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Sample records for fe2o3 thin films

  1. Visible light catalysis of rhodamine B using nanostructured Fe(2)O(3), TiO(2) and TiO(2)/Fe(2)O(3) thin films.

    Science.gov (United States)

    Mahadik, M A; Shinde, S S; Mohite, V S; Kumbhar, S S; Moholkar, A V; Rajpure, K Y; Ganesan, V; Nayak, J; Barman, S R; Bhosale, C H

    2014-04-05

    The Fe(2)O(3), TiO(2) and TiO(2)/Fe(2)O(3) composite films are deposited using spray pyrolysis method onto glass and FTO coated substrates. The structural, morphological, optical and photocatalytic properties of Fe(2)O(3), TiO(2) and TiO(2)/Fe(2)O(3) thin films are studied. XRD analysis confirms that films are polycrystalline with rhombohedral and tetragonal crystal structures for Fe2O3 and TiO(2) respectively. The photocatalytic activity was tested for the degradation of Rhrodamine B (Rh B) in aqueous medium. The rate constant (-k) was evaluated as a function of the initial concentration of species. Substantial reduction in concentrations of organic species was observed from COD and TOC analysis. Photocatalytic degradation effect is relatively higher in case of the TiO(2)/Fe(2)O(3) than TiO(2) and Fe(2)O(3) thin film photoelectrodes in the degradation of Rh B and 98% removal efficiency of Rh B is obtained after 20min. The photocatalytic experimental results indicate that TiO(2)/α-Fe(2)O(3) photoelectrode is promising material for removing of water pollutants.

  2. Spin Seebeck effect in insulating epitaxial γ-Fe2O3 thin films

    Science.gov (United States)

    Jiménez-Cavero, P.; Lucas, I.; Anadón, A.; Ramos, R.; Niizeki, T.; Aguirre, M. H.; Algarabel, P. A.; Uchida, K.; Ibarra, M. R.; Saitoh, E.; Morellón, L.

    2017-02-01

    We report the fabrication of high crystal quality epitaxial thin films of maghemite (γ-Fe2O3), a classic ferrimagnetic insulating iron oxide. Spin Seebeck effect (SSE) measurements in γ-Fe2O3/Pt bilayers as a function of sample preparation conditions and temperature yield a SSE coefficient of 0.5(1) μV/K at room temperature. Dependence on temperature allows us to estimate the magnon diffusion length in maghemite to be in the range of tens of nanometers, in good agreement with that of conducting iron oxide magnetite (Fe3O4), establishing the relevance of spin currents of magnonic origin in magnetic iron oxides.

  3. Spin Seebeck effect in insulating epitaxial γ−Fe2O3 thin films

    Directory of Open Access Journals (Sweden)

    P. Jiménez-Cavero

    2017-02-01

    Full Text Available We report the fabrication of high crystal quality epitaxial thin films of maghemite (γ−Fe2O3, a classic ferrimagnetic insulating iron oxide. Spin Seebeck effect (SSE measurements in γ−Fe2O3/Pt bilayers as a function of sample preparation conditions and temperature yield a SSE coefficient of 0.5(1 μV/K at room temperature. Dependence on temperature allows us to estimate the magnon diffusion length in maghemite to be in the range of tens of nanometers, in good agreement with that of conducting iron oxide magnetite (Fe3O4, establishing the relevance of spin currents of magnonic origin in magnetic iron oxides.

  4. Thickness dependent activity of nanostructured TiO 2/α-Fe 2O 3 photocatalyst thin films

    Science.gov (United States)

    Akhavan, O.

    2010-12-01

    The effect of thickness of TiO 2 coating on synergistic photocatalytic activity of TiO 2 (anatase)/α-Fe 2O 3/glass thin films as photocatalysts for degradation of Escherichia coli bacteria in a low-concentration H 2O 2 solution and under visible light irradiation was investigated. Nanograined α-Fe 2O 3 films with optical band-gap of 2.06 eV were fabricated by post-annealing of thermal evaporated iron oxide thin films at 400 °C in air. Increase in thickness of the Fe 2O 3 thin film (here, up to 200 nm) resulted in a slight reduction of the optical band-gap energy and an increase in the photoinactivation of the bacteria. Sol-gel TiO 2 coatings were deposited on the α-Fe 2O 3 (200 nm)/glass films, and then, they were annealed at 400 °C in air for crystallization of the TiO 2 and formation of TiO 2/Fe 2O 3 heterojunction. For the TiO 2 coatings with thicknesses ≤50 nm, the antibacterial activity of the TiO 2/α-Fe 2O 3 (200 nm) was found to be better than the activity of the bare α-Fe 2O 3 film. The optimum thickness of the TiO 2 coating was found to be 10 nm, resulting in about 70 and 250% improvement in visible light photo-induced antibacterial activity of the TiO 2/α-Fe 2O 3 thin film as compared to the corresponding activity of the bare α-Fe 2O 3 and TiO 2 thin films, respectively. The improvement in the photoinactivation of bacteria on surface of TiO 2/α-Fe 2O 3 was assigned to formation of Ti-O-Fe bond at the interface.

  5. Pinning enhancement in MgB2 superconducting thin films by magnetic nanoparticles of Fe2O3

    Indian Academy of Sciences (India)

    E Taylan Koparan; A Surdu; K Kizilkaya; A Sidorenko; E Yanmaz

    2013-11-01

    MgB2 thin films were fabricated on -plane Al2O3 (1$\\bar{1}$02) substrates. First, deposition of boron was performed by rf magnetron sputtering on Al2O3 substrates and followed by a post-deposition annealing at 850 °C in magnesium vapour. In order to investigate the effect of Fe2O3 nanoparticles on the structural and magnetic properties of films, MgB2 films were coated with different concentrations of Fe2O3 nanoparticles by spin coating process. The magnetic field dependence of the critical current density c was calculated from the M–H loops and magnetic field dependence of the pinning force density, p(), was investigated for the films containing different concentrations of Fe2O3 nanoparticles. The critical current densities, c, in 3Tmagnetic field at 5 K were found to be around 2.7 × 104 A/cm2, 4.3 × 104 A/cm2, 1.3 × 105 A/cm2 and 5.2 × 104 A/cm2 for films with concentrations of 0, 25, 50 and 100% Fe2O3, respectively. It was found that the films coated with Fe2O3 nanoparticles have significantly enhanced the critical current density. It can be noted that especially the films coated by Fe2O3 became stronger in the magnetic field and at higher temperatures. It was believed that coated films indicated the presence of artificial pinning centres created by Fe2O3 nanoparticles. The results of AFM indicate that surface roughness of the films significantly decreased with increase in concentration of coating material.

  6. Oxidative degradation of industrial wastewater using spray deposited TiO2/Au:Fe2O3 bilayered thin films.

    Science.gov (United States)

    Mahadik, M A; Shinde, S S; Pathan, H M; Rajpure, K Y; Bhosale, C H

    2014-12-01

    The Fe2O3, Au:Fe2O3, TiO2/Fe2O3 and TiO2/Au:Fe2O3 thin films are successfully prepared by the spray pyrolysis technique at an optimised substrate temperature of 400 °C and 470 °C, respectively onto amorphous and F:SnO2 coated glass substrates. The effect of TiO2 layer onto photoelectrochemical (PEC), structural, optical and morphological properties of Fe2O3, Au:Fe2O3, TiO2/Fe2O3 and TiO2/Au:Fe2O3 thin films is studied. The PEC characterization shows that, maximum values of short circuit current (Isc) and open circuit voltage (Voc) are (Isc = 185 μA and Voc = 450 mV) are at 38 nm thickness of TiO2. Deposited films are polycrystalline with a rhombohedral and anatase crystal structure having (104) preferred orientation. SEM and AFM images show deposited thin films are compact and uniform with seed like grains. The photocatalytic activities of the large surface area (64 cm(2)) TiO2/Au:Fe2O3 thin film photocatalysts were evaluated by photoelectrocatalytic degradation of industrial wastewater under sunlight light irradiation. The results show that the TiO2/Au:Fe2O3 thin film photocatalyst exhibited about 87% and 94% degradation of pollutant in sugarcane and textile industrial wastewater, respectively. The significant reduction in COD and BOD values from 95 mg/L to 13 mg/L and 75 mg/L to 11 mg/L, respectively was also observed.

  7. Physical properties of hematite α-Fe2O3 thin films: application to photoelectrochemical solar cells

    Institute of Scientific and Technical Information of China (English)

    S. S. Shinde; R. A. Bansode; C. H. Bhosale; K. Y. Rajpure

    2011-01-01

    The physical properties and photoelectrochemical characterization of aluminium doped hematite α-Fe2O3, synthesized by spray pyrolysis, have been investigated in regard to solar energy conversion. Stable Al-doped iron (Ⅲ) oxide thin films synthesized by a spray pyrolysis technique reveals an oxygen deficiency, and the oxide exhibits n-type conductivity confirmed by anodic photocurrent generation. The preparative parameters have been optimized to obtain good quality thin films which are uniform and well adherent to the substrate. The deposited iron oxide thin films show the single hematite phase with polycrystalline rhombohedral crystal structure with crystallite size 20-40 nm. Optical analysis enabled to point out the increase in direct band-gap energy from 2.2 to 2.25 eV with doping concentration which is attributed to a blue shift. The dielectric constant and dielectric loss are studied as a function of frequency. To understand the conduction mechanism in the films, AC conductivity is measured. The conduction occurs by small polaron hopping through mixed valences Fe2+/3+ with an electron mobility 300 K of 1.08 cm2/(V.s). The α-Fe2O3 exhibits long term chemical stability in neutral solution and has been characterized photoelectrochemically to assess its activity as a photoanode for various electrolytes using white light to obtain Ⅰ- characteristics. The Al-doped hematite exhibited a higher photocurrent response when compared with undoped films achieving a power conversion efficiency of 2.37% at 10 at% Al:Fe2O3 thin films along with fill factor 0.38 in NaOH electrolyte. The flat band potential Vfb (-0.87 VSCE) is determined by extrapolating the linear part to C-2 = 0 and the slope of the Mott-Schottky plot.

  8. Characterization and antibacterial activity of nanocrystalline Mn doped Fe2O3 thin films grown by successive ionic layer adsorption and reaction method

    OpenAIRE

    2016-01-01

    Successive ionic layer adsorption and reaction (SILAR) method have been successfully employed to grow nanocrystalline Mn doped α-Fe2O3 thin films onto glass substrates. The structural analysis revealed that, the films are nanocrystalline in nature with rhombohedral structure. The optical studies showed that α-Fe2O3 thin film exhibits 3.02 eV band gap energy and it decreases to 2.95 eV as the Mn doping percentage in it was increased from 0 to 8 wt.%. The SILAR grown α-Fe2O3 film exhibits antib...

  9. In situ RHEED and XPS studies of epitaxial thin alpha-Fe2O3 films on sapphire

    NARCIS (Netherlands)

    Fujii, T; Alders, D; Voogt, FC; Hibma, T; Thole, BT; Sawatzky, GA

    1996-01-01

    In situ RHEED and XPS measurements of epitaxial alpha-Fe2O3(0001) films are reported as a function of the number of deposited monolayers. The films were prepared on alpha-Al2O3(0001) substrates by MBE. The RHEED patterns suggest that layer-by-layer growth of alpha-Fe2O3(0001) occurs for the first fe

  10. Inverse opal structured α-Fe2O3 on graphene thin films: enhanced photo-assisted water splitting

    Science.gov (United States)

    Zhang, Kan; Shi, Xinjian; Kim, Jung Kyu; Lee, Jae Sung; Park, Jong Hyeok

    2013-02-01

    A graphene interlayer was successfully inserted into inverse opaline hematite (α-Fe2O3) photoanodes for solar water splitting using the template assisted electrodeposition method. Finding the optimal thermal annealing temperature is crucial for the successful attainment of the inverse opaline hematite nanostructure on a graphene thin film. This is because an appropriate temperature is required to convert pre-deposited Fe0 into hematite with optimum crystalline structure and to simultaneously remove the soft polystyrene template without thermal degradation of the graphene film on a transparent conductive substrate. Different from the conventional strategies based on graphene-semiconductor systems, this novel mechanism has been proposed whereby the graphene interlayer can act as both an electron transfer layer and an electrolyte blocking barrier, by which it not only reduces the charge recombination at the substrate-electrolyte interface but also helps electron transportation from α-Fe2O3 to the substrate of the photoanode. Therefore, both photocurrent density and incident photon-to-current efficiency (IPCE) have been remarkably improved, which are several times higher than those of the pure inverse opaline hematite photoanode.A graphene interlayer was successfully inserted into inverse opaline hematite (α-Fe2O3) photoanodes for solar water splitting using the template assisted electrodeposition method. Finding the optimal thermal annealing temperature is crucial for the successful attainment of the inverse opaline hematite nanostructure on a graphene thin film. This is because an appropriate temperature is required to convert pre-deposited Fe0 into hematite with optimum crystalline structure and to simultaneously remove the soft polystyrene template without thermal degradation of the graphene film on a transparent conductive substrate. Different from the conventional strategies based on graphene-semiconductor systems, this novel mechanism has been proposed

  11. Characterization and antibacterial activity of nanocrystalline Mn doped Fe2O3 thin films grown by successive ionic layer adsorption and reaction method

    Directory of Open Access Journals (Sweden)

    M.R. Belkhedkar

    2016-10-01

    Full Text Available Successive ionic layer adsorption and reaction (SILAR method have been successfully employed to grow nanocrystalline Mn doped α-Fe2O3 thin films onto glass substrates. The structural analysis revealed that, the films are nanocrystalline in nature with rhombohedral structure. The optical studies showed that α-Fe2O3 thin film exhibits 3.02 eV band gap energy and it decreases to 2.95 eV as the Mn doping percentage in it was increased from 0 to 8 wt.%. The SILAR grown α-Fe2O3 film exhibits antibacterial character against Staphylococcus aureus bacteria and it increases remarkably with Mn doping.

  12. Photoelectrochemical Characterization of Sprayed α-Fe2O3 Thin Films: Influence of Si Doping and SnO2 Interfacial Layer

    Directory of Open Access Journals (Sweden)

    Yongqi Liang

    2008-01-01

    Full Text Available α-Fe2O3 thin film photoanodes for solar water splitting were prepared by spray pyrolysis of Fe(AcAc3. The donor density in the Fe2O3 films could be tuned between 1017–1020 cm-3 by doping with silicon. By depositing a 5 nm SnO2 interfacial layer between the Fe2O3 films and the transparent conducting substrates, both the reproducibility and the photocurrent can be enhanced. The effects of Si doping and the presence of the SnO2 interfacial layer were systematically studied. The highest photoresponse is obtained for Fe2O3 doped with 0.2% Si, resulting in a photocurrent of 0.37 mA/cm2 at 1.23 VRHE in a 1.0 M KOH solution under 80 mW/cm2 AM1.5 illumination.

  13. Translucent thin film Fe2O3 photoanodes for efficient water splitting by sunlight: nanostructure-directing effect of Si-doping.

    Science.gov (United States)

    Cesar, Ilkay; Kay, Andreas; Gonzalez Martinez, José A; Grätzel, Michael

    2006-04-12

    Thin, silicon-doped nanocrystalline alpha-Fe2O3 films have been deposited on F-doped SnO2 substrates by ultrasonic spray pyrolysis and chemical vapor deposition at atmospheric pressure. The photocatalytic activity of these films with regard to photoelectrochemical water oxidation was measured at pH 13.6 under simulated AM 1.5 global sunlight. The photoanodes prepared by USP and APCVD gave 1.17 and 1.45 mA/cm2, respectively, at 1.23 V vs RHE. The morphology of the alpha-Fe2O3 was strongly influenced by the silicon doping, decreasing the feature size of the mesoscopic film. The silicon-doped alpha-Fe2O3 nano-leaflets show a preferred orientation with the (001) basal plane normal to the substrate. The best performing photoanode would yield a solar-to-chemical conversion efficiency of 2.1% in a tandem device using two dye-sensitized solar cells in series.

  14. Low-cost flexible supercapacitors with high-energy density based on nanostructured MnO2 and Fe2O3 thin films directly fabricated onto stainless steel

    National Research Council Canada - National Science Library

    Gund, Girish S; Dubal, Deepak P; Chodankar, Nilesh R; Cho, Jun Y; Gomez-Romero, Pedro; Park, Chan; Lokhande, Chandrakant D

    2015-01-01

    ...) methods have been employed in order to prepare manganese oxide (MnO2) and iron oxide (Fe2O3) thin films, respectively with the fine optimized nanostructures on highly flexible stainless steel sheet...

  15. Fabrication of Thin Films of α-Fe2O3 via Atomic Layer Deposition Using Iron Bisamidinate and Water under Mild Growth Conditions.

    Science.gov (United States)

    Avila, Jason R; Kim, Dong Wook; Rimoldi, Martino; Farha, Omar K; Hupp, Joseph T

    2015-08-01

    Atomic layer deposition (ALD) has been shown to be an excellent method for depositing thin films of iron oxide. With limited iron precursors available, the methods widely used require harsh conditions such as high temperatures and/or the use of oxidants such as ozone or peroxide. This letter aims to show that bis(N,N'-di-t-butylacetamidinato) iron(II) (iron bisamidinate or FeAMD) is an ideal ALD precursor because of its reactivity with water and relative volatility. Using in situ QCM analysis, we show outstanding conformal self-limiting growth of FeOx using FeAMD and water at temperatures lower than 200 °C. By annealing thin films of FeOx at 500 °C, we observe the formation of α-Fe2O3, confirming that we can use FeAMD to fabricate thin films of catalytically promising iron oxide materials using moderate growth conditions.

  16. An innovative concept of use of redox-active electrolyte in asymmetric capacitor based on MWCNTs/MnO2 and Fe2O3 thin films

    Science.gov (United States)

    Chodankar, Nilesh R.; Dubal, Deepak P.; Lokhande, Abhishek C.; Patil, Amar M.; Kim, Jin H.; Lokhande, Chandrakant D.

    2016-12-01

    In present investigation, we have prepared a nanocomposites of highly porous MnO2 spongy balls and multi-walled carbon nanotubes (MWCNTs) in thin film form and tested in novel redox-active electrolyte (K3[Fe(CN)6] doped aqueous Na2SO4) for supercapacitor application. Briefly, MWCNTs were deposited on stainless steel substrate by “dip and dry” method followed by electrodeposition of MnO2 spongy balls. Further, the supercapacitive properties of these hybrid thin films were evaluated in hybrid electrolyte ((K3[Fe(CN)6 doped aqueous Na2SO4). Thus, this is the first proof-of-design where redox-active electrolyte is applied to MWCNTs/MnO2 hybrid thin films. Impressively, the MWCNTs/MnO2 hybrid film showed a significant improvement in electrochemical performance with maximum specific capacitance of 1012 Fg‑1 at 2 mA cm‑2 current density in redox-active electrolyte, which is 1.5-fold higher than that of conventional electrolyte (Na2SO4). Further, asymmetric capacitor based on MWCNTs/MnO2 hybrid film as positive and Fe2O3 thin film as negative electrode was fabricated and tested in redox-active electrolytes. Strikingly, MWCNTs/MnO2//Fe2O3 asymmetric cell showed an excellent supercapacitive performance with maximum specific capacitance of 226 Fg‑1 and specific energy of 54.39 Wh kg‑1 at specific power of 667 Wkg‑1. Strikingly, actual practical demonstration shows lightning of 567 red LEDs suggesting “ready-to sell” product for industries.

  17. Mesoporous α-Fe2O3 thin films synthesized via the sol-gel process for light-driven water oxidation.

    Science.gov (United States)

    Hamd, Wael; Cobo, Saioa; Fize, Jennifer; Baldinozzi, Gianguido; Schwartz, Wilfrid; Reymermier, Maryse; Pereira, Alexandre; Fontecave, Marc; Artero, Vincent; Laberty-Robert, Christel; Sanchez, Clement

    2012-10-14

    This work reports a facile and cost-effective method for synthesizing photoactive α-Fe(2)O(3) films as well as their performances when used as photoanodes for water oxidation. Transparent α-Fe(2)O(3) mesoporous films were fabricated by template-directed sol-gel chemistry coupled with the dip-coating approach, followed by annealing at various temperatures from 350 °C to 750 °C in air. α-Fe(2)O(3) films were characterized by X-ray diffraction, XPS, FE-SEM and electrochemical measurements. The photoelectrochemical performance of α-Fe(2)O(3) photoanodes was characterized and optimized through the deposition of Co-based co-catalysts via different methods (impregnation, electro-deposition and photo-electro-deposition). Interestingly, the resulting hematite films heat-treated at relatively low temperature (500 °C), and therefore devoid of any extrinsic dopant, achieve light-driven water oxidation under near-to-neutral (pH = 8) aqueous conditions after decoration with a Co catalyst. The onset potential is 0.75 V vs. the reversible hydrogen electrode (RHE), thus corresponding to 450 mV light-induced underpotential, although modest photocurrent density values (40 μA cm(-2)) are obtained below 1.23 V vs. RHE. These new materials with a very large interfacial area in contact with the electrolyte and allowing for a high loading of water oxidation catalysts open new avenues for the optimization of photo-electrochemical water splitting.

  18. TiO2 and Fe2O3 films for photoelectrochemical water splitting.

    Science.gov (United States)

    Krysa, Josef; Zlamal, Martin; Kment, Stepan; Brunclikova, Michaela; Hubicka, Zdenek

    2015-01-09

    Titanium oxide (TiO2) and iron oxide (α-Fe2O3) hematite films have potential applications as photoanodes in electrochemical water splitting. In the present work TiO2 and α-Fe2O3 thin films were prepared by two methods, e.g., sol-gel and High Power Impulse Magnetron Sputtering (HiPIMS) and judged on the basis of physical properties such as crystalline structure and surface topography and functional properties such as simulated photoelectrochemical (PEC) water splitting conditions. It was revealed that the HiPIMS method already provides crystalline structures of anatase TiO2 and hematite Fe2O3 during the deposition, whereas to finalize the sol-gel route the as-deposited films must always be annealed to obtain the crystalline phase. Regarding the PEC activity, both TiO2 films show similar photocurrent density, but only when illuminated by UV light. A different situation was observed for hematite films where plasmatic films showed a tenfold enhancement of the stable photocurrent density over the sol-gel hematite films for both UV and visible irradiation. The superior properties of plasmatic film could be explained by ability to address some of the hematite drawbacks by deposition of very thin films (25 nm) consisting of small densely packed particles and by doping with Sn.

  19. TiO2 and Fe2O3 Films for Photoelectrochemical Water Splitting

    Directory of Open Access Journals (Sweden)

    Josef Krysa

    2015-01-01

    Full Text Available Titanium oxide (TiO2 and iron oxide (α-Fe2O3 hematite films have potential applications as photoanodes in electrochemical water splitting. In the present work TiO2 and α-Fe2O3 thin films were prepared by two methods, e.g., sol-gel and High Power Impulse Magnetron Sputtering (HiPIMS and judged on the basis of physical properties such as crystalline structure and surface topography and functional properties such as simulated photoelectrochemical (PEC water splitting conditions. It was revealed that the HiPIMS method already provides crystalline structures of anatase TiO2 and hematite Fe2O3 during the deposition, whereas to finalize the sol-gel route the as-deposited films must always be annealed to obtain the crystalline phase. Regarding the PEC activity, both TiO2 films show similar photocurrent density, but only when illuminated by UV light. A different situation was observed for hematite films where plasmatic films showed a tenfold enhancement of the stable photocurrent density over the sol-gel hematite films for both UV and visible irradiation. The superior properties of plasmatic films could be explained by ability to address some of the hematite drawbacks by the deposition of very thin films (25 nm consisting of small densely packed particles and by doping with Sn.

  20. Chemistry of the Fe2O3/BiFeO3 Interface in BiFeO3 Thin Film Heterostructures

    Directory of Open Access Journals (Sweden)

    Valanoor Nagarajan

    2010-12-01

    Full Text Available We investigate the interfacial chemistry of secondary Fe2O3 phases formed in a BiFeO3 (BFO layer in BFO/ La0.67Sr0.33MnO3 (LSMO/SrTiO3 (STO heterostructures. A combination of high-resolution spherical aberration corrected scanning TEM and spectroscopy results, reveals that specific chemical and crystallographic similarities between Fe2O3 and BFO, enable the BFO layer to form a facile host for Fe2O3.

  1. Low-cost flexible supercapacitors with high-energy density based on nanostructured MnO2 and Fe2O3 thin films directly fabricated onto stainless steel

    Science.gov (United States)

    Gund, Girish S.; Dubal, Deepak P.; Chodankar, Nilesh R.; Cho, Jun Y.; Gomez-Romero, Pedro; Park, Chan; Lokhande, Chandrakant D.

    2015-07-01

    The facile and economical electrochemical and successive ionic layer adsorption and reaction (SILAR) methods have been employed in order to prepare manganese oxide (MnO2) and iron oxide (Fe2O3) thin films, respectively with the fine optimized nanostructures on highly flexible stainless steel sheet. The symmetric and asymmetric flexible-solid-state supercapacitors (FSS-SCs) of nanostructured (nanosheets for MnO2 and nanoparticles for Fe2O3) electrodes with Na2SO4/Carboxymethyl cellulose (CMC) gel as a separator and electrolyte were assembled. MnO2 as positive and negative electrodes were used to fabricate symmetric SC, while the asymmetric SC was assembled by employing MnO2 as positive and Fe2O3 as negative electrode. Furthermore, the electrochemical features of symmetric and asymmetric SCs are systematically investigated. The results verify that the fabricated symmetric and asymmetric FSS-SCs present excellent reversibility (within the voltage window of 0-1 V and 0-2 V, respectively) and good cycling stability (83 and 91%, respectively for 3000 of CV cycles). Additionally, the asymmetric SC shows maximum specific capacitance of 92 Fg-1, about 2-fold of higher energy density (41.8 Wh kg-1) than symmetric SC and excellent mechanical flexibility. Furthermore, the “real-life” demonstration of fabricated SCs to the panel of SUK confirms that asymmetric SC has 2-fold higher energy density compare to symmetric SC.

