Chemistry, spectroscopy and the role of supported vanadium oxides in heterogeneous catalysis

NARCIS (Netherlands)

Weckhuysen, B.M.; Keller, D.E.

2003-01-01

Supported vanadium oxide catalysts are active in a wide range of applications. In this review, an overview is given of the current knowledge available about vanadium oxide-based catalysts. The review starts with the importance of vanadium in heterogeneous catalysis, a discussion of the molecular

Ab initio Investigation of Helium in Vanadium Oxide Nanoclusters

Science.gov (United States)

Danielson, Thomas; Tea, Eric; Hin, Celine

Nanostructured ferritic alloys (NFAs) are strong candidate materials for the next generation of fission reactors and future fusion reactors. They are characterized by a large number density of oxide nanoclusters dispersed throughout a BCC iron matrix, where current oxide nanoclusters are primarily comprised of Y-Ti-O compounds. The oxide nanoclusters provide the alloy with high resistance to neutron irradiation, high yield strength and high creep strength at the elevated temperatures of a reactor environment. In addition, the oxide nanoclusters serve as trapping sites for transmutation product helium providing substantially increased resistance to catastrophic cracking and embrittlement. Although the mechanical properties and radiation resistance of the existing NFAs is promising, the problem of forming large scale reactor components continues to present a formidable challenge due to the high hardness and unpredictable fracture behavior of the alloys. An alternative alloy has been previously proposed and fabricated where vanadium is added in order to form vanadium oxide nanoclusters that serve as deflection sites for crack propagation. Although experiments have shown evidence that the fracture behavior of the alloys is improved, it is unknown whether or not the vanadium oxide nanoclusters are effective trapping sites for helium. We present results obtained using density functional theory investigating the thermodynamic stability of helium with the vanadium oxide matrix to make a comparison of trapping effectiveness to traditional Y-Ti-O compounds.

X-Ray Absorption Studies of Vanadium-Containing Metal Oxide Nanocrystals

Energy Technology Data Exchange (ETDEWEB)

Hohn, Keith, L.

2006-01-09

Metal oxide nanocrystals offer significant potential for use as catalysts or catalyst supports due to their high surface areas and unique chemical properties that result from the high number of exposed corners and edges. However, little is known about the catalytic activity of these materials, especially as oxidation catalysts. This research focused on the preparation, characterization and use of vanadium-containing nanocrystals as selective oxidation catalysts. Three vanadium-containing nanocrystals were prepared using a modified sol-gel procedure: V/MgO, V/SiO2, and vanadium phosphate (VPO). These represent active oxidation catalysts for a number of industrially relevant reactions. The catalysts were characterized by x-ray diffraction and Raman, UV-VIS, infrared and x-ray absorption spectroscopies with the goal of determining the primary structural and chemical differences between nanocrystals and microcrystals. The catalytic activity of these catalysts was also studied in oxidative dehydrogenation of butane and methanol oxidation to formaldehyde. V/MgO nanocrystals were investigated for activity in oxidative dehydrogenation of butane and compared to conventional V/MgO catalysts. Characterization of V/MgO catalysts using Raman spectroscopy and x-ray absorption spectroscopy showed that both types of catalysts contained magnesium orthovanadate at vanadium loadings below 15 weight%, but above that loading, magnesium pyrovanadate may have been present. In general, MgO nanocrystals had roughly half the crystal size and double the surface area of the conventional MgO. In oxidative dehydrogenation of butane, nanocrystalline V/MgO gave higher selectivity to butene than conventional V/MgO at the same conversion. This difference was attributed to differences in vanadium domain size resulting from the higher surface areas of the nanocrystalline support, since characterization suggested that similar vanadium phases were present on both types of catalysts. Experiments in

Novel hybrid materials based on the vanadium oxide nanobelts

Energy Technology Data Exchange (ETDEWEB)

Zabrodina, G.S., E-mail: kudgs@mail.ru [G.A. Razuvaev Institute of Organometallic Chemistry of Russian Academy of Sciences, Nizhny Novgorod 603950 (Russian Federation); Lobachevsky State University, Nizhny Novgorod 603950 (Russian Federation); Makarov, S.G.; Kremlev, K.V. [G.A. Razuvaev Institute of Organometallic Chemistry of Russian Academy of Sciences, Nizhny Novgorod 603950 (Russian Federation); Lobachevsky State University, Nizhny Novgorod 603950 (Russian Federation); Yunin, P.A.; Gusev, S.A. [Institute for Physics of Microstructures Russian Academy of Sciences, Nizhny Novgorod 603087 (Russian Federation); Kaverin, B.S.; Kaverina, L.B. [G.A. Razuvaev Institute of Organometallic Chemistry of Russian Academy of Sciences, Nizhny Novgorod 603950 (Russian Federation); Ketkov, S.Yu. [G.A. Razuvaev Institute of Organometallic Chemistry of Russian Academy of Sciences, Nizhny Novgorod 603950 (Russian Federation); Lobachevsky State University, Nizhny Novgorod 603950 (Russian Federation)

2016-04-15

Graphical abstract: - Highlights: • Flat and curved vanadium oxide nanobelts have been synthesized. • Hybrid material was prepared via decoration of flexible nanobelts with zinc phthalocyanine. • Investigations of the thermal stability, morphologies and structures were carried out. - Abstract: Novel hybrid materials based on zinc phthalocyanine and nanostructured vanadium oxides have attracted extensive attention for the development of academic research and innovative industrial applications such as flexible electronics, optical sensors and heterogeneous catalysts. Vanadium oxides nanobelts were synthesized via a hydrothermal treatment V{sub 2}O{sub 5}·nH{sub 2}O gel with surfactants (TBAB, CTAB) used as structure-directing agents, where CTAB – cetyltrimethylammonium bromide, TBAB – tetrabutylammonium bromide. Hybrid materials were prepared decoration of (CTA){sub 0.33}V{sub 2}O{sub 5} flexible nanobelts with cationic zinc phthalocyanine by the ion-exchange route. Investigations of the thermal stability, morphologies and structures of the (CTA){sub 0.33}V{sub 2}O{sub 5}, (TBA){sub 0.16}V{sub 2}O{sub 5} nanobelts and zinc phthalocyanine exchange product were carried out. The hybrid materials based on the nanostructured vanadium oxide and zinc phthalocyanine were tested as photocatalysts for oxidation of citronellol and 2-mercaptoethanol by dioxygen.

Structural and silver/vanadium ratio effects on silver vanadium phosphorous oxide solution formation kinetics: impact on battery electrochemistry.

Science.gov (United States)

Bock, David C; Takeuchi, Kenneth J; Marschilok, Amy C; Takeuchi, Esther S

2015-01-21

The detailed understanding of non-faradaic parasitic reactions which diminish battery calendar life is essential to the development of effective batteries for use in long life applications. The dissolution of cathode materials including manganese, cobalt and vanadium oxides in battery systems has been identified as a battery failure mechanism, yet detailed dissolution studies including kinetic analysis are absent from the literature. The results presented here provide a framework for the quantitative and kinetic analyses of the dissolution of cathode materials which will aid the broader community in more fully understanding this battery failure mechanism. In this study, the dissolution of silver vanadium oxide, representing the primary battery powering implantable cardioverter defibrillators (ICD), is compared with the dissolution of silver vanadium phosphorous oxide (Ag(w)VxPyOz) materials which were targeted as alternatives to minimize solubility. This study contains the first kinetic analyses of silver and vanadium solution formation from Ag0.48VOPO4·1.9H2O and Ag2VP2O8, in a non-aqueous battery electrolyte. The kinetic results are compared with those of Ag2VO2PO4 and Ag2V4O11 to probe the relationships among crystal structure, stoichiometry, and solubility. For vanadium, significant dissolution was observed for Ag2V4O11 as well as for the phosphate oxide Ag0.49VOPO4·1.9H2O, which may involve structural water or the existence of multiple vanadium oxidation states. Notably, the materials from the SVPO family with the lowest vanadium solubility are Ag2VO2PO4 and Ag2VP2O8. The low concentrations and solution rates coupled with their electrochemical performance make these materials interesting alternatives to Ag2V4O11 for the ICD application.

Partial Oxidation of n-Butane over a Sol-Gel Prepared Vanadium Phosphorous Oxide

Directory of Open Access Journals (Sweden)

Juan M. Salazar

2013-01-01

Full Text Available Vanadium phosphorous oxide (VPO is traditionally manufactured from solid vanadium oxides by synthesizing VOHPO4∙0.5H2O (the precursor followed by in situ activation to produce (VO2P2O7 (the active phase. This paper discusses an alternative synthesis method based on sol-gel techniques. Vanadium (V triisopropoxide oxide was reacted with ortho-phosphoric acid in an aprotic solvent. The products were dried at high pressure in an autoclave with a controlled excess of solvent. This procedure produced a gel of VOPO4 with interlayer entrapped molecules. The surface area of the obtained materials was between 50 and 120 m2/g. Alcohol produced by the alkoxide hydrolysis reduced the vanadium during the drying step, thus VOPO4 was converted to the precursor. This procedure yielded non-agglomerated platelets, which were dehydrated and evaluated in a butane-air mixture. Catalysts were significantly more selective than the traditionally prepared materials with similar intrinsic activity. It is suggested that the small crystallite size obtained increased their selectivity towards maleic anhydride.

Processing, characterization, and bactericidal activity of undoped and silver-doped vanadium oxides

Energy Technology Data Exchange (ETDEWEB)

Tousley, M.E.; Wren, A.W.; Towler, M.R. [Inamori School of Engineering, Alfred University, Alfred, NY 14803 (United States); Mellott, N.P., E-mail: mellott@alfred.edu [Inamori School of Engineering, Alfred University, Alfred, NY 14803 (United States)

2012-12-14

Vanadium oxide (V) and silver-doped vanadium oxide (Ag-V) powders were prepared via sol-gel processing. Structural evolution and bactericidal activity was examined as a function of temperature ranging from 250, 350, 450 and 550 Degree-Sign C. Powders were characterized using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and Raman spectroscopy. Results from all techniques showed vanadium pentoxide (V{sub 2}O{sub 5}) is the predominant phase regardless of heat treatment temperature or the addition of silver (Ag). XRD analysis suggests Ag is present as AgCl in samples heat treated to 250, 350, and 450 Degree-Sign C and as AgV{sub 6}O{sub 15} at 550 Degree-Sign C. Bactericidal activity was evaluated against Escherichia coli using the agar disk diffusion method considering both Ag-V and undoped, V powders. While the addition of Ag significantly increased bactericidal properties, the specific Ag valency, or crystal structure and morphology formed at higher temperatures, had little effect on functionality. -- Highlights: Black-Right-Pointing-Pointer Vanadium and silver-doped vanadium oxide powders were prepared via sol-gel. Black-Right-Pointing-Pointer Powders were characterized using advanced, complementary structural techniques. Black-Right-Pointing-Pointer Bactericidal activity was evaluated against E. coli. Black-Right-Pointing-Pointer Both vanadium and silver doped vanadium oxide show bactericidal activity.

Investigation of structural, morphological and electrical properties of APCVD vanadium oxide thin films

International Nuclear Information System (INIS)

Papadimitropoulos, Georgios; Trantalidis, Stelios; Tsiatouras, Athanasios; Vasilopoulou, Maria; Davazoglou, Dimitrios; Kostis, Ioannis

2015-01-01

Vanadium oxide films were chemically vapor deposited (CVD) on oxidized Si substrates covered with CVD tungsten (W) thin films and on glass substrates covered with indium tin oxide (ITO) films, using vanadium(V) oxy-tri-isopropoxide (C 9 H 21 O 4 V) vapors. X-ray diffraction (XRD) measurements showed that the deposited films were composed of a mixture of vanadium oxides; the composition was determined mainly by the deposition temperature and less by the precursor temperature. At temperatures up to 450 C the films were mostly composed by monoclinic VO 2 . Other peaks corresponding to various vanadium oxides were also observed. X-ray microanalysis confirmed the composition of the films. The surface morphology was studied with atomic force microscopy (AFM) and scanning electron microscopy (SEM). These measurements revealed that the morphology strongly depends on the used substrate and the deposition conditions. The well-known metal-insulator transition was observed near 75 C for films mostly composed by monoclinic VO 2 . Films deposited at 450 C exhibited two transitions one near 50 C and the other near 60 C possibly related to the presence of other vanadium phases or of important stresses in them. Finally, the vanadium oxide thin films exhibited significant sensory capabilities decreasing their resistance in the presence of hydrogen gas with response times in the order of a few seconds and working temperature at 40 C. (copyright 2015 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Synthesis and photocatalytic activity of graphene based doped TiO2 nanocomposites

International Nuclear Information System (INIS)

Gu, Yongji; Xing, Mingyang; Zhang, Jinlong

2014-01-01

Graphical abstract: - Highlights: • Graphene based doped TiO 2 nanocomposites were prepared. • The intimate contact between doped TiO 2 and graphene is achieved simultaneously. • These nanocomposites showed higher photocatalytic activity than TiO 2 and doped TiO 2 . • Photocatalytic mechanism was explained thoroughly. - Abstract: The nanocomposites of reduced graphene oxide based nitrogen doped TiO 2 (N–TiO 2 –RGO) and reduced graphene oxide based nitrogen and vanadium co-doped TiO 2 (N, V–TiO 2 –RGO) were prepared via a facile hydrothermal reaction of graphene oxide and TiO 2 in a water solvent. In this hydrothermal treatment, the reduction of graphene oxide and the intimate contact between nitrogen doped TiO 2 (N–TiO 2 ) or nitrogen and vanadium co-doped TiO 2 (N,V–TiO 2 ) and the RGO sheet is achieved simultaneously. Both N–TiO 2 –RGO and N,V–TiO 2 –RGO nanocomposites exhibit much higher visible light photocatalytic activity than N–TiO 2 and N,V–TiO 2 , and the order of visible light photocatalytic activity is N,V–TiO 2 –RGO > N–TiO 2 –RGO > N,V–TiO 2 > N–TiO 2 > TiO 2 . According to the characterization, the enhanced photocatalytic activity of the nanocomposites is attributed to reasons, such as enhancement of adsorption of pollutants, light absorption intensity, minimizing the recombination of photoinduced electrons and holes and more excited states of these nanocomposites under visible light irradiation. Overall, this work provides a more marked contrast of graphene based semiconductor nanocomposites and a more comprehensive explanation of the mechanism

Vanadium oxide nanotubes as cathode material for Mg-ion batteries

DEFF Research Database (Denmark)

Christensen, Christian Kolle; Sørensen, Daniel Risskov; Bøjesen, Espen Drath

Vanadium oxide compounds as cathode material for secondary Li-ion batteries gained interest in the 1970’s due to high specific capacity (>250mAh/g), but showed substantial capacity fading.1 Developments in the control of nanostructured morphologies have led to more advanced materials, and recently...... vanadium oxide nanotubes (VOx-NT) were shown to perform well as a cathode material for Mg-ion batteries.2 The VOx-NTs are easily prepared via a hydrothermal process to form multiwalled scrolls of VO layer with primary amines interlayer spacer molecules.3 The tunable and relative large layer spacing 1-3 nm...... synchrotron powder X-ray diffraction measured during battery operation. These results indicate Mg-intercalation in the multiwalled VOx-NTs occurs within the space between the individual vanadium oxide layers while the underlying VOx frameworks constructing the walls are affected only to a minor degree...

Vanadium oxide monolayer catalysts : The vapor-phase oxidation of methanol

NARCIS (Netherlands)

Roozeboom, Fred; Cordingley, Peter D.; Gellings, P.J.

1981-01-01

The oxidation of methanol over vanadium oxide, unsupported and applied as a monolayer on γ-Al2O3, CeO2, TiO2, and ZrO2, was studied between 100 and 400 °C in a continuous-flow reactor. At temperatures from 150 to about 250 °C two main reactions take place, (a) dehydration of methanol to dimethyl

Vanadium Doped Tungsten Oxide Material - Electrical Physical and Sensing Properties

Directory of Open Access Journals (Sweden)

Shishkin N. Y.

2008-05-01

Full Text Available The electrical physical and sensing (to VOCs and inorganic gases properties of vanadium doped tungsten oxide in the regions of phase transition temperature were investigated. Vanadium oxide (II dimerization was observed in the doped material, corresponding to new phase transition. The extreme sensitivity and selectivity to chemically active gases and vapors in small concentrations: CO, NOx, NH3 acetone, ethanol near phase transitions temperature was found. Sensor elements were manufactured for the quantitative detection (close to 1 ppm of alcohol and ammonia.

Bipolar resistive switching in room temperature grown disordered vanadium oxide thin-film devices

Science.gov (United States)

Wong, Franklin J.; Sriram, Tirunelveli S.; Smith, Brian R.; Ramanathan, Shriram

2013-09-01

We demonstrate bipolar switching with high OFF/ON resistance ratios (>104) in Pt/vanadium oxide/Cu structures deposited entirely at room temperature. The SET (RESET) process occurs when negative (positive) bias is applied to the top Cu electrode. The vanadium oxide (VOx) films are amorphous and close to the vanadium pentoxide stoichiometry. We also investigated Cu/VOx/W structures, reversing the position of the Cu electrode, and found the same polarity dependence with respect to the top and bottom electrodes, which suggests that the bipolar nature is linked to the VOx layer itself. Bipolar switching can be observed at 100 °C, indicating that it not due to a temperature-induced metal-insulator transition of a vanadium dioxide second phase. We discuss how ionic drift can lead to the bipolar electrical behavior of our junctions, similar to those observed in devices based on several other defective oxides. Such low-temperature processed oxide switches could be of relevance to back-end or package integration processing schemes.

Raman and XPS characterization of vanadium oxide thin films with temperature

Energy Technology Data Exchange (ETDEWEB)

Ureña-Begara, Ferran, E-mail: ferran.urena@uclouvain.be [Université catholique de Louvain, Institute of Information and Communication Technologies, Electronics and Applied Mathematics (ICTEAM), Louvain-la-Neuve (Belgium); Crunteanu, Aurelian [XLIM Research Institute, UMR 7252, CNRS/Université de Limoges, Limoges (France); Raskin, Jean-Pierre [Université catholique de Louvain, Institute of Information and Communication Technologies, Electronics and Applied Mathematics (ICTEAM), Louvain-la-Neuve (Belgium)

2017-05-01

Highlights: • Comprehensive study of the oxidation of VO{sub 2} thin films from R.T. up to 550 °C. • Phase changes and mixed-valence vanadium oxides formed during the oxidation process. • Reported Raman and XPS signatures for each vanadium oxide. • Monitoring of the current and resistance evolution at the surface of the films. • Oxidation model describing the evolution of the vanadium oxides and phase changes. - Abstract: The oxidation mechanisms and the numerous phase transitions undergone by VO{sub 2} thin films deposited on SiO{sub 2}/Si and Al{sub 2}O{sub 3} substrates when heated from room temperature (R.T.) up to 550 °C in air are investigated by Raman and X-ray photoelectron spectroscopy. The results show that the films undergo several intermediate phase transitions between the initial VO{sub 2} monoclinic phase at R.T. and the final V{sub 2}O{sub 5} phase at 550 °C. The information about these intermediate phase transitions is scarce and their identification is important since they are often found during the synthesis of vanadium dioxide films. Significant changes in the film conductivity have also been observed to occur associated to the phase transitions. In this work, current and resistance measurements performed on the surface of the films are implemented in parallel with the Raman measurements to correlate the different phases with the conductivity of the films. A model to explain the oxidation mechanisms and phenomena occurring during the oxidation of the films is proposed. Peak frequencies, full-width half-maxima, binding energies and oxidation states from the Raman and X-ray photoelectron spectroscopy experiments are reported and analyzed for all the phases encountered in VO{sub 2} films prepared on SiO{sub 2}/Si and Al{sub 2}O{sub 3} substrates.

Self-assembling Synthesis of Vanadium Oxide Nanotubes and Simple Determination of the Content of Ⅴ(Ⅳ)

Institute of Scientific and Technical Information of China (English)

MAI Li-qiang; CHEN Wen; XU Qing; ZHU Quan-yao; HAN Chun-hua; PENG Jun-feng

2003-01-01

High-yielding low-cost vanadium oxide nanotubes were prepared by the hydrothermal self-assembling process from vanadium pentoxide and organic molecules as structure-directing templates. Moreover, a new method was discovered for determining the content of V (Ⅳ) in vanadium oxide nanotubes by thermogravimetric analysis ( TGA ). This method is simple, precise and feasible and can be extended to determine the content of low oxidation state in the other transition metal oxide nanomaterials.

Nature of active vanadium nanospecies in MCM-41 type catalysts for olefins oxidation

Energy Technology Data Exchange (ETDEWEB)

Chanquía, Corina M., E-mail: cchanquia@cab.cnea.gov.ar [Centro Atómico Bariloche, Comisión Nacional de Energía Atómica (CAB-CNEA). Av. Bustillo 9500, R8402AGP, San Carlos de Bariloche, Río Negro (Argentina); Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET). Avenida Rivadavia 1917, C1033AAJ, Ciudad Autónoma de Buenos Aires (Argentina); Cánepa, Analía L. [Centro de Investigación y Tecnología Química (CITeQ), Universidad Tecnológica Nacional, Facultad Regional Córdoba (UTN-FRC), Maestro López esq. Cruz Roja Argentina, Ciudad Universitaria, 5016, Córdoba Capital (Argentina); Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET). Avenida Rivadavia 1917, C1033AAJ, Ciudad Autónoma de Buenos Aires (Argentina); Winkler, Elin L. [Centro Atómico Bariloche, Comisión Nacional de Energía Atómica (CAB-CNEA). Av. Bustillo 9500, R8402AGP, San Carlos de Bariloche, Río Negro (Argentina); Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET). Avenida Rivadavia 1917, C1033AAJ, Ciudad Autónoma de Buenos Aires (Argentina); and others

2016-06-01

A multi-technique physicochemical investigation including UV–Vis-DRS, Raman spectroscopy, XPS, ESR and FTIRS with pyridine adsorption was performed to analyze the nature of different vanadium nanospecies present on MCM-41 type catalysts. By employing a direct hydrothermal synthesis, vanadium species were incorporated into siliceous structure mainly as tetrahedrally coordinated isolated V{sup δ+} ions, which would be located inside the wall and on the wall surface of the mesoporous channels. The coexistence of both vanadium oxidation states V{sup 4+} and V{sup 5+} was also revealed. Acidity measurements permitted to infer about the majority presence of Lewis acid sites, which increase with vanadium content. The catalytic performance of these materials was evaluated in the reaction of α-pinene oxidation with H{sub 2}O{sub 2}. The highest intrinsic activity of the sample with lower V loading was attributed to the high dispersion and efficiency of the isolated V{sup δ+} species that actuate as active sites. A mixture of reaction products arising from competitive processes of epoxidation and allylic oxidation was found. - Highlights: • Nature of vanadium nanospecies in mesoporous silicates was investigated. • From hydrothermal sol–gel synthesis, isolated V{sup δ+} sites were mainly generated. • The coexistence of both vanadium oxidation states V{sup 4+} and V{sup 5+} was revealed. • The catalytic performance was evaluated in α-pinene oxidation with H{sub 2}O{sub 2}. • The high catalytic activity is attributed to high dispersion of isolated V{sup δ+} ions.

One-step hydrothermal synthesis of hexangular starfruit-like vanadium oxide for high power aqueous supercapacitors

Science.gov (United States)

Shao, Jie; Li, Xinyong; Qu, Qunting; Zheng, Honghe

2012-12-01

Homogenous hexangular starfruit-like vanadium oxide was prepared for the first time by a one-step hydrothermal method. The assembly process of hexangular starfruit-like structure was observed from TEM images. The electrochemical performance of starfruit-like vanadium oxide was examined by cyclic voltammetry and galvanostatic charge/discharge. The obtained starfruit-like vanadium oxide exhibits a high power capability (19 Wh kg-1 at the specific power of 3.4 kW kg-1) and good cycling stability for supercapacitors application.

Nanocomposite of graphene and metal oxide materials

Science.gov (United States)

Liu, Jun; Aksay, Ilhan A.; Choi, Daiwon; Wang, Donghai; Yang, Zhenguo

2012-09-04

Nanocomposite materials comprising a metal oxide bonded to at least one graphene material. The nanocomposite materials exhibit a specific capacity of at least twice that of the metal oxide material without the graphene at a charge/discharge rate greater than about 10C.

Nanocomposite of graphene and metal oxide materials

Science.gov (United States)

Liu, Jun; Aksay, Ilhan A.; Choi, Daiwon; Wang, Donghai; Yang, Zhenguo

2013-10-15

Nanocomposite materials comprising a metal oxide bonded to at least one graphene material. The nanocomposite materials exhibit a specific capacity of at least twice that of the metal oxide material without the graphene at a charge/discharge rate greater than about 10 C.

Graphene oxide - Polyvinyl alcohol nanocomposite based electrode material for supercapacitors

Science.gov (United States)

Pawar, Pranav Bhagwan; Shukla, Shobha; Saxena, Sumit

2016-07-01

Supercapacitors are high capacitive energy storage devices and find applications where rapid bursts of power are required. Thus materials offering high specific capacitance are of fundamental interest in development of these electrochemical devices. Graphene oxide based nanocomposites are mechanically robust and have interesting electronic properties. These form potential electrode materials efficient for charge storage in supercapacitors. In this perspective, we investigate low cost graphene oxide based nanocomposites as electrode material for supercapacitor. Nanocomposites of graphene oxide and polyvinyl alcohol were synthesized in solution phase by integrating graphene oxide as filler in polyvinyl alcohol matrix. Structural and optical characterizations suggest the formation of graphene oxide and polyvinyl alcohol nanocomposites. These nanocomposites were found to have high specific capacitance, were cyclable, ecofriendly and economical. Our studies suggest that nanocomposites prepared by adding 0.5% wt/wt of graphene oxide in polyvinyl alcohol can be used an efficient electrode material for supercapacitors.

Optical and electrochromic properties of sol-gel deposited Ti- doped vanadium oxide films

International Nuclear Information System (INIS)

Oezer, N.; Sabuncu, S.

1997-01-01

Because of the yellowish color, vanadium oxide films in the as deposited state is not as favorable as transparent coatings for most elector chromic devices. an interesting possibility to alter the yellowish colours is the doping with other non-absorbing metal oxides. Ti doped vanadium oxide films with various amounts of titanium were synthesized and investigated as transparent counter electrodes for electrochromic transmissive device application. Electrochromic titanium doped vanadium pentoxide (V sub 2 O 5) coatings were prepared by the sol-gel dip coating technique. The coating solutions were synthesized from vanadium tri(isopropoxide) precursors. X-ray diffraction (XRD) studies showed that the sol-gel deposited doped films heat treated at temperatures below 350 degree centigrade, were amorphous, whereas hose heat treated at higher temperatures were slight y crystalline. The optical and electrochemical properties of the Ti doped vanadium oxide films has been investigated in 0.1 m LiClO sub 4 propylene carbonate solution color changes by dropping were noted for all investigated films exhibits good electrochemical cycling (CV) measurements also showed that Ti doped V sub 2 O sub 5 films exhibits good electrochemical cycling reversibility, 'in situ' optical measurement revealed that those films exhibits good electrochemical cycling the spectra range 300 < lambda < 800 nm and change color between yellow and light green. The change in visible transmittance was 25 % for 5% Ti doped film. (author)

Lithium insertion in sputtered vanadium oxide film

DEFF Research Database (Denmark)

West, K.; Zachau-Christiansen, B.; Skaarup, S.V.

1992-01-01

were oxygen deficient compared to V2O5. Films prepared in pure argon were reduced to V(4) or lower. The vanadium oxide films were tested in solid-state lithium cells. Films sputtered in oxygen showed electrochemical properties similar to crystalline V2O5. The main differences are a decreased capacity...

Preparation and characterization of graphene-based vanadium oxide composite semiconducting films with horizontally aligned nanowire arrays

International Nuclear Information System (INIS)

Jung, Hye-Mi; Um, Sukkee

2016-01-01

Highly oriented crystalline hybrid thin films primarily consisting of Magnéli-phase VO 2 and conductive graphene nanoplatelets are fabricated by a sol–gel process via dipping pyrolysis. A combination of chemical, microstructural, and electrical analyses reveals that graphene oxide (GO)-templated vanadium oxide (VO x ) nanocomposite films exhibit a vertically stacked multi-lamellar nanostructure consisting of horizontally aligned vanadium oxide nanowire (VNW) arrays along the (hk0) set of planes on a GO template, with an average crystallite size of 41.4 Å and a crystallographic tensile strain of 0.83%. In addition, GO-derived VO x composite semiconducting films, which have an sp 3 /sp 2 bonding ratio of 0.862, display thermally induced electrical switching properties in the temperature range of − 20 °C to 140 °C, with a transition temperature of approximately 65 °C. We ascribe these results to the use of GO sheets, which serve as a morphological growth template as well as an electrochemically tunable platform for enhancing the charge-carrier mobility. Moreover, the experimental studies demonstrate that graphene-based Magnéli-phase VO x composite semiconducting films can be used in advanced thermo-sensitive smart sensing/switching applications because of their outstanding thermo-electrodynamic properties and high surface charge density induced by the planar-type VNWs. - Highlights: • VO x -graphene oxide composite (G/VO x ) films were fabricated by sol–gel process. • The G/VO x films mainly consisted of Magnéli-phase VO 2 and reduced graphene sheets. • The G/VO x films exhibited multi-lamellar textures with planar VO x nanowire arrays. • The G/VO x films showed the thermo-sensitive electrical switching properties. • Effects of GOs on the electrical characteristics of the G/VO x films were discussed.

XPS study of vanadium surface oxidation by oxygen ion bombardment

Czech Academy of Sciences Publication Activity Database

Alov, N.; Kutsko, D.; Spirovová, Ilona; Bastl, Zdeněk

2006-01-01

Roč. 600, č. 8 (2006), s. 1628-1631 ISSN 0039-6028 R&D Projects: GA ČR GA104/04/0467 Institutional research plan: CEZ:AV0Z40400503 Keywords : vanadium oxide * oxide film * ion-beam oxidation * X-ray photoelectron spectroscopy Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 1.880, year: 2006

Improving methane gas sensing properties of multi-walled carbonnanotubes by vanadium oxide filling

CSIR Research Space (South Africa)

Chimowa, George

2017-08-01

Full Text Available Manipulation of electrical properties and hence gas sensing properties of multi-walled carbon nanotubes (MWNTs) by filling the inner wall with vanadium oxide is presented. Using a simple capillary technique, MWNTs are filled with vanadium metal...

Synthesis and magnetic properties of bulk transparent PMMA/Fe-oxide nanocomposites

Science.gov (United States)

Li, Shanghua; Qin, Jian; Fornara, Andrea; Toprak, Muhammet; Muhammed, Mamoun; Kim, Do Kyung

2009-05-01

PMMA/Fe-oxide nanocomposites are fabricated by a chemical method. Monodispersed Fe-oxide nanoparticles are well dispersed in the PMMA matrix by in situ polymerization, resulting in a bulk transparent polymeric nanocomposite. The magnetic behavior of the PMMA/Fe-oxide nanocomposites is investigated. The transparent PMMA/Fe-oxide nanocomposite has potentially interesting magneto-optic applications without compromising the advantages of a lightweight, noncorrosive polymeric material with very high transparency even for bulk samples.

Synthesis and magnetic properties of bulk transparent PMMA/Fe-oxide nanocomposites

International Nuclear Information System (INIS)

Li Shanghua; Qin Jian; Fornara, Andrea; Toprak, Muhammet; Muhammed, Mamoun; Kim, Do Kyung

2009-01-01

PMMA/Fe-oxide nanocomposites are fabricated by a chemical method. Monodispersed Fe-oxide nanoparticles are well dispersed in the PMMA matrix by in situ polymerization, resulting in a bulk transparent polymeric nanocomposite. The magnetic behavior of the PMMA/Fe-oxide nanocomposites is investigated. The transparent PMMA/Fe-oxide nanocomposite has potentially interesting magneto-optic applications without compromising the advantages of a lightweight, noncorrosive polymeric material with very high transparency even for bulk samples.

Cure kinetics and chemorheology of EPDM/graphene oxide nanocomposites

Energy Technology Data Exchange (ETDEWEB)

Allahbakhsh, Ahmad [Department of Polymer Engineering, Islamic Azad University, South Tehran Branch, 17776-13651 Tehran (Iran, Islamic Republic of); Mazinani, Saeedeh, E-mail: s.mazinani@aut.ac.ir [Amirkabir Nanotechnology Research Institute (ANTRI), Amirkabir University of Technology, Tehran (Iran, Islamic Republic of); Kalaee, Mohammad Reza [Department of Polymer Engineering, Islamic Azad University, South Tehran Branch, 17776-13651 Tehran (Iran, Islamic Republic of); Sharif, Farhad [Department of Polymer Engineering and Color Technology, Amirkabir University of Technology, Tehran (Iran, Islamic Republic of)

2013-07-10

Graphical abstract: - Highlights: • Graphene oxide content and dispersion as effective parameters on cure kinetics. • Graphene oxide as an effective controlling factor of crosslink density. • Interaction of graphene oxide with curing system (ZnO) during curing process. - Abstract: In this study, the effect of graphene oxide on cure behavior of ethylene–propylene–diene rubber (EPDM) nanocomposite is studied. In this regard, the cure kinetics of nanocomposite is studied employing different empirical methods. The required activation energy of nth-order cure process shows about 160 kJ/mol increments upon 5 phr graphene oxide loading compared to 1 phr graphene oxide loading. However, the required activation energy is significantly reduced followed by incorporation of graphene oxide in nanocomposites compared to neat EPDM sample. Furthermore, the effect of graphene oxide on structural properties of nanocomposites during the cure process is studied using X-ray diffraction, scanning electron microscopy and Fourier transform infrared spectrometry techniques. As the results show, graphene oxide interestingly affects the structure of zinc oxide during the vulcanization process. This behavior could be probably related to high tendency of zinc oxide to react with oxidized surface of graphene oxide.

Vanadium

Science.gov (United States)

Kelley, Karen D.; Scott, Clinton T.; Polyak, Désirée E.; Kimball, Bryn E.; Schulz, Klaus J.; DeYoung,, John H.; Seal, Robert R.; Bradley, Dwight C.

2017-12-19

sands, and oil shales may be important future sources.Vanadium occurs in one of four oxidation states in nature: +2, +3, +4, and +5. The V3+ ion has an octahedral radius that is almost identical to that of (Fe3+) and (Al3+) and, therefore, it substitutes in ferromagnesian minerals. During weathering, much of the vanadium may partition into newly formed clay minerals, and it either remains in the +3 valence state or oxidizes to the +4 valence state, both of which are relatively insoluble. If erosion is insignificant but chemical leaching is intense, the residual material may be enriched in vanadium, as are some bauxites and laterites. During the weathering of igneous, residual, or sedimentary rocks, some vanadium oxidizes to the +5 valence state, especially in the intensive oxidizing conditions that are characteristic of arid climates.The average contents of vanadium in the environment are as follows: soils [10 to 500 parts per million (ppm)]; streams and rivers [0.2 to 2.9 parts per billion (ppb)]; and coastal seawater (0.3 to 2.8 ppb). Concentrations of vanadium in soils (548 to 7,160 ppm) collected near vanadium mines in China, the Czech Republic, and South Africa are many times greater than natural concentrations in soils. Additionally, if deposits contain sulfide minerals such as chalcocite, pyrite, and sphalerite, high levels of acidity may be present if sulfide dissolution is not balanced by the presence of acid-neutralizing carbonate minerals. Some of the vanadium-bearing deposit types, particularly some SSV and black-shale deposits, contain appreciable amounts of carbonate minerals, which lowers the acid-generation potential.Vanadium is a micronutrient with a postulated requirement for humans of less than 10 micrograms per day, which can be met through dietary intake. Primary and secondary drinking water regulations for vanadium are not currently in place in the United States. Vanadium toxicity is thought to result from an intake of more than 10 to 20 milligrams

Positron annihilation in sodium and copper β-vanadium oxide bronzes

International Nuclear Information System (INIS)

Dryzek, J.; Rogowska, E.

1990-01-01

Studies of copper and sodium β-vanadium oxide bronzes are performed using positron annihilation measured with a long slit angular correlation apparatus. The dependences of peak coincidence rate on temperature (40 to 310deg C) are obtained for different concentrations of donor atoms in the case of copper vanadium oxide bronzes. A three-states model corresponding to the annihilation of positrons in donor atom sublattice is applied for the description of the experimental data. The creation enthalpy of vacancies for that sublattice is equal to (0.60 ± 0.01) eV for Na 0.33 V 2 O 5 and equal to (0.64 ± 0.01) eV for Cu x V 2 O 5 . (author)

Fluorometric determination of vanadium (V) by utilizing its catalytic effect on the oxidation of o-aminophenol by chlorate

Energy Technology Data Exchange (ETDEWEB)

Hiraki, K; Shimizu, N; Nishikawa, Y [Kinki Univ., Higashi-Osaka, Osaka (Japan). Faculty of Science and Technology; Shigematsu, T

1981-12-01

The oxidation of o-aminophenol by chlorate ion takes place in acidic milieu and is catalyzed by a trace amount of vanadium (V). Vanadium (V) oxidizes o-aminophenol to 2-amino-3-phenoxazone, then the vanadium (IV) produced is reoxidized to vanadium (V) by the sodium chlorate. Further oxidation of o-aminophenol proceeds by repetition of these reactions. The oxidation product (2-amino-3-phenoxazone) gives an intense fluorescence; under optimum conditions, the fluorescence intensity is proportional to the concentration of vanadium. The most suitable concentration of o-aminophenol and sodium chlorate for the determination of vanadium (V) were found to be 0.02 M and 2 x 10/sup -4/ M, respectively. From 0.1 ppm to 5 ppm of vanadium (V) can be determined under the optimum conditions; reaction temperature 50/sup 0/C, reaction time 2 h, and at pH 2 +- 0.2. If the reaction time is increased to 3 h at 55/sup 0/C, the method may be extended from 2 ppb to 15 ppb of vanadium. Interferences of diverse ions were tested, among which Fe (III) and Mn (VII) caused positive errors, and Cr (VI), Mo (VI) negative errors if present in 40 fold w/w ratio to V (V).

Vanadium recovery process

International Nuclear Information System (INIS)

Pyrih, R.Z.; Rickard, R.S.

1978-01-01

A process for recovering vanadium values from carbonaceous type vanadium ores, and vanadium scrap, such as vanadium contaminated spent catalyst, is disclosed which comprises roasting the vanadium containing material in air at a temperature less than about 600 0 C to produce a material substantially devoid of organic matter, subjecting said roasted material to a further oxidizing roast in an oxygen atmosphere at a temperature of at least about 800 0 C for a period sufficient to convert substantially all of the vanadium to the soluble form, leaching the calcine with a suitable dilute mineral acid or water at a pH of neutral to about 2 to recover vanadium values, precipitating vanadium values as iron vanadate from the leach solution with a soluble iron compound at a pH from neutral to about 1, and recovering ferrovanadium from the iron vanadate by a reduction vacuum smelting operation. The conversion of vanadium in the ore to the soluble form by the oxidizing roast is accomplished without the addition of an alkaline salt during calcining

Decomposition of hydrogen peroxide on nickel oxide - vanadium pentoxide catalysts and the effect of ionizing radiation on them

International Nuclear Information System (INIS)

Mucka, V.

1984-01-01

Some physico-chemical and catalytic properties of nickel oxide-vanadium pentoxide two-component catalysts were studied over the entire concentration range of the components, using the decomposition of hydrogen peroxide in an aqueous solution as the test reaction. The two oxides were found to affect each other; this was shown by the dependences of the specific surface area, the V 4+ ion concentration, and the catalyst activity on the system composition. At low vanadium pentoxide concentrations (up to 15 mol%) the reaction took place on nickel oxide modified with vanadium pentoxide, whereas in the region of higher vanadium pentoxide concentrations the decomposition of the peroxide was catalyzed primarily in the homogeneous phase by vanadium(V) peroxide ions; in a sample with 30 mol% V 2 O 5 , trivalent vanadium also played a part. With catalysts obtained by mere mechanical mixing of the two oxides, a modified activity was observed in the region of high excess of nickel oxide. The activity of catalyst, particularly pure nickel oxide, was increased by its partial reduction and decreased by its exposure to gamma radiation if the dose was higher than 10 5 Gy. The effects observed are interpreted in terms of the concept of bivalent catalytic centres. (author)

Sulfonated graphene oxide/nafion composite membrane for vanadium redox flow battery.

Science.gov (United States)

Kim, Byung Guk; Han, Tae Hee; Cho, Chang Gi

2014-12-01

Nafion is the most frequently used as the membrane material due to its good proton conductivity, and excellent chemical and mechanical stabilities. But it is known to have poor barrier property due to its well-developed water channels. In order to overcome this drawback, graphene oxide (GO) derivatives were introduced for Nafion composite membranes. Sulfonated graphene oxide (sGO) was prepared from GO. Both sGO and GO were treated each with phenyl isocyanate and transformed into corresponding isGO and iGO in order to promote miscibility with Nafion. Then composite membranes were obtained, and the adaptability as a membrane for vanadium redox flow battery (VRFB) was investigated in terms of proton conductivity and vanadium permeability. Compared to a pristine Nafion, proton conductivities of both isGO/Nafion and iGO/Nafion membranes showed less temperature sensitivity. Both membranes also showed quite lower vanadium permeability at room temperature. Selectivity of the membrane was the highest for isGO/Nafion and the lowest for the pristine Nafion.

Vanadium oxide thin films deposited on silicon dioxide buffer layers by magnetron sputtering

International Nuclear Information System (INIS)

Chen Sihai; Ma Hong; Wang Shuangbao; Shen Nan; Xiao Jing; Zhou Hao; Zhao Xiaomei; Li Yi; Yi Xinjian

2006-01-01

Thin films made by vanadium oxide have been obtained by direct current magnetron sputtering method on SiO 2 buffer layers. A detailed electrical and structural characterization has been performed on the deposited films by four-point probe method and scanning electron microscopy (SEM). At room temperature, the four-point probe measurement result presents the resistance of the film to be 25 kU/sheet. The temperature coefficient of resistance is - 2.0%/K. SEM image indicates that the vanadium oxide exhibits a submicrostructure with lamella size ranging from 60 nm to 300 nm. A 32 x 32-element test microbolometer was fabricated based on the deposited thin film. The infrared response testing showed that the response was 200 mV. The obtained results allow us to conclude that the vanadium oxide thin films on SiO 2 buffer layers is suitable for uncooled focal plane arrays applications

Statistical analysis on hollow and core-shell structured vanadium oxide microspheres as cathode materials for Lithium ion batteries

Directory of Open Access Journals (Sweden)

Xing Liang

2018-06-01

Full Text Available In this data, the statistical analyses of vanadium oxide microspheres cathode materials are presented for the research article entitled “Statistical analyses on hollow and core-shell structured vanadium oxides microspheres as cathode materials for Lithium ion batteries” (Liang et al., 2017 [1]. This article shows the statistical analyses on N2 adsorption-desorption isotherm and morphology vanadium oxide microspheres as cathode materials for LIBs. Keywords: Adsorption-desorption isotherm, Pore size distribution, SEM images, TEM images

Vanadium oxide thin films and fibers obtained by acetylacetonate sol–gel method

Energy Technology Data Exchange (ETDEWEB)

Berezina, O.; Kirienko, D. [Department of Physical Engineering, Petrozavodsk State University, 185910 Petrozavodsk (Russian Federation); Pergament, A., E-mail: aperg@psu.karelia.ru [Department of Physical Engineering, Petrozavodsk State University, 185910 Petrozavodsk (Russian Federation); Stefanovich, G.; Velichko, A. [Department of Physical Engineering, Petrozavodsk State University, 185910 Petrozavodsk (Russian Federation); Zlomanov, V. [Department of Chemistry, Moscow State University, 119991 Moscow (Russian Federation)

2015-01-01

Vanadium oxide films and fibers have been fabricated by the acetylacetonate sol–gel method followed by annealing in wet nitrogen. The samples are characterized by X-ray diffraction and electrical conductivity measurements. The effects of a sol aging, the precursor decomposition and the gas atmosphere composition on the annealing process, structure and properties of the films are discussed. The two-stage temperature regime of annealing of amorphous films in wet nitrogen for formation of the well crystallized VO{sub 2} phase is chosen: 1) 25–550 °C and 2) 550–600 °C. The obtained films demonstrate the metal–insulator transition and electrical switching. Also, the effect of the polyvinylpyrrolidone additive concentration and electrospinning parameters on qualitative (absence of defects and gel drops) and quantitative (length and diameter) characteristics of vanadium oxide fibers is studied. - Highlights: • Vanadium oxide thin films and fibers are synthesized by sol–gel method. • The effect of annealing, atmosphere, time and electrospinning parameters is studied. • Produced VO{sub 2} structures exhibit metal–insulator transition and electrical switching.

Ethylenediamine-functionalized graphene oxide incorporated acid-base ion exchange membranes for vanadium redox flow battery

International Nuclear Information System (INIS)

Liu, Shuai; Li, Dan; Wang, Lihua; Yang, Haijun; Han, Xutong; Liu, Biqian

2017-01-01

Highlights: • Ethylenediamine functionalized graphene oxide. • Layered structure of functionalized graphene oxide block vanadium ions crossover. • Protonated N-containing groups suppress vanadium ions permeation. • Ion transport channels are narrowed by electrostatic interactions. • Vanadium crossover decreased due to enhanced Donnan effect and special structure. - Abstract: As a promising large-scale energy storage battery, vanadium redox flow battery (VRFB) is urgently needed to develop cost-effective membranes with excellent performance. Novel acid-base ion exchange membranes (IEMs) are fabricated based on sulfonated poly(ether ether ketone) (SPEEK) matrix and modified graphene oxide (GO) by solution blending. N-based functionalized graphene oxide (GO-NH 2 ) is fabricated by grafting ethylenediamine onto the edge of GO via a facile method. On one hand, the impermeable layered structures effectively block ion transport pathway to restrain vanadium ions crossover. On the other hand, acid-base pairs form between −SO 3 − groups and N-based groups on the edge of GO nanosheets, which not only suppress vanadium ions contamination but also provide a narrow pathway for proton migration. The structure is beneficial for achieving an intrinsic balance between conductivity and permeability. By altering amounts of GO-NH 2 , a sequence of acid-base IEMs are characterized in detail. The single cells assembled with acid-base IEMs show self-discharge time for 160 h, capacity retention 92% after 100 cycle, coulombic efficiency 97.2% and energy efficiency 89.5%. All data indicate that acid-base IEMs have promising prospects for VRFB applications.

Heterogeneous catalysis in the liquid-phase oxidation of olefins--3. The activity of supported vanadium-chromium binary oxide catalyst for the oxidation of cyclohexene

Energy Technology Data Exchange (ETDEWEB)

Takehira, K; Hayakawa, T; Ishikawa, T

1979-03-01

The activity of supported vanadium-chromium binary oxide catalyst for the oxidation of cyclohexene to 1-cyclohexenyl hydroperoxide, 2-cyclohexene-1-one, 2-cyclohexene-1-ol, and cyclohexene oxide was due to the interaction between the metal oxides and the carriers. The oxidation reaction was carried out in benzene at 60/sup 0/C for four hours with the binary oxide supported on (GAMMA)-alumina or silica; three series of catalysts were prepared by combining the vanadium and chromium oxide components with alumina hydrate or silica sol by a kneading method. The silica-supported catalysts had the greatest activity, the highest being the V/sub 2/O/sub 5//SiO/sub 2/ system, which lost its activity quickly during the reaction. This was followed in activity by the Cr/sub 2/O/sub 3//SiO/sub 2/ system, containing the chromium(V) species. The Cr/sub 2/O/sub 3//Al/sub 2/O/sub 3/ system also had high activity and the chromium(V) species. The vanadium and chromium metal ions are probably coordinated tetrahedrally on the support, and these complexes catalyze cyclohexene autoxidation by decomposing 1-cyclohexenyl hydroperoxide.

Additive for vanadium and sulfur oxide capture in catalytic cracking

International Nuclear Information System (INIS)

Chin, A.A.; Sapre, A.V.; Sarli, M.S.

1991-01-01

This patent describes a fluid catalytic cracking process in which a hydrocarbon feedstock. It comprises: a vanadium contaminant in an amount of a least 2 ppmw is cracked under fluid catalytic cracking conditions with a solid, particulate cracking catalyst to produce cracking products of lower molecular weight while depositing carbonaceous material on the particles of cracking catalyst, separating the particles of cracking catalyst from the cracking products in the disengaging zone and oxidatively regenerating the cracking catalyst by burning off the deposited carbonaceous material in a regeneration zone, the improvement comprising reducing the make-up rate of the cracking catalyst by contacting the cracking feed with a particulate additive composition for passivating the vanadium content of the feed, comprising an alkaline earth metal oxide and an alkaline earth metal spinel

Electrochemical studies on vanadium oxides, 9

International Nuclear Information System (INIS)

Miura, Takashi; Yamamoto, Masahiro; Takahashi, Hirobumi; Kishi, Tomiya; Nagai, Takashi

1979-01-01

The mechanism of the anodic oxidation of various organic compounds-including methanol, formaldehyde, formic acid, ethanol, acetaldehyde and acetic acid-at illuminated vanadium pentoxide (V 2 O 5 ) single crystal electrodes were investigated in aqueous solutions of an H 2 SO 4 -K 2 SO 4 system of about pH 2, in which oxygen evolution from water molecules had previously been confirmed to occur with a current efficiency of about 100%. It was shown that all the organics were oxidized by the so called hole-current doubling mechanism, and that the oxygen evolution reaction, which competed with the above oxidation reaction at the hole-capturing step from the valence band of the electrode, proceeded by the simple hole-capturing mechanism, not followed by an electron injection step into the conduction band. Furthermore, it is considered that chloride ions added to the electrolytes tended to hinder hole-current doubling oxidation owing to their reactivity with the holes at the illuminated V 2 O 5 electrodes. (author)

A method for recovery of iron, titanium, and vanadium from vanadium-bearing titanomagnetite

Science.gov (United States)

Zhang, Yi-min; Wang, Li-na; Chen, De-sheng; Wang, Wei-jing; Liu, Ya-hui; Zhao, Hong-xin; Qi, Tao

2018-02-01

An innovative method for recovering valuable elements from vanadium-bearing titanomagnetite is proposed. This method involves two procedures: low-temperature roasting of vanadium-bearing titanomagnetite and water leaching of roasting slag. During the roasting process, the reduction of iron oxides to metallic iron, the sodium oxidation of vanadium oxides to water-soluble sodium vanadate, and the smelting separation of metallic iron and slag were accomplished simultaneously. Optimal roasting conditions for iron/slag separation were achieved with a mixture thickness of 42.5 mm, a roasting temperature of 1200°C, a residence time of 2 h, a molar ratio of C/O of 1.7, and a sodium carbonate addition of 70wt%, as well as with the use of anthracite as a reductant. Under the optimal conditions, 93.67% iron from the raw ore was recovered in the form of iron nugget with 95.44% iron grade. After a water leaching process, 85.61% of the vanadium from the roasting slag was leached, confirming the sodium oxidation of most of the vanadium oxides to water-soluble sodium vanadate during the roasting process. The total recoveries of iron, vanadium, and titanium were 93.67%, 72.68%, and 99.72%, respectively.

Electrodeposition of Polypyrrole/Reduced Graphene Oxide/Iron Oxide Nanocomposite as Supercapacitor Electrode Material

Directory of Open Access Journals (Sweden)

Y. C. Eeu

2013-01-01

Full Text Available Polypyrrole (PPy was reinforced with reduced graphene oxide (RGO and iron oxide to achieve electrochemical stability and enhancement. The ternary nanocomposite film was prepared using a facile one-pot chronoamperometry approach, which is inexpensive and experimentally friendly. The field emission scanning electron microscopy (FESEM image shows a layered morphology of the ternary nanocomposite film as opposed to the dendritic structure of PPy, suggesting hybridization of the three materials during electrodeposition. X-ray diffraction (XRD profile shows the presence of Fe2O3 in the ternary nanocomposite. Cyclic voltammetry (CV analysis illustrates enhanced current for the nanocomposite by twofold and fourfold compared to its binary (PPy/RGO and individual (PPy counterparts, respectively. The ternary nanocomposite film exhibited excellent specific capacitance retention even after 200 cycles of charge/discharge.

Structural, optical and electrochemical properties of F-doped vanadium oxide transparent semiconducting thin films

Energy Technology Data Exchange (ETDEWEB)

Mousavi, M.; Khorrami, G.H. [University of Bojnord, Department of Physics, Faculty of Basic Science, Bojnord (Iran, Islamic Republic of); Kompany, A. [Ferdowsi University of Mashhad, Department of Physics, Mashhad (Iran, Islamic Republic of); Yazdi, S.T. [Payame Noor University (PNU), Department of Physics, Tehran (Iran, Islamic Republic of)

2017-12-15

In this study, F-doped vanadium oxide thin films with doping levels up to 60 at % were prepared by spray pyrolysis method on glass substrates. To measure the electrochemical properties, some films were deposited on fluorine-tin oxide coated glass substrates. The effect of F-doping on the structural, electrical, optical and electrochemical properties of vanadium oxide samples was investigated. The X-ray diffractographs analysis has shown that all the samples grow in tetragonal β-V{sub 2}O{sub 5} phase structure with the preferred orientation of [200]. The intensity of (200) peak belonging to β-V{sub 2}O{sub 5} phase was strongest in the undoped vanadium oxide film. The scanning electron microscopy images show that the samples have nanorod- and nanobelt-shaped structure. The size of the nanobelts in the F-doped vanadium oxide films is smaller than that in the pure sample and the width of the nanobelts increases from 30 to 70 nm with F concentration. With increasing F-doping level from 10 to 60 at %, the resistivity, the transparency and the optical band gap decrease from 111 to 20 Ω cm, 70 to 50% and 2.4 to 2.36 eV, respectively. The cyclic voltammogram (CV) results show that the undoped sample has the most extensive CV and by increasing F-doping level from 20 to 60 at %, the area of the CV is expanded. The anodic and cathodic peaks in F-doped samples are stronger. (orig.)

Thermal radiative near field transport between vanadium dioxide and silicon oxide across the metal insulator transition

Energy Technology Data Exchange (ETDEWEB)

Menges, F.; Spieser, M.; Riel, H.; Gotsmann, B., E-mail: bgo@zurich.ibm.com [IBM Research-Zurich, Säumerstrasse 4, CH-8803 Rüschlikon (Switzerland); Dittberner, M. [IBM Research-Zurich, Säumerstrasse 4, CH-8803 Rüschlikon (Switzerland); Photonics Laboratory, ETH Zurich, 8093 Zurich (Switzerland); Novotny, L. [Photonics Laboratory, ETH Zurich, 8093 Zurich (Switzerland); Passarello, D.; Parkin, S. S. P. [IBM Almaden Research Center, 650 Harry Road, San Jose, California 95120 (United States)

2016-04-25

The thermal radiative near field transport between vanadium dioxide and silicon oxide at submicron distances is expected to exhibit a strong dependence on the state of vanadium dioxide which undergoes a metal-insulator transition near room temperature. We report the measurement of near field thermal transport between a heated silicon oxide micro-sphere and a vanadium dioxide thin film on a titanium oxide (rutile) substrate. The temperatures of the 15 nm vanadium dioxide thin film varied to be below and above the metal-insulator-transition, and the sphere temperatures were varied in a range between 100 and 200 °C. The measurements were performed using a vacuum-based scanning thermal microscope with a cantilevered resistive thermal sensor. We observe a thermal conductivity per unit area between the sphere and the film with a distance dependence following a power law trend and a conductance contrast larger than 2 for the two different phase states of the film.

Comparative ion insertion study into a nanostructured vanadium oxide in aqueous salt solutions

Energy Technology Data Exchange (ETDEWEB)

Yuan, Q.; Ren, S. L.; Zukowski, J.; Pomeroy, M.; Soghomonian, V., E-mail: soghomon@vt.edu [Department of Physics, Virginia Tech, Blacksburg, Virginia 24061 (United States)

2014-07-07

We present a comparative study for the electrochemical insertion of different cations into a nanostructured vanadium oxide material. The oxide is hydrothemally synthesized and electrically characterized by variable temperature measurements. The electrochemical reactions are performed in aqueous chloride solutions of lithium, sodium, potassium, and ammonium, and the electrochemical behavior of various cycles are correlated with visual changes in the vanadium oxide nanosheets as observed by scanning electron microscopy. We note an increase in the specific charge per cycle in the cases of sodium and ammonium ions only, correlated with minimal physical changes to the nanosheets. The differing behavior of the various ions has implications for their use in electrical energy storage applications.

Graphene oxide nanocomposites and their electrorheology

International Nuclear Information System (INIS)

Zhang, Wen Ling; Liu, Ying Dan; Choi, Hyoung Jin

2013-01-01

Graphical abstract: - Highlights: • GO-based PANI, NCOPA and PS nanocomposites are prepared. • The nanocomposites are adopted as novel electrorheological (ER) candidates. • Their critical ER characteristics and dielectric performance are analyzed. • Typical ER behavior widens applications of GO-based nanocomposites. - Abstract: Graphene oxide (GO), a novel one-atom carbon system, has become one of the most interesting materials recently due to its unique physical and chemical properties in addition to graphene. This article briefly reviews a recent progress of the fabrication of GO-based polyaniline, ionic N-substituted copolyaniline and polystyrene nanocomposites. The critical electrorheological characteristics such as flow response and yield stress from rheological measurement, relaxation time and achievable polarizability from dielectric analysis are also analyzed

X-ray Absorption Study of Graphene Oxide and Transition Metal Oxide Nanocomposites.

Science.gov (United States)

Gandhiraman, Ram P; Nordlund, Dennis; Javier, Cristina; Koehne, Jessica E; Chen, Bin; Meyyappan, M

2014-08-14

The surface properties of the electrode materials play a crucial role in determining the performance and efficiency of energy storage devices. Graphene oxide and nanostructures of 3d transition metal oxides were synthesized for construction of electrodes in supercapacitors, and the electronic structure and oxidation states were probed using near-edge X-ray absorption fine structure. Understanding the chemistry of graphene oxide would provide valuable insight into its reactivity and properties as the graphene oxide transformation to reduced-graphene oxide is a key step in the synthesis of the electrode materials. Polarized behavior of the synchrotron X-rays and the angular dependency of the near-edge X-ray absorption fine structures (NEXAFS) have been utilized to study the orientation of the σ and π bonds of the graphene oxide and graphene oxide-metal oxide nanocomposites. The core-level transitions of individual metal oxides and that of the graphene oxide nanocomposite showed that the interaction of graphene oxide with the metal oxide nanostructures has not altered the electronic structure of either of them. As the restoration of the π network is important for good electrical conductivity, the C K edge NEXAFS spectra of reduced graphene oxide nanocomposites confirms the same through increased intensity of the sp 2 -derived unoccupied states π* band. A pronounced angular dependency of the reduced sample and the formation of excitonic peaks confirmed the formation of extended conjugated network.

Controlled synthesis and electrochemical properties of vanadium oxides with different nanostructures

International Nuclear Information System (INIS)

Zhang, Yifu; Zhou, Min; Huang, Chi; Chen, Chongxue; Cao, Yuliang; Fan, Meijuan; Li, Houbin; Liu, Xinghai; Xie, Guangyong

2012-01-01

Vanadium oxides (V 3 O 7 .H 2 O and VO 2 ) with different morphologies have been selectively synthesized by a facile hydrothermal approach using glucose as the reducing and structure-directing reagent. The as-obtained V 3 O 7 .H 2 O nanobelts have a length up to several tens of micrometers, width of about 60-150 nm and thickness of about 5-10 nm, while the as-prepared VO 2 (B) nanobelts have a length of about 1.0- 7 μm, width, 80-140 nm and thickness, 2-8 nm. It was found that the quantity of glucose, the reaction temperature and the reaction time had significant influence on the compositions and morphologies of final products. Vanadium oxides with different morphologies were easily synthesized by controlling the concentration of glucose. The formation mechanism was also briefly discussed, indicating that glucose played different roles in synthesizing various vanadium oxides. The phase transition from VO 2 (B) to VO 2 (M) were investigated and the phase transition temperature of the VO 2 (M) appeared at around 68 deg C. Furthermore, the electrochemical properties of V 3 O 7 .H 2 O nanobelts, VO 2 (B) nanobelts and VO 2 (B) nanosheets were investigated and they exhibited a high initial discharge capacity of 296, 247 and 227 mAh/g, respectively. (author)

Hysteresis phenomena at metal-semiconductor phase transformation in vanadium oxides

International Nuclear Information System (INIS)

Lanskaya, T.G.; Merkulov, I.A.; Chudnovski , F.A.

1978-01-01

The hysteresis phenomena during the metal-semiconductor phase transformation (MSPT) in vanadium oxides are investigated. It is shown experimentally that the hysteresis effects during MSPT in vanadium oxides are associated not only with the martensite nature of the transformation, but also with activation processes. It is shown that the hysteresis phenomena during MSPT may be described by the distribution function of microregions of the crystal in the phase transformation temperature T 0 and the coercive temperature Tsub(c). An experimental method for constructing this distribution function was worked out. An analysis of the experimental data shows that finely dispersed films are characterized by a wide range of values of T 0 and Tsub(c) (55 deg C 0 <65 deg C, 6 deg C< Tsub(c)<12 deg C). The peculiarities of the optical recording of information on monocrystal and finely dispersed films are considered

Researches on vanadium and its compounds; Recherches sur le Vanadium et ses composes

Energy Technology Data Exchange (ETDEWEB)

Morette, Andre

1937-06-03

In this research thesis, the author proposes a new study of the action of some reduction agents on two groups of vanadium compounds, oxides and chlorides. Thus, he reports the study of the circumstances of reduction of vanadium oxides by carbon and of vanadium carburization from these compounds. He also reports the determination of the composition of vanadium melts obtained at high temperatures (either in a vacuum furnace or with an electric arc furnace). In order to determine in which conditions the processing of vanadium oxides could produce the pure metal, the author studied the action of calcium and magnesium on the vanadium pentoxide and trioxide. The second part of the thesis addresses the preparation of pure vanadium from vanadium anhydride chlorides. Then, the author reports the development of processes which could easily produce powdered vanadium [French] Nous nous sommes propose de reprendre l'etude de l'action de quelques reducteurs sur les deux groupes de composes du vanadium, oxydes et chlorures. Nous avons ete ainsi amene a preciser les circonstances de la reduction des oxydes de vanadium par le carbone et de la carburation du vanadium a partir de ceux-ci, puis a determiner la constitution des fontes de vanadium obtenues a haute temperature, soit au four a vide, soit au four a arc. D'autre part, en vue de determiner dans quelles conditions le traitement des oxydes de vanadium pourrait conduire au metal pur, nous avons repris et complete des travaux anterieurs concernant l'action du calcium et du magnesium sur le pentoxyde ou eventuellement le trioxyde de vanadium. Une seconde partie de notre these a ete consacree a la preparation du vanadium pur a partir des chlorures anhydres de vanadium. Nous nous sommes attache a trouver le mode operatoire le plus favorable pour l'obtention de chacun d'eux. Il nous a ete donne ainsi l'occasion de preciser certaines de leurs proprietes physiques et chimiques. Puis, a la suite d'essais systematiques, nous avons

Roll-to-Roll Processing of Inverted Polymer Solar Cells using Hydrated Vanadium(V)Oxide as a PEDOT:PSS Replacement

DEFF Research Database (Denmark)

Martinez, Nieves Espinosa; Dam, Henrik Friis; Tanenbaum, David M.

