect of doping at the A site on the thermal conductivity of a pyrochlore oxide La2Zr2O7, has been investigated. Oxide powders of various compositions La2Zr2O7, La(1.7)Gd(0.3)Zr2O7, La(1.7)Yb(0.3)Zr2O7 and La(1.7)Gd(0.15)Yb(0.15)Zr2O7 were synthesized by the citric acid sol-gel method. These powders were hot pressed into discs and used for thermal conductivity measurements using a steady-state laser heat flux test technique. The rare earth oxide doped pyrochlores La(1.7)Gd(0.3)Zr2O7, La(1.7)Yb(0.3)Zr2O7 and La(1.7)Gd(0.15)Yb(0.15)Zr2O7 had lower thermal conductivity than the un-doped La2Zr2O7. The Gd2O3 and Yb2O3 co-doped composition showed the lowest thermal conductivity.

  16. Alkaline earth metal doped tin oxide as a novel oxygen storage material

    Energy Technology Data Exchange (ETDEWEB)

    Dong, Qiang, E-mail: dong@tagen.tohoku.ac.jp [Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, 2-1-1 Katahira, Aoba-ku Sendai 980-8577 (Japan); Yin, Shu; Yoshida, Mizuki; Wu, Xiaoyong; Liu, Bin [Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, 2-1-1 Katahira, Aoba-ku Sendai 980-8577 (Japan); Miura, Akira; Takei, Takahiro; Kumada, Nobuhiro [Department of Research Interdisciplinary Graduate School of Medicine and Engineering, University of Yamanashi, Miyamae cho-7, Kofu 400-8511 (Japan); Sato, Tsugio [Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, 2-1-1 Katahira, Aoba-ku Sendai 980-8577 (Japan)

    2015-09-15

    Alkaline earth metal doped tin oxide (SnO{sub 2}) hollow nanospheres with a diameter of 50 nm have been synthesized successfully via a facial solvothermal route in a very simple system composed of only ethanol, acetic acid, SnCl{sub 4}·5H{sub 2}O and A(NO{sub 3}){sub 2}·xH{sub 2}O (A = Mg, Ca, Sr, Ba). The synthesized undoped SnO{sub 2} and A-doped SnO{sub 2} hollow nanospheres were characterized by the oxygen storage capacity (OSC), X-ray diffraction, transmission electron microscopy and the Brunauer–Emmet–Teller (BET) technique. The OSC values of all samples were measured using thermogravimetric-differential thermal analysis. The incorporation of alkaline earth metal ion into tin oxide greatly enhanced the thermal stability and OSC. Especially, Ba-doped SnO{sub 2} hollow nanospheres calcined at 1000 °C for 20 h with a BET surface area of 61 m{sup 2} g{sup −1} exhibited the considerably high OSC of 457 μmol-O g{sup −1} and good thermal stability. Alkaline earth metal doped tin oxide has the potential to be a novel oxygen storage material.

  17. Synthesis and photoluminescent characteristics of Dy3+ doped Gd2O3 phosphors

    Science.gov (United States)

    Jeena, T. R.; Ezhil Raj, A. Moses; Bououdina, M.

    2017-02-01

    Pure and dysprosium doped gadolinium oxide nanoparticles for three different concentrations (2, 5 and 10 mol.%) were synthesized by auto-combustion method using citric acid as fuel. The nanoparticles obtained were characterized using powder x-ray diffraction (XRD), Fourier transform infrared (FTIR), scanning electron microscopy (SEM), UV–vis–NIR spectroscopy and photoluminescence (PL) spectroscopy techniques. XRD pattern revealed the crystalline cubic phase with space group Ia3 (Space Group: 206) for both the pure and doped Gd2O3 nanoparticles. The metal oxide phase formation and purity of Gd2O3 nanoparticles were further confirmed from the FTIR spectra. Morphology of the pure Gd2O3 powder is loosely dispersed clusters of tiny particles with microscopic pores, whereas for the doped samples aggregates were broken to form small clusters. Optical absorption measurements were recorded in the UV–vis–NIR wavelength region and the optical band gap variations with dopant concentration were discussed. The PL spectra of pure and Dy3+ doped Gd2O3 nanoparticles have been studied and the effect of emitted light on the yellow-to-blue intensity ratio (Y/B) of Dy3+ emission was demonstrated.