  2. Influence of Lithium on Nanosized Films of Fe2O3

    Directory of Open Access Journals (Sweden)

    A. Turković

    2011-01-01

    Full Text Available We have investigated nanosized thin films of α-Fe2O3 (hematite and α-Fe2O3 with addition of Li, by the impedance spectroscopy (IS, the Raman spectroscopy, scanning electron microscopy (SEM, and X-ray diffraction (XRD. Combining all of these methods, and earlier obtained thermally stimulated currents (TSC on the same samples, the dependence of structural and electrical properties upon percentage of Li added into the matrix of these metal-oxide films was found. The comparison of IS, Raman, SEM, XRD, and TSC results reveals the increase of the size of nanoparticles upon inducing 1% of Li in Fe2O3 matrix followed by the decrease of the size of nanoparticles in the case of samples with 10% Li, as well as the decrease (increase of conductivity, respectively. These changes are explained by the structural and morphological changes caused by the impact of Li+ ions in the charge transfers. This material is suitable for application in the galvanic cell of second generation that could be used as solar-cells backup.

  3. High-loading Fe2O3/SWNT composite films for lithium-ion battery applications

    Science.gov (United States)

    Wang, Ying; Guo, Jiahui; Li, Li; Ge, Yali; Li, Baojun; Zhang, Yingjiu; Shang, Yuanyuan; Cao, Anyuan

    2017-08-01

    Single-walled carbon nanotube (SWNT) films are a potential candidate as porous conductive electrodes for energy conversion and storage; tailoring the loading and distribution of active materials grafted on SWNTs is critical for achieving maximum performance. Here, we show that as-synthesized SWNT samples containing residual Fe catalyst can be directly converted to Fe2O3/SWNT composite films by thermal annealing in air. The mass loading of Fe2O3 nanoparticles is tunable from 63 wt% up to 96 wt%, depending on the annealing temperature (from 450 °C to 600 °C), while maintaining the porous network structure. Interconnected SWNT networks containing high-loading active oxides lead to synergistic effect as an anode material for lithium ion batteries. The performance is improved consistently with increasing Fe2O3 loading. As a result, our Fe2O3/SWNT composite films exhibit a high reversible capacity (1007.1 mA h g-1 at a current density of 200 mA g-1), excellent rate capability (384.9 mA h g-1 at 5 A g-1) and stable cycling performance with the discharge capacity up to 567.1 mA h g-1 after 600 cycles at 2 A g-1. The high-loading Fe2O3/SWNT composite films have potential applications as nanostructured electrodes for various energy devices such as supercapacitors and Li-ion batteries.

  4. The influence of the film thickness of nanostructured alpha-Fe2O3 on water photooxidation.

    Science.gov (United States)

    Souza, Flavio Leandro; Lopes, Kirian Pimenta; Longo, Elson; Leite, Edson Roberto

    2009-02-28

    The present work shows the influence of the film thickness in the optical and photoelectrochemical properties of nanostructured alpha-Fe(2)O(3) thin film. We found that the film thickness has a strong influence on the optical absorption and the results here reported can help in the design of nanostructured alpha-Fe(2)O(3) with superior performance for water photo-oxidation. The results show that the optical property of the hematite film is affected by the film thickness, probably due to the stress induced by the strong interaction between film and substrate. This stress generates defects in the crystal lattice of the hematite film, increasing the (e(-))-(h(+)) recombination process.

  5. Single step synthesis of (a-Fe2O3) hematite films by hydrothermal electrochemical deposition

    OpenAIRE

    2015-01-01

    A single step electrodeposition of alpha-Fe2O3 films under hydrothermal conditions without post-annealing requirement is described. Primary attention is paid to understand the effects of synthesis conditions, such as temperature, precursor concentration, pH, and time on the structure and morphology of the films. Moreover, the photoelectrochemical properties of hematite films grown by hydrothermal-electrochemical deposition (HED) are also discussed. It is discovered that HED enables the produc...

  6. Single step synthesis of (a-Fe2O3) hematite films by hydrothermal electrochemical deposition

    OpenAIRE

    Yılmaz, Ceren; Ünal, Uğur

    2015-01-01

    A single step electrodeposition of alpha-Fe2O3 films under hydrothermal conditions without post-annealing requirement is described. Primary attention is paid to understand the effects of synthesis conditions, such as temperature, precursor concentration, pH, and time on the structure and morphology of the films. Moreover, the photoelectrochemical properties of hematite films grown by hydrothermal-electrochemical deposition (HED) are also discussed. It is discovered that HED enables the produc...

  7. PENGARUH PENAMBAHAN NiO TERHADAP KARAKTERISTIK KERAMIK FILM TEBAL Fe2O3 UNTUK SENSOR GAS ASETON

    Directory of Open Access Journals (Sweden)

    E. Suhendi

    2012-12-01

    Full Text Available Pembuatan keramik film tebal Fe2O3-NiO telah dilakukan dengan menggunakan Fe2O3 lokal sebagai bahan dasar untuk sensor gas aseton.  Serbuk Fe2O3 dicampur dengan serbuk NiO dengan konsentrasi 0, 10 dan 50% mol secara homogen. Serbuk campuran kemudian dicampur dengan organic vehicle (OV terbuat dari campuran terpineol dan etil selulose dengan komposisi 75% berat serbuk campuran dan 25% berat OV dan diaduk membentuk pasta. Pasta dilapiskan di atas substrat alumina dengan metode screen printing lalu dibakar pada suhu 900oC selama 90 menit hingga membentuk keramik film tebal. Film tebal dianalisis dengan difraksi sinar-x (XRD dan mikroskop elektron (SEM. Resistansi listrik keramik film tebal diukur pada berbagai suhu di ruangan berisi udara dan berisi gas aseton. Karakterisasi XRD menunjukkan bahwa struktur kristal yang terbentuk adalah Fe2O3 hematit dan NiFe2O4 kubik spinel sebagai fase kedua untuk penambahan konsentrasi NiO 10% dan 50%. Penambahan NiO diketahui memperkecil ukuran butir film tebal Fe2O3 dan meningkatkan resistansi listriknya. Keramik film tebal yang dibuat sensitif terhadap gas aseton.Fabrication of thick film Fe2O3-NiO ceramics for acetone gas sensor has been carried out using local Fe2O3as raw material.  The Fe2O3 powder was mixed with NiO powder homogeneously with NiO concentration of 0, 10 and 50 mole %. The mixed powder was then mixed with organic vehicle (OV made of alpha terpineol and ethyl cellulose with composition of 75 weight % mixed powder and 25 weight % OV forming a paste. The paste was coated on alumina substrates by screen printing method, then fired at 900oC for 90 minutes to produce thick film ceramics. The thick film was analyzed using x-ray diffraction (XRD and scanning electron microscope (SEM. Resistance of the thick films was measured at different temperatures in chamber containing air and containing acetone gas. XRD characterization showed that the crystal structures are hematite Fe2O3 and NiFe2O4 cubic

  8. Stabilisation of Fe2O3-rich Perovskite Nanophase in Epitaxial Rare-earth Doped BiFeO3 Films.

    Science.gov (United States)

    Zhang, Huairuo; Reaney, Ian M; Marincel, Daniel M; Trolier-McKinstry, Susan; Ramasse, Quentin M; MacLaren, Ian; Findlay, Scott D; Fraleigh, Robert D; Ross, Ian M; Hu, Shunbo; Ren, Wei; Rainforth, W Mark

    2015-08-14

    Researchers have demonstrated that BiFeO3 exhibits ferroelectric hysteresis but none have shown a strong ferromagnetic response in either bulk or thin film without significant structural or compositional modification. When remanent magnetisations are observed in BiFeO3 based thin films, iron oxide second phases are often detected. Using aberration-corrected scanning transmission electron microscopy, atomic resolution electron energy loss spectrum-mapping and quantitative energy dispersive X-ray spectroscopy analysis, we reveal the existence of a new Fe2O3-rich perovskite nanophase, with an approximate formula (Fe0.6Bi0.25Nd0.15)(3+) Fe(3+)O3, formed within epitaxial Ti and Nd doped BiFeO3 perovskite films grown by pulsed laser deposition. The incorporation of Nd and Bi ions on the A-site and coherent growth with the matrix stabilise the Fe2O3-rich perovskite phase and preliminary density functional theory calculations suggest that it should have a ferrimagnetic response. Perovskite-structured Fe2O3 has been reported previously but never conclusively proven when fabricated at high-pressure high-temperature. This work suggests the incorporation of large A-site species may help stabilise perovskite-structured Fe2O3. This finding is therefore significant not only to the thin film but also to the high-pressure community.

  9. 氢氟酸腐蚀对α-Fe2O3薄膜光解水电极光电化学性质的影响%Effect of HF Treatment on the Photoelectrochemical Properties of a Hematite Thin Film Photoanode for Water Splitting

    Institute of Scientific and Technical Information of China (English)

    胡玉祥; 姜春香; 方亮; 郑分刚; 董雯; 苏晓东; 沈明荣

    2014-01-01

    The effects of HF treatment on the photoelectrochemical (PEC) properties of sol-gel prepared hematite (α-Fe2O3) thin films were investigated. Pores and interstices between the grains developed on the film surface as the HF etching time increased. The photocurrent density of theα-Fe2O3 photoanode decreased within the first 5 min of etching, and then increased quickly as the etching time increased. At longer time than 15 min the photocurrent density deteriorated. Re-annealing the etched samples significantly enhanced the photocurrent density. Based on electrochemical impedance spectroscopy, Raman and X-ray photoelectron spectroscopies, we propose that two factors contribute to photocurrent density reversely: the porosity and the lowered crystal inity of theα-Fe2O3 surface because of HF treatment. A schematic model was compiled to explain the enhanced PEC activities of the etched plus re-annealedα-Fe2O3 photoanode. The PEC and water splitting measurements showed that the etched plus re-annealed photoanode is more stable than the as-prepared one.%使用溶胶-凝胶法制备了α-Fe2O3薄膜,研究了氢氟酸腐蚀薄膜表面对其光电化学性质的影响。实验发现,薄膜表面的孔洞和间隙随着氢氟酸浸蚀时间的增长而发生变化。氢氟酸浸蚀5 min,α-Fe2O3电极的光电流降低;随后随浸蚀时间增加而迅速增加;当浸蚀时间大于15 min时,其光电流再次下降,但对浸蚀过的样品再次退火可以使光电流大幅增加。通过电化学交流阻抗谱、拉曼和X射线光电子能谱分析,提出了两个影响光电流的因素:氢氟酸表面浸蚀造成薄膜表面的多孔性和结晶度降低。为此,通过示意图解释了结合浸蚀和退火后处理两个步骤来增强α-Fe2O3薄膜光解水电极光电活性的原理。相对于初始的α-Fe2O3电极,浸蚀并且再退火处理后,其光电性质更加稳定。

  10. Synthesis and characterization of mesoporous α-Fe2O3 nanoparticles and investigation of electrical properties of fabricated thick films

    Directory of Open Access Journals (Sweden)

    Ali Mirzaei

    2016-12-01

    Full Text Available In this work, α-Fe2O3 nanoparticles (NPs have been synthesized by using a simple Pechini sol-gel method from iron nitrate, citric acid as complexing agent and ethylene glycol as polymerization agent. The calcined α-Fe2O3 NPs were fully characterized by different techniques. It was confirmed that ultrafine and highly crystalline α-Fe2O3 NPs with high purity and mesoporous nature can be obtained after calcination at 550 °C for 3 h. In addition, the results of electrical resistance measurements of the fabricated Fe2O3 thick films showed that α-Fe2O3 thick films have stable electrical properties which are beneficial for electrical applications such as gas sensing and field effect transistors.

  11. First-principles study of sulfur atom doping and adsorption on α-Fe2O3 (0001) film

    Science.gov (United States)

    An, Jiao; Wanaguru, Prabath; Xia, Congxin; Tao, Meng; Zhang, Qiming

    2016-09-01

    Using the spin-polarized density functional theory (DFT) and the DFT + U method, the geometric and electronic properties of the hematite α-Fe2O3 (0001) film with the sulfur (S) atom doping and adsorption have been investigated systematically. The most stable hematite α-Fe2O3 (0001) film with an anti-ferromagnetic arrangement is identified. For the study of sulfur adsorption on the film, the S adatom prefers to bond with three O atoms, in the center of a triangle formed by the three O atoms. The S acts as a cation at this site. The sulfur adsorption has introduced two gap states, in addition to the unoccupied surface states. Furthermore, with the most stable S-adsorption configuration, the diffusion of the S adatom from the surface to the inside is searched and the transition state along the minimum-energy pathway is also evaluated. For S-doping in the film, it is found that S substitution of O in the top layer is energetically favored than that in the deeper layer. It shows that the value of the band gap is reduced to ∼1.26 eV from ∼1.43 eV of the clean film. The formation energy of S substitution of O in the film is also obtained.

  12. In situ diffuse reflectance infrared Fourier transform spectroscopy study of formaldehyde adsorption and reactions on nano γ-Fe2O3 films

    Science.gov (United States)

    Huang, Kaijin; Kong, Lingcong; Yuan, Fangli; Xie, Changsheng

    2013-04-01

    The nano γ-Fe2O3 films gas sensor was fabricated by the screen printing technology. The phase structures and morphologies of nano γ-Fe2O3 films were characterized by X-ray diffraction (XRD) and field-emission scanning electron microscopy (FESEM), respectively. The gas sensitivity of the films to 100 ppm formaldehyde was investigated. The surface adsorption and reaction process between nano γ-Fe2O3 films and formaldehyde was studied by in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) method at different temperatures. DRIFTS results showed that dioxymethylene, formate ions, polyoxymethylene and molecularly formaldehyde surface species were detected when the nano γ-Fe2O3 films exposed to 100 ppm formaldehyde at different temperatures. A possible mechanism of the reaction process was discussed.

  13. Unpredicted surface termination of α-Fe2O3(0001) film grown by mist chemical vapor deposition

    Science.gov (United States)

    Osaka, Shun; Kubo, Osamu; Takahashi, Kazuki; Oda, Masaya; Kaneko, Kentaro; Tabata, Hiroshi; Fujita, Shizuo; Katayama, Mitsuhiro

    2017-06-01

    We analyze the surface structure of an α-Fe2O3(0001) film grown on a c-plane sapphire substrate by mist chemical vapor deposition (CVD), which has been recently developed as a simple, safe, and cost-effective film growth method. Using coaxial impact-collision ion scattering spectroscopy, we found that the atomic-layer sequence of the surface termination of an α-Fe2O3(0001) film grown by mist CVD was Fe-O3-Fe- from the top layer. This surface termination is predicted to form in an oxygen-poor environment by density functional theory combined with a thermodynamical approach despite that the mist CVD process is performed with atmospheric-pressure air. The surface structure markedly changes after annealing above 600 °C in ultrahigh vacuum. We found that only a couple of layers from the top layer transform into Fe3O4(111) after 650 °C annealing, which would be so-called biphase reconstruction. Complete transformation into a Fe3O4(111) film occurs at 700 °C, whose atomic-layer sequence is determined to be Fe-O4-Fe3- from the top layer.

  14. Study of α-Fe2O3 formation and its measurement in oxide films of wheel surface during ELID grinding process

    Science.gov (United States)

    Kuai, Jicai; Ardashev, Dmitrii V.; Zhang, Huali

    2017-02-01

    This paper presents the study of forming mechanism of α-Fe2O3 in oxide films on electrolytic in-process dressing (ELID) grinding wheel surface. To investigate the component content and the microtopography of oxide films, XRD, XPS, IR spectrum analysis, SEM, and TEM measurements are performed on ELID grinding wheels. In XRD test results, the characteristic absorption band of α-Fe2O3 is found in the oxide film. XPS tests show that there is full of ferrous iron and oxygen element in the oxide film. Also, the characteristic spectral line of XPS is identical to the standard spectrum of α-Fe2O3. Several vibration peaks (471, 1029, 1384, 1630, 3430) are observed by IR spectrum analysis. It can be easily seen by contrast with the standard photographs that the vibration peak of 1029 is of Fe-O vibration band in IR spectrum of α-Fe2O3 powder. Therefore, these measurement results confirm the existence of α-Fe2O3 in the oxide films, and explain the polishing effect of oxide films during ELID grinding. The fresh oxide film is porous and moisture rich. However, the oxide film after squeezing to dry is investigated by SEM imaging to present tortoiseshell cracks. Geometrically, α-Fe2O3 appears to be nearly spherical with particle size around 5-50 nm. This indicates fine polishing improvement by oxide films, and is identified as the mechanism responsible for excellent surface quality by ELID grinding.

  15. Morphology and crystal structure control of alpha-Fe2O3 films by hydrothermal-electrochemical deposition in the presence of Ce3+ and/or acetate, F- ions

    OpenAIRE

    Yılmaz, Özgür; Ünal, Uğur

    2016-01-01

    Hydrothermal-electrochemical growth of Hematite (alpha-Fe2O3) thin films in the presence of Ce3+ and/or CH3COO- and F- ions is reported. Primary attention is paid to understanding the synergistic effect of temperature and additive ions on the growth of Hematite particles. The literature describes the shape-controlled electrodeposition of iron oxide films, but these reports involve low-temperature depositions (

  16. Rapid fabrication of superhydrophobic Al/Fe2O3 nanothermite film with excellent energy-release characteristics and long-term storage stability

    Science.gov (United States)

    Ke, Xiang; Zhou, Xiang; Hao, Gaozi; Xiao, Lei; Liu, Jie; Jiang, Wei

    2017-06-01

    One of the challenges for the application of energetic materials is their energy-retaining capabilities after long-term storage. In this study, we report a facile method to fabricate superhydrophobic Al/Fe2O3 nanothermite film by combining electrophoretic deposition and surface modification technologies. Different concentrations of dispersion solvents and additives are investigated to optimize the deposition parameters. Meanwhile, the dependence of deposition rates on nanoparticle concentrations is also studied. The surface morphology and chemical composition are characterized by field-emission scanning electron microscopy, X-ray diffraction, X-ray energy-dispersive spectroscopy, and X-ray photoelectron spectroscopy. A static contact angles as high as 156° shows the superhydrophobicity of the nanothermite film. Natural and accelerated aging tests are performed and the thermal behavior is analyzed. Thermal analysis shows that the surface modification contributes to significantly improved energy-release characteristics for both fresh and aged samples, which is supposed to be attributed to the preignition reaction between Al2O3 shell and FAS-17. Superhydrophobic Al/Fe2O3 nanothermite film exhibits excellent long-time storage stability with 83.4% of energy left in natural aging test and 60.5% in accelerated aging test. This study is instructive to the practical applications of nanothermites, especially in highly humid environment.

  17. Electrodeposition of Fe2O3 nanoparticles and its supercapacitive properties

    Science.gov (United States)

    Kadam, S. L.; Padwal, P. M.; Mane, S. M.; Kulkarni, S. B.

    2016-04-01

    Fe2O3 metal oxide nanoparticles are synthesized by electrodeposition method on stainless steel substrate. The crystal structure and surface morphological studies of the obtained metal oxide thin film are carried out by using X-ray diffraction (XRD) technique and Scanning Electron Microscopy (SEM) respectively. The electrochemical properties of Fe2O3 thin film like Cyclic Voltammetry (CV), Galvonostatic Charge-Discharge (GCD) and Electrochemical Impedance Spectroscopy (EIS) are studied in a bath of 0.5 M Na2SO4 as electrolyte. The observed specific capacitance shows improved values 135 Fg-1 at 5 mVs-1 scan rate. The electrochemical stability of Fe2O3 electrode is investigated using cyclic voltammetry for 1000 cycles at a scan rate 50 mVs-1. The Fe2O3 electrode exhibits superior cycling stability with only 4-5% capacitance loss after one thousand cycles. The values of specific power and specific energy of Fe2O3 electrode obtained from Galvonostatic charge discharge studies are 2250 W.kg-1 and 63.15 Wh.kg-1 respectively at current density 1 A/g. From all the electrochemical properties of Fe2O3 electrode, it indicates that it will be promising electrode material for supercapacitor application.

  18. Phase-transformation in iron oxide and formation of Cu/γ-Fe2O3 nanocomposite using radio-frequency sputtering with metal chips on an α-Fe2O3 target

    Science.gov (United States)

    Abe, Seishi; Watanabe, Masato

    2017-07-01

    A simple technique that uses radio-frequency sputtering with a functional element on a hematite (α-Fe2O3) target is presented for the production of maghemite (γ-Fe2O3) thin films. These films are prepared on water-cooled glass substrates in an Ar atmosphere. Investigations are done with Ti, Si, Al, Cu, Mo, and Zn, with γ-Fe2O3 being obtained only in the presence of Cu, indicating that phase transition occurs only for this metal. Mössbauer spectra and magnetization analysis reveal that the quality of the obtained γ-Fe2O3 films is higher than that of the film produced using Mg, which was reported in our previous work. High-angle annular dark-field scanning tunneling electron microscopy and electron energy-loss spectroscopy reveal that the added Cu remains in a metallic state (without oxidization), forming a Cu/γ-Fe2O3 phase-mixture in the as-deposited film. The Cu/γ-Fe2O3 composite film exhibits negative magnetoresistance (MR), with a MR ratio of approximately 0.6% at room temperature in an applied field of 10 kOe, and a negative Faraday rotation of -5708 deg cm-1 at 830 nm.

  19. PREPARATION AND CHARACTERIZATION OF Fe2O3/SiO2/TiO2 COMPOSITE FILM%Fe2O3/SiO2/TiO2复合薄膜的制备与表征

    Institute of Scientific and Technical Information of China (English)

    崔鹏; 张金玲

    2008-01-01

    采用溶胶.凝胶法制备了Fe2O3/SiO2/TiO2三元复合薄膜.通过XRD表征、紫外.可见透射光谱分析,考察了Fe2 O3/SiO2对TiO2晶型、亲水性、光催化性能的影响.结果表明:加入Fe2O3、SiO2后TiO2仍然保持完整的锐钛型,抑制了TiO2晶粒的增长,且加入Fe2O3后TiO2的吸收波长发生了"红移".Fe2O3/SiO2/TiO2光催化性能、亲水性能优于SiO2/TiO2、Fe2O3/TiO2及单-TiO2膜.

  20. Spin reorientation in α-Fe2O3 nanoparticles induced by interparticle exchange interactions in alpha-Fe2O3/NiO nanocomposites

    DEFF Research Database (Denmark)

    Frandsen, Cathrine; Lefmann, Kim; Lebech, Bente

    2011-01-01

    We report that the spin structure of alpha-Fe2O3 nanoparticles rotates coherently out of the basal (001) plane at low temperatures when interacting with thin plate-shaped NiO nanoparticles. The observed spin reorientation (up to similar to 70 degrees) in alpha-Fe2O3 nanoparticles has, in appearan...

  1. Spin reorientation in α-Fe2O3 nanoparticles induced by interparticle exchange interactions in alpha-Fe2O3/NiO nanocomposites

    DEFF Research Database (Denmark)

    Frandsen, Cathrine; Lefmann, Kim; Lebech, Bente;

    2011-01-01

    We report that the spin structure of alpha-Fe2O3 nanoparticles rotates coherently out of the basal (001) plane at low temperatures when interacting with thin plate-shaped NiO nanoparticles. The observed spin reorientation (up to similar to 70 degrees) in alpha-Fe2O3 nanoparticles has, in appearan...

  2. α-Fe2O3/SA复合薄膜光催化降解亚甲基蓝的条件及机理研究%Study on Conditions and Mechanism of Photocatalytic Degradation of Methylene Blue with α-Fe2O3/SA Film

    Institute of Scientific and Technical Information of China (English)

    陈力勤; 谢茹胜

    2012-01-01

    在光催化反应器中,紫外灯为光源,以α-Fe2O3/SA薄膜(海藻酸钠简记为SA)为例进行亚甲基蓝溶液的降解研究,考察了催化剂用量、溶液的pH值、亚甲基蓝的初始质量浓度及添加少量的H2O2对亚甲基蓝的降解率的影响,进一步探讨了亚甲基蓝的降解机理.结果表明,单一材料中,电子在光催化作用下由亚甲基蓝的中间态D*转移到激发态D+,从而再转移到a-Fe2O3和TiO2导带上;复合材料a-Fe2O3-TiO2/SA对亚甲基蓝的降解为光电催化氧化机制.%The detail quantitive examination was carried out to investigate the photo-catalytic degradation effect of methylene blue in violet irradiation with a-Fe2O3 catalysts. The experiment results demonstrated that photocatalysis lead to a charge transfer with the concomitant quenching of the transitional state for methylene blue and the formation of the excited state for methylene blue, then on thermodynamic grounds, charge transferred from methylene blue in the excited state to the conduction band of o-Fe2O3 and TiO2. The degradation of methelene blue with a novel multiple-semiconductor o-Fe2O3-TiO2/SA was photo-electro-catalytic-oxidative mechanism.

