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Sample records for titania nanosheet cryatallites

  1. Immobilization of Superoxide Dismutase on Polyelectrolyte-Functionalized Titania Nanosheets.

    Science.gov (United States)

    Rouster, Paul; Pavlovic, Marko; Szilagyi, Istvan

    2018-02-16

    The superoxide dismutase (SOD) enzyme was successfully immobilized on titania nanosheets (TNS) functionalized with the poly(diallyldimethylammonium chloride) (PDADMAC) polyelectrolyte. The TNS-PDADMAC solid support was prepared by hydrothermal synthesis followed by self-assembled polyelectrolyte layer formation. It was found that SOD strongly adsorbed onto oppositely charged TNS-PDADMAC through electrostatic and hydrophobic interactions. The TNS-PDADMAC-SOD material was characterized by light scattering and microscopy techniques. Colloidal stability studies revealed that the obtained nanocomposites possessed good resistance against salt-induced aggregation in aqueous suspensions. The enzyme kept its functional integrity upon immobilization; therefore, TNS-PDADMAC-SOD showed excellent superoxide radical anion scavenging activity. The developed system is a promising candidate for applications in which suspensions of antioxidant activity are required in the manufacturing processes. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  2. Bulk-heterojunction organic solar cells sandwiched by solution processed molybdenum oxide and titania nanosheet layers

    Science.gov (United States)

    Itoh, Eiji; Goto, Yoshinori; Fukuda, Katsutoshi

    2014-02-01

    The contributions of ultrathin titania nanosheet (TN) crystallites were studied in both an inverted bulk-heterojunction (BHJ) cell in an indium-tin oxide (ITO)/titania nanosheet (TN)/poly(3-hexylthiophene) (P3HT):phenyl-C61-butyric acid methylester (PCBM) active layer/MoOx/Ag multilayered photovoltaic device and a conventional BHJ cell in ITO/MoOx/P3HT:PCBM active layer/TN/Al multilayered photovoltaic device. The insertion of only one or two layers of poly(diallyldimethylammonium chloride) (PDDA) and TN multilayered film prepared by the layer-by-layer deposition technique effectively decreased the leakage current and increased the open circuit voltage (VOC), fill factor (FF), and power conversion efficiency (η). The conventional cell sandwiched between a solution-processed, partially crystallized molybdenum oxide hole-extracting buffer layer and a TN electron extracting buffer layer showed comparable cell performance to a device sandwiched between vacuum-deposited molybdenum oxide and TN layers, whereas the inverted cell with solution-processed molybdenum oxide showed a poorer performance probably owing to the increment in the leakage current across the film. The abnormal S-shaped curves observed in the inverted BHJ cell above VOC disappeared with the use of a polyfluorene-based cationic semiconducting polymer as a substitute for an insulating PDDA film, resulting in the improved cell performance.

  3. Layer-by-Layer Assembly and Photocatalytic Activity of Titania Nanosheets on Coal Fly Ash Microspheres

    Directory of Open Access Journals (Sweden)

    Xing Cui

    2014-01-01

    Full Text Available In order to address the problem with titania distribution and recovery, series of Ti0.91O2/CFA photocatalysts (Ti0.91O2/CFA-n, n=2,4,6, and 8 were fabricated by assembling Ti0.91O2 nanosheets on coal fly ash (CFA microspheres via the layer-by-layer assembly (LBLA process and characterized by scanning electron microscopy (SEM, X-ray diffraction analysis (XRD, N2-sorption, and ultraviolet-visible absorption (UV-vis techniques. The SEM images and UV-vis spectra illustrated that Ti0.91O2 nanosheets were immobilized successfully on the CFA by the LBLA approach and changed the characteristics of CFA noticeably. The photocatalytic activity of Ti0.91O2/CFA was evaluated by the photodegradation of methylene blue (MB under UV irradiation. The results demonstrated that Ti0.91O2/CFA-6 showed the best photocatalytic activity among the series of Ti0.91O2/CFA irradiated for 60 min, with a decoloration rate above 43%. After photocatalysis, the Ti0.91O2/CFA could be easily separated and recycled from aqueous solution and Ti0.91O2 nanosheets were still anchored on the CFA.

  4. Electrochemical performance of mixed crystallographic phase nanotubes and nanosheets of titania and titania-carbon/silver composites for lithium-ion batteries

    International Nuclear Information System (INIS)

    Das, Shyamal K.; Bhattacharyya, Aninda J.

    2011-01-01

    Highlights: → Carbon wired TiO 2 nanotubes as anode for lithium ion batteries. → Mixed phase nanotubes show higher energy and power density than titania nanosheets. → Lithium storage and phase stabilization influenced by morphology of carbon coating. - Abstract: The role of homogeneity in ex situ grown conductive coatings and dimensionality in the lithium storage properties of TiO 2 is discussed here. TiO 2 nanotube and nanosheet comprising of mixed crystallographic phases of anatase and TiO 2 (B) have been synthesized by an optimized hydrothermal method. Surface modifications of TiO 2 nanotube are realized via coating the nanotube with Ag nanoparticles and amorphous carbon. The first discharge cycle capacity (at current rate = 10 mA g -1 ) for TiO 2 nanotube and nanosheet were 355 mAh g -1 and 225 mAh g -1 , respectively. The conductive surface coating stabilized the titania crystallographic structure during lithium insertion-deinsertion processes via reduction in the accessibility of lithium ions to the trapping sites. The irreversible capacity is beneficially minimized from 110 mAh g -1 for TiO 2 nanotubes to 96 mAh g -1 and 57 mAh g -1 respectively for Ag and carbon modified TiO 2 nanotubes. The homogeneously coated amorphous carbon over TiO 2 renders better lithium battery performance than randomly distributed Ag nanoparticles coated TiO 2 due to efficient hopping of electrons.

  5. Destabilization of Titania Nanosheet Suspensions by Inorganic Salts: Hofmeister Series and Schulze-Hardy Rule.

    Science.gov (United States)

    Rouster, Paul; Pavlovic, Marko; Szilagyi, Istvan

    2017-07-13

    Ion specific effects on colloidal stability of titania nanosheets (TNS) were investigated in aqueous suspensions. The charge of the particles was varied by the pH of the solutions, therefore, the influence of mono- and multivalent anions on the charging and aggregation behavior could be studied when they were present either as counter or co-ions in the systems. The aggregation processes in the presence of inorganic salts were mainly driven by interparticle forces of electrostatic origin, however, chemical interactions between more complex ions and the surface led to additional attractive forces. The adsorption of anions significantly changed the surface charge properties and hence, the resistance of the TNS against salt-induced aggregation. On the basis of their ability in destabilization of the dispersions, the monovalent ions could be ordered according to the Hofmeister series in acidic solutions, where they act as counterions. However, the behavior of the biphosphate anion was atypical and its adsorption induced charge reversal of the particles. The multivalent anions destabilized the oppositely charged TNS more effectively and the aggregation processes followed the Schulze-Hardy rule. Only weak or negligible interactions were observed between the anions and the particles in alkaline suspensions, where the TNS possessed negative charge.

  6. Construction of highly ordered lamellar nanostructures through Langmuir-Blodgett deposition of molecularly thin titania nanosheets tens of micrometers wide and their excellent dielectric properties.

    Science.gov (United States)

    Akatsuka, Kosho; Haga, Masa-aki; Ebina, Yasuo; Osada, Minoru; Fukuda, Katsutoshi; Sasaki, Takayoshi

    2009-05-26

    Exfoliated unilamellar titania nanosheets of Ti(0.87)O(2) with a lateral size of 10-30 microm were deposited layer-by-layer onto various substrates by Langmuir-Blodgett procedure to produce a highly ordered lamellar nanofilms. The nanosheets dispersed in an aqueous suspension containing quaternary ammonium ions as a supporting electrolyte floated spontaneously at the air/liquid interface, and they were successfully transferred onto the substrate after surface compression. Neat tiling of the nanosheets could be realized at an optimized surface pressure. The film thus obtained was exposed to UV light to turn the substrate surface hydrophilic, which was helpful for stable repetition of monolayer deposition. Layer-by-layer growth was confirmed by UV-visible absorption spectra, which showed progressive enhancement of an absorption band due to the nanosheet. Cross-sectional transmission electron microscopy images visualized the ultrathin film homogeneously deposited on the substrate surface and a lamellar fringe of the layer-by-layer assembled nanosheets was clearly resolved at a higher magnification. X-ray diffraction data on the films showed sharp basal reflections up to the seventh order, and Williamson-Hall analysis of the pattern indicated that the film was coherent across the total thickness with respect to X-ray and that the lattice strain was extremely small. In addition, the first basal reflection was accompanied by small satellite peaks, which are accounted for by the Laue interference function. All these features clearly indicate the formation of a highly ordered lamellar nanostructure of the titania nanosheets comparable to artificial lattice films produced via modern vapor-phase deposition processes. The obtained films showed superior dielectric and insulating properties as a reflection of the highly organized film nanoarchitecture.

  7. Template-free synthesis of two-dimensional titania/titanate nanosheets as electrodes for high-performance supercapacitor applications

    Science.gov (United States)

    Barai, Hasi Rani; Rahman, Md. Mahbubur; Joo, Sang Woo

    2017-12-01

    Template-free two-dimensional (2D) titania/titanate nanosheets on Ti metal foil (TiNS/Ti) is prepared by a hydrothermal method at 150 °C assisted by KOH(aq.),followed by sintering at 500 °C. A single thin layer of TiNS is grown with 2D morphology when using low concentrations of KOH(aq.) (0.25 and 0.5 M). However, the morphology is transformed to 1D when using a high concentration of KOH(aq.). The TiNS is a mixture of rutile TiO2 and K-titanate (K2Ti3O7 and K2Ti2O5) with the formation of Ti3+ interstitials. The optimized TiNS/Ti electrode exhibits quasi-rectangular cyclic voltammograms (CVs) in a wide potential range. The specific capacitance (Cs) are 6.8 × 103 and 4.7 × 103 μF/cm2 according to the CV (scan rate, 5 mV/s) and charge-discharge measurements (CD, current density, 50 μA/cm2), respectively. These values are much higher than those reported for pure 0D and 1D TiO2 nanostructures.The higher Cs for the TiNS/Ti electrode can be ascribed to the increased rate of K+ intercalation and de-intercalation during charging and discharging, as well as enhanced conductivity enable by the K in the crystal lattice (10.30%) and Ti3+ interstitials (5.2%), respectively. The TiNS/Ti electrode shows excellent stability with the Cs retention of 89% even after 5000 CD cycles.

  8. Superlattice assembly of graphene oxide (GO) and titania nanosheets: fabrication, in situ photocatalytic reduction of GO and highly improved carrier transport

    Science.gov (United States)

    Cai, Xingke; Ma, Renzhi; Ozawa, Tadashi C.; Sakai, Nobuyuki; Funatsu, Asami; Sasaki, Takayoshi

    2014-11-01

    Two different kinds of two-dimensional (2D) materials, graphene oxide (GO) and titanium oxide nanosheets (Ti0.87O20.52-), were self-assembled layer-by-layer using a polycation as a linker into a superlattice film. Successful construction of an alternate molecular assembly was confirmed by atomic force microscopy and UV-visible absorption spectroscopy as well as X-ray diffraction analysis. Exposure of the resulting film to UV light effectively promoted photocatalytic reduction of GO as well as decomposition of the polycation, which are due to their intimate molecular-level contact. The reduction completed within 3 hours, bringing about a decrease of the sheet resistance by ~106. This process provides a clean and mild route to reduced graphene oxide (rGO), showing advantages over other chemical and thermal reduction processes. A field-effect-transistor device was fabricated using the resulting superlattice assembly of rGO/Ti0.87O20.52- as a channel material. The rGO in the film was found to work as a unipolar n-type conductor, which is in contrast to ambipolar or unipolar p-type behavior mostly reported for rGO films. This unique property may be associated with the electron doping effect from Ti0.87O20.52- nanosheets. A significant improvement in the conductance and electron carrier mobility by more than one order of magnitude was revealed, which may be accounted for by the heteroassembly with Ti0.87O20.52- nanosheets with a high dielectric constant as well as the better 2D structure of rGO produced via the soft photocatalytic reduction.Two different kinds of two-dimensional (2D) materials, graphene oxide (GO) and titanium oxide nanosheets (Ti0.87O20.52-), were self-assembled layer-by-layer using a polycation as a linker into a superlattice film. Successful construction of an alternate molecular assembly was confirmed by atomic force microscopy and UV-visible absorption spectroscopy as well as X-ray diffraction analysis. Exposure of the resulting film to UV light

  9. Rational design of hierarchically porous birnessite-type manganese dioxides nanosheets on different one-dimensional titania-based nanowires for high performance supercapacitors

    Science.gov (United States)

    Zhang, Yu Xin; Kuang, Min; Hao, Xiao Dong; Liu, Yan; Huang, Ming; Guo, Xiao Long; Yan, Jing; Han, Gen Quan; Li, Jing

    2014-12-01

    A facile and large-scale strategy of mesoporous birnessite-type manganese dioxide (MnO2) nanosheets on one-dimension (1D) H2Ti3O7 and anatase/TiO2 (B) nanowires (NWs) is developed for high performance supercapacitors. The morphological characteristics of MnO2 nanoflakes on H2Ti3O7 and anatase/TiO2 (B) NWs could be rationally designed with various characteristics (e.g., the sheet thickness, surface area). Interestingly, the MnO2/TiO2 NWs exhibit a more optimized electrochemical performance with specific capacitance of 120 F g-1 at current density of 0.1 A g-1 (based on MnO2 + TiO2) than MnO2/H2Ti3O7 NWs. An asymmetric supercapacitor of MnO2/TiO2//activated graphene (AG) yields a better energy density of 29.8 Wh kg-1 than MnO2/H2Ti3O7//AG asymmetric supercapacitor, while maintaining desirable cycling stability. Indeed, the pseudocapacitive difference is related to the substrates, unique structure and surface area. Especially, the anatase/TiO2 (B) mixed-phase system can provide good electronic conductivity and high utilization of MnO2 nanosheets.

  10. Rational design of hierarchically porous birnessite-type manganese dioxides nanosheets on different one-dimensional titania-based nanowires for high performance supercapacitors

    KAUST Repository

    Zhang, Yu Xin

    2014-12-01

    A facile and large-scale strategy of mesoporous birnessite-type manganese dioxide (MnO2) nanosheets on one-dimension (1D) H2Ti 3O7 and anatase/TiO2 (B) nanowires (NWs) is developed for high performance supercapacitors. The morphological characteristics of MnO2 nanoflakes on H2Ti 3O7 and anatase/TiO2 (B) NWs could be rationally designed with various characteristics (e.g., the sheet thickness, surface area). Interestingly, the MnO2/TiO2 NWs exhibit a more optimized electrochemical performance with specific capacitance of 120 F g-1 at current density of 0.1 A g-1 (based on MnO 2 + TiO2) than MnO2/H2Ti 3O7 NWs. An asymmetric supercapacitor of MnO 2/TiO2//activated graphene (AG) yields a better energy density of 29.8 Wh kg-1 than MnO2/H2Ti 3O7//AG asymmetric supercapacitor, while maintaining desirable cycling stability. Indeed, the pseudocapacitive difference is related to the substrates, unique structure and surface area. Especially, the anatase/TiO2 (B) mixed-phase system can provide good electronic conductivity and high utilization of MnO2 nanosheets. © 2014 Elsevier B.V. All rights reserved.

  11. Development of highly porous crystalline titania photocatalysts

    Science.gov (United States)

    Marszewski, Michal

    The objectives of this dissertation are the design, synthesis, and characterization of titania materials with surface area, porosity, crystallinity and doping tailored toward photocatalytic applications. Ultimately, the research should result in a strategy allowing the synthesis of titania with all these important features. The synthetic methods investigated in this research will include: i) soft-templating, ii) hard-templating, and iii) modified precursor strategy. Soft-templating strategy uses organic templates--either block copolymers or surfactants--that under specific conditions assemble into micelles, and later, these micelles are used to template the desired material around them. The resulting organic-inorganic composite is then calcined in air to remove the organic template and recover the final material with high surface area and large pore volume. This work explores 1) synthesis of titania materials in the presence of polymer templates, and the effects of different synthetic conditions on the structure of the resulting materials. Hard-templating, in contrast to soft-templating, uses inorganic templates. The hard template is introduced during the synthesis to cast its shape onto the fabricated material and removed afterwards, when the material has formed. The final material is an inverse replica of the hard template used, typically with a well-developed mesostructure. This work explores 1) hard templating synthesis of titania materials using silica and alumina, and 2) the effects of the template amount and type. The modified precursor strategy is a novel synthetic method, developed in this research, and designed specifically to achieve titania material with high surface area, large pore volume, high crystallinity, and possibly doping. The modified precursors are prepared by reacting generic titania precursors, such as titanium isopropoxide (TIPO), with organic acids, which results in substitution of some or all alkoxide groups in TIPO structure. The goal

  12. Hydrothermal synthesis of nanostructured titania

    International Nuclear Information System (INIS)

    Yoshito, Walter Kenji; Ferreira, Nildemar A.M.; Rumbao, Ana Carolina S. Coutinho; Lazar, Dolores R.R.; Ussui, Valter

    2009-01-01

    Titania ceramics have many applications due to its surface properties and, recently, its nanostructured compounds, prepared by hydrothermal treatments, have been described to improve these properties. In this work, commercial titanium dioxide was treated with 10% sodium hydroxide solution in a pressurized reactor at 150°C for 24 hours under vigorous stirring and then washed following two different procedures. The first one consisted of washing with water and ethanol and the second with water and hydrochloric acid solution (1%). Resulting powders were characterized by X-ray diffraction, N 2 gas adsorption and field emission gun scanning and transmission electronic microscopy. Results showed that from an original starting material with mainly rutile phase, both anatase and H 2 Ti 3 O 7 phase could be identified after the hydrothermal treatment. Surface area of powders presented a notable increase of one order of magnitude and micrographs showed a rearrangement on the microstructure of powders. (author)

  13. Hydrothermal synthesis of nanostructured titania

    International Nuclear Information System (INIS)

    Yoshito, W.K.; Ferreira, N.A.M.; Lazar, D.R.R.; Ussui, V.; Rumbao, A.C.S.

    2011-01-01

    Titania ceramics have many applications due to its surface properties and, recently, its nanostructured compounds, prepared by hydrothermal treatments, have been described to improve these properties. In this work, commercial titanium dioxide was treated with 10% sodium hydroxide solution in a pressurized reactor at 150 deg C for 24 hours under vigorous stirring and then washed following two different procedures. The first one consisted of washing with water and ethanol and the second with water and hydrochloric acid solution (1%). Resulting powders were characterized by X-ray diffraction, N 2 gas adsorption and field emission gun scanning and transmission electronic microscopy. Results showed that from an original starting material with mainly rutile phase, both anatase and H 2 Ti 3 O 7 phase could be identified after the hydrothermal treatment. Surface area of powders presented a notable increase of one order of magnitude and micrographs showed a rearrangement on the microstructure of powders. (author)

  14. Electrochemical biosensing based on polypyrrole/titania nanotube hybrid

    Energy Technology Data Exchange (ETDEWEB)

    Xie, Yibing, E-mail: ybxie@seu.edu.cn; Zhao, Ye

    2013-12-01

    The glucose oxidase (GOD) modified polypyrrole/titania nanotube enzyme electrode is fabricated for electrochemical biosensing application. The titania nanotube array is grown directly on a titanium substrate through an anodic oxidation process. A thin film of polypyrrole is coated onto titania nanotube array to form polypyrrole/titania nanotube hybrid through a normal pulse voltammetry process. GOD-polypyrrole/titania nanotube enzyme electrode is prepared by the covalent immobilization of GOD onto polypyrrole/titania nanotube hybrid via the cross-linker of glutaraldehyde. The morphology and microstructure of nanotube electrodes are characterized by field emission scanning electron microscopy and Fourier transform infrared analysis. The biosensing properties of this nanotube enzyme electrode have been investigated by means of cyclic voltammetry and chronoamperometry. The hydrophilic polypyrrole/titania nanotube hybrid provides highly accessible nanochannels for GOD encapsulation, presenting good enzymatic affinity. As-formed GOD-polypyrrole/titania nanotube enzyme electrode well conducts bioelectrocatalytic oxidation of glucose, exhibiting a good biosensing performance with a high sensitivity, low detection limit and wide linear detection range. - Graphical abstract: The schematic diagram presents the fabrication of glucose oxidase modified polypyrrole/titania (GOD-PPy/TiO{sub 2}) nanotube enzyme electrode for biosensing application. - Highlights: • Hydrophilic polypyrrole/titania nanotube hybrid is well used as biosensing substrate. • Polypyrrole promotes GOD immobilization on titania nanotubes via glutaraldehyde. • GOD-polypyrrole/titania enzyme electrode shows good bioelectrocatalytic reactivity.

  15. Electrochemical biosensing based on polypyrrole/titania nanotube hybrid

    International Nuclear Information System (INIS)

    Xie, Yibing; Zhao, Ye

    2013-01-01

    The glucose oxidase (GOD) modified polypyrrole/titania nanotube enzyme electrode is fabricated for electrochemical biosensing application. The titania nanotube array is grown directly on a titanium substrate through an anodic oxidation process. A thin film of polypyrrole is coated onto titania nanotube array to form polypyrrole/titania nanotube hybrid through a normal pulse voltammetry process. GOD-polypyrrole/titania nanotube enzyme electrode is prepared by the covalent immobilization of GOD onto polypyrrole/titania nanotube hybrid via the cross-linker of glutaraldehyde. The morphology and microstructure of nanotube electrodes are characterized by field emission scanning electron microscopy and Fourier transform infrared analysis. The biosensing properties of this nanotube enzyme electrode have been investigated by means of cyclic voltammetry and chronoamperometry. The hydrophilic polypyrrole/titania nanotube hybrid provides highly accessible nanochannels for GOD encapsulation, presenting good enzymatic affinity. As-formed GOD-polypyrrole/titania nanotube enzyme electrode well conducts bioelectrocatalytic oxidation of glucose, exhibiting a good biosensing performance with a high sensitivity, low detection limit and wide linear detection range. - Graphical abstract: The schematic diagram presents the fabrication of glucose oxidase modified polypyrrole/titania (GOD-PPy/TiO 2 ) nanotube enzyme electrode for biosensing application. - Highlights: • Hydrophilic polypyrrole/titania nanotube hybrid is well used as biosensing substrate. • Polypyrrole promotes GOD immobilization on titania nanotubes via glutaraldehyde. • GOD-polypyrrole/titania enzyme electrode shows good bioelectrocatalytic reactivity

  16. Preparation and characterization of titania based nanowires

    International Nuclear Information System (INIS)

    Stengl, Vaclav; Bakardjieva, Snejana; Murafa, Natalie; Vecernikova, Eva; Subrt, Jan; Balek, Vladimir

    2007-01-01

    A new method for preparation of titania nanowires with diameter around 10 nm and length up to 2-3 μm is described. The precursor was prepared from sodium titanate by adding ethylene glycole (EG) and heating at temperature of 198 deg. C for 6 h under reflux. The sodium titanate glycolate formed by this way aggregated into 1D nanostructures and was subsequently transformed into titania glycolate during a chemical treatment with 98% sulfuric acid. Titania nanowires with variable amount of anatase and rutile were prepared by heating to temperatures in the range 350-1000 deg. C. The precursor as well as titania based samples were characterized by X-ray diffraction, Infrared spectroscopy, Scanning electron microscopy, High resolution transmission microscopy, Thermogravimetry, Differential thermal analysis, Evolved gas analysis and Emanation thermal analysis. The nitrogen adsorption/desorption was used for surface area and porosity determination. The photoactivity of the prepared titania samples was assessed by the photocatalytic decomposition of 4-chlorophenol in an aqueous slurry under UV irradiation of 365 nm wavelength

  17. KOH modified graphene nanosheets for supercapacitor electrodes

    Science.gov (United States)

    Li, Yueming; van Zijll, Marshall; Chiang, Shirley; Pan, Ning

    Chemical modification of graphene nanosheets by KOH was examined as a way to enhance the specific capacity of graphene nanosheets in supercapacitor. Fourier transform infrared spectroscopy, Raman spectroscopy and X-ray photoelectron spectroscopy were used to investigate the effects of the treatment on the surface of the graphene nanosheets. The specific capacitance of 136 F g -1 was obtained for KOH treated graphene by integration of the cyclic voltammogram, an increase of about 35% compared with that for the pristine graphene nanosheets.

  18. Sustainable steric stabilization of colloidal titania nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Elbasuney, Sherif, E-mail: sherif_basuney2000@yahoo.com

    2017-07-01

    Graphical abstract: Controlled surface properties of titania nanoparticles via surface modification, flocculation from aqueous phase (a), stabilization in aqueous phase (b), extraction to organic phase (c). - Highlights: • Complete change in surface properties of titania nanoparticles from hydrophilic to hydrophobic. • Harvesting the formulated nanoparticles from the aqueous phase to the organic phase. • Exclusive surface modification in the reactor during nanoparticle synthesis. • Sustainable stabilization of titania nanoparticles in aqueous media with polar polymeric dispersant. - Abstract: A route to produce a stable colloidal suspension is essential if mono-dispersed particles are to be successfully synthesized, isolated, and used in subsequent nanocomposite manufacture. Dispersing nanoparticles in fluids was found to be an important approach for avoiding poor dispersion characteristics. However, there is still a great tendency for colloidal nanoparticles to flocculate over time. Steric stabilization can prevent coagulation by introducing a thick adsorbed organic layer which constitutes a significant steric barrier that can prevent the particle surfaces from coming into direct contact. One of the main features of hydrothermal synthesis technique is that it offers novel approaches for sustainable nanoparticle surface modification. This manuscript reports on the sustainable steric stabilization of titanium dioxide nanoparticles. Nanoparticle surface modification was performed via two main approaches including post-synthesis and in situ surface modification. The tuneable hydrothermal conditions (i.e. temperature, pressure, flow rates, and surfactant addition) were optimized to enable controlled steric stabilization in a continuous fashion. Effective post synthesis surface modification with organic ligand (dodecenyl succinic anhydride (DDSA)) was achieved; the optimum surface coating temperature was reported to be 180–240 °C to ensure DDSA ring opening

  19. Fabrication of homogeneous titania/MWNT composite materials

    International Nuclear Information System (INIS)

    Korbely, Barbara; Nemeth, Zoltan; Reti, Balazs; Seo, Jin Won; Magrez, Arnaud; Forro, Laszlo; Hernadi, Klara

    2011-01-01

    Highlights: → Homogenous titania coverage on MWNT surface in a controllable way. → Various titanium alkoxy precursors are suitable for layer formation. → Acetone and ethanol are the best to promote interaction between MWNT and titania. -- Abstract: MWNT/titania nanocomposites were prepared by an impregnation method and subsequent heat treatment at 400 o C. Precursor compounds such as titanium (IV) propoxide and titanium (IV) ethoxide were used to cover the surface of CNTs under solution conditions. Electron microscopy and X-ray diffraction techniques were carried out to characterize the as-prepared titania layers.

  20. The functionalization of carbon nanosheets

    Science.gov (United States)

    Quinlan, Ronald A.

    Carbon nanosheets are a novel two-dimensional nanostructure made up of 2-20 graphene atomic planes oriented with their in-plane axis perpendicular to the growth substrate. Previous efforts in developing nanosheet technology have focused on the characterization of the system and their development as an electron source due to the high atomic enhancement factor (beta) and low turn on field. Further investigation of nanosheets as high surface area electrodes revealed poor wetting by polymeric material and extreme hydrophobic behavior. Because nanosheet technology has promise as a high surface area electrode material, this thesis research has focused on three areas of interest: the enhancement of nanosheets through chemical modification, the incorporation of the nanosheets into a polymeric composite and the delivery of a proof of concept measurement. We have successfully introduced defects into the graphene lattice of the nanosheet system via an acid treatment. Inspection of these defects by x-ray absorption near-edge spectroscopy (XANES) shows the introduction of two features in the spectra assigned to C=O pi* and C-O sigma* transitions. Thermal desorption spectroscopy (TDS) was used to identify the oxygen containing groups created during the functionalization as carboxylic and hydroxyl functional groups. These groups were identified through the combination of carboxylic, hydroxyl, anhydride and lactone peaks in the CO2, CO and H 2O TDS spectra. Deconvolution of the TDS spectra using 1st and 2nd order Polanyi-Wigner equations enables the calculation of desorption energy values for individual features and for the estimation of the number of atoms desorbing from the surface during a particular event. Identification of the exact nature of the functional groups was attempted through high resolution x-ray photoelectron spectroscopy (XPS) of the C(1s) and O(1s) peaks. Though the pairing of sub-peaks with specific functionalities of the system was not possible due to the

  1. The potential health risk of titania nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Ruinan, E-mail: ruinanzhang87@gmail.com [School of Chemistry and Chemical Engineering, Shandong University, Jinan 250100 (China); Bai, Yuhong, E-mail: yuhong.bai1983@gmail.com [School of Pharmaceutical Sciences, Shandong University, Jinan 250100 (China); Zhang, Bin, E-mail: binzhang1968@hotmail.com [School of Chemistry and Chemical Engineering, Shandong University, Jinan 250100 (China); Chen, Lingxin, E-mail: lxchen@yic.ac.cn [Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai, Shandong 264003 (China); Yan, Bing, E-mail: dr.bingyan@gmail.com [School of Chemistry and Chemical Engineering, Shandong University, Jinan 250100 (China); Department of Chemical Biology and Therapeutics, St. Jude Children' s Research Hospital, Memphis, TN 38105 (United States)

    2012-04-15

    Highlights: Black-Right-Pointing-Pointer Nanotechnology has been widely used in environmental treatments. Black-Right-Pointing-Pointer The safety of nanomaterials to human is under-studied. Black-Right-Pointing-Pointer Taking titania nanoparticle as an example to address nanotoxicity and remedy. Black-Right-Pointing-Pointer The much needed future investigations are suggested. - Abstract: Widespread use of titania nanoparticles (TNPs) has caused a significant release of TNPs into the environment, increasing human exposure to TNPs. The potential toxicity of TNPs has become an urgent concern. Various models have been used to evaluate the toxic effects of TNPs, but the relationship between TNPs' toxicity and physicochemical properties is largely unknown. This review summarizes relevant reports to support the development of better predictive toxicological models and the safe future application of TNPs.

  2. The potential health risk of titania nanoparticles

    International Nuclear Information System (INIS)

    Zhang, Ruinan; Bai, Yuhong; Zhang, Bin; Chen, Lingxin; Yan, Bing

    2012-01-01

    Highlights: ► Nanotechnology has been widely used in environmental treatments. ► The safety of nanomaterials to human is under-studied. ► Taking titania nanoparticle as an example to address nanotoxicity and remedy. ► The much needed future investigations are suggested. - Abstract: Widespread use of titania nanoparticles (TNPs) has caused a significant release of TNPs into the environment, increasing human exposure to TNPs. The potential toxicity of TNPs has become an urgent concern. Various models have been used to evaluate the toxic effects of TNPs, but the relationship between TNPs’ toxicity and physicochemical properties is largely unknown. This review summarizes relevant reports to support the development of better predictive toxicological models and the safe future application of TNPs.

  3. Sustainable steric stabilization of colloidal titania nanoparticles

    Science.gov (United States)

    Elbasuney, Sherif

    2017-07-01

    A route to produce a stable colloidal suspension is essential if mono-dispersed particles are to be successfully synthesized, isolated, and used in subsequent nanocomposite manufacture. Dispersing nanoparticles in fluids was found to be an important approach for avoiding poor dispersion characteristics. However, there is still a great tendency for colloidal nanoparticles to flocculate over time. Steric stabilization can prevent coagulation by introducing a thick adsorbed organic layer which constitutes a significant steric barrier that can prevent the particle surfaces from coming into direct contact. One of the main features of hydrothermal synthesis technique is that it offers novel approaches for sustainable nanoparticle surface modification. This manuscript reports on the sustainable steric stabilization of titanium dioxide nanoparticles. Nanoparticle surface modification was performed via two main approaches including post-synthesis and in situ surface modification. The tuneable hydrothermal conditions (i.e. temperature, pressure, flow rates, and surfactant addition) were optimized to enable controlled steric stabilization in a continuous fashion. Effective post synthesis surface modification with organic ligand (dodecenyl succinic anhydride (DDSA)) was achieved; the optimum surface coating temperature was reported to be 180-240 °C to ensure DDSA ring opening and binding to titania nanoparticles. Organic-modified titania demonstrated complete change in surface properties from hydrophilic to hydrophobic and exhibited phase transfer from the aqueous phase to the organic phase. Exclusive surface modification in the reactor was found to be an effective approach; it demonstrated surfactant loading level 2.2 times that of post synthesis surface modification. Titania was also stabilized in aqueous media using poly acrylic acid (PAA) as polar polymeric dispersant. PAA-titania nanoparticles demonstrated a durable amorphous polymeric layer of 2 nm thickness. This

  4. Fabrication of ruthenium metal nanosheets via topotactic metallization of exfoliated ruthenate nanosheets.

    Science.gov (United States)

    Fukuda, Katsutoshi; Sato, Jun; Saida, Takahiro; Sugimoto, Wataru; Ebina, Yasuo; Shibata, Tatsuo; Osada, Minoru; Sasaki, Takayoshi

    2013-03-04

    The metallization behavior of molecularly thin RuO2 nanosheets obtained from complete delamination of layered ruthenates was studied. Interestingly, the RuO2 nanosheets in a monolayer state topotactically transformed into a single layer of Ru atoms, i.e., ruthenium metal nanosheets, which can be regarded as a new family of nanosized metals.

  5. Effect of Nanosheet Surface Structure of Titanium Alloys on Cell Differentiation

    Directory of Open Access Journals (Sweden)

    Satoshi Komasa

    2014-01-01

    Full Text Available Titanium alloys are the most frequently used dental implants partly because of the protective oxide coating that spontaneously forms on their surface. We fabricated titania nanosheet (TNS structures on titanium surfaces by NaOH treatment to improve bone differentiation on titanium alloy implants. The cellular response to TNSs on Ti6Al4V alloy was investigated, and the ability of the modified surfaces to affect osteogenic differentiation of rat bone marrow cells and increase the success rate of titanium implants was evaluated. The nanoscale network structures formed by alkali etching markedly enhanced the functions of cell adhesion and osteogenesis-related gene expression of rat bone marrow cells. Other cell behaviors, such as proliferation, alkaline phosphatase activity, osteocalcin deposition, and mineralization, were also markedly increased in TNS-modified Ti6Al4V. Our results suggest that titanium implants modified with nanostructures promote osteogenic differentiation, which may improve the biointegration of these implants into the alveolar bone.

  6. Ultrahigh temperature-sensitive silicon MZI with titania cladding

    Directory of Open Access Journals (Sweden)

    Jong-Moo eLee

    2015-05-01

    Full Text Available We present a possibility of intensifying temperature sensitivity of a silicon Mach-Zehnder interferometer (MZI by using a highly negative thermo-optic property of titania (TiO2. Temperature sensitivity of an asymmetric silicon MZI with a titania cladding is experimentally measured from +18pm/C to -340 pm/C depending on design parameters of MZI.

  7. Hydrogen peroxide route to Sn-doped titania photocatalysts

    Directory of Open Access Journals (Sweden)

    Štengl Václav

    2012-10-01

    Full Text Available Abstract Background The work aims at improving photocatalytic activity of titania under Vis light irradiation using modification by Sn ions and an original, simple synthesis method. Tin-doped titania catalysts were prepared by thermal hydrolysis of aqueous solutions of titanium peroxo-complexes in the presence of SnCl4 or SnCl2 using an original, proprietary "one pot" synthesis not employing organic solvents, metallo-organic precursors, autoclave aging nor post-synthesis calcination. The products were characterized in details by powder diffraction, XPS, UV–vis, IR, and Raman spectroscopies, electron microscopy and surface area and porosity measurements Results The presence of tin in synthesis mixtures favors the formation of rutile and brookite at the expense of anatase, decreases the particle size of all formed titania polymorphs, and extends light absorption of titania to visible light region >400 nm by both red shift of the absorption edge and introduction of new chromophores. The photocatalytic activity of titania under UV irradiation and >400 nm light was tested by decomposition kinetics of Orange II dye in aqueous solution Conclusions Doping by Sn improves titania photoactivity under UV light and affords considerable photoactivity under >400 nm light due to increased specific surface area and a phase heterogeneity of the Sn-doped titania powders.

  8. Surface characterization of Ag/Titania adsorbents

    International Nuclear Information System (INIS)

    Samokhvalov, Alexander; Nair, Sachin; Duin, Evert C.; Tatarchuk, Bruce J.

    2010-01-01

    The Ag/Titania adsorbent for selective removal of the desulfurization-refractive polycyclic aromatic sulfur heterocycles (PASHs) from liquid hydrocarbon fuels was prepared, its total and the Ag specific surface area were determined and the surface reaction sites in the sorbent that may be active in the adsorptive selective desulfurization were characterized by several spectroscopic and surface science techniques. The sorbent contains Ag, Ti, O and spurious C on its surface, as by the XPS measurements. Silver is present as an oxide, as judged by the XPS Auger parameter (AP). The complementary electron spin resonance (ESR) spectroscopy confirms that the majority of Ag is present in the diamagnetic Ag 1+ form, with the minor concentration (∼0.1% of total Ag) present as Ag 2+ . The findings by XPS and ESR are confirmed by the XRD, UV-vis spectroscopy and thermodynamic considerations. The supported Ag is highly dispersed on the surface of the titania support, with the particle size of ∼30-60 A depending on Ag content, with an Ag specific surface area of ∼7-14 m 2 /g, vs. the total surface area of ∼114-58 m 2 /g.

  9. Reverse osmosis desalination of chitosan cross-linked graphene oxide/titania hybrid lamellar membranes.

    Science.gov (United States)

    Deng, Hui; Sun, Penzhan; Zhang, Yingjiu; Zhu, Hongwei

    2016-07-08

    With excellent mass transport properties, graphene oxide (GO)-based lamellar membranes are believed to have great potential in water desalination. In order to quantify whether GO-based membranes are indeed suitable for reverse osmosis (RO) desalination, three sub-micrometer thick GO-based lamellar membranes: GO-only, reduced GO (RGO)/titania (TO) nanosheets and RGO/TO/chitosan (CTS) are prepared, and their RO desalination performances are evaluated in a home-made RO test apparatus. The photoreduction of GO by TO improves the salt rejection, which increases slowly with the membrane thickness. The RGO/TO/CTS hybrid membranes exhibit higher rejection rates of only about 30% (greater than threefold improvement compared with a GO-only membrane) which is still inferior compared to other commercial RO membranes. The low rejection rates mainly arise from the pressure-induced weakening of the ion-GO interlayer interactions. Despite the advantages of simple, low-cost preparation, high permeability and selectivity of GO-based lamellar membranes, as the current desalination performances are not high enough to afford practical application, there still remains a great challenge to realize high performance separation membranes for water desalination applications.

  10. Fabrication of Titania Nanotubes for Gas Sensing Applications

    Science.gov (United States)

    Dzilal, A. A.; Muti, M. N.; John, O. D.

    2010-03-01

    Detection of hydrogen is needed for industrial process control and medical applications where presence of hydrogen indicates different type of health problems. Titanium dioxide nanotube structure is chosen as an active component in the gas sensor because of its highly sensitive electrical resistance to hydrogen over a wide range of concentrations. The objective of the work is to fabricate good quality titania nanotubes suitable for hydrogen sensing applications. The fabrication method used is anodizing method. The anodizing parameters namely the voltage, time duration, concentration of hydrofluoric acid in water, separation between the electrodes and the ambient temperature are varied accordingly to find the optimum anodizing conditions for production of good quality titania nanotubes. The highly ordered porous titania nanotubes produced by this method are in tabular shape and have good uniformity and alignment over large areas. From the investigation done, certain set of anodizing parameters have been found to produce good quality titania nanotubes with diameter ranges from 47 nm to 94 nm.

  11. Fabrication of Inverted Bulk-Heterojunction Organic Solar Cell with Ultrathin Titanium Oxide Nanosheet as an Electron-Extracting Buffer Layer

    Science.gov (United States)

    Itoh, Eiji; Maruyama, Yasutake; Fukuda, Katsutoshi

    2012-02-01

    The contributions and deposition conditions of ultrathin titania nanosheet (TN) crystallites were studied in an inverted bulk-heterojunction (BHJ) cell in indium tin oxide (ITO)/titania nanosheet/poly(3-hexylthiophene) (P3HT):phenyl-C61-butyric acid methylester (PCBM) active layer/MoOx/Ag multilayered photovoltaic devices. Only one or two layers of poly(diallyldimethylammonium chloride) (PDDA) and TN multilayered film deposited by the layer-by-layer deposition technique effectively decreased the leakage current and increased both open circuit voltage (VOC) and fill factor (FF), and power conversion efficiency (η) was increased nearly twofold by the insertion of two TN layers. The deposition of additional TN layers caused the reduction in FF, and the abnormal S-shaped curves above VOC for the devices with three and four TN layers were ascribed to the interfacial potential barrier at the ITO/TN interface and the series resistance across the multilayers of TN and PDDA. The performance of the BHJ cell with TN was markedly improved, and the S-shaped curves were eliminated following the the insertion of anatase-phase titanium dioxide between the ITO and TN layers owing to the decrease in the interfacial potential barrier.

  12. Novel structuring routines of titania films for application in photovoltaics

    OpenAIRE

    Niedermeier, Martin A.

    2014-01-01

    Novel routines to structure titania thin films on various length scales are investigated regarding photovoltaic applications. The main focus of the investigations lies on the custom-tailoring of the morphologies of the titania films using sol-gel chemistry in combination with block copolymer templating. Additionally, a low-temperature routine for functional hybrid films as well as the growth of gold as electrode material on top of an organic hole-conductor are investigated. Im Hinblick auf...

  13. Plasma sprayed alumina-titania coatings

    International Nuclear Information System (INIS)

    Steeper, T.J.; Rotolico, A.J.; Nerz, J.E.; Riggs, W.L. II; Varacalle, D.J. Jr.; Wilson, G.C.

    1992-01-01

    This paper presents an experimental study of the air plasma spraying (APS) of alumina-titania powder using argon-hydrogen working gases. This powder system is being used in the fabrication of heater tubes that emulate nuclear fuel tubes for use in thermal-hydraulic testing. Experiments were conducted using a Taguchi fractional-factorial design parametric study. Operating parameters were varied around the typical spray parameters in a systematic design of experiments in order to display the range of plasma processing conditions and their effect on the resultant coatings. The coatings were characterized by hardness and electrical tests, surface profilometry, image analysis, optical metallography, and x-ray diffraction. Coating qualities are discussed with respect to dielectric strength, hardness, porosity, surface roughness, deposition efficiency, and microstructure. attempts are made to correlate the features of the coatings with the changes in operating parameters

  14. Controlled growth of silica-titania hybrid functional nanoparticles through a multistep microfluidic approach.

    Science.gov (United States)

    Shiba, K; Sugiyama, T; Takei, T; Yoshikawa, G

    2015-11-11

    Silica/titania-based functional nanoparticles were prepared through controlled nucleation of titania and subsequent encapsulation by silica through a multistep microfluidic approach, which was successfully applied to obtaining aminopropyl-functionalized silica/titania nanoparticles for a highly sensitive humidity sensor.

  15. Seeded Growth of Titania Colloids with Refractive Index Tunability and Fluorophore-Free Luminescence

    NARCIS (Netherlands)

    Demirors, A.F.; Jannasch, A.; van Oostrum, P.D.J.; Schäffer, E.; Imhof, A.; van Blaaderen, A.

    2011-01-01

    Titania is an important material in modern materials science, chemistry, and physics because of its special catalytic, electric, and optical properties. Here, we describe a novel method to synthesize colloidal particles with a crystalline titania, anatase core and an amorphous titania-shell

  16. Improving the photovoltaic performance of dye-sensitized solar cell by graphene/titania photoanode

    International Nuclear Information System (INIS)

    Zhao, Junchang; Wu, Jihuai; Zheng, Ming; Huo, Jinghao; Tu, Yongguang

    2015-01-01

    Highlights: • A colloid of graphene/titania is prepared, and thus a graphene/titania film is made. • The film shows high porosity, large surface area and small transfer resistance. • The cell with graphene/titania photoanode obtains a conversion efficiency of 7.52%. • Which is increased by 18% compared to the cell with pristine titania electrode. - Abstract: A mixed colloid of graphene and titania is synthesized by a one-step hydrothermal reaction, thus a graphene/titania film photoanode is prepared. The graphene/titania film shows high porosity and large specific surface area, which favors a full adsorption of sensitized dye. On the other hand, the graphene/titania electrode has smaller charge transfer resistance than the pristine titania electrode, which replies that the graphene/titania electrode accelerates electronic transportation and suppresses the charge recombination. Under an optimal condition, the dye-sensitized solar cell based on graphene/titania photoanode achieve a power conversion efficiency of 7.52%, which is increased by 17.7% compared to the cell based on the pristine titania electrode under a simulated solar light irradiation of 100 mW·cm −2

  17. Titania based nanocomposites as a photocatalyst: A review

    Directory of Open Access Journals (Sweden)

    Farha Modi

    2016-08-01

    Full Text Available Titanium dioxide or Titania is a semiconductor compound having remarkable dielectric, electronic and physico-chemical surface properties. It has excellent photocatalytic efficiency in presence of UV light. The curious grey matter of scientists has forced them to focus their attention to make Titania capable of utilizing the whole visible spectrum of light also. The hurdle that they faced was larger band gap of 3 eV and more, for this, efforts were directed towards adding other materials to Titania. The present article reviews the recent advances in the synthesis of different Titanium-based nanocomposite materials and their photocatalytic efficiency so as to apply them for several applications such as removal of dyes, other water pollutants, microbes and metals. A brief explanation of the photocatalytic process and the structural properties of TiO2 are also touched upon. Various past and recent approaches made in these directions of utilizing Titania based nanocomposites for photocatalytic activities are reviewed. It is suggested that there is a need to establish the kinetics of photo-corrosion and thermodynamic part of the photo-corrosion of various composites developed by different group across the globe, so that Titania based nanocomposites could be commercially utilized.

  18. In-situ deposition of hydroxyapatite on graphene nanosheets

    OpenAIRE

    Neelgund, Gururaj M.; Oki, Aderemi; Luo, Zhiping

    2013-01-01

    Graphene nanosheets were effectively functionalized by in-situ deposition of hydroxyaptite through a facile chemical precipitation method. Prior to grafting of hydroxyapatite, chemically modified graphene nanosheets were obtained by the reduction of graphene oxide in presence of ethylenediamine. The resulting hydroxyapatite functionalized graphene nanosheets were characterized by attenuated total reflection IR spectroscopy, X-ray diffraction, field emission scanning electron microscopy, trans...

  19. Green synthesis and characterization of graphene nanosheets

    Energy Technology Data Exchange (ETDEWEB)

    Tavakoli, Farnosh [School of Chemistry, College of Science, University of Tehran, Tehran (Iran, Islamic Republic of); Salavati-Niasari, Masoud, E-mail: salavati@kashanu.ac.ir [Institute of Nano Science and Nano Technology, University of Kashan, Kashan, P. O. Box. 87317-51167, Islamic Republic of Iran (Iran, Islamic Republic of); Department of Inorganic Chemistry, Faculty of Chemistry, University of Kashan, Kashan, P. O. Box. 87317-51167, Islamic Republic of Iran (Iran, Islamic Republic of); Badiei, Alireza [School of Chemistry, College of Science, University of Tehran, Tehran (Iran, Islamic Republic of); Mohandes, Fatemeh [Department of Inorganic Chemistry, Faculty of Chemistry, University of Kashan, Kashan, P. O. Box. 87317-51167, Islamic Republic of Iran (Iran, Islamic Republic of)

    2015-03-15

    Highlights: • For the first time, we have synthesized graphene nanosheets in the presence of pomegranate juice. • Here pomegranate juice was used not only as reductant but also as capping agent. • FT-IR, XRD, SEM, EDS and TEM were used to characterize the samples. • According to TEM image, graphene nanosheet is individually exfoliated after stirring for 24 h. • As shown in the TEM image, graphene monolayer is obtained. - Abstract: For the first time, we have successfully synthesized graphene nanosheets in the presence of pomegranate juice. In this approach, pomegranate juice was used not only as reductant but also as capping agent to form graphene nanosheets. At first, the improved Hummer method to oxidize graphite for the synthesis of graphene oxide (GO) was applied, and then the as-produced graphene oxide was reduced by pomegranate juice to form graphene nanosheets. Fourier transformed infrared (FT-IR), X-ray powder diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectrometry (EDS), high resolution transmission electron microscopy (HRTEM), atomic force microscopy (AFM) and raman were used to characterize the samples. The results obtained from the characterization techniques proved high purity of the final products.

  20. Green synthesis and characterization of graphene nanosheets

    International Nuclear Information System (INIS)

    Tavakoli, Farnosh; Salavati-Niasari, Masoud; Badiei, Alireza; Mohandes, Fatemeh

    2015-01-01

    Highlights: • For the first time, we have synthesized graphene nanosheets in the presence of pomegranate juice. • Here pomegranate juice was used not only as reductant but also as capping agent. • FT-IR, XRD, SEM, EDS and TEM were used to characterize the samples. • According to TEM image, graphene nanosheet is individually exfoliated after stirring for 24 h. • As shown in the TEM image, graphene monolayer is obtained. - Abstract: For the first time, we have successfully synthesized graphene nanosheets in the presence of pomegranate juice. In this approach, pomegranate juice was used not only as reductant but also as capping agent to form graphene nanosheets. At first, the improved Hummer method to oxidize graphite for the synthesis of graphene oxide (GO) was applied, and then the as-produced graphene oxide was reduced by pomegranate juice to form graphene nanosheets. Fourier transformed infrared (FT-IR), X-ray powder diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectrometry (EDS), high resolution transmission electron microscopy (HRTEM), atomic force microscopy (AFM) and raman were used to characterize the samples. The results obtained from the characterization techniques proved high purity of the final products

  1. Adsorption of vitamin E on mesoporous titania nanocrystals

    International Nuclear Information System (INIS)

    Shih, C.J.; Lin, C.T.; Wu, S.M.

    2010-01-01

    Tri-block nonionic surfactant and titanium chloride were used as starting materials for the synthesis of mesoporous titania nanocrystallite powders. The main objective of the present study was to examine the synthesis of mesoporous titania nanocrystals and the adsorption of vitamin E on those nanocrystals using X-ray diffraction (XRD), transmission electron microscopy, and nitrogen adsorption and desorption isotherms. When the calcination temperature was increased to 300 o C, the reflection peaks in the XRD pattern indicated the presence of an anatase phase. The crystallinity of the nanocrystallites increased from 80% to 98.6% with increasing calcination temperature from 465 o C to 500 o C. The N 2 adsorption data and XRD data taken after vitamin E adsorption revealed that the vitamin E molecules were adsorbed in the mesopores of the titania nanocrystals.

  2. Adsorption of vitamin E on mesoporous titania nanocrystals

    Energy Technology Data Exchange (ETDEWEB)

    Shih, C.J., E-mail: cjshih@kmu.edu.tw [Department of Fragrance and Cosmetic Science, Kaohsiung Medical University, Kaohsiung 807, Taiwan (China); Lin, C.T.; Wu, S.M. [School of Pharmacy, College of Pharmacy, Kaohsiung Medical University, Kaohsiung 807, Taiwan (China)

    2010-07-15

    Tri-block nonionic surfactant and titanium chloride were used as starting materials for the synthesis of mesoporous titania nanocrystallite powders. The main objective of the present study was to examine the synthesis of mesoporous titania nanocrystals and the adsorption of vitamin E on those nanocrystals using X-ray diffraction (XRD), transmission electron microscopy, and nitrogen adsorption and desorption isotherms. When the calcination temperature was increased to 300 {sup o}C, the reflection peaks in the XRD pattern indicated the presence of an anatase phase. The crystallinity of the nanocrystallites increased from 80% to 98.6% with increasing calcination temperature from 465 {sup o}C to 500 {sup o}C. The N{sub 2} adsorption data and XRD data taken after vitamin E adsorption revealed that the vitamin E molecules were adsorbed in the mesopores of the titania nanocrystals.

  3. The improved stability of enzyme encapsulated in biomimetic titania particles

    International Nuclear Information System (INIS)

    Jiang Yanjun; Sun Qianyun; Jiang Zhongyi; Zhang Lei; Li Jian; Li Lin; Sun Xiaohui

    2009-01-01

    This study demonstrates a novel biomimetic approach for the entrapment of yeast alcohol dehydrogenase (YADH) within titania nanoparticles to improve its stability. Protamine was as the template and catalyst for the condensation of titanium (IV) bis(ammonium lactato) dihydroxide (Ti-BALDH) into titania nanoparticles in which YADH was trapped. The as-prepared titania/protamine/YADH composites were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), dynamic light scattering (DLS), X-ray powder diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The mechanism of YADH encapsulation was tentatively proposed from a series of experimental results. The preliminary investigation showed that encapsulated YADH could retain most of its initial activity. Compared to free YADH, encapsulated YADH exhibited significantly improved thermal, pH and recycling stability. After 5 weeks storage, no substantial loss of catalytic activity for encapsulated YADH was observed

  4. M-Polynomials and Topological Indices of Titania Nanotubes

    Directory of Open Access Journals (Sweden)

    Mobeen Munir

    2016-10-01

    Full Text Available Titania is one of the most comprehensively studied nanostructures due to their widespread applications in the production of catalytic, gas sensing, and corrosion-resistant materials. M-polynomial of nanotubes has been vastly investigated, as it produces many degree-based topological indices, which are numerical parameters capturing structural and chemical properties. These indices are used in the development of quantitative structure-activity relationships (QSARs in which the biological activity and other properties of molecules, such as boiling point, stability, strain energy, etc., are correlated with their structure. In this report, we provide M-polynomials of single-walled titania (SW TiO2 nanotubes and recover important topological degree-based indices to theoretically judge these nanotubes. We also plot surfaces associated to single-walled titania (SW TiO2 nanotubes.

  5. Increased fibroblast functionality on CNN2-loaded titania nanotubes

    Directory of Open Access Journals (Sweden)

    Wei HB

    2012-02-01

    Full Text Available Hongbo Wei*, Shuyi Wu*, Zhihong Feng, Wei Zhou, Yan Dong, Guofeng Wu, Shizhu Bai, Yimin Zhao Department of Prosthodontics, School of Stomatology, Fourth Military Medical University, Xi'an, People's Republic of China *These authors contributed equally to this workAbstract: Infection and epithelial downgrowth are major problems associated with maxillofacial percutaneous implants. These complications are mainly due to the improper closure of the implant–skin interface. Therefore, designing a percutaneous implant that better promotes the formation of a stable soft tissue biologic seal around percutaneous sites is highly desirable. Additionally, the fibroblast has been proven to play an important role in the formation of biologic seals. In this study, titania nanotubes were filled with 11.2 kDa C-terminal CCN2 (connective tissue growth factor fragment, which could exert full CCN2 activity to increase the biological functionality of fibroblasts. This drug delivery system was fabricated on a titanium implant surface. CCN2 was loaded into anodized titania nanotubes using a simplified lyophilization method and the loading efficiency was approximately 80%. Then, the release kinetics of CCN2 from these nanotubes was investigated. Furthermore, the influence of CCN2-loaded titania nanotubes on fibroblast functionality was examined. The results revealed increased fibroblast adhesion at 0.25, 0.5, 1, 2, 4, and 24 hours, increased fibroblast viability over the course of 5 days, as well as enhanced actin cytoskeleton organization on CCN2-loaded titania nanotubes surfaces compared to uncoated, unmodified counterparts. Therefore, the results from this in vitro study demonstrate that CCN2-loaded titania nanotubes have the ability to increase fibroblast functionality and should be further studied as a method of promoting the formation of a stable soft tissue biologic seal around percutaneous sites.Keywords: anodization, titania nanotubes, adhesion, connective

  6. Tin-Platinum catalysts interactions on titania and silica

    International Nuclear Information System (INIS)

    Nava, N.; Del Angel, P.; Salmones, J.; Baggio-Saitovitch, E.; Santiago, P.

    2007-01-01

    Pt-Sn was supported on titania and silica, and the resulting interactions between the components in prepared samples and the resulting interactions between the components before and after treatment with hydrogen were characterized by Moessbauer spectroscopy, X-ray diffraction, Rietveld refinement, high-resolution transmission electron microscopy (HRTEM) and catalytic tests data. Results show the presence of Pt and SnO 2 after calcinations, and Pt 3 Sn, PtSn and PtSn 3 after reduction. Rietveld analysis shows that some Ti 4+ are replaced by Sn 4+ atoms in the titania structure. Finally, HRTEM and the practically absence of activity observed confirms that metallic platinum is encapsulated

  7. Photocatalytic composites based on titania nanoparticles and carbon nanomaterials

    International Nuclear Information System (INIS)

    Nguyen, Bich Ha; Nguyen, Van Hieu; Vu, Dinh Lam

    2015-01-01

    In this article we present a review on recent experimental works toward the formation of visible light responsive composite photocatalysts on the basis of titania nanoparticles and carbon nanomaterials of different types. The research results achieved in last years has shown that the nanocomposite photocatalysts comprising titania nanoparticles and graphene or graphene oxide sheets, and also nanoparticles of noble metals and metallic oxides, exhibited the evident priority compared to the others. Therefore our review emphasizes the research on these promising visible light responsive nanophotocatalysts. (review)

  8. Synthesis and characterization of natural hydroxyapatite (recycled) composites with titania

    International Nuclear Information System (INIS)

    Mendes Filho, Antonio Alves; Gouveia, Vitor Jose Pinto; Pereira, Renato Alves; Araujo, Fernando Gabriel da Silva; Sousa, Camila Mateus de

    2010-01-01

    Natural hydroxyapatite biphasic ceramics (recycled) with titania (TiO_2-Hap) were studied in this work. For the formation of such ceramic the powders were mixed natural hydroxyapatite obtained from veal bone by the hydrothermal method with titania (TiO_2), forming the composites H9T1. The powders, manually homogenized, were conformed in pellet and sintered at temperatures between 1200 and 1400 deg C The ceramic bodies were characterized by XRD and SEM/EDS. The initial results were not satisfactory and require new studies. (author)

  9. Hydrolysis and ion exchange of titania nanoparticles towards large-scale titania and titanate nanobelts for gas sensing applications

    International Nuclear Information System (INIS)

    Bela, Somaiah; Ho, Ghim Wei; Wong, Andrew See Weng

    2010-01-01

    One-dimensional titanate and titania nanostructures are prepared by hydrothermal method from titania nanoparticles precursor via hydrolysis and ion exchange processes. The formation mechanism and the reaction process of the nanobelts are elucidated. The effects of the NaOH concentration, HCl leaching duration and the calcination temperature on the morphology and chemical composition of the produced nanobelts are investigated. Na + ions of the titanate nanobelts can be effectively removed by longer acid leaching and neutralization process and transformed into metastable hydrogen titanate compound. A hybrid hydrogen titanate and anatase titania nanobelts can be obtained under dehydration process of 500 0 C. The nanobelts are produced in gram quantities and easily made into nanostructure paper for the bulk study on their electrical and sensing properties. The sensing properties of the nanobelts sheet are tested and exhibited response to H 2 gas.

  10. Total Scattering Analysis of Disordered Nanosheet Materials

    Science.gov (United States)

    Metz, Peter C.

    Two dimensional materials are of increasing interest as building blocks for functional coatings, catalysts, and electrochemical devices. While increasingly sophisticated processing routes have been designed to obtain high-quality exfoliated nanosheets and controlled, self-assembled mesostructures, structural characterization of these materials remains challenging. This work presents a novel method of analyzing pair distribution function (PDF) data for disordered nanosheet ensembles, where supercell stacking models are used to infer atom correlations over as much as 50 A. Hierarchical models are used to reduce the parameter space of the refined model and help eliminate strongly correlated parameters. Three data sets for restacked nanosheet assemblies with stacking disorder are analyzed using these methods: simulated data for graphene-like layers, experimental data for 1 nm thick perovskite layers, and experimental data for highly defective delta-MnO2 layers. In each case, the sensitivity of the PDF to the real-space distribution of layer positions is demonstrated by exploring the fit residual as a function of stacking vectors. The refined models demonstrate that nanosheets tend towards local interlayer ordering, which is hypothesized to be driven by the electrostatic potential of the layer surfaces. Correctly accounting for interlayer atom correlations permits more accurate refinement of local structural details including local structure perturbations and defect site occupancies. In the delta-MnO2 nanosheet material, the new modeling approach identified 14% Mn vacancies while application of 3D periodic crystalline models to the < 7 A PDF region suggests a 25% vacancy concentration. In contrast, the perovskite nanosheet material is demonstrated to exhibit almost negligible structural relaxation in contrast with the bulk crystalline material from which it is derived.

  11. Synthesis and polymorphic control for visible light active titania nanoparticles

    Science.gov (United States)

    Kaewgun, Sujaree

    Titania (TiO2) is useful for many applications in photocatalysis, antimicrobials, pigment, deodorization, and decomposition of harmful organics and undesirable compounds in the air and waste water under UV irradiation. Among the three phases of TiO2, Rutile, Anatase, and Brookite, studies have been more focused on the anatase and rutile phases. Pure brookite is the most difficult phase to prepare, even under hydrothermal conditions. Predominantly brookite phase TiO2 nanoparticles were prepared by the Water-based Ambient Condition Sol (WACS) process in our laboratory. The objectives of this research were to enhance visible light active (VLA) photocatalytic properties of polymorphic brookite TiO2 by minimizing the lattice defects and narrowing band gap of titania by nitrogen and/or carbon chromophone, and to investigate the deactivation, reusability, and regeneration of the VLA titania in order to design better titania catalysts for organic compound degradation applications. In order to study the influence of hydroxyl content on photocatalytic activities (PCAs) of polymorphic titania nanoparticles, the WACS samples were post-treated by a Solvent-based Ambient Condition Sol (SACS) process in sec-butanol (sec-BuOH). All samples were characterized for phase composition, surface area, hydroxyl contamination, and particle morphology by x-ray diffraction, N2 physisorption, FT-IR, solid state 1H NMR and scanning electron microscopy, and then compared to a commercial titania, Degussa P25. Evaluation of methyl orange (MO) degradation under UV irradiation results showed that the lower lattice hydroxyl content in SACS titania enhanced the PCA. As-prepared titania and SACS samples, which have similar surface areas and crystallinity, were compared in order to prove that the superior PCA came from the reduction in the lattice hydroxyl content. To enhance PCA and VLA properties of WACS, an alternative high boiling point polar solvent, N-methylpyrrolidone (NMP), was utilized in the

  12. Role of binder in the synthesis of titania membrane

    Indian Academy of Sciences (India)

    Unknown

    Abstract. The synthesis of titania membrane through sol–gel route involves hydrolysis of alkoxide, peptization of hydrous oxide of titanium to obtain a sol, adjustment of the sol viscosity by including a binder and filtration of the viscous sol through a microporous support, gelation and sintering to desired temperature.

  13. Role of binder in the synthesis of titania membrane

    Indian Academy of Sciences (India)

    The synthesis of titania membrane through sol–gel route involves hydrolysis of alkoxide, peptization of hydrous oxide of titanium to obtain a sol, adjustment of the sol viscosity by including a binder and filtration of the viscous sol through a microporous support, gelation and sintering to desired temperature. The binder plays ...

  14. Band Gap Engineering of Titania Systems Purposed for Photocatalytic Activity

    Science.gov (United States)

    Thurston, Cameron

    Ab initio computer aided design drastically increases candidate population for highly specified material discovery and selection. These simulations, carried out through a first-principles computational approach, accurately extrapolate material properties and behavior. Titanium Dioxide (TiO2 ) is one such material that stands to gain a great deal from the use of these simulations. In its anatase form, titania (TiO2 ) has been found to exhibit a band gap nearing 3.2 eV. If titania is to become a viable alternative to other contemporary photoactive materials exhibiting band gaps better suited for the solar spectrum, then the band gap must be subsequently reduced. To lower the energy needed for electronic excitation, both transition metals and non-metals have been extensively researched and are currently viable candidates for the continued reduction of titania's band gap. The introduction of multicomponent atomic doping introduces new energy bands which tend to both reduce the band gap and recombination loss. Ta-N, Nb-N, V-N, Cr-N, Mo-N, and W-N substitutions were studied in titania and subsequent energy and band gap calculations show a favorable band gap reduction in the case of passivated systems.

  15. Size and morphology effects of titania on dye-sensitized solar cells performance

    International Nuclear Information System (INIS)

    Chien, Wen-Chen; Lin, Chien-Chih; Jang, Shiue-Ming; Kao, Tien-Hsieh

    2013-01-01

    This study uses commercial titania (P25) to prepare titania nanowires (NWs) using alkali and hydrothermal treatments. Nanosized titania P25 and NWs were used to prepare spray-dried titania P25 (SP25) and spray-dried titania nanowires (SNWs), respectively, using the spray-drying process. These different titania sizes and morphologies were used to fabricate photoelectrodes for dye-sensitized solar cells (DSSCs) and to investigate their effect on cell performance. All prepared titania NWs and SNWs were in the anatase phase after heat treatment at 450 °C for 2 h. The specific areas for titania with different morphologies were 49.5 m 2 /g for P25, 48.3 m 2 /g for SP25, 42.6 m 2 /g for NWs, and 40.3 m 2 /g for SNWs. The results show that the surface areas decreased when the titania P25 or NWs were processed by spray drying. In optimal conditions, DSSCs prepared from P25 + 2.5 wt.% NWs with a light-to-electric energy conversion efficiency of 5.88% were produced using a simulated solar light irradiation of 100 mW/cm 2 (AM 1.5). - Highlights: • Titania with different size and morphology were prepared. • Hydrothermal and spray drying process were applied. • Solar cells with an efficiency of 5.88% were produced

  16. Size and morphology effects of titania on dye-sensitized solar cells performance

    Energy Technology Data Exchange (ETDEWEB)

    Chien, Wen-Chen, E-mail: wcchien@mail.mcut.edu.tw [Department of Chemical Engineering, Ming Chi University of Technology, 84 Gunjuan Road, New Taipei City 243, Taiwan (China); Battery Research Center of Green Energy, Ming Chi University of Technology, 84 Gunjuan Road, New Taipei City 243, Taiwan (China); Lin, Chien-Chih [Department of Chemical Engineering, Ming Chi University of Technology, 84 Gunjuan Road, New Taipei City 243, Taiwan (China); Jang, Shiue-Ming [Industrial Technology Research Institute, Hsinchu 310, Taiwan (China); Kao, Tien-Hsieh [Department of Chemical Engineering, Ming Chi University of Technology, 84 Gunjuan Road, New Taipei City 243, Taiwan (China)

    2013-10-01

    This study uses commercial titania (P25) to prepare titania nanowires (NWs) using alkali and hydrothermal treatments. Nanosized titania P25 and NWs were used to prepare spray-dried titania P25 (SP25) and spray-dried titania nanowires (SNWs), respectively, using the spray-drying process. These different titania sizes and morphologies were used to fabricate photoelectrodes for dye-sensitized solar cells (DSSCs) and to investigate their effect on cell performance. All prepared titania NWs and SNWs were in the anatase phase after heat treatment at 450 °C for 2 h. The specific areas for titania with different morphologies were 49.5 m{sup 2}/g for P25, 48.3 m{sup 2}/g for SP25, 42.6 m{sup 2}/g for NWs, and 40.3 m{sup 2}/g for SNWs. The results show that the surface areas decreased when the titania P25 or NWs were processed by spray drying. In optimal conditions, DSSCs prepared from P25 + 2.5 wt.% NWs with a light-to-electric energy conversion efficiency of 5.88% were produced using a simulated solar light irradiation of 100 mW/cm{sup 2} (AM 1.5). - Highlights: • Titania with different size and morphology were prepared. • Hydrothermal and spray drying process were applied. • Solar cells with an efficiency of 5.88% were produced.

  17. Boron nitride nanosheets reinforced glass matrix composites

    Czech Academy of Sciences Publication Activity Database

    Saggar, Richa; Porwal, H.; Tatarko, P.; Dlouhý, Ivo; Reece, M. J.

    2015-01-01

    Roč. 114, SEP (2015), S26-S32 ISSN 1743-6753 R&D Projects: GA MŠk(CZ) 7AMB14SK155 EU Projects: European Commission(XE) 264526 Institutional support: RVO:68081723 Keywords : Boron nitride nanosheets * Borosilicate glass * Mechanical properties Subject RIV: JL - Materials Fatigue, Friction Mechanics Impact factor: 1.162, year: 2015

  18. Nickel-cobalt hydroxide nanosheets: Synthesis, morphology and electrochemical properties.

    Science.gov (United States)

    Schneiderová, Barbora; Demel, Jan; Zhigunov, Alexander; Bohuslav, Jan; Tarábková, Hana; Janda, Pavel; Lang, Kamil

    2017-08-01

    This paper reports the synthesis, characterization, and electrochemical performance of nickel-cobalt hydroxide nanosheets. The hydroxide nanosheets of approximately 0.7nm thickness were prepared by delamination of layered nickel-cobalt hydroxide lactate in water and formed transparent colloids that were stable for months. The nanosheets were deposited on highly oriented pyrolytic graphite by spin coating, and their electrochemical behavior was investigated by cyclic voltammetry in potassium hydroxide electrolyte. Our method of electrode preparation allows for studying the electrochemistry of nanosheets where the majority of the active centers can participate in the charge transfer reaction. The observed electrochemical response was ascribed to mutual compensation of the cobalt and nickel response via electron sharing between these metals in the hydroxide nanosheets, a process that differentiates the behavior of nickel-cobalt hydroxide nanosheets from single nickel hydroxide or cobalt hydroxide nanosheets or their physical mixture. The presence of cobalt in the nickel-cobalt hydroxide nanosheets apparently decreases the time of electrochemical activation of the nanosheet layer, which for the nickel hydroxide nanosheets alone requires more potential sweeps. Copyright © 2017 Elsevier Inc. All rights reserved.

  19. Synthesis of mesoporous titania by homogeneous hydrolysis of titania oxo-sulfate in the presence of cationic and anionic surfactants

    Czech Academy of Sciences Publication Activity Database

    Štengl, Václav; Houšková, Vendula; Murafa, Nataliya; Bakardjieva, Snejana

    2010-01-01

    Roč. 54, č. 4 (2010), s. 368-378 ISSN 0862-5468 R&D Projects: GA ČR GA203/08/0334 Institutional research plan: CEZ:AV0Z40320502 Keywords : surfactant * titania * mesoporous * photocatalyst Subject RIV: CA - Inorganic Chemistry Impact factor: 0.297, year: 2010

  20. Performance engineering of dye sensitized solar cells (DSSC) using Ag modified titania as photoanode

    Science.gov (United States)

    Nair, Ranjith G.; Mathan Kumar, P.; Samdarshi, S. K.

    2018-01-01

    Present work reports the fabrication of silver (Ag) modified titania photoanode as an efficient photoanode for Dye Sensitized Solar Cell (DSSC). Pristine and Ag modified Titania nanomaterials were prepared using sol gel method. The structural analyses confirm the high crystallinity of the samples with crystallite size distribution in nanorange. TEM micrograph confirms that the synthesized nanomaterials are in uniform size. A red shift is observed in the UV DRS spectra compared to pristine Titania and which confirm the incorporation of Ag inside titania. A prototype DSSC was fabricated using the pristine and modified Titania as photoanode, Ruthenium dye as sensitizer, I-/I-3 as redox electrolyte and platinum counter electrode. The cell with Ag modified titania photoanode showed 15 times enhanced photoconversion efficiency (PCE) than the pristine one. This improved performance of the Ag modified DSSC can be ascribed to reduced recombination and improved charge carrier transport of electrons/holes at the interfaces.

  1. Vapor phase modification of sol-gel derived titania (TiO{sub 2}) surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Piwonski, Ireneusz [University of Lodz, Department of Chemical Technology and Environmental Protection, Pomorska 163, 90-236 Lodz (Poland)]. E-mail: irek@uni.lodz.pl; Ilik, Aneta [University of Lodz, Department of Chemical Technology and Environmental Protection, Pomorska 163, 90-236 Lodz (Poland)

    2006-12-30

    Chemical vapor deposition (CVD) method was used in titania surface modification. Titania layers were obtained in sol-gel process and prepared as thin films on silicon wafers in dip-coating method. In order to define the influence of modification on titania surface properties (e.g., friction), various types of fluoroalkylsilanes were used. The effectiveness of the modification was monitored by FT-IR spectroscopy. The topography and frictional measurements were investigated with the use of atomic force microscopy (AFM)

  2. Development of a dielectric ceramic based on diatomite-titania part two: dielectric properties characterization

    Directory of Open Access Journals (Sweden)

    Medeiros Jamilson Pinto

    1998-01-01

    Full Text Available Dielectric properties of sintered diatomite-titania ceramics are presented. Specific capacitance, dissipation factor, quality factor and dielectric constant were determined as a function of sintering temperature, titania content and frequency; the temperature coefficient of capacitance was measured as a function of frequency. Besides leakage current, the dependence of the insulation resistance and the dielectric strength on the applied dc voltage were studied. The results show that diatomite-titania compositions can be used as an alternative dielectric.

  3. Performance enhancement of direct ethanol fuel cell using Nafion composites with high volume fraction of titania

    Science.gov (United States)

    Matos, B. R.; Isidoro, R. A.; Santiago, E. I.; Fonseca, F. C.

    2014-12-01

    The present study reports on the performance enhancement of direct ethanol fuel cell (DEFC) at 130 °C with Nafion-titania composite electrolytes prepared by sol-gel technique and containing high volume fractions of the ceramic phase. It is found that for high volume fractions of titania (>10 vol%) the ethanol uptake of composites is largely reduced while the proton conductivity at high-temperatures is weakly dependent on the titania content. Such tradeoff between alcohol uptake and conductivity resulted in a boost of DEFC performance at high temperatures using Nafion-titania composites with high fraction of the inorganic phase.

  4. In situ deposition of hydroxyapatite on graphene nanosheets

    International Nuclear Information System (INIS)

    Neelgund, Gururaj M.; Oki, Aderemi; Luo, Zhiping

    2013-01-01

    Graphical abstract: A facile chemical precipitation method is reported for effective in situ deposition of hydroxyapatite on graphene nanosheets. Prior to grafting of hydroxyapatite, chemically modified graphene nanosheets were obtained by the reduction of graphene oxide in presence of ethylenediamine. Display Omitted Highlights: ► It is a facile and effective method for deposition of HA on GR nanosheets. ► It avoids the use of harmful reducing agents like hydrazine, NaBH 4 etc. ► GR nanosheets were produced using bio-compatible, ethylenediamine. ► The graphitic structure of synthesized GR nanosheets was high ordered. ► The ratio of Ca to P in HA was 1.64, which is close to ratio in natural bone. -- Abstract: Graphene nanosheets were effectively functionalized by in situ deposition of hydroxyapatite through a facile chemical precipitation method. Prior to grafting of hydroxyapatite, chemically modified graphene nanosheets were obtained by the reduction of graphene oxide in presence of ethylenediamine. The resulting hydroxyapatite functionalized graphene nanosheets were characterized by attenuated total reflection IR spectroscopy, X-ray diffraction, field emission scanning electron microscopy, transmission electron microscopy, X-ray energy dispersive spectroscopy, Raman spectroscopy and thermogravimetric analysis. These characterization techniques revealed the successful grafting of hydroxyapatite over well exfoliated graphene nanosheets without destroying their structure.

  5. In situ deposition of hydroxyapatite on graphene nanosheets

    Energy Technology Data Exchange (ETDEWEB)

    Neelgund, Gururaj M. [Department of Chemistry, Prairie View A and M University, Prairie View, TX 77446 (United States); Oki, Aderemi, E-mail: aroki@pvamu.edu [Department of Chemistry, Prairie View A and M University, Prairie View, TX 77446 (United States); Luo, Zhiping [Microscopy and Imaging Center and Materials Science and Engineering Program, Texas A and M University, College Station, TX 77843 (United States)

    2013-02-15

    Graphical abstract: A facile chemical precipitation method is reported for effective in situ deposition of hydroxyapatite on graphene nanosheets. Prior to grafting of hydroxyapatite, chemically modified graphene nanosheets were obtained by the reduction of graphene oxide in presence of ethylenediamine. Display Omitted Highlights: ► It is a facile and effective method for deposition of HA on GR nanosheets. ► It avoids the use of harmful reducing agents like hydrazine, NaBH{sub 4} etc. ► GR nanosheets were produced using bio-compatible, ethylenediamine. ► The graphitic structure of synthesized GR nanosheets was high ordered. ► The ratio of Ca to P in HA was 1.64, which is close to ratio in natural bone. -- Abstract: Graphene nanosheets were effectively functionalized by in situ deposition of hydroxyapatite through a facile chemical precipitation method. Prior to grafting of hydroxyapatite, chemically modified graphene nanosheets were obtained by the reduction of graphene oxide in presence of ethylenediamine. The resulting hydroxyapatite functionalized graphene nanosheets were characterized by attenuated total reflection IR spectroscopy, X-ray diffraction, field emission scanning electron microscopy, transmission electron microscopy, X-ray energy dispersive spectroscopy, Raman spectroscopy and thermogravimetric analysis. These characterization techniques revealed the successful grafting of hydroxyapatite over well exfoliated graphene nanosheets without destroying their structure.

  6. NiO nanosheet assembles for supercapacitor electrode materials

    OpenAIRE

    Huanhao Xiao; Shunyu Yao; Hongda Liu; Fengyu Qu; Xu Zhang; Xiang Wu

    2016-01-01

    In this paper, large scale hierarchically assembled NiO nanosheets have been favorably fabricated through a facile hydrothermal route. The as-prepared NiO nanosheet assembles were characterized in detail by various analytical techniques. The results showed these nanosheets present the thickness of about 30 nm and the surface area is 116.9 m2 g−1. These NiO nanosheet assembles were used as the working electrode materials in electrochemical tests, which demonstrated a specific capacitance value...

  7. Tin-Platinum catalysts interactions on titania and silica

    Energy Technology Data Exchange (ETDEWEB)

    Nava, N. [Instituto Mexicano del Petroleo Lazaro Cardenas 152, 07730 Mexico, D.F. (Mexico)], E-mail: tnava@imp.mx; Del Angel, P. [Instituto Mexicano del Petroleo Lazaro Cardenas 152, 07730 Mexico, D.F. (Mexico); Salmones, J. [Instituto Politecnico Nacional-ESIQIE UPALM, 07738 Mexico, D.F. (Mexico); Baggio-Saitovitch, E. [Centro Brasileiro de Pesquisas Fisicas, Rua Dr. Xavier Sigaud 150, 22290-180 Rio de Janeiro, Brasil (Brazil); Santiago, P. [Instituto de Fisica, UNAM, Mexico, D. F., 04510 Mexico (Mexico)

    2007-09-30

    Pt-Sn was supported on titania and silica, and the resulting interactions between the components in prepared samples and the resulting interactions between the components before and after treatment with hydrogen were characterized by Moessbauer spectroscopy, X-ray diffraction, Rietveld refinement, high-resolution transmission electron microscopy (HRTEM) and catalytic tests data. Results show the presence of Pt and SnO{sub 2} after calcinations, and Pt{sub 3}Sn, PtSn and PtSn{sub 3} after reduction. Rietveld analysis shows that some Ti{sup 4+} are replaced by Sn{sup 4+} atoms in the titania structure. Finally, HRTEM and the practically absence of activity observed confirms that metallic platinum is encapsulated.

  8. Photoelectrochemical reactivity of polyoxophosphotungstates embedded in titania tubules

    International Nuclear Information System (INIS)

    Xie Yibing

    2006-01-01

    A highly ordered and crystallized titania (TiO 2 ) nanotube array is fabricated by a low-voltage anodization plus a post-embedding calcination process. Polyoxophosphotungstate-titania (POPTA-TiO 2 ) composite catalyst is synthesized by embedding POPTA in TiO 2 tubule channels to improve the photoelectrochemical properties. The morphological characteristics and crystal behaviour of POPTA-TiO 2 are examined by field-emission scanning electron microscopy and x-ray diffraction. The stability of the chemical structure has been analysed by Fourier transformed infrared spectroscopy measurements. The photoelectrochemical properties are investigated by means of the polarization current response. Photocatalytic and photoelectrocatalytic reactivities for the degradation of an endocrine disrupting chemical have also been investigated to examine the photoelectrochemical reaction efficiency of POPTA-TiO 2 composite catalyst

  9. Lithium ion batteries with titania/graphene anodes

    Science.gov (United States)

    Liu, Jun; Choi, Daiwon; Yang, Zhenguo; Wang, Donghai; Graff, Gordon L; Nie, Zimin; Viswanathan, Vilayanur V; Zhang, Jason; Xu, Wu; Kim, Jin Yong

    2013-05-28

    Lithium ion batteries having an anode comprising at least one graphene layer in electrical communication with titania to form a nanocomposite material, a cathode comprising a lithium olivine structure, and an electrolyte. The graphene layer has a carbon to oxygen ratio of between 15 to 1 and 500 to 1 and a surface area of between 400 and 2630 m.sup.2/g. The nanocomposite material has a specific capacity at least twice that of a titania material without graphene material at a charge/discharge rate greater than about 10 C. The olivine structure of the cathode of the lithium ion battery of the present invention is LiMPO.sub.4 where M is selected from the group consisting of Fe, Mn, Co, Ni and combinations thereof.