  18. Influences of glycerol as an efficient doping agent on crystal structure and antibacterial activity of B-TiO2 nano-materials.

    Science.gov (United States)

    Yang, He; Wang, Yuzheng; Xue, Xiangxin

    2014-10-01

    In this study, highly effective boron acid and glycerol co-doped TiO2 nano-materials were directly synthesized via a sol-gel method. The resulting materials were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectrum (FT-IR), UV-vis diffuse reflectance spectroscopy (DRS) and X-ray photoelectron (PL) spectroscopy. The results indicate that boron dopant is partially embedded into the interstitial TiO2 structure or incorporated into the TiO2 lattice through occupying the position of the oxygen atom, and others is present in the form of B2O3. Boron acid and glycerol co-doping TiO2 materials show obvious red shift in their absorption edges and efficient electron-hole separation because of the glycerol doping. The study on the antibacterial activities demonstrate that co-doped TiO2 nano-materials could effectively inactivate the bacteria under visible light irradiation. Co-doped TiO2 nano-materials exhibit more excellent antibacterial performance than B-doped TiO2 nano-materials.

  19. Sectioned Core Doping Effect on Higher-Order Mode Amplification in Yb-Doped Rod-Type Photonic Crystal Fibers

    DEFF Research Database (Denmark)

    Poli, F.; Lægsgaard, Jesper; Passaro, D.

    2009-01-01

    The amplification properties of guided modes in Yb-doped rod-type photonic crystal fibers with sectioned core doping have been investigated, evaluating the doped-area radius which provides the effective suppression of both LP 11- and LP02-like modes.......The amplification properties of guided modes in Yb-doped rod-type photonic crystal fibers with sectioned core doping have been investigated, evaluating the doped-area radius which provides the effective suppression of both LP 11- and LP02-like modes....

  20. A numerical model for CO effect evaluation in HT-PEMFCs: Part 2 - Application to different membranes

    Science.gov (United States)

    Cozzolino, R.; Chiappini, D.; Tribioli, L.

    2016-06-01

    In this paper, a self-made numerical model of a high temperature polymer electrolyte membrane fuel cell is presented. In particular, we focus on the impact of CO poisoning on fuel cell performance and its influence on electrochemical modelling. More specifically, the aim of this work is to demonstrate the effectiveness of our zero-dimensional electrochemical model of HT-PEMFCs, by comparing numerical and experimental results, obtained from two different commercial membranes electrode assemblies: the first one is based on polybenzimidazole (PBI) doped with phosphoric acid, while the second one uses a PBI electrolyte with aromatic polyether polymers/copolymers bearing pyridine units, always doped with H3PO4. The analysis has been carried out considering both the effect of CO poisoning and operating temperature for the two membranes above mentioned.

  1. Doping of Semiconducting Atomic Chains

    Science.gov (United States)

    Toshishige, Yamada; Kutler, Paul (Technical Monitor)

    1997-01-01

    Due to the rapid progress in atom manipulation technology, atomic chain electronics would not be a dream, where foreign atoms are placed on a substrate to form a chain, and its electronic properties are designed by controlling the lattice constant d. It has been shown theoretically that a Si atomic chain is metallic regardless of d and that a Mg atomic chain is semiconducting or insulating with a band gap modified with d. For electronic applications, it is essential to establish a method to dope a semiconducting chain, which is to control the Fermi energy position without altering the original band structure. If we replace some of the chain atoms with dopant atoms randomly, the electrons will see random potential along the chain and will be localized strongly in space (Anderson localization). However, if we replace periodically, although the electrons can spread over the chain, there will generally appear new bands and band gaps reflecting the new periodicity of dopant atoms. This will change the original band structure significantly. In order to overcome this dilemma, we may place a dopant atom beside the chain at every N lattice periods (N > 1). Because of the periodic arrangement of dopant atoms, we can avoid the unwanted Anderson localization. Moreover, since the dopant atoms do not constitute the chain, the overlap interaction between them is minimized, and the band structure modification can be made smallest. Some tight-binding results will be discussed to demonstrate the present idea.

  2. Neutron transmutation doped silicon detectors

    Energy Technology Data Exchange (ETDEWEB)

    Kim, K.; Krejner, Kh.; Ito, D.; Khusimi, K.; Okava, S.; Sirejsi, F.