2011-01-01

roll-to-roll (R2R) processing of all layers. The devices were prepared on flexible polyethyleneterphthalate (PET) and had the structure PET/ITO/ZnO/P3HT:PCBM/V2O5·(H2O)n/Ag. The ITO and silver electrodes were processed and patterned by use of screen printing. The zinc oxide, P3HT:PCBM and vanadium(V)oxide......The use of hydrated vanadium(V)oxide as a replacement of the commonly employed hole transporting material PEDOT:PSS was explored in this work. Polymer solar cells were prepared by spin coating on glass. Polymer solar cells and modules comprising 16 serially connected cells were prepared using full...... layers were processed by slot-die coating. The hydrated vanadium(V)oxide layer was slot-die coated using an isopropanol solution of vanadyl-triisopropoxide (VTIP). Coating experiments were carried out to establish the critical thickness of the hydrated vanadium(V)oxide layer by varying the concentration...

Effect of thermal treatment conditions on properties of vanadium molybdenum oxide catalyst in acrolein oxidation reaction to acrylic acid

International Nuclear Information System (INIS)

Gorshkova, T.P.; Tarasova, D.V.; Olen'kova, I.P.; Andrushkevich, T.V.; Nikoro, T.A.

1984-01-01

The effect of thermal treatment conditions (temperature and gas medium) on properties of vanadium molybdenum oxide catalyst in acrolein oxidation reaction to acrylic acid is investigated. It is shown that active and selective catalysts are formed in the course of thermal decomposition of the drying product of ammonium metavanadate and paramolybdate under the conditions ensuring the vanadium ion reduction up to tetravalent state with conservation of molybdenum oxidation degree equal to 6. It is possible to realize it either by treatment of the catalyst calcinated in the air flow at 300 deg by the reaction mixture at the activation stage or by gas-reducer flow treatment at 280 deg. Thermal treatment in the reducing medium of the oxidized catalyst does not lead to complete regeneration of its properties

Oxidation of vanadium carbide in air; Oxidacion de carburo de vanadio en aire

Energy Technology Data Exchange (ETDEWEB)

Ruiz, A.; Troiani, L.; Materan, E. [Universidad Simon Bolivar, Depto. de la Ciencia de los Materiales, Grupo de Ingenieria de Superficies e Interfaces, Caracas, Venezuela, (Venezuela)

1998-12-31

It was studied the samples oxidation of vanadium carbide (V{sub 8}C{sub 7}), synterized and in powder, in order to know the temperature influence and the aggregation state in the kinetics and the oxidation products. The assays were realized in static air, at temperature between 600 y 750 Centigrade, between 6 and 24 hours periods. The gaseous products were analyzed through gas chromatography while the condensates ones were analyzed through optical microscopy and scanning electron microscopy, X-ray diffraction and chemical analysis by X-ray fluorescence analysis. It was found that in the V{sub 8}C{sub 7} oxidation occurs two basic processes: the gaseous oxides production which results of the carbon oxidation, fundamentally CO{sub 2}, and the vanadium condensate oxides production, fundamentally V{sub 2}O{sub 5}. In the synterized samples assayed under 650 Centigrade, the kinetics is lineal with loss of mass, suggesting a control by the formation of gaseous products in the sample surface, while in the synterized samples assayed over 650 Centigrade, it occurs a neat gain of mass, which is attributed to vanadium pentoxide fusion. These processes produce stratified layers of V{sub 2}O{sub 5} although at higher temperatures also it was detected V{sub 2}O{sub 4}. The superficial area effect is revealed in what the powder samples always experiment a mass neat increase in all essay temperatures, being the condensate oxidation products, fundamentally V{sub 2}O{sub 5} and V{sub 6}O{sub 13}. (Author)

Hybrid chemical vapour and nanoceramic aerosol assisted deposition for multifunctional nanocomposite thin films

Energy Technology Data Exchange (ETDEWEB)

Warwick, Michael E.A.; Dunnill, Charles W.; Goodall, Josie; Darr, Jawwad A.; Binions, Russell, E-mail: uccarbi@ucl.ac.uk

2011-07-01

Hybrid atmospheric pressure chemical vapour and aerosol assisted deposition via the reaction of vanadium acetylacetonate and a suspension of preformed titanium dioxide or cerium dioxide nanoparticles, led to the production of vanadium dioxide nanocomposite thin films on glass substrates. The preformed nanoparticle oxides used for the aerosol were synthesised using a continuous hydrothermal flow synthesis route involving the rapid reaction of a metal salt solution with a flow of supercritical water in a flow reactor. Multifunctional nanocomposite thin films from the hybrid deposition process were characterised using scanning electron microscopy, X-ray diffraction and X-ray photoelectron spectroscopy. The functional properties of the films were evaluated using variable temperature optical measurements to assess thermochromic behaviour and methylene blue photodecolourisation experiments to assess photocatalytic activity. The tests show that the films are multifunctional in that they are thermochromic (having a large change in infra-red reflectivity upon exceeding the thermochromic transition temperature) and have significant photocatalytic activity under irradiation with 254 nm light.

Mesoporous binary metal oxide nanocomposites: Synthesis, characterization and decontamination of sulfur mustard

Energy Technology Data Exchange (ETDEWEB)

Praveen Kumar, J., E-mail: praveenjella10@gmail.com; Prasad, G.K.; Ramacharyulu, P.V.R.K.; Singh, Beer; Gopi, T.; Krishna, R.

2016-04-15

Mesoporous MnO{sub 2}–ZnO, Fe{sub 2}O{sub 3}–ZnO, NiO–ZnO, and CeO{sub 2}–ZnO binary metal oxide nanocomposites were studied as sorbent decontaminants against sulfur mustard. They were synthesized by precipitation pyrolysis method and characterized by means of transmission electron microscopy, scanning electron microscopy coupled with energy dispersive analysis of X rays, X ray diffraction, and nitrogen adsorption techniques. The transmission electron microscopy and nitrogen adsorption data indicated the presence of pores with diameter ranging from 10 to 70 nm in the binary metal oxide nanocomposites and these materials exhibited surface area values in the range of 76–134 m{sup 2}/g. These binary metal oxide nanocomposites demonstrated large decontamination efficiencies against sulfur mustard when compared to their single component metal oxide nanoparticles. The binary metal oxide nanocomposites effectively decontaminated sulfur mustard into relatively non toxic products such as chloro ethyl vinyl sulfide, divinyl sulfide, 1,4-oxathiane, etc. The promising decontamination properties of binary metal oxide nanocomposites against sulfur mustard were attributed to the basic sites, Lewis acid sites, and the presence of these sites was confirmed by CO{sub 2} and NH{sub 3} temperature programmed desorption. - Graphical abstract: Mesoporous MnO{sub 2}–ZnO, Fe{sub 2}O{sub 3}–ZnO, NiO–ZnO, and CeO{sub 2}–ZnO binary metal oxide nanocomposites were studied as sorbent decontaminants against sulfur mustard. - Highlights: • Binary metal oxide nanocomposites were synthesized by co-precipitation method. • They were studied as sorbent decontaminants against sulfur mustard. • They decontaminated sulfur mustard into non toxic products. • MnO{sub 2}–ZnO and CeO{sub 2}–ZnO nanocomposites showed greater decontamination efficiency.

Lithium-Vanadium bronzes as model catalysts for the selective reduction of nitric oxide

NARCIS (Netherlands)

Bosch, H.; Bongers, Annemie; Enoch, Gert; Snel, Ruud; Ross, Julian R.H.

1989-01-01

The effect of alkali metals on the selective reduction of nitric oxide with ammonia has been studied on bulk iron oxide and bulk vanadium oxide. The influence of additions of LiOH, NaOH and KOH on the activity was screened by pulse experiments carried out in the absence of gaseous oxygen; FTIR

Roll-to-Roll Processing of Inverted Polymer Solar Cells using Hydrated Vanadium(V)Oxide as a PEDOT:PSS Replacement.

Science.gov (United States)

Espinosa, Nieves; Dam, Henrik Friis; Tanenbaum, David M; Andreasen, Jens W; Jørgensen, Mikkel; Krebs, Frederik C

2011-01-11

The use of hydrated vanadium(V)oxide as a replacement of the commonly employed hole transporting material PEDOT:PSS was explored in this work. Polymer solar cells were prepared by spin coating on glass. Polymer solar cells and modules comprising 16 serially connected cells were prepared using full roll-to-roll (R2R) processing of all layers. The devices were prepared on flexible polyethyleneterphthalate (PET) and had the structure PET/ITO/ZnO/P3HT:PCBM/V₂O₅·(H₂O) n /Ag. The ITO and silver electrodes were processed and patterned by use of screen printing. The zinc oxide, P3HT:PCBM and vanadium(V)oxide layers were processed by slot-die coating. The hydrated vanadium(V)oxide layer was slot-die coated using an isopropanol solution of vanadyl-triisopropoxide (VTIP). Coating experiments were carried out to establish the critical thickness of the hydrated vanadium(V)oxide layer by varying the concentration of the VTIP precursor over two orders of magnitude. Hydrated vanadium(V)oxide layers were characterized by profilometry, scanning electron microscopy, energy dispersive X-ray spectroscopy, and grazing incidence wide angle X-ray scattering. The power conversion efficiency (PCE) for completed modules was up to 0.18%, in contrast to single cells where efficiencies of 0.4% were achieved. Stability tests under indoor and outdoor conditions were accomplished over three weeks on a solar tracker.

Metal oxide/polyaniline nanocomposites

Indian Academy of Sciences (India)

Nanocomposites of iron oxide with conducting polymer in the form of powders of varying compositions have been studied to understand the effects of particle size, cluster size and magnetic inter-particle interactions. The sizes of the nanoparticles were estimated to be ∼ 10–20 nm from the X-ray diffraction (XRD) and the ...

Metal oxide/polyaniline nanocomposites: Cluster size and ...

Indian Academy of Sciences (India)

Wintec

Metal oxide/polyaniline nanocomposites; structural properties; magnetic properties. 1. Introduction ... The powder obtained was ground in a motor and pestle, sonicated in ... Figure 1. XRD of (a) iron oxide nanoparticles and (b) iron oxide/PANI (1 : 0⋅4) composite. .... shape of the particles and the anisotropy energy, as also.

Preparation and characterization of polyindole - iron oxide nanocomposite electrolyte

International Nuclear Information System (INIS)

Rajasudha, G.; Stephen, A.; Narayanan, V.

2009-01-01

Full text: A novel polyindole-iron oxide containing LiClO 4 solid polymer electrolyte has been prepared. The diverse property of magnetic nanoparticle has elicited wide interest from the point of view of technological applications. Their properties are known to be strongly dependent on size, anisotropy and inter particle interactions. The proton conducting materials has received considerable attention as electrolyte materials in technological applications such as fuel cells, sensors and electrochromic display. In this work, polyindole-iron oxide nanocomposite containing LiClO 4 was prepared by in situ polymerization. The indole was polymerized in the presence of iron oxide, using ammonium peroxy disulphate as an oxidizing agent. The polyindole-iron oxide nanocomposite was characterized by XRD, IR, SEM, TGA and TEM. The iron oxide nano particles was incorporated into polyindole and was confirmed by XRD and Fourier transform infrared (FTIR) spectroscopy. The surface Morphology and thermal stability were studied by thermogravimetric analysis (TGA) and SEM respectively. The ionic conductivity of polyindole electrolyte was analyzed from impedance spectrum. The prepared polyindole-iron oxide nanocomposite could be used as solid electrolyte in lithium ion batteries

Graphene oxide--MnO2 nanocomposites for supercapacitors.

Science.gov (United States)

Chen, Sheng; Zhu, Junwu; Wu, Xiaodong; Han, Qiaofeng; Wang, Xin

2010-05-25

A composite of graphene oxide supported by needle-like MnO(2) nanocrystals (GO-MnO(2) nanocomposites) has been fabricated through a simple soft chemical route in a water-isopropyl alcohol system. The formation mechanism of these intriguing nanocomposites investigated by transmission electron microscopy and Raman and ultraviolet-visible absorption spectroscopy is proposed as intercalation and adsorption of manganese ions onto the GO sheets, followed by the nucleation and growth of the crystal species in a double solvent system via dissolution-crystallization and oriented attachment mechanisms, which in turn results in the exfoliation of GO sheets. Interestingly, it was found that the electrochemical performance of as-prepared nanocomposites could be enhanced by the chemical interaction between GO and MnO(2). This method provides a facile and straightforward approach to deposit MnO(2) nanoparticles onto the graphene oxide sheets (single layer of graphite oxide) and may be readily extended to the preparation of other classes of hybrids based on GO sheets for technological applications.

Fabrication and characterization of free-standing polypyrrole/graphene oxide nanocomposite paper

International Nuclear Information System (INIS)

Li Lanyan; Xia Keqiang; Li Liang; Shang Songmin; Guo Qingzhong; Yan Guoping

2012-01-01

Flexible polypyrrole/graphene oxide (GO) nanocomposite paper was prepared via a facile and one-step chemical oxidation polymerization method. The morphology and microstructure of the obtained papers were characterized by SEM, FTIR, and XRD. GO was confirmed experimentally to be exfoliated and uniformly dispersed in the resulting nanocomposites. The specific capacitance value of the nanocomposite paper has been determined to be about 330 F/g at a scan rate of 100 mV/s, suggesting the possible application of the nanocomposite as a supercapacitor electrode. After 700 cycles at a scan rate of 100 mV/s, only 9 % decrease in specific capacitance as compared to initial value indicates the superior electrochemical cyclic stability of the nanocomposite paper.

Dehydrogenation of Ethylbenzene with Carbon Dioxide as Soft Oxidant over Supported Vanadium-Antimony Oxide Catalyst

Energy Technology Data Exchange (ETDEWEB)

Hong, Do Young; Vislovskiy, Vladislav P.; Yoo, Jin S.; Chang, Jong San [Korea Research Institute of Chemical Technology, Daejeon (Korea, Republic of); Park, Sang Eon [Inha University, Incheon (Korea, Republic of); Park, Min Seok [Mongolia International University, Ulaanbaatar (Mongolia)

2005-11-15

This work presents that carbon dioxide, which is a main contributor to the global warming effect, could be utilized as a selective oxidant in the oxidative dehydrogenation of ethylbenzene. The dehydrogenation of ethylbenzene over alumina-supported vanadium-antimony oxide catalyst has been studied under different atmospheres such as inert nitrogen, steam, oxygen or carbon dioxide as diluent or oxidant. Among them, the addition of carbon dioxide gave the highest styrene yield (up to 82%) and styrene selectivity (up to 97%) along with stable activity. Carbon dioxide could play a beneficial role of a selective oxidant in the improvement of the catalytic behavior through the oxidative pathway.

Synthesis and characterization of alumina-supported vanadium oxide catalysts prepared by the molecular designed dispersion of VO(acac)2 complexes

NARCIS (Netherlands)

Weckhuysen, B.M.; Baltes, M.; Voort, P. van der; Ramachandra Rao, R.; Catana, Gabriela; Schoonheydt, R.A.; Vansant, E.F.

2000-01-01

Alumina-supported vanadium oxide catalysts have been prepared by the molecular designed dispersion method, using the vanadyl acetylacetonate complex (VO(acac)2). The complex has been adsorbed on the support from solution, followed by thermal conversion into the corresponding supported vanadium oxide

Graphene oxide/ferroferric oxide/polyethylenimine nanocomposites for Congo red adsorption from water.

Science.gov (United States)

Wang, Lina; Mao, Changming; Sui, Ning; Liu, Manhong; Yu, William W

2017-04-01

Graphene oxide/ferroferric oxide/polyethylenimine (GO/Fe 3 O 4 /PEI) nanocomposites were synthesized by an in situ growth of Fe 3 O 4 nanoparticles on GO sheets, and then modified by PEI. The GO/Fe 3 O 4 /PEI nanocomposites showed extremely high removal efficiency for anionic dye Congo Red (CR) due to the positively charged PEI molecules (methylene blue was also tested but with low adsorption capacity due to its cationic property). The CR removal capacity was 574.7 mg g -1 , higher than most of reported results. The adsorption kinetics could be well described by a pseudo-second-order model. Furthermore, GO/Fe 3 O 4 /PEI nanocomposites could be easily recycled by magnetic separation. The removal efficiency remained above 70% after five cycles.

Characterization polyethylene terephthalate nanocomposites mixing with nano-silica and titanium oxide

Directory of Open Access Journals (Sweden)

Rusu Mircea A.

2017-01-01

Full Text Available Polyethylene terephthalate (PET based nanocomposites containing nano-silica (Aerosil (Degusa and titanium oxide (TiO2 (Merk were prepared by melt compounding. Influence of nano-silica and titanium oxide on properties of the resulting nanocomposites was investigated by scanning electron microscopy (SEM, Fourier transform infrared spectroscopy (FTIR and atomic force microscopy (AFM. The possible interaction between nano-silica and titanium oxide particles with PET functional groups at bulk and surface was elucidated by transmission of FTIR-ATR spectroscopy. AFM studies of the resulting nanocomposites showed an increased surface roughness compared to pure PET. SEM images illustrated that nano-silica particles have tendency to migrate to the surface of the PET matrix much more than titanium oxide powder.

CO oxidation on Alsbnd Au nano-composite systems

Science.gov (United States)

Rajesh, C.; Majumder, C.

2018-03-01

Using first principles method we report the CO oxidation behaviour of Alsbnd Au nano-composites in three different size ranges: Al6Au8, Al13Au42 and a periodic slab of Alsbnd Au(1 1 1) surface. The clusters prefer enclosed structures with alternating arrangement of Al and Au atoms, maximising Auδ-sbnd Alδ+ bonds. Charge distribution analysis suggests the charge transfer from Al to Au atoms, corroborated by the red shift in the density of states spectrum. Further, CO oxidation on these nano-composite systems was investigated through both Eley - Rideal and Langmuir Hinshelwood mechanism. While, these clusters interact with O2 non-dissociatively with an elongation of the Osbnd O bond, further interaction with CO led to formation of CO2 spontaneously. On contrary, the CO2 evolution by co-adsorption of O2 and CO molecules has a transition state barrier. On the basis of the results it is inferred that nano-composite material of Alsbnd Au shows significant promise toward effective oxidative catalysis.

Vanadium Bioleaching Behavior by Acidithiobacillus ferrooxidans from a Vanadium-Bearing Shale

Directory of Open Access Journals (Sweden)

Dunpei Wei

2018-01-01

Full Text Available This study investigated bioleaching behavior of vanadium from a vanadium-bearing shale using Acidithiobacillus ferrooxidans (A. ferrooxidans. Results showed a maximum recovery of 62% vanadium in 1.2-day bioleaching, which was 22.45% higher than the controls. Then, the vanadium leaching efficiency decreased significantly, only 24% of that was obtained on the tenth day. The vanadium extraction in 1.2 days was mainly attributed to the dissolution of vanadium in free oxides of shale. Fe3+ produced by A. ferrooxidans promoted the dissolution process. X-ray diffraction (XRD patterns of the leached residues confirmed the generation of jarosite. SEM-EDS analysis of the residues indicated that jarosite adsorbed on the shale and inhibited the further dissolution of vanadium. The relevance of V, Fe, S, O was quite good in the energy disperse X-ray spectrometry (EDS element mapping of jarosite, and acid-washing of the jarosite resulted in 31.6% of the vanadium in the precipitates desorption, indicating that the decrease of vanadium leaching efficiency in bioleaching process was caused by both adsorption and co-precipitation with jarosite.

The active component of vanadium-molybdenum catalysts for the oxidation of acrolein to acrylic acid

International Nuclear Information System (INIS)

Andrushkevich, T.V.; Kuznetsova, T.G.

1986-01-01

The catalytic properties of the vanadium-molybdenum oxide system were investigated in the oxidation of acrolein to acrylic acid. The active component of the catalyst is the compound VMo 3 O 11 , the maximum amount of which is observed at a content of 7-15 mole% V 2 O 4 . The compound VMo 3 O 11 is formed in the thermodecomposition of silicomolybdovanadium heteropoly acids or isopoly compounds, reduced with respect to vanadium, and contains V 4+ and Mo 6+ . The optimum treatment for the formation of this compound is treatment in the reaction mixture at 400 degrees C

The oxidation of organic additives in the positive vanadium electrolyte and its effect on the performance of vanadium redox flow battery

Science.gov (United States)

Nguyen, Tam D.; Whitehead, Adam; Scherer, Günther G.; Wai, Nyunt; Oo, Moe O.; Bhattarai, Arjun; Chandra, Ghimire P.; Xu, Zhichuan J.

2016-12-01

Despite many desirable properties, the vanadium redox flow battery is limited, in the maximum operation temperature that can be continuously endured, before precipitation begins in the positive electrolyte. Many additives have been proposed to improve the thermal stability of the charged positive electrolyte. However, we have found that the apparent stability, revealed in laboratory testing, is often simply an artifact of the test method and arises from the oxidation of the additive, with corresponding partial reduction of V(V) to V(IV). This does not improve the stability of the electrolyte in an operating system. Here, we examined the oxidation of some typical organic additives with carboxyl, alcohol, and multi-functional groups, in sulfuric acid solutions containing V(V). The UV-vis measurements and titration results showed that many compounds reduced the state-of-charge (SOC) of vanadium electrolyte, for example, by 27.8, 88.5, and 81.9% with the addition of 1%wt of EDTA disodium salt, pyrogallol, and ascorbic acid, respectively. The cell cycling also indicated the effect of organic additives on the cell performance, with significant reduction in the usable charge capacity. In addition, a standard screening method for thermally stable additives was introduced, to quickly screen suitable additives for the positive vanadium electrolyte.

Study of propane partial oxidation on vanadium-containing catalysts

Energy Technology Data Exchange (ETDEWEB)

Komashko, G.A.; Khalamejda, S.V.; Zazhigalov, V.A. [AN Ukrainskoj SSR, Kiev (Ukraine). Inst. Fizicheskoj Khimii

1998-12-31

The present results indicate that maximum selectivity to acrylic acid can be reached over V-P-Zr-O catalysts. When the hydrocarbon concentration is 5.1 vol.% the selectivity is about 30% at quite high paraffin conversion. Conclusively, some explanations to the observed facts can be given. The V-P-O catalyst promotion with lanthanum by means of mechanochemical treatment is distinguished by the additive uniform spreading all over the matrix surface. Such twophase system is highly active in propane conversion (lanthanum oxide) and further oxidation of the desired products. The similar properties are attributed to V-P-Bi-La-O catalyst. Bismuth, tellurium and zirconium additives having clearly defined acidic properties provoke the surface acidity strengthening and make easier desorption of the acidic product (acrylic acid) from the surface lowering its further oxidation. Additionally, since bismuth and zirconium are able to form phosphates and, according to, to create space limitations for the paraffin molecule movement out of the active group boundaries, this can be one more support in favour of the selectivity increase. With this point of view very interesting results were obtained. It has been shown that the more limited the size of the vanadium unit, the higher the selectivity is. Monoclinic phase AV{sub 2}P{sub 2}O{sub 10} which consists in clusters of four vanadium atoms is sensibly more reactive than the orthorhombic phase consists in V{sub {infinity}} infinite chains. (orig.)

Mineralogy and geochemistry of vanadium in the Colorado Plateau

Science.gov (United States)

Weeks, A.D.

1961-01-01

The chief domestic source of vanadium is uraniferous sandstone in the Colorado Plateau. Vanadium is 3-, 4-, or 5-valent in nature and, as oxides or combined with other elements, it forms more than 40 minerals in the Plateau ores. These ores have been studied with regard to the relative amounts of vanadium silicates and oxide-vanadates, uranium-vanadium ratios, the progressive oxidation of black low-valent ores to high-valent carnotite-type ores, and theories of origin. ?? 1961.

Conjugated polymer/graphene oxide nanocomposite as thermistor

Energy Technology Data Exchange (ETDEWEB)

Joshi, Girish M., E-mail: varadgm@gmail.com; Deshmukh, Kalim [Polymer Nanocomposite Laboratory, Material Physics Division, School of Advanced Sciences, VIT University, Vellore - 632014, TN (India)

2015-06-24

We demonstrated the synthesis and measurement of temperature dependent electrical resistivity of graphene oxide (GO) reinforced poly (3, 4 - ethylenedioxythiophene) - tetramethacrylate (PEDOTTMA)/Polymethylmethacrylate (PMMA) based nanocomposites. Negative temperature coefficient (NTC) was observed for 0.5, 1 % GO loading and the positive temperature coefficient (PTC) was observed for 1.5 and 2 % Go loading in the temperature (40 to 120 °C). The GO inducted nanocomposite perform as an excellent thermistor and suitable for electronic and sensor domain.

Conjugated polymer/graphene oxide nanocomposite as thermistor

International Nuclear Information System (INIS)

Joshi, Girish M.; Deshmukh, Kalim

2015-01-01

We demonstrated the synthesis and measurement of temperature dependent electrical resistivity of graphene oxide (GO) reinforced poly (3, 4 - ethylenedioxythiophene) - tetramethacrylate (PEDOTTMA)/Polymethylmethacrylate (PMMA) based nanocomposites. Negative temperature coefficient (NTC) was observed for 0.5, 1 % GO loading and the positive temperature coefficient (PTC) was observed for 1.5 and 2 % Go loading in the temperature (40 to 120 °C). The GO inducted nanocomposite perform as an excellent thermistor and suitable for electronic and sensor domain

Importance of Vanadium-Catalyzed Oxidation of SO2to SO3in Two-Stroke Marine Diesel Engines

DEFF Research Database (Denmark)

Colom, Juan M.; Alzueta, María U.; Christensen, Jakob Munkholt

2016-01-01

Low-speed marine diesel engines are mostly operated on heavy fuel oils, which have a high content of sulfur andash, including trace amounts of vanadium, nickel, and aluminum. In particular, vanadium oxides could catalyze in-cylinderoxidation of SO2 to SO3, promoting the formation of sulfuric acid...

Vanadium Electrolyte Studies for the Vanadium Redox Battery-A Review.

Science.gov (United States)

Skyllas-Kazacos, Maria; Cao, Liuyue; Kazacos, Michael; Kausar, Nadeem; Mousa, Asem

2016-07-07

The electrolyte is one of the most important components of the vanadium redox flow battery and its properties will affect cell performance and behavior in addition to the overall battery cost. Vanadium exists in several oxidation states with significantly different half-cell potentials that can produce practical cell voltages. It is thus possible to use the same element in both half-cells and thereby eliminate problems of cross-contamination inherent in all other flow battery chemistries. Electrolyte properties vary with supporting electrolyte composition, state-of-charge, and temperature and this will impact on the characteristics, behavior, and performance of the vanadium battery in practical applications. This Review provides a broad overview of the physical properties and characteristics of the vanadium battery electrolyte under different conditions, together with a description of some of the processing methods that have been developed to produce vanadium electrolytes for vanadium redox flow battery applications. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Electrochemical Properties of Graphene-vanadium Oxide Composite Prepared by Electro-deposition for Electrochemical Capacitors

International Nuclear Information System (INIS)

Jeong, Heeyoung; Jeong, Sang Mun

2015-01-01

The nanostructural graphene/vanadium oxide (graphene/V 2 O 5 ) composite with enhanced capacitance was synthesized by the electro-deposition in 0.5 M VOSO 4 solution. The morphology of composites was characterized using scanning electron microscopy (SEM), x-ray diffraction pattern (XRD), and x-ray photoelectron spectroscopy (XPS). The oxidation states of the electro-deposited vanadium oxide was found to be V 5+ and V 4+ . The morphology of the prepared graphene/V 2 O 5 composite exhibits a netlike nano-structure with V 2 O 5 nanorods in about 100 nm diameter, which could lead a better contact between electrolyte an electrode. The composite with a deposition time of 4,000 s exhibits the specific capacitance of 854 mF/cm 2 at a scan rate of 20 mV/s and the capacitance retention of 53% after 1000 CV cycles

Synthesis of vanadium oxide powders by evaporative decomposition of solutions

International Nuclear Information System (INIS)

Lawton, S.A.; Theby, E.A.

1995-01-01

Powders of the vanadium oxides V 2 O 4 , V 6 O 13 , and V 2 O 5 were produced by thermal decomposition of aqueous solutions of vanadyl sulfate hydrate in atmospheres of N 2 , H 2 mixed with N 2 , or air. The composition of the oxide powder was determined by the reactor temperature and gas composition. Residual sulfur concentrations in powders produced by decomposition at 740 C were less than 1 at.%, and these powders consisted of hollow, roughly spherical aggregates of particles less than 1 microm in diameter

Topotactic synthesis of vanadium nitride solid foams

International Nuclear Information System (INIS)

Oyama, S.T.; Kapoor, R.; Oyama, H.T.; Hofmann, D.J.; Matijevic, E.

1993-01-01

Vanadium nitride has been synthesized with a surface area of 120 m 2 g -1 by temperature programmed nitridation of a foam-like vanadium oxide (35 m 2 g -1 ), precipitated from vanadate solutions. The nitridation reaction was established to be topotactic and pseudomorphous by x-ray powder diffraction and scanning electron microscopy. The crystallographic relationship between the nitride and oxide was {200}//{001}. The effect of precursor geometry on the product size and shape was investigated by employing vanadium oxide solids of different morphologies

Oxygen Barrier Properties and Melt Crystallization Behavior of Poly(ethylene terephthalate)/Graphene Oxide Nanocomposites

OpenAIRE

Szymczyk, Anna; Paszkiewicz, Sandra; Pawelec, Iwona; Lisiecki, Slawomir; Jotko, Marek; Spitalsky, Zdenko; Mosnácek, Jaroslav; Roslaniec, Zbigniew

2015-01-01

Poly(ethylene terephthalate) nanocomposites with low loading (0.1–0.5 wt%) of graphene oxide (GO) have been prepared by using in situ polymerization method. TEM study of nanocomposites morphology has shown uniform distribution of highly exfoliated graphene oxide nanoplatelets in PET matrix. Investigations of oxygen permeability of amorphous films of nanocomposites showed that the nanocomposites had better oxygen barrier properties than the neat PET. The improvement of oxygen permeability for ...

Facile hydrothermal preparation of titanium dioxide decorated reduced graphene oxide nanocomposite

Science.gov (United States)

Chang, Betty Yea Sze; Huang, Nay Ming; An’amt, Mohd Nor; Marlinda, Abdul Rahman; Norazriena, Yusoff; Muhamad, Muhamad Rasat; Harrison, Ian; Lim, Hong Ngee; Chia, Chin Hua

2012-01-01

A simple single-stage approach, based on the hydrothermal technique, has been introduced to synthesize reduced graphene oxide/titanium dioxide nanocomposites. The titanium dioxide nanoparticles are formed at the same time as the graphene oxide is reduced to graphene. The triethanolamine used in the process has two roles. It acts as a reducing agent for the graphene oxide as well as a capping agent, allowing the formation of titanium dioxide nanoparticles with a narrow size distribution (~20 nm). Transmission electron micrographs show that the nanoparticles are uniformly distributed on the reduced graphene oxide nanosheet. Thermogravimetric analysis shows the nanocomposites have an enhanced thermal stability over the original components. The potential applications for this technology were demonstrated by the use of a reduced graphene oxide/titanium dioxide nanocomposite-modified glassy carbon electrode, which enhanced the electrochemical performance compared to a conventional glassy carbon electrode when interacting with mercury(II) ions in potassium chloride electrolyte. PMID:22848166

Extreme Mechanical Behavior of Nacre-Mimetic Graphene-Oxide and Silk Nanocomposites.

Science.gov (United States)

Xie, Wanting; Tadepalli, Sirimuvva; Park, Sang Hyun; Kazemi-Moridani, Amir; Jiang, Qisheng; Singamaneni, Srikanth; Lee, Jae-Hwang

2018-02-14

Biological materials have the ability to withstand extreme mechanical forces due to their unique multilevel hierarchical structure. Here, we fabricated a nacre-mimetic nanocomposite comprised of silk fibroin and graphene oxide that exhibits hybridized dynamic responses arising from alternating high-contrast mechanical properties of the components at the nanoscale. Dynamic mechanical behavior of these nanocomposites is assessed through a microscale ballistic characterization using a 7.6 μm diameter silica sphere moving at a speed of approximately 400 m/s. The volume fraction of graphene oxide in these composites is systematically varied from 0 to 32 vol % to quantify the dynamic effects correlating with the structural morphologies of the graphene oxide flakes. Specific penetration energy of the films rapidly increases as the distribution of graphene oxide flakes evolves from noninteracting, isolated sheets to a partially overlapping continuous sheet. The specific penetration energy of the nanocomposite at the highest graphene oxide content tested here is found to be significantly higher than that of Kevlar fabrics and close to that of pure multilayer graphene. This study evidently demonstrates that the morphologies of nanoscale constituents and their interactions are critical to realize scalable high-performance nanocomposites using typical nanomaterial constituents having finite dimensions.

Lithium diffusion in silver vanadium oxide

International Nuclear Information System (INIS)

Takeuchi, E.S.; Thiebolt, W.C. III

1989-01-01

Lithium/silver vanadium oxide (SVO) batteries have been developed to power implantable devices. The voltage of Li/SVO cells decreases with discharge allowing state of charge assessment by accurate determination of the cells' open circuit voltage. The open circuit voltage recovery of Li/SVO cells was monitored during intermittent high rate discharge. It was found that the voltage does not recover at the same rate or magnitude at all depths of discharge. The authors describe lithium diffusion in SVO studied by low scan rate voltammetry where utilization of SVO at various scan rates was used to determine the diffusion rate of lithium. A pulse technique was also used where the rate of lithium diffusion was measured at various depths of discharge

Fabrication of polypyrrole/vanadium oxide nanotube composite with enhanced electrochemical performance as cathode in rechargeable batteries

International Nuclear Information System (INIS)

Zhou, Xiaowei; Chen, Xu; He, Taoling; Bi, Qinsong; Sun, Li; Liu, Zhu

2017-01-01

Highlights: • VO_xNTs were hydrothermally prepared using C_1_2H_2_7N as soft template with scalability. • Polypyrrole/VO_xNTs with less C_1_2H_2_7N template and higher conductivity were obtained. • Polypyrrole/VO_xNTs exhibit better performance as cathode for LIBs compared to VO_xNTs. • Further modification to VO_xNTs with desired electrochemical property can be expected. - Abstract: Vanadium oxide nanotubes (VO_xNTs) with hollow as well as multi-walled features were fabricated under hydrothermal condition by soft-template method. This novel VO_xNTs can be used as cathode material for lithium ion batteries (LIBs), but displaying low specific capacity and poor cycling performance owing to the residual of a mass of soft-template (C_1_2H_2_7N) and intrinsic low conductivity of VO_x. Cation exchange technique and oxidative polymerization process of pyrrole monomers were conducted to wipe off partial soft-template without electrochemical activity within VO_xNTs and simultaneously form polypyrrole coating on VO_xNTs, respectively. The resulting polypyrrole/VO_xNTs nanocomposite delivers much improved capacity and cyclic stability. Further optimizations, such as complete elimination of organic template and enhancing the crystallinity, can make this unique nanostructure a promising cathode for LIBs.

Fabrication of polypyrrole/vanadium oxide nanotube composite with enhanced electrochemical performance as cathode in rechargeable batteries

Energy Technology Data Exchange (ETDEWEB)

Zhou, Xiaowei, E-mail: zhouxiaowei@ynu.edu.cn [Department of Physics, School of Physics and Astronomy, Yunnan University, Kunming 650504, Yunnan (China); Chen, Xu; He, Taoling; Bi, Qinsong [Department of Physics, School of Physics and Astronomy, Yunnan University, Kunming 650504, Yunnan (China); Sun, Li [Department of Physics, School of Physics and Astronomy, Yunnan University, Kunming 650504, Yunnan (China); Department of Mechanical Engineering, University of Houston, Houston 77204, TX (United States); Liu, Zhu, E-mail: zhuliu@ynu.edu.cn [Department of Physics, School of Physics and Astronomy, Yunnan University, Kunming 650504, Yunnan (China); Yunnan Key Laboratory of Micro/Nano-Materials and Technology, Yunnan University, Kunming 650091, Yunnan (China)

2017-05-31

Highlights: • VO{sub x}NTs were hydrothermally prepared using C{sub 12}H{sub 27}N as soft template with scalability. • Polypyrrole/VO{sub x}NTs with less C{sub 12}H{sub 27}N template and higher conductivity were obtained. • Polypyrrole/VO{sub x}NTs exhibit better performance as cathode for LIBs compared to VO{sub x}NTs. • Further modification to VO{sub x}NTs with desired electrochemical property can be expected. - Abstract: Vanadium oxide nanotubes (VO{sub x}NTs) with hollow as well as multi-walled features were fabricated under hydrothermal condition by soft-template method. This novel VO{sub x}NTs can be used as cathode material for lithium ion batteries (LIBs), but displaying low specific capacity and poor cycling performance owing to the residual of a mass of soft-template (C{sub 12}H{sub 27}N) and intrinsic low conductivity of VO{sub x}. Cation exchange technique and oxidative polymerization process of pyrrole monomers were conducted to wipe off partial soft-template without electrochemical activity within VO{sub x}NTs and simultaneously form polypyrrole coating on VO{sub x}NTs, respectively. The resulting polypyrrole/VO{sub x}NTs nanocomposite delivers much improved capacity and cyclic stability. Further optimizations, such as complete elimination of organic template and enhancing the crystallinity, can make this unique nanostructure a promising cathode for LIBs.

Structure and conductive properties of poly(ethylene oxide)/layered double hydroxide nanocomposite polymer electrolytes

International Nuclear Information System (INIS)

Liao, C.-S.; Ye, W.-B.

2004-01-01

The oligo(ethylene oxide) modified layered double hydroxide (LDH) prepared by template method was added as a nanoscale nucleating agent into poly(ethylene oxide) (PEO) to form PEO/OLDH nanocomposite electrolytes. The effects of OLDH addition on morphology and conductivities of nanocomposite electrolytes were studied using wide-angle X-ray diffractometer, polarized optical microscopy, differential scanning calorimetry and ionic conductivity measurement. The results show that the exfoliated morphology of nanocomposites is formed due to the surface modification of LDH layers with PEO matrix compatible oligo(ethylene oxide)s. The nanoscale dispersed OLDH layers inhibit the crystal growth of PEO crystallites and result in a plenty amount of intercrystalline grain boundary within PEO/OLDH nanocomposites. The ionic conductivities of nanocomposite electrolytes are enhanced by three orders of magnitude compared to the pure PEO polymer electrolytes at ambient temperature. It can be attributed to the ease transport of Li + along intercrystalline amorphous phase. This novel nanocomposite electrolytes system with high conductivities will be benefited to fabricate the thin-film type of Li-polymer secondary battery

Thermochemistry of the complex oxides of uranium, vanadium, and alkali metals

International Nuclear Information System (INIS)

Karyakin, N.V.; Chernorukov, N.G.; Suleimanov, E.V.; Kharyushina, E.A.

1992-01-01

The standard enthalpies of the formation at T 298.15 K of complex oxides of uranium(VI), vanadium(V) and alkali metals with the general formula M 1 VUO 6 where M 1 = Na, K, Rb, and Cs, were calculated from the results of calorimetric experiments and from published data. 8 refs., 1 tab

Ion-exchange preparation of high-purity vanadium acid from industrial liquors

International Nuclear Information System (INIS)

Sajdakhmedov, U.A.; Arslanov, Sh.S.; Vulikh, A.I.

1994-01-01

The results of investigations on production of special-purity vanadium acid and vanadium oxide directly from process solutions (technical grade liquors) using ionites are presented. Potentiality of thorough purification of vanadium(5) oxide, when producing vanadium acid on the KU-2 cationite with subsequent purification on anionite, is shown. On the basis of the results obtained a principle flowsheet of ion-exchange production of high-purity vanadium(5) oxide from industrial liquors has been developed. 2 refs.; 1 fig.; 4 tabs

A new oxidimetric reagent: potassium dichromate in a strong phosphoric acid medium-VI Potentiometric titration of vanadium(III) alone and in mixture with vanadium(IV).

Science.gov (United States)

Rao, G G; Rao, P K

1966-09-01

Vanadium(III) can be titrated at room temperature with potassium dichromate in an 8-12M phosphoric acid medium. Two potential breaks are observed in 12M phosphoric add with 0.2N potassium dichromate, the first corresponding to the oxidation of vanadium(III) to vanadium(IV) and the second to the oxidation of vanadium(IV) to vanadium(V). In titrations with 0.05N dichromate only the first break in potential is clearly observed. The method has been extended to the titration of mixtures of vanadium(III) and vanadium(IV). Conditions have also been found for the visual titration of vanadium(III) using ferroln or barium diphenylamine sulphonate as indicator.

Enhanced photoluminescence in transparent thin films of polyaniline–zinc oxide nanocomposite prepared from oleic acid modified zinc oxide nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Sajimol Augustine, M., E-mail: sajimollazar@gmail.com [Department of Physics, St. Teresa' s College, Kochi-11, Kerala (India); Jeeju, P.P.; Varma, S.J.; Francis Xavier, P.A. [Division for Research in Advanced Materials, Department of Physics, Cochin University of Science and Technology, Kochi-22, Kerala (India); Jayalekshmi, S., E-mail: lakshminathcusat@gmail.com [Division for Research in Advanced Materials, Department of Physics, Cochin University of Science and Technology, Kochi-22, Kerala (India)

2014-07-01

Oleic acid capped zinc oxide (ZnO) nanoparticles have been synthesized by a wet chemical route. The chemical oxidative method is employed to synthesize polyaniline (PANI) and PANI/ZnO nanocomposites doped with four different dopants such as orthophosphoric acid (H{sub 3}PO{sub 4}), hydrochloric acid (HCl), naphthalene-2-sulphonic acid and camphor sulphonic acid (CSA). The samples have been structurally characterized by X-ray diffraction (XRD), field emission scanning electron microscopy and Fourier transform infrared (FT-IR) spectroscopic techniques. A comparison of the photoluminescence (PL) emission intensity of PANI and PANI/ZnO nanocomposites is attempted. The enhanced PL intensity in PANI/ZnO nanocomposites is caused by the presence of nanostructured and highly fluorescent ZnO in the composites. It has been observed that, among the composites, the H{sub 3}PO{sub 4} doped PANI/ZnO nanocomposite is found to exhibit the highest PL intensity because of the higher extent of (pi) conjugation and the more orderly arrangement of the benzenoid and quinonoid units. In the present work, transparent thin films of PANI and PANI/ZnO nanocomposite for which PL intensity is found to be maximum, have been prepared after re-doping with CSA by the spin-coating technique. The XRD pattern of the PANI/ZnO film shows exceptionally good crystallanity compared to that of pure PANI, which suggests that the addition of ZnO nanocrystals helps in enhancing the crystallanity of the PANI/ZnO nanocomposite. There is a significant increase in the PL emission intensity of the PANI/ZnO nanocomposite film making it suitable for the fabrication of optoelectronic devices. - Highlights: • Oleic acid capped zinc oxide nanoparticles are synthesized by wet chemical method. • Polyaniline/zinc oxide nanocomposites are prepared by in-situ polymerization. • Polyaniline and polyaniline/zinc oxide thin films are deposited using spin-coating. • Enhanced photoluminescence is observed in polyaniline

Mesoporous C/CrN and C/VN Nanocomposites Obtained by One-Pot Soft-Templating Process

Directory of Open Access Journals (Sweden)

Julien Kiener

2016-07-01

Full Text Available Nanocomposites of ordered mesoporous carbon associated with chromium nitride (CrN or vanadium nitride (VN nanoparticles were obtained by a simple one-pot synthesis based on the solvent evaporation induced self-assembly (EISA process using Pluronic triblock surfactant as soft-template and a phenol-based resin (resol as carbon precursor. These nanocomposites were characterized by X-ray diffraction, nitrogen physisorption and Transmission Electron Microscopy (TEM techniques. Electron tomography (or 3D-TEM technique was particularly useful for providing direct insight on the internal architecture of C/CrN nanocomposite. Nanocomposites showed a very well organized hexagonal mesoporous carbon structure and a relatively high concentration of nanoparticles well distributed in the porous network. The chromium and vanadium nitrides/mesoporous carbon nanocomposites could have many potential applications in catalysis, Li-ion batteries, and supercapacitors.

Co3O4/reduced graphene oxide nanocomposite for removal of organic pollutants from aqueous medium

Science.gov (United States)

Mishra, Amodini; Kuanr, B. K.; Mohanty, T.

2017-05-01

The magnetic nanocomposite (MNC) of cobalt oxide/graphene oxide (Co3O4/rGO) has been synthesized by hydrothermal method to demonstrate its use as organic pollutants remover. The phase formation of the cobalt oxide magnetic nanoparticles (MNPs) has been confirmed by X-ray diffraction (XRD) analysis. The nanocomposite has been characterized by Raman spectroscopic technique and two Raman peaks associated with graphene oxide are observed. The morphological study of the nanocomposite has been done using scanning electron microscope (SEM). The nanocomposite has been used for removal of organic pollutants from aqueous medium by using ultra-violet spectroscopy.

Aqueous vanadium ion dynamics relevant to bioinorganic chemistry: A review.

Science.gov (United States)

Kustin, Kenneth

2015-06-01

Aqueous solutions of the four highest vanadium oxidation states exhibit four diverse colors, which only hint at the diverse reactions that these ions can undergo. Cationic vanadium ions form complexes with ligands; anionic vanadium ions form complexes with ligands and self-react to form isopolyanions. All vanadium species undergo oxidation-reduction reactions. With a few exceptions, elucidation of the dynamics of these reactions awaited the development of fast reaction techniques before the kinetics of elementary ligation, condensation, reduction, and oxidation of the aqueous vanadium ions could be investigated. As the biological roles played by endogenous and therapeutic vanadium expand, it is appropriate to bring the results of the diverse kinetics studies under one umbrella. To achieve this goal this review presents a systematic examination of elementary aqueous vanadium ion dynamics. Copyright © 2014 Elsevier Inc. All rights reserved.

Efficiency improvement of multicrystalline silicon solar cells after surface and grain boundaries passivation using vanadium oxide

Energy Technology Data Exchange (ETDEWEB)

Derbali, L., E-mail: rayan.slat@yahoo.fr [Photovoltaiec Laboratory, Research and Technology Center of Energy, Technopole de Borj-Cedria, BP 95, Hammam-Lif 2050 (Tunisia); Ezzaouia, H. [Photovoltaiec Laboratory, Research and Technology Center of Energy, Technopole de Borj-Cedria, BP 95, Hammam-Lif 2050 (Tunisia)

2012-08-01

Highlights: Black-Right-Pointing-Pointer Evaporation of vanadium pentoxide onto the front surface leads to reduce the surface reflectivity considerably. Black-Right-Pointing-Pointer An efficient surface passivation can be obtained after thermal treatment of obtained films. Black-Right-Pointing-Pointer Efficiency of the obtained solar cells has been improved noticeably after thermal treatment of deposited thin films. - Abstract: The aim of this work is to investigate the effect of vanadium oxide deposition onto the front surface of multicrystalline silicon (mc-Si) substrat, without any additional cost in the fabrication process and leading to an efficient surface and grain boundaries (GBs) passivation that have not been reported before. The lowest reflectance of mc-Si coated with vanadium oxide film of 9% was achieved by annealing the deposited film at 600 Degree-Sign C. Vanadium pentoxide (V{sub 2}O{sub 5}) were thermally evaporated onto the surface of mc-Si substrates, followed by a short annealing duration at a temperature ranging between 600 Degree-Sign C and 800 Degree-Sign C, under O{sub 2} atmosphere. The chemical composition of the films was analyzed by means of Fourier transform infrared spectroscopy (FTIR). Surface and cross-section morphology were determined by atomic force microscope (AFM) and a scanning electron microscope (SEM), respectively. The deposited vanadium oxide thin films make the possibility of combining in one processing step an antireflection coating deposition along with efficient surface state passivation, as compared to a reference wafer. Silicon solar cells based on untreated and treated mc-Si wafers were achieved. We showed that mc-silicon solar cells, subjected to the above treatment, have better short circuit currents and open-circuit voltages than those made from untreated wafers. Thus, the efficiency of obtained solar cells has been improved.

Efficiency improvement of multicrystalline silicon solar cells after surface and grain boundaries passivation using vanadium oxide

International Nuclear Information System (INIS)

Derbali, L.; Ezzaouia, H.

2012-01-01

Highlights: ► Evaporation of vanadium pentoxide onto the front surface leads to reduce the surface reflectivity considerably. ► An efficient surface passivation can be obtained after thermal treatment of obtained films. ► Efficiency of the obtained solar cells has been improved noticeably after thermal treatment of deposited thin films. - Abstract: The aim of this work is to investigate the effect of vanadium oxide deposition onto the front surface of multicrystalline silicon (mc-Si) substrat, without any additional cost in the fabrication process and leading to an efficient surface and grain boundaries (GBs) passivation that have not been reported before. The lowest reflectance of mc-Si coated with vanadium oxide film of 9% was achieved by annealing the deposited film at 600 °C. Vanadium pentoxide (V 2 O 5 ) were thermally evaporated onto the surface of mc-Si substrates, followed by a short annealing duration at a temperature ranging between 600 °C and 800 °C, under O 2 atmosphere. The chemical composition of the films was analyzed by means of Fourier transform infrared spectroscopy (FTIR). Surface and cross-section morphology were determined by atomic force microscope (AFM) and a scanning electron microscope (SEM), respectively. The deposited vanadium oxide thin films make the possibility of combining in one processing step an antireflection coating deposition along with efficient surface state passivation, as compared to a reference wafer. Silicon solar cells based on untreated and treated mc-Si wafers were achieved. We showed that mc-silicon solar cells, subjected to the above treatment, have better short circuit currents and open-circuit voltages than those made from untreated wafers. Thus, the efficiency of obtained solar cells has been improved.

Reduced graphene oxide/CeO{sub 2} nanocomposite with enhanced photocatalytic performance

Energy Technology Data Exchange (ETDEWEB)

Kaur, Jasmeet, E-mail: jasmeet.dayal@gmail.com; Anand, Kanika; Singh, Gurpreet; Hastir, Anita; Virpal,; Singh, Ravi Chand [Laboratory For Sensors and Physics Education, Department of Physics, GND University, Amritsar-143005 (India); Anand, Kanica [Semiconductors Laboratory, Department of Physics, GND University, Amritsar– 143005 (India)

2015-05-15

In this work, reduced graphene oxide /cerium oxide (RGO/CeO{sub 2}) nanocomposite was synthesized by in situ reduction of cerium nitrate Ce(NO{sub 3}){sub 3}·6H{sub 2}O in the presence of graphene oxide by hydrazine hydrate (N{sub 2}H{sub 4}.H{sub 2}O). The intrinsic characteristics of as-prepared nanocomposite were studied using powder x-ray diffraction (XRD), Raman spectroscopy and field-emission scanning electron microscopy (FESEM). The photocatalytic degradation of methylene blue (MB) was employed as a model reaction to evaluate the photocatalytic activity of the RGO/CeO{sub 2} nanocomposite. The as-obtained RGO/CeO{sub 2} nanocomposite displays a significantly enhanced photocatalytic degradation of MB dye in comparison with bare CeO{sub 2} nanoparticles under sunlight irradiation, which can be attributed to the improved separation of electron-hole pairs and enhanced adsorption performance due to presence of RGO.

Synthesis of graphene oxide-copper molybdate (GO-CuM) nanocomposites for photocatalytic application

Science.gov (United States)

Singh, Gajendar; Bhargava, V. Sai; Sharma, Manu

2018-05-01

Transition metal molybdates (TMBs) MMoO4 (M=Ni, Cu, Fe, Zn, Co, etc.) based nanocomposites have been considered as remarkable materials in the field of electronics, optics, catalysis, supercapicitors and energy storage devices. Nanocomposites of TMBs with graphene oxide have also been chosen as an effective material in photocatalytic application. GO-CuM nanocomposites were synthesized by ultra-sonication method at RT, followed by reflux route for preparation of CuM and GO by modified Hemmer's method. As prepared nanocomposites were characterized using analytical techniques such as PXRD, SEM, FT-IR and UV-Visible spectroscopy. The enhanced photocatalytic activity of Methylene blue (MB) dye was observed by GO-CuM nanocomposites as compared to pure copper molybdate. GO-CuM nanocomposites show high photodegradation rate (0.094 min-1) whereas CuM was degraded only 30 % with the rate of 0.0029 min-1. The high photocatalytic efficiency is due to the presence of graphene oxide that helps to delay the charge recombination in photocatalytic reaction The effect of the different amount of graphene oxide on the photocatalytic activity of as prepared photocatalyst has also been investigated.

Vanadium induces dopaminergic neurotoxicity via protein kinase Cdelta dependent oxidative signaling mechanisms: Relevance to etiopathogenesis of Parkinson's disease

International Nuclear Information System (INIS)

Afeseh Ngwa, Hilary; Kanthasamy, Arthi; Anantharam, Vellareddy; Song, Chunjuan; Witte, Travis; Houk, Robert; Kanthasamy, Anumantha G.

2009-01-01

Environmental exposure to neurotoxic metals through various sources including exposure to welding fumes has been linked to an increased incidence of Parkinson's disease (PD). Welding fumes contain many different metals including vanadium typically present as particulates containing vanadium pentoxide (V 2 O 5 ). However, possible neurotoxic effects of this metal oxide on dopaminergic neuronal cells are not well studied. In the present study, we characterized vanadium-induced oxidative stress-dependent cellular events in cell culture models of PD. V 2 O 5 was neurotoxic to dopaminergic neuronal cells including primary nigral dopaminergic neurons and the EC 50 was determined to be 37 μM in N27 dopaminergic neuronal cell model. The neurotoxic effect was accompanied by a time-dependent uptake of vanadium and upregulation of metal transporter proteins Tf and DMT1 in N27 cells. Additionally, vanadium resulted in a threefold increase in reactive oxygen species generation, followed by release of mitochondrial cytochrome c into cytoplasm and subsequent activation of caspase-9 (> fourfold) and caspase-3 (> ninefold). Interestingly, vanadium exposure induced proteolytic cleavage of native protein kinase Cdelta (PKCδ, 72-74 kDa) to yield a 41 kDa catalytically active fragment resulting in a persistent increase in PKCδ kinase activity. Co-treatment with pan-caspase inhibitor Z-VAD-FMK significantly blocked vanadium-induced PKCδ proteolytic activation, indicating that caspases mediate PKCδ cleavage. Also, co-treatment with Z-VAD-FMK almost completely inhibited V 2 O 5 -induced DNA fragmentation. Furthermore, PKCδ knockdown using siRNA protected N27 cells from V 2 O 5 -induced apoptotic cell death. Collectively, these results demonstrate that vanadium can exert neurotoxic effects in dopaminergic neuronal cells via caspase-3-dependent PKCδ cleavage, suggesting that metal exposure may promote nigral dopaminergic degeneration.

Vanadium oxide (VO) based low cost counter electrode in dye sensitized solar cell (DSSC) applications

Energy Technology Data Exchange (ETDEWEB)

Vijayakumar, P.; Pandian, Muthu Senthil; Ramasamy, P., E-mail: ramasamyp@ssn.edu.in [SSN Research Centre, SSN College of Engineering, Kalavakkam-603 110, Chennai, Tamilnadu (India)

2015-06-24

Vanadium oxide nanostars were synthesized by chemical method. The prepared Vanadium oxide nanostars are introduced into dye sensitized solar cell (DSSC) as counter electrode (CE) catalyst to replace the expensive platinum (Pt). The products were characterized by X-ray diffractometry (XRD), scanning electron microscopy (SEM), and Brunauer–Emmett–Teller (BET) method. The photovoltaic performance of the VO as counter electrode based DSSC was evaluated under simulated standard global AM 1.5G sunlight (100 mW/cm{sup 2}). The solar to electrical energy conversion efficiency (η) of the DSSC was found to be 0.38%.This work expands the Counter electrode catalyst, which can help to reduce the cost of DSSC and thereby encourage their fundamental research and commercial application.

Effect of the number of iron oxide nanoparticle layers on the magnetic properties of nanocomposite LbL assemblies

International Nuclear Information System (INIS)

Dincer, Ilker; Tozkoparan, Onur; German, Sergey V.; Markin, Alexey V.; Yildirim, Oguz; Khomutov, Gennady B.; Gorin, Dmitry A.; Venig, Sergey B.; Elerman, Yalcin

2012-01-01

Aqueous colloidal suspension of iron oxide nanoparticles has been synthesized. Z-potential of iron oxide nanoparticles stabilized by citric acid was −35±3 mV. Iron oxide nanoparticles have been characterized by the light scattering method and transmission electron microscopy. The polyelectrolyte/iron oxide nanoparticle thin films with different numbers of iron oxide nanoparticle layers have been prepared on the surface of silicon substrates via the layer-by-layer assembly technique. The physical properties and chemical composition of nanocomposite thin films have been studied by atomic force microscopy, magnetic force microscopy, magnetization measurements, Raman spectroscopy. Using the analysis of experimental data it was established, that the magnetic properties of nanocomposite films depended on the number of iron oxide nanoparticle layers, the size of iron oxide nanoparticle aggregates, the distance between aggregates, and the chemical composition of iron oxide nanoparticles embedded into the nanocomposite films. The magnetic permeability of nanocomposite coatings has been calculated. The magnetic permeability values depend on the number of iron oxide nanoparticle layers in nanocomposite film. - Highlights: ► The magnetic properties of nanocomposite films depended on the number of iron oxide nanoparticle layers. ► The iron oxide nanoparticle phase in nanocomposite coatings is a mixture of magnetite and maghemite phases. ► The magnetite and maghemite phases depend on a number of iron oxide nanoparticle layers because the iron oxide nanoparticles are oxidized from magnetite to maghemite.

Structural, photoconductivity, and dielectric studies of polythiophene-tin oxide nanocomposites

Energy Technology Data Exchange (ETDEWEB)

Murugavel, S., E-mail: starin85@gmail.com; Malathi, M., E-mail: mmalathi@vit.ac.in

2016-09-15

Highlights: • Synthesis of polythiophene-tin oxide nanocomposites confirmed by FTIR and EDAX. • SEM shows SnO{sub 2} nanoparticles embedded within polythiophene matrix. • Stability and isoelectric point suggest nanoparticle–matrix interaction. • High dielectric constant due to high Maxwell–Wagner interfacial polarization. - Abstract: Polythiophene-tinoxide (PT-SnO{sub 2}) nanocomposites were prepared by in situ chemical oxidative polymerization, in the presence of various concentrations of SnO{sub 2} nanoparticles. Samples were characterized by X-ray diffraction, Fourier-transform infrared spectroscopy, thermogravimetric analysis, X-ray photoelectron spectroscopy and Zeta potential measurements. Morphologies and elemental compositions were investigated by transmission electron microscopy, field-emission scanning electron microscopy and energy-dispersive X-ray spectroscopy. The photoconductivity of the nanocomposites was studied by field-dependent dark and photo conductivity measurements. Their dielectric properties were investigated using dielectric spectroscopy, in the frequency range of 1kHz–1 MHz. The results indicated that the SnO{sub 2} nanoparticles in the PT-SnO{sub 2} nanocomposite were responsible for its enhanced dielectric performance.

Color and vanadium valency in V-doped ZrO2

International Nuclear Information System (INIS)

Ren, Feng; Ishida, Shingo; Takeuchi, Nobuyuki

1993-01-01

The distribution and chemical states of vanadium in V-doped ZrO 2 were studied to clarify the origin of the color of vanadium-zirconium yellow pigment in comparison with vanadium-tin yellow pigment. ESCA data and measurements of lattice constants of V-doped ZrO 2 revealed that vanadium was dissolved mainly as V 4+ substituting for Zr in ZrO 2 lattice, and its solubility limit was 0.5 wt% as V 2 O 5 . It was found that the yellow color of vanadium-zirconium yellow was produced predominantly by the dissolved vanadium and that the contribution of vanadium oxide on ZrO 2 grains to the yellow color was about 1.30 of that of the dissolved vanadium when compared on the basis of equimolar quantity of vanadium. Most of the undissolved vanadium oxide was in an amorphous or a poorly crystallized state

Pepspectives of chlorine application in metallurgy of vanadium

International Nuclear Information System (INIS)

Korshunov, B.G.; Kutsenko, S.A.

1983-01-01

The most expedient variants of reprocessing of vanadium technical oxide (5), ferrovanadium and converter slags by chlorine technology with production of pure metal are considered. It is shown that production of vanadium by the way of electro- or metallothermal reduction of chlorides provides more plastic metal in comparison with reduction from oxides. The methods of production of VOCl 3 , VCl 4 and vanadium lowest chlorides are considered. Necessity of expansion of production of vanadium chlorine derivatives is dictated as well by their increasing application in different areas of national economy, in particular, as catalysts in organic synthesis

In situ chemical synthesis of ruthenium oxide/reduced graphene oxide nanocomposites for electrochemical capacitor applications.

Science.gov (United States)

Kim, Ji-Young; Kim, Kwang-Heon; Yoon, Seung-Beom; Kim, Hyun-Kyung; Park, Sang-Hoon; Kim, Kwang-Bum

2013-08-07

An in situ chemical synthesis approach has been developed to prepare ruthenium oxide/reduced graphene oxide (RGO) nanocomposites. It is found that as the C/O ratio increases, the number density of RuO2 nanoparticles decreases, because the chemical interaction between the Ru ions and the oxygen-containing functional groups provides anchoring sites where the nucleation of particles takes place. For electrochemical capacitor applications, the microwave-hydrothermal process was carried out to improve the conductivity of RGO in RuO2/RGO nanocomposites. The significant improvement in capacitance and high rate capability might result from the RuO2 nanoparticles used as spacers that make the interior layers of the reduced graphene oxide electrode available for electrolyte access.

Study of PVDF/Graphene oxide nanocomposites by UV-Vis analysis

International Nuclear Information System (INIS)

Pereira, Juliana V.

2013-01-01

In this work we have prepared nanocomposites made by mixing Poly (vinylidene fluoride) [PVDF] and grapheme oxide nanosheets (GO) aiming to find dosimetric properties for applications in high dose dosimetry. Graphene Oxides (GO) nanosheets were synthesized by the Hummers method, using graphite supplied by Aldrich as the starting material. Nanocomposites were produced by mixing solved PDVF in DMAc with GO dispersed in an aqueous solution by sonication. The samples were irradiated with a Co-60 source at constant dose rate (12 kGy/h), with doses ranging from 50 to 1,000 kGy. The UV-Vis and spectrophotometry have been used to monitor the appearing of C=C conjugated bonds and radio-oxidation of carbon (C=O). The PVDF/OG nanocomposites prepared with 1.88 at.% of OG presented the best dosimetric properties. In this material, UVVis spectrometry has revealed that the absorbance intensities at 250 nm can be used for high dosimetry purposes for gamma doses ranging from 100 to 750 kGy. In this range, it is possible to observe a linear relationship between Abs and Dose. (author)

Experimental and theoretical study of the reactions between neutral vanadium oxide clusters and ethane, ethylene, and acetylene.