  10. Adherence and scratching resistance of nanometric titania films

    International Nuclear Information System (INIS)

    Pascoali, S.; Dominguini, L.; Borges, J.B.

    2012-01-01

    TiO 2 films has been used to extend the wear resistance in bearing, seals for pumps and bone prostheses. In this study was analyzed the conventional hardness and scratch toughness. The scratching test equipment used was developed at the Laboratory of materials Labmat / UFSC. The tests were performed on Titania films deposited on glass plates and ceramics via reactive DC magnetron sputtering. The films were deposited by 10, 15 and 60 min. One of the samples has a titanium metal film of a few nanometers thick between the substrate and the Titania film, the oxide has been deposited for 30 min. At this rang of tests loads the deposited films show good adhesion to substrate, there was no cracking or spalling of the film. (author)

  11. EFFECTS OF SYNTHESIS PARAMETERS ON THE STRUCTURE OF TITANIA NANOTUBES

    Directory of Open Access Journals (Sweden)

    M. NORANI MUTI

    2008-08-01

    Full Text Available Detection of hydrogen is crucial for industrial process control and medical applications where presence of hydrogen in breath indicates different type of health problems particularly in infants. A better performed sensor with high sensitivity, selectivity, reliability and faster response time would be critical and sought after especially for medical applications. Titanium dioxide nanotube structure is chosen as an active component in the gas sensor because of its highly sensitive electrical resistance to hydrogen over a wide range of concentrations. The objective of the work is to investigate the effect of the anodizing conditions on the structure of titania nanotubes produced by anodizing method. The anodizing parameters namely the ambient temperature and separation of electrodes are varied accordingly to find the optimum anodizing conditions for production of good quality titania nanotubes for enhanced properties based on their uniformity, coverage, pore size and crystallinity. Samples of nanotubes produced were subjected to annealing process at varying time and temperature in order to improve the crystallinity of the nanotubes. The highly ordered porous titania nanotubes produced by this method are of tabular shape and have good uniformity and alignment over large areas. The pore size of the titania nanotubes ranges from 47 to 94 nm, while the wall thickness is in the range of 17 to 26 nm. The length of the nanotubes was found to be about 280 nm. The structure of nanotubes changes from amorphous to crystalline after undergoing annealing treatment. Nanotubes have also shown to have better crystallinity if they were subjected to annealing treatment at higher temperature. The characteristics of nanotubes obtained are found to be agreeable to those that have been reported to show improved hydrogen gas sensing properties.

  12. Titania may produce abiotic oxygen atmospheres on habitable exoplanets

    OpenAIRE

    Norio Narita; Takafumi Enomoto; Shigeyuki Masaoka; Nobuhiko Kusakabe

    2015-01-01

    The search for habitable exoplanets in the Universe is actively ongoing in the field of astronomy. The biggest future milestone is to determine whether life exists on such habitable exoplanets. In that context, oxygen in the atmosphere has been considered strong evidence for the presence of photosynthetic organisms. In this paper, we show that a previously unconsidered photochemical mechanism by titanium (IV) oxide (titania) can produce abiotic oxygen from liquid water under near ultraviolet ...

  13. Lamellar Micelles - Mediated Synthesis of Nanoscale Thick Sheets of Titania

    Czech Academy of Sciences Publication Activity Database

    Klusoň, P.; Lusková, H.; Šolcová, Olga; Matějová, Lenka; Cajthaml, Tomáš

    2007-01-01

    Roč. 61, 14-15 (2007), s. 2931-2934 ISSN 0167-577X R&D Projects: GA ČR(CZ) GA104/04/0963; GA ČR(CZ) GD203/03/H140 Institutional research plan: CEZ:AV0Z40720504; CEZ:AV0Z50200510 Keywords : nanostructures * lamellar titania * templating Subject RIV: CA - Inorganic Chemistry Impact factor: 1.625, year: 2007

  14. Intrinsic ferromagnetism in hexagonal boron nitride nanosheets

    Energy Technology Data Exchange (ETDEWEB)

    Si, M. S.; Gao, Daqiang, E-mail: gaodq@lzu.edu.cn, E-mail: xueds@lzu.edu.cn; Yang, Dezheng; Peng, Yong; Zhang, Z. Y.; Xue, Desheng, E-mail: gaodq@lzu.edu.cn, E-mail: xueds@lzu.edu.cn [Key Laboratory for Magnetism and Magnetic Materials of the Ministry of Education, Lanzhou University, Lanzhou 730000 (China); Liu, Yushen [Jiangsu Laboratory of Advanced Functional Materials and College of Physics and Engineering, Changshu Institute of Technology, Changshu 215500 (China); Deng, Xiaohui [Department of Physics and Electronic Information Science, Hengyang Normal University, Hengyang 421008 (China); Zhang, G. P. [Department of Physics, Indiana State University, Terre Haute, Indiana 47809 (United States)

    2014-05-28

    Understanding the mechanism of ferromagnetism in hexagonal boron nitride nanosheets, which possess only s and p electrons in comparison with normal ferromagnets based on localized d or f electrons, is a current challenge. In this work, we report an experimental finding that the ferromagnetic coupling is an intrinsic property of hexagonal boron nitride nanosheets, which has never been reported before. Moreover, we further confirm it from ab initio calculations. We show that the measured ferromagnetism should be attributed to the localized π states at edges, where the electron-electron interaction plays the role in this ferromagnetic ordering. More importantly, we demonstrate such edge-induced ferromagnetism causes a high Curie temperature well above room temperature. Our systematical work, including experimental measurements and theoretical confirmation, proves that such unusual room temperature ferromagnetism in hexagonal boron nitride nanosheets is edge-dependent, similar to widely reported graphene-based materials. It is believed that this work will open new perspectives for hexagonal boron nitride spintronic devices.

  15. The immobilization of titania nanoparticles on hyaluronan films and their photocatalytic properties

    International Nuclear Information System (INIS)

    Pasqui, Daniela; Atrei, Andrea; Barbucci, Rolando

    2009-01-01

    We have developed a method to bind titania nanoparticles onto hyaluronic films (HA) photoimmobilized on silanized glass. Titania nanoparticles were deposited on the HA films from commercially available dispersions by casting and dip-coating methods at various pH values. XPS was used to monitor the deposition of titania and to estimate the surface coverage of the nanoparticles. The topography of the titania-modified HA films was investigated by means of AFM. XPS results indicate that the titania surface coverage depends on the preparation method and the pH of the dispersion. We found that the maximum titania nanoparticle surface coverage was obtained by the casting method with the formation of aggregates and multilayers of particles. The titania surface coverage for the surfaces prepared by the dip-coating method is pH-dependent. The surfaces prepared at pH 2 show a surface coverage of 65% and a rather uniform distribution of particles. We found that titania nanoparticles are anchored in a stable way to the HA substrate in a phosphate buffer solution (PBS) and that the interaction between the HA and the titania is through the carbonyl group of carboxylates and amidic groups of the polymer. AFM images clearly show that titania nanoparticles are uniformly distributed over the HA films. By measuring the average diameter and the average height of the nanoparticles deposited on HA films it appears that the particles are partially embedded in the polysaccharide films. The results of the study on the photobleaching of methylene blue indicate that the characteristic photocatalytic activity of titania is maintained when the nanoparticles are anchored to the HA substrate.

  16. Fabrication and structural characterization of highly ordered titania nanotube arrays

    Science.gov (United States)

    Shi, Hongtao; Ordonez, Rosita

    Titanium (Ti) dioxide nanotubes have drawn much attention in the past decade due to the fact that titania is an extremely versatile material with a variety of technological applications. Anodizing Ti in different electrolytes has proved to be quite successful so far in creating the nanotubes, however, their degree of order is still not nearly as good as nanoporous anodic alumina. In this work, we first deposit a thin layer of aluminum (Al) onto electropolished Ti substrates, using thermal evaporation. Such an Al layer is then anodized in 0.3 M oxalic acid, forming an ordered nanoporous alumina mask on top of Ti. Afterwards, the anodization of Ti is accomplished at 20 V in solutions containing 1 M NaH2PO4 and 0.5% HF or H2SO4, which results in the creation of ordered titania nanotube arrays. The inner pore diameter of the nanotubes can be tuned from ~50 nm to ~75 nm, depending on the anodization voltage applied to Al or Ti. X-ray diffractometry shows the as-grown titania nanotubes are amorphous. Samples annealed at different temperatures in ambient atmosphere will be also reported.

  17. Titania may produce abiotic oxygen atmospheres on habitable exoplanets.

    Science.gov (United States)

    Narita, Norio; Enomoto, Takafumi; Masaoka, Shigeyuki; Kusakabe, Nobuhiko

    2015-09-10

    The search for habitable exoplanets in the Universe is actively ongoing in the field of astronomy. The biggest future milestone is to determine whether life exists on such habitable exoplanets. In that context, oxygen in the atmosphere has been considered strong evidence for the presence of photosynthetic organisms. In this paper, we show that a previously unconsidered photochemical mechanism by titanium (IV) oxide (titania) can produce abiotic oxygen from liquid water under near ultraviolet (NUV) lights on the surface of exoplanets. Titania works as a photocatalyst to dissociate liquid water in this process. This mechanism offers a different source of a possibility of abiotic oxygen in atmospheres of exoplanets from previously considered photodissociation of water vapor in upper atmospheres by extreme ultraviolet (XUV) light. Our order-of-magnitude estimation shows that possible amounts of oxygen produced by this abiotic mechanism can be comparable with or even more than that in the atmosphere of the current Earth, depending on the amount of active surface area for this mechanism. We conclude that titania may act as a potential source of false signs of life on habitable exoplanets.

  18. Synthesis of erbium oxide nanosheets and up-conversion properties

    DEFF Research Database (Denmark)

    Chen, X. B.; Wang, Cen; Hu, X.R.

    2011-01-01

    A novel erbium-based compound as well as Er2O3 nanosheets have been synthesized through a simple hydrothermal route. The nanosheets are of 200 nm width and 10–15 nm thickness. It is suggested that this erbium-based compound has a possible formula of Er2O5H4 with a primitive tetragonal structure (...

  19. Surface Properties of Photocatalytic Nano-Crystalline Titania Films and Reactor for Photocatalytic Degradation of Chloroform

    DEFF Research Database (Denmark)

    Søgaard, Erik Gydesen; Simonsen, Morten Enggrob; Jensen, Henrik

    2006-01-01

    In this work two immobilizations techniques of TiO2 onto glass were investigated; deposition of previously made titania powder (PMTP) and a sol-gel method. The titania powder used in this work was Degussa P25, Hombikat UV100 and a powder prepared in our laboratory SC134. The prepared TiO2 films w...

  20. Synthesis of eccentric titania-silica core-shell and composite particles

    NARCIS (Netherlands)

    Demirors, A.F.; van Blaaderen, A.; Imhof, A.

    2009-01-01

    We describe a novel method to synthesize colloidal particles with an eccentric core-shell structure. Titania-silica core-shell particles were synthesized by silica coating of porous titania particles under Sto¨ber (Sto¨ber et al. J. Colloid Interface Sci. 1968, 26, 62) conditions. We can control

  1. Flexible Lithium-Ion Fiber Battery by the Regular Stacking of Two-Dimensional Titanium Oxide Nanosheets Hybridized with Reduced Graphene Oxide.

    Science.gov (United States)

    Hoshide, Tatsumasa; Zheng, Yuanchuan; Hou, Junyu; Wang, Zhiqiang; Li, Qingwen; Zhao, Zhigang; Ma, Renzhi; Sasaki, Takayoshi; Geng, Fengxia

    2017-06-14

    Increasing interest has recently been devoted to developing small, rapid, and portable electronic devices; thus, it is becoming critically important to provide matching light and flexible energy-storage systems to power them. To this end, compared with the inevitable drawbacks of being bulky, heavy, and rigid for traditional planar sandwiched structures, linear fiber-shaped lithium-ion batteries (LIB) have become increasingly important owing to their combined superiorities of miniaturization, adaptability, and weavability, the progress of which being heavily dependent on the development of new fiber-shaped electrodes. Here, we report a novel fiber battery electrode based on the most widely used LIB material, titanium oxide, which is processed into two-dimensional nanosheets and assembled into a macroscopic fiber by a scalable wet-spinning process. The titania sheets are regularly stacked and conformally hybridized in situ with reduced graphene oxide (rGO), thereby serving as efficient current collectors, which endows the novel fiber electrode with excellent integrated mechanical properties combined with superior battery performances in terms of linear densities, rate capabilities, and cyclic behaviors. The present study clearly demonstrates a new material-design paradigm toward novel fiber electrodes by assembling metal oxide nanosheets into an ordered macroscopic structure, which would represent the most-promising solution to advanced flexible energy-storage systems.

  2. Evaluation of the Morphology and Osteogenic Potential of Titania-Based Electrospun Nanofibers

    Directory of Open Access Journals (Sweden)

    Xiaokun Wang

    2012-01-01

    Full Text Available Submicron-scale titania-based ceramic fibers with various compositions have been prepared by electrospinning. The as-prepared nanofibers were heat-treated at 700°C for 3 h to obtain pure inorganic fiber meshes. The results show that the diameter and morphology of the nanofibers are affected by starting polymer concentration and sol-gel composition. The titania and titania-silica nanofibers had the average diameter about 100–300 nm. The crystal phase varied from high-crystallized rutile-anatase mixed crystal to low-crystallized anatase with adding the silica addition. The morphology and crystal phase were evaluated by SEM and XRD. Bone-marrow-derived mesenchymal stem cells were seeded on titania-silica 50/50 fiber meshes. Cell number and early differentiation marker expressions were analyzed, and the results indicated osteogenic potential of the titania-silica 50/50 fiber meshes.

  3. Structurally stabilized organosilane-templated thermostable mesoporous titania.

    Science.gov (United States)

    Amoli, Vipin; Tiwari, Rashmi; Dutta, Arghya; Bhaumik, Asim; Sinha, Anil Kumar

    2014-01-13

    Structurally thermostable mesoporous anatase TiO2 (m-TiO2) nanoparticles, uniquely decorated with atomically dispersed SiO2, is reported for the first time. The inorganic Si portion of the novel organosilane template, used as a mesopores-directing agent, is found to be incorporated in the pore walls of the titania aggregates, mainly as isolated sites. This is evident by transmission electron microscopy and high-angle annular dark field scanning transmission electron microscopy, combined with electron dispersive X-ray spectroscopy. This type of unique structure provides exceptional stability to this new material against thermal collapse of the mesoporous structure, which is reflected in its high surface area (the highest known for anatase titania), even after high-temperature (550 °C) calcination. Control of crystallite size, pore diameter, and surface area is achieved by varying the molar ratios of the titanium precursor and the template during synthesis. These mesoporous materials retain their porosity and high surface area after template removal and further NaOH/HCl treatment to remove silica. We investigate their performance for dye-sensitized solar cells (DSSCs) with bilayer TiO2 electrodes, which are prepared by applying a coating of m-TiO2 onto a commercial titania (P25) film. The high surface area of the upper mesoporous layer in the P25-m-TiO2 DSSC significantly increases the dye loading ability of the photoanode. The photocurrent and fill factor for the DSSC with the bilayer TiO2 electrode are greatly improved. The large increase in photocurrent current (ca. 56%) in the P25-m-TiO2 DSSC is believed to play a significant role in achieving a remarkable increase in the photovoltaic efficiency (60%) of the device, compared to DSSCs with a monolayer of P25 as the electrode. Copyright © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. Recent progress in mesoporous titania materials: adjusting morphology for innovative applications

    Directory of Open Access Journals (Sweden)

    Juan L Vivero-Escoto, Ya-Dong Chiang, Kevin C-W Wu and Yusuke Yamauchi

    2012-01-01

    Full Text Available This review article summarizes recent developments in mesoporous titania materials, particularly in the fields of morphology control and applications. We first briefly introduce the history of mesoporous titania materials and then review several synthesis approaches. Currently, mesoporous titania nanoparticles (MTNs have attracted much attention in various fields, such as medicine, catalysis, separation and optics. Compared with bulk mesoporous titania materials, which are above a micrometer in size, nanometer-sized MTNs have additional properties, such as fast mass transport, strong adhesion to substrates and good dispersion in solution. However, it has generally been known that the successful synthesis of MTNs is very difficult owing to the rapid hydrolysis of titanium-containing precursors and the crystallization of titania upon thermal treatment. Finally, we review four emerging fields including photocatalysis, photovoltaic devices, sensing and biomedical applications of mesoporous titania materials. Because of its high surface area, controlled porous structure, suitable morphology and semiconducting behavior, mesoporous titania is expected to be used in innovative applications.

  5. Hybrids of ethylene vinyl acetate with Na-montmorillonite and titania: preparation and characterization

    International Nuclear Information System (INIS)

    Ashfaq, M.

    2010-01-01

    Hybrids of Ethylene vinyl acetate (EVA) with Na-montmorillonite and titania were formed. Montmorillonite was organically modified by two different modifiers: Pyridinium ions and 4. 4-oxydianilinium ions. X-ray diffraction results revealed that Pyridinium ions increased the .interlayer spacing by 0.33 nm and 4, 4-oxydianilinium by 0.55 nm approximately. These modified organo-clays were successfully exfoliated in EVA using melt blending. These hybrids showed improvement in mechanical and thermal properties. 4, 4-oxydianilinium ions were degraded at higher temperature due to which thermal degradation was enhanced in EVA. In addition to this, EVA/titania hybrids were also prepared using sot-gel technique and modified by triethoxy vinyl silane and (3-aminopropyI)- triethoxy silane to increase their compatibility with EVA. Some portion of unmodified titania was heat treated to 600 degree C to obtain particulate titania. The hybrid of particulate titania and modified titania improved the mechanical properties and thermal properties. Especially in case of modified titania toughness was almost doubled. (author)

  6. Tuning electronic and magnetic properties of GaN nanosheets by surface modifications and nanosheet thickness.

    Science.gov (United States)

    Xiao, Meixia; Yao, Tingzhen; Ao, Zhimin; Wei, Peng; Wang, Danghui; Song, Haiyang

    2015-04-14

    Density-functional theory calculations are performed to investigate the effects of surface modifications and nanosheet thickness on the electronic and magnetic properties of gallium nitride (GaN) nanosheets (NSs). Unlike the bare GaN NSs terminating with polar surfaces, the systems with hydrogenated Ga (H-GaN), fluorinated Ga (F-GaN), and chlorinated Ga (Cl-GaN) preserve their initial wurtzite structures and exhibit ferromagnetic states. The abovementioned three different decorations on Ga atoms are energetically more favorable for thicker GaN NSs. Moreover, as the thickness increases, H-GaN and F-GaN NSs undergo semiconductor to metal and half-metal to metal transition, respectively, while Cl-GaN NSs remain completely metallic. The predicted diverse and tunable electronic and magnetic properties highlight the potential of GaN NSs for novel electronic and spintronic nanodevices.

  7. Fabrication of modified lithium orthosilicate pebbles by addition of titania

    Energy Technology Data Exchange (ETDEWEB)

    Knitter, R., E-mail: regina.knitter@kit.edu [Karlsruhe Institute of Technology (KIT), Institute for Applied Materials (IAM-WPT), Karlsruhe, 76021 (Germany); Kolb, M.H.H.; Kaufmann, U. [Karlsruhe Institute of Technology (KIT), Institute for Applied Materials (IAM-WPT), Karlsruhe, 76021 (Germany); Goraieb, A.A. [Goraieb Versuchstechnik (GVT), Karlsruhe, 76227 (Germany)

    2013-11-15

    Highlights: ► Lithium orthosilicate pebbles with additions of titania were fabricated by a modified melt-based process. ► The fabricated pebbles exhibit a very fine-grained microstructure with lithium metatitanate as a secondary phase. ► Due to the addition of titanate, the crush load of the pebbles was significantly increased. ► The closed porosity was found to be slightly increased with increasing titanate content. -- Abstract: Lithium orthosilicate pebbles are one of the ceramic tritium breeder materials destined for the European solid breeder test blanket modules of ITER, the large-scale scientific experiment intended to prove the viability of fusion as an energy source, presently under construction in Cadarache, France. While the current reference material is fabricated by melt-spraying with 2.5 wt.% excess of silica, resulting in a two-phase material of lithium orthosilicate and metasilicate, a modified melt-based process was used to fabricate breeder pebbles with additions of titania in order to obtain pebbles with lithium metatitanate as a secondary phase. The fabricated two-phase pebbles exhibit a fine-grained microstructure and increased crush loads. The optimum titanate content has yet to be evaluated, nonetheless the pebbles may have the potential to combine the advantages of both lithium orthosilicate and metatitanate breeder ceramics.

  8. Characterization of nanocrystalline anatase titania: an in situ HTXRD study

    International Nuclear Information System (INIS)

    Jagtap, Neelam; Bhagwat, Mahesh; Awati, Preeti; Ramaswamy, Veda

    2005-01-01

    Nanocrystalline titania was synthesized by the hydrolysis of titanium iso-propoxide using ultrasonication. The powder XRD patterns of the sample were recorded in static air and vacuum using a Philips X-pert Pro diffractometer equipped with a high-temperature attachment (HTK16) from room temperature (298 K) to 1173 K and were analyzed by the Rietveld refinement technique. The anatase to rutile phase transformation was observed at 1173 K for the data collected in static air. Only 3% of anatase titania transformed to rutile when the experiments were carried out at 1173 K in vacuum. The phase transformation from anatase to rutile is accompanied by a continuous increase in the crystallite size of the anatase phase from 9 nm at room temperature to 28 nm at 873 K and then to 50 nm at 1173 K in air while the process of crystallite growth was suppressed in vacuum. A linear increase in the unit cell parameters 'a' and 'c', and thus, an overall linear increase in the unit cell volume was observed as a function of temperature in static air as well as vacuum. The lattice and volume thermal expansion coefficients (TEC), α a , α c and α V at 873 K are 8.57 x 10 -6 , 8.71 x 10 -6 and 25.91 x 10 -6 K -1 in air and 18.01 x 10 -6 , 14.95 x 10 -6 and 51.13 x 10 -6 K -1 in vacuum, respectively

  9. Hydroxyapatite nucleated and grown on nano titania particles enhances recruitment of Escherichia coli for subsequent photocatalytic elimination

    International Nuclear Information System (INIS)

    Huang, Jing; Liu, Yi; Liu, Yuxin; Li, Hua

    2015-01-01

    Titania-hydroxyapatite (HA) nanocomposites were fabricated by wet chemical synthesis approach. HA exhibited crystallographic orientation of nucleation on nano titania particle, forming the composite particles with titania being partially enwrapped with HA. Microstructural characterization by high resolution transmission electron microscopy revealed coherent interfacial bond of (110) and (222) planes of HA crystal with (101) plane of anatase. The HA layer promoted significantly recruitment of Escherichia coli bacteria onto the titania-based particles for subsequent photocatalytic killing. Less extent of enwrapping of HA on titania particle, as accomplished by increasing the aging time of HA suspension, gave rise to better capability of photocatalytic degradation of methylene blue and sterilization of the bacteria. The novel HA-enwrapped titania powder shows great potential for environmental applications. - Highlights: • Titania-hydroxyapatite nanocomposite powder was fabricated with cladding structure. • Hydroxyapatite nucleated and grew on titania particle with preferred orientation. • Hydroxyapatite layer promotes recruitment of Escherichia coli onto titania-based particles. • The titania-hydroxyapatite particles show excellent antibacterial performances. • The nanocomposite powder exhibits excellent photocatalytic performances

  10. Hydroxyapatite nucleated and grown on nano titania particles enhances recruitment of Escherichia coli for subsequent photocatalytic elimination

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Jing; Liu, Yi; Liu, Yuxin; Li, Hua, E-mail: lihua@nimte.ac.cn

    2015-02-01

    Titania-hydroxyapatite (HA) nanocomposites were fabricated by wet chemical synthesis approach. HA exhibited crystallographic orientation of nucleation on nano titania particle, forming the composite particles with titania being partially enwrapped with HA. Microstructural characterization by high resolution transmission electron microscopy revealed coherent interfacial bond of (110) and (222) planes of HA crystal with (101) plane of anatase. The HA layer promoted significantly recruitment of Escherichia coli bacteria onto the titania-based particles for subsequent photocatalytic killing. Less extent of enwrapping of HA on titania particle, as accomplished by increasing the aging time of HA suspension, gave rise to better capability of photocatalytic degradation of methylene blue and sterilization of the bacteria. The novel HA-enwrapped titania powder shows great potential for environmental applications. - Highlights: • Titania-hydroxyapatite nanocomposite powder was fabricated with cladding structure. • Hydroxyapatite nucleated and grew on titania particle with preferred orientation. • Hydroxyapatite layer promotes recruitment of Escherichia coli onto titania-based particles. • The titania-hydroxyapatite particles show excellent antibacterial performances. • The nanocomposite powder exhibits excellent photocatalytic performances.

  11. Ferrocene-Functionalized Graphene Oxide Nanosheets: Efficient Electronic Communication between Ferrocene Centers across Graphene Nanosheets

    International Nuclear Information System (INIS)

    Lu, Yizhong; Jiang, Yuanyuan; Wu, Haibin; Chen, Wei

    2015-01-01

    Highlights: • Graphene oxide (GO) nanosheets functionalized with ferrocenyl moieties (GO-Fc) are fabricated. • GO-Fc shows efficient electronic communication between ferrocene centers. • GO-Fc exhibits two pairs of voltammetric peaks with a large potential spacing of 0.515 V. • GO-Fc shows a broad absorption peak in the near-infrared range (∼ 1428 nm) at mixed valence. - Abstract: Graphene oxide (GO) nanosheets functionalized with ferrocenyl moieties (GO-Fc) were fabricated through strong covalent C−C bonds. The resulting hybrid showed efficient electronic communication between ferrocene centers due to the strong electron delocalization facilitated by the large pi-pi conjugated structure of graphene sheets. The obtained hybrid exhibited two pairs of voltammetric peaks with a large potential spacing of 0.515 V and a broad absorption peak in the near-infrared range (∼ 1428 nm) at mixed valence. The electrochemical and near IR spectroscopic features suggested a Class II/III behavior of the intervalence charge transfer. This work indicates clearly that strong electronic coupling between ferrocene centers can be easily realized across graphene nanosheets with sp 2 -hybridized carbon

  12. Controlled Interactions between Two Dimensional Layered Inorganic Nanosheets and Polymers

    Science.gov (United States)

    2016-06-15

    AFRL-AFOSR-JP-TR-2016-0071 Controlled Interactions between Two Dimensional Layered Inorganic Nanosheets and Polymers Cheolmin Park YONSEI UNIVERSITY...Interactions between Two Dimensional Layered Inorganic Nanosheets and Polymers 5a.  CONTRACT NUMBER 5b.  GRANT NUMBER FA2386-14-1-4054 5c.  PROGRAM ELEMENT...prospects for a variety of emerging applications in a broad range of fields, such as electronics, energy conversion and storage, catalysis and polymer

  13. Superhydrophilic SnO{sub 2} nanosheet-assembled film

    Energy Technology Data Exchange (ETDEWEB)

    Masuda, Yoshitake, E-mail: masuda-y@aist.go.jp; Kato, Kazumi

    2013-10-01

    SnO{sub 2} films were fabricated on fluorine-doped tin oxide (FTO) substrates in aqueous solutions. The films of about 800 nm in thickness grew in the solutions containing SnF{sub 2} of 25 mM at 90 °C for 24 h. They consisted of nanosheets of about 5–10 nm in thickness and about 100–1600 nm in plane size. The films had gradient structure of nanosheets. Smaller nanosheets formed dense structures in a bottom area, while larger nanosheets formed porous structures in a surface area of the films. The SnO{sub 2} films showed higher transparency than bare FTO substrates in a visible light region of 470 to 850 nm. Decrease of reflectance increased transparency. The SnO{sub 2} films had superhydrophilic surfaces of static contact angle below 1°. Nanosheet-assembled structures contributed high hydrophilicity. The surfaces were further modified with light irradiation. High speed camera observation showed that spread speed of water was improved with the irradiation. Removal of surface adsorbed organic molecules and increase in the number of hydroxyl groups brought superhydrophilicity and high spread speed. - Highlights: ► SnO{sub 2} nanosheet films were prepared from aqueous solutions. ► The antireflective films showed superhydrophilicity. ► Crystal growth mechanism of the gradient structures is discussed.

  14. Rapid synthesis of nitrogen doped titania with mixed crystal lattice via microwave-assisted hydrothermal method

    International Nuclear Information System (INIS)

    Zhang Peilin; Liu Bin; Yin Shu; Wang Yuhua; Petrykin, Valery; Kakihana, Masato; Sato, Tsugio

    2009-01-01

    A microwave-assisted hydrothermal method was employed to synthesize nitrogen doped titania nanoparticles. Due to the high heating efficiency of microwave, rapid synthesis could be achieved in comparison with the conventional oven. Mixed crystal lattice was found existing in the obtained product, and the phase transformation behaviour under calcination was studied by XRD measurement together with Raman spectroscopy in details. The obtained nitrogen doped titania showed high specific surface area, about 300 m 2 g -1 . Photocatalytic activity in destructing NO x gas by the prepared sample exceeded that of commercial titania (P 25) or nitrogen doped titania synthesized by conventional hydrothermal method, under both visible-light and ultraviolet-light irradiation.

  15. Synthesis and characterization of silica–titania core–shell particles

    Indian Academy of Sciences (India)

    reactants (titanium butoxide and water) and the amount of added silica particles. Differ- ... of titania onto silica can enhance its stability and catalytic activity. It is also an .... This work has been supported by DST India under the Nanomaterials,.

  16. Dynamic Diffraction Studies on the Crystallization, Phase Transformation, and Activation Energies in Anodized Titania Nanotubes.

    Science.gov (United States)

    Albetran, Hani; Vega, Victor; Prida, Victor M; Low, It-Meng

    2018-02-23

    The influence of calcination time on the phase transformation and crystallization kinetics of anodized titania nanotube arrays was studied using in-situ isothermal and non-isothermal synchrotron radiation diffraction from room temperature to 900 °C. Anatase first crystallized at 400 °C, while rutile crystallized at 550 °C. Isothermal heating of the anodized titania nanotubes by an increase in the calcination time at 400, 450, 500, 550, 600, and 650 °C resulted in a slight reduction in anatase abundance, but an increase in the abundance of rutile because of an anatase-to-rutile transformation. The Avrami equation was used to model the titania crystallization mechanism and the Arrhenius equation was used to estimate the activation energies of the titania phase transformation. Activation energies of 22 (10) kJ/mol for the titanium-to-anatase transformation, and 207 (17) kJ/mol for the anatase-to-rutile transformation were estimated.

  17. Photocatalytic polymerization induced by a transparent anatase titania aqueous sol and fabrication of polymer composites

    Directory of Open Access Journals (Sweden)

    2010-06-01

    Full Text Available The surface modification of the anatase titania nanoparticles prepared via a controlled nonhydrolytic sol-gel process is achieved by the formation of the bidentate coordination between titania and methacrylic acid (MAA molecules. The in situ photocatalytic polymerization of methyl methacrylate (MMA monomer is initiated by surface modified anatase titania nanoparticles under Xe lamp irradiation. A variety of techniques including differential scanning calorimetry (DSC, thermo-gravimetric analysis (TGA and scanning electron microscopy (SEM are employed to characterize the resulting materials. The glass transition temperatures and the thermal stabilities of polymethyl methacrylate (PMMA composite materials prepared via photocatalytic polymerization are enhanced compared with pure polymer. The partial aggregation of titania nanoparticles in PMMA composite films is derived from the surface polymerization of MMA, which makes the inorganic particles hydrophobic and drives them to the water/oil interfaces.

  18. Macrostructure-dependent photocatalytic property of high-surface-area porous titania films

    Energy Technology Data Exchange (ETDEWEB)

    Kimura, T., E-mail: t-kimura@aist.go.jp [Advanced Manufacturing Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Shimoshidami, Moriyama-ku, Nagoya 463-8560 (Japan)

    2014-11-01

    Porous titania films with different macrostructures were prepared with precise control of condensation degree and density of the oxide frameworks in the presence of spherical aggregates of polystyrene-block-poly(oxyethylene) (PS-b-PEO) diblock copolymer. Following detailed explanation of the formation mechanisms of three (reticular, spherical, and large spherical) macrostructures by the colloidal PS-b-PEO templating, structural variation of the titania frameworks during calcination were investigated by X-ray diffraction and X-ray photoelectron spectroscopy. Then, photocatalytic performance of the macroporous titania films was evaluated through simple degradation experiments of methylene blue under an UV irradiation. Consequently, absolute surface area of the film and crystallinity of the titania frameworks were important for understanding the photocatalytic performance, but the catalytic performance can be improved further by the macrostructural design that controls diffusivity of the targeted molecules inside the film and their accessibility to active sites.

  19. Macrostructure-dependent photocatalytic property of high-surface-area porous titania films

    Directory of Open Access Journals (Sweden)

    T. Kimura

    2014-11-01

    Full Text Available Porous titania films with different macrostructures were prepared with precise control of condensation degree and density of the oxide frameworks in the presence of spherical aggregates of polystyrene-block-poly(oxyethylene (PS-b-PEO diblock copolymer. Following detailed explanation of the formation mechanisms of three (reticular, spherical, and large spherical macrostructures by the colloidal PS-b-PEO templating, structural variation of the titania frameworks during calcination were investigated by X-ray diffraction and X-ray photoelectron spectroscopy. Then, photocatalytic performance of the macroporous titania films was evaluated through simple degradation experiments of methylene blue under an UV irradiation. Consequently, absolute surface area of the film and crystallinity of the titania frameworks were important for understanding the photocatalytic performance, but the catalytic performance can be improved further by the macrostructural design that controls diffusivity of the targeted molecules inside the film and their accessibility to active sites.

  20. Hydrogen gas sensing feature of polyaniline/titania (rutile) nanocomposite at environmental conditions

    Science.gov (United States)

    Milani Moghaddam, Hossain; Nasirian, Shahruz

    2014-10-01

    The resistance-based sensors of polyaniline/titania (rutile) nanocomposite (TPNC) were prepared by spin coating technique onto an epoxy glass substrate with Cu-interdigited electrodes to study their hydrogen (H2) gas sensing features. Our findings are that the change of the surface morphology, porosity and wt% of titania in TPNCs have a significant effect on H2 gas sensing of sensors. All of the sensors had a reproducibility response toward 0.8 vol% H2 gas at room temperature, air pressure and 50% relative humidity. A sensor with 40 wt% of titania nanoparticles had better response/recovery time and the response than other sensors. Moreover, H2 gas sensing mechanism of TPNC sensors based contact areas and the correlation of energy levels between PANI chains and the titania grains were studied.

  1. Sintering and mechanical properties of the alumina–tricalcium phosphate–titania composites

    Energy Technology Data Exchange (ETDEWEB)

    Sakka, Siwar, E-mail: sakka.siwar@yahoo.fr; Bouaziz, Jamel; Ben Ayed, Foued

    2014-07-01

    The objective of this study was to determine the effect of the content of titania and the sintering process on the transformation phase, the densification, the rupture strength and the microstructures of the alumina–10 wt.% tricalcium phosphate composites. After the sintering process, the samples were examined by using {sup 31}P and {sup 27}Al magic angle scanning nuclear magnetic resonance, X-ray powder diffraction and scanning electron microscopy analysis. The Brazilian test was used to measure the rupture strength of the samples. The present results provide new information about solid-state reactivity in the ternary system α-alumina-β-tricalcium phosphate–anatase–titania. The differential thermal analysis of the α-alumina-β-tricalcium phosphate–titania composites shows two endothermic peaks, at 1360 °C and at 1405 °C, which are caused by the reactions between titania/alumina and titania/tricalcium phosphate, respectively. Thus, the presence of titania in the alumina–10 wt.% tricalcium phosphate leads to the formation of β-Al{sub 2}TiO{sub 5} at 1360 °C. At 1600 °C, the alumina–10 wt.% tricalcium phosphate–5 wt.% titania composites displayed the highest rupture strength (74 MPa), compared to the alumina–10 wt.% tricalcium phosphate composites (13.5 MPa). Accordingly, the increase of the rupture strength is due to the formation of the new β-Al{sub 2}TiO{sub 5} phase. - Highlights: • We examine the mechanical properties of bioceramics. • We measure the rupture strength by the Brazilian test. • We characterize the alumina–10 wt.% tricalcium phosphate–titania composites.

  2. Iron on mixed zirconia-titania substrate F-T catalyst

    International Nuclear Information System (INIS)

    Dyer, P.N.; Nordquist, A.F.; Pierantozzi, R.

    1988-01-01

    This patent deals with a Fischer-Tropsch catalyst comprising iron co-deposited with or deposited on particles comprising a mixture of zirconia and titania, preferably formed by co-precipitation of compounds convertible to zirconia and titania, such as zirconium and titanium alkoxide. The invention also comprises the method of making this catalyst and an improved Fischer-Tropsch reaction process in which the catalyst is utilized

  3. Biological performance of titania containing phosphate-based glasses for bone tissue engineering applications

    International Nuclear Information System (INIS)

    Abou Neel, Ensanya Ali; Chrzanowski, Wojciech; Knowles, Jonathan Campbell

    2014-01-01

    The interplay between glass chemistry, structure, degradation kinetics, and biological activity provides flexibility for the development of scaffolds with highly specific cellular response. The aim of this study was therefore to investigate the role of titania inclusion into the phosphate-based glass on its ability to stimulate osteoblast-like human osteosarcoma (HOS) cells to adhere, proliferate and differentiate. In depth morphological and biochemical characterisation was performed on HOS cells cultured on the surface of glass discs. Cell proliferation was also studied in the presence of the glass extract. Cell differentiation, through osteoblast phenotype genes, alkaline phosphatase (ALP) activity and osteocalcin production, was carried out using normal or osteogenic media. Both Thermanox® and titania free glass were used as controls. The data demonstrated that titania inclusion provides desired cytocompatible surface that supported initial cell attachment, sustained viability, and increased cell proliferation similar or significantly higher than Thermanox®. The modified glasses regulated osteoblastic cell differentiation as detected by osteoblast phenotype gene transcription and upregulated ALP and osteocalcin expression. Using osteogenic media had no significant effect on ALP activity and osteocalcin expression. Therefore, titania modified phosphate glasses may have future use as bone tissue engineering scaffolds. - Highlights: • This study investigated the role of titania on the biological response of phosphate glasses. • Incorporation of titania improved HOS cell attachment, viability and proliferation. • Titania modified glasses regulated osteoblastic cell differentiation. • Using osteogenic media had no significant effect on cell differentiation. • Titania modified glasses may have future use as bone tissue engineering scaffolds

  4. Interstratified nanohybrid assembled by alternating cationic layered double hydroxide nanosheets and anionic layered titanate nanosheets with superior photocatalytic activity

    International Nuclear Information System (INIS)

    Lin, Bizhou; Sun, Ping; Zhou, Yi; Jiang, Shaofeng; Gao, Bifen; Chen, Yilin

    2014-01-01

    Graphical abstract: - Highlights: • Two kinds of nanosheets are well arranged in a layer-by-layer alternating fashion. • Effective interfacial heterojunction and high specific surface were observed. • Interstratified nanohybrid exhibits a superior photocatalytic activity. - Abstract: Oppositely charged 2D inorganic nanosheets of ZnAl-layered double hydroxide and layered titanate were successfully assembled into an interstratified nanohybrid through simply mixing the corresponding nanosheet suspensions. Powder X-ray diffraction and high-resolution transmission electron microscope clearly revealed that the component nanosheets in the as-obtained nanohybrid ZnAl–Ti 3 O 7 retain the 2D sheet skeletons of the pristine materials and that the two kinds of nanosheets are well arranged in a layer-by-layer alternating fashion with a basal spacing of about 1.3 nm, coincident with the thickness summation of the two component nanosheets. The effective interfacial heterojunction between them and the high specific surface area resulted in that the nanohybrid exhibits a superior photocatalytic activity in the degradation of methylene blue with a reaction constant k of 2.81 × 10 −2 min −1 , which is about 9 and 4 times higher than its precursors H 2 Ti 3 O 7 and ZnAl-LDH, respectively. Based on UV–vis, XPS and photoelectrochemical measurements, a proposed photoexcitation model was provided to understand its photocatalytic behavior

  5. Chirality of Single-Handed Twisted Titania Tubular Nanoribbons Prepared Through Sol-gel Transcription.

    Science.gov (United States)

    Wang, Sibing; Zhang, Chuanyong; Li, Yi; Li, Baozong; Yang, Yonggang

    2015-08-01

    Single-handed twisted titania tubular nanoribbons were prepared through sol-gel transcription using a pair of enantiomers. Handedness was controlled by that of the template. The obtained samples were characterized using field-emission electron microscopy, transmission electron microscopy, diffuse reflectance circular dichroism (DRCD), and X-ray diffraction. The DRCD spectra indicated that the titania nanotubes exhibit optical activity. Although the tubular structure was destroyed after being calcined at 700 °C for 2.0 h, DRCD signals were still identified. However, the DRCD signals disappeared after being calcined at 1000 °C for 2.0 h. The optical activity of titania was proposed to be due to chiral defects. Previous results showed that straight titania tubes could be used as asymmetric autocatalysts, indicating that titania exhibit chirality at the angstrom level. Herein, it was found that they also exhibit DRCD signals, indicating that there are no obvious relationships between morphology at the nano level and chirality at the angstrom level. The nanotube chirality should originate from the chiral defects on the nanotube inner surface. The Fourier transform infrared spectra indicated that the chirality of the titania was transferred from the gelators through the hydrogen bonding between N-H and Ti-OH. © 2015 Wiley Periodicals, Inc.

  6. Solventless acid-free synthesis of mesostructured titania: Nanovessels for metal complexes and metal nanoclusters

    Energy Technology Data Exchange (ETDEWEB)

    Dag, Oe.; Celik, Oe.; Ozin, G.A. [Department of Chemistry, Bilkent University, 06533 Ankara (Turkey); Soten, I.; Polarz, S.; Coombs, N. [Materials Chemistry Research Group, Chemistry Department, University of Toronto, 80 St. George Street, Toronto, Ontario M5S 3H6 (Canada)

    2003-01-01

    A new and highly reproducible method to obtain mesostructured titania materials is introduced in this contribution. The mesostructured titania is obtained by employing self-assembled structures of non-ionic alkyl-poly(ethylene oxide) surfactants as templates. The materials are produced without additional solvents such as alcohols, or even water. Only the titanium(IV) ethoxide and the surfactant (C{sub 12}EO{sub 10}) are needed. Water, in the form of that attached to the surfactant and from the atmosphere, induces growth of titania nanoclusters in the synthesis sol. It is indicated that these nanoclusters interact with the surfactant EO-head groups to form a new titanotropic amphiphile. The new amphiphiles self-assemble into titanium nanocluster-surfactant hybrid lyotropic phases, which are transformed to the final mesostructured materials by further condensation of the titania network. The titania materials can be obtained also with noble-metal particles immobilized in the mesostructured framework. It is seen that when different metal salts are used as the metal precursors, different interactions with the titania walls are found. The materials are characterized by X-ray diffraction (XRD), polarization optical microscopy (POM), transmission electron microscopy (TEM), UV-vis spectroscopy, and micro-Raman analysis. (Abstract Copyright [2003], Wiley Periodicals, Inc.)

  7. Preparation and bioactivity evaluation of hydroxyapatite-titania/chitosan-gelatin polymeric biocomposites

    International Nuclear Information System (INIS)

    Mohamed, Khaled R.; Mostafa, Amani A.

    2008-01-01

    Biocomposites consisting of hydroxyapatite (HA) and natural polymers such as collagen, chitosan, chitin,and gelatin have been extensively investigated. However, studies on the combination of HA and titania with chitosan and gelatin have not been conducted yet. Novel biodegradable hydroxyapatite-titania/chitosan-gelatin polymeric composites were fabricated. In this work, our results are concerning with the preparation and characterization of HA powder and HA filler containing titania powder (10 and 30%) with a chitosan and gelatin copolymer matrix. The present research focuses on characterizing the structure of this novel class of biocomposites. Thermogravimetric analysis (TGA), X-ray diffraction (XRD), and Fourier Transformed Infrared Spectroscopy (FT-IR), Scanning electron microscopy (SEM-EDAX) were employed to assess the produced composites. The mechanical properties in terms of compressive strength and hardness test were also investigated. The in vitro study in simulated body fluid (SBF) was performed to assess the bioactivity of composites. The results proved that apatite resembling natural bone are formed faster and greater in the case the composite of HA containing 10% titania into chitosan-gelatin polymeric matrix when they are soaked in a simulated body fluid (SBF) than the composite containing 30% titania. The biocomposites containing HA with 10% titania are expected to be attractive for bioapplications as bone substitutes and scaffolds for tissue engineering in future

  8. Molecularly imprinted titania nanoparticles for selective recognition and assay of uric acid

    Science.gov (United States)

    Mujahid, Adnan; Khan, Aimen Idrees; Afzal, Adeel; Hussain, Tajamal; Raza, Muhammad Hamid; Shah, Asma Tufail; uz Zaman, Waheed

    2015-06-01

    Molecularly imprinted titania nanoparticles are su ccessfully synthesized by sol-gel method for the selective recognition of uric acid. Atomic force microscopy is used to study the morphology of uric acid imprinted titania nanoparticles with diameter in the range of 100-150 nm. Scanning electron microscopy images of thick titania layer indicate the formation of fine network of titania nanoparticles with uniform distribution. Molecular imprinting of uric acid as well as its subsequent washing is confirmed by Fourier transformation infrared spectroscopy measurements. Uric acid rebinding studies reveal the recognition capability of imprinted particles in the range of 0.01-0.095 mmol, which is applicable in monitoring normal to elevated levels of uric acid in human blood. The optical shift (signal) of imprinted particles is six times higher in comparison with non-imprinted particles for the same concentration of uric acid. Imprinted titania particles have shown substantially reduced binding affinity toward interfering and structurally related substances, e.g. ascorbic acid and guanine. These results suggest the possible application of titania nanoparticles in uric acid recognition and quantification in blood serum.

  9. Hydrogen gas sensing feature of polyaniline/titania (rutile) nanocomposite at environmental conditions

    Energy Technology Data Exchange (ETDEWEB)

    Milani Moghaddam, Hossain, E-mail: hossainmilani@yahoo.com [Solid State Physics Department, University of Mazandaran, Babolsar (Iran, Islamic Republic of); Nasirian, Shahruz [Solid State Physics Department, University of Mazandaran, Babolsar (Iran, Islamic Republic of); Basic Sciences Department, Mazandaran University of Science and Technology, Babol (Iran, Islamic Republic of)

    2014-10-30

    Graphical abstract: - Highlights: • Polyaniline/titania (rutile) nanocomposite (TPNC) was synthesized by a chemical oxidative polymerization method. • Surface morphology and titania (rutile) wt% in TPNC sensors were significant factors for H{sub 2} gas sensing. • TPNC sensors could be used for H{sub 2} gas sensing at different R.H. humidity. • TPNC Sensors exhibited considerable sensitive, reversible and repeatable response to H{sub 2} gas at environmental conditions. - Abstract: The resistance-based sensors of polyaniline/titania (rutile) nanocomposite (TPNC) were prepared by spin coating technique onto an epoxy glass substrate with Cu-interdigited electrodes to study their hydrogen (H{sub 2}) gas sensing features. Our findings are that the change of the surface morphology, porosity and wt% of titania in TPNCs have a significant effect on H{sub 2} gas sensing of sensors. All of the sensors had a reproducibility response toward 0.8 vol% H{sub 2} gas at room temperature, air pressure and 50% relative humidity. A sensor with 40 wt% of titania nanoparticles had better response/recovery time and the response than other sensors. Moreover, H{sub 2} gas sensing mechanism of TPNC sensors based contact areas and the correlation of energy levels between PANI chains and the titania grains were studied.

  10. Thermally modified titania photocatalysts for phenol removal from water

    Directory of Open Access Journals (Sweden)

    Joanna Grzechulska-Damszel

    2006-01-01

    Full Text Available Two kinds of titanium dioxide were used as starting materials for thermal modification: Tytanpol A11 supplied by Chemical Factory “Police” S.A. (Poland and Degussa P25 supplied by Degussa AG (Germany. The photocatalytic activity of titania materials modified by thermal treatment was tested in the reaction of photocatalytic oxidation of phenol. It was found that the highest activity in the reaction of photocatalytic decomposition of phenol, in case of Tytanpol A11, shows the samples of material modified at temperatures of 700 and 750°C. These catalysts were more active than untreated A11, whereas materials modified at higher temperatures show lower activity. In the case of P25, all thermally treated materials were less active than the unmodified material. The photocatalyst samples were characterized by UV-Vis/DR, FTIR/DRS, and XRD methods.

  11. Sensitization of Xanthophylls-Chlorophyllin Mixtures on Titania Solar Cells

    Directory of Open Access Journals (Sweden)

    Indriana Kartini

    2015-03-01

    Full Text Available Co-sensitization of natural dyes on TiO2 for dye-sensitized solar cell (DSSC was proposed between chlorophyllin (C and xanthophylls (X at various volume ratios of C/X. Chlorophyllin is chlorophyll derivative providing -COOH groups essential for binding to TiO2. The chlorophyll was extracted from dried spinach (amaranthus viridis leaves in a mixture of methanol-acetone (70%:30%. Chlorophyll extract dye was obtained after partition of the crude extracts in diethyl ether solution. Then, it was hydrolyzed under alkaline condition to get chlorophyllin. Xanthophyll was extracted from fresh petal of chrysanthemum (chrysanthemum indicum flowers. Blending of chlorophyllin and xanthophyll was carried out at various volume ratios of C to X (1:0, 5:1, 1:1, 1:5, 0:1. Titania solar cells were constructed in sandwich system of conducting glass-titania/dyes as the photoanode and conducting glass-platinum as the photocathode. Electrolyte solution containing I-/I3- was inserted between the electrodes by capillary action. All dye extracts and blending solutions were analyzed by UV-Vis spectrophotometer. It is shown that the absorption spectra of blending dyes are complimentary in the visible region resulted in a panchromatic response of the dyes. From the cyclic voltammogram of the dyes and blended-dyes, it is found that the energy level of xanthophyll is the lowest. The I-V test at 100 mw/cm2 irradiation confirmed that the energy conversion efficiency (h of the blended dyes of xanthophyll and chlorophyllin-sensitized solar cell resulted in significant improvement than those of the single dye. Beneficially, the mixed dyes can be adsorbed from solution blend using single dipping step.

  12. Hierarchical nanoflowers assembled with Au nanoparticles decorated ZnO nanosheets toward enhanced photocatalytic properties

    DEFF Research Database (Denmark)

    Yu, Cuiyan; Yu, Yanlong; Xu, Tao

    2017-01-01

    Hierarchical nanoflowers assembled with Au nanoparticles (NPs) decorated ZnO nanosheets (Au-ZnO nanosheet flowers, AZNSFs) were successful synthesized. The AZNSFs showed more efficient activity to photodegradation of RhB than that of pure ZnO nanosheet flowers and commercial ZnO nanopowders. The ...

  13. Preparation of nitrogen-doped titania using sol-gel technique and its photocatalytic activity

    International Nuclear Information System (INIS)

    Qin Haoli; Gu Guobang; Liu Song

    2008-01-01

    Yellowish nitrogen-doped titania was produced through sol-gel method at room temperature, with the elemental nitrogen derived from aqua ammonia. The titania catalysts were characterized using TG-DSC, XRD, BET, TEM, and UV-vis diffuse reflectance spectrophotometer. Methyl orange (MO) and 2-mercaptobenzothiazole (MBT) were used in this study as model chemicals and both the adsorption isotherm and photocatalytic activity of the nitrogen-doped titania catalysts were evaluated based on the MO and MBT photodegradation in aqueous solution under UV and visible light, respectively. The results showed that all titania catalysts were anatase. The crystallite size of nitrogen-doped ones increased with the increase of N/Ti proportion, both the adsorption capacity and adsorption equilibrium constants of the nitrogen-doped titania catalysts were improved by the doping of nitrogen. The doping of nitrogen could extend the absorption shoulder into the visible-light region, thus nitrogen-doped titania possessed visible-light activity illustrated by that higher capability of degradation of MO and MBT under the irradiation of visible light, whereas the pure ones showed little such kind of visible-light activity. The kinetics of the MO and MBT photodegradation using different nitrogen-doped titania were also studied, the experiments demonstrated that there was an optimum N/Ti proportion of 4 mol% to exhibit the highest visible-light activity. The UV activity of nitrogen-doped titania catalysts were worse than that of the pure one and Degussa P-25. In addition, nitrogen-doped titania had weakened appreciably activity in the visible-light region as the N/Ti proportion increased, while a reverse relationship exists for the UV light. It was concluded that the enhancement of MO and MBT photodegradation using the nitrogen-doped titania catalysts mainly involved in both the improvement of the organic substrate adsorption in catalysts suspension and the enhancement of the separation of electron

  14. Soluble, Exfoliated Two-Dimensional Nanosheets as Excellent Aqueous Lubricants.

    Science.gov (United States)

    Zhang, Wenling; Cao, Yanlin; Tian, Pengyi; Guo, Fei; Tian, Yu; Zheng, Wen; Ji, Xuqiang; Liu, Jingquan

    2016-11-30

    Dispersion in water of two-dimensional (2D) nanosheets is conducive to their practical applications in fundamental science communities due to their abundance, low cost, and ecofriendliness. However, it is difficult to achieve stable aqueous 2D material suspensions because of the intrinsic hydrophobic properties of the layered materials. Here, we report an effective and economic way of producing various 2D nanosheets (h-BN, MoS 2 , MoSe 2 , WS 2 , and graphene) as aqueous dispersions using carbon quantum dots (CQDs) as exfoliation agents and stabilizers. The dispersion was prepared through a liquid phase exfoliation. The as-synthesized stable 2D nanosheets based dispersions were characterized by UV-vis, HRTEM, AFM, Raman, XPS, and XRD. The solutions based on CQD decorated 2D nanosheets were utilized as aqueous lubricants, which realized a friction coefficient as low as 0.02 and even achieved a superlubricity under certain working conditions. The excellent lubricating properties were attributed to the synergetic effects of the 2D nanosheets and CQDs, such as good dispersion stability and easy-sliding interlayer structure. This work thus proposes a novel strategy for the design and preparation of high-performance water based green lubricants.

  15. NiO nanosheet assembles for supercapacitor electrode materials

    Directory of Open Access Journals (Sweden)

    Huanhao Xiao

    2016-06-01

    Full Text Available In this paper, large scale hierarchically assembled NiO nanosheets have been favorably fabricated through a facile hydrothermal route. The as-prepared NiO nanosheet assembles were characterized in detail by various analytical techniques. The results showed these nanosheets present the thickness of about 30 nm and the surface area is 116.9 m2 g−1. These NiO nanosheet assembles were used as the working electrode materials in electrochemical tests, which demonstrated a specific capacitance value of 81.67 F g−1 at the current density of 0.5 A g−1 and excellent long cycle-life stability with 78.5% of its discharge specific capacitance retention after 3000 cycles at the current density of 0.5 A g−1, revealing the as-synthesized NiO nanosheet assembles might be a promising electrode material for supercapacitor applications.

  16. Silver decorated titanate/titania nanostructures for efficient solar driven photocatalysis

    International Nuclear Information System (INIS)

    Gong, Dangguo; Ho, Weng Chye Jeffrey; Tang Yuxin; Tay Qiuling; Lai Yuekun; Highfield, James George; Chen Zhong

    2012-01-01

    Photocatalysis has attracted significant interest to solve both the energy crisis and effectively combat environmental contamination. However, as the most widely used photocatalyst, titania (TiO 2 ) suffers from inefficient utilization of solar energy due to its wide band gap. In the present paper, we describe a method to extend the absorption edge of photocatalyst to visible region by the surface plasmon effect of silver. Silver ions are photo-reduced onto the surface of titanate nanotubes, which are synthesized by a conventional hydrothermal method. The as-synthesized Ag/titanate composite is transformed into Ag/titania nanoparticles by annealing at different temperatures. It is found that the interaction of Ag nanoparticles with the supports (titanate/titania) plays a key role for the visible light activity. The samples annealed at low temperature (<350 °C) do not show significant activity under our conditions, while the one annealed at 450 °C shows fast-degradation of methyl orange (MO) under visible light irradiation. The detailed mechanisms are also discussed. - Graphical abstract: Silver nanoparticles decorated titanate/titania as visible light active photocatalysts: silver nanoparticles could be excited by visible light due to its surface plasmon effect and excited electrons could be transferred to the conduction band of the semiconductor, where the reduction process occurs. Highlights: ► Uniform Ag nanoparticles are photo-reduced onto titanate and titania nanostructures. ► Titania crystal is formed by annealing hydrogen titanate at different temperatures. ► Best visible-light activity is achieved by Ag-loaded titania annealed at 450 °C. ► The visible light activity is attributed to the surface plasmonic resonance effect.

  17. High-Quality ZnCdS Nanosheets Prepared Using Solvothermal Synthesis

    International Nuclear Information System (INIS)

    Mahdi, M.A.; Hassan, J.J.; Ng, S.S.; Hassan, Z.

    2013-01-01

    For the first time, Zn X Cd 1-X S nanosheets with different Zn and Cd ion concentrations were prepared using solvothermal synthesis at 200 degree C for 4 and 24 h. The crystalline structure of the nanosheets was wurtzite. The optical band gaps of the nanosheets increased with increasing Zn ratio; this increase is consistent with the band gaps estimated using Vegard’s formula. The photoluminescence spectra for the 24 h nanosheets had higher emission intensities than those for the 4 h nanosheets. The emission band corresponding to intrinsic near-band-edge emission and a broad peak associated with extrinsic deep-level emission were observed in the photoluminescence spectra.

  18. In situ iron-57 Moessbauer spectroscopic investigations of the effect of titania surface area on the reducibility of titania-supported iron oxide

    International Nuclear Information System (INIS)

    Berry, F.J.; Du Hongzhang

    1990-01-01

    Iron-57 Moessbauer spectroscopy has been used to monitor the reducibility in hydrogen of iron oxides supported on titania of differing surface areas. The results show that although Fe 3+ in the iron oxide supported on low surface area titania (11 m 2 g -1 ) is not amenable to facile reduction at low temperatures, complete reduction to metallic iron is achieved by treatment at 600deg C. The data also show that the extent of reduction at elevated temperatures exceeds that which is obtained on similar silica- and alumina-supported systems. Fe 3+ in iron oxide supported on higher surface area titania (50 m 2 g -1 and 240 m 2 g -1 ) is partially reduced in hydrogen at 235deg C to Fe 2+ but fails to attain complete reduction to the metallic state following treatment at 600deg C. The results are related to the different dispersions of iron oxide which can be attained on titania of differing surface area and the consequent interactions between the support and the supported phases. (orig.)

  19. Modified Unzipping Technique to Prepare Graphene Nano-Sheets

    Science.gov (United States)

    Al-Tamimi, B. H.; Farid, S. B. H.; Chyad, F. A.

    2018-05-01

    Graphene nano-sheets have been prepared via unzipping approach of multiwall carbon nanotubes (MWCNTs). The method includes two chemical-steps, in which a multi-parameter oxidation step is performed to achieve unzipping the carbon nanotubes. Then, a reduction step is carried out to achieve the final graphene nano-sheets. In the oxidation step, the oxidant material was minimized and balanced with longer curing time. This modification is made in order to reduce the oxygen-functional groups at the ends of graphene basal planes, which reduce its electrical conductivity. In addition, a similar adjustment is achieved in the reduction step, i.e. the consumed chemicals is reduced which make the overall process more economic and eco-friendly. The prepared nano-sheets were characterized by atomic force microscopy, scanning electron microscopy, and Raman spectroscopy. The average thickness of the prepared graphene was about 5.23 nm.

  20. Structural and optical properties of CdSe nanosheets

    Science.gov (United States)

    Solanki, Rekha Garg; Rajaram, P.; Arora, Aman

    2018-04-01

    Nanosheets of CdSe have been synthesized using a solvothermal route using citric acid as an additive. It is found that the citric acid effectively controls the structural and optical properties of CdSe nanostructures. XRD studies confirm the formation of hexagonal wurtzite phase of CdSe. The FESEM micrographs show that the obtained CdSe nanocrystals are in the form of very thin sheets (nanosheets). Optical absorption studies as well as Photoluminescence spectra show that the optical gap is around 1.76 eV which is close to the reported bulk value of 1.74 eV. The prepared CdSe nanosheets because of large surface area may be useful for catalytic activities in medicine, biotechnology and environmental chemistry and in biomedical imaging for in vitro detection of a breast cancer cells.

  1. Direct Synthesis of 7 nm Thick Zinc(II)-Benzimidazole-Acetate Metal-Organic Framework Nanosheets

    Energy Technology Data Exchange (ETDEWEB)

    Xue, Feng; Kumar, Prashant; Xu, Wenqian; Mkhoyan, K. Andre; Tsapatsis, Michael

    2018-01-09

    Two-dimensional metal-organic frameworks (MOFs) are promising candidates for high performance gas sepa-ration membranes. Currently, MOF nanosheets are mostly fabricated through delamination of layered MOFs, which often re-sults in a low yield of intact free-standing nanosheets. In this work, we present a direct synthesis method for zinc(II)-benzimidazole-acetate (Zn(Bim)OAc) MOF nanosheets. The obtained nanosheets have a lateral dimension of 600 nm when synthesized at room temperature. By adjusting the synthesis temperature, the morphology of obtained nanosheets can be readily tuned from nanosheets to nanobelts. A thickness of 7 nm is determined for Zn(Bim)OAc using high-angle annular dark-field scanning transmission electron microscopy, which makes these nanosheets promising building blocks of gas sepa-ration membranes.

  2. Correlation between lateral size and gas sensing performance of MoSe2 nanosheets

    Science.gov (United States)

    Zhang, Shaolin; Nguyen, Thuy Hang; Zhang, Weibin; Park, Youngsin; Yang, Woochul

    2017-10-01

    We demonstrate a facile synthetic method to prepare lateral size controlled molybdenum diselenide (MoSe2) nanosheets using liquid phase exfoliated few-layer MoSe2 nanosheets as a starting material. By precisely controlling the centrifugation condition, preparation of MoSe2 nanosheets with a narrow size distribution ranging from several hundred nanometers to several micrometers could be realized. The accurate size control of MoSe2 nanosheets offers us a great opportunity to examine the size dependent sensing properties. The sensing test results demonstrate that the MoSe2 nanosheets provide competitive advantages compared with conventional graphene based sensors. A tradeoff phenomenon on sensing response and recovery as the lateral size of MoSe2 nanosheets varies is observed. First principles calculations reveal that the ratio of edge-surface sites is responsible for this phenomenon. The correlation between the lateral size and gas sensing performance of MoSe2 nanosheets is established.

  3. Synthesis of Titania-supported Copper Nanoparticles via Refined Alkoxide Sol-gel Process

    International Nuclear Information System (INIS)

    Wu, Jeffrey C.S.; Tseng, I.-Hsiang; Chang, W.-C.

    2001-01-01

    Nanoparticles of titania and copper-loaded titania were synthesized by a refined sol-gel method using titanium butoxide. Unlike the conventional sol-gel procedure of adding water directly, the esterification of anhydrous butanol and glacial acetic acid provided the hydrolyzing water. In addition, acetic acid also served as a chelating ligand to stabilize the hydrolysis-condensation process and minimize the agglomeration of titania. Following the hydrolysis, Cu/TiO 2 was prepared by adding copper chloride to titania sol. The sol was dried, then calcined at 500 deg. C to remove organics and transformed to anatase titania which was verified by XRD. Cu/TiO 2 was further hydrogen-reduced at 300 deg. C. The recovery of Ti was exceeded by an average of 95% from titanium butoxide. TEM micrographs show that the Cu/TiO 2 particles are near uniform. The average crystallite sizes are 17-20 nm estimated from the peak broadening of XRD spectra. The bandgaps of TiO 2 and reduced Cu/TiO 2 range from 2.70 to 3.15 eV estimated from the diffusive reflective UV-Vis spectra. XPS analysis shows that Cu 2p 3/2 is 933.4 eV indicating primary Cu 2 O form on the TiO 2 supports. The binding energy of Ti does not exhibit chemical shift suggesting negligible interaction of Cu cluster and TiO 2 support

  4. Synthesis of Titania-supported Copper Nanoparticles via Refined Alkoxide Sol-gel Process

    Science.gov (United States)

    Wu, Jeffrey C. S.; Tseng, I.-Hsiang; Chang, Wan-Chen

    2001-06-01

    Nanoparticles of titania and copper-loaded titania were synthesized by a refined sol-gel method using titanium butoxide. Unlike the conventional sol-gel procedure of adding water directly, the esterification of anhydrous butanol and glacial acetic acid provided the hydrolyzing water. In addition, acetic acid also served as a chelating ligand to stabilize the hydrolysis-condensation process and minimize the agglomeration of titania. Following the hydrolysis, Cu/TiO2 was prepared by adding copper chloride to titania sol. The sol was dried, then calcined at 500°C to remove organics and transformed to anatase titania which was verified by XRD. Cu/TiO2 was further hydrogen-reduced at 300°C. The recovery of Ti was exceeded by an average of 95% from titanium butoxide. TEM micrographs show that the Cu/TiO2 particles are near uniform. The average crystallite sizes are 17-20 nm estimated from the peak broadening of XRD spectra. The bandgaps of TiO2 and reduced Cu/TiO2 range from 2.70 to 3.15 eV estimated from the diffusive reflective UV-Vis spectra. XPS analysis shows that Cu 2p3/2 is 933.4 eV indicating primary Cu2O form on the TiO2 supports. The binding energy of Ti does not exhibit chemical shift suggesting negligible interaction of Cu cluster and TiO2 support.

  5. High-density arrays of titania nanoparticles using monolayer micellar films of diblock copolymers as templates.

    Science.gov (United States)

    Li, Xue; Lau, King Hang Aaron; Kim, Dong Ha; Knoll, Wolfgang

    2005-05-24

    Highly dense arrays of titania nanoparticles were fabricated using surface micellar films of poly(styrene-block-2-vinylpyridine) diblock copolymers (PS-b-P2VP) as reaction scaffolds. Titania could be introduced selectively within P2VP nanodomains in PS-b-P2VP films through the binary reaction between water molecules trapped in the P2VP domains and the TiCl(4) vapor precursors. Subsequent UV exposure or oxygen plasma treatment removed the organic matrix, leading to titania nanoparticle arrays on the substrate surface. The diameter of the titania domains and the interparticle distance were defined by the lateral scale present in the microphase-separated morphology of the initial PS-b-P2VP films. The typical diameter of titania nanoparticles obtained by oxygen plasma treatment was of the order of approximately 23 nm. Photoluminescence (PL) properties were investigated for films before and after plasma treatment. Both samples showed PL properties with major physical origin due to self-trapped excitons, indicating that the local environment of the titanium atoms is similar.

  6. Reduced Titania Films with Ordered Nanopores and Their Application to Visible Light Water Splitting

    International Nuclear Information System (INIS)

    Shahid, Muhammad; Choi, Seoyeong; Liu, Jingling; Kwon, Younguk

    2013-01-01

    We report on the photoelectrochemical properties of partially reduced mesoporous titania thin films. The fabrication is achieved by synthesizing mesoporous titania thin films through the self-assembly of a titania precursor and a block copolymer, followed by aging and calcination, and heat-treatment under a H 2 (1 torr) environment. Depending on the temperature used for the reaction with H2, the degree of the reduction (generation of oxygen vacancies) of the titania is controlled. The oxygen vacancies induce visible light absorption, and decrease of resistance while the mesoporosity is practically unaltered. The photoelectrochemical activity data on these films, by measuring their photocurrent-potential behavior in 1 M NaOH electrolyte under AM 1.5G 100 mW cm -2 illumination, show that the three effects of the oxygen vacancies contribute to the enhancement of the photoelectrochemical properties of the mesoporous titania thin films. The results show that these oxygen deficient TiO 2 mesoporous thin films hold great promise for a solar hydrogen generation. Suggestions for the materials design for improved photoelectrochemical properties are made

  7. Synthesis and characterization of noble metal–titania core–shell nanostructures with tunable shell thickness

    Directory of Open Access Journals (Sweden)

    Bartosz Bartosewicz

    2017-10-01

    Full Text Available Core–shell nanostructures have found applications in many fields, including surface enhanced spectroscopy, catalysis and solar cells. Titania-coated noble metal nanoparticles, which combine the surface plasmon resonance properties of the core and the photoactivity of the shell, have great potential for these applications. However, the controllable synthesis of such nanostructures remains a challenge due to the high reactivity of titania precursors. Hence, a simple titania coating method that would allow better control over the shell formation is desired. A sol–gel based titania coating method, which allows control over the shell thickness, was developed and applied to the synthesis of Ag@TiO2 and Au@TiO2 with various shell thicknesses. The morphology of the synthesized structures was investigated using scanning electron microscopy (SEM. Their sizes and shell thicknesses were determined using tunable resistive pulse sensing (TRPS technique. The optical properties of the synthesized structures were characterized using UV–vis spectroscopy. Ag@TiO2 and Au@TiO2 structures with shell thickness in the range of ≈40–70 nm and 90 nm, for the Ag and Au nanostructures respectively, were prepared using a method we developed and adapted, consisting of a change in the titania precursor concentration. The synthesized nanostructures exhibited significant absorption in the UV–vis range. The TRPS technique was shown to be a very useful tool for the characterization of metal–metal oxide core–shell nanostructures.

  8. Plasma sprayed rutile titania-nanosilver antibacterial coatings

    Energy Technology Data Exchange (ETDEWEB)

    Gao, Jinjin [Key Lab of Inorganic Coating Materials, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050 (China); Zhao, Chengjian [National Key Laboratory of Human Factors Engineering, Department of ECLSS, China Astronaut Researching and Training Center, Beijing, 100094 (China); Zhou, Jingfang [Ian Wark Research Institute, University of South Australia, Mawson Lakes Campus, Mawson Lakes, SA, 5095 (Australia); Li, Chunxia [National Key Laboratory of Human Factors Engineering, Department of ECLSS, China Astronaut Researching and Training Center, Beijing, 100094 (China); Shao, Yiran; Shi, Chao [Key Lab of Inorganic Coating Materials, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050 (China); Zhu, Yingchun, E-mail: yzhu@mail.sic.ac.cn [Key Lab of Inorganic Coating Materials, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050 (China)

    2015-11-15

    Graphical abstract: - Highlights: • TiO{sub 2}/Ag feedstock powders containing 1–10,000 ppm silver nanoparticles were double sintered and deposited by plasma spray. • TiO{sub 2}/Ag coatings were composed of pure rutile phase and homogeneously-distributed metallic silver. • TiO{sub 2}/Ag coatings with more than 10 ppm silver nanoparticles exhibited strong antibacterial activity against E. coli and S. aureus. - Abstract: Rutile titania (TiO{sub 2}) coatings have superior mechanical properties and excellent stability that make them preferential candidates for various applications. In order to prevent infection arising from bacteria, significant efforts have been focused on antibacterial TiO{sub 2} coatings. In the study, titania-nanosilver (TiO{sub 2}/Ag) coatings with five different kinds of weight percentages of silver nanoparticles (AgNPs) were prepared by plasma spray. The feedstock powders, which had a composition of rutile TiO{sub 2} powders containing 1–10,000 ppm AgNPs, were double sintered and deposited on stainless steel substrates with optimized spraying parameters. X-Ray diffraction and scanning electron microscopy were used to analysize the phase composition and surface morphology of TiO{sub 2}/Ag powders and coatings. Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) were employed to examine the antibacterial activity of the as-prepared coatings by bacterial counting method. The results showed that silver existed homogeneously in the TiO{sub 2}/Ag coatings and no crystalline changed happened in the TiO{sub 2} structure. The reduction ratios on the TiO{sub 2}/Ag coatings with 10 ppm AgNPs were as high as 94.8% and 95.6% for E. coli and S. aureus, respectively, and the TiO{sub 2}/Ag coatings with 100–1000 ppm AgNPs exhibited 100% bactericidal activity against E. coli and S. aureus, which indicated the TiO{sub 2}/Ag coatings with more than 10 ppm AgNPs had strong antibacterial activity. Moreover, the main factors influencing the

  9. Plasma sprayed rutile titania-nanosilver antibacterial coatings

    International Nuclear Information System (INIS)

    Gao, Jinjin; Zhao, Chengjian; Zhou, Jingfang; Li, Chunxia; Shao, Yiran; Shi, Chao; Zhu, Yingchun

    2015-01-01

    Graphical abstract: - Highlights: • TiO_2/Ag feedstock powders containing 1–10,000 ppm silver nanoparticles were double sintered and deposited by plasma spray. • TiO_2/Ag coatings were composed of pure rutile phase and homogeneously-distributed metallic silver. • TiO_2/Ag coatings with more than 10 ppm silver nanoparticles exhibited strong antibacterial activity against E. coli and S. aureus. - Abstract: Rutile titania (TiO_2) coatings have superior mechanical properties and excellent stability that make them preferential candidates for various applications. In order to prevent infection arising from bacteria, significant efforts have been focused on antibacterial TiO_2 coatings. In the study, titania-nanosilver (TiO_2/Ag) coatings with five different kinds of weight percentages of silver nanoparticles (AgNPs) were prepared by plasma spray. The feedstock powders, which had a composition of rutile TiO_2 powders containing 1–10,000 ppm AgNPs, were double sintered and deposited on stainless steel substrates with optimized spraying parameters. X-Ray diffraction and scanning electron microscopy were used to analysize the phase composition and surface morphology of TiO_2/Ag powders and coatings. Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) were employed to examine the antibacterial activity of the as-prepared coatings by bacterial counting method. The results showed that silver existed homogeneously in the TiO_2/Ag coatings and no crystalline changed happened in the TiO_2 structure. The reduction ratios on the TiO_2/Ag coatings with 10 ppm AgNPs were as high as 94.8% and 95.6% for E. coli and S. aureus, respectively, and the TiO_2/Ag coatings with 100–1000 ppm AgNPs exhibited 100% bactericidal activity against E. coli and S. aureus, which indicated the TiO_2/Ag coatings with more than 10 ppm AgNPs had strong antibacterial activity. Moreover, the main factors influencing the antibacterial properties of TiO_2/Ag coatings were discussed with

  10. Band gap evaluations of metal-inserted titania nanomaterials

    International Nuclear Information System (INIS)

    Bashir, Sajid; Liu, Jingbo; Zhang Hui; Sun Xuhui; Guo Jinghua

    2013-01-01

    The electronic and crystalline properties of iron-inserted titania (Fe x Ti 1−x O 2 ) nanoparticles were measured using synchrotron-based soft X-ray spectroscopy and high-temperature X-ray powder diffraction (HT-XRD). The data from X-ray absorption and emission spectroscopy were used to examine occupied and unoccupied densities of states for O 2p and Ti/Fe 3d hybrid orbital characteristics. It was found that Fe 3+ insertion resulted in an up-shift of the band gap from 3.20 to 3.46 eV. This observation reflected site occupancy in the TiO 2 lattice by Fe dopant ions. From HT-XRD Rietveld analysis, Ti occupancy was found to be 0.92 and oxygen 1.00. In addition, the crystal structure remained anatase within a temperature range of 25–800 °C, while the lattice distortion increased due to thermal expansion.

  11. Hydrothermal growth of titania nanowires for SAW device sensing area

    Directory of Open Access Journals (Sweden)

    Zakaria Mohd Rosydi

    2017-01-01

    Full Text Available Synthesis of titania or titanium dioxide (TiO2 is attracted to energy and environmental applications. Here, the growth of nanostructure TiO2 nanowires on Si (100 substrates by using the two-step method. Different seed layers of TiO2 were deposited by spin coating and annealing, followed by the growth of TiO2 nanowires by using the hydrothermal method. The sol-gel technique was used in preparing the TiO2 solution for the thin film deposition purpose. Acetic acid, hydrochloric acid and tris (2-aminoethyl amine were used as a stabilizer to synthesize three different TiO2 seed layers. The aim of this study was to understand the role of polycrystalline size on thin film towards the diameter of nanowires grown as a sensing area in Surface Acoustic Wave (SAW Biosensor. The morphology and structure of the thin film and TiO2 nanowires were characterized using X-Ray diffraction (XRD, scanning electron microscope (SEM, field emission scanning electron microscope (FESEM and atomic force microscopy (AFM.

  12. Characterization of sodium phenytoin co-gelled with titania for a controlled drug-release system

    International Nuclear Information System (INIS)

    Lopez, T.; Quintana, P.; Ortiz-Islas, E.; Vinogradova, E.; Manjarrez, J.; Aguilar, D.H.; Castillo-Ocampo, P.; Magana, C.; Azamar, J.A.

    2007-01-01

    Sodium phenytoin, C 15 H 11 N 2 NaO 2 , in several concentrations was co-gelled with titania (TiO 2 ), by a sol-gel process. This technique is a promising method to encapsulate several drugs, in this case, phenytoin is an anticonvulsant used to control epileptic seizures. Samples were prepared by adding different concentrations (X = 50, 100, 200 and 250 mg per 20 g of titania matrix) of sodium phenytoin (Ph) to a solution of titanium n-butoxide. The resulting titania-Ph-X materials were characterized by transmission electron microscopy (TEM), Fourier transformed infrared (FT-IR) spectroscopy, X-ray diffraction (XRD), and Brunauer-Emmet-Teller (BET) surface areas. The porous nanomaterials showed a wide range of particle size, from 10 to 210 nm, with a mean pore diameter of 5 nm. X-ray diffraction showed an amorphous structure of the prepared samples

  13. An iron-57 Moessbauer spectroscopic study of titania-supported iron- and iron-iridium catalysts

    International Nuclear Information System (INIS)

    Berry, F.J.; Jobson, S.

    1992-01-01

    57 Fe Moessbauer spectroscopy shows that titania-supported iron is reduced by treatment in hydrogen at significantly lower temperatures than corresponding silica- and alumina-supported catalysts. The metallic iron formed under hydrogen at 600deg C is partially converted to carbide by treatment in carbon monoxide and hydrogen. In contrast to its alumina- and silica-supported counterparts, the remainder of the titania-supported iron is unchanged by this gaseous mixture. The 57 Fe Moessbauer spectra of EXAFS show that iron and iridium in the titania-supported iron-iridium catalysts are reduced in hydrogen at even lower temperatures and, after treatment at 600deg C, are predominantly present as the iron-iridium alloy. The treatment of these reduced catalysts in carbon monoxide and hydrogen is shown by Moessbauer spectroscopy and EXAFS to induce the segregation of iron from the iron-iridium alloy and its conversion to iron oxide. (orig.)

  14. Synthesis, characterizations and photocatalytic studies of mesoporous titania prepared by using four plant skins as templates

    Energy Technology Data Exchange (ETDEWEB)

    Miao Yingchun [Department of Applied Chemistry, Key Laboratory of Medicinal Chemistry for Natural Resource, Ministry of Education, Yunnan University, Kunming 650091 (China); Faculty of Chemical and Life Sciences, Qujing Normal University, Qujing 655000 (China); Zhai Zhongbiao [Department of Applied Chemistry, Key Laboratory of Medicinal Chemistry for Natural Resource, Ministry of Education, Yunnan University, Kunming 650091 (China); Kunming Metallurgy Research Institute, Kunming 650031 (China); He Jiao; Li Bin; Li Junjie [Department of Applied Chemistry, Key Laboratory of Medicinal Chemistry for Natural Resource, Ministry of Education, Yunnan University, Kunming 650091 (China); Wang Jiaqiang, E-mail: jqwang@ynu.edu.cn [Department of Applied Chemistry, Key Laboratory of Medicinal Chemistry for Natural Resource, Ministry of Education, Yunnan University, Kunming 650091 (China)

    2010-07-20

    Anatase mesoporous titania with novel morphologies were synthesized by using the skins of tomatoes, bulb onions, grapes, and garlic bulbs, respectively, as templates and used for the photodegradation of Gentian violet, methyl violet, xylenol orange, and Rhodamine B under UV light. The samples were characterized by a combination of various physicochemical techniques, such as X-ray diffraction, SEM, HRTEM, N{sub 2} adsorption/desorption, diffuse reflectance UV-Vis, and FT-IR. It was found that all of the synthesized mesoporous titania samples exhibited similar morphologies to those of the original templates. The photoactivity of P25 TiO{sub 2} for the four dyes is nearly the same while the mesoporous titania samples synthesized by using the four skins as templates exhibited varied photoactivities for the four dyes.