    1984-01-01

    A method of doping neutron transmutation during (NTD) of Si crystals is described. Characteristics of detectors made of crystals obtained by the NTD method at low and room temperatures are measured. The possibility is studied of using the NTD method to produce Si crystals with a longer lifetime of non-base charge carriers, high specific resistance and more even distribution of specific resistance over the detector radius. The NTD method is based on /sup 30/Si isotope transmutation into /sup 31/Si following the (n, ..gamma..)-reaction. The /sup 31/Si isotope is unstable and transforms to /sup 31/P while emitting ..beta../sup -/. The NTD method consists in introduction of purified gaseous monosilan SiH/sub 4/ into the furnace to undergo thermal decomposition at 860 deg C with the formation of polycrystalline n-type Si. The polycrystalline Si prepared is treated mechanically and, after purification by the method of a ''floating zone'' in vacuum and in argon irradiated by a thermal neutron flux with the a density of 5x10/sup 11/ neUtr/(cm/sup 2/ x s) for 30-75 min. An analysis of the data obtained shows that the specifications of the Si detectors prepared by the NTD method are the same as those of conventional Si-detectors widely used nowadays but their cost of production is considerably lower.

  3. Growth hormone doping: a review

    Directory of Open Access Journals (Sweden)

    Erotokritou-Mulligan I

    2011-07-01

    Full Text Available Ioulietta Erotokritou-Mulligan, Richard IG Holt, Peter H SönksenDevelopmental Origins of Health and Disease Division, University of Southampton School of Medicine, The Institute of Developmental Science, Southampton General Hospital, Southampton, UKAbstract: The use of growth hormone (GH as a performance enhancing substance was first promoted in lay publications, long before scientists fully acknowledged its benefits. It is thought athletes currently use GH to enhance their athletic performance and to accelerate the healing of sporting injuries. Over recent years, a number of high profile athletes have admitted to using GH. To date, there is only limited and weak evidence for its beneficial effects on performance. Nevertheless the “hype” around its effectiveness and the lack of a foolproof detection methodology that will detect its abuse longer than 24 hours after the last injection has encouraged its widespread use. This article reviews the current evidence of the ergogenic effects of GH along with the risks associated with its use. The review also examines methodologies, both currently available and in development for detecting its abuse.Keywords: performance enhancing substance, GH, doping in sport, detection methods

  4. Superconductivity in doped Dirac semimetals

    Science.gov (United States)

    Hashimoto, Tatsuki; Kobayashi, Shingo; Tanaka, Yukio; Sato, Masatoshi

    2016-07-01

    We theoretically study intrinsic superconductivity in doped Dirac semimetals. Dirac semimetals host bulk Dirac points, which are formed by doubly degenerate bands, so the Hamiltonian is described by a 4 ×4 matrix and six types of k -independent pair potentials are allowed by the Fermi-Dirac statistics. We show that the unique spin-orbit coupling leads to characteristic superconducting gap structures and d vectors on the Fermi surface and the electron-electron interaction between intra and interorbitals gives a novel phase diagram of superconductivity. It is found that when the interorbital attraction is dominant, an unconventional superconducting state with point nodes appears. To verify the experimental signature of possible superconducting states, we calculate the temperature dependence of bulk physical properties such as electronic specific heat and spin susceptibility and surface state. In the unconventional superconducting phase, either dispersive or flat Andreev bound states appear between point nodes, which leads to double peaks or a single peak in the surface density of states, respectively. As a result, possible superconducting states can be distinguished by combining bulk and surface measurements.

  5. Photocatalytic degradation of methylene blue dye under visible light over Cr doped strontium titanate (SrTiO3) nanoparticles.

    Science.gov (United States)

    Qazi, Inamur Rahman; Lee, Woo-Jin; Lee, Hyun-Cheol; Hassan, Mallick Shamshi; Yang, O-Bong

    2010-05-01

    Strontium titanate (SrTiO3) and chromium doped SrTiO3 (Cr/SrTiO3) were prepared by modified sol-gel method with the citric acid as a chelating agent in the ethylene glycol solution for the effective photodegradation of methylene blue dye under visible light irradiation. The synthesized doped and un-doped SrTiO3 nanoparticles were structurally characterized and their photoresponse performances for the efficient degradation of methylene blue dye have been demonstrated. After introducing the Cr on SrTiO3, UV-Vis absorption was appeared the red-shift at 566 nm from 392 nm as compare with bare SrTiO3. The photocatalytic degradation activity of Cr/SrTiO3 was significantly improved to 60% degradation of methylene blue in 3 h under visible light, which is approximately 5 times higher than that of the bare SrTiO3.