  3. Nanoscale TiO2 and Fe2O3 Architectures for Solar Energy Conversion Schemes

    Science.gov (United States)

    Sedach, Pavel Anatolyvich

    The direct conversion of sunlight into more useable forms of energy has the potential of alleviating the environmental and social problems associated with a dependence on fossil fuels. If solar energy is to be utilized en-masse, however, it must be inexpensive and widely available. In this vein, the focus of this thesis is on nanostructured materials relevant to solar energy conversion and storage. Specifically, this thesis describes the ambient sol-gel synthesis of titanium dioxide (Ti02) nanowires designed for enhanced charge-transfer in solar collection devices, and the synthesis of novel disordered metal-oxide (MOx) catalysts for water oxidation. The introductory chapter of this thesis gives an overview of the various approaches to solar energy conversion. Sol---gel reaction conditions that enable the growth of one-dimensional (1-D) anatase TiO2 nanostructures from fluorine-doped tin oxide (FTO) for photovoltaics (PVs) are described in the second chapter. The generation of these linear nanostructures in the absence of an external bias or template is achieved by using facile experimental conditions (e.g., acetic acid (HOAc) and titanium isopropoxide (Ti(OiPr)4) in anhydrous heptane). The procedure was developed by functionalizing base-treated substrates with Ti-oxide nucleation sites that serve as a foundation for the growth of linear Ti-oxide macromolecules, which upon calcination, render uniform films of randomly oriented anatase TiO2 nanowires. A systematic evaluation of how reaction conditions (e.g., solvent volume, stoichiometry of reagents, substrate base treatment) affect the generation of these TiO 2 films is presented. A photo-organic MO. deposition route (i.e., photochemical metal-organic deposition (PMOD)) used to deposit thin-films of amorphous iron oxide (a-Fe2O3) for water oxidation catalysis is detailed in third chapter. It is shown that the irradiation of a spin-coated metal-organic film produces a film of non-crystalline a-Fe203. It is shown

  4. A new combustion route to -Fe2O3 synthesis

    Indian Academy of Sciences (India)

    A Venkataraman; Vijay A Hiremath; S K Date; S D Kulkarni

    2001-12-01

    A new combustion route for the synthesis of -Fe2O3 is reported by employing purified -Fe2O3 as aprecursor in the present investigation. This synthesis which is similar to a self propagation combustion reaction, involves fewer steps, a shorter overall processing time, is a low energy reaction without the need of any explosives, and also the reaction is completed in a single step yielding magnetic iron oxide i.e. -Fe2O3. The as synthesized -Fe2O3 is characterized employing thermal, XRD, SEM, magnetic hysteresis, and density measurements. The effect of ball-milling on magnetic properties is also presented.

  5. A Facile Electrochemical Reduction Method for Improving Photocatalytic Performance of α-Fe2O3 Photoanode for Solar Water Splitting.

    Science.gov (United States)

    Wang, Jue; Waters, Joseph L; Kung, Patrick; Kim, Seongsin M; Kelly, John T; McNamara, Louis E; Hammer, Nathan I; Pemberton, Barry C; Schmehl, Russell H; Gupta, Arunava; Pan, Shanlin

    2017-01-11

    Electrochemical reduction method is used for the first time to significantly improve the photo-electrochemical performance of α-Fe2O3 photoanode prepared on fluorine-doped tin oxide substrates by spin-coating aqueous solution of Fe(NO3)3 followed by thermal annealing in air. Photocurrent density of α-Fe2O3 thin film photoanode can be enhanced 25 times by partially reducing the oxide film to form more conductive Fe3O4 (magnetite). Fe3O4 helps facilitate efficient charge transport and collection from the top α-Fe2O3 layer upon light absorption and charge separation to yield enhanced photocurrent density. The optimal enhancement can be obtained for water. Electrochemical reduction of α-Fe2O3 in unbuffered pH-neutral solution yields much higher but unstable photocurrent enhancement because of the increase in local pH value accompanied by proton reduction at a hematite surface.

  6. Preparation of α-Fe2O3 Nanofiber via Electrospinning Process

    Institute of Scientific and Technical Information of China (English)

    SHAO Chang-lu; YANG Xing-hua; GUAN Hong-yu; YU Na; LIU Yi-chun

    2004-01-01

    A thin PVA/FeCl3 composite fiber was prepared by using sol-gel processing and electrospinning tech niques. A nanofiber of α-Fe2O3 with the diameter of 50-150 nm was obtained via high temperature calcina tion of the PVA/FeCl3 composite fiber. The material was characterized by infra-red(IR) spectroscopy, X-ray diffraction(XRD), and scanning electron microscopy(SEM). The results show that the fiber after the calci nation at 700 ℃ was a pure α-Fe2O3 nanofiber.

  7. Gradient doping - a case study with Ti-Fe2O3 towards an improved photoelectrochemical response.

    Science.gov (United States)

    Srivastav, Anupam; Verma, Anuradha; Banerjee, Anamika; Khan, Saif A; Gupta, Mukul; Satsangi, Vibha Rani; Shrivastav, Rohit; Dass, Sahab

    2016-12-07

    The present study investigates the effect of gradient doping on modifying the photoelectrochemical response of Ti-doped Fe2O3 photoanodes for their use in sunlight based water splitting for hydrogen evolution. The deposition of a thin film over the ITO (tin doped indium oxide) substrate was carried out using a spray pyrolysis method. The concentration of dopant was varied from 0.5-8.0 at% and two sets of samples were also prepared with low to high (0.5-8%) and high to low (8-0.5%) dopant concentrations in the direction towards the substrate. The prepared thin films were characterized using X-ray Diffractometry (XRD), Scanning Electron Microscopy (SEM), Energy Dispersive X-ray (EDX) Spectroscopy, Secondary Ion Mass Spectroscopy (SIMS), X-ray Photoelectron Spectroscopy (XPS) and UV-visible Spectroscopy. The photoelectrochemical studies revealed that the deposition of dopant layers with a low to high concentration towards the substrate exhibited a highly improved photoresponse (200 times) in comparison to the pristine sample and a two fold enhancement in comparison to 2% Ti-doped Fe2O3. The improvement in the photoresponse has been attributed to the values of a high flat band potential, low resistance, high open circuit voltage, carrier separation efficiency, applied bias photon-to-current conversion efficiency (ABPE), and incident photon-to-current conversion efficiency (IPCE). A reduced charge transfer resistance has been demonstrated with Nyquist plots.

  8. Symmetric transparent and flexible supercapacitor based on bio-inspired graphene-wrapped Fe2O3 nanowire networks

    Science.gov (United States)

    Huang, Xuankai; Zhang, Haiyan; Li, Na

    2017-02-01

    Transition metal oxides with high specific capacitance materials are ideal for a new generation of high-performance transparent supercapacitors but are rarely reported. Commonly, the synthesis of the required nanostructured materials is a crucial step required to achieve the transparency of the device. In this study, a Fe2O3 nanowire network transparent film is developed simply through air-solution interface reactions and wrapped in graphene shells for use as transparent electrodes. The Fe2O3 nanowire networks surrounded by the graphene layer exhibit an effective encapsulation structure, providing rapid three-dimensional electron and ion transport pathways. The specific areal capacitance (3.3 mF cm-2 at a scan rate of 10 mV s-1) was greatly improved, which is at least one hundred times higher than that for transparent devices based on planar chemical vapor deposition graphene. Furthermore, the films have a power density of 191.3 W cm-3, which is higher than that of electrolytic capacitors, an energy density of 8 mWh cm-3, which is comparable to that of lithium thin-film batteries, and superior cycling stability.

  9. Ultrathin Epitaxial Ferromagneticγ-Fe2O3Layer as High Efficiency Spin Filtering Materials for Spintronics Device Based on Semiconductors

    KAUST Repository

    Li, Peng

    2016-06-01

    In spintronics, identifying an effective technique for generating spin-polarized current has fundamental importance. The spin-filtering effect across a ferromagnetic insulating layer originates from unequal tunneling barrier heights for spin-up and spin-down electrons, which has shown great promise for use in different ferromagnetic materials. However, the low spin-filtering efficiency in some materials can be ascribed partially to the difficulty in fabricating high-quality thin film with high Curie temperature and/or partially to the improper model used to extract the spin-filtering efficiency. In this work, a new technique is successfully developed to fabricate high quality, ferrimagnetic insulating γ-Fe2O3 films as spin filter. To extract the spin-filtering effect of γ-Fe2O3 films more accurately, a new model is proposed based on Fowler–Nordheim tunneling and Zeeman effect to obtain the spin polarization of the tunneling currents. Spin polarization of the tunneled current can be as high as −94.3% at 2 K in γ-Fe2O3 layer with 6.5 nm thick, and the spin polarization decays monotonically with temperature. Although the spin-filter effect is not very high at room temperature, this work demonstrates that spinel ferrites are very promising materials for spin injection into semiconductors at low temperature, which is important for development of novel spintronics devices. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

  10. α-Fe2O3/TiO2 3D hierarchical nanostructures for enhanced photoelectrochemical water splitting.

    Science.gov (United States)

    Han, Hyungkyu; Riboni, Francesca; Karlicky, Frantisek; Kment, Stepan; Goswami, Anandarup; Sudhagar, Pitchaimuthu; Yoo, Jeongeun; Wang, Lei; Tomanec, Ondrej; Petr, Martin; Haderka, Ondrej; Terashima, Chiaki; Fujishima, Akira; Schmuki, Patrik; Zboril, Radek

    2017-01-07

    We report the fabrication of 3D hierarchical hetero-nanostructures composed of thin α-Fe2O3 nanoflakes branched on TiO2 nanotubes. The novel α-Fe2O3/TiO2 hierarchical nanostructures, synthesized on FTO through a multi-step hydrothermal process, exhibit enhanced performances in photo-electrochemical water splitting and in the photocatalytic degradation of an organic dye, with respect to pure TiO2 nanotubes. An enhanced separation of photogenerated charge carriers is here proposed as the main factor for the observed photo-activities: electrons photogenerated in TiO2 are efficiently collected at FTO, while holes are transferred to the α-Fe2O3 nanobranches that serve as charge mediators to the electrolyte. The morphology of α-Fe2O3 that varies from ultrathin nanoflakes to nanorod/nanofiber structures depending on the Fe precursor concentration was shown to have a significant impact on the photo-induced activity of the α-Fe2O3/TiO2 composites. In particular, it is shown that for an optimized photo-electrochemical structure, a combination of critical factors should be achieved such as (i) TiO2 light absorption and photo-activation vs.α-Fe2O3-induced shadowing effect and (ii) the availability of free TiO2 surface vs.α-Fe2O3-coated surface. Finally, theoretical analysis, based on DFT calculations, confirmed the optical properties experimentally determined for the α-Fe2O3/TiO2 hierarchical nanostructures. We anticipate that this new multi-step hydrothermal process can be a blueprint for the design and development of other hierarchical heterogeneous metal oxide electrodes suitable for photo-electrochemical applications.

  11. Magnetic characterization of iron oxides formed after thermal treatment of nontronite and the formation of three polymorphs of Fe2O3: α-Fe2O3, γ-Fe2O3, ɛ-Fe2O3

    Science.gov (United States)

    Berquo, T. S.; Moskowitz, B. M.

    2011-12-01

    Nontronite is an Fe-rich smectite clay that occurs widely in terrestrial soils, sediments and weathering formations and may also be present in the Martian regolith. The thermal decomposition of nontronite is known to form various magnetic iron oxides but their compositions, magnetic properties, and formation pathways remain poorly understood. The magnetic alteration products of nontronite have been proposed as a source for the magnetic phases in the surface layers and dust on Mars as well as in some archeological fired-bricks and ceramic pottery. One alteration product of nontronite is ɛ-Fe2O3 which is ferrimagnetic with a Curie temperature of ~ 500 K and extremely large coercivity (HC ~ 1-2 T) at 300 K. In this work nontronite samples from eight source localities were heated to 1000°C in air for one hour. The magnetic properties of the alteration products were investigated with low-temperature (LT) magnetization and AC susceptibility curves, hysteresis loops, Mossbauer spectroscopy, and X-ray diffraction. The thermal treatment was effective in converting the nontronite to a combination of different polymorphs of ferric oxide depending on source locality and included: hematite (α-Fe2O3), ɛ-Fe2O3, and a cubic spinel phase that suggest the presence of maghemite (γ-Fe2O3). Mossbauer spectra at 300 K identified hematite and ɛ-Fe2O3 as the main phases in 7 samples with amounts ranging from 26-100% for hematite 0-69% for ɛ-Fe2O3. One sample showed a paramagnetic Fe3+ doublet and a broad sextet characteristic of magnetic relaxation effects. Upon cooling to 4.2 K, the Mossbauer spectrum was consistent with maghemite. In all samples except one, the magnetic hyperfine fields for the hematite phase are slightly reduced as compared with its stoichiometric form indicating some iron substitution with ions such as Al. This is consistent with the observation that all but one sample lacked the characteristic Morin transition for pure hematite on LT-remanence warming curves

  12. Synthesis of ferrite grade -Fe2O3

    Indian Academy of Sciences (India)

    K S Rane; V M S Verenkar

    2001-02-01

    Iron(II) carboxylato–hydrazinates: Ferrous fumarato–hydrazinate (FFH), FeC4H2O4.2N2H4; ferrous succinato–hydrazinate (FSH), FeC4H4O4.2N2H4;ferrous maleato–hydrazinate (FEH), FeC4H2O4.2N2H4;ferrous malato–hydrazinate (FLH), FeC4H4O5.2N2H4;ferrous malonato–hydrazinate (FMH), FeC3H2O4.1.5N2H4.H2O; and ferrous tartrato–hydrazinate (FTH), FeC4H4O6.N2H4.H2O are being synthesized for the first time. These decompose (autocatalytically) in an ordinary atmosphere to mainly -Fe2O3, while the unhydrazinated iron(II) carboxylates in air yield -Fe2O3, but the controlled atmosphere of moisture requires for the oxalates to stabilize the metastable -Fe2O3. The hydrazine released during heating reacts with atmospheric oxygen liberating enormous energy, $$N_2H_4 + O_2 \\rightarrow N_2 + H_2O;\\Delta H_2O = – 621 kJ/mol,$$ which enables to oxidatively decompose the dehydrazinated complex to -Fe2O3. The reaction products N2 + H2O provide the necessary atmosphere of moisture needed for the stabilization of the metastable oxide. The synthesis, characterization and thermal decomposition (DTA/TG) of the iron(II) carboxylato–hydrazinates are discussed to explain the suitability of -Fe2O3 in the ferrite synthesis.

  13. Plasmonic layer enhanced photoelectrochemical response of Fe2O3 photoanodes

    Science.gov (United States)

    Verma, Anuradha; Srivastav, Anupam; Banerjee, Anamika; Sharma, Dipika; Sharma, Shailja; Singh, Udai Bhan; Satsangi, Vibha Rani; Shrivastav, Rohit; Avasthi, Devesh Kumar; Dass, Sahab

    2016-05-01

    Present experimental study focuses on the influence of plasmonic layer in Zr-doped Fe2O3 (Z-F) thin film based photoanodes deposited in different configurations for photo splitting of water. The Au nanoparticles (plasmonic layer) as bottom layer and surface (top) layer are incorporated in the spray pyrolytically deposited Z-F thin layer. In addition to this, fabrication of Z-F sandwiched between two plasmonic Au layers (Au/Z-F/Au) as well as plasmonic Au layer sandwiched between two Z-F layers (Z-F/Au/Z-F) are also undertaken. All configurations using plasmonic layer show enhanced photoresponse in comparison to the pristine Z-F samples. The Z-F sandwiched between two plasmonic layers shows the most significant increase in photocurrent density at 0.8 V/SCE (Saturated Calomel Electrode) and also improved optical absorption due to the presence of two palsmonic layers which promote charge transfer and inhibit charge recombination. The obtained results are supported by characterization techniques viz. X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Energy Dispersive X-ray Analysis (EDAX), UV-Visible absorption spectroscopy, Photoelectrochemical properties, Mott-Schottky analysis and efficiency measurements of photoelectrochemical (PEC) sytstem.

  14. Lead adsorption study on combustion derived -Fe2O3 surface

    Indian Academy of Sciences (India)

    Arunkumar Lagashetty; H Vijayanand; S Basavaraja; N N Mallikarjuna; A Venkataraman

    2010-02-01

    New combustion synthetic route for the synthesis of nanosized -Fe2O3 by microwave-assisted route is reported. X-ray density, tap density and powder density of prepared -Fe2O3 are calculated. Adsorption study of Pb2+ on combustion derived nanosized -Fe2O3 is studied by dynamic method. The -Fe2O3 structure and lead adsorbed -Fe2O3 (Pb--Fe2O3) are studied by X-ray diffraction (XRD). Additional lead peaks in Pb--Fe2O3 sample pattern confirm the lead adsorption. Morphology of as prepared -Fe2O3 and Pb--Fe2O3 is studied by scanning electron micrograph (SEM) technique. Varied morphology for Pb--Fe2O3 compared to its -Fe2O3 is observed. Variation of bonding in Pb--Fe2O3 sample due to lead adsorption is viewed by infrared spectroscopic (IR) technique. Energy dispersive X-ray microanalysis (EDX) is scanned for the lead adsorbed -Fe2O3 to know the presence of lead on -Fe2O3 surface. The eluent lead solution is characterized by atomic absorption spectroscopy (AAS) and solution conductivity (SC). Reduction in the concentration and increase in conductance of eluent lead solution is observed. The potential use of solid adsorbents for the adsorption of heavy metal pollutants is envisaged in the present work.

  15. Thermal oxidation synthesis and magnetic properties of large-areaα-Fe2 O3 nanobelts%大面积α-Fe2O3纳米带的热氧化制备及其磁性能

    Institute of Scientific and Technical Information of China (English)

    钟明龙; 刘仲武; 焦东玲; 钟喜春; 余红雅; 曾德长

    2014-01-01

    Large-areaα-Fe2 O3 nanobelts were synthesized by heating the Fe film on silicon substrate in air,using a very simple hotplate technique.The morphologies,crystal structures,growth mechanism and magnetic prop-erties of the nanobelts were investigated.The results showed that single-crystalα-Fe2 O3 nanobelts grew per-pendicularly to the substrate along [110]direction with a very sharp tip about 10-50 nm.The length of the nanobelts were from hundreds nanometers to several micrometers.A diffusion mechanism was responsible for theα-Fe2 O3 nanostructure growth at relatively low temperatures.The Morin temperature TM and Néel temper-ature TN ofα-Fe2 O3 nanostructures were only 113 and 814 K,respectively,which were about 150 K lower than those for their bulk counterpart.%通过电热板在空气中直接加热氧化沉积在硅基片上的Fe膜,在其表面上获得大面积α-Fe2 O3纳米带,这一方法为制备大面积氧化物纳米结构提供了一种非常简单的工艺。研究了所制备的α-Fe2 O3纳米带的形貌、晶体结构、生长机制及其磁性能。α-Fe2 O3纳米带呈尖锐状并沿[110]方向垂直基片生长,其顶端为10~50 nm,长度为几百纳米至几微米。α-Fe2 O3纳米带在较低温度下的生长过程是一种扩散机制。α-Fe2 O3纳米结构的Morin温度TM、Néel温度TN 分别为113和814 K,与其块体材料相比均降低了150 K左右。

  16. Thermal Stability of Fe2O3 Nanowires

    Institute of Scientific and Technical Information of China (English)

    Xiongjian ZHANG; Qin HAN; Zhao DONG; Yingying XU; Han ZHANG

    2008-01-01

    Metal oxide nanostructures (CuO, Co3O4, ZnO and α-Fe2O3) have been successfully fabricated by a simple and efficient method: heating the appropriate metals in air at low temperatures ranging from 200 to 400℃. The chemical composition, morphology and crystallinity of the nanostructures have been characterized by micro-Raman spectroscopy, X-ray diffraction, scanning electron microscopy and transmission electron microscopy. Two mechanisms: vapor-solid and surface diffusion play dominant roles in the growth of metal oxide nanostructures starting with low melting point metals (Zn and Cu) and high melting point metals (Fe and Co), respectively. With sharp ends and large aspect ratio, the metal oxide nanostructures exhibit impressive field-induced electron emission properties, indicating their potentials as future electron source and displays. The water wettability and anti-wettability properties of iron oxide nanoflakes were also discussed in this work.

  17. Effect of Fe2O3 and Binder on the Electrochemical Properties of Fe2O3/AB (Acetylene Black) Composite Electrodes

    Science.gov (United States)

    Anh, Trinh Tuan; Thuan, Vu Manh; Thang, Doan Ha; Hang, Bui Thi

    2017-01-01

    In an effort to find the best anode material for Fe/air batteries, a Fe2O3/AB (Acetylene Black) composite was prepared by dry-type ball milling using Fe2O3 nanoparticles and AB as the active and additive materials, respectively. The effects of various binders and Fe2O3 content on the electrochemical properties of Fe2O3/AB electrodes in alkaline solution were investigated. It was found that the content of Fe2O3 strongly affected the electrochemical behavior of Fe2O3/AB electrodes; with Fe2O3 nanopowder content reaching 70 wt.% for the electrode and showing improvement of the cyclability. When the electrode binder polytetrafluoroethylene (PTFE) was used, clear redox peaks were observed via cyclic voltammetry (CV), while polyvinylidene fluoride-containing electrodes provided CV curves with unobservable redox peaks. Increasing either binder content in the electrode showed a negative effect in terms of the cyclability of the Fe2O3/AB electrode.

  18. α-Fe2O3的掺杂改性和降解性能%Doping modification and degradation of α-Fe2O3

    Institute of Scientific and Technical Information of China (English)

    涂盛辉; 刘婷; 骆中璨; 杜军

    2015-01-01

    利用水热法制备α-Fe2O3,再以α-Fe2O3为活性组分,利用浸渍法制备Ag/α-Fe2O3、Al/α-Fe2O3、Zn/α-Fe2O3、Cu/α-Fe2O3催化剂,比较4种催化剂的催化活性,通过XRD、SEM、FT-IR等表征手段对Al/α-Fe2O3催化剂的结构和形貌进行分析,与纯的α-Fe2O3催化剂相比,负载铝的α-Fe2O3催化剂的催化活性更好,稳定性也更高.考察了Al掺杂量、煅烧温度、煅烧时间等制备条件对催化剂催化活性的影响,确定了最佳制备条件.结果表明:当Al掺杂量为40%,煅烧温度为700℃,煅烧时间为2h,催化剂的催化活性最高,且Al/α-Fe2O3降解酸性大红符合伪一级动力学方程,催化剂在连续使用7次后,仍然保持较高的催化效果.

  19. Growth of Fe2O3/SnO2 nanobelt arrays on iron foil for efficient photocatalytic degradation of methylene blue

    Science.gov (United States)

    Lei, Rui; Ni, Hongwei; Chen, Rongsheng; Zhang, Bowei; Zhan, Weiting; Li, Yang

    2017-04-01

    Tin(IV) oxide has been intensively employed in optoelectronic devices due to its excellent electrical and optical properties. But the high recombination rates of the photogenerated electron-hole pairs of SnO2 nanomaterials often results in low photocatalytic efficiency. Herein, we proposed a facile route to prepare a novel Fe2O3/SnO2 heterojunction structure. The nanobelt arrays grown on iron foil naturally form a Schottky-type contact and provide a direct pathway for the photogenerated excitons. Hence, the Fe2O3/SnO2 nanobelt arrays exhibit much improved photocatalytic performance with the degradation rate constant on the Fe2O3/SnO2 film of approximately 12 times to that of α-Fe2O3 nanobelt arrays.

  20. Optical properties of nanocrystallite films of α-Fe2O3 and α-Fe2-x Cr x O3 (0.0  ⩽  x  ⩽  0.9) deposited on glass substrates

    Science.gov (United States)

    Kumar, Ajay; Yadav, Kamlesh

    2017-07-01

    α-Fe2O3 films are deposited on fluorine-doped tin oxide (FTO) and indium-doped tin oxide (ITO) substrates for 1, 4 and 6 min using a spray pyrolysis technique. We also deposited α-Fe2-x Cr x O3 (x  =  0.0, 0.1, 0.2, 0.3, 0.4, 0.7 and 0.9) films on the FTO substrate for a deposition time of 35 s. The structural and optical properties of these films were then studied. The x-ray diffraction (XRD) patterns show that all the films are crystalline in nature with a hexagonal crystal structure. The average grain size and unit cell volume were calculated using XRD data. It is found that the average grain size and unit cell volume increase with an increasing film thickness and Cr-doping concentration. The value of strain decreases with an increasing film thickness and Cr-doping content. It is also found that films with the same deposition time on the ITO substrate are more crystalline than on the FTO substrate. Furthermore, the average grain size is obtained from field emission scanning electron microscopy (FESEM) images. FESEM analysis confirms that the average grain size increases with the film thickness and Cr-doping concentration. The optical absorption spectra of the films show that the absorbance increases with an increasing deposition time and Cr concentration. The energy band gap (E g) of all the films has been calculated using Tauc’s relation. A narrowing of the band gap was observed with an increase in film thickness and Cr-doping content. The reduction of the band gap with the increase in film thickness of the films deposited on the ITO substrate is larger than for the film deposited on the FTO substrate. The refractive index is also obtained from the absorption spectra of the films using the Moss relation: n  =  \\sqrt[4]{≤ft(k/{{E}\\text{g}}\\right)} , where k  =108 eV. The refractive index decreases with an increase in the optical band gap. The band gaps of the films are also calculated from the FTIR spectra. This is in good

  1. Recognition and transmembrane delivery of bioconjugated Fe2O3@Au nanoparticles with living cells

    Science.gov (United States)

    Sun, Linlin; Wang, Jine; Wang, Zhenxin

    2010-02-01

    Here, we describe the synthesis of peptide- and/or protein-functionalized Fe2O3 core-Au shell (Fe2O3@Au) nanoparticles for imaging and targeting of living cells. When functionalized with the transmembrane peptide RRRRRRRR (R8), the Fe2O3@Au nanoparticles (R8-Fe2O3@Au) are able to serve as cellular trafficking agents with excellent biocompatibility. The internalization mechanism and delivery efficiency of the R8-Fe2O3@Au nanoparticles have been characterized with dark-field microscopy and fluorescence confocal scanning laser microcopy. Experimental result suggests that the R8-Fe2O3@Au nanoparticles are internalized initially by binding with the membrane-associated proteoglycans on cell surfaces, especially heparan sulfate proteoglycans (HSPGs), following an energy-dependent endocytosis process to enter into living cells. After conjugation with the epidermal growth factor receptor antibody (anti-EGFR), these nanoparticles can also be used for the recognition of cell membrane antigens to specifically label tumor cells.Here, we describe the synthesis of peptide- and/or protein-functionalized Fe2O3 core-Au shell (Fe2O3@Au) nanoparticles for imaging and targeting of living cells. When functionalized with the transmembrane peptide RRRRRRRR (R8), the Fe2O3@Au nanoparticles (R8-Fe2O3@Au) are able to serve as cellular trafficking agents with excellent biocompatibility. The internalization mechanism and delivery efficiency of the R8-Fe2O3@Au nanoparticles have been characterized with dark-field microscopy and fluorescence confocal scanning laser microcopy. Experimental result suggests that the R8-Fe2O3@Au nanoparticles are internalized initially by binding with the membrane-associated proteoglycans on cell surfaces, especially heparan sulfate proteoglycans (HSPGs), following an energy-dependent endocytosis process to enter into living cells. After conjugation with the epidermal growth factor receptor antibody (anti-EGFR), these nanoparticles can also be used for the

  2. Preparation and Characterization of Fe2O3/Al2O3 Nano-composites

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Al2O3/Fe2O3 nano-composites were prepared by sol-gel route. The effect of Fe2O3 content on the structure, grain size and characterization of the composite were investigated through X-ray diffraction and M(o)ssbauer spectrum. The X-ray diffraction results show that Al2O3/Fe2O3 nano-composites with the Fe2O3, content of 40 wt% can be obtained after heat-treated at 900℃. The M(o)ssbauer effect results show that all samples exhibit clear super-paramagnetic phenomenon. Particles grow and defects reduce with the increasing of Fe2O3 conteni and some α-Fe2O3 stay magnetic order.