Science.gov (United States)

Dong, Feng; Heinbuch, Scott; Xie, Yan; Rocca, Jorge J; Bernstein, Elliot R; Wang, Zhe-Chen; Deng, Ke; He, Sheng-Gui

2008-02-13

Reactions of neutral vanadium oxide clusters with small hydrocarbons, namely C2H6, C2H4, and C2H2, are investigated by experiment and density functional theory (DFT) calculations. Single photon ionization through extreme ultraviolet (EUV, 46.9 nm, 26.5 eV) and vacuum ultraviolet (VUV, 118 nm, 10.5 eV) lasers is used to detect neutral cluster distributions and reaction products. The most stable vanadium oxide clusters VO2, V2O5, V3O7, V4O10, etc. tend to associate with C2H4 generating products V(m)O(n)C2H4. Oxygen-rich clusters VO3(V2O5)(n=0,1,2...), (e.g., VO3, V3O8, and V5O13) react with C2H4 molecules to cause a cleavage of the C=C bond of C2H4 to produce (V2O5)(n)VO2CH2 clusters. For the reactions of vanadium oxide clusters (V(m)O(n)) with C2H2 molecules, V(m)O(n)C2H2 are assigned as the major products of the association reactions. Additionally, a dehydration reaction for VO3 + C2H2 to produce VO2C2 is also identified. C2H6 molecules are quite stable toward reaction with neutral vanadium oxide clusters. Density functional theory calculations are employed to investigate association reactions for V2O5 + C2H(x). The observed relative reactivity of C2 hydrocarbons toward neutral vanadium oxide clusters is well interpreted by using the DFT calculated binding energies. DFT calculations of the pathways for VO3+C2H4 and VO3+C2H2 reaction systems indicate that the reactions VO3+C2H4 --> VO2CH2 + H2CO and VO3+C2H2 --> VO2C2 + H2O are thermodynamically favorable and overall barrierless at room temperature, in good agreement with the experimental observations.

Physicochemical properties of nanocomposite: Hydroxyapatite in reduced graphene oxide.

Science.gov (United States)

Rajesh, A; Mangamma, G; Sairam, T N; Subramanian, S; Kalavathi, S; Kamruddin, M; Dash, S

2017-07-01

Graphene oxide (GO) based nanocomposites have gained considerable attention in the field of material science due to their excellent physicochemical and biological properties. Incorporation of nanomaterials into GO sheets prevents the formation of π-π stacking bond thereby giving rise to composites that show the improved properties compared to their individual counterparts. In this work, reduced graphene oxide (rGO) - hydroxyapatite (HAP) nanocomposites were synthesized by ultrasonic method. Increasing the c/a ratio of HAP in the diffraction pattern of rGO/HAP nanocomposites indicates the c-axis oriented grown HAP nanorods interacting with rGO layers. Shift in wavenumber (15cm -1 ) and increase of full width at half maximum (45cm -1 ) of G band in Raman spectra of the rGO/HAP nanocomposites are observed and attributed to the tensile strain induced due to the intercalated HAP nanorods between the rGO layers. Atomic force microscopy (AFM) and phase imaging studies revealed the intercalation of HAP nanorod with diameter 30nm and length 110-120nm in rGO sheets was clearly perceived along with improved elasticity compared to pristine HAP. 13 C-NMR results proved the synergistic interaction between both components in rGO/HAP nanocomposite. The novel properties observed and the microscopic mechanism responsible for this are a result of the structural modification in rGO layers brought about by the intercalation of HAP nanorods. Copyright © 2017. Published by Elsevier B.V.

Synthesis and evaluation of gas sensing properties of PANI based graphene oxide nanocomposites

International Nuclear Information System (INIS)

Gaikwad, Ganesh; Patil, Pritam; Patil, Devidas; Naik, Jitendra

2017-01-01

Highlights: • Developed GO, ZnO, PANI nanocomposites. • Evaluated for effect of GO addition on gas sensing performance. • Performed ammonia gas sensing at room temperature. • Obtained excellent recovery time of gas sensor. - Abstract: Polyaniline (PANI) nanofibers and Polyaniline/Graphene Oxide (PANI/GO), Polyaniline/Graphene Oxide/Zinc Oxide (PANI/GO/ZnO) nanocomposites were successfully prepared by nanoemulsion method. The synthesized nanofibers and nanocomposites were characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and Field emission scanning electron microscope (FE-SEM), has showed the evidence of interaction between PANI nanofibers, GO nanosheets and ZnO nanoparticles, respectively. PANI nanofibers and nanocomposites were used for the sensing of NH_3_, LPG, CO_2 and H_2S gases respectively at room temperature. It was observed that the PANI nanofibers and PANI/GO, PANI/GO/ZnO nanocomposites with different weight ratios of ZnO and GO had better selectivity and sensitivity towards NH_3 at room temperature. Best performance was shown by PANI/GO/ZnO nanocomposite response of 5.706 (10.3 times better response than PANI sensor) for 1000 ppm NH_3 at 80 ± 1 °C with the recovery time of 1 min 30 s only.

Synthesis and evaluation of gas sensing properties of PANI based graphene oxide nanocomposites

Energy Technology Data Exchange (ETDEWEB)

Gaikwad, Ganesh [Department of Chemical Engineering, University Institute of Chemical Technology, North Maharashtra University, Jalgaon 425001, Maharashtra (India); Patil, Pritam [SVMIT, College of Engineering, Bharuch 392001, Gujarat (India); Patil, Devidas [Bulk and Nanomaterials Research Laboratory, Rani Laxmibai Mahavidyalaya Parola, Jalgaon 425111, Maharashtra (India); Naik, Jitendra, E-mail: jbnaik@nmu.ac.in [Department of Chemical Engineering, University Institute of Chemical Technology, North Maharashtra University, Jalgaon 425001, Maharashtra (India)

2017-04-15

Highlights: • Developed GO, ZnO, PANI nanocomposites. • Evaluated for effect of GO addition on gas sensing performance. • Performed ammonia gas sensing at room temperature. • Obtained excellent recovery time of gas sensor. - Abstract: Polyaniline (PANI) nanofibers and Polyaniline/Graphene Oxide (PANI/GO), Polyaniline/Graphene Oxide/Zinc Oxide (PANI/GO/ZnO) nanocomposites were successfully prepared by nanoemulsion method. The synthesized nanofibers and nanocomposites were characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and Field emission scanning electron microscope (FE-SEM), has showed the evidence of interaction between PANI nanofibers, GO nanosheets and ZnO nanoparticles, respectively. PANI nanofibers and nanocomposites were used for the sensing of NH{sub 3,} LPG, CO{sub 2} and H{sub 2}S gases respectively at room temperature. It was observed that the PANI nanofibers and PANI/GO, PANI/GO/ZnO nanocomposites with different weight ratios of ZnO and GO had better selectivity and sensitivity towards NH{sub 3} at room temperature. Best performance was shown by PANI/GO/ZnO nanocomposite response of 5.706 (10.3 times better response than PANI sensor) for 1000 ppm NH{sub 3} at 80 ± 1 °C with the recovery time of 1 min 30 s only.

Mesoporous CuO–ZnO binary metal oxide nanocomposite for decontamination of sulfur mustard

International Nuclear Information System (INIS)

Praveen Kumar, J.; Prasad, G.K.; Ramacharyulu, P.V.R.K.; Garg, P.; Ganesan, K.

2013-01-01

Mesoporous CuO–ZnO binary metal oxide nanocomposites were studied as sorbent decontaminants against sulfur mustard, a well known chemical warfare agent. They were prepared by precipitation pyrolysis method and characterized by means of X-ray diffraction, transmission electron microscopy, nitrogen adsorption, Fourier transform infrared spectroscopy techniques. Obtained data indicated the presence of mesopores with diameter ranging from 2 to 80 nm and the materials exhibited relatively high surface area 86 m 2 g −1 when compared to the individual metal oxide nanoparticles. Reactive sites of mesoporous CuO–ZnO binary metal oxide nanocomposites were studied by infrared spectroscopy technique using pyridine as a probe molecule. These materials demonstrated superior decontamination properties against sulfur mustard when compared to single component metal oxides and decontaminated it to divinyl sulfide, chloroethyl vinyl sulfide, hemisulfur mustard, etc. - Graphical abstract: Mesoporous CuO–ZnO binary metal oxide nanocomposites were studied as sorbent decontaminants against sulfur mustard, a well known chemical warfare agent. These materials demonstrated superior decontamination properties against sulfur mustard and decontaminated it to divinyl sulfide, chloroethyl vinyl sulfide, hemisulfur mustard, etc. - Highlights: • Preparation of mesoporous CuO–ZnO binary metal oxide nanocomposite. • CuO–ZnO with better surface area was synthesized by precipitation pyrolysis. • Decontamination of HD using mesoporous CuO–ZnO binary metal oxide nanocomposite. • HD decontaminated by elimination and hydrolysis reactions

Mesoporous CuO–ZnO binary metal oxide nanocomposite for decontamination of sulfur mustard

Energy Technology Data Exchange (ETDEWEB)

Praveen Kumar, J.; Prasad, G.K., E-mail: gkprasad2001@yahoo.com; Ramacharyulu, P.V.R.K.; Garg, P.; Ganesan, K.

2013-11-01

Mesoporous CuO–ZnO binary metal oxide nanocomposites were studied as sorbent decontaminants against sulfur mustard, a well known chemical warfare agent. They were prepared by precipitation pyrolysis method and characterized by means of X-ray diffraction, transmission electron microscopy, nitrogen adsorption, Fourier transform infrared spectroscopy techniques. Obtained data indicated the presence of mesopores with diameter ranging from 2 to 80 nm and the materials exhibited relatively high surface area 86 m{sup 2} g{sup −1} when compared to the individual metal oxide nanoparticles. Reactive sites of mesoporous CuO–ZnO binary metal oxide nanocomposites were studied by infrared spectroscopy technique using pyridine as a probe molecule. These materials demonstrated superior decontamination properties against sulfur mustard when compared to single component metal oxides and decontaminated it to divinyl sulfide, chloroethyl vinyl sulfide, hemisulfur mustard, etc. - Graphical abstract: Mesoporous CuO–ZnO binary metal oxide nanocomposites were studied as sorbent decontaminants against sulfur mustard, a well known chemical warfare agent. These materials demonstrated superior decontamination properties against sulfur mustard and decontaminated it to divinyl sulfide, chloroethyl vinyl sulfide, hemisulfur mustard, etc. - Highlights: • Preparation of mesoporous CuO–ZnO binary metal oxide nanocomposite. • CuO–ZnO with better surface area was synthesized by precipitation pyrolysis. • Decontamination of HD using mesoporous CuO–ZnO binary metal oxide nanocomposite. • HD decontaminated by elimination and hydrolysis reactions.

Ultrasonic-assisted synthesis and magnetic studies of iron oxide/MCM-41 nanocomposite

International Nuclear Information System (INIS)

Ursachi, Irina; Vasile, Aurelia; Ianculescu, Adelina; Vasile, Eugeniu; Stancu, Alexandru

2011-01-01

Highlights: → A quick and facile route for the synthesis of iron oxide/MCM-41 nanocomposite. → Magnetic nanoparticles were stabilized inside the pores of mesoporous silica MCM-41. → The pore size of MCM-41 dictates the properties of iron oxide nanoparticles. → The procedure provides a narrow size distribution of magnetic nanoparticles. - Abstract: Iron oxide nanoparticles were stabilized within the pores of mesoporous silica MCM-41 amino-functionalized by a sonochemical method. Formation of iron oxide nanoparticles inside the mesoporous channels of amino-functionalized MCM-41 was realized by wet impregnation using iron nitrate, followed by calcinations at 550 deg. C in air. The effect of functionalization level on structural and magnetic properties of obtained nanocomposites was studied. The resulting materials were characterized by powder X-ray diffraction (XRD), high-resolution transmission electron microscopy and selected area electron diffraction (HRTEM and SAED), vibrating sample and superconducting quantum interface magnetometers (VSM and SQUID) and nitrogen adsorption-desorption isotherms measurements. The HRTEM images reveal that the most of the iron oxide nanoparticles were dispersed inside the mesopores of silica matrix and the pore diameter of the amino-functionalized MCM-41 matrix dictates the particle size of iron oxide nanoparticles. The obtained material possesses mesoporous structure and interesting magnetic properties. Saturation magnetization value of magnetic iron oxide nanopatricles stabilized in MCM-41 amino-functionalized by in situ sonochemical synthesis was 1.84 emu g -1 . An important finding is that obtained magnetic nanocomposite materials exhibit enhanced magnetic properties than those of iron oxide/MCM-41 nanocomposite obtained by conventional method. The described method is providing a rather short preparation time and a narrow size distribution of iron oxide nanoparticles.

Chemically stabilized reduced graphene oxide/zirconia nanocomposite: synthesis and characterization

Science.gov (United States)

Sagadevan, Suresh; Zaman Chowdhury, Zaira; Enamul Hoque, Md; Podder, Jiban

2017-11-01

In this research, chemical method was used to fabricate reduced graphene oxide/zirconia (rGO/ZrO2) nanocomposite. X-ray Diffraction analysis (XRD) was carried out to examine the crystalline structure of the nanocomposites. The nanocomposite prepared here has average crystallite size of 14 nm. The surface morphology was observed using scanning electron microscopic analysis (SEM) coupled with electron dispersion spectroscopy (EDS) to detect the chemical element over the surface of the nanocomposites. High-resolution Transmission electron microscopic analysis (HR-TEM) was carried out to determine the particle size and shape of the nanocomposites. The optical property of the prepared samples was determined using UV-visible absorption spectrum. The functional groups were identified using FTIR and Raman spectroscopic analysis. Efficient, cost effective and properly optimized synthesis process of rGO/ZrO2 nanocomposite can ensure the presence of infiltrating graphene network inside the ZrO2 matrix to enhance the electrical properties of the hybrid composites up to a greater scale. Thus the dielectric constant, dielectric loss and AC conductivity of the prepared sample was measured at various frequencies and temperatures. The analytical results obtained here confirmed the homogeneous dispersion of ZrO2 nanostructures over the surface of reduced graphene oxide nanosheets. Overall, the research demonstrated that the rGO/ZrO2 nano-hybrid structure fabricated here can be considered as a promising candidate for applications in nanoelectronics and optoelectronics.

Tungsten oxide-graphene oxide (WO3-GO) nanocomposite as an efficient photocatalyst, antibacterial and anticancer agent

Science.gov (United States)

Jeevitha, G.; Abhinayaa, R.; Mangalaraj, D.; Ponpandian, N.

2018-05-01

Functioning of ultrasonically prepared tungsten oxide-graphene oxide (WO3-GO) nanocomposite as a photocatalyst, antibacterial and anticancer system was investigated and the obtained results were compared with that of pure WO3 nanoparticles. Structural, morphological, compositional and optical properties of the prepared WO3 nanoparticles and WO3-GO nanocomposite were studied. Photocatalytic efficiency of the system on organic dyes such as methylene blue (MB, cationic) and indigo carmine (IC, anionic) was investigated. The enhanced efficiency of the WO3-GO nanocomposite system was evaluated under sunlight and compared with that of pure WO3. The degradation efficiency values for MB and IC were found to be 97.03% and 95.43% at 180 and 120 min respectively. Antibacterial activity of the WO3-GO nanocomposite under visible light was tested and improved inhibition results were observed for Escherichia coli and Bacillus subtilis after 6 h of light exposure. The photocatalytic degradation efficiency and antibacterial activity of the WO3-GO nanocomposite are attributed to the improved electron-hole pair separation rate. Investigation on anticancer activity of WO3-GO nanocomposite was tested on human lung cancer (A-549) cell line and the IC50 value was found to be 139.6 ± 4.53 μg/mL. The results obtained in this study may be used as a platform for the development of photocatalysis applications based on WO3-GO nanocomposite.

Enhanced performance of biodegradable poly(butylene succinate)/graphene oxide nanocomposites via in situ polymerization.

Science.gov (United States)

Wang, X W; Zhang, C-A; Wang, P L; Zhao, J; Zhang, W; Ji, J H; Hua, K; Zhou, J; Yang, X B; Li, X P

2012-05-08

Poly(butylene succinate) (PBS)/graphene oxide (GO) nanocomposites were facilely prepared via in situ polymerization. The properties of the nanocomposites were studied using FTIR, XRD, and (1)H NMR, and the state of dispersion of GO in the PBS matrix was examined by SEM. The crystallization and melting behavior of the PBS matrix in the presence of dispersed GO nanosheets have been studied by DSC and polarized optical microscopy. Through the mechnical testing machine and DMA, PBS/GO nanocomposites with 3% GO have shown a 43% increase in tensile strength and a 45% improvement in storage modulus. This high performance of the nanocomposites is mainly attributed to the high strength of graphene oxide combined with the strong interfacial interactions in the uniformly dispersed PBS/GO nanocomposites.

Determination of trace vanadium using its catalytic effect on the oxidation of gallic acid by bromate

International Nuclear Information System (INIS)

Yamane, Takeshi; Fukasawa, Tsutomu

1976-01-01

The oxidation of gallic acid by bromate with trace vanadium as catalyst was followed spectrophotometrically by measurements of absorbance change at 420 nm. The reaction rate was obtained graphically from the absorbance vs. time curve in the range of about 15 to 40 min. reaction time. The reaction rate was proportional to the concentration of vanadium(V) in the range 0--120 ng (under the conditions of 5.3x10 -3 M gallic acid, 6.0x10 -3 M potassium bromate, pH 3.8) and 0--30 ng (1.1x10 -2 M gallic acid, 2.7x10 -2 M potassium bromate, pH 3.8). Using this relationship, the concentration of vanadium as low as 0.1 ng/ml can be determined. The relative standard deviations at 50 ng and 20 ng of vanadium were 3.5% (n=14) and 4.0% (n=10), respectively. Iron(III) interfered seriously even when present in 20 times the amounts of vanadium. Up to 60 times, W(VI), Mo(VI) and iodide did not interfere. Many of the other ions examined were found to have no effect or slight effect even when present in 1000 times the amounts of vanadium. Other factors affecting the reaction rate were also studied. (auth.)

Preparation and characterization of vanadium oxide thin films

Energy Technology Data Exchange (ETDEWEB)

Monfort, O.; Plesch, G. [Comenius University of Bratislava, Faculty of Natural Sciences, Department of Inorganic Chemistry, 84215 Bratislava (Slovakia); Roch, T. [Comenius University of Bratislava, Faculty of Mathematics Physics and Informatics, Department of Experimental Physics, 84248 Bratislava (Slovakia)

2013-04-16

The thermotropic VO{sub 2} films have many applications, since they exhibit semiconductor-conductor switching properties at temperature around 70 grad C. Vanadium oxide thin films were prepared via sol-gel method. Spin coater was used to depose these films on Si/SiO{sub 2} and lime glass substrates. Thin films of V{sub 2}O{sub 5} can be reduced to metastable VO{sub 2} thin films at the temperature of 450 grad C under the pressure of 10{sup -2} Pa. These films are then converted to thermotropic VO{sub 2} at 700 grad C in argon under normal pressure. (authors)

Size-dependent cytotoxicity and inflammatory responses of PEGylated silica-iron oxide nanocomposite size series

Science.gov (United States)

Injumpa, Wishulada; Ritprajak, Patcharee; Insin, Numpon

2017-04-01

Iron oxides nanoparticles have been utilized in biological systems and biomedical applications for many years because they are relatively safe and stable comparing to other magnetic nanomaterials. In some applications, iron oxide nanoparticles were modified with silica in order to be more stable in biological systems and able to be functionalized with various functional groups. Moreover, poly(ethylene glycol) (PEG) was one on the most used polymer to graft onto the nanoparticles in order to increase their biocompatibility, dispersibility and stability in aqueous solutions. Therefore, the nanocomposites comprising iron oxide nanoparticles, silica, and PEG could become multifunctional carriers combining superparamagnetic character, multi-functionality and high stability in biological environments. Herein, we reported the preparation of the nanocomposites and effects of their sizes on cytotoxicity and inflammatory responses. The PEGylated silica-iron oxide nanocomposites were prepared by coating of poly(poly(ethylene glycol) monomethyl ether methacrylate) (PPEGMA) on magnetic nanoparticle-silica nanocomposites via Atom Transfer Radical Polymerization (ATRP). The iron oxide nanoparticles were synthesized using a thermal decomposition method. The silica shells were then coated on iron oxides nanoparticles using reverse microemulsion and sol-gel methods. The size series of the nanocomposites with the diameter of 24.86±4.38, 45.24±5.00, 98.10±8.88 and 202.22±6.70 nm as measured using TEM were obtained. Thermogravimetric analysis (TGA) was used for the determination of % weight of PPEGMA on the nanocomposites showing the weight loss of ranging from 65% for smallest particles to 30% for largest particles. The various sizes (20, 40, 100, 200 nm) and concentrations (10, 100, 1000 μg/mL) of the nanocomposites were tested for their cytotoxicity in fibroblast and macrophage cell lines using MTT assay. The different sizes did not affect cell viability of fibroblast, albeit

Graphite furnace atomic absorption spectrometric determination of vanadium after cloud point extraction in the presence of graphene oxide

Science.gov (United States)

López-García, Ignacio; Marín-Hernández, Juan José; Hernández-Córdoba, Manuel

2018-05-01

Vanadium (V) and vanadium (IV) in the presence of a small concentration of graphene oxide (0.05 mg mL-1) are quantitatively transferred to the coacervate obtained with Triton X-114 in a cloud point microextraction process. The surfactant-rich phase is directly injected into the graphite atomizer of an atomic absorption spectrometer. Using a 10-mL aliquot sample and 150 μL of a 15% Triton X-114 solution, the enrichment factor for the analyte is 103, which results in a detection limit of 0.02 μg L-1 vanadium. The separation of V(V) and V(IV) using an ion-exchanger allows speciation of the element at low concentrations. Data for seven reference water samples with certified vanadium contents confirm the reliability of the procedure. Several beer samples are also analyzed, those supplied as canned drinks showing low levels of tetravalent vanadium.

Determination of vanadium

International Nuclear Information System (INIS)

Stepin, V.V.; Kurbatova, V.I.; Fedorova, N.D.

1980-01-01

Titrimetric and potentiometric methods of vanadium determination in ferrovanadium are developed. The essence of the titrimetric method using phenylanthranilic acid as indicator is in the following. Ferrovanadium weighed amount is dissolved in H 2 SO 4 , vanadium is oxidated by potassium permanganate to V(5) and is titrated by a solution of double salt of sulfuric Fe(2) and ammonium in the presence of indicator. Potentiometric titration is carried out using the same indicator [ru

Graphite-graphite oxide composite electrode for vanadium redox flow battery

International Nuclear Information System (INIS)

Li Wenyue; Liu Jianguo; Yan Chuanwei

2011-01-01

Highlights: → A new composite electrode is designed for vanadium redox flow battery (VRB). → The graphite oxide (GO) is used as electrode reactions catalyst. → The excellent electrode activity is attributed to the oxygen-containing groups attached on the GO surface. → A catalytic mechanism of the GO towards the redox reactions is presumed. - Abstract: A graphite/graphite oxide (GO) composite electrode for vanadium redox battery (VRB) was prepared successfully in this paper. The materials were characterized with X-ray diffraction, X-ray photoelectron spectroscopy and scanning electron microscopy. The specific surface area was measured by the Brunauer-Emmett-Teller method. The redox reactions of [VO 2 ] + /[VO] 2+ and V 3+ /V 2+ were studied with cyclic voltammetry and electrochemical impedance spectroscopy. The results indicated that the electrochemical performances of the electrode were improved greatly when 3 wt% GO was added into graphite electrode. The redox peak currents of [VO 2 ] + /[VO] 2+ and V 3+ /V 2+ couples on the composite electrode were increased nearly twice as large as that on the graphite electrode, and the charge transfer resistances of the redox pairs on the composite electrode are also reduced. The enhanced electrochemical activity could be ascribed to the presence of plentiful oxygen functional groups on the basal planes and sheet edges of the GO and large specific surface areas introduced by the GO.

Pore-Size-Tuned Graphene Oxide Frameworks as Ion-Selective and Protective Layers on Hydrocarbon Membranes for Vanadium Redox-Flow Batteries.

Science.gov (United States)

Kim, Soohyun; Choi, Junghoon; Choi, Chanyong; Heo, Jiyun; Kim, Dae Woo; Lee, Jang Yong; Hong, Young Taik; Jung, Hee-Tae; Kim, Hee-Tak

2018-05-07

The laminated structure of graphene oxide (GO) membranes provides exceptional ion-separation properties due to the regular interlayer spacing ( d) between laminate layers. However, a larger effective pore size of the laminate immersed in water (∼11.1 Å) than the hydrated diameter of vanadium ions (>6.0 Å) prevents its use in vanadium redox-flow batteries (VRFB). In this work, we report an ion-selective graphene oxide framework (GOF) with a d tuned by cross-linking the GO nanosheets. Its effective pore size (∼5.9 Å) excludes vanadium ions by size but allows proton conduction. The GOF membrane is employed as a protective layer to address the poor chemical stability of sulfonated poly(arylene ether sulfone) (SPAES) membranes against VO 2 + in VRFB. By effectively blocking vanadium ions, the GOF/SPAES membrane exhibits vanadium-ion permeability 4.2 times lower and a durability 5 times longer than that of the pristine SPAES membrane. Moreover, the VRFB with the GOF/SPAES membrane achieves an energy efficiency of 89% at 80 mA cm -2 and a capacity retention of 88% even after 400 cycles, far exceeding results for Nafion 115 and demonstrating its practical applicability for VRFB.

Graphene Oxide-TiO2 Nanocomposite Films for Electron Transport Applications

Science.gov (United States)

Saleem, Abida; Ullah, Naveed; Khursheed, Kamran; Iqbal, Tahir; Shah, Saqlain A.; Asjad, Muhammad; Sarwar, Nazim; Saleem, Murtaza; Arshad, Muhammad

2018-03-01

Graphene oxide-titanium dioxide (GO-TiO2) nanocomposite thin films were prepared for application as the window layer of perovskite solar cells. Graphene oxide (GO) was prepared by a modified Hummer's method, and titanium dioxide (TiO2) nanoparticles were synthesized by hydrothermal solution method. Thin films of GO-TiO2 nanocomposite were prepared with different wt.% of GO by spin coating on indium tin oxide (ITO) substrate followed by annealing at 150°C. X-ray diffraction analysis revealed rutile phase of TiO2 nanostructures. The bandgap of the pure TiO2 thin film was found to be 3.5 eV, reducing to 2.9 eV for the GO-TiO2 nanocomposites with a red-shift towards higher wavelength. Furthermore, thermal postannealing at 400°C improved the transparency in the visible region and decreased the sheet resistance. Morphological and elemental analysis was performed by scanning electron microscopy and energy-dispersive x-ray spectroscopy, respectively. The current-voltage characteristic of the GO-TiO2 nanocomposites indicated Ohmic contact with the ITO substrate. The chemical composition of the as-synthesized GO-TiO2 nanocomposites was investigated by x-ray photoelectron spectroscopy (XPS). The results presented herein demonstrate a new, low-temperature solution-processing approach to obtain rGO-TiO2 composite material for use as the electron transport layer of perovskite solar cells.

Crystallization and unusual rheological behavior in poly(ethylene oxide)–clay nanocomposites

KAUST Repository

Kelarakis, Antonios; Giannelis, Emmanuel P.

2011-01-01

We report a systematic study of the crystallization and rheological behavior of poly(ethylene oxide) (PEO)-clay nanocomposites. To that end a series of nanocomposites based on PEOs of different molecular weight (103 < MW < 105 g/mol) and clay

Size-dependent cytotoxicity and inflammatory responses of PEGylated silica-iron oxide nanocomposite size series

Energy Technology Data Exchange (ETDEWEB)

Injumpa, Wishulada [Department of Chemistry, Faculty of Science, Chulalongkorn University, Bangkok 10330 (Thailand); Ritprajak, Patcharee [Department of Microbiology, and RU in Oral Microbiology and Immunology, Faculty of Dentistry, Chulalongkorn University, Bangkok 10330 (Thailand); Insin, Numpon, E-mail: Numpon.I@chula.ac.th [Department of Chemistry, Faculty of Science, Chulalongkorn University, Bangkok 10330 (Thailand)

2017-04-01

Iron oxides nanoparticles have been utilized in biological systems and biomedical applications for many years because they are relatively safe and stable comparing to other magnetic nanomaterials. In some applications, iron oxide nanoparticles were modified with silica in order to be more stable in biological systems and able to be functionalized with various functional groups. Moreover, poly(ethylene glycol) (PEG) was one on the most used polymer to graft onto the nanoparticles in order to increase their biocompatibility, dispersibility and stability in aqueous solutions. Therefore, the nanocomposites comprising iron oxide nanoparticles, silica, and PEG could become multifunctional carriers combining superparamagnetic character, multi-functionality and high stability in biological environments. Herein, we reported the preparation of the nanocomposites and effects of their sizes on cytotoxicity and inflammatory responses. The PEGylated silica-iron oxide nanocomposites were prepared by coating of poly(poly(ethylene glycol) monomethyl ether methacrylate) (PPEGMA) on magnetic nanoparticle-silica nanocomposites via Atom Transfer Radical Polymerization (ATRP). The iron oxide nanoparticles were synthesized using a thermal decomposition method. The silica shells were then coated on iron oxides nanoparticles using reverse microemulsion and sol-gel methods. The size series of the nanocomposites with the diameter of 24.86±4.38, 45.24±5.00, 98.10±8.88 and 202.22±6.70 nm as measured using TEM were obtained. Thermogravimetric analysis (TGA) was used for the determination of % weight of PPEGMA on the nanocomposites showing the weight loss of ranging from 65% for smallest particles to 30% for largest particles. The various sizes (20, 40, 100, 200 nm) and concentrations (10, 100, 1000 μg/mL) of the nanocomposites were tested for their cytotoxicity in fibroblast and macrophage cell lines using MTT assay. The different sizes did not affect cell viability of fibroblast, albeit

MnO2-Graphene Oxide-PEDOT:PSS Nanocomposite for an Electrochemical Supercapacitor

Science.gov (United States)

Patil, Dipali S.; Pawar, Sachin A.; Shin, Jae Cheol; Kim, Hyo Jin

2018-04-01

A ternary nanocomposite with poly (3,4 ethylene dioxythiophene:poly(styrene sulfonate) (PEDOT:PSS)-MnO2 nanowires-graphene oxide (PMn-GO) was synthesized by using simple chemical route. The formation of the nanocomposite was analyzed by using X-ray diffraction and X-ray photoelectron spectroscopy. Field-emission scanning microscopy (FESEM) revealed the formation of MnO2 nanowires and graphene oxide nanosheets. The highest specific capacitance (areal capacitance) of 841 Fg -1 (177 mFcm -2) at 10 mVs -1 and energy density of 0.593 kWhkg -1 at 0.5 mA were observed for PMn-GO, indicating a constructive synergistic effect of PEDOT:PSS, MnO2 nanowires and graphene oxide. The achieved promising electrochemical characteristics showed that this ternary nanocomposite is a good alternative as an electrode material for supercapacitor.

Oxidative dehydration of glycerol to acrylic acid over vanadium-impregnated zeolite beta

Energy Technology Data Exchange (ETDEWEB)

Pestana, Carolina F.M.; Guerra, Antonio C.O.; Turci, Cassia C. [Universidade Federal do Rio de Janeiro, RJ (Brazil). Inst. de Quimica; Ferreira, Glaucio B. [Universidade Federal Fluminense, Niteroi, RJ (Brazil). Inst. de Quimica; Mota, Claudio J.A., E-mail: cmota@iq.ufrj.br [INCT Energia e Ambiente, Universidade Federal do Rio de Janeiro, RJ (Brazil)

2013-01-15

The oxidative dehydration of glycerol to acrylic acid was studied over vanadium-impregnated zeolite Beta. Catalysts were prepared by wet impregnation of ammonium metavanadate over ammonium-exchanged zeolite Beta, followed by air calcination at 823 K. Impregnation reduced the specific surface area, but did not significantly affected the acidity (Bronsted and Lewis) of the zeolites. The catalytic evaluation was carried out in a fixed bed flow reactor using air as the carrier and injecting glycerol by means of a syringe pump. Acrolein was the main product, with acetaldehyde and hydroxy-acetone (acetol) being also formed. Acrylic acid was formed with approximately 25% selectivity at 548 K over the impregnated zeolites. The result can be explained by XPS (X-ray photoelectron spectroscopy) measurements, which indicated a good dispersion of the vanadium inside the pores. (author)

Oxidative dehydration of glycerol to acrylic acid over vanadium-impregnated zeolite beta

International Nuclear Information System (INIS)

Pestana, Carolina F.M.; Guerra, Antonio C.O.; Turci, Cassia C.

2013-01-01

The oxidative dehydration of glycerol to acrylic acid was studied over vanadium-impregnated zeolite Beta. Catalysts were prepared by wet impregnation of ammonium metavanadate over ammonium-exchanged zeolite Beta, followed by air calcination at 823 K. Impregnation reduced the specific surface area, but did not significantly affected the acidity (Bronsted and Lewis) of the zeolites. The catalytic evaluation was carried out in a fixed bed flow reactor using air as the carrier and injecting glycerol by means of a syringe pump. Acrolein was the main product, with acetaldehyde and hydroxy-acetone (acetol) being also formed. Acrylic acid was formed with approximately 25% selectivity at 548 K over the impregnated zeolites. The result can be explained by XPS (X-ray photoelectron spectroscopy) measurements, which indicated a good dispersion of the vanadium inside the pores. (author)

Kinetic investigation of vanadium (V)/(IV) redox couple on electrochemically oxidized graphite electrodes

International Nuclear Information System (INIS)

Wang, Wenjun; Wei, Zengfu; Su, Wei; Fan, Xinzhuang; Liu, Jianguo; Yan, Chuanwei; Zeng, Chaoliu

2016-01-01

Highlights: • The VO_2"+/VO"2"+ redox reaction of the electrode could be facilitated to some extent with the increasing anodic corrosion. • A real reaction kinetic equation for the oxidation of VO"2"+ on the electrochemically oxidized electrode has been firstly obtained. • The establishment of the kinetic equation is conducive to predict polarization behaviors of the electrodes in engineering application. - Abstract: The morphology, surface composition, wettability and the kinetic parameters of the electrochemically oxidized graphite electrodes obtained under different anodic polarization conditions have been examined by scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), contact angle measurements, steady-state polarization and cyclic voltammetry (CV) tests, with an attempt to investigate the inherent correlation between the physicochemical properties and the kinetic characteristics for carbon electrodes used in an all-vanadium redox flow battery (VRFB). When the anodic polarization potential raises up to 1.8 V vs. SCE, the anodic corrosion of the graphite might happen and a large number of oxygen-containing functional groups generate. The VO_2"+/VO"2"+ redox reaction can be facilitated and the reaction reversibility tends to become better with the increasing anodic potential, possibly owing to the increased surface oxides and the resulting improved wettability of the electrode. Based on this, a real reaction kinetic equation for the oxidation of VO"2"+ has been obtained on the electrode polarized at 1.8 V vs. SCE and it can be also well used to predict the polarization behavior of the oxidized electrode in vanadium (IV) acidic solutions.

Roasting and leaching behaviors of vanadium and chromium in calcification roasting-acid leaching of high-chromium vanadium slag

Science.gov (United States)

Wen, Jing; Jiang, Tao; Zhou, Mi; Gao, Hui-yang; Liu, Jia-yi; Xue, Xiang-xin

2018-05-01

Calcification roasting-acid leaching of high-chromium vanadium slag (HCVS) was conducted to elucidate the roasting and leaching behaviors of vanadium and chromium. The effects of the purity of CaO, molar ratio between CaO and V2O5 ( n(CaO)/ n(V2O5)), roasting temperature, holding time, and the heating rate used in the oxidation-calcification processes were investigated. The roasting process and mechanism were analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM), and thermogravimetry-differential scanning calorimetry (TG-DSC). The results show that most of vanadium reacted with CaO to generate calcium vanadates and transferred into the leaching liquid, whereas almost all of the chromium remained in the leaching residue in the form of (Fe0.6Cr0.4)2O3. Variation trends of the vanadium and chromium leaching ratios were always opposite because of the competitive reactions of oxidation and calcification between vanadium and chromium with CaO. Moreover, CaO was more likely to combine with vanadium, as further confirmed by thermodynamic analysis. When the HCVS with CaO added in an n(CaO)/ n(V2O5) ratio of 0.5 was roasted in an air atmosphere at a heating rate of 10°C/min from room temperature to 950°C and maintained at this temperature for 60 min, the leaching ratios of vanadium and chromium reached 91.14% and 0.49%, respectively; thus, efficient extraction of vanadium from HCVS was achieved and the leaching residue could be used as a new raw material for the extraction of chromium. Furthermore, the oxidation and calcification reactions of the spinel phases occurred at 592 and 630°C for n(CaO)/ n(V2O5) ratios of 0.5 and 5, respectively.

Oxygen Barrier Properties and Melt Crystallization Behavior of Poly(ethylene terephthalate/Graphene Oxide Nanocomposites

Directory of Open Access Journals (Sweden)

Anna Szymczyk

2015-01-01

Full Text Available Poly(ethylene terephthalate nanocomposites with low loading (0.1–0.5 wt% of graphene oxide (GO have been prepared by using in situ polymerization method. TEM study of nanocomposites morphology has shown uniform distribution of highly exfoliated graphene oxide nanoplatelets in PET matrix. Investigations of oxygen permeability of amorphous films of nanocomposites showed that the nanocomposites had better oxygen barrier properties than the neat PET. The improvement of oxygen permeability for PET nanocomposite films over the neat PET is approximately factors of 2–3.3. DSC study on the nonisothermal crystallization behaviors proves that GO acts as a nucleating agent to accelerate the crystallization of PET matrix. The evolution of the lamellar nanostructure of nanocomposite and neat PET was monitored by SAXS during nonisothermal crystallization from the melt. It was found that unfilled PET and nanocomposite with the highest concentration of GO (0.5 wt% showed almost similar values of the long period (L=11.4 nm for neat PET and L=11.5 nm for PET/0.5GO.

Kinetics and mechanism of oxidation of acetanilide by quinquevalent vanadium in acid medium

International Nuclear Information System (INIS)

Gupta, R.

1990-01-01

The kinetics of the oxidation of acetanilide with vanadium(V) in sulphuric acid medium at constant ionic strength has been studied. The reaction is first order with oxidant. The order of reaction in acetanilide varies from one to zero. The reaction follows an acid catalyzed independent path, exhibiting square dependence in H + . A Bunnett plot indicates that the water acts as a nucleophile. The thermodynamic parameters have been computed. A probable reaction mechanism and rate law consistent with these data are given. (Author)

Green synthesis, characterization, and anticancer activity of hyaluronan/zinc oxide nanocomposites

Directory of Open Access Journals (Sweden)

Namvar F

2016-07-01

Full Text Available Farideh Namvar,1,2 Susan Azizi,3 Heshu Sulaiman Rahman,4–6 Rosfarizan Mohamad,1,3 Abdullah Rasedee,4 Mozhgan Soltani,2 Raha Abdul Rahim71Institute of Tropical Forestry and Forest Products (INTROP, Universiti Putra Malaysia, UPM Serdang, Selangor, Malaysia; 2Research Center for Animal Development Applied Biology, Mashhad Branch, Islamic Azad University, Mashhad, Iran; 3Department of Bioprocess Technology, Faculty of Biotechnology and Biomolecular Sciences, 4Department of Veterinary Laboratory Diagnosis, Faculty of Veterinary Medicine, Universiti Putra Malaysia, UPM Serdang, Selangor, Malaysia; 5Department of Clinic and Internal Medicine, College of Veterinary Medicine, University of Sulaimani, 6Department of Laboratory Medical Sciences, Komar University of Science and Technology, Sulaimani City, Kurdistan Region, Northern Iraq; 7Department of Cell and Molecular Biology, Faculty of Biotechnology and Biomolecular Sciences, Universiti Putra Malaysia, UPM Serdang, Selangor, Malaysia Abstract: The study describes an in situ green biosynthesis of zinc oxide nanocomposite using the seaweed Sargassum muticum water extract and hyaluronan biopolymer. The morphology and optical properties of the hyaluronan/zinc oxide (HA/ZnO nanocomposite were determined by Fourier transform infrared spectroscopy, X-ray diffraction, field emission scanning electron microscopy, transmission electron microscopy, and ultraviolet–vis analysis. Electron microscopy and X-ray diffraction analysis showed that the zinc oxide nanoparticles were polydispersed with a mean size of 10.2±1.5 nm. The nanoparticles were mostly hexagonal in crystalline form. The HA/ZnO nanocomposite showed the absorption properties in the ultraviolet zone that is ascribed to the band gap of zinc oxide nanocomposite. In the cytotoxicity study, cancer cells, pancreatic adenocarcinoma (PANC-1, ovarian adenocarcinoma (CaOV-3, colonic adenocarcinoma (COLO205, and acute promyelocytic leukemia (HL-60 cells

The structural studies of vanadium substituted lithium-bismuth-boro-tellurite glass

Science.gov (United States)

Madhu, A.; Eraiah, B.

2018-05-01

The structural studies of vanadium substituted lithium-bismuth-boro-tellurite glass is successfully prepared and certain analysis like XRD,FTIR,DTA/TGA with density, molar volume are done. The amorphous phase has been identified based on X-ray diffraction analysis. The vanadium oxide plays the role as a glass-modifier and influences on BO3 ↔ BO4 conversion. The observed nonlinear variation in Tg with vanadium oxide increase, it reflects structural changes. The nonlinear variation of density and molar volume can be attributed to vanadium oxide incorporation have increased the number of Non-bridging oxygen (NBO'S).

Hysteresis Phenomena in Sulfur Dioxide Oxidation over Supported Vanadium Catalysts

DEFF Research Database (Denmark)

Masters, Stephen G.; Eriksen, Kim Michael; Fehrmann, Rasmus

1997-01-01

Catalyst deactivation and hysteresis behavior in industrial SO2-oxidation catalysts have been studied in the temperature region 350-480 C by combined in situ EPR spectroscopy and catalytic activity measurements. The feed gas composition simulated sulfuric acid synthesis gas and wet/dry de......NOx'ed flue gas. The vanadium (IV) compound K4(VO)3(SO4)5 precipitated during all the investigated conditions hence causing catalyst deactivation. Hysteresis behavior of both the catalytic activity and the V(IV) content was observed during reheating....

Graphene oxide-silica nanohybrids as fillers for PA6 based nanocomposites

International Nuclear Information System (INIS)

Maio, A.; Fucarino, R.; Khatibi, R.; Botta, L.; Scaffaro, R.; Rosselli, S.; Bruno, M.

2014-01-01

Graphene oxide (GO) was prepared by oxidation of graphite flakes by a mixture of H 2 SO 4 /H 3 PO 4 and KMnO 4 based on Marcano's method. Two different masterbatches containing GO (33.3%) and polyamide-6 (PA6) (66.7%) were prepared both via solvent casting in formic acid and by melt mixing in a mini-extruder (Haake). The two masterbatches were then used to prepare PA6-based nanocomposites with a content of 2% in GO. For comparison, a nanocomposite by direct mixing of PA6 and GO (2%) and PA6/graphite nanocomposites were prepared, too. The oxidation of graphite into GO was assessed by X-ray diffraction (XRD), Micro-Raman spectroscopy, scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) analyses. All these techniques demonstrated the effectiveness of the graphite modification, since the results put into evidence that, after the acid treatment, interlayer distance, oxygen content and defects increased. SEM micrographs carried out on the nanocomposites, showed GO layers totally surrounded by polyamide-6, this feature is likely due to the strong interaction between the hydrophilic moieties located both on GO and on PA6. On the contrary, no interactions were observed when graphite was used as filler. Mechanical characterization, carried out by tensile and dynamic-mechanical tests, marked an improvement of the mechanical properties observed. Photoluminescence and EPR measurements were carried out onto nanoparticles and nanocomposites to study the nature of the interactions and to assess the possibility to use this class of materials as semiconductors or optical sensors

Influence of phosphorus and potassium impurities on the properties of vanadium oxide supported on TiO2

NARCIS (Netherlands)

van Hengstum, A.J.; Pranger, J.; van Ommen, J.G.; Gellings, P.J.

1984-01-01

The catalytic properties of vanadium oxide catalysts supported on TiO2 from Tioxide were strongly affected by phosphorus and potassium, present as impurities in the TiO2 support. The effects observed were stronaly dependent on the type of hydrocarbon oxidised. In the oxidation of toluene to benzoic

Nanocomposites of cellulose/iron oxide: influence of synthesis conditions on their morphological behavior and thermal stability

International Nuclear Information System (INIS)

Ma Mingguo; Zhu Jiefang; Li Shuming; Jia Ning; Sun Runcang

2012-01-01

Nanocomposites of cellulose/iron oxide have been successfully prepared by hydrothermal method using cellulose solution and Fe(NO 3 ) 3 ·9H 2 O at 180 °C. The cellulose solution was obtained by the dissolution of microcrystalline cellulose in NaOH/urea aqueous solution, which is a good system to dissolve cellulose and favors the synthesis of iron oxide without needing any template or other reagents. The phases, microstructure, and morphologies of nanocomposites were characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), and energy-dispersive X-ray spectra (EDS). The effects of the heating time, heating temperature, cellulose concentration, and ferric nitrate concentration on the morphological behavior of products were investigated. The experimental results indicated that the cellulose concentration played an important role in both the phase and shape of iron oxide in nanocomposites. Moreover, the nanocomposites synthesized by using different cellulose concentrations displayed different thermal stabilities. - Highlights: ► Nanocomposites of cellulose/iron oxide have been prepared by hydrothermal method. ► The cellulose concentration played an important role in the phase of iron oxide. ► The cellulose concentration played an important role in the shape of iron oxide. ► The samples displayed different thermal stabilities.

Study of vanadium based mesoporous silicas for oxidative dehydrogenation of propane and n-butane

Czech Academy of Sciences Publication Activity Database

Bulánek, R.; Kalužová, A.; Setnička, M.; Zukal, Arnošt; Čičmanec, P.; Mayerová, Jana

2012-01-01

Roč. 179, č. 1 (2012), s. 149-158 ISSN 0920-5861 R&D Projects: GA ČR GAP106/10/0196 Institutional research plan: CEZ:AV0Z40400503 Keywords : vanadium * oxidative dehydrogenation * mesoporous silicas Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 2.980, year: 2012

Structure-property relationships in NO_x sensor materials composed of arrays of vanadium oxide nanoclusters

Energy Technology Data Exchange (ETDEWEB)

Putrevu, Naga Ravikanth; Darling, Seth B.; Segre, Carlo U.; Ganegoda, Hasitha; Khan, M. Ishaque

2017-10-04

The mixed-valent vanadium oxide based three-dimensional framework structure species [Cd₃(H₂O)₁₂V₁₆^IVV₂^VO₃₆(OH)₆(AO₄)]∙24H₂O, (A=V,S) (Cd₃(VO)_o) represents a rare example of an interesting sensor material which exhibits NO_x {NO+NO₂} semiconducting gas sensor properties under ambient conditions. The electrical resistance of the sensor material Cd₃(VO)_o decreases in air. Combined characterization studies revealed that the building block, {V₁₈O₄₂(AO₄)} cluster, of 3-D framework undergoes oxidation and remains intact for at least 2 months. The decrease in resistance is attributable to the reactivity of molecular oxygen towards vanadium which results in an increase in the oxidation state as well as the coordination number of vanadium center and decrease in band gap of Cd₃(VO)_o. Based on these results we propose that the changes in semiconducting properties of Cd₃(VO)_o under ambient conditions are due to the greater overlap between the O 2p and V 3d orbitals occurring during the oxidation.

GRAPHENE BASED METAL AND METAL OXIDE NANOCOMPOSITES: SYNTHESIS, PROPERTIES AND THEIR APPLICATIONS

KAUST Repository

Khan, Mujeeb; Tahir, Muhammad Nawaz; Adil, Syed F; Khan, Hadayat Ullah; Siddiqui, Rafiq H; Al-Warthan, Abdulrahman Abdullah; Tremel, Wolfgang

2015-01-01

Graphene, an atomically thin two-dimensional carbonaceous material, has attracted tremendous attention in the scientific community, due to its exceptional electronic, electrical, and mechanical properties. Indeed, with the recent explosion of methods for a large-scale synthesis of graphene, the number of publications related to graphene and other graphene based materials have increased exponentially. Particularly the easy preparation of graphene like materials, such as, highly reduced graphene oxide (HRG) via reduction of graphite oxide (GO), offers a wide range of possibilities for the preparation of graphene based inorganic nanocomposites by the incorporation of various functional nanomaterials for a variety of applications. In this review, we discuss the current development of graphene based metal and metal oxide nanocomposites, with a detailed account of their synthesis and properties. Specifically, much attention has been given to their wide range of applications in various fields, including, electronics, electrochemical and electrical fields. Overall, by the inclusion of various references, this review covers in detail aspects of the graphene-based inorganic nanocomposites.

GRAPHENE BASED METAL AND METAL OXIDE NANOCOMPOSITES: SYNTHESIS, PROPERTIES AND THEIR APPLICATIONS

KAUST Repository

Khan, Mujeeb

2015-06-11

Graphene, an atomically thin two-dimensional carbonaceous material, has attracted tremendous attention in the scientific community, due to its exceptional electronic, electrical, and mechanical properties. Indeed, with the recent explosion of methods for a large-scale synthesis of graphene, the number of publications related to graphene and other graphene based materials have increased exponentially. Particularly the easy preparation of graphene like materials, such as, highly reduced graphene oxide (HRG) via reduction of graphite oxide (GO), offers a wide range of possibilities for the preparation of graphene based inorganic nanocomposites by the incorporation of various functional nanomaterials for a variety of applications. In this review, we discuss the current development of graphene based metal and metal oxide nanocomposites, with a detailed account of their synthesis and properties. Specifically, much attention has been given to their wide range of applications in various fields, including, electronics, electrochemical and electrical fields. Overall, by the inclusion of various references, this review covers in detail aspects of the graphene-based inorganic nanocomposites.

Physicochemical properties of vanadium impregnated Al-PILCs: Effect of vanadium source

Energy Technology Data Exchange (ETDEWEB)

Balci, Suna, E-mail: sunabalci@gazi.edu.tr; Tecimer, Aylin

2015-03-01

Graphical abstract: - Highlights: • Vanadium was incorporated into Al-PILC using NaVO{sub 3} or VOSO{sub 4}·3H{sub 2}O precursors by wet impregnation, washing after wet impregnation and impregnation from solution methods. • The layered structure of the supports was retained after the vanadium incorporation. • Incorporation took place both by settling and ion exchange mechanism with the treatment VOSO{sub 4}·3H{sub 2}O precursor while settling was dominant in the use of NaVO{sub 3} precursor. • Treatment with VOSO{sub 4}·3H{sub 2}O which was acidic in solution resulted in more structural deformation. • V{sub 2}O{sub 5} and VO{sub 2} were found as the major oxide forms on the impregnated samples. Loading of vanadyl sulfate hydrate (VOSO{sub 4}·H{sub 2}O) resulted in higher V/Si ratio. Most of the vanadium was bonded in +5 oxide form. • Changes in the FTIR signals after vanadium incorporation caused by Brønsted and Lewis sites, silanol, water and vanadium vibrations were occured. • Dehydroxylation of the structure took place around 300 °C. Samples obtained by impregnation and washing after wet impregnation methods resulted in similar mass losses and the wet impregnated sample showed the highest mass loss among the impregnated samples. - Summary: Clay from the Middle Anatolian previously pillared by Al{sub 13}-Keggin ions and then calcined at 300 °C (Al-PILC) was impregnated with aqueous solutions of vanadium precursors by impregnation from solution (I), wet impregnation (WI) and washing after wet impregnation (WWI) methods. The crystal and textural properties were evaluated by X-ray powder diffraction (XRD), nitrogen sorption and transmission electron microscopy (TEM) images. Vanadium incorporation into the Al-PILC resulted decreases in the basal spacing from 1.75 nm to 1.35 nm with the preserved typical layered structure. The use of sodium metavanadate (NaVO{sub 3}) as the source and the impregnation from solution as the incorporation method

Effects of Vanadium Ions in Different Oxidation States on Myosin ATPase Extracted from the Solitary Ascidian, Halocynthia roretzi (Drasche) : Biochemistry

OpenAIRE

HITOSHI, MICHIBATA; YUTAKA, ZENKO; KENJI, YAMADA; MASATO, HASEGAWA; TATSURO, TERADA; TAKAHARU, NUMAKUANI; Biological Institute, Faculty of Science, Toyama University; Biological Institute, Faculty of Science, Toyama University; Biological Institute, Faculty of Science, Toyama University; Biological Institute, Faculty of Science, Toyama University; Department of Chemistry, Toyama College of Technology; Marine Biological Station, Tohoku University

1989-01-01

Some ascidians are known to accumulate vanadium ion within their tissues by 10^6-fold as that in sea water and store the metal ion in its reduced tetravalent and/or trivalent states. It is also well known that phosphoenzymes are inhibited by pentavalent vanadium ion over a range of 10nM to 1mM. In the present experiment we have therefore examined the effects of vanadium ions in different oxidation states on the activity of myosin ATPase extracted from the mantle of the ascidian, Halocynthia r...

Characterization and Electrical Response to Humidity of Sintered Polymeric Electrospun Fibers of Vanadium Oxide-({TiO}_{{2}} /{WO}_{{3}} )

Science.gov (United States)

Araújo, E. S.; Libardi, J.; Faia, P. M.; de Oliveira, H. P.

2018-02-01

Metal oxide composites have attracted much consideration due to their promising applications in humidity sensors in response to the physical and chemical property modifications of the resulting materials. This work focused on the preparation, microstructural characterization and analysis of humidity-dependent electrical properties of undoped and vanadium oxide (V2O5)-doped titanium oxide/tungsten oxide (TiO2/WO3) sintered ceramic films obtained by electrospinning. The electrical properties were investigated by impedance spectroscopy (400 Hz-40 MHz) as a function of relative humidity (RH). The results revealed a typical transition in the transport mechanisms controlled by the appropriated doping level of V2O5, which introduces important advantages to RH detection due to the atomic substitution of titanium by vanadium atoms in highly doped structures. These aspects are directly related to the microstructure modification and structure fabrication procedure.

Highly Active PdNi/RGO/Polyoxometalate Nanocomposite Electrocatalyst for Alcohol Oxidation.

Science.gov (United States)

Hu, Jing; Wu, Xiaofeng; Zhang, Qingfan; Gao, Mingyan; Qiu, Haifang; Huang, Keke; Feng, Shouhua; Wang, Tingting; Yang, Ying; Liu, Zhelin; Zhao, Bo

2018-02-27

A PdNi/RGO/polyoxometalate nanocomposite has been successfully synthesized by a simple wet-chemical method. Characterizations such as transmission electron microscopy, energy dispersive X-ray spectroscopy, X-ray diffraction analysis, and X-ray photoelectron spectroscopy are employed to verify the morphology, structure, and elemental composition of the as-prepared nanocomposite. Inspired by the fast-developing fuel cells, the electrochemical catalytic performance of the nanocomposite toward methanol and ethanol oxidation in alkaline media is further tested. Notably, the nanocomposite exhibits excellent catalytic activity and long-term stability toward alcohol electrooxidation compared with the PdNi/RGO and commercial Pd/C catalyst. Furthermore, the electrochemical results reveal that the prepared nanocomposite is attractive as a promising electrocatalyst for direct alcohol fuel cells, in which the phosphotungstic acid plays a crucial role in enhancing the electrocatalytic activities of the catalyst.

Graphene oxide-silica nanohybrids as fillers for PA6 based nanocomposites

Energy Technology Data Exchange (ETDEWEB)

Maio, A. [Department of Civil, Environmental, Aerospace, Materials Engineering, University of Palermo, Viale delle Scienze, Ed. 6, 90128, Palermo, Italy and STEBICEF, Section of Biology and Chemistry, University of Palermo, Viale delle Scienze, Parco d' Orleans (Italy); Fucarino, R.; Khatibi, R. [Dipartimento di Ingegneria Chimica, Gestionale, Informatica, Meccanica, University of Palermo, Viale delle Scienze, Ed. 6, 90128, Palermo (Italy); Botta, L.; Scaffaro, R. [Department of Civil, Environmental, Aerospace, Materials Engineering, University of Palermo, Viale delle Scienze, Ed. 6, 90128, Palermo (Italy); Rosselli, S.; Bruno, M. [STEBICEF, Section of Biology and Chemistry, University of Palermo, Viale delle Scienze, Parco d' Orleans II, 90128 Palermo (Italy)

2014-05-15

Graphene oxide (GO) was prepared by oxidation of graphite flakes by a mixture of H{sub 2}SO{sub 4}/H{sub 3}PO{sub 4} and KMnO{sub 4} based on Marcano's method. Two different masterbatches containing GO (33.3%) and polyamide-6 (PA6) (66.7%) were prepared both via solvent casting in formic acid and by melt mixing in a mini-extruder (Haake). The two masterbatches were then used to prepare PA6-based nanocomposites with a content of 2% in GO. For comparison, a nanocomposite by direct mixing of PA6 and GO (2%) and PA6/graphite nanocomposites were prepared, too. The oxidation of graphite into GO was assessed by X-ray diffraction (XRD), Micro-Raman spectroscopy, scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) analyses. All these techniques demonstrated the effectiveness of the graphite modification, since the results put into evidence that, after the acid treatment, interlayer distance, oxygen content and defects increased. SEM micrographs carried out on the nanocomposites, showed GO layers totally surrounded by polyamide-6, this feature is likely due to the strong interaction between the hydrophilic moieties located both on GO and on PA6. On the contrary, no interactions were observed when graphite was used as filler. Mechanical characterization, carried out by tensile and dynamic-mechanical tests, marked an improvement of the mechanical properties observed. Photoluminescence and EPR measurements were carried out onto nanoparticles and nanocomposites to study the nature of the interactions and to assess the possibility to use this class of materials as semiconductors or optical sensors.

Tunable room-temperature ferromagnet using an iron-oxide and graphene oxide nanocomposite

KAUST Repository

Lin, Aigu L.

2015-06-23

Magnetic materials have found wide application ranging from electronics and memories to medicine. Essential to these advances is the control of the magnetic order. To date, most room-temperature applications have a fixed magnetic moment whose orientation is manipulated for functionality. Here we demonstrate an iron-oxide and graphene oxide nanocomposite based device that acts as a tunable ferromagnet at room temperature. Not only can we tune its transition temperature in a wide range of temperatures around room temperature, but the magnetization can also be tuned from zero to 0.011 A m2/kg through an initialization process with two readily accessible knobs (magnetic field and electric current), after which the system retains its magnetic properties semi-permanently until the next initialization process. We construct a theoretical model to illustrate that this tunability originates from an indirect exchange interaction mediated by spin-imbalanced electrons inside the nanocomposite. © 2015 Scientific Reports.

Tunable room-temperature ferromagnet using an iron-oxide and graphene oxide nanocomposite

KAUST Repository

Lin, Aigu L.; Rodrigues, J. N B; Su, Chenliang; Milletari, M.; Loh, Kian Ping; Wu, Tao; Chen, Wei; Neto, A. H Castro; Adam, Shaffique; Wee, Andrew T S

2015-01-01

Magnetic materials have found wide application ranging from electronics and memories to medicine. Essential to these advances is the control of the magnetic order. To date, most room-temperature applications have a fixed magnetic moment whose orientation is manipulated for functionality. Here we demonstrate an iron-oxide and graphene oxide nanocomposite based device that acts as a tunable ferromagnet at room temperature. Not only can we tune its transition temperature in a wide range of temperatures around room temperature, but the magnetization can also be tuned from zero to 0.011 A m2/kg through an initialization process with two readily accessible knobs (magnetic field and electric current), after which the system retains its magnetic properties semi-permanently until the next initialization process. We construct a theoretical model to illustrate that this tunability originates from an indirect exchange interaction mediated by spin-imbalanced electrons inside the nanocomposite. © 2015 Scientific Reports.

Ionic liquid-modified metal sulfides/graphene oxide nanocomposites for photoelectric conversion

International Nuclear Information System (INIS)

Zhang, Yu; Zhang, Yù; Pei, Qi; Feng, Ting; Mao, Hui; Zhang, Wei; Wu, Shuyao; Liu, Daliang; Wang, Hongyu; Song, Xi-Ming

2015-01-01

Graphical abstract: - Highlights: • Metal sulfide (CdS, ZnS, Ag 2 S)/GO nanocomposites were prepared by electrostatic adherence. • Ionic liquid was used to link the metal sulfide and GO in the electrostatic adherence process. • The as-prepared samples showed enhanced photocurrent and highly efficient photocatalytic activity under visible light irradiation. - Abstract: Ionic liquid-modified metal sulfides/graphene oxide nanocomposites are prepared via a facile electrostatic adsorption. Ionic liquid (IL) is firstly used as surface modifier and structure-directing agent of metal sulfide (MS) crystallization process, obtaining ionic liquid modified-MS (IL-MS) nanoparticles with positive charges on surface. IL-MS/GO is obtained by electrostatic adherence between positively charged IL-MS and negatively charged graphene oxide (GO). The as-prepared sample shows enhanced photocurrent and highly efficient photocatalytic activity under visible light irradiation, indicating IL-MS/GO nanocomposites greatly promoted the separation of photogenerated electron–hole pairs

Oxide/polymer nanocomposites as new luminescent materials

Science.gov (United States)

Vollath, D.; Szabó, D. V.; Schlabach, S.

2004-06-01

It is demonstrated that nanocomposites, consisting of an electrically insulating oxide core and PMMA coating exhibit strong luminescence. This luminescence is connected to the interface, where PMMA is bond via a carboxylate bonding to the surface. In this case, luminescence is originated at the carbonyl group of the coating polymer. With decreasing particle size, this emission shows a blue shift, following a law inversely the ones found for quantum confinement systems. For semi-conducting oxides, such as ZnO, this interface related emission is found additionally to quantum confinement phenomena.

Influence of Na diffusion on thermochromism of vanadium oxide films and suppression through mixed-alkali effect

Energy Technology Data Exchange (ETDEWEB)

Miller, Mark J.; Wang, Junlan, E-mail: junlan@u.washington.edu

2015-10-15

Highlights: • Vanadium oxide films were reactively sputtered on three types of glass substrates. • Na diffusion from soda-lime glass undesirably inhibited thermochromism. • Na diffusion was suppressed by replacing half of sodium in glass with potassium. • Mixed-alkali effect promotes thermochromic VO{sub 2} films on glass substrates. - Abstract: Vanadium(IV) oxide possesses a reversible first-order phase transformation near 68 °C. Potential applications of the material include advanced optical devices and thermochromic smart windows. In this study, vanadium oxide films were grown on three types of glass substrates using reactive DC magnetron sputtering and were then annealed in air. The substrates were characterized with energy-dispersive X-ray spectroscopy, and the films were characterized with X-ray photoelectron spectroscopy, X-ray diffraction, scanning electron microscopy, atomic force microscopy, transmission electron microscopy, and UV-Vis-NIR spectrophotometry. The results show that the composition of the substrate has a major impact on the microstructure and optical properties of the deposited films. Sodium (Na) in the glass can undesirably inhibit thermochromism; however, replacing half of the Na with potassium (K) suppresses the Na diffusion and promotes the nucleation of pure VO{sub 2} with superior thermochromic functionality. The improved performance is attributed to the mixed-alkali effect between Na and K. These findings are both scientifically and technologically important since soda (Na{sub 2}O) is an essential flux material in glass products such as windows.