  6. Visible Light-Photocatalytic Activity of Sulfate-Doped Titanium Dioxide Prepared by the Sol−Gel Method

    Directory of Open Access Journals (Sweden)

    Tsuneo Fujii

    2013-04-01

    Full Text Available Sulfate-doped TiO2 was prepared from sol−gel systems containing titaniumalkoxide and sulfuric acid. The time needed for gelation of the systems was significantlyreduced by ultrasonic irradiation. The doped sulfate was observed by FTIR and XPSmeasurements. Some sulfate ions remained in the TiO2 even after heating at 300−600 °C.The UV and visible photocatalytic activities of the samples were confirmed by thedegradation of trichloroethylene (TCE. The activity of the photocatalyst samples duringthe UV irradiation strongly depended on their crystallinities rather than their specificsurface areas, i.e., adsorption ability. The degradation rate during the visible irradiationdepended on both the adsorption ability and visible absorption of the photocatalystsamples. The visible absorption induced by the sulfate-doping was effective for theTCE degradation.

  7. Non-metal doped TiO2 nanotube arrays for high efficiency photocatalytic decomposition of organic species in water

    Science.gov (United States)

    Szkoda, Mariusz; Siuzdak, Katarzyna; Lisowska-Oleksiak, Anna

    2016-10-01

    Titanium dioxide is a well-known photoactive semiconductor with a variety of possible applications. The procedure of pollutant degradation is mainly performed using TiO2 powder suspension. It can also be exploited an immobilized catalyst on a solid support. Morphology and chemical doping have a great influence on TiO2 activity under illumination. Here we compare photoactivity of titania nanotube arrays doped with non-metal atoms: nitrogen, iodine and boron applied for photodegradation of organic dye - methylene blue and terephtalic acid. The doped samples act as a much better photocatalyst in the degradation process of methylene blue and lead to the formation of much higher amount of hydroxyl radicals (•OH) than undoped TiO2 nanotube arrays. The use of a catalyst active under solar light illumination in the form of thin films on a stable substrate can be scaled up for an industrial application.

  8. Growth and characterization of pure and lithium doped strontium tartrate tetrahydrate crystals by solution–gel technique

    Indian Academy of Sciences (India)

    B Suresh Kumar; M H Rahim Kutty; M R Sudarsana Kumar; K Rajendra Babu

    2007-08-01

    The effect of lithium ion as dopant on the size and transparency of strontium tartrate tetrahydrate (SrC4H4O6.4H2O) crystals are presented in this paper. Growth of single crystals of undoped and lithium doped strontium tartrate tetrahydrate by controlled diffusion of strontium nitrate into the gel charged with tartaric acid at room temperature are narrated. The lithium ion enhances the size and transparency of the doped crystals. The crystal structure of the compound was confirmed by X-ray diffractometry and dopant concentration with ICP–atomic emission spectrometer system. Thermal decomposition of the grown crystals is investigated by TGA and DTA studies. The FTIR spectra of pure and doped crystals are recorded and analysed. Kurtz powder technique has been used to test SHG efficiency of the crystals.

  9. BF3-doped polyaniline: A novel conducting polymer

    Indian Academy of Sciences (India)

    Debangshu Chaudhuri; D D Sarma

    2006-07-01

    We review the unusual structural, transport and magnetic properties of highly conducting polyaniline, doped with boron trifluoride. Our studies establish the unique conducting state of this system, which is in distinct contrast with the conventional proton-doped polyaniline samples.