  15. Iron carbide on titania surface modified with group VA oxides as Fischer-Tropsch catalysts

    International Nuclear Information System (INIS)

    Wachs, I.E.; Fiato, R.A.; Chersich, C.C.

    1986-01-01

    A catalyst is described comprising iron carbide supported on a surface modified titania wherein the support comprises an oxide of a metal selected form the group consisting of niobium, vanadium, tantalum or mixture thereof supported on the titania wherein at least a portion of the supported oxide of niobium, vanandium, tantalum or mixture is in a non-crystalline form. The amount of the supported oxide ranges from about 0.5 to 25 weight percent metal oxide on the titania support based on the total support composition and the catalyst contains at least about 2 milligrams of iron, calculated as Fe/sub 2/O/sub 3/, per square meter of support surface

  16. Titania-coated manganite nanoparticles: Synthesis of the shell, characterization and MRI properties

    Energy Technology Data Exchange (ETDEWEB)

    Jirák, Zdeněk; Kuličková, Jarmila [Institute of Physics, AS CR, Cukrovarnická 10, 162 00 Praha 6 (Czech Republic); Herynek, Vít [Institute for Clinical and Experimental Medicine, Vídeňská 1958/9, 140 21 Praha 4 (Czech Republic); Maryško, Miroslav [Institute of Physics, AS CR, Cukrovarnická 10, 162 00 Praha 6 (Czech Republic); Koktan, Jakub [Institute of Physics, AS CR, Cukrovarnická 10, 162 00 Praha 6 (Czech Republic); University of Chemistry and Technology, Prague, Technická 5, 166 28 Praha 6 (Czech Republic); Kaman, Ondřej, E-mail: kamano@seznam.cz [Institute of Physics, AS CR, Cukrovarnická 10, 162 00 Praha 6 (Czech Republic)

    2017-04-01

    Novel procedure for coating of oxide nanoparticles with titania, employing hydrolysis and polycondensation of titanium alkoxides under high-dilution conditions and cationic surfactants, is developed and applied to magnetic cores of perovskite manganite. Bare particles of the ferromagnetic La{sub 0.65}Sr{sub 0.35}MnO{sub 3} phase, possessing high magnetization, M{sub 10} {sub kOe}(4.5 K) = 63.5 emu g{sup −1}, and Curie temperature, T{sub C} = 355 K, are synthesized by sol-gel procedure and subsequently coated with titania. Further, a comparative silica-coated product is prepared. In order to analyse the morphology, colloidal stability, and surface properties of these two types of coated particles, a detailed study by means of transmission electron microscopy, dynamic light scattering, zeta-potential measurements, and IR spectroscopy is carried out. The experiments on the titania-coated sample reveal a continuous though porous character of the TiO{sub 2} shell, the nature of which is amorphous but can be transformed to anatase at higher temperatures. Finally, the relaxometric study at the magnetic field of 0.5 T, performed to quantity the transverse relaxivity and its temperature dependence, reveals important differences between the titania-coated and silica-coated nanoparticles. - Highlights: • Magnetic nanoparticles of perovskite La{sub 0.65}Sr{sub 0.35}MnO{sub 3} phase are coated with TiO{sub 2}. • The titania forms a continuous and amorphous shell and provides colloidal stability. • Morphology and surface properties are compared to a silica-coated product. • MRI properties of both the titania- and silica-coated particles are studied at 0.5 T. • The temperature dependence of r{sub 2} is strongly affected by the type of coating.

  17. Synthesis, characterization and photocatalytic activity of porous manganese oxide doped titania for toluene decomposition

    International Nuclear Information System (INIS)

    Jothiramalingam, R.; Wang, M.K.

    2007-01-01

    The present study describes the photocatalytic degradation of toluene in gas phase on different porous manganese oxide doped titanium dioxide. As synthesized birnessite and cryptomelane type porous manganese oxide were doped with titania and tested for photocatalytic decomposition of toluene in gas phase. The effects of the inlet concentration of toluene, flow rate (retention time) were examined and the relative humidity was maintained constantly. Thermal and textural characterization of manganese oxide doped titania materials were characterized by X-ray diffraction (XRD), thermogravemetry (TG), BET and TEM-EDAX studies. The aim of the present study is to synthesize the porous manganese oxide doped titania and to study its photocatalytic activity for toluene degradation in gas phase. Cryptomelane doped titania catalyst prepared in water medium [K-OMS-2 (W)] is shown the good toluene degradation with lower catalysts loading compared to commercial bulk titania in annular type photo reactor. The higher photocatalytic activity due to various factors such as catalyst preparation method, experimental conditions, catalyst loading, surface area, etc. In the present study manganese oxide OMS doped titania materials prepared by both aqueous and non-aqueous medium, aqueous medium prepared catalyst shows the good efficiency due to the presence of OH bonded groups on the surface of catalyst. The linear forms of different kinetic equations were applied to the adsorption data and their goodness of fit was evaluated based on the R 2 and standard error. The goodness to the linear fit was observed for Elovich model with high R 2 (≥0.9477) value

  18. Toward Edge-Defined Holey Boron Nitride Nanosheets

    Science.gov (United States)

    Lin, Yi; Liao, Yunlong; Chen, Zhongfan; Connell, John W.

    2015-01-01

    "Holey" two-dimensional (2D) nanosheets with well-defined holy morphology and edge chemistry are highly desirable for applications such as energy storage, catalysis, sensing, transistors, and molecular transport/separation. For example, holey grapheme is currently under extensive investigation for energy storage applications because of the improvement in ion transport due to through the thickness pathways provided by the holes. Without the holes, the 2D materials have significant limitations for such applications in which efficient ion transport is important. As part of an effort to apply this approach to other 2D nanomaterials, a method to etch geometrically defined pits or holes on the basal plane surface of hexagonal boron nitride (h-BN) nanosheets has been developed. The etching, conducted via heating in ambient air using metal nanoparticles as catalysts, was facile, controllable, and scalable. Starting h-BN layered crystals were etched and subsequently exfoliated into boron nitride nanosheets (BNNSs). The as-etched and exfoliated h-BN nanosheets possessed defined pit and hole shapes that were comprised of regulated nanostructures at the edges. The current finding are the first step toward the bulk preparation of holey BNNSs with defined holes and edges.

  19. Multimetallic nanosheets: synthesis and applications in fuel cells.

    Science.gov (United States)

    Zeb Gul Sial, Muhammad Aurang; Ud Din, Muhammad Aizaz; Wang, Xun

    2018-04-03

    Two-dimensional nanomaterials, particularly multimetallic nanosheets with single or few atoms thickness, are attracting extensive research attention because they display remarkable advantages over their bulk counterparts, including high electron mobility, unsaturated surface coordination, a high aspect ratio, and distinctive physical, chemical, and electronic properties. In particular, their ultrathin thickness endows them with ultrahigh specific surface areas and a relatively high surface energy, making them highly favorable for surface active applications; for example, they have great potential for a broad range of fuel cell applications. First, the state-of-the-art research on the synthesis of nanosheets with a controlled size, thickness, shape, and composition is described and special emphasis is placed on the rational design of multimetallic nanosheets. Then, a correlation is performed with the performance of multimetallic nanosheets with modified and improved electrochemical properties and high stability, including for the oxygen reduction reaction (ORR), hydrogen evolution reaction (HER), formic acid oxidation (FAO), methanol oxidation reaction (MOR), ethanol oxidation reaction (EOR), and methanol tolerance are outlined. Finally, some perspectives and advantages offered by this class of materials are highlighted for the development of highly efficient fuel cell electrocatalysts, featuring low cost, enhanced performance, and high stability, which are the key factors for accelerating the commercialization of future promising fuel cells.

  20. Field emission properties of ZnO nanosheet arrays

    International Nuclear Information System (INIS)

    Naik, Kusha Kumar; Rout, Chandra Sekhar; Khare, Ruchita; More, Mahendra A.; Chakravarty, Disha; Late, Dattatray J.; Thapa, Ranjit

    2014-01-01

    Electron emission properties of electrodeposited ZnO nanosheet arrays grown on Indium tin oxide coated glass substrates have been studied. Influence of oxygen vacancies on electronic structures and field emission properties of ZnO nanosheets are investigated using density functional theory. The oxygen vacancies produce unshared d electrons which form an impurity energy state; this causes shifting of Fermi level towards the vacuum, and so the barrier energy for electron extraction reduces. The ZnO nanosheet arrays exhibit a low turn-on field of 2.4 V/μm at 0.1 μA/cm 2 and current density of 50.1 μA/cm 2 at an applied field of 6.4 V/μm with field enhancement factor, β = 5812 and good field emission current stability. The nanosheet arrays grown by a facile electrodeposition process have great potential as robust high performance vertical structure electron emitters for future flat panel displays and vacuum electronic device applications

  1. Design of titania nanotube structures by focused laser beam direct writing

    International Nuclear Information System (INIS)

    Enachi, Mihai; Stevens-Kalceff, Marion A.; Sarua, Andrei; Ursaki, Veaceslav; Tiginyanu, Ion

    2013-01-01

    In this work, we report on electrochemical fabrication of titania films consisting of nanotubes (NTs) and their treatment by focused laser beam. The results of sample characterization by optical and scanning electron microscopy, cathodoluminescence imaging, and Raman scattering scanning spectroscopy are compared to those inherent to specimens subjected to thermal treatment in a furnace. The obtained data demonstrate possibilities for controlling crystallographic structure of TiO 2 NTs by focused laser beam direct writing. These findings open new prospects for the design and fabrication of spatial architectures based on titania nanotubes

  2. Dynamic Diffraction Studies on the Crystallization, Phase Transformation, and Activation Energies in Anodized Titania Nanotubes

    OpenAIRE

    Hani Albetran; Victor Vega; Victor M. Prida; It-Meng Low

    2018-01-01

    The influence of calcination time on the phase transformation and crystallization kinetics of anodized titania nanotube arrays was studied using in-situ isothermal and non-isothermal synchrotron radiation diffraction from room temperature to 900 °C. Anatase first crystallized at 400 °C, while rutile crystallized at 550 °C. Isothermal heating of the anodized titania nanotubes by an increase in the calcination time at 400, 450, 500, 550, 600, and 650 °C resulted in a slight reduction in anatase...

  3. In situ EPR studies of reaction pathways in Titania photocatalyst-promoted alkylation of alkenes.

    Science.gov (United States)

    Rhydderch, Shona; Howe, Russell F

    2015-03-03

    In situ EPR spectroscopy at cryogenic temperatures has been used to observe and identify paramagnetic species produced when titania is irradiated in the presence of reactants used in the photocatalytic alkylation of maleimide with t-butyl carboxylic acid or phenoxyacetic acid. It is shown that maleimide acts as an acceptor of conduction band electrons. Valence band holes oxidise t-butyl carboxylic acid to the t-butyl radical and phenoxyacetic acid to the phenoxyacetic acid radical cation. In the presence of maleimide, the phenoxymethyl radical is formed from phenoxyacetic acid. The relevance of these observations to the mechanisms of titania photocatalyst-promoted alkylation of alkenes is discussed.

  4. Dispersion tailoring of a silicon strip waveguide employing Titania-Alumina thin-film coating

    DEFF Research Database (Denmark)

    Guo, Kai; Christensen, Jesper B.; Christensen, Erik N.

    2017-01-01

    We numerically demonstrate dispersion tailoring of a silicon strip waveguide employing Titania-Alumina thin-film coating using a finite-difference mode solver. The proposed structure exhibits spectrally-flattened near-zero anomalous dispersion within the telecom wavelength range. We also numerica......We numerically demonstrate dispersion tailoring of a silicon strip waveguide employing Titania-Alumina thin-film coating using a finite-difference mode solver. The proposed structure exhibits spectrally-flattened near-zero anomalous dispersion within the telecom wavelength range. We also...

  5. Magnetic behaviour of arrays of Ni nanowires by electrodeposition into self-aligned titania nanotubes

    International Nuclear Information System (INIS)

    Prida, V.M.; Hernandez-Velez, M.; Cervera, M.; Pirota, K.; Sanz, R.; Navas, D.; Asenjo, A.; Aranda, P.; Ruiz-Hitzky, E.; Batallan, F.; Vazquez, M.; Hernando, B.; Menendez, A.; Bordel, N.; Pereiro, R.

    2005-01-01

    Arrays of Ni nanowires electrodeposited into self-aligned and randomly disordered titania nanotube arrays grown by anodization process are investigated by X-ray diffraction, SEM, rf-GDOES and VSM magnetometry. The titania nanotube outer diameter is about 160 nm, wall thickness ranging from 60 to 70 nm and 300 nm in depth. The so-obtained Ni nanowires reach above 100 nm diameter and 240 nm length, giving rise to coercive fields of 98 and 200 Oe in the perpendicular or parallel to the nanowires axis hysteresis loops, respectively. The formation of magnetic vortex domain states is also discussed

  6. Oxidations of amines with molecular oxygen using bifunctional gold–titania catalysts

    DEFF Research Database (Denmark)

    Klitgaard, Søren Kegnæs; Egeblad, Kresten; Mentzel, Uffe Vie

    2008-01-01

    titania catalysts can be employed to facilitate the oxidation of amines into amides with high selectivity. Furthermore, we report that pure titania is in fact itself a catalyst for the oxidation of amines with molecular oxygen under very mild conditions. We demonstrate that these new methodologies open up for two......Over the past decades it has become clear that supported gold nanoparticles are surprisingly active and selective catalysts for several green oxidation reactions of oxygen-containing hydrocarbons using molecular oxygen as the stoichiometric oxidant. We here report that bifunctional gold...

  7. Surface layer composition of titania produced by various methods. The change of layer state under illumination

    International Nuclear Information System (INIS)

    Zakharenko, V; Daibova, E; Zmeeva, O; Kosova, N

    2016-01-01

    The comparative analysis of experimental data over titanium dioxide powders prepared by various ways under ambient air is carried out. The results over TiO 2 prepared by high-temperature heating of anatase, produced by burning of titanium micro particles and grinding of rutile crystal are used for that comparison. Water and carbon dioxide were the main products released from the surface of the titania powders. It was found that under UV irradiation absorbed by titania, in absent oxygen, water effectively reacts with lattice oxygen of titanium dioxide. (paper)

  8. Two-dimensional mesoporous carbon nanosheets and their derived graphene nanosheets: synthesis and efficient lithium ion storage.

    Science.gov (United States)

    Fang, Yin; Lv, Yingying; Che, Renchao; Wu, Haoyu; Zhang, Xuehua; Gu, Dong; Zheng, Gengfeng; Zhao, Dongyuan

    2013-01-30

    We report a new solution deposition method to synthesize an unprecedented type of two-dimensional ordered mesoporous carbon nanosheets via a controlled low-concentration monomicelle close-packing assembly approach. These obtained carbon nanosheets possess only one layer of ordered mesopores on the surface of a substrate, typically the inner walls of anodic aluminum oxide pore channels, and can be further converted into mesoporous graphene nanosheets by carbonization. The atomically flat graphene layers with mesopores provide high surface area for lithium ion adsorption and intercalation, while the ordered mesopores perpendicular to the graphene layer enable efficient ion transport as well as volume expansion flexibility, thus representing a unique orthogonal architecture for excellent lithium ion storage capacity and cycling performance. Lithium ion battery anodes made of the mesoporous graphene nanosheets have exhibited an excellent reversible capacity of 1040 mAh/g at 100 mA/g, and they can retain at 833 mAh/g even after numerous cycles at varied current densities. Even at a large current density of 5 A/g, the reversible capacity is retained around 255 mAh/g, larger than for most other porous carbon-based anodes previously reported, suggesting a remarkably promising candidate for energy storage.

  9. The Effect of Titanium Tetrahedral Coordination of Silica-Titania Catalyst on the Physical Properties of Biodiesel

    Science.gov (United States)

    Nizar, U. K.; Hidayatul, J.; Sundari, R.; Bahrizal, B.; Amran, A.; Putra, A.; Latisma DJ, L.; Dewata, I.

    2018-04-01

    This study investigates the correlation of the number of titanium tetrahedral coordination and biodiesel production. The solid-state method has been used to synthesis of silica-titania catalyst for biodiesel production, which the precursors, i.e. silica and titania commercials were heated in the temperature range of 450 - 550°C. The characterization of the prepared silica-titania has been studied by FTIR and DR UV-Vis in order to identify and calculate the presence of titanium tetrahedral coordination in silica-titania catalyst. A very small peak at around 950 cm-1 indicated the presence of titanium tetrahedral coordination through Si–O–Ti bonds. Deconvolution of DR UV-Vis spectra showed the coordination of titanium in silica-titania is more octahedral. However, the number of titanium tetrahedral coordination of the prepared silica-titania is found higher than that of TiO2 commercial. The increasing of titanium tetrahedral fraction in silica-titania affects the physical properties of biodiesel in terms of boiling point, viscosity and density, which is produced by the reaction of methanol and palm oil.

  10. Plasmonic Titania Photo catalysts Active under UV and Visible-Light Irradiation: Influence of Gold Amount, Size, and Shape

    International Nuclear Information System (INIS)

    Kowalska, E.; Rau, S.; Kowalska, E.; Kowalska, E.; Ohtani, B.

    2012-01-01

    Plasmonic titania photo catalysts were prepared by titania modification with gold by photo deposition. It was found that for smaller amount of deposited gold (≤ 0.1 wt%), anatase presence and large surface area were beneficial for efficient hydrogen evolution during methanol dehydrogenation. After testing twelve amounts of deposited gold on large rutile titania, the existence of three optima for 0.5, 2 and >6 wt% of gold was found during acetic acid degradation. Under visible light irradiation, in the case of small gold NPs deposited on fine anatase titania, the dependence of photo activity on gold amount was parabolic, and large gold amount (2 wt%), observable as an intensively coloured powder, caused photo activity decrease. While for large gold NPs deposited on large rutile titania, the dependence represented cascade increase, due to change of size and shape of deposited gold with its amount increase. It has been thought that spherical/hemispherical shape of gold NPs, in comparison with rod-like ones, is beneficial for higher level of photo activity under visible light irradiation. For all tested systems and regardless of deposited amount of gold, each rutile Au/TiO 2 photo catalyst of large gold and titania NPs exhibited much higher photo activity than anatase Au/TiO 2 of small gold and titania NPs

  11. Hollow mesoporous titania microspheres: New technology and enhanced photocatalytic activity

    Energy Technology Data Exchange (ETDEWEB)

    Feng, Zhenliang; Wei, Wenrui; Wang, Litong [School of Chemical Engineering, Fuzhou University, Fuzhou 350108 (China); Hong, Ruoyu, E-mail: rhong@suda.edu.cn [School of Chemical Engineering, Fuzhou University, Fuzhou 350108 (China); College of Chemistry, Chemical Engineering and Materials Science & Key Laboratory of Organic Synthesis of Jiangsu Province, Soochow University, SIP, Suzhou 215123 (China)

    2015-12-01

    Graphical abstract: Schematic of the formation process of HTS. - Highlights: • Amino modified porous PS-DVB microspheres were used as templates to coat TiO{sub 2.} • The coating of TiO{sub 2} was conducted under regular changing atmospheric pressure. • The PS-DVB@TiO{sub 2} was calcinated first under nitrogen and then under air to get HTS. • The resultant products were provided with high surface area and excellent photocatalytic activity under UV irradiation. - Abstract: Hollow titania microspheres (HTS) were fabricated via a sol–gel process by coating the hydrolysis product of titanium tetrabutoxide (TBOT) onto the amino (–NH{sub 2}) modified porous polystyrene cross-linked divinyl benzene (PS-DVB) microspheres under changing atmospheric pressure, followed by calcination in nitrogen and air atmosphere. Particularly, the atmospheric pressure was continuously and regularly changed during the formation process of PS-DVB@TiO{sub 2} microspheres. Then the TiO{sub 2} particles were absorbed into the pores and onto the surface of PS-DVB as well. The resultant HTS (around 2 μm in diameter) featured a high specific surface area (84.37 m{sup 2}/g), anatase crystal and stable hollow microsphere structure, which led to high photocatalysis activity. The photocatalytic degradation of malachite green (MG) organic dye solution was conducted under ultraviolet (UV) light irradiation, which showed a high photocatalytic ability (81% of MG was degraded after UV irradiation for 88 min). Therefore, it could be potentially applied for the treatment of wastewater contaminated by organic pollutants.

  12. Structural and photoluminescence properties of Si-based nanosheet bundles rooted on Si substrates

    Science.gov (United States)

    Yuan, Peiling; Tamaki, Ryo; Kusazaki, Shinya; Atsumi, Nanae; Saito, Yuya; Kumazawa, Yuki; Ahsan, Nazmul; Okada, Yoshitaka; Ishida, Akihiro; Tatsuoka, Hirokazu

    2018-04-01

    Si-based nanosheet bundles were synthesized by the extraction of Ca atoms from CaSi2 microwalls grown on Si substrates by inositol hexakisphosphate solution or thermal treatment in FeCl2 vapor. The structural and photoluminescence properties of the Si-based nanosheet bundles were examined. The photoluminescence emissions in the visible region were clearly observed, and the temperature and excitation intensity dependences of the emissions were characterized. The observed Si-based nanosheets consist of thin Si layers, and a superlattice-like layered structural model is proposed to describe the Si-based nanosheet bundle structures and their photoluminescence property. The photoluminescence property of the nanosheets significantly depends on their treatment process. The luminescence mechanism of the nanosheets was discussed.

  13. Preparation and supercapacitor application of the single crystal nickel hydroxide and oxide nanosheets

    Energy Technology Data Exchange (ETDEWEB)

    Li, Qing [Department of Materials Science and Engineering, Yunnan University, 650091 Kunming (China); Ni, Haifang [Institute of Materials Science and Engineering, University of Science and Technology Beijing, 100083 Beijing (China); Cai, Yun; Cai, Xiaoyan [Department of Materials Science and Engineering, Yunnan University, 650091 Kunming (China); Liu, Yongjun [Advanced Analysis and Measurement Center, Yunnan University, 650091 Kunming (China); Chen, Gang [Department of Materials Science and Engineering, Yunnan University, 650091 Kunming (China); Fan, Li-Zhen, E-mail: fanlizhen@ustb.edu.cn [Institute of Materials Science and Engineering, University of Science and Technology Beijing, 100083 Beijing (China); Wang, Yude, E-mail: ydwang@ynu.edu.cn [Department of Materials Science and Engineering, Yunnan University, 650091 Kunming (China)

    2013-09-01

    Graphical abstract: The nickel hydroxide and nickel oxide nanosheets prepared using CTAB at room temperature exhibit a high specific capacitance, prompt charge/discharge rate. - Highlights: • The nickel hydroxide nanosheets were prepared using CTAB at room temperature. • Ni(OH){sub 2} nanosheet can be successfully converted to NiO nanosheet via calcination. • The NiO nanosheet has a specific capacitance of 388 F g{sup −1} at 5 A g{sup −1} in KOH solution. • Anneal temperature impacts capacitive properties as electrode. - Abstract: The single crystalline Ni(OH){sub 2} nanosheets were synthesized by a simple chemical precipitation method using nickel chloride as precursors and ammonia as precipitating agent. The Ni(OH){sub 2} nanosheets were successfully converted to NiO nanosheets via calcination under appropriate conditions. Analytical methods such as X-ray diffraction (XRD) spectra, scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution TEM (HRTEM), and Fourier transformed infrared (FTIR) spectra were employed to characterize the morphology and microstructure of the final products. The experimental results revealed that Ni(OH){sub 2} nanosheets were shape-preserved transformed to NiO nanosheets at 250 °C for 24 h. Ni(OH){sub 2} and NiO nanosheets were directly functionalized as supercapacitor electrodes for potential energy storage applications, whose charge–discharge properties, electrochemical impedance spectra, cyclic voltammetry, and cycle performance were examined. The experimental results show that the single-crystalline NiO nanosheets are a promising candidate for the supercapacitor electrode. They exhibit a high specific capacitance, prompt charge/discharge rate.

  14. Layered-metal-hydroxide nanosheet arrays with controlled nanostructures to assist direct electronic communication at biointerfaces.

    Science.gov (United States)

    An, Zhe; Lu, Shan; Zhao, Liwei; He, Jing

    2011-10-18

    In this work, ordered vertical arrays of layered double hydroxide (LDH) nanosheets have been developed to achieve electron transfer (eT) at biointerfaces in electrochemical devices. It is found that tailoring the gap size of LDH nanosheet arrays could significantly promote the eT rate. This research has successfully extended nanomaterials for efficient modifications of electrode surfaces from nanoparticles, nanowires, nanorods, and nanotubes to nanosheets. © 2011 American Chemical Society

  15. Climatic impacts of stratospheric geoengineering with sulfate, black carbon and titania injection

    Directory of Open Access Journals (Sweden)

    A. C. Jones

    2016-03-01

    Full Text Available In this paper, we examine the potential climatic effects of geoengineering by sulfate, black carbon and titania injection against a baseline RCP8.5 scenario. We use the HadGEM2-CCS model to simulate scenarios in which the top-of-the-atmosphere radiative imbalance due to rising greenhouse gas concentrations is offset by sufficient aerosol injection throughout the 2020–2100 period. We find that the global-mean temperature is effectively maintained at historical levels for the entirety of the period for all three aerosol-injection scenarios, though there is a wide range of side-effects which are discussed in detail. The most prominent conclusion is that although the BC injection rate necessary to produce an equivalent global mean temperature response is much lower, the severity of stratospheric temperature changes (> +70 °C and precipitation impacts effectively exclude BC from being a viable option for geoengineering. Additionally, while it has been suggested that titania would be an effective particle because of its high scattering efficiency, it also efficiently absorbs solar ultraviolet radiation producing a significant stratospheric warming (> +20 °C. As injection rates and climatic impacts for titania are close to those for sulfate, there appears to be little benefit in terms of climatic influence of using titania when compared to the injection of sulfur dioxide, which has the added benefit of being well-modeled through extensive research that has been carried out on naturally occurring explosive volcanic eruptions.

  16. Degradation of organophosphorus pesticide parathion methyl on nanostructured titania-iron mixed oxides

    Czech Academy of Sciences Publication Activity Database

    Henych, Jiří; Štengl, Václav; Slušná, Michaela; Matys Grygar, Tomáš; Janoš, P.; Kuráň, P.; Šťastný, M.

    2015-01-01

    Roč. 344, JUL (2015), s. 9-16 ISSN 0169-4332 R&D Projects: GA ČR(CZ) GAP106/12/1116 Institutional support: RVO:61388980 Keywords : Titania-iron oxides * Homogeneous hydrolysis * Degradation of organophosphates * Parathion methyl Subject RIV: CA - Inorganic Chemistry Impact factor: 3.150, year: 2015

  17. Effect of urea on the photoactivity of titania powder prepared by sol-gel method

    International Nuclear Information System (INIS)

    Cheng Ping; Deng Changsheng; Gu Mingyuan; Dai Xiaming

    2008-01-01

    The synthesis of nanocrystalline titania powders from the hydrolysis of Ti(OBu n ) 4 in the presence of urea was investigated. DRS results showed that a redshift occurred in the absorption edge of titania with increasing the content of urea. XRD results indicated that urea showed a retarding effect on the transformation of titania from anatase to rutile. Moreover, the addition of urea resulted in a higher Brunauer-Emmett-Teller (BET) surface area as well as a larger average pore size of TiO 2 nanoparticles. The average pore size of urea/TiO 2 gels calcined at 500 deg. C increased with the increase of urea content, while the specific surface area increased with the amount of urea to reach a maximum at 10% and then decreased with further increase of the amount of urea. The maximal specific surface area of 64.4 m 2 g -1 was obtained for 10% urea/TiO 2 gels calcined at 500 deg. C, which showed an average particle size of 15 nm and pore size distribution in the range of mesopores centered at 5.8 nm. The photocatalytic experiments exhibited that titania nanoparticles prepared in the presence of urea could effectively photodegrade methyl orange under visible light irradiation due to the redshift of the absorption edge. The maximum photoactivity was achieved when the content of urea was 10%, which was attributed to the higher specific surface area

  18. Photocatalytic degradation of paraoxon-ethyl in aqueous solution using titania nanoparticulate film

    International Nuclear Information System (INIS)

    Prasad, G.K.; Ramacharyulu, P.V.R.K.; Kumar, J. Praveen; Srivastava, A.R.; Singh, Beer

    2012-01-01

    Photocatalytic degradation of paraoxon-ethyl (o,o-diethyl o-(4-nitrophenyl) phosphate), a well known surrogate of chemical warfare agents, in aqueous solution was studied by using titania nanoparticulate film. Reaction followed pseudo first order behaviour. Photolytic degradation reaction of paraoxon-ethyl demonstrated relatively low rate with a value of rate constant of 2.5 × 10 −3 min −1 . Whereas, degradation reaction in the presence of titania nanoparticulate film and UV light displayed enhanced rate with a value of rate constant of 6.9 × 10 −3 min −1 due to photocatalysis. Gas chromatography–mass spectrometry analysis showed the formation of p-nitrophenol, o,o-diethyl phosphonic acid, o-ethyl, diphosphonic acid, phosphoric acid, dimerized product of o,o-diethyl phosphonic acid, acetaldehyde, and carbon dioxide due to photocatalytic degradation of paraoxon-ethyl. It indicates that, photocatalytic degradation reaction begins with destruction of P–O–C bonds. Subsequently, P, C atoms were found to be oxidized gradually, and contributed to its photocatalytic degradation. - Highlights: ► Synthesis of titania nanoparticles by sol–gel method. ► Fabrication of titania nanoparticulate film by dip coating. ► Paraoxon ethyl degradation reactions followed pseudo first order behaviour. ► Paraoxon-ethyl degraded to non toxic compounds like CO 2 , acetaldehyde, and nitrophenol.

  19. Optical, mechanical and TEM assessment of titania-doped Bi2V1 ...

    Indian Academy of Sciences (India)

    2016-08-26

    Aug 26, 2016 ... Home; Journals; Bulletin of Materials Science; Volume 37; Issue 7. Optical, mechanical and TEM assessment of titania-doped Bi2V1−TiO5.5−δ bismuth vanadate oxides. Gurbinder Kaur Gary Pickrell Vishal Kumar Om Prakash Pandey Kulvir Singh Daniel Homa. Volume 37 Issue 7 December 2014 pp ...

  20. Kinetics of the water formation in the propene epoxidation over gold-titania catalysts

    NARCIS (Netherlands)

    Nijhuis, T.A.; Weckhuysen, B.M.

    2007-01-01

    The kinetics of the hydrogen oxidation were determined for a number of different gold catalysts supported on titania, silica, and silicalite-1. A dual site Langmuir-Hinshelwood kinetic model was able to describe the reaction well. The kinetic parameters are independent of the support. Water was

  1. Dynamic Diffraction Studies on the Crystallization, Phase Transformation, and Activation Energies in Anodized Titania Nanotubes

    Directory of Open Access Journals (Sweden)

    Hani Albetran

    2018-02-01

    Full Text Available The influence of calcination time on the phase transformation and crystallization kinetics of anodized titania nanotube arrays was studied using in-situ isothermal and non-isothermal synchrotron radiation diffraction from room temperature to 900 °C. Anatase first crystallized at 400 °C, while rutile crystallized at 550 °C. Isothermal heating of the anodized titania nanotubes by an increase in the calcination time at 400, 450, 500, 550, 600, and 650 °C resulted in a slight reduction in anatase abundance, but an increase in the abundance of rutile because of an anatase-to-rutile transformation. The Avrami equation was used to model the titania crystallization mechanism and the Arrhenius equation was used to estimate the activation energies of the titania phase transformation. Activation energies of 22 (10 kJ/mol for the titanium-to-anatase transformation, and 207 (17 kJ/mol for the anatase-to-rutile transformation were estimated.

  2. In vivo demonstration of enhanced radiotherapy using rare earth doped titania nanoparticles.

    Science.gov (United States)

    Townley, Helen E; Kim, Jeewon; Dobson, Peter J

    2012-08-21

    Radiation therapy is often limited by damage to healthy tissue and associated side-effects; restricting radiation to ineffective doses. Preferential incorporation of materials into tumour tissue can enhance the effect of radiation. Titania has precedent for use in photodynamic therapy (PDT), generating reactive oxygen species (ROS) upon photoexcitation, but is limited by the penetration depth of UV light. Optimization of a nanomaterial for interaction with X-rays could be used for deep tumour treatment. As such, titania nanoparticles were doped with gadolinium to optimize the localized energy absorption from a conventional medical X-ray, and further optimized by the addition of other rare earth (RE) elements. These elements were selected due to their large X-ray photon interaction cross-section, and potential for integration into the titania crystal structure. Specific activation of the nanoparticles by X-ray can result in generation of ROS leading to cell death in a tumour-localized manner. We show here that intratumoural injection of RE doped titania nanoparticles can enhance the efficacy of radiotherapy in vivo.

  3. Enhanced photocatalytic activity of titania-silica mixed oxide prepared via basic hydrolyzation

    International Nuclear Information System (INIS)

    Xie Chao; Xu Zili; Yang Qiujing; Xue Baoyong; Du Yaoguo; Zhang Jiahua

    2004-01-01

    Two different synthesis routes were applied to prepare TiO 2 -XSiO 2 (X denotes mol% of silica in titania-silica mixed oxides) with different silica concentrations by using ammonia water as hydrolysis catalyst. Through comparing the photocatalytic performance of two sets of mixed oxides, we found that the photocatalytic activity of mixed oxides prepared via the route which can promote homogeneity, was significantly enhanced as compared with that of counterparts prepared via the another route, and the highest photocatalytic activity obtained by adding about 9.1 mol% silica into titania was much higher than that of pure TiO 2 . The mixed oxides were investigated by means of XRD, thermal analysis, UV-vis, FT-IR and XPS. The characterization results suggest that, in comparison with pure TiO 2 , the mixed oxides exhibit smaller crystallite size and higher thermal stability which can elevate the temperature of anatase to rutile phase transformation due to the addition of silica. Furthermore, Broensted acidity, which is associated with the formation of Ti-O-Si hetero linkages where tetrahedrally coordinated silica is chemically mixed with the octahedral titania matrix, may be a very important contribution to the enhanced photocatalytic activity of titania-silica mixed oxides as well

  4. Facile synthesis of hierarchical nanostructured rutile titania for lithium-ion battery

    International Nuclear Information System (INIS)

    Fei Hailong; Wei Mingdeng

    2011-01-01

    Highlights: → Rutile TiO 2 sub-microflowers and sub-microspheres with different building blocks as anode materials of lithium-ion battery. → Controllable morphologies with oxalic acid by the hydrothermal technique. → Sub-microflower and sub-microspheres constructed by well organized nanorods exhibited high capacity and good cycle stability. → Small size building blocks nanorods enhance the transfer rate of Li-ion. - Abstract: A facile hydrothermal method is developed to prepare rutile titania sub-microflowers consisting of nanorods with oxalic acid and TiOSO 4 as reagents. The diameter of sub-microflowers and nanorods is found to be ca. 800 and 40 nm, respectively. Also, the shape and size of building blocks in rutile titania sub-microflowers can be considerably controlled via adjusting the reaction time and reactant amounts. Rutile titania sub-microflowers composed of nanorods display higher discharge capacity and better rate cycle stability than other rutile titania nanostructures as lithium-ion battery anode material due to enhancing the Li-ion transfer rate for small size building blocks.

  5. Hazard reduction for the application of titania nanoparticles in environmental technology

    NARCIS (Netherlands)

    Reijnders, L.

    2008-01-01

    Photocatalytically active titania (TiO2) nanoparticles are applied, and considered for application, in the degradation of hazardous substances. However, these nanoparticles are also hazardous by themselves. High efficiency immobilization of TiO2 nanoparticles on large inorganic supports that are not

  6. Photocatalytic degradation of paraoxon-ethyl in aqueous solution using titania nanoparticulate film

    Energy Technology Data Exchange (ETDEWEB)

    Prasad, G.K., E-mail: gkprasad2001@yahoo.com; Ramacharyulu, P.V.R.K.; Kumar, J. Praveen; Srivastava, A.R.; Singh, Beer

    2012-06-30

    Photocatalytic degradation of paraoxon-ethyl (o,o-diethyl o-(4-nitrophenyl) phosphate), a well known surrogate of chemical warfare agents, in aqueous solution was studied by using titania nanoparticulate film. Reaction followed pseudo first order behaviour. Photolytic degradation reaction of paraoxon-ethyl demonstrated relatively low rate with a value of rate constant of 2.5 Multiplication-Sign 10{sup -3} min{sup -1}. Whereas, degradation reaction in the presence of titania nanoparticulate film and UV light displayed enhanced rate with a value of rate constant of 6.9 Multiplication-Sign 10{sup -3} min{sup -1} due to photocatalysis. Gas chromatography-mass spectrometry analysis showed the formation of p-nitrophenol, o,o-diethyl phosphonic acid, o-ethyl, diphosphonic acid, phosphoric acid, dimerized product of o,o-diethyl phosphonic acid, acetaldehyde, and carbon dioxide due to photocatalytic degradation of paraoxon-ethyl. It indicates that, photocatalytic degradation reaction begins with destruction of P-O-C bonds. Subsequently, P, C atoms were found to be oxidized gradually, and contributed to its photocatalytic degradation. - Highlights: Black-Right-Pointing-Pointer Synthesis of titania nanoparticles by sol-gel method. Black-Right-Pointing-Pointer Fabrication of titania nanoparticulate film by dip coating. Black-Right-Pointing-Pointer Paraoxon ethyl degradation reactions followed pseudo first order behaviour. Black-Right-Pointing-Pointer Paraoxon-ethyl degraded to non toxic compounds like CO{sub 2}, acetaldehyde, and nitrophenol.

  7. Recyclable Aggregates of Mesoporous Titania Synthesized by Thermal Treatment of Amorphous or Peptized Precursors

    Directory of Open Access Journals (Sweden)

    Maria Cristina Mascolo

    2018-03-01

    Full Text Available Recyclable aggregates of mesoporous titania with different anatase–rutile ratios have been prepared by thermal treatments of either amorphous or peptized precursors. These last two have been obtained by hydrolysis of either Ti(OC2H54 or of Ti(OC2H54 in mixture with 5 mol % Zr(OC3H74 at room temperature in the presence of NH4OH as a catalyzing agent. The anatase–rutile ratio, the recyclable aggregates of the nano-sized particles, the mesoporosity, the surface area and the crystallinity of the resulting crystallized products of titania can be controlled by the synthesis parameters including: concentration of ammonia catalyst, stirring time and concentration of the peptizing HNO3, drying method of peptized precursors, calcination temperature, and finally the ramp rate up to the titania crystallization temperature. A broad range of synthesis parameters control the crystal sizes of titania particles produced. This allows catalyst preparation with very different crystal size, surface area, anatase to rutile crystal ratio and various mesoporous structures. Drying by lyophilization of precursors reduce the aggregation of the primary particles giving micro-/macroporous structures.

  8. Preparation of Nanocrystalline Titania Thin Films by Using Pure and Water-modified Supercritical Carbon Dioxide.

    Czech Academy of Sciences Publication Activity Database

    Sajfrtová, Marie; Cerhová, Marie; Dřínek, Vladislav; Daniš, S.; Matějová, L.

    2016-01-01

    Roč. 117, NOV 2016 (2016), s. 289-296 ISSN 0896-8446 R&D Projects: GA ČR GA14-23274S Institutional support: RVO:67985858 Keywords : titania thin films * supercritical carbon dioxide * crystallization Subject RIV: CA - Inorganic Chemistry Impact factor: 2.991, year: 2016

  9. Thermal stability of titanate nanorods and titania nanowires formed from titanate nanotubes by heating

    Czech Academy of Sciences Publication Activity Database

    Brunátová, T.; Matěj, Z.; Oleynikov, P.; Vesely, J.; Danis, S.; Popelková, Daniela; Kuzel, R.

    2014-01-01

    Roč. 98, December (2014), s. 26-36 ISSN 1044-5803 Institutional support: RVO:61389013 Keywords : titania nanowires * titanate nanorods * X-ray diffraction Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.845, year: 2014

  10. Bactericidal performance of visible-light responsive titania photocatalyst with silver nanostructures.

    Directory of Open Access Journals (Sweden)

    Ming-Show Wong

    Full Text Available BACKGROUND: Titania dioxide (TiO(2 photocatalyst is primarily induced by ultraviolet light irradiation. Visible-light responsive anion-doped TiO(2 photocatalysts contain higher quantum efficiency under sunlight and can be used safely in indoor settings without exposing to biohazardous ultraviolet light. The antibacterial efficiency, however, remains to be further improved. METHODOLOGY/PRINCIPAL FINDINGS: Using thermal reduction method, here we synthesized silver-nanostructures coated TiO(2 thin films that contain a high visible-light responsive antibacterial property. Among our tested titania substrates including TiO(2, carbon-doped TiO(2 [TiO(2 (C] and nitrogen-doped TiO(2 [TiO(2 (N], TiO(2 (N showed the best performance after silver coating. The synergistic antibacterial effect results approximately 5 log reductions of surviving bacteria of Escherichia coli, Streptococcus pyogenes, Staphylococcus aureus and Acinetobacter baumannii. Scanning electron microscope analysis indicated that crystalline silver formed unique wire-like nanostructures on TiO(2 (N substrates, while formed relatively straight and thicker rod-shaped precipitates on the other two titania materials. CONCLUSION/SIGNIFICANCE: Our results suggested that proper forms of silver on various titania materials could further influence the bactericidal property.

  11. Carbon nanosheets by microwave plasma enhanced chemical vapor deposition in CH4-Ar system

    International Nuclear Information System (INIS)

    Wang Zhipeng; Shoji, Mao; Ogata, Hironori

    2011-01-01

    We employ a new gas mixture of CH 4 -Ar to fabricate carbon nanosheets by microwave plasma enhanced chemical vapor deposition at the growth temperature of less than 500 deg. C. The catalyst-free nanosheets possess flower-like structures with a large amount of sharp edges, which consist of a few layers of graphene sheets according to the observation by transmission electron microscopy. These high-quality carbon nanosheets demonstrated a faster electron transfer between the electrolyte and the nanosheet surface, due to their edge defects and graphene structures.

  12. Physicochemical characterization of functionalized-nanostructured-titania as a carrier of copper complexes for cancer treatment

    Energy Technology Data Exchange (ETDEWEB)

    López, Tessy [Nanotechnology and Nanomedicine Laboratory, Metropolitan Autonomous University-Xochimilco, Calzada del Hueso 1100, Villa Quietud, Coyoacán, 04960 México D.F. (Mexico); Nanotechnology Laboratory, National Institute of Neurology and Neurosurgery “MVS”, Avenida Insurgentes Sur 3877, La Fama, Tlalpan, 14269 México D.F. (Mexico); Department of Chemical and Biomolecular Engineering, Tulane University, 6823 St. Charles Avenue, New Orleans (United States); Ortiz, Emma, E-mail: emma170@hotmail.com [Nanotechnology Laboratory, National Institute of Neurology and Neurosurgery “MVS”, Avenida Insurgentes Sur 3877, La Fama, Tlalpan, 14269 México D.F. (Mexico); Guevara, Patricia [Neuroimmunology Laboratory, National Institute of Neurology and Neurosurgery “MVS”, Insurgentes Sur 3877, La Fama, Tlalpan, 14269 México D.F. (Mexico); Gómez, Esteban [Nanotechnology Laboratory, National Institute of Neurology and Neurosurgery “MVS”, Avenida Insurgentes Sur 3877, La Fama, Tlalpan, 14269 México D.F. (Mexico); Novaro, Octavio [Institute of Physics-UNAM, Circuito de la Investigación Científica Ciudad Universitaria, CP 04510 México D.F. (Mexico)

    2014-07-01

    In the present paper we report the preparation and characterization of functionalized-TiO{sub 2} (F-TiO{sub 2}) to obtain a biocompatible material to be used as carrier of alternative anticancer agents: copper acetate and copper acetylacetonate. The sol–gel procedure was used to prepare the fuctionalized titania material through hydrolysis and condensation of the titanium's butoxide. Sulfate, amine and phosphate ions served as functional groups which were anchored to the titania's surface. Mineral acids and gamma amine butyric acid were the precursors and they were added at the initial step of the synthesis. The copper complexes were loaded on titania and were also added to the reactor synthesis from the beginning. Infrared and ultraviolet–visible spectroscopies were the principal techniques used to the characterization of F-TiO{sub 2} and copper complexes loaded on titania materials. Transmission Electronic Microscopy (TEM) was used to complement the characterization's studies. The biocompatibility of F-TiO{sub 2} was evaluated by treating different cancer cell lines with increased concentration of this compound. The amine, the sulfate and the phosphate on the titania's surface, as well as the integral structures of the metal complexes on titania were well identified by infrared and ultraviolet–visible spectroscopies. The TEM photographs of Cu(acac){sub 2}/F-TiO{sub 2} and Cu(Oac){sub 2}/F-TiO{sub 2} materials showed the formation of nanoparticles, which have sizes ranging from 4 to 10 nm, with no morphology alterations in comparison with F-TiO{sub 2} nanoparticles, suggesting that the presence of low quantities of copper do not affect the structure of the nanoparticles. The Energy Dispersive Spectroscopy (EDS) confirms the presence of copper on the titania's nanoparticles. The biological results indicate that there is more than 90% cell survival, thus suggesting that F-TiO{sub 2} does not cause damage to the cells. Therefore

  13. Physicochemical characterization of functionalized-nanostructured-titania as a carrier of copper complexes for cancer treatment

    International Nuclear Information System (INIS)

    López, Tessy; Ortiz, Emma; Guevara, Patricia; Gómez, Esteban; Novaro, Octavio

    2014-01-01

    In the present paper we report the preparation and characterization of functionalized-TiO 2 (F-TiO 2 ) to obtain a biocompatible material to be used as carrier of alternative anticancer agents: copper acetate and copper acetylacetonate. The sol–gel procedure was used to prepare the fuctionalized titania material through hydrolysis and condensation of the titanium's butoxide. Sulfate, amine and phosphate ions served as functional groups which were anchored to the titania's surface. Mineral acids and gamma amine butyric acid were the precursors and they were added at the initial step of the synthesis. The copper complexes were loaded on titania and were also added to the reactor synthesis from the beginning. Infrared and ultraviolet–visible spectroscopies were the principal techniques used to the characterization of F-TiO 2 and copper complexes loaded on titania materials. Transmission Electronic Microscopy (TEM) was used to complement the characterization's studies. The biocompatibility of F-TiO 2 was evaluated by treating different cancer cell lines with increased concentration of this compound. The amine, the sulfate and the phosphate on the titania's surface, as well as the integral structures of the metal complexes on titania were well identified by infrared and ultraviolet–visible spectroscopies. The TEM photographs of Cu(acac) 2 /F-TiO 2 and Cu(Oac) 2 /F-TiO 2 materials showed the formation of nanoparticles, which have sizes ranging from 4 to 10 nm, with no morphology alterations in comparison with F-TiO 2 nanoparticles, suggesting that the presence of low quantities of copper do not affect the structure of the nanoparticles. The Energy Dispersive Spectroscopy (EDS) confirms the presence of copper on the titania's nanoparticles. The biological results indicate that there is more than 90% cell survival, thus suggesting that F-TiO 2 does not cause damage to the cells. Therefore, highly biocompatible titania was obtained by

  14. Controlled release of phenytoin for epilepsy treatment from titania and silica based materials

    Energy Technology Data Exchange (ETDEWEB)

    Lopez, Tessy, E-mail: tessy3@prodigy.net.mx [Universidad Autonoma Metropolitana-Xochimilco. Departamento de Microbiologia. Calzada del Hueso 1100, Col. Villa Quietud, Coyoacan, C.P. 04960, Mexico D.F. Mexico (Mexico); Instituto Nacional de Neurologia y Neurocirugia ' MVS' . Laboratorio de Nanotecnologia. Av. Insurgentes Sur 3877, Col. La Fama, Tlalpan, 14269, Mexico, D.F. Mexico (Mexico); Department of Chemical and Biomolecular Engineering, Tulane University, New Orleans, LA 70118 (United States); Ortiz, Emma [Instituto Nacional de Neurologia y Neurocirugia ' MVS' . Laboratorio de Nanotecnologia. Av. Insurgentes Sur 3877, Col. La Fama, Tlalpan, 14269, Mexico, D.F. Mexico (Mexico); Meza, Doraliz [Universidad Autonoma Metropolitana-Iztapalapa, Departamento de Quimica, Av. San Rafael Atlixco 186, A.P. 55-534, Mexico D.F., C.P. 09340 (Mexico); Basaldella, Elena [CIC-CINDECA - Universidad Nacional de La Plata - Calle 47 No 257 - La Plata (Argentina); Bokhimi, Xim; Magana, Carlos [Instituto de fisica, UNAM. Circuito de la Investigacion s/n. C.U. Mexico D.F. 01000 (Mexico); Sepulveda, Antonio; Rodriguez, Francisco; Ruiz, Javier [Departamento de Quimica Inorganica, Universidad de Alicante. Apartado 99, E-03080 Alicante, Espana Spain (Spain)

    2011-04-15

    Research highlights: {yields} Template technique was used to obtain well ordered nanostructured materials: SBA-15 and titania tubes. {yields} Phenytoin (PH), a drug used in epilepsy treatment, was loaded in these materials to used como PH release. {yields} Loaded PH showed a good stability inside the used materials as observed by spectroscopy analysis. {yields} The load-release PH are faster in nanostructured TiO2 tubes than in mesoporous silica matrix. {yields} There is an inverse effect of the surface area of the structured materials on the amount of released PH. - Abstract: Template technique was used to obtain well ordered nanostructured materials: mesoporous silica and nanostructured titania tubes. This technique permits the synthesis of solids with controlled mesoporosity, where a large variety of molecules that have therapeutic activity can be hosted and further released to specific sites. In this work phenytoin (PH), a drug used in epilepsy treatment, was loaded in ordered mesoporous silica (SBA 15) and nanostructured titania tubes (TiO{sub 2}). The pure materials and those containing PH were characterized by X-ray diffraction, FTIR spectroscopy, transmission electron microscopy (TEM), scanning electron microscopy (SEM) and N{sub 2} adsorption-desorption at 77 K. In order to determine the loading capacity of the antiepileptic drug on these silica- and titania-based materials, the loading and release of PH was investigated using UV-vis spectroscopy. Tubular structures were found for the titania samples, for which the X-ray diffractograms showed to be formed by anatase and rutile phases. On the other hand, an amorphous phase was found in the silica sample. A highly ordered hexagonal structure of 1D cylindrical channels was also observed for this material. Loaded PH showed a good stability inside the used materials as observed by spectroscopy analysis. The adsorption and desorption of PH are faster in nanostructured TiO{sub 2} tubes than in mesoporous silica

  15. Synthesis of Titania-supported Copper Nanoparticles via Refined Alkoxide Sol-gel Process

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Jeffrey C.S., E-mail: Cswu@ccms.ntu.edu.tw; Tseng, I.-Hsiang; Chang, W.-C. [National Taiwan University, Department of Chemical Engineering (China)

    2001-06-15

    Nanoparticles of titania and copper-loaded titania were synthesized by a refined sol-gel method using titanium butoxide. Unlike the conventional sol-gel procedure of adding water directly, the esterification of anhydrous butanol and glacial acetic acid provided the hydrolyzing water. In addition, acetic acid also served as a chelating ligand to stabilize the hydrolysis-condensation process and minimize the agglomeration of titania. Following the hydrolysis, Cu/TiO{sub 2} was prepared by adding copper chloride to titania sol. The sol was dried, then calcined at 500 deg. C to remove organics and transformed to anatase titania which was verified by XRD. Cu/TiO{sub 2} was further hydrogen-reduced at 300 deg. C. The recovery of Ti was exceeded by an average of 95% from titanium butoxide. TEM micrographs show that the Cu/TiO{sub 2} particles are near uniform. The average crystallite sizes are 17-20 nm estimated from the peak broadening of XRD spectra. The bandgaps of TiO{sub 2} and reduced Cu/TiO{sub 2} range from 2.70 to 3.15 eV estimated from the diffusive reflective UV-Vis spectra. XPS analysis shows that Cu 2p{sub 3/2} is 933.4 eV indicating primary Cu{sub 2}O form on the TiO{sub 2} supports. The binding energy of Ti does not exhibit chemical shift suggesting negligible interaction of Cu cluster and TiO{sub 2} support.

  16. Controlled release of phenytoin for epilepsy treatment from titania and silica based materials

    International Nuclear Information System (INIS)

    Lopez, Tessy; Ortiz, Emma; Meza, Doraliz; Basaldella, Elena; Bokhimi, Xim; Magana, Carlos; Sepulveda, Antonio; Rodriguez, Francisco; Ruiz, Javier

    2011-01-01

    Research highlights: → Template technique was used to obtain well ordered nanostructured materials: SBA-15 and titania tubes. → Phenytoin (PH), a drug used in epilepsy treatment, was loaded in these materials to used como PH release. → Loaded PH showed a good stability inside the used materials as observed by spectroscopy analysis. → The load-release PH are faster in nanostructured TiO2 tubes than in mesoporous silica matrix. → There is an inverse effect of the surface area of the structured materials on the amount of released PH. - Abstract: Template technique was used to obtain well ordered nanostructured materials: mesoporous silica and nanostructured titania tubes. This technique permits the synthesis of solids with controlled mesoporosity, where a large variety of molecules that have therapeutic activity can be hosted and further released to specific sites. In this work phenytoin (PH), a drug used in epilepsy treatment, was loaded in ordered mesoporous silica (SBA 15) and nanostructured titania tubes (TiO 2 ). The pure materials and those containing PH were characterized by X-ray diffraction, FTIR spectroscopy, transmission electron microscopy (TEM), scanning electron microscopy (SEM) and N 2 adsorption-desorption at 77 K. In order to determine the loading capacity of the antiepileptic drug on these silica- and titania-based materials, the loading and release of PH was investigated using UV-vis spectroscopy. Tubular structures were found for the titania samples, for which the X-ray diffractograms showed to be formed by anatase and rutile phases. On the other hand, an amorphous phase was found in the silica sample. A highly ordered hexagonal structure of 1D cylindrical channels was also observed for this material. Loaded PH showed a good stability inside the used materials as observed by spectroscopy analysis. The adsorption and desorption of PH are faster in nanostructured TiO 2 tubes than in mesoporous silica matrix.

  17. Anomalous piezoelectricity in two-dimensional graphene nitride nanosheets.

    Science.gov (United States)

    Zelisko, Matthew; Hanlumyuang, Yuranan; Yang, Shubin; Liu, Yuanming; Lei, Chihou; Li, Jiangyu; Ajayan, Pulickel M; Sharma, Pradeep

    2014-06-27

    Piezoelectricity is a unique property of materials that permits the conversion of mechanical stimuli into electrical and vice versa. On the basis of crystal symmetry considerations, pristine carbon nitride (C3N4) in its various forms is non-piezoelectric. Here we find clear evidence via piezoresponse force microscopy and quantum mechanical calculations that both atomically thin and layered graphitic carbon nitride, or graphene nitride, nanosheets exhibit anomalous piezoelectricity. Insights from ab inito calculations indicate that the emergence of piezoelectricity in this material is due to the fact that a stable phase of graphene nitride nanosheet is riddled with regularly spaced triangular holes. These non-centrosymmetric pores, and the universal presence of flexoelectricity in all dielectrics, lead to the manifestation of the apparent and experimentally verified piezoelectric response. Quantitatively, an e11 piezoelectric coefficient of 0.758 C m(-2) is predicted for C3N4 superlattice, significantly larger than that of the commonly compared α-quartz.

  18. Nanosheet-Assembled ZnO Microflower Photocatalysts

    Directory of Open Access Journals (Sweden)

    Siwen Zhang

    2014-01-01

    Full Text Available Large scale ZnO microflowers assembled by numerous nanosheets are synthesized through a facile and effective hydrothermal route. The structure and morphology of the resultant products are characterized by X-ray diffraction (XRD and scanning electron microscope (SEM. Photocatalytic properties of the as-synthesized products are also investigated. The results demonstrate that eosin red aqueous solution can be degraded over 97% after 110 min under UV light irradiation. In addition, methyl orange (MO and Congo red (CR aqueous solution degradation experiments also are conducted in the same condition, respectively. It showed that nanosheet-assembled ZnO microflowers represent high photocatalytic activities with a degradation efficiency of 91% for CR with 90 min of irradiation and 90% for MO with 60 min of irradiation. The reported ZnO products may be promising candidates as the photocatalysts in waste water treatment.

  19. Reduced humic acid nanosheets and its uses as nanofiller

    Science.gov (United States)

    Duraia, El-shazly M.; Henderson, B.; Beall, Gary W.

    2015-10-01

    Leonardite is highly oxidized form of lignite coal and contains a number of carboxyl groups around the edges of a graphene-like core. A novel approach has been developed to synthesize graphene oxide-like nanosheets in large scale utilizing leonardite as a starting material. Humic acid extracted from leonardite has been reduced by performing a high pressure catalytic hydrogenation. The reaction was carried out inside a high pressure stirred reactor at 150 °C and 750 psi (~5.2×106 Pa). Morphology of the as-synthesized samples showed porous platy particles and EDAX analysis indicates the carbon and oxygen atomic ratios as 96:4-97:3%. The as-synthesized material has been used as nanofiller in polyurethane. The reduced humic acid-polyurethane nanocomposite showed over 250% increase of Young's modulus. This new approach provides a low cost and scalable source for graphene oxide-like nanosheets in nanocomposite applications.

  20. Adsorption of CO, CO2, H2, and H2O on titania surfaces with different oxidation states

    International Nuclear Information System (INIS)

    Raupp, G.B.; Dumesic, J.A.

    1985-01-01

    The adsorptive properties of titania surfaces with different oxidation states were proved by temperature-programmed desorption (TPD) of CO, H 2 , CO 2 , and H 2 O. Auger electron spectroscopy and X-ray photoelectron spectroscopy revealed that vacuum annealing an oxidized titanium foil at temperatures from 300 to 800 K was an effective means of systematically varying the average surface oxidation state from Ti 4+ to Ti 2+ . Carbon monoxide weakly adsorbed (desorption energy of 44-49 kJ x mol -1 ) in a carbonyl fashion on coordinatively unsaturated cation sites. Titania surfaces were inert with respect to H 2 adsorption and dissociation. Carbon dioxide adsorbed in a linear molecular fashion. Water adsorbed both molecularly and dissociatively. Results are discussed in terms of the role of titania oxidation state in CO hydrogenation over titania-supported metal catalysts. 74 references, 7 figures

  1. Nickel-cobalt hydroxide nanosheets: Synthesis, morphology and electrochemical properties

    Czech Academy of Sciences Publication Activity Database

    Schneiderová, Barbora; Demel, Jan; Zhigunov, Alexander; Bohuslav, Jan; Tarábková, Hana; Janda, Pavel; Lang, Kamil

    2017-01-01

    Roč. 499, AUG (2017), s. 138-144 ISSN 0021-9797 Institutional support: RVO:61388980 ; RVO:61389013 ; RVO:61388955 Keywords : Hydroxide nanosheets * Delamination * Exfoliation * Layered nickel hydroxide * Layered cobalt hydroxide * Electrode material Subject RIV: CA - Inorganic Chemistry; CF - Physical ; Theoretical Chemistry (UFCH-W); CD - Macromolecular Chemistry (UMCH-V) OBOR OECD: Inorganic and nuclear chemistry; Physical chemistry (UFCH-W); Polymer science (UMCH-V) Impact factor: 4.233, year: 2016

  2. Nucleic acid-functionalized transition metal nanosheets for biosensing applications.

    Science.gov (United States)

    Mo, Liuting; Li, Juan; Liu, Qiaoling; Qiu, Liping; Tan, Weihong

    2017-03-15

    In clinical diagnostics, as well as food and environmental safety practices, biosensors are powerful tools for monitoring biological or biochemical processes. Two-dimensional (2D) transition metal nanomaterials, including transition metal chalcogenides (TMCs) and transition metal oxides (TMOs), are receiving growing interest for their use in biosensing applications based on such unique properties as high surface area and fluorescence quenching abilities. Meanwhile, nucleic acid probes based on Watson-Crick base-pairing rules are also being widely applied in biosensing based on their excellent recognition capability. In particular, the emergence of functional nucleic acids in the 1980s, especially aptamers, has substantially extended the recognition capability of nucleic acids to various targets, ranging from small organic molecules and metal ions to proteins and cells. Based on π-π stacking interaction between transition metal nanosheets and nucleic acids, biosensing systems can be easily assembled. Therefore, the combination of 2D transition metal nanomaterials and nucleic acids brings intriguing opportunities in bioanalysis and biomedicine. In this review, we summarize recent advances of nucleic acid-functionalized transition metal nanosheets in biosensing applications. The structure and properties of 2D transition metal nanomaterials are first discussed, emphasizing the interaction between transition metal nanosheets and nucleic acids. Then, the applications of nucleic acid-functionalized transition metal nanosheet-based biosensors are discussed in the context of different signal transducing mechanisms, including optical and electrochemical approaches. Finally, we provide our perspectives on the current challenges and opportunities in this promising field. Copyright © 2016 Elsevier B.V. All rights reserved.

  3. Hydrogen sensor based on palladium-yttrium alloy nanosheet

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Boyi [Queensland Micro- and Nanotechnology Centre, Griffith University, Nathan, QLD 4111 (Australia); Zhu, Yong, E-mail: y.zhu@griffith.edu.au [Queensland Micro- and Nanotechnology Centre, Griffith University, Nathan, QLD 4111 (Australia); Chen, Youping; Song, Han; Huang, Pengcheng [School of Mechanical Science and Engineering, Huazhong University of Science and Technology, Wuhan, 430074 (China); Dao, Dzung Viet [Queensland Micro- and Nanotechnology Centre, Griffith University, Nathan, QLD 4111 (Australia)

    2017-06-15

    This paper presents a hydrogen sensor based on palladium-yttrium (Pd-Y) alloy nanosheet. Zigzag-shaped Pd-Y nanosheet with a thickness of 19.3 nm was deposited on a quartz substrate by using an ultrahigh-vacuum magnetron sputtering system and shadow mask. The atomic ratio of palladium to yttrium in the nanosheet was 0.92/0.08. The fabrication process was simple and low-cost, and the sensor can be mass-produced. The experimental results show the sensor has a superior sensitivity, reversibility, and reproducibility. The resistive-based hydrogen detection mechanism in this research is much simpler and more compact compared to the optical-based detection method. - Highlights: • Pd-Y sensing element was fabricated using a magnetron sputtering system and shadow mask. • The Pd-Y compound consisted of 92% Pd and 8% Y. • The fabrication process was simple, low-cost, and mass-production compatible. • The sensor showed superior sensitivity, reversibility, and reproducibility to hydrogen gas. • The device is more compact than the optical-based counterpart.

  4. Hydrogen sensor based on palladium-yttrium alloy nanosheet

    International Nuclear Information System (INIS)

    Wang, Boyi; Zhu, Yong; Chen, Youping; Song, Han; Huang, Pengcheng; Dao, Dzung Viet

    2017-01-01

    This paper presents a hydrogen sensor based on palladium-yttrium (Pd-Y) alloy nanosheet. Zigzag-shaped Pd-Y nanosheet with a thickness of 19.3 nm was deposited on a quartz substrate by using an ultrahigh-vacuum magnetron sputtering system and shadow mask. The atomic ratio of palladium to yttrium in the nanosheet was 0.92/0.08. The fabrication process was simple and low-cost, and the sensor can be mass-produced. The experimental results show the sensor has a superior sensitivity, reversibility, and reproducibility. The resistive-based hydrogen detection mechanism in this research is much simpler and more compact compared to the optical-based detection method. - Highlights: • Pd-Y sensing element was fabricated using a magnetron sputtering system and shadow mask. • The Pd-Y compound consisted of 92% Pd and 8% Y. • The fabrication process was simple, low-cost, and mass-production compatible. • The sensor showed superior sensitivity, reversibility, and reproducibility to hydrogen gas. • The device is more compact than the optical-based counterpart.

  5. Metallic molybdenum disulfide nanosheet-based electrochemical actuators

    Science.gov (United States)

    Acerce, Muharrem; Akdoğan, E. Koray; Chhowalla, Manish

    2017-09-01

    Actuators that convert electrical energy to mechanical energy are useful in a wide variety of electromechanical systems and in robotics, with applications such as steerable catheters, adaptive wings for aircraft and drag-reducing wind turbines. Actuation systems can be based on various stimuli, such as heat, solvent adsorption/desorption, or electrochemical action (in systems such as carbon nanotube electrodes, graphite electrodes, polymer electrodes and metals). Here we demonstrate that the dynamic expansion and contraction of electrode films formed by restacking chemically exfoliated nanosheets of two-dimensional metallic molybdenum disulfide (MoS2) on thin plastic substrates can generate substantial mechanical forces. These films are capable of lifting masses that are more than 150 times that of the electrode over several millimetres and for hundreds of cycles. Specifically, the MoS2 films are able to generate mechanical stresses of about 17 megapascals—higher than mammalian muscle (about 0.3 megapascals) and comparable to ceramic piezoelectric actuators (about 40 megapascals)—and strains of about 0.6 per cent, operating at frequencies up to 1 hertz. The actuation performance is attributed to the high electrical conductivity of the metallic 1T phase of MoS2 nanosheets, the elastic modulus of restacked MoS2 layers (2 to 4 gigapascals) and fast proton diffusion between the nanosheets. These results could lead to new electrochemical actuators for high-strain and high-frequency applications.

  6. Designer Shape Anisotropy on Transition-Metal-Dichalcogenide Nanosheets.

    Science.gov (United States)

    Martella, Christian; Mennucci, Carlo; Lamperti, Alessio; Cappelluti, Emmanuele; de Mongeot, Francesco Buatier; Molle, Alessandro

    2018-03-01

    MoS 2 and generally speaking, the wide family of transition-metal dichalcogenides represents a solid nanotechnology platform on which to engineer a wealth of new and outperforming applications involving 2D materials. An even richer flexibility can be gained by extrinsically inducing an in-plane shape anisotropy of the nanosheets. Here, the synthesis of anisotropic MoS 2 nanosheets is proposed as a prototypical example in this respect starting from a highly conformal chemical vapor deposition on prepatterend substrates and aiming at the more general purpose of tailoring anisotropy of 2D nanosheets by design. This is envisioned to be a suitable configuration for strain engineering as far as strain can be spatially redistributed in morphologically different regions. With a similar approach, both the optical and electronic properties of the 2D transition-metal dichalcogenides can be tailored over macroscopic sample areas in a self-organized fashion, thus paving the way for new applications in the field of optical metasurfaces, light harvesting, and catalysis. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  7. Development of a dielectric ceramic based on diatomite-titania. Part one: powder preparation and sintering study

    Directory of Open Access Journals (Sweden)

    Tavares Elcio Correia de Souza

    1997-01-01

    Full Text Available This work presents powder preparation and sintering experiments of a mixture diatomite-titania. X-ray diffraction, DTA, TGA as well as chemical and microstructural analyses were made. The sintering process was investigated as a function of sintering temperature and time, mass variation, linear shrinkage and activation energy. The results show that sintering of diatomite-titania could be described by a viscous flow mechanism.

  8. Rational design of hierarchically porous birnessite-type manganese dioxides nanosheets on different one-dimensional titania-based nanowires for high performance supercapacitors

    KAUST Repository

    Zhang, Yu Xin; Kuang, Min; Hao, Xiao Dong; Liu, Yan; Huang, Ming; Guo, Xiao Long; Yan, Jing; Han, Gen Quan; Li, Jing

    2014-01-01

    asymmetric supercapacitor, while maintaining desirable cycling stability. Indeed, the pseudocapacitive difference is related to the substrates, unique structure and surface area. Especially, the anatase/TiO2 (B) mixed-phase system can provide good electronic

  9. Activity of nanosized titania synthesized from thermal decomposition of titanium (IV n-butoxide for the photocatalytic degradation of diuron

    Directory of Open Access Journals (Sweden)

    Jitlada Klongdee, Wansiri Petchkroh, Kosin Phuempoonsathaporn, Piyasan Praserthdam, Alisa S. Vangnai and Varong Pavarajarn

    2005-01-01

    Full Text Available Nanoparticles of anatase titania were synthesized by the thermal decomposition of titanium (IV n-butoxide in 1,4-butanediol. The powder obtained was characterized by various characterization techniques, such as XRD, BET, SEM and TEM, to confirm that it was a collection of single crystal anatase with particle size smaller than 15 nm. The synthesized titania was employed as catalyst for the photodegradation of diuron, a herbicide belonging to the phenylurea family, which has been considered as a biologically active pollutant in soil and water. Although diuron is chemically stable, degradation of diuron by photocatalyzed oxidation was found possible. The conversions achieved by titania prepared were in the range of 70–80% within 6 h of reaction, using standard UV lamps, while over 99% conversion was achieved under solar irradiation. The photocatalytic activity was compared with that of the Japanese Reference Catalyst (JRC-TIO-1 titania from the Catalysis Society of Japan. The synthesized titania exhibited higher rate and efficiency in diuron degradation than reference catalyst. The results from the investigations by controlling various reaction parameters, such as oxygen dissolved in the solution, diuron concentration, as well as light source, suggested that the enhanced photocatalytic activity was the result from higher crystallinity of the synthesized titania.

  10. Mixed conductivity, structural and microstructural characterization of titania-doped yttria tetragonal zirconia polycrystalline/titania-doped yttria stabilized zirconia composite anode matrices

    International Nuclear Information System (INIS)

    Colomer, M.T.; Maczka, M.

    2011-01-01

    Taking advantage of the fact that TiO 2 additions to 8YSZ cause not only the formation of a titania-doped YSZ solid solution but also a titania-doped YTZP solid solution, composite materials based on both solutions were prepared by solid state reaction. In particular, additions of 15 mol% of TiO 2 give rise to composite materials constituted by 0.51 mol fraction titania-doped yttria tetragonal zirconia polycrystalline and 0.49 mol fraction titania-doped yttria stabilized zirconia (0.51TiYTZP/0.49TiYSZ). Furthermore, Y 2 (Ti 1-y Zr y ) 2 O 7 pyrochlore is present as an impurity phase with y close to 1, according to FT-Raman results. Lower and higher additions of titania than that of 15 mol%, i.e., x=0, 5, 10, 20, 25 and 30 mol% were considered to study the evolution of 8YSZ phase as a function of the TiO 2 content. Furthermore, zirconium titanate phase (ZrTiO 4 ) is detected when the titania content is equal or higher than 20 mol% and this phase admits Y 2 O 3 in solid solution according to FE-SEM-EDX. The 0.51TiYTZP/0.49TiYSZ duplex material was selected in this study to establish the mechanism of its electronic conduction under low oxygen partial pressures. In the pO 2 range from 0.21 to 10 -7.5 atm. the conductivity is predominantly ionic and constant over the range and its value is 0.01 S/cm. The ionic plus electronic conductivity is 0.02 S/cm at 1000 o C and 10 -12.3 atm. Furthermore, the onset of electronic conductivity under reducing conditions exhibits a -1/4 pO 2 dependence. Therefore, it is concluded that the n-type electronic conduction in the duplex material can be due to a small polaron-hopping between Ti 3+ and Ti 4+ . -- Graphical abstract: FE-SEM micrograph of a polished and thermal etched surface of a Ti-doped YTZP/Ti-doped YSZ composite material. Display Omitted Research highlights: → Ti-doped YTZP/Ti-doped YSZ composite materials are mixed conductors under low partial pressures. → From 5 mol% of TiO 2 , Y 2 (Ti 1-y ,Zr y ) 2 O 7 pyrochlore is

  11. Nanostructure of highly aromatic graphene nanosheets -- From optoelectronics to electrochemical energy storage applications

    Science.gov (United States)

    Biswas, Sanjib

    The exceptional electrical properties along with intriguing physical and chemical aspects of graphene nanosheets can only be realized by nanostructuring these materials through the homogeneous and orderly distribution of these nanosheets without compromising the aromaticity of the native basal plane. Graphene nanosheets prepared by direct exfoliation as opposed to the graphene oxide route are necessary in order to preserve the native chemical properties of graphene basal planes. This research has been directed at optimally combining the diverse physical and chemical aspects of graphene nanosheets such as particle size, surface area and edge chemistry to fabricate nanostructured architectures for optoelectronics and high power electrochemical energy storage applications. In the first nanostructuring effort, a monolayer of these ultrathin, highly hydrophobic graphene nanosheets was prepared on a large area substrate via self-assembly at the liquid-liquid interface. Driven by the minimization of interfacial energy these planar graphene nanosheets produce a close packed monolayer structure at the liquid-liquid interface. The resulting monolayer film exhibits high electrical conductivity of more than 1000 S/cm and an optical transmission of more than 70-80% between wavelengths of 550 nm and 2000 nm making it an ideal candidate for optoelectronic applications. In the second part of this research, nanostructuring was used to create a configuration suitable for supercapacitor applications. A free standing, 100% binder free multilayer, flexible film consisting of monolayers of graphene nanosheets was prepared by utilizing the van der Waals forces of attraction between the basal plans of the graphene nanosheets coupled with capillary driven and drying-induced collapse. A major benefit in this approach is that the graphene nanosheet's attractive physical and chemical characteristics can be synthesized into an architecture consisting of large and small nanosheets to create an

  12. Recent Applications of 2D Inorganic Nanosheets for Emerging Energy Storage System.

    Science.gov (United States)

    Oh, Seung Mi; Patil, Sharad B; Jin, Xiaoyan; Hwang, Seong-Ju

    2018-04-03

    Among many types of nanostructured inorganic materials, highly anisotropic 2D nanosheets provide unique advantages in designing and synthesizing efficient electrode and electrocatalyst materials for novel energy storage technologies. 2D inorganic nanosheets boast lots of unique characteristics such as high surface area, short ion diffusion path, tailorable compositions, and tunable electronic structures. These merits of 2D inorganic nanosheets render them promising candidate materials as electrodes for diverse secondary batteries and supercapacitors, and electrocatalysts. A wide spectrum of examples is presented for inorganic nanosheet-based electrodes and electrocatalysts. Future perspectives in research about 2D nanosheet-based functional materials are discussed to provide insight for the development of next-generation energy storage systems using 2D nanostructured materials. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. Nanosheets of Nonlayered Aluminum Metal-Organic Frameworks through a Surfactant-Assisted Method

    KAUST Repository

    Pustovarenko, Alexey

    2018-05-18

    During the last decade, the synthesis and application of metal-organic framework (MOF) nanosheets has received growing interest, showing unique performances for different technological applications. Despite the potential of this type of nanolamellar materials, the synthetic routes developed so far are restricted to MOFs possessing layered structures, limiting further development in this field. Here, a bottom-up surfactant-assisted synthetic approach is presented for the fabrication of nanosheets of various nonlayered MOFs, broadening the scope of MOF nanosheets application. Surfactant-assisted preorganization of the metallic precursor prior to MOF synthesis enables the manufacture of nonlayered Al-containing MOF lamellae. These MOF nanosheets are shown to exhibit a superior performance over other crystal morphologies for both chemical sensing and gas separation. As revealed by electron microscopy and diffraction, this superior performance arises from the shorter diffusion pathway in the MOF nanosheets, whose 1D channels are oriented along the shortest particle dimension.

  14. Ambipolar thermoelectric power of chemically-exfoliated RuO2 nanosheets

    Science.gov (United States)

    Kim, Jeongmin; Yoo, Somi; Moon, Hongjae; Kim, Se Yun; Ko, Dong-Su; Roh, Jong Wook; Lee, Wooyoung

    2018-01-01

    The electrical conductivity and Seebeck coefficient of RuO2 nanosheets are enhanced by metal nanoparticle doping using Ag-acetate solutions. In this study, RuO2 monolayer and bilayer nanosheets exfoliated from layered alkali metal ruthenates are transferred to Si substrates for device fabrication, and the temperature dependence of their conductivity and Seebeck coefficients is investigated. For pristine RuO2 nanosheets, the sign of the Seebeck coefficient changes with temperature from 350-450 K. This indicates that the dominant type of charge carrier is dependent on the temperature, and the RuO2 nanosheets show ambipolar carrier transport behavior. By contrast, the sign of the Seebeck coefficient for Ag nanoparticle-doped RuO2 nanosheets does not change with temperature, indicating that the extra charge carriers from metal nanoparticles promote n-type semiconductor behavior.

  15. Suspended HOPG nanosheets for HOPG nanoresonator engineering and new carbon nanostructure synthesis

    International Nuclear Information System (INIS)

    Rose, F; Debray, A; Martin, P; Fujita, H; Kawakatsu, H

    2006-01-01

    Suspended highly oriented pyrolytic graphite (HOPG) nanosheets (10-300 nm thick) were created by direct mechanical cleavage of a bulk HOPG crystal onto silicon micropillars and microtracks. We show that suspended HOPG nanosheets can be used to engineer HOPG nanoresonators such as membranes, bridges, and cantilevers as thin as 28 carbon atom layers. We measured by Doppler laser heterodyne interferometry that the discrete vibration modes of an HOPG nanosheet membrane and the resonance frequency of a FIB-created HOPG microcantilever lie in the MHz frequency regime. Moreover, a new carbon nanostructure, named 'nanolace', was synthesized by focused ion beam (FIB) sputtering of suspended HOPG nanosheets. Graphite nanosheets suspended on micropillars were eroded by a FIB to create self-oriented pseudo-periodical ripples. Additional sputtering and subsequent milling of these ripples led to the formation of honeycomb-like shaped nanolaces suspended and linked by ribbons

  16. Characterization of vanadium-doped mesoporous titania and its adsorption of gaseous benzene

    Energy Technology Data Exchange (ETDEWEB)

    Nguyen-Phan, Thuy-Duong; Song, Myoung Bock; Yun, Hyunran; Kim, Eui Jung; Oh, Eun-Suok [School of Chemical Engineering and Bioengineering, University of Ulsan, Mugeo-dong, Nam-gu, Ulsan 680-749 (Korea, Republic of); Shin, Eun Woo, E-mail: ewshin@mail.ulsan.ac.kr [School of Chemical Engineering and Bioengineering, University of Ulsan, Mugeo-dong, Nam-gu, Ulsan 680-749 (Korea, Republic of)

    2011-01-01

    A series of vanadium-doped mesoporous titania with different metal contents was synthesized in the study via a sol-gel process with the assistance of a dodecylamine surfactant. The existence of vanadium ions not only suppressed crystallization and sintering but also enhanced the porosity of the mesoporous TiO{sub 2}. Varying the vanadium concentration led to significant changes in the chemical oxidation state of each component. The presence of metal dopants significantly improved the removal efficiency of benzene and the doping the titania with 5 mol% vanadium removed the most benzene, regardless of the adsorption temperature. The adsorption behavior was elucidated by the specific surface area, the interactions between surface hydroxyl groups and the {pi}-electrons of benzene, and the formation of {sigma}-bonding and d-{pi}* back-donation between the adsorbent and organic compounds.

  17. Basic Principle of Advanced Oxidation Technology : Hybrid Technology Based on Ozone and Titania

    International Nuclear Information System (INIS)

    Widdi Usada; Agus Purwadi

    2007-01-01

    One of problems in health environment is organic liquid waste from many pollutant resources. Environmental friendly technology for degrading this waste is ozone which produced by plasma discharge technology, but its capability is limited. However, it is needed a new environmental friendly technology which has stronger capability. This new technology is so called advanced oxidation technology. Advanced oxidation technology is a hybrid of ozone, peroxide, UV light and photo catalyst. In this paper, it is introduced basic principle of hybrid of ozone and titania photo catalyst semiconductor. The capability of organic liquid degradation will be stronger because there is new radical which is produced by chemical reaction between electron-hole pair from photo catalyst titania and water or oxygen. This new radical then degrades this organic pollutant. This technology is used to degrade phenol. (author)

  18. Enhanced visible-light activity of titania via confinement inside carbon nanotubes

    KAUST Repository

    Chen, Wei

    2011-09-28

    Titania confined inside carbon nanotubes (CNTs) was synthesized using a restrained hydrolysis method. Raman spectra and magnetic measurements using a SQUID magnetometer suggested the formation of remarkable oxygen vacancies over the encapsulated TiO 2 in comparison with nanoparticles dispersed on the outer surface of CNTs, extending the photoresponse of TiO 2 from the UV to the visible-light region. The CNT-confined TiO 2 exhibited improved visible-light activity in the degradation of methylene blue (MB) relative to the outside titania and commercial P25, which is attributed to the modification of the electronic structure of TiO 2 induced by the unique confinement inside CNTs. These results provide further insight into the effect of confinement within CNTs, and the composites are expected to be promising for applications in visible-light photocatalysis. © 2011 American Chemical Society.