Evaluation of poly (vinyl alcohol) based cryogel–zinc oxide nanocomposites for possible applications as wound dressing materials

Energy Technology Data Exchange (ETDEWEB)

Chaturvedi, Archana [Bose Memorial Research Laboratory, Department of Chemistry, Government Autonomous Science College Jabalpur (India); Bajpai, Anil K., E-mail: akbmrl@yahoo.co.in [Bose Memorial Research Laboratory, Department of Chemistry, Government Autonomous Science College Jabalpur (India); Bajpai, Jaya [Bose Memorial Research Laboratory, Department of Chemistry, Government Autonomous Science College Jabalpur (India); Singh, Sunil K. [Department of Chemistry, Guru Ghasidas University, Bilaspur, CG (India)

2016-08-01

In this investigation cryogels composed of poly (vinyl alcohol) (PVA) were prepared by repeated freeze thaw method followed by in situ precipitation of zinc oxide nanoparticles within the cryogel networks. Fourier transformed infrared spectroscopy (FTIR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray diffraction (XRD), Energy dispersive X-ray spectroscopy (EDX) were used to characterize the nanocomposites. The morphologies of native PVA cryogels and PVA cryogel-ZnO nanocomposites were observed by scanning electron microscopy (SEM), transmission electron microscopy (TEM) techniques. The SEM analysis suggested that cryogels show a well-defined porous morphology whereas TEM micrographs revealed the presence of nearly spherical and well separated zinc oxide nanoparticles with diameter < 100 nm. XRD results showed all relevant Bragg's reflections for crystal structure of zinc oxide nanoparticles. Thermo gravimetric-differential thermal analysis (TG-DTA) was conducted to evaluate thermal stability of the nanocomposites. Mechanical properties of nanocomposites were determined in terms of tensile strength and percent elongation. Biocompatible nature was ascertained by anti-haemolytic activity, bovine serum albumin (blood protein) adsorption and in vitro cytotoxicity tests. The prepared nanocomposites were also investigated for swelling and deswelling behaviours. The results revealed that both the swelling and deswelling process depend on the chemical composition of the nanocomposites, number of freeze-thaw cycles, pH and temperature of the swelling medium. The developed biocompatible PVA cryogel-ZnO nanocomposites were also tested for antibacterial activities against both Gram-negative and Gram-positive bacteria. - Highlights: • PVA–zinc oxide nanocomposites have been prepared with no chemical crosslinking. • The nanocomposites are completely biocompatible. • They also show antibacterial property. • The nanocomposites

Preparation of silicon carbide-supported vanadium oxide and its application of removing NO by ammonia

Energy Technology Data Exchange (ETDEWEB)

Wang, Zi-Bo; Xu, Xu [Yangzhou University, College of Environmental Science and Engineering, Yangzhou, Jiangsu (China); Bai, Shu-Li [Wuyi University, College of Chemical and Environmental Engineering, Jiangmen, Guangdong (China); Guan, Yu-Jiang; Jiang, Sheng-Tao [Taizhou University, Environmental Engineering, Taizhou, Zhejiang (China)

2017-03-15

The aim of this work was to study the preparation of SiC-supported V{sub 2}O{sub 5} catalysts and the kinetics on selective catalytic reduction for NO with NH{sub 3} on the catalysts. Using incipient wetness impregnation methods, vanadium oxide was applied to silicon carbide to prepare a SiC-supported vanadium oxide. X-ray photoelectron spectroscopy analysis confirmed that V{sub 2}O{sub 5} existed in the prepared materials. Using the prepared materials as catalysts, selective catalytic reduction for NO by NH{sub 3} has been analyzed, and reaction kinetics on the catalysts was studied at 150-300 C. The obtained results showed that the reduction reaction on the catalysts is close to zero-order kinetics with respect to NH{sub 3}, first-order with respect to NO, and half-order to O{sub 2}. Apparent activation energy for the reduction reaction was found to be 38 kJ mol{sup -1}. The prepared materials are stable and reusable. (orig.)

Three-dimensional Nitrogen-Doped Reduced Graphene Oxide/Carbon Nanotube Composite Catalysts for Vanadium Flow Batteries

Energy Technology Data Exchange (ETDEWEB)

Fu, Shaofang [School of Mechanical and Materials Engineering, Washington State University, WA, 99164 USA.; Zhu, Chengzhou [School of Mechanical and Materials Engineering, Washington State University, WA, 99164 USA.; Song, Junhua [School of Mechanical and Materials Engineering, Washington State University, WA, 99164 USA.; Engelhard, Mark H. [Environmental Molecular Science Laboratory, Pacific Northwest National Laboratory, Richland, WA 99354 USA.; Du, Dan [School of Mechanical and Materials Engineering, Washington State University, WA, 99164 USA.; Lin, Yuehe [School of Mechanical and Materials Engineering, Washington State University, WA, 99164 USA.; Environmental Molecular Science Laboratory, Pacific Northwest National Laboratory, Richland, WA 99354 USA.

2017-02-22

The development of vanadium redox flow battery is limited by the sluggish kinetics of the reaction, especially the cathodic VO2+/VO2+ redox couples. Therefore, it is vital to develop new electrocatalyst with enhanced activity to improve the battery performance. Herein, we first synthesized the hydrogel precursor by a facile hydrothermal method. After the following carbonization, nitrogen-doped reduced graphene oxide/carbon nanotube composite was obtained. By virtue of the large surface area and good conductivey, which are ensured by the unique hybrid structure, as well as the proper nitrogen doping, the as-prepared composite presents enhanced catalytic performance toward the VO2+/VO2+ redox reaction. We also demonstrated the composite with carbon nanotube loading of 2 mg/mL exhibits the highest activity and remarkable stability in aqueous solution due to the strong synergy between reduced graphene oxide and carbon nanotubes, indicating that this composite might show promising applications in vanadium redox flow battery.

Ion sensing properties of vanadium/tungsten mixed oxides

International Nuclear Information System (INIS)

Guidelli, Eder Jose; Guerra, Elidia Maria; Mulato, Marcelo

2011-01-01

Vanadium/tungsten mixed oxide (V 2 O 5 /WO 3 ) sensing membranes were deposited on glassy carbon substrates and used as the H + sensor of the extended gate field effect transistor (EGFET) device. X-ray diffractograms indicated a decrease of the interplanar spacing of V 2 O 5 after the insertion of WO 3 revealing that the lamellar structure is under compressive stress. The crystallinity increases with increasing WO 3 molar ratio. The film is not homogeneous, with more WO 3 material sitting at the surface. This influences the response of pH sensors using the EGFET configuration. The maximum sensitivity of 68 mV pH -1 was obtained for the sample with 5% WO 3 molar ratio. For higher WO 3 molar ratios, the behavior is not linear. It can be concluded that V 2 O 5 dominates for acidic solutions while WO 3 dominates for basic solutions. Therefore, the mixed oxide with low amount of WO 3 is the main candidate for further use as biosensor.

Liquid crystalline polymer nanocomposites reinforced with in-situ reduced graphene oxide

Directory of Open Access Journals (Sweden)

D. Pedrazzoli

2015-08-01

Full Text Available In this work liquid-crystalline polymer (LCP nanocomposites reinforced with in-situ reduced graphene oxide are investigated. Graphene oxide (GO was first synthesized by the Hummers method, and the kinetics of its thermal reduction was assessed. GO layers were then homogeneously dispersed in a thermotropic liquid crystalline polymer matrix (Vectran®, and an in-situ thermal reduction of GO into reduced graphene oxide (rGO was performed. Even at low rGO amount, the resulting nanocomposites exhibited an enhancement of both the mechanical properties and the thermal stability. Improvements of the creep stability and of the thermo-mechanical behavior were also observed upon nanofiller incorporation. Furthermore, in-situ thermal reduction of the insulating GO into the more electrically conductive rGO led to an important surface resistivity decrease in the nanofilled samples.

Design and development of anisotropic inorganic/polystyrene nanocomposites by surface modification of zinc oxide nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Han, Xiao [School of Materials Science and Engineering, Tongji University, Shanghai 200092 (China); Research Center for Translational Medicine, East Hospital, the Institute for Biomedical Engineering & Nano Science, Tongji University School of Medicine, Shanghai 200092 (China); Huang, Shiming [Department of Physics, Tongji University, Shanghai 200092 (China); Wang, Yilong, E-mail: yilongwang@tongji.edu.cn [Research Center for Translational Medicine, East Hospital, the Institute for Biomedical Engineering & Nano Science, Tongji University School of Medicine, Shanghai 200092 (China); Shi, Donglu, E-mail: shid@ucmail.uc.edu [Research Center for Translational Medicine, East Hospital, the Institute for Biomedical Engineering & Nano Science, Tongji University School of Medicine, Shanghai 200092 (China); The Materials Science and Engineering Program, College of Engineering and Applied Science, University of Cincinnati, Cincinnati, OH 45221 (United States)

2016-07-01

Anisotropic yolk/shell or Janus inorganic/polystyrene nanocomposites were prepared by combining miniemulsion polymerization and sol–gel reaction. The morphologies of the anisotropic composites were found to be greatly influenced by surface modification of zinc oxide (ZnO) nanoparticle seeds. Two different types of the oleic acid modified ZnO nanoparticles (OA-ZnO) were prepared by post-treatment of commercial ZnO powder and homemade OA-ZnO nanoparticles. The morphologies and properties of the nanocomposites were investigated by transmission electron microscope (TEM), thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FT-IR), dynamic light scattering (DLS), and energy dispersive X-ray spectroscopy (EDX). It was found that both post-treated OA-ZnO and in-situ prepared OA-ZnO nanoparticles resulted in the yolk–shell and Janus structure nanocomposites, but with varied size and morphology. These nanocomposites showed stable and strong fluorescence by introducing quantum dots as the co-seeds. The fluorescent anisotropic nanocomposites were decorated separately with surface carboxyl and hydroxyl groups. These composites with unique anisotropic properties will have high potential in biomedical applications, particularly in bio-detection. - Graphical abstract: Design and development of anisotropic inorganic/polystyrene nanocomposites by surface modification of zinc oxide nanoparticles. - Highlights: • Non-magnetic anisotropic yolk/shell or Janus nanocomposites are prepared and characterized. • Different surface modification of zinc oxide (ZnO) nanoparticles results in varied morphology and size of the final product. • Fluorescent anisotropic nanocomposites embodying quantum dots are an ideal candidate for bio-detection applications.

Annealing effects on the structural and optical properties of vanadium oxide film obtained by the hot-filament metal oxide deposition technique (HFMOD)

Energy Technology Data Exchange (ETDEWEB)

Scarminio, Jair; Silva, Paulo Rogerio Catarini da, E-mail: scarmini@uel.br, E-mail: prcsilva@uel.br [Universidade Estadual de Londrina (UEL), PR (Brazil). Departamento de Fisica; Gelamo, Rogerio Valentim, E-mail: rogelamo@gmail.com [Universidade Federal do Triangulo Mineiro (UFTM), Uberaba, MG (Brazil); Moraes, Mario Antonio Bica de, E-mail: bmoraes@mailhost.ifi.unicamp.br [Universidade Estadual de Campinas (UNICAMP), SP (Brazil)

2017-01-15

Vanadium oxide films amorphous, nonstoichiometric and highly absorbing in the optical region were deposited on ITO-coated glass and on silicon substrates, by the hot-filament metal oxide deposition technique (HFMOD) and oxidized by ex-situ annealing in a furnace at 200, 300, 400 and 500 deg C, under an atmosphere of argon and rarefied oxygen. X-ray diffraction, Raman and Rutherford backscattering spectroscopy as well as optical transmission were employed to characterize the amorphous and annealed films. When annealed at 200 and 300 deg C the as-deposited opaque films become transparent but still amorphous. Under treatments at 400 and 500 deg C a crystalline nonstoichiometric V{sub 2}O{sub 5} structure is formed. All the annealed films became semiconducting, with their optical absorption coefficients changing with the annealing temperature. An optical gap of 2.25 eV was measured for the films annealed at 400 and 500 deg C. The annealing in rarefied oxygen atmosphere proved to be a useful and simple ex-situ method to modulate the structural and optical properties of vanadium oxide films deposited by HFMOD technique. This technique could be applied to other amorphous and non-absorbing oxide films, replacing the conventional and sometimes expensive method of modulate desirable film properties by controlling the film deposition parameters. Even more, the HFMOD technique can be an inexpensive alternative to deposit metal oxide films. (author)

Radiation modification of vanadium catalyst for anthracene oxidation

International Nuclear Information System (INIS)

Norek, J.; Vymetal, J.; Mucka, V.; Pospisil, M.; Cabicar, J.

1985-01-01

Vanadium pentoxide on a suitable carrier is often used as catalyst for the oxidation of anthracene in the gaseous phase to 9,10-anthraquinone. The activity and selectivity of the catalyst may be affected by irradiation. The effects were studied of gamma radiation on the properties of the catalyst where the active system was a V 2 O 5 -KOH-K 2 SO 4 mixture on a Al 2 O 3 +SiO 2 carrier. The 60 Co radiation source had an activity of 185 TBq; the carrier of the catalyst was irradiated at a dose rate of 3.05, 1.98 and 0.084 kGy/h to a total dose of 10 kGy. Irradiation increased the selectivity of the catalyst such that in the oxidation temperature optimum of 300 to 400 degC the yield of 9,10-anthraquinone increased by 4.6 to 4.8 %mol. to roughly 90 %mol.; a significant reduction of the content of acid components (phthalanhydride) in the oxidation product also occurred. This effect remained unchanged for 5 months after irradiation. A reduction of selectivity was observed at lower dose rates only in the temperature range between 400 and 480 degC. (A.K.)

Hybrid ternary rice paper-manganese oxide-carbon nanotube nanocomposites for flexible supercapacitors

Science.gov (United States)

Jiang, Wenchao; Zhang, Kaixi; Wei, Li; Yu, Dingshan; Wei, Jun; Chen, Yuan

2013-10-01

Modern portable electronic devices create a strong demand for flexible energy storage devices. Paper based nanocomposites are attractive as sustainable materials for such applications. Here, we directly explored the hydroxyl chemistry of cellulose fibers to synthesize hybrid ternary nanocomposites, comprised of rice paper, single-walled carbon nanotubes (SWCNTs) and manganese oxide nanoparticles. The functional groups on cellulose fibers can react with adsorbed permanganate ions, resulting in uniform deposition of manganese oxide nanoparticles. SWCNTs coated on top of manganese oxide nanoparticles form a highly conductive network connecting individual manganese oxide particles. By using the hybrid ternary composites as electrodes, the assembled two-electrode supercapacitors demonstrated high capacitance (260.2 F g-1), energy (9.0 W h kg-1), power (59.7 kW kg-1), and cycle stability (12% drop after 3000 cycles). In addition, the nanocomposites show good strength and excellent mechanical flexibility, and their capacitance shows negligible changes after bending more than 100 times. These findings suggest that opportunities exist to further explore the rich chemistry of cellulose fibers for innovative energy applications.Modern portable electronic devices create a strong demand for flexible energy storage devices. Paper based nanocomposites are attractive as sustainable materials for such applications. Here, we directly explored the hydroxyl chemistry of cellulose fibers to synthesize hybrid ternary nanocomposites, comprised of rice paper, single-walled carbon nanotubes (SWCNTs) and manganese oxide nanoparticles. The functional groups on cellulose fibers can react with adsorbed permanganate ions, resulting in uniform deposition of manganese oxide nanoparticles. SWCNTs coated on top of manganese oxide nanoparticles form a highly conductive network connecting individual manganese oxide particles. By using the hybrid ternary composites as electrodes, the assembled two

Studies of vanadium-phosphorus-oxygen selective oxidation catalysts by sup 31 P and sup 51 V NMR spin-echo and volume susceptibility measurements

Energy Technology Data Exchange (ETDEWEB)

Li, Juan.

1991-10-01

The purpose of this work is to characterize the vanadium-phosphorous oxide (V-P-O) catalysts for the selective oxidation of n-butane and 1-butene to maleic anhydride. The utility of solid state nuclear magnetic resonance as an analytical tool in this investigation lies in its sensitivity to the electronic environment surrounding the phosphorous and vanadium nuclei, and proximity of paramagnetic species. Spin-echo mapping NMR of {sup 31}p and {sup 51}v and volume magnetic susceptibility measurements were used as local microscopic probes of the presence of V{sup 5+}, V{sup 4+}, V{sup 3+} species in the model compounds: {beta}-VOPO{sub 4}, {beta}-VOPO{sub 4} treated with n-butane/1-butene, (VO){sub 2}P{sub 2}O{sub 7} treated with n-butane/1-butene; and industrial catalysts with P/V (phosphorus to vanadium) ratio of 0.9, 1.0 and 1.1, before and after treatment with n-butane and 1-butene. The NMR spectra provide a picture of how the oxidation states of vanadium are distributed in these catalysts. 73 refs., 32 figs., 8 tabs.

Cross-linkable graphene oxide embedded nanocomposite hydrogel with enhanced mechanics and cytocompatibility for tissue engineering.

Science.gov (United States)

Liu, Xifeng; Miller, A Lee; Waletzki, Brian E; Lu, Lichun

2018-05-01

Graphene oxide (GO) is an attractive material that can be utilized to enhance the modulus and conductivities of substrates and hydrogels. To covalently cross-link graphene oxide sheets into hydrogels, abundant cross-linkable double bonds were introduced to synthesize the graphene-oxide-tris-acrylate sheet (GO-TrisA). Polyacrylamide (PAM) nanocomposite hydrogels were then fabricated with inherent covalently and permanently cross-linked GO-TrisA sheets. Results showed that the covalently cross-linked GO-TrisA/PAM nanocomposite hydrogel had enhanced mechanical strength, thermo stability compared with GO/PAM hydrogel maintained mainly by hydrogen bonding between PAM chains and GO sheets. In vitro cell study showed that the covalently cross-linked rGO-TrisA/PAM nanocomposite hydrogel had excellent cytocompatibility after in situ reduction. These results suggest that rGO-TrisA/PAM nanocomposite hydrogel holds great potential for tissue engineering applications. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 106A: 1247-1257, 2018. © 2018 Wiley Periodicals, Inc.

Electrochromic nanocomposite films

Science.gov (United States)

Milliron, Delia; Llordes, Anna; Buonsanti, Raffaella; Garcia, Guillermo

2018-04-10

The present invention provides an electrochromic nanocomposite film. In an exemplary embodiment, the electrochromic nanocomposite film, includes (1) a solid matrix of oxide based material and (2) transparent conducting oxide (TCO) nanostructures embedded in the matrix. In a further embodiment, the electrochromic nanocomposite film farther includes a substrate upon which the matrix is deposited. The present invention also provides a method of preparing an electrochromic nanocomposite film.

Graphene oxide/MnO{sub 2} nanocomposite as destructive adsorbent of nerve-agent simulants in aqueous media

Energy Technology Data Exchange (ETDEWEB)

Šťastný, Martin, E-mail: stastny@iic.cas.cz [Materials Chemistry Department, Institute of Inorganic Chemistry AS CR v.v.i., 25068 Husinec-Řež (Czech Republic); Faculty of the Environment, J.E. Purkyně University in Ústí nad Labem, Králova Výšina 7, 400 96 Ústí nad Labem (Czech Republic); Tolasz, Jakub; Štengl, Václav; Henych, Jiří [Materials Chemistry Department, Institute of Inorganic Chemistry AS CR v.v.i., 25068 Husinec-Řež (Czech Republic); Žižka, David [Faculty of the Environment, J.E. Purkyně University in Ústí nad Labem, Králova Výšina 7, 400 96 Ústí nad Labem (Czech Republic)

2017-08-01

Highlights: • Nanocomposite graphene oxide-birnessite-type MnO{sub 2} was synthesized by thermal hydrolysis. • New destructive sorbent for safe degradation of nerve-agent simulants. • 95% degradation activity for DMMP and TEP. - Abstract: Graphene oxide/MnO{sub 2} nanocomposite was prepared by thermal hydrolysis of potassium permanganate (KMnO{sub 4}) and 2-chloroacetamide aqueous solutions with graphene oxide (GO) suspension. The synthesized samples were characterized by specific surface area (BET) and porosity determination (BJH), X-ray Diffraction (XRD) and high-resolution electron microscopes (HRSEM, HRTEM). These nanocomposites were used in an experimental evaluation of their adsorption activity with nerve agent simulants dimethyl methyl phosphonate (DMMP) and triethyl phosphate (TEP) in aqueous media. The nanocomposites exhibited enhanced adsorptive degradation ability compared to pure manganese oxide (MnO{sub 2}) and GO. The GO amount in the nanocomposites affected their degradation activity substantially. The best adsorption efficiency was observed for samples with moderate GO amount. Three methods were used to observe the mechanism of the nerve-agent simulants deactivation: Gas chromatography with mass spectrometry (GC–MS), High-Performance Liquid Chromatography (HPLC) and in situ Infrared spectroscopy (FTIR). It was shown that the hydrolysis on the surface of prepared nanocomposites yields volatile primary alcohols (methanol and ethanol) as the main hydrolysis products.

Vanadium and affective disorders

International Nuclear Information System (INIS)

Naylor, G.J.

1985-01-01

The oxidation reduction state of vanadium will influence its inhibitory effect, and it has been suggested that the control of this oxidation reduction could be a physiological means of controlling Na-K ATPase and hence membrane transport. However, there is no general agreement on this. For such a hypothesis to be true, tissue concentrations of vanadium would need to be sufficient to cause inhibition of Na-K ATPase. There has been considerable variation in the concentration of vanadium reported to be present in human blood and plasma - e.g., 8.4 μmoleliter, 0.11 μmoleliter, 0.04 μmoleliter and 0.0006-0.018 μmliter. Methods of assay have varied, even including enzymic methods, but the two major methods now used are neutron activation analysis and atomic absorption spectrophotometry using an electrical flameless atomizer. Using neutron activation analysis, difficulties arise from the short half-ife of V 52 (3.76 min) and for the need to separate Na 24 and Cl 36 from the sample since their radiation interfere with those from V 52 . Results from preirradiation separation agree well with those from atomic absorption spectrophotometry, but those from postirradiation separation are usually much lower. Though there is no agreement on the physiological role of vanadium there is evidence that it plays a part in the etiology of manic-depressive psychosis

Oxidative Stress as a Mechanism Involved in Kidney Damage After Subchronic Exposure to Vanadium Inhalation and Oral Sweetened Beverages in a Mouse Model.

Science.gov (United States)

Espinosa-Zurutuza, Maribel; González-Villalva, Adriana; Albarrán-Alonso, Juan Carlos; Colín-Barenque, Laura; Bizarro-Nevares, Patricia; Rojas-Lemus, Marcela; López-Valdéz, Nelly; Fortoul, Teresa I

Kidney diseases have notably increased in the last few years. This is partially explained by the increase in metabolic syndrome, diabetes, and systemic blood hypertension. However, there is a segment of the population that has neither of the previous risk factors, yet suffers kidney damage. Exposure to atmospheric pollutants has been suggested as a possible risk factor. Air-suspended particles carry on their surface a variety of fuel combustion-related residues such as metals, and vanadium is one of these. Vanadium might produce oxidative stress resulting in the damage of some organs such as the kidney. Additionally, in countries like Mexico, the ingestion of sweetened beverages is a major issue; whether these beverages alone are responsible for direct kidney damage or whether their ingestion promotes the progression of an existing renal damage generates controversy. In this study, we report the combined effect of vanadium inhalation and sweetened beverages ingestion in a mouse model. Forty CD-1 male mice were distributed in 4 groups: control, vanadium inhalation, 30% sucrose in drinking water, and vanadium inhalation plus sucrose 30% in drinking water. Our results support that vanadium inhalation and the ingestion of 30% sucrose induce functional and histological kidney damage and an increase in oxidative stress biomarkers, which were higher in the combined effect of vanadium plus 30% sucrose. The results also support that the ingestion of 30% sucrose alone without hyperglycemia also produces kidney damage.

Assessment of morphology and property of graphene oxide-hydroxypropylmethylcellulose nanocomposite films.

Science.gov (United States)

Ghosh, Tapas Kumar; Gope, Shirshendu; Mondal, Dibyendu; Bhowmik, Biplab; Mollick, Md Masud Rahaman; Maity, Dipanwita; Roy, Indranil; Sarkar, Gunjan; Sadhukhan, Sourav; Rana, Dipak; Chakraborty, Mukut; Chattopadhyay, Dipankar

2014-05-01

Graphene oxide (GO) was synthesized by Hummer's method and characterized by using Fourier transform infrared spectroscopy and Raman spectroscopy. The as synthesized GO was used to make GO/hydroxypropylmethylcellulose (HPMC) nanocomposite films by the solution mixing method using different concentrations of GO. The nanocomposite films were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM) and thermo-gravimetric analysis. Mechanical properties, water absorption property and water vapor transmission rate were also measured. XRD analysis showed the formation of exfoliated HPMC/GO nanocomposites films. The FESEM results revealed high interfacial adhesion between the GO and HPMC matrix. The tensile strength and Young's modulus of the nanocomposite films containing the highest weight percentage of GO increased sharply. The thermal stability of HPMC/GO nanocomposites was slightly better than pure HPMC. The water absorption and water vapor transmission rate of HPMC film was reduced with the addition of up to 1 wt% GO. Copyright © 2014 Elsevier B.V. All rights reserved.

Carbon nanotube/platinum nanoparticle nanocomposites: preparation, characterization and application in electro oxidation of alcohols

International Nuclear Information System (INIS)

Kalinke, Adir H.; Zarbin, Aldo J. G.

2014-01-01

The synthesis and characterization of different platinum nanoparticle/ carbon nanotube nanocomposite samples are described along with the application of these nanocomposites as electrocatalysts for alcohol oxidation. Samples were prepared by a biphasic system in which platinum nanoparticles (Pt-NPs) are synthesized in situ in contact with a carbon nanotube (CNT) dispersion. Variables including platinum precursor/CNT ratio, previous chemical treatment of carbon nanotubes, and presence or absence of a capping agent were evaluated and correlated with the characteristic of the synthesized materials. Samples were characterized by Raman spectroscopy, X-ray diffraction, thermogravimetric analysis and transmission electron microscopy. Glassy carbon electrodes were modified by the nanocomposite samples and evaluated as electrocatalysts for alcohol oxidation. Current densities of 56.1 and 79.8/104.7 mA cm -2 were determined for the oxidation of methanol and ethanol, respectively. (author)

Nanocomposite oxide thin films grown by pulsed energy beam deposition

International Nuclear Information System (INIS)

Nistor, M.; Petitmangin, A.; Hebert, C.; Seiler, W.

2011-01-01

Highly non-stoichiometric indium tin oxide (ITO) thin films were grown by pulsed energy beam deposition (pulsed laser deposition-PLD and pulsed electron beam deposition-PED) under low oxygen pressure. The analysis of the structure and electrical transport properties showed that ITO films with a large oxygen deficiency (more than 20%) are nanocomposite films with metallic (In, Sn) clusters embedded in a stoichiometric and crystalline oxide matrix. The presence of the metallic clusters induces specific transport properties, i.e. a metallic conductivity via percolation with a superconducting transition at low temperature (about 6 K) and the melting and freezing of the In-Sn clusters in the room temperature to 450 K range evidenced by large changes in resistivity and a hysteresis cycle. By controlling the oxygen deficiency and temperature during the growth, the transport and optical properties of the nanocomposite oxide films could be tuned from metallic-like to insulating and from transparent to absorbing films.

Integrated Ternary Bioinspired Nanocomposites via Synergistic Toughening of Reduced Graphene Oxide and Double-Walled Carbon Nanotubes.

Science.gov (United States)

Gong, Shanshan; Cui, Wei; Zhang, Qi; Cao, Anyuan; Jiang, Lei; Cheng, Qunfeng

2015-12-22

With its synergistic toughening effect and hierarchical micro/nanoscale structure, natural nacre sets a "gold standard" for nacre-inspired materials with integrated high strength and toughness. We demonstrated strong and tough ternary bioinspired nanocomposites through synergistic toughening of reduced graphene oxide and double-walled carbon nanotube (DWNT) and covalent bonding. The tensile strength and toughness of this kind of ternary bioinspired nanocomposites reaches 374.1 ± 22.8 MPa and 9.2 ± 0.8 MJ/m(3), which is 2.6 and 3.3 times that of pure reduced graphene oxide film, respectively. Furthermore, this ternary bioinspired nanocomposite has a high conductivity of 394.0 ± 6.8 S/cm and also shows excellent fatigue-resistant properties, which may enable this material to be used in aerospace, flexible energy devices, and artificial muscle. The synergistic building blocks with covalent bonding for constructing ternary bioinspired nanocomposites can serve as the basis of a strategy for the construction of integrated, high-performance, reduced graphene oxide (rGO)-based nanocomposites in the future.

A Novel Method of Mechanical Oxidation of CNT for Polymer Nanocomposite Application: Evaluation of Mechanical, Dynamic Mechanical, and Rheological Properties

Directory of Open Access Journals (Sweden)

Priyanka Pandey

2014-01-01

Full Text Available A new approach of oxidation of carbon nanotubes has been used to oxidize the CNTs. A comparative aspect of the mechanical oxidation and acid oxidation process has been established. FTIR analysis and titration method have shown the higher feasibility of the mechanical oxidation method to oxidize the CNTs. Comparatively less damage to the CNTs has been observed in case of mechanically oxidized as compared to acid oxidized CNTs. The mechanical properties of the nanocomposites reinforced with the acid oxidized CNT (ACNT and mechanically oxidized CNTs (McCNT were analyzed and relatively higher properties in the nanocomposites reinforced with McCNT were noticed. The less degree of entanglement in the McCNTs was noticed as compared to ACNTs. The dynamic mechanical analysis of the nanocomposites revealed much improved load transfer capability in the McCNT reinforced composites. Further, the rheological properties of the nanocomposites revealed the higher performance of McCNT reinforced composites.

Biomolecule-assisted synthesis of Ag/reduced graphene oxide nanocomposite with excellent electrocatalytic and antibacterial performance

Energy Technology Data Exchange (ETDEWEB)

Fathalipour, Soghra, E-mail: fathalipour@pnu.ac.ir [Department of Chemistry, Payame Noor University, PO Box: 19395-3697, Tehran (Iran, Islamic Republic of); Pourbeyram, Sima; Sharafian, Aziaeh [Department of Chemistry, Payame Noor University, PO Box: 19395-3697, Tehran (Iran, Islamic Republic of); Tanomand, Asghar [Department of Basic Sciences, Faculty Of Medicine, Maragheh University of Medical Sciences, PO Box: 78151-55158 (Iran, Islamic Republic of); Azam, Parisa [Department of Chemistry, Payame Noor University, PO Box: 19395-3697, Tehran (Iran, Islamic Republic of)

2017-06-01

In this work, an environmentally friendly method was applied for the synthesis of aqueous suspension of L-cysteine modified Ag nanoparticles (NPs)-decorated reduced graphene oxide (rGO) nanocomposite. L-cysteine played a triple role as reducing agent, stabilizer and linker of Ag NPs onto the surface of rGO. The resultant nanocomposite was characterized by Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction studies (XRD), zeta potential, Raman spectroscopy, scanning electron microscopy (SEM) and energy dispersive analysis of X-ray (EDX). Meanwhile, minimum inhibitory concentration (MIC), minimum bacterial concentration (MBC), agar well diffusion and cyclic voltammetry (CV) techniques were used for the investigation of antibacterial and electrocatalytic behaviors of the nanocomposite, respectively. The obtained nanocomposite showed not only enhanced electrocatalytic activity for glucose but also excellent antibacterial activity against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus). - Highlights: • Biocompatible reduced graphene oxide/ Ag nanocomposite was synthesized based on cysteine- Ag nanoparticles. • The reaction was carried out at room temperature without any further reducer. • The nanocomposite displayed excellent antibacterial and electrocatalytic activity against glucose.

Chitosan/graphene oxide nanocomposite films with enhanced interfacial interaction and their electrochemical applications

International Nuclear Information System (INIS)

He, Linghao; Wang, Hongfang; Xia, Guangmei; Sun, Jing; Song, Rui

2014-01-01

Graphical abstract: Nanocomposites by introducing graphene oxide (GO) into chitosan (CS) matrix were prepared and the effect of GO on the crystallization, thermal stability and mechanical properties of the films were investigated. In addition, the electrochemical behavior of the CS/GO modified electrode was comparatively studied with that of the neat CS-modified electrode. - Highlights: • Graphene oxide (GO) with well dispersion in the biopolymer chitosan (CS) matrix. • Detectable interactions do exist between the GO nanosheets and CS segments. • The addition of minor GO can improve the electrochemical activity of the neat CS. - Abstract: A series of chitosan (CS) nanocomposites incorporated with graphene oxide (GO) nanosheets were facilely prepared by sonochemical method. Characterized by scanning electron microscopy, the obtained nanocomposites showed fine dispersion of GO in the CS matrix. Meanwhile, a marked interfacial interaction was also revealed as the values of glass transition temperature, the decomposition temperature and the storage modulus were significantly increased with the addition of GO. Furthermore, the well dispersed GO nanosheets could significantly improve the electrochemical activity of the CS as demonstrated by the electrochemical behaviors of pure CS and the GO/CS composite electrodes. Hence, the GO/CS nanocomposites film could be a promising candidate in the fabrication of electrochemical biosensors

Metal Oxide-Carbon Nanocomposites for Aqueous and Nonaqueous Supercapacitors, Phase I

Data.gov (United States)

National Aeronautics and Space Administration — This Small Business Innovation Research Phase I effort focuses on development of novel metal-oxide-carbon nanocomposites for application in pseudocapacitive...

Oxidative dehydrogenation of ethane over vanadium supported on mesoporous materials of M41S family

Czech Academy of Sciences Publication Activity Database

Čapek, J.; Adam, J.; Grygar, Tomáš; Bulánek, R.; Vradman, L.; Košová-Kučerová, G.; Čičmanec, P.; Knotek, P.

2008-01-01

Roč. 342, 1-2 (2008), s. 99-106 ISSN 0926-860X Grant - others:GA ČR(CZ) GP104/07/P038 Program:GP Institutional research plan: CEZ:AV0Z40320502 Keywords : oxidative dehydrogenation * ethane * vanadium * mesoporous materials Subject RIV: CA - Inorganic Chemistry Impact factor: 3.190, year: 2008

One-step synthesis and properties of monolithic photoluminescent ruby colored cuprous oxide antimony oxide glass nanocomposites

Energy Technology Data Exchange (ETDEWEB)

Som, Tirtha [Glass Science and Technology Section, Glass Division, Central Glass and Ceramic Research Institute, Council of Scientific and Industrial Research (CSIR, India), 196, Raja S.C. Mullick Road, Kolkata 700032 (India); Karmakar, Basudeb, E-mail: basudebk@cgcri.res.in [Glass Science and Technology Section, Glass Division, Central Glass and Ceramic Research Institute, Council of Scientific and Industrial Research (CSIR, India), 196, Raja S.C. Mullick Road, Kolkata 700032 (India)

2011-04-14

Research highlights: > Single-step synthesis of Cu{sub 2}O, Cu{sub y}Sb{sub 2-x}(O,OH){sub 6-7} (y {<=} 2, x {<=} 1) and Cu nanocrystals co-doped novel antimony oxide glass hybrid nanocomposites. > Yellow and orange colored nanocomposites shows size-controlled band gap shift of Cu{sub 2}O. > Red nanocomposite exhibits surface plasmon resonance band due to metallic Cu. > They exhibit broad deep-red photoluminescence emission under various UV excitation wavelengths. - Abstract: Cuprous oxide (Cu{sub 2}O) antimony glass (K{sub 2}O-B{sub 2}O{sub 3}-Sb{sub 2}O{sub 3}) monolithic nanocomposites having brilliant yellow to ruby red color have been synthesized by a single-step melt-quench technique involving in situ thermochemical reduction of Cu{sup 2+} (CuO) by the reducing glass matrix without using any external reducing agent. The X-ray diffraction (XRD), infrared transmission and reflection spectra, and selected area electron diffraction analysis support the reduction of Cu{sup 2+} to Cu{sup +} with the formation of Cu{sub 2}O nanoclusters along with Cu{sub y}Sb{sub 2-x}(O,OH){sub 6-7} (y {<=} 2, x {<=} 1) nanocrystalline phases while Cu{sup 0} nanoclusters are formed at very high Cu concentration. The UV-vis spectra of the yellow and orange colored nanocomposites show size-controlled band gap shift of the semiconductor (Cu{sub 2}O) nanocrystallites embedded in the glasses while the red nanocomposite exhibits surface plasmon resonance band at 529 nm due to metallic Cu. Transmission electron microscopic image advocates the formation of nanocystallites (5-42 nm). Photoluminescence emission studies show broad red emission band around 626 nm under various excitation wavelengths from 210 to 270 nm.

Colloidal titania-silica-iron oxide nanocomposites and the effect from silica thickness on the photocatalytic and bactericidal activities

Energy Technology Data Exchange (ETDEWEB)

Chanhom, Padtaraporn [Department of Chemistry, Faculty of Science, Chulalongkorn University, Bangkok 10330 (Thailand); Charoenlap, Nisanart [Laboratory of Biotechnology, Chulabhorn Research Institute, Bangkok 10210 (Thailand); Tomapatanaget, Boosayarat [Department of Chemistry, Faculty of Science, Chulalongkorn University, Bangkok 10330 (Thailand); Insin, Numpon, E-mail: Numpon.I@chula.ac.th [Department of Chemistry, Faculty of Science, Chulalongkorn University, Bangkok 10330 (Thailand)

2017-04-01

New types of colloidal multifunctional nanocomposites that combine superparamagnetic character and high photocatalytic activity were synthesized and investigated. The superparamagnetic nanocomposites composed of anatase titania, silica, and iron oxide nanoparticles (TSI) were synthesized using thermal decomposition method followed by microemulsion method, without calcination at high temperature. Different techniques including X-ray diffraction (XRD) and transmission electron microscope (TEM) were used to characterize and confirm the structure of the nanocomposites. These nanocomposites showed high photocatalytic activity when used in the photodegradation of methylene blue under irradiation with a black light lamp. Moreover, the nanocomposites exhibited high antibacterial properties. From our study, the nanocomposites can be useful in various applications such as removal of pollutants with readily separation from the environment using an external magnetic field. These composites could effectively photo-degrade the dye at least three cycles without regeneration. The effects of silica shell thickness on the photocatalytic activity was investigated, and the thickness of 6 nm of the silica interlayer is enough for the inhibition of electron translocation between titania and iron oxide nanoparticles and maintaining the efficiency of photocatalytic activity of titania nanoparticles. - Highlights: • New colloidal nanocomposites of iron oxide-silica-titania were prepared. • The nanocomposites exhibited high photocatalytic activity with magnetic response. • The effects of silica thickness on photocatalytic activity were investigated. • Bactericidal activity of the nanocomposites was demonstrated.

Vacancy distribution in nonstoichiometric vanadium monoxide

International Nuclear Information System (INIS)

Gusev, A.I.; Davydov, D.A.; Valeeva, A.A.

2011-01-01

Graphical abstract: Display Omitted Research highlights: → A certain fraction of vanadium atoms in disordered cubic vanadium monoxide VO y and ordered tetragonal phase V 52 O 64 is located in tetrahedral positions of a basic cubic lattice. → These positions are never occupied by any atoms in other strongly nonstoichiometric carbides, nitrides and oxides. → Both disordered and ordered structures of vanadium monoxide are characterized by the presence of short-range order of displacements in the oxygen sublattice and short-range order of substitution in the metal sublattice. → The short-range order of displacement is caused by the local displacements of O atoms from V (t) atoms occupying tetrahedral positions. The short-range order of substitution appears because V (t) atoms in the tetrahedral positions are always in the environment of four vacancies □ of the vanadium sublattice. - Abstract: Structural vacancy distribution in the crystal lattice of the tetragonal V 52 O 64 superstructure which is formed on the basis of disordered superstoichiometric cubic vanadium monoxide VO y ≡V x O z is experimentally determined and the presence of significant local atomic displacements and large local microstrains in a crystal lattice of real ordered phase is established. It is shown that the relaxation of local microstrains takes place owing to the basic disordered cubic phase grain refinement and a formation of ordered phase domains. The ordered phase domains grow in the direction from the boundaries to the centre of grains of the disordered basic cubic phase. Isothermal evolution at 970 K of the average domain size in ordered VO 1.29 vanadium monoxide is established. It is shown that the short-range order presents in a metal sublattice of disordered cubic VO y vanadium monoxide. The character of the short-range order is such that vanadium atoms occupying tetrahedral positions are in the environment of four vacant sites of the vanadium sublattice. This means that the

Vanadium pentoxide nanoparticles mimic vanadium haloperoxidases and thwart biofilm formation

Science.gov (United States)

Natalio, Filipe; André, Rute; Hartog, Aloysius F.; Stoll, Brigitte; Jochum, Klaus Peter; Wever, Ron; Tremel, Wolfgang

2012-08-01

Marine biofouling--the colonization of small marine microorganisms on surfaces that are directly exposed to seawater, such as ships' hulls--is an expensive problem that is currently without an environmentally compatible solution. Biofouling leads to increased hydrodynamic drag, which, in turn, causes increased fuel consumption and greenhouse gas emissions. Tributyltin-free antifouling coatings and paints based on metal complexes or biocides have been shown to efficiently prevent marine biofouling. However, these materials can damage the environment through metal leaching (for example, of copper and zinc) and bacteria resistance. Here, we show that vanadium pentoxide nanowires act like naturally occurring vanadium haloperoxidases to prevent marine biofouling. In the presence of bromide ions and hydrogen peroxide, the nanowires catalyse the oxidation of bromide ions to hypobromous acid (HOBr). Singlet molecular oxygen (1O2) is formed and this exerts strong antibacterial activity, which prevents marine biofouling without being toxic to marine biota. Vanadium pentoxide nanowires have the potential to be an alternative approach to conventional anti-biofouling agents.

Rf-sputtered vanadium oxide thin films: effect of oxygen partial pressure on structural and electrochemical properties

CERN Document Server

Park, Y J; Ryu, K S; Chang, S H; Park, S C; Yoon, S M; Kim, D K

2001-01-01

Vanadium oxide thin films with thickness of about 2000 A have been prepared by radio frequency sputter deposition using a V sub 2 O sub 5 target in a mixed argon and oxygen atmosphere with different Ar/O sub 2 ratio ranging from 99/1 to 90/10. X-ray diffraction and X-ray absorption near edge structure spectroscopic studies show that the oxygen content higher than 5% crystallizes a stoichiometric V sub O sub 5 phase, while oxygen deficient phase is formed in the lower oxygen content. The oxygen content in the mixed Ar + O sub 2 has a significant influence on electrochemical lithium insertion/deinsertion property. The discharge-charge capacity of vanadium oxide film increases with increasing the reactive oxygen content. The V sub O sub 5 film deposited at the Ar/O sub 2 ratio of 90/10 exhibits high discharge capacity of 100 mu Ah/cm sup 2 -mu m along with good cycle performance.

Localized and collectivized behaviour of d-electrons in complicated titanium, vanadium and niobium oxides

International Nuclear Information System (INIS)

Bazuev, G.V.; Shvejkin, G.P.

1980-01-01

On the basis of investigation of electric and magnetic properties of oxide compounds of transition metals made are the conclusions on the degree of localization and delocalization of d-electrons in them. Generalized are the investigation results of complicated titanium, vanadium, niobium oxide compounds in low degrees of oxidation with rare earth and alkaline earth elements belonging to the two structural types: perovskite and pyrochlore. Presented are the results of investigations of perovskite-like solid solutions and of variable-content phases containing cations of transition metals in two different oxidation degrees: oxide niobium bronzes of two-valent europium and titanium bronzes of rare-earth elements, as well as Lnsub(1-x)Msub(x)Vsub(1-x)sup(3+)Vsub(x)sup(4+)Osub(3), where M is an alkaline earth element

Geochemistry of vanadium in an epigenetic, sandstone-hosted vanadium- uranium deposit, Henry Basin, Utah

Science.gov (United States)

Wanty, R.B.; Goldhaber, M.B.; Northrop, H.R.

1990-01-01

The epigenetic Tony M vanadium-uranium orebody in south-central Utah is hosted in fluvial sandstones of the Morrison Formation (Upper Jurassic). Measurements of the relative amounts of V+3 and V +4 in ore minerals show that V+3 is more abundant. Thermodynamic calculations show that vanadium was more likely transported to the site of mineralization as V+4. The ore formed as V+4 was reduced by hydrogen sulfide, followed by hydrolysis and precipitation of V+3 in oxide minerals or chlorite. Uranium was transported as uranyl ion (U+6), or some complex thereof, and reduced by hydrogen sulfide, forming coffinite. Detrital organic matter in the rocks served as the carbon source for sulfate-reducing bacteria. Vanadium most likely was derived from the dissolution of iron-titanium oxides. Uranium probably was derived from the overlying Brushy Basin Member of the Morrison Formation. Previous studies have shown that the ore formed at the density-stratified interface between a basinal brine and dilute meteoric water. The mineralization processes described above occurred within the mixing zone between these two fluids. -from Authors

Dielectric property study of poly(4-vinylphenol)-graphene oxide nanocomposite thin film

Science.gov (United States)

Roy, Dhrubojyoti

2018-05-01

Thin film capacitor device having a sandwich structure of indium tin oxide (ITO)-coated glass/polymer or polymer nanocomposite /silver has been fabricated and their dielectric and leakage current properties has been studied. The dielectric properties of the capacitors were characterized for frequencies ranging from 1 KHz to 1 MHz. 5 wt% Poly(4-vinylphenol)(PVPh)-Graphene (GO) nanocomposite exhibited an increase in dielectric constant to 5.6 and small rise in dielectric loss to around˜0.05 at 10 KHz w.r.t polymer. The DC conductivity measurements reveal rise of leakage current in nanocomposite.

Preparation of copper (I) oxide nanohexagon decorated reduced graphene oxide nanocomposite and its application in electrochemical sensing of dopamine

Energy Technology Data Exchange (ETDEWEB)

Sivasubramanian, R., E-mail: rss@psgias.ac.in; Biji, P.

2016-08-15

Highlights: • Cu{sub 2}O nanohexagon–reduced graphene oxide (rGO) nanocomposite has been prepared by in-situ reduction method. • The rGO-Cu{sub 2}O/GCE exhibited excellent catalytic properties for dopamine due to the synergistic action of the nanocomposite. • The proposed sensor is highly selective toward dopamine in the presence of ascorbic acid and uric acid. - Graphical Abstract: - Abstract: An electrochemical sensor using copper (I) oxide nanostructure decorated reduced graphene oxide (rGO) nanocomposite has been proposed for selective detection of dopamine. The rGO–Cu{sub 2}O nanocomposite was synthesized by in-situ chemical reduction method and was characterized using Transmission Electron Microscope (TEM), Energy Dispersive X-ray (EDX) analysis, X-ray Diffraction (XRD) patterns, Fourier Transform Infrared (FTIR), UV–vis and Raman Spectroscopy, respectively. From Cyclic Voltammetric (CV) studies, it was inferred that rGO–Cu{sub 2}O/GCE exhibits excellent electrocatalytic activity toward dopamine, which is attributed to the enhanced conductivity as well as the synergistic effect of the nanocomposite. The sensing was carried out using Differential Pulse Voltammetry (DPV) wherefrom a Limit of Detection (LOD) of 50 nM with a linear range from 10 µM to 900 µM was estimated. The effect of potential interfering agents such as Uric Acid (UA), Ascorbic Acid (AA), glucose, K{sup +}, Na{sup +}, Cl{sup −}, and SO{sub 4}{sup −} ions toward sensing were investigated. The performance of the sensor toward the estimation of dopamine in human blood and urine samples were analyzed. The facile method for the preparation of a nanocomposite in conjunction with the low detection limit and the wide linear range for dopamine sensing is the advantage of this present study.

Self-assembly of a tetrahedral 58-nuclear barium vanadium oxide cluster.

Science.gov (United States)

Kastner, Katharina; Puscher, Bianka; Streb, Carsten

2013-01-07

We report the synthesis and characterization of a molecular barium vanadium oxide cluster featuring high nuclearity and high symmetry. The tetrameric, 2.3 nm cluster H(5)[Ba(10)(NMP)(14)(H(2)O)(8)[V(12)O(33)](4)Br] is based on a bromide-centred, octahedral barium scaffold which is capped by four previously unknown [V(12)O(33)](6-) clusters in a tetrahedral fashion. The compound represents the largest polyoxovanadate-based heterometallic cluster known to date. The cluster is formed in organic solution and it is suggested that the bulky N-methyl-2-pyrrolidone (NMP) solvent ligands allow the isolation of this giant molecule and prevent further condensation to a solid-state metal oxide. The cluster is fully characterized using single-crystal XRD, elemental analysis, ESI mass spectrometry and other spectroscopic techniques.

Oxidation of vanadium metal in oxygen plasma and their characterizations

Science.gov (United States)

Sharma, Rabindar Kumar; Singh, Megha; Kumar, Prabhat; Reddy, G. B.

2015-09-01

In this report, the role of oxygen plasma on oxidation of vanadium (V) metal and the volatilization of its oxides has been studied as a function of source (V metal strip) temperature (Tss) and oxygen partial pressure (PO2). The presence of O2-plasma not only enhances the oxidation rate but also ficilitates in transport of oxide molecules from metal to substrate, as confirmed by the simultanous deposition of oxide film onto substrate. Both the oxidized metal strips and oxide films deposited on substrates are characterized separately. The structural and vibrational results evidence the presence of two different oxide phases (i.e. orthorhombic V2O5 and monocilinic V O2) in oxide layers formed on V metal strips, whereas the oxide films deposited on substrates exhibit only orthorhombic phase (i.e. V2O5). The decrease in peak intensities recorded from heated V metal strips on increasing Tss points out the increment in the rate of oxide volatilization, which also confirms by the oxide layer thickness measurements. The SEM results show the noticeable surface changes on V-strips as the function of Tss and PO2 and their optimum values are recorded to be 500 ˚ C and 7.5 × 10-2 Torr, respectively to deposit maximum thick oxide film on substrate. The formation of microcracks on oxidized V-strips, those responsible to countinue oxidation is also confirmed by SEM results. The compositional study of oxide layers formed on V-strips, corroborates their pureness and further assures about the existence of mixed oxide phases. The effect of oxygen partial pressure on oxidation of V-metal has also been discussed in the present report. All the results are well in agreement to each other.

Hybrid nanocomposite based on cellulose and tin oxide: growth, structure, tensile and electrical characteristics

International Nuclear Information System (INIS)

Mahadeva, Suresha K; Kim, Jaehwan

2011-01-01

A highly flexible nanocomposite was developed by coating a regenerated cellulose film with a thin layer of tin oxide (SnO 2 ) by liquid-phase deposition. Tin oxide was crystallized in solution and formed nanocrystal coatings on regenerated cellulose. The nanocrystalline layers did not exfoliate from cellulose. Transmission electron microscopy and energy dispersive x-ray spectroscopy suggest that SnO 2 was not only deposited over the cellulose surface, but also nucleated and grew inside the cellulose film. Current-voltage characteristics of the nanocomposite revealed that its electrical resistivity decreases with deposition time, with the lowest value obtained for 24 h of deposition. The cellulose-SnO 2 hybrid nanocomposite can be used for biodegradable and disposable chemical, humidity and biosensors.

Preparation, characterization, and antibacterial activity of silver nanoparticle-decorated graphene oxide nanocomposite.

Science.gov (United States)

Shao, Wei; Liu, Xiufeng; Min, Huihua; Dong, Guanghui; Feng, Qingyuan; Zuo, Songlin

2015-04-01

In this work, we report a facile and green approach to prepare a uniform silver nanoparticles (AgNPs) decorated graphene oxide (GO) nanocomposite (GO-Ag). The nanocomposite was fully characterized by transmission electron microscopy (TEM), Fourier transform infrared (FTIR) spectra, ultraviolet-visible (UV-vis) absorption spectra, and X-ray photoelectron spectroscopy (XPS), which demonstrated that AgNPs with a diameter of approximately 22 nm were uniformly and compactly deposited on GO. To investigate the silver ion release behaviors, HEPES buffers with different pH (5.5, 7, and 8.5) were selected and the mechanism of release actions was discussed in detail. The cytotoxicity of GO-Ag nanocomposite was also studied using HEK 293 cells. GO-Ag nanocomposite displayed good cytocompatibility. Furthermore, the antibacterial properties of GO-Ag nanocomposite were studied using Gram-negative E. coli ATCC 25922 and Gram-positive S. aureus ATCC 6538 by both the plate count method and disk diffusion method. The nanocomposite showed excellent antibacterial activity. These results demonstrated that GO-Ag nanocomposite, as a kind of antibacterial material, had a great promise for application in a wide range of biomedical applications.

Graphene Oxide/Poly(3-hexylthiophene) Nanocomposite Thin-Film Phototransistor for Logic Circuit Applications

Science.gov (United States)

Mansouri, S.; Coskun, B.; El Mir, L.; Al-Sehemi, Abdullah G.; Al-Ghamdi, Ahmed; Yakuphanoglu, F.

2018-04-01

Graphene is a sheet-structured material that lacks a forbidden band, being a good candidate for use in radiofrequency applications. We have elaborated graphene-oxide-doped poly(3-hexylthiophene) nanocomposite to increase the interlayer distance and thereby open a large bandgap for use in the field of logic circuits. Graphene oxide/poly(3-hexylthiophene) (GO/P3HT) nanocomposite thin-film transistors (TFTs) were fabricated on silicon oxide substrate by spin coating method. The current-voltage ( I- V) characteristics of TFTs with various P3HT compositions were studied in the dark and under light illumination. The photocurrent, charge carrier mobility, subthreshold voltage, density of interface states, density of occupied states, and I ON/ I OFF ratio of the devices strongly depended on the P3HT weight ratio in the composite. The effects of white-light illumination on the electrical parameters of the transistors were investigated. The results indicated that GO/P3HT nanocomposite thin-film transistors have high potential for use in radiofrequency applications, and their feasibility for use in digital applications has been demonstrated.

Ab Initio Calculations of Transport Properties of Vanadium Oxides

Science.gov (United States)

Lamsal, Chiranjivi; Ravindra, N. M.

2018-04-01

The temperature-dependent transport properties of vanadium oxides have been studied near the Fermi energy using the Kohn-Sham band structure approach combined with Boltzmann transport equations. V2O5 exhibits significant thermoelectric properties, which can be attributed to its layered structure and stability. Highly anisotropic electrical conduction in V2O5 is clearly manifested in the calculations. Due to specific details of the band structure and anisotropic electron-phonon interactions, maxima and crossovers are also seen in the temperature-dependent Seebeck coefficient of V2O5. During the phase transition of VO2, the Seebeck coefficient changes by 18.9 µV/K, which is close to (within 10% of) the observed discontinuity of 17.3 µV/K.

Elastomeric Nanocomposite Based on Exfoliated Graphene Oxide and Its Characteristics without Vulcanization

Directory of Open Access Journals (Sweden)

Nasser Abdullah Habib

2017-01-01

Full Text Available Rubber nanocomposites have emerged as one of the advanced materials in recent years. The aim of this work was to homogeneously disperse graphene oxide (GO sheets into Nitrile Butadiene Rubber (NBR and investigate the characteristics of GO/NBR nanocomposite without vulcanization. A suitable solvent was found to dissolve dry NBR while GO was exfoliated completely in an aqueous base solution using sonication. GO was dispersed into NBR at different loadings by solution mixing to produce unvulcanized GO/NBR nanocomposites. Scanning Electron Microscopy (SEM, Fourier-Transform Infrared Spectroscopy (FTIR, and X-Ray Diffraction (XRD were used to characterize the samples. Furthermore, mechanical and electrical properties of unvulcanized GO/NBR nanocomposites were carried out to determine the influence of GO on the NBR properties. The results showed that the modulus of GO/NBR nanocomposite at 1 wt% of GO was enhanced by about 238% compared with unfilled NBR. These results provide insight into the properties of unvulcanized GO/NBR nanocomposite for application as coatings or adhesives.

Nickel Oxide and Nickel Co-doped Graphitic Carbon Nitride Nanocomposites and its Octylphenol Sensing Application

KAUST Repository

Gong, Wanyun; Zou, Jing; Zhang, Sheng; Zhou, Xin; Jiang, Jizhou

2015-01-01

Nickel oxide and nickel co-doped graphitic carbon nitride (NiO-Ni-GCN) nanocomposites were successfully prepared by thermal treatment of melamine and NiCl2 6H2O. NiO-Ni-GCN nanocomposites showed superior electrochemical catalytic activity for the oxidation of octylphenol to pure GCN. A detection method of octylphenol in environmental water samples was developed based at NiO-Ni-GCN nanocomposites modified electrode under infrared light irradiation. Differential pulse voltammetry was used as the analytic technique of octylphenol, exhibiting stable and specific concentration-dependent oxidation signal in the presence of octylphenol in the range of 10nM to 1μM and 1μM to 50μM, with a detection limit of 3.3nM (3S/N). © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Nickel Oxide and Nickel Co-doped Graphitic Carbon Nitride Nanocomposites and its Octylphenol Sensing Application

KAUST Repository

Gong, Wanyun

2015-11-16

Nickel oxide and nickel co-doped graphitic carbon nitride (NiO-Ni-GCN) nanocomposites were successfully prepared by thermal treatment of melamine and NiCl2 6H2O. NiO-Ni-GCN nanocomposites showed superior electrochemical catalytic activity for the oxidation of octylphenol to pure GCN. A detection method of octylphenol in environmental water samples was developed based at NiO-Ni-GCN nanocomposites modified electrode under infrared light irradiation. Differential pulse voltammetry was used as the analytic technique of octylphenol, exhibiting stable and specific concentration-dependent oxidation signal in the presence of octylphenol in the range of 10nM to 1μM and 1μM to 50μM, with a detection limit of 3.3nM (3S/N). © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Superior Photocatalytic Performance of CeO₂ Nanoparticles and Reduced Graphene Oxide Nanocomposite Prepared by Low Cost Co-Precipitation Method.

Science.gov (United States)

Jayanthi, Mani; Lavanya, Thirugnanam; Saradha, Nagarajan Anbil; Satheesh, Kaveri; Chenthamarai, SriRangarajan; Jayavel, Ramasamy

2018-05-01

In this article, cerium oxide nanoparticles (CeO2 NPs) and reduced graphene oxide nanocomposite have been fabricated through simple, easy and cost effective co-precipitation method. The structural, optical and morphological characterization provides the evidence of successful synthesis of CeO2 NPs and nanocomposite. X-ray photoelectron spectroscopic characterization provides useful information about the concentrations and proportions of Ce3+ and Ce4+ ions in nanoparticles as well as in nanocomposite. These studies provide an insight to understand enhanced photocatalytic activity of nanocomposite. The nanocomposite produces 81% photocatalytic degradation of methyl orange compared to only 45% degradation by CeO2 NPs alone.

Reduced Graphene Oxide/Au Nanocomposite for NO2 Sensing at Low Operating Temperature

Directory of Open Access Journals (Sweden)

Hao Zhang

2016-07-01

Full Text Available A reduced grapheme oxide (rGO/Au hybrid nanocomposite has been synthesized by hydrothermal treatment using graphite and HAuCl4 as the precursors. Characterization, including X-ray diffraction (XRD, Raman spectra, X-ray photoelecton spectroscopy (XPS and transmission electron microscopy (TEM, indicates the formation of rGO/Au. A gas sensor fabricated with rGO/Au nanocomposite was applied for NO2 detection at 50 °C. Compared with pure rGO, rGO/Au nanocomposite exhibits higher sensitivity, a more rapid response–recovery process and excellent reproducibility.

Vanadium recycling in the United States in 2004

Science.gov (United States)

Goonan, Thomas G.

2011-01-01

As one of a series of reports that describe the recycling of metal commodities in the United States, this report discusses the flow of vanadium in the U.S. economy in 2004. This report includes a description of vanadium supply and demand in the United States and illustrates the extent of vanadium recycling and recycling trends. In 2004, apparent vanadium consumption, by end use, in the United States was 3,820 metric tons (t) in steelmaking and 232 t in manufacturing, of which 17 t was for the production of superalloys and 215 t was for the production of other alloys, cast iron, catalysts, and chemicals. Vanadium use in steel is almost entirely dissipative because recovery of vanadium from steel scrap is chemically impeded under the oxidizing conditions in steelmaking furnaces. The greatest amount of vanadium recycling is in the superalloy, other-alloy, and catalyst sectors of the vanadium market. Vanadium-bearing catalysts are associated with hydrocarbon recovery and refining in the oil industry. In 2004, 2,850 t of vanadium contained in alloy scrap and spent catalysts was recycled, which amounted to about 44 percent of U.S. domestic production. About 94 percent of vanadium use in the United States was dissipative (3,820 t in steel/4,050 t in steel+fabricated products).

Synthesis and characterization of nanocomposite powders of calcium phosphate/titanium oxide for biomedical applications

Energy Technology Data Exchange (ETDEWEB)

Delima, S.A.; Camargo, N.H.A.; Souza, J.C.P.; Gemelli, E., E-mail: sarahamindelima@hotmail.com, E-mail: dem2nhac@joinville.udesc.br, E-mail: souzajulio@joinville.udesc.br, E-mail: gemelli@joinville.udesc.br [Universidade do Estado de Santa Catarina (UDESC), Joinville, SC (Brazil). Centro de Ciencias Tecnologicas

2009-07-01

The nanostructured bioceramics of calcium phosphate are current themes of research and they are becoming important as bone matrix in regeneration of tissues in orthopedic and dental applications. Nanocomposite powders of calcium phosphate, reinforced with nanometric particles of titanium oxide, silica oxide and alumina oxid ealpha, are being widely studied because they offer new microstructures, nanostructures and interconnected microporosity with high superficial area of micropores that contribute to osteointegration and osteoinduction processes. This study is about the synthesis of nanocomposites powders of calcium phosphate reinforced with 1%, 2%, 3% and 5% in volume of titanium oxide and its characterization through the techniques of X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Differential Thermal Analysis (DTA), Thermogravimetry (TG) and Dilatometry. (author)

Synthesis and characterization of nanocomposite powders of calcium phosphate/titanium oxide for biomedical applications

International Nuclear Information System (INIS)

Delima, S.A.; Camargo, N.H.A.; Souza, J.C.P.; Gemelli, E.

2009-01-01

The nanostructured bioceramics of calcium phosphate are current themes of research and they are becoming important as bone matrix in regeneration of tissues in orthopedic and dental applications. Nanocomposite powders of calcium phosphate, reinforced with nanometric particles of titanium oxide, silica oxide and alumina oxid ealpha, are being widely studied because they offer new microstructures, nanostructures and interconnected microporosity with high superficial area of micropores that contribute to osteointegration and osteoinduction processes. This study is about the synthesis of nanocomposites powders of calcium phosphate reinforced with 1%, 2%, 3% and 5% in volume of titanium oxide and its characterization through the techniques of X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Differential Thermal Analysis (DTA), Thermogravimetry (TG) and Dilatometry. (author)

A metallic metal oxide (Ti5O9)-metal oxide (TiO2) nanocomposite as the heterojunction to enhance visible-light photocatalytic activity.

Science.gov (United States)

Li, L H; Deng, Z X; Xiao, J X; Yang, G W

2015-01-26

Coupling titanium dioxide (TiO2) with other semiconductors is a popular method to extend the optical response range of TiO2 and improve its photon quantum efficiency, as coupled semiconductors can increase the separation rate of photoinduced charge carriers in photocatalysts. Differing from normal semiconductors, metallic oxides have no energy gap separating occupied and unoccupied levels, but they can excite electrons between bands to create a high carrier mobility to facilitate kinetic charge separation. Here, we propose the first metallic metal oxide-metal oxide (Ti5O9-TiO2) nanocomposite as a heterojunction for enhancing the visible-light photocatalytic activity of TiO2 nanoparticles and we demonstrate that this hybridized TiO2-Ti5O9 nanostructure possesses an excellent visible-light photocatalytic performance in the process of photodegrading dyes. The TiO2-Ti5O9 nanocomposites are synthesized in one step using laser ablation in liquid under ambient conditions. The as-synthesized nanocomposites show strong visible-light absorption in the range of 300-800 nm and high visible-light photocatalytic activity in the oxidation of rhodamine B. They also exhibit excellent cycling stability in the photodegrading process. A working mechanism for the metallic metal oxide-metal oxide nanocomposite in the visible-light photocatalytic process is proposed based on first-principle calculations of Ti5O9. This study suggests that metallic metal oxides can be regarded as partners for metal oxide photocatalysts in the construction of heterojunctions to improve photocatalytic activity.