  10. Electronic and electrochemical doping of graphene by surface adsorbates

    Directory of Open Access Journals (Sweden)

    Hugo Pinto

    2014-10-01

    Full Text Available Many potential applications of graphene require its precise and controllable doping with charge carriers. Being a two-dimensional material graphene is extremely sensitive to surface adsorbates, so its electronic properties can be effectively modified by deposition of different atoms and molecules. In this paper, we review two mechanisms of graphene doping by surface adsorbates, namely electronic and electrochemical doping. Although, electronic doping has been extensively studied and discussed in the literature, much less attention has been paid to electrochemical doping. This mechanism can, however, explain the doping of graphene by adsorbates for which no charge transfer is expected within the electronic doping model. In addition, electrochemical doping is in the origin of the hysteresis effects often observed in graphene-based field effect transistors when operating in the atmospheric environment.

  11. Electrospark doping of steel with tungsten

    Energy Technology Data Exchange (ETDEWEB)

    Denisova, Yulia, E-mail: yukolubaeva@mail.ru; Shugurov, Vladimir, E-mail: shugurov@opee.hcei.tsc.ru [Institute of High-Current Electronics of the Siberian Branch of the Russian Academy of Sciences, 634055, Russia, Tomsk, 2/3 Akademicheskiy Ave (Russian Federation); Petrikova, Elizaveta, E-mail: elizmarkova@yahoo.com [Institute of High-Current Electronics of the Siberian Branch of the Russian Academy of Sciences, 634055, Russia, Tomsk, 2/3 Akademicheskiy Ave (Russian Federation); National Research Tomsk State University, 36 Lenin Str. Tomsk, 634050 (Russian Federation); Seksenalina, Malika, E-mail: sportmiss@bk.ru [National Research Tomsk Polytechnic University, 30 Lenin Str. Tomsk, 634050 (Russian Federation); Ivanova, Olga, E-mail: ivaov@mail.ru; Ikonnikova, Irina, E-mail: irinaikonnikova@yandex.ru [Tomsk State University of Architecture and Building, 2 Solyanaya Sq. Tomsk, 634003 (Russian Federation); Kunitsyna, Tatyana, E-mail: kma11061990@mail.ru; Vlasov, Victor, E-mail: rector@tsuab.ru [National Research Tomsk Polytechnic University, 30 Lenin Str. Tomsk, 634050 (Russian Federation); Tomsk State University of Architecture and Building, 2 Solyanaya Sq. Tomsk, 634003 (Russian Federation); Klopotov, Anatoliy, E-mail: klopotovaa@tsuab.ru [National Research Tomsk State University, 36 Lenin Str. Tomsk, 634050 (Russian Federation); Tomsk State University of Architecture and Building, 2 Solyanaya Sq. Tomsk, 634003 (Russian Federation); Ivanov, Yuriy, E-mail: yufi55@mail.ru [Institute of High-Current Electronics of the Siberian Branch of the Russian Academy of Sciences, 634055, Russia, Tomsk, 2/3 Akademicheskiy Ave (Russian Federation); National Research Tomsk State University, 36 Lenin Str. Tomsk, 634050 (Russian Federation); National Research Tomsk Polytechnic University, 30 Lenin Str. Tomsk, 634050 (Russian Federation)

    2016-01-15

    The paper is devoted to the numerical modeling of thermal processes and the analysis of the structure and properties of the surface layer of carbon steel subjected to electrospark doping with tungsten. The problem of finding the temperature field in the system film (tungsten) / substrate (iron) is reduced to the solution of the heat conductivity equation. A one-dimensional case of heating and cooling of a plate with the thickness d has been considered. Calculations of temperature fields formed in the system film / substrate synthesized using methods of electrospark doping have been carried out as a part of one-dimensional approximation. Calculations have been performed to select the mode of the subsequent treatment of the system film / substrate with a high-intensity pulsed electron beam. Authors revealed the conditions of irradiation allowing implementing processes of steel doping with tungsten. A thermodynamic analysis of phase transformations taking place during doping of iron with tungsten in equilibrium conditions has been performed. The studies have been carried out on the surface layer of the substrate modified using the method of electrospark doping. The results showed the formation in the surface layer of a structure with a highly developed relief and increased strength properties.