  19. The detection of improvised nonmilitary peroxide based explosives using a titania nanotube array sensor

    International Nuclear Information System (INIS)

    Banerjee, Subarna; Mohapatra, Susanta K; Misra, Mano; Mishra, Indu B

    2009-01-01

    There is a critical need to develop an efficient, reliable and highly selective sensor for the detection of improvised nonmilitary explosives. This paper describes the utilization of functionalized titania nanotube arrays for sensing improvised organic peroxide explosives such as triacetone triperoxide (TATP). TATP forms complexes with titania nanotube arrays (prepared by anodization and sensitized with zinc ions) and thus affects the electron state of the nanosensing device, which is signaled as a change in current of the overall nanotube material. The response is rapid and a signal of five to eight orders of magnitude is observed. These nanotube array sensors can be used as hand-held miniaturized devices as well as large scale portable units for military and homeland security applications.

  20. Structural transformation of nanocrystalline titania by sol-gel and the growth kinetics of crystallites

    International Nuclear Information System (INIS)

    Hu Linhua; Dai Songyuan; Wang Kongjia

    2002-05-01

    Structural transformation of nanocrystalline titania prepared by sol-gel with hydrolysis precursor titanium isopropoxide was investigated. At the same time, the growth kinetics of titania powders was also studied here. It was found that the grain size of the powders increased slowly with autoclave heating temperature up to 230 degree C, when hydrolysis pH was 0.9, but grew rapidly when heating temperature was higher that 230 degree C. The activation energies for growth of anatase crystallites in two temperature regions were calculated to be 18.5 kJ/mol and 59.7 kJ/mol respectively. The X-ray diffraction results show that the transformation from anatase phase to rutile phase starts at 230 degree C and structural transformation finished when temperature raises to 270 degree C, which is a temperature much more lower than that of the transformation by conventional literature reports

  1. UV-Irradiated Photocatalytic Degradation of Nitrobenzene by Titania Binding on Quartz Tube

    Directory of Open Access Journals (Sweden)

    Thou-Jen Whang

    2012-01-01

    Full Text Available A new method for UV-irradiated degradation of nitrobenzene by titania photocatalysts was proposed, titania nanoparticles were coated on a quartz tube through the introduction of tetraethyl orthosilicate into the matrix. The dependence of nitrobenzene photodegradation on pH, temperature, concentration, and air feeding was discussed, and the physical properties such as the activation energy, entropy, enthalpy, adsorption constant, and rate constant were acquired by conducting the reactions in a variety of experimental conditions. The optimum efficiency of the photodegradation with the nitrobenzene residue as low as 8.8% was achieved according to the experimental conditions indicated. The photodegradation pathways were also investigated through HPLC, GC/MS, ion chromatography (IC, and chemical oxygen demand (COD analyses.

  2. Fabrication of porous silver/titania composite hollow spheres with enhanced photocatalytic performance

    International Nuclear Information System (INIS)

    Li, Sa; Halperin, Shakked O.; Wang, Chang-An

    2015-01-01

    Silver/titania composite hollow spheres were first synthesized through an in-situ chemical reaction using functional-grouped carbon spheres as the template in this study. The prepared samples were characterized through an X-ray diffraction, N 2 adsorption–desorption, scanning electron microscopy, transmission electron microscopy and UV–Vis spectrophotometer. The photocatalytic activity of as-prepared samples was evaluated by photocatalytic decolorization of Methyl orange (MO) aqueous solution at ambient temperature under UV light. We found a structure with an optimal Ag:TiO 2 composition that exhibited a photodecomposition rate constant more than twice as high as titania hollow spheres lacking silver, and over three times higher than a commercial photocatalyst. - Highlights: • Ag/silver composites. • Hollow spheres. • Photocatalysis enhancement

  3. Hydrothermal crystallization of amorphous titania films deposited using low temperature atomic layer deposition

    Energy Technology Data Exchange (ETDEWEB)

    Mitchell, D.R.G. [Institute of Materials Engineering, ANSTO, PMB 1, Menai, NSW 2234 (Australia)], E-mail: drm@ansto.gov.au; Triani, G.; Zhang, Z. [Institute of Materials Engineering, ANSTO, PMB 1, Menai, NSW 2234 (Australia)

    2008-10-01

    A two stage process (atomic layer deposition, followed by hydrothermal treatment) for producing crystalline titania thin films at temperatures compatible with polymeric substrates (< 130 deg. C) has been assessed. Titania thin films were deposited at 80 deg. C using atomic layer deposition. They were extremely flat, uniform and almost entirely amorphous. They also contained relatively high levels of residual Cl from the precursor. After hydrothermal treatment at 120 deg. C for 1 day, > 50% of the film had crystallized. Crystallization was complete after 10 days of hydrothermal treatment. Crystallization of the film resulted in the formation of coarse grained anatase. Residual Cl was completely expelled from the film upon crystallization. As a result of the amorphous to crystalline transformation voids formed at the crystallization front. Inward and lateral crystal growth resulted in voids being localized to the film/substrate interface and crystallite perimeters resulting in pinholing. Both these phenomena resulted in films with poor adhesion and film integrity was severely compromised.

  4. Gas sensor based on photoconductive electrospun titania nanofibres operating at room temperature

    Energy Technology Data Exchange (ETDEWEB)

    Zampetti, E., E-mail: emiliano.zampetti@artov.imm.cnr.it; Macagnano, A.; Bearzotti, A. [Consiglio Nazionale delle Ricerche, Istituto per la Microelettronica e Microsistemi (CNR IMM) (Italy)

    2013-04-15

    An important drawback of semiconductor gas sensors is their operating temperature that needs the use of heaters. To overcome this problem a prototyping sensor using titania nanofibres (with an average diameter of 50 nm) as sensitive membrane were fabricated by electrospinning directly on the transducer of the sensor. Exploiting the effect of titania photoconductivity, resistance variations upon gas interaction under continuous irradiation of ultra violet light were measured at room temperature. The resistive sensor response was evaluated towards ammonia, nitrogen dioxide and humidity. The sensor exhibited a higher response to ammonia than to nitrogen dioxide, especially for concentrations larger than 100 ppb. For 200 ppb of ammonia and nitrogen dioxide, the responses were {approx}2.8 and 1.5 %, respectively.

  5. The detection of improvised nonmilitary peroxide based explosives using a titania nanotube array sensor.

    Science.gov (United States)

    Banerjee, Subarna; Mohapatra, Susanta K; Misra, Mano; Mishra, Indu B

    2009-02-18

    There is a critical need to develop an efficient, reliable and highly selective sensor for the detection of improvised nonmilitary explosives. This paper describes the utilization of functionalized titania nanotube arrays for sensing improvised organic peroxide explosives such as triacetone triperoxide (TATP). TATP forms complexes with titania nanotube arrays (prepared by anodization and sensitized with zinc ions) and thus affects the electron state of the nanosensing device, which is signaled as a change in current of the overall nanotube material. The response is rapid and a signal of five to eight orders of magnitude is observed. These nanotube array sensors can be used as hand-held miniaturized devices as well as large scale portable units for military and homeland security applications.

  6. Impedance response of carbon nanotube-titania electrodes dried under modified gravity

    International Nuclear Information System (INIS)

    Ordenana-Martinez, A.S.; Rincon, M.E.; Vargas, M.; Ramos, E.

    2011-01-01

    The synthesis and impregnation of porous titania films by commercial multiwalled carbon nanotubes and nanotube rich carbon soot are reported. The samples were dried under terrestrial gravity g and in a centrifuge accelerated at 13 g. X-Ray Diffraction data and Scanning Electron Microscopy images indicated differences in the crystal structure and tendency to agglomeration in both carbon types, providing different microstructures of functionally graded electrodes. Drying the samples in a centrifuge helps to the distribution of carbon nanoparticles and to the decrement of the impedance at the contact interfaces. The presence of titania weakens the differences observed in both drying protocols, but not the differences due to the carbon source. Superior capacitance and network conductivity were observed in electrodes based on commercial carbon nanotubes.

  7. Effect of titania on the characteristics of a Tin-Platinum catalyst

    Energy Technology Data Exchange (ETDEWEB)

    Morales-Gil, P., E-mail: moralesp@imp.mx; Nava, N. [Instituto Mexicano del Petróleo (Mexico); Baggio-Saitovitch, E. [Centro Brasileiro de Pesquisas Físicas (Brazil)

    2015-06-15

    Pt-Sn bimetallic catalysts dispersed on alumina are commonly used for reforming and dehydrogenation reactions. In this research work, Pt and Sn were supported on titania. The resulting interactions between the components in the prepared samples, before and after treatment with hydrogen, were studied by Mössbauer spectroscopy, X-ray diffraction and Rietveld refinement. The results show the presence of Pt and SnO{sub 2} after calcinations. After the reduction process, metallic Pt, PtSn, and Pt{sub 3}Sn alloys were identified. The Rietveld refinement analysis shows that some Ti{sup 4+} atoms were replaced by Sn{sup 4+} atoms in the titania structure. Finally, the Mössbauer spectroscopy and X-ray diffraction results indicate that metallic platinum and SnO{sub 2} are encapsulated by a TiOx layer.

  8. Photocatalytic inactivation of hospital-associated bacteria using titania nanoparticle coated textiles

    International Nuclear Information System (INIS)

    Tahir, T.; Qazi, I.A.; Hashmi, I.; Baig, M.A.

    2017-01-01

    Modification in hospital textiles to include disinfection properties may help in the reduction of nosocomial infections. In this study, antibacterial properties were imparted to cotton fabric by modifying it with pure and (1%) silver doped titania nanoparticles. The nanoparticles were prepared by liquid impregnation process and characterized using X-ray Diffraction (XRD) spectroscopy, Scanning Electron Microscopy (SEM) and Energy Dispersive Spectroscopy (EDS). These nanoparticles were attached to cotton fabric using a cross linking agent succinic acid. Samples were washed at three different temperatures (30, 60 and 90 degree C), with and without detergent and for different number of cycles to test the durability of nanoparticles to the fabric. Scanning Electron Microscopy (SEM) was used for studying surface topography of fabric. Energy Dispersive X-ray fluorescence (ED-XRF) spectrometer was used to detect the titanium present on the fabric. Catalytic spectrophotometry using UV/visible spectrophotometer was used to determine titania concentration in washing effluent. The antibacterial activity of the modified fabric was examined against Methicillin Resistant Staphylococcus aureus (MRSA) under UV and fluorescent light. The maximum durability of titania nanoparticles to the fabric was retained after washing without detergent at 30 degree C. The overall results of durability testing showed that coating of nanoparticles on fabric was durable against washing at various conditions, hence suitable from an environmental perspective. Antibacterial testing showed 100% photocatalytic inactivation of MRSA after 4 and 24 h of UV and fluorescent light exposure respectively. The potential of using such textiles in hospital environment was validated through the use of modified bed linen in a local hospital for a period of three days consecutively. The viable count indicated the reduced bacterial contamination on nano-coated fabric as compared to uncoated fabric. Bed linen, curtains

  9. Super/Subcritical Fluid Extractions for Preparation of the Crystalline Titania

    Czech Academy of Sciences Publication Activity Database

    Matějová, Lenka; Cajthaml, Tomáš; Matěj, Z.; Benada, Oldřich; Klusoň, Petr; Šolcová, Olga

    2010-01-01

    Roč. 52, č. 2 (2010), s. 215-221 ISSN 0896-8446 R&D Projects: GA ČR GP104/09/P290; GA ČR GA104/09/0694 Institutional research plan: CEZ:AV0Z40720504; CEZ:AV0Z50200510 Keywords : titania * supercritical fluid extraction * pressurised fluid extraction Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 2.986, year: 2010

  10. Induction plasma-sprayed photocatalytically active titania coatings and their characterisation by micro-Raman spectroscopy

    Czech Academy of Sciences Publication Activity Database

    Burlacov, I.; Jirkovský, Jaromír; Muller, M.; Heimann, R. B.

    2006-01-01

    Roč. 201, 1-2 (2006), s. 255-264 ISSN 0257-8972 Grant - others:European Communities(XE) EVKI-2002-30025 Institutional research plan: CEZ:AV0Z40400503 Source of funding: R - rámcový projekt EK Keywords : titania (anatase) coatings * induction plasma spraying * suspension plasma spraying * Raman spectroscopy Subject RIV: CG - Electrochemistry Impact factor: 1.559, year: 2006

  11. Mn-Zn ferrite nanoparticles with silica and titania coatings: synthesis, transverse relaxivity and cytotoxicity

    Czech Academy of Sciences Publication Activity Database

    Kaman, Ondřej; Kuličková, Jarmila; Maryško, Miroslav; Veverka, Pavel; Herynek, V.; Havelek, R.; Královec, K.; Kubániová, D.; Kohout, J.; Dvořák, P.; Jirák, Zdeněk

    2017-01-01

    Roč. 53, č. 11 (2017), s. 1-8, č. článku 5300908. ISSN 0018-9464 R&D Projects: GA ČR GA16-04340S Institutional support: RVO:68378271 Keywords : amorphous titania * silica * magnetic nanoparticles * Mn-Zn ferrite * transverse relaxivity * cytotoxicity Subject RIV: BM - Solid Matter Physics ; Magnetism OBOR OECD: Condensed matter physics (including formerly solid state physics, supercond.) Impact factor: 1.243, year: 2016

  12. PVA assisted low temperature anatase to rutile phase transformation (ART) and properties of titania nanoparticles

    International Nuclear Information System (INIS)

    Mondal, Shrabani; Madhuri, Rashmi; Sharma, Prashant K.

    2015-01-01

    Anatase to rutile phase transformation (ART) of titania nanoparticles is observed at very low temperature (180 °C) just by introducing polyvinyl alcohol (PVA) during co-precipitation followed by hydrothermal synthesis. The detailed investigations pertaining to the structural, optical and electrochemical properties of the nanosized titania and titania/PVA nanohybrid has been carried out. The crystallite size and crystal structure is confirmed using X-ray diffraction (XRD). Transmission electron microscopic (TEM) image reveals formation of spherical NPs in both the cases. Identification of functional groups is done using Fourier transform infrared spectroscopy (FTIR). The photoluminescence studies showed that emission slightly shifts towards higher wavelength side with remarkable decrease in intensity for TiO 2 /PVA nanocomposite (rutile samples). The remarkable decrease in PL intensity in TiO 2 /PVA nanocomposite (rutile samples) is explained considering the surface passivation during growth process. Ion transportation is monitored via Cyclic voltammetric (CV) and Electrochemical Impedance Spectroscopy (EIS) measurements. A significant enhancement of peak cathodic current in case of nanocomposite modified electrode is observed. It is assumed that TiO 2 /PVA (rutile) nanoparticles provided the conducting path for the electrons and hence enhanced the electrochemical reaction. - Graphical abstract: Present work reports anatase to rutile phase transformation (ART) of titania nanoparticles at very low temperature (180 °C) just by introducing polyvinyl alcohol (PVA) during co-precipitation followed by hydrothermal synthesis. - Highlights: • Low temperature phase transformation of TiO 2 nanoparticles from anatase to rutile. • Role of PVA in phase transformation. • Synthesis of spherical shaped uniformly distributed PVA capped TiO 2 NPs. • Explained the charge transfer process among anatase to rutile phase transformation via luminescence studies. • Enhanced

  13. Titania nanotubes with adjustable dimensions for drug reservoir sites and enhanced cell adhesion

    International Nuclear Information System (INIS)

    Çalışkan, Nazlı; Bayram, Cem; Erdal, Ebru; Karahaliloğlu, Zeynep; Denkbaş, Emir Baki

    2014-01-01

    This study aims to generate a bactericidal agent releasing surface via nanotube layer on titanium metal and to investigate how aspect ratio of nanotubes affects drug elution time and cell proliferation. Titania nanotube layers were generated on metal surfaces by anodic oxidation at various voltage and time parameters. Gentamicin loading was carried out via simple pipetting and the samples were tested against S. aureus for the efficacy of the applied modification. Drug releasing time and cell proliferation were also tested in vitro. Titania nanotube layers with varying diameters and lengths were prepared after anodization and anodizing duration was found as the most effective parameter for amount of loaded drug and drug releasing time. Drug elution lasted up to 4 days after anodizing for 80 min of the samples, whereas release completed in 24 h when the samples were anodized for 20 min. All processed samples had bactericidal properties against S. aureus organism except unmodified titanium, which was also subjected to drug incorporation step. The anodization also enhanced water wettability and cell adhesion results. Anodic oxidation is an effective surface modification to enhance tissue–implant interactions and also resultant titania layer can act as a drug reservoir for the release of bactericidal agents. The use of implants as local drug eluting devices is promising but further in vivo testing is required. - Highlights: • Titanium surfaces were anodized and a nanotubular titania layer was obtained. • Drug eluting time was found to be increasing with anodizaton time. • Varying nanotube diameters has no effect in drug elution time but amount of incorporated drug

  14. Titania and zirconia binary oxides as catalysts for total oxidation of ethyl acetate and methanol decomposition

    Czech Academy of Sciences Publication Activity Database

    Tsoncheva, T.; Mileva, A.; Issa, G.; Dimitrov, M.; Kovacheva, D.; Henych, Jiří; Kormunda, M.; Scotti, N.; Slušná, Michaela; Tolasz, Jakub; Štengl, Václav

    2018-01-01

    Roč. 6, č. 2 (2018), s. 2540-2550 ISSN 2213-3437 Grant - others:AV ČR(CZ) BAS-17-13 Program:Bilaterální spolupráce Institutional support: RVO:61388980 Keywords : Effect of preparation procedure * Ethyl acetate oxidation * Methanol decomposition * Titania-zirconia binary oxides Subject RIV: CA - Inorganic Chemistry OBOR OECD: Inorganic and nuclear chemistry

  15. Titania nanotubes with adjustable dimensions for drug reservoir sites and enhanced cell adhesion

    Energy Technology Data Exchange (ETDEWEB)

    Çalışkan, Nazlı; Bayram, Cem; Erdal, Ebru; Karahaliloğlu, Zeynep; Denkbaş, Emir Baki, E-mail: denkbas@hacettepe.edu.tr

    2014-02-01

    This study aims to generate a bactericidal agent releasing surface via nanotube layer on titanium metal and to investigate how aspect ratio of nanotubes affects drug elution time and cell proliferation. Titania nanotube layers were generated on metal surfaces by anodic oxidation at various voltage and time parameters. Gentamicin loading was carried out via simple pipetting and the samples were tested against S. aureus for the efficacy of the applied modification. Drug releasing time and cell proliferation were also tested in vitro. Titania nanotube layers with varying diameters and lengths were prepared after anodization and anodizing duration was found as the most effective parameter for amount of loaded drug and drug releasing time. Drug elution lasted up to 4 days after anodizing for 80 min of the samples, whereas release completed in 24 h when the samples were anodized for 20 min. All processed samples had bactericidal properties against S. aureus organism except unmodified titanium, which was also subjected to drug incorporation step. The anodization also enhanced water wettability and cell adhesion results. Anodic oxidation is an effective surface modification to enhance tissue–implant interactions and also resultant titania layer can act as a drug reservoir for the release of bactericidal agents. The use of implants as local drug eluting devices is promising but further in vivo testing is required. - Highlights: • Titanium surfaces were anodized and a nanotubular titania layer was obtained. • Drug eluting time was found to be increasing with anodizaton time. • Varying nanotube diameters has no effect in drug elution time but amount of incorporated drug.

  16. Titania-coated manganite nanoparticles: synthesis of the shell, characterization and MRI properties

    Czech Academy of Sciences Publication Activity Database

    Jirák, Zdeněk; Kuličková, Jarmila; Herynek, Vít; Maryško, Miroslav; Koktan, Jakub; Kaman, Ondřej

    2017-01-01

    Roč. 427, Apr (2017), s. 245-250 ISSN 0304-8853 R&D Projects: GA ČR GA15-10088S; GA ČR GA16-04340S Institutional support: RVO:68378271 ; RVO:68378041 Keywords : magnetic nanoparticles * core-shell nanoparticles * titania coating * perovskite manganite * magnetic resonance imaging * transverse relaxivity Subject RIV: BM - Solid Matter Physics ; Magnetism OBOR OECD: Condensed matter physics (including formerly solid state physics, supercond.) Impact factor: 2.630, year: 2016

  17. Selective epoxidation of allylic alcohols with a titania-silica aerogel

    Energy Technology Data Exchange (ETDEWEB)

    Dusi, M.; Mallat, T.; Baiker, A. [Lab. of Technical Chemistry, Swiss Federal Inst. of Technology, ETH-Zentrum, Zuerich (Switzerland)

    1998-12-31

    An amorphous mesoporous titania-silica aerogel (20 wt%TiO{sub 2} - 80 wt% SiO{sub 2}) and tert.-butylhydroperoxide (TBHP) have been used for the epoxidation of various allylic alcohols. Allylic alcohols possessing an internal double bond were more reactive than those with a terminal C=C bond. Epoxide selectivities could be improved by addition of (basic) zeolite 4 A and NaHCO{sub 3} to the reaction mixture. (orig.)

  18. Titania Supported Co-Mn-Al Oxide Catalysts in Total Oxidation of Ethanol

    Czech Academy of Sciences Publication Activity Database

    Ludvíková, Jana; Jirátová, Květa; Klempa, Jan; Böhmová, Vlasta; Obalová, L.

    2012-01-01

    Roč. 179, č. 1 (2012), s. 164-169 ISSN 0920-5861 R&D Projects: GA ČR GAP106/10/1762; GA ČR GD203/08/H032 Institutional research plan: CEZ:AV0Z40720504; CEZ:AV0Z30130516 Keywords : mixed oxide catalysts * voc oxidation * titania Subject RIV: CI - Industrial Chemistry, Chemical Engineering Impact factor: 2.980, year: 2012

  19. Diffusion structural analysis study of titania films deposited by sol-gel technique on silica glass

    Czech Academy of Sciences Publication Activity Database

    Balek, V.; Mitsuhashi, T.; Bountseva, I.M.; Haneda, H.; Málek, Z.; Šubrt, Jan

    2003-01-01

    Roč. 26, 1-3 (2003), s. 185-189 ISSN 0928-0707. [International Workshop on Glasses, Ceramics, Hybrids and Nanocomposites from Gels /11./. Abano Terme, 16.09.2001-21.09.2001] Institutional research plan: CEZ:AV0Z4032918 Keywords : titania film * diffusion structural analysis * sol-gel Subject RIV: CA - Inorganic Chemistry Impact factor: 1.546, year: 2003

  20. Effect of titania particles on the microstructure and properties of the epoxy resin coatings on sintered NdFeB permanent magnets

    International Nuclear Information System (INIS)

    Xu, J.L.; Huang, Z.X.; Luo, J.M.; Zhong, Z.C.

    2014-01-01

    The nanometer titania particles enhanced epoxy resin composite coatings were prepared on the sintered NdFeB permanent magnets by cathodic electrophoretic deposition. The effects of titania particle concentrations on the microstructure and properties of the epoxy coatings were investigated by surface and cross-sectional morphologies observation, surface roughness and microhardness measurement, H 2 SO 4 solution immersion test, neutral salt spray test and magnetic properties measurement. The results showed that the thickness of epoxy coatings with and without the titania particles addition was about 40 μm. The titania particles could be uniformly dispersed and embedded in the epoxy matrix if the titania particles concentration was lower than 40 g/l. With increasing titania particle concentrations, the number of the particles embedded in the epoxy matrix increased and the surface roughness and microhardness of the composite coatings increased. At the same time, the weight loss of the coated samples immersed in H 2 SO 4 solution decreased and the neutral salt spray time of the coated samples prolonged. It could be concluded that the titania particles did not change the thickness of the epoxy coatings and did not deteriorate the magnetic properties of NdFeB substrates, but could greatly improve the microhardness and corrosion resistance of the epoxy coatings. - Highlights: • The titania particles enhanced epoxy resin coatings were prepared on sintered NdFeB by cathodic electrophoretic deposition. • The titania particles could be uniformly dispersed and embedded in the epoxy resin matrix. • With increasing titania concentrations, the surface roughness and the microhardness of composite coatings increased. • The addition of titania particles greatly improved the corrosion resistance of the epoxy coatings. • The composition coatings did not deteriorate the magnetic properties of NdFeB substrates

  1. Effect of titania particles on the microstructure and properties of the epoxy resin coatings on sintered NdFeB permanent magnets

    Energy Technology Data Exchange (ETDEWEB)

    Xu, J.L., E-mail: jlxu@nchu.edu.cn; Huang, Z.X.; Luo, J.M.; Zhong, Z.C., E-mail: zzhong.2006@yahoo.com.cn

    2014-04-15

    The nanometer titania particles enhanced epoxy resin composite coatings were prepared on the sintered NdFeB permanent magnets by cathodic electrophoretic deposition. The effects of titania particle concentrations on the microstructure and properties of the epoxy coatings were investigated by surface and cross-sectional morphologies observation, surface roughness and microhardness measurement, H{sub 2}SO{sub 4} solution immersion test, neutral salt spray test and magnetic properties measurement. The results showed that the thickness of epoxy coatings with and without the titania particles addition was about 40 μm. The titania particles could be uniformly dispersed and embedded in the epoxy matrix if the titania particles concentration was lower than 40 g/l. With increasing titania particle concentrations, the number of the particles embedded in the epoxy matrix increased and the surface roughness and microhardness of the composite coatings increased. At the same time, the weight loss of the coated samples immersed in H{sub 2}SO{sub 4} solution decreased and the neutral salt spray time of the coated samples prolonged. It could be concluded that the titania particles did not change the thickness of the epoxy coatings and did not deteriorate the magnetic properties of NdFeB substrates, but could greatly improve the microhardness and corrosion resistance of the epoxy coatings. - Highlights: • The titania particles enhanced epoxy resin coatings were prepared on sintered NdFeB by cathodic electrophoretic deposition. • The titania particles could be uniformly dispersed and embedded in the epoxy resin matrix. • With increasing titania concentrations, the surface roughness and the microhardness of composite coatings increased. • The addition of titania particles greatly improved the corrosion resistance of the epoxy coatings. • The composition coatings did not deteriorate the magnetic properties of NdFeB substrates.

  2. Amperometric biosensor for hydrogen peroxide based on hemoglobin entrapped in titania sol-gel film

    International Nuclear Information System (INIS)

    Yu Jiuhong; Ju Huangxian

    2003-01-01

    Hemoglobin (Hb) was entrapped in a titania sol-gel matrix and used as a mimetic peroxidase to construct a novel amperometric biosensor for hydrogen peroxide. The Hb entrapped titania sol-gel film was obtained with a vapor deposition method, which simplified the traditional sol-gel process for protein immobilization. The morphologies of both titania sol-gel and the Hb films were characterized using scanning electron microscopy (SEM) and proved to be chemically clean, porous, homogeneous. This matrix provided a biocompatible microenvironment for retaining the native structure and activity of the entrapped Hb and a very low mass transport barrier to the substrates. H 2 O 2 could be reduced by the catalysis of the entrapped hemoglobin at -300 mV without any mediator. The reagentless H 2 O 2 sensor exhibited a fast response (less than 5 s) and sensitivity as high as 1.29 mA mM -1 cm -2 . The linear range for H 2 O 2 determination was from 5.0x10 -7 to 5.4x10 -5 M with a detection limit of 1.2x10 -7 M. The apparent Michaelis-Menten constant of the encapsulated hemoglobin was calculated to be 0.18±0.02 mM. The stability of the biosensor was also evaluated

  3. In-vitro bioactivity and electrochemical behavior of polyaniline encapsulated titania nanotube arrays for biomedical applications

    Science.gov (United States)

    Agilan, P.; Rajendran, N.

    2018-05-01

    Titania nanotube arrays (TNTA) have attracted increasing attention due to their outstanding properties and potential applications in biomedical field. Fabrication of titania nanotubes on titanium surface enhances the biocompatibility. Polyaniline (PANI) is one of the best conducting polymers with remarkable corrosion resistance and reasonable biocompatibility. In this work, the corrosion resistance and biocompatibility of polyaniline encapsulated TiO2 nanotubes for orthopaedic applications were investigated. The vertically oriented, highly ordered TiO2 nanotubes were fabricated on titanium by electrochemical anodization process using fluoride containing electrolytes. The anodization parameters viz., voltage, pH, time and electrolyte concentration were optimized to get orderly arranged TNTA. Further, the conducting polymer PANI was encapsulated on TNTA by electropolymerization process to enhance the corrosion resistance. The nanostructure of the fabricated TNTA and polyaniline encapsulated titania nanotube arrays (PANI-TNTA) were investigated by HR SEM analysis. The formed phases and functional groups were find using XRD, ATR-FTIR. The hydrophilic surface of TNTA and PANI-TNTA was identified by water contact angle studies. The corrosion behavior of specimens was evaluated by electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization studies. In-vitro immersion studies were carried out in simulated body fluid solution (Hanks' solution) to evaluate the bioactivity of the TNTA and PANI-TNTA. The surface morphological studies revealed the formation of PANI on the TNTA surface. Formation of hydroxyapatite (HAp) on the surfaces of TNTA and PANI-TNTA enhanced the bioactivity and corrosion resistance.

  4. Scanning probe microscopy studies on the adsorption of selected molecular dyes on titania

    Directory of Open Access Journals (Sweden)

    Jakub S. Prauzner-Bechcicki

    2016-11-01

    Full Text Available Titanium dioxide, or titania, sensitized with organic dyes is a very attractive platform for photovoltaic applications. In this context, the knowledge of properties of the titania–sensitizer junction is essential for designing efficient devices. Consequently, studies on the adsorption of organic dyes on titania surfaces and on the influence of the adsorption geometry on the energy level alignment between the substrate and an organic adsorbate are necessary. The method of choice for investigating the local environment of a single dye molecule is high-resolution scanning probe microscopy. Microscopic results combined with the outcome of common spectroscopic methods provide a better understanding of the mechanism taking place at the titania–sensitizer interface. In the following paper, we review the recent scanning probe microscopic research of a certain group of molecular assemblies on rutile titania surfaces as it pertains to dye-sensitized solar cell applications. We focus on experiments on adsorption of three types of prototypical dye molecules, i.e., perylene-3,4,9,10-tetracarboxylic dianhydride (PTCDA, phtalocyanines and porphyrins. Two interesting heteromolecular systems comprising molecules that are aligned with the given review are discussed as well.

  5. Studies of Dye Sensitisation Kinetics and Sorption Isotherms of Direct Red 23 on Titania

    Directory of Open Access Journals (Sweden)

    Peter J. Holliman

    2008-01-01

    Full Text Available Sorption kinetics and isotherms have been measured for a commercial dye (Direct Red 23 on different samples of powdered Titania, and the data were analysed to better understand the dye sensitization process for dye sensitised solar cells (DSSCs. For the sorption kinetics, the data show rapid initial sorption (<1 hour followed by slower rate of increasing uptake between 1 and 24 hours. While higher initial concentrations of dye correspond to higher sorption overall, less dye is absorbed from higher initial dye concentrations when considered as percentage uptake. The correlation between the sorption data and model isotherms has been considered with time. The Langmuir model shows better correlations compared to the Freundlich isotherm. The dye uptake data has also been correlated with Titania characterization data (X-ray diffraction, scanning electron microscopy, BET and zero point charge analysis. Kinetic data show significantly better fits to second-order models compared to first order. This suggests that chemisorption is taking place and that the interaction between the dye sorbate and the Titania sorbent involves electron sharing to form an ester bond.

  6. Titania nanotubes with adjustable dimensions for drug reservoir sites and enhanced cell adhesion.

    Science.gov (United States)

    Çalışkan, Nazlı; Bayram, Cem; Erdal, Ebru; Karahaliloğlu, Zeynep; Denkbaş, Emir Baki

    2014-02-01

    This study aims to generate a bactericidal agent releasing surface via nanotube layer on titanium metal and to investigate how aspect ratio of nanotubes affects drug elution time and cell proliferation. Titania nanotube layers were generated on metal surfaces by anodic oxidation at various voltage and time parameters. Gentamicin loading was carried out via simple pipetting and the samples were tested against S. aureus for the efficacy of the applied modification. Drug releasing time and cell proliferation were also tested in vitro. Titania nanotube layers with varying diameters and lengths were prepared after anodization and anodizing duration was found as the most effective parameter for amount of loaded drug and drug releasing time. Drug elution lasted up to 4 days after anodizing for 80 min of the samples, whereas release completed in 24 h when the samples were anodized for 20 min. All processed samples had bactericidal properties against S. aureus organism except unmodified titanium, which was also subjected to drug incorporation step. The anodization also enhanced water wettability and cell adhesion results. Anodic oxidation is an effective surface modification to enhance tissue-implant interactions and also resultant titania layer can act as a drug reservoir for the release of bactericidal agents. The use of implants as local drug eluting devices is promising but further in vivo testing is required. Copyright © 2013 Elsevier B.V. All rights reserved.

  7. First principles study of vibrational dynamics of ceria-titania hybrid clusters

    Energy Technology Data Exchange (ETDEWEB)

    Majid, Abdul, E-mail: abdulmajid40@yahoo.com; Bibi, Maryam [University of Gujrat, Department of Physics (Pakistan)

    2017-04-15

    Density functional theory based calculations were performed to study vibrational properties of ceria, titania, and ceria-titania hybrid clusters. The findings revealed the dominance of vibrations related to oxygen when compared to those of metallic atoms in the clusters. In case of hybrid cluster, the softening of normal modes related to exterior oxygen atoms in ceria and softening/hardening of high/low frequency modes related to titania dimmers are observed. The results calculated for monomers conform to symmetry predictions according to which three IR and three Raman active modes were detected for TiO{sub 2}, whereas two IR active and one Raman active modes were observed for CeO{sub 2}. The comparative analysis indicates that the hybrid cluster CeTiO{sub 4} contains simultaneous vibrational fingerprints of the component dimmers. The symmetry, nature of vibrations, IR and Raman activity, intensities, and atomic involvement in different modes of the clusters are described in detail. The study points to engineering of CeTiO{sub 4} to tailor its properties for technological visible region applications in photocatalytic and electrochemical devices.

  8. Guided in Situ Polymerization of MEH-PPV in Mesoporous Titania Photoanodes.

    Science.gov (United States)

    Minar, Norma K; Docampo, Pablo; Fattakhova-Rohlfing, Dina; Bein, Thomas

    2015-05-20

    Incorporation of conjugated polymers into porous metal oxide networks is a challenging task, which is being pursued via many different approaches. We have developed the guided in situ polymerization of poly(2-methoxy-5-(2'-ethylhexyloxy)-p-phenylenevinylene) (MEH-PPV) in porous titania films by means of surface functionalization. The controlled polymerization via the Gilch route was induced by an alkoxide base and by increasing the temperature. The selected and specially designed surface-functionalizing linker molecules mimic the monomer or its activated form, respectively. In this way, we drastically enhanced the amount of MEH-PPV incorporated into the porous titania phase compared to nonfunctionalized samples by a factor of 6. Additionally, photovoltaic measurements were performed. The devices show shunting or series resistance limitations, depending on the surface functionalization prior to in situ polymerization of MEH-PPV. We suggest that the reason for this behavior can be found in the orientation of the grown polymer chains with respect to the titania surface. Therefore, the geometry of the anchoring via the linker molecules is relevant for exploiting the full electronic potential of the conjugated polymer in the resulting hybrid composite. This observation will help to design future synthesis methods for new hybrid materials from conjugated polymers and n-type semiconductors to take full advantage of favorable electronic interactions between the two phases.

  9. Nanoscale roughness and morphology affect the IsoElectric Point of titania surfaces.

    Directory of Open Access Journals (Sweden)

    Francesca Borghi

    Full Text Available We report on the systematic investigation of the role of surface nanoscale roughness and morphology on the charging behaviour of nanostructured titania (TiO2 surfaces in aqueous solutions. IsoElectric Points (IEPs of surfaces have been characterized by direct measurement of the electrostatic double layer interactions between titania surfaces and the micrometer-sized spherical silica probe of an atomic force microscope in NaCl aqueous electrolyte. The use of a colloidal probe provides well-defined interaction geometry and allows effectively probing the overall effect of nanoscale morphology. By using supersonic cluster beam deposition to fabricate nanostructured titania films, we achieved a quantitative control over the surface morphological parameters. We performed a systematical exploration of the electrical double layer properties in different interaction regimes characterized by different ratios of characteristic nanometric lengths of the system: the surface rms roughness Rq, the correlation length ξ and the Debye length λD. We observed a remarkable reduction by several pH units of IEP on rough nanostructured surfaces, with respect to flat crystalline rutile TiO2. In order to explain the observed behavior of IEP, we consider the roughness-induced self-overlap of the electrical double layers as a potential source of deviation from the trend expected for flat surfaces.

  10. Titania-Coated Silica Alone and Modified by Sodium Alginate as Sorbents for Heavy Metal Ions

    Science.gov (United States)

    Kołodyńska, D.; Gęca, M.; Skwarek, E.; Goncharuk, O.

    2018-04-01

    The novel organic-inorganic biohybrid composite adsorbent was synthesized based on nanosized silica-titania modified with alginate within the development of effective adsorbent for heavy metal ions. Effects of metal species Cu(II), Zn(II), Cd(II), and Pb(II); concentrations; pH; temperature; and adsorption onto titania-coated silica (ST20) initial or modified by sodium alginate (ST20-ALG) were studied. The equilibrium and kinetic data of metal ions adsorption were analyzed using Langmuir and Freundlich adsorption models and kinetic models: pseudo first order, pseudo second order, intraparticle kinetic model, and Elovich. The maximum sorption capacities observed were higher for the ST20-ALG composite compared to the initial ST20 oxide for all studied metal ions, namely their values for ST20-ALG were 22.44 mg g- 1 for Cu(II) adsorption, 19.95 mg g- 1 for Zn(II), 18.85 mg g- 1 for Cd(II), and 32.49 mg g- 1 for Pb(II). Structure and properties of initial silica-titania ST20 and modified by sodium alginate ST20-ALG adsorbents were analyzed using nitrogen adsorption/desorption isotherms, ATR-FTIR, SEM-EDS, and pHpzc techniques.

  11. Electrochemical coating of dental implants with anodic porous titania for enhanced osteointegration

    Directory of Open Access Journals (Sweden)

    Amirreza Shayganpour

    2015-11-01

    Full Text Available Clinical long-term osteointegration of titanium-based biomedical devices is the main goal for both dental and orthopedical implants. Both the surface morphology and the possible functionalization of the implant surface are important points. In the last decade, following the success of nanostructured anodic porous alumina, anodic porous titania has also attracted the interest of academic researchers. This material, investigated mainly for its photocatalytic properties and for applications in solar cells, is usually obtained from the anodization of ultrapure titanium. We anodized dental implants made of commercial grade titanium under different experimental conditions and characterized the resulting surface morphology with scanning electron microscopy equipped with an energy dispersive spectrometer. The appearance of nanopores on these implants confirm that anodic porous titania can be obtained not only on ultrapure and flat titanium but also as a conformal coating on curved surfaces of real objects made of industrial titanium alloys. Raman spectroscopy showed that the titania phase obtained is anatase. Furthermore, it was demonstrated that by carrying out the anodization in the presence of electrolyte additives such as magnesium, these can be incorporated into the porous coating. The proposed method for the surface nanostructuring of biomedical implants should allow for integration of conventional microscale treatments such as sandblasting with additive nanoscale patterning. Additional advantages are provided by this material when considering the possible loading of bioactive drugs in the porous cavities.

  12. Porous titania surfaces on titanium with hierarchical macro- and mesoporosities for enhancing cell adhesion, proliferation and mineralization

    International Nuclear Information System (INIS)

    Han, Guang; Müller, Werner E.G.; Wang, Xiaohong; Lilja, Louise; Shen, Zhijian

    2015-01-01

    Titanium received a macroporous titania surface layer by anodization, which contains open pores with average pore diameter around 5 μm. An additional mesoporous titania top layer following the contour of the macropores, of 100–200 nm thickness and with a pore diameter of 10 nm, was formed by using the evaporation-induced self-assembly (EISA) method with titanium (IV) tetraethoxide as the precursor. A coherent laminar titania surface layer was thus obtained, creating a hierarchical macro- and mesoporous surface that was characterized by high-resolution electron microscopy. The interfacial bonding between the surface layers and the titanium matrix was characterized by the scratch test that confirmed a stable and strong bonding of titania surface layers on titanium. The wettability to water and the effects on the osteosarcoma cell line (SaOS-2) proliferation and mineralization of the formed titania surface layers were studied systematically by cell culture and scanning electron microscopy. The results proved that the porous titania surface with hierarchical macro- and mesoporosities was hydrophilic that significantly promoted cell attachment and spreading. A synergistic role of the hierarchical macro- and mesoporosities was revealed in terms of enhancing cell adhesion, proliferation and mineralization, compared with the titania surface with solo scale topography. - Highlights: • We developed a hierarchical macro- and mesoporous surface layer on titanium. • New surface layer was strong enough to sustain on implant surface. • New surface owned better surface wettability. • New surface can promote SaOS-2 cell adhesion, proliferation and mineralization. • Synergistic effects on cell responses occur when two porous structures coexist

  13. Porous titania surfaces on titanium with hierarchical macro- and mesoporosities for enhancing cell adhesion, proliferation and mineralization

    Energy Technology Data Exchange (ETDEWEB)

    Han, Guang [Department of Materials and Environmental Chemistry, Arrhenius Laboratory, Stockholm University, 10691 Stockholm (Sweden); Müller, Werner E.G.; Wang, Xiaohong [ERC Advanced Grant Research Group at the Institute for Physiological Chemistry, University Medical Center of the Johannes Gutenberg University Mainz, Duesbergweg 6, D-55128 Mainz (Germany); Lilja, Louise [Department of Materials and Environmental Chemistry, Arrhenius Laboratory, Stockholm University, 10691 Stockholm (Sweden); Department of Physics, Chemistry and Biology, Linköping University, SE-581 83 Linköping (Sweden); Shen, Zhijian, E-mail: shen@mmk.su.se [Department of Materials and Environmental Chemistry, Arrhenius Laboratory, Stockholm University, 10691 Stockholm (Sweden)

    2015-02-01

    Titanium received a macroporous titania surface layer by anodization, which contains open pores with average pore diameter around 5 μm. An additional mesoporous titania top layer following the contour of the macropores, of 100–200 nm thickness and with a pore diameter of 10 nm, was formed by using the evaporation-induced self-assembly (EISA) method with titanium (IV) tetraethoxide as the precursor. A coherent laminar titania surface layer was thus obtained, creating a hierarchical macro- and mesoporous surface that was characterized by high-resolution electron microscopy. The interfacial bonding between the surface layers and the titanium matrix was characterized by the scratch test that confirmed a stable and strong bonding of titania surface layers on titanium. The wettability to water and the effects on the osteosarcoma cell line (SaOS-2) proliferation and mineralization of the formed titania surface layers were studied systematically by cell culture and scanning electron microscopy. The results proved that the porous titania surface with hierarchical macro- and mesoporosities was hydrophilic that significantly promoted cell attachment and spreading. A synergistic role of the hierarchical macro- and mesoporosities was revealed in terms of enhancing cell adhesion, proliferation and mineralization, compared with the titania surface with solo scale topography. - Highlights: • We developed a hierarchical macro- and mesoporous surface layer on titanium. • New surface layer was strong enough to sustain on implant surface. • New surface owned better surface wettability. • New surface can promote SaOS-2 cell adhesion, proliferation and mineralization. • Synergistic effects on cell responses occur when two porous structures coexist.

  14. The role of nanocrystalline titania coating on nanostructured austenitic stainless steel in enhancing osteoblasts functions for regeneration of tissue

    Energy Technology Data Exchange (ETDEWEB)

    Shah, J.S.; Venkatsurya, P.K.C.; Thein-Han, W.W. [Biomaterials and Biomedical Engineering Research Laboratory, Center for Structural and Functional Materials, University of Louisiana at Lafayette, P.O. Box 44130, Lafayette, LA 70504 (United States); Misra, R.D.K., E-mail: dmisra@louisiana.edu [Biomaterials and Biomedical Engineering Research Laboratory, Center for Structural and Functional Materials, University of Louisiana at Lafayette, P.O. Box 44130, Lafayette, LA 70504 (United States); Pesacreta, T.C. [Department of Biology, University of Louisiana at Lafayette, P.O. Box 42451, Lafayette, LA 70504 (United States); Somani, M.C.; Karjalainen, L.P. [Department of Mechanical Engineering, University of Oulu, P.O. Box 4200, 90014 Oulu (Finland)

    2011-03-12

    In the context of osseointegration of metallic implants, while nanostructuring the surface favorably modulates cellular response, the disinfective attributes required during the healing process are not available. Thus, in the present study, we demonstrate that nanocrystalline titania provides cumulative benefit of enhancing osteoblasts functions to promote the efficacy of metal implants together with the disinfective attributes. To this end, the primary objective here is to examine the select functions of bone forming cells (osteoblasts) on electrocrystallized nanonodular titania-coated nanograined/ultrafine grained (NG/UFG) austenitic stainless steel. The accompanying objective is to study the disinfective/antimicrobial activity. To the best of our understanding this is the first study of nanophase titania on a non-titanium substrate. The osteoblasts functions were investigated in terms of cell attachment, proliferation, and quantitative analysis of proteins, actin and vinculin. In comparison to the bare NG/UFG substrate, the nanophase titania-coated substrate exhibited higher degree of cell attachment and proliferation which are regulated via cellular and molecular interactions with proteins, actin and vinculin. The enhanced functions of osteoblasts suggest that nanophase titania adsorbs extracellular matrix proteins, fibronectin and vitronectin from serum enhancing protein, with subsequent binding of integrins and osteoblasts precursor to titania. The antimicrobial attributes assessed in terms of degradation of methyl orange and effectiveness in killing E. coli supports the viewpoint that large surface area of titania would be instrumental in reducing the detrimental effect of biologically reactive oxygen species produced by macrophages in the vicinity of the metal bone/implant interface. In summary, the study provides some new insights concerning nanostructuring of metallic substrates with specific physical and surface properties for medical devices with

  15. Synthesis and structural property of Si nanosheets connected to Si nanowires using MnCl{sub 2}/Si powder source

    Energy Technology Data Exchange (ETDEWEB)

    Meng, Erchao [Graduate School of Science and Technology, Shizuoka University, 3-5-1 Johuku, Naka-ku, Hamamatsu, Shizuoka 432-8561 (Japan); Ueki, Akiko [Toyota Central R& D Labs., Inc., 41-1 Yokomichi, Nagakute, Aichi 480-1192 (Japan); Meng, Xiang [Graduate School of Science and Technology, Shizuoka University, 3-5-1 Johuku, Naka-ku, Hamamatsu, Shizuoka 432-8561 (Japan); Suzuki, Hiroaki [Graduate School of Engineering, Shizuoka University, 3-5-1 Johuku, Naka-ku, Hamamatsu, Shizuoka 432-8561 (Japan); Itahara, Hiroshi [Toyota Central R& D Labs., Inc., 41-1 Yokomichi, Nagakute, Aichi 480-1192 (Japan); Tatsuoka, Hirokazu, E-mail: tatsuoka.hirokazu@shizuoka.ac.jp [Graduate School of Integrated Science and Technology, Shizuoka University, 3-5-1 Johuku, Naka-ku, Hamamatsu, Shizuoka 432-8561 (Japan)

    2016-08-15

    Graphical abstract: Si nanosheets connected to Si nanowires synthesized using a MnCl{sub 2}/Si powder source with an Au catalyst avoid the use of air-sensitive SiH{sub 4} or SiCl{sub 4}. It was evident from these structural features of the nanosheets (leaf blade) with nanowires (petiole) that the nanosheets were formed by the twin-plane reentrant-edge mechanism. The feature of the observed lattice fringes of the Si(111) nanosheets was clearly explained by the interference with the extra diffraction spots that arose due to the reciprocal lattice streaking effect. - Highlights: • New Si nanosheets connected to Si nanowires were synthesized using MnCl{sub 2}/Si powders. • The synthesis method has benefits in terms of avoiding air sensitive SiH{sub 4} or SiCl{sub 4}. • Structural property and electron diffraction of the Si nanosheets were clarified. • Odd lattice fringes of the Si nanosheets observed by HRTEM were clearly explained. - Abstract: Si nanosheets connected to Si nanowires were synthesized using a MnCl{sub 2}/Si powder source with an Au catalyst. The synthesis method has benefits in terms of avoiding conventionally used air-sensitive SiH{sub 4} or SiCl{sub 4}. The existence of the Si nanosheets connected to the Si<111> nanowires, like sprouts or leaves with petioles, was observed, and the surface of the nanosheets was Si{111}. The nanosheets were grown in the growth direction of <211> perpendicular to that of the Si nanowires. It was evident from these structural features of the nanosheets that the nanosheets were formed by the twin-plane reentrant-edge mechanism. The feature of the observed lattice fringes, which do not appear for Si bulk crystals, of the Si(111) nanosheets obtained by high resolution transmission electron microscopy was clearly explained due to the extra diffraction spots that arose by the reciprocal lattice streaking effect.

  16. Boron nitride nanosheets as oxygen-atom corrosion protective coatings

    International Nuclear Information System (INIS)

    Yi, Min; Shen, Zhigang; Zhao, Xiaohu; Liang, Shuaishuai; Liu, Lei

    2014-01-01

    The research of two-dimensional nanomaterials for anticorrosion applications is just recently burgeoning. Herein, we demonstrate the boron nitride nanosheets (BNNSs) coatings for protecting polymer from oxygen-atom corrosion. High-quality BNNSs, which are produced by an effective fluid dynamics method with multiple exfoliation mechanisms, can be assembled into coatings with controlled thickness by vacuum filtration. After exposed in atom oxygen, the naked polymer is severely corroded with remarkable mass loss, while the BNNSs-coated polymer remains intact. Barrier and bonding effects of the BNNSs are responsible for the coating's protective performance. These preliminary yet reproducible results pave a way for resisting oxygen-atom corrosion

  17. Surface activation of graphene oxide nanosheets by ultraviolet irradiation for highly efficient anti-bacterials

    Science.gov (United States)

    Veerapandian, Murugan; Zhang, Linghe; Krishnamoorthy, Karthikeyan; Yun, Kyusik

    2013-10-01

    A comprehensive investigation of anti-bacterial properties of graphene oxide (GO) and ultraviolet (UV) irradiated GO nanosheets was carried out. Microscopic characterization revealed that the GO nanosheet-like structures had wavy features and wrinkles or thin grooves. Fundamental surface chemical states of GO nanosheets (before and after UV irradiation) were investigated using x-ray photoelectron spectroscopy and ultraviolet photoelectron spectroscopy. Minimum inhibitory concentration (MIC) results revealed that UV irradiated GO nanosheets have more pronounced anti-bacterial behavior than GO nanosheets and standard antibiotic, kanamycin. The MIC of UV irradiated GO nanosheets was 0.125 μg ml-1 for Escherichia coli and Salmonella typhimurium, 0.25 μg ml-1 for Bacillus subtilis and 0.5 μg ml-1 for Enterococcus faecalis, ensuring its potential as an anti-infective agent for controlling the growth of pathogenic bacteria. The minimum bactericidal concentration of normal GO nanosheets was determined to be two-fold higher than its corresponding MIC value, indicating promising bactericidal activity. The mechanism of anti-bacterial action was evaluated by measuring the enzymatic activity of β-d-galactosidase for the hydrolysis of o-nitrophenol-β-d-galactopyranoside.

  18. Surface activation of graphene oxide nanosheets by ultraviolet irradiation for highly efficient anti-bacterials

    International Nuclear Information System (INIS)

    Veerapandian, Murugan; Zhang, Linghe; Yun, Kyusik; Krishnamoorthy, Karthikeyan

    2013-01-01

    A comprehensive investigation of anti-bacterial properties of graphene oxide (GO) and ultraviolet (UV) irradiated GO nanosheets was carried out. Microscopic characterization revealed that the GO nanosheet-like structures had wavy features and wrinkles or thin grooves. Fundamental surface chemical states of GO nanosheets (before and after UV irradiation) were investigated using x-ray photoelectron spectroscopy and ultraviolet photoelectron spectroscopy. Minimum inhibitory concentration (MIC) results revealed that UV irradiated GO nanosheets have more pronounced anti-bacterial behavior than GO nanosheets and standard antibiotic, kanamycin. The MIC of UV irradiated GO nanosheets was 0.125 μg ml −1 for Escherichia coli and Salmonella typhimurium, 0.25 μg ml −1 for Bacillus subtilis and 0.5 μg ml −1 for Enterococcus faecalis, ensuring its potential as an anti-infective agent for controlling the growth of pathogenic bacteria. The minimum bactericidal concentration of normal GO nanosheets was determined to be two-fold higher than its corresponding MIC value, indicating promising bactericidal activity. The mechanism of anti-bacterial action was evaluated by measuring the enzymatic activity of β-d-galactosidase for the hydrolysis of o-nitrophenol-β-d-galactopyranoside. (paper)

  19. Graphene-like monolayer InSe–X: several promising half-metallic nanosheets in spintronics

    Science.gov (United States)

    Liu, Jun; Kang, Wei; Zhou, Ting-Yan; Ma, Chong-Geng

    2018-04-01

    Several half-metallic graphene-like nanosheets, namely halogen atom adsorbed InSe–X (X  =  F, Cl, Br and I) nanosheets, are predicted by first-principles calculations. Then, their structural, electric and magnetic properties are studied in detail. The calculated negative adsorption energies of these InSe–X nanosheets ensure that they attain stable adsorption structures, which suggests that they may be prepared experimentally. The pristine InSe monolayer is a typical semi-conductor, whereas it is interesting that the X ion (X  =  F, Cl, Br and I) adsorbed InSe–X nanosheets are electronically conductive. They can be promising and good candidates for applications of half-metallic 2D materials. The calculated magnetic moments of these nanosheets are close to 1.0 µ B. In the InSe–F nanosheet, there are sp2 hybridized orbitals due to the crystal field effect, and its electroconductibility, half-metallicity and magnetic moments originate from the In and Se ions, not the F ion. However, in InSe–X (X  =  Cl, Br and I) nanosheets, there are sp3 hybridized orbitals, and their electroconductibility, half-metallicity and magnetic moments originate mainly from X ions, together partially with the In and Se ions.

  20. Graphene/MnO{sub 2} hybrid nanosheets as high performance electrode materials for supercapacitors

    Energy Technology Data Exchange (ETDEWEB)

    Mondal, Anjon Kumar, E-mail: Anjon.K.Mondal@student.uts.edu.au [Centre for Clean Energy Technology, School of Chemistry and Forensic Science, University of Technology, Sydney, Broadway, Sydney, NSW 2007 (Australia); Wang, Bei; Su, Dawei; Wang, Ying; Chen, Shuangqiang [Centre for Clean Energy Technology, School of Chemistry and Forensic Science, University of Technology, Sydney, Broadway, Sydney, NSW 2007 (Australia); Zhang, Xiaogang [College of Materials Science and Engineering, Nanjing University of Aeronautics and Astronautics, Nanjing (China); Wang, Guoxiu, E-mail: Guoxiu.wang@uts.edu.au [Centre for Clean Energy Technology, School of Chemistry and Forensic Science, University of Technology, Sydney, Broadway, Sydney, NSW 2007 (Australia)

    2014-01-15

    Graphene/MnO{sub 2} hybrid nanosheets were prepared by incorporating graphene and MnO{sub 2} nanosheets in ethylene glycol. Scanning electron microscopy and transmission electron microscopy analyses confirmed nanosheet morphology of the hybrid materials. Graphene/MnO{sub 2} hybrid nanosheets with different ratios were investigated as electrode materials for supercapacitors by cyclic voltammetry (CV) and galvanostatic charge–discharge in 1 M Na{sub 2}SO{sub 4} electrolyte. We found that the graphene/MnO{sub 2} hybrid nanosheets with a weight ratio of 1:4 (graphene:MnO{sub 2}) delivered the highest specific capacitance of 320 F g{sup −1}. Graphene/MnO{sub 2} hybrid nanosheets also exhibited good capacitance retention on 2000 cycles. - Highlights: • Graphene/MnO{sub 2} hybrid nanosheets with different ratios were fabricated. • The specific capacitance is strongly dependent on graphene/MnO{sub 2} ratios. • The graphene/MnO{sub 2} hybrid electrode (1:4) exhibited high specific capacitance. • The electrode retained 84% of the initial specific capacitance after 2000 cycles.

  1. Photochemical decoration of silver nanoparticles on graphene oxide nanosheets and their optical characterization

    Energy Technology Data Exchange (ETDEWEB)

    Lan, Nguyen Thi; Chi, Do Thi; Dinh, Ngo Xuan; Hung, Nguyen Duy; Lan, Hoang [Department of Nanoscience and Nanotechnology, Advanced Institute for Science and Technology (AIST), Hanoi University of Science and Technology (HUST), No. 1 Dai Co Viet Street, Hai Ba Trung District, Hanoi (Viet Nam); Tuan, Pham Anh [Vietnam Metrology Institute, 08 Hoang Quoc Viet Road, Cau Giay District, Hanoi (Viet Nam); Thang, Le Hong [School of Materials Science and Engineering, Hanoi University of Science and Technology (HUST), 01 Dai Co Viet Street, Hai Ba Trung District, Hanoi (Viet Nam); Trung, Nguyen Ngoc [School of Engineering Physics, Hanoi University of Science and Technology (HUST), 01 Dai Co Viet Street, Hai Ba Trung District, Hanoi (Viet Nam); Hoa, Nguyen Quang [Department of Physics, Hanoi University of Science, 334 Nguyen Trai, Thanh Xuan, Hanoi (Viet Nam); Huy, Tran Quang [Laboratory for Ultrastructure and Bionanotechnology (LUBN), National Institute of Hygiene and Epidemiology (NIHE), No. 1 Yecxanh Street, Hai Ba Trung District, Hanoi (Viet Nam); Quy, Nguyen Van [International Training Institute for Materials Science (ITIMS), Hanoi University of Science and Technology (HUST), 01 Dai Co Viet Street, Hai Ba Trung District, Hanoi (Viet Nam); Duong, Thanh-Tung [Department of Materials Engineering, Chungnam National University, Daeduk Science Town, 305-764 Daejeon (Korea, Republic of); Phan, Vu Ngoc [Department of Nanoscience and Nanotechnology, Advanced Institute for Science and Technology (AIST), Hanoi University of Science and Technology (HUST), No. 1 Dai Co Viet Street, Hai Ba Trung District, Hanoi (Viet Nam); Le, Anh-Tuan, E-mail: tuan.leanh1@hust.edu.vn [Department of Nanoscience and Nanotechnology, Advanced Institute for Science and Technology (AIST), Hanoi University of Science and Technology (HUST), No. 1 Dai Co Viet Street, Hai Ba Trung District, Hanoi (Viet Nam)

    2014-12-05

    Highlights: • A photochemical method for effective decoration of the Ag-NPs on GO nanosheets is presented. • The average size of the Ag-NPs on the GO nanosheets obtained ∼6–7 nm with uniform size distribution. • Surface interaction of Ag-NPs with GO nanosheets leads to surface plasmon-enhanced luminescence. - Abstract: Nanohybrid materials based on silver nanoparticles (Ag-NPs) and graphene oxide (GO) are attracting considerable research interest because of their potential many applications including surface-enhanced Raman scattering, catalysis, sensors, biomedicine and antimicrobials. In this study, we established a simple and effective method of preparing a finely dispersed Ag-GO aqueous solution using modified Hummer and photochemical technique. The Ag-NPs formation on GO nanosheets was analyzed by X-ray diffraction, transmission electron microscopy, Raman spectroscopy, and Fourier-transform infrared spectroscopy. The average size of Ag-NPs on the GO nanosheets was approximately 6–7 nm with nearly uniform size distribution. The Ag-GO nanohybrid also exhibits an adsorption band at 435 nm because of the presence of Ag-NPs on the GO nanosheets. Photoluminescence emission of the Ag-GO nanohybrid was found at 400 and 530 nm, which can be attributed to the interaction between the luminescence of exploited GO nanosheets and localized surface plasmon resonance from metallic Ag-NPs. The observed excellent optical properties of the as-prepared Ag-GO nanohybrid showed a significant potential for optoelectronics applications.

  2. Two-dimensional bismuth nanosheets as prospective photo-detector with tunable optoelectronic performance

    Science.gov (United States)

    Huang, Hao; Ren, Xiaohui; Li, Zhongjun; Wang, Huide; Huang, Zongyu; Qiao, Hui; Tang, Pinghua; Zhao, Jinlai; Liang, Weiyuan; Ge, Yanqi; Liu, Jie; Li, Jianqing; Qi, Xiang; Zhang, Han

    2018-06-01

    Two dimensional Bi nanosheets have been employed to fabricate electrodes for broadband photo-detection. A series of characterization techniques including scanning electron microscopy and high-resolution transmission electron microscopy have verified that Bi nanosheets with intact lamellar structure have been obtained after facile liquid phase exfoliation. In the meanwhile, UV–vis and Raman spectra are also carried out and the inherent optical and physical properties of Bi nanosheets are confirmed. Inherited from the topological characteristics of Bi bulk counterpart, the resultant Bi nanosheet-based photo-detector exhibits preferable photo-response activity as well as environmental robustness. We then evaluate the photo-electrochemical (PEC) performance of the photodetector in 1 M NaOH and 0.5 M Na2SO4 electrolytes, and demonstrated that the as-prepared Bi nanosheets may possess a great potential as PEC-type photo-detector. Additional PEC measurements show that the current density of Bi nanosheets can reach up to 830 nA cm‑2, while an enhanced responsivity (1.8 μA W‑1) had been achieved. We anticipate that this contribution can provide feasibility towards the construction of high-performance elemental Bi nanosheets-based optoelectronic devices in the future.

  3. Graphene/MnO2 hybrid nanosheets as high performance electrode materials for supercapacitors

    International Nuclear Information System (INIS)

    Mondal, Anjon Kumar; Wang, Bei; Su, Dawei; Wang, Ying; Chen, Shuangqiang; Zhang, Xiaogang; Wang, Guoxiu

    2014-01-01

    Graphene/MnO 2 hybrid nanosheets were prepared by incorporating graphene and MnO 2 nanosheets in ethylene glycol. Scanning electron microscopy and transmission electron microscopy analyses confirmed nanosheet morphology of the hybrid materials. Graphene/MnO 2 hybrid nanosheets with different ratios were investigated as electrode materials for supercapacitors by cyclic voltammetry (CV) and galvanostatic charge–discharge in 1 M Na 2 SO 4 electrolyte. We found that the graphene/MnO 2 hybrid nanosheets with a weight ratio of 1:4 (graphene:MnO 2 ) delivered the highest specific capacitance of 320 F g −1 . Graphene/MnO 2 hybrid nanosheets also exhibited good capacitance retention on 2000 cycles. - Highlights: • Graphene/MnO 2 hybrid nanosheets with different ratios were fabricated. • The specific capacitance is strongly dependent on graphene/MnO 2 ratios. • The graphene/MnO 2 hybrid electrode (1:4) exhibited high specific capacitance. • The electrode retained 84% of the initial specific capacitance after 2000 cycles

  4. Synthesis of Ultrathin Si Nanosheets from Natural Clays for Lithium-Ion Battery Anodes.

    Science.gov (United States)

    Ryu, Jaegeon; Hong, Dongki; Choi, Sinho; Park, Soojin

    2016-02-23

    Two-dimensional Si nanosheets have been studied as a promising candidate for lithium-ion battery anode materials. However, Si nanosheets reported so far showed poor cycling performances and required further improvements. In this work, we utilize inexpensive natural clays for preparing high quality Si nanosheets via a one-step simultaneous molten salt-induced exfoliation and chemical reduction process. This approach produces high purity mesoporous Si nanosheets in high yield. As a control experiment, two-step process (pre-exfoliated silicate sheets and subsequent chemical reduction) cannot sustain their original two-dimensional structure. In contrast, one-step method results in a production of 5 nm-thick highly porous Si nanosheets. Carbon-coated Si nanosheet anodes exhibit a high reversible capacity of 865 mAh g(-1) at 1.0 A g(-1) with an outstanding capacity retention of 92.3% after 500 cycles. It also delivers high rate capability, corresponding to a capacity of 60% at 20 A g(-1) compared to that of 2.0 A g(-1). Furthermore, the Si nanosheet electrodes show volume expansion of only 42% after 200 cycles.

  5. Spin valley and giant quantum spin Hall gap of hydrofluorinated bismuth nanosheet.

    Science.gov (United States)

    Gao, Heng; Wu, Wei; Hu, Tao; Stroppa, Alessandro; Wang, Xinran; Wang, Baigeng; Miao, Feng; Ren, Wei

    2018-05-09

    Spin-valley and electronic band topological properties have been extensively explored in quantum material science, yet their coexistence has rarely been realized in stoichiometric two-dimensional (2D) materials. We theoretically predict the quantum spin Hall effect (QSHE) in the hydrofluorinated bismuth (Bi 2 HF) nanosheet where the hydrogen (H) and fluorine (F) atoms are functionalized on opposite sides of bismuth (Bi) atomic monolayer. Such Bi 2 HF nanosheet is found to be a 2D topological insulator with a giant band gap of 0.97 eV which might host room temperature QSHE. The atomistic structure of Bi 2 HF nanosheet is noncentrosymmetric and the spontaneous polarization arises from the hydrofluorinated morphology. The phonon spectrum and ab initio molecular dynamic (AIMD) calculations reveal that the proposed Bi 2 HF nanosheet is dynamically and thermally stable. The inversion symmetry breaking together with spin-orbit coupling (SOC) leads to the coupling between spin and valley in Bi 2 HF nanosheet. The emerging valley-dependent properties and the interplay between intrinsic dipole and SOC are investigated using first-principles calculations combined with an effective Hamiltonian model. The topological invariant of the Bi 2 HF nanosheet is confirmed by using Wilson loop method and the calculated helical metallic edge states are shown to host QSHE. The Bi 2 HF nanosheet is therefore a promising platform to realize room temperature QSHE and valley spintronics.

  6. Photochemical decoration of silver nanoparticles on graphene oxide nanosheets and their optical characterization

    International Nuclear Information System (INIS)

    Lan, Nguyen Thi; Chi, Do Thi; Dinh, Ngo Xuan; Hung, Nguyen Duy; Lan, Hoang; Tuan, Pham Anh; Thang, Le Hong; Trung, Nguyen Ngoc; Hoa, Nguyen Quang; Huy, Tran Quang; Quy, Nguyen Van; Duong, Thanh-Tung; Phan, Vu Ngoc; Le, Anh-Tuan

    2014-01-01

    Highlights: • A photochemical method for effective decoration of the Ag-NPs on GO nanosheets is presented. • The average size of the Ag-NPs on the GO nanosheets obtained ∼6–7 nm with uniform size distribution. • Surface interaction of Ag-NPs with GO nanosheets leads to surface plasmon-enhanced luminescence. - Abstract: Nanohybrid materials based on silver nanoparticles (Ag-NPs) and graphene oxide (GO) are attracting considerable research interest because of their potential many applications including surface-enhanced Raman scattering, catalysis, sensors, biomedicine and antimicrobials. In this study, we established a simple and effective method of preparing a finely dispersed Ag-GO aqueous solution using modified Hummer and photochemical technique. The Ag-NPs formation on GO nanosheets was analyzed by X-ray diffraction, transmission electron microscopy, Raman spectroscopy, and Fourier-transform infrared spectroscopy. The average size of Ag-NPs on the GO nanosheets was approximately 6–7 nm with nearly uniform size distribution. The Ag-GO nanohybrid also exhibits an adsorption band at 435 nm because of the presence of Ag-NPs on the GO nanosheets. Photoluminescence emission of the Ag-GO nanohybrid was found at 400 and 530 nm, which can be attributed to the interaction between the luminescence of exploited GO nanosheets and localized surface plasmon resonance from metallic Ag-NPs. The observed excellent optical properties of the as-prepared Ag-GO nanohybrid showed a significant potential for optoelectronics applications

  7. A DFT study on the effect of supporting titania on silica graphene epoxy graphene and carbon nanotubes - Interfacial properties and optical response

    CSIR Research Space (South Africa)

    Kiarii, EM

    2017-08-01

    Full Text Available A first principles study of the Titania is done as used in photo-catalysis to generate charge carries. Models of titania, silica, graphene, epoxy graphene monoxide, single wall Carbon nanotubes and their respective layer were studied in order...

  8. Hydroxyapatite formation on titania-based materials in a solution mimicking body fluid: Effects of manganese and iron addition in anatase.

    Science.gov (United States)

    Shin, Euisup; Kim, Ill Yong; Cho, Sung Baek; Ohtsuki, Chikara

    2015-03-01

    Hydroxyapatite formation on the surfaces of implanted materials plays an important role in osteoconduction of bone substitutes in bone tissues. Titania hydrogels are known to instigate hydroxyapatite formation in a solution mimicking human blood plasma. To date, the relationship between the surface characteristics of titania and hydroxyapatite formation on its surface remains unclear. In this study, titania powders with varying surface characteristics were prepared by addition of manganese or iron to examine hydroxyapatite formation in a type of simulated body fluid (Kokubo solution). Hydroxyapatite formation was monitored by observation of deposited particles with scale-like morphology on the prepared titania powders. The effect of the titania surface characteristics, i.e., crystal structure, zeta potential, hydroxy group content, and specific surface area, on hydroxyapatite formation was examined. Hydroxyapatite formation was observed on the surface of titania powders that were primarily anatase, and featured a negative zeta potential and low specific surface areas irrespective of the hydroxy group content. High specific surface areas inhibited the formation of hydroxyapatite because calcium and phosphate ions were mostly consumed by adsorption on the titania surface. Thus, these surface characteristics of titania determine its osteoconductivity following exposure to body fluid. Copyright © 2014 Elsevier B.V. All rights reserved.

  9. Study of hybrid solar cells made of multilayer nanocrystalline titania and poly(3-octylthiophene) or poly-(3-(2-methylhex-2-yl)-oxy-carbonyldithiophene)

    DEFF Research Database (Denmark)

    Antoniadou, Maria; Stathatos, Elias; Boukos, Nikolaos

    2009-01-01

    Hybrid solar cells have been constructed by using nanocrystalline titania and hole-transporting polymers. Titania was deposited on fluorine-doped tin-oxide transparent electrodes in three layers: a blocking layer and two nanostructured layers, giving densely packed or open structures. Open...

  10. Noncovalently Functionalized Tungsten Disulfide Nanosheets for Enhanced Mechanical and Thermal Properties of Epoxy Nanocomposites.

    Science.gov (United States)

    Sahu, Megha; Narashimhan, Lakshmi; Prakash, Om; Raichur, Ashok M

    2017-04-26

    In the present study, noncovalently functionalized tungsten disulfide (WS 2 ) nanosheets were used as a toughening agent for epoxy nanocomposites. WS 2 was modified with branched polyethyleneimine (PEI) to increase the degree of interaction of nanosheets with the epoxy matrix and prevent restacking and agglomeration of the sheets in the epoxy matrix. The functionalization of WS 2 sheets was confirmed through Fourier transform infrared spectroscopy and thermogravimetric analysis. The exfoliation of the bulk WS 2 was confirmed through X-ray diffraction and various microscopic techniques. Epoxy nanocomposites containing up to 1 wt % of WS 2 -PEI nanosheets were fabricated. They showed a remarkable improvement in fracture toughness (K IC ). K IC increased from 0.94 to 1.72 MPa m -1/2 for WS 2 -PEI nanosheet loadings as low as 0.25 wt %. Compressive and flexural properties also showed a significant improvement as incorporation of 0.25 wt % of WS 2 -PEI nanosheets resulted in 43 and 65% increase in the compressive and flexural strengths of epoxy nanocomposites, respectively, compared with neat epoxy. Thermal stability and thermomechanical properties of the WS 2 -PEI-modified epoxy also showed a significant improvement. The simultaneous improvement in the mechanical and thermal properties could be attributed to the good dispersion of WS 2 -PEI nanosheets in the matrix, intrinsic high strength and thermal properties of the nanosheets, and improved interaction of the WS 2 nanosheets with the epoxy matrix owing to the presence of PEI molecules on the surface of the WS 2 nanosheets.

  11. The effect of the deposition parameters on size, distribution and antimicrobial properties of photoinduced silver nanoparticles on titania coatings

    Energy Technology Data Exchange (ETDEWEB)

    Piwonski, Ireneusz, E-mail: irek@uni.lodz.pl [University of Lodz, Department of Technology and Chemistry of Materials, Pomorska 163, 90-236 Lodz (Poland); Kadziola, Kinga; Kisielewska, Aneta; Soliwoda, Katarzyna [University of Lodz, Department of Technology and Chemistry of Materials, Pomorska 163, 90-236 Lodz (Poland); Wolszczak, Marian [Technical University of Lodz, Institute of Applied Radiation Chemistry, Wroblewskiego 15, 93-590 Lodz (Poland); Lisowska, Katarzyna; Wronska, Natalia; Felczak, Aleksandra [University of Lodz, Department of Industrial Microbiology and Biotechnology, Pilarskiego 14/16, 90-231 Lodz (Poland)

    2011-06-01

    Controlled photodeposition of silver nanoparticles (AgNP) on titania coatings using two different sources of UV light is described. Titania (anatase) thin films were prepared by the sol-gel dip-coating method on silicon wafers. AgNPs were grown on the titania surface as a result of UV illumination of titania films immersed in aqueous solutions of silver nitrate. UV xenon lamp or excimer laser, both operating at the wavelength 351 {+-} 5 nm, was used as illumination sources. The AFM topography of AgNP/TiO{sub 2} nanocomposites revealed that silver nanoparticles could be synthesized by both sources of illumination, however the photocatalysis carried out by UV light from xenon lamp illumination leads to larger AgNP than those synthesized using the laser beam. It was found that the increasing concentration of silver ions in the initial solution increases the number of Ag nanoparticles on the titania surface, while longer time of irradiation results the growth of larger size nanoparticles. Antibacterial tests performed on TiO{sub 2} covered by Ag nanoparticles revealed that increasing density of nanoparticles enhances the inhibition of bacterial growth. It was also found that antibacterial activity drops by only 10-15% after 6 cycles compared to the initial use.

  12. The effect of the deposition parameters on size, distribution and antimicrobial properties of photoinduced silver nanoparticles on titania coatings

    International Nuclear Information System (INIS)

    Piwonski, Ireneusz; Kadziola, Kinga; Kisielewska, Aneta; Soliwoda, Katarzyna; Wolszczak, Marian; Lisowska, Katarzyna; Wronska, Natalia; Felczak, Aleksandra

    2011-01-01

    Controlled photodeposition of silver nanoparticles (AgNP) on titania coatings using two different sources of UV light is described. Titania (anatase) thin films were prepared by the sol-gel dip-coating method on silicon wafers. AgNPs were grown on the titania surface as a result of UV illumination of titania films immersed in aqueous solutions of silver nitrate. UV xenon lamp or excimer laser, both operating at the wavelength 351 ± 5 nm, was used as illumination sources. The AFM topography of AgNP/TiO 2 nanocomposites revealed that silver nanoparticles could be synthesized by both sources of illumination, however the photocatalysis carried out by UV light from xenon lamp illumination leads to larger AgNP than those synthesized using the laser beam. It was found that the increasing concentration of silver ions in the initial solution increases the number of Ag nanoparticles on the titania surface, while longer time of irradiation results the growth of larger size nanoparticles. Antibacterial tests performed on TiO 2 covered by Ag nanoparticles revealed that increasing density of nanoparticles enhances the inhibition of bacterial growth. It was also found that antibacterial activity drops by only 10-15% after 6 cycles compared to the initial use.

  13. On the determining role of network structure titania in silicone against bacterial colonization: Mechanism and disruption of biofilm

    International Nuclear Information System (INIS)

    Depan, D.; Misra, R.D.K.

    2014-01-01

    Silicone-based biomedical devices are prone to microbial adhesion, which is the primary cause of concern in the functioning of the artificial device. Silicone exhibiting long-term and effective antibacterial ability is highly desirable to prevent implant related infections. In this regard, nanophase titania was incorporated in silicone as an integral part of the silicone network structure through cross-link mechanism, with the objective to reduce bacterial adhesion to a minimum. The bacterial adhesion was studied using crystal violet assay, while the mechanism of inhibition of biofilm formation was studied via electron microscopy. The incorporation of nanophase titania in silicone dramatically reduced the viability of Staphylococcus aureus (S. aureus) and the capability to adhere on the surface of hybrid silicone by ∼ 93% in relation to stand alone silicone. The conclusion of dramatic reduction in the viability of S. aureus is corroborated by different experimental approaches including biofilm inhibition assay, zone of inhibition, and through a novel experiment that involved incubation of biofilm with titania nanoparticles. It is proposed that the mechanism of disruption of bacterial film in the presence of titania involves puncturing of the bacterial cell membrane. - Highlights: • Network structure titania in silicone imparts antimicrobial activity. • Ability to microbial adhesion is significantly reduced. • Antimicrobial mechanism involves rupture of biofilm

  14. Visible-Light Degradation of Dyes and Phenols over Mesoporous Titania Prepared by Using Anthocyanin from Red Radish as Template

    Directory of Open Access Journals (Sweden)

    Zhiying Yan

    2014-01-01

    Full Text Available Heterogeneous photocatalysis is able to operate effectively to eliminate organic compounds from wastewater in the presence of semiconductor photocatalyst and a light source. Although photosensitization of titania by organic dyes is one of the conventional ways for visible-light utilization of titania, previous studies have not yet addressed the use of natural food coloring agents as templates in the synthesis of mesostructured materials, let alone the simultaneous achievement of highly crystalline mesoscopic framework and visible-light photocatalytic activity. In this work, anthocyanin, a natural pigment from red radish was directly used as template in synthesis of highly crystalline mesoporous titania. The synthesized mesoporous titania samples were characterized by a combination of various physicochemical techniques, such as XRD, SEM, HRTEM, nitrogen adsorption/desorption, and diffuse reflectance UV-Vis. The prepared mesoporous titania photocatalyst exhibited significant activity under visible-light irradiation for the degradation of dyes and phenols due to its red shift of band-gap-absorption onset and visible-light response as a result of the incorporation of surface carbon species.

  15. Macroscale and Nanoscale Morphology Evolution during in Situ Spray Coating of Titania Films for Perovskite Solar Cells.

    Science.gov (United States)

    Su, Bo; Caller-Guzman, Herbert A; Körstgens, Volker; Rui, Yichuan; Yao, Yuan; Saxena, Nitin; Santoro, Gonzalo; Roth, Stephan V; Müller-Buschbaum, Peter

    2017-12-20

    Mesoporous titania is a cheap and widely used material for photovoltaic applications. To enable a large-scale fabrication and a controllable pore size, we combined a block copolymer-assisted sol-gel route with spray coating to fabricate titania films, in which the block copolymer polystyrene-block-poly(ethylene oxide) (PS-b-PEO) is used as a structure-directing template. Both the macroscale and nanoscale are studied. The kinetics and thermodynamics of the spray deposition processes are simulated on a macroscale, which shows a good agreement with the large-scale morphology of the spray-coated films obtained in practice. On the nanoscale, the structure evolution of the titania films is probed with in situ grazing incidence small-angle X-ray scattering (GISAXS) during the spray process. The changes of the PS domain size depend not only on micellization but also on solvent evaporation during the spray coating. Perovskite (CH 3 NH 3 PbI 3 ) solar cells (PSCs) based on sprayed titania film are fabricated, which showcases the suitability of spray-deposited titania films for PSCs.

  16. The feasibility of tunable p-type Mg doping in a GaN monolayer nanosheet

    International Nuclear Information System (INIS)

    Xia, Congxin; Peng, Yuting; Wei, Shuyi; Jia, Yu

    2013-01-01

    Based on density functional theory, the electronic structures, formation energy and transition energy level of a p-type Mg-doped GaN nanosheet are investigated. Numerical results show that the transition energy level decreases monotonously with increasing Mg doping concentration in Mg-doped GaN nanosheet systems, which is lower than that of the Mg-doped bulk GaN case. Moreover, the formation energy calculations indicate that Mg-doped GaN nanosheet structures can be realized under N-rich experimental growth conditions

  17. Electrodeposition of Mesoporous Co3O4 Nanosheets on Carbon Foam for High Performance Supercapacitors

    Directory of Open Access Journals (Sweden)

    Zhemi Xu

    2014-01-01

    Full Text Available Metal oxide nanosheets have promising potential applications in novel energy storage devices. In this work, Co3O4 nanosheets/carbon foam with excellent supercapacitor characteristics was successfully fabricated, without using metal substrates. The experimental results demonstrate that the electrochemical tests showed that the as-prepared Co3O4 nanosheets exhibited an ideal capacitive behavior with a maximum specific capacitance of 106 F/g in 1 M NaOH solution at a scan rate of 0.1 V s−1.