Sonication-Induced Modification of Carbon Nanotubes: Effect on the Rheological and Thermo-Oxidative Behaviour of Polymer-Based Nanocomposites.

Science.gov (United States)

Arrigo, Rossella; Teresi, Rosalia; Gambarotti, Cristian; Parisi, Filippo; Lazzara, Giuseppe; Dintcheva, Nadka Tzankova

2018-03-05

The aim of this work is the investigation of the effect of ultrasound treatment on the structural characteristics of carbon nanotubes (CNTs) and the consequent influence that the shortening induced by sonication exerts on the morphology, rheological behaviour and thermo-oxidative resistance of ultra-high molecular weight polyethylene (UHMWPE)-based nanocomposites. First, CNTs have been subjected to sonication for different time intervals and the performed spectroscopic and morphological analyses reveal that a dramatic decrease of the CNT's original length occurs with increased sonication time. The reduction of the initial length of CNTs strongly affects the nanocomposite rheological behaviour, which progressively changes from solid-like to liquid-like as the CNT sonication time increases. The study of the thermo-oxidative behaviour of the investigated nanocomposites reveals that the CNT sonication has a detrimental effect on the thermo-oxidative stability of nanocomposites, especially for long exposure times. The worsening of the thermo-oxidative resistance of sonicated CNT-containing nanocomposites could be attributed to the lower thermal conductivity of low-aspect-ratio CNTs, which causes the increase of the local temperature at the polymer/nanofillers interphase, with the consequent acceleration of the degradative phenomena.

Sonication-Induced Modification of Carbon Nanotubes: Effect on the Rheological and Thermo-Oxidative Behaviour of Polymer-Based Nanocomposites

Science.gov (United States)

Teresi, Rosalia; Gambarotti, Cristian; Dintcheva, Nadka Tzankova

2018-01-01

The aim of this work is the investigation of the effect of ultrasound treatment on the structural characteristics of carbon nanotubes (CNTs) and the consequent influence that the shortening induced by sonication exerts on the morphology, rheological behaviour and thermo-oxidative resistance of ultra-high molecular weight polyethylene (UHMWPE)-based nanocomposites. First, CNTs have been subjected to sonication for different time intervals and the performed spectroscopic and morphological analyses reveal that a dramatic decrease of the CNT’s original length occurs with increased sonication time. The reduction of the initial length of CNTs strongly affects the nanocomposite rheological behaviour, which progressively changes from solid-like to liquid-like as the CNT sonication time increases. The study of the thermo-oxidative behaviour of the investigated nanocomposites reveals that the CNT sonication has a detrimental effect on the thermo-oxidative stability of nanocomposites, especially for long exposure times. The worsening of the thermo-oxidative resistance of sonicated CNT-containing nanocomposites could be attributed to the lower thermal conductivity of low-aspect-ratio CNTs, which causes the increase of the local temperature at the polymer/nanofillers interphase, with the consequent acceleration of the degradative phenomena. PMID:29510595

Vanadium-substituted heteropolyacids immobilized on amine- functionalized mesoporous MCM-41: A recyclable catalyst for selective oxidation of alcohols with H2O2

International Nuclear Information System (INIS)

Dong, Xinbo; Wang, Danjun; Li, Kebin; Zhen, Yanzhong; Hu, Huaiming; Xue, Ganglin

2014-01-01

Graphical abstract: Vanadium-substituted phosphotungstic acids are immobilized on amine- functionalized mesoporous MCM-41 and the hybrid catalyst is proved to be a highly efficient solid catalyst for the oxidation of aromatic alcohols to the corresponding carbonyl compounds with H 2 O 2 , featured by the high conversion and selectivity, easy recovery, and quite steady reuse. - Highlights: • Vanadium-substituted phosphotungstic acid immobilized on amine-functionalized mesoporous MCM-41 are prepared. • HPAs were fixed on the inner surface of mesoporous MCM-41 by chemical bonding to aminosilane groups. • The hybrid catalyst showed much higher catalytic activity than the pure HPAs. • The hybrid catalyst is a highly efficient recyclable solid catalyst for the selective oxidation of aromatic alcohols. - Abstract: New hybrid materials of vanadium-substituted phosphotungstic acids (VHPW) immobilized on amine-functionalized mesoporous MCM-41 (VHPW/MCM-41/NH 2 ) are prepared and characterized by FT-IR, XRD, N 2 adsorption, elemental analysis, SEM and TEM for their structural integrity and physicochemical properties. It is found that the structure of the heteropolyacids is retained upon immobilization over mesoporous materials. The catalytic activities of these hybrid materials are tested in the selective oxidation of alcohols to the carbonyl products with 30% aqueous H 2 O 2 as oxidant in toluene. The catalytic activities of different number of vanadium-substituted phosphotungstic acid are investigated, and among the catalysts, H 5 [PV 2 W 10 O 40 ] immobilized on amine-functionalized MCM-41 exhibits the highest activity with 97% conversion and 99% selectivity in the oxidation of benzyl alcohol to benzaldehyde. The hybrid catalyst is proved to be a highly efficient recyclable solid catalyst for the selective oxidation of aromatic alcohols to the corresponding aldehydes with H 2 O 2

Chitosan-iron oxide nanocomposite based electrochemical aptasensor for determination of malathion

Energy Technology Data Exchange (ETDEWEB)

Prabhakar, Nirmal, E-mail: nirmalprabhakar@gmail.com; Thakur, Himkusha; Bharti, Anu; Kaur, Navpreet

2016-10-05

An electrochemical aptasensor based on chitosan-iron oxide nanocomposite (CHIT-IO) film deposited on fluorine tin Oxide (FTO) was developed for the detection of malathion. Iron oxide nanoparticles were prepared by co-precipitation method and characterized by Transmission electron microscopy and UV–Visible spectroscopy. The biotinylated DNA aptamer sequence specific to the malathion was immobilized onto the iron oxide doped-chitosan/FTO electrode by using streptavidin as linking molecule. Various characterization studies like Field Emission-Scanning Electron Microscopy (FE-SEM), Fourier Transform Infrared Spectroscopy (FT-IR), and Electrochemical studies were performed to attest the successful fabrication of bioelectrodes. Experimental parameters like aptamer concentration, response time, stability of electrode and reusability studies were optimized. Aptamer immobilized chitosan-iron oxide nanocomposite (APT/SA/CHIT-IO/FTO) bioelectrodes exhibited LOD of about 0.001 ng/mL within 15 min and spike-in studies revealed about 80–92% recovery of malathion from the lettuce leaves and soil sample. - Highlights: • An electrochemical aptasensor for the detection of Malathion has been developed. • Chitosan-iron oxide NP deposited FTO sheets provides platform for aptamer immobilization. • Aptasensor has efficiency to detect malathion upto 0.001 ng/mL within 15 min.

Surface acoustic wave sensors with Graphene/PANI nanocomposites for nitric oxide detection

Science.gov (United States)

Wang, Beibei; Zheng, Lei; Zhou, Lingling

2017-12-01

Surface acoustic wave sensors with grapheme/PANI nanocomposite sensitive films for detecting nitric oxide (NO) were fabricated and experimentally studied. Morphological characterization and functionalization of the sensing material were explored using SEM and FTIR, respectively. The study of sensor response compared film sensitivity, response time, reversibility, and limit of detection for nanocomposite films, pure grapheme and pure PANI to the detection of NO. The response and recovery times were 40s and 20s when detecting 4ppm NO, respectively. The frequency response was discovered to be linear in the NO concentration range 1-50 ppm. The nanocomposite sensors had improved sensitivities compared to the polymer devices, and better response times.

Fabrication of ammonium perchlorate/copper-chromium oxides core-shell nanocomposites for catalytic thermal decomposition of ammonium perchlorate

Energy Technology Data Exchange (ETDEWEB)

Eslami, Abbas, E-mail: eslami@umz.ac.ir [Department of Inorganic Chemistry, Faculty of Chemistry, University of Mazandaran, P.O.Box 47416-95447, Babolsar (Iran, Islamic Republic of); Juibari, Nafise Modanlou [Department of Inorganic Chemistry, Faculty of Chemistry, University of Mazandaran, P.O.Box 47416-95447, Babolsar (Iran, Islamic Republic of); Hosseini, Seyed Ghorban [Department of Chemistry, Malek Ashtar University of Technology, P.O. Box 16765-3454, Tehran (Iran, Islamic Republic of)

2016-09-15

The ammonium perchlorate/Cu(II)-Cr(III)-oxides(AP/Cu-Cr-O) core-shell nanocomposites were in-situ prepared by deposition of copper and chromium oxides on suspended ammonium perchlorate particles in ethyl acetate as solvent. The results of differential scanning calorimetery (DSC) and thermal gravimetric analysis (TGA) experiments showed that the nanocomposites have excellent catalytic effect on the thermal decomposition of AP, so that the released heat increases up to about 3-fold over initial values, changing from 450 J/g for pure AP to 1510 J/g for most appropriate mixture. For better comparison, single metal oxide/AP core-shell nanocomposite have also been prepared and the results showed that they have less catalytic effect respect to mixed metal oxides system. Scanning electron microscopy (SEM) results revealed homogenous deposition of nanoparticles on the surface of AP and fabrication of core-shell structures. The kinetic parameters of thermal decomposition of both pure AP and AP/Cu-Cr-O samples have been calculated by Kissinger method and the results showed that the values of pre-exponential factor and activation energy are higher for AP/Cu-Cr-O nanocomposite. The better catalytic effect of Cu-Cr-O nanocomposites is probably attributed to the synergistic effect between Cu{sup 2+} and Cr{sup 3+} in the nanocomposites, smaller particle size and more crystal defect. - Highlights: • The Cu-Cr-O nanoparticles were synthesized by chemical liquid deposition method. • Then, the AP/Cu-Cr-O core-shell nanocomposites were prepared. • The core-shell samples showed high catalytic activity for AP decomposition. • Thermal decomposition of samples occurs at lower temperature range.

Silver Nanoparticles-graphene Oxide Nanocomposite for Antibacterial Purpose

International Nuclear Information System (INIS)

Chook, S.W.; Chia, C.H.; Sarani Zakaria; Mohd Khan Ayob; Chee, K.L.; Neoh, H.M.; Huang, N.M.

2011-01-01

Graphene oxide (GO) sheets, a single layer of carbon atoms which can be served as substrates for fabricating metallic nanoparticles-GO nano composites, have been used in this study The nanocomposite of silver nanoparticles and graphene oxide were produced via in-situ synthesis and with the aid of chitosan to investigate the formation of silver nanoparticles on the graphene oxide sheets. XRD and UV-Vis studies confirmed the formation of silver nanoparticles on GO sheets, while TEM and FESEM images presented the loading of silver nanoparticles on the GO sheets. The degree of loading and distribution of the silver nanoparticles on the graphene oxide were depended on the procedure during the formation of silver nanoparticles. The nano composites can be potentially used in food packaging and biomedical applications. (author)

Novel porous graphene oxide and hydroxyapatite nanosheets-reinforced sodium alginate hybrid nanocomposites for medical applications

International Nuclear Information System (INIS)

Xiong, Guangyao; Luo, Honglin; Zuo, Guifu; Ren, Kaijing; Wan, Yizao

2015-01-01

Graphene oxide (GO) and hydroxyapatite (HAp) are frequently used as reinforcements in polymers to improve mechanical and biological properties. In this work, novel porous hybrid nanocomposites consisting of GO, HAp, and sodium alginate (SA) have been prepared by facile solution mixing and freeze drying in an attempt to obtain a scaffold with desirable mechanical and biological properties. The as-prepared porous GO/HAp/SA hybrid nanocomposites were characterized by SEM, XRD, FTIR, TGA, and mechanical testing. In addition, preliminary cell behavior was assessed by CCK8 assay. It is found that the GO/HAp/SA nanocomposites show improved compressive strength and modulus over neat SA and HAp/SA nanocomposites. CCK8 results reveal that the GO/HAp/SA nanocomposites show enhanced cell proliferation over neat SA and GO/SA nanocomposite. It has been demonstrated that GO/HAp20/SA holds promise in bone tissue engineering. - Graphical abstract: Display Omitted - Highlights: • Graphene oxide (GO), hydroxyapatite (HAp), and alginate (SA) nanocomposites were fabricated. • The novel porous composites were prepared by solution mixture and freeze drying. • The GO/HAp/SA had porous structure with porosity > 85% and pore size > 150 μm. • The GO/HAp/SA exhibited improved mechanical properties over HAp/SA counterparts. • The GO/HAp/SA showed enhanced cell proliferation over GO/SA counterparts

Novel porous graphene oxide and hydroxyapatite nanosheets-reinforced sodium alginate hybrid nanocomposites for medical applications

Energy Technology Data Exchange (ETDEWEB)

Xiong, Guangyao [School of Mechanical and Electrical Engineering, East China Jiaotong University, Nanchang 330013 (China); Luo, Honglin [Research Institute of Biomaterials and Transportation, East China Jiaotong University, Nanchang 330013 (China); School of Materials Science and Engineering, Tianjin Key Laboratory of Composite and Functional Materials, Key Laboratory of Advanced Ceramics and Machining Technology, Ministry of Education, Tianjin University, Tianjin 300072 (China); Zuo, Guifu [Hebei Provincial Key Laboratory of Inorganic Nonmetallic Materials, College of Materials Science and Engineering, Hebei United University, Tangshan 063009 (China); Ren, Kaijing [Department of Joint Surgery, Tianjin Hospital, Tianjin 300211 (China); Wan, Yizao, E-mail: yzwantju@126.com [Research Institute of Biomaterials and Transportation, East China Jiaotong University, Nanchang 330013 (China); School of Materials Science and Engineering, Tianjin Key Laboratory of Composite and Functional Materials, Key Laboratory of Advanced Ceramics and Machining Technology, Ministry of Education, Tianjin University, Tianjin 300072 (China)

2015-09-15

Graphene oxide (GO) and hydroxyapatite (HAp) are frequently used as reinforcements in polymers to improve mechanical and biological properties. In this work, novel porous hybrid nanocomposites consisting of GO, HAp, and sodium alginate (SA) have been prepared by facile solution mixing and freeze drying in an attempt to obtain a scaffold with desirable mechanical and biological properties. The as-prepared porous GO/HAp/SA hybrid nanocomposites were characterized by SEM, XRD, FTIR, TGA, and mechanical testing. In addition, preliminary cell behavior was assessed by CCK8 assay. It is found that the GO/HAp/SA nanocomposites show improved compressive strength and modulus over neat SA and HAp/SA nanocomposites. CCK8 results reveal that the GO/HAp/SA nanocomposites show enhanced cell proliferation over neat SA and GO/SA nanocomposite. It has been demonstrated that GO/HAp20/SA holds promise in bone tissue engineering. - Graphical abstract: Display Omitted - Highlights: • Graphene oxide (GO), hydroxyapatite (HAp), and alginate (SA) nanocomposites were fabricated. • The novel porous composites were prepared by solution mixture and freeze drying. • The GO/HAp/SA had porous structure with porosity > 85% and pore size > 150 μm. • The GO/HAp/SA exhibited improved mechanical properties over HAp/SA counterparts. • The GO/HAp/SA showed enhanced cell proliferation over GO/SA counterparts.

Ecological approach to graphene oxide reinforced poly (methyl methacrylate) nanocomposites.

Science.gov (United States)

Morimune, Seira; Nishino, Takashi; Goto, Takuya

2012-07-25

Graphene oxide (GO) possesses the desirable characteristic of aqueous solution processability attributed to the oxygen-containing functional groups on the basal planes and edges of graphene. To provide an alternative to conventional procedures for fabricating poly (methyl methacrylate) (PMMA)/GO nanocomposites, which use organic solutions and/or surfactants, we have developed an environmentally friendly technique in which PMMA is polymerized by soap-free emulsion polymerization and incorporated with GO using water as a processing medium. Experimental results showed that the fabricated PMMA/GO nanocomposites had excellent mechanical, thermal, and O2 barrier properties with the nanodispersion of GO.

Bioinspired, Ultrastrong, Highly Biocompatible, and Bioactive Natural Polymer/Graphene Oxide Nanocomposite Films.

Science.gov (United States)

Zhu, Wen-Kun; Cong, Huai-Ping; Yao, Hong-Bin; Mao, Li-Bo; Asiri, Abdullah M; Alamry, Khalid A; Marwani, Hadi M; Yu, Shu-Hong

2015-09-09

Tough and biocompatible nanocomposite films: A new type of bioinspired ultrastrong, highly biocompatible, and bioactive konjac glucomannan (KGM)/graphene oxide (GO) nanocomposite film is fabricated on a large scale by a simple solution-casting method. Such KGM-GO composite films exhibit much enhanced mechanical properties under the strong hydrogen-bonding interactions, showing great potential in the fields of tissue engineering and food package. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Morphology, thermal, mechanical, and barrier properties of graphene oxide/poly(lactic acid) nanocomposite films

International Nuclear Information System (INIS)

Kim, Seong Woo; Choi, Hyun Muk

2016-01-01

To improve the physical and gas barrier properties of biodegradable poly(lactic acid) (PLA) film, two graphene nanosheets of highly functionalized graphene oxide (0.3 wt% to 0.7 wt%) and low-functionalized graphene oxide (0.5 wt%) were incorporated into PLA resin via solution blending method. Subsequently, we investigated the effects of material parameters such as loading level and degree of functionalization for the graphene nanosheets on the morphology and properties of the resultant nanocomposites. The highly functionalized graphene oxide (GO) caused more exfoliation and homogeneous dispersion in PLA matrix as well as more sustainable suspensions in THF, compared to low-functionalized graphene oxide (LFGO). When loaded with GO from 0.3 wt% to 0.7 wt%, the glass transition temperature, degree of crystallinity, tensile strength and modulus increased steadily. The GO gave rise to more pronounced effect in the thermal and mechanical reinforcement, relative to LFGO. In addition, the preparation of fairly transparent PLA-based nanocomposite film with noticeably improved barrier performance achieved only when incorporated with GO up to 0.7wt%. As a result, GO may be more compatible with hydrophilic PLA resin, compared to LFGO, resulting in more prominent enhancement of nanocomposites properties.

Poly(vinyl alcohol)/poly(acrylic acid)/TiO2/graphene oxide nanocomposite hydrogels for pH-sensitive photocatalytic degradation of organic pollutants

International Nuclear Information System (INIS)

Moon, Young-E; Jung, Gowun; Yun, Jumi; Kim, Hyung-Il

2013-01-01

Graphical abstract: The photocatalytic removal of pollutants was improved by the two-step mechanism based on the adsorption of pollutants by hydrogel and the effective decomposition by combination of TiO 2 and graphene oxide. -- Highlights: • pH sensitive PVA/PAAc hydrogels were prepared by radical polymerization and condensation reaction. • PVA/PAAc/TiO 2 /graphene oxide nanocomposite hydrogels were used for treatment of basic waste water. • Photocatalytic acitivity of TiO 2 was improved by incorporation of graphene oxide. • Photocatalytic decomposition by nanocomposite hydrogel was improved by increasing pH. -- Abstract: Poly(vinyl alcohol)/poly(acrylic acid)/TiO 2 /graphene oxide nanocomposite hydrogels were prepared using radical polymerization and condensation reaction for the photocatalytic treatment of waste water. Graphene oxide was used as an additive to improve the photocatalytic activity of poly(vinyl alcohol)/poly(acrylic acid)/TiO 2 nanocomposite hydrogels. Both TiO 2 and graphene oxide were immobilized in poly(vinyl alcohol)/poly(acrylic acid) hydrogel matrix for an easier recovery after the waste water treatment. The photocatalytic activity of poly(vinyl alcohol)/poly(acrylic acid)/TiO 2 /graphene oxide nanocomposite hydrogels was evaluated on the base of the degradation of pollutants by using UV spectrometer. The improved removal of pollutants was due to the two-step mechanism based on the adsorption of pollutants by nanocomposite hydrogel and the effective decomposition of pollutants by TiO 2 and graphene oxide. The highest swelling of nanocomposite hydrogel was observed at pH 10 indicating that poly(vinyl alcohol)/poly(acrylic acid)/TiO 2 /graphene oxide nanocomposite hydrogels were suitable as a promising system for the treatment of basic waste water

Synthesis of Polyaniline-Coated Graphene Oxide@SrTiO3 Nanocube Nanocomposites for Enhanced Removal of Carcinogenic Dyes from Aqueous Solution

Directory of Open Access Journals (Sweden)

Syed Shahabuddin

2016-09-01

Full Text Available The present investigation highlights the synthesis of polyaniline (PANI-coated graphene oxide doped with SrTiO3 nanocube nanocomposites through facile in situ oxidative polymerization method for the efficient removal of carcinogenic dyes, namely, the cationic dye methylene blue (MB and the anionic dye methyl orange (MO. The presence of oxygenated functional groups comprised of hydroxyl and epoxy groups in graphene oxide (GO and nitrogen-containing functionalities such as imine groups and amine groups in polyaniline work synergistically to impart cationic and anionic nature to the synthesised nanocomposite, whereas SrTiO3 nanocubes act as spacers aiding in segregation of GO sheets, thereby increasing the effective surface area of nanocomposite. The synthesised nanocomposites were characterised by field emission scanning electron microscopy (FESEM, transmission electron microscopy (TEM, thermogravimetric analysis (TGA, X-ray diffraction (XRD, and Fourier transform infrared spectroscopy (FTIR. The adsorption efficiencies of graphene oxide (GO, PANI homopolymer, and SrTiO3 nanocubes-doped nanocomposites were assessed by monitoring the adsorption of methylene blue and methyl orange dyes from aqueous solution. The adsorption efficiency of nanocomposites doped with SrTiO3 nanocubes were found to be of higher magnitude as compared with undoped nanocomposite. Moreover, the nanocomposite with 2 wt % SrTiO3 with respect to graphene oxide demonstrated excellent adsorption behaviour with 99% and 91% removal of MB and MO, respectively, in a very short duration of time.

Effect of vanadium compounds on acid phosphatase activity.

Science.gov (United States)

Vescina, C M; Sálice, V C; Cortizo, A M; Etcheverry, S B

1996-01-01

The direct effect of different vanadium compounds on acid phosphatase (ACP) activity was investigated. Vanadate and vanadyl but not pervanadate inhibited the wheat germ ACP activity. These vanadium derivatives did not alter the fibroblast Swiss 3T3 soluble fraction ACP activity. Using inhibitors of tyrosine phosphatases (PTPases), the wheat germ ACP was partially characterized as a PTPase. This study suggests that the inhibitory ability of different vanadium derivatives to modulate ACP activity seems to depend on the geometry around the vanadium atom more than on the oxidation state. Our results indicate a correlation between the PTPase activity and the sensitivity to vanadate and vanadyl cation.

Design of Magnetic Gelatine/Silica Nanocomposites by Nanoemulsification: Encapsulation versus in Situ Growth of Iron Oxide Colloids

Directory of Open Access Journals (Sweden)

Joachim Allouche

2014-07-01

Full Text Available The design of magnetic nanoparticles by incorporation of iron oxide colloids within gelatine/silica hybrid nanoparticles has been performed for the first time through a nanoemulsion route using the encapsulation of pre-formed magnetite nanocrystals and the in situ precipitation of ferrous/ferric ions. The first method leads to bi-continuous hybrid nanocomposites containing a limited amount of well-dispersed magnetite colloids. In contrast, the second approach allows the formation of gelatine-silica core-shell nanostructures incorporating larger amounts of agglomerated iron oxide colloids. Both magnetic nanocomposites exhibit similar superparamagnetic behaviors. Whereas nanocomposites obtained via an in situ approach show a strong tendency to aggregate in solution, the encapsulation route allows further surface modification of the magnetic nanocomposites, leading to quaternary gold/iron oxide/silica/gelatine nanoparticles. Hence, such a first-time rational combination of nano-emulsion, nanocrystallization and sol-gel chemistry allows the elaboration of multi-component functional nanomaterials. This constitutes a step forward in the design of more complex bio-nanoplatforms.

Understanding the adsorptive and photoactivity properties of Ag-graphene oxide nanocomposites.

Science.gov (United States)

Martínez-Orozco, R D; Rosu, H C; Lee, Soo-Wohn; Rodríguez-González, V

2013-12-15

Nanocomposites of graphene oxide (GO) and silver nanoparticles (AgNPs) were synthetized using a practical photochemical silver functionalization. Their photocatalytic activities were evaluated with two dyes, Rhodamine B and Indigo Carmine, under visible-light irradiation. The prepared nanocomposites were characterized by HRTEM, FESEM, XRD, Raman, FTIR and UV-vis absorption spectroscopy. These nanocomposites present new defect domains of sp(3) type in combination with several graphitic functional groups that act as nucleation sites for anchoring AgNPs, while the sp(2)-sp(3) edge defects domains of GO generate the photoactivity. Furthermore, their photocatalytic performances are governed by their large adsorption capacity, and strong interaction with dye chromophores. A comprehensive photocatalytic way underlying the importance of adsorption is suggested to explain the low visible-light responsive photoactivity of the AgNPs-GO nanocomposites and the possible binding-site saturation. Then, the usage of H2SO4 allows the production of ionic species and helps to confirm the strong adsorption of both dyes. The ability to synthesize AgNPs-GO nanocomposites with extensive adsorptive capacity is certainly of interest for the efficient removal of hazardous materials. Copyright © 2013 Elsevier B.V. All rights reserved.

An extraction process to recover vanadium from low-grade vanadium-bearing titanomagnetite

Energy Technology Data Exchange (ETDEWEB)

Chen, Desheng; Zhao, Hongxin; Hu, Guoping [National Engineering Laboratory for Hydrometallurgical Cleaner Production Technology, Beijing 100190 (China); Key Laboratory of Green Process and Engineering, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190 (China); Qi, Tao, E-mail: tqgreen@ipe.ac.cn [National Engineering Laboratory for Hydrometallurgical Cleaner Production Technology, Beijing 100190 (China); Key Laboratory of Green Process and Engineering, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190 (China); Yu, Hongdong; Zhang, Guozhi [National Engineering Laboratory for Hydrometallurgical Cleaner Production Technology, Beijing 100190 (China); Key Laboratory of Green Process and Engineering, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190 (China); Wang, Lina, E-mail: linawang@ipe.ac.cn [National Engineering Laboratory for Hydrometallurgical Cleaner Production Technology, Beijing 100190 (China); Key Laboratory of Green Process and Engineering, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190 (China); Wang, Weijing [National Engineering Laboratory for Hydrometallurgical Cleaner Production Technology, Beijing 100190 (China); Key Laboratory of Green Process and Engineering, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190 (China)

2015-08-30

Highlights: • The leaching solution contains high concentration of acid, iron, impurities and lower vanadium. • 99.4% of vanadium and 4.2% of iron were extracted by three-stage extraction process. • 99.6% of vanadium and 5.4% of iron were stripped by three-stage stripping process. • The stripping solution contains 40.16 g/L V{sub 2}O{sub 5}, 0.691 g/L Fe, 0.007 g/L TiO{sub 2} and 0.247 g/L CaO. • The vanadium product of V{sub 2}O{sub 5} with purity of 99.12%, 0.026% Fe and well crystallized. - Abstract: An extraction process to recover vanadium from low-grade vanadium-bearing titanomagnetite was developed. In this study, a mixed solvent system of di(2-ethylhexyl) phosphate (D2EHPA) and tri-n-butyl phosphate (TBP) diluted with kerosene was used for the selective extraction of vanadium from a hydrochloric acid leaching solution that contained low vanadium concentration with high concentrations of iron and impurities of Ca, Mg, and Al. In the extraction process, the initial solution pH and the phase ratio had considerable functions in the extraction of vanadium from the hydrochloric acid leaching solution. Under optimal extraction conditions (i.e., 30–40 °C for 10 min, 1:3 phase ratio (O/A), 20% D2EHPA concentration (v/v), and 0–0.8 initial solution pH), 99.4% vanadium and only 4.2% iron were extracted by the three-stage counter-current extraction process. In the stripping process with H{sub 2}SO{sub 4} as the stripping agent and under optimal stripping conditions (i.e., 20% H{sub 2}SO{sub 4} concentration, 5:1 phase ratio (O/A), 20 min stripping time, and 40 °C stripping temperature), 99.6% vanadium and only 5.4% iron were stripped by the three-stage counter-current stripping process. The stripping solution contained 40.16 g/L V{sub 2}O{sub 5}, 0.691g/L Fe, 0.007 g/L TiO{sub 2}, 0.006 g/L SiO{sub 2} and 0.247 g/L CaO. A V{sub 2}O{sub 5} product with a purity of 99.12% V{sub 2}O{sub 5} and only 0.026% Fe was obtained after the oxidation, precipitation

NEXAFS characterization and reactivity studies of bimetallic vanadium molybdenum oxynitride hydrotreating catalysts

Energy Technology Data Exchange (ETDEWEB)

Kapoor, R.; Oyama, S.T. [Virginia Polytechnic Inst., Blacksburg, VA (United States); Fruehberger, B.; Chen, J.G. [Exxon Research and Engineering Company, Annandale, NJ (United States)

1997-02-27

The surface and bulk compositions of vanadium molybdenum oxynitride (V{sub 2}MoO{sub 1.7}N{sub 2.4}), prepared by temperature-programmed reaction (TPR) of vanadium molybdenum oxide (V{sub 2}MoO{sub 8}) with ammonia, have been characterized using near-edge X-ray absorption fine structure (NEXAFS) spectroscopy. The NEXAFS data were recorded at the K-edges of nitrogen and oxygen, the L-edge of vanadium, and the M-edge of molybdenum. The nitrogen K-edge region of V-Mo oxynitride shows the characteristic NEXAFS features of early-transition-metal nitrides, although these features are different from those of either VN or Mo{sub 2}N. Furthermore, comparison of the electron yield and fluorescence yield measurements also reveals that the oxidation state is different for vanadium near the surface region and for vanadium in the bulk, which is estimated to be 2.8 {+-} 0.3 and 3.8 {+-} 0.3, respectively. The oxidation state of bulk molybdenum is also estimated to be 4.4 {+-} 0.3. The X-ray diffraction pattern shows that the bulk phase of the bimetallic oxide is different from the pure monometallic oxide phases but the oxynitride has a cubic structure that resembles the pure vanadium and molybdenum nitride phases. The V-Mo oxide as prepared shows a preferential orientation of [001] crystallographic planes which is lost during the nitridation process. This shows that the solid state transformation V{sub 2}MoO{sub 8} {yields} V{sub 2}MoO{sub 1.7}N{sub 2.4} is not topotactic. 27 refs., 8 figs., 1 tab.

Transformers: the changing phases of low-dimensional vanadium oxide bronzes.

Science.gov (United States)

Marley, Peter M; Horrocks, Gregory A; Pelcher, Kate E; Banerjee, Sarbajit

2015-03-28

In this feature article, we explore the electronic and structural phase transformations of ternary vanadium oxides with the composition MxV2O5 where M is an intercalated cation. The periodic arrays of intercalated cations ordered along quasi-1D tunnels or layered between 2D sheets of the V2O5 framework induce partial reduction of the framework vanadium atoms giving rise to charge ordering patterns that are specific to the metal M and stoichiometry x. This periodic charge ordering makes these materials remarkably versatile platforms for studying electron correlation and underpins the manifestation of phenomena such as colossal metal-insulator transitions, quantized charge corrals, and superconductivity. We describe current mechanistic understanding of these emergent phenomena with a particular emphasis on the benefits derived from scaling these materials to nanostructured dimensions wherein precise ordering of cations can be obtained and phase relationships can be derived that are entirely inaccessible in the bulk. In particular, structural transformations induced by intercalation are dramatically accelerated due to the shorter diffusion path lengths at nanometer-sized dimensions, which cause a dramatic reduction of kinetic barriers to phase transformations and facilitate interconversion between the different frameworks. We conclude by summarizing numerous technological applications that have become feasible due to recent advances in controlling the structural chemistry and both electronic and structural phase transitions in these versatile frameworks.

The interfacial chemistry of metallized, oxide coated, and nanocomposite coated polymer films

Energy Technology Data Exchange (ETDEWEB)

Barker, C.P. [Durham Univ. (United Kingdom). Dept. of Chemistry; Kochem, K.H. [HOECHST Aktiengesellschaft, Werk Kalle/Albert, Geschaftsbereich H, Rheingaustrasse 190-196, D-65174 Wiesbaden (Germany); Revell, K.M. [CAMVAC (Europe) Ltd., Burrell Way, Thetford, Norfolk IP24 3QY (United Kingdom); Kelly, R.S.A. [CAMVAC (Europe) Ltd., Burrell Way, Thetford, Norfolk IP24 3QY (United Kingdom); Badyal, J.P.S. [Durham Univ. (United Kingdom). Dept. of Chemistry

1995-02-15

Aluminium, aluminium oxide, and aluminium/aluminium oxide nanocomposite coated polymer substrates have been characterized by X-ray photoelectron spectroscopy, transmission electron microscopy, argon ion sputter depth profiling, and gas permeation measurements. A comparison of the similarities and differences between these coatings has provided a detailed insight into the physicochemical origins of gas barrier associated with metallized plastics. Keywords: Aluminium; Aluminium oxide; Coatings; X-ray photoelectron spectroscopy ((orig.))

The vanadium/oxygen system in the analysis of sodium for oxygen

International Nuclear Information System (INIS)

Walker, J.A.J.; Price, W.B.

1981-05-01

An investigation of the V-O-Na system at 1023 K is described for oxygen in sodium contents of 5 to 25 ppm. Electron spectroscopy combined with depth profiling is used to determine the vanadium/oxygen ratios inwards from the surface of vanadium foil and these ratios are compared with theoretical predictions. The validity of the vanadium wire technique as an analytical method is examined and a model for the vanadium oxidation is suggested. (author)

Hydrothermal synthesis of graphene oxide/multiwalled carbon nanotube/Fe3O4 ternary nanocomposite for removal of Cu (II) and methylene blue

Science.gov (United States)

Long, Zhihang; Zhan, Yingqing; Li, Fei; Wan, Xinyi; He, Yi; Hou, Chunyan; Hu, Hai

2017-09-01

In this work, highly activated graphene oxide/multiwalled carbon nanotube/Fe3O4 ternary nanocomposite adsorbent was prepared from a simple hydrothermal route by using ferrous sulfate as precursor. For this purpose, the graphene oxide/multiwalled carbon nanotube architectures were formed through the π-π attractions between them, followed by attaching Fe3O4 nanoparticles onto their surface. The structure and composition of as-prepared ternary nanocomposite were characterized by XRD, FTIR, XPS, SEM, TEM, Raman, TGA, and BET. It was found that the resultant porous graphene oxide/multiwalled carbon nanotube/Fe3O4 ternary nanocomposite with large surface area could effectively prevent the π-π stacking interactions between graphene oxide nanosheets and greatly improve sorption sites on the surfaces. Thus, owing to the unique ternary nanocomposite architecture and synergistic effect among various components, as-prepared ternary nanocomposite exhibited high separation efficiency when they were used to remove the Cu (II) and methylene blue from aqueous solutions. Furthermore, the adsorption isotherms of ternary nanocomposite structures for Cu (II) and methylene blue removal fitted the Langmuir isotherm model. This work demonstrated that the graphene oxide/multiwalled carbon nanotube/Fe3O4 ternary nanocomposite was promising as an efficient adsorbent for heavy metal ions and organic dye removal from wastewater in low concentration.

Elastomeric Nanocomposite Based on Exfoliated Graphene Oxide and Its Characteristics without Vulcanization

OpenAIRE

Nasser Abdullah Habib; Buong Woei Chieng; Norkhairunnisa Mazlan; Umer Rashid; Robiah Yunus; Suraya Abdul Rashid

2017-01-01

Rubber nanocomposites have emerged as one of the advanced materials in recent years. The aim of this work was to homogeneously disperse graphene oxide (GO) sheets into Nitrile Butadiene Rubber (NBR) and investigate the characteristics of GO/NBR nanocomposite without vulcanization. A suitable solvent was found to dissolve dry NBR while GO was exfoliated completely in an aqueous base solution using sonication. GO was dispersed into NBR at different loadings by solution mixing to produce unvulca...

Graphene oxide-MnO2 nanocomposite for supercapacitor application

Science.gov (United States)

Muhammed Shafi, P.; Vishal, Jose K.; Chandra Bose, A.

2016-09-01

Increased depletion of fossil fuels along with global warming and climate change made the society to think about alternate green and sustainable energy sources and better energy storage devices. Extensive research has been performed on the development of solar cells, fuel cells, Lithium- ion battery and supercapacitors to combat the green house effect and its consequences, and to meet the increased energy crisis. Supercapacitors, also known as electrochemical capacitors are gained a great attention because of their pulse power supply, long cycle life (>100,000), simple principle and high dynamic of charge propagation. Its greater power density than lithium- ion battery and much larger energy density than conventional capacitors brought super capacitors to a promising energy storage device to meet the increased energy demands. Here we demonstrate supercapacitor electrode materials with graphene oxide (electric double layer capacitor) and α-MnO2 nanomaterial (pseudo-capacitor), as well as composite of these materials, which means that the bulk of the material undergoes a fast redox reaction to provide the capacitive response and they exhibit superior specific energies in addition to the carbon-based supercapacitors (double-layer capacitors). A simple soft chemical route is utilized to synthesize graphene oxide, α-MnO2 and graphene oxide-MnO2 composite. The phase and the structure of the synthesized materials are studied using X-ray diffractometry (XRD). The functional group and the presence of impurities are understood from Fourier transform infrared (FTIR) spectra. The capacitive properties of the graphene oxide, graphene oxide - MnO2 nanocomposite and α-MnO2 are tested with the help of cyclic voltammetry (CV) and galvanostatic charge - discharge techniques using 1 M Na2SO4 in aqueous solution as electrolyte. It was found that graphene oxide - MnO2 nanocomposite shows better electrochemical behaviour compared to individual graphene oxide and α-MnO2 nanomaterial.

Synthesis and Characterization of Nanocomposites Tin Oxide-Graphene Doping Pd Using Polyol Method

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Aminuddin Debataraja

2018-05-01

Full Text Available This paper report on polyol method for Pd doped tin oxide-graphene nanocomposite thin film. XRD result shows sharp peaks at certain 2θ value and match with tin oxide, graphene, and Pd database. FTIR result shows peak from alcohol chain for –OH strong bonded absorption (3444 cm-1, also there are aldehyde and ketone which are indicated by C=O strong absorption (1751 cm-1. Moreover, alkene is also formed for decreasing symmetry intensity C=C (1616 cm-1, while alkyne is formed at strong deformation absorption at 646 and 613 cm-1. SEM and TEM result show SnO2 particles are attached uniformly on graphene surface layer. The composition for C, O, Sn, and Pd are 33.13, 25.58, 35.35 and 5.94%, respectively. This result indicated that the good composition is formed for Pd doped SnO2-graphene nanocomposite. The nanocomposite is promising materials for toxic gas sensor application at low temperature.

Graphene-zinc oxide (G-ZnO nanocomposite for electrochemical supercapacitor applications

Directory of Open Access Journals (Sweden)

Murugan Saranya

2016-12-01

Full Text Available Graphene-ZnO nanocomposites (G-ZnO were prepared by a facile solvothermal approach. Well, crystalline ZnO nanoparticles with size in the range of 30–70 nm are uniformly deposited on the graphene sheets, as evidenced by different techniques. The electrochemical properties of the prepared nanocomposites were examined by measuring the specific capacitance in 6 M KOH solution using cyclic voltammetry and galvanostatic charge–discharge techniques. G-ZnO nanocomposites showed a good capacitive behavior with a specific capacitance of 122.4 F/g as compared to graphene oxide (2.13 F/g and rGO (102.5 F/g at 5 mV/s scan rate. Results demonstrated that such hybrid materials are promising electrode materials for high-performance supercapacitor applications.

Structure and Properties of Nanocomposites based on PTT-block-PTMO Copolymer and Graphene Oxide prepared by in Situ Polymerization

OpenAIRE

Paszkiewicz, Sandra; Szymczyk, Anna; Špitalský, Zdenko; Mosnáček, Jaroslav; Kwiatkowski, Konrad; Rosłaniec, Zbigniew

2014-01-01

Poly(trimethylene terephthalate-block-tetramethylene oxide) (PTT-PTMO) copolymer/graphene oxide nanocomposites were prepared by in situ polymerization. From the SEM and TEM images of PTT-PTMO/GO nanocomposite, it can be seen that GO sheets are clearly well-dispersed in the PTT-PTMO matrix. TEM images also showed that graphene was well exfoliated into individual sheets, suggesting that in situ polymerization is a highly efficient method for preparing nanocomposites. The influence of GO on the ...

Vanadium

International Nuclear Information System (INIS)

Duke, V.W.A.

1983-07-01

Although a relatively abundant element, vanadium occurs only rarely in sufficient concentration to be worked commercially. In most cases, vanadium is produced as a co-product of some other element, most commonly iron. The principal ore deposits of vanadium occur in titaniferous magnetites that have been formed by magnetic segregation. Important commercial deposits of vanadium also occur associated with uranium, and with phosphate deposits. The principal uses of vanadium are in the production of special purpose, particularly high-strength low-alloy steels, in the manufacture of titanium alloys, and as a catalyst, notably in the manufacture of sulphuric acid. Small quantities of vanadium, often in combination with niobium, are added to steel to bring about toughening through grain refinement, and increased tensile strength through precipitation hardening. Known world reserves of vanadium are very large and fully adequate to meet any foreseeable demand. By far the largest known deposits of vanadium occur in South Africa. Many other similar deposits are known, but are only exploited in the USSR and China. The present total world demand for vanadium amounts to about 40 000 tons of metal annually and this is produced primarily in four countries, South Africa, the USSR, the People's Republic of China and the United States of America, in that order. South Africa is the principal vanadium producing country in the world, supplying vanadium in various forms. Vanadium has a very low and non-accumulative toxicity; recovery plants can be operated in such a manner to ensure no air or steam pollution results

Simultaneous electrochemical determination of dopamine and paracetamol on multiwalled carbon nanotubes/graphene oxide nanocomposite-modified glassy carbon electrode.

Science.gov (United States)

Cheemalapati, Srikanth; Palanisamy, Selvakumar; Mani, Veerappan; Chen, Shen-Ming

2013-12-15

In the present study, multiwalled carbon nanotubes (MWCNT)/graphene oxide (GO) nanocomposite was prepared by homogenous dispersion of MWCNT and GO and used for the simultaneous voltammetric determination of dopamine (DA) and paracetamol (PA). The TEM results confirmed that MWCNT walls were wrapped well with GO sheets. The MWCNT/GO nanocomposite showed superior electrocatalytic activity towards the oxidation of DA and PA, when compared with either pristine MWCNT or GO. The major reason for the efficient simultaneous detection of DA and PA at nanocomposite was the synergistic effect between MWCNT and GO. The electrochemical oxidation of DA and PA was investigated by cyclic voltammetry, differential pulse voltammetry and amperometry. The nanocomposite modified electrode showed electrocatalytic oxidation of DA and PA in the linear response range from 0.2 to 400 µmol L(-1) and 0.5 to 400 µmol L(-1) with the detection limit of 22 nmol L(-1) and 47 nmol L(-1) respectively. The proposed sensor displayed good selectivity, sensitivity, stability with appreciable consistency and precision. © 2013 Elsevier B.V. All rights reserved.

Effective Recovery of Vanadium from Oil Refinery Waste into Vanadium-Based Metal-Organic Frameworks.

Science.gov (United States)

Zhan, Guowu; Ng, Wei Cheng; Lin, Wenlin Yvonne; Koh, Shin Nuo; Wang, Chi-Hwa

2018-03-06

Carbon black waste, an oil refinery waste, contains a high concentration of vanadium(V) leftover from the processing of crude oil. For the sake of environmental sustainability, it is therefore of interest to recover the vanadium as useful products instead of disposing of it. In this work, V was recovered in the form of vanadium-based metal-organic frameworks (V-MOFs) via a novel pathway by using the leaching solution of carbon black waste instead of commercially available vanadium chemicals. Two different types of V-MOFs with high levels of crystallinity and phase purity were fabricated in very high yields (>98%) based on a coordination modulation method. The V-MOFs exhibited well-defined and controlled shapes such as nanofibers (length: > 10 μm) and nanorods (length: ∼270 nm). Furthermore, the V-MOFs showed high catalytic activities for the oxidation of benzyl alcohol to benzaldehyde, indicating the strong potential of the waste-derived V-MOFs in catalysis applications. Overall, our work offers a green synthesis pathway for the preparation of V-MOFs by using heavy metals of industrial waste as the metal source.

Effect of substrate temperature on thermochromic vanadium dioxide thin films sputtered from vanadium target

Science.gov (United States)

Madiba, I. G.; Kotsedi, L.; Ngom, B. D.; Khanyile, B. S.; Maaza, M.

2018-05-01

Vanadium dioxide films have been known as the most promising thermochromic thin films for smart windows which self-control the solar radiation and heat transfer for energy saving, comfort in houses and automotives. Such an attractive technological application is due to the fact that vanadium dioxide crystals exhibit a fast semiconductor-to-metal phase transition at a transition temperature Tc of about 68 °C, together with sharp optical changes from high transmitive to high reflective coatings in the IR spectral region. The phase transition has been associated with the nature of the microstructure, stoichiometry and stresses related to the oxide. This study reports on the effect of the crystallographic quality controlled by the substrate temperature on the thermochromic properties of vanadium dioxide thin films synthesized by reactive radio frequency inverted cylindrical magnetron sputtering from vanadium target. The reports results are based on X-ray diffraction, Atomic force microscopy, and UV-Visible spectrophotometer. The average crystalline grain size of VO2 increases with the substrate temperature, inducing stress related phenomena within the films.

Optical spectra of vanadium (5, 4) compounds during extraction by di-2-ethylhexylphosphoric acid

International Nuclear Information System (INIS)

Kurbatova, L.D.; Medvedeva, N.I.

2000-01-01

Optical spectra of vanadium (5, 4) complexes with HDEHP are studied using literature data on quantum-chemical calculations of vanadium (5) and vanadium (4) oxides. Extraction of vanadium is conducted by undiluted HDEHP from sulfuric acid solutions. Absorption electron spectra (AES) of vanadium (5), vanadium (4) and vanadium (5, 4) compounds are presented. In AES of vanadium (5, 4) four absorption bands at 24000, 17000, 14500 and 13500 cm -1 appear. Comparison with spectra of vanadium (5) and vanadium (4) shows that band 17000 cm -1 which appears only during mutual extraction of vanadium (5) and vanadium (4) is caused by transitions appearing between filled and empty levels of d-zone broadened by vanadium (5) and vanadium (4) interaction [ru

Crystallization and unusual rheological behavior in poly(ethylene oxide)–clay nanocomposites

KAUST Repository

Kelarakis, Antonios

2011-05-01

We report a systematic study of the crystallization and rheological behavior of poly(ethylene oxide) (PEO)-clay nanocomposites. To that end a series of nanocomposites based on PEOs of different molecular weight (103 < MW < 105 g/mol) and clay surface modifier was synthesized and characterized. Incorporation of organoclays with polar (MMT-OH) or aromatic groups (MMT-Ar) suppresses the crystallization of polymer chains in low MW PEO, but does not significantly affect the crystallization of high MW matrices. In addition, the relative complex viscosity of the nanocomposites based on low MW PEO increases significantly, but the effect is less pronounced at higher MWs. The viscosity increases in the series MMT-Alk < MMT-OH < MMT-Ar. In contrast to the neat PEO which exhibits a monotonic decrease of viscosity with temperature, all nanocomposites show an increase after a certain temperature. This is the first report of such dramatic enhancements in the viscoelasticity of nanocomposites, which are reversible, are based on a simple polymer matrix and are true in a wide temperature range. © 2011 Elsevier Ltd. All rights reserved.

Nanocomposites of recycled polycarbonate and nano-zinc oxide (rPC/nZnO): effect of gamma radiation and nano oxide content on the thermal properties

International Nuclear Information System (INIS)

Carvalho, A.L.F.; Mendes, L.C.; Cestari, S.P.

2014-01-01

In order to promote the barrier action to the ultraviolet radiation and increase of mechanical characteristics, nanocomposites of recycled polycarbonate (rPC) and nano-zinc oxide (nZnO) containing 1, 2 and 3 % (wt/wt) of nano oxide were prepared. Since for obtaining nanocomposites and irradiating polymers are promising tools and attractive for improving the material performance, the effects of nano-zinc oxide and gamma radiation, at doses ranged from 10 to 50 kGy, were evaluated in terms of thermal characteristics of the rPC. The rPC/nZnO nanocomposites were characterized by thermogravimetric analysis (TGA) and differential explanatory calorimetry (DSC). There was a progressive decrease of the T_g as function of gamma dosage and nano-zinc oxide content. Initially, the Tonset and Tmax decayed as function of gamma dosage but a recovery was observed. The amount of nano-zinc oxide induced a decreasing of T_o_n_s_e_t and T_m_a_x. (author)

Hollow carbon sphere/metal oxide nanocomposites anodes for lithium-ion batteries

International Nuclear Information System (INIS)

Wenelska, K.; Ottmann, A.; Schneider, P.; Thauer, E.; Klingeler, R.; Mijowska, E.

2016-01-01

HCS (Hollow carbon spheres) covered with metal oxide nanoparticles (SnO_2 and MnO_2, respectively) were successfully synthesized and investigated regarding their potential as anode materials for lithium-ion batteries. Raman spectroscopy shows a high degree of graphitization for the HCS host structure. The mesoporous nature of the nanocomposites is confirmed by Brunauer–Emmett–Teller analysis. For both metal oxides under study, the metal oxide functionalization of HCS yields a significant increase of electrochemical performance. The charge capacity of HCS/SnO_2 is 370 mA hg"−"1 after 45 cycles (266 mA hg"−"1 in HCS/MnO_2) which clearly exceeds the value of 188 mA hg"−"1 in pristine HCS. Remarkably, the data imply excellent long term cycling stability after 100 cycles in both cases. The results hence show that mesoporous HCS/metal oxide nanocomposites enable exploiting the potential of metal oxide anode materials in Lithium-ion batteries by providing a HCS host structure which is both conductive and stable enough to accommodate big volume change effects. - Highlights: • Strategy to synthesize hollow carbon spheres decorated by metal oxides nanoparticles. • High-performance of HCS/MOx storage as mesoporous hybrid material. • The results hence demonstrate high electrochemical activity of the HCS/MOx.

The electronic structure and metal-insulator transitions in vanadium oxides

International Nuclear Information System (INIS)

Mossanek, Rodrigo Jose Ochekoski

2010-01-01

The electronic structure and metal-insulator transitions in vanadium oxides (SrVO_3, CaVO_3, LaVO_3 and YVO_3) are studied here. The purpose is to show a new interpretation to the spectra which is coherent with the changes across the metal-insulator transition. The main experimental techniques are the X-ray photoemission (PES) and X-ray absorption (XAS) spectroscopies. The spectra are interpreted with cluster model, band structure and atomic multiplet calculations. The presence of charge-transfer satellites in the core-level PES spectra showed that these vanadium oxides cannot be classified in the Mott-Hubbard regime. Further, the valence band and core-level spectra presented a similar behavior across the metal insulator transition. In fact, the structures in the spectra and their changes are determined by the different screening channels present in the metallic or insulating phases. The calculated spectral weight showed that the coherent fluctuations dominate the spectra at the Fermi level and give the metallic character to the SrVO_3 and CaVO_3 compounds. The vanishing of this charge fluctuation and the replacement by the Mott-Hubbard screening in the LaVO_3 and YVO_3 systems is ultimately responsible for the opening of a band gap and the insulating character. Further, the correlation effects are, indeed, important to the occupied electronic structure (coherent and incoherent peaks). On the other hand, the unoccupied electronic structure is dominated by exchange and crystal field effects (t2g and eg sub-bands of majority and minority spins). The optical conductivity spectrum was obtained by convoluting the removal and addition states. It showed that the oxygen states, as well as the crystal field and exchange effects are necessary to correctly compare and interpret the experimental results. Further, a correlation at the charge-transfer region of the core-level and valence band optical spectra was observed, which could be extended to other transition metal oxides

Novel acid-base hybrid membrane based on amine-functionalized reduced graphene oxide and sulfonated polyimide for vanadium redox flow battery

International Nuclear Information System (INIS)

Cao, Li; Sun, Qingqing; Gao, Yahui; Liu, Luntao; Shi, Haifeng

2015-01-01

A series of novel acid-base hybrid membranes (SPI/PEI-rGO) based on sulfonated polyimide (SPI) with polyethyleneimine-functionalized reduced graphene oxide (PEI-rGO) are prepared by a solution-casting method for vanadium redox flow battery (VRB). FT-IR and XPS results prove the successful fabrication of PEI-rGO and SPI/PEI-rGO hybrid membranes, which show a dense and homogeneous structure observed by SEM. The physicochemical properties such as water uptake, swelling ratio, ion exchange capacity, proton conductivity and vanadium ion permeability are well controlled by the incorporated PEI-rGO fillers. The interfacial-formed acid-base pairs between PEI-rGO and SPI matrix effectively reduce the swelling ratio and vanadium ion permeability, increasing the stability performance of the hybrid membranes. SPI/PEI-rGO-2 hybrid membrane exhibits a higher coulombic efficiency (CE, 95%) and energy efficiency (EE, 75.6%) at 40 mA cm −2 , as compared with Nafion 117 membrane (CE, 91% and EE, 66.8%). The self-discharge time of the VRB with SPI/PEI-rGO-2 hybrid membrane (80 h) is longer than that of Nafion 117 membrane (26 h), demonstrating the excellent blocking ability for vanadium ion. After 100 charge-discharge cycles, SPI/PEI-rGO-2 membrane exhibits the good stability under strong oxidizing and acid condition, proving that SPI/PEI-rGO acid-base hybrid membranes could be used as the promising candidates for VRB applications

Hydrometallurgic treatment of a mineral containing uranium, vanadium and phosphorus

International Nuclear Information System (INIS)

Echenique, Patricia; Fruchtenicht, Fernando; Gil, Daniel; Vigo, Daniel; Bouza, Angel; Vert, Gabriela; Becquart, Elena

1987-01-01

A preliminary study of a mineral has been made towards the hydrometallurgy separation of uranium, vanadium and phosphorus. After the ore dressing, work on sulfuric acid with oxidation leaching has been made, to get the uranium, vanadium and phosphorus in solution. For the separation and purification of these elements, two alternative solvent extraction methods have been tested. One of them has been the extraction of uranium and vanadium and a selective stripping of both elements. The second one has been the selective extraction of uranium and vanadium at different aqueous solutions pH. In both methods, the same reagent has been used: di(2-ethylhexyl) phosphoric acid, kerosene as diluent with two different synergistic agents: TOPO (tri-n-octyl phosphine oxide) and TBP (tri-n-butyl phosphate). Batch studies have been made to determine the equilibrium isotherms for uranium and vanadium. A continuous countercurrent simulation method has been used to get the best phase ratio and to test different stripping agents. For the first method, an important loss of uranium and vanadium at the feed solution conditioning for the extraction step has been observed. For the second method, a good recovery of uranium has been reached, but there has been losses of vanadium in pH adjustment. Nevertheless, among these processes, the last seems to work better in this mineral hydrometallurgy. (Author) [es

Graphene oxide-silver nanocomposite as a promising biocidal agent against methicillin-resistant Staphylococcus aureus

Directory of Open Access Journals (Sweden)

de Moraes ACM

2015-11-01

Full Text Available Ana Carolina Mazarin de Moraes,1 Bruna Araujo Lima,2 Andreia Fonseca de Faria,1 Marcelo Brocchi,2 Oswaldo Luiz Alves1 1Laboratory of Solid State Chemistry, Institute of Chemistry, University of Campinas, Campinas, São Paulo, Brazil; 2Department of Genetics, Evolution and Bioagents, Institute of Biology, University of Campinas, Campinas, São Paulo, Brazil Background: Methicillin-resistant Staphylococcus aureus (MRSA has been responsible for serious hospital infections worldwide. Nanomaterials are an alternative to conventional antibiotic compounds, because bacteria are unlikely to develop microbial resistance against nanomaterials. In the past decade, graphene oxide (GO has emerged as a material that is often used to support and stabilize silver nanoparticles (AgNPs for the preparation of novel antibacterial nanocomposites. In this work, we report the synthesis of the graphene-oxide silver nanocomposite (GO-Ag and its antibacterial activity against relevant microorganisms in medicine. Materials and methods: GO-Ag nanocomposite was synthesized through the reduction of silver ions (Ag+ by sodium citrate in an aqueous GO dispersion, and was extensively characterized using ultraviolet-visible absorption spectroscopy, X-ray diffraction, thermogravimetric analysis, X-ray photoelectron spectroscopy, and transmission electron microscopy. The antibacterial activity was evaluated by microdilution assays and time-kill experiments. The morphology of bacterial cells treated with GO-Ag was investigated via transmission electron microscopy. Results: AgNPs were well distributed throughout GO sheets, with an average size of 9.4±2.8 nm. The GO-Ag nanocomposite exhibited an excellent antibacterial activity against methicillin-resistant S. aureus, Acinetobacter baumannii, Enterococcus faecalis, and Escherichia coli. All (100% MRSA cells were inactivated after 4 hours of exposure to GO-Ag sheets. In addition, no toxicity was found for either pristine GO or bare Ag

Vanadium oxide V2O5 reaction with calcium metavanadate

International Nuclear Information System (INIS)

Krasnenko, T.I.; Slobodin, B.V.; Zhilyaev, V.A.

1983-01-01

Complex physicochemical studies on the V 2 O 5 Ca(VO 3 ) 2 mixtures, annealed under different conditions, were conducted. It was established that the V 2 O 5 -Ca(VO 3 ) 2 system is characterized by the following features: defective structure of initial components, which are in equilibrium state; irreversible structural transformation without changes in the macrosymmetry (530 deg C) of calcium metavanadate, deficient in calcium and oxygen; melting of eutectic mixture of components which are in equilibrium at 616+-3 deg C; Ca(VO 3 ) 2 melting with decomposition at 775+-3 deg C. Besides this, the formation of oxide vanadium bronze of β-type calcium is possible under some conditions (narrow temperature range, certain partial oxygen pressure, etc)

Dielectric properties of modified graphene oxide filled polyurethane nanocomposites and its correlation with rheology

NARCIS (Netherlands)

Sadasivuni, K.K.; Ponnamma, D.; Kumar, B.; Strankowski, M.; Cardinaels, R.M.; Moldenaers, P.; Thomas, S.; Grohens, Y.

2014-01-01

This study aims at investigating the dynamic mechanical, dielectric and rheological properties of reinforced polyurethane (PU) nanocomposites containing hydrophilic graphene oxide (GO) and/or hydrophobic modified graphene oxide (mGO) sheets. The organic modification of GO was performed with

Microwave-assisted synthesis of Mn{sub 3}O{sub 4} nanoparticles@reduced graphene oxide nanocomposites for high performance supercapacitors

Energy Technology Data Exchange (ETDEWEB)

She, Xiao; Zhang, Xinmin; Liu, Jingya [School of Materials Science and Engineering, Wuhan Institute of Technology, Wuhan 430073 (China); Li, Liang, E-mail: msell08@163.com [School of Materials Science and Engineering, Wuhan Institute of Technology, Wuhan 430073 (China); Yu, Xianghua; Huang, Zhiliang [School of Materials Science and Engineering, Wuhan Institute of Technology, Wuhan 430073 (China); Shang, Songmin, E-mail: shang.songmin@polyu.edu.hk [Institute of Textiles and Clothing, The Hong Kong Polytechnic University, Hong Kong (China)

2015-10-15

Highlights: • Mn{sub 3}O{sub 4}@rGO nanocomposites were prepared by one-step microwave-assisted method. • The growth of Mn{sub 3}O{sub 4} and the reduction of graphene oxide occurred simultaneously. • Specific capacitance of the nanocomposite is higher than those of rGO and Mn{sub 3}O{sub 4}. • The nanocomposites have good rate capability and cycling stability. - ABSTRACT: One-step microwave-assisted synthetic route for the fabrication of Mn{sub 3}O{sub 4} nanoparticles@reduced graphene oxide (Mn{sub 3}O{sub 4}@rGO) nanocomposites has been demonstrated. The morphological structures of the nanocomposites are characterized by Fourier transform infrared spectroscopy (FT-IR), Raman spectroscopy, X-ray diffraction (XRD), thermogravimetric analyses (TGA), and scanning electron microscopy (SEM), respectively. All of the results indicate that the microwave-assisted synthesis results in the growth of Mn{sub 3}O{sub 4} and the reduction of graphene oxide simultaneously in ethylene glycol-water system. The specific capacitance of the as-prepared Mn{sub 3}O{sub 4}@rGO nanocomposite is higher than those of rGO and pure Mn{sub 3}O{sub 4}, which indicates the synergetic interaction between rGO and Mn{sub 3}O{sub 4}. The nanocomposites also have good rate capability and cycling stability in electrochemical experiments. This facile technique may be extended to the large scale and cost effective production of other composites based on graphene and metal oxide for many applications.

High rate capability of lithium/silver vanadium oxide cells

International Nuclear Information System (INIS)

Takeuchi, E.S.; Zelinsky, M.A.; Keister, P.

1986-01-01

High rate characteristics of the lithium/silver vanadium oxide system were investigated in test cells providing four different limiting surface areas. The cells were tested by constant current and constant resistance discharge with current densities ranging from 0.04 to 6.4 mA/cm/sup 2/. The maximum current density under constant resistance and constant current discharges which would deliver 50% of theoretical capacity was determined. The ability of the cells to deliver high current pulses was evaluated by application of 10 second pulses with current densities ranging from 3 to 30 mA/cm/sup 2/. The voltage delay characteristics of the cells were determined after 1 to 3 months of storage at open circuit voltage or under low level background currents. The volumetric and gravimetric energy density of the SVO system is compared to other cathode materials

Extrusion of polysaccharide nanocrystal reinforced polymer nanocomposites through compatibilization with poly(ethylene oxide).

Science.gov (United States)

Pereda, Mariana; El Kissi, Nadia; Dufresne, Alain

2014-06-25

Polysaccharide nanocrystals with a rodlike shape but with different dimensions and specific surface area were prepared from cotton and capim dourado cellulose, and with a plateletlike morphology from waxy maize starch granules. The rheological behavior of aqueous solutions of poly(ethylene oxide) (PEO) with different molecular weights when adding these nanoparticles was investigated evidencing specific interactions between PEO chains and nanocrystals. Because PEO also bears hydrophobic moieties, it was employed as a compatibilizing agent for the melt processing of polymer nanocomposites. The freeze-dried mixtures were used to prepare nanocomposite materials with a low density polyethylene matrix by extrusion. The thermal and mechanical behavior of ensuing nanocomposites was studied.