  12. Erbium doped stain etched porous silicon

    Energy Technology Data Exchange (ETDEWEB)

    Gonzalez-Diaz, B. [Departamento de Fisica Basica, Universidad de La Laguna, Avda. Astrofisico Francisco Sanchez, 38204 La Laguna, S/C de Tenerife (Spain); Diaz-Herrera, B. [Departamento de Energia Fotovoltaica, Instituto Tecnologico de Energias Renovables (ITER), Poligono Industrial de Granadilla, 38611 S/C Tenerife (Spain); Guerrero-Lemus, R. [Departamento de Fisica Basica, Universidad de La Laguna, Avda. Astrofisico Francisco Sanchez, 38204 La Laguna, S/C de Tenerife (Spain)], E-mail: rglemus@ull.es; Mendez-Ramos, J.; Rodriguez, V.D. [Departamento de Fisica Fundamental, Experimental Electronica y Sistemas, Universidad de La Laguna, Avda. Astrofisico Francisco Sanchez, 38204 La Laguna, S/C de Tenerife (Spain); Hernandez-Rodriguez, C. [Departamento de Fisica Basica, Universidad de La Laguna, Avda. Astrofisico Francisco Sanchez, 38204 La Laguna, S/C de Tenerife (Spain); Martinez-Duart, J.M. [Departamento de Fisica Aplicada, C-XII, Universidad Autonoma de Madrid, 28049 Cantoblanco, Madrid (Spain)

    2008-01-15

    In this work a simple erbium doping process applied to stain etched porous silicon layers (PSLs) is proposed. This doping process has been developed for application in porous silicon solar cells, where conventional erbium doping processes are not affordable because of the high processing cost and technical difficulties. The PSLs were formed by immersion in a HF/HNO{sub 3} solution to properly adjust the porosity and pore thickness to an optimal doping of the porous structure. After the formation of the porous structure, the PSLs were analyzed by means of nitrogen BET (Brunauer, Emmett and Teller) area measurements and scanning electron microscopy. Subsequently, the PSLs were immersed in a saturated erbium nitrate solution in order to cover the porous surface. Then, the samples were subjected to a thermal process to activate the Er{sup 3+} ions. Different temperatures and annealing times were used in this process. The photoluminescence of the PSLs was evaluated before and after the doping processes and the composition was analyzed by Fourier transform IR spectroscopy.

  13. Scandia doped tungsten matrix for impregnated cathode

    Institute of Scientific and Technical Information of China (English)

    WANG Jinshu; WANG Yanchun; LIU Wei; LI Hongyi; ZHOU Meiling

    2008-01-01

    As a matrix for Sc-type impregnated cathode,scandia doped tungsten with a uniform ldistribution of SC2O3 was obtained by powder metallurgy combined with the liquid-solid doping method.The microstructure and composition of the powder and the anti-ion bombardment behavior of scandium in the matrix were studied by means of SEM,EDS,XRD,and in-situ AES methods.Tungsten powder covered with scandium oxide,an ideal scandium oxide-doped tungsten powder for the preparation of Sc-type impregnated cathode,was obtained using the liquid-solid doping method.Compared with the matrix prepared with the mechanically mixed powder of tungsten and scandium oxide,SC2O3-W matrix prepared with this kind of powder had smaller grain size and uniform distribution of scandium.Sc on the surface of Sc2O3 doped tungsten mauix had good high temperature stability and good anti-ion bombardment capability.

  14. Changes in the structure of doped poly aniline (Pani-HCL) due to the process of de-doped;Alteracos na estrutura da polianilina dopada (PAni-HCL) devido ao processo de desdopagem

    Energy Technology Data Exchange (ETDEWEB)

    Gomes, Everton Carlos; Oliveira, Maria Auxiliadora Silva de, E-mail: evertonquimica@gmail.co [Instituto Tecnologico da Aeronautica (ITA), Sao Jose dos Campos, SP (Brazil). Dept. de Engenharia Mecanica e Aeronautica. Lab. de Estudos de Corrosao

    2009-07-01

    The poly aniline (PAni) is much studied, partly due to its relatively ease chemical or electrochemical synthesis, thermal stability in air and redox behavior. The chemical synthesis of poly aniline (PAni) was performed in a medium containing hydrochloric acid (HCl) as a doping agent. After that, the obtained polymer was de-doped in alkaline medium (NH4OH). Thermogravimetric analysis (TG) showed that the doped polymer, PAni-HCl, shows better thermal stability in comparison with the de-doped polymer (PAni-NH4OH). Differential scanning calorimetry (DSC) analyses show that the number of processes occurring during the heating of the polymer, as well as the complexity of them, is much higher in the PAni-HCl than the in the PAni-NH4OH. Through the spectra of FTIR and Raman could conclude that dedoping PAni-HCl was not complete, but the degree of doping of PAni-NH4OH decreased by treatment with ammonium hydroxide. XRD analysis pointed out that as the PAni-HCl as the PAni-NH4OH are partially crystalline. (author)