  18. Investigation into the effects of surface stripping ZnO nanosheets

    Science.gov (United States)

    Barnett, Chris J.; Jackson, Georgina; Jones, Daniel R.; Lewis, Aled R.; Welsby, Kathryn; Evans, Jon E.; McGettrick, James D.; Watson, Trystan; Maffeis, Thierry G. G.; Dunstan, Peter R.; Barron, Andrew R.; Cobley, Richard J.

    2018-04-01

    ZnO nanosheets are polycrystalline nanostructures that are used in devices including solar cells and gas sensors. However, for efficient and reproducible device operation and contact behaviour the conductivity characteristics must be controlled and surface contaminants removed. Here we use low doses of argon bombardment to remove surface contamination and make reproducible lower resistance contacts. Higher doses strip the surface of the nanosheets altering the contact type from near-ohmic to rectifying by removing the donor-type defects, which photoluminescence shows to be concentrated in the near-surface. Controlled doses of argon treatments allow nanosheets to be customised for device formation.

  19. Study the gas sensing properties of boron nitride nanosheets

    International Nuclear Information System (INIS)

    Sajjad, Muhammad; Feng, Peter

    2014-01-01

    Graphical abstract: - Highlights: • We synthesized boron nitride nanosheets (BNNSs) on silicon substrate. • We analyzed gas sensing properties of BNNSs-based gas-sensor device. • CH 4 gas is used to measure gas-sensing properties of the device. • Quick response and recovery time of the device is recorded. • BNNSs showed excellent sensitivity to the working gas. - Abstract: In the present communication, we report on the synthesis of boron nitride nanosheets (BNNSs) and study of their gas sensing properties. BNNSs are synthesized by irradiating pyrolytic hexagonal boron nitride (h-BN) target using CO 2 laser pulses. High resolution transmission electron microscopic measurements (HRTEM) revealed 2-dientional honeycomb crystal lattice structure of BNNSs. HRTEM, electron diffraction, XRD and Raman scattering measurements clearly identified h-BN. Gas sensing properties of synthesized BNNSs were analyzed with prototype gas sensor using methane as working gas. A systematic response curve of the sensor is recorded in each cycle of gas “in” and “out”; suggesting excellent sensitivity and high performance of BNNSs-based gas-sensor

  20. A Two-Dimensional Lamellar Membrane: MXene Nanosheet Stacks.

    Science.gov (United States)

    Ding, Li; Wei, Yanying; Wang, Yanjie; Chen, Hongbin; Caro, Jürgen; Wang, Haihui

    2017-02-06

    Two-dimensional (2D) materials are promising candidates for advanced water purification membranes. A new kind of lamellar membrane is based on a stack of 2D MXene nanosheets. Starting from compact Ti 3 AlC 2 , delaminated nanosheets of the composition Ti 3 C 2 T x with the functional groups T (O, OH, and/or F) can be produced by etching and ultrasonication and stapled on a porous support by vacuum filtration. The MXene membrane supported on anodic aluminum oxide (AAO) substrate shows excellent water permeance (more than 1000 L m -2  h -1  bar -1 ) and favorable rejection rate (over 90 %) for molecules with sizes larger than 2.5 nm. The water permeance through the MXene membrane is much higher than that of the most membranes with similar rejections. Long-time operation also reveals the outstanding stability of the MXene membrane for water purification. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  1. Structure and Optical Properties of Titania-PDMS Hybrid Nanocomposites Prepared by In Situ Non-Aqueous Synthesis

    Directory of Open Access Journals (Sweden)

    Antoine R. M. Dalod

    2017-12-01

    Full Text Available Organic-inorganic hybrid materials are attractive due to the combination of properties from the two distinct types of materials. In this work, transparent titania-polydimethylsiloxane hybrid materials with up to 15.5 vol. % TiO2 content were prepared by an in situ non-aqueous method using titanium (IV isopropoxide and hydroxy-terminated polydimethylsiloxane as precursors. Spectroscopy (Fourier transform infrared, Raman, Ultraviolet-visible, ellipsometry and small-angle X-ray scattering analysis allowed to describe in detail the structure and the optical properties of the nanocomposites. Titanium alkoxide was successfully used as a cross-linker and titania-like nanodomains with an average size of approximately 4 nm were shown to form during the process. The resulting hybrid nanocomposites exhibit high transparency and tunable refractive index from 1.42 up to 1.56, depending on the titania content.

  2. Optimizing sol-gel infiltration for the fabrication of high-quality titania inverse opal and its photocatalytic activity

    International Nuclear Information System (INIS)

    Liu Weijie; Zou Bo; Zhao Jing; Cui Haining

    2010-01-01

    This article reports an optimized sol-gel opal infiltration technique for the fabrication of high-quality titania inverse opal. Different from previous reports, the presently proposed method is facile, efficient and suitable for other inorganic oxide. We have compared two different infiltration strategies and their influences on the structure, photonic properties and photocatalytic activity. The obtained titania inverse opal displays excellent photonic properties with photonic band gap at 320 nm and better photocatalytic effect, which is attributed to its high-quality inverse opal nanostructure. Reproducibility tests prove that the photocatalytic activity of the resultant titania inverse opal remains intact even after five repeated photocatalytic reactions under the same procedure and experimental conditions.

  3. Synthesis and luminescence properties of hybrid organic-inorganic transparent titania thin film activated by in- situ formed lanthanide complexes

    Science.gov (United States)

    Wang, Yige; Wang, Li; Li, Huanrong; Liu, Peng; Qin, Dashan; Liu, Binyuan; Zhang, Wenjun; Deng, Ruiping; Zhang, Hongjie

    2008-03-01

    Stable transparent titania thin films were fabricated at room temperature by combining thenoyltrifluoroacetone (TTFA)-modified titanium precursors with amphiphilic triblock poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) (PEO-PPO-PEO, P123) copolymers. The obtained transparent titania thin films were systematically investigated by IR spectroscopy, PL emission and excitation spectroscopy and transmission electron microscopy. IR spectroscopy indicates that TTFA coordinates the titanium center during the process of hydrolysis and condensation. Luminescence spectroscopy confirms the in-situ formation of lanthanide complexes in the transparent titania thin film. TEM image shows that the in-situ formed lanthanide complexes were homogeneously distributed throughout the whole thin film. The quantum yield and the number of water coordinated to lanthanide metal center have been theoretically determined based on the luminescence data.

  4. TiO2 nanosheets synthesized by atomic layer deposition for photocatalysis

    Directory of Open Access Journals (Sweden)

    Riyanto Edy

    2016-10-01

    Full Text Available Two-dimensional TiO2 nanosheets were synthesized by atomic layer deposition (ALD on dissolvable sacrificial polymer layer. The photocatalytic performance of free-standing TiO2 nanosheets prepared with different numbers of ALD cycles (100, 300, 500, and 1000 were investigated by evaluating the degradation rates of methyl orange solutions. It is shown that the photocatalytic activity increases due to Ti3+ defect and the locally ordered structures in amorphous TiO2 nanosheets. The difference in the surface areas of nanosheets may also play a crucial role in the photocatalytic activity. The results obtained in this work can have potential applications in fields like water splitting and dye-sensitized solar cells.

  5. Nanosheet-assembled NiO microstructures for high-performance supercapacitors.

    Science.gov (United States)

    Purushothaman, Kamatchi Kamaraj; Babu, Inbamani Manohara; Sethuraman, Balasubramanian; Muralidharan, Gopalan

    2013-11-13

    Nanosheet-assembled NiO microstructures have been synthesized via a hydrothermal method. The presence of anionic surfactant in the fabrication process initiates the formation of lamellar micelles and a self-assembling process. This leads to the formation of NiO nanosheets and organizes it into microstructures. The effect of preparation temperature on the morphological, structural, and electrochemical properties and stability upon continuous charge/discharge cycles has been examined for supercapacitor applications. Electrochemical analysis demonstrated that NiO nanosheets prepared at 160 °C are capable of delivering a specific capacitance of 989 F g(-1) at a scan rate of 3 mV s(-1) for the potential window of 0-0.6 V. The nanosheets exhibit excellent capacity retention, 97% retention after 1000 continuous charge/discharge cycles, and an energy density of 49.45 W h kg(-1).

  6. Hydrothermal synthesis of nickel oxide nanosheets for lithium-ion batteries and supercapacitors with excellent performance.

    Science.gov (United States)

    Mondal, Anjon Kumar; Su, Dawei; Wang, Ying; Chen, Shuangqiang; Wang, Guoxiu

    2013-11-01

    Nickel oxide nanosheets have been successfully synthesized by a facile ethylene glycol mediated hydrothermal method. The morphology and crystal structure of the nickel oxide nanosheets were characterized by X-ray diffraction, field-emission SEM, and TEM. When applied as electrode materials for lithium-ion batteries and supercapacitors, nickel oxide nanosheets exhibited a high, reversible lithium storage capacity of 1193 mA h g(-1) at a current density of 500 mA g(-1), an enhanced rate capability, and good cycling stability. Nickel oxide nanosheets also demonstrated a superior specific capacitance of 999 F g(-1) at a current density of 20 A g(-1) in supercapacitors. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  7. Prediction of mechanical properties for hexagonal boron nitride nanosheets using molecular mechanics model

    Energy Technology Data Exchange (ETDEWEB)

    Natsuki, Toshiaki [Shinshu University, Faculty of Textile Science and Technology, Ueda (Japan); Shinshu University, Institute of Carbon Science and Technology, Nagano (Japan); Natsuki, Jun [Shinshu University, Institute of Carbon Science and Technology, Nagano (Japan)

    2017-04-15

    Mechanical behaviors of nanomaterials are not easy to be evaluated in the laboratory because of their extremely small size and difficulty controlling. Thus, a suitable model for the estimation of the mechanical properties for nanomaterials becomes very important. In this study, the elastic properties of boron nitride (BN) nanosheets, including the elastic modulus, the shear modulus, and the Poisson's ratio, are predicted using a molecular mechanics model. The molecular mechanics force filed is established to directly incorporate the Morse potential function into the constitutive model of nanostructures. According to the molecular mechanics model, the chirality effect of hexagonal BN nanosheets on the elastic modulus is investigated through a closed-form solution. The simulated result shows that BN nanosheets exhibit an isotropic elastic property. The present analysis yields a set of very simple formulas and is able to be served as a good approximation on the mechanical properties for the BN nanosheets. (orig.)

  8. Palladium nanoparticles anchored on graphene nanosheets: Methanol, ethanol oxidation reactions and their kinetic studies

    KAUST Repository

    Nagaraju, Doddahalli H.; Devaraj, Sappani; Balaya, Palani

    2014-01-01

    nanosheets. The electro-catalytic activity of Gra/Pd nanocomposites toward methanol and ethanol oxidation in alkaline medium was evaluated by cyclic voltammetric studies. 1:1 Gra/Pd nanocomposite exhibited good electro-catalytic activity and efficient

  9. Multilayered nano-architecture of variable sized graphene nanosheets for enhanced supercapacitor electrode performance.

    Science.gov (United States)

    Biswas, Sanjib; Drzal, Lawrence T

    2010-08-01

    The diverse physical and chemical aspects of graphene nanosheets such as particle size surface area and edge chemistry were combined to fabricate a new supercapacitor electrode architecture consisting of a highly aligned network of large-sized nanosheets as a series of current collectors within a multilayer configuration of bulk electrode. Capillary driven self-assembly of monolayers of graphene nanosheets was employed to create a flexible, multilayer, free-standing film of highly hydrophobic nanosheets over large macroscopic areas. This nanoarchitecture exhibits a high-frequency capacitative response and a nearly rectangular cyclic voltammogram at 1000 mV/s scanning rate and possesses a rapid current response, small equivalent series resistance (ESR), and fast ionic diffusion for high-power electrical double-layer capacitor (EDLC) application.

  10. Chirality-dependent anisotropic elastic properties of a monolayer graphene nanosheet.

    Science.gov (United States)

    Guo, Jian-Gang; Zhou, Li-Jun; Kang, Yi-Lan

    2012-04-01

    An analytical approach is presented to predict the elastic properties of a monolayer graphene nanosheet based on interatomic potential energy and continuum mechanics. The elastic extension and torsional springs are utilized to simulate the stretching and angle variation of carbon-carbon bond, respectively. The constitutive equation of the graphene nanosheet is derived by using the strain energy density, and the analytical formulations for nonzero elastic constants are obtained. The in-plane elastic properties of the monolayer graphene nanosheet are proved to be anisotropic. In addition, Young's moduli, Poisson's ratios and shear modulus of the monolayer graphene nanosheet are calculated according to the force constants derived from Morse potential and AMBER force field, respectively, and they were proved to be chirality-dependent. The comparison with experimental results shows a very agreement.

  11. Synthesis of strongly fluorescent molybdenum disulfide nanosheets for cell-targeted labeling.

    Science.gov (United States)

    Wang, Nan; Wei, Fang; Qi, Yuhang; Li, Hongxiang; Lu, Xin; Zhao, Guoqiang; Xu, Qun

    2014-11-26

    MoS2 nanosheets with polydispersity of the lateral dimensions from natural mineral molybdenite have been prepared in the emulsions microenvironment built by the water/surfactant/CO2 system. The size, thickness, and atomic structure are characterized by transmission electron microscopy (TEM), atomic force microscopy (AFM), and laser-scattering particle size analysis. Meanwhile, by the analysis of photoluminescence spectroscopy and microscope, the MoS2 nanosheets with smaller lateral dimensions exhibit extraordinary photoluminescence properties different from those with relatively larger lateral dimensions. The discovery of the excitation dependent photoluminescence for MoS2 nanosheets makes them potentially of interests for the applications in optoelectronics and biology. Moreover, we demonstrate that the fabricated MoS2 nanosheets can be a nontoxic fluorescent label for cell-targeted labeling application.

  12. Prediction of mechanical properties for hexagonal boron nitride nanosheets using molecular mechanics model

    International Nuclear Information System (INIS)

    Natsuki, Toshiaki; Natsuki, Jun

    2017-01-01

    Mechanical behaviors of nanomaterials are not easy to be evaluated in the laboratory because of their extremely small size and difficulty controlling. Thus, a suitable model for the estimation of the mechanical properties for nanomaterials becomes very important. In this study, the elastic properties of boron nitride (BN) nanosheets, including the elastic modulus, the shear modulus, and the Poisson's ratio, are predicted using a molecular mechanics model. The molecular mechanics force filed is established to directly incorporate the Morse potential function into the constitutive model of nanostructures. According to the molecular mechanics model, the chirality effect of hexagonal BN nanosheets on the elastic modulus is investigated through a closed-form solution. The simulated result shows that BN nanosheets exhibit an isotropic elastic property. The present analysis yields a set of very simple formulas and is able to be served as a good approximation on the mechanical properties for the BN nanosheets. (orig.)

  13. Anion vacancy-mediated ferromagnetism in atomic-thick Ni3N nanosheets

    Science.gov (United States)

    Xia, Baorui; Wang, Tongtong; Chi, Xiao; Yu, Xiaojiang; Liu, Peitao; Zhang, Jingyan; Xi, Shibo; Du, Yonghua; Gao, Daqiang

    2017-12-01

    Realizing spin and electronic behavior of two-dimensional ultrathin nanosheets is significant to construct next generation nanoelectronics. Here, atomic-thick Ni3N nanosheets with clear room temperature ferromagnetism and high saturation magnetization (1.2 emu/g) are reported. X-ray magnetic circular dichroism and first-principles calculation results give the evidence that the observed intrinsic ferromagnetism in Ni3N nanosheets originates from the surface N-deficiency, where alignments of localized large magnetic moments of Ni in the vicinity of the N defect can be aligned parallel to activate macroscopic ferromagnetism. These ultrathin Ni3N nanosheets show great potential application in next-generation electron devices.

  14. Titania Supported Pt and Pt/Pd Nano-particle Catalysts for the Oxidation of Sulfur Dioxide

    DEFF Research Database (Denmark)

    Koutsopoulos, Sotiris; Johannessen, Tue; Eriksen, Kim Michael

    2006-01-01

    Several types of titania (anatase) were used as supports for pure platinum and Pt–Pd bimetallic alloy catalysts. The preparation methods, normal wet impregnation technique and flame aerosol synthesis, obtained metal loadings of 2% by weight. The prepared catalysts were tested for SO2 oxidation...... activity at atmospheric pressure in the temperature range 250–600 °C. The SO2 to SO3 conversion efficiency of the Pt–Pd alloy was significantly higher than that of the individual metals. The effects of the preparation method and the titania type used on the properties and activity of the resulting catalyst...

  15. Hybrid Dye-Sensitized Solar Cells Consisting of Double Titania Layers for Harvesting Light with Wide Range of Wavelengths

    Science.gov (United States)

    Sadamasu, Kengo; Inoue, Takafumi; Ogomi, Yuhei; Pandey, Shyam S.; Hayase, Shuzi

    2011-02-01

    We report a hybrid dye-sensitized solar cell consisting of double titania layers (top and bottom layers) stained with two dyes. A top layer fabricated on a glass was mechanically pressed with a bottom layer fabricated on a glass cloth. The glass cloth acts as a supporter of a porous titania layer as well as a holder of electrolyte. The incident photon to current efficiency (IPCE) curve had two peaks corresponding to those of the two dyes, which demonstrates that electrons are collected from both the top and bottom layers.

  16. Photocatalysis of methylene blue contaminated water using titania fiber doped with silicon; Fotocatalise de aguas contaminadas com azul de metileno utilizando fibras de titania dopadas com silicio

    Energy Technology Data Exchange (ETDEWEB)

    Ugarteche, C.V.; Alves, A.K.; Berutti, F.A.; Bergmann, C.P. [Universidade Federal do Rio Grande do Sul (LACER/UFRGS), Porto Alegre, RS (Brazil). Lab. de Materiais Ceramicos

    2009-07-01

    In this work, titania fibers doped with silicon were synthesized by electro spinning methodology, using titanium propoxide, silicon tetra propoxide and a solution of polyvinylpyrrolidone as precursors. The non-tissue material obtained was characterized by X-ray diffraction to determine the phase and crystallite size, BET method to determine the surface and SEM to analyze the microstructure of the fibers. The photo catalytic activity of the fibers in comparison with the standard TiO{sub 2} Degussa P25 was evaluated using a 20ppm methylene blue solution. The composition containing 30% of silicon kept the anatase phase stable until the heat treatment temperature of 800 deg C. In the other compositions there was a formation of the rutile phase, which is less photoactive. The compositions containing silicon were photo catalytic efficient and some of them were more active that the standard P25. (author)

  17. Synthesizing new types of ultrathin 2D metal oxide nanosheets via half-successive ion layer adsorption and reaction

    Science.gov (United States)

    Gao, Linjie; Li, Yaguang; Xiao, Mu; Wang, Shufang; Fu, Guangsheng; Wang, Lianzhou

    2017-06-01

    Two-dimensional (2D) metal oxide nanosheets have demonstrated their great potential in a broad range of applications. The existing synthesis strategies are mainly preparing 2D nanosheets from layered and specific transition metal oxides. How to prepare the other types of metal oxides as ultrathin 2D nanosheets remains unsolved, especially for metal oxides containing alkali, alkaline earth metal, and multiple metal elements. Herein, we developed a half-successive ion layer adsorption and reaction (SILAR) method, which could synthesize those types of metal oxides as ultrathin 2D nanosheets. The synthesized 2D metal oxides nanosheets are within 1 nm level thickness and 500 m2 · g-1 level surface area. This method allows us to develop many new types of ultrathin 2D metal oxides nanosheets that have never been prepared before.

  18. Effective coating of titania nanoparticles with alumina via atomic layer deposition

    Science.gov (United States)

    Azizpour, H.; Talebi, M.; Tichelaar, F. D.; Sotudeh-Gharebagh, R.; Guo, J.; van Ommen, J. R.; Mostoufi, N.

    2017-12-01

    Alumina films were deposited on titania nanoparticles via atomic layer deposition (ALD) in a fluidized bed reactor at 180 °C and 1 bar. Online mass spectrometry was used for real time monitoring of effluent gases from the reactor during each reaction cycle in order to determine the optimal dosing time of precursors. Different oxygen sources were used to see which oxygen source, in combination with trimethyl aluminium (TMA), provides the highest alumina growth per cycle (GPC). Experiments were carried out in 4, 7 and 10 cycles using the optimal dosing time of precursors. Several characterization methods, such as high resolution transmission electron microscopy (HRTEM), Brunauer-Emmett-Teller (BET), energy dispersive X-ray spectroscopy (EDX), Fourier transform infrared (FTIR), X-ray diffraction (XRD) and instrumental neutron activation analysis (INAA), were conducted on the products. Formation of the alumina film was confirmed by EDX mapping and EDX line profiling, FTIR and TEM. When using either water or deuterium oxide as the oxygen source, the thickness of the alumina film was greater than that of ozone. The average GPC measured by TEM for the ALD of TMA with water, deuterium oxide and ozone was about 0.16 nm, 0.15 nm and 0.11 nm, respectively. The average GPC calculated using the mass fraction of aluminum from INAA was close to those measured from TEM images. Excess amounts of precursors lead to a higher average growth of alumina film per cycle due to insufficient purging time. XRD analysis demonstrated that amorphous alumina was coated on titania nanoparticles. This amorphous layer was easily distinguished from the crystalline core in the TEM images. Decrease in the photocatalytic activity of titania nanoparticles after alumina coating was confirmed by measuring degradation of Rhodamine B by ultraviolet irradiation.

  19. Fabrication of Self-Cleaning, Reusable Titania Templates for Nanometer and Micrometer Scale Protein Patterning.

    Science.gov (United States)

    Moxey, Mark; Johnson, Alexander; El-Zubir, Osama; Cartron, Michael; Dinachali, Saman Safari; Hunter, C Neil; Saifullah, Mohammad S M; Chong, Karen S L; Leggett, Graham J

    2015-06-23

    The photocatalytic self-cleaning characteristics of titania facilitate the fabrication of reuseable templates for protein nanopatterning. Titania nanostructures were fabricated over square centimeter areas by interferometric lithography (IL) and nanoimprint lithography (NIL). With the use of a Lloyd's mirror two-beam interferometer, self-assembled monolayers of alkylphosphonates adsorbed on the native oxide of a Ti film were patterned by photocatalytic nanolithography. In regions exposed to a maximum in the interferogram, the monolayer was removed by photocatalytic oxidation. In regions exposed to an intensity minimum, the monolayer remained intact. After exposure, the sample was etched in piranha solution to yield Ti nanostructures with widths as small as 30 nm. NIL was performed by using a silicon stamp to imprint a spin-cast film of titanium dioxide resin; after calcination and reactive ion etching, TiO2 nanopillars were formed. For both fabrication techniques, subsequent adsorption of an oligo(ethylene glycol) functionalized trichlorosilane yielded an entirely passive, protein-resistant surface. Near-UV exposure caused removal of this protein-resistant film from the titania regions by photocatalytic degradation, leaving the passivating silane film intact on the silicon dioxide regions. Proteins labeled with fluorescent dyes were adsorbed to the titanium dioxide regions, yielding nanopatterns with bright fluorescence. Subsequent near-UV irradiation of the samples removed the protein from the titanium dioxide nanostructures by photocatalytic degradation facilitating the adsorption of a different protein. The process was repeated multiple times. These simple methods appear to yield durable, reuseable samples that may be of value to laboratories that require nanostructured biological interfaces but do not have access to the infrastructure required for nanofabrication.

  20. Adsorption and degradation of model volatile organic compounds by a combined titania-montmorillonite-silica photocatalyst

    International Nuclear Information System (INIS)

    Chen Jiangyao; Li Guiying; He Zhigui; An Taicheng

    2011-01-01

    Highlights: → Adsorptive combined titania-montmorillonite-silica photocatalysts synthesized. → All catalysts had relatively high adsorption capacities of multinary VOCs. → All catalysts preferred to adsorb the VOCs with higher polarity. → CTMS80 can effectively photocatalytically remove VOCs of various components. - Abstract: A series of adsorptive photocatalysts, combined titania-montmorillonite-silica were synthesized. The resultant photocatalysts consisted of more and more spherically agglomerated TiO 2 particles with increasing of TiO 2 content, and anatase was the only crystalline phase with nano-scale TiO 2 particles. With increasing of the cation exchange capacity to TiO 2 molar ratio, specific surface area and pore volume increased very slightly. In a fluidized bed photocatalytic reactor by choosing toluene, ethyl acetate and ethanethiol as model pollutants, all catalysts had relatively high adsorption capacities and preferred to adsorb higher polarity pollutants. Langmuir isotherm model better described equilibrium data compared to Freundlich model. Competitive adsorptions were observed for the mixed pollutants on the catalysts, leading to decrease adsorption capacity for each pollutant. The combined titania-montmorillonite-silica photocatalyst exhibited excellent photocatalytic removal ability to model pollutants of various components. Almost 100% of degradation efficiency was achieved within 120 min for each pollutant with about 500 ppb initial concentration, though the efficiencies of multi-component compounds slightly decreased. All photocatalytic reactions followed the Langmuir-Hinshelwood model. Degradation rate constants of multi-component systems were lower than those for single systems, following the order of toluene < ethyl acetate < ethanethiol, and increased with the increase of adsorption capacities for different pollutants of various components.

  1. Few-layered MoSe2 nanosheets as an advanced electrode material for supercapacitors.

    Science.gov (United States)

    Balasingam, Suresh Kannan; Lee, Jae Sung; Jun, Yongseok

    2015-09-21

    We report the synthesis of few-layered MoSe2 nanosheets using a facile hydrothermal method and their electrochemical charge storage behavior. A systematic study of the structure and morphology of the as-synthesized MoSe2 nanosheets was performed. The downward peak shift in the Raman spectrum and the high-resolution transmission electron microscopy images confirmed the formation of few-layered nanosheets. The electrochemical energy-storage behavior of MoSe2 nanosheets was also investigated for supercapacitor applications in a symmetric cell configuration. The MoSe2 nanosheet electrode exhibited a maximum specific capacitance of 198.9 F g(-1) and the symmetric device showed 49.7 F g(-1) at a scan rate of 2 mV s(-1). A capacitance retention of approximately 75% was observed even after 10 000 cycles at a high charge-discharge current density of 5 A g(-1). The two-dimensional MoSe2 nanosheets exhibited a high specific capacitance and good cyclic stability, which makes it a promising electrode material for supercapacitor applications.

  2. A facile homogeneous precipitation synthesis of NiO nanosheets and their applications in water treatment

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Junfeng, E-mail: daidai02304@163.com [School of Chemistry and Materials Engineering, Changshu Institute of Technology, Changshu (China); Jiangsu Laboratory of Advanced Functional Materials, Changshu Institute of Technology, Changshu (China); Tan, Yang; Su, Kang; Zhao, Junjie; Yang, Chen; Sang, Lingling [School of Chemistry and Materials Engineering, Changshu Institute of Technology, Changshu (China); Lu, Hongbin [National Laboratory of Solid State Microstructures and College of Engineering and Applied Sciences, Nanjing University, Nanjing (China); Chen, JianHua [School of Chemistry and Materials Engineering, Changshu Institute of Technology, Changshu (China); Jiangsu Laboratory of Advanced Functional Materials, Changshu Institute of Technology, Changshu (China)

    2015-05-15

    Highlights: • NiO nanosheets were synthesized via a facile homogeneous precipitation method. • The NiO nanosheets have a large surface area. • This preparation method was low-cost, simple equipments, easy preparation, short reaction time and better repeatability. • The product also showed a favourable ability to remove Cr(VI) and Congo red (CR) in water treatment. - Abstract: NiO nanosheets were successfully synthesized by a facile homogeneous precipitation method with the assistance of ethanol amine. The sample was characterized by X-ray diffraction (XRD), scanning electronic microscopy (SEM), transmission electron microscopy (TEM), and nitrogen adsorption–desorption techniques. The results demonstrated that the as-prepared product was cubic NiO nanosheets with a large surface area of 170.1 m{sup 2} g{sup −1}. Further, the as-prepared product was used to investigate its potential application for wastewater treatment. The maximum adsorption capacity for Cr(VI) and Congo red (CR) on NiO nanosheets has been determined using the Langmuir equation and found to reach up to 48.98 and 167.73 mg g{sup −1}, respectively. It could be concluded that NiO nanosheets with special surface features had the potential as adsorbents for wastewater treatment.

  3. Morphological Evolution of Vertically Standing Molybdenum Disulfide Nanosheets by Chemical Vapor Deposition.

    Science.gov (United States)

    Zhang, Song; Liu, Jiajia; Ruiz, Karla Hernandez; Tu, Rong; Yang, Meijun; Li, Qizhong; Shi, Ji; Li, Haiwen; Zhang, Lianmeng; Goto, Takashi

    2018-04-20

    In this study, we demonstrated the chemical vapor deposition (CVD) of vertically standing molybdenum disulfide (MoS₂) nanosheets, with an unconventional combination of molybdenum hexacarbonyl (Mo(CO)₆) and 1,2-ethanedithiol (C₂H₆S₂) as the novel kind of Mo and S precursors respectively. The effect of the distance between the precursor’s outlet and substrates (denoted as d ) on the growth characteristics of MoS₂, including surface morphology and nanosheet structure, was investigated. Meanwhile, the relationship between the structure characteristics of MoS₂ nanosheets and their catalytic performance for hydrogen evolution reaction (HER) was elucidated. The formation of vertically standing nanosheets was analyzed and verified by means of an extrusion growth model. The crystallinity, average length, and average depth between peak and valley ( R z) of MoS₂ nanosheets differed depending on the spatial location of the substrate. Good crystalized MoS₂ nanosheets grown at d = 5.5 cm with the largest average length of 440 nm, and the highest R z of 162 nm contributed to a better HER performance, with a respective Tafel slope and exchange current density of 138.9 mV/decade, and 22.6 μA/cm² for raw data (127.8 mV/decade and 19.3 μA/cm² for iR-corrected data).

  4. Gold Nanoparticles on Layered Double Hydroxide Nanosheets and Its Electrocatalysis for Glucose Oxidation

    Energy Technology Data Exchange (ETDEWEB)

    Cho, Hye Ran; Lee, Jong Hyeon [The Catholic University of Korea, Bucheon (Korea, Republic of); Cho, Se Hee; Ji, Hong Geun [H and A PharmaChem, Bucheon (Korea, Republic of)

    2016-03-15

    We developed a new way to form the well-defined nanocomposite of Au NPs and exfoliated LDH nanosheet by in situ chemical reduction with NaBH{sub 4}. The optical and structural studies indicate that the Au NPs are highly dispersed and immobilized on the surface of LDH nanosheets. The Au/LDH nanosheet exhibited an excellent electrocatalysis toward glucose oxidation reaction. The results strongly demonstrate that the nanoscopic natures and dense positive charges of LDH nanosheet effectively stabilized the Au NPs to maintain their inherent properties during the synthesis and the electrocatalysis. The use of the double hydroxide nanosheets as nanoscopic support materials for the transition-metal NPs will dramatically improve their functionalities in heterogeneous catalysis. Recently, two-dimensional nanosheet of exfoliated layered double hydroxide (LDH) has emerged as a new type of solid support to immobilize the diverse metal NPs because of the large metal hydroxide area, good biochemical stability, and highly charged positive potential of 1- to 2-nm thick LDH layers. LDHs consist of a continuous stack of positively charged metal hydroxide layers with counter anions and water molecules placed in interlayer spaces.

  5. Nanostructural evolution from nanosheets to one-dimensional nanoparticles for manganese oxide

    International Nuclear Information System (INIS)

    Pan, Hongmei; Kong, Xingang; Wen, Puhong; Kitayama, Tomonori; Feng, Qi

    2012-01-01

    Highlights: ► Nanosheets were transformed to other one-dimensional nanoparticles. ► Nanofibers, nanotubes, nanoribbons, and nanobelts were obtained. ► Nanoparticle morphology can be controlled with organic amines. ► Organic amines act as morphology directing agent. -- Abstract: This paper introduces a novel hydrothermal soft chemical synthesis process for manganese oxide nanostructured particles using two-dimensional manganese oxide nanosheets as precursor. In this process, a birnessite-type manganese oxide with a layered structure was exfoliated into its elementary layer nanosheets, and then the nanosheets were hydrothermally treated to transform the two-dimensional morphology of the nanosheets to one-dimensional nanoparticles. The manganese oxide nanofibers, nanotubes, nanobelts, nanoribbons, and fabric-ribbon-like particles constructed from nanofibers or nanobelts were obtained using this hydrothermal soft chemical process. The nanostructural evolution from the two-dimensional nanosheets to the one-dimensional nanoparticles was characterized by XRD, SEM, TEM, and TG-DTA analysis. The morphology and nanostructure of the products are strongly dependent on the molecular dimension of organic amine cations added in the reaction system. The organic amine cations act as a morphology directing agent in the nanostructural evolution process.

  6. Preparation and supercapacitance performance of manganese oxide nanosheets/graphene/carbon nanotubes ternary composite film

    International Nuclear Information System (INIS)

    Tang, Qianqiu; Sun, Minqiang; Yu, Shuangmin; Wang, Gengchao

    2014-01-01

    Graphical abstract: - Highlights: • The MnO 2 nanosheets/graphene/MWCNT composite film with a porous sandwich structure was fabricated through a filtration-directed self-assembly. • The introduction of graphene and MWCNT restricts dense stacking of MnO 2 nanosheets. • Ternary composite film exhibits impressive electrochemical performance compared to pure MnO 2 nanosheets. - Abstract: A novel MnO 2 nanosheets/graphene nanosheets/carboxylic multi-walled carbon nanotubes (MONS/GNS/cMWCNT) ternary composite film was fabricated through a filtration-directed self-assembly method. The Field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM) images showed the porous sandwiched structure of MONS/GNS/cMWCNT with GNS providing a conductive substrate and cMWCNT functioning as a vertical electron pathway. The X-ray diffraction (XRD) and Raman spectra further confirmed that the introduction of GNS and cMWCNT restricted the serious aggregation of MONS, resulting in a higher specific area (691 m 2 g −1 ). As a result, the MONS/GNS/cMWCNT composite film exhibited higher specific capacitance (248 Fg −1 at 1 Ag −1 in 1 M Na 2 SO 4 ), better rate performance (66.9% capacitance retention from 0.2 to 10 Ag −1 ) and cycling stability (86.5% retention after 3000 cycles) compared with those of pure dried MnO 2 nanosheets

  7. Photovoltaic behaviour of titanyl phthalocyanine thin films and titania bilayer films

    Czech Academy of Sciences Publication Activity Database

    Drabik, M.; Zachary, A. M.; Choi, Y.; Hanuš, J.; Toušek, J.; Toušková, J.; Cimrová, Věra; Slavinská, D.; Biederman, H.; Hanley, L.

    2008-01-01

    Roč. 268, č. 1 (2008), s. 57-60 ISSN 1022-1360. [Microsymposium on Advanced Polymer Materials for Photonics and Electronics /47./. Prague, 15.07.2007-19.07.2007] R&D Projects: GA MŠk(CZ) 1M06031 Grant - others:National Science Foundation(US) CHE0241425; GA MŠk(CZ) 1P05ME754 Institutional research plan: CEZ:AV0Z40500505 Keywords : conjugated polymers * photovoltaics * phthalocyanine * thin films * titania Subject RIV: BM - Solid Matter Physics ; Magnetism

  8. Primary role of electron work function for evaluation of nanostructured titania implant surface against bacterial infection

    Energy Technology Data Exchange (ETDEWEB)

    Golda-Cepa, M., E-mail: golda@chemia.uj.edu.pl [Faculty of Chemistry, Jagiellonian University, Ingardena 3, 30-060 Krakow (Poland); Syrek, K. [Faculty of Chemistry, Jagiellonian University, Ingardena 3, 30-060 Krakow (Poland); Brzychczy-Wloch, M. [Department of Bacteriology, Microbial Ecology and Parasitology, Jagiellonian University Medical College, Czysta 18, 31-121 Krakow (Poland); Sulka, G.D. [Faculty of Chemistry, Jagiellonian University, Ingardena 3, 30-060 Krakow (Poland); Kotarba, A., E-mail: kotarba@chemia.uj.edu.pl [Faculty of Chemistry, Jagiellonian University, Ingardena 3, 30-060 Krakow (Poland)

    2016-09-01

    The electron work function as an essential descriptor for the evaluation of metal implant surfaces against bacterial infection is identified for the first time. Its validity is demonstrated on Staphylococcus aureus adhesion to nanostructured titania surfaces. The established correlation: work function–bacteria adhesion is of general importance since it can be used for direct evaluation of any electrically conductive implant surfaces. - Highlights: • The correlation between work function and bacteria adhesion was discovered. • The discovered correlation is rationalized in terms of electrostatic bacteria–surface repulsion. • The results provide basis for the simple evaluation of implant surfaces against infection.

  9. Efficacy of radiosensitizing doped titania nanoparticles under hypoxia and preparation of an embolic microparticle

    Directory of Open Access Journals (Sweden)

    Morrison RA

    2017-05-01

    Full Text Available Rachel A Morrison,1,* Malgorzata J Rybak-Smith,1,* James M Thompson,2 Bénédicte Thiebaut,3 Mark A Hill,2 Helen E Townley1,4 1Department of Engineering Science, 2Gray Laboratories, CRUK/MRC Oxford Institute for Radiation Oncology, University of Oxford, Oxford, 3Johnson Matthey, Technology Centre, Reading, Berkshire, 4Nuffield Department of Obstetrics and Gynaecology, John Radcliffe Hospital, University of Oxford, Oxford, UK *These authors have contributed equally to this work Abstract: The aim of this study was to develop a manufacturing protocol for large-scale production of doped titania radiosensitizing nanoparticles (NPs to establish their activity under hypoxia and to produce a multimodal radiosensitizing embolic particle for cancer treatment. We have previously shown that radiosensitizing NPs can be synthesized from titania doped with rare earth elements, especially gadolinium. To translate this technology to the clinic, a crucial step is to find a suitable, scalable, high-throughput method. Herein, we have described the use of flame spray pyrolysis (FSP to generate NPs from titanium and gadolinium precursors to produce titania NPs doped with 5 at% gadolinium. The NPs were fully characterized, and their capacity to act as radiosensitizers was confirmed by clonogenic assays. The integrity of the NPs in vitro was also ascertained due to the potentially adverse effects of free gadolinium in the body. The activity of the NPs was then studied under hypoxia since this is often a barrier to effective radiotherapy. In vitro radiosensitization experiments were performed with both the hypoxia mimetics deferoxamine and cobalt chloride and also under true hypoxia (oxygen concentration of 0.2%. It was shown that the radiosensitizing NPs were able to cause a significant increase in cell death even after irradiation under hypoxic conditions such as those found in tumors. Subsequently, the synthesized NPs were used to modify polystyrene embolization

  10. Optical and electrical characterizations of nanocomposite film of titania adsorbed onto oxidized multiwalled carbon nanotubes

    International Nuclear Information System (INIS)

    Feng Wei; Feng Yiyu; Wu Zigang; Fujii, Akihiko; Ozaki, Masanori; Yoshino, Katsumi

    2005-01-01

    Composite film containing titania electrostatically linked to oxidized multiwalled carbon nanotubes (TiO 2 -s-MWNTs) was prepared from a suspension of TiO 2 nanoparticles in soluble carbon nanotubes. The structure of the film was analysed principally by Fourier transform infrared spectroscopy, scanning electron micrography and x-ray diffraction. The optical and electrical characterizations of the film were investigated by UV-vis spectrum, photoluminescence and photoconductivity. The enhancement of photocurrent in the TiO 2 -s-MWNT film is discussed by taking the photoinduced charge transfer between the MWNT and TiO 2 into consideration

  11. Experimental Study on Indoor Air Cleaning Technique of Nano-Titania Catalysis Under Plasma Discharge

    International Nuclear Information System (INIS)

    Gao Deli; Yang Xuechang; Zhou Fei; Wu Yuhuang

    2008-01-01

    In this study, a new technique of air cleaning by plasma combined with catalyst was proposed, which consisted of electrostatic precipitation, volatile organic compounds (VOCs) decomposition and sterilization. A novel indoor air purifier based on this technique was adopted. The experimental results showed that formaldehyde decomposition by the plasma-catalyst hybrid system was more efficient than that by plasma only. Positive discharge was better than negative discharge in formaldehyde removal. Meanwhile, the outlet concentration of ozone byproduct was effectively reduced by the nano-titania catalyst.

  12. Reactive magnetron sputtering deposition of bismuth tungstate onto titania nanoparticles for enhancing visible light photocatalytic activity

    Energy Technology Data Exchange (ETDEWEB)

    Ratova, Marina, E-mail: marina_ratova@hotmail.com [Surface Engineering Group, School of Engineering, Manchester Metropolitan University, Manchester, M1 5GD (United Kingdom); Kelly, Peter J.; West, Glen T. [Surface Engineering Group, School of Engineering, Manchester Metropolitan University, Manchester, M1 5GD (United Kingdom); Tosheva, Lubomira; Edge, Michele [School of Science and the Environment, Manchester Metropolitan University, Manchester M1 5GD (United Kingdom)

    2017-01-15

    Highlights: • Bismuth tungstate coatings were deposited by reactive magnetron sputtering. • Oscillating bowl was introduced to the system to enable coating of nanopartulates. • Deposition of Bi{sub 2}WO{sub 6} enhanced visible light activity of titania nanoparticles. • The best results were obtained for coating with Bi:W ratio of approximately 2:1. • Deposition of Bi{sub 2}WO{sub 6} onto TiO{sub 2} resulted in more efficient electron-hole separation. - Abstract: Titanium dioxide − bismuth tungstate composite materials were prepared by pulsed DC reactive magnetron sputtering of bismuth and tungsten metallic targets in argon/oxygen atmosphere onto anatase and rutile titania nanoparticles. The use of an oscillating bowl placed beneath the two magnetrons arranged in a co-planar closed field configuration enabled the deposition of bismuth tungstate onto loose powders, rather than a solid substrate. The atomic ratio of the bismuth/tungsten coatings was controlled by varying the power applied to each target. The effect of the bismuth tungstate coatings on the phase, optical and photocatalytic properties of titania was investigated by X-ray diffraction, energy-dispersive X-ray spectroscopy (EDX), Brunauer–Emmett–Teller (BET) surface area measurements, transmission electron microscopy (TEM), UV–vis diffuse reflectance spectroscopy and an acetone degradation test. The latter involved measurements of the rate of CO{sub 2} evolution under visible light irradiation of the photocatalysts, which indicated that the deposition of bismuth tungstate resulted in a significant enhancement of visible light activity, for both anatase and rutile titania particles. The best results were achieved for coatings with a bismuth to tungsten atomic ratio of 2:1. In addition, the mechanism by which the photocatalytic activity of the TiO{sub 2} nanoparticles was enhanced by compounding it with bismuth tungstate was studied by microwave cavity perturbation. The results of these

  13. Primary role of electron work function for evaluation of nanostructured titania implant surface against bacterial infection

    International Nuclear Information System (INIS)

    Golda-Cepa, M.; Syrek, K.; Brzychczy-Wloch, M.; Sulka, G.D.; Kotarba, A.

    2016-01-01

    The electron work function as an essential descriptor for the evaluation of metal implant surfaces against bacterial infection is identified for the first time. Its validity is demonstrated on Staphylococcus aureus adhesion to nanostructured titania surfaces. The established correlation: work function–bacteria adhesion is of general importance since it can be used for direct evaluation of any electrically conductive implant surfaces. - Highlights: • The correlation between work function and bacteria adhesion was discovered. • The discovered correlation is rationalized in terms of electrostatic bacteria–surface repulsion. • The results provide basis for the simple evaluation of implant surfaces against infection.

  14. Aging effects on vertical graphene nanosheets and their thermal stability

    Science.gov (United States)

    Ghosh, S.; Polaki, S. R.; Ajikumar, P. K.; Krishna, N. G.; Kamruddin, M.

    2018-03-01

    The present study investigates environmental aging effects and thermal stability of vertical graphene nanosheets (VGN). Self-organized VGN is synthesized by plasma enhanced chemical vapor deposition and exposed to ambient conditions over 6-month period to examine its aging behavior. A systematic inspection is carried out on morphology, chemical structure, wettability and electrical property by scanning electron microscopy, Raman spectroscopy, X-ray photoelectron spectroscopy, water contact angle and four-probe resistivity measurements at regular intervals, respectively. Detailed microscopic and spectroscopic analysis substantiated the retention of graphitic quality and surface chemistry of VGN over the test period. An unchanged sheet resistance and hydrophobicity reveals its electrical and wetting stability over the time, respectively. Thermogravimetric analysis ensures an excellent thermal stability of VGN up to 575 °C in ambient atmosphere. These findings of long-term morphological, structural, wetting, electrical and thermal stability of VGN validate their potential utilization for the next-generation device applications.

  15. Band structure of hydrogenated Si nanosheets and nanotubes

    International Nuclear Information System (INIS)

    Guzman-Verri, G G; Lew Yan Voon, L C

    2011-01-01

    The band structures of fully hydrogenated Si nanosheets and nanotubes are elucidated by the use of an empirical tight-binding model. The hydrogenated Si sheet is a semiconductor with an indirect band gap of about 2.2 eV. The symmetries of the wavefunctions allow us to explain the origin of the gap. We predict that, for certain chiralities, hydrogenated Si nanotubes represent a new type of semiconductor, one with coexisting direct and indirect gaps of exactly the same magnitude. This behavior is different from that governed by the Hamada rule established for non-hydrogenated carbon and silicon nanotubes. A comparison to the results of an ab initio calculation is made.

  16. Synthesis, characterization and performance of NiMo catalysts supported on titania modified alumina for the hydroprocessing of different gas oils derived from Athabasca bitumen

    Energy Technology Data Exchange (ETDEWEB)

    Ferdous, D.; Bakhshi, N.N.; Dalai, A.K. [Catalysis and Chemical Reactor Engineering Laboratories, Department of Chemical Engineering, University of Saskatchewan, 57 Campus Drive, Saskatoon, Sask. (Canada); Adjaye, J. [Syncrude Canada Ltd., Edmonton Research Center, No. 9421, 17th Avenue, Edmonton, Alta. (Canada)

    2007-03-08

    In this work, a series of NiMo/Al{sub 2}O{sub 3} catalyst was prepared using different Al{sub 2}O{sub 3} supports modified by titania (0-9 wt%). All modified supports and fresh catalysts were characterized by BET surface area, pore volume and pore diameter measurement, TPR, TPD, XRD, FTIR and Raman spectroscopy analyses. The initial activity of these catalysts were tested in a trickle-bed reactor using three different gas oils such as light gas oil (LGO), blended gas oil (blended: 50% LGO and 50% HGO) and heavy gas oil (HGO), all derived from Athabasca bitumen. Little structural change in alumina was observed with the incorporation of titania. XRD analysis showed the well dispersion of Ni and Mo on the support. Titania in alumina increased the formation of polymolybdenum oxide on the catalyst as evident from TPR and Raman analyses. Weak-intermediate-strong acid sites on the catalyst were observed at all titania concentrations. The Lewis and Bronsted acidity on the catalyst surface increased with the increase in titania concentration from 0 to 9 wt%. Nitrogen conversion increased from 57 to 71 wt%, from 83 to 93 wt% and from 75 to 80 wt% for LGO, blended and HGO, respectively and also sulfur conversion of LGO increased from 86 to 92 wt% when titania concentration was increased from 0 to 9 wt%. For blended and HGO, sulfur conversion was in the range 96-99 wt% at all titania concentrations. (author)

  17. THE EFFECT OF NANO-TITANIA ADDITION ON THE PROPERTIES OF HIGH-ALUMINA LOW-CEMENT SELF-FLOWING REFRACTORY CASTABLES

    Directory of Open Access Journals (Sweden)

    Sasan Otroj

    2011-12-01

    Full Text Available The self-flow characteristics and properties of high-alumina low-cement refractory castables added with nano-titania particles are investigated. For this reason, the reactive alumina in the castable composition is substituted by nano-titania powder in 0-1 %wt. range. The microstructures, phase composition, physical and mechanical properties of these refractory castables at different temperatures are studied. The results show that the addition of nano-titania particles has great effect on the self-flow characteristics, phase composition, physical and mechanical properties of these refractory castables. With increase of nano-titania particles in castable composition, the self-flow value and working time tend to decrease. With addition of 0.5 wt.% nano-titania in the castable composition, the mechanical strength of castable in all firing temperatures tends to increase. It is attributed to the formation of CA6 phase and enhanced ceramic bonding. Nano-titania particles can act as a nucleating agent for hibonite phase and decrease the formation temperature of hibonite. Because of perovskite phase formation, the addition of 1 wt.% nano-titania can decrease the mechanical strength of castable after firing.

  18. (Gold core)/(titania shell) nanostructures for plasmon-enhanced photon harvesting and generation of reactive oxygen species

    KAUST Repository

    Fang, Caihong; Jia, Henglei; Chang, Shuai; Ruan, Qifeng; Wang, Peng; Chen, Tao; Wang, Jianfang

    2014-01-01

    Integration of gold and titania in a nanoscale core/shell architecture can offer large active metal/semiconductor interfacial areas and avoid aggregation and reshaping of the metal nanocrystal core. Such hybrid nanostructures are very useful for studying plasmon-enhanced/enabled processes and have great potential in light-harvesting applications. Herein we report on a facile route to (gold nanocrystal core)/(titania shell) nanostructures with their plasmon band synthetically variable from ∼700 nm to over 1000 nm. The coating method has also been applied to other mono- and bi-metallic Pd, Pt, Au nanocrystals. The gold/titania nanostructures have been employed as the scattering layer in dye-sensitized solar cells, with the resultant cells exhibiting a 13.3% increase in the power conversion efficiency and a 75% decrease in the scattering-layer thickness. Moreover, under resonant excitation, the gold/titania nanostructures can efficiently utilize low-energy photons to generate reactive oxygen species, including singlet oxygen and hydroxyl radicals.

  19. 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.

  20. The Effect of Type and Concentration of Modifier in Supercritical Carbon Dioxide on Crystallization of Nanocrystalline Titania Thin Films.

    Czech Academy of Sciences Publication Activity Database

    Sajfrtová, Marie; Cerhová, Marie; Jandová, Věra; Dřínek, Vladislav; Daniš, E.; Matějová, L.

    2018-01-01

    Roč. 133, MAR 2018 (2018), s. 211-217 ISSN 0896-8446 R&D Projects: GA ČR GA14-23274S Institutional support: RVO:67985858 Keywords : titania thin film * supercritical carbon dioxide * crystallization Subject RIV: CF - Physical ; Theoretical Chemistry OBOR OECD: Physical chemistry Impact factor: 2.991, year: 2016

  1. Multistack integration of three-dimensional hyperbranched anatase titania architectures for high-efficiency dye-sensitized solar cells.

    Science.gov (United States)

    Wu, Wu-Qiang; Xu, Yang-Fan; Rao, Hua-Shang; Su, Cheng-Yong; Kuang, Dai-Bin

    2014-04-30

    An unprecedented attempt was conducted on suitably functionalized integration of three-dimensional hyperbranched titania architectures for efficient multistack photoanode, constructed via layer-by-layer assembly of hyperbranched hierarchical tree-like titania nanowires (underlayer), branched hierarchical rambutan-like titania hollow submicrometer-sized spheres (intermediate layer), and hyperbranched hierarchical urchin-like titania micrometer-sized spheres (top layer). Owing to favorable charge-collection, superior light harvesting efficiency and extended electron lifetime, the multilayered TiO2-based devices showed greater J(sc) and V(oc) than those of a conventional TiO2 nanoparticle (TNP), and an overall power conversion efficiency of 11.01% (J(sc) = 18.53 mA cm(-2); V(oc) = 827 mV and FF = 0.72) was attained, which remarkably outperformed that of a TNP-based reference cell (η = 7.62%) with a similar film thickness. Meanwhile, the facile and operable film-fabricating technique (hydrothermal and drop-casting) provides a promising scheme and great simplicity for high performance/cost ratio photovoltaic device processability in a sustainable way.

  2. Polyaniline nanowire array encapsulated in titania nanotubes as a superior electrode for supercapacitors

    Science.gov (United States)

    Xie, Keyu; Li, Jie; Lai, Yanqing; Zhang, Zhi'an; Liu, Yexiang; Zhang, Guoge; Huang, Haitao

    2011-05-01

    Conducting polymer with 1D nanostructure exhibits excellent electrochemical performances but a poor cyclability that limits its use in supercapacitors. In this work, a novel composite electrode made of polyaniline nanowire-titania nanotube array was synthesized via a simple and inexpensive electrochemical route by electropolymerizing aniline onto an anodized titania nanotube array. The specific capacitance was as high as 732 F g-1 at 1 A g-1, which remained at 543 F g-1 when the current density was increased by 20 times. 74% of the maximum energy density (36.6 Wh kg-1) was maintained even at a high power density of 6000 W kg-1. An excellent long cycle life of the electrode was observed with a retention of ~86% of the initial specific capacitance after 2000 cycles. The good electrochemical performance was attributed to the unique microstructure of the electrode with disordered PANI nanowire arrays encapsulated inside the TiO2 nanotubes, providing high surface area, fast diffusion path for ions and long-term cycle stability. Such a nanocomposite electrode is attractive for supercapacitor applications.

  3. Composite templates synthesis of mesoporous titania from industrial titanyl sulfate solution under external outfields

    International Nuclear Information System (INIS)

    Tian Congxue

    2008-01-01

    The precursors of mesoporous titania were synthesized via supra-molecular self-assembly route induced by composite templates (CTAB/P-123) from industrial titanyl sulfate solution under ultrasonic irradiation, microwave and hydrothermal condition. The hydrolysis and polycondensation rates of TiOSO 4 solution were controlled by adjusting the pH value at about 1.0. Mesoporous titania with anatase phase was obtained after templates removal by calcinations. The as-prepared powder was characterized by X-ray diffraction (XRD), N 2 isothermal adsorption-desorption, HRTEM and SAD. External outfields with enhancing polar action and soft hydrothermal condition were beneficial to prepare better mesoporous TiO 2 . Ultrasonic vibration promoted the formation of mesoporous structure. Under microwave irradiation, mesoporous TiO 2 was synthesized with BET specific surface area of 190.6 m 2 g -1 , average pore diameter of 2.57 nm and crystal size of 13.65 nm. And ultrasonic irradiation, microwave and hydrothermal conditions were making for forming and stabilizing the mesoporous structure

  4. Anodic Titania Nanotube Arrays Sensitized with Mn- or Co-Doped CdS Nanocrystals

    International Nuclear Information System (INIS)

    Smith, York R.; Gakhar, Ruchi; Merwin, Augustus; Mohanty, Swomitra K.; Chidambaram, Dev; Misra, Mano

    2014-01-01

    Highlights: • Mn or Co doped CdS where synthesized and deposited onto TiO 2 nanotubular arrays. • Synthesis and deposition were achieved simultaneously using SILAR method. • Various characterization techniques demonstrate lattice incorporation of dopant. • Photoelectrochemical performance was analyzed using AM 1.5 irradiation. • Dopants increases depletion width of CdS and increase photoelectrochemical responses. - Abstract: The use of doped luminescent nanocrystals or quantum dots have mainly been explored for imaging applications; however, recently they have gained interest in solar energy conversion applications due to long electron lifetimes, tunable band gaps and emission by compositional control. In this study, we have examined the application of Mn or Co doped CdS nanocrystals as a sensitizing layer over titania nanotubular arrays synthesized via electrochemical anodization in photoelectrochemical applications. The doped and undoped CdS nanocrystals were simultaneously synthesized and deposited onto the titania surface by adoption of a successive ion layer adsorption-reaction (SILAR) method. Various characterization methods indicate lattice incorporation of the dopant within CdS. The addition of dopants to CdS was found to improve the photoelectrochemical performance by increasing the depletion width of the CdS nanocrystals and reducing recombination losses of charge carriers

  5. Enhancing the antimony sorption properties of nano titania-chitosan beads using epichlorohydrin as the crosslinker.

    Science.gov (United States)

    Nishad, Padala Abdul; Bhaskarapillai, Anupkumar; Velmurugan, Sankaralingam

    2017-07-15

    Antimony is classified as a pollutant of priority importance by USEPA. We have earlier reported the synthesis of nano-titania impregnated epichlorohydrin crosslinked chitosan (TA-Cts-Epi) beads, in a format suitable for large scale applications with high sorption capacity for antimony. To understand the sorption mechanism, and to fine tune the bead composition, the effect of crosslinking density on the swelling and sorption properties of the beads was investigated in detail. Epichlorohydrin effected significant changes in physical and sorption properties of the beads. The antimony sorption capacity of the TA-Cts-Epi beads prepared by crosslinking 0.3g non-crosslinked titania-chitosan beads (TA-Cts-NCL) with 6.4mmol epichlorohydrin was 493μmol/g, while those crosslinked with 0.64mmol showed a capacity of 133μmol/g. Whereas, TA-Cts-NCL beads showed a capacity of 75μmol/g. The increase in uptake capacity with increase in crosslinking demonstrated the active involvement of the epichlorohydrin moieties in antimony binding leading to enhanced sorption. Apart from altering the stability, swelling behaviour and sorption kinetics of the beads, crosslinking significantly increased the uptake of the anionic species via electrostatic interactions. Epichlorohydrin crosslinked chitosan beads prepared without TiO 2 also showed similar behaviour. The results demonstrated the involvement of chitosan, TiO 2 and epichlorohydrin in sorption. Copyright © 2017 Elsevier B.V. All rights reserved.

  6. Alumina- and titania-based monolithic catalysts for low temperature selective catalytic reduction of nitrogen oxides

    International Nuclear Information System (INIS)

    Blanco, J.; Avila, P.; Suarez, S.; Martin, J.A.; Knapp, C.

    2000-01-01

    The selective catalytic reduction of NO+NO 2 (NO x ) at low temperature (180-230C) with ammonia has been investigated with copper-nickel and vanadium oxides supported on titania and alumina monoliths. The influence of the operating temperature, as well as NH 3 /NO x and NO/NO 2 inlet ratios has been studied. High NO x conversions were obtained at operating conditions similar to those used in industrial scale units with all the catalysts. Reaction temperature, ammonia and nitrogen dioxide inlet concentration increased the N 2 O formation with the copper-nickel catalysts, while no increase was observed with the vanadium catalysts. The vanadium-titania catalyst exhibited the highest DeNO x activity, with no detectable ammonia slip and a low N 2 O formation when NH 3 /NO x inlet ratio was kept below 0.8. TPR results of this catalyst with NO/NH 3 /O 2 , NO 2 /NH 3 /O 2 and NO/NO 2 /NH 3 /O 2 feed mixtures indicated that the presence of NO 2 as the only nitrogen oxide increases the quantity of adsorbed species, which seem to be responsible for N 2 O formation. When NO was also present, N 2 O formation was not observed

  7. Double-sided anodic titania nanotube arrays: a lopsided growth process.

    Science.gov (United States)

    Sun, Lidong; Zhang, Sam; Sun, Xiao Wei; Wang, Xiaoyan; Cai, Yanli

    2010-12-07

    In the past decade, the pore diameter of anodic titania nanotubes was reported to be influenced by a number of factors in organic electrolyte, for example, applied potential, working distance, water content, and temperature. All these were closely related to potential drop in the organic electrolyte. In this work, the essential role of electric field originating from the potential drop was directly revealed for the first time using a simple two-electrode anodizing method. Anodic titania nanotube arrays were grown simultaneously at both sides of a titanium foil, with tube length being longer at the front side than that at the back side. This lopsided growth was attributed to the higher ionic flux induced by electric field at the front side. Accordingly, the nanotube length was further tailored to be comparable at both sides by modulating the electric field. These results are promising to be used in parallel configuration dye-sensitized solar cells, water splitting, and gas sensors, as a result of high surface area produced by the double-sided architecture.

  8. P25 nanoparticles decorated on titania nanotubes arrays as effective drug delivery system for ibuprofen

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Zhang; Xie, Chunlin; Luo, Fei; Li, Ping; Xiao, Xiufeng, E-mail: xfxiao@fjnu.edu.cn

    2015-01-01

    Highlights: • P25 nanoparticles decorated on titania nanotube arrays were prepared by hydrothermal treatment. • P25 nanoparticles were conducive to improve the loading effect of ibuprofen into nanotube arrays. • The diameters of the decorated nanotubes were decrease markedly which led to an effective and prolonged drug release. - Abstract: In this study, uniformly distributed layer of P25 nanoparticles (NPs) decorated on titania (TiO{sub 2}) nanotubes (TNTs) arrays was prepared in a teflon-lined stainless steel autoclave by the hydrothermal treatment. To investigate the influence of the P25 concentration, different concentrations of P25 NPs were added into the solution to obtain the optimal decorative effect. TNTs decorated with P25 (TNTs–P25) and TNTs without P25 decorated on its surface were loaded with ibuprofen (IBU) via vacuum drying and its release properties were investigated. The samples were characterized by field emission scanning electron microscopy, X-ray diffraction, and Fourier transform infrared spectroscopy. The results indicated that P25 NPs were successfully decorated on the surface of TNTs by hydrothermal method and the optimal concentration was found to be 7.5 × 10{sup −4} M. P25 NPs decorated on TNTs led to a significant increase in the specific surface area of TNTs which was conducive to improve the loading effect of IBU. Importantly, the diameters of the decorated nanotubes were reduced to 100 ± 10 nm and the increase in roughness led to an effective and prolonged drug release.

  9. Drug-eluting Ti wires with titania nanotube arrays for bone fixation and reduced bone infection

    Science.gov (United States)

    Gulati, Karan; Aw, Moom Sinn; Losic, Dusan

    2011-10-01

    Current bone fixation technology which uses stainless steel wires known as Kirschner wires for fracture fixing often causes infection and reduced skeletal load resulting in implant failure. Creating new wires with drug-eluting properties to locally deliver drugs is an appealing approach to address some of these problems. This study presents the use of titanium [Ti] wires with titania nanotube [TNT] arrays formed with a drug delivery capability to design alternative bone fixation tools for orthopaedic applications. A titania layer with an array of nanotube structures was synthesised on the surface of a Ti wire by electrochemical anodisation and loaded with antibiotic (gentamicin) used as a model of bone anti-bacterial drug. Successful fabrication of TNT structures with pore diameters of approximately 170 nm and length of 70 μm is demonstrated for the first time in the form of wires. The drug release characteristics of TNT-Ti wires were evaluated, showing a two-phase release, with a burst release (37%) and a slow release with zero-order kinetics over 11 days. These results confirmed our system's ability to be applied as a drug-eluting tool for orthopaedic applications. The established biocompatibility of TNT structures, closer modulus of elasticity to natural bones and possible inclusion of desired drugs, proteins or growth factors make this system a promising alternative to replace conventional bone implants to prevent bone infection and to be used for targeted treatment of bone cancer, osteomyelitis and other orthopaedic diseases.

  10. Synthesis and characterization of titania-based monodisperse fluorescent europium nanoparticles for biolabeling

    International Nuclear Information System (INIS)

    Tan Mingqian; Wang Guilan; Ye Zhiqiang; Yuan Jingli

    2006-01-01

    Inorganic-organic hybrid titania-based nanoparticles covalently bound to a fluorescent Eu 3+ chelate of 4,4'-bis(1'',1'',1'',2'',2'',3'',3''-heptafluoro-4'',6''-hexanedion-6''-yl) chlorosulfo-o-terphenyl (BHHCT-Eu 3+ ) were synthesized by a sol-gel technique. A conjugate of BHHCT with 3-[2-(2-aminoethylamino) ethylamino]propyl-trimethoxysilane (APTS) was used as a precursor for the nanoparticle preparation and monodisperse nanoparticles consisting of titania network and silica sub-network covalently bound to the Eu 3+ chelate were prepared by the copolymerization of APTS-BHHCT conjugate, titanium tetraisopropoxide (TTIP) and free APTS in EuCl 3 water-alcohol solution. The effects of reaction conditions on size and fluorescence lifetime of the nanoparticles were investigated. The characterizations by transmission electron microscopy and fluorometric methods indicate that the nanoparticles are near spherical and strongly fluorescent having a fluorescence quantum yield of 11.6% and a long fluorescence lifetime of ∼0.4 ms. The direct-introduced amino groups on the nanoparticle's surface by using free APTS in nanoparticle preparation facilitated the biolabeling process of the nanoparticles. The nanoparticle-labeled streptavidin (SA) was prepared and used in a sandwich-type time-resolved fluoroimmunoassay (TR-FIA) of human prostate-specific antigen (PSA) by using a 96-well microtiter plate as the solid phase carrier. The method gives a detection limit of 66 pg/ml for the PSA assay

  11. Potassium effects on kinetics of propane oxydehydrogenation on vanadia-titania catalyst

    International Nuclear Information System (INIS)

    Grabowski, R.; Samson, K.

    2003-01-01

    Oxidative dehydrogenation of propane (ODH) over V 2 O 5 /TiO 2 and V 2 O 5 /TiO 2 doped with K was carried out by measuring conversions and selectiveness for various feed compositions, contact times and temperatures. The results obtained for both catalysts were interpreted on the basis of the mechanism, in which propene is formed through Eley-Rideal sequence of steps, i.e. without participation of the adsorbed propane species. Kinetic constants (activation energies, pre-exponential factors) for the model of ODH reaction of propane on these catalysts, obtained on the basis of steady-state results, are given. Addition of K to vanadia-titania catalysts leads to decrease of total combustion of propane and consecutive combustion of propene. It has been found that the direct propane total oxidation is 5 - 9 times lower than that of the consecutive propene oxidation and is almost temperature independent for potassium doped catalyst, whereas it quickly decreases with temperature for a non-doped catalyst. Secondly, the addition of K to a vanadia-titania catalyst decreases the activation energies for propene formation (k 1 ), parallel formation of CO x (k 3 ) and reoxidation of the catalyst (k os ). Potassium exhibits a stronger inhibitory effect on the secondary propene combustion, what reflects the lower activity of V 5+ cations modified by the strongly basic alkali oxide species. (author)

  12. Self-assembly of protein-based biomaterials initiated by titania nanotubes.

    Science.gov (United States)

    Forstater, Jacob H; Kleinhammes, Alfred; Wu, Yue

    2013-12-03

    Protein-based biomaterials are a promising strategy for creating robust highly selective biocatalysts. The assembled biomaterials must sufficiently retain the near-native structure of proteins and provide molecular access to catalytically active sites. These requirements often exclude the use of conventional assembly techniques, which rely on covalent cross-linking of proteins or entrapment within a scaffold. Here we demonstrate that titania nanotubes can initiate and template the self-assembly of enzymes, such as ribonuclease A, while maintaining their catalytic activity. Initially, the enzymes form multilayer thick ellipsoidal aggregates centered on the nanotube surface; subsequently, these nanosized entities assemble into a micrometer-sized enzyme material that has enhanced enzymatic activity and contains as little as 0.1 wt % TiO2 nanotubes. This phenomenon is uniquely associated with the active anatase (001)-like surface of titania nanotubes and does not occur on other anatase nanomaterials, which contain significantly fewer undercoordinated Ti surface sites. These findings present a nanotechnology-enabled mechanism of biomaterial growth and open a new route for creating stable protein-based biomaterials and biocatalysts without the need for chemical modification.

  13. Development and characterization of silica and titania based nano structured materials for the removal of indoor and outdoor air pollutants

    Science.gov (United States)

    Peiris, Thelge Manindu Nirasha

    Solar energy driven catalytic systems have gained popularity in environmental remediation recently. Various photocatalytic systems have been reported in this regard and most of the photocatalysts are based on well-known semiconducting material, Titanium Dioxide, while some are based on other materials such as Silicon Dioxide and various Zeolites. However, in titania based photocatalysts, titania is actively involved in the catalytic mechanism by absorbing light and generating exitons. Because of this vast popularity of titania in the field of photocatalysis it is believed that photocatalysis mainly occurs via non-localized mechanisms and semiconductors are extremely important. Even though it is still rare, photocatalysis could be localized and possible without use of a semiconductor as well. Thus, to support localized photocatalytic systems, and to compare the activity to titania based systems, degradation of organic air pollutants by nanostructured silica, titania and mixed silica titania systems were studied. New materials were prepared using two different approaches, precipitation technique (xerogel) and aerogel preparation technique. The prepared xerogel samples were doped with both metal (silver) and non-metals (carbon and sulfur) and aerogel samples were loaded with Chromium, Cobalt and Vanadium separately, in order to achieve visible light photocatalytic activity. Characterization studies of the materials were carried out using Nova BET analysis, DR UV-vis spectrometry, powder X-ray diffraction, X-ray photoelectron Spectroscopy, FT-IR spectroscopy, Transmission Electron Microscopy, etc. Kinetics of the catalytic activities was studied using a Shimadzu GCMS-QP 5000 instrument using a closed glass reactor. All the experiments were carried out in gaseous phase using acetaldehyde as the model pollutant. Kinetic results suggest that chromium doped silica systems are good UV and visible light active photocatalysts. This is a good example for a localized

  14. The anodization synthesis of copper oxide nanosheet arrays and their photoelectrochemical properties

    Energy Technology Data Exchange (ETDEWEB)

    Shu, Xia [School of Materials Science and Engineering, Hefei University of Technology, Hefei 230009 (China); Zheng, Hongmei [School of Materials Science and Engineering, Hefei University of Technology, Hefei 230009 (China); Key Laboratory of Advanced Functional Materials and Devices of Anhui Province, Hefei 230009 (China); Xu, Guangqing, E-mail: gqxu1979@hfut.edu.cn [School of Materials Science and Engineering, Hefei University of Technology, Hefei 230009 (China); Key Laboratory of Advanced Functional Materials and Devices of Anhui Province, Hefei 230009 (China); Zhao, Jiebo [School of Materials Science and Engineering, Hefei University of Technology, Hefei 230009 (China); Cui, Lihua [School of Materials Science and Engineering, Hefei University of Technology, Hefei 230009 (China); School of Materials Science and Engineering, Beifang University of Nationalities, Yinchuan 750021 (China); Cui, Jiewu; Qin, Yongqiang; Wang, Yan [School of Materials Science and Engineering, Hefei University of Technology, Hefei 230009 (China); Zhang, Yong [School of Materials Science and Engineering, Hefei University of Technology, Hefei 230009 (China); Key Laboratory of Advanced Functional Materials and Devices of Anhui Province, Hefei 230009 (China); Wu, Yucheng, E-mail: ycwu@hfut.edu.cn [School of Materials Science and Engineering, Hefei University of Technology, Hefei 230009 (China); Key Laboratory of Advanced Functional Materials and Devices of Anhui Province, Hefei 230009 (China)

    2017-08-01

    Graphical abstract: Current-time and potential-time curves of the copper foil anodization process, CV of copper substrate in anodization solution and SEM morphologies of anodization products on Cu substrates obtained at different time. - Highlights: • Copper oxides nanosheet arrays were achieved via anodization method. • The growth mechanisms of the copper anodization process were studied. • Photoelectrochemical performances of copper oxides NSAs were studied. - Abstract: We studied the growth of copper oxide nanosheet arrays on copper foil via a simple anodization method. The structures, morphologies, and elemental compositions of the specimens were characterized with an X-ray diffractometer, scanning electron microscope, high resolution transmission electron microscope, and X-ray photoelectron spectrometer. The copper oxide (Cu{sub 2}O and CuO) nanosheet arrays were comprised of 30-nm-thick nanosheets that stand vertically on the Cu substrate. The anodizing parameters, such as the current density, temperature, and polyethylene glycol concentration, were optimized to obtain the regular nanosheet arrays. The optical absorption properties of the anodized products were evaluated using a diffuse reflectance spectrometer, and broad and strong optical absorption bands arising from the UV to visible region were observed. The photoelectrochemical performance of the nanosheet arrays was measured with chronoamperometry and cyclic voltammetry on an electrochemical workstation equipped with a Xe lamp (wavelength >400 nm). A negative photocurrent was obtained due to the p-type semiconductor of the copper oxides. The copper oxide nanosheet arrays achieve the highest photocurrent of 0.4 mA/cm{sup 2} at the current density of 1.0 A/dm{sup 2}, temperature of 70 °C, and polyethylene glycol concentration of 0.5 g/L.

  15. Commercial and home-made nitrogen modified titanias. A short reflection about the advantageous/disadvantageous properties of nitrogen doping in the frame of their applicability

    Science.gov (United States)

    Pap, Zs.; Mogyorósi, K.; Veréb, G.; Dombi, A.; Hernádi, K.; Danciu, V.; Baia, L.

    2014-09-01

    As visible light driven photocatalysis became more and more intensively studied, the first commercial products showed up on the market. Simultaneously controversial results appeared in the literature generating an intensive debate regarding the advantages and draw-backs of nitrogen doping of titania. Hence, the present work focuses on two commercially available and four sol-gel made nitrogen modified titania powders regarding their structure and activity. It is demonstrated that the interstitial nitrogen entities “leak out” from the catalysts if the material is irradiated with UV light, while substitutional nitrogen remains stable. However, the latter one was proven to be less important in the photocatalytic point of view. These observations were also valid in the case of sol-gel made nitrogen modified titanias. Furthermore, the results obtained after applying different spectroscopic methods (IR, XPS and DRS) shown that the yellow color of the titanias, does not necessary mean that a successful doping is achieved.

  16. Soft template strategy to synthesize iron oxide-titania yolk-shell nanoparticles as high-performance anode materials for lithium-ion battery applications.

    Science.gov (United States)

    Lim, Joohyun; Um, Ji Hyun; Ahn, Jihoon; Yu, Seung-Ho; Sung, Yung-Eun; Lee, Jin-Kyu

    2015-05-18

    Yolk-shell-structured nanoparticles with iron oxide core, void, and a titania shell configuration are prepared by a simple soft template method and used as the anode material for lithium ion batteries. The iron oxide-titania yolk-shell nanoparticles (IO@void@TNPs) exhibit a higher and more stable capacity than simply mixed nanoparticles of iron oxide and hollow titania because of the unique structure obtained by the perfect separation between iron oxide nanoparticles, in combination with the adequate internal void space provided by stable titania shells. Moreover, the structural effect of IO@void@TNPs clearly demonstrates that the capacity retention value after 50 cycles is approximately 4 times that for IONPs under harsh operating conditions, that is, when the temperature is increased to 80 °C. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  17. Preparation and corrosion resistance of a nanocomposite plasma electrolytic oxidation coating on Mg-1%Ca alloy formed in aluminate electrolyte containing titania nano-additives

    DEFF Research Database (Denmark)

    Daroonparvar, Mohammadreza; Yajid, M. A. M.; Yusof, N. M.

    2016-01-01

    Titania nanoparticles were utilized as suspension in alkaline aluminate electrolyte to form nanocomposite coatings on magnesium alloy containing 1 wt% calcium by plasma electrolytic oxidation process. Microhardness, wettability, potentiodynamic polarization, wettability, electrochemical impedance...

  18. Synthesis of novel CuO nanosheets and their non-enzymatic glucose sensing applications.

    Science.gov (United States)

    Ibupoto, Zafar Hussain; Khun, Kimleang; Beni, Valerio; Liu, Xianjie; Willander, Magnus

    2013-06-20

    In this study, we have developed a sensitive and selective glucose sensor using novel CuO nanosheets which were grown on a gold coated glass substrate by a low temperature growth method. X-ray differaction (XRD) and scanning electron microscopy (SEM) techniques were used for the structural characterization of CuO nanostructures. CuO nanosheets are highly dense, uniform, and exhibited good crystalline array structure. X-ray photoelectron spectroscopy (XPS) technique was applied for the study of chemical composition of CuO nanosheets and the obtained information demonstrated pure phase CuO nanosheets. The novel CuO nanosheets were employed for the development of a sensitive and selective non-enzymatic glucose sensor. The measured sensitivity and a correlation coefficient are in order 5.20 × 10² µA/mMcm² and 0.998, respectively. The proposed sensor is associated with several advantages such as low cost, simplicity, high stability, reproducibility and selectivity for the quick detection of glucose.

  19. Synthesis of Novel CuO Nanosheets and Their Non-Enzymatic Glucose Sensing Applications

    Directory of Open Access Journals (Sweden)

    Magnus Willander

    2013-06-01

    Full Text Available In this study, we have developed a sensitive and selective glucose sensor using novel CuO nanosheets which were grown on a gold coated glass substrate by a low temperature growth method. X-ray differaction (XRD and scanning electron microscopy (SEM techniques were used for the structural characterization of CuO nanostructures. CuO nanosheets are highly dense, uniform, and exhibited good crystalline array structure. X-ray photoelectron spectroscopy (XPS technique was applied for the study of chemical composition of CuO nanosheets and the obtained information demonstrated pure phase CuO nanosheets. The novel CuO nanosheets were employed for the development of a sensitive and selective non-enzymatic glucose sensor. The measured sensitivity and a correlation coefficient are in order 5.20 × 102 µA/mMcm2 and 0.998, respectively. The proposed sensor is associated with several advantages such as low cost, simplicity, high stability, reproducibility and selectivity for the quick detection of glucose.

  20. Incorporation of Graphene-Related Carbon Nanosheets in Membrane Fabrication for Water Treatment: A Review

    Directory of Open Access Journals (Sweden)

    Jenny Lawler

    2016-12-01

    Full Text Available The minimization of the trade-off between the flux and the selectivity of membranes is a key area that researchers are continually working to optimise, particularly in the area of fabrication of novel membranes. Flux versus selectivity issues apply in many industrial applications of membranes, for example the unwanted diffusion of methanol in fuel cells, retention of valuable proteins in downstream processing of biopharmaceuticals, rejection of organic matter and micro-organisms in water treatment, or salt permeation in desalination. The incorporation of nanosheets within membrane structures can potentially lead to enhancements in such properties as the antifouling ability, hydrophilicy and permeability of membranes, with concomitant improvements in the flux/selectivity balance. Graphene nanosheets and derivatives such as graphene oxide and reduced graphene oxide have been investigated for this purpose, for example inclusion of nanosheets within the active layer of Reverse Osmosis or Nanofiltration membranes or the blending of nanosheets as fillers within Ultrafiltration membranes. This review summarizes the incorporation of graphene derivatives into polymeric membranes for water treatment with a focus on a number of industrial applications, including desalination and pharmaceutical removal, where enhancement of productivity and reduction in fouling characteristics have been afforded by appropriate incorporation of graphene derived nanosheets during membrane fabrication.

  1. Novel iron oxyhydroxide lepidocrocite nanosheet as ultrahigh power density anode material for asymmetric supercapacitors.

    Science.gov (United States)

    Chen, Ying-Chu; Lin, Yan-Gu; Hsu, Yu-Kuei; Yen, Shi-Chern; Chen, Kuei-Hsien; Chen, Li-Chyong

    2014-09-24

    A simple one-step electroplating route is proposed for the synthesis of novel iron oxyhydroxide lepidocrocite (γ-FeOOH) nanosheet anodes with distinct layered channels, and the microstructural influence on the pseudocapacitive performance of the obtained γ-FeOOH nanosheets is investigated via in situ X-ray absorption spectroscopy (XAS) and electrochemical measurement. The in situ XAS results regarding charge storage mechanisms of electrodeposited γ-FeOOH nanosheets show that a Li(+) can reversibly insert/desert into/from the 2D channels between the [FeO6 ] octahedral subunits depending on the applied potential. This process charge compensates the Fe(2+) /Fe(3+) redox transition upon charging-discharging and thus contributes to an ideal pseudocapacitive behavior of the γ-FeOOH electrode. Electrochemical results indicate that the γ-FeOOH nanosheet shows the outstanding pseudocapacitive performance, which achieves the extraordinary power density of 9000 W kg(-1) with good rate performance. Most importantly, the asymmetric supercapacitors with excellent electrochemical performance are further realized by using 2D MnO2 and γ-FeOOH nanosheets as cathode and anode materials, respectively. The obtained device can be cycled reversibly at a maximum cell voltage of 1.85 V in a mild aqueous electrolyte, further delivering a maximum power density of 16 000 W kg(-1) at an energy density of 37.4 Wh kg(-1). © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  2. Two-Dimensional Metal-Organic Framework Nanosheets for Membrane-Based Gas Separation.