  3. Synthesis of Co2+-doped Fe2O3 photocatalyst for degradation of pararosaniline dye

    Science.gov (United States)

    Suresh, R.; Giribabu, K.; Manigandan, R.; Mangalaraja, R. V.; Solorza, Jorge Yanez; Stephen, A.; Narayanan, V.

    2017-06-01

    In this paper, x (=2, 5, 7 and 10mol%) Co2+-doped Fe2O3 (xCo:Fe2O3) nanoparticles with enhanced photocatalytic activity have been reported. xCo:Fe2O3 nanoparticles were successfully prepared by co-precipitation followed thermal decomposition method. The structural, optical and morphological properties of the prepared samples were studied by X-ray diffraction (XRD), Fourier transform infrared (FT-IR), X-ray photoelectron spectroscopy (XPS), diffuse reflectance (DR) UV-visible absorption spectroscopy, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The obtained results revealed that Co2+ ions were well doped within the lattices of Fe2O3. Also, Co2+ ions suppress the formation of the most stable α- Fe2O3 and stabilize less stable γ-Fe2O3 at 450 °C. The photocatalytic activity of xCo:Fe2O3 was examined by using pararosaniline (PR) dye. It was found that photocatalytic degradation of PR depends on dopant concentration (Co2+ ions). Relatively, the highest photocatalytic activity was observed for 5%Co:Fe2O3 nanoparticles. The plausible photocatalytic degradation pathway of PR at xCo:Fe2O3 surface has also been proposed.

  4. Fe2O3/ Co3O4 composite nanoparticle ethanol sensor

    CERN Document Server

    Mirzaei, Ali; Sun, Gun-Joo; Kheel, Hyejoon; Lee, Sangmin; lee, Chongmu

    2016-01-01

    In this study Fe2O3/Co3O4 nanocomposites were synthesized by using a simple hydrothermal route. The X-ray diffraction analysis results showed that synthesized powders were pure, and nanocrystalline in nature. Moreover, Scanning electron microscopy revealed that Fe2O3 nanoparticles had spherical shapes while Co3O4 particles had a rod-like morphology. Ethanol sensing properties of Fe2O3/Co3O4 nanocomposites were examined and compared with those of pristine Fe2O3 nanoparticles. It was shown that the gas sensing properties of Fe2O3/Co3O4 nanocomposites were superior to those of pristine Fe2O3 nanoparticles and for all concentrations of ethanol, the response of the nanocomposite sensor was higher than the pristine Fe2O3 nanoparticle sensor. In detail, the response of Fe2O3/Co3O4 nanocomposite sensor to 200 ppm of ethanol at 300{\\deg}C was about 3 times higher than pristine one. Also in general, the response and recovery times of Fe2O3/Co3O4 nanocomposite sensor were shorter than those of the pristine one. The impr...

  5. Aggregation and stability of Fe2O3:Influence of humic acid concentration, Fe2O3 concentration and pH

    Science.gov (United States)

    Ahmad, Nur Suraya; Radiman, Shahidan; Yaacob, Wan Zuhairi Wan

    2016-11-01

    The scenario of released nanoparticles from consumer product into the environment especially natural waters are increased concern nowadays. Assessing their aggregation and stability under environmental conditions are important to determining their fate and behavior in natural waters. The aggregation behavior of Fe2O3 nanoparticles (NPs) was investigated at variable concentration of humic acid, Fe2O3 NPs concentration and pH variation in solution using dynamic light scattering to measure their z-average hydrodynamic diameter and zeta potential value. The stability are then evaluated by assessing their aggregation and disaggregation. Increasing humic acid concentration induced the disaggregation of Fe2O3 NPs. At a lower concentrations of Fe2O3 (5) of solution induced disaggregation of suspensions and make it stable in the solution. TEM imaging have confirmed that Fe2O3 NPs aggregate and disaggregate in the presence of humic acid. Our study result shows that aggregation and stability of Fe2O3 NPs were depends on concentration of humic acid, concentration of NPs itself and the pH of the solutions.

  6. Rheological non-Newtonian behaviour of ethylene glycol-based Fe2O3 nanofluids

    Directory of Open Access Journals (Sweden)

    Pastoriza-Gallego María

    2011-01-01

    Full Text Available Abstract The rheological behaviour of ethylene glycol-based nanofluids containing hexagonal scalenohedral-shaped α-Fe2O3 (hematite nanoparticles at 303.15 K and particle weight concentrations up to 25% has been carried out using a cone-plate Physica MCR rheometer. The tests performed show that the studied nanofluids present non-Newtonian shear-thinning behaviour. In addition, the viscosity at a given shear rate is time dependent, i.e. the fluid is thixotropic. Finally, using strain sweep and frequency sweep tests, the storage modulus G', loss modulus G″ and damping factor were determined as a function of the frequency showing viscoelastic behaviour for all samples.

  7. Hierachical Ni@Fe2O3 superparticles through epitaxial growth of γ-Fe2O3 nanorods on in situ formed Ni nanoplates

    Science.gov (United States)

    Tahir, Muhammad Nawaz; Herzberger, Jana; Natalio, Filipe; Köhler, Oskar; Branscheid, Robert; Mugnaioli, Enrico; Ksenofontov, Vadim; Panthöfer, Martin; Kolb, Ute; Frey, Holger; Tremel, Wolfgang

    2016-05-01

    One endeavour of nanochemistry is the bottom-up synthesis of functional mesoscale structures from basic building blocks. We report a one-pot wet chemical synthesis of Ni@γ-Fe2O3 superparticles containing Ni cores densely covered with highly oriented γ-Fe2O3 (maghemite) nanorods (NRs) by controlled reduction/decomposition of nickel acetate (Ni(ac)2) and Fe(CO)5. Automated diffraction tomography (ADT) of the Ni-Fe2O3 interface in combination with Mössbauer spectroscopy showed that selective and oriented growth of the γ-Fe2O3 nanorods on the Ni core is facilitated through the formation of a Fe0.05Ni0.95 alloy and the appearance of superstructure features that may reduce strain at the Ni-Fe2O3 interface. The common orientation of the maghemite nanorods on the Ni core of the superparticles leads to a greatly enhanced magnetization. After functionalization with a catechol-functional polyethylene glycol (C-PEG) ligand the Ni@γ-Fe2O3 superparticles were dispersible in water.One endeavour of nanochemistry is the bottom-up synthesis of functional mesoscale structures from basic building blocks. We report a one-pot wet chemical synthesis of Ni@γ-Fe2O3 superparticles containing Ni cores densely covered with highly oriented γ-Fe2O3 (maghemite) nanorods (NRs) by controlled reduction/decomposition of nickel acetate (Ni(ac)2) and Fe(CO)5. Automated diffraction tomography (ADT) of the Ni-Fe2O3 interface in combination with Mössbauer spectroscopy showed that selective and oriented growth of the γ-Fe2O3 nanorods on the Ni core is facilitated through the formation of a Fe0.05Ni0.95 alloy and the appearance of superstructure features that may reduce strain at the Ni-Fe2O3 interface. The common orientation of the maghemite nanorods on the Ni core of the superparticles leads to a greatly enhanced magnetization. After functionalization with a catechol-functional polyethylene glycol (C-PEG) ligand the Ni@γ-Fe2O3 superparticles were dispersible in water. Electronic supplementary

  8. Excellent ethanol sensing properties based on Er2O3-Fe2O3 nanotubes

    Institute of Scientific and Technical Information of China (English)

    刘唱白; 何滢; 王圣蕾

    2015-01-01

    In this work, pureα-Fe2O3 and Er2O3-Fe2O3 nanotubes were synthesized by a simple single-capillary electrospin-ning technology followed by calcination treatment. The morphologies and crystal structures of the as-prepared samples were characterized by scanning electron microscopy and x-ray diffraction, respectively. The gas-sensing properties of the as-prepared samples have been researched, and the result shows that the Er2O3-Fe2O3 nanotubes exhibit much better sen-sitivity to ethanol. The response value of Er2O3-Fe2O3 nanotubes to 10 ppm ethanol is 21 at the operating temperature 240◦, which is 14 times larger than that of pureα-Fe2O3 nanotubes (response value is 1.5). The ethanol sensing properties ofα-Fe2O3 nanotubes are remarkably enhanced by doping Er, and the lowest detection limit of Er2O3-Fe2O3 nanotubes is 300 ppb, to which the response value is about 2. The response and recovery times are about 4 s and 70 s to 10 ppm ethanol, respectively. In addition, the Er2O3-Fe2O3 nanotubes possess good selectivity and long-term stability.

  9. Magnetic Properties of γ-Fe2O3 Nanoparticles Prepared by Laser Ablation

    Institute of Scientific and Technical Information of China (English)

    WANG Zemin; ZENG Xiaoyan

    2006-01-01

    A new method of preparing nanoparticles by pulsed-laser ablation of a tiny wire was reported, and pure maghemite ( γ-Fe2O3 ) nanoparticles were synthesized by this method in a mixed gas flux of N2 and O2 at atmospheric pressure. The obtainedγ- Fe2O3 nanopartiles were in the range of 5 to 80 nm in diameter and largely spherical in shape. Structural characteristics and morphologies of the nanoparticles were characterized by XRD and TEM, respectively. Moreover, magnetic properties of the obtained γ- Fe2O3 nanopartiles in the temperature range of 300 to 773 K were investigated. The experimental results demonstrate that the squareness value of the hysteresis loop decreases with increasing temperature. Both the coercivity and the saturation magnetization of the γ- Fe2O3 nanoparticles show a constantly decreasing trend with increasing temperature up to the occurrence of the transformation from γ- Fe2O3 to α- Fe2O3. Especially, at the temperature of 773 K, the γ- Fe2O3 begins to transform to the α-Fe2O3 phase and the hysteresis loop becomes unclosed.

  10. Cathodic electrophoretic deposition ofα-Fe2O3 coating

    Institute of Scientific and Technical Information of China (English)

    马莉; 常通; 李小斌; 李志友; 张斗; 周科朝

    2015-01-01

    Submicroα-Fe2O3 coatings were formed using electrophoretic deposition (EPD) technique in aqueous media. The zeta potentials of differentα-Fe2O3 suspensions with different additives were measured as a function of pH to identify the optimum suspension condition for deposition. Electrophoretic depositions ofα-Fe2O3 coatings under different applied electric fields and deposition time were studied and the effects of applied voltages and deposition time on deposition rates and thicknesses were investigated. The particle packing densities of the deposits at various applied voltages and deposition time were also analyzed by a scanning electron microscope (SEM). The results show that crack-freeα-Fe2O3 coatings with uniform microstructure and good adherence to the nickel substrates are successfully obtained. Electrophoretic depositedα-Fe2O3 coating from aqueous suspension is a feasible, low-cost and environmental friendly method.

  11. Preparation of α-Fe2O3 Nanodisks by Blocking the Growth of (001) Plane

    Institute of Scientific and Technical Information of China (English)

    Baoliang Lv; Yao Xu; Dong Wu; Yuhan Sun

    2009-01-01

    Based on the difference of hydroxy group configuration on different planes of α-Fe2O3 nanoparticles, using the special adsorption and coordination of phosphate on the (001) plane of α-Fe2O3, well-crystallized and well dispersed α-Fe2O3 nanodisks with diameter of 150-200 nm and thickness of 40-80 nm were synthesized via a hydrothermal method. The magnetic properties of synthesized nanodisks were investigated. It was found that the nanodisks possessed a saturation magnetization (Ms) of 0.38 emu/g, a remanent magnetization (Mr) of 0.031 emu/g and a coercivity of 452.91 Oe at room temperature. The Mr and coercivity of synthesized α-Fe2O3 nanodisks are higher and the Ms is lower than those of other previously reported α-Fe2O3 nanostructures.

  12. Novel α-Fe2O3/CdS cornlike nanorods with enhanced photocatalytic performance.

    Science.gov (United States)

    Shi, Ye; Li, Hanying; Wang, Ling; Shen, Wei; Chen, Hongzheng

    2012-09-26

    Various semiconductors have been studied as photocatalysts for photocatalytic degradation of pollutants in aqueous solutions. As one of the promising visible-light-driven semiconductor photocatalysts, α-Fe(2)O(3) has advantages of low cost and stability. However, its application is inhibited by the poor separation of photogenerated electron-hole pair. In this work, hybrid structures were prepared to improve the performance of α-Fe(2)O(3). CdS nanoparticles were overgrown on the preformed single-crystalline α-Fe(2)O(3) nanorods by a simple and mild one-step wet-chemical method, resulting in α-Fe(2)O(3)/CdS cornlike nanocomposites. X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and Raman spectroscopy showed the α-Fe(2)O(3)/CdS core/shell heterostructure of the nanocomposite with high crystallinity. Furthermore, the cornlike nanocomposites exhibited superior photocatalytic performances under visible light irradiation over the pure α-Fe(2)O(3) nanorods and CdS nanoparticles. The photocatalytic activity of the composites is superior to the previously-reported pure α-Fe(2)O(3) nanomaterials, and the performance is comparable to both the commercial TiO(2) (P25) which is used under UV irradiation and the newly developed α-Fe(2)O(3)/SnO(2) photocatalyst under visible light irradiation. The enhanced performance is associated with the larger surface area of the cornlike structure, the crystalline nature of the materials and the synergy in light absorption and charge separation between α-Fe(2)O(3) and CdS. As such, our α-Fe(2)O(3)/CdS cornlike nanocomposites may be promising to be used as visible-light-driven high-performance photocatalyst.

  13. Nanoparticle Metamorphosis: An in Situ High-Temperature Transmission Electron Microscopy Study of the Structural Evolution of Heterogeneous Au:Fe 2 O 3 Nanoparticles

    KAUST Repository

    Baumgardner, William J.

    2014-05-27

    High-temperature in situ electron microscopy and X-ray diffraction have revealed that Au and Fe2O3 particles fuse in a fluid fashion at temperatures far below their size-reduced melting points. With increasing temperature, the fused particles undergo a sequence of complex structural transformations from surface alloy to phase segregated and ultimately core-shell structures. The combination of in situ electron microscopy and spectroscopy provides insights into fundamental thermodynamic and kinetic aspects governing the formation of heterogeneous nanostructures. The observed structural transformations present an interesting analogy to thin film growth on the curved surface of a nanoparticle. Using single-particle observations, we constructed a phase diagram illustrating the complex relationships among composition, morphology, temperature, and particle size. © 2014 American Chemical Society.

  14. Fe3O4/γ-Fe2O3 nanoparticle multilayers deposited by the Langmuir-Blodgett technique for gas sensors application.

    Science.gov (United States)

    Capone, S; Manera, M G; Taurino, A; Siciliano, P; Rella, R; Luby, S; Benkovicova, M; Siffalovic, P; Majkova, E

    2014-02-04

    Fe3O4/γ-Fe2O3 nanoparticles (NPs) based thin films were used as active layers in solid state resistive chemical sensors. NPs were synthesized by high temperature solution phase reaction. Sensing NP monolayers (ML) were deposited by Langmuir-Blodgett (LB) techniques onto chemoresistive transduction platforms. The sensing ML were UV treated to remove NP insulating capping. Sensors surface was characterized by scanning electron microscopy (SEM). Systematic gas sensing tests in controlled atmosphere were carried out toward NO2, CO, and acetone at different concentrations and working temperatures of the sensing layers. The best sensing performance results were obtained for sensors with higher NPs coverage (10 ML), mainly for NO2 gas showing interesting selectivity toward nitrogen oxides. Electrical properties and conduction mechanisms are discussed.

  15. Electrodeposition of Ni-Co-Fe2O3 composite coatings

    Institute of Scientific and Technical Information of China (English)

    MA Li; ZHOU Ke-chao; LI Zhi-you; WEI Qiu-ping

    2010-01-01

    Ni-Co-Fe2O3 composite coatings were electrodeposited using cetyltrimethylammonium bromide(CTAB)-modified Watt's nickel bath with Fe2O3 particles dispersed in it.The effects of the plating parameters on the chemical composition,structural and morphological characteristics of the electrodeposited Ni-Co-Fe2O3 composite coatings were investigated by energy dispersive X-ray(EDS)spectroscopy,X-ray diffractometry(XRD)and scanning electron microscopy(SEM).The results reveal that Fe2O3 particles can be codeposited in the Ni-Co matrix.The codeposition of Fe2O3 particles with Ni-Co is favoured at high Fe2O3 particle concentration and medium stirring,and the deposition of Co is favoured at high concentration of CTAB.Moreover,the study of the textural perfection of the deposits reveals that the presence of particles leads to the worsening of the quality of the observed preferred orientation.Composites with high concentration of embedded particles exhibit a preferred crystal orientation of .The more the embedded Fe2O3 particles in the metallic matrix,the smaller the sizes of the crystallite for the composite deposits.

  16. Fabrication and characteristics of spindle Fe2O3@Au core/shell particles

    Institute of Scientific and Technical Information of China (English)

    SHEN Hong-xia; YAO Jian-lin; GU Ren-ao

    2009-01-01

    The fabrication and characteristics of spindle Fe2O3@Au core/shell particle were investigated, and the effect of the core/shell nanoparticles as the surface enhanced Raman spectroscopy (SERS)-active substrates was studied. By using the seed-catalyzed reduction technique, anisotropic Fe2O3@Au core/shell particles with spindle morphology were successfully prepared. The Fe2O3 particles with spindle morphology were initially prepared as original cores. The Au nanoparticles of 2 nm were attached onto the Fe2O3 particles through organosilane molecules. Uniform Au shell formed onto Fe2O3 core modified by Au nanoparticles through the in-situ reduction of HAuCl4. The shell thickness was controlled through regulating the concentration of HAuCl4 solution. The results of TEM, XRD and UV-vis characterization show that the core/shell particles with the original shape of the Fe2O3 particles are obtained and these surfaces are covered by Au shell completely. The surface enhanced Raman spectrum of the probe molecules adsorbed on these core/shell substrates is strong and the intensity is enhanced with the increase of the thickness of Au shell or the aspect ratio of particles. The spindle Fe2O3@Au core/shell particles exhibit optimum (SERS) activity.

  17. Application of Al/B/Fe2O3 Nano Thermite in Composite Solid Propellant

    Directory of Open Access Journals (Sweden)

    Jingke Deng

    2016-03-01

    Full Text Available Hydroxyl-terminated polybutadiene (HTPB propellant were prepared with different content of Al/B/Fe2O3 nano thermite, and the mechanical, thermal and energetic performances were studied. Al/B/Fe2O3 nano thermite exhibited good compatibility with HTPB and dioctyl sebacate (DOS through differential scanning calorimetry (DSC tests. Mechanical experiments show that the mechanical properties of HTPB propellant could be improved by the addition of a small quantity of Al/B/Fe2O3 nano thermite, compared with the absence of Al/B/Fe2O3 nano thermite. For example, with the addition of 3% Al/B/Fe2O3 nano thermite, the tensile strength and elongation of propellant had the increase of 15.3% and 32.1%, respectively. Thermal analysis indicated that the decomposition of ammonium perchlorate (AP in HTPB propellant could be catalyzed by Al/B/Fe2O3 nano thermite, the high-temperature exothermic peak of AP was shifted to lower temperature by 70.8 °C when the content of Al/B/Fe2O3 nano thermite was 5%, and the heat released was enhanced by 70%. At the same time, the heat of explosion of HTPB propellant could also be enhanced by the addition of Al/B/Fe2O3 nano thermite. Copyright © 2016 BCREC GROUP. All rights reserved  Received: 5th November 2015; Revised: 4th December 2015; Accepted: 30th December 2015 How to Cite: Deng, J., Li, G., Shen, L., Luo, Y. (2016. Application of Al/B/Fe2O3 Nano Thermite in Composite Solid Propellant. Bulletin of Chemical Reaction Engineering & Catalysis, 11 (1: 109-114. (doi:10.9767/bcrec.11.1.432.109-114 Permalink/DOI: http://dx.doi.org/10.9767/bcrec.11.1.432.109-114

  18. UV-Vis and Surface Photovoltage Spectra of Fe2O3/Polystyrene Composite Microspheres

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Fe2O3 sol with the particle diameter of 3-5 nm was flocculated by the addition of SDS, and the flocculate formed was redispersed by the further addition of that surfactant. Thus the surfactant bilayer was formed on the surface of Fe2O3. The emulsion polymerization of styrene(St) adsolubilized on the surfactant adsorbed bilayer was carried out by initiator potassium persulfate(KPS). The UV-Vis and surface photovoltage spectra(SPS) indicate that the Fe2O3 particles were encapsulated in polystyrene(PSt) successfully.

  19. Facile preparation of α-Fe2O3 nanobulk via bubble electrospinning and thermal treatment

    Directory of Open Access Journals (Sweden)

    Liu Peng

    2016-01-01

    Full Text Available In this work, α-Fe2O3 nanobulk with high aspect ratio were successfully prepared via a facile bubble electrospinning technique using polyvinylidene fluoride and iron chloride hexahydrate (FeCl3•6H2O as α-Fe2O3 precursor followed by annealing in air at 600°C. The products were characterized with field emission scanning electron microscope, Fourier transform infrared, X-ray photoelectron spectroscopy, and thermogravimetric analysis. The results showed that α-Fe2O3 nanobulk has a hierarchical heterostructure which has an extremely broad application prospect in many areas.

  20. Mechanical alloying of an immiscible α-Fe2O3-SnO2 ceramic

    DEFF Research Database (Denmark)

    Jiang, Jianzhong; Lin, Rong; Mørup, Steen

    1997-01-01

    in the immiscible ceramic oxide system. X-ray diffraction and Mossbauer spectroscopy investigations show that mechanical milling of alpha-Fe2O3 and SnO2 involves alloying on an atomic scale and that true solid solution formation occurs. We suggest that the high defect concentration and the chemical enthalpy of Fe3......+-O2--Sn4+ interfaces between nanostructured alpha-Fe2O3 and SnO2 regions may serve as a driving force for the formation of a solid solution in the immiscible ceramic system.......A solid solution of about 6 mol% SnO2 in alpha-Fe2O3 has been prepared by mechanical alloying of alpha-Fe2O3 and SnO2 powder blends. This result demonstrates that high energy ball milling can be used to prepare metastable oxide solid solutions with an extended range of compositions...

  1. Synthesis and magnetic properties of CdS/α-Fe2O3 hierarchical nanostructures

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    CdS/α-Fe2O3 hierarchical nanostructures, where the CdS nanorods grow irregularly on the side surface of α-Fe2O3 nanorods, were synthesized via a three-step process. The diameters and lengths of CdS nanorods can be tuned by changing the ethylenediamine (EDA) and Cd ion concentrations. The magnetic investigations by superconducting quantum interference device indicate that the hierarchical nanostructures have an Morin transition at lower temperature (230 K) than that of the single bulk α-Fe2O3 materials (263 K). Importantly, the hierarchical nanostructures exhibit weakly ferromagnetic characteristics at 300 K. A sharp peak assigned to the surface trap induced emission are observed in room temperature PL spectra. Combining with the optoelectronic properties of CdS, the CdS/ α-Fe2O3 hierarchical nanostructures may be used as multi-functional materials for optoelectronic and magnetic devices.

  2. Synthesis and magnetic properties of CdS/α-Fe2O3 hierarchical nanostructures

    Institute of Scientific and Technical Information of China (English)

    CHEN YuJin; SHI XiaoLing; CAO MaoSheng; ZHU ChunLing

    2009-01-01

    CdS/α-Fe2O3 hierarchical nanostructures, where the CdS nanorods grow irregularly on the side surface of α-Fe2O3 nanorods, were synthesized via a three-step process. The diameters and lengths of CdS nanorods can be tuned by changing the ethylenediamine (EDA) and Cd ion concentrations. The mag-netic investigations by superconducting quantum interference device indicate that the hierarchical nanostructures have an Morin transition at lower temperature (230 K) than that of the single bulk α-Fe2O3 materials (263 K). Importantly, the hierarchical nanostructures exhibit weakly ferromagnetic characteristics at 300 K. A sharp peak assigned to the surface trap induced emission are observed in room temperature PL spectra. Combining with the optoelectronic properties of CdS, the CdS/α-Fe2O3 hierarchical nanostructures may be used as multi-functional materials for optoelectronic and magnetic devices.

  3. Effect of Fe2O3 on the physical and structural properties of bismuth silicate glasses

    Science.gov (United States)

    Parmar, Rajesh; Kundu, R. S.; Punia, R.; Aghamkar, P.; Kishore, N.

    2013-06-01

    Iron containing bismuth silicate glasses with compositions 70SiO2ṡ(100-x)Bi2O3ṡxFe2O3 have been prepared using conventional melt-quenching method and their amorphous nature has been investigated using XRD. Density has been measured using Archimedes' principle and molar volume (Vm) have also been estimated. With increase in Fe2O3 content, there is a decrease in density and molar volume of the glass samples. The glass transition temperature (Tg) have been determined using Differential Scanning Calorimetry (DSC) and are observed to increase with increase in Fe2O3 content. In the present glass system bismuth and iron plays the role of network modifier and the symmetry of silicate network goes on increasing with Fe2O3 content and it modifies the physical and structural properties of these glasses.