  15. Effects of Ni doping on photocatalytic activity of TiO2 thin films prepared by liquid phase deposition technique

    Indian Academy of Sciences (India)

    Noor Shahina Begum; H M Farveez Ahmed; K R Gunashekar

    2008-10-01

    The TiO2 thin films doped by Ni uniformly and non-uniformly were prepared on glass substrate from an aqueous solution of ammonium hexa-fluoro titanate and NiF2 by liquid phase deposition technique. The addition of boric acid as an – scavenger will shift the equilibrium to one side and thereby deposition of the film is progressed. The rate of the reaction and the nature of deposition depend on growing time and temperature. The resultant films were characterized by XRD, EDAX, UV and SEM. The result shows that the deposited films have amorphous background, which becomes crystalline at 500°C. The EDAX data confirms the existence of Ni atoms in TiO2 matrix. XRD analysis reveals the peaks corresponding to Ni but no peak of crystalline NiO was found. The transmittance spectra of Ni uniformly and non-uniformly doped TiO2 thin films show `blue shift and red shift’, respectively. Ni-doped TiO2 thin films can be used as photocatalyst for the photodegradation of methyl orange dye. It was found that, organic dye undergoes degradation efficiently in presence of non-uniformly Ni-doped TiO2 thin films when compared to uniformly doped films and pure TiO2 films under visible light. The photocatalytic activity increases with increase in the concentration of Ni in case of nonuniformly doped thin films but decreases with the concentration when uniformly doped thin films were used.

  16. Characterization and photocatalytic properties of N-doped BiVO{sub 4} synthesized via a sol-gel method

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Min, E-mail: minwang62@msn.com [College of Environmental and Chemical Engineering, Shenyang Ligong University, Shenyang 110165 (China); Liu, Qiong; Che, Yinsheng; Zhang, Lifang; Zhang, Dong [College of Environmental and Chemical Engineering, Shenyang Ligong University, Shenyang 110165 (China)

    2013-01-25

    Highlights: Black-Right-Pointing-Pointer The N-doped BiVO{sub 4} photocatalysts have higher visible-light activity. Black-Right-Pointing-Pointer The N-doped BiVO{sub 4} can be synthesized using hexamethylene tetramine (C{sub 6}H{sub 12}N{sub 4}) as nitrogen source. Black-Right-Pointing-Pointer The maximum activity was observed when the molar ratio of N/Bi was 20%. Black-Right-Pointing-Pointer The higher activity can be related to more oxygen vacancies, V{sup 4+} and a red shift. - Abstract: A N-doped BiVO{sub 4} photocatalyst with high visible light activity was synthesized by the complexing sol-gel method using citric acid as a chelate and hexamethylene tetramine (C{sub 6}H{sub 12}N{sub 4}) as a nitrogen source. The as-prepared N-doped BiVO{sub 4} samples were characterized by X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), scanning electron microscopy (SEM), specific surface area (BET) and UV-Vis diffuse reflectance spectroscopy (DRS). The photocatalytic activity was evaluated by photocatalytic degradation of methyl orange (MO) solution under visible light. This technique revealed that pure BiVO{sub 4} and all the N-doped samples were in a monoclinic phase; no peaks of any other phases or impurities were detected. Nitrogen atoms were doped into the BiVO{sub 4} lattice and filled the atomic sites of oxygen to form O-Bi-N-V-O bonds, which contributed to the appearance of the more active species V{sup 4+} and oxygen vacancies. The doped nitrogen resulted in a red shift in the absorption edge. However, the N-doping only slightly changed the morphologies and BET special surface areas of the samples. The photocatalytic activity of BiVO{sub 4} significantly depended on the N-doping content and the calcination temperature. The maximum activity was observed for the catalyst obtained via calcination at 500 Degree-Sign C, for which the molar ratio of N to Bi was 0.20. Excess N-doping decreased the light absorption.