Dynamic mechanical properties of hydroxyapatite/polyethylene oxide nanocomposites: characterizing isotropic and post-processing microstructures

Science.gov (United States)

Shofner, Meisha; Lee, Ji Hoon

2012-02-01

Compatible component interfaces in polymer nanocomposites can be used to facilitate a dispersed morphology and improved physical properties as has been shown extensively in experimental results concerning amorphous matrix nanocomposites. In this research, a block copolymer compatibilized interface is employed in a semi-crystalline matrix to prevent large scale nanoparticle clustering and enable microstructure construction with post-processing drawing. The specific materials used are hydroxyapatite nanoparticles coated with a polyethylene oxide-b-polymethacrylic acid block copolymer and a polyethylene oxide matrix. Two particle shapes are used: spherical and needle-shaped. Characterization of the dynamic mechanical properties indicated that the two nanoparticle systems provided similar levels of reinforcement to the matrix. For the needle-shaped nanoparticles, the post-processing step increased matrix crystallinity and changed the thermomechanical reinforcement trends. These results will be used to further refine the post-processing parameters to achieve a nanocomposite microstructure with triangulated arrays of nanoparticles.

Polyurethane Nanocomposites Containing Reduced Graphene Oxide, FTIR, Raman, and XRD Studies

Directory of Open Access Journals (Sweden)

Michał Strankowski

2016-01-01

Full Text Available Recently, graphene and other graphene-based materials have become an essential part of composite science and technology. Their unique properties are not only restricted to graphene but also shared with derivative compounds like graphene oxide, reduced graphene oxide, functionalized graphene, and so forth. One of the most structurally important materials, graphene oxide (GO, is prepared by the oxidation of graphite. Though removal of the oxide groups can create vacancies and structural defects, reduced graphene oxide (rGO is used in composites as effective filler similar to GO. Authors developed a new polyurethane nanocomposite using a derivative of grapheme, thermally reduced graphene oxide (rGO, to modify the matrix of polyurethane elastomers, by rGO.

Supported Vanadium Oxide Catalysts: Quantitative Spectroscopy, Preferential Adsorption of V^4+/5+, and Al2O3 Coating of Zeolite Y

NARCIS (Netherlands)

Catana, Gabriela; Rao, R.R.; Weckhuysen, B.M.; Voort, Pascal van der; Vansant, Etienne; Schoonheydt, R.A.

1998-01-01

A series of supported vanadium oxide catalysts were prepared by the incipient wetness method as a function of the support composition (Al2O3, SiO2, and USY), the metal oxide loading (0-1 wt %), and the impregnation salt (vanadyl sulfate and ammonium vanadate). These catalysts have been studied by

rGO-ZnO nanocomposites for high electrocatalytic effect on water oxidation obtained by microwave-hydrothermal method

Science.gov (United States)

Romeiro, Fernanda C.; Rodrigues, Mônica A.; Silva, Luiz A. J.; Catto, Ariadne C.; da Silva, Luis F.; Longo, Elson; Nossol, Edson; Lima, Renata C.

2017-11-01

Reduced graphene oxide-zinc oxide (rGO-ZnO) nanocomposites were successfully synthesized using a facile microwave-hydrothermal method under mild conditions, and their electrocatalytic properties towards O2 evolution were investigated. The microwave radiation played an important role in obtainment of well dispersed ZnO nanoparticles directly on reduced graphene oxide sheets without any additional reducing reagents or passivation agent. X-ray diffraction (XRD), Raman and infrared spectroscopies indicated the reduction of GO as well as the successful synthesis of rGO-ZnO nanocomposites. The chemical states of the samples were shown by XPS analyses. Due to the synergic effect, the resulting nanocomposites exhibited high electronic interaction between ZnO and rGO sheets, which improved the electrocatalytic oxidation of water with low onset potential of 0.48 V (vs. Ag/AgCl) in neutral pH and long-term stability, with high current density during electrolysis. The overpotential for water oxidation decreased in alkaline pH, suggesting useful insight on the catalytic mechanism for O2 evolution.

Vanadium-substituted heteropolyacids immobilized on amine- functionalized mesoporous MCM-41: A recyclable catalyst for selective oxidation of alcohols with H{sub 2}O{sub 2}

Energy Technology Data Exchange (ETDEWEB)

Dong, Xinbo [Key Laboratory of Synthetic and Natural Functional Molecule Chemistry, Department of Chemistry (Ministry of Education), Northwest University, Xi' an 710069 (China); Wang, Danjun [Key Laboratory of Synthetic and Natural Functional Molecule Chemistry, Department of Chemistry (Ministry of Education), Northwest University, Xi' an 710069 (China); College of Chemistry Chemical Engineering, Yanan University, Shaanxi Key Laboratory of Chemical Reaction Engineering, Yan' an 716000 (China); Li, Kebin [Key Laboratory of Synthetic and Natural Functional Molecule Chemistry, Department of Chemistry (Ministry of Education), Northwest University, Xi' an 710069 (China); Zhen, Yanzhong [Key Laboratory of Synthetic and Natural Functional Molecule Chemistry, Department of Chemistry (Ministry of Education), Northwest University, Xi' an 710069 (China); College of Chemistry Chemical Engineering, Yanan University, Shaanxi Key Laboratory of Chemical Reaction Engineering, Yan' an 716000 (China); Hu, Huaiming [Key Laboratory of Synthetic and Natural Functional Molecule Chemistry, Department of Chemistry (Ministry of Education), Northwest University, Xi' an 710069 (China); Xue, Ganglin, E-mail: xglin707@163.com [Key Laboratory of Synthetic and Natural Functional Molecule Chemistry, Department of Chemistry (Ministry of Education), Northwest University, Xi' an 710069 (China)

2014-09-15

Graphical abstract: Vanadium-substituted phosphotungstic acids are immobilized on amine- functionalized mesoporous MCM-41 and the hybrid catalyst is proved to be a highly efficient solid catalyst for the oxidation of aromatic alcohols to the corresponding carbonyl compounds with H{sub 2}O{sub 2}, featured by the high conversion and selectivity, easy recovery, and quite steady reuse. - Highlights: • Vanadium-substituted phosphotungstic acid immobilized on amine-functionalized mesoporous MCM-41 are prepared. • HPAs were fixed on the inner surface of mesoporous MCM-41 by chemical bonding to aminosilane groups. • The hybrid catalyst showed much higher catalytic activity than the pure HPAs. • The hybrid catalyst is a highly efficient recyclable solid catalyst for the selective oxidation of aromatic alcohols. - Abstract: New hybrid materials of vanadium-substituted phosphotungstic acids (VHPW) immobilized on amine-functionalized mesoporous MCM-41 (VHPW/MCM-41/NH{sub 2}) are prepared and characterized by FT-IR, XRD, N{sub 2} adsorption, elemental analysis, SEM and TEM for their structural integrity and physicochemical properties. It is found that the structure of the heteropolyacids is retained upon immobilization over mesoporous materials. The catalytic activities of these hybrid materials are tested in the selective oxidation of alcohols to the carbonyl products with 30% aqueous H{sub 2}O{sub 2} as oxidant in toluene. The catalytic activities of different number of vanadium-substituted phosphotungstic acid are investigated, and among the catalysts, H{sub 5}[PV{sub 2}W{sub 10}O{sub 40}] immobilized on amine-functionalized MCM-41 exhibits the highest activity with 97% conversion and 99% selectivity in the oxidation of benzyl alcohol to benzaldehyde. The hybrid catalyst is proved to be a highly efficient recyclable solid catalyst for the selective oxidation of aromatic alcohols to the corresponding aldehydes with H{sub 2}O{sub 2}.

Application of graphene oxide-poly (vinyl alcohol) polymer nanocomposite for memory devices

Science.gov (United States)

Kaushal, Jyoti; Kaur, Ravneet; Sharma, Jadab; Tripathi, S. K.

2018-05-01

Significant attention has been gained by polymer nanocomposites because of their possible demands in future electronic memory devices. In the present work, device based on Graphene Oxide (GO) and polyvinyl alcohol (PVA) has been made and examined for the memory device application. The prepared Graphene oxide (GO) and GO-PVA nanocomposite (NC) has been characterized by X-ray Diffraction (XRD). GO nanosheets show the diffraction peak at 2θ = 11.60° and the interlayer spacing of 0.761 nm. The XRD of GO-PVA NC shows the diffraction peak at 2θ =18.56°. The fabricated device shows bipolar switching behavior having ON/OFF current ratio ˜102. The Write-Read-Erase-Read (WRER) cycles test shows that the Al/GO-PVA/Ag device has good stability and repeatability.

A Facile Route to Metal Oxides/Single-Walled Carbon Nanotube Macrofilm Nanocomposites for Energy Storage

Science.gov (United States)

Cao, Zeyuan; Wei, Bingqing

2015-05-01

Nanocomposites consisting of transition-metal oxides and carbon nanomaterials with a desired size and structure are highly demanded for high performance energy storage devices. Here, a facile two-step and cost-efficient approach relying on directly thermal treatment of chemical-vapor-deposition products is developed as a general synthetic method to prepare a family of metal oxides (MxOy (M=Fe, Co, Ni))/single-walled carbon nanotube (SWNT) macrofilm nanocomposites. The MxOy nanoparticles obtained are of 3-17 nm in diameter and homogeneously anchor on the free-standing SWNT macrofilms. NiO/SWNT also exhibits a high specific capacitance of 400 F g-1 and fast charge-transfer Faradaic redox reactions to achieve asymmetric supercapacitors with a high power and energy density. All MxOy/SWNT nanocomposites could deliver a high capacity beyond 1000 mAh g-1 and show excellent cycling stability for lithium-ion batteries. The impressive results demonstrate the promise for energy storage devices and the general approach may pave the way to synthesize other functional nanocomposites.

A Facile Route to Metal Oxides/Single-Walled Carbon Nanotube Macrofilm Nanocomposites for Energy Storage

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Zeyuan eCao

2015-05-01

Full Text Available Nanocomposites consisting of transition-metal oxides and carbon nanomaterials with a desired size and structure are highly demanded for high performance energy storage devices. Here, a facile two-step and cost-efficient approach relying on directly thermal treatment of chemical-vapor-deposition products is developed as a general synthetic method to prepare a family of metal oxides (MxOy (M=Fe, Co, Ni/single-walled carbon nanotube (SWNT macrofilm nanocomposites. The MxOy nanoparticles obtained are of 3-17 nm in diameter and homogeneously anchor on the free-standing SWNT macrofilms. NiO/SWNT also exhibits a high specific capacitance of 400 F g-1 and fast charge-transfer Faradaic redox reactions to achieve asymmetric supercapacitors with a high power and energy density. All MxOy/SWNT nanocomposites could deliver a high capacity beyond 1000 mAh g-1 and show excellent cycling stability for lithium-ion batteries. The impressive results demonstrate the promise for energy storage devices and the general approach may pave the way to synthesize other functional nanocomposites.

In-situ synthesis and performance of titanium oxide/poly(methyl methacrylate) nanocomposites.

Science.gov (United States)

Bandugula, Uttam C; Clayton, L M; Harmon, J P; Kumar, Ashok

2005-05-01

Polymer nanocomposites have elicited extensive research efforts due to their potential to exhibit spectacular properties. They have immense potential and are befitting materials to serve as an ideal and futuristic alternative for varied applications. Poly(methyl methacrylate) (PMMA) and titanium oxide (TiO2) nanocomposites used in this study were fabricated by an in-situ free radical polymerization process. Three point bend tests were conducted with a modified universal microtribometer to evaluate fracture toughness. The results indicated that the stress intensity values increase as the concentration of titanium oxide increases up to 1 vol% and subsequently decrease at higher concentrations. Scanning electron microscopy (SEM) images of fracture surfaces afforded clues as to the possible deformation mechanism. Ultraviolet-visible spectroscopy (UV-vis) evaluated the degree of transparency of the nanocomposites. It was observed that samples became opaque as the concentration was increased beyond 0.01% volume fraction. X-ray diffraction characterized the TiO2 crystalline phase and Scherrer's equation was used to calculate the crystallite size. Among the concentrations considered the 3% volume fraction sample had the largest crystallite size. Finally, microhardness measurements further characterized the mechanical properties of the composites.

Vanadium based materials as electrode materials for high performance supercapacitors

Science.gov (United States)

Yan, Yan; Li, Bing; Guo, Wei; Pang, Huan; Xue, Huaiguo

2016-10-01

As a kind of supercapacitors, pseudocapacitors have attracted wide attention in recent years. The capacitance of the electrochemical capacitors based on pseudocapacitance arises mainly from redox reactions between electrolytes and active materials. These materials usually have several oxidation states for oxidation and reduction. Many research teams have focused on the development of an alternative material for electrochemical capacitors. Many transition metal oxides have been shown to be suitable as electrode materials of electrochemical capacitors. Among them, vanadium based materials are being developed for this purpose. Vanadium based materials are known as one of the best active materials for high power/energy density electrochemical capacitors due to its outstanding specific capacitance and long cycle life, high conductivity and good electrochemical reversibility. There are different kinds of synthetic methods such as sol-gel hydrothermal/solvothermal method, template method, electrospinning method, atomic layer deposition, and electrodeposition method that have been successfully applied to prepare vanadium based electrode materials. In our review, we give an overall summary and evaluation of the recent progress in the research of vanadium based materials for electrochemical capacitors that include synthesis methods, the electrochemical performances of the electrode materials and the devices.

Growth and structure of Si and Ge in vanadium oxide nanomesh on Pd(1 1 1) studied by STM and DFT

International Nuclear Information System (INIS)

Chan, Lap Hong; Hayazaki, Shinji; Ogawa, Kokushi; Yuhara, Junji

2013-01-01

Highlights: ► We studied the growth and structure of Si and Ge in vanadium oxide nanomesh on Pd(1 1 1) by STM and DFT calculations. ► All the Si atoms formed isolated Si nanoclusters. ► Some Ge atoms formed monomer Ge nanodots on Pd(1 1 1), while the others formed isolated Ge nanoclusters. - Abstract: The growth of silicon (Si)/germanium (Ge) atoms in a well ordered (4 × 4) vanadium (V) oxide nanomesh on Pd(1 1 1) prepared by ultra-high-vacuum evaporation has been studied by scanning tunneling microscopy (STM) and ab initio density functional theory (DFT) calculations. At the very beginning of the Si deposition, all of the Si atoms deposited were adsorbed on top of the V-oxide nanomesh, forming Si nanoclusters, and each Si atom formed was isolated other Si atoms. Two different adsorption sites for Si atoms were observed by STM. In the case of Ge deposition, some Ge atoms filled the vanadium oxide nanoholes, forming Ge nanodots on Pd(1 1 1), while the others were adsorbed on top of the V-oxide nanomesh, forming isolated Ge nanoclusters. The ab initio DFT total-energy calculations indicated that the Ge atoms occupying the nanohole were more stable than those adsorbed on the nanomesh. The simulated images were highly consistent with the experimental STM images with the exception of the Ge nanodots, which exhibited a large, uniform protrusion in the STM images. Therefore, the adsorbed atom might be mobile in the nanohole at room temperature, possibly as a result of interaction with the STM tip.

Effect of Nanodiamonds on Structure and Durability of Polyethylene Oxide-Based Nanocomposites

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Rossella Arrigo

2016-01-01

Full Text Available Polymer-based nanocomposites containing nanodiamonds (NDs are attractive multifunctional materials with a growing range of applications. In this work, in the frame of developing completely biocompatible systems, nanocomposites based on polyethylene oxide (PEO and different amount of NDs have been formulated through melt mixing and fully characterized. In particular, the reinforcement effect of NDs in PEO has been probed through tensile tests, and the rheological response of PEO-based nanocomposites as a function of the nanoparticles amount has been investigated and discussed. The obtained results show that the presence of well-distributed NDs strengthens the mechanical performance of the nanocomposites and brings about an increase of the PEO crystallinity, suggesting a strong adhesion between NDs and polymer matrix. Furthermore, as a result of NDs adding, alterations of the rheological behaviour of neat PEO can be noticed, as NDs are able to significantly influence the long-range dynamics of PEO chains. Besides, accelerated aging tests demonstrate that NDs show a remarkable protective ability against PEO photodegradation, due to their ability to attenuate efficiently UV radiation. The latter opens up new avenues for the use of NDs as multifunctional nanofillers for polymer-based nanocomposites with enhanced photooxidative resistance.

Synthesis and morphology of hydroxyapatite/polyethylene oxide nanocomposites with block copolymer compatibilized interfaces

Science.gov (United States)

Lee, Ji Hoon; Shofner, Meisha

2012-02-01

In order to exploit the promise of polymer nanocomposites, special consideration should be given to component interfaces during synthesis and processing. Previous results from this group have shown that nanoparticles clustered into larger structures consistent with their native shape when the polymer matrix crystallinity was high. Therefore in this research, the nanoparticles are disguised from a highly-crystalline polymer matrix by cloaking them with a matrix-compatible block copolymer. Specifically, spherical and needle-shaped hydroxyapatite nanoparticles were synthesized using a block copolymer templating method. The block copolymer used, polyethylene oxide-b-polymethacrylic acid, remained on the nanoparticle surface following synthesis with the polyethylene oxide block exposed. These nanoparticles were subsequently added to a polyethylene oxide matrix using solution processing. Characterization of the nanocomposites indicated that the copolymer coating prevented the nanoparticles from assembling into ordered clusters and that the matrix crystallinity was decreased at a nanoparticle spacing of approximately 100 nm.

Graphenated polyaniline-doped tungsten oxide nanocomposite sensor for real time determination of phenanthrene

International Nuclear Information System (INIS)

Tovide, Oluwakemi; Jaheed, Nazeem; Mohamed, Nurali; Nxusani, Ezo; Sunday, Christopher E.; Tsegaye, Abebaw; Ajayi, Rachel F.; Njomo, Njagi; Makelane, Hlamulo; Bilibana, Mawethu; Baker, Priscilla G.; Williams, Avril; Vilakazi, Sibulelo; Tshikhudo, Robert; Iwuoha, Emmanuel I.

2014-01-01

A graphenated polyaniline/tungsten oxide (PANI/WO 3 /GR) nanocomposite sensor was prepared by electropolymerisation of a mixture of aniline monomer and tungsten oxide on a graphene-modified glassy carbon electrode (GCE). The PANI/WO 3 /GR/GCE nanocomposite electrode was tested as a sensor for the determination of phenanthrene. The direct electro-oxidation behaviour of phenanthrene on the PANI/WO 3 /GR modified GCE was carefully investigated by cyclic voltammetry. The results indicated that the PANI/WO 3 /GR/GCE sensor was more sensitive to phenanthrene (with a dynamic linear range of 1.0 - 6.0 pM and a detection limit of 0.123 pM.) than GCE, PANI/GCE or PANI/WO 3 /GCE. The sensor exhibited excellent reproducibility and long-term stability. The sensor exhibits lower detection sensitivity than the WHO permissible level of 1.12 nM phenanthrene in wastewater

Surface plasmon resonance-based fiber-optic hydrogen gas sensor utilizing palladium supported zinc oxide multilayers and their nanocomposite.

Science.gov (United States)

Tabassum, Rana; Gupta, Banshi D

2015-02-10

We analyze surface plasmon resonance-based fiber-optic sensor for sensing of small concentrations of hydrogen gas in the visible region of the electromagnetic spectrum. One of the two probes considered has multilayers of zinc oxide (ZnO) and palladium (Pd) while the other has layer of their composite over a silver coated unclad core of the fiber. The analysis is carried out for different volume fractions of palladium nanoparticles dispersed in zinc oxide host material in the nanocomposite layer. For the analysis, a Maxwell-Garnett model is adopted for calculating the dielectric function of a ZnO:Pd nanocomposite having nanoparticles of dimensions smaller than the wavelength of radiation used. The effects of the volume fraction of the nanoparticles in the nanocomposite and the thickness of the nanocomposite layer on the figure of merit of the sensor have been studied. The film thickness of the layer and the volume fraction of nanoparticles in the ZnO:Pd nanocomposite layer have been optimized to achieve the maximum value of the figure of merit of the sensor. It has been found that the figure of merit of the sensing probe coated with ZnO:Pd nanocomposite is more than twofold of the sensing probe coated with multilayers of Pd and ZnO over a silver coated unclad core of the fiber; hence, the sensor with a nanocomposite layer works better than that with multilayers of zinc oxide and palladium. The sensor can be used for online monitoring and remote sensing of hydrogen gas.

Application of vanadium incorporated phosphomolybdate supported on the modified kaolinin synthesis of diphenyl carbonate by oxidative carbonylation with phenol

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Peng Meng

2017-01-01

Full Text Available Keggin-type molybdophosphoric acid, molybdophosphoric salt and vanadium incorporated molybdophosphoric salt supported on the modified kaolin (MK were investigated as redox co-catalysts for the oxidative carbonylation of phenol to diphenyl carbonate (DPC in the absence of solvent. The 20 wt.% of MnAMPV5 (one kind of vanadium incorporated molybdophosphoric salt loaded on MK showed the highest catalytic activity with the yield of 24.68% and a TON of 306, while the selectivity amounts to nearly 100% in all the carbonylation reactions. The catalysts were characterized by XRD, BET, XPS and H2-TPR. The reusability study showed that the catalysts were stable and active.

Graphene Oxide-Based Nanocomposites Decorated with Silver Nanoparticles as an Antibacterial Agent

Science.gov (United States)

Jaworski, Sławomir; Wierzbicki, Mateusz; Sawosz, Ewa; Jung, Anna; Gielerak, Grzegorz; Biernat, Joanna; Jaremek, Henryk; Łojkowski, Witold; Woźniak, Bartosz; Wojnarowicz, Jacek; Stobiński, Leszek; Małolepszy, Artur; Mazurkiewicz-Pawlicka, Marta; Łojkowski, Maciej; Kurantowicz, Natalia; Chwalibog, André

2018-04-01

One of the most promising methods against drug-resistant bacteria can be surface-modified materials with biocidal nanoparticles and nanocomposites. Herein, we present a nanocomposite with silver nanoparticles (Ag-NPs) on the surface of graphene oxide (GO) as a novel multifunctional antibacterial and antifungal material. Ultrasonic technologies have been used as an effective method of coating polyurethane foils. Toxicity on gram-negative bacteria ( Escherichia coli), gram-positive bacteria ( Staphylococcus aureus and Staphylococcus epidermidis), and pathogenic yeast ( Candida albicans) was evaluated by analysis of cell morphology, assessment of cell viability using the PrestoBlue assay, analysis of cell membrane integrity using the lactate dehydrogenase assay, and reactive oxygen species production. Compared to Ag-NPs and GO, which have been widely used as antibacterial agents, our nanocomposite shows much higher antimicrobial efficiency toward bacteria and yeast cells.

High electrocatalytic performance of nitrogen-doped carbon nanofiber-supported nickel oxide nanocomposite for methanol oxidation in alkaline medium

Energy Technology Data Exchange (ETDEWEB)

Al-Enizi, Abdullah M. [Department of Chemistry, King Saud University, PO Box: 2455, Riyadh 11451 (Saudi Arabia); Elzatahry, Ahmed A., E-mail: aelzatahry@ksu.edu.sa [Materials Science and Technology Program, College of Arts and Science, Qatar University, Doha 2713 (Qatar); Advanced Technology and New Materials Research Institute, City of Scientific Research and Technology Applications, New Borg El-Arab City, Alexandria 21934 (Egypt); Abdullah, Aboubakr M., E-mail: bakr@qu.edu.qa [Center for Advanced Materials, Qatar University, Doha 2713 (Qatar); Vinu, Ajayan [Future Industries Institute, University of South Australia, Building X-X2-09, Mawson Lakes Campus, Mawson Lakes 5095 SA (Australia); Iwai, Hideo [Materials Analysis Station, National Institute for Materials Science, 1-2-1 Sengen, Tsukuba, Ibaraki, 305-0047 (Japan); Al-Deyab, Salem S. [Petrochemical Research Chair, Department of Chemistry, King Saud University, PO Box: 2455, Riyadh 11451 (Saudi Arabia)

2017-04-15

Highlights: • A mixture of Polyvinylpyrrolidone (PVP), graphene and emeraldine base polyaniline (PANi) was electrospun and used as starting materials to prepare a nitrogen-doped carbon nanofiber (N-CNF). • Nickel oxide was loaded on the N-CNF to form a nanocomposite which was calcined later at different temperatures. • The effect of calcination temperature on the electrocatalytic behavior of the nanocomposite was studied which shows that the nanocomposite calcined at 500 °C was proved to be very high compared to the other calcination temperatures. • The stability of catalyst was excellent and its resistance to the adsorption of the intermediates generated from the methanol oxidation was very high. - Abstract: Nitrogen-Doped Carbon Nanofiber (N-CNF)–supported NiO composite was prepared by electrospinning a sol-gel mixture of graphene and polyaniline (PANi) with aqueous solutions of Polyvinylpyrrolidone (PVP) followed by a high-temperature annealing process. The electrospun was stabilized for 2 h at 280 °C, carbonized for 5 h at 1200 °C then loaded by 10% NiO. The electrocatalytic activities of the produced nanocomposite have been studied using cyclic voltammetry, and chronoamperometry. Also, N-CNF was characterized by X-ray diffraction (XRD), thermogravimetric analysis (TGA), surface area (BET), X-ray photoelectron spectroscopy (XPS), transmission electron microscope (TEM), and scanning-electron microscopy (SEM). The obtained N-doped carbon nanofiber was found to have a nitrogen content of 2.6 atomic% with a diameter range of (140–160) nm, and a surface area (393.3 m{sup 2} g{sup −1}). In addition, it showed a high electrocatalytic behavior towards methanol oxidation reaction in alkaline medium and high stability and resistivity to the adsorption of intermediates.

Synthesis and characterization of fly ash-zinc oxide nanocomposite

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Kunal Yeole

2014-04-01

Full Text Available Fly ash, generated in thermal power plants, is recognized as an environmental pollutant. Thus, measures are required to be undertaken to dispose it in an environmentally friendly method. In this paper an attempt is made to coat zinc oxide nano-particles on the surface of fly ash by a simple and environmentally friendly facile chemical method, at room temperature. Zinc oxide may serve as effective corrosion inhibitor by providing sacrificial protection. Concentration of fly ash was varied as 5, 10 and 15 (w/w % of zinc oxide. It was found that crystallinity increased, whereas particle size, specific gravity and oil absorption value decreased with increased concentration of fly ash in zinc oxide, which is attributed to the uniform distribution of zinc oxide on the surface of fly ash. These nanocomposites can potentially be used in commercial applications as additive for anticorrosion coatings.

Lactoferrin modified graphene oxide iron oxide nanocomposite for glioma-targeted drug delivery.

Science.gov (United States)

Song, Meng-Meng; Xu, Huai-Liang; Liang, Jun-Xing; Xiang, Hui-Hui; Liu, Rui; Shen, Yu-Xian

2017-08-01

Targeting delivery of drugs in a specific manner represents a potential powerful technology in gliomas. Herein, we prepared a multifunctional targeted delivery system based on graphene oxide (GO) that contains a molecular bio-targeting ligand and superparamagnetic iron oxide nanoparticles on the surface of GO for magnetic targeting. Superparamagnetic Fe 3 O 4 nanoparticles was loaded on the surface of GO via chemical precipitation method to form GO@Fe 3 O 4 nanocomposites. Lactoferrin (Lf), an iron-transporting serum glycoprotein that binds to receptors overexpressed at the surface of glioma cells and vascular endothelial cell of the blood brain barrier, was chosen as the targeted ligand to construct the targeted delivery system Lf@GO@Fe 3 O 4 through EDC/NHS chemistry. With the confirmation of TEM, DLS and VSM, the resulting Lf@GO@Fe 3 O 4 had a size distribution of 200-1000nm and exhibited a superparamagnetic behavior. The nano delivery system had a high loading capacity and exhibited a pH-dependent release behavior. Compared with free DOX and DOX@GO@Fe 3 O 4 , Lf@GO@Fe 3 O 4 @DOX displayed greater intracellular delivery efficiency and stronger cytotoxicity against C6 glioma cells. The results demonstrated the potential utility of Lf conjugated GO@Fe 3 O 4 nanocomposites for therapeutic application in the treatment of gliomas. Copyright © 2017. Published by Elsevier B.V.

Enhanced catalytic hydrogenation activity of Ni/reduced graphene oxide nanocomposite prepared by a solid-state method

Science.gov (United States)

Li, Yizhao; Cao, Yali; Jia, Dianzeng

2018-01-01

A simple solid-state method has been applied to synthesize Ni/reduced graphene oxide (Ni/rGO) nanocomposite under ambient condition. Ni nanoparticles with size of 10-30 nm supported on reduced graphene oxide (rGO) nanosheets are obtained through one-pot solid-state co-reduction among nickel chloride, graphene oxide, and sodium borohydride. The Ni/rGO nanohybrid shows enhanced catalytic activity toward the reduction of p-nitrophenol (PNP) into p-aminophenol compared with Ni nanoparticles. The results of kinetic research display that the pseudo-first-order rate constant for hydrogenation reaction of PNP with Ni/rGO nanocomposite is 7.66 × 10-3 s-1, which is higher than that of Ni nanoparticles (4.48 × 10-3 s-1). It also presents superior turnover frequency (TOF, 5.36 h-1) and lower activation energy ( E a, 29.65 kJ mol-1) in the hydrogenation of PNP with Ni/rGO nanocomposite. Furthermore, composite catalyst can be magnetically separated and reused for five cycles. The large surface area and high electron transfer property of rGO support are beneficial for good catalytic performance of Ni/rGO nanocomposite. Our study demonstrates a simple approach to fabricate metal-rGO heterogeneous nanostructures with advanced functions.

Preparation, Characterization, and Properties of In Situ Formed Graphene Oxide/Phenol Formaldehyde Nanocomposites

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Weihua Xu

2013-01-01

Full Text Available Graphene oxide (GO has shown great potential to be used as fillers to develop polymer nanocomposites for important applications due to their special 2D geometrical structure as well as their outstanding mechanical, thermal, and electrical properties. In this work, GO was incorporated into phenol formaldehyde (PF resin by in situ polymerization. The morphologies and structures of GO sheets were characterized by FTIR, XRD, and AFM methods. The structure and properties of the GO/PF nanocomposites were characterized using FTIR, XRD, DSC, and TGA methods. Effects of GO content, reactive conditions, and blending methods on the structure and properties of GO/PF nanocomposites were studied. It was found that due to the well dispersion of GO sheets in polymer matrix and the strong interfacial interaction between the GO sheets and PF matrix, the thermal stability and thermal mechanical properties of the GO/PF nanocomposites were greatly enhanced.

Nanocomposites of manganese oxides and carbon nanotubes for aqueous supercapacitor stacks

Energy Technology Data Exchange (ETDEWEB)

Zhang Shengwen; Peng Chuang; Ng, Kok C. [Department of Chemical and Environmental Engineering, Faculty of Engineering, University of Nottingham, University Park, Nottingham NG7 2RD (United Kingdom); Chen, George Z., E-mail: george.chen@nottingham.ac.u [Department of Chemical and Environmental Engineering, Faculty of Engineering, University of Nottingham, University Park, Nottingham NG7 2RD (United Kingdom)

2010-10-30

Symmetrical supercapacitors and their serially connected two-cell stacks via a bipolar electrode were constructed with nanocomposites of manganese oxides and carbon nanotubes (MnO{sub x}/CNTs) as the electrode materials. Nanocomposites with different contents of MnO{sub x} were synthesised through the redox reaction between KMnO{sub 4} and CNTs in aqueous solutions. The nanocomposites were characterised by scanning and transmission electron microscopy, BET nitrogen adsorption and X-ray diffraction before being examined in a three-electrode cell with a novel trenched graphite disc electrode by electrochemical means, including cyclic voltammetry, galvanostatic charging-discharging, and electrochemical impedance spectroscopy. The nanocomposites demonstrated capacitive behaviour in the potential range of 0-0.85 V (vs Ag/AgCl) in aqueous KCl electrolytes with less than 9% capacitance decrease after 9000 charging-discharging cycles. Symmetrical supercapacitors of identical positive and negative MnO{sub x}/CNTs electrodes showed capacitive performance in good agreement with the individual electrodes (e.g. 0.90 V, 0.53 F, 1.3 cm{sup 2}). The bipolarly connected two-cell stacks of the symmetrical cells exhibited characteristics in accordance with expectation, including a doubled stack voltage and reduced internal resistance per cell.

Investigation of space charge distribution of low-density polyethylene/GO-GNF (graphene oxide from graphite nanofiber) nanocomposite for HVDC application.

Science.gov (United States)

Kim, Yoon Jin; Ha, Son-Tung; Lee, Gun Joo; Nam, Jin Ho; Ryu, Ik Hyun; Nam, Su Hyun; Park, Cheol Min; In, Insik; Kim, Jiwan; Han, Chul Jong

2013-05-01

This paper reported a research on space charge distribution in low-density polyethylene (LDPE) nanocomposites with different types of graphene and graphene oxide (GO) at low filler content (0.05 wt%) under high DC electric field. Effect of addition of graphene oxide or graphene, its dispersion in LDPE polymer matrix on the ability to suppress space charge generation will be investigated and compared with MgO/LDPE nanocomposite at the same filler concentration. At an applied electric field of 80 kV/mm, a positive packet-like charge was observed in both neat LDPE, MgO/LDPE, and graphene/LDPE nanocomposites, whereas only little homogenous space charge was observed in GO/LDPE nanocomposites, especially with GO synthesized from graphite nano fiber (GNF) which is only -100 nm in diameter. Our research also suggests that dispersion of graphene oxide particles on the polymer matrix plays a significant role to the performance of nanocomposites on suppressing packet-like space charge. From these results, it is expected that nano-sized GO synthesized from GNF can be a promising filler material to LDPE composite for HVDC applications.

Development of Vanadium Phosphaate Catalysts for Methanol Production by Selective Oxidation of Methane.

Energy Technology Data Exchange (ETDEWEB)

McCormick, R.L.

1997-10-01

This DOE sponsored study of methane partial oxidation was initiated at Amax Research and Development in Golden, CO in October of 1993. Shortly thereafter the management of Amax closed this R&D facility and the PI moved to the Colorado School of Mines. The project was begun again after contract transfer via a novation agreement. Experimental work began with testing of vandyl pyrophosphate (VPO), a well known alkane selective oxidation catalyst. It was found that VPO was not a selective catalyst for methane conversion yielding primarily CO. However, promotion of VPO with Fe, Cr, and other first row transition metals led to measurable yields for formaldehyde, as noted in the summary table. Catalyst characterization studies indicated that the role of promoters was to stabilize some of the vanadium in the V{sup 5+} oxidation state rather than the V{sup 4+} state formally expected for (VO){sub 2}P{sub 2}O{sub 7}.

Visible light assisted nitrogen dioxide sensing using tungsten oxide - Graphene oxide nanocomposite sensors

Energy Technology Data Exchange (ETDEWEB)

Geng, Xin [College of Mechanical Engineering, Yangzhou University, Yangzhou 225127 (China); College of Chemistry and Chemical Engineering, Yangzhou University, Yangzhou 225002 (China); You, Jiajun; Wang, Jie [College of Mechanical Engineering, Yangzhou University, Yangzhou 225127 (China); Zhang, Chao, E-mail: zhangc@yzu.edu.cn [College of Mechanical Engineering, Yangzhou University, Yangzhou 225127 (China)

2017-04-15

Tungsten oxide (WO{sub 3}) coatings were deposited by solution precursor plasma spray (SPPS) on alumina substrates. In order to enhance the NO{sub 2} sensing properties of the pure WO{sub 3} coatings at room temperature, illuminating with visible light and formation of p-n heterojunction were used. The SPPS WO{sub 3} coatings were modified by immersing them into a synthesized graphene oxide (GO) suspension to obtain the WO{sub 3}-GO composites. Raman and FTIR results demonstrated that p-n heterojunctions were successfully formed in the WO{sub 3}-GO composites. The UV–Vis spectra showed that the WO{sub 3}-GO composites had a longer visible light absorption range compared with the WO{sub 3} coatings. The sensors based on the WO{sub 3}-GO coatings exhibited ultra-high responses to NO{sub 2} at room temperature performed under visible light illumination. - Highlights: • Highly porous nanostructured WO{sub 3} coatings were deposited by SPPS process. • The WO{sub 3}-GO nanocomposites with p-n heterojunctions were successfully prepared. • The WO{sub 3}-GO nanocomposites exhibited ultra-high responses to 0.9 ppm NO{sub 2}. • The enhanced performance was ascribed to the fine structure and heterojunction.

Spectrophotometric determination of vanadium in environmental and biological samples

International Nuclear Information System (INIS)

Rekha, D.; Krishnapriya, B.; Subrahmanyam, P.; Reddyprasad, P.; Dilip Kumar, J.; Chiranjeevi, P.

2007-01-01

The method is based on oxidation of p-nitro aniline by vanadium (V) followed by coupling reaction with N-(1-naphthalene-1-y1)ethane-1, 2-diaminedihydrochloride (NEDA) in basic medium of pH 8 to give purple colored derivative. The derivative having an λ max 525nm is stable for 10 days. Beer's law is obeyed for vanadium (V) in the concentration range of 0.03-4.5 μg ml -1 . The proposed method was successfully applied to the analysis of vanadium in environmental and biological samples. (author)

Influence of Thermal Annealing Treatment on Bipolar Switching Properties of Vanadium Oxide Thin-Film Resistance Random-Access Memory Devices

Science.gov (United States)

Chen, Kai-Huang; Cheng, Chien-Min; Kao, Ming-Cheng; Chang, Kuan-Chang; Chang, Ting-Chang; Tsai, Tsung-Ming; Wu, Sean; Su, Feng-Yi

2017-04-01

The bipolar switching properties and electrical conduction mechanism of vanadium oxide thin-film resistive random-access memory (RRAM) devices obtained using a rapid thermal annealing (RTA) process have been investigated in high-resistive status/low-resistive status (HRS/LRS) and are discussed herein. In addition, the resistance switching properties and quality improvement of the vanadium oxide thin-film RRAM devices were measured by x-ray diffraction (XRD) analysis, x-ray photoelectron spectrometry (XPS), scanning electron microscopy (SEM), atomic force microscopy (AFM), and current-voltage ( I- V) measurements. The activation energy of the hopping conduction mechanism in the devices was investigated based on Arrhenius plots in HRS and LRS. The hopping conduction distance and activation energy barrier were obtained as 12 nm and 45 meV, respectively. The thermal annealing process is recognized as a candidate method for fabrication of thin-film RRAM devices, being compatible with integrated circuit technology for nonvolatile memory devices.

Determination of vanadium in Syrian commercial and raffinate phosphoric acid

International Nuclear Information System (INIS)

Al-Merey, R.

2002-04-01

This study presents two methods for vanadium determination in Syrian commercial phosphoric acid. The vanadium (V) in the oxidized commercial phosphoric acid by ammonium persulfate solution is extracted from 5-M hydrochloride acid medium using N-benzoyl-N-phenyl hydroxyl amine (BPHA) in chloroform as an extracting solution. The first method, the extract vanadium as VOL 2 Cl is changed to V 2 O 3 L 4 complex by the addition of benzimidazole in 1-butanol to the violet organic layer. The absorbance is then measured at 440 nm (the molar absorptivity was found to be 3865 M -1 cm -1 ), where Beer law is applicable up to 36-μg ml -1 . the accuracy, precision and detection limit were found to be 3.7%, 77 ppb and 37 ppb, respectively. the second method, the organic layer is heated to evaporate chloroform, the residue is digested using 20% ammonium persulfate and 2-M sulfuric acid solutions. The vanadium concentration is measured spectrophotometrically by oxidizing gallic acid with persulfate (S 2 O 8 2- ) anion in phosphoric acid medium, where the vanadium (V) acts as a catalyst in the oxidation reaction. This method has a high sensitivity (∼10 -12 ) with accuracy and precision 5% and 0.621 ppb, respectively. Also Beer law at λ m ax=415 nm (ε=∼2 x 10 6 M -1 ) is applicable in the range 2.58-33.3 ppb. (author)

The bioinorganic electrochemistry of vanadium-penicillamine complexes

International Nuclear Information System (INIS)

Bagal, U.A.; Riechel, T.L.

1989-01-01

Vanadium (V) has been found to inhibit (Na + , K + )-ATPase in the sodium pump reaction in erythrocytes. Glutathione has been suggested as the reducing agent that reverses the effect by reducing vanadium to the (IV) oxidation state. Penicillamine is being studied as a model for glutathione since both have sulfhydryl groups which are involved in redox and coordination chemistry. The electrochemistry in DMSO of penicillamine, its carboxylic ester, and their VO 2 + complexes are discussed in this paper

A comparative assessment of the acute inhalation toxicity of vanadium compounds.

Science.gov (United States)

Rajendran, N; Seagrave, J C; Plunkett, L M; MacGregor, J A

2016-11-01

Vanadium compounds have become important in industrial processes, resulting in workplace exposure potential and are present in ambient air as a result of fossil fuel combustion. A series of acute nose-only inhalation toxicity studies was conducted in both rats and mice in order to obtain comparative data on the acute toxicity potential of compounds used commercially. V 2 O 3 , V 2 O 4 , and V 2 O 5 , which have different oxidation states (+3, +4, +5, respectively), were delivered as micronized powders; the highly water-soluble and hygroscopic VOSO 4 (+4) could not be micronized and was instead delivered as a liquid aerosol from an aqueous solution. V 2 O 5 was the most acutely toxic micronized powder in both species. Despite its lower overall percentage vanadium content, a liquid aerosol of VOSO 4 was more toxic than the V 2 O 5 particles in mice, but not in rats. These data suggest that an interaction of characteristics, i.e., bioavailability, solubility and oxidation state, as well as species sensitivity, likely affect the toxicity potential of vanadium compounds. Based on clinical observations and gross necropsy findings, the lung appeared to be the target organ for all compounds. The level of hazard posed will depend on the specific chemical form of the vanadium. Future work to define the inhalation toxicity potential of vanadium compounds of various oxidation states after repeated exposures will be important in understanding how the physico-chemical and biological characteristics of specific vanadium compounds interact to affect toxicity potential and the potential risks posed to human health.

Hydrothermal synthesis and characterization of novel vanadium oxides and their application as cathodes in lithium secondary batteries

Science.gov (United States)

Chirayil, Thomas George

Novel layered or tunneled vanadium oxides are sought as a substitute for the expensive Lisb{x}CoOsb2 cathode material in lithium rechargeable batteries. The hydrothermal synthesis approach was taken in search of new vanadium oxides in the presence of a structure directing cation, TMA. A systematic study was done on the hydrothermal synthesis of the Vsb{2}Osb{5}-TMAOH-LiOH system. It was determined from this study that the pH of the reaction mixture was very critical in the formation of many compounds. Acetic acid utilized to adjust the pH of the reaction mixture in the presence of TMA behaved as a buffer and maintained a constant pH during the reaction. Hydrothermal synthesis conducted between pH 10 and 2 resulted in the formation of 7 compounds. At the highest pH, a well known compound Lisb3VOsb4, was formed. Between pH 5.2-9, a layered compound, TMAVsb3Osb7 resulted. The thermal treatment of TMAVsb3Osb7 under oxygen lead to an oxidized phase, TMAVsb3Osb8, which increased its lithium capacity significantly. Between pH 5-6, a cluster compound, TMAsb8lbrack Vsb{22}Osb{54}(CHsb3COO)rbrack{*}4Hsb2O with the acetate ion trapped inside the caged Vsb{22}Osb{54} cluster, and a layered vanadium oxide, Lisb{x}Vsb{2-delta}Osb{4-delta}{*}Hsb2O was obtained. The Lisb{x}Vsb{2-delta}Osb{4-delta}{*}Hsb2O compound was dehydrated to form Lisb{x}Vsb{2-delta}Osb{4-delta} and the lithium was removed electrochemically to form a new type of "VOsb2". Several alkylamines, DMSO and an additional water molecule were intercalated to swell the layers of Lisb{x}Vsb{2-delta}Osb{4-delta}{*}Hsb2O. Lowering the pH between 3.0-3.5, resulted in layered compound, TMAVsb4Osb{10}, with TMA residing between the layers. Layered compounds, TMAVsb8Osb{20} and TMAsb{0.17}Hsp+sb{0.1}Vsb2Osb5, were obtained at very acidic conditions. The hydrothermally grown TMAsb{0.17}Hsp+sb{0.1}Vsb2Osb5 is similar to the xerogel Vsb2Osb5 intercalated with TMA synthesized by the sol-gel process. Several trends were observed

Synthesis of electrochromic vanadium oxide by pulsed spray pyrolysis technique and its properties

International Nuclear Information System (INIS)

Patil, C E; Tarwal, N L; Shinde, P S; Patil, P S; Deshmukh, H P

2009-01-01

A new improved pulsed spray pyrolysis technique (PSPT) was employed to deposit a vanadium oxide (V 2 O 5 ) thin film from a methanolic vanadium chloride precursor onto glass and conducting F : SnO 2 coated glass substrates. The structural, morphological, electrical, optical and spectroscopic properties of the film deposited at 573 K were studied. Infrared spectroscopy and x-ray diffraction confirmed the presence of the V 2 O 5 phase. The V 2 O 5 film (thickness ∼118 nm) is polycrystalline with a tetragonal crystal structure. Scanning electron microscopy reveals compact granular morphology consisting of ∼80-100 nm size grains. The film is transparent in the visible region (average %T ∼70%) with an optical band gap energy of 2.47 eV involving both direct and indirect optical transitions. The room temperature electrical resistivity (conductivity) of the film is 1.6 x 10 8 Ω cm (6.25 x 10 -9 S cm -1 ) with an activation energy of 0.67 eV in the temperature range 300-550 K. It exhibited cathodic electrochromism in the lithium containing electrolyte (0.5 M LiClO 4 + propylene carbonate).

The ability of silicide coating to delay the catastrophic oxidation of vanadium under severe conditions

Energy Technology Data Exchange (ETDEWEB)

Chaia, N., E-mail: nabil.chaia@univ-lorraine.fr [Université de Lorraine, Institut Jean Lamour – UMR7198, Boulevard des Aiguillettes, BP70239, 54506 Vandoeuvre-lès-Nancy Cedex (France); Mathieu, S., E-mail: stephane.mathieu@univ-lorraine.fr [Université de Lorraine, Institut Jean Lamour – UMR7198, Boulevard des Aiguillettes, BP70239, 54506 Vandoeuvre-lès-Nancy Cedex (France); Rouillard, F., E-mail: fabien.rouillard@cea.fr [CEA, DEN, DPC, SCCME, Laboratoire d’Etude de la Corrosion Non Aqueuse, F-91191 Gif-sur-Yvette (France); Vilasi, M., E-mail: michel.vilasi@univ-lorraine.fr [Université de Lorraine, Institut Jean Lamour – UMR7198, Boulevard des Aiguillettes, BP70239, 54506 Vandoeuvre-lès-Nancy Cedex (France)

2015-02-15

Highlights: • Oxidation protection is due to the formation of a pure silica layer. • V–4Cr–4Ti with V{sub x}Si{sub y} silicide coating withstands 400 1-h cycles (1100 °C-T{sub amb}) in air. • Three-point flexure testing at 950 °C and 75 MPa does not induce coating breakdown. • No delamination between coating and substrate is observed in any test. - Abstract: V–4Cr–4Ti vanadium alloy is a potential cladding material for sodium-cooled fast-neutron reactors (SFRs). However, its affinity for oxygen and the subsequent embrittlement that oxygen induces causes a need for an oxygen diffusion barrier, which can be obtained by manufacturing a multi-layered silicide coating. The present work aims to evaluate the effects of thermal cycling (using a cyclic oxidation device) and tensile and compressive stresses (using the three-point flexure test) on the coated alloy system. Tests were performed in air up to 1100 °C, which is 200 °C higher than the accidental temperature for SFR applications. The results showed that the VSi{sub 2} coating was able to protect the vanadium substrate from oxidation for more than 400 1-h cycles between 1100 °C and room temperature. The severe bending applied to the coated alloy at 950 °C using a load of 75 MPa did not lead to specimen breakage. It can be suggested that the VSi{sub 2} coating has mechanical properties compatible with the V–4Cr–4Ti alloy for SFR applications.

Biopolymeric nanocomposites with enhanced interphases.

Science.gov (United States)

Yin, Yi; Hu, Kesong; Grant, Anise M; Zhang, Yuhong; Tsukruk, Vladimir V

2015-10-06

Ultrathin and robust nanocomposite membranes were fabricated by incorporating graphene oxide (GO) sheets into a silk fibroin (SF) matrix by a dynamic spin-assisted layer-by-layer assembly (dSA-LbL). We observed that in contrast to traditional SA-LbL reported earlier fast solution removal during dropping of solution on constantly spinning substrates resulted in largely unfolded biomacromolecules with enhanced surface interactions and suppressed nanofibril formation. The resulting laminated nanocomposites possess outstanding mechanical properties, significantly exceeding those previously reported for conventional LbL films with similar composition. The tensile modulus reached extremely high values of 170 GPa, which have never been reported for graphene oxide-based nanocomposites, the ultimate strength was close to 300 MPa, and the toughness was above 3.4 MJ m(-3). The failure modes observed for these membranes suggested the self-reinforcing mechanism of adjacent graphene oxide sheets with strong 2 nm thick silk interphase composed mostly from individual backbones. This interphase reinforcement leads to the effective load transfer between the graphene oxide components in reinforced laminated nanocomposite materials with excellent mechanical strength that surpasses those known today for conventional flexible laminated carbon nanocomposites from graphene oxide and biopolymer components.

Synthesis of NiO–Al{sub 2}O{sub 3} nanocomposites by sol–gel process and their use as catalyst for the oxidation of styrene

Energy Technology Data Exchange (ETDEWEB)

Yadav, Sudheer Kumar; Jeevanandam, P., E-mail: jeevafcy@iitr.ac.in

2014-10-15

Highlights: • NiO–Al{sub 2}O{sub 3} nanocomposites have been synthesized by sol–gel method. • The synthesis takes shorter time (∼48 h) compared to reported methods. • The nanocomposites show high catalytic activity for the oxidation of styrene compared to NiO. - Abstract: NiO–Al{sub 2}O{sub 3} nanocomposites were prepared by sol–gel method. The synthesized nanocomposites were characterized by X-ray diffraction, FT-IR spectroscopy, Raman spectroscopy, field emission scanning electron microscopy coupled with energy dispersive X-ray analysis, transmission electron microscopy, diffuse reflectance spectroscopy and magnetic measurements. XRD results indicate that the NiO–Al{sub 2}O{sub 3} nanocomposites consist of small NiO crystallites (mean size ∼2.6 nm). TEM results indicate uniform distribution of NiO nanoparticles in the Al{sub 2}O{sub 3} matrix. Increase in the band gap of NiO in the nanocomposites compared to pure NiO nanoparticles is observed and the nanocomposites show superparamagnetic behaviour. The NiO–Al{sub 2}O{sub 3} nanocomposites show high catalytic activity for the oxidation of styrene using tert-butyl hydroperoxide as the oxidant and also show higher selectivity for styrene oxide with higher total conversion compared to pure NiO nanoparticles.

Graphene oxide (rGO)-metal oxide (TiO2/Fe3O4) based nanocomposites for the removal of methylene blue

Science.gov (United States)

Banerjee, Soma; Benjwal, Poonam; Singh, Milan; Kar, Kamal K.

2018-05-01

Herein, ternary nanocomposites based on titanium dioxide, ferric oxide and reduced graphene oxide (GO) have been developed for photocatalytic degradation of methylene blue. The nanocomposites are prepared by simple sol-gel and wet assembly methods with varying weight ratio of each components to obtain efficient photocatalytic degradation. Due to the synergistic effect among the three components, a swift removal of methylene blue becomes possible under visible and UV light. The rGO-Fe3O4-TiO2 nanocomposite having composition 1:1:2 has achieved maximum degradation of methylene blue from the aqueous solution. About 99% of the dye has been removed within 6 min under UV irradiation, while in presence of visible light, 94% has been degraded from the wastewater. The enhancement of photocatalytic activity in this ternary system is attributed to the efficient separation of charge carriers from TiO2 to rGO under the exposure of light and the initiation of photo-Fenton reaction due to the incorporated Fe3O4 nanoparticles in presence of H2O2, which provides highly reactive hydroxyl ions that mineralize the pollutants. All these results indicate that these ternary nanocomposites possess great potential for both UV and visible light driven methylene blue destruction from the wastewater.

Melt quenched vanadium oxide embedded in graphene oxide sheets as composite electrodes for amperometric dopamine sensing and lithium ion battery applications

Energy Technology Data Exchange (ETDEWEB)

Sreejesh, M. [Materials Research Laboratory, Department of Physics, National Institute of Technology Karnataka, P.O. Srinivasnagar, Surathkal, Mangaluru 575 025 (India); Shenoy, Sulakshana [Functional Nanostructured Materials Research Laboratory, Department of Physics, National Institute of Technology Karnataka, P.O. Srinivasnagar, Surathkal, Mangaluru 575 025 (India); Sridharan, Kishore, E-mail: kishore@nitk.edu.in [Functional Nanostructured Materials Research Laboratory, Department of Physics, National Institute of Technology Karnataka, P.O. Srinivasnagar, Surathkal, Mangaluru 575 025 (India); Kufian, D.; Arof, A.K. [Centre for Ionics, Department of Physics, Faculty of Science, University of Malaya, 50603 Kuala Lumpur (Malaysia); Nagaraja, H.S., E-mail: nagaraja@nitk.edu.in [Materials Research Laboratory, Department of Physics, National Institute of Technology Karnataka, P.O. Srinivasnagar, Surathkal, Mangaluru 575 025 (India)

2017-07-15

Highlights: • Layered vanadium oxides (MVO) are prepared through melt quenching process. • MVO is hydrothermally treated with graphene oxide to form MVGO composites. • Dopamine detection capacity using MVGO is 0.07 μM with good selectivity. • Sensitivity of dopamine detection is 25.02 μA mM{sup −1} cm{sup −2}. • Discharge capacity of MVGO electrode is 200 mAhg{sup −1} after 10 cycles. - Abstract: Electrochemical sensors and lithium-ion batteries are two important topics in electrochemistry that have attracted much attention owing to their extensive applications in enzyme-free biosensors and portable electronic devices. Herein, we report a simple hydrothermal approach for synthesizing composites of melt quenched vanadium oxide embedded on graphene oxide of equal proportion (MVGO50) for the fabrication of electrodes for nonenzymatic amperometic dopamine sensor and lithium-ion battery applications. The sensing performance of MVGO50 electrodes through chronoamperometry studies in 0.1 M PBS solution (at pH 7) over a wide range of dopamine concentration exhibited a highest sensitivity of 25.02 μA mM{sup −1} cm{sup −2} with the lowest detection limit of 0.07 μM. In addition, the selective sensing capability of MVGO50 was also tested through chronoamperometry studies by the addition of a very small concentration of dopamine (10 μM) in the presence of a fairly higher concentration of uric acid (10 mM) as the interfering species. Furthermore, the reversible lithium cycling properties of MVGO50 are evaluated by galvanostatic charge-discharge cycling studies. MVGO50 electrodes exhibited enhanced rate capacity of up to 200 mAhg{sup −1} at a current of 0.1C rate and remained stable during cycling. These results indicate that MVGO composites are potential candidates for electrochemical device applications.

Zirconium oxide nanotube-Nafion composite as high performance membrane for all vanadium redox flow battery

Science.gov (United States)

Aziz, Md. Abdul; Shanmugam, Sangaraju

2017-01-01

A high-performance composite membrane for vanadium redox flow battery (VRB) consisting of ZrO2 nanotubes (ZrNT) and perfluorosulfonic acid (Nafion) was fabricated. The VRB operated with a composite (Nafion-ZrNT) membrane showed the improved ion-selectivity (ratio of proton conductivity to permeability), low self-discharge rate, high discharge capacity and high energy efficiency in comparison with a pristine commercial Nafion-117 membrane. The incorporation of zirconium oxide nanotubes in the Nafion matrix exhibits high proton conductivity (95.2 mS cm-1) and high oxidative stability (99.9%). The Nafion-ZrNT composite membrane exhibited low vanadium ion permeability (3.2 × 10-9 cm2 min-1) and superior ion selectivity (2.95 × 107 S min cm-3). The VRB constructed with a Nafion-ZrNT composite membrane has lower self-discharge rate maintaining an open-circuit voltage of 1.3 V for 330 h relative to a pristine Nafion membrane (29 h). The discharge capacity of Nafion-ZrNT membrane (987 mAh) was 3.5-times higher than Nafion-117 membrane (280 mAh) after 100 charge-discharge cycles. These superior properties resulted in higher coulombic and voltage efficiencies with Nafion-ZrNT membranes compared to VRB with Nafion-117 membrane at a 40 mA cm-2 current density.

Electrochemical intercalation of lithium into polypyrrole/silver vanadium oxide composite used for lithium primary batteries

Energy Technology Data Exchange (ETDEWEB)

Lee, Jong-Won; Popov, Branko N. [Center for Electrochemical Engineering, Department of Chemical Engineering, University of South Carolina, Columbia, SC 29208 (United States)

2006-10-20

Hybrid composites of polypyrrole (PPy) and silver vanadium oxide (SVO) used for lithium primary batteries were chemically synthesized by an oxidative polymerization of pyrrole monomer on the SVO surface in an acidic medium. The composite electrode exhibited higher discharge capacity and better rate capability as compared with the pristine SVO electrode. The improvement in electrochemical performance of the composite electrode was due to PPy which accommodates lithium ions and also enhances the SVO utilization. Chronoamperometric and ac-impedance measurements indicated that lithium intercalation proceeds under the mixed control by interfacial charge transfer and diffusion. The enhanced SVO utilization in the composite electrode results from a facilitated kinetics of interfacial charge transfer in the presence of PPy. (author)

Electrochemical intercalation of lithium into polypyrrole/silver vanadium oxide composite used for lithium primary batteries

Science.gov (United States)

Lee, Jong-Won; Popov, Branko N.

Hybrid composites of polypyrrole (PPy) and silver vanadium oxide (SVO) used for lithium primary batteries were chemically synthesized by an oxidative polymerization of pyrrole monomer on the SVO surface in an acidic medium. The composite electrode exhibited higher discharge capacity and better rate capability as compared with the pristine SVO electrode. The improvement in electrochemical performance of the composite electrode was due to PPy which accommodates lithium ions and also enhances the SVO utilization. Chronoamperometric and ac-impedance measurements indicated that lithium intercalation proceeds under the mixed control by interfacial charge transfer and diffusion. The enhanced SVO utilization in the composite electrode results from a facilitated kinetics of interfacial charge transfer in the presence of PPy.

Sorption of Sr(II) onto nanocomposites of graphene oxide-polymeric matrix

Czech Academy of Sciences Publication Activity Database

Bubeníková, M.; Ecorchard, Petra; Szatmáry, L.; Mrózek, Ondřej; Salačová, P.; Tolasz, Jakub

2018-01-01

Roč. 315, č. 2 (2018), s. 263-272 ISSN 0236-5731 R&D Projects: GA TA ČR(CZ) TA04020222 Institutional support: RVO:61388980 Keywords : Graphene oxide * Nanocomposite * PA66 * Polystyrene * Radiostrontium removal Subject RIV: CA - Inorganic Chemistry OBOR OECD: Inorganic and nuclear chemistry Impact factor: 1.282, year: 2016

Study on the poisoning effect-of non-vanadium catalysts by potassium

Science.gov (United States)

Zeng, Huanmu; Liu, Ying; Yu, Xiaowei; Lin, Yasi

2018-02-01

The poisoning effect of catalyst by alkali metals is one of the problems in the selective catalytic reduction (SCR) of NO by NH3. Serious deactivation by alkali poisoning have been proved to take place in the commercial vanadium catalyst. Recently, non-vanadium catalysts such as copper oxides, manganese oxides, chromium oxides and cerium oxides have attracted special attentions in SCR application. However, their tolerance in the presence of alkali metals is still doubtful. In this paper, copper oxides, manganese oxides, chromium oxides and cerium oxides supported on TiO2 nanoparticle was prepared by impregnating method. Potassium nitrate was chosen as the precursor of poisoner. Catalytic activities of these catalysts were evaluated before and after the addition of potassium. Some characterization methods including X-ray diffraction and temperature programmed desorption was utilized to reveal the main reason of alkali deactivation.

Multifunctional pH-sensitive superparamagnetic iron-oxide nanocomposites for targeted drug delivery and MR imaging.

Science.gov (United States)

Zhu, Lijuan; Wang, Dali; Wei, Xuan; Zhu, Xinyuan; Li, Jianqi; Tu, Chunlai; Su, Yue; Wu, Jieli; Zhu, Bangshang; Yan, Deyue

2013-08-10

A multifunctional pH-sensitive superparamagnetic iron-oxide (SPIO) nanocomposite system was developed for simultaneous tumor magnetic resonance imaging (MRI) and therapy. Small-size SPIO nanoparticles were chemically bonded with antitumor drug doxorubicin (DOX) and biocompatible poly(ethylene glycol) (PEG) through pH-sensitive acylhydrazone linkages, resulting in the formation of SPIO nanocomposites with magnetic targeting and pH-sensitive properties. These DOX-conjugated SPIO nanocomposites exhibited not only good stability in aqueous solution but also high saturation magnetizations. Under an acidic environment, the DOX was quickly released from the SPIO nanocomposites due to the cleavage of pH-sensitive acylhydrazone linkages. With the help of magnetic field, the DOX-conjugated SPIO nanocomposites showed high cellular uptake, indicating their magnetic targeting property. Comparing to free DOX, the DOX-conjugated SPIO nanocomposites showed better antitumor effect under magnetic field. At the same time, the relaxivity value of these SPIO nanocomposites was higher than 146s(-1)mM(-1) Fe, leading to ~4 times enhancement compared to that of free SPIO nanoparticles. As a negative contrast agent, these SPIO nanocomposites illustrated high resolution in MRI diagnosis of tumor-bearing mice. All of these results confirm that these pH-sensitive SPIO nanocomposites are promising hybrid materials for synergistic MRI diagnosis and tumor therapy. Copyright © 2013 Elsevier B.V. All rights reserved.

A novel layered manganese oxide/poly(aniline-co-o-anisidine) nanocomposite and its application for electrochemical supercapacitor

International Nuclear Information System (INIS)

Yang Xiaofeng; Wang Gengchao; Wang Ruiyu; Li Xingwei

2010-01-01

A novel layered manganese oxide/poly(aniline-co-o-anisidine) nanocomposite [MnO 2 /P(An-co-oAs)] was successfully synthesized by a delamination/reassembling process using P(An-co-oAs) ionomer and layered manganese oxide in aqueous solution. This nanocomposite obtained was then characterized by Fourier transform infrared (FTIR) spectra, X-ray diffraction (XRD), electron microscopy (SEM), and thermogravimetric (TG) analysis. X-ray diffraction and electron microscope analysis showed that the MnO 2 /P(An-co-oAs) nanocomposite had a lamellar structure with increasing interlayer spacing. The MnO 2 /P(An-co-oAs) nanocomposite exhibited substantially improved conductivity, which was near 100 times greater than that of its pristine MnO 2 (3.5 x 10 -7 S cm -1 ). The specific capacitance of the MnO 2 /P(An-co-oAs) nanocomposite reached 262 F g -1 in 1 M Na 2 SO 4 at a current density of 1 A g -1 , which was significantly higher than that of either of its two pristine materials [MnO 2 (182 F g -1 ) or P(An-co-oAs) (127 F g -1 )] owing to the synergic effect between the two pristine components. The fabrication mechanism of the nanocomposite was also proposed and discussed in this paper.