  4. Defect-induced enhanced photocatalytic activities of reduced α-Fe2O3 nanoblades

    Science.gov (United States)

    Feng, Honglei; Wang, Yiqian; Wang, Chao; Diao, Feiyu; Zhu, Wenhui; Mu, Peng; Yuan, Lu; Zhou, Guangwen; Rosei, Federico

    2016-07-01

    Bicrystalline α-Fe2O3 nanoblades (NBs) synthesized by thermal oxidation of iron foils were reduced in vacuum, to study the effect of reduction treatment on microstructural changes and photocatalytic properties. After the vacuum reduction, most bicrystalline α-Fe2O3 NBs transform into single-layered NBs, which contain more defects such as oxygen vacancies, perfect dislocations and dense pores. By comparing the photodegradation capability of non-reduced and reduced α-Fe2O3 NBs over model dye rhodamine B (RhB) in the presence of hydrogen peroxide, we find that vacuum-reduction induced microstructural defects can significantly enhance the photocatalytic efficiency. Even after 10 cycles, the reduced α-Fe2O3 NBs still show a very high photocatalytic activity. Our results demonstrate that defect engineering is a powerful tool to enhance the photocatalytic performance of nanomaterials.

  5. Synthesis and Characterization of Bifunctional α-Fe2O3-Ag Nanoparticles

    Directory of Open Access Journals (Sweden)

    Alvaro Ruíz-Baltazar

    2015-01-01

    Full Text Available The synthesis of α-Fe2O3-Ag bimetallic nanoparticles using a novel and simplified route is presented in this work. These hybrid nanoparticles were produced using a modification of the chemical reduction method by sodium borohydride (NaBH4. Fe(III chloride hexahydrate (FeCl3·6H2O and silver nitrate (AgNO3 as precursors were employed. Particles with semispherical morphology and dumbbell configuration were observed. High-resolution transmission electron microscopy (HRTEM technique reveals the structure of the dumbbell-like α-Fe2O3-Ag nanoparticles. Some theoretical models further confirm the formation of the α-Fe2O3-Ag structures. Analysis by cyclic voltammetry reveals an interesting catalytic behavior which is associated with the combination of the individual properties of the Ag and α-Fe2O3 nanoparticles.

  6. Preparation and Thermo-Physical Properties of Fe2O3-Propylene Glycol Nanofluids.

    Science.gov (United States)

    Shylaja, A; Manikandan, S; Suganthi, K S; Rajan, K S

    2015-02-01

    Iron oxide (Fe2O3) nanoparticles were prepared from ferric chloride and ferrous sulphate by precipitation reaction. Fe2O3-propylene glycol nanofluid was prepared by dispersing Fe2O3 nanoparticles in propylene glycol through stirred bead milling, shear homogenization and probe ultrasonication. The nanofluid was characterized through measurement of viscosity, particle size distribution and thermal conductivity. The interactions between Fe2O3 nanoparticles and propylene glycol on the nanoparticle surfaces lead to reduction in viscosity, the magnitude of which increases with nanoparticle concentration (0-2 vol%) at room temperature. The thermal conductivity enhancement for 2 vol% nanofluid was about 21% at room temperature, with liquid layering being the major contributor for thermal conductivity enhancement.

  7. Synthesis and characterization of ring-like α-Fe2O3

    Science.gov (United States)

    Li, Lili; Chu, Ying; Liu, Yang

    2007-03-01

    A novel ring-like α-Fe2O3 with a cave at the centre was first synthesized via the redox reaction of Fe2+ with S2O82- in solution. The samples were characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), x-ray diffraction (XRD) and vibrating sample magnetometry (VSM). The possible mechanisms of shape evolution for the formation of ring-like α-Fe2O3 were discussed. Magnetic hysteresis measurements revealed that the ring-like α-Fe2O3 display a magnetic behaviour with a coercivity of 1690 Oe at room temperature. The photocatalytic degradation of salicylic acid revealed that ring-like α-Fe2O3 exhibits a photocatalytic property.

  8. Controlled Synthesis and Magnetic Properties of Uniform Hierarchical Polyhedral α-Fe2O3 Particles

    Science.gov (United States)

    Long, Nguyen Viet; Yang, Yong; Thi, Cao Minh; Phuc, Le Hong; Nogami, Masayuki

    2017-02-01

    The controlled synthesis of uniform hierarchical polyhedral iron (Fe) micro-/nanoscale oxide particles with the α-Fe2O3 structure is presented. The hierarchical polyhedral iron oxide particles were synthesized by modified polyol methods with sodium borohydride as a powerful and efficient reducing agent. A critical heat treatment process used during the synthesis allowed for the interesting formation of α-Fe2O3 hematite with a micro-/nanoscale structure. The structure and weak ferromagnetism of the α-Fe2O3 particles were investigated by x-ray diffraction with whole pattern fitting and Rietveld refinement, scanning electron microscopy, and by vibrating sample magnetometry. The as-prepared α-Fe2O3 particles and the three dimensional models presented have promising practical applications for energy storage and conversion in batteries, capacitors, and fuel cells, and related spintronic devices and technologies.

  9. Hydrothermal Synthesis and Characterization of Cobalt Doped α-Fe2O3

    Science.gov (United States)

    Suresh, R.; Vijayalakshmi, L.; Stephen, A.; Narayanan, V.

    2010-10-01

    Nanocrystalline pure and Co-doped α-Fe2O3 were obtained via the hydrolysis of FeCl3 in the temperature range from 90 to 95 °C under reflux condition for 8 h and the precipitate (FeOOH) is annealed at 600 °C for 6 h. The samples are characterized by various techniques. FTIR spectrum of the samples confirmed the formation of Fe2O3. The XRD studies show that the formation of pure α-Fe2O3 without any impurity phases. Both XRD and SEM micrograph of the samples show that the increase in cobalt concentration can effectively increases the agglomeration of the particles. The EDS spectrum of the samples show that the increase in concentration of cobalt increases the doping amount of the cobalt in α-Fe2O3

  10. Thermal Recycling of Brominated Flame Retardants with Fe2O3.

    Science.gov (United States)

    Altarawneh, Mohammednoor; Ahmed, Oday H; Jiang, Zhong-Tao; Dlugogorski, Bogdan Z

    2016-08-04

    Plastics containing brominated flame retardants (BFRs) constitute the major fraction of nonmetallic content in e-waste. Co-pyrolysis of BFRs with hematite (Fe2O3) represents a viable option for the thermal recycling of BFRs. Consensus of experimental findings confirms the excellent bromine fixation ability of Fe2O3 and the subsequent formation of iron bromides. This contribution provides a comprehensive mechanistic account of the primary reactions between a cluster model of Fe2O3 and major bromine-bearing products from the decomposition of tetrabromobisphenol A (TBBA), the most commonly deployed BFR. We estimate the thermo-kinetic parameters for interactions of Fe2O3 with HBr, brominated alkanes and alkenes, bromobenzene, and bromophenol. Dissociative addition of HBr at a Fe-O bond proceeds through a trivial barrier of 8.2 kcal/mol with fitted parameters in the Arrhenius equation of k(T) = 7.96 × 10(11) exp(-6400/RT) s(-1). The facile and irreversible nature for HBr addition to Fe2O3 accords with the experimentally reported 90% reduction in HBr emission when Fe2O3 interacts with TBBA pyrolysates. A detailed kinetic analysis indicates that, transformation of Fe2O3 into iron bromides and oxybromides occurs via successive addition of HBr to Fe(Br)-O(H) entities. Elimination of a water molecule proceeds through an intramolecular H transfer. A direct elimination one-step mechanism operates in the dehydrohalogenation of bromoethane into ethene over Fe2O3. Dissociative decomposition and direct elimination channels assume comparable reaction rates in formation of acetylene from vinyl bromide. Results from this study provide an atomic-based insight into a promising thermal recycling route of e-waste.

  11. X-RAY DEBYE TEMPERATURE STUDY OF Fe2O3 NANOPARTICLES

    OpenAIRE

    2012-01-01

    Fe2O3 nanoparticle powders have been prepared by a chemical route synthesis. The resulting nanoparticle powders were characterized by X-ray diffraction (XRD) and scanning electron microscope (SEM). The Debye temperature, mean-square amplitudes of vibration, Debye-Waller factor, particle size, lattice strain, and vacancy formation of energies of Fe2O3 nanoparticles prepared by chemical route synthesis have been obtained from Xray integrated intensities. The integrated intensities have been mea...

  12. Uses of -Fe2O3 and fly ash as solid adsorbents

    Indian Academy of Sciences (India)

    J Shakhapure; H Vijayanand; S Basavaraja; V Hiremath; A Venkataraman

    2005-12-01

    Solid adsorbents have shown great promise for control of particulate and non-particulate matter and as gas sensing devices in recent times. In the present study, adsorption of environmental toxic pollutant such as lead ions on solid adsorbents viz. -Fe2O3 and fly ash, are reported. Considerable adsorption was observed on fly ash when compared to -Fe2O3 surface. These studies are characterized by employing solid state and solution studies.

  13. Fe2O3-Modified Porous BiVO4 Nanoplates with Enhanced Photocatalytic Activity

    Institute of Scientific and Technical Information of China (English)

    Ping Cai; Shu-Mei Zhou; De-Kun Ma; Shen-Nan Liu; Wei Chen; Shao-Ming Huang

    2015-01-01

    As BiVO4 is one of the most popular visible-light-responding photocatalysts, it has been widely used for visible-light-driven water splitting and environmental purification. However, the typical photocatalytic activity of unmodified BiVO4 for the degradation of organic pollutants is still not impressive. To address this limitation, we studied Fe2O3-modified porous BiVO4 nanoplates. Compared with unmodified BiVO4, the Fe2O3-modified porous BiVO4 nanoplates showed significantly enhanced photocatalytic activities in decomposing both dye and colorless pollutant models, such as rhodamine B (RhB) and phenol, respectively. The pseudo-first-order reaction rate constants for the degradation of RhB and phenol on Fe2O3-modified BiVO4 porous nanoplates are 27 and 31 times larger than that of pristine BiVO4, respectively. We also found that the Fe2O3 may act as an efficient non-precious metal co-catalyst, which is responsible for the excellent photocatalytic activity of Fe2O3/BiVO4. Graphical Abstract Fe2O3, as a cheap and efficient co-catalyst, could greatly enhance the photocatalytic activity of BiVO4 porous nanoplates in decomposing organic pollutants.

  14. Facile synthesis of porous Fe2O3 nanorods and their photocatalytic properties

    Directory of Open Access Journals (Sweden)

    Xiaosi Liu

    2015-09-01

    Full Text Available Porous Fe2O3 nanorods were obtained using a facile chemical solution method with subsequent calcination. The structures and morphological evolution were characterized by X-ray diffraction, field emission scanning electron microscopy, thermogravimetric-differential thermal analysis, and Brunauer–Emmett–Teller (BET N2 adsorption–desorption analyses. The calculated BET surface area of the porous Fe2O3 nanorods was 18.8 m2 g−1. The porous Fe2O3 nanorods were used as a catalyst to photodegrade Rhodamine B, methylene blue, methyl orange, p-nitrophenol, and eosin B. Compared to the commercial Fe2O3 powder, the as-prepared porous Fe2O3 nanorods exhibited higher catalytic activities owing to their large surface areas and porous nanostructures. The photocatalytic reaction rate constant of the porous Fe2O3 nanorods in the photocatalytic decomposition of Rhodamine B under simulated solar light was calculated to be 0.0131 min−1. Moreover, the catalyst was found to have superior stability and reusability.

  15. Investigation of genotoxic potential of various sizes Fe2O3 nanoparticles with comet assay

    Directory of Open Access Journals (Sweden)

    İbrahim Hakkı Ciğerci

    2015-06-01

    In this study, genotoxic potential of <50 nm and <100 nm Fe2O3 nanoparticles were investigated by using Comet Assay. Allium cepa root meristems were exposed with five doses (0.001, 0.01, 0.1, 1, 10 mM of <50 nm for 4 hour and three doses (2.5, 5 (EC50, 10 mM for <100 nm of Fe2O3 nanoparticle for 24 and 96 h. Methyl methanesulfonate -MMS (10 ppm was used as a positive control. The results were also analyzed statistically by using SPSS by Windows, 18.0. It was determined that different doses of <50 nm Fe2O3 nanoparticle have no genotoxic effect of DNA. Different doses of <100 nm Fe2O3 have no genotoxic but only 10 mM dose have genotoxic effect on DNA. When compared <50 nm with <100 nm of Fe2O3 nanoparticle; <50 nm have more effects than <100 nm of Fe2O3 on DNA damage.

  16. Aqueous synthesis and enhanced photocatalytic activity of ZnO/Fe2O3 heterostructures

    Science.gov (United States)

    Achouri, Faouzi; Corbel, Serge; Aboulaich, Abdelhay; Balan, Lavinia; Ghrabi, Ahmed; Ben Said, Myriam; Schneider, Raphaël

    2014-10-01

    We report a facile synthesis of ZnO/Fe2O3 heterostructures based on the hydrolysis of FeCl3 in the presence of ZnO nanoparticles. The material structure, composition, and its optical properties have been examined by means of transmission electron microscopy, scanning electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy and diffuse reflectance UV-visible spectroscopy. Results obtained show that 2.9 nm-sized Fe2O3 nanoparticles produced assemble with ZnO to form ZnO/Fe2O3 heterostructures. We have evaluated the photodegradation performances of ZnO/Fe2O3 materials using salicylic acid under UV-light. ZnO/Fe2O3 heterostructures exhibited enhanced photocatalytic capabilities than commercial ZnO due to the effective electron/hole separation at the interfaces of ZnO/Fe2O3 allowing the enhanced hydroxyl and superoxide radicals production from the heterostructure.

  17. Three-dimensional graphene anchored Fe2O3@C core-shell nanoparticles as supercapacitor electrodes

    DEFF Research Database (Denmark)

    Zhang, Miao; Sha, Junwei; Miao, Xiaoying

    2017-01-01

    Three-dimensional (3D) reduced graphene oxide (rGO) anchored carbon-coated Fe2O3 core-shell nanoparticles (Fe2O3@C-rGO) has been developed successfully through a simple one-pot hydrothermal process followed by a further annealing treatment. The 3D Fe2O3@C-rGO nanocomposite consists of carbon...

  18. Preparation of magnetic recoverable nanosize Cu-Fe2O3/Fe photocatalysts.

    Science.gov (United States)

    Kang, Hsu-Ya; Wang, H Paul

    2013-07-02

    Iron based catalysts generally have the advantage of the easily operated magnetically recovery from application sites. In the present work, paramagnetic iron and copper core-shell nanoparticles having the iron fractions (X(Fe) = Fe/(Cu+Fe)) of 0.33-1.0 were prepared and characterized by in situ synchrotron X-ray absorption and scattering spectroscopy. During the temperature-programmed carbonization (TPC) of Cu(2+)- and Fe(3+)-β-cyclodextrin (CD) complexes, a rapid reduction of Cu(II) occurs at about 453 K together with a growth of the metallic copper (Cu). Iron proceeds in the distinct growth path. At 453-513 K, the Fe(III) → Fe(II) → Fe consecutive reduction is observed. The unreduced Fe(III) (7-13%) is coated on the surfaces of the Fe nanoparticles (as Fe2O3/Fe). Growth of the Fe nanoparticle is inhibited by the surface Fe2O3, while the steady growth in Cu is observed. The Cu has a size range of 14-18 nm in diameter, compared to the small Fe2O3/Fe ones (3-6 nm). Under the UV-visible light irradiation for four hours, methylene blue can be photocatalytically degraded (>90%) by the (Cu-Fe2O3/Fe)@C. The (Cu-Fe2O3/Fe)@C photocatalysts can effectively oxidize dye molecules, providing a promising alternative for dye degradation using solar energy. Recovery of the (Cu-Fe2O3/Fe)@C photocatalysts can be attained by applying external magnetic field to trap the ferromagnetic Cu-Fe2O3/Fe nanoparticles, which suggests an economically attractive process, especially applied in photocatalytic degradation of dye-contaminated wastewater.

  19. Photocatalysis applications of some hybrid polymeric composites incorporating TiO2 nanoparticles and their combinations with SiO2/Fe2O3.

    Science.gov (United States)

    Chibac, Andreea Laura; Buruiana, Tinca; Melinte, Violeta; Buruiana, Emil C

    2017-01-01

    Polymer nanocomposites containing titanium oxide nanoparticles (TiO2 NPs) combined with other inorganic components (Si-O-Si or/and γ-Fe2O3) were prepared by the dispersion of premade NPs (nanocrystalline TiO2, TiO2/SiO2, TiO2/Fe2O3, TiO2/SiO2/Fe2O3) within a photopolymerizable urethane dimethacrylate (polytetrahydrofuran-urethane dimethacrylate, PTHF-UDMA). The physicochemical characterization of nanoparticles and hybrid polymeric composites with 10 wt % NPs (S1-S4) was realized through XRD, TEM and FTIR analyses. The mean size (10-30 nm) and the crystallinity of the NPs varied as a function of the inorganic constituent. The catalytic activity of these hybrid films was tested for the photodegradation of phenol, hydroquinone and dopamine in aqueous solution under UV or visible-light irradiation. The best results were obtained for the films with TiO2/Fe2O3 or TiO2/SiO2/Fe2O3 NPs. The degradation of the mentioned model pollutants varied between 71% and 100% (after 250 min of irradiation) depending on the composition of the hybrid film tested and the light applied (UV-visible light). Also, it was established that such hybrid films can be reused at least for five cycles, without losing too much of the photocatalytic efficiency (ca. 7%). These findings could have implications in the development of new nanocatalysts.

  20. Photocatalysis applications of some hybrid polymeric composites incorporating TiO2 nanoparticles and their combinations with SiO2/Fe2O3

    Science.gov (United States)

    Buruiana, Tinca; Melinte, Violeta; Buruiana, Emil C

    2017-01-01

    Polymer nanocomposites containing titanium oxide nanoparticles (TiO2 NPs) combined with other inorganic components (Si–O–Si or/and γ-Fe2O3) were prepared by the dispersion of premade NPs (nanocrystalline TiO2, TiO2/SiO2, TiO2/Fe2O3, TiO2/SiO2/Fe2O3) within a photopolymerizable urethane dimethacrylate (polytetrahydrofuran-urethane dimethacrylate, PTHF-UDMA). The physicochemical characterization of nanoparticles and hybrid polymeric composites with 10 wt % NPs (S1–S4) was realized through XRD, TEM and FTIR analyses. The mean size (10–30 nm) and the crystallinity of the NPs varied as a function of the inorganic constituent. The catalytic activity of these hybrid films was tested for the photodegradation of phenol, hydroquinone and dopamine in aqueous solution under UV or visible-light irradiation. The best results were obtained for the films with TiO2/Fe2O3 or TiO2/SiO2/Fe2O3 NPs. The degradation of the mentioned model pollutants varied between 71% and 100% (after 250 min of irradiation) depending on the composition of the hybrid film tested and the light applied (UV–visible light). Also, it was established that such hybrid films can be reused at least for five cycles, without losing too much of the photocatalytic efficiency (ca. 7%). These findings could have implications in the development of new nanocatalysts. PMID:28243566

  1. Hydrothermal synthesis of reduced graphene sheets/Fe2O3 nanorods composites and their enhanced electrochemical performance for supercapacitors

    Science.gov (United States)

    Yang, Wanlu; Gao, Zan; Wang, Jun; Wang, Bin; Liu, Lianhe

    2013-06-01

    Reduced graphene nanosheets/Fe2O3 nanorods (GNS/Fe2O3) composite has been fabricated by a hydrothermal route for supercapacitor electrode materials. The obtained GNS/Fe2O3 composite formed a uniform structure with the Fe2O3 nanorods grew on the graphene surface and/or filled between the graphene sheets. The electrochemical performances of the GNS/Fe2O3 hybrid supercapacitor were tested by cyclic voltammetry, electrochemical impedance spectroscopy, and galvanostatic charge-discharge tests in 6 M KOH electrolyte. Comparing with the pure Fe2O3 electrode, GNS/Fe2O3 composite electrode exhibits an enhanced specific capacitance of 320 F g-1 at 10 mA cm-2 and an excellent cycle-ability with capacity retention of about 97% after 500 cycles. The simple and cost-effective preparation technique of this composite with good capacitive behavior encourages its potential commercial application.

  2. Magnetism and thermal induced characteristics of Fe2O3 content bioceramics

    Science.gov (United States)

    Wu, Chun-Shiang; Hsi, Chi-Shiung; Hsu, Fang-Chi; Wang, Moo-Chin; Chen, Yung-Sheng

    2012-11-01

    Magnetic properties of Li2O-MnO2-CaO-P2O5-SiO2 (LMCPS) glasses doped with various amounts of Fe2O3 were investigated. There is a dramatic change in the magnetic property of pristine LMCPS after the addition of Fe2O3 and crystallized at 850 °C for 4 h. Both the electron paramagnetic resonance and magnetic susceptibility measurements showed that the glass ceramic with 4 at% Fe2O3 exhibited the coexistence of superparamagnetism and ferromagnetism at room temperature. When the Fe2O3 content was higher than 8 at%, the LMCPS glasses showed ferromagnetism behavior. The complex magnetic behavior is due to the distribution of (Li, Mn)ferrite particle sizes driven by the Fe2O3 content. The thermal induced hysteresis loss of the crystallized LMCPS glass ceramics was characterized under an alternating magnetic field. The energy dissipations of the crystallized LMCPS glass ceramics were determined by the concentration and Mn/Fe ratios of Li(Mn, Fe)ferrite phase formed in the glass ceramics.

  3. The Preparation and Biocompatibility Study on Fe2O3 Magnetic Nanoparticles Used in Tumor Hyperthermia

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Objective:To evaluate the in vitro and in vivo toxicity of self-prepared nanosized Fe2 O3, which has the potential implication in tumor hyperthermia. Methods:Fe2O3 nanoparticles were prepared by improving co-precipitation, which characterization was detected by TEM, XRD, CMIAS, EDS. MTT assay was used to evaluate the in vitro cytotoxicity test; hemolytic test was carried out to estimate whether it has blood toxicity;Fe2O3 suspended in sterile 0.9% NaCl was intraperitoneally injected into Kunming mouse to calculate the LD50; micronucleus (MN) were reckoned to identify whether it is genotoxic. Results :The nanoparticles are brown spherical particles with diameter ranging from 8 to 15 nm, which have good decentralization and stability. The experiments also showed that the toxicity of the material on mouse fibroblast (L-929) cell lines was 0 - 1 degree; it has no hemolysis activity; LD50 arrived at 5.45 g/kg-1 after intraperitoneal injection of 1 ml suspension; micronucleus test showed that it has no genotoxic effects either. Conclusion:The results showed that the Fe2O3 nanoparticles are prepared successfully, the self-prepared nanosized Fe2O3 is a kind of high biocompatibility materials and perhaps it is suitable for further application in tumor hyperthermia.

  4. Synthesis, characterization and magnetic properties of polyaniline/-Fe2O3 composites

    Indian Academy of Sciences (India)

    Syed Khasim; S C Raghavendra; M Revanasiddappa; K C Sajjan; Mohana Lakshmi; Muhammad Faisal

    2011-12-01

    Conducting polyaniline/-Fe2O3 (PANI/FE) composites have been synthesized using an in situ deposition technique by placing fine-graded -Fe2O3 in a polymerization mixture of aniline. The composites are characterized by using scanning electron microscopy (SEM), X-ray diffraction (XRD) and infrared (IR) spectroscopy. The electrical properties such as d.c. and a.c. conductivities are studied by sandwitching the pellets of these composites between the silver electrodes. It is observed that the conductivity increases up to a composition of 20 wt.% of -Fe2O3 in polyaniline and decreases thereafter. The initial increase in conductivity is attributed to the extended chain length of polyaniline, where polarons possess sufficient energy to hop between favourable sites. Beyond 20 wt.% of -Fe2O3 in polyaniline, the blocking of charge carrier hop occurs, reducing conductivity values. The magnetic properties such as hysteresis characteristics and normalized a.c. susceptibility are also measured, which show a strong dependence on content of -Fe2O3 in polyaniline. Because of superparamagnetic behaviour of these composites, they may find extensive technological applications, especially for absorbing and shielding applications in microwave frequencies.

  5. Mesoscopic bar magnet based on ɛ-Fe2O3 hard ferrite

    Science.gov (United States)

    Ohkoshi, Shin-Ichi; Namai, Asuka; Yamaoka, Takehiro; Yoshikiyo, Marie; Imoto, Kenta; Nasu, Tomomichi; Anan, Shizuka; Umeta, Yoshikazu; Nakagawa, Kosuke; Tokoro, Hiroko

    2016-06-01

    Ferrite magnets have a long history. They are used in motors, magnetic fluids, drug delivery systems, etc. Herein we report a mesoscopic ferrite bar magnet based on rod-shaped ɛ-Fe2O3 with a large coercive field (>25 kOe). The ɛ-Fe2O3-based bar magnet is a single crystal with a single magnetic domain along the longitudinal direction. A wide frequency range spectroscopic study shows that the crystallographic a-axis of ɛ-Fe2O3, which corresponds to the longitudinal direction of the bar magnet, plays an important role in linear and non-linear magneto-optical transitions, phonon modes, and the magnon (Kittel mode). Due to its multiferroic property, a magnetic-responsive non-linear optical sheet is manufactured as an application using an ɛ-Fe2O3-based bar magnet, resin, and polyethylene terephthalate. Furthermore, from the viewpoint of the large coercive field property, we demonstrate that a mesoscopic ɛ-Fe2O3 bar magnet can be used as a magnetic force microscopy probe.