    Science.gov (United States)

    Peng, Yuan; Li, Yanshuo; Ban, Yujie; Yang, Weishen

    2017-08-07

    Metal-organic framework (MOF) nanosheets could serve as ideal building blocks of molecular sieve membranes owing to their structural diversity and minimized mass-transfer barrier. To date, discovery of appropriate MOF nanosheets and facile fabrication of high performance MOF nanosheet-based membranes remain as great challenges. A modified soft-physical exfoliation method was used to disintegrate a lamellar amphiprotic MOF into nanosheets with a high aspect ratio. Consequently sub-10 nm-thick ultrathin membranes were successfully prepared, and these demonstrated a remarkable H 2 /CO 2 separation performance, with a separation factor of up to 166 and H 2 permeance of up to 8×10 -7  mol m -2  s -1  Pa -1 at elevated testing temperatures owing to a well-defined size-exclusion effect. This nanosheet-based membrane holds great promise as the next generation of ultrapermeable gas separation membrane. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  3. Homogeneously dispersed CeO2 nanoparticles on exfoliated hexaniobate nanosheets

    Science.gov (United States)

    Marques, Thalles M. F.; Strayer, Megan E.; Ghosh, Anupama; Silva, Alexandre; Ferreira, Odair P.; Fujisawa, Kazunori; Alves da Cunha, Jose R.; Abreu, Guilherme J. P.; Terrones, Mauricio; Mallouk, Thomas E.; Viana, Bartolomeu C.

    2017-12-01

    Hexaniobate nanosheets derived from the parent compound K4Nb6O17 have been decorated with CeO2 nanoparticles by ion exchange with aqueous cerium (IV) solution. Very homogeneous CeO2 nanoparticle decoration of the hexaniobate sheets can be achieved by this method and the resulting composites may absorb visible light. HRTEM images show that ∼3.0 nm diameter CeO2 nanoparticles adhere to hexaniobate nanosheets that are exfoliated and then restacked prior to Ce deposition. The interfacial interaction between CeO2 nanoparticles and nanosheets would be due to an electrostatic attraction mechanism. Raman and XRD measurements have given strong evidence that CeO2 nanoparticles have fluorite structure. EDS, FTIR and XPS results suggest almost complete exchange of TBA+ and K+ by Ce4+. Cerium ion exchange on the acid exchanged parent compound, H2.9K1.1Nb6O17, revealed that the extent of Ce ion exchange is much greater in case of nanosheets, which may be rationalized by the larger surface area available after exfoliation. XPS measurements show that the ratio of Ce4+/Ce3+ is around 4.4, in agreement with the formation of fluorite structure (CeO2). Thus, these CeO2 nanoparticle/nanosheet composites may be useful for catalytic processes.

  4. Alcohol molecules adsorption on graphane nanosheets - A first-principles investigation

    Science.gov (United States)

    Nagarajan, V.; Chandiramouli, R.

    2018-05-01

    The geometric structure, electronic and adsorption properties of methanol, ethanol and 1-propanol molecules on hydrogenated graphene (graphane) were investigated using first-principles calculations. The stability of graphane base material is confirmed using formation energy and phonon band structures. The adsorption of alcohol molecules on bare graphane and hydrogen vacant graphane nanosheet is found to be prominent and the selectivity of alcohol molecules can be achieved using bare or hydrogen vacant graphane nanosheet. Moreover, the interaction of alcohol molecules on bare and hydrogen vacant graphane nanosheets is studied using the adsorption energy, energy band gap variation, Bader charge transfer and average energy band gap variation. The adsorption energy ranges from -0.149 to -0.383 eV upon alcohol adsorption. The energy gap varies from 4.71 to 2.62 eV for bare graphane and from 4.02 to 3.60 eV for hydrogen vacant graphane nanosheets upon adsorption of alcohol molecules. The adsorption properties of alcohol molecules provide useful information for the possible application of graphane nanosheet as a base material for the detection of alcohol molecules.

  5. Reduction of graphene oxide nanosheets by natural beta carotene and its potential use as supercapacitor electrode

    Directory of Open Access Journals (Sweden)

    Rubaiyi M. Zaid

    2015-07-01

    Full Text Available A green, non-toxic and eco-friendly approach for the reduction of graphene oxide (GO nanosheets using natural β-carotene is reported. The FTIR spectroscopy and thermogravimetric analyses reveal the oxygen scavenging property of β-carotene successfully removes oxygen functionalities on GO nanosheets. Complete GO reduction is achieved within 16 h with 10 mM β-carotene as confirmed by the UV spectroscopy results. The high resolution transmission electron microscopy images provide clear evidence for the formation of few layers of graphene nanosheets. Furthermore, the mechanism of GO reduction by β-carotene has been proposed in this study. The electrochemical testing shows good charge storage properties of β-carotene reduced GO (142 F/g at 10 mV/s; 149 F/g at 1 A/g in Na2SO4, with stable cycling (89% for up to 1000 cycles. The findings suggest the reduction of GO nanosheets by β-carotene is a suitable approach in producing graphene nanosheets for supercapacitor electrode.

  6. Probing the biocompatibility of MoS2 nanosheets by cytotoxicity assay and electrical impedance spectroscopy

    Science.gov (United States)

    Shah, Pratikkumar; Narayanan, Tharangattu N.; Li, Chen-Zhong; Alwarappan, Subbiah

    2015-08-01

    Transition metal dichalgogenides such as MoS2 have recently emerged as hot two-dimensional (2D) materials due to their superior electronic and catalytic properties. Recently, we have reported the usefulness of MoS2 nanosheets toward the electrochemical detection of neurotransmitters and glucose (Narayanan et al 2014 Nanotechnology 25 335702). Furthermore, there are reports available in the literature that demonstrate the usefulness of MoS2 nanosheets for biosensing and energy storage applications (Zhu et al 2013 J. Am. Chem. Soc. 135 5998-6001 Pumera and Loo 2014 Trends Anal. Chem. 61 49-53 Lee et al 2014 Sci. Rep. 4 7352; Stephenson et al 2014 Energy Environ. Sci. 7 209-31). Understanding the cytotoxic effect of any material is very important prior to employing them for any in vivo biological applications such as implantable sensors, chips, or carriers for drug delivery and cell imaging purposes. Herein, we report the cytotoxicity of the MoS2 nanosheets based on the cytotoxic assay results and electrical impedance analysis using rat pheochromocytoma cells (PC12) and rat adrenal medulla endothelial cells (RAMEC). Our results indicated that the MoS2 nanosheets synthesized in our work are safe 2D nanosheets for futuristic biomedical applications.

  7. A Simple Synthesis of Two-Dimensional Ultrathin Nickel Cobaltite Nanosheets for Electrochemical Lithium Storage

    International Nuclear Information System (INIS)

    Zhu, Youqi; Cao, Chuanbao

    2015-01-01

    We report a simple microwave-assisted method to fabricate high-quality two-dimensional (2D) ultrathin NiCo 2 O 4 nanosheets with a geometrically graphene-like architecture. The unique large-area nanostructures represent an ultrahigh surface atomic ratio with almost all active elements exposed outside for surface-dependent electrochemical reaction processes. Experimental results reveal that the as-synthesized ultrathin NiCo 2 O 4 nanosheets show excellent electrochemical performances for lithium storage application. The ultrathin NiCo 2 O 4 nanosheets could deliver a high first discharge capacity (1287.1 mAh g −1 ) with initial Coulombic efficiency of 80.0% at 200 mA g −1 current density. The reversible lithium storage capacity still retains at 804.8 mAh g −1 in the 100th cycle, suggesting a good cycling stability. The excellent electrochemical properties of the as-synthesized NiCo 2 O 4 nanosheets could be ascribed to the unique ultrathin 2D architecture, which could offer large exposed active surface with more lithium-insertion channels and significantly reduce lithium ion diffusion distance. The cost-efficient synthesis and excellent lithium storage properties make the 2D NiCo 2 O 4 nanosheets as a promising anode material for high-performance lithium ion batteries

  8. Size dependent emission stimulation in ZnO nanosheets

    International Nuclear Information System (INIS)

    Torchynska, T.V.; El Filali, B.

    2014-01-01

    Photoluminescence (PL), X ray diffraction (XRD) and Raman scattering have been studied in crystalline ZnO nanosheets (NSs) of different sizes, estimated by scanning electronic microscopy (SEM). ZnO NSs with the size from the range of 60–600 nm were created by the electrochemical (anodization) method and followed thermal annealing at 400 °C for 2 h in ambient air. XRD study confirms the wurtzite structure of ZnO NSs and has revealed that the lattice parameters increase monotonically with decreasing NS sizes. Simultaneously the intensity of a set of Raman peaks increases and Raman peaks shift into the low energy range. The surface phonon has been detected in smallest size ZnO NSs. Two types of PL bands deal with a set of phonon replicas of free excitons and the defect related emission have been detected in ZnO NSs. The intensity enhancement of exciton- and defect-related PL bands with decreasing ZnO NS sizes has been detected. The intensity stimulation of exciton-related PL bands is attributed to the realization of the week confinement and the exciton-light coupling with the formation of polariton in small size ZnO NSs of 67–170 nm. The intensity rising of defect-related PL bands is attributed to the concentration enlargement of surface defects when the surface to volume ration increases at decreasing ZnO NS sizes. Numerical simulations of radiative lifetimes and exciton radiative recombination rates in ZnO NSs for different emission wavelengths have been done using the exciton-light coupling model. Then the experimental and numerically simulated PL results have been compared and discussed. - Highlights: • Optical and structural investigations of the ZnO nanosheets with the sizes 60–600 nm. • The enlargement of interplanar distances in the wurtzite ZnO crystal lattice is detected. • The change of optic phonon energy and surface phonon appearing are reveled. • ZnO emission stimulation at the week confinement and electron-light coupling with the

  9. Preparation and applications of mechanically exfoliated single-layer and multilayer MoS₂ and WSe₂ nanosheets.

    Science.gov (United States)

    Li, Hai; Wu, Jumiati; Yin, Zongyou; Zhang, Hua

    2014-04-15

    Although great progress has been achieved in the study of graphene, the small current ON/OFF ratio in graphene-based field-effect transistors (FETs) limits its application in the fields of conventional transistors or logic circuits for low-power electronic switching. Recently, layered transition metal dichalcogenide (TMD) materials, especially MoS2, have attracted increasing attention. In contrast to its bulk material with an indirect band gap, a single-layer (1L) MoS2 nanosheet is a semiconductor with a direct band gap of ~1.8 eV, which makes it a promising candidate for optoelectronic applications due to the enhancement of photoluminescence and high current ON/OFF ratio. Compared with TMD nanosheets prepared by chemical vapor deposition and liquid exfoliation, mechanically exfoliated ones possess pristine, clean, and high-quality structures, which are suitable for the fundamental study and potential applications based on their intrinsic thickness-dependent properties. In this Account, we summarize our recent research on the preparation, characterization, and applications of 1L and multilayer MoS2 and WSe2 nanosheets produced by mechanical exfoliation. During the preparation of nanosheets, we proposed a simple optical identification method to distinguish 1L and multilayer MoS2 and WSe2 nanosheets on a Si substrate coated with 90 and 300 nm SiO2. In addition, we used Raman spectroscopy to characterize mechanically exfoliated 1L and multilayer WSe2 nanosheets. For the first time, a new Raman peak at 308 cm(-1) was observed in the spectra of WSe2 nanosheets except for the 1L WSe2 nanosheet. Importantly, we found that the 1L WSe2 nanosheet is very sensitive to the laser power during characterization. The high power laser-induced local oxidation of WSe2 nanosheets and single crystals was monitored by Raman spectroscopy and atomic force microscopy (AFM). Hexagonal and monoclinic structured WO3 thin films were obtained from the local oxidization of single- to triple

  10. Titania nanotube powders obtained by rapid breakdown anodization in perchloric acid electrolytes

    International Nuclear Information System (INIS)

    Ali, Saima; Hannula, Simo-Pekka

    2017-01-01

    Titania nanotube (TNT) powders are prepared by rapid break down anodization (RBA) in a 0.1 M perchloric acid (HClO 4 ) solution (Process 1), and ethylene glycol (EG) mixture with HClO 4 and water (Process 2). A study of the as-prepared and calcined TNT powders obtained by both processes is implemented to evaluate and compare the morphology, crystal structure, specific surface area, and the composition of the nanotubes. Longer TNTs are formed in Process 1, while comparatively larger pore diameter and wall thickness are obtained for the nanotubes prepared by Process 2. The TNTs obtained by Process 1 are converted to nanorods at 350 °C, while nanotubes obtained by Process 2 preserve tubular morphology till 350 °C. In addition, the TNTs prepared by an aqueous electrolyte have a crystalline structure, whereas the TNTs obtained by Process 2 are amorphous. Samples calcined till 450 °C have XRD peaks from the anatase phase, while the rutile phase appears at 550 °C for the TNTs prepared by both processes. The Raman spectra also show clear anatase peaks for all samples except the as-prepared sample obtained by Process 2, thus supporting the XRD findings. FTIR spectra reveal the presence of O-H groups in the structure for the TNTs obtained by both processes. However, the presence is less prominent for annealed samples. Additionally, TNTs obtained by Process 2 have a carbonaceous impurity present in the structure attributed to the electrolyte used in that process. While a negligible weight loss is typical for TNTs prepared from aqueous electrolytes, a weight loss of 38.6% in the temperature range of 25–600 °C is found for TNTs prepared in EG electrolyte (Process 2). A large specific surface area of 179.2 m 2 g −1 is obtained for TNTs prepared by Process 1, whereas Process 2 produces nanotubes with a lower specific surface area. The difference appears to correspond to the dimensions of the nanotubes obtained by the two processes. - Graphical abstract: Titania nanotube

  11. Titania nanotube powders obtained by rapid breakdown anodization in perchloric acid electrolytes

    Energy Technology Data Exchange (ETDEWEB)

    Ali, Saima, E-mail: saima.ali@aalto.fi; Hannula, Simo-Pekka

    2017-05-15

    Titania nanotube (TNT) powders are prepared by rapid break down anodization (RBA) in a 0.1 M perchloric acid (HClO{sub 4}) solution (Process 1), and ethylene glycol (EG) mixture with HClO{sub 4} and water (Process 2). A study of the as-prepared and calcined TNT powders obtained by both processes is implemented to evaluate and compare the morphology, crystal structure, specific surface area, and the composition of the nanotubes. Longer TNTs are formed in Process 1, while comparatively larger pore diameter and wall thickness are obtained for the nanotubes prepared by Process 2. The TNTs obtained by Process 1 are converted to nanorods at 350 °C, while nanotubes obtained by Process 2 preserve tubular morphology till 350 °C. In addition, the TNTs prepared by an aqueous electrolyte have a crystalline structure, whereas the TNTs obtained by Process 2 are amorphous. Samples calcined till 450 °C have XRD peaks from the anatase phase, while the rutile phase appears at 550 °C for the TNTs prepared by both processes. The Raman spectra also show clear anatase peaks for all samples except the as-prepared sample obtained by Process 2, thus supporting the XRD findings. FTIR spectra reveal the presence of O-H groups in the structure for the TNTs obtained by both processes. However, the presence is less prominent for annealed samples. Additionally, TNTs obtained by Process 2 have a carbonaceous impurity present in the structure attributed to the electrolyte used in that process. While a negligible weight loss is typical for TNTs prepared from aqueous electrolytes, a weight loss of 38.6% in the temperature range of 25–600 °C is found for TNTs prepared in EG electrolyte (Process 2). A large specific surface area of 179.2 m{sup 2} g{sup −1} is obtained for TNTs prepared by Process 1, whereas Process 2 produces nanotubes with a lower specific surface area. The difference appears to correspond to the dimensions of the nanotubes obtained by the two processes. - Graphical abstract

  12. Dispersed-nanoparticle loading synthesis for monodisperse Au-titania composite particles and their crystallization for highly active UV and visible photocatalysts.

    Science.gov (United States)

    Sakamoto, Takeshi; Nagao, Daisuke; Noba, Masahiro; Ishii, Haruyuki; Konno, Mikio

    2014-06-24

    Submicrometer-sized amorphous titania spheres incorporating Au nanoparticles (NPs) were prepared in a one-pot synthesis consisting of a sol-gel reaction of titanium(IV) isopropoxide in the presence of chloroauric acid and a successive reduction with sodium borohydride in a mixed solvent of ethanol/acetonitrile. The synthesis was allowed to prepare monodisperse titania spheres that homogeneously incorporated Au NPs with sizes of ca. 7 nm. The Au NP-loaded titania spheres underwent different crystallization processes, including 500 °C calcination in air, high-temperature hydrothermal treatment (HHT), and/or low-temperature hydrothermal treatment (LHT). Photocatalytic experiments were conducted with the Au NP-loaded crystalline titania spheres under irradiation of UV and visible light. A combined process of LHT at 80 °C followed by calcination at 500 °C could effectively crystallize titania spheres maintaining the dispersion state of Au NPs, which led to photocatalytic activity higher than that of commercial P25 under UV irradiation. Under visible light irradiation, the Au NP-titania spheres prepared with a crystallization process of LHT at 80 °C for 6 h showed photocatalytic activity much higher than a commercial product of visible light photocatalyst. Structure analysis of the visible light photocatalysts indicates the importance of prevention of the Au NPs aggregation in the crystallization processes for enhancement of photocatalytic activity.

  13. Graphene nanosheet-induced toughening of yttria-stabilized zirconia

    Energy Technology Data Exchange (ETDEWEB)

    Su, Jianan; Chen, Yao; Huang, Qiqi [Soochow University, School of Mechanical and Electric Engineering, Collaborative Innovation Center of Suzhou Nano Science and Technology, Suzhou (China)

    2017-01-15

    Graphene nanosheet (GNS)-reinforced yttria-stabilized tetragonal zirconia polycrystals (TZP) were synthesized using spark plasma sintering (SPS), and the influences of the added GNSs on microstructure evolution and the microscopic mechanical properties of the sintered composites were investigated. Raman spectroscopy and microstructure observation corroborated that these added GNSs, which can survive the harsh SPS processing condition, homogeneously distribute in the matrix of all composites to hinder significantly the grain growth. In comparison with the monolithic TZP, the indentation fracture toughness of a GNS/TZP composite reaches maximum value and increases by up to ∝36% (from ∝4.1 to ∝5.6 MPa m{sup 0.5}) even at 0.5% weight fraction, GNS pullout, crack bridging, crack deflection, and crack branching are responsible for the increased fracture toughness. The computed energy dissipation by GNS pullout decreases with increasing the number of graphene layers due to weak bonding between them, and therefore, graphene agglomeration would impair toughening effect. Moreover, scratch studies suggest that GNS/TZP composites exhibit improved scratch resistance due to the fact that GNSs are promising reinforcing and lubricating nanofillers in ceramic composites. (orig.)

  14. Scalable transfer of vertical graphene nanosheets for flexible supercapacitor applications

    Science.gov (United States)

    Sahoo, Gopinath; Ghosh, Subrata; Polaki, S. R.; Mathews, Tom; Kamruddin, M.

    2017-10-01

    Vertical graphene nanosheets (VGN) are the material of choice for application in next-generation electronic devices. The growing demand for VGN-based flexible devices for the electronics industry brings in restriction on VGN growth temperature. The difficulty associated with the direct growth of VGN on flexible substrates can be overcome by adopting an effective strategy of transferring the well-grown VGN onto arbitrary flexible substrates through a soft chemistry route. In the present study, we report an inexpensive and scalable technique for the polymer-free transfer of VGN onto arbitrary substrates without disrupting its morphology, structure, and properties. After transfer, the morphology, chemical structure, and electrical properties are analyzed by scanning electron microscopy, Raman spectroscopy, x-ray photoelectron spectroscopy, and four-probe resistive methods, respectively. The wetting properties are studied from the water contact angle measurements. The observed results indicate the retention of morphology, surface chemistry, structure, and electronic properties. Furthermore, the storage capacity of the transferred VGN-based binder-free and current collector-free flexible symmetric supercapacitor device is studied. A very low sheet resistance of 670 Ω/□ and excellent supercapacitance of 158 μF cm-2 with 86% retention after 10 000 cycles show the prospect of the damage-free VGN transfer approach for the fabrication of flexible nanoelectronic devices.

  15. High performance supercapacitors using metal oxide anchored graphene nanosheet electrodes

    KAUST Repository

    Baby, Rakhi Raghavan

    2011-01-01

    Metal oxide nanoparticles were chemically anchored onto graphene nanosheets (GNs) and the resultant composites - SnO2/GNs, MnO2/GNs and RuO2/GNs (58% of GNs loading) - coated over conductive carbon fabric substrates were successfully used as supercapacitor electrodes. The results showed that the incorporation of metal oxide nanoparticles improved the capacitive performance of GNs due to a combination of the effect of spacers and redox reactions. The specific capacitance values (with respect to the composite mass) obtained for SnO2/GNs (195 F g-1) and RuO 2/GNs (365 F g-1) composites at a scan rate of 20 mV s-1 in the present study are the best ones reported to date for a two electrode configuration. The resultant supercapacitors also exhibited high values for maximum energy (27.6, 33.1 and 50.6 W h kg-1) and power densities (15.9, 20.4 and 31.2 kW kg-1) for SnO2/GNs, MnO2/GNs and RuO2/GNs respectively. These findings demonstrate the importance and great potential of metal oxide/GNs based composite coated carbon fabric in the development of high-performance energy-storage systems. © 2011 The Royal Society of Chemistry.

  16. Enhanced supercapacitance of activated vertical graphene nanosheets in hybrid electrolyte

    Science.gov (United States)

    Ghosh, Subrata; Sahoo, Gopinath; Polaki, S. R.; Krishna, Nanda Gopala; Kamruddin, M.; Mathews, Tom

    2017-12-01

    Supercapacitors are becoming the workhorse for emerging energy storage applications due to their higher power density and superior cycle life compared to conventional batteries. The performance of supercapacitors depends on the electrode material, type of electrolyte, and interaction between them. Owing to the beneficial interconnected porous structure with multiple conducting channels, vertical graphene nanosheets (VGN) have proved to be leading supercapacitor electrode materials. Herein, we demonstrate a novel approach based on the combination of surface activation and a new organo-aqueous hybrid electrolyte, tetraethylammonium tetrafluoroborate in H2SO4, to achieve significant enhancement in supercapacitor performance of VGN. As-synthesized VGN exhibits an excellent supercapacitance of 0.64 mF/cm2 in H2SO4. However, identification of a novel electrolyte for performance enhancement is the subject of current research. The present manuscript demonstrates the potential of the hybrid electrolyte in enhancing the areal capacitance (1.99 mF/cm2) with excellent retention (only 5.4% loss after 5000 cycles) and Coulombic efficiency (93.1%). In addition, a five-fold enhancement in the capacitance of VGNs (0.64 to 3.31 mF/cm2) with a reduced internal resistance is achieved by the combination of KOH activation and the hybrid electrolyte.

  17. Soft chemical synthesis of silicon nanosheets and their applications

    Energy Technology Data Exchange (ETDEWEB)

    Nakano, Hideyuki; Ikuno, Takashi [Toyota Central R& D Labs., Inc., 41-1 Yokomichi, Nagakute, Aichi 480-1192 (Japan)

    2016-12-15

    Two-dimensional silicon nanomaterials are expected to show different properties from those of bulk silicon materials by virtue of surface functionalization and quantum size effects. Since facile fabrication processes of large area silicon nanosheets (SiNSs) are required for practical applications, a development of soft chemical synthesis route without using conventional vacuum processes is a challenging issue. We have recently succeeded to prepare SiNSs with sub-nanometer thicknesses by exfoliating layered silicon compounds, and they are found to be composed of crystalline single-atom-thick silicon layers. In this review, we present the synthesis and modification methods of SiNSs. These SiNSs have atomically flat and smooth surfaces due to dense coverage of organic moieties, and they are easily self-assembled in a concentrated state to form a regularly stacked structure. We have also characterized the electron transport properties and the electronic structures of SiNSs. Finally, the potential applications of these SiNSs and organic modified SiNSs are also reviewed.

  18. Phonon shift in chemically exfoliated WS2 nanosheet

    Science.gov (United States)

    Sarkar, Abdus Salam; Pal, Suman Kalyan

    2018-04-01

    We have synthesized few layer WS2 nanosheets in a low boiling point solvent. Few layer of WS2 sheets are characterized by various techniques such as UV-visible and Raman spectroscopy, transmission electron microscopy (TEM), atomic force microscopy (AFM) and scanning electron microscopy (SEM). UV-Vis absorption spectra confirm the well dispersed in isopropyl alcohol. SEM and TEM images indicate the sheet like morphology of WS2. Atomic force microscopy image and room temperature Raman spectroscopy confirm the exfoliation of few layer (4-5 layer) of WS2. Further, Raman spectroscopy was used as a meteorology tool to determine the temperature co-efficient. We have systematically investigated the temperature dependent Raman spectroscopic behavior of few layer WS2. Our results depict the softening of the Raman modes E12g in plane vibration and A1g out of plane vibration with increasing the temperature from 77 K to 300 K. Softening of the Raman modes could be explained in terms of the double resonance which is active in the layered materials. The observed temperature coefficients for two Raman peaks E12g and A1g, are - 0.022 cm-1 and -0.009 cm-1, respectively.

  19. Bent silica nanosheets directed from crystalline templates controlled by proton donors

    International Nuclear Information System (INIS)

    Matsukizono, Hiroyuki; Jin, Ren-Hua

    2011-01-01

    Linear poly(ethyleneimine) (LPEI) is easily crystallizable with the formation of various morphologies in the aqueous medium when its hot solution cooled down to room temperature. Herein, we prepared a series of crystalline precipitates of LPEI grown in the presence of proton donating compounds such as Tris–HCl, tartaric acid, amino acids, and used the precipitates in directing silica deposition. Since the proton donating compounds can mediate the pH with donating the proton to LPEI, the crystallization of LPEI evidently depended on the concentrations of the proton donating compounds. It was found that the precipitates grown in the conditions of the pH ranged 8.2–8.5 directed well-controlled bent nanosheet of silica/LPEI composites. The bent nanosheet is constructed by multi-layered structures with a little slippage between layers. The bent nanosheet silica has slit-like pore with ca. 10 nm width.

  20. Holey two-dimensional transition metal oxide nanosheets for efficient energy storage

    Science.gov (United States)

    Peng, Lele; Xiong, Pan; Ma, Lu; Yuan, Yifei; Zhu, Yue; Chen, Dahong; Luo, Xiangyi; Lu, Jun; Amine, Khalil; Yu, Guihua

    2017-04-01

    Transition metal oxide nanomaterials are promising electrodes for alkali-ion batteries owing to their distinct reaction mechanism, abundant active sites and shortened ion diffusion distance. However, detailed conversion reaction processes in terms of the oxidation state evolution and chemical/mechanical stability of the electrodes are still poorly understood. Herein we explore a general synthetic strategy for versatile synthesis of various holey transition metal oxide nanosheets with adjustable hole sizes that enable greatly enhanced alkali-ion storage properties. We employ in-situ transmission electron microscopy and operando X-ray absorption structures to study the mechanical properties, morphology evolution and oxidation state changes during electrochemical processes. We find that these holey oxide nanosheets exhibit strong mechanical stability inherited from graphene oxide, displaying minimal structural changes during lithiation/delithiation processes. These holey oxide nanosheets represent a promising material platform for in-situ probing the electrochemical processes, and could open up opportunities in many energy storage and conversion systems.

  1. Cobalt nanosheet arrays supported silicon film as anode materials for lithium ion batteries

    International Nuclear Information System (INIS)

    Huang, X.H.; Wu, J.B.; Cao, Y.Q.; Zhang, P.; Lin, Y.; Guo, R.Q.

    2016-01-01

    Cobalt nanosheet arrays supported silicon film is prepared and used as anode materials for lithium ion batteries. The film is fabricated using chemical bath deposition, hydrogen reduction and radio-frequency magnetron sputtering techniques. The microstructure and morphology are characterized by means of scanning electron microscopy (SEM), transmission electron microscopy (TEM) and energy dispersive spectroscopy (EDS). In this composite film, the silicon layer is supported by interconnected aligned cobalt nanosheet arrays that act as the three-dimensional current collector and buffering network. The electrochemical performance as anode materials for lithium ion batteries is investigated by cyclic voltammetry (CV) and galvanostatic charge-discharge tests. The results show that the film prepared by sputtering for 1500 s exhibits high capacity, good rate capability and stable cycle ability. It is believed that the cobalt nanosheet arrays play important roles in the electrochemical performance of the silicon layer.

  2. Supercapacitors based on graphene-supported iron nanosheets as negative electrode materials.

    Science.gov (United States)

    Long, Conglai; Wei, Tong; Yan, Jun; Jiang, Lili; Fan, Zhuangjun

    2013-12-23

    We report a facile strategy to prepare iron nanosheets directly grown on graphene sheets nanocomposite (C-PGF) through the carbonization of iron ions adsorbed onto polyaniline nanosheet/graphene oxide hybrid material. Because of the synergistic effect of iron nanosheets and graphene sheets, the as-obtained C-PGF exhibits an ultrahigh capacitance of ca. 720 F g(-1) in 6 M KOH aqueous solution. Additionally, the assembled asymmetric supercapacitor (C-PGF//Ni(OH)2/CNTs) delivers a remarkable high power density and a noticeable ultrahigh energy density of ca. 140 Wh kg(-1) (based on the total mass of active materials) and an acceptable cycling performance of 78% retention after 2000 cycles. Therefore, the designed supercapacitors with high energy density, comparable to rechargeable lithium-ion batteries (LIBs), offer an important guideline for future design of advanced next-generation supercapacitors for both industrial and consumer applications.

  3. Spin polarized first principles study of Mn doped gallium nitride monolayer nanosheet

    Science.gov (United States)

    Sharma, Venus; Kaur, Sumandeep; Srivastava, Sunita; Kumar, Tankeshwar

    2017-05-01

    The structural, electronic and magnetic properties of gallium nitride nanosheet (GaNs) doped with Mn atoms have been studied using spin polarized density functional theory. The binding energy per atom, Energy Band gap, Fermi energy, magnetic moment, electric dipole moment have been found. The doped nanosheet is found to be more stable than pure GaN monolayer nanosheet. Adsorption of Mn atom has been done at four different sites on GaNs which affects the fermi level position. It is found that depending on the doping site, Mn can behave both like p-type semiconductor and also as n-type semiconductor. Also, it is ascertained that Mn doped GaNs (GaNs-Mn) exhibits ferromagnetic behavior.

  4. Hydroxyapatite grafted carbon nanotubes and graphene nanosheets: Promising bone implant materials

    Science.gov (United States)

    Oyefusi, Adebola; Olanipekun, Opeyemi; Neelgund, Gururaj M.; Peterson, Deforest; Stone, Julia M.; Williams, Ebonee; Carson, Laura; Regisford, Gloria; Oki, Aderemi

    2014-11-01

    In the present study, hydroxyapatite (HA) was successfully grafted to carboxylated carbon nanotubes (CNTs) and graphene nanosheets. The HA grafted CNTs and HA-graphene nanosheets were characterized using FT-IR, TGA, SEM and X-ray diffraction. The HA grafted CNTs and graphene nanosheets (CNTs-HA and Gr-HA) were further used to examine the proliferation and differentiation rate of temperature-sensitive human fetal osteoblastic cell line (hFOB 1.19). Total protein assays and western blot analysis of osteocalcin expression were used as indicators of cell proliferation and differentiation. Results indicated that hFOB 1.19 cells proliferate and differentiate well in treatment media containing CNTs-HA and graphene-HA. Both CNTs-HA and graphene-HA could be promising nanomaterials for use as scaffolds in bone tissue engineering.

  5. Hydroxyapatite grafted carbon nanotubes and graphene nanosheets: promising bone implant materials.

    Science.gov (United States)

    Oyefusi, Adebola; Olanipekun, Opeyemi; Neelgund, Gururaj M; Peterson, Deforest; Stone, Julia M; Williams, Ebonee; Carson, Laura; Regisford, Gloria; Oki, Aderemi

    2014-11-11

    In the present study, hydroxyapatite (HA) was successfully grafted to carboxylated carbon nanotubes (CNTs) and graphene nanosheets. The HA grafted CNTs and HA-graphene nanosheets were characterized using FT-IR, TGA, SEM and X-ray diffraction. The HA grafted CNTs and graphene nanosheets (CNTs-HA and Gr-HA) were further used to examine the proliferation and differentiation rate of temperature-sensitive human fetal osteoblastic cell line (hFOB 1.19). Total protein assays and western blot analysis of osteocalcin expression were used as indicators of cell proliferation and differentiation. Results indicated that hFOB 1.19 cells proliferate and differentiate well in treatment media containing CNTs-HA and graphene-HA. Both CNTs-HA and graphene-HA could be promising nanomaterials for use as scaffolds in bone tissue engineering. Copyright © 2014 Elsevier B.V. All rights reserved.

  6. Mn3O4 nanoparticles embedded into graphene nanosheets: Preparation, characterization, and electrochemical properties for supercapacitors

    International Nuclear Information System (INIS)

    Wang Bei; Park, Jinsoo; Wang Chengyin; Ahn, Hyojun; Wang, Guoxiu

    2010-01-01

    Mn 3 O 4 /graphene nanocomposites were synthesized by mixing graphene suspension in ethylene glycol with MnO 2 organosol, followed by subsequent ultrasonication processing and heat treatment. The as-prepared product consists of nanosized Mn 3 O 4 particles homogeneously distributed on graphene nanosheets, which has been confirmed by field emission scanning electron microscopy and transmission electron microscopy analysis. Atomic force microscope analysis further identified the distribution of dense Mn 3 O 4 nanoparticles on graphene nanosheets. When used as electrode materials in supercapacitors, Mn 3 O 4 /graphene nanocomposites exhibited a high specific capacitance of 175 F g -1 in 1 M Na 2 SO 4 electrolyte and 256 F g -1 in 6 M KOH electrolyte, respectively. The enhanced supercapacitance of Mn 3 O 4 /graphene nanocomposites could be ascribed to both electrochemical contributions of Mn 3 O 4 nanoparticles, functional groups attached to graphene nanosheets, and significantly increased specific surface area.

  7. Ultrathin mesoporous Co3O4 nanosheets on Ni foam for high-performance supercapacitors

    International Nuclear Information System (INIS)

    Qiu, Kangwen; Lu, Yang; Cheng, Jinbing; Yan, Hailong; Hou, Xiaoyi; Zhang, Deyang; Lu, Min; Liu, Xianming; Luo, Yongsong

    2015-01-01

    Ultrathin Co 3 O 4 nanosheets with a mesoporous structure and a large surface area are hydrothermally grown on a three dimensional nickel foam. The ultrathin mesoporous Co 3 O 4 nanosheets are grown on Ni foam with robust adhesion, which endows fast ion and electron transport, large electroactive surface area, and excellent structural stability. Such unique nanoarchitecture exhibits remarkable electrochemical performance with high capacitance and desirable cycle life. When evaluate as an electrode material for supercapacitors, the Co 3 O 4 nanosheets electrode is able to deliver high specific capacitance of 2194 F g −1 at a current density of 1 A g −1 in 1 M KOH aqueous solution. The electrode also exhibits excellent cycling stability by retaining 93.1% of the maximum capacitance after 5000 charge-discharge cycles. The fabrication strategy presented here is facile, cost-effective, and can offer a way for energy storage device applications

  8. Hierarchical Pd-Sn alloy nanosheet dendrites: an economical and highly active catalyst for ethanol electrooxidation.

    Science.gov (United States)

    Ding, Liang-Xin; Wang, An-Liang; Ou, Yan-Nan; Li, Qi; Guo, Rui; Zhao, Wen-Xia; Tong, Ye-Xiang; Li, Gao-Ren

    2013-01-01

    Hierarchical alloy nanosheet dendrites (ANSDs) are highly favorable for superior catalytic performance and efficient utilization of catalyst because of the special characteristics of alloys, nanosheets, and dendritic nanostructures. In this paper, we demonstrate for the first time a facile and efficient electrodeposition approach for the controllable synthesis of Pd-Sn ANSDs with high surface area. These synthesized Pd-Sn ANSDs exhibit high electrocatalytic activity and superior long-term cycle stability toward ethanol oxidation in alkaline media. The enhanced electrocataytic activity of Pd-Sn ANSDs may be attributed to Pd-Sn alloys, nanosheet dendrite induced promotional effect, large number of active sites on dendrite surface, large surface area, and good electrical contact with the base electrode. Because of the simple implement and high flexibility, the proposed approach can be considered as a general and powerful strategy to synthesize the alloy electrocatalysts with high surface areas and open dendritic nanostructures.

  9. Controlled synthesis of triangular and hexagonal Ni nanosheets and their size-dependent properties

    International Nuclear Information System (INIS)

    Leng Yonghua; Wang Yuntao; Li Xingguo; Liu Tong; Takahashhi, Seiki

    2006-01-01

    A solution phase method has been used to synthesize triangular and hexagonal Ni nanosheets with different edge lengths by controlling the reaction kinetics. This procedure is realized by introducing Fe(CO) 5 into the reaction system to slow the formation rate of Ni(0). The introduced Fe(CO) 5 exists as Fe(III) ions in the solution, which could oxidize Ni(0) back to Ni(II). By controlling the nucleation density, the sheet edge lengths could be changed from 19 nm to several hundreds of nanometres. The Ni nanosheets exhibit the transition from superparamagnetism to ferromagnetism with increasing sheet edge lengths. Their blocking temperature decreases with applied field and increasing sheet edge lengths. The Ni nanosheets also exhibit a surface plasmon resonance (SPR) feature, which is quite different from that of the Ni nanoparticles

  10. Effect of titania addition on the thermal conductivity of UO2 fuel [Paper IIIB-C

    International Nuclear Information System (INIS)

    Sengupta, A.K.; Kumar, A.; Arora, K.B.S.; Pandey, V.D.; Nair, M.R.; Kamath, H.S.

    1986-01-01

    Pellet clad interaction in nuclear reactor fuel elements can be reduced by the use of higher grain size UO 2 fuel. This is achieved by the addition of dopant like titania, niobia etc. However, these dopants are considered as impurities which may affect the thermophysical and thermomechanical properties of the fuel. Thermal Conductivity which is one of the important properties controlling the inpile performance of the fuel has been measured for pure UO 2 and UO 2 containing 0.05wt per cent and 0.1wt per cent TiO 2 in the temperature range 900K to 1900K in vacuum. Thermal conductivity was obtained from thermal diffusivity data measured by laser flash method. The paper highlights the experimental results and discusses the effect of TiO 2 on the thermal conductivity of UO 2 fuel. (author)

  11. Critical Filler Concentration in Sulfated Titania-Added Nafion™ Membranes for Fuel Cell Applications

    Directory of Open Access Journals (Sweden)

    Mirko Sgambetterra

    2016-04-01

    Full Text Available In this communication we present a detailed study of Nafion™ composite membranes containing different amounts of nanosized sulfated titania particles, synthesized through an optimized one-step synthesis procedure. Functional membrane properties, such as ionic exchange capacity and water uptake (WU ability will be described and discussed, together with thermal analysis, atomic force microscopy and Raman spectroscopy data. Also electrochemical properties such as proton conductivity and performances in hydrogen fuel cells will be presented. It has been demonstrated that a critical concentration of filler particles can boost the fuel cell performance at low humidification, exhibiting a significant improvement of the maximum power and current density delivered under 30% low-relative humidity (RH and 70 °C with respect to bare Nafion™-based systems.

  12. Optimization of mechanical strength of titania fibers fabricated by direct drawing

    Science.gov (United States)

    Hanschmidt, Kelli; Tätte, Tanel; Hussainova, Irina; Part, Marko; Mändar, Hugo; Roosalu, Kaspar; Chasiotis, Ioannis

    2013-11-01

    Nanostructured polycrystalline titania (TiO2) microfibers were produced by direct drawing from visco-elastic alkoxide precursors. The fiber crystallinity and grain size were shown to depend on post-treatment calcination temperature. Tensile tests with individual fibers showed strong sensitivity of the elastic modulus and the tensile strength to microstructural details of the fibers. The elastic modulus of as-fabricated fibers increased about 10 times after calcination at 700 ∘C, while the strain at failure remained almost the same at ˜1.4 %. The highest tensile strength of more than 800 MPa was exhibited by nanoscale grained fibers with a bimodal grain size distribution consisting of rutile grains embedded into an anatase matrix. This structure is believed to have reduced the critical defect size, and thus increased the tensile strength. The resultant fibers showed properties that were appropriate for reinforcement of different matrixes.

  13. Nanomanufacturing of titania interfaces with controlled structural and functional properties by supersonic cluster beam deposition

    Energy Technology Data Exchange (ETDEWEB)

    Podestà, Alessandro, E-mail: alessandro.podesta@mi.infn.it, E-mail: pmilani@mi.infn.it; Borghi, Francesca; Indrieri, Marco; Bovio, Simone; Piazzoni, Claudio; Milani, Paolo, E-mail: alessandro.podesta@mi.infn.it, E-mail: pmilani@mi.infn.it [Centro Interdisciplinare Materiali e Interfacce Nanostrutturati (C.I.Ma.I.Na.), Dipartimento di Fisica, Università degli Studi di Milano, via Celoria 16, 20133 Milano (Italy)

    2015-12-21

    Great emphasis is placed on the development of integrated approaches for the synthesis and the characterization of ad hoc nanostructured platforms, to be used as templates with controlled morphology and chemical properties for the investigation of specific phenomena of great relevance in interdisciplinary fields such as biotechnology, medicine, and advanced materials. Here, we discuss the crucial role and the advantages of thin film deposition strategies based on cluster-assembling from supersonic cluster beams. We select cluster-assembled nanostructured titania (ns-TiO{sub 2}) as a case study to demonstrate that accurate control over morphological parameters can be routinely achieved, and consequently, over several relevant interfacial properties and phenomena, like surface charging in a liquid electrolyte, and proteins and nanoparticles adsorption. In particular, we show that the very good control of nanoscale morphology is obtained by taking advantage of simple scaling laws governing the ballistic deposition regime of low-energy, mass-dispersed clusters with reduced surface mobility.

  14. Laser-induced incandescence of titania nanoparticles synthesized in a flame

    Science.gov (United States)

    Cignoli, F.; Bellomunno, C.; Maffi, S.; Zizak, G.

    2009-09-01

    Laser induced incandescence experiments were carried out in a flame reactor during titania nanoparticle synthesis. The structure of the reactor employed allowed for a rather smooth particle growth along the flame axis, with limited mixing of different size particles. Particle incandescence was excited by the 4th harmonic of a Nd:YAG laser. The radiation emitted from the particles was recorded in time and checked by spectral analysis. Results were compared with measurements from transmission electron microscopy of samples taken at the same locations probed by incandescence. This was done covering a portion of the flame length within which a particle size growth of a factor of about four was detected . The incandescence decay time was found to increase monotonically with particle size. The attainment of a process control tool in nanoparticle flame synthesis appears to be realistic.

  15. Effect of titania addition on the thermal conductivity of UO2 fuel (Paper IIIB-C)

    Energy Technology Data Exchange (ETDEWEB)

    Sengupta, A K; Kumar, A; Arora, K B.S.; Pandey, V D; Nair, M R; Kamath, H S

    1986-01-01

    Pellet clad interaction in nuclear reactor fuel elements can be reduced by the use of higher grain size UO2 fuel. This is achieved by the addition of dopant like titania, niobia etc. However, these dopants are considered as impurities which may affect the thermophysical and thermomechanical properties of the fuel. Thermal Conductivity which is one of the important properties controlling the inpile performance of the fuel has been measured for pure UO2 and UO2 containing 0.05wt per cent and 0.1wt per cent TiO2 in the temperature range 900K to 1900K in vacuum. Thermal conductivity was obtained from thermal diffusivity data measured by laser flash method. The paper highlights the experimental results and discusses the effect of TiO2 on the thermal conductivity of UO2 fuel. 5 figures.

  16. Photodegradation of Reactive Golden Yellow R Dye Catalyzed by Effective Titania (TiO2)

    International Nuclear Information System (INIS)

    Bedurus, E.A.; Marinah Mohd Ariffin; Mohd Hasmizam Razali

    2015-01-01

    In the present research, Microwave Assisted Synthesis (MAS) method was applied to synthesize titania (TiO 2 ) at 150 degree Celsius in a range of 2-6 hours heating time. Each prepared TiO 2 were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD) and nitrogen gas (N 2 ) sorption analysis (Brunaeur-Emmett-Teller (BET) and Barrett-Joyner-Halenda (BJH) calculation) techniques. The TiO 2 prepared by MAS 150 degree Celsius (4 hours) has emerged with the highest photo catalytic activity. Within 4 hours, the TiO 2 managed to catalyze the degradation of Reactive Golden Yellow R dye up to 98.51 %. This is because of the TiO 2 possessed high crystallinity of anatase phase, small crystallite size and high pore volume compared to other prepared TiO 2 . (author)

  17. The influence of sodium lauryl sulfate on the crystal phases of titania by hydrothermal method

    Science.gov (United States)

    Liu, Chaohong; Wang, Xin

    2012-11-01

    In this paper, we prepared TiO2 nanostructures by a hydrothermal method and investigated the influence of the SO4^{2-} ion and the effect of long alkyl chains of sodium dodecyl sulfate on the crystal phases of TiO2 by experiments and theoretical calculations. The results indicate that the absorption of the H+HSO4 fragment on rutile (110) is more stable than that of the 2H+SO4 fragment and more favorable to the formation of anatase. The absorption and steric effects of sodium dodecyl sulfate on the surfaces of TiO2 grains also have an important influence on the formation of mixed crystals by changing the speed and the way of octahedral TiO6 units combining. Based on the above facts, we revised the original reaction scheme for crystalline titania formation by previous authors.

  18. Double-side illuminated titania nanotubes for high volume hydrogen generation by water splitting

    Science.gov (United States)

    Mohapatra, Susanta K.; Mahajan, Vishal K.; Misra, Mano

    2007-11-01

    A sonoelectrochemical anodization method is proposed to synthesize TiO2 nanotubular arrays on both sides of a titanium foil (TiO2/Ti/TiO2). Highly ordered TiO2 nanotubular arrays of 16 cm2 area with uniform surface distribution can be obtained using this anodization procedure. These double-sided TiO2/Ti/TiO2 materials are used as both photoanode (carbon-doped titania nanotubes) and cathode (Pt nanoparticles dispersed on TiO2 nanotubes; PtTiO2/Ti/PtTiO2) in a specially designed photoelectrochemical cell to generate hydrogen by water splitting at a rate of 38 ml h-1. The nanomaterials are characterized by FESEM, HRTEM, STEM, EDS, FFT, SAED and XPS techniques. The present approach can be used for large-scale hydrogen generation using renewable energy sources.

  19. On the morphology and potential application of polydimethylsiloxane-silica-titania composites

    Directory of Open Access Journals (Sweden)

    2011-02-01

    Full Text Available Polydimethylsiloxane-α,ω-diol was used as matrix for the preparation of polysiloxane-SiO2-TiO2 composites through in situ incorporation of silica and titania using a solvent-free sol-gel procedure. For this purpose, oxide precursors tetraethyl-orthosilicate and tetrabutyl-orthotitanate, and a proper condensation catalyst, viz. dibuthyltin dilaurate, were added in pre-established amounts to the polymer. The hydrolysis and condensation reactions take place under mild conditions, with the formation of silicon and titanium oxide networks and polymer crosslinking. The effect of SiO2 and TiO2 mass ratio on the morphology of the composites was investigated by scanning electron microscopy (SEM and X-rays diffraction (XRD, and interpreted in correlation with differential scanning calorimetry (DSC and energy-dispersive X-ray spectroscopy (EDX data. The film samples were tested as active elements in actuation devices.

  20. Preparation and Characterization of Highly Spherical Silica-titania Aerogel Beads with High Surface Area

    Directory of Open Access Journals (Sweden)

    YU Yu-xi

    2017-02-01

    Full Text Available The silica-titania aerogel beads were synthesized through sol-gel reaction followed by supercritical drying, in which TEOS and TBT as co-precursors, EtOH as solvents, HAC and NH3·H2O as catalysts. The as-prepared aerogel beads were characterized by SEM,TEM,XRD,FT-IR,TG-DTA and nitrogen adsorption-desorption. The results indicate that the diameter distribution of beads are between 1-8mm, the average diameter of beads is 3.5mm. The aerogel beads have nanoporous network structure with high specific surface area of 914.5m2/g, and the TiO2 particles are distributed in the aerogel uniformly, which keep the anatase crystal under high temperature.

  1. Photocatalytic degradation of selected herbicides in aqueous suspensions of doped titania under visible light irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Sojic, Daniela V., E-mail: daniela.sojic@dh.uns.ac.rs [Department of Chemistry, Biochemistry and Environmental Protection, Faculty of Sciences, University of Novi Sad, Trg D. Obradovica 3, 21000 Novi Sad (Serbia); Despotovic, Vesna N., E-mail: vesna.despotovic@dh.uns.ac.rs [Department of Chemistry, Biochemistry and Environmental Protection, Faculty of Sciences, University of Novi Sad, Trg D. Obradovica 3, 21000 Novi Sad (Serbia); Abazovic, Nadica D., E-mail: kiki@vinca.rs [Vinca Institute of Nuclear Sciences, 11001 Beograd, PO Box 522 (Serbia); Comor, Mirjana I., E-mail: mirjanac@vinca.rs [Vinca Institute of Nuclear Sciences, 11001 Beograd, PO Box 522 (Serbia); Abramovic, Biljana F., E-mail: biljana.abramovic@dh.uns.ac.rs [Department of Chemistry, Biochemistry and Environmental Protection, Faculty of Sciences, University of Novi Sad, Trg D. Obradovica 3, 21000 Novi Sad (Serbia)

    2010-07-15

    The aim of this work was to study the efficiency of Fe- and N-doped titania suspensions in the photocatalytic degradation of the herbicides RS-2-(4-chloro-o-tolyloxy)propionic acid (mecoprop, MCPP), (4-chloro-2-methylphenoxy)acetic acid (MCPA), and 3,6-dichloropyridine-2-carboxylic acid (clopyralid, CP) under the visible light ({lambda} {>=} 400 nm) irradiation. The obtained results were compared with those of the corresponding undoped TiO{sub 2} (rutile/anatase) and of the most frequently used TiO{sub 2} Degussa P25. Computational modeling procedures were used to optimize geometry and molecular electrostatic potentials of MCPP, MCPA and CP and discuss the obtained results. The results indicate that the efficiency of photocatalytic degradation is greatly influenced by the molecular structure of the compound. Lowering of the band gap of titanium dioxide by doping is not always favorable for increasing photocatalytic efficiency of degradation.

  2. Nanomanufacturing of titania interfaces with controlled structural and functional properties by supersonic cluster beam deposition

    International Nuclear Information System (INIS)

    Podestà, Alessandro; Borghi, Francesca; Indrieri, Marco; Bovio, Simone; Piazzoni, Claudio; Milani, Paolo

    2015-01-01

    Great emphasis is placed on the development of integrated approaches for the synthesis and the characterization of ad hoc nanostructured platforms, to be used as templates with controlled morphology and chemical properties for the investigation of specific phenomena of great relevance in interdisciplinary fields such as biotechnology, medicine, and advanced materials. Here, we discuss the crucial role and the advantages of thin film deposition strategies based on cluster-assembling from supersonic cluster beams. We select cluster-assembled nanostructured titania (ns-TiO 2 ) as a case study to demonstrate that accurate control over morphological parameters can be routinely achieved, and consequently, over several relevant interfacial properties and phenomena, like surface charging in a liquid electrolyte, and proteins and nanoparticles adsorption. In particular, we show that the very good control of nanoscale morphology is obtained by taking advantage of simple scaling laws governing the ballistic deposition regime of low-energy, mass-dispersed clusters with reduced surface mobility

  3. Single-crystalline self-branched anatase titania nanowires for dye-sensitized solar cells

    Science.gov (United States)

    Li, Zhenquan; Yang, Huang; Wu, Fei; Fu, Jianxun; Wang, Linjun; Yang, Weiguang

    2017-03-01

    The morphology of the anatase titania plays an important role in improving the photovoltaic performance in dye-sensitized solar cells. In this work, single-crystalline self-branched anatase TiO2 nanowires have been synthesized by hydrothermal method using TBAH and CTAB as morphology controlling agents. The obtained self-branched TiO2 nanowires dominated by a large percentage of (010) facets. The photovoltaic conversion efficiency (6.37%) of dye-sensitized solar cell (DSSC) based on the self-branched TiO2 nanowires shows a significant improvement (26.6%) compared to that of P25 TiO2 (5.03%). The enhanced performance of the self-branched TiO2 nanowires-based DSSC is due to heir large percent of exposed (010) facets which have strong dye adsorption capacity and effective charge transport of the self-branched 1D nanostructures.

  4. Efficient adsorption concentration and photolysis of acetaldehyde on titania-mesoporous silica composite

    Science.gov (United States)

    Yamaguchi, Satoshi; Matsumoto, Akihiko

    2017-07-01

    Titania-mesoporous silica composite (TiO2/MCM) was prepared by hydrolysis of titaniumtetraisopropoxide (TTIP) with the presence of mesoporous silica MCM-41. The TiO2/MCM samples consisted of highly dispersed TiO2 on the surface of MCM-41. Dynamic adsorption and photocatalytic decomposition features for acetaldehyde (CH3CHO) were measured by flow method. The amount of CH3CHO decomposition on TiO2/MCM-41 increased with the TiO2 amount, suggesting that a large amount of CH3CHO was adsorbed on mesopores of MCM-41 of the TiO2/MCM and was efficiently decomposed on finely dispersed TiO2 surface by ultraviolet irradiation.

  5. A Convenient and Templated Method for the Fabrication of Monodisperse Micrometer Hollow Titania Spheres

    Directory of Open Access Journals (Sweden)

    Haibo Yao

    2013-01-01

    Full Text Available A simple and widely applicable methodology was presented to synthesize monodisperse micrometer hollow titania spheres (HTS based on the templating method. It was performed by using the preformed poly(styrene-acrylic acid (PSA as template spheres which was mixed with tetrabutyltitanate (TBOT in an ethanol solvent under steam treatment. The HTS which were obtained by the calcination of PSA/TiO2 composite core-shell spheres had a narrow particle size distribution and commendable surface topography characterized by SEM. The calcined HTS at 500°C displayed crystalline reflection peaks that were characteristic to the anatase phase by XRD. Moreover, some key influencing factors including TBOT concentration and reaction time were analyzed. As expected, the diameter of HTS could be readily controlled by altering the size of PSA template spheres. In addition, the approach was also applied to fabricate hollow zirconia spheres and other inorganic spheres.

  6. Nanocasting of Periodic Mesoporous Materials as an Effective Strategy to Prepare Mixed Phases of Titania

    Directory of Open Access Journals (Sweden)

    Luther Mahoney

    2015-12-01

    Full Text Available Mesoporous titanium dioxide materials were prepared using a nanocasting technique involving silica SBA-15 as the hard-template. At an optimal loading of titanium precursor, the hexagonal periodic array of pores in SBA-15 was retained. The phases of titanium dioxide could be easily varied by the number of impregnation cycles and the nature of titanium alkoxide employed. Low number of impregnation cycles produced mixed phases of anatase and TiO2(B. The mesoporous TiO2 materials were tested for solar hydrogen production, and the material consisting of 98% anatase and 2% TiO2(B exhibited the highest yield of hydrogen from the photocatalytic splitting of water. The periodicity of the pores was an important factor that influenced the photocatalytic activity. This study indicates that mixed phases of titania containing ordered array of pores can be prepared by using the nanocasting strategy.

  7. Nafion Titania Nanotubes Nanocomposite Electrolytes for High-Temperature Direct Methanol Fuel Cells

    Directory of Open Access Journals (Sweden)

    Nonhlanhla Precious Cele

    2012-01-01

    Full Text Available Nafion-based nanocomposite membranes containing various amounts of titania nanotubes (TNTs as an inorganic filler have been prepared using melt-mixing method and have been investigated for proton exchange membrane applications. The one-dimensional TNTs have been prepared from potassium hydroxide using hydrothermal route and conventional heating. Nafion R1100 in a protonated form was used, and TNT contents were in a range of 0.5–2.0 wt%. The acid-treated composite membranes, at lowest inorganic additive content, exhibited improved properties in terms of thermal stability and methanol (MeOH permeability. The best performing nanocomposite was the membrane containing only 0.5 wt% TNTs showing ionic conductivity value of 7.2×10-2 S·cm-1 at 26°C and 100% of relative humidity.

  8. Nanomanufacturing of titania interfaces with controlled structural and functional properties by supersonic cluster beam deposition

    Science.gov (United States)

    Podestà, Alessandro; Borghi, Francesca; Indrieri, Marco; Bovio, Simone; Piazzoni, Claudio; Milani, Paolo

    2015-12-01

    Great emphasis is placed on the development of integrated approaches for the synthesis and the characterization of ad hoc nanostructured platforms, to be used as templates with controlled morphology and chemical properties for the investigation of specific phenomena of great relevance in interdisciplinary fields such as biotechnology, medicine, and advanced materials. Here, we discuss the crucial role and the advantages of thin film deposition strategies based on cluster-assembling from supersonic cluster beams. We select cluster-assembled nanostructured titania (ns-TiO2) as a case study to demonstrate that accurate control over morphological parameters can be routinely achieved, and consequently, over several relevant interfacial properties and phenomena, like surface charging in a liquid electrolyte, and proteins and nanoparticles adsorption. In particular, we show that the very good control of nanoscale morphology is obtained by taking advantage of simple scaling laws governing the ballistic deposition regime of low-energy, mass-dispersed clusters with reduced surface mobility.

  9. Photocatalysis of methylene blue contaminated water using titania fiber doped with silicon

    International Nuclear Information System (INIS)

    Ugarteche, C.V.; Alves, A.K.; Berutti, F.A.; Bergmann, C.P.

    2009-01-01

    In this work, titania fibers doped with silicon were synthesized by electro spinning methodology, using titanium propoxide, silicon tetra propoxide and a solution of polyvinylpyrrolidone as precursors. The non-tissue material obtained was characterized by X-ray diffraction to determine the phase and crystallite size, BET method to determine the surface and SEM to analyze the microstructure of the fibers. The photo catalytic activity of the fibers in comparison with the standard TiO 2 Degussa P25 was evaluated using a 20ppm methylene blue solution. The composition containing 30% of silicon kept the anatase phase stable until the heat treatment temperature of 800 deg C. In the other compositions there was a formation of the rutile phase, which is less photoactive. The compositions containing silicon were photo catalytic efficient and some of them were more active that the standard P25. (author)

  10. Manufacturing a durable superhydrophobic polypropylene coating on aluminum alloy substrate by adding nano-titania nanoparticles.

    Science.gov (United States)

    Jiang, Haiyun; Wu, Ruomei; Hu, Zhongliang; Yuan, Zhiqing; Zhao, Xuehui; Liu, Qilong

    2014-07-01

    A superhydrophobic polypropylene (PP) coating on the surface of aluminum alloy coupons is unstable because of the existence of metastable state in curing process. Nano-titania particles were added into PP solution to form hierarchical micro- and nano-structures of PP coatings on the surface of aluminum alloy coupons. The morphology of the coatings was observed with Scanning Electron Microscopy (SEM), and the corresponding structure and components were investigated with Energy Dispersive Spectrometer (EDS) and X-ray diffractometer (XRD), respectively. The results indicated that nano-TiO2 particles are the main nucleation cores in the curing of the coatings; PP in solution is enclosed in these cores and crystallizes gradually. The coatings can preserve the stable micro- and nano-structure on six months due to the nucleation action of nano-TiO2 particles, and its durable water contact angle (WCA) is about 164 +/- 1.5 degrees.

  11. Sol-gel formed spherical nanostructured titania based liquefied petroleum gas sensor

    Science.gov (United States)

    Sabhajeet, S. R.; Yadav, B. C.; Sonker, Rakesh K.

    2018-05-01

    The present work reports the preparation of Titania(TiO2) thin film by sol-gel technique and its Liquefied Petroleum Gas (LPG) sensing. TiO2 exists in numerous phases possessing different structural properties like amorphous, anatase or anatase/rutile mixed phases. The structural analysis confirmed the formation of TiO2 having an average crystallite size 21 nm. SEM showed the regular and porous surface morphology. The band gap of the material was found as 3.65 eV. This film was employed for LPG sensing and variations in resistance with exposure of LPG were observed. Sensor response (S) as a function of time was calculated and its maximum value was found as 2.8 for 4% vol. of LPG with a response and recovery times of 240 sec and 248 sec respectively.

  12. Synthesis and properties of electrically conductive, ductile, extremely long (~50 μm) nanosheets of K(x)CoO2·yH2O.

    Science.gov (United States)

    Aksit, Mahmut; Hoselton, Benjamin C; Kim, Ha Jun; Ha, Don-Hyung; Robinson, Richard D

    2013-09-25

    Extremely long, electrically conductive, ductile, free-standing nanosheets of water-stabilized KxCoO2·yH2O are synthesized using the sol-gel and electric-field induced kinetic-demixing (SGKD) process. Room temperature in-plane resistivity of the KxCoO2·yH2O nanosheets is less than ~4.7 mΩ·cm, which corresponds to one of the lowest resistivity values reported for metal oxide nanosheets. The synthesis produces tens of thousands of very high aspect ratio (50,000:50,000:1 = length/width/thickness), millimeter length nanosheets stacked into a macro-scale pellet. Free-standing nanosheets up to ~50 μm long are readily delaminated from the stacked nanosheets. High-resolution transmission electron microscopy (HR-TEM) studies of the free-standing nanosheets indicate that the delaminated pieces consist of individual nanosheet crystals that are turbostratically stacked. X-ray diffraction (XRD) studies confirm that the nanosheets are stacked in perfect registry along their c-axis. Scanning electron microscopy (SEM) based statistical analysis show that the average thickness of the nanosheets is ~13 nm. The nanosheets show ductility with a bending radius as small as ~5 nm.

  13. Multifunctional nanosheets based on folic acid modified manganese oxide for tumor-targeting theranostic application

    Science.gov (United States)

    Hao, Yongwei; Wang, Lei; Zhang, Bingxiang; Zhao, Hongjuan; Niu, Mengya; Hu, Yujie; Zheng, Cuixia; Zhang, Hongling; Chang, Junbiao; Zhang, Zhenzhong; Zhang, Yun

    2016-01-01

    It is highly desirable to develop smart nanocarriers with stimuli-responsive drug-releasing and diagnostic-imaging functions for cancer theranostics. Herein, we develop a reduction and pH dual-responsive tumor theranostic platform based on degradable manganese dioxide (MnO2) nanosheets. The MnO2 nanosheets with a size of 20-60 nm were first synthesized and modified with (3-Aminopropyl) trimethoxysilane (APTMS) to get amine-functionalized MnO2, and then functionalized by NH2-PEG2000-COOH (PEG). The tumor-targeting group, folic acid (FA), was finally conjugated with the PEGylated MnO2 nanosheets. Then, doxorubicin (DOX), a chemotherapeutic agent, was loaded onto the modified nanosheets through a physical adsorption, which was designated as MnO2-PEG-FA/DOX. The prepared MnO2-PEG-FA/DOX nanosheets with good biocompatibility can not only efficiently deliver DOX to tumor cells in vitro and in vivo, leading to enhanced anti-tumor efficiency, but can also respond to a slightly acidic environment and high concentration of reduced glutathione (GSH), which caused degradation of MnO2 into manganese ions enabling magnetic resonance imaging (MRI). The longitudinal relaxation rate r 1 was 2.26 mM-1 s-1 at pH 5.0 containing 2 mM GSH. These reduction and pH dual-responsive biodegradable nanosheets combining efficient MRI and chemotherapy provide a novel and promising platform for tumor-targeting theranostic application.

  14. Evaluating Mechanical Properties of Few Layers MoS2 Nanosheets-Polymer Composites

    Directory of Open Access Journals (Sweden)

    Muhammad Bilal Khan

    2017-01-01

    Full Text Available The reinforcement effects of liquid exfoliated molybdenum disulphide (MoS2 nanosheets, dispersed in polystyrene (PS matrix, are evaluated here. The range of composites (0~0.002 volume fraction (Vf MoS2-PS is prepared via solution casting. Size selected MoS2 nanosheets (3~4 layers, with a lateral dimension L 0.5~1 µm, have improved Young’s modulus up to 0.8 GPa for 0.0002 Vf MoS2-PS as compared to 0.2 GPa observed for PS only. The ultimate tensile strength (UTS is improved considerably (~×3 with a minute addition of MoS2 nanosheets (0.00002 Vf. The MoS2 nanosheets lateral dimension and number of layers are approximated using atomic force microscopy (AFM. The composites formation is confirmed using X-ray diffraction (XRD and scanning electron microscopy (SEM. Theoretical predicted results (Halpin-Tsai model are well below the experimental findings, especially at lower concentrations. Only at maximum concentrations, the experimental and theoretical results coincide. The high aspect ratio of MoS2 nanosheets, homogeneous dispersion inside polymer, and their probable planar orientation are the possible reasons for the effective stress transfer, resulting in enhanced mechanical characteristics. Moreover, the micro-Vickers hardness (HV of the MoS2-PS is also improved from 19 (PS to 23 (0.002 Vf MoS2-PS as MoS2 nanosheets inclusion may hinder the deformation more effectively.

  15. Molecular adsorption of hydrogen peroxide on N- and Fe-doped titania nanoclusters

    Energy Technology Data Exchange (ETDEWEB)

    Mohajeri, Afshan, E-mail: amohajeri@shirazu.ac.ir; Dashti, Nasimeh Lari

    2017-06-15

    Highlights: • The stability and electronic properties of N/Fe-doped (TiO{sub 2}){sub n} clusters with n = 5,6 were studied. • The adsorption H{sub 2}O{sub 2} on the surface of doped clusters has been investigated. • This is the first report of H{sub 2}O{sub 2} adsorption onto the (TiO{sub 2}){sub n} cluster in the presence of metal and non-metal dopants. • The effect of N and Fe dopants on interaction strength was studied. - Abstract: Titanium dioxide (titania) nanoparticles have been extensively investigated for photocatalytic applications such as the decomposition and adsorption of pollutant and undesirable compound in air and waste water. In this context, the present article reports the molecular adsorption of hydrogen peroxide on the surface of doped titania clusters. Density functional theory calculations were performed to investigate the structures and electronic properties of two nanoscale (TiO{sub 2}){sub n} clusters (n = 5,6) modified by nitrogen and iron dopants. The relative stability of all possible N-doped and Fe-doped isomers has been compared with each other and with the parent cluster. It was found that the Fe-doped clusters are in general more stable than the N-doped counterparts. Moreover, after N/Fe doping an enhanced in the magnetization of the clusters is observed. In the second part, we have investigated different modes of H{sub 2}O{sub 2} adsorption on the lowest-energy isomers of doped clusters. In almost all the cases, the adsorptions on the doped clusters are found to be less exothermic than on the corresponding undoped parent cluster. Our results highlight the essential role of charge transfer into the interaction between H{sub 2}O{sub 2} and doped (TiO{sub 2}){sub n} clusters, especially for Fe-doped clusters.

  16. Inhibited Bacterial Adhesion and Biofilm Formation on Quaternized Chitosan-Loaded Titania Nanotubes with Various Diameters

    Directory of Open Access Journals (Sweden)

    Wen-tao Lin

    2016-03-01

    Full Text Available Titania nanotube-based local drug delivery is an attractive strategy for combating implant-associated infection. In our previous study, we demonstrated that the gentamicin-loaded nanotubes could dramatically inhibit bacterial adhesion and biofilm formation on implant surfaces. Considering the overuse of antibiotics may lead to the evolution of antibiotic-resistant bacteria, we synthesized a new quaternized chitosan derivative (hydroxypropyltrimethyl ammonium chloride chitosan, HACC with a 27% degree of substitution (DS; referred to as 27% HACC that had a strong antibacterial activity and simultaneously good biocompatibility with osteogenic cells. Titania nanotubes with various diameters (80, 120, 160, and 200 nm and 200 nm length were loaded with 2 mg of HACC using a lyophilization method and vacuum drying. Two standard strain, methicillin-resistant Staphylococcus aureus (American Type Culture Collection 43300 and Staphylococcus epidermidis (American Type Culture Collection 35984, and two clinical isolates, S. aureus 376 and S. epidermidis 389, were selected to investigate the bacterial adhesion at 6 h and biofilm formation at 24, 48, and 72 h on the HACC-loaded nanotubes (NT-H using the spread plate method, confocal laser scanning microscopy (CLSM, and scanning electron microscopy (SEM. Smooth titanium (Smooth Ti was also investigated and compared. We found that NT-H could significantly inhibit bacterial adhesion and biofilm formation on its surface compared with Smooth Ti, and the NT-H with 160 nm and 200 nm diameters had stronger antibacterial activity because of the extended HACC release time of NT-H with larger diameters. Therefore, NT-H can significantly improve the antibacterial ability of orthopedic implants and provide a promising strategy to prevent implant-associated infections.

  17. Preparation and characterization of porous carbon–titania nanocomposite films as solar selective absorbers

    International Nuclear Information System (INIS)

    Cheng, B.; Wang, K.K.; Wang, K.P.; Li, M.; Jiang, W.; Cong, B.J.; Song, C.L.; Jia, S.H.; Han, G.R.; Liu, Y.

    2015-01-01

    Highlights: • The nanocomposites porous C/TiO 2 film were fabricated via PIPS method. • The HRTEM reveals the size of carbon nanoparticles is about 1.1 nm. • The PVP advantages residual carbon content but suppresses its crystallization. • The film exhibits high α (0.928–0.959) with low ε (0.074–0.105) for single layer. - Abstract: Newly proposed selective solar absorbers of porous carbon–titania nanocomposite films with a well-defined interconnected macropores structure were prepared via a polymer-assisted photopolymerization-induced phase-separation method. The microstructure and optical properties of as-deposited nanocomposite films were characterized and discussed in detail. The results show that non-ionic water-soluble polymer polyvinylpyrrolidone works as a sol modifier advantaging the mean size of the interconnected macropores, residual carbon content, and films thickness, but suppresses the order degree of the carbon remained in the films. The high-resolution transmission electron microscopy demonstrated that a small amount of graphite particles with size of around 1.1 nm embedded in the cavity of the porous while the wall of the porous consists of amorphous carbon and titania composites. The single layer of as-prepared porous C/TiO 2 nanocomposite films exhibits high solar absorptance (α = 0.928–0.959) with low thermal emittance (ε = 0.074–0.105), yielding an optimized photothermal conversion efficiency η = α − ε of 0.864 corresponding to a film thickness of around 338 nm, indication of such film is fair enough to serve as an excellent solar absorber

  18. Comparison of self-cleaning properties of three titania coatings on float glass

    Energy Technology Data Exchange (ETDEWEB)

    Piispanen, Minna, E-mail: minna.piispanen@abo.fi [Abo Akademi University, Process Chemistry Centre, Piispankatu 8, 20500 Turku (Finland); Hupa, Leena, E-mail: leena.hupa@abo.fi [Abo Akademi University, Process Chemistry Centre, Piispankatu 8, 20500 Turku (Finland)

    2011-11-15

    This work compares the self-cleaning properties of experimental TiO{sub 2} and TiO{sub 2}-Ag coatings on float glass with a commercial self-cleaning glass. In the experimental surfaces, TiO{sub 2} coating was applied to float glass via the sol-gel route, while TiO{sub 2}-Ag coating was applied by the liquid flame spray method, which deposits TiO{sub 2}-Ag composite nanoparticles on the surface. The effect of the coatings on the surface wettability and the activation time for achieving hydrophilicity was studied through water contact angle as a function of exposure time to UV light. The surface morphology was investigated by using scanning electron microscopy (SEM) and confocal optical microscopy. The photocatalytic activity of the coatings was examined with methylene blue and stearic acid degradation tests. Finally, the soil attachment to the surfaces was tested with a sebum-based model soil. The sol-gel TiO{sub 2} coating became superhydrophilic within a few hours, while the activation time needed for the commercial titania coated glass was several days. The surface with the TiO{sub 2}-Ag nanoparticles did not show any marked changes in the water contact angle. The commercial titania coated and the sol-gel TiO{sub 2} surfaces showed self-cleaning properties and clearly lower attachment of soil than the uncoated and TiO{sub 2}-Ag coated surfaces. The difference in the interaction of the surfaces with the organic contaminants was assumed to depend mainly on differences in the thickness of the coatings.

  19. Comparison of self-cleaning properties of three titania coatings on float glass

    International Nuclear Information System (INIS)

    Piispanen, Minna; Hupa, Leena

    2011-01-01

    This work compares the self-cleaning properties of experimental TiO 2 and TiO 2 -Ag coatings on float glass with a commercial self-cleaning glass. In the experimental surfaces, TiO 2 coating was applied to float glass via the sol-gel route, while TiO 2 -Ag coating was applied by the liquid flame spray method, which deposits TiO 2 -Ag composite nanoparticles on the surface. The effect of the coatings on the surface wettability and the activation time for achieving hydrophilicity was studied through water contact angle as a function of exposure time to UV light. The surface morphology was investigated by using scanning electron microscopy (SEM) and confocal optical microscopy. The photocatalytic activity of the coatings was examined with methylene blue and stearic acid degradation tests. Finally, the soil attachment to the surfaces was tested with a sebum-based model soil. The sol-gel TiO 2 coating became superhydrophilic within a few hours, while the activation time needed for the commercial titania coated glass was several days. The surface with the TiO 2 -Ag nanoparticles did not show any marked changes in the water contact angle. The commercial titania coated and the sol-gel TiO 2 surfaces showed self-cleaning properties and clearly lower attachment of soil than the uncoated and TiO 2 -Ag coated surfaces. The difference in the interaction of the surfaces with the organic contaminants was assumed to depend mainly on differences in the thickness of the coatings.

  20. Thioglycolic acid (TGA) assisted hydrothermal synthesis of SnS nanorods and nanosheets

    International Nuclear Information System (INIS)

    Biswas, Subhajit; Kar, Soumitra; Chaudhuri, Subhadra

    2007-01-01

    Nanorods and nanosheets of tin sulfide (SnS) were synthesized by a novel thioglycolic acid (TGA) assisted hydrothermal process. The as prepared nanostructures were characterized by X-ray diffraction (XRD) study, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). XRD study reveals the formation of well-crystallized orthorhombic structure of SnS. Diameter of the SnS nanorods varied within 30-100 nm. High-resolution transmission electron microscopy (HRTEM) and selected area electron diffraction (SAED) patterns identify the single crystalline nature for the SnS nanocrystals. The mechanism for the TGA assisted growth for the nanosheets and nanorods have been discussed

  1. Mechanical properties of nanosheets and nanotubes investigated using a new geometry independent volume definition

    International Nuclear Information System (INIS)

    Wagner, Philipp; Ivanovskaya, Viktoria V; Ewels, Christopher P; Rayson, Mark J; Briddon, Patrick R

    2013-01-01

    Cross-sectional area and volume become difficult to define as material dimensions approach the atomic scale. This limits the transferability of macroscopic concepts such as Young’s modulus. We propose a new volume definition where the enclosed nanosheet or nanotube average electron density matches that of the parent layered bulk material. We calculate the Young’s moduli for various nanosheets (including graphene, BN and MoS 2 ) and nanotubes. Further implications of this new volume definition such as a Fermi level dependent Young’s modulus and out-of-plane Poisson’s ratio are shown. (paper)

  2. Peptoid nanosheets as soluble, two-dimensional templates for calcium carbonate mineralization.

    Science.gov (United States)

    Jun, Joo Myung V; Altoe, M Virginia P; Aloni, Shaul; Zuckermann, Ronald N

    2015-06-25

    Nacre-mimetic materials are of great interest, but difficult to synthesize, because they require the ordering of organic and inorganic materials on several length scales. Here we introduce peptoid nanosheets as a versatile two-dimensional platform to develop nacre mimetic materials. Free-floating zwitterionic nanosheets were mineralized with thin films of amorphous calcium carbonate (of 2-20 nm thickness) on their surface to produce planar nacre synthons. These can serve as tunable building blocks to produce layered brick and mortar nanoarchitectures.

  3. High-quality molybdenum disulfide nanosheets with 3D structure for electrochemical sensing

    Energy Technology Data Exchange (ETDEWEB)

    Yin, Aiping, E-mail: aipingyin1964@163.com [Department of chemistry, Xinzhou Teachers University, Xinzhou, Shanxi (China); Wei, Xuehong [College of Chemistry and Chemical Engineering, Shanxi University, Taiyuan, Shanxi (China); Cao, Yexia; Li, Huiqing [Department of chemistry, Xinzhou Teachers University, Xinzhou, Shanxi (China)

    2016-11-01

    Graphical abstract: MoS{sub 2} ultrathin nanosheets are successfully synthesized via a facile strategy, one-step pyrolysis of ammonium molybdate, thiourea and layered g-C{sub 3}N{sub 4} template. Possessing hierarchical porous structure and large pore volume as well as good conductivity, MoS{sub 2} ultrathin nanosheets demonstrates significantly improved electrocatalytic activity toward oxidation of AA, DA, and UA. Display Omitted - Highlights: • MoS{sub 2} ultrathin nanosheets are achieved via a facile strategy, one-step pyrolysis of ammonium molybdate, thiourea and layered g-C{sub 3}N{sub 4} template. • The sacrificial template (g-C{sub 3}N{sub 4}) plays a significant role in this synthetic process, which brings ultrathin structure and three-dimensional porous network for MoS{sub 2} materials. • The MoS{sub 2} ultrathin nanosheets sample displays significantly improved electrocatalytic performance toward oxidation of AA, DA, and UA, manifesting enlarged peak separation and increased peak current. • Meantime, simultaneous determination of these biomolecules is achieved in a wide concentration rang with high sensitivity, selectivity, stability and good reproducibility on modified electrode of the MoS{sub 2} nanosheets. - Abstract: An electrochemical sensor has been developed for simultaneous detection of dopamine (DA), uric acid (UA) and ascorbic acid (AA) based on pure MoS{sub 2} nanosheets modified electrode. The MoS{sub 2} nanosheets are achieved via a facile strategy, one-step pyrolysis of ammonium molybdate, thiourea and layered g-C{sub 3}N{sub 4} template. Possessing hierarchical porous structure and large pore volume as well as good conductivity, MoS{sub 2} nanosheets demonstrates significantly improved electrocatalytic activity toward oxidation of AA, DA, and UA. In the coexisting system, the peak separation of AA–DA, DA–UA and AA–UA is 208.3 mV, 128.0 mV and 336.3 mV, respectively, which is much larger than for other MoS{sub 2}-based catalyst

  4. Click chemistry approach to functionalize two-dimensional macromolecules of graphene oxide nanosheets

    Institute of Scientific and Technical Information of China (English)

    Liang Kou; Hongkun He; Chao Gao

    2010-01-01

    A facile 'click chemistry' approach to functionalize 2D macromolecules of graphene oxide nanosheets with poly(ethylene glycol) of different molecular weights,polystyrene,palmitic acid and various amino acids was presented.FTIR,TGA,Raman spectroscopy,XPS,XRD,TEM,AFM and SEM were utilized to characterize the products.High degree of functionalization was achieved on the flat surfaces of graphene oxide,affording polymer-grafted 2D brushes and amino acids-immobilized nanosheets,which show improved solubility in organic solvents.The click chemistry strategy reported herein provides a facile and general method for functionalization of graphene oxide with macromolecules and desired biomolecules.

  5. Three-dimensional WS2 nanosheet networks for H2O2 produced for cell signaling

    Science.gov (United States)

    Tang, Jing; Quan, Yingzhou; Zhang, Yueyu; Jiang, Min; Al-Enizi, Abdullah M.; Kong, Biao; An, Tiance; Wang, Wenshuo; Xia, Limin; Gong, Xingao; Zheng, Gengfeng

    2016-03-01

    Hydrogen peroxide (H2O2) is an important molecular messenger for cellular signal transduction. The capability of direct probing of H2O2 in complex biological systems can offer potential for elucidating its manifold roles in living systems. Here we report the fabrication of three-dimensional (3D) WS2 nanosheet networks with flower-like morphologies on a variety of conducting substrates. The semiconducting WS2 nanosheets with largely exposed edge sites on flexible carbon fibers enable abundant catalytically active sites, excellent charge transfer, and high permeability to chemicals and biomaterials. Thus, the 3D WS2-based nano-bio-interface exhibits a wide detection range, high sensitivity and rapid response time for H2O2, and is capable of visualizing endogenous H2O2 produced in living RAW 264.7 macrophage cells and neurons. First-principles calculations further demonstrate that the enhanced sensitivity of probing H2O2 is attributed to the efficient and spontaneous H2O2 adsorption on WS2 nanosheet edge sites. The combined features of 3D WS2 nanosheet networks suggest attractive new opportunities for exploring the physiological roles of reactive oxygen species like H2O2 in living systems.Hydrogen peroxide (H2O2) is an important molecular messenger for cellular signal transduction. The capability of direct probing of H2O2 in complex biological systems can offer potential for elucidating its manifold roles in living systems. Here we report the fabrication of three-dimensional (3D) WS2 nanosheet networks with flower-like morphologies on a variety of conducting substrates. The semiconducting WS2 nanosheets with largely exposed edge sites on flexible carbon fibers enable abundant catalytically active sites, excellent charge transfer, and high permeability to chemicals and biomaterials. Thus, the 3D WS2-based nano-bio-interface exhibits a wide detection range, high sensitivity and rapid response time for H2O2, and is capable of visualizing endogenous H2O2 produced in

  6. Thiol-modified MoS2 nanosheets as a functional layer for electrical bistable devices

    Science.gov (United States)

    Li, Guan; Tan, Fenxue; Lv, Bokun; Wu, Mengying; Wang, Ruiqi; Lu, Yue; Li, Xu; Li, Zhiqiang; Teng, Feng

    2018-01-01

    Molybdenum disulfide nanosheets have been synthesized by one-pot method using 1-ODT as sulfur source and surfactant. The structure, morphology and optical properties of samples were investigated by XRD, FTIR, Abs spectrum and TEM patterns. The XRD pattern indicated that the as-obtained MoS2 belong to hexagonal system. The as-obtained MoS2 nanosheets blending with PVK could be used to fabricate an electrically bistable devices through a simple spin-coating method and the device exhibited an obvious electrical bistability properties. The charge transport mechanism of the device was discussed based on the filamentary switching models.