The preparation and characteristic of poly (3,4-ethylenedioxythiophene)/reduced graphene oxide nanocomposite and its application for supercapacitor electrode

Energy Technology Data Exchange (ETDEWEB)

Mao, Xiling [State Key Laboratory of Electronic Thin Films and Integrated Devices, School of Optoelectronic Information, University of Electronic Science and Technology of China (UESTC), Chengdu 610054 (China); Yang, Wenyao [School of Electrical and Electronic Engineering, Engineering Research Center of Electronic Information Technology and Application, Chongqing University of Arts and Sciences, Chongqing 402160 (China); He, Xin; Chen, Yan; Zhao, Yuetao; Zhou, Yujiu; Yang, Yajie [State Key Laboratory of Electronic Thin Films and Integrated Devices, School of Optoelectronic Information, University of Electronic Science and Technology of China (UESTC), Chengdu 610054 (China); Xu, Jianhua, E-mail: jianhuaxu8023@126.com [State Key Laboratory of Electronic Thin Films and Integrated Devices, School of Optoelectronic Information, University of Electronic Science and Technology of China (UESTC), Chengdu 610054 (China)

2017-02-15

Highlights: • A facile method to prepare PEDOT/rGO nanocomposite. • Taking full advantages of electrochemical polymerization and laser-writing methods. • The PEDOT/rGO nanocomposite possesses excellent electrochemical properties. - Abstract: Here we demonstrate a facile electrochemical polymerization and laser induction process to fabricate poly (3,4-ethylenedioxythiophene)/reduced graphene oxide (PEDOT/rGO) nanocomposite, which can be used as supercapacitor electrode material. Firstly, a PEDOT film is deposited on ITO substrate using an electrochemical polymerization method and a graphene oxide (GO) film is successively deposited on as-prepared PEDOT film through a spin-coating method. Then, by using a laser-writing method, the GO film is transformed into the rGO and a PEDOT/rGO nanocomposite is obtained. The resulting nanocomposite shows high areal capacitance about 43.75 mF/cm{sup 2}, which is nearly 3 times higher than that of the PEDOT film at a current density of 0.2 mA/cm{sup 2}. The PEDOT/rGO nanocomposite exhibits excellent cyclic stability, which can retain 83.6% of its initial capacitance after 1000 charge-discharge cycles. Furthermore, this nanocomposite can be deposited on varied substrates as electrode materials, which shows promising application to prepare high performance energy storage materials.

Vanadium oxides supported on hydrotalcite-type precursors: the effect of acid-base properties on the oxidation of isopropanol

Directory of Open Access Journals (Sweden)

D. M. Meira

2006-09-01

Full Text Available Vanadium oxide supported on hydrotalcite-type precursors was studied in the oxidation of isopropanol. Hydrotalcites with different y = Mg/Al ratios were synthesized by the method of coprecipitation nitrates of Mg and Al cations with K2CO3 as precipitant. The decomposition of these hydrotalcite precursors at 450°C yielded homogeneous MgyAlOx mixed oxides that contain the Al+3 cations totally incorporated into the MgO framework. The materials were characterized by chemical analysis, BET superficial area, X-ray diffraction, temperature-programmed reduction (TPR and the reaction of isopropanol, a probe molecule used to evaluate the acid-base properties. The results of TPR showed that the reducibility of V+5 decreased with the increase in magnesium loading in catalysts. The X-ray diffraction patterns of Al-rich hydrotalcite precursors showed the presence of crystalline phases of brucite and gibbsite. It was shown that chemical composition, texture, acid-base properties of the active sites and also Mg/Al ratio strongly affect the formation of the products in the oxidation of isopropanol. The Al-rich catalysts were much more active than the Mg-rich ones, converting isopropanol mainly to propylene.

Vanadium oxides supported on hydrotalcite-type precursors: the effect of acid base properties on the oxidation of isopropanol

Energy Technology Data Exchange (ETDEWEB)

Meira, D.M.; Cortez, G.G. [Faculdade de Engenharia Quimica de Lorena, Lorena, SP (Brazil). Dept. de Engenharia Quimica. Lab. de Catalise II]. E-mail: cortez@dequi.faenquil.br; Monteiro, W.R.; Rodrigues, J.A.J. [Instituto Nacional de Pesquisas Espaciais (INPE), Sao Jose dos Campos, SP (Brazil). Lab. Associado de Combustao e Propulsao]. E-mail: jajr@lcp.inpe.br

2006-07-15

Vanadium oxide supported on hydrotalcite-type precursors was studied in the oxidation of isopropanol. Hydrotalcites with different y = Mg/Al ratios were synthesized by the method of coprecipitation nitrates of Mg and Al cations with K{sub 2}CO{sub 3} as precipitant. The decomposition of these hydrotalcite precursors at 450 deg C yielded homogeneous MgyAlOx mixed oxides that contain the Al{sup +3} cations totally incorporated into the MgO framework. The materials were characterized by chemical analysis, BET superficial area, X-ray diffraction, temperature-programmed reduction (TPR) and the reaction of isopropanol, a probe molecule used to evaluate the acid-base properties. The results of TPR showed that the reducibility of V{sup +5} decreased with the increase in magnesium loading in catalysts. The X-ray diffraction patterns of Al-rich hydrotalcite precursors showed the presence of crystalline phases of brucite and gibbsite. It was shown that chemical composition, texture, acid-base properties of the active sites and also Mg/Al ratio strongly affect the formation of the products in the oxidation of isopropanol. The Al-rich catalysts were much more active than the Mg-rich ones, converting isopropanol mainly to propylene. (author)

Ferroferric oxide/polystyrene (Fe3O4/PS superparamagnetic nanocomposite via facile in situ bulk radical polymerization

Directory of Open Access Journals (Sweden)

2010-03-01

Full Text Available Organo-modified ferroferric oxide superparamagnetic nanoparticles, synthesized by the coprecipitation of superparamagnetic nanoparticles in presence of oleic acid (OA, were incorporated in polystyrene (PS by the facile in situ bulk radical polymerization by using 2,2-azobisisobutyronitrile (AIBN as initiator. The transmission electron microscopy (TEM analysis of the resultant uniform ferroferric oxide/polystyrene superparamagnetic nanocomposite (Fe3O4/PS showed that the superparamagnetic nanoparticles had been dispersed homogeneously in the polymer matrix due to the surface grafted polystyrene, confirmed by Fourier transform infrared (FT-IR spectroscopy and thermogravimetric analysis (TGA. The superparamagnetic property of the Fe3O4/PS nanocomposite was testified by the vibrating sample magnetometer (VSM analysis. The strategy developed is expected to be applied for the large-scale industrial manufacturing of the superparamagnetic polymer nanocomposite.

Novel Nanocomposite Materials for Advanced Li-Ion Rechargeable Batteries

Directory of Open Access Journals (Sweden)

Chuan Cai

2009-09-01

Full Text Available Nanostructured materials lie at the heart of fundamental advances in efficient energy storage and/or conversion, in which surface processes and transport kinetics play determining roles. Nanocomposite materials will have a further enhancement in properties compared to their constituent phases. This Review describes some recent developments of nanocomposite materials for high-performance Li-ion rechargeable batteries, including carbon-oxide nanocomposites, polymer-oxide nanocomposites, metal-oxide nanocomposites, and silicon-based nanocomposites, etc. The major goal of this Review is to highlight some new progress in using these nanocomposite materials as electrodes to develop Li-ion rechargeable batteries with high energy density, high rate capability, and excellent cycling stability.

Self-assembly of a superparamagnetic raspberry-like silica/iron oxide nanocomposite using epoxy-amine coupling chemistry.

Science.gov (United States)

Cano, Manuel; de la Cueva-Méndez, Guillermo

2015-02-28

The fabrication of colloidal nanocomposites would benefit from controlled hetero-assembly of ready-made particles through covalent bonding. Here we used epoxy-amine coupling chemistry to promote the self-assembly of superparamagnetic raspberry-like nanocomposites. This adaptable method induced the covalent attachment of iron oxide nanoparticles sparsely coated with amine groups onto epoxylated silica cores in the absence of other reactants.

A corrosion-protective coating based on a solution-processable polymer-grafted graphene oxide nanocomposite

International Nuclear Information System (INIS)

Qi, Kai; Sun, Yimin; Duan, Hongwei; Guo, Xingpeng

2015-01-01

Highlights: • Solution-processable polymer-grafted graphene nanocomposite is synthesized. • The nanocomposite exhibits synergistic properties of both building blocks. • The nanocomposite can be easily applied to form a protective coating on metals. • The coating can effectively prevent corrosion of copper substrate. - Abstract: A new type of solution-processable graphene coating has been synthesized by grafting polymethylmethacrylate (PMMA) brushes on graphene oxide (GO) via surface-initiated atom transfer radical polymerization (ATRP). One major finding is that the PMMA-grafted GO nanocomposite exhibits synergistic properties of both building blocks, i.e., permeation inhibition of GO and solubility of PMMA in a variety of solvents, which makes it compatible with commonly used coating methods to form uniform coatings with controlled thickness. Our results demonstrate that PMMA-grafted GO coating can effectively block charge transfer at the metal–electrolyte interface and prevent corrosion of the copper substrate under aggressive saline conditions

Superparamagnetic magnetite nanocrystals-graphene oxide nanocomposites: facile synthesis and their enhanced electric double-layer capacitor performance.

Science.gov (United States)

Wang, Qihua; Wang, Dewei; Li, Yuqi; Wang, Tingmei

2012-06-01

Superparamagnetic magnetite nanocrystals-graphene oxide (FGO) nanocomposites were successfully synthesized through a simple yet versatile one-step solution-processed approach at ambient conditions. Magnetite (Fe3O4) nanocrystals (NCs) with a size of 10-50 nm were uniformly deposited on the surfaces of graphene oxide (GO) sheets, which were confirmed by transmission electron microscopy (TEM) and high-angle annular dark field scanning transmission election microscopy (HAADF-STEM) studies. FGO with different Fe3O4 loadings could be controlled by simply manipulating the initial weight ratio of the precursors. The M-H measurements suggested that the as-prepared FGO nanocomposites have a large saturation magnetizations that made them can move regularly under an external magnetic field. Significantly, FGO nanocomposites also exhibit enhanced electric double-layer capacitor (EDLC) activity compared with pure Fe3O4 NCs and GO in terms of specific capacitance and high-rate charge-discharge.

Vanadium Compounds as PTP Inhibitors

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Elsa Irving

2017-12-01

Full Text Available Phosphotyrosine signaling is regulated by the opposing actions of protein tyrosine kinases (PTKs and protein tyrosine phosphatases (PTPs. Here we discuss the potential of vanadium derivatives as PTP enzyme inhibitors and metallotherapeutics. We describe how vanadate in the V oxidized state is thought to inhibit PTPs, thus acting as a pan-inhibitor of this enzyme superfamily. We discuss recent developments in the biological and biochemical actions of more complex vanadium derivatives, including decavanadate and in particular the growing number of oxidovanadium compounds with organic ligands. Pre-clinical studies involving these compounds are discussed in the anti-diabetic and anti-cancer contexts. Although in many cases PTP inhibition has been implicated, it is also clear that many such compounds have further biochemical effects in cells. There also remain concerns surrounding off-target toxicities and long-term use of vanadium compounds in vivo in humans, hindering their progress through clinical trials. Despite these current misgivings, interest in these chemicals continues and many believe they could still have therapeutic potential. If so, we argue that this field would benefit from greater focus on improving the delivery and tissue targeting of vanadium compounds in order to minimize off-target toxicities. This may then harness their full therapeutic potential.

Highly Controlled Diffusion Drug Release from Ureasil-Poly(ethylene oxide)-Na+-Montmorillonite Hybrid Hydrogel Nanocomposites.

Science.gov (United States)

Jesus, Celso R N; Molina, Eduardo F; Pulcinelli, Sandra H; Santilli, Celso V

2018-06-06

In this work, we report the effects of incorporation of variable amounts (1-20 wt %) of sodium montmorillonite (MMT) into a siloxane-poly(ethylene oxide) hybrid hydrogel prepared by the sol-gel route. The aim was to control the nanostructural features of the nanocomposite, improve the release profile of the sodium diclofenac (SDCF) drug, and optimize the swelling behavior of the hydrophilic matrix. The nanoscopic characteristics of the siloxane-cross-linked poly(ethylene oxide) network, the semicrystallinity of the hybrid, and the intercalated or exfoliated structure of the clay were investigated by X-ray diffraction, small-angle X-ray scattering, and differential scanning calorimetry. The correlation between the nanoscopic features of nanocomposites containing different amounts of MMT and the swelling behavior revealed the key role of exfoliated silicate in controlling the water uptake by means of a flow barrier effect. The release of the drug from the nanocomposite displayed a stepped pattern kinetically controlled by the diffusion of SDCF molecules through the mass transport barrier created by the exfoliated silicate. The sustained SDCF release provided by the hybrid hydrogel nanocomposite could be useful for the prolonged treatment of painful conditions, such as arthritis, sprains and strains, gout, migraine, and pain after surgical procedures.

Reduced graphene oxide-germanium quantum dot nanocomposite: electronic, optical and magnetic properties

Science.gov (United States)

Amollo, Tabitha A.; Mola, Genene T.; Nyamori, Vincent O.

2017-12-01

Graphene provides numerous possibilities for structural modification and functionalization of its carbon backbone. Localized magnetic moments can, as well, be induced in graphene by the formation of structural defects which include vacancies, edges, and adatoms. In this work, graphene was functionalized using germanium atoms, we report the effect of the Ge ad atoms on the structural, electrical, optical and magnetic properties of graphene. Reduced graphene oxide (rGO)-germanium quantum dot nanocomposites of high crystalline quality were synthesized by the microwave-assisted solvothermal reaction. Highly crystalline spherical shaped germanium quantum dots, of diameter ranging between 1.6-9.0 nm, are anchored on the basal planes of rGO. The nanocomposites exhibit high electrical conductivity with a sheet resistance of up to 16 Ω sq-1. The electrical conductivity is observed to increase with the increase in Ge content in the nanocomposites. High defect-induced magnetization is attained in the composites via germanium adatoms. The evolution of the magnetic moments in the nanocomposites and the coercivity showed marked dependence on the Ge quantum dots size and concentration. Quantum confinement effects is evidenced in the UV-vis absorbance spectra and photoluminescence emission spectra of the nanocomposites which show marked size-dependence. The composites manifest strong absorption in the UV region, strong luminescence in the near UV region, and a moderate luminescence in the visible region.

The tunable plasma synthesis of Pt-reduced graphene oxide nanocomposites

Directory of Open Access Journals (Sweden)

Yulong Ma

2017-06-01

Full Text Available Herein, we have developed Pt-plasma reduced graphene oxide (Pt/P-rGO catalysts displaying high overpotentials for methanol oxidation reaction (MOR through facile and tunable plasma treatments. We provide insight into the improved performance of these catalysts by combining electrochemical measurements with microscopic and spectroscopic characterization techniques. The analysis results showed that the Pt nanoparticles (NPs were successfully deposited on P-rGO. The deposition and uniformity of Pt NPs were influenced by tuning the discharge power of the plasma. The catalytic performance towards the methanol oxidation reaction is investigated. The Pt/P-rGO NPs composites under 100 W show the best electrocatalytic activity. These results were vital to the further application of graphene-based metal nanocomposites synthesized by plasma technology.

Synergetic effect of graphene oxide-carbon nanotube on nanomechanical properties of acrylonitrile butadiene styrene nanocomposites

Science.gov (United States)

Jyoti, Jeevan; Pratap Singh, Bhanu; Chockalingam, Sreekumar; Joshi, Amish G.; Gupta, Tejendra K.; Dhakate, S. R.

2018-04-01

Herein, multiwall carbon nanotubes (MWCNTs), reduced graphene oxide (rGO), graphene oxide-carbon nanotubes (GCNTs) hybrid reinforced acrylonitrile butadiene styrene (ABS) nanocomposites have been prepared by micro twin screw extruder with back flow channel and the effect of different type of fillers on the nanomechanical properties are studied. The combination of both graphene oxide and CNT has enhanced the dispersion in polymer matrix and lower the probability of CNTs aggregation. GCNTs hybrid have been synthesized via novel chemical route and well characterized using Raman spectroscopic technique. The nanoindentation hardness and elastic modulus of GCNTs-ABS hybrid nanocomposites were improved from 211.3 MPa and 4.12 GPa of neat ABS to 298.9 MPa and 6.02 GPa, respectively at 5wt% GCNTs loading. In addition to hardness and elastic modulus, other mechanical properties i.e. plastic index parameter, elastic recovery, ratio of residual displacement after load removal and displacement at the maximum load and plastic deformation energy have also been investigated. These results were correlated with Raman and X-ray photoelectron spectroscopic (XPS) techniques and microstructural characterizations (scanning electron microscopy). Our demonstration would provide guidelines for the fabrication of hard and scratches nanocomposite materials for potential use in, automotive trim components and bumper bars, carrying cases and electronic industries and electromagnetic interference shielding.

Non-enzymatic glucose sensing platform using self assembled cobalt oxide/graphene nanocomposites immobilized graphite modified electrode

DEFF Research Database (Denmark)

Vivekananth, R.; Babu, R. Suresh; Prasanna, K.

2018-01-01

A new strategy to prepare the densely packed cobalt oxide (Co3O4)/graphene nanocomposites by a self-assembly method were adopted in this work. A new non-enzymatic glucose determination has been fabricated by using Co3O4/graphene nanocomposites modified electrode as a sensing material. The nanocom...... of the modified electrode for glucose determination has been evaluated in urine samples....

Enhanced catalytic and dopamine sensing properties of electrochemically reduced conducting polymer nanocomposite doped with pure graphene oxide.

Science.gov (United States)

Wang, Wenting; Xu, Guiyun; Cui, Xinyan Tracy; Sheng, Ge; Luo, Xiliang

2014-08-15

Significantly enhanced catalytic activity of a nanocomposite composed of conducting polymer poly (3,4-ethylenedioxythiophene) (PEDOT) doped with graphene oxide (GO) was achieved through a simple electrochemical reduction process. The nanocomposite (PEDOT/GO) was electrodeposited on an electrode and followed by electrochemical reduction, and the obtained reduced nanocomposite (PEDOT/RGO) modified electrode exhibited lowered electrochemical impedance and excellent electrocatalytic activity towards the oxidation of dopamine. Based on the excellent catalytic property of PEDOT/RGO, an electrochemical sensor capable of sensitive and selective detection of DA was developed. The fabricated sensor can detect DA in a wide linear range from 0.1 to 175μM, with a detection limit of 39nM, and it is free from common interferences such as uric acid and ascorbic acid. Copyright © 2014 Elsevier B.V. All rights reserved.

Vanadium Recovery from Oil Fly Ash by Carbon Removal and Roast-Leach Process

Science.gov (United States)

Jung, Myungwon; Mishra, Brajendra

2018-02-01

This research mainly focuses on the recovery of vanadium from oil fly ash by carbon removal and the roast-leach process. The oil fly ash contained about 85% unburned carbon and 2.2% vanadium by weight. A vanadium-enriched product was obtained after carbon removal, and the vanadium content of this product was 19% by weight. Next, the vanadium-enriched product was roasted with sodium carbonate to convert vanadium oxides to water-soluble sodium metavanadate. The roasted sample was leached with water at 60°C, and the extraction percentage of vanadium was about 92% by weight. Several analytical techniques, such as inductively coupled plasma atomic emission spectroscopy (ICP-AES), x-ray fluorescence (XRF), and thermogravimetric and differential thermal analysis (TG-DTA), were utilized for sample analyses. Thermodynamic modeling was also conducted with HSC chemistry software to explain the experimental results.

An overview of the oxidation performance of silicide diffusion coatings for vanadium-based alloys for generation IV reactors

International Nuclear Information System (INIS)

Chaia, N.; Mathieu, S.; Cozzika, T.; Rouillard, F.; Desgranges, C.; Courouau, J.L.; Petitjean, C.; David, N.; Vilasi, M.

2013-01-01

Highlights: ► Diffusion barrier to oxygen were manufactured by pack cementation diffusion process. ► The use of CrSi 2 + Si and TiSi 2 + Si as masteralloys increased the quality of the coating. ► Thermodynamic stability (coatings/vanadium) was obtained at the operating temperature. ► MSi 2 coatings developed low growing oxide scale in air and at low oxygen pressure. ► Coatings presented high compatibility with liquid sodium ( 2 ) for 360 h. - Abstract: This study focuses on the development of new protective coatings for the vanadium-based alloy V-4Cr-4Ti. Halide-activated pack-cementation (HAPC) technique was used to develop V x Si y multilayered diffusive silicide coatings. The outer layers (coatings) were formed of VSi 2 doped with 27 at.% Cr or TiSi 2 . These compounds exhibited a very low oxidation rate at 650 °C, both in air and at a low oxygen pressure (He, 5 ppm O 2 ). The coatings formed mainly of MSi 2 were found to be insensitive to pesting and largely unreactive to liquid sodium ( 2 ) during a 360 h compatibility test at 550 °C.

Electrical properties improvement of multicrystalline silicon solar cells using a combination of porous silicon and vanadium oxide treatment

International Nuclear Information System (INIS)

Derbali, L.; Ezzaouia, H.

2013-01-01

In this paper, we will report the enhancement of the conversion efficiency of multicrystalline silicon solar cells after coating the front surface with a porous silicon layer treated with vanadium oxide. The incorporation of vanadium oxide into the porous silicon (PS) structure, followed by a thermal treatment under oxygen ambient, leads to an important decrease of the surface reflectivity, a significant enhancement of the effective minority carrier lifetime (τ eff ) and a significant enhancement of the photoluminescence (PL) of the PS structure. We Obtained a noticeable increase of (τ eff ) from 3.11 μs to 134.74 μs and the surface recombination velocity (S eff ) have decreased from 8441 cm s −1 to 195 cm s −1 . The reflectivity spectra of obtained films, performed in the 300–1200 nm wavelength range, show an important decrease of the average reflectivity from 40% to 5%. We notice a significant improvement of the internal quantum efficiency (IQE) in the used multicrystalline silicon substrates. Results are analyzed and compared to those carried out on a reference (untreated) sample. The electrical properties of the treated silicon solar cells were improved noticeably as regard to the reference (untreated) sample.

Impressive nonlinear optical response exhibited by Poly(vinylidene fluoride) (PVDF)/reduced graphene oxide (RGO) nanocomposite films

Science.gov (United States)

Sabira, K.; Saheeda, P.; Divyasree, M. C.; Jayalekshmi, S.

2017-12-01

In the present work, the nonlinear optical properties of free-standing films of Poly(vinylidene fluoride) (PVDF)/reduced graphene oxide (RGO) nanocomposite are investigated to assess their suitability as efficient optical limiters. The PVDF/RGO nanocomposite films are generated by mixing different concentrations of RGO as the filler, with PVDF, using solution casting method. The XRD and FTIR data of these nanocomposite films confirm the enhancement in the β phase of PVDF when RGO is added to PVDF, which is one of the prime factors, enhancing the nonlinear response of the nanocomposite. The open aperture and closed aperture Z-scan technique under nanosecond excitation (532 nm, 7 ns) is used to investigate the nonlinear optical characteristics of the PVDF/RGO nanocomposite films. These films are found to exhibit two photon absorption assisted optical non linearity in the nanosecond regime. The highlight of the present work is the observation of quite low values of the normalized transmittance and low optical limiting threshold power in free standing films of PVDF/RGO nanocomposite. These flexible, free-standing and stable nanocomposite films offer high application prospects in the design of efficient optical limiting devices of any desired size or shape.

Effect of temperature on the structural, linear, and nonlinear optical properties of MgO-doped graphene oxide nanocomposites

Science.gov (United States)

Kimiagar, Salimeh; Abrinaei, Fahimeh

2018-01-01

Magnesium oxide (MgO)-graphene oxide (GO) nanocomposites were prepared by the hydrothermal method at different temperatures. The effect of growth temperature on the structural, linear, and nonlinear optical (NLO) parameters was investigated. The decoration of MgO on GO sheets was confirmed by X-ray diffraction, scanning electron microscopy, Fourier transform infrared, and UV-visible (UV-vis) spectroscopy analyses. The energy band-gaps of MgO-GO nanocomposites were calculated from UV-vis spectrum using Tauc plot. The NLO parameters of MgO-GO nanocomposites were calculated for the first time by the simple Z-scan technique with nanosecond Nd:YAG laser at 532 nm. The nonlinear absorption coefficient β and nonlinear refractive index n2 for MgO-GO nanocomposites at the laser intensity of 1.1×108 W/cm2 were measured to be in the order of 10-7 cm/W and 10-12 cm2/W, respectively. The third-order NLO susceptibility of MgO-GO nanocomposites was measured in the order of 10-9 esu. The results showed that MgO-GO structures have negative nonlinearity as well as good nonlinear two-photon absorption at 532 nm. Furthermore, the NLO parameters increased by the enhancement of the growth temperature. As the investigation of new materials plays an important role in the advancement of optoelectronics, MgO-GO nanocomposites possess potential applications in NLO devices.

Evaluation of dosimetric characteristics of graphene oxide/PVC nanocomposite for gamma radiation applications

Energy Technology Data Exchange (ETDEWEB)

Feizi, Shahzad; Malekie, Shahryar; Ziaie, Farhood [Nuclear Science and Technology Research Institute (NSTRI), Karaj (Iran, Islamic Republic of). Radiation Application Research School; Rahighi, Reza; Tayyebi, Ahmad [Univ. of Technology, Tehran (Iran, Islamic Republic of). Dept. of Physics

2017-04-01

Graphene oxide-polyvinyl chloride composite was prepared using tetrahydrofuran solvent-assisted dispersion of characterized nano flakes of graphene oxide in polymer matrix. Electrical percolation threshold of GO/PVC nanocomposite was determined via a finite element simulation method with a 2D model and compared with experimental results. A conductive cell with two silver coated walls was designed and fabricated for exploring dosimetric properties of the composite. Some characteristics of the new nanocomposite such as linearity of dose response, repeatability, sensitivity and angular dependence are investigated. According to 2D proposed method, obtained data associated to electrical conductivity of the GO/polymer composite for PVC matrix plotted in different GO weight percentages and had good compatibility (validity) with experimental data. The dose response is linear in the 17-51 mGy dose range and it can be introduced for gamma radiation dosimetry in diagnostic activities.

Low-temperature direct synthesis of mesoporous vanadium nitrides for electrochemical capacitors

Science.gov (United States)

Lee, Hae-Min; Jeong, Gyoung Hwa; Kim, Sang-Wook; Kim, Chang-Koo

2017-04-01

Mesoporous vanadium nitrides are directly synthesized by a one-step chemical precipitation method at a low temperature (70 °C). Structural and morphological analyses reveal that vanadium nitride consist of long and slender nanowhiskers, and mesopores with diameters of 2-5 nm. Compositional analysis confirms the presence of vanadium in the VN structure, along with oxidized vanadium. The cyclic voltammetry and charge-discharge tests indicate that the obtained material stores charges via a combination of electric double-layer capacitance and pseudocapacitance mechanisms. The vanadium nitride electrode exhibits a specific capacitance of 598 F/g at a current density of 4 A/g. After 5000 charge-discharge cycles, the electrode has an equivalent series resistance of 1.42 Ω and retains 83% of its initial specific capacitance. This direct low-temperature synthesis of mesoporous vanadium nitrides is a simple and promising method to achieve high specific capacitance and low equivalent series resistance for electrochemical capacitor applications.

A comparative study of silver-graphene oxide nanocomposites as a recyclable catalyst for the aerobic oxidation of benzyl alcohol: Support effect

Energy Technology Data Exchange (ETDEWEB)

Zahed, Bahareh; Hosseini-Monfared, Hassan, E-mail: monfared@znu.ac.ir

2015-02-15

Graphical abstract: - Highlights: • Characteristics of three different graphene oxide (GO) are studied as a support for Ag nanoparticles. • The required conditions for a best support are determined. • For the first time the silver nanoparticles decorated GO as catalyst for aerobic oxidation of benzyl alcohol and the effects of the degree of reduction of GO on AgNPs on GO are reported. - Abstract: Three different nanocomposites of silver and graphene oxide, namely silver nanoparticles (AgNPs) immobilized on reduced graphene oxide (AgNPs/rGO), partially reduced graphene oxide (AgNPs/GO) and thiolated partially reduced graphene oxide (AgNPs/GOSH), were synthesized in order to compare their properties. Characterizations were carried out by infrared and UV–Vis and Raman spectroscopy, ICP, X-ray diffraction, SEM and TEM, confirming both the targeted chemical modification and the composite formation. The nanocomposites were successfully employed in the aerobic oxidation of benzyl alcohol at atmospheric pressure. AgNPs/GOSH is stable and recyclable catalyst which showed the highest activity in the aerobic oxidation of benzyl alcohol in the presence of N-hydroxyphthalimide (NHPI) to give benzaldehyde with 58% selectivity in 24 h at 61% conversion. The favorite properties of AgNPs/GOSH are reasonably attributed to the stable and well distributed AgNPs over GOSH due to strong adhesion between AgNPs and GOSH.

Interaction of titanium and vanadium with carbon dioxide under heating

International Nuclear Information System (INIS)

Vlasyuk, R.Z.; Kurovskij, V.Ya.; Lyapunov, V.P.; Radomysel'skij, I.D.

1986-01-01

The methods of gravitmetric and X-ray phase analysis as well as analysis of composition of gases in the heating chamber have been used to investigate the mechanism of titanium and vanadium interaction with carbon dioxide in the 300-1000 deg C temperature range. The analogy of mechanisms of the interaction of titanium and vanadium with carbon dioxide in oxides production on the metal surface with subsequent carbidizing treatment at temperatures above 800 deg C is shown. Temperature limits of material operation on the base of titanium or vanadium in carbon dioxide must not exceed 400 or 600 deg C, respectively

Low-temperature direct synthesis of mesoporous vanadium nitrides for electrochemical capacitors

Energy Technology Data Exchange (ETDEWEB)

Lee, Hae-Min [Institute of NT-IT Fusion Technology, Ajou University, 206 Worldcup-ro, Yeongtong-gu, Suwon 16499 (Korea, Republic of); Jeong, Gyoung Hwa [Department of Chemistry, Ulsan National Institute of Science and Technology (UNIST), Banyeon 100, Ulsan 44919 (Korea, Republic of); Kim, Sang-Wook [Department of Molecular Science and Technology, Ajou University, 206 Worldcup-ro, Yeongtong-gu, Suwon 16499 (Korea, Republic of); Kim, Chang-Koo, E-mail: changkoo@ajou.ac.kr [Department of Chemical Engineering and Department of Energy Systems Research, Ajou University, 206 Worldcup-ro, Yeongtong-gu, Suwon 16499 (Korea, Republic of)

2017-04-01

Highlights: • Vanadium nitrides were directly synthesized by a one-step chemical precipitation method. • This method was carried out at a low temperature of 70 °C. • Vanadium nitrides had a specific capacitance of 598 F/g. • The equivalent series resistance of the vanadium nitride electrode was 1.42 Ω after 5000 cycles. - Abstract: Mesoporous vanadium nitrides are directly synthesized by a one-step chemical precipitation method at a low temperature (70 °C). Structural and morphological analyses reveal that vanadium nitride consist of long and slender nanowhiskers, and mesopores with diameters of 2–5 nm. Compositional analysis confirms the presence of vanadium in the VN structure, along with oxidized vanadium. The cyclic voltammetry and charge-discharge tests indicate that the obtained material stores charges via a combination of electric double-layer capacitance and pseudocapacitance mechanisms. The vanadium nitride electrode exhibits a specific capacitance of 598 F/g at a current density of 4 A/g. After 5000 charge-discharge cycles, the electrode has an equivalent series resistance of 1.42 Ω and retains 83% of its initial specific capacitance. This direct low-temperature synthesis of mesoporous vanadium nitrides is a simple and promising method to achieve high specific capacitance and low equivalent series resistance for electrochemical capacitor applications.

Structure and function of vanadium haloperoxidases

NARCIS (Netherlands)

Wever, R.; Michibata, H.

2012-01-01

Vanadium haloperoxidases contain the bare metal oxide vanadate as a prosthetic group and differ strongly from the heme peroxidases in substrate specificity and molecular properties. The substrates of these enzymes are limited to halides and sulfides, which in the presence of hydrogen peroxide are

The electrical properties of semiconducting vanadium phosphate glasses

International Nuclear Information System (INIS)

Moridi, G.R.; Hogarth, C.A.; Hekmat Shooar, N.H.

1984-01-01

Vanadium phosphate glasses are a group of oxide glasses which show the semiconducting behaviour. In contrast to the conventional glasses, the conduction mechanism in these glasses is electronic, rather than being ionic. Since 1954, when the first paper appeared on the semiconducting properties of these glasses, much work has been carried out on transition-metal-oxide glasses in general, and vanadium phosphate glasses in particular. The mechanism of conduction is basicaly due to the transport of electrons between the transition-metal ions in different valency states. In the present paper, we have reviewed the previous works on the electrical characteristics of P 2 O 5 -V 2 O 5 glasses and also discussed the current theoretical ideas relevant for the interpretation of the experimental data

Chemical vapour deposition of vanadium oxide thermochromic thin films

Science.gov (United States)

Piccirillo, Clara

Thermochromic materials change optical properties, such as transmittance or reflectance, with a variation in temperature. An ideal intelligent (smart) material will allow solar radiation in through a window in cold conditions, but reflect that radiation in warmer conditions. The variation in the properties is often associated with a phase change, which takes place at a definite temperature, and is normally reversible. Such materials are usually applied to window glass as thin films. This thesis presents the work on the development of thermochromic vanadium (IV) oxide (VO2) thin films - both undoped and doped with tungsten, niobium and gold nanoparticles - which could be employed as solar control coatings. The films were deposited using Chemical Vapour Deposition (CVD), using improved Atmospheric Pressure (APCVD), novel Aerosol Assisted (AACVD) and novel hybrid AP/AACVD techniques. The effects of dopants on the metalto- semiconductor transition temperature and transmittance/reflectance characteristics were also investigated. This work significantly increased the understanding of the mechanisms behind thermochromic behaviour, and resulted in thermochromic materials based on VO2 with greatly improved properties.

Characterization of thermal reaction of aluminum/copper (II) oxide/poly(tetrafluoroethene) nanocomposite by thermogravimetric analysis, differential scanning calorimetry, mass spectrometry and X-ray diffraction

International Nuclear Information System (INIS)

Li, Xiangyu; Yang, Hongtao; Li, Yan-chun

2015-01-01

Highlights: • The thermal reaction properties of the Al/CuO/PTFE nanocomposite were investigated. • The Al/PTFE and CuO/PTFE nanocomposites were prepared and tested for comparison. • TG/DSC–MS and XRD analysis were performed. • PTFE is oxidizing Al and reducing CuO during the thermal decomposition. - Abstract: The application of fluoropolymers as reactive agent in energetic materials have attracted significant interest recently. In this study, the thermal reaction properties of the aluminum nanoparticles/copper (II) oxide nanoparticles/poly(tetrafluoroethene) (Al-NPs/CuO-NPs/PTFE) nanocomposite (mass ratio of Al-NPs/CuO-NPs/PTFE = 20/60/20) were investigated by means of thermogravimetry/differential scanning calorimetry–mass spectrometry (TG/DSC–MS) and X-ray diffraction (XRD) analyses. The Al-NPs/PTFE (mass ratio of Al-NPs/PTFE = 50/50) and CuO-NPs/PTFE (mass ratio of CuO-NPs/PTFE = 75/25) nanocomposites were also prepared and tested for comparison. It is observed that PTFE is acting as both oxidizer and reducer during the thermal decomposition process of Al-NPs/CuO-NPs/PTFE nanocomposites. Before 615 °C, PTFE is oxidized by CuO-NPs and oxidizing Al-NPs, resulting mass reduction. After 615 °C, the excessive aluminum and copper (I)/copper (II) oxide will proceed the exothermic condensed phase reaction.

Electrical conductivity of activated carbon-metal oxide nanocomposites under compression: a comparison study.

Science.gov (United States)

Barroso-Bogeat, A; Alexandre-Franco, M; Fernández-González, C; Macías-García, A; Gómez-Serrano, V

2014-12-07

From a granular commercial activated carbon (AC) and six metal oxide (Al2O3, Fe2O3, SnO2, TiO2, WO3 and ZnO) precursors, two series of AC-metal oxide nanocomposites were prepared by wet impregnation, oven-drying at 120 °C, and subsequent heat treatment at 200 or 850 °C in an inert atmosphere. Here, the electrical conductivity of the resulting products was studied under moderate compression. The influence of the applied pressure, sample volume, mechanical work, and density of the hybrid materials was thoroughly investigated. The DC electrical conductivity of the compressed samples was measured at room temperature by the four-probe method. Compaction assays suggest that the mechanical properties of the nanocomposites are largely determined by the carbon matrix. Both the decrease in volume and the increase in density were relatively small and only significant at pressures lower than 100 kPa for AC and most nanocomposites. In contrast, the bulk electrical conductivity of the hybrid materials was strongly influenced by the intrinsic conductivity, mean crystallite size, content and chemical nature of the supported phases, which ultimately depend on the metal oxide precursor and heat treatment temperature. The supported nanoparticles may be considered to act as electrical switches either hindering or favouring the effective electron transport between the AC cores of neighbouring composite particles in contact under compression. Conductivity values as a rule were lower for the nanocomposites than for the raw AC, all of them falling in the range of semiconductor materials. With the increase in heat treatment temperature, the trend is toward the improvement of conductivity due to the increase in the crystallite size and, in some cases, to the formation of metals in the elemental state and even metal carbides. The patterns of variation of the electrical conductivity with pressure and mechanical work were slightly similar, thus suggesting the predominance of the pressure

Multifunctional zirconium oxide doped chitosan based hybrid nanocomposites as bone tissue engineering materials.

Science.gov (United States)

Bhowmick, Arundhati; Jana, Piyali; Pramanik, Nilkamal; Mitra, Tapas; Banerjee, Sovan Lal; Gnanamani, Arumugam; Das, Manas; Kundu, Patit Paban

2016-10-20

This paper reports the development of multifunctional zirconium oxide (ZrO2) doped nancomposites having chitosan (CTS), organically modified montmorillonite (OMMT) and nano-hydroxyapatite (HAP). Formation of these nanocomposites was confirmed by various characterization techniques such as Fourier transform infrared spectroscopy and powder X-ray diffraction. Scanning electron microscopy images revealed uniform distribution of OMMT and nano-HAP-ZrO2 into CTS matrix. Powder XRD study and TEM study revealed that OMMT has partially exfoliated into the polymer matrix. Enhanced mechanical properties in comparison to the reported literature were obtained after the addition of ZrO2 nanoparticle into the nanocomposites. In rheological measurements, CMZH I-III exhibited greater storage modulus (G') than loss modulus (G″). TGA results showed that these nanocomposites are thermally more stable compare to pure CTS film. Strong antibacterial zone of inhibition and the lowest minimum inhibition concentration (MIC) value of these nanocomposites against bacterial strains proved that these materials have the ability to prevent bacterial infection in orthopedic implants. Compatibility of these nanocomposites with pH and blood of human body was established. It was observed from the swelling study that the swelling percentage was increased with decreasing the hydrophobic OMMT content. Human osteoblastic MG-63 cell proliferations were observed on the nanocomposites and cytocompatibility of these nanocomposites was also established. Moreover, addition of 5wt% OMMT and 5wt% nano-HAP-ZrO2 into 90wt% CTS matrix provides maximum tensile strength, storage modulus, aqueous swelling and cytocompatibility along with strong antibacterial effect, pH and erythrocyte compatibility. Copyright © 2016 Elsevier Ltd. All rights reserved.

Hydration effects on the molecular structure of silica-supported vanadium oxide catalysts: A combined IR, Raman, UV–vis and EXAFS study

NARCIS (Netherlands)

Keller, D.E.; Visser, T.; Soulimani, F.; Koningsberger, D.C.; Weckhuysen, B.M.

2007-01-01

The effect of hydration on the molecular structure of silica-supported vanadium oxide catalysts with loadings of 1–16 wt.% V has been systematically investigated by infrared, Raman, UV–vis and EXAFS spectroscopy. IR and Raman spectra recorded during hydration revealed the formation of V–OH groups,

Simultaneous Oxidation and Sequestration of As(III) from Water by Using Redox Polymer-Based Fe(III) Oxide Nanocomposite.

Science.gov (United States)

Zhang, Xiaolin; Wu, Mengfei; Dong, Hao; Li, Hongchao; Pan, Bingcai

2017-06-06

Water decontamination from As(III) is an urgent but still challenging task. Herein, we fabricated a bifunctional nanocomposite HFO@PS-Cl for highly efficient removal of As(III), with active chlorine covalently binding spherical polystyrene host for in situ oxidation of As(III) to As(V), and Fe(III) hydroxide (HFO) nanoparticles (NPs) embedded inside for specific As(V) removal. HFO@PS-Cl could work effectively in a wide pH range (5-9), and other substances like sulfate, chloride, bicarbonate, silicate, and humic acid exert insignificant effect on As(III) removal. As(III) sequestration is realized via two pathways, that is, oxidation to As(V) by the active chlorine followed by specific As(V) adsorption onto HFO NPs, and As(III) adsorption onto HFO NPs followed by oxidation to As(V). The exhausted HFO@PS-Cl could be refreshed for cyclic runs with insignificant capacity loss by the combined regeneration strategy, that is, alkaline solution to rinse the adsorbed As(V) and NaClO solution to renew the host oxidation capability. In addition, fixed-bed experiments demonstrated that the HFO@PS-Cl column could generate >1760 bed volume (BV) effluent from a synthetic As(III)-containing groundwater to meet the drinking water standard (nanocomposites, HFO@PS-N and HFO@D201 could only generate 450 and 600 BV effluents under otherwise identical conditions.

Investigation of optical properties of aluminium oxide doped polystyrene polymer nanocomposite films

Science.gov (United States)

Bhavsar, Shilpa; Patel, Gnansagar B.; Singh, N. L.

2018-03-01

In the present work, a simple solution casting method was utilized to synthesize aluminium oxide (Al2O3) doped polystyrene (PS) polymer nanocomposite films. As synthesized films were characterized using X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, ultra violet (UV)-visible spectroscopy, photoluminescence (PL) method and scanning electron microscopy (SEM). The crystalline nature of the films was found to decrease after incorporation of filler in the polymer matrix as revealed by XRD results. A new carbonyl group was appeared in the FTIR spectra and confirmed the charge transfer reaction between filler and polymer matrix. The decrease in the band gap was found with the filler concentration in the synthesized polymer nanocomposite films. Photoluminescence emission spectra of nanocomposites were observed at 411 nm, 435 nm and 462 nm, respectively in violet-blue region which indicates interaction between the dopant and the polymer matrix. The PL emission spectra of polymer nanocomposite films with 3 wt% of Al2O3 filler exhibited higher peak intensity. The Al2O3 filler dispersion is found to reduce band gap and promote luminescence property in polystyrene. SEM analysis indicates the agglomeration of Al2O3 nanoparticles into PS matrix at higher concentration.

Graphene oxide-silver nanocomposite as a promising biocidal agent against methicillin-resistant Staphylococcus aureus.

Science.gov (United States)

de Moraes, Ana Carolina Mazarin; Lima, Bruna Araujo; de Faria, Andreia Fonseca; Brocchi, Marcelo; Alves, Oswaldo Luiz

2015-01-01

Methicillin-resistant Staphylococcus aureus (MRSA) has been responsible for serious hospital infections worldwide. Nanomaterials are an alternative to conventional antibiotic compounds, because bacteria are unlikely to develop microbial resistance against nanomaterials. In the past decade, graphene oxide (GO) has emerged as a material that is often used to support and stabilize silver nanoparticles (AgNPs) for the preparation of novel antibacterial nanocomposites. In this work, we report the synthesis of the graphene-oxide silver nanocomposite (GO-Ag) and its antibacterial activity against relevant microorganisms in medicine. GO-Ag nanocomposite was synthesized through the reduction of silver ions (Ag(+)) by sodium citrate in an aqueous GO dispersion, and was extensively characterized using ultraviolet-visible absorption spectroscopy, X-ray diffraction, thermogravimetric analysis, X-ray photoelectron spectroscopy, and transmission electron microscopy. The antibacterial activity was evaluated by microdilution assays and time-kill experiments. The morphology of bacterial cells treated with GO-Ag was investigated via transmission electron microscopy. AgNPs were well distributed throughout GO sheets, with an average size of 9.4±2.8 nm. The GO-Ag nanocomposite exhibited an excellent antibacterial activity against methicillin-resistant S. aureus, Acinetobacter baumannii, Enterococcus faecalis, and Escherichia coli. All (100%) MRSA cells were inactivated after 4 hours of exposure to GO-Ag sheets. In addition, no toxicity was found for either pristine GO or bare AgNPs within the tested concentration range. Transmission electronic microscopy images offered insights into how GO-Ag nanosheets interacted with bacterial cells. Our results indicate that the GO-Ag nanocomposite is a promising antibacterial agent against common nosocomial bacteria, particularly antibiotic-resistant MRSA. Morphological injuries on MRSA cells revealed a likely loss of viability as a result of the

Hierarchical Nanocomposites of Polyaniline Nanowire Arrays on Reduced Graphene Oxide Sheets for Supercapacitors

Science.gov (United States)

Wang, Li; Ye, Yinjian; Lu, Xingping; Wen, Zhubiao; Li, Zhuang; Hou, Haoqing; Song, Yonghai

2013-12-01

Here we reported a novel route to synthesize a hierarchical nanocomposite (PANI-frGO) of polyaniline (PANI) nanowire arrays covalently bonded on reduced graphene oxide (rGO). In this strategy, nitrophenyl groups were initially grafted on rGO via C-C bond, and then reduced to aminophenyl to act as anchor sites for the growth of PANI arrays on rGO. The functionalized process was confirmed by atomic force microscopy, scanning electron microscopy, Fourier transform infrared spectroscopy, Raman spectroscopy and thermogravimetric analysis. The electrochemical properties of the PANI-frGO as supercapacitor materials were investigated. The PANI-frGO nanocomposites showed high capacitance of 590 F g-1 at 0.1 A g-1, and had no loss of capacitance after 200 cycles at 2 A g-1. The improved electrochemical performance suggests promising application of the PANI-frGO nanocomposites in high-performance supercapacitors.

Synthesis and characterization of Zinc (II)-loaded Zeolite/Graphene oxide nanocomposite as a new drug carrier

Energy Technology Data Exchange (ETDEWEB)

Khatamian, M. [Inorganic Chemistry Department, Faculty of Chemistry, University of Tabriz, C.P. 51664 Tabriz (Iran, Islamic Republic of); Divband, B., E-mail: baharakdivband@yahoo.com [Research Center for Pharmaceutical Nanotechnology, Tabriz University of Medical Sciences, Tabriz (Iran, Islamic Republic of); Inorganic Chemistry Department, Faculty of Chemistry, University of Tabriz, C.P. 51664 Tabriz (Iran, Islamic Republic of); Farahmand-zahed, F. [Inorganic Chemistry Department, Faculty of Chemistry, University of Tabriz, C.P. 51664 Tabriz (Iran, Islamic Republic of)

2016-09-01

Current research has focused on the preparation of Zinc-clinoptilolite/Graphene Oxide (Zn-Clin/GO) hybrid nanostructure and investigating its biocompatibility for the first time. As prepared samples were characterized by X-ray diffraction (XRD), Scanning electron microscopy (SEM), Thermo gravimetric analysis (TGA) and Fourier transform infrared (FT-IR). In order to use it as a drug carrier two important factors were investigated: cytocompatibility of nanocomposites and their drug loading capacity. The results showed that the prepared nanocomposite is cytocompatible and its high loading capacity and slow release performance for Doxorubicin (DOX), as a cancer drug, proved that it can be used as a drug carrier. At last in-vitro toxicity of DOX loaded nanocomposite was compared with pure DOX. - Graphical abstract: Biocompatible Zn-clinoptilolite/Graphene oxide hybrid nanostructure as in vitro drug delivery systems (DDS) was able to store and release substantial amounts of doxorubicin to the lung cancer cell lines. Display Omitted - Highlights: • Zn-Clin/GO nanocomposite as a new in vitro drug carrier with high loading capacity is synthesized. • Two synthesis methods (Microwave assisted hydrothermal method and Reflux method) are used. • All of the carriers (Zn-Clin, Zn-Clin/GO, GO) showed high biocompatibility.

Synthesis and characterization of Zinc (II)-loaded Zeolite/Graphene oxide nanocomposite as a new drug carrier

International Nuclear Information System (INIS)

Khatamian, M.; Divband, B.; Farahmand-zahed, F.

2016-01-01

Current research has focused on the preparation of Zinc-clinoptilolite/Graphene Oxide (Zn-Clin/GO) hybrid nanostructure and investigating its biocompatibility for the first time. As prepared samples were characterized by X-ray diffraction (XRD), Scanning electron microscopy (SEM), Thermo gravimetric analysis (TGA) and Fourier transform infrared (FT-IR). In order to use it as a drug carrier two important factors were investigated: cytocompatibility of nanocomposites and their drug loading capacity. The results showed that the prepared nanocomposite is cytocompatible and its high loading capacity and slow release performance for Doxorubicin (DOX), as a cancer drug, proved that it can be used as a drug carrier. At last in-vitro toxicity of DOX loaded nanocomposite was compared with pure DOX. - Graphical abstract: Biocompatible Zn-clinoptilolite/Graphene oxide hybrid nanostructure as in vitro drug delivery systems (DDS) was able to store and release substantial amounts of doxorubicin to the lung cancer cell lines. Display Omitted - Highlights: • Zn-Clin/GO nanocomposite as a new in vitro drug carrier with high loading capacity is synthesized. • Two synthesis methods (Microwave assisted hydrothermal method and Reflux method) are used. • All of the carriers (Zn-Clin, Zn-Clin/GO, GO) showed high biocompatibility.

Oxidation-reduction phenomena in tabular uranium-vanadium bearing sandstone from the Salt Wash deposits (Upper Jurassic) of the Cottonwood Wash district (Utah, USA)

International Nuclear Information System (INIS)

Meunier, J.D.

1984-02-01

A braided to meandering fluvial environment has been postulated for this area after a sedimentological study. The mineralization is spatially related with conifer derived organic matter and wood is preserved in these sediments because of the reducing environment of deposition. The degree of maturation of the organic matter has been estimated from chemical analyses. Results show the presence of variable diagenetic oxidation depending on the environment. The organic matter which was least affected by this oxidation have attained a thermal maturation characteristic of the end stage of diagenesis. The high grade ore is situated at the edges of or within the trunks of trees (which remained permeable during diagenesis) and at the boundaries of the carbonaceous beds. Geochemical study shows there to be good correlation between uranium and vanadium. Uranium occurs as pitchblende, coffinite or as impregnations in the vanadiferous clay cement. A detailed study of clays shows an association of chlorite and roscoelite which most probably contain V 3+ . Fluid inclusion study suggests burying temperatures of >= 100 0 C and shows the existance of brines before the mineralization. The following genetical model is proposed. Low Eh uraniferous solutions move through a reduced pyritised environment. The low degree of oxidation of the pyrites propagates the destabilization of the clastic iron-titanium oxides which release vanadium and the dissociation of uranylcarbonates. Then, the deposit of pitchblende, coffinite, montroseite and vanadiferous clays took place in association with a secondary pyrite. When the rocks were uplifted to the subsurface, uranium (IV) and vanadium (III) were remobilised in an oxidising environment to form a secondary mineralization essentially represented by tyuyamunite [fr

Insulin and vanadium protect against osteoarthritis development secondary to diabetes mellitus in rats.

Science.gov (United States)

El Karib, Abbas O; Al-Ani, Bahjat; Al-Hashem, Fahaid; Dallak, Mohammad; Bin-Jaliah, Ismaeel; El-Gamal, Basiouny; Bashir, Salah O; Eid, Refaat A; Haidara, Mohamed A

2016-07-01

Diabetic complications such as cardiovascular disease and osteoarthritis (OA) are among the common public health problems. The effect of insulin on OA secondary to diabetes has not been investigated before in animal models. Therefore, we sought to determine whether insulin and the insulin-mimicking agent, vanadium can protect from developing OA in diabetic rats. Type 1 diabetes mellitus (T1DM) was induced in Sprague-Dawley rats and treated with insulin and/or vanadium. Tissues harvested from the articular cartilage of the knee joint were examined by scanning electron microscopy, and blood samples were assayed for oxidative stress and inflammatory biomarkers. Eight weeks following the induction of diabetes, a profound damage to the knee joint compared to the control non-diabetic group was observed. Treatment of diabetic rats with insulin and/or vanadium differentially protected from diabetes-induced cartilage damage and deteriorated fibrils of collagen fibers. The relative biological potencies were insulin + vanadium > insulin > vanadium. Furthermore, there was about 2- to 5-fold increase in TNF-α (from 31.02 ± 1.92 to 60.5 ± 1.18 pg/ml, p 1) and IL-6 (from 64.67 ± 8.16 to 338.0 ± 38.9 pg/ml, p 1) cytokines and free radicals measured as TBARS (from 3.21 ± 0.37 to 11.48 ± 1.5 µM, p 1) in the diabetic group, which was significantly reduced with insulin and or vanadium. Meanwhile, SOD decreased (from 17.79 ± 8.9 to 8.250.29, p 1) and was increased with insulin and vanadium. The relative potencies of the treating agents on inflammatory and oxidative stress biomarkers were insulin + vanadium > insulin > vanadium. The present study demonstrates that co-administration of insulin and vanadium to T1DM rats protect against diabetes-induced OA possibly by lowering biomarkers of inflammation and oxidative stress.

Nanocomposites based on hierarchical porous carbon fiber@vanadium nitride nanoparticles as supercapacitor electrodes.

Science.gov (United States)

Ran, Fen; Wu, Yage; Jiang, Minghuan; Tan, Yongtao; Liu, Ying; Kong, Lingbin; Kang, Long; Chen, Shaowei

2018-03-28

In this study, a hybrid electrode material for supercapacitors based on hierarchical porous carbon fiber@vanadium nitride nanoparticles is fabricated using the method of phase-separation mediated by the PAA-b-PAN-b-PAA tri-block copolymer. In the phase-separation procedure, the ionic block copolymer self-assembled on the surface of carbon nanofibers, and is used to adsorb NH 4 VO 3 . Thermal treatment at controlled temperatures under an NH 3  : N 2 atmosphere led to the formation of vanadium nitride nanoparticles that are distributed uniformly on the nanofiber surface. By changing the PAN to PAA-b-PAN-b-PAA ratio in the casting solution, a maximum specific capacitance of 240.5 F g -1 is achieved at the current density of 0.5 A g -1 with good rate capability at a capacitance retention of 72.1% at 5.0 A g -1 in an aqueous electrolyte of 6 mol L -1 KOH within the potential range of -1.10 to 0 V (rN/A = 1.5/1.0). Moreover, an asymmetric supercapacitor is assembled by using the hierarchical porous carbon fiber@vanadium nitride as the negative electrode and Ni(OH) 2 as the positive electrode. Remarkably, at the power density of 400 W kg -1 , the supercapacitor device delivers a better energy density of 39.3 W h kg -1 . It also shows excellent electrochemical stability, and thus might be used as a promising energy-storage device.

The effect of material composition of 3-dimensional graphene oxide and self-doped polyaniline nanocomposites on DNA analytical sensitivity.

Science.gov (United States)

Yang, Tao; Chen, Huaiyin; Yang, Ruirui; Wang, Xinxing; Nan, Fuxin; Jiao, Kui

2015-09-01

Until now, morphology effects of 2-dimensional or 3-dimensional graphene nanocomposites and the effect of material composition on the biosensors have been rarely reported. In this paper, the various nanocomposites based on graphene oxide and self-doped polyaniline nanofibres for studying the effect of morphology and material composition on DNA sensitivity were directly reported. The isolation and dispersion of graphene oxide were realized via intercalated self-doped polyaniline and ultrasonication, where the ultrasonication prompts the aggregates of graphite oxide to break up and self-doped polyaniline to diffuse into the stacked graphene oxide. Significant electrochemical enhancement has been observed due to the existence of self-doped polyaniline, which bridges the defects for electron transfer and, in the mean time, increases the basal spacing between graphene oxide sheets. Different morphologies can result in different ssDNA surface density, which can further influence the hybridization efficiency. Compared with 2-dimensional graphene oxide, self-doped polyaniline and other morphologies of nanocomposites, 3-dimensional graphene oxide-self-doped polyaniline nanowalls exhibited the highest surface density and hybridization efficiency. Furthermore, the fabricated biosensors presented the broad detection range with the low detection limit due to the specific surface area, a large number of electroactive species, and open accessible space supported by nanowalls. Copyright © 2015 Elsevier B.V. All rights reserved.

Determination of Vanadium Binding Mode on Seawater-Contacted Polyamidoxime Adsorbents

Energy Technology Data Exchange (ETDEWEB)

Zhang, Zhicheng [Lawrence Berkeley National Laboratory (LBNL); Rao, Linfeng [Lawrence Berkeley National Laboratory (LBNL); Abney, Carter W. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Bryantsev, Vyacheslav [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Ivanov, Aleksandr [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

2017-09-01

Adsorbents developed for the recovery of uranium from seawater display poor selectivity over other transition metals present in the ocean, with vanadium particularly problematic. To improve selectivity, an indispensable step is the positive identification of metal binding environments following actual seawater deployment. In this work we apply x-ray absorption fine structure (XAFS) spectroscopy to directly investigate the vanadium binding environment on seawater-deployed polyamidoxime adsorbents. Comparison of the x-ray absorption near edge spectra (XANES) reveal marked similarities to recently a reported non-oxido vanadium (V) structure formed upon binding with cyclic imidedioxime, a byproduct of generating amidoxime functionalities. Density functional theory (DFT) calculations provided a series of putative vanadium binding environments for both vanadium (IV) and vanadium (V) oxidation states, and with both amidoxime and cyclic imidedioxime. Fits of the extended XAFS (EXAFS) data confirmed vanadium (V) is bound exclusively by the cyclic imidedioxime moiety in a 1:2 metal:ligand fashion, though a modest structural distortion is also observed compared to crystal structure data and computationally optimized geometries which is attributed to morphology effects from the polymer graft chain and the absence of crystal packing interactions. These results demonstrate that improved selectivity for uranium over vanadium can be achieved by suppressing the formation of cyclic imidedioxime during preparation of polyamidoxime adsorbents for seawater uranium recovery.

Enhanced polymer light-emitting diode property using fluorescent conducting polymer-reduced graphene oxide nanocomposite as active emissive layer

Science.gov (United States)

Singh, Jyoti Prakash; Saha, Uttam; Jaiswal, Rimpa; Anand, Raghubir Singh; Srivastava, Anurag; Goswami, Thako Hari

2014-11-01

The present article reports the polymer light-emitting diode property of the nanocomposite comprising poly 9,9-dioctyl fluorene- alt-bithiophene and reduced graphene oxide used as an emissive layer. Two times repetition of Hummers oxidation and hydrazine hydrate reduction method produce reduced graphene oxide (term as rGO2) with more uniform distribution in size and thickness. In addition, this uniquely synthesized rGO2 induces favorable shift in balance of electron and hole recombination zone toward the center of emissive layer owing to increase in in-plane crystallite size and high localize aromatic confinement. Five times increase in maximum device efficiency (Cd/A) and three times increase in maximum brightness (Cd/m2) are achieved with the LED device using nanocomposite as emissive layer compared to neat polymer. Also, the fabricated device requires relatively low turn-on voltage (4 V) because of low energy barrier between PEDOT work function (-5.0 eV) and HOMO levels of bi-thiophene copolymer -5.67 eV) and nanocomposite (-5.66 eV).

Highly Efficient Gas-Phase Oxidation of Renewable Furfural to Maleic Anhydride over Plate Vanadium Phosphorus Oxide Catalyst.

Science.gov (United States)

Li, Xiukai; Ko, Jogie; Zhang, Yugen

2018-02-09

Maleic anhydride (MAnh) and its acids are critical intermediates in chemical industry. The synthesis of maleic anhydride from renewable furfural is one of the most sought after processes in the field of sustainable chemistry. In this study, a plate vanadium phosphorus oxide (VPO) catalyst synthesized by a hydrothermal method with glucose as a green reducing agent catalyzes furfural oxidation to MAnh in the gas phase. The plate catalyst-denoted as VPO HT -has a preferentially exposed (200) crystal plane and exhibited dramatically enhanced activity, selectivity and stability as compared to conventional VPO catalysts and other state-of-the-art catalytic systems. At 360 °C reaction temperature with air as an oxidant, about 90 % yield of MAnh was obtained at 10 vol % of furfural in the feed, a furfural concentration value that is much higher than those (<2 vol %) reported for other catalytic systems. The catalyst showed good long-term stability and there was no decrease in activity or selectivity for MAnh during the time-on-stream of 25 h. The high efficiency and catalyst stability indicate the great potential of this system for the synthesis of maleic anhydride from renewable furfural. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Effect of temperature on the structural, linear, and nonlinear optical properties of MgO-doped graphene oxide nanocomposites

Directory of Open Access Journals (Sweden)

Kimiagar Salimeh

2018-01-01

Full Text Available Magnesium oxide (MgO-graphene oxide (GO nanocomposites were prepared by the hydrothermal method at different temperatures. The effect of growth temperature on the structural, linear, and nonlinear optical (NLO parameters was investigated. The decoration of MgO on GO sheets was confirmed by X-ray diffraction, scanning electron microscopy, Fourier transform infrared, and UV-visible (UV-vis spectroscopy analyses. The energy band-gaps of MgO-GO nanocomposites were calculated from UV-vis spectrum using Tauc plot. The NLO parameters of MgO-GO nanocomposites were calculated for the first time by the simple Z-scan technique with nanosecond Nd:YAG laser at 532 nm. The nonlinear absorption coefficient β and nonlinear refractive index n2 for MgO-GO nanocomposites at the laser intensity of 1.1×108 W/cm2 were measured to be in the order of 10−7 cm/W and 10−12 cm2/W, respectively. The third-order NLO susceptibility of MgO-GO nanocomposites was measured in the order of 10−9 esu. The results showed that MgO-GO structures have negative nonlinearity as well as good nonlinear two-photon absorption at 532 nm. Furthermore, the NLO parameters increased by the enhancement of the growth temperature. As the investigation of new materials plays an important role in the advancement of optoelectronics, MgO-GO nanocomposites possess potential applications in NLO devices.

Recovery of vanadium (V) from used catalysts in sulfuric acid production units by oxalic acid

International Nuclear Information System (INIS)

Abdulbaki, M.; Shino, O.

2009-07-01

Vanadium penta oxide (V 2 O 5 ), is used, in large quantities as a catalyst for the oxidation of SO 2 to SO 3 in sulfuric acid production units, during the oxidation process the level of the oxidation declines with the time because of catalyst poisoning. So the spent catalyst is usually through out in a specified special places by General Fertilizer Company which causes a pollution of the land. The present paper, studies the recovery of vanadium from the spent catalyst by using the oxalic acid. The optimal conditions of spent catalyst leaching have been studied. It has been shown that 2%(w/w) of oxalic acid is the most suitable for leaching process at 70 degree centigrade. The precipitation of vanadium using some alkaline media NH 4 OH has been also studied, it has been shown that ammonium hydroxide was the best at 50 degree centigrade. (author)

Microwave assisted facile synthesis of reduced graphene oxide-silver (RGO-Ag) nanocomposite and their application as active SERS substrate

International Nuclear Information System (INIS)

Wadhwa, Heena; Kumar, Devender; Mahendia, Suman; Kumar, Shyam

2017-01-01

The present paper represents the facile and rapid synthesis of reduced graphene oxide-silver (RGO-Ag) nanocomposite with the help of microwave irradiation. The graphene oxide (GO) solution has been prepared in bulk using Hummer's method followed by microwave assisted in-situ reduction of GO and silver nitrate (AgNO_3) by hydrazine hydrate in a short spam of 5 min. The prepared nanocomposite has been characterized using Transmission Electron Microscopy (TEM), X-Ray Diffraction (XRD) Scanning Electron Microscopy (SEM) and UV–Visible spectroscopy. TEM analysis shows that Ag nanoparticles with average size 32 nm are uniformly entangled with in RGO layers. The UV–Visible absorption spectrum of nanocomposite depicts the reduction of GO to RGO along with the formation of Ag nanoparticles with the presence of characteristic surface Plasmon resonance (SPR) peak of Ag nanoparticles at 422 nm. The performance of prepared nanocomposite has been tested as the active Surface Enhanced Raman Scattering (SERS) substrate for Rhodamine 6G with detection limit 0.1 μM. - Highlights: • The RGO and RGO-Ag nanocomposite were synthesized with microwave irradiation. • Ag nanoparticles of average size 32 nm are uniformly entangled within RGO layers. • RGO itself is a florescence quencher with SERS detection limit 1 μM for R6G. • RGO-Ag nanocomposite show good SERS activity for R6G with detection limit 0.1 μM.