  6. Mesoscopic bar magnet based on ε-Fe2O3 hard ferrite

    Science.gov (United States)

    Ohkoshi, Shin-ichi; Namai, Asuka; Yamaoka, Takehiro; Yoshikiyo, Marie; Imoto, Kenta; Nasu, Tomomichi; Anan, Shizuka; Umeta, Yoshikazu; Nakagawa, Kosuke; Tokoro, Hiroko

    2016-01-01

    Ferrite magnets have a long history. They are used in motors, magnetic fluids, drug delivery systems, etc. Herein we report a mesoscopic ferrite bar magnet based on rod-shaped ε-Fe2O3 with a large coercive field (>25 kOe). The ε-Fe2O3–based bar magnet is a single crystal with a single magnetic domain along the longitudinal direction. A wide frequency range spectroscopic study shows that the crystallographic a-axis of ε-Fe2O3, which corresponds to the longitudinal direction of the bar magnet, plays an important role in linear and non-linear magneto-optical transitions, phonon modes, and the magnon (Kittel mode). Due to its multiferroic property, a magnetic-responsive non-linear optical sheet is manufactured as an application using an ε-Fe2O3–based bar magnet, resin, and polyethylene terephthalate. Furthermore, from the viewpoint of the large coercive field property, we demonstrate that a mesoscopic ε-Fe2O3 bar magnet can be used as a magnetic force microscopy probe. PMID:27273575

  7. Hydrothermal synthesis and properties of controlled α-Fe2O3 nanostructures in HEPES solution.

    Science.gov (United States)

    Li, Hui; Lu, Zhong; Li, Qin; So, Man-Ho; Che, Chi-Ming; Chen, Rong

    2011-09-05

    A facile, template-free, and environmentally friendly hydrothermal strategy was explored for the controllable synthesis of α-Fe(2)O(3) nanostructures in HEPES solution (HEPES=2-[4-(2-hydroxyethyl)-1-piperazinyl]ethanesulfonic acid). The effects of experimental parameters including HEPES/FeCl(3) molar ratio, pH value, reaction temperature, and reaction time on the formation of α-Fe(2)O(3) nanostructures have been investigated systematically. Based on the observations of the products, the function of HEPES in the reaction is discussed. The different α-Fe(2)O(3) nanostructures possess different optical, magnetic properties, and photocatalytic activities, depending on the shape and size of the sample. In addition, a novel and facile approach was developed for the synthesis of Au/α-Fe(2)O(3) and Ag/α-Fe(2)O(3) nanocomposites in HEPES buffer solution; this verified the dual function of HEPES both as reductant and stabilizer. This work provides a new strategy for the controllable synthesis of transition metal oxide nanostructures and metal-supported nanocomposites, and gives a strong evidence of the relationship between the property and morphology/size of nanomaterials.

  8. Photoelectrochemical Properties of FeO Supported on TiO2-Based Thin Films Converted from Self-Assembled Hydrogen Titanate Nanotube Powders

    Directory of Open Access Journals (Sweden)

    Kyung-Jong Noh

    2012-01-01

    Full Text Available A photoanode was fabricated using hematite (α-Fe2O3 nanoparticles which had been held in a thin film of hydrogen titanate nanotubes (H-TiNT, synthesized by repetitive self-assembling method on FTO (fluorine-doped tin oxide glass, which were incorporated via dipping process in aqueous Fe(NO33 solution. Current voltage (I-V electrochemical properties of the photoanode heat-treated at 500°C for 10 min in air were evaluated under ultraviolet-visible light irradiation. Microstructure and crystallinity changes were also investigated. The prepared Fe2O3/H-TiNT/FTO composite thin film exhibited about threefold as much photocurrent as the Fe2O3/FTO film. The improvement in photocurrent was considered to be caused by reduced recombination of electrons and holes, with an appropriate amount of Fe2O3 spherical nanoparticles supported on the H-TiNT/FTO film. Nanosized spherical Fe2O3 particles with about 65 wt% on the H-TiNT/FTO film showed best performance in our study.

  9. Solvothermal synthesis and characterization of acicular -Fe2O3 nanoparticles

    Indian Academy of Sciences (India)

    S Basavaraja; D S Balaji; Mahesh D Bedre; D Raghunandan; P M Prithviraj Swamy; A Venkataraman

    2011-12-01

    Nanometer-sized -Fe2O3 particles have been prepared by a simple solvothermal method using ferric acetylacetonate as a precursor. The products were characterized by X-ray diffraction (XRD), energy dispersive X-ray microanalysis (EDAX), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), transition electron microscopy (TEM), infrared spectroscopy (IR) and thermal analysis (TG–DTA). XRD indicates that the product is single-phase -Fe2O3 with rhombohedral structure. Bundles of acicular shaped nanoparticles are seen in TEM images with an aspect ratio ∼ 12; typically 8–12 nm wide and over 150 nm long. The -Fe2O3 nanoparticles posses a high thermal stability, as observed on thermal analysis traces.

  10. Synthesis and Magnetic Properties of Maghemite (γ-Fe2O3 Short-Nanotubes

    Directory of Open Access Journals (Sweden)

    Xiao XH

    2010-01-01

    Full Text Available Abstract We report a rational synthesis of maghemite (γ-Fe2O3 short-nanotubes (SNTs by a convenient hydrothermal method and subsequent annealing process. The structure, shape, and magnetic properties of the SNTs were investigated. Room-temperature and low-temperature magnetic measurements show that the as-fabricated γ-Fe2O3 SNTs are ferromagnetic, and its coercivity is nonzero when the temperature above blocking temperature (TB. The hysteresis loop was operated to show that the magnetic properties of γ-Fe2O3 SNTs are strongly influenced by the morphology of the crystal. The unique magnetic behaviors were interpreted by the competition of the demagnetization energy of quasi-one-dimensional nanostructures and the magnetocrystalline anisotropy energy of particles in SNTs.

  11. SYNTHESIS AND PROPERTIES OF SUPERPARAMAGNETIC Y-Fe2O3

    Directory of Open Access Journals (Sweden)

    V.O. Kotsyubynsky

    2014-05-01

    Full Text Available Method of nanodispersed y-Fe2O3 synthesis by thermal decomposition of iron citrate is proposed. The investigations of obtained oxides crystal­line and magnetic structures are done. Nanodispersed y-Fe2O3 with sizes of coherent scattering regions about 4-7 nm was is only one phase after gel sintering at 200, 250 and 300оС; the particles of synthesized materials are in a state of magnetic ordering and in superparamagnetic state. The influence of mag­netic dipole interparticles interaction on parameters of Moss­bauer spectra is observed. The phenomenological mo­del of the differences between nanodispersed y-Fe2O3 magnetic micro­structures ob­tained after annealing at different tem­pe­ra­tu­res is presented.

  12. Facile hydrothermal route to the controlled synthesis of -Fe2O3 1-D nanostructures

    Indian Academy of Sciences (India)

    Lixia Yang; Ying Liang; Hou Chen; Lingyan Kong; Wei Jiang

    2008-12-01

    Single-crystalline -Fe2O3 1-D nanostructures can be obtained via a facile one-step hydrothermal synthetic route. It was found that the introduction of SnCl4 played a key role in determining the composition and morphology of -Fe2O3. The addition of SnCl4 favours the formation of Fe2O3 rather than FeOOH, and the morphology can be tuned from nanorod to double-shuttle as the increase of SnCl4 concentration. The products were characterized by X-ray powder diffraction (XRD), transmission electron microscopy (TEM) and selectedarea electron diffraction (SAED). This simple method does not need any seed, catalyst, or template, thus is promising for large-scale and low-cost production.

  13. Synthesis and Magnetic Properties of Maghemite (gamma-Fe(2)O(3)) Short-Nanotubes.

    Science.gov (United States)

    Wu, W; Xiao, X H; Zhang, S F; Peng, T C; Zhou, J; Ren, F; Jiang, C Z

    2010-06-17

    We report a rational synthesis of maghemite (gamma-Fe(2)O(3)) short-nanotubes (SNTs) by a convenient hydrothermal method and subsequent annealing process. The structure, shape, and magnetic properties of the SNTs were investigated. Room-temperature and low-temperature magnetic measurements show that the as-fabricated gamma-Fe(2)O(3) SNTs are ferromagnetic, and its coercivity is nonzero when the temperature above blocking temperature (T(B)). The hysteresis loop was operated to show that the magnetic properties of gamma-Fe(2)O(3) SNTs are strongly influenced by the morphology of the crystal. The unique magnetic behaviors were interpreted by the competition of the demagnetization energy of quasi-one-dimensional nanostructures and the magnetocrystalline anisotropy energy of particles in SNTs.

  14. Novel hollow α-Fe2O3 nanofibers via electrospinning for dye adsorption

    Science.gov (United States)

    Gao, Qiang; Luo, Jun; Wang, Xingyue; Gao, Chunxia; Ge, Mingqiao

    2015-04-01

    Nanomaterials such as iron oxides and ferrites have been intensively investigated for water treatment and environmental remediation applications. In this work, hollow α-Fe2O3 nanofibers made of rice-like nanorods were successfully synthesized via a simple hydrothermal reaction on polyvinyl alcohol (PVA) nanofiber template followed by calcination. The crystallographic structure and the morphology of the as-prepared α-Fe2O3 nanofibers were characterized by X-ray diffraction, energy dispersive X-ray spectrometer, and scanning electron microscope. Batch adsorption experiments were conducted, and ultraviolet-visible spectra were recorded before and after the adsorption to investigate the dye adsorption performance. The results showed that hollow α-Fe2O3 fiber assembles exhibited good magnetic responsive performance, as well as efficient adsorption for methyl orange in water. This work provided a versatile strategy for further design and development of functional nanofiber-nanoparticle composites towards various applications.

  15. Multifunctional Hybrid Fe2O3-Au Nanoparticles for Efficient Plasmonic Heating.

    Science.gov (United States)

    Murph, Simona E Hunyadi; Larsen, George K; Lascola, Robert J

    2016-02-20

    One of the most widely used methods for manufacturing colloidal gold nanospherical particles involves the reduction of chloroauric acid (HAuCl4) to neutral gold Au(0) by reducing agents, such as sodium citrate or sodium borohydride. The extension of this method to decorate iron oxide or similar nanoparticles with gold nanoparticles to create multifunctional hybrid Fe2O3-Au nanoparticles is straightforward. This approach yields fairly good control over Au nanoparticle dimensions and loading onto Fe2O3. Additionally, the Au metal size, shape, and loading can easily be tuned by changing experimental parameters (e.g., reactant concentrations, reducing agents, surfactants, etc.). An advantage of this procedure is that the reaction can be done in air or water, and, in principle, is amenable to scaling up. The use of such optically tunable Fe2O3-Au nanoparticles for hyperthermia studies is an attractive option as it capitalizes on plasmonic heating of gold nanoparticles tuned to absorb light strongly in the VIS-NIR region. In addition to its plasmonic effects, nanoscale Au provides a unique surface for interesting chemistries and catalysis. The Fe2O3 material provides additional functionality due to its magnetic property. For example, an external magnetic field could be used to collect and recycle the hybrid Fe2O3-Au nanoparticles after a catalytic experiment, or alternatively, the magnetic Fe2O3 can be used for hyperthermia studies through magnetic heat induction. The photothermal experiment described in this report measures bulk temperature change and nanoparticle solution mass loss as functions of time using infrared thermocouples and a balance, respectively. The ease of sample preparation and the use of readily available equipment are distinct advantages of this technique. A caveat is that these photothermal measurements assess the bulk solution temperature and not the surface of the nanoparticle where the heat is transduced and the temperature is likely to be higher.

  16. Enhanced bulk modulus and reduced transition pressure in gamma-Fe2O3 nanocrystals

    DEFF Research Database (Denmark)

    Jiang, Jianzhong; Olsen, J. Staun; Gerward, Leif

    1998-01-01

    Synchrotron radiation X-ray diffraction studies of gamma-Fe2O3 have been performed with emphasis on the pressure-induced phase transformation gamma(maghemite) - alpha(hematite) and the equation of state of the nanophase material. For gamma-Fe2O3 the bulk modulus has been found to increase from 203...... GPa for the bulk material to 305 GPa for 9 nm size crystals. At the same time the transition pressure decreases from 35 to 27 GPa. The reduced transition pressure is explained in terms of nucleation and growth, the larger volume change upon transition in the nanocrystalline material being the main...

  17. Microwave-Assisted Fabrication of γ-Fe2O3 Nanoparticles from

    Directory of Open Access Journals (Sweden)

    Mohammad Kooti

    2011-01-01

    Full Text Available Maghemite (γ-Fe2O3 nanoparticles which have a wide range of applications were fabricated by microwave heating of acetylacetonato iron (III precursor. The precursor is very easy to make, and on irradiation by microwave decomposes to maghemite nanoparticles. The as-prepared γ-Fe2O3 nanostructured has been characterized by X-ray powder diffraction, energy dispersive X-ray spectroscopy (EDX, scanning electron microscope (SEM and transmission electron microscopy (TEM techniques. The maghemite nanoparticles were obtained in high yield and purity and the average size of the particles was estimated to be about 13 nm.

  18. Synthesis, Characterization, and Magnetic Studies of α-Fe2O3 Nanoparticles

    Directory of Open Access Journals (Sweden)

    Avnish Kumar Arora

    2014-01-01

    Full Text Available Very fine nanosized metal oxide, namely, iron oxide (α-Fe2O3 has been synthesized by precipitation method using ammonia as precipitating agent and characterized by using XRD (X-ray diffraction, TGA/DTA, surface area measurement, transmission electron microscopy (TEM, and magnetic measurements techniques. XRD studies show that iron oxide was formed as α-Fe2O3 instead of the commonly formed magnetite nanoparticles (Fe3O4 or a mixture of magnetite (Fe3O4 and maghemite (γ-Fe2O3, cubic, and it has rhombohedral structure. Magnetic measurements showed that iron oxide has five unpaired electrons and is ferromagnetic in nature, Ms value being 1.7 emu/g. The particle size of the synthesized iron oxide was determined by TEM. TEM images show that the size of particles of Fe2O3 varied from 15 nm to 49 nm with average crystallite size 35 nm.

  19. Unconventional Synthesis of γ-Fe2O3: Excellent Low-Concentration Ethanol Sensing Performance

    Science.gov (United States)

    Naskar, Atanu; Narjinary, Mousumi; Kundu, Susmita

    2016-09-01

    This study reports on a simple unconventional procedure for synthesis of γ-Fe2O3 nanopowder and its fabrication as a resistive ethanol sensor. γ-Fe2O3 powder having an average particle size of ˜15 nm was prepared by thermal decomposition of iron(III) acetylacetonate. Platinum incorporation (0.5-1.5 wt.%) was also carried out for enhancing sensing performance. The powders were characterized using an x-ray diffractometer, x-ray photoelectron spectroscopy, Brunauer-Emmett-Teller surface area, field area scanning electron microscopy, transmission electron microscopy along with energy dispersion x-ray analyses. Sensor fabricated from pure γ-Fe2O3 exhibited excellent ethanol sensing performance at concentrations down to 1 ppm, having a great demand in medical diagnosis and food-processing industries. The response observed for pure γ-Fe2O3 (˜75% for 1 ppm ethanol) was enhanced ˜10% after 1 wt.% Pt impregnation. Sensors were quite stable and selective towards ethanol vapour detection. A possible mechanism for high sensing performance has been discussed.

  20. Unconventional Synthesis of γ-Fe2O3: Excellent Low-Concentration Ethanol Sensing Performance

    Science.gov (United States)

    Naskar, Atanu; Narjinary, Mousumi; Kundu, Susmita

    2017-01-01

    This study reports on a simple unconventional procedure for synthesis of γ-Fe2O3 nanopowder and its fabrication as a resistive ethanol sensor. γ-Fe2O3 powder having an average particle size of ˜15 nm was prepared by thermal decomposition of iron(III) acetylacetonate. Platinum incorporation (0.5-1.5 wt.%) was also carried out for enhancing sensing performance. The powders were characterized using an x-ray diffractometer, x-ray photoelectron spectroscopy, Brunauer-Emmett-Teller surface area, field area scanning electron microscopy, transmission electron microscopy along with energy dispersion x-ray analyses. Sensor fabricated from pure γ-Fe2O3 exhibited excellent ethanol sensing performance at concentrations down to 1 ppm, having a great demand in medical diagnosis and food-processing industries. The response observed for pure γ-Fe2O3 (˜75% for 1 ppm ethanol) was enhanced ˜10% after 1 wt.% Pt impregnation. Sensors were quite stable and selective towards ethanol vapour detection. A possible mechanism for high sensing performance has been discussed.

  1. Photocatalytic activity of titanium dioxide modified by Fe2O3 nanoparticles

    Science.gov (United States)

    Wodka, Dawid; Socha, Robert P.; Bielańska, Elżbieta; Elżbieciak-Wodka, Magdalena; Nowak, Paweł; Warszyński, Piotr

    2014-11-01

    Photocatalytic activity of Fe2O3/TiO2 composites obtained by precipitation was investigated. The composite material containing 1.0 wt% of iron(III) oxide nanoparticles was obtained by depositing Fe2O3 on the Evonic-Degussa P25 titania surface. SEM, XPS, DRS, CV and EIS techniques were applied to examine synthetized pale orange photocatalyst. The XPS measurements revealed that iron is present mainly in the +3 oxidation state but iron in the +2 oxidation state can be also detected. Electrochemical analysis indicated that surface modification of Degussa P25 by Fe2O3 causes the appearance of surface states in such a material. Nevertheless, based on the DRS measurement it was shown that iron(III) oxide nanoparticles modified the P25 spectral properties but they did not change the band gap width. The photocatalytic activity of Fe2O3/TiO2 composite was compared to photocatalytic activity of pristine P25 in photooxidation reaction of model compounds: oxalic acid (OxA) and formic acid (FA). Photodecomposition reaction was investigated in a batch reactor containing aqueous suspension of a photocatalyst illuminated by either UV or artificial sunlight (halogen lamp). The tests proved that nanoparticles deposited on titania surface triggers the increase in photocatalytic activity, this increase depends however on the decomposed substance.

  2. Hydrothermal Synthesis and Ammonia Sensing Properties of WO3/Fe2O3 Nanorod Composites

    Science.gov (United States)

    Dien, Nguyen Dac; Phuoc, Luong Huu; Hien, Vu Xuan; Vuong, Dang Duc; Chien, Nguyen Duc

    2017-01-01

    WO3 nanorods (NRs) and α-Fe2O3 NRs were fabricated by hydrothermal treatment. Composites of these materials were created by mixing with ratios of 1:2, 1:1 and 2:1 in weight. Morphology, structure and composition characteristics of the WO3/Fe2O3 NRs composites were characterized by scanning electron microscopy, x-ray diffraction and energy dispersive x-ray spectroscopy analyses. The results of sensing measurements indicated that the sensor based on WO3:Fe2O3 with the ratio of 2:1 exhibited fairly good sensitivity toward NH3 at 300°C and the sensor based on WO3:Fe2O3 with the ratio of 1:1 can be used as a NH3 sensor with an operating temperature of 350°C. Selectivity and response-recovery times are suitable for practical applications. Finally, the mechanism for the improvement in the gas-sensing property was discussed.

  3. Review on α-Fe2O3 based negative electrode for high performance supercapacitors

    Science.gov (United States)

    Nithya, V. D.; Arul, N. Sabari

    2016-09-01

    Supercapacitor is an electrochemical energy storage device which has drawn attention of the researchers in recent years due to its high power density and long cycle life. Recently, an enormous effort has been imposed to improve the energy density of supercapacitor and might be attained through asymmetric cell configuration that offer wider potential window. Until now, a significant advancement has been achieved in the fabrication of positive electrodes for asymmetric cell. Nevertheless, the electrochemical performance of negative electrode materials is less explored, especially Hematite (α-Fe2O3). The α-Fe2O3 has been proved to be a promising negative electrode in supercapacitor application due to its wide operating potential, high redox activity, low cost, abundant availability and eco-friendliness. In this review, we have chosen α-Fe2O3 as the negative electrode and discussed its latest research progress with emphasis on various surface engineering synthesis strategies such as, carbon, polymer, metal-metal oxide, and ternary based α-Fe2O3 composites for supercapacitor. Besides, the importance of their synergistic effects over the supercapacitive performance in terms of specific capacitance, energy density, power density, cycling life and rate capability are highlighted. Also, an extensive analysis of the literature about its symmetric/asymmetric cell performance is explored.

  4. TEXTURE FUNCTION IN γ-Fe2O3 MAGNETIC TAPES

    OpenAIRE

    Martinez, B.; Labarta, A.; Obradors, X.; Cusidó, J.; Tejada, J.

    1985-01-01

    The texture function of single domain γ-Fe2O3 particles belonging to magnetic tapes has been quantitatively evaluated by using data of Mössbauer spectroscopy and magnetic hysteresis loop measurements. It has been verified that the contribution of the terms having 1 > 4 can be neglected.

  5. Catalytic oxidation of gas-phase elemental mercury by nano-Fe2O3

    Institute of Scientific and Technical Information of China (English)

    Fanhai Kong; Jianrong Qiu; Hao Liu; Ran Zhao; Zhihui Ai

    2011-01-01

    Heterogeneous oxidation of gas-phase Hg0 by nano-Fe2O3 was investigated on a fixed bed reactor, and the effects of oxygen concentration, bed temperature, water vapour concentration and particle size have been discussed. The results showed that Hg0 could be oxidized by active oxygen atom on the surface of nano-Fe2O3 as well as lattice oxygen in nano-Fe2O3. Among the factors that affect Hg0 oxidation by nano-Fe2O3, bed temperature plays an important role. More than 40% of total mercury was oxidized at 300℃,however, the test temperature at 400℃ could cause sintering of nano-catalyst, which led to a lower efficiency of Hg0 oxidation. The increase of oxygen concentration could promote mercury oxidation and led to higher Hg0 oxidation efficiency. No obvious mercury oxidation was detected in the pure N2 atmosphere, which indicates that oxygen is required in the gas stream for mercury oxidation. The presence of water vapour showed different effects on mercury oxidation depending on its concentration. The lower content of water vapour could promote mercury oxidation, while the higher content of water vapour inhibits mercury oxidation.

  6. Synthesis and characterization of Fe2O3 nanoparticles by simple precipitation method

    Science.gov (United States)

    Sankadiya, Siyaram; Oswal, Nidhi; Jain, Pranat; Gupta, Nitish

    2016-04-01

    A simple and efficient synthesis of Iron-oxide nanoparticles was carried out by precipitation method using ferric chloride as precursor and ammonium hydroxide as a stabilizing agent at different calcination temperatures. The synthesized powder was characterized by powder X-Ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), Field Emission Scanning Electron Microscope (FE-SEM) and Transmission Electron Microscopy (TEM). X-ray diffraction indicated the formation hematite Fe2O3 structure. FTIR showed various functional groups of particles and absorption bands related to metal oxygen vibration modes. The heating temperatures were varied at 100 °C, 200°C, and 300°C. The Fe2O3 nanostructures with the average particle size of about 36.22 nm were prepared at 300°C for 4h. TEM study is also confirming the nanosize of Fe2O3 particle. This aqueous precipitation method gives a large scale production of Fe2O3 nanoparticles easily.

  7. Hierarchical hollow spheres of Fe2O3 @polyaniline for lithium ion battery anodes.

    Science.gov (United States)

    Jeong, Jae-Min; Choi, Bong Gill; Lee, Soon Chang; Lee, Kyoung G; Chang, Sung-Jin; Han, Young-Kyu; Lee, Young Boo; Lee, Hyun Uk; Kwon, Soonjo; Lee, Gaehang; Lee, Chang-Soo; Huh, Yun Suk

    2013-11-20

    Hierarchical hollow spheres of Fe2 O3 @polyaniline are fabricated by template-free synthesis of iron oxides followed by a post in- and exterior construction. A combination of large surface area with porous structure, fast ion/electron transport, and mechanical integrity renders this material attractive as a lithium-ion anode, showing superior rate capability and cycling performance.

  8. Relationship Between Iron Whisker Growth and Doping Amount of Oxide During Fe2O3 Reduction

    Science.gov (United States)

    Gong, Xuzhong; Zhao, Zhilong; Wang, Zhi; Zhang, Ben; Guo, Lei; Guo, Zhancheng

    2016-04-01

    Iron whisker growth during Fe2O3 doped with oxide reduced by CO was investigated by using in situ observation and scanning electron microscopy. The results indicated that the minimum doping amount (MDA) of various oxides, hindering the iron whisker growth, was different. The MDA of Al2O3, Li2O, Na2O, and K2O was 0.5, 0.4, 4, and 12 pct, respectively. From the reduction rate, it was found that Li2O, MgO, and Al2O3 had some suppressive effects on the Fe2O3 reduction process, thus, confining the growth of iron whisker. However, other oxides had some catalytic effects on the Fe2O3 reduction process (Fe2O3-Fe3O4-FeO-Fe), such as CaO, SrO, BaO, Na2O, and K2O. As long as their doping amount was enough, these oxides could inhibit the diffusion of the Fe atom. When the metal ionic radius in doped oxide was bigger than that of Fe3+, such as Ca2+, Sr2+, Ba2+, Na+, and K+, there were lots of spaces left in Fe2O3 doped with oxide after reduction, improving Fe atom diffusion. Consequently, their MDA was more than that of small radius to restrain the growth of iron whisker. Finally, the relationship between corresponding metal ionic radius, electron layer number, valence electron number, and MDA of oxide was expressed by using data fitting as follows: N_{{{{A}}y {{O}}x }} = 1.3 × 10^{ - 5} × {r_{{{{A}}^{x + } }}2 × √{n_{{{{A}}^{x + } }} } }/{f_{q }}

  9. Nanosized As2O3/Fe2O3 complexes combined with magnetic fluid hyperthermia selectively target liver cancer cells

    Institute of Scientific and Technical Information of China (English)

    Zi-Yu Wang; Jian Song; Dong-Sheng Zhang

    2009-01-01

    AIM: To study the methods of preparing the magnetic nano-microspheres of Fe2O3 and As2O3/Fe2O3 complexes and their therapeutic effects with magnetic fluid hyperthermia (MFH). METHODS: Nanospheres were prepared by chemical co-precipitation and their shape and diameter were observed. Hemolysis, micronucleus, cell viability, and LD50 along with other in vivo tests were performed to evaluate the Fe2O3 microsphere biocompatibility. The inhibition ratio of tumors after Fe2O3 and As2O3/Fe2O3 injections combined with induced hyperthermia in xenograft human hepatocarcinoma was calculated. RESULTS: Fe2O3 and As2O3/Fe2O3 particles were round with an average diameter of 20 nm and 100 nm as observed under transmission electron microscope. Upon exposure to an alternating magnetic field (AMF), the temperature of the suspension of magnetic particles increased to 41-51℃, depending on different particle concentrations, and remained stable thereafter. Nanosized Fe2O3 microspheres are a new kind of biomaterial without cytotoxic effects. The LD50 of both Fe2O3 and As2O3/Fe2O3 in mice was higher than 5 g/kg. One to four weeks after Fe2O3 and As2O3/Fe2O3 complex injections into healthy pig livers, no significant differences were found in serum AST, ALT, BUN and Cr levels among the pigs of all groups (P > 0.05), and no obvious pathological alterations were observed. After exposure to alternating magnetic fields, the inhibition ratio of the tumors was significantly different from controls in the Fe2O3 and As2O3/Fe2O3 groups (68.74% and 82.79%, respectively; P < 0.01). Tumors of mice in treatment groups showed obvious necrosis, while normal tissues adjoining the tumor and internal organs did not.CONCLUSION: Fe2O3 and As2O3/Fe2O3 complexes exerted radiofrequency-induced hyperthermia and drug toxicity on tumors without any liver or kidney damage. Therefore, nanospheres are ideal carriers for tumortargeted therapy.