  7. Effect of Mn doped-titania on the activity of metallocene catalyst by in situ ethylene polymerization

    KAUST Repository

    Abdul Kaleel, S. H.

    2012-09-01

    Ethylene polymerization was carried out using highly active metallocene catalysts (Cp 2ZrCl 2 and Cp 2TiCl 2) in combination with methylalumoxane. Titanium(IV) oxide containing 1% Mn as dopant was used as nanofillers. The influence of filler concentration, reaction temperature and pressure on the catalytic activity and polymer properties was investigated. There was a fourfold increase in the activity of zirconocene catalyst by addition of doped-titania. The morphology indicates that the doped-titania nanoparticles have a nucleus effect on the polymerization and caused a homogeneous PE shell around them. The optimum condition for polymerization was found to be 30°C. © 2012 The Korean Society of Industrial and Engineering Chemistry.

  8. Hierarchically porous CoFe2O4 nanosheets supported on Ni foam with excellent electrochemical properties for asymmetric supercapacitors

    Science.gov (United States)

    Gao, Hongyan; Xiang, Junjie; Cao, Yan

    2017-08-01

    A new type of hierarchically mesoporous cobalt ferrite oxide nanosheets, CoFe2O4 nanosheets, has been successfully fabricated via a simple hydrothermal method on the Ni foam followed by a post-annealing treatment. This CoFe2O4 nanosheets was employed as a supercapacitor electrode and exhibited an excellent capacitance of 503 F g-1 at a current density of 2 A g-1. When the current density increased to 20 A g-1, the capacitance of CoFe2O4 nanosheets can maintain 78.5% (395 F g-1) of the initial value, indicating the remarkable rate capability of the as-prepared CoFe2O4 nanosheets. An aqueous asymmetric supercapacitor (ASC) based on CoFe2O4 nanosheets as a positive electrode and the activated carbon (AC) as a negative electrode was assembled for the first time. The as-fabricated ASC delivered a specific capacitance of 73.12 F g-1 at a current density of 1.2 A g-1 in a voltage window of 1.5 V. The CoFe2O4//AC ASC could achieve a high energy density of 22.85 W h kg-1 and good long-term cycling stability (98% retention after 5000 cycles). These results demonstrated that CoFe2O4 nanosheets could be one of the promising electrode material for supercapacitors applications.

  9. Visible-light photocatalytic activity of Ag2O coated Bi2WO6 hierarchical microspheres assembled by nanosheets

    International Nuclear Information System (INIS)

    Chen, Lin; Hua, Hao; Yang, Qi; Hu, Chenguo

    2015-01-01

    Graphical abstract: - Highlights: • Bi 2 WO 6 hierarchical microspheres assembled by nanosheets and dispersed nanosheets are synthesized. • Ag 2 O/Bi 2 WO 6 heterostuctures exhibites an enhanced photocatalytic activity compared with the Bi 2 WO 6 nanostructures. • Photocatalytic activity of the Ag 2 O/Bi 2 WO 6 microspheres is higher than that of the nanosheets. • Bi 2 WO 6 hierarchical structure is an excellent architecture for loading of Ag 2 O nanoparticles. - Abstract: Bi 2 WO 6 hierarchical microspheres assembled by nanosheets and dispersed nanosheets were synthesized by hydrothermal reaction in different conditions. Ag 2 O nanoparticles were deposited on the surface of Bi 2 WO 6 microspheres and nanosheets by the chemical precipitation method. The photocatalytic performance of pure Bi 2 WO 6 nanostructures and Ag 2 O/Bi 2 WO 6 heterostructures were evaluated by the photocatalytic decolorization of RhB solution under visible-light irradiation. Compared with the pure Bi 2 WO 6 nanostructures, the Ag 2 O/Bi 2 WO 6 heterostructures exhibited an obviously enhanced photocatalytic activity. And photocatalytic activity of the Ag 2 O/Bi 2 WO 6 microspheres is higher than that of the Ag 2 O/Bi 2 WO 6 nanosheets. This work demonstrates that the Bi 2 WO 6 hierarchical three-dimensional structure is an excellent architecture for the loading of Ag 2 O nanoparticles to build a highly efficient photocatalyst

  10. Controlling drug delivery kinetics from mesoporous titania thin films by pore size and surface energy

    Directory of Open Access Journals (Sweden)

    Karlsson J

    2015-07-01

    Full Text Available Johan Karlsson, Saba Atefyekta, Martin Andersson Department of Chemical and Biological Engineering, Chalmers University of Technology, Gothenburg, Sweden Abstract: The osseointegration capacity of bone-anchoring implants can be improved by the use of drugs that are administrated by an inbuilt drug delivery system. However, to attain superior control of drug delivery and to have the ability to administer drugs of varying size, including proteins, further material development of drug carriers is needed. Mesoporous materials have shown great potential in drug delivery applications to provide and maintain a drug concentration within the therapeutic window for the desired period of time. Moreover, drug delivery from coatings consisting of mesoporous titania has shown to be promising to improve healing of bone-anchoring implants. Here we report on how the delivery of an osteoporosis drug, alendronate, can be controlled by altering pore size and surface energy of mesoporous titania thin films. The pore size was varied from 3.4 nm to 7.2 nm by the use of different structure-directing templates and addition of a swelling agent. The surface energy was also altered by grafting dimethylsilane to the pore walls. The drug uptake and release profiles were monitored in situ using quartz crystal microbalance with dissipation (QCM-D and it was shown that both pore size and surface energy had a profound effect on both the adsorption and release kinetics of alendronate. The QCM-D data provided evidence that the drug delivery from mesoporous titania films is controlled by a binding–diffusion mechanism. The yielded knowledge of release kinetics is crucial in order to improve the in vivo tissue response associated to therapeutic treatments. Keywords: mesoporous titania, controlled drug delivery, release kinetics, alendronate, QCM-D

  11. Sandwich-like singled-walled titania nanotube as a novel semiconductor electrode for quantum dot-sensitized solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Dong, Cunku; Li, Xin; Fan, Xiujuan [Department of Chemistry, Harbin Institute of Technology, Harbin 150090 (China); Qi, Jingyao [School of Municipal and Environmental Engineering, Harbin Institute of Technology, Harbin 150090 (China)

    2012-06-15

    A novel sandwich-like singled-walled titania nanotube is designed as a photoanode in quantum dot-sensitized solar cells. It acts as a hollow coaxial nanocable, in which the injected electron is confined in the conducting layer for transport, guarded from electron recombination by the protective layers. An ultrafast interfacial electron transfer is also expected in this photoelectric system due to the unique nanoarchitecture. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  12. Refining waste hardmetals into tungsten oxide nanosheets via facile method

    Energy Technology Data Exchange (ETDEWEB)

    Li, Zhifei; Zheng, Guangwei; Wang, Jinshu, E-mail: wangjsh@bjut.edu.cn; Li, Hongyi, E-mail: lhy06@bjut.edu.cn; Wu, Junshu; Du, Yucheng [Beijing University of Technology, Key Laboratory of Advanced Functional Materials, School of Materials Science and Engineering (China)

    2016-04-15

    A new hydrothermal system has been designed to recycle waste WC–Co hardmetal with low cobalt (Co) content (3 %). In the solution system, nitric acid was designed to dissolve Co, H{sub 2}O{sub 2} served as oxidant to accelerate the oxidation of the WC–Co hardmetals, and fluorine (F{sup −}) was designed to dissolve and recrystallize generated tungsten oxides, which were found to possess a layered structure using scanning electron microscopy and transmission electron microscopy. The obtained tungsten oxides were identified as WO{sub 3}·0.33H{sub 2}O by X-ray diffraction and their specific surface area was measured as 89.2 m{sup 2} g{sup −1} via N{sub 2} adsorption–desorption techniques. The present layered structure tungsten oxides exhibited a promising capability for removing lead ion (Pb{sup 2+}) and organic species, such as methyl blue. The adsorption model was found to be in agreement with Langmuir isotherm model. Given the facile synthesis procedure and promising properties of final products, this new approach should have great potential for refining some other waste hardmetals or tungsten products.Graphical AbstractA new hydrothermal system was designed to recycle waste hardmetal with low cobalt content. Through this method, waste hardmetal was refined into WO{sub 3}·0.33H{sub 2}O nanosheets which shows excellent adsorption capacities toward methylene blue and lead ion (Pb{sup 2+}).

  13. Microwave assisted rapid growth of Mg(OH){sub 2} nanosheet networks for ethanol chemical sensor application

    Energy Technology Data Exchange (ETDEWEB)

    Al-Hazmi, Faten [Department of Physics, College of Science, King Abdulaziz University, P.O. Box 80203, Jeddah 21569 (Saudi Arabia); Umar, Ahmad, E-mail: ahmadumar786@gmail.com [Promising Centre for Sensors and Electronic Devices (PCSED) and Centre for Advanced Materials and Nano-Research (CAMNR), Najran University, P.O. Box 1988, Najran 11001 (Saudi Arabia); Dar, G.N. [Promising Centre for Sensors and Electronic Devices (PCSED) and Centre for Advanced Materials and Nano-Research (CAMNR), Najran University, P.O. Box 1988, Najran 11001 (Saudi Arabia); Al-Ghamdi, A.A.; Al-Sayari, S.A. [Department of Physics, College of Science, King Abdulaziz University, P.O. Box 80203, Jeddah 21569 (Saudi Arabia); Al-Hajry, A. [Promising Centre for Sensors and Electronic Devices (PCSED) and Centre for Advanced Materials and Nano-Research (CAMNR), Najran University, P.O. Box 1988, Najran 11001 (Saudi Arabia); Department of Physics, College of Science and Arts, Najran University, P.O. Box 1988, Najran 11001 (Saudi Arabia); Kim, S.H. [Promising Centre for Sensors and Electronic Devices (PCSED) and Centre for Advanced Materials and Nano-Research (CAMNR), Najran University, P.O. Box 1988, Najran 11001 (Saudi Arabia); Al-Tuwirqi, Reem M. [Department of Physics, College of Science, King Abdulaziz University, P.O. Box 80203, Jeddah 21569 (Saudi Arabia); Alnowaiserb, Fowzia [Department of Chemistry, Faculty of Science, King Abdulaziz University, Jeddah (Saudi Arabia); El-Tantawy, Farid [Department of Physics, Faculty of Science, Suez Canal University, Ismailia (Egypt)

    2012-04-05

    Highlights: Black-Right-Pointing-Pointer A facile microwave-assisted synthesis and characterizations of magnesium hydroxide (Mg(OH){sub 2}) nanosheet networks. Black-Right-Pointing-Pointer Fabrication of ethanol sensor based on (Mg(OH){sub 2}) nanosheet networks. Black-Right-Pointing-Pointer Good sensitivity ({approx}3.991 {mu}A cm{sup -2} mM{sup -1}) and lower detection limit (5 {mu}M). Black-Right-Pointing-Pointer This research opens a way to utilize Mg(OH){sub 2} nanostructures for chemical sensors applications. - Abstract: This paper reports a facile microwave-assisted synthesis of magnesium hydroxide (Mg(OH){sub 2}) nanosheet networks and their utilization for the fabrication of efficient ethanol chemical sensor. The synthesized nanosheets networks were characterized in terms of their morphological, structural and optical properties using various analysis techniques such as field emission scanning electron microscopy (FESEM), X-ray diffraction pattern (XRD), Fourier transform infrared (FTIR) and UV-Vis spectroscopy. The detailed morphological and structural investigations reveal that the synthesized (Mg(OH){sub 2}) products are nanosheet networks, grown in high density, and possessing hexagonal crystal structure. The optical band gap of as-synthesized Mg(OH){sub 2} nanosheet networks was examined by UV-Vis absorption spectrum, and found to be 5.76 eV. The synthesized nanosheet networks were used as supporting matrices for the fabrication of I-V technique based efficient ethanol chemical sensor. The fabricated ethanol sensor based on nanosheet networks exhibits good sensitivity ({approx}3.991 {mu}A cm{sup -2} mM{sup -1}) and lower detection limit (5 {mu}M), with linearity (R = 0.9925) in short response time (10.0 s). This work demonstrate that the simply synthesized Mg(OH){sub 2} nanosheet networks can effectively be used for the fabrication of efficient ethanol chemical sensors.

  14. Role of boundary layer diffusion in vapor deposition growth of chalcogenide nanosheets: the case of GeS.

    Science.gov (United States)

    Li, Chun; Huang, Liang; Snigdha, Gayatri Pongur; Yu, Yifei; Cao, Linyou

    2012-10-23

    We report a synthesis of single-crystalline two-dimensional GeS nanosheets using vapor deposition processes and show that the growth behavior of the nanosheet is substantially different from those of other nanomaterials and thin films grown by vapor depositions. The nanosheet growth is subject to strong influences of the diffusion of source materials through the boundary layer of gas flows. This boundary layer diffusion is found to be the rate-determining step of the growth under typical experimental conditions, evidenced by a substantial dependence of the nanosheet's size on diffusion fluxes. We also find that high-quality GeS nanosheets can grow only in the diffusion-limited regime, as the crystalline quality substantially deteriorates when the rate-determining step is changed away from the boundary layer diffusion. We establish a simple model to analyze the diffusion dynamics in experiments. Our analysis uncovers an intuitive correlation of diffusion flux with the partial pressure of source materials, the flow rate of carrier gas, and the total pressure in the synthetic setup. The observed significant role of boundary layer diffusions in the growth is unique for nanosheets. It may be correlated with the high growth rate of GeS nanosheets, ~3-5 μm/min, which is 1 order of magnitude higher than other nanomaterials (such as nanowires) and thin films. This fundamental understanding of the effect of boundary layer diffusions may generally apply to other chalcogenide nanosheets that can grow rapidly. It can provide useful guidance for the development of general paradigms to control the synthesis of nanosheets.

  15. Preparation and properties of titania based ionogels synthesized using ionic liquid 1-ethyl-3-methyl imidazolium thiocyanate

    Energy Technology Data Exchange (ETDEWEB)

    Verma, Y.L.; Tripathi, A.K.; Shalu; Singh, V.K.; Balo, L.; Gupta, H.; Singh, S.K.; Singh, R.K., E-mail: rajendrasingh.bhu@gmail.com

    2017-06-15

    Highlights: • Synthesis of titania based ionogels using non-aqueous sol-gel process. • Ionogels are found to be mesoporous structure with uniform pore size distribution. • Ionic liquid extracted TiO{sub 2} matrix reveals the anatase phase of TiO{sub 2}. • Properties of ionic liquid are found to change in TiO{sub 2} matrix. - Abstract: Present study reports the synthesis of titania (TiO{sub 2}) based ionogels using ionic liquid (IL) 1-ethyl-3-methyl imidazolium thiocyanate ([EMIM][SCN]) by non-aqueous sol-gel process. Ionogels are characterized using N{sub 2} adsorption-desorption, TGA, DSC, SEM, TEM, XRD, and FTIR. N{sub 2}-sorption results show that TiO{sub 2} matrices have meso-pores with uniform pore size distribution. Thermal studies reveal that thermal stability of confined IL decreases while the glass transition temperature (T{sub g}) is found to increase. XRD patterns show that IL containing TiO{sub 2} matrices exhibit amorphous (weak crystalline peaks) nature however after extraction of IL from ionogel, it shows the crystalline (anatase) phase of TiO{sub 2} which has also been found from SAED pattern. SEM micrographs reveal that as the amount of IL is increased, TiO{sub 2} particles are found to agglomerate. FTIR results indicate that the vibrational frequencies of confined IL are found to shift due to interaction of IL molecules with titania pore wall surface.

  16. Improving the photovoltaic parameters in Quantum dot sensitized solar cells through employment of chemically deposited compact titania blocking layer

    Energy Technology Data Exchange (ETDEWEB)

    Rajendra Prasad, M.B., E-mail: rajendraprasadmb75@gmail.com [Advanced Physics Laboratory, Department of Physics, SavitibaiPhule Pune University, Pune, 411007 (India); National Defence Academy, Khadakwasla, Pune, 411023 (India); Kadam, Vishal [Advanced Physics Laboratory, Department of Physics, SavitibaiPhule Pune University, Pune, 411007 (India); Joo, Oh-Shim [Korea Institute of Science and Technology, PO Box No. 131, Chongryang, Seoul, 130-650 (Korea, Republic of); Pathan, Habib M. [Advanced Physics Laboratory, Department of Physics, SavitibaiPhule Pune University, Pune, 411007 (India)

    2017-06-15

    Incorporation of compact blocking layer at the Transparent Conducting Oxide (TCO)/Electrolyte interface is an effective method to improve the device performance in QDSSC through mitigation of electron recombinations at this interface. This paper reports the most facile and cost effective method of depositing a rutile titania Compact Layer (CL) over Fluorine doped Tin Oxide (FTO) substrate and its application in titania based CdS QD sensitized solar cells. The deposited compact layers are characterized to study their structural, optical, morphological and electrochemical properties using X-Ray Diffractometry, UV–Visible spectroscopy, Scanning electron microscopy, Cyclic Voltammetry and Contact Angle measurements. Sandwich solar cells are fabricated using these CL based electrodes and characterized using Electrochemical Impedance Spectroscopy, Open Circuit Voltage Decay and J-V characteristics. The CL incorporated CdS QDSSC showed more than 100% increase in the photoconversion efficiency (1.68%) as compared to its bare FTO counterpart (0.73%) proving the efficacy of employed strategy. - Highlights: • Deposited titania compact layer by a facile room temperature chemical bath method. • Employed this to mitigate back electron transfer at TCO/Electrolyte interface. • Compact layer incorporation has improved the solar cell performance by 130%.

  17. An Enthusiastic Glance in to the Visible Responsive Photocatalysts for Energy Production and Pollutant Removal, with Special Emphasis on Titania

    Directory of Open Access Journals (Sweden)

    Padikkaparambil Silija

    2012-01-01

    Full Text Available As a consequence of the rapid growth of industry, major problems are created related to energy and environment. Sunlight being one of the most potential alternative source of energy, the development of efficient solar-energy storage systems is an important subject in the fields of science and technology. Here we have reviewed and summarized some of the recent reports on visible responsive photocatalysts. In this review, the influence of various metal oxide photocatalysts on energy production and pollutant removal are presented with special emphasis on titania based photocatalysts. The photoactivity of titania for various pollutant degradation, modified titania (TiO2 systems, their physical and chemical characteristics, and so forth, are described in detail at this juncture. Different methods used to enhance the visible light absorption of TiO2, like doping with metals and nonmetals, coupling with other metal oxides, and so forth, have been discussed. Various applications of photocatalysts including photocatalytic treatment of waste water, pesticide degradation and water splitting to produce hydrogen are summarized. The development of photocatalysts that function under visible light for the efficient utilization of sunlight is an area of current interest and thus the different methods of preparation for the visible active photocatalysts are also explored.

  18. Photocatalytic Activity and Characterization of Carbon-Modified Titania for Visible-Light-Active Photodegradation of Nitrogen Oxides

    Directory of Open Access Journals (Sweden)

    Chun-Hung Huang

    2012-01-01

    Full Text Available A variety of carbon-modified titania powders were prepared by impregnation method using a commercial available titania powder, Hombikat UV100, as matrix material while a range of alcohols from propanol to hexanol were used as precursors of carbon sources. Rising the carbon number of alcoholic precursor molecule, the modified titania showed increasing visible activities of NOx photodegradation. The catalyst modified with cyclohexanol exhibited the best activities of 62%, 62%, 59%, and 54% for the total NOx removal under UV, blue, green, and red light irradiation, respectively. The high activity with long wavelength irradiation suggested a good capability of photocatalysis in full visible light spectrum. Analysis of UV-visible spectrum indicated that carbon modification promoted visible light absorption and red shift in band gap. XPS spectroscopic analysis identified the existence of carbonate species (C=O, which increased with the increasing carbon number of precursor molecule. Photoluminescence spectra demonstrated that the carbonate species suppressed the recombination rate of electron-hole pair. As a result, a mechanism of visible-light-active photocatalyst was proposed according to the formation of carbonate species on carbon-modified TiO2.

  19. Electrostatic Self-Assembly Enabling Integrated Bulk and Interfacial Sodium Storage in 3D Titania-Graphene Hybrid

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Gui-Liang [Chemical; Xiao, Lisong [Center; Sheng, Tian [Collaborative; Liu, Jianzhao [Chemical; Hu, Yi-Xin [Chemical; Department; Ma, Tianyuan [Chemical; Amine, Rachid [Materials; Xie, Yingying [Chemical; Zhang, Xiaoyi [X-ray Science; Liu, Yuzi [Nanoscience; Ren, Yang [X-ray Science; Sun, Cheng-Jun [X-ray Science; Heald, Steve M. [X-ray Science; Kovacevic, Jasmina [Center; Sehlleier, Yee Hwa [Center; Schulz, Christof [Center; Mattis, Wenjuan Liu [Microvast Power Solutions, 12603; Sun, Shi-Gang [Collaborative; Wiggers, Hartmut [Center; Chen, Zonghai [Chemical; Amine, Khalil [Chemical

    2017-12-15

    Room temperature sodium-ion batteries have attracted increased attention for energy storage due to the natural abundance of sodium. However, it remains a huge challenge to develop versatile electrode materials with favorable properties, which requires smart structure design and good mechanistic understanding. Herein, we reported a general and scalable approach to synthesize 3D titania-graphene hybrid via electrostatic-interaction-induced self-assembly. Synchrotron X-ray probe, transmission electron microscopy and computational modeling revealed that the strong interaction between Titania and graphene through comparably strong van-der-Waals forces not only facilitates bulk Na+ intercalation but also enhances the interfacial sodium storage. As a result, the titania-graphene hybrid exhibits exceptional long-term cycle stability up to 5000 cycles, and ultrahigh rate capability up to 20 C for sodium storage. Furthermore, density function theory calculation indicated that the interfacial Li+, K+, Mg2+ and Al3+ storage can be enhanced as well. The proposed general strategy opens up new avenues to create versatile materials for advanced battery systems.

  20. Electrostatic Self-Assembly Enabling Integrated Bulk and Interfacial Sodium Storage in 3D Titania-Graphene Hybrid.

    Science.gov (United States)

    Xu, Gui-Liang; Xiao, Lisong; Sheng, Tian; Liu, Jianzhao; Hu, Yi-Xin; Ma, Tianyuan; Amine, Rachid; Xie, Yingying; Zhang, Xiaoyi; Liu, Yuzi; Ren, Yang; Sun, Cheng-Jun; Heald, Steve M; Kovacevic, Jasmina; Sehlleier, Yee Hwa; Schulz, Christof; Mattis, Wenjuan Liu; Sun, Shi-Gang; Wiggers, Hartmut; Chen, Zonghai; Amine, Khalil

    2018-01-10

    Room-temperature sodium-ion batteries have attracted increased attention for energy storage due to the natural abundance of sodium. However, it remains a huge challenge to develop versatile electrode materials with favorable properties, which requires smart structure design and good mechanistic understanding. Herein, we reported a general and scalable approach to synthesize three-dimensional (3D) titania-graphene hybrid via electrostatic-interaction-induced self-assembly. Synchrotron X-ray probe, transmission electron microscopy, and computational modeling revealed that the strong interaction between titania and graphene through comparably strong van der Waals forces not only facilitates bulk Na + intercalation but also enhances the interfacial sodium storage. As a result, the titania-graphene hybrid exhibits exceptional long-term cycle stability up to 5000 cycles, and ultrahigh rate capability up to 20 C for sodium storage. Furthermore, density function theory calculation indicated that the interfacial Li + , K + , Mg 2+, and Al 3+ storage can be enhanced as well. The proposed general strategy opens up new avenues to create versatile materials for advanced battery systems.

  1. Sol-gel titania-coated needles for solid phase dynamic extraction-GC/MS analysis of desomorphine and desocodeine.

    Science.gov (United States)

    Su, Chi-Ju; Srimurugan, Sankarewaran; Chen, Chinpiao; Shu, Hun-Chi

    2011-01-01

    Novel sol-gel titania film coated needles for solid-phase dynamic extraction (SPDE)-GC/MS analysis of desomorphine and desocodeine are described. The high thermal stability of titania film permits efficient extraction and analysis of poorly volatile opiate drugs. The influences of sol-gel reaction time, coating layer, extraction and desorption time and temperature on the SPDE needle performance were investigated. The deuterium labeled internal standard was introduced either during the extraction of analyte or directly injected to GC after the extraction process. The latter method was shown to be more sensitive for the analysis of water and urine samples containing opiate drugs. The proposed conditions provided a wide linear range (from 5-5000 ppb), and satisfactory linearity, with R(2) values from 0.9958 to 0.9999, and prominent sensitivity, LOQs (1.0-5.0 ng/g). The sol-gel titania film coated needle with SPDE-GC/MS will be a promising technique for desomorphine and desocodeine analysis in urine.

  2. Au-coated 3-D nanoporous titania layer prepared using polystyrene-b-poly(2-vinylpyridine) block copolymer nanoparticles.

    Science.gov (United States)

    Shin, Won-Jeong; Basarir, Fevzihan; Yoon, Tae-Ho; Lee, Jae-Suk

    2009-04-09

    New nanoporous structures of Au-coated titania layers were prepared by using amphiphilic block copolymer nanoparticles as a template. A 3-D template composed of self-assembled quaternized polystyrene-b-poly(2-vinylpyridine) (Q-PS-b-P2VP) block copolymer nanoparticles below 100 nm was prepared. The core-shell-type nanoparticles were well ordered three-dimensionally using the vertical immersion method on the substrate. The polar solvents were added to the polymer solution to prevent particle merging at 40 degrees C when considering the interaction between polymer nanoparticles and solvents. Furthermore, Au-coated PS-b-P2VP nanoparticles were prepared using thiol-capped Au nanoparticles (3 nm). The 3-D arrays with Au-coated PS-b-P2VP nanoparticles as a template contributed to the preparation of the nanoporous Au-coated titania layer. Therefore, the nanoporous Au-coated titania layer was fabricated by removing PS-b-P2VP block copolymer nanoparticles by oxygen plasma etching.

  3. A simple way to prepare reduced graphene oxide nanosheets/Fe2O3-Pd/N-doped carbon nanosheets and their application in catalysis.

    Science.gov (United States)

    Yao, Tongjie; Zhang, Junshuai; Zuo, Quan; Wang, Hao; Wu, Jie; Zhang, Xiao; Cui, Tieyu

    2016-04-15

    The catalysts with Pd and γ-Fe2O3 nanoparticles embedded between reduced graphene oxide nanosheets (rGS) and N-doped carbon nanosheets (NCS) were prepared through a two-step method. Firstly, graphene oxide nanosheets (GS)/prussian blue (PB)-Pd/polypyrrole (PPy) composites were synthesized by using pyrrole monomer as reductant, K3Fe(CN)6 and PdCl2 as oxidants in the presence of GS via a redox reaction. Subsequently, the as-obtained GS/PB-Pd/PPy composites were calcinated in N2 atmosphere. During the heat-treatment, carbonization of PPy to NCS, conversion of nonmagnetic PB to magnetic γ-Fe2O3 nanoparticles, and reduction of GS to rGS were finished, simultaneously. rGS/Fe2O3-Pd/NCS composites exhibited good catalytic activity toward reduction of 4-nitrophenol. The rate constant k and turnover frequency were calculated and compared with recent reports. Owing to γ-Fe2O3 nanoparticles, the rGS/Fe2O3-Pd/NCS composites could be quickly separated by magnet and reused without obvious decrease in activity. Copyright © 2016 Elsevier Inc. All rights reserved.

  4. Metal-Organic Framework Nanosheets for Fast-Response and Highly Sensitive Luminescent Sensing of Fe3+

    DEFF Research Database (Denmark)

    Xu, Hui; Iversen, Bo Brummerstedt

    of graphene, Since the discovery of graphene, series of two-dimensional (2-D) nanosheets materials such as metal oxides, metal hydroxides, transition metal chalcogenides (TMDs), boron nitride (BN) and black phosphorus have been of great interests, and have been extensively investigated for applications...... in electronics, lithium-ion batteries, catalysis and mechanical properties, etc. 2-D MOF nanosheets materials, as a new member of the 2-D nanomaterials family, are still at the very early stage. However, to the best of our knowledge, the 2-D MOF nanosheets materials for luminescent sensing have been rarely...

  5. Adsorption behavior of NH3 and NO2 molecules on stanene and stanane nanosheets - A density functional theory study

    Science.gov (United States)

    Nagarajan, V.; Chandiramouli, R.

    2018-03-01

    Using density functional theory method, we investigate the adsorption properties of NH3 and NO2 molecules on stanene and stanane nanosheets. The adsorption of molecules is explored based on the charge transfer, energetics, energy band gap and average energy gap variation. Moreover, the optimal adsorption sites of NH3 and NO2 molecules are identified on stanene and stanane nanosheets. Besides, the state-of-the-art provides the key features for the development of chemi-resistive nanosensor based on stanene and stanane nanosheets upon adsorption of NH3 and NO2 molecules. Furthermore, the study shows that adsorption of NO2 molecules is more prominent rather than NH3 molecules.

  6. Hydrophilic MoSe2 Nanosheets as Effective Photothermal Therapy Agents and Their Application in Smart Devices.

    Science.gov (United States)

    Lei, Zhouyue; Zhu, Wencheng; Xu, Shengjie; Ding, Jian; Wan, Jiaxun; Wu, Peiyi

    2016-08-17

    A facile poly(vinylpyrrolidone) (PVP)-assisted exfoliation method is utilized to simultaneously exfoliate and noncovalently modify MoSe2 nanosheets. The resultant hydrophilic nanosheets are shown to be promising candidates for biocompatible photothermal therapy (PTT) agents, and they could also be encapsulated into a hydrogel matrix for some intelligent devices. This work not only provides novel insights into exfoliation and modification of transition metal dichalcogenide (TMD) nanosheets but also might spark more research into engineering multifunctional TMD-related nanocomposites, which is in favor of further exploiting the attractive properties of these emerging layered two-dimensional (2D) nanomaterials.

  7. SnO2 nanosheets grown on graphene sheets with enhanced lithium storage properties.

    Science.gov (United States)

    Ding, Shujiang; Luan, Deyan; Boey, Freddy Yin Chiang; Chen, Jun Song; Lou, Xiong Wen David

    2011-07-07

    We demonstrate a new hydrothermal method to directly grow SnO(2) nanosheets on a graphene oxide support that is subsequently reduced to graphene. This unique SnO(2)/graphene hybrid structure exhibits enhanced lithium storage properties with high reversible capacities and good cycling performance. This journal is © The Royal Society of Chemistry 2011

  8. Novel carbon nanosheets as support for ultrahigh-resolution structural analysis of nanoparticles

    International Nuclear Information System (INIS)

    Nottbohm, Christoph T.; Beyer, Andre; Sologubenko, Alla S.; Ennen, Inga; Huetten, Andreas; Roesner, Harald; Eck, Wolfgang; Mayer, Joachim; Goelzhaeuser, Armin

    2008-01-01

    The resolution in transmission electron microscopy (TEM) has reached values as low as 0.08 nm. However, these values are not accessible for very small objects in the size range of a few nanometers or lower, as they have to be placed on some support, which contributes to the overall electron-scattering signal, thereby blurring the contrast. Here, we report on the use of nanosheets made from cross-linked aromatic self-assembled monolayers as TEM sample supports. When transferred onto a copper grid, a single 1.6-nm-thick nanosheet can cover the grid and is free standing within the micron-sized openings. Despite its thinness, the sheet is stable under the impact of the electron beam. Micrographs taken from nanoclusters onto these nanosheets show highly increased contrast in comparison to the images taken from amorphous carbon supports. In scanning transmission electron microscopy with nanosheet support, a size analysis of sub-nanometer Au clusters was performed and single Au atoms were resolved

  9. Effects of surface passivation on twin-free GaAs nanosheets.

    Science.gov (United States)

    Arab, Shermin; Chi, Chun-Yung; Shi, Teng; Wang, Yuda; Dapkus, Daniel P; Jackson, Howard E; Smith, Leigh M; Cronin, Stephen B

    2015-02-24

    Unlike nanowires, GaAs nanosheets exhibit no twin defects, stacking faults, or dislocations even when grown on lattice mismatched substrates. As such, they are excellent candidates for optoelectronic applications, including LEDs and solar cells. We report substantial enhancements in the photoluminescence efficiency and the lifetime of passivated GaAs nanosheets produced using the selected area growth (SAG) method with metal organic chemical vapor deposition (MOCVD). Measurements are performed on individual GaAs nanosheets with and without an AlGaAs passivation layer. Both steady-state photoluminescence and time-resolved photoluminescence spectroscopy are performed to study the optoelectronic performance of these nanostructures. Our results show that AlGaAs passivation of GaAs nanosheets leads to a 30- to 40-fold enhancement in the photoluminescence intensity. The photoluminescence lifetime increases from less than 30 to 300 ps with passivation, indicating an order of magnitude improvement in the minority carrier lifetime. We attribute these enhancements to the reduction of nonradiative recombination due to the compensation of surface states after passivation. The surface recombination velocity decreases from an initial value of 2.5 × 10(5) to 2.7 × 10(4) cm/s with passivation.

  10. Oxygen vacancy effect on photoluminescence of KNb3O8 nanosheets

    Science.gov (United States)

    Li, Rui; Liu, Liying; Ming, Bangming; Ji, Yuhang; Wang, Ruzhi

    2018-05-01

    Fungus-like potassium niobate (KNb3O8) nanosheets have been synthesized on indium-doped tin oxide (ITO) glass substrates by a simple and environmental friendly two-step hydrothermal process. The prepared samples have been characterized by using X-ray Diffraction (XRD), Field Emission Scanning Electron Microscope (FESEM), High Resolution Transmission Electron Microscope (HRTEM), Fourier Transform Infra-Red Spectroscopy (FTIR), Raman Spectroscopy and X-ray Photoelectron Spectroscopy (XPS). Furthermore, the photoluminescence (PL) of KNb3O8 nanosheets have been systematically studied. The results showed that the PL spectrum is between 300 and 645 nm with a 325 nm light excitation, which is divided into some sub-peaks. It is different from the perfect KNb3O8 nanosheets whose PL emission peaks located at near 433 nm. It should be originated from the effect of the oxygen (O) vacancies in the KNb3O8 nanosheets, which the PLs peaks can be found at about 490 nm and 530 nm by different position of O vacancy. The experimental results are in accordance with the first-principles calculations. Our results may present a feasible clue to estimate the defect position in KNb3O8 by the shape analysis of its spectrum of PLs.

  11. Metal–semiconductor transition in atomically thin Bi2Sr2Co2O8 nanosheets

    Directory of Open Access Journals (Sweden)

    Yang Wang

    2014-09-01

    Full Text Available Two-dimensional layered materials have attracted considerable attention since the discovery of graphene. Here we demonstrate that the layered Bi2Sr2Co2O8 (BSCO can be mechanically exfoliated into single- or few-layer nanosheets. The BSCO nanosheets with four or more layers display bulk metallic characteristics, while the nanosheets with three or fewer layers have a layer-number-dependent semiconducting characteristics. Charge transport in bilayer or trilayer BSCO nanosheets exhibits Mott 2D variable-range-hopping (VRH conduction throughout 2 K–300 K, while the charge transport in monolayers follows the Mott-VRH law above a crossover temperature of 75 K, and is governed by Efros and Shklovskii-VRH laws below 75 K. Disorder potentials and Coulomb charging both contribute to the transport gap of these nanodevices. Our study reveals a distinct layer number-dependent metal-to-semiconductor transition in a new class of 2D materials, and is of great significance for both fundamental investigations and practical devices.

  12. The facile synthesis of hierarchical NiCoO2 nanotubes comprised ultrathin nanosheets for supercapacitors

    Science.gov (United States)

    Xu, Xin; Zhou, Han; Ding, Shujiang; Li, Jun; Li, Beibei; Yu, Demei

    2014-12-01

    Hierarchical NiCoO2 nanosheets nanotubes are successfully prepared by a mild solution method based on the template of polymeric nanotubes (PNT) followed by a thermal annealing treatment. The microstructure and chemical composition of NiCoO2 nanosheets nanotubes are characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), Brunauer-Emmett-Teller (BET) analyzer, X-ray diffraction (XRD) and Thermogravimetric analysis (TGA). When evaluated as an electrode material for supercapacitors, the results of electrochemical test show that the unique NiCoO2 nanosheets nanotubes exhibit relatively high specific capacitance of 1468, 1352, 1233, 1178, 1020 and 672 F g-1 at the discharge current densities of 2, 4, 8, 10, 20 and 40 A g-1, respectively. They also reveal an excellent cycling stability of 99.2% retention after 3000 cycles at 10 A g-1. The smart nanostructures of the NiCoO2 nanosheets nanotubes make a prominent contribution to the excellent electrochemical performance.

  13. Few-layered Ni(OH)2 nanosheets for high-performance supercapacitors

    Science.gov (United States)

    Sun, Wenping; Rui, Xianhong; Ulaganathan, Mani; Madhavi, Srinivasan; Yan, Qingyu

    2015-11-01

    Few-layered Ni(OH)2 nanosheets (4-5 nm in thickness) are synthesized towards high-performance supercapacitors. The ultrathin Ni(OH)2 nanosheets show high specific capacitance and good rate capability in both three-electrode and asymmetric devices. In the three-electrode device, the Ni(OH)2 nanosheets deliver a high capacitance of 2064 F g-1 at 2 A g-1, and the capacitance still has a retention of 1837 F g-1 at a high current density of 20 A g-1. Such excellent performance is by far one of the best for Ni(OH)2 electrodes. In the two-electrode asymmetric device, the specific capacitance is 248 F g-1 at 1 A g-1, and reaches 113 F g-1 at 20 A g-1. The capacitance of the asymmetric device maintains to be 166 F g-1 during the 4000th cycle at 2 A g-1, suggesting good cycling stability of the device. Besides, the asymmetric device exhibits gravimetric energy density of 22 Wh kg-1 at a power density of 0.8 kW kg-1. The present results demonstrate that the ultrathin Ni(OH)2 nanosheets are highly attractive electrode materials for achieving fast charging/discharging and high-capacity supercapacitors.

  14. Mesoporous g-C₃N₄ Nanosheets: Synthesis, Superior Adsorption Capacity and Photocatalytic Activity.

    Science.gov (United States)

    Li, Dong-Feng; Huang, Wei-Qing; Zou, Lan-Rong; Pan, Anlian; Huang, Gui-Fang

    2018-08-01

    Elimination of pollutants from water is one of the greatest challenges in resolving global environmental issues. Herein, we report a high-surface-area mesoporous g-C3N4 nanosheet with remarkable high adsorption capacity and photocatalytic performance, which is prepared through directly polycondensation of urea followed by a consecutive one-step thermal exfoliation strategy. This one-pot method to prepare mesoporous g-C3N4 nanosheet is facile and rapid in comparison with others. The superior adsorption capacity of the fabricated mesoporous g-C3N4 nanostructures is demonstrated by a model organic pollutant-methylene blue (MB), which is up to 72.2 mg/g, about 6 times as that of the largest value of various g-C3N4 adsorbents reported so far. Moreover, this kind of porous g-C3N4 nanosheet exhibits high photocatalytic activity to MB and phenol degradation. Particularly, the regenerated samples show excellent performance of pollutant removal after consecutive adsorption/degradation cycles. Therefore, this mesoporous g-C3N4 nanosheet may be an attractive robust metal-free material with great promise for organic pollutant elimination.

  15. Plasmon mediated enhancement and tuning of optical emission properties of two dimensional graphitic carbon nitride nanosheets.

    Science.gov (United States)

    Bayan, Sayan; Gogurla, Narendar; Midya, Anupam; Singha, Achintya; Ray, Samit K

    2017-12-01

    We demonstrate surface plasmon induced enhancement and tunablilty in optical emission properties of two dimensional graphitic carbon nitride (g-C 3 N 4 ) nanosheets through the attachment of gold (Au) nanoparticles. Raman spectroscopy has revealed surface enhanced Raman scattering that arises due to the combined effect of the charge transfer process and localized surface plasmon induced enhancement in electromagnetic field, both occurring at the nanoparticle-nanosheet interface. Photoluminescence studies suggest that at an optimal concentration of nanoparticles, the emission intensity can be enhanced, which is maximum within the 500-525 nm region. Further, the fabricated electroluminescent devices reveal that the emission feature can be tuned from bluish-green to red (∼160 nm shift) upon attaching Au nanoparticles. We propose that the π*→π transition in g-C 3 N 4 can trigger surface plasmon oscillation in Au, which subsequently increases the excitation process in the nanosheets and results in enhanced emission in the green region of the photoluminescence spectrum. On the other hand, electroluminescence of g-C 3 N 4 can induce plasmon oscillation more efficiently and thus can lead to red emission from Au nanoparticles through the radiative damping of particle plasmons. The influence of nanoparticle size and coverage on the emission properties of two dimensional g-C 3 N 4 , nanosheets has also been studied in detail.

  16. Ultra-broadband nonlinear saturable absorption of high-yield MoS2 nanosheets

    Science.gov (United States)

    Wei, Rongfei; Zhang, Hang; Hu, Zhongliang; Qiao, Tian; He, Xin; Guo, Qiangbing; Tian, Xiangling; Chen, Zhi; Qiu, Jianrong

    2016-07-01

    High-yield MoS2 nanosheets with strong nonlinear optical (NLO) responses in a broad near-infrared range were synthesized by a facile hydrothermal method. The observation of saturable absorption, which was excited by the light with photon energy smaller than the gap energy of MoS2, can be attributed to the enhancement of the hybridization between the Mo d-orbital and S p-orbital by the oxygen incorporation into MoS2. High-yield MoS2 nanosheets with high modulation depth and large saturable intensity generated a stable, passively Q-switched fiber laser pulse at 1.56 μm. The high output power of 1.08 mW can be attained under a very low pump power of 30.87 mW. Compared to recently reported passively Q-switched fiber lasers utilizing exfoliated MoS2 nanosheets, the efficiency of the laser for our passive Q-switching operation is larger and reaches 3.50%. This research may extend the understanding on the NLO properties of MoS2 and indicate the feasibility of the high-yield MoS2 nanosheets to passively Q-switched fiber laser effectively at low pump strengths.

  17. Solution-Processable Ultrathin Size- and Shape-Controlled Colloidal Cu2-xS Nanosheets

    NARCIS (Netherlands)

    van der Stam, Ward; Akkerman, Quinten A.; Ke, Xiaoxing; van Huis, Marijn A.; Bals, Sara; Donega, Celso de Mello

    2015-01-01

    Ultrathin two-dimensional (2D) nanosheets (NSs) possess extraordinary properties that are attractive for both fundamental studies and technological devices. Solution-based bottom-up methods are emerging as promising routes to produce free-standing NSs, but the synthesis of colloidal NSs with

  18. Formation of colloidal copper indium sulfide nanosheets by two-dimensional self-organization

    NARCIS (Netherlands)

    Berends, A.C.|info:eu-repo/dai/nl/411263986; Meeldijk, J.D.|info:eu-repo/dai/nl/323921647; van Huis, M.A.|info:eu-repo/dai/nl/304097586; de Mello-Donega, C.|info:eu-repo/dai/nl/125593899

    2017-01-01

    Colloidal 2D semiconductor nanosheets (NSs) are an interesting new class of materials due to their unique properties. However, synthesis of these NSs is challenging and synthesis procedures for materials other than the well-known Pb- and Cd- chalcogenides are still underdeveloped. In this paper, we

  19. Boron nitride nanosheets as improved and reusable substrates for gold nanoparticles enabled surface enhanced Raman spectroscopy

    KAUST Repository

    Cai, Qiran

    2015-01-01

    Atomically thin boron nitride (BN) nanosheets have been found to be excellent substrates for noble metal particles enabled surface enhanced Raman spectroscopy (SERS), thanks to their good adsorption of aromatic molecules, high thermal stability and weak Raman scattering. Faceted gold (Au) nanoparticles have been synthesized on BN nanosheets using a simple but controllable and reproducible sputtering and annealing method. The size and density of the Au particles can be controlled by sputtering time, current and annealing temperature etc. Under the same sputtering and annealing conditions, the Au particles on BN of different thicknesses show various sizes because the surface diffusion coefficients of Au depend on the thickness of BN. Intriguingly, decorated with similar morphology and distribution of Au particles, BN nanosheets exhibit better Raman enhancements than silicon substrates as well as bulk BN crystals. Additionally, BN nanosheets show no noticeable SERS signal and hence cause no interference to the Raman signal of the analyte. The Au/BN substrates can be reused by heating in air to remove the adsorbed analyte without loss of SERS enhancement. This journal is © the Owner Societies 2015.

  20. Facilely prepared, N, O-codoped nanosheet derived from pre-functionalized polymer as supercapacitor electrodes

    Science.gov (United States)

    Wang, Jun; Yang, Ting; Zeng, Zheling; Deng, Shuguang

    2018-04-01

    Nitrogen and oxygen codoped carbon nanosheets derived from pre-functionalized polymer were prepared using a facile direct pyrolysis method. The carbon microstructures are tunable with micro- and mesopore size distribution and a large specific surface area (1628.9-2146.1 m2 g-1). Furthermore, a significant morphology change, from carbon granules to carbon nanosheets, occurred at an annealing temperature of 1273 K. The unique carbon sheet morphology guaranteed a good specific capacitance of 246.4 F g-1 at 0.5 A g-1 in 1 M H2SO4 aqueous solution and an excellent rate capability with a retention of 87.9% at 5 A g-1 as coin cell. The outstanding capacitance attributes to the combination of pseudocapacitance due to the N,O dual-doping and unique nanosheet morphology. Moreover, its outstanding cycling performance with 95% retention over 10,000 cycles at 10 A g-1 and an acceptable energy density of 8.6 Wh kg-1 at 0.2 A g-1 make the N,O-codoped carbon nanosheet potent and promising electrode material for high performance supercapacitors.

  1. Glass and cellulose acetate fibers-supported boehmite nanosheets for bacteria adsorption

    Directory of Open Access Journals (Sweden)

    N.V. Svarovskaya

    2017-04-01

    Full Text Available In this work, in situ method of producing hybrid fibrous adsorbents in which boehmite nanosheets with high sorption properties formed on the surface of hydrophilic microfibres, such as cellulose acetate and glass fibre, was described. The boehmite nanosheets were fabricated by the reaction of composite AlN/Al nanoparticles with water at 60 °C. The synthesized samples were characterized by X-ray diffractometer, scanning, transmission electron microscopy, Fourier transform infrared spectrometer (FT-IR, zeta-potential and specific surface area analyzers. The introduction of microfibres into a diluted aqueous suspension of nanopowders causes heteroadagulation of the nanoparticles and accelerates their further transformation. This effect is most substantial with the glass microfibre, which is thought to have a higher concentration of surface groups capable of generating hydrogen bonds that act as heteroadagulation and nucleation centres. The experimental results showed that the morphology of the resultant hybrid fibrous adsorbents differed accordingly: the nanosheets were attached on-edge to the glass microfibre surface, while on the surface of the cellulose acetate microfibre, they were secured in the form of spherical “nanoflowers” of agglomerated nanosheets. The effect of the morphology of hybrid fibrous adsorbents on adsorption bacteria Escherichia coli was also investigated.

  2. Free-Standing Bilayered Nanoparticle Superlattice Nanosheets with Asymmetric Ionic Transport Behaviors.

    Science.gov (United States)

    Rao, Siyuan; Si, Kae Jye; Yap, Lim Wei; Xiang, Yan; Cheng, Wenlong

    2015-11-24

    Natural cell membranes can directionally and selectively regulate the ion transport, which is critical for the functioning of living cells. Here, we report on the fabrication of an artificial membrane based on an asymmetric nanoparticle superlattice bilayered nanosheet, which exhibits similar ion transport characteristics. The superlattice nanosheets were fabricated via a drying-mediated self-assembly of polystyrene-capped gold nanoparticles at the liquid-air interface. By adopting a layer-by-layer assembly process, an asymmetric nanomembrane could be obtained consisting of two nanosheets with different nanoparticle size. The resulting nanomembranes exhibit an asymmetric ion transport behavior, and diode-like current-voltage curves were observed. The asymmetric ion transport is attributed to the cone-like nanochannels formed within the membranes, upon which a simulation map was established to illustrate the relationship between the channel structure and the ionic selectivity, in consistency with our experimental results. Our superlattice nanosheet-based design presents a promising strategy for the fabrication of next-generation smart nanomembranes for rationally and selectively regulating the ion transport even at a large ion flux, with potential applications in a wide range of fields, including biosensor devices, energy conversion, biophotonics, and bioelectronics.

  3. A general synthesis strategy for the multifunctional 3D polypyrrole foam of thin 2D nanosheets

    Science.gov (United States)

    Xue, Jiangli; Mo, Maosong; Liu, Zhuming; Ye, Dapeng; Cheng, Zhihua; Xu, Tong; Qu, Liangti

    2018-05-01

    A 3D macroporous conductive polymer foam of thin 2D polypyrrole (PPy) nanosheets is developed by adopting a novel intercalation of guest (monomer Py) between the layers of the lamellar host (3D vanadium oxide foam) template-replication strategy. The 3D PPy foam of thin 2D nanosheets exhibits diverse functions including reversible compressibility, shape memory, absorption/adsorption and mechanically deformable supercapacitor characteristics. The as-prepared 3D PPy foam of thin nanosheets is highly light weight with a density of 12 mg·cm-3 which can bear the large compressive strain up to 80% whether in wet or dry states; and can absorb organic solutions or extract dye molecules fast and efficiently. In particular, the PPy nanosheet-based foamas a mechanically deformable electrode material for supercapacitors exhibits high specific capacitance of 70 F·g-1 at a fast charge-discharge rate of 50 mA·g-1, superior to that of any other typical pure PPy-based capacitor. We envision that the strategy presented here should be applicable to fabrication of a wide variety of organic polymer foams and hydrogels of low-dimensional nanostructures and even inorganic foams and hydrogels of low-dimensional nanostructures, and thus allow for exploration of their advanced physical and chemical properties.

  4. Interlayer expanded molybdenum disulfide nanosheets assembly for electrochemical supercapacitor with enhanced performance

    Energy Technology Data Exchange (ETDEWEB)

    Xiao, Huaqing; Wang, Shutao; Zhang, Shuo; Wang, Yihe; Xu, Qingfei; Hu, Wenjie [College of Science, China University of Petroleum (East China), 66 Changjiang West Road, Qingdao Economic Development Zone, Qingdao, Shandong, 266580 (China); Zhou, Yan, E-mail: yanzhou@upc.edu.cn [College of Science, China University of Petroleum (East China), 66 Changjiang West Road, Qingdao Economic Development Zone, Qingdao, Shandong, 266580 (China); State Key Laboratory of Heavy Oil Processing, China University of Petroleum (East China), 66 Changjiang West Road, Qingdao Economic Development Zone, Qingdao, Shandong, 266580 (China); Wang, Zhaojie [College of Science, China University of Petroleum (East China), 66 Changjiang West Road, Qingdao Economic Development Zone, Qingdao, Shandong, 266580 (China); An, Changhua [College of Science, China University of Petroleum (East China), 66 Changjiang West Road, Qingdao Economic Development Zone, Qingdao, Shandong, 266580 (China); College of Chemistry and Chemical Engineering, Tianjin University of Technology, Tianjin, 300384 (China); Zhang, Jun, E-mail: zhangj@upc.edu.cn [State Key Laboratory of Heavy Oil Processing, China University of Petroleum (East China), 66 Changjiang West Road, Qingdao Economic Development Zone, Qingdao, Shandong, 266580 (China)

    2017-05-01

    Rational structural design for electrode materials is essential for fabricating high performance supercapacitors. In this work, we demonstrated a novel way to prepare incompact MoS{sub 2} nanosheets assembled nanorods with the interlayer of MoS{sub 2} nanosheets expanded to 0.89 nm, namely layer expanded MoS{sub 2} nanorods (LE-MoS{sub 2} NRs). The material was characterized by XRD, XPS and electron microscopes. The XRD data and HRTEM images confirmed the existence of expanded interlayer of MoS{sub 2} nanosheets. N{sub 2} adsorption-desorption isotherms of LE-MoS{sub 2} NRs indicated high specific area up to 37.0 m{sup 2} g{sup −1}. It was found that the expanded interlayer spacing can benefit the ion transportation within the MoS{sub 2} interlayers. The as-prepared electrode material showed capacitance up to 231 F g{sup −1} at 1 A g{sup −1} charge-discharge current and cycling stability test indicated high capacitance of 177 F g{sup −1} was retained after 1000 cycles. - Highlights: • High performance electrochemical supercapacitor electrode material. • Interlayer expanded MoS{sub 2} to achieve enhanced capacitance. • Facile hydrothermal synthesis of interlayer expanded MoS{sub 2}. • MoS{sub 2} nanosheets assembled incompact nanorods.

  5. An approach for scalable production of silver (Ag) decorated WS2 nanosheets

    Science.gov (United States)

    Sumesh, C. K.; Kapatel, Sanni; Chaudhari, Arti

    2018-05-01

    In the Present study we report the synthesis of Ag nanoparticles (NPs) decorated WS2 nanosheets by sonochemical exfoliation followed by simple chemical reduction process at room temperature. The morphology and microstructure of the as-synthesized Ag-WS2 nanocomposite were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) and optical absorption (UV-Vis.) spectroscopy. X-ray and TEM analysis shows the presence of Ag with significant peak over 38.08°, 44.22°, 64.37° and 77.33° at 2θ angle for (111), (200), (220) and (311) respectively. The Ag nanoparticles are randomly distributed throughout the surface of the WS2 nanosheets without undergoing further oxidation during the formation of composites. The formation of Ag-WS2 nanocomposites shows a clear blue shift in the absorption as we obtained the characteristics absorption valleys at 456, 536 and 631 nm from the UV Vis spectroscopy analysis compared to pure WS2 nanosheets. Henceforth a facile method for the Ag decoration on WS2 nanosheets was put forward and briefly discussed. The proposed synthesis method is very promising for the low cost and large-scale synthesis of other noble metal incorporation TMDC compounds.

  6. Modification of WS2 nanosheets with controllable layers via oxygen ion irradiation

    Science.gov (United States)

    Song, Honglian; Yu, Xiaofei; Chen, Ming; Qiao, Mei; Wang, Tiejun; Zhang, Jing; Liu, Yong; Liu, Peng; Wang, Xuelin

    2018-05-01

    As one kind of two-dimensional materials, WS2 nanosheets have drawn much attention with different kinds of research methods. Yet ion irradiation method was barely used for WS2 nanosheets. In this paper, the structure, composition and optical band gap (Eg) of the multilayer WS2 films deposited by chemical vapor deposition (CVD) method on sapphire substrates before and after oxygen ion irradiation with different energy and fluences were studied. Precise tailored layer-structures and a controllable optical band gap of WS2 nanosheets were achieved after oxygen ion irradiation. The results shows higher energy oxygen irradiation changed the shape from triangular shaped grains to irregular rectangle shape but did not change 2H-WS2 phase structure. The intensity of E2g1 (Г) and A1g (Г) modes decreased and have small shifts after oxygen ion irradiation. The peak frequency difference between the E2g1 (Г) and A1g (Г) modes (Δω) decreased after oxygen ion irradiation, and this result indicates the number of layers decreased after oxygen ion irradiation. The Eg decreased with the increase of the energy and the fluence of oxygen ions. The number of layers, thickness and optical band gap changed after ion irradiation with different ion fluences and energies. The results proposed a new strategy for precise control of multilayer nanosheets and demonstrated the high applicability of ion irradiation in super-capacitors, field effect transistors and other applications.

  7. Interlayer expanded molybdenum disulfide nanosheets assembly for electrochemical supercapacitor with enhanced performance

    International Nuclear Information System (INIS)

    Xiao, Huaqing; Wang, Shutao; Zhang, Shuo; Wang, Yihe; Xu, Qingfei; Hu, Wenjie; Zhou, Yan; Wang, Zhaojie; An, Changhua; Zhang, Jun

    2017-01-01

    Rational structural design for electrode materials is essential for fabricating high performance supercapacitors. In this work, we demonstrated a novel way to prepare incompact MoS_2 nanosheets assembled nanorods with the interlayer of MoS_2 nanosheets expanded to 0.89 nm, namely layer expanded MoS_2 nanorods (LE-MoS_2 NRs). The material was characterized by XRD, XPS and electron microscopes. The XRD data and HRTEM images confirmed the existence of expanded interlayer of MoS_2 nanosheets. N_2 adsorption-desorption isotherms of LE-MoS_2 NRs indicated high specific area up to 37.0 m"2 g"−"1. It was found that the expanded interlayer spacing can benefit the ion transportation within the MoS_2 interlayers. The as-prepared electrode material showed capacitance up to 231 F g"−"1 at 1 A g"−"1 charge-discharge current and cycling stability test indicated high capacitance of 177 F g"−"1 was retained after 1000 cycles. - Highlights: • High performance electrochemical supercapacitor electrode material. • Interlayer expanded MoS_2 to achieve enhanced capacitance. • Facile hydrothermal synthesis of interlayer expanded MoS_2. • MoS_2 nanosheets assembled incompact nanorods.

  8. MoS2 nanosheet functionalized with Cu nanoparticles and its application for glucose detection

    International Nuclear Information System (INIS)

    Huang, Jingwei; Dong, Zhengping; Li, Yanrong; Li, Jing; Tang, Weijie; Yang, Haidong; Wang, Jia; Bao, Yun; Jin, Jun; Li, Rong

    2013-01-01

    Graphical abstract: - Highlights: • First report on decorating MoS 2 nanosheet with Cu nanoparticles by chemical reduction. • Cu nanoparticles were uniformly decorated on MoS 2 nanosheet. • Glucose biosensor based on copper nanoparticles-MoS 2 nanosheet hybrid is fabricated. • The biosensor exhibits high sensitivity. - Abstract: For the first time, Cu nanoparticles were evenly decorated on MoS 2 nanosheet by chemical reduction. The as-prepared Cu-MoS 2 hybrid was characterized by atomic force microscope (AFM), Raman spectroscopy, transmission electron microscopy (TEM), X-ray diffraction (XRD) and then used to fabricate a non-enzymatic glucose sensor. The performance of our sensor was investigated by cyclic voltammetry and amperometric measurement in alkaline media. Electrochemical tests showed that Cu-MoS 2 hybrid exhibited synergistic electrocatalytic activity on the oxidation of glucose with a high sensitivity of 1055 μA mM −1 cm −2 and a linear range up to 4 mM

  9. Graphene nanosheets and graphite oxide as promising adsorbents for removal of organic contaminants from aqueous solution.

    Science.gov (United States)

    Ji, Liangliang; Chen, Wei; Xu, Zhaoyi; Zheng, Shourong; Zhu, Dongqiang

    2013-01-01

    Graphenes are an emerging class of carbon nanomaterials whose adsorption properties toward organic compounds have not been well understood. In the present study, graphene nanosheets were prepared by reoxidation and abrupt heating of graphite oxide, which was prepared by sequential chemical oxidation of commercial nonporous graphite powder. Adsorption properties of three aromatic compounds (naphthalene, 2-naphthol, and 1-naphthylamine) and one pharmaceutical compound (tylosin) on graphene nanosheets and graphite oxide were examined to explore the potential of these two adsorbents for the removal of organic contaminants from aqueous solutions. Compared with the literature data of adsorption on carbon nanotubes, adsorption of bulky, flexible tylosin on graphene nanosheets exhibited markedly faster adsorption kinetics, which can be attributed to their opened-up layer structure. Graphene nanosheets and graphite oxide showed similar sequences of adsorption affinity: 1-naphthylamine > 2-naphthol > tylosin > naphthalene (with much larger differences observed on graphite oxide). It was proposed that the strong adsorption of the three aromatic compounds was mainly due to π-π electron donor-acceptor interactions with the graphitic surfaces of adsorbents. Additionally, Lewis acid-base interaction was likely an important factor contributing to the strong adsorption of 1-naphthylamine and tylosin, especially for the O-functionality-abundant graphite oxide. After being normalized on the basis of adsorbent surface area, adsorption affinities of all four tested adsorbates on graphene nanosheets were very close to those on nonporous graphite powder, reflecting complete accessibility of the adsorbent surface area in adsorption. Copyright © by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, Inc.

  10. Enhanced electrochemical performance of CoAl-layered double hydroxide nanosheet arrays coated by platinum films

    International Nuclear Information System (INIS)

    Cheng, J.P.; Fang, J.H.; Li, M.; Zhang, W.F.; Liu, F.; Zhang, X.B.

    2013-01-01

    Graphical abstract: Schematic illustration for the electron transport between the current collector and the active CoAl LDH arrays, where the yellow arrows indicate the high resistance of CoAl LDH, while the green arrows present the high conductivity of Pt films on LDH. -- Highlights: •CoAl layered double hydroxide nanosheet arrays are synthesized by hydrothermal method. •Pt films coated on surface of CoAl nanosheets facilitate fast electron transport. •CoAl LDH nanosheets coated with Pt film for 5 min have an excellent performance. -- Abstract: Three-dimensional network of cobalt and aluminum layered double hydroxide (LDH) nanosheets was synthesized on nickel foam by a simple hydrothermal method. The CoAl-LDH nonosheets were subsequently coated by ion sputtering with thin layers of Pt films to facilitate fast electron transport between current collector and the CoAl-LDH active materials. The optimal thickness of the Pt film acquiring the best performance was identified by applying various sputtering time in controlled experiments. The supercapacitor built by the CoAl-LDH nanosheets coated with Pt film sputtered for 5 min has a high specific capacitance (734.4 F g −1 at 3 A g −1 ), excellent rate capability as well as cycling stability. Moreover, it showed a long life of 77% retention after 6000 cycles and its general morphology was preserved after the test. The synergetic affect of conductive layer of Pt films and CoAl-LDH on the improvement of electrochemical properties was discussed and this would provide a useful clue in designing novel and effective electrode materials for supercapacitors

  11. Exfoliated MoS2 nanosheets as efficient catalysts for electrochemical hydrogen evolution

    International Nuclear Information System (INIS)

    Ji, Shanshan; Yang, Zhe; Zhang, Chao; Liu, Zhenyan; Tjiu, Weng Weei; Phang, In Yee; Zhang, Zheng; Pan, Jisheng; Liu, Tianxi

    2013-01-01

    Graphical abstract: An efficient electrocatalyst for hydrogen evolution has been developed based on exfoliation of bulk MoS 2 crystals via a direct dispersion and ultrasonication method. Drop-casting method is used to fabricate the exfoliated MoS 2 nanosheets modified glass carbon electrode (E-MoS 2 /GCE) with various loadings. The E-MoS 2 /GCE with electrode loading of 48 μg cm −1 exhibits high catalytic activity for hydrogen evolution with a low overpotential (−0.12 V) and a high current density (1.26 mA cm −2 , at η = 150 mV). -- Highlights: • Two-dimensional MoS 2 nanosheets have been obtained by exfoliation of bulk MoS 2 crystals. • Exfoliated MoS 2 nanosheets show high electrocatalytic activity for H 2 production. • This study provides a new approach for renewable and economic H 2 production. -- Abstract: An efficient electrocatalyst for hydrogen evolution has been developed based on liquid exfoliation of bulk MoS 2 via a direct dispersion and ultrasonication method. Transmission electron microscopy and atomic force microscopy measurements show that the exfoliated MoS 2 consists of two-dimensional nanosheets. The exfoliated MoS 2 nanosheets modified glass carbon electrode (E-MoS 2 /GCE) with various loadings is fabricated via a drop-casting method. The electrocatalytic activity of E-MoS 2 /GCE toward hydrogen evolution reaction is examined using linear sweep voltammetry. It is shown that the E-MoS 2 /GCE with an electrode loading of 48 μg cm −2 exhibits a high catalytic activity for hydrogen evolution with a low overpotential (−0.12 V) and a high current density (1.26 mA cm −2 , at η = 150 mV)

  12. Chemically linked metal-matrix nanocomposites of boron nitride nanosheets and silver as thermal interface materials

    Science.gov (United States)

    Nagabandi, N.; Yegin, C.; Feng, X.; King, C.; Oh, J. K.; Scholar, E. A.; Narumanchi, S.; Akbulut, M.

    2018-03-01

    Herein, novel hybrid nanocomposite thermal interface materials (TIMs) relying on the chemical linkage of silver, boron nitride nanosheets (BNNSs), and organic ligands are reported. These TIMs were prepared using a co-electrodeposition/chemisorption approach where the electrolytic reduction of silver ions into silver nano-/micro-crystals was coupled with the conjugation of ligand-coated nanosheets onto silver crystals. Furthermore, the influence of the bond strength of silver/nanosheet links on the thermal, mechanical, and structural properties is investigated using a combination of techniques including laser flash analysis, phase-sensitive transient thermoreflectance, nanoindentation, and electron microscopy. The internal nanostructure was found to be strongly dependent on the linker chemistry. While the chemical grafting of 4-cyano-benzoyl chloride (CBC) and 2-mercapto-5-benzimidazole carboxylic acid (MBCA) on BNNSs led to the uniform distribution of functionalized-nanosheets in the silver crystal matrix, the physical binding of 4-bromo-benzoyl chloride linkers on nanosheets caused the aggregation and phase separation. The thermal conductivity was 236-258 W m-1 K and 306-321 W m-1 K for physically and chemically conjugated TIMs, respectively, while their hardness varied from 400-495 MPa and from 240 to 360 MPa, respectively. The corresponding ratio of thermal conductivity to hardness, which is a critical parameter controlling the performance of TIMs, was ultrahigh for the chemically conjugated TIMs: 1.3 × 10-6 m2 K-1 s for MBCA-BNNS and 8.5 × 10-7 m2 K-1 s for CBC-BNNS. We anticipate that these materials can satisfy some of the emerging thermal management needs arising from the improved performance and efficiency, miniaturization, and/or high throughput of electronic devices, energy storage devices, energy conversion systems, light-emitting diodes, and telecommunication components.

  13. Highly-ordered mesoporous titania thin films prepared via surfactant assembly on conductive indium-tin-oxide/glass substrate and its optical properties

    International Nuclear Information System (INIS)

    Uchida, Hiroshi; Patel, Mehul N.; May, R. Alan; Gupta, Gaurav; Stevenson, Keith J.; Johnston, Keith P.

    2010-01-01

    Highly ordered mesoporous titanium dioxide (titania, TiO 2 ) thin films on indium-tin-oxide (ITO) coated glass were prepared via a Pluronic (P123) block copolymer template and a hydrophilic TiO 2 buffer layer. The contraction of the 3D hexagonal array of P123 micelles upon calcination merges the titania domains on the TiO 2 buffer layer to form mesoporous films with a mesochannel diameter of approximately 10 nm and a pore-to-pore distance of 10 nm. The mesoporous titania films on TiO 2 -buffered ITO/glass featured an inverse mesospace with a hexagonally-ordered structure, whereas the films formed without a TiO 2 buffer layer had a disordered microstructure with submicron cracks because of non-uniform water condensation on the hydrophobic ITO/glass surface. The density of the mesoporous film was 83% that of a bulk TiO 2 film. The optical band gap of the mesoporous titania thin film was approximately 3.4 eV, larger than that for nonporous anatase TiO 2 (∼ 3.2 eV), suggesting that the nanoscopic grain size leads to an increase in the band gap due to weak quantum confinement effects. The ability to form highly-ordered mesoporous titania films on electrically conductive and transparent substrates offers the potential for facile fabrication of high surface area semiconductive films with small diffusion lengths for optoelectronics applications.

  14. Probing the Effects of Templating on the UV and Visible Light Photocatalytic Activity of Porous Nitrogen-Modified Titania Monoliths for Dye Removal.

    Science.gov (United States)

    Nursam, Natalita M; Wang, Xingdong; Tan, Jeannie Z Y; Caruso, Rachel A

    2016-07-13

    Porous nitrogen-modified titania (N-titania) monoliths with tailored morphologies were prepared using phase separation and agarose gel templating techniques. The doping and templating process were simultaneously carried out in a one-pot step using alcohol amine-assisted sol-gel chemistry. The amount of polymer used in the monoliths that were prepared using phase separation was shown to affect both the physical and optical properties: higher poly(ethylene glycol) content increased the specific surface area, porosity, and visible light absorption of the final materials. For the agarose-templated monoliths, the infiltration conditions affected the monolith morphology. A porous monolith with high surface area and the least shrinkage was obtained when the N containing alkoxide precursor was infiltrated into the agarose scaffolds at 60 °C. The effect of the diverse porous morphologies on the photocatalytic activity of N-titania was studied for the decomposition of methylene blue (MB) under visible and UV light irradiation. The highest visible light activity was achieved by the agarose-templated N-titania monolith, in part due to higher N incorporation. This sample also showed better UV activity, partly because of the higher specific surface area (up to 112 m(2) g(-1)) compared to the phase separation-induced monoliths (up to 103 m(2) g(-1)). Overall, agarose-templated, porous N-titania monoliths provided better features for effectively removing the MB contaminant.

  15. Transmission electron microscopy of carbon-coated and iron-doped titania nanoparticles

    KAUST Repository

    Anjum, Dalaver H.

    2016-08-02

    We present a study on the properties of iron (Fe)-doped and carbon (C)-coated titania (TiO2) nanoparticles (NPs) which has been compiled by using x-ray diffraction (XRD), transmission electron microscopy (TEM), and x-ray photoelectron spectroscopy (XPS). These TiO2 NPs were prepared by using the flame synthesis method. This method allows the simultaneous C coating and Fe doping of TiO2 NPs. XRD investigations revealed that the phase of the prepared NPs was anatase TiO2. Conventional TEM analysis showed that the average size of the TiO2 NPs was about 65 nm and that the NPs were uniformly coated with the element C. Furthermore, from the x-ray energy dispersive spectrometry analysis, it was found that about 8 at.% Fe was present in the synthesized samples. High-resolution TEM (HRTEM) revealed the graphitized carbon structure of the layer surrounding the prepared TiO2 NPs. HRTEM analysis further revealed that the NPs possessed the crystalline structure of anatase titania. Energy-filtered TEM (EFTEM) analysis showed the C coating and Fe doping of the NPs. The ratio of L3 and L2 peaks for the Ti-L23 and Fe-L23 edges present in the core loss electron energy loss spectroscopy (EELS) revealed a +4 oxidation state for the Ti and a +3 oxidation state for the Fe. These EELS results were further confirmed with XPS analysis. The electronic properties of the samples were investigated by applying Kramers-Kronig analysis to the low-loss EELS spectra acquired from the prepared NPs. The presented results showed that the band gap energy of the TiO2 NPs decreased from an original value of 3.2 eV to about 2.2 eV, which is quite close to the ideal band gap energy of 1.65 eV for photocatalysis semiconductors. The observed decrease in band gap energy of the TiO2 NPs was attributed to the presence of Fe atoms at the lattice sites of the anatase TiO2 lattice. In short, C-coated and Fe-doped TiO2 NPs were synthesized with a rather cost-effective and comparatively easily scalable method. The

  16. Controlling the microstructure and properties of titania nanopowders for high efficiency dye sensitized solar cells

    International Nuclear Information System (INIS)

    Shalan, A.E.; Rashad, M.M.; Yu, Youhai; Lira-Cantú, Mónica; Abdel-Mottaleb, M.S.A.

    2013-01-01

    Graphical abstract: (a) A highly ordered, vertically oriented TiO 2 nanorods compared with TiO 2 nanopaticles and (b) Dye sensitized solar cell fabricated using sealing technique. Highlights: ► TiO 2 nanorods particles size of 3–5 nm was synthesized hydrothermally at 100 °C. ► S BET was 78.14 m 2 /g and the band gap energy was 3.2 eV. ► (J sc ) and (V oc ) of the DSSC were in the range 10.84–13.23 mA cm −2 and 0.71–0.78 V. ► Conversion efficiency of DSSCs was 7.2%. ► IPCE analyses of the DSSC showed two peaks, at ∼350 and 520 nm. -- Abstract: A low temperature hydrothermal process have been developed to synthesize titania nanorods (NRs) and nanoparticles (NPs) with controlled size for dye sensitized solar cells (DSSCs). Effect of calcination temperature on the performance of TiO 2 nanoparticles for solar cells was investigated and discussed. The crystallite size and the relative crystallinity of the anatase phase were increased with increasing the calcination temperature. The structures and morphologies of both (TiO 2 nanorods and nanoparticles) were characterized using XRD, SEM, TEM/HRTEM, UV–vis Spectroscopy, FTIR and BET specific surface area (S BET ) as well as pore-size distribution by BJH. The size of the titania nanorods was 6.7 nm width and 22 nm length while it was 13 nm for nanoparticles. Efficiency of dye-sensitized solar cells (DSSCs) fabricated with oriented TiO 2 nanorods was reported to be more superior compared to DSSC based on mesoporous TiO 2 nanoparticles due to their high surface area, hierarchically mesoporous structures, low charge recombination and fast electron-transfer rate. With increasing calcination temperature of the prepared nanopowders, the light-electricity conversion efficiency (η) decreased. The efficiency of the assembly solar cells was decreased due to the agglomeration of the particles and difficulty of electron movement. The power efficiency was enhanced from 1.7% for TiO 2 nanoparticles cells at

  17. Polymer-derived Ceramic SiCN-MoS2 Nanosheet Composite for Lithium Ion Battery Anodes

    Science.gov (United States)

    Bhandavat, Romil; Singh, Gurpreet

    2012-02-01

    We demonstrate synthesis of a novel SiCN-MoS2 nanosheet composite for use as Li-ion battery anode for high power applications. The nanosheet composite was prepared by thermal decomposition of polysilazane (SiCN precursor) on exfoliated MoS2 surfaces. The morphology and chemical structure was studied using a range of spectroscopy techniques that revealed a sidewall functionalization of exfoliated MoS2 by the polymeric precursor. The thermodynamic stability of SiCN-MoS2 nanosheets was also confirmed by thermo-gravimetric analysis (1000 degree C). Batteries assembled using MoS2-SiCN nanosheets as active anode material showed that lithium can be reversibly intercalated in the voltage range of 0-2.5 V with first cycle discharge capacity of 620 mAh/g at a current density of 100 mA/g.

  18. Enhanced rate performance of mesoporous Co3O4 nanosheet supercapacitor electrodes by hydrous RuO2 nanoparticle decoration

    KAUST Repository

    Baby, Rakhi Raghavan; Ché n, Wěi; Hedhili, Mohamed N.; Cha, Dong Kyu; Alshareef, Husam N.

    2014-01-01

    -dimensional network with exceptional supercapacitor performance in standard two electrode configuration. Dramatic improvement in the rate capacity of the Co3O4 nanosheets is achieved by electrodeposition of nanocrystalline, hydrous RuO 2 nanoparticles dispersed

  19. Li n @B36 ( n = 1, 2) Nanosheet with Remarkable Electro-Optical Properties: A DFT Study

    Science.gov (United States)

    Solimannejad, Mohammad; Kamalinahad, Saeedeh; Shakerzadeh, Ehsan

    2017-07-01

    In this study, an attempt has been made to investigate alteration in electro-optical properties of bowl-shape B36 nanosheet due to interaction with one and two Li atoms. Our results reveal that the highest occupied molecular orbital-lowest unoccupied molecular orbital (HOMO-LUMO) gap of B36 nanosheet is decreased because of a high energy level which is formed under influence of interactions with Li atoms. Gigantic enhancement in the first hyperpolarizability ( β 0) of the studied nanosheet up to 4920.62 au is indicated owing to the effect of Li adsorption. The result of the present study may be eventuating to design and fabrication of a nanosheet with tunable electro-optical properties.

  20. 2D Sn-doped ZnO ultrathin nanosheet networks for enhanced acetone gas sensing application

    KAUST Repository

    Al-Hadeethi, Yas; Umar, Ahmad; Al-Heniti, Saleh. H.; Kumar, Rajesh; Kim, S.H.; Zhang, Xixiang; Raffah, Bahaaudin M.

    2016-01-01

    In this paper, we report the synthesis, characterizations and gas sensing application of 2D Sn-doped ZnO ultrathin nanosheet networks synthesized by a simple and facile hydrothermal process. The synthesized nanosheets were characterized using several techniques in terms of their morphological, structural, optical and compositional properties. The detailed characterizations confirmed that the nanosheets are pure, grown in high-density, possessing well-crystalline wurtzite hexagonal phase and exhibiting good optical properties. Further, the synthesized nanosheets were used as functional material to develop nanosensor device by coating it on the alumina substrate with suitable electrodes. The fabricated sensor device was tested towards acetone gas which exhibited a maximum sensitivity of 5.556 (Ra/Rg) for 200 ppm of acetone at 320 °C.

  1. Mesoporous carbon anchored with SnS2 nanosheets as an advanced anode for lithium-ion batteries

    International Nuclear Information System (INIS)

    Li, Jianping; Wu, Ping; Lou, Feijian; Zhang, Peng; Tang, Yawen; Zhou, Yiming; Lu, Tianhong

    2013-01-01

    Highlights: •SnS 2 nanosheets densely and uniformly anchored on 3D mesoporous carbon matrix. •Unique structural characteristics of both 2D nanosheet and 3D porous carbon matrix. •Markedly enhanced lithium storage capability by virtue of its structure superiority. -- Abstract: This paper reports a novel type of nanohybrid, mesoporous carbon anchored with SnS 2 nanosheets (MC-SnS 2 NSs), which integrates the structural characteristics of both two-dimensional (2D) nanosheet and 3D porous carbon matrix. When evaluated as an anode for lithium-ion batteries, the MC-SnS 2 NSs exhibits significantly enhanced cycling stability and rate capability by virtue of its unique structural superiority

  2. 2D Sn-doped ZnO ultrathin nanosheet networks for enhanced acetone gas sensing application

    KAUST Repository

    Al-Hadeethi, Yas

    2016-11-10

    In this paper, we report the synthesis, characterizations and gas sensing application of 2D Sn-doped ZnO ultrathin nanosheet networks synthesized by a simple and facile hydrothermal process. The synthesized nanosheets were characterized using several techniques in terms of their morphological, structural, optical and compositional properties. The detailed characterizations confirmed that the nanosheets are pure, grown in high-density, possessing well-crystalline wurtzite hexagonal phase and exhibiting good optical properties. Further, the synthesized nanosheets were used as functional material to develop nanosensor device by coating it on the alumina substrate with suitable electrodes. The fabricated sensor device was tested towards acetone gas which exhibited a maximum sensitivity of 5.556 (Ra/Rg) for 200 ppm of acetone at 320 °C.

  3. Enhanced ductility in thermally sprayed titania coating synthesized using a nanostructured feedstock

    International Nuclear Information System (INIS)

    Lima, R.S.; Marple, B.R.

    2005-01-01

    Nanostructured and conventional titania (TiO 2 ) feedstock powders were thermally sprayed via high velocity oxy-fuel (HVOF). The microstructure, porosity, Vickers hardness, crack propagation resistance, bond strength (ASTM C633), abrasion behavior (ASTM G65) and the wear scar characteristics of these two types of coatings were analyzed and compared. The coating made from the nanostructured feedstock exhibited a bimodal microstructure, with regions containing particles that were fully molten (conventional matrix) and regions with embedded particles that were semi-molten (nanostructured zones) during the thermal spraying process. The bimodal coating also exhibited higher bond strength and higher wear resistance when compared to the conventional coating. By comparing the wear scars of both coatings (via scanning electron microscopy and roughness measurements) it was observed that when the coatings were subjected to the same abrasive conditions the wear scar of the bimodal coating was smoother, with more plastically deformed regions than the conventional coating. It was concluded that this enhanced ductility of the bimodal coating was caused by its higher toughness. The results suggest that nanostructured zones randomly distributed in the microstructure of the bimodal coating act as crack arresters, thereby enhancing toughness and promoting higher critical depth of cut, which provides a broader plastic deformation range than that exhibited by the conventional coating. This work provides evidence that the enhanced ductility of the bimodal coating is a nanostructured-related property, not caused by any other microstructural artifact

  4. Stability of erbium and silver implanted in silica-titania sol-gel films

    International Nuclear Information System (INIS)

    Ramos, A.R.; Marques, C.; Alves, E.; Marques, A.C.; Almeida, R.M.