Heterogeneous nanocomposites composed of silver sulfide and hollow structured Pd nanoparticles with enhanced catalytic activity toward formic acid oxidation

International Nuclear Information System (INIS)

Chen, Dong; Cui, Penglei; Liu, Hui; Yang, Jun

2015-01-01

Highlights: • Core–shell Ag-Ag/Pd nanoparticles with an Ag core and an Ag/Pd alloy shell are prepared via galvanic replacement reaction. • Heterogeneous Ag2S-hollow Pd nanocomposites are fabricated by converting the Ag component into Ag2S using element sulfur. • The heterogeneous Ag2S-hollow Pd nanocomposites display enhanced activity for formic acid oxidation due to electronic coupling effect. • The methodology may find applications to produce the semiconductor-metal nanocomposites with interesting architectures and tailored functionalities. - Abstract: Nanocomposites consisting semiconductor and noble metal domains are of great interest for their synergistic effect-based enhanced properties in a given application. Herein, we demonstrate a facile approach for the synthesis of heterogeneous nanocomposites consisting of silver sulfide (Ag 2 S) and hollow structured Pd nanoparticles (hPd). It begins with the preparation of core–shell nanoparticles with an Ag core and an alloy Ag/Pd shell in an organic solvent via galvanic replacement reaction (GRR) between Ag seed particles pre-synthesized and Pd 2+ ion precursors. The Ag component is then removed from the core and shell regions of core–shell Ag-Ag/Pd nanoparticles, and converted into Ag 2 S by elemental sulfur (S). The Ag 2 S forms the semiconductor domain in the nanocomposite and shares the solid-state interface with the resultant hollow structured Pd nanoparticle. As demonstrated, the Ag 2 S-hPd nanocomposites exhibit superior catalytic activity and durability for formic acid oxidation, compared to the pure Pd nanoparticles prepared by oleylamine reduction of Pd ion precursors and commercial Pd/C catalyst, due to the electronic coupling between semiconductor and noble metal domains in the nanocomposites. In addition, the structural transformation from core–shell to heterogeneous nanocomposites may provide new opportunities to design and fabricate hybrid nanostructures with interesting

Nanocrystal-polymer nanocomposite electrochromic device

Science.gov (United States)

Milliron, Delia; Runnerstrom, Evan; Helms, Brett; Llordes, Anna; Buonsanti, Raffaella; Garcia, Guillermo

2015-12-08

Described is an electrochromic nanocomposite film comprising a solid matrix of an oxide based material, the solid matrix comprising a plurality of transparent conducting oxide (TCO) nanostructures dispersed in the solid matrix and a lithium salt dispersed in the solid matrix. Also described is a near infrared nanostructured electrochromic device having a functional layer comprising the electrochromic nanocomposite film.

Rutile vanadium antimonates. A new class of catalysts for selective reduction of NO with ammonia

Energy Technology Data Exchange (ETDEWEB)

Brazdil, James F.; Ebner, Ann M.; Cavalcanti, Fernando A.P. [BP Chemicals Inc., Cleveland, OH (United States)

1997-12-31

This paper describes a new class of vanadium containing oxide catalysts that are active and selective for the selective catalytic reduction of NO with ammonia. Vanadium antimony oxide based catalysts were found to be effective in the conversion of NO with little or no ammonia slippage when tested using gas mixtures containing between 300 and 700ppm NO. X-ray diffraction analyses of the catalysts show that the dominant phase present in the catalyst is vanadium antimonate having a defect rutile crystal structure. The catalysts are active and selective in the ranges of 400-460C and gas hourly space velocities of 3000-8000h{sup -1}

Apoptosis inducing ability of silver decorated highly reduced graphene oxide nanocomposites in A549 lung cancer

Directory of Open Access Journals (Sweden)

Khan M

2016-03-01

Full Text Available Merajuddin Khan,1 Mujeeb Khan,1 Abdulhadi H Al-Marri,1 Abdulrahman Al-Warthan,1 Hamad Z Alkhathlan,1 Mohammed Rafiq H Siddiqui,1 Vadithe Lakshma Nayak,2 Ahmed Kamal,2 Syed F Adil1 1Department of Chemistry, College of Science, King Saud University, Riyadh, Kingdom of Saudi Arabia; 2Department of Medicinal Chemistry and Pharmacology, CSIR – Indian Institute of Chemical Technology, Hyderabad, India Abstract: Recently, graphene and graphene-based materials have been increasingly used for various biological applications due to their extraordinary physicochemical properties. Here, we demonstrate the anticancer properties and apoptosis-inducing ability of silver doped highly reduced graphene oxide nanocomposites synthesized by employing green approach. These nano­composites (PGE-HRG-Ag were synthesized by using Pulicaria glutinosa extract (PGE as a reducing agent and were evaluated for their anticancer properties against various human cancer cell lines with tamoxifen as the reference drug. A correlation between the amount of Ag nanoparticles on the surface of highly reduced graphene oxide (HRG and the anticancer activity of nanocomposite was observed, wherein an increase in the concentration of Ag nanoparticles on the surface of HRG led to the enhanced anticancer activity of the nanocomposite. The nanocomposite PGE-HRG-Ag-2 exhibited more potent cytotoxicity than standard drug in A549 cells, a human lung cancer cell line. A detailed investigation was undertaken and Fluorescence activated cell sorting (FACS analysis demonstrated that the nanocomposite PGE-HRG-Ag-2 showed G0/G1 phase cell cycle arrest and induced apoptosis in A549 cells. Studies such as, measurement of mitochondrial membrane potential, generation of reactive oxygen species (ROS and Annexin V-FITC staining assay suggested that this compound induced apoptosis in human lung cancer cells. Keywords: plant extract, graphene/silver nanocomposites, anticancer, apoptosis

Nickel oxide/polypyrrole/silver nanocomposites with core/shell/shell structure: Synthesis, characterization and their electrochemical behaviour with antimicrobial activities

Energy Technology Data Exchange (ETDEWEB)

Das, Dhaneswar; Nath, Bikash C. [Department of Chemical Sciences, Tezpur University, Tezpur 784028, Assam (India); Phukon, Pinkee [Department of Molecular Biology and Biotechnology, Tezpur University, Tezpur 784028, Assam (India); Saikia, Bhaskar J.; Kamrupi, Isha R. [Department of Chemical Sciences, Tezpur University, Tezpur 784028, Assam (India); Dolui, Swapan K., E-mail: dolui@tezu.ernet.in [Department of Chemical Sciences, Tezpur University, Tezpur 784028, Assam (India)

2013-10-01

Magnetic and conducting Nickel oxide–polypyrrole (NiO/PPy) nanoparticles with core–shell structure were prepared in the presence of Nickel oxide (NiO) in aqueous solution containing sodium dodecyl benzenesulfonate (SDBS) as a surfactant as well as dopant. A stable dispersion of silver (Ag) nanoparticles was synthesized by chemical (citrate reduction) method. NiO/PPy nanocomposites were added to the Ag colloid under stirring. Ag nanoparticles could be electrostatically attracted on the surface of NiO/PPy nanocomposites, leading to formation of NiO/PPy/Ag nanocomposites with core/shell/shell structure. The morphology, structure, particle size and composition of the products were characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, cyclic voltammetry (CV) and current–voltage (I–V) analysis. The resultant nanocomposites have the good conductivity and excellent electrochemical and catalytic properties of PPy and Ag nanoparticles. Furthermore, the nanocomposites showed excellent antibacterial behaviour due to the presence of Ag nanoparticles in the composite. The thermal stability of NiO–PPy as well as NiO/PPy/Ag nanocomposites was higher than that of pristine PPy. Studies of IR spectra suggest that the increased thermal stability may be due to interactions between NiO and Ag nanoparticles with the PPy backbone. - Highlights: • NiO nanoparticles were synthesized by two step soft chemical synthesis route. • Ag nanoparticles were prepared by using citrate reduction method. • NiO/PPy nanocomposites are synthesized by chemical oxidative polymerization process. • NiO/PPy/Ag nanocomposites can be used in the water purification technology.

Nickel oxide/polypyrrole/silver nanocomposites with core/shell/shell structure: Synthesis, characterization and their electrochemical behaviour with antimicrobial activities

International Nuclear Information System (INIS)

Das, Dhaneswar; Nath, Bikash C.; Phukon, Pinkee; Saikia, Bhaskar J.; Kamrupi, Isha R.; Dolui, Swapan K.

2013-01-01

Magnetic and conducting Nickel oxide–polypyrrole (NiO/PPy) nanoparticles with core–shell structure were prepared in the presence of Nickel oxide (NiO) in aqueous solution containing sodium dodecyl benzenesulfonate (SDBS) as a surfactant as well as dopant. A stable dispersion of silver (Ag) nanoparticles was synthesized by chemical (citrate reduction) method. NiO/PPy nanocomposites were added to the Ag colloid under stirring. Ag nanoparticles could be electrostatically attracted on the surface of NiO/PPy nanocomposites, leading to formation of NiO/PPy/Ag nanocomposites with core/shell/shell structure. The morphology, structure, particle size and composition of the products were characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, cyclic voltammetry (CV) and current–voltage (I–V) analysis. The resultant nanocomposites have the good conductivity and excellent electrochemical and catalytic properties of PPy and Ag nanoparticles. Furthermore, the nanocomposites showed excellent antibacterial behaviour due to the presence of Ag nanoparticles in the composite. The thermal stability of NiO–PPy as well as NiO/PPy/Ag nanocomposites was higher than that of pristine PPy. Studies of IR spectra suggest that the increased thermal stability may be due to interactions between NiO and Ag nanoparticles with the PPy backbone. - Highlights: • NiO nanoparticles were synthesized by two step soft chemical synthesis route. • Ag nanoparticles were prepared by using citrate reduction method. • NiO/PPy nanocomposites are synthesized by chemical oxidative polymerization process. • NiO/PPy/Ag nanocomposites can be used in the water purification technology

Enhanced mechanical properties of hydrothermal carbamated cellulose nanocomposite film reinforced with graphene oxide.

Science.gov (United States)

Gan, Sinyee; Zakaria, Sarani; Syed Jaafar, Sharifah Nabihah

2017-09-15

Cellulose carbamate (CC) was synthesized via hydrothermal process and mixed with graphene oxide (GO) to form a homogeneous cellulose matrix nanocomposite films. The properties of CC/GO nanocomposite films fabricated using simple solution-mixing method with different GO loadings were studied. Transmission electron microscope analysis showed the exfoliation of self-synthesized GO nanosheets within the CC matrix. X-ray diffraction results confirmed the crystalline structure of CC/GO films as the CC/GO mass ratio increased from 100/0 to 100/4. The mechanical properties of CC/GO film were significantly improved as compared to neat CC film. From thermogravimetric analysis result, the introduction of GO enhanced the thermal stability and carbon yields. The 3D homogeneous porous structures of the CC/GO films were observed under Field emission scanning electron microscope. These improvements in nanocomposite film properties could be confirmed by Fourier transform infrared spectroscopy due to the strong and good interactions between CC and GO. Copyright © 2017 Elsevier Ltd. All rights reserved.

Swift heavy ion induced modification in morphological and physico-chemical properties of tin oxide nanocomposites

Energy Technology Data Exchange (ETDEWEB)

Jaiswal, Manoj Kumar [University School of Basic and Applied Sciences, Guru Gobind Singh Indraprastha University, New Delhi 110 078 (India); Kanjilal, D. [Inter University Accelerator Centre, Aruna Asaf Ali Marg, New Delhi 110 067 (India); Kumar, Rajesh, E-mail: rajeshkumaripu@gmail.com [University School of Basic and Applied Sciences, Guru Gobind Singh Indraprastha University, New Delhi 110 078 (India)

2013-11-15

Nanocomposite thin films of tin oxide (SnO{sub 2})/titanium oxide (TiO{sub 2}) were grown on silicon (1 0 0) substrates by electron beam evaporation deposition technique using sintered nanocomposite pellet of SnO{sub 2}/TiO{sub 2} in the percentage ratio of 95:5. Sintering of the nanocomposite pellet was done at 1300 °C for 24 h. The thicknesses of these films were measured to be 100 nm during deposition using piezo-sensor attached to the deposition chamber. TiO{sub 2} doped SnO{sub 2} nanocomposite films were irradiated by 100 MeV Au{sup 8+} ion beam at fluence range varying from 1 × 10{sup 11} ions/cm{sup 2} to 5 × 10{sup 13} ions/cm{sup 2} at Inter University Accelerator Center (IUAC), New Delhi, India. Chemical properties of pristine and ion irradiation modified thin films were characterized by Fourier Transform Infrared (FTIR) spectroscopy. FTIR peak at 610 cm{sup −1} confirms the presence of O–Sn–O bridge of tin (IV) oxide signifying the composite nature of pristine and irradiated thin films. Atomic Force Microscope (AFM) in tapping mode was used to study the surface morphology and grain growth due to swift heavy ion irradiation at different fluencies. Grain size calculations obtained from sectional analysis of AFM images were compared with results obtained from Glancing Angle X-ray Diffraction (GAXRD) measurements using Scherrer’s formulae. Phase transformation due to irradiation was observed from Glancing Angle X-ray Diffraction (GAXRD) results. The prominent 2θ peaks observed in GAXRD spectrum are at 30.67°, 32.08°, 43.91°, 44.91° and 52.35° in the irradiated films.

Photodeposited metal-semiconductor nanocomposites and their applications

Directory of Open Access Journals (Sweden)

Yoonkyung Lee

2018-06-01

Full Text Available While two-dimensional layered nanomaterials including transition metal oxides and transition metal dichalcogenides have been widely researched because of their unique electronic and optical properties, they still have some limitations. To overcome these limitations, transition metal oxides and transition metal dichalcogenides based nanocomposites have been developed using various methods and have exhibited superior properties. In this paper, we introduce the photodeposition method and review the photodeposition of metal nanoparticles on the surface of transition metal oxide and transition metal dichalcogenides. Their current applications are also explained, such as photocatalysis, hydrogen evolution reaction, surface enhanced Ramanscattering, etc. This approach for nanocomposites has potential for future research areas such as photocatalysis, hydrogen evolution reaction, surface enhanced Raman scattering, and other applications. This approach for nanocomposite has the potential for future research areas. Keywords: Photodeposition, Nanocomposite, Transition metal oxide, Transition metal dichalcogenide

Polymer encapsulated upconversion nanoparticle/iron oxide nanocomposites for multimodal imaging and magnetic targeted drug delivery.

Science.gov (United States)

Xu, Huan; Cheng, Liang; Wang, Chao; Ma, Xinxing; Li, Yonggang; Liu, Zhuang

2011-12-01

Multimodal imaging and imaging-guided therapies have become a new trend in the current development of cancer theranostics. In this work, we encapsulate hydrophobic upconversion nanoparticles (UCNPs) together with iron oxide nanoparticles (IONPs) by using an amphiphilic block copolymer, poly (styrene-block-allyl alcohol) (PS(16)-b-PAA(10)), via a microemulsion method, obtaining an UC-IO@Polymer multi-functional nanocomposite system. Fluorescent dye and anti-cancer drug molecules can be further loaded inside the UC-IO@Polymer nanocomposite for additional functionalities. Utilizing the Squaraine (SQ) dye loaded nanocomposite (UC-IO@Polymer-SQ), triple-modal upconversion luminescence (UCL)/down-conversion fluorescence (FL)/magnetic resonance (MR) imaging is demonstrated in vitro and in vivo, and also applied for in vivo cancer cell tracking in mice. On the other hand, a chemotherapy drug, doxorubicin, is also loaded into the nanocomposite, forming an UC-IO@Polymer-DOX complex, which enables novel imaging-guided and magnetic targeted drug delivery. Our work provides a method to fabricate a nanocomposite system with highly integrated functionalities for multimodal biomedical imaging and cancer therapy. Copyright © 2011 Elsevier Ltd. All rights reserved.

Reduced graphene oxide/hydroxylated styrene-butadiene-styrene tri-block copolymer electroconductive nanocomposites: Preparation and properties

Energy Technology Data Exchange (ETDEWEB)

Xiong, Yuanqin; Xie, Yanyan [Institute of Polymer Science and Engineering, College of Chemistry and Chemical Engineering, Hunan University, Changsha 410082 (China); Zhang, Fan [College of Chemistry and Chemical Engineering, Jishou University, Jishou 416000 (China); Ou, Encai; Jiang, Zhuojuan; Ke, Lili; Hu, Ding [Institute of Polymer Science and Engineering, College of Chemistry and Chemical Engineering, Hunan University, Changsha 410082 (China); Xu, Weijian, E-mail: weijianxu59@gmail.com [Institute of Polymer Science and Engineering, College of Chemistry and Chemical Engineering, Hunan University, Changsha 410082 (China)

2012-08-20

Highlights: Black-Right-Pointing-Pointer RGO/HO-SBS nanocomposites are prepared successfully. Black-Right-Pointing-Pointer The introduction of -OH improves the compatibility between RGO and HO-SBS. Black-Right-Pointing-Pointer RGO disperse homogeneously and form a compact continuous network in matrix (HO-SBS). Black-Right-Pointing-Pointer The percolation threshold of the nanocomposites is of 0.2-0.5 wt% (0.09-0.23 vol%) and its conductivity is up to 1.3 S/m. - Abstract: Flexible and electroconductive nanocomposites based on reduced graphene oxide (RGO) and hydroxylated styrene-butadiene-styrene tri-block copolymer (HO-SBS) were prepared by solution blending method. By the introduction of the groups of -OH and >C=O onto SBS, the compatibility between RGO and SBS was enhanced. Field emission scanning electron microscopy (FE-SEM) and high-resolution transmission electron microscopy (HR-TEM) showed that RGO dispersed homogeneously and formed a compact continuous network in matrix (HO-SBS). The addition of RGO improved the thermal stability of the RGO/HO-SBS nanocomposites while slightly lowered the mechanical property. Moreover, RGO gave the nanocomposites a maximum electrical conductivity up to 1.3 S/m.

Application of vanadium alloys to a fusion reactor blanket

Energy Technology Data Exchange (ETDEWEB)

Bethin, J.; Tobin, A. (Grumman Aerospace Corp., Bethpage, NY (USA). Research and Development Center)

1984-05-01

Vanadium and vanadium alloys are of interest in fusion reactor blanket applications due to their low induced radioactivity and outstanding elevated temperature mechanical properties during neutron irradiation. The major limitation to the use of vanadium is its sensitivity to oxygen impurities in the blanket environment, leading to oxygen embrittlement. A quantitative analysis was performed of the interaction of gaseous impurities in a helium coolant with vanadium and the V-15Cr-5Ti alloy under conditions expected in a fusion reactor blanket. It was shown that the use of unalloyed V would impose severe restrictions on the helium gas cleanup system due to excessive oxygen buildup and embrittlement of the metal. However, internal oxidation effects and the possibly lower terminal oxygen solubility in the alloy would impose much less severe cleanup constraints. It is suggested that V-15Cr-5Ti is a promising candidate for certain blanket applications and deserves further consideration.

Graphene/vanadium oxide nanotubes composite as electrode material for electrochemical capacitors

International Nuclear Information System (INIS)

Fu, Meimei; Ge, Chongyong; Hou, Zhaohui; Cao, Jianguo; He, Binhong; Zeng, Fanyan; Kuang, Yafei

2013-01-01

Graphene/vanadium oxide nanotubes (VOx-NTs) composite was successfully synthesized through the hydrothermal process in which acetone as solvent and 1-hexadecylamine (HDA) as structure-directing template were used. Morphology, structure and composition of the as-obtained composite were investigated by scanning electron microscopy (SEM), X-ray diffraction (XRD), Raman spectroscopy, nitrogen isothermal adsorption/desorption and thermo gravimetric analysis (TGA). The composite with the VOx-NTs amount of 69.0 wt% can deliver a specific capacitance of 210 F/g at a current density of 1 A/g in 1 M Na 2 SO 4 aqueous solution, which is nearly twice as that of pristine graphene (128 F/g) or VOx-NTs (127 F/g), and exhibit a good performance rate. Compared with pure VOx-NTs, the cycle stability of the composite was also greatly improved due to the enhanced conductivity of the electrode and the structure buffer role of graphene

Synthesis of reduced graphene oxide-anatase TiO2 nanocomposite and its improved photo-induced charge transfer properties.

Science.gov (United States)

Wang, Ping; Zhai, Yueming; Wang, Dejun; Dong, Shaojun

2011-04-01

The construction of reduced graphene oxide or graphene oxide with semiconductor has gained more and more attention due to its unexpected optoelectronic and electronic properties. The synthesis of reduced graphene oxide (RGO) or graphene oxide-semiconductor nanocomposite with well-dispersed decorated particles is still a challenge now. Herein, we demonstrate a facile method for the synthesis of graphene oxide-amorphous TiO(2) and reduced graphene oxide-anatase TiO(2) nanocomposites with well-dispersed particles. The as-synthesized samples were characterized by transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, UV-Vis absorption spectroscopy, Fourier transform infrared spectrometry, and thermogravimetric analysis. The photovoltaic properties of RGO-anatase TiO(2) were also compared with that of similar sized anatase TiO(2) by transient photovoltage technique, and it was interesting to find that the combination of reduced graphene oxide with anatase TiO(2) will significantly increase the photovoltaic response and retard the recombination of electron-hole pairs in the excited anatase TiO(2).

Thermal desorption of toluene from Vanadium-containing catalysts coated onto various carriers

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Z. Zheksenbaeva

2012-12-01

Full Text Available The method temperature-programmed desorption has been studied the state of toluene on the surface-modified vanadium catalysts on different carriers. Among the investigated carriers the most active in the reaction of partial oxidation of toluene is anatase structural titanium dioxide. For the partial oxidation of toluene on modified vanadium-containing catalysts deposited on TiO2 was tested. It was found that on the catalyst 20%V2O5-5%MoO3-2%Sb2O3/TiO2 at a temperature of 673K, volume rate of 15 thousand hours-1 oxidation of toluene is 80% c yield of benzoic acid with a selectivity of  70% of 87.5%.

Experimental investigation of new low-dimensional spin systems in vanadium oxides

International Nuclear Information System (INIS)

Kaul, E.E.

2005-01-01

In this dissertation we reported our experimental investigation of the magnetic properties of nine low-dimensional vanadium compounds. Two of these materials are completely new (Pb 2 V 5 O 12 and Pb 2 VO(PO 4 ) 2 ) and were found during our search for new low-dimensional vanadium oxides. Among the other seven vanadium compounds studied, three were physically investigated for the first time (Sr 2 VO(PO 4 ) 2 , BaZnVO(PO 4 ) 2 and SrZnVO(PO 4 ) 2 ). Two had hitherto only preliminary, and wrongly interpreted, susceptibility measurements reported in the literature (Sr 2 V 3 O 9 and Ba 2 V 3 O 9 ) while the remaining two (Li 2 VOSiO 4 and Li 2 VOGeO 4 ) were previously investigated in some detail but the interpretation of the data was controversial. We investigated the magnetic properties of these materials by means of magnetic susceptibility and specific heat (C p (T)) measurements (as well as single crystal ESR measurements in the case of Sr 2 V 3 O 9 ). We synthesized the samples necessary for our physical studies. That required a search of the optimal synthesis conditions for obtaining pure, high quality, polycrystalline samples. Single crystals of Sr 2 V 3 O 9 and Pb 2 VO(PO 4 ) 2 were also successfully grown. Pb 2 VO(PO 4 ) 2 , BaZnVO(PO 4 ) 2 , SrZnVO(PO 4 ) 2 , Li 2 VOSiO 4 and Li 2 VOGeO 4 were found to be experimental examples of frustrated square-lattice systems which are described by theJ 1 -J 2 model. We found that Li 2 VOSiO 4 and Li 2 VOGeO 4 posses a weakly frustrated antiferromagnetic square lattice while Pb 2 VO(PO 4 ) 2 , BaZnVO(PO 4 ) 2 and SrZnVO(PO 4 ) 2 form a more strongly frustrated ferromagnetic square lattice. Pb 2 V 5 O 12 is structurally and compositionally related to the two dimensional A 2+ V 4+ n O 2n+1 vanadates. Its structure consists of layers formed by edge- and corner-shared square VO 5 pyramids. The basic structural units are plaquettes consisting of six corner-shared pyramids pointing in the same direction, which form a spin

APS- and XPS-investigations of vanadium, vanadium carbide and graphite

Energy Technology Data Exchange (ETDEWEB)

Bradshaw, A M; Krause, U [Technische Univ. Muenchen (F.R. Germany). Inst. fuer Physikalische Chemie und Theoretische Chemie

1975-11-01

Soft X-ray appearance potential spectroscopy (APS) and X-ray photoelectron spectroscopy (XPS) have been used to study vanadium, vanadium carbide, and graphite. The chemical shifts for vanadium carbide with respect to metallic vanadium and graphite are compared for the two methods. The Csub(K) structure in APS and the valence band in XPS for vanadium carbide show good agreement with the band structure calculations of Neckel and co-workers. Using the band structure calculations of Painter et al. it is also shown how the multi-peak structure in the APS spectrum of graphite is possibly due to density of states effects. It would therefore appear that plasmon coupling plays only a minor role.

Intercalation compounds of vanadium pentoxide hydrated with metalporphyrins and lanthanide ions

International Nuclear Information System (INIS)

Oliveira, Herenilton Paulino

1994-01-01

The lamellar structure of the vanadium pentoxide matrix allows the intercalation of organic molecules, ions and conductor polymers. It is important to emphasize that the vanadium oxide matrix is an intrinsic semiconductor and presents electrochromic properties. In the beginning of this work the method of synthesis and the electrochemical and electrochromic properties were extensively explored. The effect of alkaline metal and lanthanide ions on the structure of vanadium oxide matrix was studied by X-ray and infrared spectroscopy. Moreover, the influence of those ions in the electrochemical, spectro electrochemical and magnetic properties were studied. Finally, some intercalation compounds containing porphyrins were prepared and characterized by elemental analysis, X-ray diffraction, and electronic, vibrational, Moessbauer and X-ray fluorescence spectroscopy. The electrochemical and spectro electrochemical properties were investigated. And the performance of an iron porphyrin based intercalation compound as catalyst for molecular oxygen reduction was evaluated using the rotating ring-disc electrode technique. (author)

Structural and Electrical Properties of Graphene Oxide-Doped PVA/PVP Blend Nanocomposite Polymer Films

Directory of Open Access Journals (Sweden)

S. K. Shahenoor Basha

2018-01-01

Full Text Available Graphene oxide (GO nanoparticles were incorporated in PVA/PVP blend polymers for the preparation of nanocomposite polymer films by the solution cast technique. XRD, FTIR, DSC, SEM, and UV-visible studies were performed on the prepared nanocomposite polymer films. XRD revealed the amorphous nature of the prepared films. Thermal analysis of the nanocomposite polymer films was analyzed by DSC. SEM revealed the morphological features and the degree of roughness of the samples. DC conductivity studies were under taken on the samples, and the conductivity was found to be 6.13 × 10−4 S·cm−1 for the polymer film prepared at room temperature. A solid-state battery has been fabricated with the chemical composition of Mg+/(PVA/PVP  :  GO/(I2 + C + electrolyte, and its cell parameters like power density and current density were calculated.

Microwave assisted facile synthesis of reduced graphene oxide-silver (RGO-Ag) nanocomposite and their application as active SERS substrate

Energy Technology Data Exchange (ETDEWEB)

Wadhwa, Heena, E-mail: heenawadhwa1988@gmail.com; Kumar, Devender, E-mail: devkumsaroha@kuk.ac.in; Mahendia, Suman, E-mail: mahendia@gmail.com; Kumar, Shyam, E-mail: profshyam@gmail.com

2017-06-15

The present paper represents the facile and rapid synthesis of reduced graphene oxide-silver (RGO-Ag) nanocomposite with the help of microwave irradiation. The graphene oxide (GO) solution has been prepared in bulk using Hummer's method followed by microwave assisted in-situ reduction of GO and silver nitrate (AgNO{sub 3}) by hydrazine hydrate in a short spam of 5 min. The prepared nanocomposite has been characterized using Transmission Electron Microscopy (TEM), X-Ray Diffraction (XRD) Scanning Electron Microscopy (SEM) and UV–Visible spectroscopy. TEM analysis shows that Ag nanoparticles with average size 32 nm are uniformly entangled with in RGO layers. The UV–Visible absorption spectrum of nanocomposite depicts the reduction of GO to RGO along with the formation of Ag nanoparticles with the presence of characteristic surface Plasmon resonance (SPR) peak of Ag nanoparticles at 422 nm. The performance of prepared nanocomposite has been tested as the active Surface Enhanced Raman Scattering (SERS) substrate for Rhodamine 6G with detection limit 0.1 μM. - Highlights: • The RGO and RGO-Ag nanocomposite were synthesized with microwave irradiation. • Ag nanoparticles of average size 32 nm are uniformly entangled within RGO layers. • RGO itself is a florescence quencher with SERS detection limit 1 μM for R6G. • RGO-Ag nanocomposite show good SERS activity for R6G with detection limit 0.1 μM.

Polypyrrole–titanium(IV) doped iron(III) oxide nanocomposites: Synthesis, characterization with tunable electrical and electrochemical properties

International Nuclear Information System (INIS)

Nandi, Debabrata; Ghosh, Arup Kumar; Gupta, Kaushik; De, Amitabha; Sen, Pintu; Duttachowdhury, Ankan; Ghosh, Uday Chand

2012-01-01

Highlights: ► Synthesis and characterization of polymer nanocomposite based on titanium doped iron(III) oxide. ► Electrical conductivity increased 100 times in composite with respect to polymer. ► Electrochemical capacitance of polymer composites increased with nanooxide content. ► Thermal stability of the polymer enhanced with nano oxide content. -- Abstract: Titanium(IV)-doped synthetic nanostructured iron(III) oxide (NITO) and polypyrrole (PPy) nanocomposites was fabricated by in situ polymerization using FeCl 3 as initiator. The polymer nanocomposites (PNCs) and pure NITO were characterized by X-ray diffraction, Föurier transform infrared spectroscopy, scanning electron microscopy, electron dispersive X-ray spectroscopy, transmission electron microscopy, etc. Thermo gravimetric and differential thermal analyses showed the enhancement of thermal stability of PNCs than the pure polymer. Electrical conductivity of the PNCs had increased significantly from 0.793 × 10 −2 S/cm to 0.450 S/cm with respect to the PPy, and that had been explained by 3-dimensional variable range hopping (VRH) conduction mechanisms. In addition, the specific capacitance of PNCs had increased from 147 F/g to 176 F/g with increasing NITO content than that of pure NITO (26 F/g), presumably due to the growing of mesoporous structure with increasing NITO content in PNCs which reduced the charge transfer resistance significantly.

Graphene oxide/MnO2 nanocomposite as destructive adsorbent of nerve-agent simulants in aqueous media

Czech Academy of Sciences Publication Activity Database

Šťastný, Martin; Tolasz, Jakub; Štengl, Václav; Henych, Jiří; Žižka, D.

2017-01-01

Roč. 412, AUG (2017), s. 19-28 ISSN 0169-4332 R&D Projects: GA MŠk(CZ) LM2015073 Institutional support: RVO:61388980 Keywords : Graphene oxide * Manganese oxide * Nanocomposite * Destructive adsorption * Nerve agent simulants * Dimethyl methyl phosphonate (DMMP) * Triethyl phosphate (TEP) Subject RIV: CA - Inorganic Chemistry OBOR OECD: Inorganic and nuclear chemistry Impact factor: 3.387, year: 2016

Influence of titanium and vanadium on the hydrogen transport through amorphous alumina films

Energy Technology Data Exchange (ETDEWEB)

Palsson, G.K. [Department of Physics, Uppsala University, Box 530, S-751 21 Uppsala (Sweden); Wang, Y.T. [Department of Physics, Uppsala University, Box 530, S-751 21 Uppsala (Sweden); Azofeifa, D. [Centro de Investigacion en Ciencia e Ingenieria de Materiales and Escuela de Fisica, Universidad de Costa Rica, San Jose (Costa Rica); Raanaei, H. [Department of Physics, Uppsala University, Box 530, S-751 21 Uppsala (Sweden); Department of Physics, Persian Gulf University, Bushehr 75168 (Iran, Islamic Republic of); Sahlberg, M. [Department of Materials Chemistry, Uppsala University, Box 538, S-751 21 Uppsala (Sweden); Hjoervarsson, B. [Department of Physics, Uppsala University, Box 530, S-751 21 Uppsala (Sweden)

2010-04-02

The influence of titanium and vanadium on the hydrogen transport rate through thin amorphous alumina films is addressed. Only small changes in the transport rate are observed when the Al{sub 2}O{sub 3} are covered with titanium or vanadium. This is in stark contrast to results with a Pd overlayer, which enhances the transport by an order of magnitude. Similarly, when titanium is embedded into the alumina the transport rate is faster than for the covered case but still slower than the undoped reference. Embedding vanadium in the alumina does not yield an increase in uptake rate compared to the vanadium covered oxide layers. These results add to the understanding of the hydrogen uptake of oxidized metals, especially the alanates, where the addition of titanium has been found to significantly enhance the rate of hydrogen uptake. The current findings eliminate two possible routes for the catalysis of alanates by Ti, namely dissociation and effective diffusion short-cuts formed by Ti. Finally, no photocatalytic enhancement was noticed on the titanium covered samples.

The Role of Interfaces in Polyethylene/Metal-Oxide Nanocomposites for Ultrahigh-Voltage Insulating Materials.

Science.gov (United States)

Pourrahimi, Amir Masoud; Olsson, Richard T; Hedenqvist, Mikael S

2018-01-01

Recent progress in the development of polyethylene/metal-oxide nanocomposites for extruded high-voltage direct-current (HVDC) cables with ultrahigh electric insulation properties is presented. This is a promising technology with the potential of raising the upper voltage limit in today's underground/submarine cables, based on pristine polyethylene, to levels where the loss of energy during electric power transmission becomes low enough to ensure intercontinental electric power transmission. The development of HVDC insulating materials together with the impact of the interface between the particles and the polymer on the nanocomposites electric properties are shown. Important parameters from the atomic to the microlevel, such as interfacial chemistry, interfacial area, and degree of particle dispersion/aggregation, are discussed. This work is placed in perspective with important work by others, and suggested mechanisms for improved insulation using nanoparticles, such as increased charge trap density, adsorption of impurities/ions, and induced particle dipole moments are considered. The effects of the nanoparticles and of their interfacial structures on the mechanical properties and the implications of cavitation on the electric properties are also discussed. Although the main interest in improving the properties of insulating polymers has been on the use of nanoparticles, leading to nanodielectrics, it is pointed out here that larger microscopic hierarchical metal-oxide particles with high surface porosity also impart good insulation properties. The impact of the type of particle and its inherent properties (purity and conductivity) on the nanocomposite dielectric and insulating properties are also discussed based on data obtained by a newly developed technique to directly observe the charge distribution on a nanometer scale in the nanocomposite. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Electrodeposition of Vanadium Oxides at Room Temperature as Cathodes in Lithium-Ion Batteries

Directory of Open Access Journals (Sweden)

Michalis Rasoulis

2017-07-01

Full Text Available Electrodeposition of vanadium pentoxide coatings was performed at room temperature and a short growth period of 15 min based on an alkaline solution of methanol and vanadyl (III acetyl acetonate. All samples were characterized by X-ray diffraction, Raman spectroscopy, field-emission scanning electron microscopy, cyclic voltammetry, and electrochemical impedance spectroscopy. The current density and electrolyte concentration were found to affect the characteristics of the as-grown coatings presenting enhanced crystallinity and porous structure at the highest values employed in both cases. The as-grown vanadium pentoxide at current density of 1.3 mA·cm−2 and electrolyte concentration of 0.5 M indicated the easiest charge transfer of Li+ across the vanadium pentoxide/electrolyte interface presenting a specific discharge capacity of 417 mAh·g−1, excellent capacitance retention of 95%, and coulombic efficiency of 94% after 1000 continuous Li+ intercalation/deintercalation scans. One may then suggest that this route is promising to prepare large area vanadium pentoxide electrodes with excellent stability and efficiency at very mild conditions.

Facile synthesis of cuprous oxide nanowires decorated graphene oxide nanosheets nanocomposites and its application in label-free electrochemical immunosensor.

Science.gov (United States)

Wang, Huan; Zhang, Yong; Wang, Yulan; Ma, Hongmin; Du, Bin; Wei, Qin

2017-01-15

In this work, the assembly between one-dimensional (1D) nanomaterials and two-dimensional (2D) nanomaterials was achieved by a simple method. Cuprous oxide nanowires decorated graphene oxide nanosheets (Cu 2 O@GO) nanocomposites were synthesized for the first time by a simple electrostatic self-assembly process. The nanostructure was well confirmed by scanning electron microscope (SEM) and transmission electron microscope (TEM) images. Taking advantages of good electrocatalytic activity and high specific surface area of Cu 2 O@GO nanocomposites, a label-free electrochemical immunosensor was developed by employing Cu 2 O@GO as signal amplification platform for the quantitative detection of alpha fetoprotein (AFP). In addition, toluidine blue (TB) was used as the electron transfer mediator to provide the electrochemical signal, which was adsorbed on graphene oxide nanosheets (GO NSs) by electrostatic attraction. The detection mechanism was based on the monitoring of the electrochemical current response change of TB by the square wave voltammetry (SWV) when immunoreaction occurred on the surface of electrode. Under optimal conditions, the proposed immunosensor displayed a high sensitivity and a low detection limit. This designed method may provide an effective method in the clinical diagnosis of AFP and other tumor markers. Copyright © 2016 Elsevier B.V. All rights reserved.

Influence of deposition temperature and amorphous carbon on microstructure and oxidation resistance of magnetron sputtered nanocomposite Crsbnd C films

Science.gov (United States)

Nygren, Kristian; Andersson, Matilda; Högström, Jonas; Fredriksson, Wendy; Edström, Kristina; Nyholm, Leif; Jansson, Ulf

2014-06-01

It is known that mechanical and tribological properties of transition metal carbide films can be tailored by adding an amorphous carbon (a-C) phase, thus making them nanocomposites. This paper addresses deposition, microstructure, and for the first time oxidation resistance of magnetron sputtered nanocomposite Crsbnd C/a-C films with emphasis on studies of both phases. By varying the deposition temperature between 20 and 700 °C and alternating the film composition, it was possible to deposit amorphous, nanocomposite, and crystalline Crsbnd C films containing about 70% C and 30% Cr, or 40% C and 60% Cr. The films deposited at temperatures below 300 °C were X-ray amorphous and 500 °C was required to grow crystalline phases. Chronoamperometric polarization at +0.6 V vs. Ag/AgCl (sat. KCl) in hot 1 mM H2SO4 resulted in oxidation of Crsbnd C, yielding Cr2O3 and C, as well as oxidation of C. The oxidation resistance is shown to depend on the deposition temperature and the presence of the a-C phase. Physical characterization of film surfaces show that very thin C/Cr2O3/Crsbnd C layers develop on the present material, which can be used to improve the oxidation resistance of, e.g. stainless steel electrodes.

Graphene/vanadium oxide nanotubes composite as electrode material for electrochemical capacitors

Energy Technology Data Exchange (ETDEWEB)

Fu, Meimei [College of Chemistry, Xiangtan University, Xiangtan 411005 (China); College of Chemistry and Chemical Engineering, Hunan Institute of Science and Technology, Yueyang 414006 (China); Ge, Chongyong [College of Chemistry and Chemical Engineering, Hunan University, Changsha 410082 (China); College of Chemistry and Chemical Engineering, Hunan Institute of Science and Technology, Yueyang 414006 (China); Hou, Zhaohui, E-mail: zhqh96@163.com [College of Chemistry and Chemical Engineering, Hunan Institute of Science and Technology, Yueyang 414006 (China); Cao, Jianguo [College of Chemistry and Chemical Engineering, Hunan University, Changsha 410082 (China); College of Chemistry and Chemical Engineering, Hunan Institute of Science and Technology, Yueyang 414006 (China); He, Binhong [College of Chemistry and Chemical Engineering, Hunan Institute of Science and Technology, Yueyang 414006 (China); Zeng, Fanyan [College of Chemistry and Chemical Engineering, Hunan University, Changsha 410082 (China); College of Chemistry and Chemical Engineering, Hunan Institute of Science and Technology, Yueyang 414006 (China); Kuang, Yafei, E-mail: yafeik@163.com [College of Chemistry and Chemical Engineering, Hunan University, Changsha 410082 (China)

2013-07-15

Graphene/vanadium oxide nanotubes (VOx-NTs) composite was successfully synthesized through the hydrothermal process in which acetone as solvent and 1-hexadecylamine (HDA) as structure-directing template were used. Morphology, structure and composition of the as-obtained composite were investigated by scanning electron microscopy (SEM), X-ray diffraction (XRD), Raman spectroscopy, nitrogen isothermal adsorption/desorption and thermo gravimetric analysis (TGA). The composite with the VOx-NTs amount of 69.0 wt% can deliver a specific capacitance of 210 F/g at a current density of 1 A/g in 1 M Na{sub 2}SO{sub 4} aqueous solution, which is nearly twice as that of pristine graphene (128 F/g) or VOx-NTs (127 F/g), and exhibit a good performance rate. Compared with pure VOx-NTs, the cycle stability of the composite was also greatly improved due to the enhanced conductivity of the electrode and the structure buffer role of graphene.

Synthesize of Graphene-Tin Oxide Nanocomposite and Its Photocatalytic Properties for the Degradation of Organic Pollutants Under Visible Light.

Science.gov (United States)

Shanmugam, M; Jayavel, R

2015-09-01

Graphene-tinoxide nanocomposite has been synthesised by coating SnO2 nanoparticles on graphene sheets by the redox reaction between graphene oxide (GO) and tin chloride. Graphene oxide was reduced to graphene and Sn2+ was oxidized to SnO2 during the redox reaction, resulting in the uniform distribution of SnO2 nanoparticles on graphene sheets. The synthesised material was characterized by XRD, SEM, AFM, FT-IR, UV-vis, TGA and Raman spectroscopic studies. SEM and AFM studies reveal the formation of wrinkled paper like structure of graphene sheets with uniform coating of SnO2 nanoparticles on either side. The strong photocatalytic degradation of Methylene orange (MO) dye was analysed using G-SnO2 nanocomposite under the visible light irradiation.

Attapulgite-CeO{sub 2}/MoS{sub 2} ternary nanocomposite for photocatalytic oxidative desulfurization

Energy Technology Data Exchange (ETDEWEB)

Li, Xiazhang, E-mail: lixiazhang509@163.com [Jiangsu Key Laboratory of Advanced Catalytic Materials and Technology, School of Petrochemical Engineering, Changzhou University, Changzhou 213164 (China); Jiangsu Key Laboratory for Environment Functional Materials, Suzhou University of Science and Technology, Suzhou 215009 (China); W.M.Keck Center for Advanced Microscopy and Microanalysis, University of Delaware, Newark, DE 19716 (United States); Zhang, Zuosong [School of Materials Science and Engineering, Changzhou University, Changzhou 213164 (China); Yao, Chao [Jiangsu Key Laboratory of Advanced Catalytic Materials and Technology, School of Petrochemical Engineering, Changzhou University, Changzhou 213164 (China); Lu, Xiaowang [School of Materials Science and Engineering, Changzhou University, Changzhou 213164 (China); Zhao, Xiaobing [School of Materials Science and Engineering, Changzhou University, Changzhou 213164 (China); Jiangsu Key Laboratory for Environment Functional Materials, Suzhou University of Science and Technology, Suzhou 215009 (China); Ni, Chaoying [W.M.Keck Center for Advanced Microscopy and Microanalysis, University of Delaware, Newark, DE 19716 (United States)

2016-02-28

Graphical abstract: - Highlights: • Novel attapulgite(ATP)-CeO{sub 2}/MoS{sub 2} ternary nanocomposites were fabricated. • ATP possessed outstanding adsorption property and enhanced the stability of the network structure. • CeO{sub 2}/MoS{sub 2} couples facilitated the separation of photo-induced electrons and holes. • Mass ratio of CeO{sub 2}/MoS{sub 2} influenced the photocatalytic oxidation desulfurization. - Abstract: Novel attapulgite(ATP)-CeO{sub 2}/MoS{sub 2} ternary nanocomposites were synthesized by microwave assisted assembly method. The structures of the nanocomposites were characterized by XRD, FT-IR, UV–vis, XPS and in situ TEM. The photocatalytic activities of ATP-CeO{sub 2}/MoS{sub 2} composites were investigated by degradating dibenzothiophene (DBT) in gasoline under visible light irradiation. The effect of the mass ratio of CeO{sub 2} to MoS{sub 2} on photocatalytic activity was investigated. The results indicate that the three-dimensional network structure is firmly constructed by ATP skeleton, CeO{sub 2} particles and MoS{sub 2} nanosheet which effectively increase the surface area of the composites and promote the separation of electrons and holes by resulting electronic transmission channels of multi-channel in space. The degradation rate of DBT can reach 95% under 3 h irradiation when the mass ratio of CeO{sub 2}/MoS{sub 2} is 4/10. A plausible mechanism for the photocatalytic oxidative desulfurization of this nanocomposite is put forward.

Carbon-Nickel oxide nanocomposites: Preparation and charecterisation

CSIR Research Space (South Africa)

Tile, N

2011-07-01

Full Text Available Nanocomposite materials have wide range of applications in solar energy conversion. In this work, C-NiO nanocomposite coatings are prepared using sol-gel synthesis and deposited on aluminium substrates using a spin coater. The coatings are prepared...

Vanadium - 1977

International Nuclear Information System (INIS)

Broderick, G.N.

1977-01-01

This report, with pertinent references, is a comprehensive description and analysis of the vanadium industry. Included is information on industry structure, size and organization; definitions, grades, and specifications; reserves and resources; geology; production and capacity; uses; technology; byproducts and coproducts; strategic considerations; economic and operating factors and problems; supply-demand relationships; and forecasts of supply and demand. Vanadium is used principally as an alloy in steel. Other important uses are in titanium alloys and in various chemical catalytic processes. The world supply of vanadium is sufficient to last far beyond the year 2000 at the present and projected rates of consumption. Almost all of the resources will economically yield vanadium only in conjunction with a coproduct

Distortion of chain conformation and reduced entanglement in polymer-graphene oxide nanocomposites

Science.gov (United States)

Weir, Michael; Boothroyd, Stephen; Johnson, David; Thompson, Richard; Coleman, Karl; Clarke, Nigel

Graphene and related two-dimensional materials are excellent candidates as filler materials in polymer nanocomposites due to their extraordinary physical properties and high aspect ratio. To explore the mechanism by which the filler affects the bulk properties of these unique systems, and to build understanding from the macromolecular level upwards, we use a combination of small-angle neutron scattering (SANS) and oscillatory rheology. Where a good dispersion is achieved in poly(methyl methacrylate)-graphene oxide (PMMA-GO) nanocomposites, we observe a reduction in the polymer radius of gyration with increasing GO concentration that is consistent with the predicted behavior of polymer melt chains at a solid interface. We use concepts from thin-film polymer physics to formulate a scaling relation for the reduction in entanglements caused by the GO interfaces. Using these scaling arguments, we utilize SANS results to directly estimate the changes to the elastic plateau modulus of the network of entangled polymer chains, and find a correlation with the measured bulk rheology. We present a direct link between interfacial confinement effects and the bulk polymer nanocomposite properties, whilst demonstrating a model system for measuring thin film polymer physics in the bulk.

Preparation and optical properties of indium tin oxide/epoxy nanocomposites with polyglycidyl methacrylate grafted nanoparticles.

Science.gov (United States)

Tao, Peng; Viswanath, Anand; Schadler, Linda S; Benicewicz, Brian C; Siegel, Richard W

2011-09-01

Visibly highly transparent indium tin oxide (ITO)/epoxy nanocomposites were prepared by dispersing polyglycidyl methacrylate (PGMA) grafted ITO nanoparticles into a commercial epoxy resin. The oleic acid stabilized, highly crystalline, and near monodisperse ITO nanoparticles were synthesized via a nonaqueous synthetic route with multigram batch quantities. An azido-phosphate ligand was synthesized and used to exchange with oleic acid on the ITO surface. The azide terminal group allows for the grafting of epoxy resin compatible PGMA polymer chains via Cu(I) catalyzed alkyne-azide "click" chemistry. Transmission electron microscopy (TEM) observation shows that PGMA grafted ITO particles were homogeneously dispersed within the epoxy matrix. Optical properties of ITO/epoxy nanocomposites with different ITO concentrations were studied with an ultraviolet-visible-near-infrared (UV-vis-NIR) spectrometer. All the ITO/epoxy nanocomposites show more than 90% optical transparency in the visible light range and absorption of UV light from 300 to 400 nm. In the near-infrared region, ITO/epoxy nanocomposites demonstrate low transmittance and the infrared (IR) transmission cutoff wavelength of the composites shifts toward the lower wavelength with increased ITO concentration. The ITO/epoxy nanocomposites were applied onto both glass and plastic substrates as visibly transparent and UV/IR opaque optical coatings.

Nanodiamond-Gold Nanocomposites with the Peroxidase-Like Oxidative Catalytic Activity.

Science.gov (United States)

Kim, Min-Chul; Lee, Dukhee; Jeong, Seong Hoon; Lee, Sang-Yup; Kang, Eunah

2016-12-21

Novel nanodiamond-gold nanocomposites (NDAus) are prepared, and their oxidative catalytic activity is examined. Gold nanoparticles are deposited on carboxylated nanodiamonds (NDs) by in situ chemical reduction of gold precursor ions to produce NDAus, which exhibit catalytic activity for the oxidation of o-phenylenediamine in the presence of hydrogen peroxide similarly to a peroxidase. This remarkable catalytic activity is exhibited only by the gold nanoparticle-decorated NDs and is not observed for either Au nanoparticles or NDs separately. Kinetic oxidative catalysis studies show that NDAus exhibit a ping-pong mechanism with an activation energy of 93.3 kJ mol -1 , with the oxidation reaction rate being proportional to the substrate concentration. NDAus retain considerable activity even after several instances of reuse and are compatible with a natural enzyme, allowing the detection of xanthine using cascade catalysis. Association with gold nanoparticles makes NDs a good carbonic catalyst due to charge transfer at the metal-carbon interface and facilitated substrate adsorption. The results of this study suggest that diverse carbonic catalysts can be obtained by interfacial incorporation of various metal/inorganic substances.

High Performances of Artificial Nacre-Like Graphene Oxide-Carrageenan Bio-Nanocomposite Films.

Science.gov (United States)

Zhu, Wenkun; Chen, Tao; Li, Yi; Lei, Jia; Chen, Xin; Yao, Weitang; Duan, Tao

2017-05-16

This study was inspired by the unique multi-scale and multi-level 'brick-and-mortar' (B&M) structure of nacre layers. We prepared the B&M, environmentally-friendly graphene oxide-carrageenan (GO-Car) nanocomposite films using the following steps. A natural polyhydroxy polymer, carrageenan, was absorbed on the surface of monolayer GO nanosheets through hydrogen-bond interactions. Following this, a GO-Car hybridized film was produced through a natural drying process. We conducted structural characterization in addition to analyzing mechanical properties and cytotoxicity of the films. Scanning electron microscope (SEM) and X-ray diffraction (XRD) analyses showed that the nanocomposite films had a similar morphology and structure to nacre. Furthermore, the results from Fourier transform infrared spectroscopy (FT-IR), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS) and Thermogravimetric (TG/DTG) were used to explain the GO-Car interaction. Analysis from static mechanical testers showed that GO-Car had enhanced Young's modulus, maximum tensile strength and breaking elongation compared to pure GO. The GO-Car nanocomposite films, containing 5% wt. of Car, was able to reach a tensile strength of 117 MPa. The biocompatibility was demonstrated using a RAW264.7 cell test, with no significant alteration found in cellular morphology and cytotoxicity. The preparation process for GO-Car films is simple and requires little time, with GO-Car films also having favorable biocompatibility and mechanical properties. These advantages make GO-Car nanocomposite films promising materials in replacing traditional petroleum-based plastics and tissue engineering-oriented support materials.

Direct electrochemistry and electrocatalysis of glucose oxidase immobilized on reduced graphene oxide and silver nanoparticles nanocomposite modified electrode.

Science.gov (United States)

Palanisamy, Selvakumar; Karuppiah, Chelladurai; Chen, Shen-Ming

2014-02-01

The direct electrochemistry of glucose oxidase (GOx) was successfully realized on electrochemically reduced graphene oxide and silver nanoparticles (RGO/Ag) nanocomposite modified electrode. The fabricated nanocomposite was characterized by field emission scanning electron microscope and energy dispersive spectroscopy. The GOx immobilized nanocomposite modified electrode showed a pair of well-defined redox peaks with a formal potential (E°) of -0.422 V, indicating that the bioactivity of GOx was retained. The heterogeneous electron transfer rate constant (Ks) of GOx at the nanocomposite was calculated to be 5.27 s(-1), revealing a fast direct electron transfer of GOx. The GOx immobilized RGO/Ag nanocomposite electrode exhibited a good electrocatalytic activity toward glucose over a linear concentration range from 0.5 to 12.5 mM with a detection limit of 0.16 mM. Besides, the fabricated biosensor showed an acceptable sensitivity and selectivity for glucose. Copyright © 2013 Elsevier B.V. All rights reserved.

Attapulgite-CeO2/MoS2 ternary nanocomposite for photocatalytic oxidative desulfurization

Science.gov (United States)

Li, Xiazhang; Zhang, Zuosong; Yao, Chao; Lu, Xiaowang; Zhao, Xiaobing; Ni, Chaoying

2016-02-01

Novel attapulgite(ATP)-CeO2/MoS2 ternary nanocomposites were synthesized by microwave assisted assembly method. The structures of the nanocomposites were characterized by XRD, FT-IR, UV-vis, XPS and in situ TEM. The photocatalytic activities of ATP-CeO2/MoS2 composites were investigated by degradating dibenzothiophene (DBT) in gasoline under visible light irradiation. The effect of the mass ratio of CeO2 to MoS2 on photocatalytic activity was investigated. The results indicate that the three-dimensional network structure is firmly constructed by ATP skeleton, CeO2 particles and MoS2 nanosheet which effectively increase the surface area of the composites and promote the separation of electrons and holes by resulting electronic transmission channels of multi-channel in space. The degradation rate of DBT can reach 95% under 3 h irradiation when the mass ratio of CeO2/MoS2 is 4/10. A plausible mechanism for the photocatalytic oxidative desulfurization of this nanocomposite is put forward.

Rare earth ions doped polyaniline/cobalt ferrite nanocomposites via a novel coordination-oxidative polymerization-hydrothermal route: Preparation and microwave-absorbing properties

Energy Technology Data Exchange (ETDEWEB)

Yang, Chunming; Jiang, Junjun; Liu, Xiaohua; Yin, Chengjie; Deng, Cuifen

2016-04-15

Polyaniline/CoRE{sub x}Fe{sub 2−x}O{sub 4} (RE=La, Ce, Y, x=0.05–0.25) nanocomposites were successfully synthesized by a novel coordination-oxidative polymerization-hydrothermal method, and doped by sulfosalicylic acid. The resultant nanocomposites were characterized by scanning electron microscope (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), vibrating sample magnetometer (VSM) and electromagnetic measurements. The composites mainly showed nanofibers with a diameter of ca. 70 nm and a length longer than 2 μm. The surface of composites was uniformly covered with numerous nanoparticles with an average size of ca. 10–20 nm. Microwave absorption properties of polyaniline/CoRE{sub x}Fe{sub 2−x}O{sub 4} nanocomposites doped with La ion were found to be better than those doped with Ce and Y ions. For the polyaniline/CoLa{sub x}Fe{sub 2−x}O{sub 4} nanocomposite, the optimal microwave absorption performance is at x=0.15, that is, the mass ratio of La in CoLa{sub x}Fe{sub 2−x}O{sub 4} is 7.5%, with the conductivity of the composite about 0.833 S/cm. Furthermore, when the layer thickness is 2 mm, the maximum reflection loss achieves the maximum number of −42.65 dB at 15.91 GHz with a bandwidth of 6.14 GHz above −10 dB loss, suggesting that these nanocomposites are excellent in microwave absorbing capacity. - Graphical abstract: Scheme PAn/CoRE{sub x}Fe{sub 2−x}O{sub 4} nanocomposites prepared via a novel coordination-oxidative polymerization-hydrothermal route. - Highlights: • An organic–inorganic hybrid―polyaniline/CoRE{sub x}Fe{sub 2−x}O{sub 4} (RE=La, Ce, Y, x=0.05–0.25) nanocomposites was prepared via a novel coordination-oxidative polymerization-hydrothermal route. • The as-prepared polyaniline/CoRE{sub x}Fe{sub 2−x}O{sub 4} nanocomposites exhibit excellent microwave absorbing performance compared with the composites prepared by using conventional method. • The novel method reported in this work could

Rare earth ions doped polyaniline/cobalt ferrite nanocomposites via a novel coordination-oxidative polymerization-hydrothermal route: Preparation and microwave-absorbing properties

International Nuclear Information System (INIS)

Yang, Chunming; Jiang, Junjun; Liu, Xiaohua; Yin, Chengjie; Deng, Cuifen

2016-01-01

Polyaniline/CoRE_xFe_2_−_xO_4 (RE=La, Ce, Y, x=0.05–0.25) nanocomposites were successfully synthesized by a novel coordination-oxidative polymerization-hydrothermal method, and doped by sulfosalicylic acid. The resultant nanocomposites were characterized by scanning electron microscope (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), vibrating sample magnetometer (VSM) and electromagnetic measurements. The composites mainly showed nanofibers with a diameter of ca. 70 nm and a length longer than 2 μm. The surface of composites was uniformly covered with numerous nanoparticles with an average size of ca. 10–20 nm. Microwave absorption properties of polyaniline/CoRE_xFe_2_−_xO_4 nanocomposites doped with La ion were found to be better than those doped with Ce and Y ions. For the polyaniline/CoLa_xFe_2_−_xO_4 nanocomposite, the optimal microwave absorption performance is at x=0.15, that is, the mass ratio of La in CoLa_xFe_2_−_xO_4 is 7.5%, with the conductivity of the composite about 0.833 S/cm. Furthermore, when the layer thickness is 2 mm, the maximum reflection loss achieves the maximum number of −42.65 dB at 15.91 GHz with a bandwidth of 6.14 GHz above −10 dB loss, suggesting that these nanocomposites are excellent in microwave absorbing capacity. - Graphical abstract: Scheme PAn/CoRE_xFe_2_−_xO_4 nanocomposites prepared via a novel coordination-oxidative polymerization-hydrothermal route. - Highlights: • An organic–inorganic hybrid―polyaniline/CoRE_xFe_2_−_xO_4 (RE=La, Ce, Y, x=0.05–0.25) nanocomposites was prepared via a novel coordination-oxidative polymerization-hydrothermal route. • The as-prepared polyaniline/CoRE_xFe_2_−_xO_4 nanocomposites exhibit excellent microwave absorbing performance compared with the composites prepared by using conventional method. • The novel method reported in this work could be employed to prepare other conductive polymers/inorganic nanocomposites as well.

Influence of Magnetite Nanoparticles on the Dielectric Properties of Metal Oxide/Polymer Nanocomposites Based on Polypropylene

Science.gov (United States)

Maharramov, A. A.; Ramazanov, M. A.; Di Palma, Luca; Shirinova, H. A.; Hajiyeva, F. V.

2018-01-01

Structure and dielectric properties of polymer nanocomposites based on isotactic polypropylene and iron oxide (Fe3O4) nanoparticles are studied. Distribution of magnetite nanoparticles in a polymer matrix was studied by scanning electron microscopy (SEM, Carl Zeiss). Dielectric properties of nanocomposites were examined by means of E7-21 impedance spectrometer in the frequency range of 102-106 Hz and temperature interval of 298-433 K. The frequency and temperature dependences of the dielectric permittivity ɛ, as well as the temperature dependence of log (ρ) were constructed. It is shown that introduction of the magnetite (Fe3O4) nanoparticles into a polypropylene matrix increases the dielectric permittivity of nanocomposites. An increase in the dielectric permittivity is explained by the increase in the polarization ability of nanocomposites. It is found that a decrease in the specific resistance with increasing temperature up to 318 K is associated with an increase in the ionic conductivity of nanocomposites. An increase in the resistance at temperatures higher than 358 K is due to the destruction of the crystalline phase of the polymer, as a result of which the distance between the Fe3O4 nanoparticles increases.

Multifunctional nanocomposite based on graphene oxide for in vitro hepatocarcinoma diagnosis and treatment.

Science.gov (United States)

Shen, Ai-Jun; Li, Dong-Liang; Cai, Xiao-Jun; Dong, Chun-Yan; Dong, Hai-Qing; Wen, Hui-Yun; Dai, Gong-Hua; Wang, Pei-Jun; Li, Yong-Yong

2012-09-01

Because of its unique chemical and physical properties, graphene oxide (GO) has attracted a large number of researchers to explore its biomedical applications in the past few years. Here, we synthesized a novel multifunctional nanocomposite based on GO and systemically investigated its applications for in vitro hepatocarcinoma diagnosis and treatment. This multifunctional nanocomposite named GO-PEG-FA/Gd/DOX was obtained as the following procedures: gadolinium-diethylenetriamine-pentaacetic acid-poly(diallyl dimethylammonium) chloride (Gd-DTPA-PDDA) as magnetic resonance imaging (MRI) probe was applied to modify GO by simple physical sorption with a loading efficiency of Gd(3+) up to 0.314 mg mg(-1). In order to improve its tumor targeting imaging and treatment efficiency, the obtained intermediate product was further modified with folic acid (FA). Finally, the nanocomposite was allowed to load anticancer drug doxorubicin hydrochloride via π-π stacking and hydrophobic interaction with the loading capacity reaching 1.38 mg mg(-1). MRI test revealed that GO-PEG-FA/Gd/DOX exhibit superior tumor targeting imaging efficiency over free Gd(3+). The in vitro release of DOX from the nanocomposite under tumor relevant condition (pH 5.5) was fast at the initial 10 h and then become relatively slow afterward. Moreover, we experimentally demonstrated that the multifunctional nanocomposite exhibited obviously cytotoxic effect upon cancer cells. Above results are promising for the next in vivo experiment and make it possible to be a potential candidate for malignancy early detection and specific treatment. Copyright © 2012 Wiley Periodicals, Inc.

In situ chemical oxidative polymerization preparation of poly(3,4-ethylenedioxythiophene)/graphene nanocomposites with enhanced thermoelectric performance.

Science.gov (United States)