  10. Enhanced Water Splitting by Fe2O3-TiO2-FTO Photoanode with Modified Energy Band Structure

    Directory of Open Access Journals (Sweden)

    Eul Noh

    2013-01-01

    Full Text Available The effect of TiO2 layer applied to the conventional Fe2O3/FTO photoanode to improve the photoelectrochemical performance was assessed from the viewpoint of the microstructure and energy band structure. Regardless of the location of the TiO2 layer in the photoanodes, that is, Fe2O3/TiO2/FTO or TiO2/Fe2O3/FTO, high performance was obtained when α-Fe2O3 and H-TiNT/anatase-TiO2 phases existed in the constituent Fe2O3 and TiO2 layers after optimized heat treatments. The presence of the Fe2O3 nanoparticles with high uniformity in the each layer of the Fe2O3/TiO2/FTO photoanode achieved by a simple dipping process seemed to positively affect the performance improvement by modifying the energy band structure to a more favorable one for efficient electrons transfer. Our current study suggests that the application of the TiO2 interlayer, together with α-Fe2O3 nanoparticles present in the each constituent layers, could significantly contribute to the performance improvement of the conventional Fe2O3 photoanode.

  11. 彩色铝粉Fe2O3/SiO2/Al的液相沉积制备与表征%Preparation and characterization of colored aluminum powder Fe2O3/SiO2/Al by liquid deposition

    Institute of Scientific and Technical Information of China (English)

    韩凯; 张赢超; 叶红齐

    2011-01-01

    采用分步液相沉积法在片状铝粉表面包覆SiO2与Fe2O3双层薄膜制备了具有金属光泽的彩色铝粉,以彩度与光泽度为主要评价指标,探讨Fe2O3用量与pH值对铝粉包覆效果的影响,利用原子力显微镜(AFM)、扫描电子显微镜(SEM)和X射线衍射(XRD)等手段对包覆前后的铝粉进行表征.结果表明:当SiO2包覆量为20%(质量分数)时,随着Fe2O3膜厚的增加,铝粉颜色由浅黄→金黄→红黄过渡,光泽度下降;当m(Fe2O3)∶m(SiO2)∶m(Al)=0.75∶0.2∶1时,铝粉具有良好的彩度与光泽度,铝粉表面粗糙度由5.05 nm增大到20.6 nm;反应过程pH值对Fe2O3包覆效果有重要影响,pH值宜控制在3.9~4.0;表面活性剂PVP的加入有利于提高Fe2O3膜层与SiO2和Al基体的结合力,从而提高颜色稳定性.%The colored aluminum flake powder with metallic luster was prepared by encapsulating SiO2 and Fe2O3 double-layer film via step liquid-phase deposition method. Using the chromaticity and gloss as the main targets, the influence of Fe2O3 amount and pH value on the coating effect was studied. The unencapsulated and encapsulated aluminum powders were characterized by AFM, SEM and XRD. The results show that when the amount of SiO2 is 20% (mass fraction), with the increase of Fe2O3 amount, the aluminum powder changed colors from pale-yellow to golden-yellow, and then to red-yellow, and the gloss is reduced. Under the condition of m(Fe2O3):m(SiO2):m(Al)= 0.75:0.2:1, the encapsulated sample has good chromaticity and gloss synchronously, and the surface roughness of the aluminum powder increases from 5.05 nm to 20.6 nm. Furthermore, pH value should be controlled between 3.9 to 4.0. The addition of PVP is helpful to improve the color stability property of the aluminum powder, the Fe2O3 film is firmly combined with SiO2 and Al.

  12. Controlled synthesis of α- and γ-Fe2O3 nanoparticles via thermolysis of PVA gels and studies on α-Fe2O3 catalyzed styrene epoxidation

    Directory of Open Access Journals (Sweden)

    Ruhul A. Bepari

    2017-01-01

    Full Text Available Fe2O3 nanoparticles with diameters in the 7–18 nm range have been synthesized via thermolysis of polyvinyl alcohol (PVA gels prepared under alkaline pH by adding Fe3+ ions into warm aqueous solutions of PVA. While calcinations at 400 °C, 500 °C and 600 °C give γ-Fe2O3 as the pure product, α-Fe2O3 is obtained by heating the gel at 700 °C. It is found that the calcination temperature has a pronounced effect on the nature of the oxide produced but has little effect on particle size. The resultant Fe2O3 nanomaterials are ferromagnetic with moderate coercivities. Preliminary investigations suggest that hematite (α-Fe2O3 nanoparticles effectively catalyze the epoxidation of styrene with tert-butyl hydroperoxide (TBHP as the terminal oxidant.

  13. Mechanical alloying in Fe2O3-MO (M: Zn, Ni, Cu, Mg) systems

    DEFF Research Database (Denmark)

    Jiang, Jianzhong; Gerward, Leif; Mørup, Steen

    1999-01-01

    of MFe2O4 ferrites are critically discussed. No significant with respect to ferrite formation rates was observed in open and closed containers used here. In the Fe2O3/ZnO system, a single ferrite phase can be synthesized but in other systems no significant amounts of ferrites are formed by high......Mechanical alloying processes in four Fe2O3MO (M: Zn, Ni, Cu, Mg) systems by high-energy ball milling from simple oxide powder mixtures in both open and closed tungsten carbide containers have been investigated by x-ray powder diffraction and Mossbauer spectroscopy. Mechanisms for the formation......-energy ball milling under the conditions used here. The dominant alloying mechanism depends on the interdiffusion at relatively low temperatures. The experimental results may also be explained by the crystal structures of the reactants and the ferrites....

  14. Sol-gel synthesis and characterization of α-Fe2O3 nanoparticles

    Science.gov (United States)

    Raja, K.; Mary Jaculine, M.; Jose, M.; Verma, Sunil; Prince, A. A. M.; Ilangovan, K.; Sethusankar, K.; Jerome Das, S.

    2015-10-01

    The α-Fe2O3 nanoparticles have been successfully synthesized via sol-gel technique. The lattice parameters, the lattice strain and crystallite size were investigated by X-ray diffraction (XRD) analysis. Fourier transform infrared spectroscopy (FT-IR) analysis has been carried out to confirm the presence of functional groups. Using UV-visible spectrum, the optical band gap energy is estimated as 2.55 eV. The morphology and chemical composition of the α-Fe2O3 nanoparticles were examined by high resolution scanning electron microscopy (HR-SEM) and energy dispersive X-ray diffraction analysis (EDX) respectively. The hysteresis loop was traced out using vibration sample magnetometer and the values of coercivity and saturation magnetization are found out to be 3891 G and 0.4193 emu/g respectively.

  15. The magnetic properties of antiferromagnetic nanoparticles: NiO and αFe2O3

    DEFF Research Database (Denmark)

    Bahl, Christian Robert Haffenden

    Nickel oxide (NiO) and hematite (a-Fe2O3), both antiferromagnets, have magnetic properties which at nanoscale differ from those of the bulk materials. With emphasis on NiO nanoparticles and comparisons with a-Fe2O3 nanoparticles these magnetic propertiesare studied by a range of experimental...... techniques: elastic and inelastic neutron scattering, Mössbauer spectroscopy, x-ray diffraction, transmission electron microscopy and vibrating sample magnetometry. Knowledge of the size and shape of thenanoparticles is an often neglected prerequisite for studies of their magnetic properties. The Ni......O nanoparticles are found to be plate shaped with the (111) planes as plate faces, a thickness of about 2.3 nm and a diameter of about 13 nm. The magneticstructure is similar to that of bulk NiO, with the spins confined in the (111) planes. Measurements of the spin dynamics reveal a value of the magnetic...

  16. Hydrothermal synthesis of monodisperse α-Fe2O3 hexagonal platelets

    Institute of Scientific and Technical Information of China (English)

    Dengfeng Peng; Sadeh Beysen; Qiang Li; Yanfei Sun; Linyu Yang

    2010-01-01

    Uniformly sized α-Fe2O3 hexagonal platelets were synthesized by a hydrothermal process using Fe(OH)3suspension and large amount of NaOH.The reaction products were characterized by X-ray diffraction(XRD),scanning electron microscopy(SEM),transmission electron microscopy(TEM),selected area electron diffraction(SAED),and a vibrating sample magnetometer(VSM).The results show that the hexagonal platelets are fine,monodisperse and consisting of single-crystals.The magnetic hysteresis(M-H)curve of the samples measured at room temperature indicates that the α-Fe2O3 micro-platelets exhibit ferromagnetic behaviors with relatively low coercivity.

  17. BOWL-SHAPED POLY(3,4-ETHYLENEDIOXYTHIOPHENE)/γ-Fe2O3 COMPOSITES WITH ELECROMAGNETIC FUNCTION

    Institute of Scientific and Technical Information of China (English)

    Zhi-ming Zhang; Yue Wang; Qiong Li; Liang-min Yu; Jadranka Travas-Sejdic; Li-juan Zhang

    2013-01-01

    In this paper,electromagnetic poly(3,4-ethylenedioxythiophene)/γ-Fe2O3 (PEDOT/γ-Fe2O3) micro-bowls,1-2 μm in diameter,were prepared by a simple environment-friendly process.In this method,the aqueous solution of cetyltrimethylammonium bromide (CTAB) instead of any organic solvent was used.FeCI3 acted as a source of FeIII for the formation of γ-Fe2O3 and as an oxidant for the polymerization of 3,4-ethylenedioxythiophene (EDOT).The bowl-shaped morphology of PEDOT/γ-Fe2O3 composites was strongly influenced by the concentration of CTAB,FeC12,ammonia solution and the reaction temperature.The saturation magnetization of PEDOT/γ-Fe2O3 micro-bowls increased with the increase of FeC12 concentration and reached 6.20 Am2/kg at the FeC12 concentration of 0.30 mol/L.The conductivity of the PEDOT/γ-Fe2O3 composites was in the range of 101 S/cm.The electrical and magnetic sources of PEDOT/γ-Fe2O3 micro-bowls were confirmed by SEM-EDX,TEM,XRD and XPS spectra.And the possible formation mechanism of PEDOT//γ-Fe2O3 was proposed.

  18. Dielectric, electrical and infrared studies of -Fe2O3 prepared by combustion method

    Indian Academy of Sciences (India)

    Vijay A Hiremath; A Venkataraman

    2003-06-01

    This paper reports the electrical and spectroscopic investigation of the gamma ferrite synthesized through combustion route. The electrical study and dielectric behaviour showed a typical ferrite nature for the samples. The $\\gamma \\rightarrow \\alpha $ transition is observed from the electrical conductivity data. Infrared spectral study showed the transition of a typical ferrite. The effect of the presence of -impurities in -Fe2O3 is also explained here.

  19. Faraday rotation enhancement of gold coated Fe2O3 nanoparticles: comparison of experiment and theory.

    Science.gov (United States)

    Dani, Raj Kumar; Wang, Hongwang; Bossmann, Stefan H; Wysin, Gary; Chikan, Viktor

    2011-12-14

    Understanding plasmonic enhancement of nanoscale magnetic materials is important to evaluate their potential for application. In this study, the Faraday rotation (FR) enhancement of gold coated Fe(2)O(3) nanoparticles (NP) is investigated experimentally and theoretically. The experiment shows that the Faraday rotation of a Fe(2)O(3) NP solution changes from approximately 3 rad/Tm to 10 rad/Tm as 5 nm gold shell is coated on a 9.7 nm Fe(2)O(3) core at 632 nm. The results also show how the volume fraction normalized Faraday rotation varies with the gold shell thickness. From the comparison of experiment and calculated Faraday rotation based on the Maxwell-Garnett theory, it is concluded that the enhancement and shell dependence of Faraday rotation of Fe(2)O(3) NPs is a result of the shifting plasmon resonance of the composite NP. In addition, the clustering of the NPs induces a different phase lag on the Faraday signal, which suggests that the collective response of the magnetic NP aggregates needs to be considered even in solution. From the Faraday phase lag, the estimated time of the full alignment of the magnetic spins of bare (cluster size 160 nm) and gold coated NPs (cluster size 90 nm) are found to be 0.65 and 0.17 μs. The calculation includes a simple theoretical approach based on the Bruggeman theory to account for the aggregation and its effect on the Faraday rotation. The Bruggeman model provides a qualitatively better agreement with the experimentally observed Faraday rotation and points out the importance of making a connection between component properties and the average "effective" optical behavior of the Faraday medium containing magnetic nanoparticles.

  20. Fe2O3 magnetic nanoparticles to enhance S. lycopersicum (tomato) plant growth and their biomineralization

    Science.gov (United States)

    Shankramma, K.; Yallappa, S.; Shivanna, M. B.; Manjanna, J.

    2016-10-01

    In the present study, we demonstrate magnetic iron (III) oxide nanoparticles (Fe2O3 NPs) uptake by the Solanum lycopersicum ( S. lycopersicum) plant. The S. lycopersicum seeds were coated with Fe2O3 NPs and allowed to germinate in moistened sand bed. The seedlings are observed for 20 days, and then, it was post-treated using different amounts of Fe2O3 NPs in hydroponic solution for 10 days. The plant was allowed to grow in green house for 3 months, and uptake of NPs through roots and translocation into different parts was studied. For this, we have segmented the plants and incubated with 10 % NaOH solution. It is found that the NPs are deposited preferentially in root hairs, root tips followed by nodal and middle zone of plant. The iron present in the whole plant was quantitatively estimated by treating dry biomass of the plant in acid. The Fe2+/Fetotal increased with increasing concentration of NPs and >45 % ferrous iron suggests the biomineralization of NPs due to rich phytochemicals in plants. We believe that the present study is useful to build a base line data for novel applications in agri-nanotechnology.

  1. One-step solid state synthesis of capped γ-Fe(2)O(3) nanocrystallites.

    Science.gov (United States)

    Zboril, R; Bakandritsos, A; Mashlan, M; Tzitzios, V; Dallas, P; Trapalis, Ch; Petridis, D

    2008-03-05

    The thermally induced solid state synthesis of soluble organophilic maghemite (γ-Fe(2)O(3)) nanocrystallites is described. The solvent-free one-step synthesis involves the reaction in the melt state of Fe(NO)(3)·9H(2)O and RCOOH (R = C(11)H(23), C(15)H(31)) at 240 °C. The method yields well-crystallized nanoparticles of γ-Fe(2)O(3) functionalized with the corresponding aliphatic acid. Transmission electron microscopy (TEM) and atomic force microscopy (AFM) observations reveal composite particles with faceted magnetic cores and average size of 20 nm, which are well capped with the surrounding organic sheath. The Fourier transform infrared (FT-IR) spectra and thermal analysis suggest a bimodal configuration of the organic shell including chemically coordinated and physisorbed molecules of aliphatic acid. The chemical bonding of the carboxylate groups to the surface iron atoms is also indicated by a paramagnetic doublet with unchanged area in the variable temperature Mössbauer spectra. The spinel γ-Fe(2)O(3) particles exhibit perfect structural and magnetic ordering, including the almost ideal ratio of octahedral to tetrahedral positions (5/3) and very low degree of spin canting, as confirmed by in-field Mössbauer spectroscopy. Magnetic measurements demonstrate the suitable properties required in various (bio)magnetic applications like superparamagnetic behavior at room temperature, high saturation magnetization achievable at low applied fields and suppressed magnetic interactions.

  2. Fe2O3 magnetic nanoparticles to enhance S. lycopersicum (tomato plant growth and their biomineralization

    Directory of Open Access Journals (Sweden)

    K. Shankramma

    2015-12-01

    Full Text Available Abstract In the present study, we demonstrate magnetic iron (III oxide nanoparticles (Fe2O3 NPs uptake by the Solanum lycopersicum (S. lycopersicum plant. The S. lycopersicum seeds were coated with Fe2O3 NPs and allowed to germinate in moistened sand bed. The seedlings are observed for 20 days, and then, it was post-treated using different amounts of Fe2O3 NPs in hydroponic solution for 10 days. The plant was allowed to grow in green house for 3 months, and uptake of NPs through roots and translocation into different parts was studied. For this, we have segmented the plants and incubated with 10 % NaOH solution. It is found that the NPs are deposited preferentially in root hairs, root tips followed by nodal and middle zone of plant. The iron present in the whole plant was quantitatively estimated by treating dry biomass of the plant in acid. The Fe2+/Fetotal increased with increasing concentration of NPs and >45 % ferrous iron suggests the biomineralization of NPs due to rich phytochemicals in plants. We believe that the present study is useful to build a base line data for novel applications in agri-nanotechnology.

  3. Fe2O3 Modified Physical, Structural and Optical Properties of Bismuth Silicate Glasses

    Directory of Open Access Journals (Sweden)

    Rajesh Parmar

    2013-01-01

    Full Text Available Iron-containing bismuth silicate glasses with compositions 60SiO2·(100−xBi2O3·xFe2O3 have been prepared by conventional melt-quenching technique. The amorphous nature of the glass samples has been ascertained by the X-ray diffraction. The density (d has been measured using Archimedes principle, molar volume (Vm has also been estimated, and both are observed to decrease with the increase in iron content. The glass transition temperature (Tg of these iron bismuth silicate glasses has been determined using differential scanning calorimetry (DSC technique, and it increases with the increase in Fe2O3 content. The IR spectra of these glasses consist mainly of [BiO6], [BiO3], and [SiO4] structural units. The optical properties are measured using UV-VIS spectroscopy. The optical bandgap energy (Eop is observed to decrease with the increase in Fe2O3 content, whereas reverse trend is observed for refractive index.

  4. Photoelectrochemical hydrogen production on α-Fe2O3 (0001): insights from theory and experiments.

    Science.gov (United States)

    Baltrusaitis, Jonas; Hu, Yong-Sheng; McFarland, Eric W; Hellman, Anders

    2014-01-01

    The photoelectrochemical (PEC) decomposition of organic compounds in wastewater is investigated by using quantum chemical (DFT) methods to evaluate alternatives to water splitting for the production of renewable and sustainable hydrogen. Methanol is used as a model organic species for the theoretical evaluations of electrolysis on the surface of the widely available semiconductor hematite, α-Fe2 O3 , a widely studied photocatalyst. Three different α-Fe2 O3 surface terminations were investigated, including the predominant surface found in aqueous electrolytes, (OH)3 R. The PEC oxidation of methanol is energetically downhill, producing CO2 and protons. The protons are reduced to hydrogen on the cathode. Experimental PEC measurements were also performed for several polyalcoholic compounds, glycerol, erythritol, and xylitol, on α-Fe2 O3 as the photocatalyst and showed high incident-photon-to-current-efficiencies (IPCE) that were much greater than those of water splitting. Interestingly, high IPCEs were observed for hydrogen production from polyalcohols in the absence of any applied bias, which was not thought to be possible on hematite. These results support the potential application of PEC for hydrogen production by using widely available hematite for the PEC oxidation of selected components of organic wastewater present in large quantities from anthropogenic and industrial sources.

  5. Large third-order optical nonlinearities in iron oxide thin films synthesized by reactive pulsed laser deposition

    Science.gov (United States)

    Mulenko, S. A.; Rudenko, V. I.; Liakhovetskyi, V. R.; Brodin, A. M.; Stefan, N.

    2016-10-01

    We report on a study of the third-order nonlinear optical properties of Fe2O3 thin films, grown by the method of laser deposition on silica (SiO2) substrates. The films were synthesized on substrates at different temperatures (293 K and 800 K) and under different oxygen pressures (0.1 Pa, 0.5 Pa, 1.0 Pa). The resulting films were amorphous, if grown on cold substrates (293 K), or polycrystalline otherwise. The third-order optical susceptibility χ(3) of the films was determined by the Z-scan method at the wavelengths of 1064 nm and 532 nm and the laser pulse width of 20 ns. Remarkably high χ(3) values on the order of 10-4 esu at 1064 nm are obtained. The results show that Fe2O3 thin films are promising nonlinear materials for contemporary optoelectronics.

  6. Photocurrent increase by metal modification of Fe2O3 photoanodes and its effect on photoelectrocatalytic hydrogen production by degradation of organic substances

    Science.gov (United States)

    Iervolino, Giuseppina; Tantis, Iosif; Sygellou, Lamprini; Vaiano, Vincenzo; Sannino, Diana; Lianos, Panagiotis

    2017-04-01

    The present work reports the investigation of photocurrent increase by metal modification of Fe2O3 photoanodes and its effect on photoelectrocatalytic hydrogen production using aqueous solutions containing various organic compounds. Fe2O3 photoanodes were prepared by the electrodeposition method. The efficiency of various metal modifiers of the hematite structure (Ti, Ni, Sn, Co and Cu) has been tested by monitoring the photoelectrochemical behavior of the ensuing photoanodes. Hydrogen production was monitored in an H-shaped reactor using pure and metal-modified hematite films deposited on FTO electrodes as photocatalyst while a combination of commercial carbon paste with dispersed Pt nanoparticles was used as electrocatalyst. In all cases, hydrogen production was obtained by application of a small external electric bias (in the range 0.5- 0.7 V vs Ag/AgCl electrode). Highest photocurrent production has been achieved with a Ti-modified Fe2O3 photoanode in the presence of glucose as sacrificial agent.

  7. Structural, optical and magnetic properties of porous alpha-Fe2O3 nanostructures prepared by rapid combustion method.

    Science.gov (United States)

    Manikandan, A; Vijaya, J Judith; Kennedy, L John

    2013-04-01

    Porous iron oxide (alpha-Fe2O3) nanoparticles were synthesized by the microwave combustion method (MCM) using urea as the fuel. For the purpose of comparison, it was also prepared using the conventional combustion method (CCM). The as-synthesized porous alpha-Fe2O3 nanoparticles were characterized by X-ray powder diffraction (XRD), high resolution scanning electron microscopy (HR-SEM), high resolution transmission electron microscopy (HR-TEM), energy dispersive X-ray analysis (EDX), diffuse reflectance spectroscopy (DRS), Brunauer-Emmett-Teller (BET) analysis and vibrating sample magnetometer (VSM) analysis. The XRD results confirmed the formation of rhombohedral alpha-Fe2O3 phase. The formation of alpha-Fe2O3 nanoparticles was confirmed by HR-SEM and HR-TEM, and their possible formation mechanisms were also proposed. The optical absorption and the band gap were determined by DRS spectra. The surface area was derived from the nitrogen adsorption-desorption isotherms using BET analysis. The magnetic properties of the synthesized alpha-Fe2O3 were investigated with vibrating sample magnetometer (VSM) and their hysteresis loops were obtained. Both the prepared samples show ferromagnetic behavior with hysteresis curve at room temperature. The relatively high saturation magnetization (65.23 emu/g) of alpha-Fe2O3-MCM suggests that this method is suitable for preparing high-quality nanocrystalline magnetic alpha-Fe2O3 for practical applications.

  8. Synthesis, Characterization and Gas Sensing Properties of Ag@α-Fe2O3 Core–Shell Nanocomposites

    Directory of Open Access Journals (Sweden)

    Ali Mirzaei

    2015-05-01

    Full Text Available Ag@α-Fe2O3 nanocomposite having a core–shell structure was synthesized by a two-step reduction-sol gel approach, including Ag nanoparticles synthesis by sodium borohydride as the reducing agent in a first step and the subsequent mixing with a Fe+3 sol for α-Fe2O3 coating. The synthesized Ag@α-Fe2O3 nanocomposite has been characterized by various techniques, such as SEM, TEM and UV-Vis spectroscopy. The electrical and gas sensing properties of the synthesized composite towards low concentrations of ethanol have been evaluated. The Ag@α-Fe2O3 nanocomposite showed better sensing characteristics than the pure α-Fe2O3. The peculiar hierarchical nano-architecture and the chemical and electronic sensitization effect of Ag nanoparticles in Ag@α-Fe2O3 sensors were postulated to play a key role in modulating gas-sensing properties in comparison to pristine α-Fe2O3 sensors.