  17. Doping To Reduce Base Resistances Of Bipolar Transistors

    Science.gov (United States)

    Lin, True-Lon

    1991-01-01

    Modified doping profile proposed to reduce base resistance of bipolar transistors. A p/p+ base-doping profile reduces base resistance without reducing current gain. Proposed low/high base-doping profile realized by such low-temperature deposition techniques as molecular-beam epitaxy, ultra-high-vacuum chemical-vapor deposition, and limited-reaction epitaxy. Produces desired doping profiles without excessive diffusion of dopant.

  18. Hydrogen Solubility in Pr-doped and Un-doped YSZ for One Chamber Fuel Cell

    DEFF Research Database (Denmark)

    Bay, Lasse; Horita, T.; Sakai, N.;

    1998-01-01

    SIMS analysis. Doping of Pr in the YSZ resulted in a higher intensity of the D ion, which indicated that hydrogen solubility was raised by the doping. The solubility of hydrogen in the electrolyte may affect the performance of one chamber fuel cells. (C) 1998 Elsevier Science B.V. All rights reserved.......Yttria-stabilised zirconia electrolytes (YSZ and Pr-doped YSZ) and yttria-doped strontium cerate (SYC) were tested in a one chamber fuel cell fed with a mixture of methane and air at 1223 K. The obtained performances were 4 mW cm(-2), 3 mW cm(-2), 2.5 mW cm(-2), and 0.15 mW cm(-2) for SYC, 1.8 mol.......% Pr-doped YSZ, 17 mol.% Pr-doped YSZ, and un-doped YSZ, respectively. These values are lower than those reported by Asano ct al., due to poisoning of the gold electrode. The solubility of hydrogen in the electrolytes was compared by means of tracer exchange using a H(2) + D(2)O mixture and subsequent...

  19. Momentum and Doping Dependence of Spin Excitations in Electron-Doped Cuprate Superconductors

    Science.gov (United States)

    Jing, Pengfei; Zhao, Huaisong; Kuang, Lülin; Lan, Yu; Feng, Shiping

    2017-01-01

    Superconductivity in copper oxides emerges on doping holes or electrons into their Mott-insulating parent compounds. The spin excitations are thought to be the mediating glue for the pairing in superconductivity. Here the momentum and doping dependence of the dynamical spin response in the electron-doped cuprate superconductors is studied based on the kinetic-energy-driven superconducting mechanism. It is shown that the dispersion of the low-energy spin excitations changes strongly upon electron doping; however, the hour-glass-shaped dispersion of the low-energy spin excitations appeared in the hole-doped case is absent on the electron-doped side due to the electron-hole asymmetry. In particular, the commensurate resonance appears in the superconducting state with the resonance energy that correlates with the dome-shaped doping dependence of the superconducting gap. Moreover, the spectral weight and dispersion of the high-energy spin excitations in the superconducting state are comparable with those in the corresponding normal state, indicating that the high-energy spin excitations do not play an important part in the pair formation.

  20. Doping dependent properties of Cr-doped ZnO nanostructures prepared by microwave irradiation.

    Science.gov (United States)

    Ahmed, Faheem; Arshi, Nishat; Anwar, M S; Koo, Bon Heun

    2014-11-01

    In this work, undoped and Cr-doped single-crystalline ZnO nanorods were prepared by a facile microwave assisted solution method. X-ray diffraction (XRD) and transmission electron microscopy (TEM) results showed that Cr-doped ZnO was comprised of single phase nature with hexagonal wurtzite structure up to 5% Cr doping, however, secondary phase ZnCr2O4 appeared upon further increasing the Cr dopant concentration. Field emission scanning electron microscopy (FESEM) and TEM micrographs suggested that the undoped nanorods with an average length of -~2 μm and a diameter in the range of 150-200 nm, respectively were observed. Interestingly, the size of nanorods decreased with the increase of Cr concentration in ZnO. Optical studies depicted that the energy bandgap was decreased with the increase of Cr concentration. Raman scattering spectra of Cr-doped ZnO revealed the lower frequency shift of E2(high) phonon mode with the increase in concentration of Cr dopant, suggested the successful doping of Cr into Zn site in ZnO. Magnetic studies showed that Cr-doped ZnO exhibited room temperature ferromagnetism (RTFM) and the value of magnetization was continuously decreased with the increase in Cr doping.