    2005-01-01

    We implanted silica-titania sol-gel films with 3 x 10 15 at./cm 2 , 180 keV Er + and 6 x 10 16 at./cm 2 , 140 keV Ag + ions. The energies were chosen so that the profiles of Ag and Er overlap. RBS and ERDA were used to study the behaviour of Ag, Er and H during the heat treatments used to density the films. Implantation causes H depletion at the film surface and an increase in H concentration just beneath the implanted Ag and Er profiles. The total H content decreases by 27% to 75% during implantation. During annealing the H content decreases, with an almost complete H loss after annealing for 35 min at 800 deg. C. The Ag profile remains stable up to 600 deg. C. Above 700 deg. C Ag becomes increasingly mobile. Annealing at 800 deg. C for 35 min results in a nearly constant Ag distribution in the film. The Er profile remains unchanged with heat treatment up to the maximum temperature used (800 deg. C)

  5. Kinetic modeling of liquefied petroleum gas (LPG) reduction of titania in MATLAB

    Science.gov (United States)

    Yin, Tan Wei; Ramakrishnan, Sivakumar; Rezan, Sheikh Abdul; Noor, Ahmad Fauzi Mohd; Izah Shoparwe, Noor; Alizadeh, Reza; Roohi, Parham

    2017-04-01

    In the present study, reduction of Titania (TiO2) by liquefied petroleum gas (LPG)-hydrogen-argon gas mixture was investigated by experimental and kinetic modelling in MATLAB. The reduction experiments were carried out in the temperature range of 1100-1200°C with a reduction time from 1-3 hours and 10-20 minutes of LPG flowing time. A shrinking core model (SCM) was employed for the kinetic modelling in order to determine the rate and extent of reduction. The highest experimental extent of reduction of 38% occurred at a temperature of 1200°C with 3 hours reduction time and 20 minutes of LPG flowing time. The SCM gave a predicted extent of reduction of 82.1% due to assumptions made in the model. The deviation between SCM and experimental data was attributed to porosity, thermodynamic properties and minute thermal fluctuations within the sample. In general, the reduction rates increased with increasing reduction temperature and LPG flowing time.

  6. Synthesis and Catalytic Applications of Non-Metal Doped Mesoporous Titania

    Directory of Open Access Journals (Sweden)

    Syed Z. Islam

    2017-03-01

    Full Text Available Mesoporous titania (mp-TiO2 has drawn tremendous attention for a diverse set of applications due to its high surface area, interfacial structure, and tunable combination of pore size, pore orientation, wall thickness, and pore connectivity. Its pore structure facilitates rapid diffusion of reactants and charge carriers to the photocatalytically active interface of TiO2. However, because the large band gap of TiO2 limits its ability to utilize visible light, non-metal doping has been extensively studied to tune the energy levels of TiO2. While first-principles calculations support the efficacy of this approach, it is challenging to efficiently introduce active non-metal dopants into the lattice of TiO2. This review surveys recent advances in the preparation of mp-TiO2 and their doping with non-metal atoms. Different doping strategies and dopant sources are discussed. Further, co-doping with combinations of non-metal dopants are discussed as strategies to reduce the band gap, improve photogenerated charge separation, and enhance visible light absorption. The improvements resulting from each doping strategy are discussed in light of potential changes in mesoporous architecture, dopant composition and chemical state, extent of band gap reduction, and improvement in photocatalytic activities. Finally, potential applications of non-metal-doped mp-TiO2 are explored in water splitting, CO2 reduction, and environmental remediation with visible light.

  7. The application of electrospun titania nanofibers in dye-sensitized solar cells.

    Science.gov (United States)

    Krysova, Hana; Zukal, Arnost; Trckova-Barakova, Jana; Chandiran, Aravind Kumar; Nazeeruddin, Mohammad Khaja; Grätzel, Michael; Kavan, Ladislav

    2013-01-01

    Titania nanofibers were fabricated using the industrial Nanospider(TM) technology. The preparative protocol was optimized by screening various precursor materials to get pure anatase nanofibers. Composite films were prepared by mixing a commercial paste of nanocrystalline anatase particles with the electrospun nanofibers, which were shortened by milling. The composite films were sensitized by Ru-bipyridine dye (coded C106) and the solar conversion efficiency was tested in a dye-sensitized solar cell filled with iodide-based electrolyte solution (coded Z960). The solar conversion efficiency of a solar cell with the optimized composite electrode (η = 7.53% at AM 1.5 irradiation) outperforms that of a solar cell with pure nanoparticle film (η = 5.44%). Still larger improvement was found for lower light intensities. At 10% sun illumination, the best composite electrode showed η = 7.04%, referenced to that of pure nanoparticle film (η = 4.69%). There are non-monotonic relations between the film's surface area, dye sorption capacity and solar performance of nanofiber-containing composite films, but the beneficial effect of the nanofiber morphology for enhancement of the solar efficiency has been demonstrated.

  8. Transparent conducting oxide films of group V doped titania prepared by aqueous chemical solution deposition

    International Nuclear Information System (INIS)

    Elen, Ken; Capon, Boris; De Dobbelaere, Christopher; Dewulf, Daan; Peys, Nick; Detavernier, Christophe; Hardy, An; Van Bael, Marlies K.

    2014-01-01

    Transparent conducting oxide (TCO) films of titania doped with vanadium (V), niobium (Nb) and tantalum (Ta) are obtained by aqueous Chemical Solution Deposition (CSD). The effect of the dopant on the crystallization and microstructure of the resulting films is examined by means of X-ray diffraction and electron microscopy. During annealing of the thin films, in-situ characterization of the crystal structure and sheet resistance is carried out. Niobium doped anatase films, obtained after annealing in forming gas, show a resistivity of 0,28 Ohm cm, which is the lowest resistivity reported for a solution deposited anatase-based TCO so far. Here, we demonstrate that aqueous CSD may provide a strategy for scalable TCO production in the future. - Highlights: • Aqueous chemical solution deposition of doped titanium dioxide • Doping delays the phase transition from anatase to rutile • Lowest resistivity after doping with niobium and annealing in Forming Gas • Transparency higher than 80% in the visible range of optical spectrum

  9. Transparent conducting oxide films of group V doped titania prepared by aqueous chemical solution deposition

    Energy Technology Data Exchange (ETDEWEB)

    Elen, Ken [Inorganic and Physical Chemistry, Institute for Materials Research, Hasselt University, Agoralaan Building D, B-3590 Diepenbeek (Belgium); IMEC vzw division IMOMEC, Agoralaan Building D, B-3590 Diepenbeek (Belgium); Strategisch Initiatief Materialen (SIM), SoPPoM Program (Belgium); Capon, Boris [Strategisch Initiatief Materialen (SIM), SoPPoM Programm (Belgium); Coating and Contacting of Nanostructures, Ghent University, Krijgslaan 281 S1, B-9000 Ghent (Belgium); De Dobbelaere, Christopher [Inorganic and Physical Chemistry, Institute for Materials Research, Hasselt University, Agoralaan Building D, B-3590 Diepenbeek (Belgium); Dewulf, Daan [Inorganic and Physical Chemistry, Institute for Materials Research, Hasselt University, Agoralaan Building D, B-3590 Diepenbeek (Belgium); IMEC vzw division IMOMEC, Agoralaan Building D, B-3590 Diepenbeek (Belgium); Peys, Nick [Inorganic and Physical Chemistry, Institute for Materials Research, Hasselt University, Agoralaan Building D, B-3590 Diepenbeek (Belgium); IMEC vzw, Kapeldreef 75, B-3001 Heverlee (Belgium); Detavernier, Christophe [Coating and Contacting of Nanostructures, Ghent University, Krijgslaan 281 S1, B-9000 Ghent (Belgium); Hardy, An [Inorganic and Physical Chemistry, Institute for Materials Research, Hasselt University, Agoralaan Building D, B-3590 Diepenbeek (Belgium); IMEC vzw division IMOMEC, Agoralaan Building D, B-3590 Diepenbeek (Belgium); Van Bael, Marlies K., E-mail: marlies.vanbael@uhasselt.be [Inorganic and Physical Chemistry, Institute for Materials Research, Hasselt University, Agoralaan Building D, B-3590 Diepenbeek (Belgium); IMEC vzw division IMOMEC, Agoralaan Building D, B-3590 Diepenbeek (Belgium)

    2014-03-31

    Transparent conducting oxide (TCO) films of titania doped with vanadium (V), niobium (Nb) and tantalum (Ta) are obtained by aqueous Chemical Solution Deposition (CSD). The effect of the dopant on the crystallization and microstructure of the resulting films is examined by means of X-ray diffraction and electron microscopy. During annealing of the thin films, in-situ characterization of the crystal structure and sheet resistance is carried out. Niobium doped anatase films, obtained after annealing in forming gas, show a resistivity of 0,28 Ohm cm, which is the lowest resistivity reported for a solution deposited anatase-based TCO so far. Here, we demonstrate that aqueous CSD may provide a strategy for scalable TCO production in the future. - Highlights: • Aqueous chemical solution deposition of doped titanium dioxide • Doping delays the phase transition from anatase to rutile • Lowest resistivity after doping with niobium and annealing in Forming Gas • Transparency higher than 80% in the visible range of optical spectrum.

  10. A Low Resistance Calcium/Reduced Titania Passivated Contact for High Efficiency Crystalline Silicon Solar Cells

    KAUST Repository

    Allen, Thomas G.

    2017-02-04

    Recent advances in the efficiency of crystalline silicon (c-Si) solar cells have come through the implementation of passivated contacts that simultaneously reduce recombination and resistive losses within the contact structure. In this contribution, low resistivity passivated contacts are demonstrated based on reduced titania (TiOx) contacted with the low work function metal, calcium (Ca). By using Ca as the overlying metal in the contact structure we are able to achieve a reduction in the contact resistivity of TiOx passivated contacts of up to two orders of magnitude compared to previously reported data on Al/TiOx contacts, allowing for the application of the Ca/TiOx contact to n-type c-Si solar cells with partial rear contacts. Implementing this contact structure on the cell level results in a power conversion efficiency of 21.8% where the Ca/TiOx contact comprises only ≈6% of the rear surface of the solar cell, an increase of 1.5% absolute compared to a similar device fabricated without the TiOx interlayer.

  11. Sol-Gel-Derived Hydroxyapatite-Carbon Nanotube/Titania Coatings on Titanium Substrates

    Directory of Open Access Journals (Sweden)

    Chuantong Liu

    2012-04-01

    Full Text Available In this paper, hydroxyapatite-carbon nanotube/titania (HA-CNT/TiO2 double layer coatings were successfully developed on titanium (Ti substrates intended for biomedical applications. A TiO2 coating was firstly developed by anodization to improve bonding between HA and Ti, and then the layer of HA and CNTs was coated on the surface by the sol-gel process to improve the biocompatibility and mechanical properties of Ti. The surfaces of double layer coatings were uniform and crack-free with a thickness of about 7 μm. The bonding strength of the HA-CNT/TiO2 coating was higher than that of the pure HA and HA-CNT coatings. Additionally, in vitro cell experiments showed that CNTs promoted the adhesion of preosteoblasts on the HA-CNT/TiO2 double layer coatings. These unique surfaces combined with the osteoconductive properties of HA exhibited the excellent mechanical properties of CNTs. Therefore, the developed HA-CNT/TiO2 coatings on Ti substrates might be a promising material for bone replacement.

  12. [Synthesis of hollow titania microspheres by using microfluidic droplet-template].

    Science.gov (United States)

    Ma, Jingyun; Jiang, Lei; Qin, Jianhu

    2011-09-01

    Droplet-based microfluidics is of great interest due to its particular characteristics compared with the conventional methods, such as reduced reagent consumption, rapid mixing, high-throughput, shape controlled, etc. A novel method using microfluidic droplet as soft template for the synthesis of hollow titania microspheres was developed. A typical polydimethylsiloxane (PDMS) microfluidic device containing "flow-focusing" geometry was used to generate water/oil (W/O) droplet. The mechanism for the hollow structure formation was based on the interfacial hydrolysis reaction between the continuous phase containing titanium butoxide precursor and the dispersed containing water. The continuous phase mixed with butanol was added in the downstream of the channel after the hydrolysis reaction. This step was used for drawing the water out of the microgels for further hydrolysis. The microgels obtained through a glass pipe integrated were washed, dried under vacuum and calcined after aging for a certain time. The fluorescence and scanning electron microscope (SEM) image of the microspheres indicated the hollow structure and the thickness of the shell. In addition, these microspheres with thin shell (about 2 microm) were apt to rupture and collapse. Droplet-based microfluidic offered a gentle and size-controllable manner to moderate this problem. Moreover, it has potential applications in photocatalysis combined with some modification realized on the chip simultaneously.

  13. A Low Resistance Calcium/Reduced Titania Passivated Contact for High Efficiency Crystalline Silicon Solar Cells

    KAUST Repository

    Allen, Thomas G.; Bullock, James; Jeangros, Quentin; Samundsett, Christian; Wan, Yimao; Cui, Jie; Hessler-Wyser, Aï cha; De Wolf, Stefaan; Javey, Ali; Cuevas, Andres

    2017-01-01

    Recent advances in the efficiency of crystalline silicon (c-Si) solar cells have come through the implementation of passivated contacts that simultaneously reduce recombination and resistive losses within the contact structure. In this contribution, low resistivity passivated contacts are demonstrated based on reduced titania (TiOx) contacted with the low work function metal, calcium (Ca). By using Ca as the overlying metal in the contact structure we are able to achieve a reduction in the contact resistivity of TiOx passivated contacts of up to two orders of magnitude compared to previously reported data on Al/TiOx contacts, allowing for the application of the Ca/TiOx contact to n-type c-Si solar cells with partial rear contacts. Implementing this contact structure on the cell level results in a power conversion efficiency of 21.8% where the Ca/TiOx contact comprises only ≈6% of the rear surface of the solar cell, an increase of 1.5% absolute compared to a similar device fabricated without the TiOx interlayer.

  14. Synthesis and characterization of titania nanotubes by anodizing of titanium in fluoride containing electrolytes

    Science.gov (United States)

    Ahmad, Akhlaq; Haq, Ehsan Ul; Akhtar, Waseem; Arshad, Muhammad; Ahmad, Zubair

    2017-11-01

    Titania nanotubular structure was prepared by anodizing titanium metal in the fluoride containing electrolytes and studied for hydrogen reduction using photo electrochemical cell. Potentiodynamic scan was performed before actual anodizing to optimize the anodizing conditions. The morphology of the TiO2 nanotubes was investigated by SEM and the presence of TiO2 nanotubes was confirmed. Raman spectroscopy was done to confirm the different phases present. Hydrogen generation capability was revealed by electrochemical testing in three-electrode system in dark and in visible light at 200 W power using Gamry Potentiostat. The corrosion potential of TiO2 nanotubes produced was found to be more active side in potassium hydroxide solution under visible light than in the dark condition. Cathodic polarization behavior of specimens in the presence of light showed more activity towards hydrogen generation than in dark condition. In comparison, the hydrogen generation capability of specimen anodized in 2H15 electrolyte was higher than specimens anodized in other electrolytes. Electrochemical impedance spectroscopy was used to study the charge transfer resistance of the nanotubes produced. The results showed that TiO2 nanotubular structure is a promising material for photoelectrochemical cell. Low-charge transfer resistance also depicts that it can be efficiently used to harvest solar energy.

  15. Aerobic methylcyclohexane-promoted epoxidation of stilbene over gold nanoparticles supported on Gd-doped titania

    KAUST Repository

    Mendez, Violaine; Guillois, Kevin; Daniè le, Sté phane; Tuel, Alain; Caps, Valerie

    2010-01-01

    Aerobic partial oxidations of alkanes and alkenes are important processes of the petrochemical industry. The radical mechanisms involved can be catalyzed by soluble salts of transition metals (Co, Cu, Mn...). We show here that the model methylcyclohexane/stilbene co-oxidation reaction can be efficiently catalyzed at lower temperature by supported gold nanoparticles. The support has little influence on gold intrinsic activity but more on the apparent reaction rates which are a combination of catalytic activity and diffusion limitations. These are here minimized by using gadolinium-doped titania nanocrystallites as support for gold nanoparticles. This material is obtained by mild hydrolysis of a new Gd4TiO(OiPr)14 bimetallic oxoalkoxide. It leads to enhanced wettability of the < 3 nm gold particles in the tert-butyl hydroperoxide (TBHP)-initiated epoxidation of stilbene in methylcyclohexane; Au/TiO2:Gd3+ is in turn as active as the state-of-the-art hydrophobic Au/SiO2 catalyst. The rate-determining step of this reaction is identified as the gold-catalyzed homolytic decomposition of TBHP generating radicals and initiating the methylcyclohexane-mediated epoxidation of stilbene, yielding a methylcyclohexan-1-ol/trans-stilbene oxide mixture. Methylcyclohexan-1-ol can also be obtained in the absence of the alkene in the gold-catalyzed solvent-free autoxidation of methylcyclohexane, evidencing the catalytic potential of gold nanoparticles for low temperature C-H activation. © 2010 The Royal Society of Chemistry.

  16. Enhancement of Capacitive Performance in Titania Nanotubes Modified by an Electrochemical Reduction Method

    Directory of Open Access Journals (Sweden)

    Nurul Asma Samsudin

    2018-01-01

    Full Text Available Highly ordered titania nanotubes (TNTs were synthesised by an electrochemical anodization method for supercapacitor applications. However, the capacitive performance of the TNTs was relatively low and comparable to the conventional capacitor. Therefore, in order to improve the capacitive performance of the TNTs, a fast and facile electrochemical reduction method was applied to modify the TNTs (R-TNTs by introducing oxygen vacancies into the lattice. X-ray photoelectron spectroscopy (XPS data confirmed the presence of oxygen vacancies in the R-TNTs lattice upon the reduction of Ti4+ to Ti3+. Electrochemical reduction parameters such as applied voltage and reduction time were varied to optimize the best conditions for the modification process. The electrochemical performance of the samples was analyzed in a three-electrode configuration cell. The cyclic voltammogram recorded at 200 mV s−1 showed a perfect square-shaped voltammogram indicating the excellent electrochemical performance of R-TNTs prepared at 5 V for 30 s. The total area of the R-TNTs voltammogram was 3 times larger than the unmodified TNTs. A specific capacitance of 11.12 mF cm−2 at a current density of 20 μA cm−2 was obtained from constant current charge-discharge measurements, which was approximately 57 times higher than that of unmodified TNTs. R-TNTs also displayed outstanding cycle stability with 99% capacity retention after 1000 cycles.

  17. Solar efficiency of a new deposited titania photocatalyst. Chlorophenol, pesticide and dye removal applications

    Energy Technology Data Exchange (ETDEWEB)

    Guillard, Chantal; Disdier, Jean; Maldonado, Manuel I.; Herrmann, Jean-Marie [Laboratoire D' Application de la Chimie a l' Environnement LACE (UMR 5634), Universite Claude Bernard Lyon I, Bat Jules Raulin, 69622 Villeurbanne Cedex (France); Monnet, Christine; Dussaud, Joseph [AHLSTROM Research and Services, ZI de l' Abbaye, 38780 Pont-Eveque (France); Malato, Sixto; Blanco, Julian [Plataforma Solar de Almeria-CIEMAT, Ctra. Senes Km. 4, 04200 Tabernas, Almeria (Spain)

    2003-11-10

    A specially designed titania photocatalyst was prepared by coating Ahlstrom non-woven paper, used as a flexible photocatalytic support, with Millennium PC500 anatase. At the same time, a new solar photoreactor (STEP) was designed based on the multi-step cascade falling-film principle to ensure good exposure to sunlight and good oxygenation of the effluent to be treated. Several types of reactants were treated: 4-chlorophenol as a model organic pollutant; formetanate, a widely used pesticide in horticulture; a mixture of pesticides used in vineyards; and indigo carmine (IC) and Congo red (CR), which are complex multifunctional dye molecules. Each reaction was performed simultaneously in a solar CPC slurry photoreactor and in the STEP photoreactor under identical solar exposure to better evaluate and validate the results obtained. The STEP solar reactor was found to be as efficient as the CPC for 4-chlorophenol and formetanate total degradation. In contrast, both dyes required longer treatment in STEP experiments. This new system, in which the final tedious filtration can actually be avoided, constitutes a good alternative to slurries.

  18. Degradation of organophosphorus pesticide parathion methyl on nanostructured titania-iron mixed oxides

    Energy Technology Data Exchange (ETDEWEB)

    Henych, Jiří, E-mail: henych@iic.cas.cz [Department of Material Chemistry, Institute of Inorganic Chemistry AS CR v.v.i., 25068 Řež (Czech Republic); Štengl, Václav; Slušná, Michaela; Matys Grygar, Tomáš [Department of Material Chemistry, Institute of Inorganic Chemistry AS CR v.v.i., 25068 Řež (Czech Republic); Janoš, Pavel; Kuráň, Pavel; Štastný, Martin [Faculty of the Environment, J.E. Purkyně University, Králova Výšina 7, 400 96 Ústí nad Labem (Czech Republic)

    2015-07-30

    Highlights: • Ti–Fe mixed oxides were synthesized via low-temperature one-pot method. • Mixed oxides were used for degradation of parathion methyl. • Pure reference oxide samples showed no degradation ability. • Mixed oxides reached 70% degree of conversion of parathion methyl. - Abstract: Titania-iron mixed oxides with various Ti:Fe ratio were prepared by homogeneous hydrolysis of aqueous solutions of titanium(IV) oxysulphate and iron(III) sulphate with urea as a precipitating agent. The synthesized samples were characterized by X-ray diffraction, Raman and infrared spectroscopy, scanning and transmission electron microscopy, XRF analysis, specific surface area (BET) and porosity determination (BJH). These oxides were used for degradation of organophosporus pesticide parathion methyl. The highest degradation efficiency approaching <70% was found for the samples with Ti:Fe ratio 0.25:1 and 1:0.25. Contrary, parathion methyl was not degraded on the surfaces of pure oxides. In general, the highest degradation rate exhibited samples consisted of the iron or titanium oxide containing a moderate amount of the admixture. However, distinct correlations between the degradation rate and the sorbent composition were not identified.

  19. Determination of Food Oxalates Using Silica–Titania Xerogel Modified with Eriochrome Cyanine R

    Directory of Open Access Journals (Sweden)

    Maria A. Morosanova

    2018-03-01

    Full Text Available The interaction of silica–titania xerogel with triphenylmethane dyes (pyrocatechol violet, chrome azurol S, eriochrome cyanine R has been investigated to create a new sensor material for solid phase spectrophotometric determination of food oxalates. The complex forming reaction between xerogel incorporated titanium(IV and triphenylmethane dyes has been studied; half-reaction periods, complex composition, equilibrium constants, and xerogel sorption capacity have been calculated for each dye. Eriochrome cyanine R (ECR is characterized by the shortest half-reaction period, the smallest equilibrium constant, and the greatest capacity; it has been chosen for the sensor material construction because titanium(IV-ECR complex is formed faster and can be destroyed easier than other studied complexes. The interaction of this sensor material with oxalates has been described: the presence of oxalates causes sensor material discoloration and the absorbance is used as analytical signal. The analytical range is 35–900 mg/L (LOD 10.5 mg/L, n = 7. High concentrations of interfering inorganic anions, organic acids, and sucrose did not affect oxalate determination. Proposed solid phase spectrophotometric procedure has been successfully applied for the determination of oxalates in food samples (sorrel, spinach, parsley, ginger, and black pepper and the results are in good agreement with HPLC oxalate determination.

  20. Characterization of gas tunnel type plasma sprayed hydroxyapatite-nanostructure titania composite coatings

    Science.gov (United States)

    Yugeswaran, S.; Kobayashi, A.; Ucisik, A. Hikmet; Subramanian, B.

    2015-08-01

    Hydroxyapatite (HA) can be coated onto metal implants as a ceramic biocompatible coating to bridge the growth between implants and human tissue. Meanwhile many efforts have been made to improve the mechanical properties of the HA coatings without affecting its bioactivity. In the present study, nanostructure titania (TiO2) was mixed with HA powder and HA-nanostructure TiO2 composite coatings were produced by gas tunnel type plasma spraying torch under optimized spraying conditions. For this purpose, composition of 10 wt% TiO2 + 90 wt% HA, 20 wt% TiO2 + 80 wt% HA and 30 wt% TiO2 + 70 wt% HA were selected as the feedstock materials. The phase, microstructure and mechanical properties of the coatings were characterized. The obtained results validated that the increase in weight percentage of nanostructure TiO2 in HA coating significantly increased the microhardness, adhesive strength and wear resistance of the coatings. Analysis of the in vitro bioactivity and cytocompatibility of the coatings were done using conventional simulated body fluid (c-SBF) solution and cultured green fluorescent protein (GFP) labeled marrow stromal cells (MSCs) respectively. The bioactivity results revealed that the composite coating has bio-active surface with good cytocompatibility.

  1. Ultrasound enhanced release of therapeutics from drug-releasing implants based on titania nanotube arrays.

    Science.gov (United States)

    Aw, Moom Sinn; Losic, Dusan

    2013-02-25

    A non-invasive and external stimulus-driven local drug delivery system (DDS) based on titania nanotube (TNT) arrays loaded with drug encapsulated polymeric micelles as drug carriers and ultrasound generator is described. Ultrasound waves (USW) generated by a pulsating sonication probe (Sonotrode) in phosphate buffered saline (PBS) at pH 7.2 as the medium for transmitting pressure waves, were used to release drug-loaded nano-carriers from the TNT arrays. It was demonstrated that a very rapid release in pulsatile mode can be achieved, controlled by several parameters on the ultrasonic generator. This includes pulse length, time, amplitude and power intensity. By optimization of these parameters, an immediate drug-micelles release of 100% that spans a desirable time of 5-50 min was achieved. It was shown that stimulated release can be generated and reproduced at any time throughout the TNT-Ti implant life, suggesting considerable potential of this approach as a feasible and tunable ultrasound-mediated drug delivery system in situ via drug-releasing implants. It is expected that this concept can be translated from an in vitro to in vivo regime for therapeutic applications using drug-releasing implants in orthopedic and coronary stents. Crown Copyright © 2013. Published by Elsevier B.V. All rights reserved.

  2. Anodic fabrication of advanced titania nanotubes photocatalysts for photoelectrocatalysis decolorization of Orange G dye.

    Science.gov (United States)

    Juang, Yaju; Liu, Yijin; Nurhayati, Ervin; Thuy, Nguyen Thi; Huang, Chihpin; Hu, Chi-Chang

    2016-02-01

    Titania nanotubes (TNTs) were fabricated on Ti mesh substrates by the anodizing technique. The effects of preparation variables, such as anodizing voltage, time and calcination temperature on the textural characteristics and photocatalytic activity of TNTs were investigated. The surface morphology, crystalline phase, and chemical composition were analyzed using field emission-scanning electron microscopy and X-ray diffraction. The photo-electrochemical properties of TNTs were examined by voltammetry. The TNTs were tested as a photoanode for advanced oxidation processes, such as photocatalytic, electrocatalytic, and photoelectrocatalytic decolorization of Orange G dye. The well-arranged TNTs electrode prepared in this work showed a high photocurrent density of 101 µA cm(-2) at an optimum length-to-diameter aspect ratio of 31.2. In dye decolorization tests, the electrochemical photocatalytic system using TNTs as the photoanode achieved total decolorization and 64% mineralization under extended reaction time. These results show that TNTs prepared by this method is greatly stable in prolonged use and suitable as a photoanode in the photocatalytic/photoelectrocatalytic treatments of dye wastewater. Copyright © 2015 Elsevier Ltd. All rights reserved.

  3. Synthesis of Co-Electrospun Lead Selenide Nanostructures within Anatase Titania Nanotubes for Advanced Photovoltaics

    Directory of Open Access Journals (Sweden)

    Evan K. Wujcik

    2015-06-01

    Full Text Available Inorganic nano-scale heterostructures have many advantages over hybrid organic-inorganic dye-sensitized solar cells (DSSC or Grätzel cells, including their resistance to photo-bleaching, thermal stability, large specific surface areas, and general robustness. This study presents a first-of-its-kind low-cost all-inorganic lead selenide-anatase titania (PbSe/TiO2 nanotube heterostructure material for photovoltaic applications. Herein, PbSe nanostructures have been co-electrospun within a hollow TiO2 nanotube with high connectivity for highly efficient charge carrier flow and electron-hole pair separation. This material has been characterized by transmission electron microscopy (TEM, electron diffraction, energy dispersive X-ray spectroscopy (EDX to show the morphology and material composition of the synthesized nanocomposite. Photovoltaic characterization has shown this newly synthesized proof-of-concept material can easily produce a photocurrent under solar illumination, and, with further refinement, could reveal a new direction in photovoltaic materials.

  4. Optimization of the Silver Nanoparticles PEALD Process on the Surface of 1-D Titania Coatings.

    Science.gov (United States)

    Radtke, Aleksandra; Jędrzejewski, Tomasz; Kozak, Wiesław; Sadowska, Beata; Więckowska-Szakiel, Marzena; Talik, Ewa; Mäkelä, Maarit; Leskelä, Markku; Piszczek, Piotr

    2017-07-24

    Plasma enhanced atomic layer deposition (PEALD) of silver nanoparticles on the surface of 1-D titania coatings, such as nanotubes (TNT) and nanoneedles (TNN), has been carried out. The formation of TNT and TNN layers enriched with dispersed silver particles of strictly defined sizes and the estimation of their bioactivity was the aim of our investigations. The structure and the morphology of produced materials were determined using X-ray photoelectron spectroscopy (XPS) and scanning electron miscroscopy (SEM). Their bioactivity and potential usefulness in the modification of implants surface have been estimated on the basis of the fibroblasts adhesion and proliferation assays, and on the basis of the determination of their antibacterial activity. The cumulative silver release profiles have been checked with the use of inductively coupled plasma-mass spectrometry (ICPMS), in order to exclude potential cytotoxicity of silver decorated systems. Among the studied nanocomposite samples, TNT coatings, prepared at 3, 10, 12 V and enriched with silver nanoparticles produced during 25 cycles of PEALD, revealed suitable biointegration properties and may actively counteract the formation of bacterial biofilm.

  5. Biocompatibility of Titania Nanotube Coatings Enriched with Silver Nanograins by Chemical Vapor Deposition

    Directory of Open Access Journals (Sweden)

    Piotr Piszczek

    2017-09-01

    Full Text Available Bioactivity investigations of titania nanotube (TNT coatings enriched with silver nanograins (TNT/Ag have been carried out. TNT/Ag nanocomposite materials were produced by combining the electrochemical anodization and chemical vapor deposition methods. Fabricated coatings were characterized by scanning electron microscopy (SEM, X-ray photoelectron spectroscopy (XPS, and Raman spectroscopy. The release effect of silver ions from TNT/Ag composites immersed in bodily fluids, has been studied using inductively coupled plasma mass spectrometry (ICP-MS. The metabolic activity assay (MTT was applied to determine the L929 murine fibroblasts adhesion and proliferation on the surface of TNT/Ag coatings. Moreover, the results of immunoassays (using peripheral blood mononuclear cells—PBMCs isolated from rats allowed the estimation of the immunological activity of TNT/Ag surface materials. Antibacterial activity of TNT/Ag coatings with different morphological and structural features was estimated against two Staphylococcus aureus strains (ATCC 29213 and H9. The TNT/Ag nanocomposite layers produced revealed a good biocompatibility promoting the fibroblast adhesion and proliferation. A desirable anti-biofilm activity against the S. aureus reference strain was mainly noticed for these TiO2 nanotube coatings, which contain dispersed Ag nanograins deposited on their surface.

  6. Fabrication of Semiordered Nanopatterned Diamond-like Carbon and Titania Films for Blood Contacting Applications.

    Science.gov (United States)

    Nandakumar, Deepika; Bendavid, Avi; Martin, Philip J; Harris, Kenneth D; Ruys, Andrew J; Lord, Megan S

    2016-03-23

    Biomaterials with the ability to interface with, but not activate, blood components are essential for a multitude of medical devices. Diamond-like carbon (DLC) and titania (TiO2) have shown promise for these applications; however, both support platelet adhesion and activation. This study explored the fabrication of nanostructured DLC and TiO2 thin film coatings using a block copolymer deposition technique that produced semiordered nanopatterns with low surface roughness (5-8 nm Rrms). These surfaces supported fibrinogen and plasma protein adsorption that predominantly adsorbed between the nanofeatures and reduced the overall surface roughness. The conformation of the adsorbed fibrinogen was altered on the nanopatterned surfaces as compared with the planar surfaces to reveal higher levels of the platelet binding region. Planar DLC and TiO2 coatings supported less platelet adhesion than nanopatterned DLC and TiO2. However, platelets on the nanopatterned DLC coatings were less spread indicating a lower level of platelet activation on the nanostructured DLC coatings compared with the planar DLC coatings. These data indicated that nanostructured DLC coatings may find application in blood contacting medical devices in the future.

  7. Correlative Raman spectroscopy and focused ion beam for targeted phase boundary analysis of titania polymorphs

    Energy Technology Data Exchange (ETDEWEB)

    Mangum, John S.; Chan, Lisa H.; Schmidt, Ute; Garten, Lauren M.; Ginley, David S.; Gorman, Brian P.

    2018-05-01

    Site-specific preparation of specimens using focused ion beam instruments for transmission electron microscopy is at the forefront of targeting regions of interest for nanoscale characterization. Typical methods of pinpointing desired features include electron backscatter diffraction for differentiating crystal structures and energy-dispersive X-Ray spectroscopy for probing compositional variations. Yet there are situations, notably in the titanium dioxide system, where these techniques can fail. Differentiating between the brookite and anatase polymorphs of titania is either excessively laborious or impossible with the aforementioned techniques. However, due to differences in bonding structure, Raman spectroscopy serves as an ideal candidate for polymorph differentiation. In this work, a correlative approach utilizing Raman spectroscopy for targeted focused ion beam specimen preparation was employed. Dark field imaging and diffraction in the transmission electron microscope confirmed the region of interest located via Raman spectroscopy and demonstrated the validity of this new method. Correlative Raman spectroscopy, scanning electron microscopy, and focused ion beam is shown to be a promising new technique for identifying site-specific preparation of nanoscale specimens in cases where conventional approaches do not suffice.

  8. Cellular Homeostasis and Antioxidant Response in Epithelial HT29 Cells on Titania Nanotube Arrays Surface

    Directory of Open Access Journals (Sweden)

    Rabiatul Basria SMN Mydin

    2017-01-01

    Full Text Available Cell growth and proliferative activities on titania nanotube arrays (TNA have raised alerts on genotoxicity risk. Present toxicogenomic approach focused on epithelial HT29 cells with TNA surface. Fledgling cell-TNA interaction has triggered G0/G1 cell cycle arrests and initiates DNA damage surveillance checkpoint, which possibly indicated the cellular stress stimuli. A profound gene regulation was observed to be involved in cellular growth and survival signals such as p53 and AKT expressions. Interestingly, the activation of redox regulator pathways (antioxidant defense was observed through the cascade interactions of GADD45, MYC, CHECK1, and ATR genes. These mechanisms furnish to protect DNA during cellular division from an oxidative challenge, set in motion with XRRC5 and RAD50 genes for DNA damage and repair activities. The cell fate decision on TNA-nanoenvironment has been reported to possibly regulate proliferative activities via expression of p27 and BCL2 tumor suppressor proteins, cogent with SKP2 and BCL2 oncogenic proteins suppression. Findings suggested that epithelial HT29 cells on the surface of TNA may have a positive regulation via cell-homeostasis mechanisms: a careful circadian orchestration between cell proliferation, survival, and death. This nanomolecular knowledge could be beneficial for advanced medical applications such as in nanomedicine and nanotherapeutics.

  9. Electronic structure of titania aerogels: Soft x-ray absorption study

    International Nuclear Information System (INIS)

    Kucheyev, S.O.; Van Buuren, T.V.; Baumann, T.F.; Satcher, J.H.; Willey, T.M.; Muelenberg, R.W.; Felter, T.E.; Poco, J.E.; Gammon, S.A.; Terminello, L.J.

    2004-01-01

    Full text: Titania aerogels - a somewhat extreme form of nanoporous TiO 2 - are open-cell solid foams derived from highly crosslinked gels by drying them under supercritical conditions. In this presentation, the unoccupied electronic states of TiO 2 aerogels are studied by soft x-ray absorption near-edge structure (XANES) spectroscopy. High-resolution O K-edge and Ti L 2,3 -edge XANES spectra of aerogels are compared with those of rutile, anatase, and unrelaxed amorphous phases of full- density TiO 2 . Results show that all the main spectroscopic features of aerogels, reflecting the element-specific partial density of empty electronic states and correlation effects, can be attributed to the absence of long-range order in stoichiometric amorphous TiO 2 . Based on these results, we discuss the effects of short- and long-range order on the electronic structure of TiO 2 . This work was performed under the auspices of the U.S. Department of Energy by the University of California, Lawrence Livermore National Laboratory under Contract No. W-7405-Eng-48

  10. Effects of Ethyl Cellulose on Performance of Titania Photoanode for Dye-sensitized Solar Cells

    Science.gov (United States)

    Liu, Ting-Chien; Wu, Chih-Chung; Huang, Chih-Hsiang; Chen, Chih-Ming

    2016-12-01

    Ethyl cellulose (EC) was added to a titania (TiO2) paste from 2 wt.% to 18 wt.% as a binder/dispersant, and its effects on the photovoltaic performance of dye-sensitized solar cells (DSSCs) were investigated. The TiO2 mesoporous film constructed on the photoanode exhibited a dense and network structure composed of well-interconnected TiO2 nanoparticles when using a proper amount of EC (10 wt.%). Excessive and deficient addition of EC resulted in aggregation of TiO2 nanoparticles and formation of pores, respectively, in the TiO2 film. The power conversion efficiency (PCE) of DSSC showed a strong dependence on the EC content and the highest PCE of 7.53% with the highest short-circuit current density ( J SC) of 12.7 mA/cm2 was achieved when the content of EC was 10 wt.%. The incident photon-to-current conversion efficiency (IPCE) results indicated that the TiO2 mesoporous film fabricated using a proper EC addition was beneficial for electron generation (also confirmed by dye desorption experiments) and electron transport, and, therefore, improved the photovoltaic performance of DSSCs.

  11. Titania-polymeric powder coatings with nano-topography support enhanced human mesenchymal cell responses.

    Science.gov (United States)

    Mozumder, Mohammad Sayem; Zhu, Jesse; Perinpanayagam, Hiran

    2012-10-01

    Titanium implant osseointegration is dependent on the cellular response to surface modifications and coatings. Titania-enriched nanocomposite polymeric resin coatings were prepared through the application of advanced ultrafine powder coating technology. Their surfaces were readily modified to create nano-rough (topographies that supported human embryonic palatal mesenchymal cell responses. Energy dispersive x-ray spectroscopy confirmed continuous and homogenous coatings with a similar composition and even distribution of titanium. Scanning electron microscopy (SEM) showed complex micro-topographies, and atomic force microscopy revealed intricate nanofeatures and surface roughness. Cell counts, mitochondrial enzyme activity reduction of yellow 3-(4,5-dimethythiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) to dark purple, SEM, and inverted fluorescence microscopy showed a marked increase in cell attachment, spreading, proliferation, and metabolic activity on the nanostructured surfaces. Reverse Transcription- Polymerase Chain Reaction (RT-PCR) analysis showed that type I collagen and Runx2 expression were induced, and Alizarin red staining showed that mineral deposits were abundant in the cell cultures grown on nanosurfaces. This enhancement in human mesenchymal cell attachment, growth, and osteogenesis were attributed to the nanosized surface topographies, roughness, and moderate wetting characteristics of the coatings. Their dimensional similarity to naturally occurring matrix proteins and crystals, coupled with their increased surface area for protein adsorption, may have facilitated the response. Therefore, this application of ultrafine powder coating technology affords highly biocompatible surfaces that can be readily modified to accentuate the cellular response. Copyright © 2012 Wiley Periodicals, Inc.

  12. D. C. plasma-sprayed coatings of nano-structured alumina-titania-silica

    CERN Document Server

    Jiang Xian Liang

    2002-01-01

    nano-crystalline powders of omega(Al sub 2 O sub 3) = 95%, omega(TiO sub 2) = 3%, and omega(SiO sub 2) = 2%, were reprocessed into agglomerated particles for plasma spraying, by using consecutive steps of ball milling, slurry forming, spray drying, and heat treatment. D.C. plasma was used to spray the agglomerated nano-crystalline powders, and resultant coatings were deposited on the substrate of stainless steel. Scanning electron microscopy (SEM) was used to examine the morphology of the agglomerated powders and the cross section of the alumina-titania-silica coatings. Experimental results show that the agglomerated nano-crystalline particles are spherical, with a size from (10-90) mu m. The flow ability of the nano-crystalline powders is greatly improved after the reprocessing. The coatings deposited by the plasma spraying are mainly of nano-structure. Unlike conventional plasma-sprayed coatings, no laminar layer could be found in the nano-structured coatings. Although the nano-structured coatings have a lo...

  13. D. C. plasma-sprayed coatings of nano-structured alumina-titania-silica

    International Nuclear Information System (INIS)

    Jiang Xianliang

    2002-01-01

    nano-crystalline powders of ω(Al 2 O 3 ) = 95%, ω(TiO 2 ) = 3%, and ω(SiO 2 ) = 2%, were reprocessed into agglomerated particles for plasma spraying, by using consecutive steps of ball milling, slurry forming, spray drying, and heat treatment. D.C. plasma was used to spray the agglomerated nano-crystalline powders, and resultant coatings were deposited on the substrate of stainless steel. Scanning electron microscopy (SEM) was used to examine the morphology of the agglomerated powders and the cross section of the alumina-titania-silica coatings. Experimental results show that the agglomerated nano-crystalline particles are spherical, with a size from (10-90) μm. The flow ability of the nano-crystalline powders is greatly improved after the reprocessing. The coatings deposited by the plasma spraying are mainly of nano-structure. Unlike conventional plasma-sprayed coatings, no laminar layer could be found in the nano-structured coatings. Although the nano-structured coatings have a lower microhardness than conventional microstructured coatings, the toughness of the nano-structured ceramic coatings is significantly improved

  14. Transparent sculptured titania films for enhanced light absorption in thin-film Si solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Hung, Kai-Hsiang, E-mail: khhung@itri.org.tw [Green Energy and Environment Research Laboratories, Industrial Technology Research Institute, Hsinchu, Taiwan (China); Chiou, Guan-Di; Wong, Ming-Show [Department of Materials Science and Engineering, National Dong Hwa University, Hualien, Taiwan (China); Wang, Yu-Chih [Green Energy and Environment Research Laboratories, Industrial Technology Research Institute, Hsinchu, Taiwan (China); Chung, I-Shan [Electronics and Optoelectronics Research Laboratories, Industrial Technology Research Institute, Hsinchu, Taiwan (China)

    2011-12-30

    This study presents a description of the enhancement of light absorption in thin-film silicon (Si) solar cells by using sculptured titania (TiO{sub 2}) films. We used an electron-beam evaporation system with a glancing angle deposition (GLAD) method to deposit porous TiO{sub 2} films on fluorine-doped SnO{sub 2} (FTO) substrates. The GLAD TiO{sub 2}/FTO films were used as conductive electrodes in hydrogenated microcrystalline silicon ({mu}c-Si:H) solar cells. Transmission electron microscopy revealed that the GLAD TiO{sub 2} films are composed of sculptured nano-pillars on an FTO surface, and this nanostructure provides a synergistic route for light scattering enhancement. The GLAD TiO{sub 2}/FTO exhibited a 68% improvement of optical haze (at {lambda} = 600 nm). The {mu}c-Si:H solar cells consisting of the GLAD-nanostructured TiO{sub 2} resulted in a 5% improvement of short-circuit current (J{sub sc}) and yielded a cell efficiency of 6.6%.

  15. Solar-assisted photodegradation of isoproturon over easily recoverable titania catalysts.

    Science.gov (United States)

    Tolosana-Moranchel, A; Carbajo, J; Faraldos, M; Bahamonde, A

    2017-03-01

    An easily recoverable homemade TiO 2 catalyst (GICA-1) has been evaluated during the overall photodegradation process, understood as photocatalytic efficiency and catalyst recovery step, in the solar light-assisted photodegradation of isoproturon and its reuse in two consecutive cycles. The global feasibility has been compared to the commercial TiO 2 P25. The homemade GICA-1 catalyst presented better sedimentation efficiency than TiO 2 P25 at all studied pHs, which could be explained by its higher average hydrodynamic particle size (3 μm) and other physicochemical surface properties. The evaluation of the overall process (isoproturon photo-oxidation + catalyst recovery) revealed GICA-1 homemade titania catalyst strengths: total removal of isoproturon in less than 60 min, easy recovery by sedimentation, and reusability in two consecutive cycles, without any loss of photocatalytic efficiency. Therefore, considering the whole photocatalytic cycle (good performance in photodegradation plus catalyst recovery step), the homemade GICA-1 photocatalyst resulted in more affordability than commercial TiO 2 P25. Graphical abstract.

  16. Influence of Titania Dispersivity on the Conversion Efficiency of Dye-Sensitized Solar Cells

    Directory of Open Access Journals (Sweden)

    Yasuhiro Yamamoto

    2011-01-01

    Full Text Available Titania powder (P25 was dispersed by bead-milling breakdown method, and the dispersivity of TiO2 was controlled by adjusting the mean secondary TiO2 particle size to 45, 56, and 75 nm by changing the dispersion solvent blend ratio of ethanol and terpineol. The transparency of the coated layer increased when the particle size of TiO2 aggregates became smaller than 100 nm. Although the transparency was significantly different according to differences in the size of nanocrystallyne-TiO2 aggregates, the resulting photovoltaic (PV effect of a dye-sensitized solar cell (DSSC was not significantly different between the different aggregate sizes. A double layer structure (transparent TiO2 layer/opaque TiO2 layer was adopted to improve the PV effect, which resulted in an improvement of the photocurrent and conversion efficiency of 13.2% and 11.1%, respectively, from that for the DSSCs with single-layered TiO2 electrodes.

  17. Biocompatibility of sol-gel hydroxyapatite-titania composite and bilayer coatings

    International Nuclear Information System (INIS)

    Sidane, D.; Rammal, H.; Beljebbar, A.; Gangloff, S.C.; Chicot, D.; Velard, F.; Khireddine, H.

    2017-01-01

    Titania-Hydroxyapatite (TiO 2 /HAP) reinforced coatings are proposed to enhance the bioactivity and corrosion resistance of 316L stainless steel (316L SS). Herein, spin- and dip-coating sol-gel processes were investigated to construct two kinds of coatings: TiO 2 /HAP composite and TiO 2 /HAP bilayer. Physicochemical characterization highlighted the bioactivity response of the TiO 2 /HAP composite once incubated in physiological conditions for 7 days whereas the TiO 2 /HAP bilayer showed instability and dissolution. Biological analysis revealed a failure in human stem cells adhesion on TiO 2 /HAP bilayer whereas on TiO 2 /HAP composite the presence of polygonal shaped cells, possessing good behaviour attested a good biocompatibility of the composite coating. Finally, TiO 2 /HAP composite with hardness up to 0.6 GPa and elastic modulus up to 18 GPa, showed an increased corrosion resistance of 316L SS. In conclusion, the user-friendly sol-gel processes led to bioactive TiO 2 /HAP composite buildup suitable for biomedical applications. - Highlights: • 316L SS implant TiO 2 reinforced HAP coatings were investigated and compared. • TiO 2 /HAP composite had better structural features and biocompatible properties. • Improvement of 316L SS implants corrosion resistance. • TiO 2 /HAP composite mechanical properties close to bone tissue • Low cost and desired material for hard tissue applications

  18. A new approach to the preparation of nitrogen-doped titania visible light photocatalyst

    KAUST Repository

    Kachina, Anna

    2012-02-28

    A new simple method is described, allowing introduction of nitrogen into the TiO 2 lattice at low temperatures. The technique is based on the introduction of oxophilic molecules, such as CCl 4, into the reaction mixture. The treatment of titanium dioxide powders by NH 3-CCl 4 mixtures leads to highly dispersed N-doped TiO 2. As compared to bare TiO 2 or to the same oxide treated with sole NH 3, the solids treated with NH 3-CCl 4 mixtures showed a stronger red shift in optical absorption and enhanced photocatalytic activity under visible light, as demonstrated for two reactions of formic acid oxidation and photocatalytic production of hydrogen from methanol. The nitridation temperature can be significantly decreased by introducing CCl 4, because of a favorable change of the reaction thermodynamics. Not only can higher specific surface area of materials be obtained as a result of avoiding sintering but a higher amount of nitrogen is introduced in a position beneficial for the enhanced catalytic activity. The X-ray photoelectron spectroscopy study demonstrated increased surface concentration of nitrogen having N 1s binding energy near 399 eV. As established by ESR, the nature of paramagnetic species generated by treatments is strongly dependent on the titania polymorph variety and crystallinity as well as on the treatment conditions, but in all cases the major part of introduced nitrogen remains ESR-silent. © 2012 American Chemical Society.

  19. Synthesis and Characterization of Flower-Like Bundles of ZnO Nanosheets by a Surfactant-Free Hydrothermal Process

    Directory of Open Access Journals (Sweden)

    Jijun Qiu

    2014-01-01

    Full Text Available Flower-like bundles of ZnO nanosheets have been prepared by using preheating hydrothermal process without any surfactants. The flower-like bundles consist of many thin and uniform hexagonal-structured ZnO nanosheets, with a thickness of 50 nm. The selected area electronic diffraction (SAED and high-resolution transmission electron microscope (HRTEM images indicate that the ZnO nanosheets are single crystal in nature. The growth mechanism of the flower-like bundles of ZnO nanosheets is discussed based on the morphology evolution with growth times and reaction conditions. It is believed that the formation of flower-like bundles of ZnO nanosheets is related to the shielding effect of OH− ions and the self-assembly process, which is dominated by a preheating time. Room temperature photoluminescence spectra results show that the annealing atmosphere strongly affects the visible emission band, which is sensitive to intrinsic and surface defects, especially oxygen interstitials, in flower-like bundles of ZnO nanosheets.

  20. High-efficient production of boron nitride nanosheets via an optimized ball milling process for lubrication in oil.

    Science.gov (United States)

    Deepika; Li, Lu Hua; Glushenkov, Alexey M; Hait, Samik K; Hodgson, Peter; Chen, Ying

    2014-12-03

    Although tailored wet ball milling can be an efficient method to produce a large quantity of two-dimensional nanomaterials, such as boron nitride (BN) nanosheets, milling parameters including milling speed, ball-to-powder ratio, milling ball size and milling agent, are important for optimization of exfoliation efficiency and production yield. In this report, we systematically investigate the effects of different milling parameters on the production of BN nanosheets with benzyl benzoate being used as the milling agent. It is found that small balls of 0.1-0.2 mm in diameter are much more effective in exfoliating BN particles to BN nanosheets. Under the optimum condition, the production yield can be as high as 13.8% and the BN nanosheets are 0.5-1.5 μm in diameter and a few nanometers thick and of relative high crystallinity and chemical purity. The lubrication properties of the BN nanosheets in base oil have also been studied. The tribological tests show that the BN nanosheets can greatly reduce the friction coefficient and wear scar diameter of the base oil.

  1. Generalized Low-Temperature Fabrication of Scalable Multi-Type Two-Dimensional Nanosheets with a Green Soft Template.

    Science.gov (United States)

    Wang, Lanfang; Song, Chuang; Shi, Yi; Dang, Liyun; Jin, Ying; Jiang, Hong; Lu, Qingyi; Gao, Feng

    2016-04-11

    Two-dimensional nanosheets with high specific surface areas and fascinating physical and chemical properties have attracted tremendous interests because of their promising potentials in both fundamental research and practical applications. However, the problem of developing a universal strategy with a facile and cost-effective synthesis process for multi-type ultrathin 2 D nanostructures remains unresolved. Herein, we report a generalized low-temperature fabrication of scalable multi-type 2 D nanosheets including metal hydroxides (such as Ni(OH)2, Co(OH)2, Cd(OH)2, and Mg(OH)2), metal oxides (such as ZnO and Mn3O4), and layered mixed transition-metal hydroxides (Ni-Co LDH, Ni-Fe LDH, Co-Fe LDH, and Ni-Co-Fe layered ternary hydroxides) through the rational employment of a green soft-template. The synthesized crystalline inorganic nanosheets possess confined thickness, resulting in ultrahigh surface atom ratios and chemically reactive facets. Upon evaluation as electrode materials for pseudocapacitors, the Ni-Co LDH nanosheets exhibit a high specific capacitance of 1087 F g(-1) at a current density of 1 A g(-1), and excellent stability, with 103% retention after 500 cycles. This strategy is facile and scalable for the production of high-quality ultrathin crystalline inorganic nanosheets, with the possibility of extension to the preparation of other complex nanosheets. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  2. Structurally Oriented Nano-Sheets in Co Thin Films: Changing Their Anisotropic Physical Properties by Thermally-Induced Relaxation.

    Science.gov (United States)

    Vergara, José; Favieres, Cristina; Magén, César; de Teresa, José María; Ibarra, Manuel Ricardo; Madurga, Vicente

    2017-12-05

    We show how nanocrystalline Co films formed by separated oblique nano-sheets display anisotropy in their resistivity, magnetization process, surface nano-morphology and optical transmission. After performing a heat treatment at 270 °C, these anisotropies decrease. This loss has been monitored measuring the resistivity as a function of temperature. The resistivity measured parallel to the direction of the nano-sheets has been constant up to 270 °C, but it decreases when measured perpendicular to the nano-sheets. This suggests the existence of a structural relaxation, which produces the change of the Co nano-sheets during annealing. The changes in the nano-morphology and the local chemical composition of the films at the nanoscale after heating above 270 °C have been analysed by scanning transmission electron microscopy (STEM). Thus, an approach and coalescence of the nano-sheets have been directly visualized. The spectrum of activation energies of this structural relaxation has indicated that the coalescence of the nano-sheets has taken place between 1.2 and 1.7 eV. In addition, an increase in the size of the nano-crystals has occurred in the samples annealed at 400 °C. This study may be relevant for the application in devices working, for example, in the GHz range and to achieve the retention of the anisotropy of these films at higher temperatures.

  3. Incorporating nitrogen atoms into cobalt nanosheets as a strategy to boost catalytic activity toward CO2 hydrogenation

    Science.gov (United States)

    Wang, Liangbing; Zhang, Wenbo; Zheng, Xusheng; Chen, Yizhen; Wu, Wenlong; Qiu, Jianxiang; Zhao, Xiangchen; Zhao, Xiao; Dai, Yizhou; Zeng, Jie

    2017-11-01

    Hydrogenation of CO2 into fuels and useful chemicals could help to reduce reliance on fossil fuels. Although great progress has been made over the past decades to improve the activity of catalysts for CO2 hydrogenation, more efficient catalysts, especially those based on non-noble metals, are desired. Here we incorporate N atoms into Co nanosheets to boost the catalytic activity toward CO2 hydrogenation. For the hydrogenation of CO2, Co4N nanosheets exhibited a turnover frequency of 25.6 h-1 in a slurry reactor under 32 bar pressure at 150 °C, which was 64 times that of Co nanosheets. The activation energy for Co4N nanosheets was 43.3 kJ mol-1, less than half of that for Co nanosheets. Mechanistic studies revealed that Co4N nanosheets were reconstructed into Co4NHx, wherein the amido-hydrogen atoms directly interacted with the CO2 to form HCOO* intermediates. In addition, the adsorbed H2O* activated amido-hydrogen atoms via the interaction of hydrogen bonds.

  4. The {0 0 1} facets-dependent superior photocatalytic activities of BiOCl nanosheets under visible light irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Li, Yingjun [College of Chemistry and Chemical Engineering, Inner Mongolia University, Hohhot 010021 (China); Wang, Qin, E-mail: qinwang@imu.edu.cn [College of Chemistry and Chemical Engineering, Inner Mongolia University, Hohhot 010021 (China); Inner Mongolia Key Lab of Nanoscience and Nanotechnology, Inner Mongolia University, Hohhot 010021 (China); Liu, Baocang [College of Chemistry and Chemical Engineering, Inner Mongolia University, Hohhot 010021 (China); Inner Mongolia Key Lab of Nanoscience and Nanotechnology, Inner Mongolia University, Hohhot 010021 (China); Zhang, Jun, E-mail: cejzhang@imu.edu.cn [College of Chemistry and Chemical Engineering, Inner Mongolia University, Hohhot 010021 (China); Inner Mongolia Key Lab of Nanoscience and Nanotechnology, Inner Mongolia University, Hohhot 010021 (China)

    2015-09-15

    Graphical abstract: - Highlights: • BiOCl nanosheets were selectively synthesized via a facile hydrothermal method. • The percentage of {0 0 1} facets over BiOCl nanosheets were well controlled. • These samples manifest superior catalytic activity for the degradation of RhB dyes. - Abstract: BiOCl nanosheets with tunable lamella thickness and dominantly exposed {0 0 1} facets were selectively synthesized via a facile hydrothermal method. By modifying the synthetic parameters, such as the amount of P123 and mannitol, the reaction time, types of surfactants, the size, thickness, morphologies, and percentage of {0 0 1} facets over BiOCl nanosheets were well controlled. The exposed {0 0 1} facets with high surface energy and high density of oxygen atoms are not only conducive to the adsorption of the rhodamine B (RhB) dye but also can accumulate the photo-generated electrons, which can be captured by O{sub 2} and converted into reactive oxygen species O{sub 2}{sup −}·. Therefore, the resultant ultrathin BiOCl nanosheets with exposed {0 0 1} facets exhibit superior catalytic activity for dye photosensitization degradation under visible light irradiation. Impressively, the ultrathin BiOCl nanosheets prepared with P123 and mannitol manifest superior catalytic activity and RhB was completely degraded within 20 min. Our current work is expected to offer a new insight into photocatalytic theory for better understanding of visible light photocatalytic reactions and rational design of highly active photocatalysts.

  5. Structurally Oriented Nano-Sheets in Co Thin Films: Changing Their Anisotropic Physical Properties by Thermally-Induced Relaxation

    Directory of Open Access Journals (Sweden)

    José Vergara

    2017-12-01

    Full Text Available We show how nanocrystalline Co films formed by separated oblique nano-sheets display anisotropy in their resistivity, magnetization process, surface nano-morphology and optical transmission. After performing a heat treatment at 270 °C, these anisotropies decrease. This loss has been monitored measuring the resistivity as a function of temperature. The resistivity measured parallel to the direction of the nano-sheets has been constant up to 270 °C, but it decreases when measured perpendicular to the nano-sheets. This suggests the existence of a structural relaxation, which produces the change of the Co nano-sheets during annealing. The changes in the nano-morphology and the local chemical composition of the films at the nanoscale after heating above 270 °C have been analysed by scanning transmission electron microscopy (STEM. Thus, an approach and coalescence of the nano-sheets have been directly visualized. The spectrum of activation energies of this structural relaxation has indicated that the coalescence of the nano-sheets has taken place between 1.2 and 1.7 eV. In addition, an increase in the size of the nano-crystals has occurred in the samples annealed at 400 °C. This study may be relevant for the application in devices working, for example, in the GHz range and to achieve the retention of the anisotropy of these films at higher temperatures.

  6. Influence of heat-treatment on lithium ion anode properties of mesoporous carbons with nanosheet-like walls

    Energy Technology Data Exchange (ETDEWEB)

    Zeng, Fanyan [College of Chemistry and Chemical Engineering, Hunan University, Changsha 410082 (China); Hou, Zhaohui, E-mail: zhqh96@163.com [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); Ge, Chongyong; Cao, Jianguo [College of Chemistry and Chemical Engineering, Hunan University, Changsha 410082 (China); Kuang, Yafei, E-mail: yafeik@163.com [College of Chemistry and Chemical Engineering, Hunan University, Changsha 410082 (China)

    2012-08-15

    Highlights: ► Mesoporous carbons possess unique nanosheet-like pore walls which can be changed by heat treatment. ► Lithium ion anode properties of mesoporous carbons could be influenced by the nanosheet-like walls. ► Mesoporous carbons with nanosheet-like walls exhibit enhanced electrochemical properties LIBs. -- Abstract: Mesoporous carbons (MCs) with nanosheet-like walls have been prepared as electrodes for lithium-ion batteries by a simple one-step infiltrating method under the action of capillary flow. The influence of heat treatment temperature on the surface topography, pore/phase structure and anode performances of as-prepared materials has been investigated. The results reveal that melted liquid-crystal polycyclic aromatic hydrocarbons could be anchored on liquid/silica interfaces by molecule engineering. After carbonization, the nanosheets are formed as the pore walls of MCs and are perpendicular to the long axis of pores. The anode properties demonstrate that C-1200 displays higher reversible capacitance than those treated in higher temperature. The rate performances of C-1200 and C-1800 are similar and more excellent than that of C-2400. These improved lithium ion anode properties could be attributed to the nanosheet-like walls of MCs which can be influenced by the heat treatment temperature.

  7. Morphology-controlled graphene nanosheets as anode material for lithium-ion batteries

    International Nuclear Information System (INIS)

    Ahn, Wook; Song, Hoon Sub; Park, Sang-Hoon; Kim, Kwang-Bum; Shin, Kyoung-Hee; Lim, Sung Nam; Yeon, Sun-Hwa

    2014-01-01

    Highlights: • Graphene nanosheets was manufactured using a simple modified version of a previously improved Hummers method. • The wrinkle-free graphene was easily manufactured from prepared graphene by post-process treatment. • Morphology-controlled graphene nanosheets showed excellent discharge performance. • Morphology-controlled graphene has the potential to be easily applied to graphene-wrapped composite. - Abstract: Morphology-controlled graphene nanosheets can be easily synthesized as anode material for application in high-capacity lithium-ion batteries. A modified version of an improved method for higher degree of oxidation of graphite oxide (GO) has been developed and characterized. X-ray diffraction analysis shows that GO prepared using this method has a higher degree of oxidation than that of using the improved method. The interlayer d-spacing increases from 0.87 nm (using the improved method) to 0.92 nm (using the modified-improved method). Also, it is confirmed by XPS analysis that the O/C ratio in GO increases from 2.51 (improved method) to 8.27 (modified-improved method). It is hypothesized that GO, which has a higher degree of oxidation, is more reducible to graphene. The more reduced graphene has a larger amount of free π-bonds and fewer layers, and it can be easily altered to morphology-controlled graphene. Graphene nanosheets prepared using the modified-improved method exhibits discharge capacities of 1079 mAh g −1 (at a constant current of 40 mA g −1 ) and 1002 mAh g −1 after 50 cycles. The capacity retention of the synthesized graphene nanosheets is 1070 mAh g −1 at a current of 40 mA g −1 after the rate capability test, and their rate capability is 463 mAh g −1 at a current of 400 mA g −1 . The morphology-controlled graphene nanosheets prepared by the modified-improved method shows better discharge performance compared to graphene prepared by the improved method

  8. Carbon monoxide adsorption studies on Ru:Mn bimetallic catalysts supported on alumina, silica and titania supported for the determination of metal surface area overview

    International Nuclear Information System (INIS)

    Hussain, S.T.

    1992-01-01

    Supported Ru: Mn bimetallic samples were studied using CO-chemisorption on alumina, silica and titania supports for the determination of active metal site/metal surface area. The data indicates the presence of Mn on the surface of Ru. With the increase of Mn loadings a decrease in the CO adsorption occurred indicating that presence of Mn masks the active sites responsible for Co-adsorption. On the titania supported system reduced at high and low temperature the CO-chemisorption data suggest the unusual behaviour. This behaviour is possibly caused due to creation of new active surface sites. (author)

  9. Recovery evaluation of organophosphorus pesticides from bee pollen by matrix solid-phase dispersion extraction using sorbents based on silica and titania

    International Nuclear Information System (INIS)

    Torres-Perea, C; Muñoz-Rodríguez, D; Carrera-Figueiras, C; Medina-Peralta, S; Moguel-Ordóñez, Y B

    2013-01-01

    This work focused on the evaluation of the recovery of organophosphorus pesticides from bee pollen after matrix solid phase-dispersion extraction (MSPD). Materials based on silica, titania and titania modified with polivylnylimidazole or polyestirene were used as adsorbents for the extraction of pesticides. Small amounts of fortified pollen (0.1 g, at 1 micro-g/g of pesticides), adsorbent (0.4 g) and solvent elution (1 mL de acetonitrile – ACN) were used in the extractions. For recovery evaluation, pollen extracts were analyzed by gas chromatography coupled with mass spectrometry.

  10. Improvement in antibacterial properties of Ti by electrodeposition of biomimetic Ca-P apatite coat on anodized titania

    Energy Technology Data Exchange (ETDEWEB)

    Gad El-Rab, Sanaa M.F. [Biotechnology Department, Faculty of Science, Taif University, Taif (Saudi Arabia); Botany Department, Faculty of Science, Asuit University, Asuit (Egypt); Fadl-allah, Sahar A., E-mail: Sahar.fadlallah@yahoo.com [Materials and Corrosion Lab (MCL), Faculty of Science, Taif University, Taif (Saudi Arabia); Chemistry Department, Faculty of Science, Cairo University, Cairo (Egypt); Montser, A.A. [Materials and Corrosion Lab (MCL), Faculty of Science, Taif University, Taif (Saudi Arabia); Chemistry Department, Faculty of Science, South-Valley University (Egypt)

    2012-11-15

    Highlights: Black-Right-Pointing-Pointer Ca-P coating on titania titanium surface was directly fabricated successfully by electrochemical deposition. Black-Right-Pointing-Pointer Treatment the titanium surface by TiO{sub 2} could improve the adhesion strength between the Ca-P coating and the surface. Black-Right-Pointing-Pointer Anodization treatment in phosphoric acid is benefit to inhibit the oral bacteria. Black-Right-Pointing-Pointer According to the electrochemical corrosion test, corrosion resistance of Ti was improved by both anodization and electrodeposition of the Ca-P/titania coating. Black-Right-Pointing-Pointer Ca-P/titania sample is believed to be a functional biomaterial which combines antibacterial activity and good corrosion resistance in bioenvironment. - Abstract: Titanium metal (Ti) with antibacterial function was successfully developed in the present study by electrodeposition of biomimetic Ca-P coat in simple supersaturated calcium and phosphate solution (SCPS). The electrochemical behavior and corrosion resistance of Ca-P deposited on anodized titanium (AT) have been investigated in SCPS by using electrochemical impedance spectroscopy (EIS). The plate-counting method was used to evaluate the antibacterial performance against Staphylococcus aureus (ATCC6538). In vitro antibacterial activity study indicated a significantly reduced number of bacteria S. aureus on Ca-P/AT plate surface when compared with that on Ti or AT surfaces and the corresponding antibacterial mechanism is discussed. The morphology and chemical structure of different titanium samples were systematically investigated by scanning electron microscope (SEM) and energy dispersive X-ray analysis (EDX). The study confirmed that the antibacterial properties of the samples were related to chemical composition of sample surface.

  11. Series-Interconnected Plastic Dye-Sensitized Solar Cells Prepared by Low- Temperature Binder-Free Titania Paste

    Directory of Open Access Journals (Sweden)

    Erlyta Septa Rosa

    2014-10-01

    Full Text Available The aim of this research is to study dye-sensitized solar cells (DSSC. This was implemented on a flexible polyethylene terephthalate (PET substrate using a mixture of transparent and scattered mesoporous anatase-titania as the electron transport layer for the photoelectrode. This mixture of anatase titania performed a dual function of light scattering and efficient dye absorption. In this study, a porous nano-TiO2 film was prepared on indium tin oxide (ITO coated polyethylene terephthalate (PET by using a binder-free titania paste; on it, a DSSC was fabricated. The paste which contained a mixture of TiO2 nanoparticles, acid chloride, and ethanol was printed on two patterns of 1x6 cm2 active areas followed by sintered at 120 ºC to form TiO2 films. A commercial dye, N719, was adsorbed on the surface of TiO2 films and assembled to two platinized conductive plastic patterns to form a counter electrode and thus a sandwich-type dye cell. Finally, a solution of KI/I2 electrolytes was injected into the cell in which a couple of sandwich-type dye cells with an active area of 6 cm2 for each cell were series interconnected with a z-type interconnection between the photoelectrode of one cell and the counter electrode of another cell. The cell performance was characterized by employing simulated solar light at an intensity of 50 mW/cm2. The results showed interconnected cells generating a short-circuit photocurrent density of 2.34 mA/cm2, an open-circuit voltage of 1.10 volt, and overall 0.172% power conversion efficiency.

  12. Gadolinium oxide decorated multiwalled carbon nanotube/tridoped titania nanocomposites for improved dye degradation under simulated solar light irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Mamba, Gcina [Department of Applied Chemistry, University of Johannesburg, Faculty of Science, P.O. Box 17011, Doornfontein 2028 (South Africa); Nanotechnology and Water Sustainability Research Unit, College of Engineering, Science and Technology, University of South Africa Florida Science Campus, 1709 Florida (South Africa); Mbianda, Xavier Yangkou [Department of Applied Chemistry, University of Johannesburg, Faculty of Science, P.O. Box 17011, Doornfontein 2028 (South Africa); Mishra, Ajay Kumar, E-mail: mishrak@unisa.ac.za [Nanotechnology and Water Sustainability Research Unit, College of Engineering, Science and Technology, University of South Africa Florida Science Campus, 1709 Florida (South Africa)

    2016-03-15

    Graphical abstract: Illustration of the collaborative effect between MWCNT-Gd and Gd,N,S-TiO{sub 2} towards degradation of AB 74. - Highlights: • MWCNT-Gd/tridoped titania was successfully prepared via a sol-gel method. • XPS revealed the presence of Ti, C, O, S, N and Gd in MWCNT-Gd/Gd,N,S-TiO{sub 2}. • MWCNT-Gd/Gd,N,S-TiO{sub 2} displayed 100% degradation of acid blue 74 in 150 min. • Over 60% TOC removal by MWCNT-Gd/Gd,N,S-TiO{sub 2}. - Abstract: Neodymium/gadolinium/europium, nitrogen and sulphur tridoped titania (Nd/Gd/Eu, N,S-TiO{sub 2}) was hybridised with pre-synthesised gadolinium oxide decorated multiwalled carbon nanotubes (MWCNT-Gd) using a sol–gel method. Subsequent to drying and calcination, composite photocatalysts: MWCNT-Gd/Nd,N,S-TiO{sub 2}, MWCNT-Gd/Gd,N,S-TiO{sub 2} and MWCNT-Gd/Eu,N,S-TiO{sub 2}, were obtained and characterised using TEM, SEM-EDX, UV–vis, XPS, XRD and FT-IR. Acid blue 74 (AB74) was used as a model dye to investigate the photocatalytic degradation properties of the prepared materials under simulated solar light irradiation. Coupling the different tridoped titania with MWCNT-Gd enhanced their activity compared to MWCNT/TiO{sub 2}, MWCNT-Gd/TiO{sub 2} and MWCNT/Gd,N,S-TiO{sub 2}. MWCNT-Gd/Gd,N,S-TiO{sub 2} showed the highest activity towards AB74 degradation reaching 100% decolourisation after 150 min of irradiation. Total organic carbon analysis revealed that over 50% of the AB74 molecules were completely mineralised after 180 min of irradiation in the presence of MWCNT-Gd/Gd,N,S-TiO{sub 2}.

  13. Generalized colloidal synthesis of high-quality, two-dimensional cesium lead halide perovskite nanosheets and their applications in photodetectors

    Science.gov (United States)

    Lv, Longfei; Xu, Yibing; Fang, Hehai; Luo, Wenjin; Xu, Fangjie; Liu, Limin; Wang, Biwei; Zhang, Xianfeng; Yang, Dong; Hu, Weida; Dong, Angang

    2016-07-01

    All-inorganic cesium lead halide perovskite (CsPbX3, X = Cl, Br, and I) nanocrystals (NCs) are emerging as an important class of semiconductor materials with superior photophysical properties and wide potential applications in optoelectronic devices. So far, only a few studies have been conducted to control the shape and geometry of CsPbX3 NCs. Here we report a general approach to directly synthesize two-dimensional (2D) CsPbX3 perovskite and mixed perovskite nanosheets with uniform and ultrathin thicknesses down to a few monolayers. The key to the high-yield synthesis of perovskite nanosheets is the development of a new Cs-oleate precursor. The as-synthesized CsPbX3 nanosheets exhibit bright photoluminescence with broad wavelength tunability by composition modulation. The excellent optoelectronic properties of CsPbX3 nanosheets combined with their unique 2D geometry and large lateral dimensions make them ideal building blocks for building functional devices. To demonstrate their potential applications in optoelectronics, photodetectors based on CsPbBr3 nanosheets are fabricated, which exhibit high on/off ratios with a fast response time.All-inorganic cesium lead halide perovskite (CsPbX3, X = Cl, Br, and I) nanocrystals (NCs) are emerging as an important class of semiconductor materials with superior photophysical properties and wide potential applications in optoelectronic devices. So far, only a few studies have been conducted to control the shape and geometry of CsPbX3 NCs. Here we report a general approach to directly synthesize two-dimensional (2D) CsPbX3 perovskite and mixed perovskite nanosheets with uniform and ultrathin thicknesses down to a few monolayers. The key to the high-yield synthesis of perovskite nanosheets is the development of a new Cs-oleate precursor. The as-synthesized CsPbX3 nanosheets exhibit bright photoluminescence with broad wavelength tunability by composition modulation. The excellent optoelectronic properties of CsPbX3 nanosheets

  14. Polymeric Electrolyte Membrane Photoelectrochemical (PEM-PEC Cell with a Web of Titania Nanotube Arrays as Photoanode and Gaseous Reactants

    Directory of Open Access Journals (Sweden)

    Tsampas M.N.

    2017-01-01

    Photoanodes of titania nanotube arrays, TNTAs, were developed, for the first time, on a Ti-web of microfiber substrates, by electrochemical anodization. The performance of TNTAs/Ti-web photoanodes were evaluated in both gaseous and liquid reactants. Due to the presence of reliable reference electrode in gas phase direct comparison of the results was possible. Gas phase operation with He or Air as carrier gases and only 2.5% of water content exhibits very promising photoefficiency in comparison with conventional PEC cells.

  15. Copper supported on nanostructured mesoporous ceria-titania composites as catalysts for sustainable environmental protection: Effect of support composition

    Czech Academy of Sciences Publication Activity Database

    Issa, G. S.; Tsoncheva, T.; Mileva, A.; Dimitrov, M.D.; Kovacheva, D.; Henych, Jiří; Štengl, Václav

    2017-01-01

    Roč. 49, SI D (2017), s. 55-62 ISSN 0324-1130 Grant - others:AV ČR(CZ) BAS-17-13 Program:Bilaterální spolupráce Institutional support: RVO:61388980 Keywords : Mesoporous nanostructured ceria-titania doped with copper * template-assisted hydrothermal synthesis * ethyl acetate oxidation * methanol decomposition Subject RIV: CA - Inorganic Chemistry OBOR OECD: Inorganic and nuclear chemistry Impact factor: 0.238, year: 2016 http://www.bcc.bas.bg/BCC_Volumes/Volume_49_Special_D_2017/BCC2017-49-SE-D-055-062.pdf

  16. Metatitanic acid pseudomorphs after titanyl sulfates: nanostructured sorbents and precursors for crystalline titania with desired particle size and shape

    Czech Academy of Sciences Publication Activity Database

    Klementová, Mariana; Motlochová, Monika; Boháček, Jaroslav; Kupčík, Jaroslav; Palatinus, Lukáš; Pližingrová, Eva; Szatmáry, L.; Šubrt, Jan

    2017-01-01

    Roč. 17, č. 12 (2017), s. 6762-6769 ISSN 1528-7483 R&D Projects: GA TA ČR(CZ) TH02020110; GA MŠk(CZ) LM2015073 Institutional support: RVO:61388980 ; RVO:68378271 Keywords : metatitanic acid * titania * pseudomorph * titanyl sulfate dihydrate structure * morphology control * sorption * radionuclides Subject RIV: CA - Inorganic Chemistry; BM - Solid Matter Physics ; Magnetism (FZU-D) OBOR OECD: Inorganic and nuclear chemistry; Condensed matter physics (including formerly solid state physics, supercond.) (FZU-D) Impact factor: 4.055, year: 2016

  17. Fabrication of a three-dimensional photonic band-gap crystal of air-spheres in a titania matrix

    Science.gov (United States)

    Diop, M.; Maurin, G.; Tork, Amir; Lessard, Roger A.

    2003-02-01

    A three-dimensional (3D) colloidal crystal have been grown from an aqueous colloidal solution of highly monodisperse submicrometer-sized polystyrene spheres using a self-assembly processing technique. The electromagnetic waves diffracted by this crystal can interfere and give rise to a photonic band-gap. However, due to the low refractive index contrast within this material the band-gap is incomplete. By filling the voids between the spheres of the colloidal crystal with titania and removing the polystyrene beads by sublimation, we obtained an inverse-opal structure with an increased refractive index contrast showing strong opalescence.

  18. An artificial muscle model unit based on inorganic nanosheet sliding by photochemical reaction.

    Science.gov (United States)

    Nabetani, Yu; Takamura, Hazuki; Hayasaka, Yuika; Sasamoto, Shin; Tanamura, Yoshihiko; Shimada, Tetsuya; Masui, Dai; Takagi, Shinsuke; Tachibana, Hiroshi; Tong, Zhiwei; Inoue, Haruo

    2013-04-21

    From the viewpoint of developing photoresponsive supramolecular systems in microenvironments to exhibit more sophisticated photo-functions even at the macroscopic level, inorganic/organic hybrid compounds based on clay or niobate nanosheets as the microenvironments were prepared, characterized, and examined for their photoreactions. We show here a novel type of artificial muscle model unit having much similarity with that in natural muscle fibrils. Upon photoirradiation, the organic/inorganic hybrid nanosheets reversibly slide horizontally on a giant scale, and the interlayer spaces in the layered hybrid structure shrink and expand vertically. In particular, our layered hybrid molecular system exhibits a macroscopic morphological change on a giant scale (~1500 nm) compared with the molecular size of ~1 nm, based on a reversible sliding mechanism.

  19. Layered-Double-Hydroxide Nanosheets as Efficient Visible-Light-Driven Photocatalysts for Dinitrogen Fixation.

    Science.gov (United States)

    Zhao, Yufei; Zhao, Yunxuan; Waterhouse, Geoffrey I N; Zheng, Lirong; Cao, Xingzong; Teng, Fei; Wu, Li-Zhu; Tung, Chen-Ho; O'Hare, Dermot; Zhang, Tierui

    2017-11-01

    Semiconductor photocatalysis attracts widespread interest in water splitting, CO 2 reduction, and N 2 fixation. N 2 reduction to NH 3 is essential to the chemical industry and to the Earth's nitrogen cycle. Industrially, NH 3 is synthesized by the Haber-Bosch process under extreme conditions (400-500 °C, 200-250 bar), stimulating research into the development of sustainable technologies for NH 3 production. Herein, this study demonstrates that ultrathin layered-double-hydroxide (LDH) photocatalysts, in particular CuCr-LDH nanosheets, possess remarkable photocatalytic activity for the photoreduction of N 2 to NH 3 in water at 25 °C under visible-light irradiation. The excellent activity can be attributed to the severely distorted structure and compressive strain in the LDH nanosheets, which significantly enhances N 2 chemisorption and thereby promotes NH 3 formation. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  20. Enhancing the mechanical properties of BN nanosheet-polymer composites by uniaxial drawing

    Science.gov (United States)

    Jan, Rahim; May, Peter; Bell, Alan P.; Habib, Amir; Khan, Umar; Coleman, Jonathan N.

    2014-04-01

    We have used liquid exfoliation of hexagonal Boron-Nitride (BN) to prepare composites of BN nanosheets of three different sizes in polyvinylchloride matrices. These composites show low levels of reinforcement, consistent with poor alignment of the nanosheets as-described by a modified version of Halpin-Tsai theory. However, drawing of the composites to 300% strain results in a considerable increase in mechanical properties with the maximum composite modulus and strength both ~×3 higher than that of the pristine polymer. In addition, the rate of increase of modulus with BN volume fraction was up to 3-fold larger than for the unstrained composites. This is higher than can be explained by drawing-induced alignment using Halpin-Tsai theory. However, the data was consistent with a combination of alignment and strain-induced de-aggregation of BN multilayers.