  9. Heterogeneous photo-Fenton degradation of acid red B over Fe2O3 supported on activated carbon fiber.

    Science.gov (United States)

    Lan, Huachun; Wang, Aiming; Liu, Ruiping; Liu, Huijuan; Qu, Jiuhui

    2015-03-21

    Fe2O3 supported on activated carbon fiber (Fe2O3/ACF) was prepared via an impregnation method and characterized by X-ray diffraction, scanning electron microscopy and BET analysis. The results indicated that Fe2O3 with small particle size was highly dispersed on the surface of the ACF and the introduction of Fe2O3 did not change the ACF pore structure. Fe2O3/ACF exhibited a higher Fenton efficiency for the degradation of acid red B (ARB), especially under simulated solar irradiation. Complete decoloration of the ARB solution and 43% removal of TOC could be achieved within 200 min under optimal conditions. It was verified that more ˙OH radicals were generated in the photo-assisted Fenton process and involved as active species in ARB degradation. FTIR analysis indicated that the degradation of ARB was initiated through the cleavage of -N=N-, followed by hydroxylation and opening of phenyl rings to form aliphatic acids, and further oxidation of aliphatic acids would produce CO2 and H2O. Moreover, Fe2O3/ACF maintained its activity after being reused 4 times and the release of iron from the catalyst was found to be insignificant during the Fenton and photo-Fenton processes, indicating that Fe2O3/ACF had good long-term stability. Copyright © 2014 Elsevier B.V. All rights reserved.

  10. Facile synthesis of graphitic carbon nitride/nanostructured α-Fe2O3 composites and their excellent electrochemical performance for supercapacitor and enzyme-free glucose detection applications

    Science.gov (United States)

    Liu, Lin; Wang, Jinxiang; Wang, Chengyin; Wang, Guoxiu

    2016-12-01

    The graphitic carbon nitride (g-C3N4)/iron oxide (α-Fe2O3) composites have been prepared by a one-step pyrolysis of Prussian blue (PB) and melamine. The Fe2O3 nanoparticles derived from PB effectively protect the thin layers of g-C3N4 from restacking and expanding. The as-prepared g-C3N4/α-Fe2O3 composites exhibit a large specific surface area, and demonstrate their excellent electrochemical performance in the supercapacitor and non-enzymatic detection of glucose. The g-C3N4/α-Fe2O3 composites facilitate the faster faradic reaction in 1.0 M KOH electrolyte, and deliver the highest specific capacitance (580 F g-1) at the current density of 1.0 A g-1. The resultant composites also show an excellent long cycle life (up to 1000 cycles) at the current density of 2 A g-1. In addition, the modified electrode based on the g-C3N4/α-Fe2O3 hybrids are also used for the non-enzymatic detection of glucose. The as-fabricated modified electrode exhibits good electrochemical performance towards the oxidation of glucose with a response time devices and sensors.

  11. Atomic scale study of ball milled Ni-Fe2O3 using Mössbauer spectroscopy

    Science.gov (United States)

    Yadav, Ravi Kumar; Govindaraj, R.; Vinod, K.; Kumar, P. A. Manoj; Amarendra, G.

    2016-05-01

    Evolution of hyperfine fields at Fe atoms has been studied in a detailed manner in a mixture of Ni and α-Fe2O3 subjected to high energy ball milling using Mossbauer spectroscopy. Mossbauer results indicate the dispersion of α-Fe2O3 particles in Ni matrix in the as ball milled condition. Evolution of α-Fe2O3 due to ball milling, reduction of the valence of associated Fe and possible interaction between the oxide particles with Ni in the matrix due to annealing treatments has been elucidated in the present study.

  12. Synthesis of fluorine-doped α-Fe2O3 nanorods toward enhanced lithium storage capability

    Science.gov (United States)

    Wang, Chundong; Zhang, Yi; Li, Yi; Liu, Jiabin; Wu, Qi-Hui; Jiang, Jianjun; Li, Yang Yang; Lu, Jian

    2017-02-01

    Nanostructured fluorine-doped α-Fe2O3 nanorods were synthesized based on a one-step low temperature hydrothermal method. The XPS results verified that fluorine has been successfully incorporated into the hematite lattice. The delivered lithium capacity was effectively improved owing to the fluorine doping comparing with the pristine α-Fe2O3. The increase in electrochemical capacity of fluorine-doped α-Fe2O3 was then studied from the pointviews of nanostructure, electronic properties, and magnetic characteristics.

  13. Science Letters: Nitrogen doping of activated carbon loading Fe2O3 and activity in carbon-nitric oxide reaction

    Institute of Scientific and Technical Information of China (English)

    WAN Xian-kai; ZOU Xue-quan; SHI Hui-xiang; WANG Da-hui

    2007-01-01

    Nitrogen doping of activated carbon loading Fe2O3 was performed by annealing in ammonia, and the activity of the modified carbon for NO reduction was studied in the presence of oxygen. Results show that Fe2O3 enhances the amount of surface oxygen complexes and facilitates nitrogen incorporation in the carbon, especially in the form of pyridinic nitrogen. The modified carbon shows excellent activity for NO reduction in the low temperature regime (<500 ℃) because of the cooperative effect of Fe2O3 and the surface nitrogen species.

  14. Magnetic field-induced off-resonance third-order optical nonlinearity of iron oxide nanoparticles incorporated mesoporous silica thin films during heat treatment.

    Science.gov (United States)

    Cui, Fangming; Feng, Chude; Xie, Rongjun; Hua, Zile; Ohtsuka, Hideyuki; Sakka, Yoshio; Shi, Jianlin

    2010-02-01

    Highly dispersed and uniform Fe(2)O(3) nanoparticles (NPs) have been incorporated into the pore channels of SBA-15 mesoporous silica thin films (MSTFs). And such Fe(2)O(3) NPs incorporated MSTFs did not show detectable nonlinear optical (NLO) signals at off-resonance wavelength 1064 nm by Z-scan technique. However after a vacuum heat treatment at 800 degrees C for 1 h under 6 T magnetic field, the Fe(2)O(3) NPs incorporated MSTFs with very low Fe content (0.8 approximately 1.5 at.%) presented distinctive NLO signals with chi(3) value in an order of 10(-10) esu. We proposed the physical reason for the NLO property generation to be the magnetic domain orientation of the iron oxide NPs incorporated within the pore channels of the MSTFs by the magnetic field heat treatment.

  15. Catalysis of Nanometer α-Fe2O3 on the Thermal Decomposition of AP

    Institute of Scientific and Technical Information of China (English)

    YANG Yi; LI Feng-sheng; LIU Hong-ying; JIANG Wei; CUI Ping

    2005-01-01

    Nanometer α-Fe2O3 catalysts were prepared by hydrolyzation in high temperature. Three kinds of precipitators, NaOH, (NH4)2CO3 and urea were used to compare the effect in the process of hydrolyzation. Nanometer sizer, transmission electron microscopy (TEM) and X-ray diffraction (XRD) were employed to test the profiles and diameters of the product particles. The test results indicate that the production is nanometer α-Fe2O3 with narrow particle size distribution (PSD) and good dispersibility. The catalysts are mixed with ammonia perchlorate (AP) in 1.0 wt.%. And the composite particles of catalysts with AP are prepared using a new solvent-nonsolvent method. Differential thermal analyzer (DTA) is employed to analysis the thermal decomposition of the composite particles and pure AP sample. The results imply that the thermal decomposition curve peaks of the samples in which nanometer α-Fe2O3 catalysts are added appear comparatively more ahead than that of pure AP sample. Among these mixtures added nanometer material, the smaller the particle diameter of catalyst is, the more ahead the thermal decomposition curve peaks of AP appear. The high and low temperature thermal decomposition curve peaks of AP mixed with the catalyst deposed by urea are more ahead of 77.8℃ and 9.7℃ than that of pure AP, respectively. The mechanism of the catalyst deposed by urea with smaller diameter and the distinct catalysis of the particles on the thermal decomposition of AP are discussed.

  16. Impact of silica environment on hyperfine interactions in 𝜖-Fe2O3 nanoparticles

    Science.gov (United States)

    Kubíčková, Lenka; Kohout, Jaroslav; Brázda, Petr; Veverka, Miroslav; Kmječ, Tomáš; Kubániová, Denisa; Bezdička, Petr; Klementová, Mariana; Šantavá, Eva; Závěta, Karel

    2016-12-01

    Magnetic nanoparticles have found broad applications in medicine, especially for cell targeting and transport, and as contrast agents in MRI. Our samples of 𝜖-Fe2O3 nanoparticles were prepared by annealing in silica matrix, which was leached off and the bare particles were then coated with amorphous silica layers of various thicknesses. The distribution of particle sizes was determined from the TEM pictures giving the average size ˜20 nm and the thickness of silica coating ˜5; 8; 12; 19 nm. The particles were further characterized by the XRPD and DC magnetic measurements. The nanoparticles consisted mainly of 𝜖-Fe2O3 with admixtures of ˜1 % of the α phase and less than 1 % of the γ phase. The hysteresis loops displayed coercivities of ˜2 T at room temperature. The parameters of hyperfine interactions were derived from transmission Mössbauer spectra. Observed differences of hyperfine fields for nanoparticles in the matrix and the bare ones are ascribed to strains produced during cooling of the composite. This interpretation is supported by slight changes of their lattice parameters and increase of the elementary cell volume deduced from XRD. The temperature dependence of the magnetization indicated a two-step magnetic transition of the 𝜖-Fe2O3 nanoparticles spread between ˜85 K and ˜150 K, which is slightly modified by remanent tensile stresses in the case of nanoparticles in the matrix. The subsequent coating of the bare particles by silica produced no further change in hyperfine parameters, which indicates that this procedure does not modify magnetic properties of nanoparticles.

  17. Magnetic dynamics of small alpha-Fe2O3 and NiO particles

    DEFF Research Database (Denmark)

    Lefmann, K.; Bødker, Franz; Hansen, Mikkel Fougt;

    1999-01-01

    We have studied the magnetic dynamics in nanocrystalline samples of alpha-Fe2O3 (hematite) and NiO by inelastic neutron scattering. By measuring around the structural and the antiferromagnetic reflections, we have probed uniform and staggered magnetic oscillations, respectively. In the hematite...... as a sign of superparamagnetic relaxation. Studies of the antiferromagnetic signal from NiO also show evidence of collective magnetic excitations, but with a higher energy of the precession state than for hematite. The inelastic signal at the structural reflection of NiO presents evidence for uniform...

  18. BONDLENGTH ALTERNATION OF NANOPARTICLES Fe2O3 COATED WITH ORGANIC SURFACTANTS PROBED BY EXAFS

    Institute of Scientific and Technical Information of China (English)

    1999-01-01

    The nanoparticles γ-Fe2O3 coated with surfactants.DBS,ST and CTAB.repsectively.were synthesized by microemulsion method.The coated ferric oxides.which show enhanced nonlinear optical properties compared with their bulk counterpart.were probed by EXAFS in solution forms.The x=-ray absorption spectra for Fe K edge were measured at room temperature by help of synchrotron radiation light source.Extended x-ray absorption fine structure analysis shows that the coating layers of organic molecules interact with surface atoms of nanopartices,the Fe-O bond length was extended.

  19. Electrochemical Behavior of Dissolved Fe2O3 in Molten CaCl2-KF

    Institute of Scientific and Technical Information of China (English)

    WANG Shu-lan; Geir Martin Haarberg; Eirin Kvalheim

    2008-01-01

    The elctrochemical behavior of dissolved Fe2O3 in 82.5CaCl2-17.5KF(mole percent,%)was studied using cyclic voltammetry,chronoamperometry,and galvanostatic electrolysis at 827℃,and the deposits were characterized by XRD and SEM.Pure iron was deposited on a rotating cylinder(210 r/min)with a cell voltage less than-1.0 V.Deposition rate was controlled by diffusion on a molybdenum electrode.The diffusion coefficient of iron species Fe(Ⅲ)in the melt at 827℃was found to be 9.7×105cm2/s.

  20. Nanofluids Containing γ-Fe2O3 Nanoparticles and Their Heat Transfer Enhancements.

    Science.gov (United States)

    Guo, Shou-Zhu; Li, Yang; Jiang, Ji-Sen; Xie, Hua-Qing

    2010-05-20

    Homogeneous and stable magnetic nanofluids containing γ-Fe2O3 nanoparticles were prepared using a two-step method, and their thermal transport properties were investigated. Thermal conductivities of the nanofluids were measured to be higher than that of base fluid, and the enhanced values increase with the volume fraction of the nanoparticles. Viscosity measurements showed that the nanofluids demonstrated Newtonian behavior and the viscosity of the nanofluids depended strongly on the tested temperatures and the nanoparticles loadings. Convective heat transfer coefficients tested in a laminar flow showed that the coefficients increased with the augment of Reynolds number and the volume fraction.

  1. Oriented attachment and exchange coupling of α-Fe2O3 nanoparticles

    DEFF Research Database (Denmark)

    Frandsen, Cathrine; Bahl, Christian Robert Haffenden; Lebech, Bente;

    2005-01-01

    We show that antiferromagnetic nanoparticles of alpha-Fe2O3 (hematite) under wet conditions can attach into chains along a common [001] axis. Electron microscopy shows that such chains typically consist of two to five particles. X-ray and neutron diffraction studies show that both structural...... and magnetic correlations exist across the interfaces along the [001] direction. This gives direct evidence for exchange coupling between particles. Exchange coupling between nanoparticles can suppress superparamagnetic relaxation and it may play a role for attachment along preferred directions. The relations...... between exchange coupling, magnetic properties, and oriented attachment are discussed....

  2. Microstructural evolution during high energy ball milling of Fe2O3-SiO2 powders

    DEFF Research Database (Denmark)

    Jiang, Jianzhong; Zhou, Y.X.; Mørup, Steen;

    1996-01-01

    The reaction of a 25 mol% Fe2O3-SiO2 (hematite-amorphous silica) powder mixture during high energy ball milling in both closed and open containers has been studied by x-ray diffraction and Mossbauer spectroscopy. After around 21 h of milling, the alpha-Fe2O3 powders with an average particle size...... of 15 nm have formed and no reaction between alpha-Fe2O3 and SiO2 is found in the two types of milling containers. This demonstrates that the high energy mechanical milling technique is able to prepare a dispersion of ultrafine alpha-Fe2O3 particles. After extended milling in the open container all iron...

  3. Self-assembling Ni(OH)2/α-Fe2O3 composites for pseudocapacitors with excellent electrochemical performance

    Science.gov (United States)

    Li, Zijiong; Zhang, Weiyang; Su, Yuling; Li, Zhikun; Groeper, Jonathan

    2017-01-01

    Novel two-dimensional (2D) nanostructured Ni(OH)2 nanosheet/α-Fe2O3 nanoplate composites (NFCs) were successfully synthesized by a simple two-step solvothermal method where the proportion of α-Fe2O3 nanoplates was found to be controllable. These composites achieved excellent performance in aqueous electrolyte due to the synergistic effect between Ni(OH)2 nanosheets and α-Fe2O3 nanoplates, such as high specific capacitance and long-term cycle stability. The obtained NFC8 possessed a maximum mass specific capacitance of 1745.33F g‑1 at a current density of 2 A g‑1, and with 84.28% retention after 3000 cycles galvanostatic charge/discharge at a high current density of 20 A g‑1. The above results show that these novel 2D nanostructured Ni(OH)2/α-Fe2O3 composites are promising electrode materials for pseudocapacitors.

  4. SYNTHESIS OF Fe2O3-MONTMORILLONITE AND ITS APPLICATION AS A PHOTOCATALYST FOR DEGRADATION OF CONGO RED DYE

    Directory of Open Access Journals (Sweden)

    Karna Wijaya

    2010-06-01

    Full Text Available The preparation of Fe2O3-montmorillonite and it's application as a catalyst for congo red dye photodegradation has been carried out. Fe2O3-montmorillonite was prepared by mixing the iron complexes pillaring agent and montmorillonite. The product was calcined at 250 oC for 5 hours. Montmorillonite and calcined product was analyzed by X-ray diffractometry (X-RD, infrared spectrophotometry (FTIR, gas  sorption analyser, X-ray fluorescense (X-RF and UV/Vis diffuse reflectance spektrophotometry (UV-DRS. Fe2O3-montmorilonite then was used as a catalyst on congo red dye photodegrdation by UV-illuminating a mixture of 50 mg Fe2O3-montmorillonite and 25 mL congo red 10­-4M at 365 nm at various illuminating times. Adsorption of congo red on Fe2O3-montmorillonite and montmorillonite was also performed as a comparison. Result of X-RD analysis showed that the 001 reflection of  Fe2O3-montmorillonite was not  detected that probably indicating the formation of house of card stucture and this result was supported also by the analysis result of distribution of pores and SEM photography result. Results of the XRF analysis showed that iron content increased  from 5.21 % (w/w in montmorillonite to 25.12 % (w/w in Fe2O3-montmorillonite. UV- DRS analysis showed the increament of band gap energy from 3.69 eV in the iron oxide bulk to 3.8 eV in Fe2O3-montmorillonite. Specific surface area of the montmorillonite also increased significantly from 69,71 m2/g to 126,49 m2/g and total pores volume increased from 50.70x10-3 mL/Å/g  to 107.89x10-3 mL/Å/g, respectively. Photodegradation of congo red using Fe2O3-montmorillonite caused the decreament of congo red concentration up to 90.22 %  on UV illumination for 60 minutes. Adsorption of congo red on Fe2O3-montmorillonite reached 84.4% and on  montmorillonite was 75.15 %.   Keywords: photodegradation, congo red, Fe2O3-montmorillonite, UV light

  5. Surface functionalization of nanostructured Fe2O3 polymorphs: from design to light-activated applications.

    Science.gov (United States)

    Barreca, Davide; Carraro, Giorgio; Gasparotto, Alberto; Maccato, Chiara; Rossi, Francesca; Salviati, Giancarlo; Tallarida, Massimo; Das, Chittaranjan; Fresno, Fernando; Korte, Dorota; Stangar, Urška Lavrenčič; Franko, Mladen; Schmeisser, Dieter

    2013-08-14

    Nanostructured iron(III) oxide deposits are grown by chemical vapor deposition (CVD) at 400-500 °C on Si(100) substrates from Fe(hfa)2TMEDA (hfa = 1,1,1,5,5,5-hexafluoro-2,4-pentanedionate; TMEDA = N,N,N',N'-tetramethylethylenediamine), yielding the selective formation of α-Fe2O3 or the scarcely studied ε-Fe2O3 polymorphs under suitably optimized preparative conditions. By using Ti(OPr(i))4 (OPr(i) = iso-propoxy) and water as atomic layer deposition (ALD) precursors, we subsequently functionalized the obtained materials at moderate temperatures (<300 °C) by an ultrathin titanomagnetite (Fe3-xTixO4) overlayer. An extensive multitechnique characterization, aimed at elucidating the system structure, morphology, composition and optical properties, evidenced that the photoactivated hydrophilic and photocatalytic behavior of the synthesized materials is dependent both on iron oxide phase composition and ALD surface modification. The proposed CVD/ALD hybrid synthetic approach candidates itself as a powerful tool for a variety of applications where semiconductor-based nanoarchitectures can benefit from the coupling with an ad hoc surface layer.

  6. γ-Fe2O3 nanoparticles filled polyvinyl alcohol as potential biomaterial for tissue engineering scaffold.

    Science.gov (United States)

    Ngadiman, Nor Hasrul Akhmal; Idris, Ani; Irfan, Muhammad; Kurniawan, Denni; Yusof, Noordin Mohd; Nasiri, Rozita

    2015-09-01

    Maghemite (γ-Fe2O3) nanoparticle with its unique magnetic properties is recently known to enhance the cell growth rate. In this study, γ-Fe2O3 is mixed into polyvinyl alcohol (PVA) matrix and then electrospun to form nanofibers. Design of experiments was used to determine the optimum parameter settings for the electrospinning process so as to produce elctrospun mats with the preferred characteristics such as good morphology, Young's modulus and porosity. The input factors of the electrospinnning process were nanoparticles content (1-5%), voltage (25-35 kV), and flow rate (1-3 ml/h) while the responses considered were Young's modulus and porosity. Empirical models for both responses as a function of the input factors were developed and the optimum input factors setting were determined, and found to be at 5% nanoparticle content, 35 kV voltage, and 1 ml/h volume flow rate. The characteristics and performance of the optimum PVA/γ-Fe2O3 nanofiber mats were compared with those of neat PVA nanofiber mats in terms of morphology, thermal properties, and hydrophilicity. The PVA/γ-Fe2O3 nanofiber mats exhibited higher fiber diameter and surface roughness yet similar thermal properties and hydrophilicity compared to neat PVA PVA/γ-Fe2O3 nanofiber mats. Biocompatibility test by exposing the nanofiber mats with human blood cells was performed. In terms of clotting time, the PVA/γ-Fe2O3 nanofibers exhibited similar behavior with neat PVA. The PVA/γ-Fe2O3 nanofibers also showed higher cells proliferation rate when MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay was done using human skin fibroblast cells. Thus, the PVA/γ-Fe2O3 electrospun nanofibers can be a promising biomaterial for tissue engineering scaffolds.

  7. Decontamination of radionuclides using γ-Fe2O3 as a Nanosorbent

    Science.gov (United States)

    Bagla, Hemlata; Thakur, Jyotsna

    2017-04-01

    The release of radioactive waste into the environment and the disposal of conditioned waste is a major environmental concern which demands the improvement in the remediation processes [1]. Due to the advancements in Nanotechnology, novel and simple nanoparticles have been proved very efficient worldwide, in the radioactive waste treatment processes [2]. These nanoparticles prove to be an excellent nanosorbents owing to its very high surface area and other size dependent properties [3]. In the present study, nanocrystalline γ-Fe2O3 was synthesized by gel-combustion method. Gel combustion method [4, 5] is the most facile method of synthesis of nanocrystalline oxides. Fuel deficient composition of ferric nitrate (oxidant) and malonyl dihydrazide (fuel) were mixed well in de-ionised water and heated at temperature 300 °C. The smouldering combustion took place resulting in formation of γ-Fe2O3 which further calcined at 500 °C to remove undesirable impurities. The prepared powder further characterized by various techniques such as X-ray diffractometer, transmission electron microscopy, BET technique and zeta potential measurements. The crystallite size of γ-Fe2O3 was found to be 11 nm. TEM images showed that the grain size obtained was in agreement with the XRD report. Sorption study have been carried out using tracer technique for batch equilibration method at room temperature and atmospheric pressure. A known amount of sorbent (γ-Fe2O3) was mixed with 10 mL of solution containing radiotracer and 1mg/mL solution of carrier. Various parameters such as contact time, pH, amount of sorbent, concentration, temperature, agitation speed were optimized, determination of sorption capacity and interference study was also conducted. The activity is measured by using single channel NaI(Tl) well type gamma ray spectrometer. γ-Fe2O3 was found to be an efficient and cost effective sorbent for the decontamination of heavy radionuclides such as Cs-137, Sr-90, Cd-115m, Cr-51, Hg

  8. Hierarchical α-Fe2O3/NiO composites with a hollow structure for a gas sensor.

    Science.gov (United States)

    Wang, Chen; Cheng, Xiaoyang; Zhou, Xin; Sun, Peng; Hu, Xiaolong; Shimanoe, Kengo; Lu, Geyu; Yamazoe, Noboru

    2014-08-13

    Hierarchical α-Fe2O3/NiO composites with a hollow nanostructure were synthesized by a facile hydrothermal method. The structures and morphologies of the composites were investigated by different kinds of techniques, including X-ray diffraction, field-emission electron scanning microscopy, transmission electron microscopy, and energy dispersive spectroscopy. Hierarchical α-Fe2O3/NiO composites were fabricated by growing the α-Fe2O3 nanorods on the surfaces of porous NiO nanosheets with a thickness of ∼12 nm. The gas sensing properties of hierarchical α-Fe2O3/NiO composites toward toluene were investigated using a static system. The response of α-Fe2O3/NiO composites to 100 ppm toluene was ∼18.68, which was 13.18 times higher than that of pure NiO at 300 °C. The enhanced response can be attributed to heterojunction. Meanwhile, the rapid response and recovery characteristics were observed because of the porous hollow structural characteristics and catalytic actions of α-Fe2O3 and NiO.

  9. Design of α-Fe2O3 nanorods functionalized tubular NiO nanostructure for discriminating toluene molecules.

    Science.gov (United States)

    Wang, Chen; Wang, Tianshuang; Wang, Boqun; Zhou, Xin; Cheng, Xiaoyang; Sun, Peng; Zheng, Jie; Lu, Geyu

    2016-05-19

    A novel tubular NiO nanostructure was synthesized by a facile and low-cost hydrothermal strategy and then further functionalized by decorating α-Fe2O3 nanorods. The images of electron microscopy indicated that the α-Fe2O3 nanorods were assembled epitaxially on the surfaces of NiO nanotubes to form α-Fe2O3/NiO nanotubes. As a proof-of-concept demonstration of the function, gas sensing devices were fabricated from as-prepared α-Fe2O3/NiO nanotubes, and showed enhanced gas response and excellent selectivity toward toluene, giving a response of 8.8 to 5 ppm target gas, which was about 7.8 times higher than that of pure NiO nanotubes at 275 °C. The improved gas sensing performance of α-Fe2O3/NiO nanotubes could be attributed to the unique tubular morphology features, p-n heterojunctions and the synergetic behavior of α-Fe2O3 and NiO.

  10. Preparation of porous α-Fe2O3-supported Pt and its sensing performance to volatile organic compounds

    Institute of Scientific and Technical Information of China (English)

    Yuhong Cheng; Yanfei Kang; Liwei Wang; Yao Wang; Shurong Wang; Yujin Li; Wei Zhong; Liangqun Peng

    2012-01-01

    Porous α-Fe2O3 was synthesized by a simple hydrothermal treatment of FeCl3 aqueous solution followed by a calcination process.In the synthesis of porous α-Fe2O3,no templates or pore-directing agents were used.The as-prepared porous α-Fe2O3 was further employed as a support for loading Pt nanoparticles.The gas sensing performance of the obtained porous α-Fe2O3-supported Pt to VOCs was investigated.The sensor presented a high response and fast response-recovery characteristic to several VOCs including acetone,ether,methanol,ethanol,butanol and hexanol.Meanwhile,it exhibited a much higher response than the pure α-Fe2O3 at the operating temperature of 260℃.The enhanced sensing properties may be related to the unique porous structure of the α-Fe2O3 support and the promoting effect of active Pt nanoparticles for the sensing reactions.

  11. Steam reforming of ethanol over Co3O4–Fe2O3 mixed oxides

    KAUST Repository

    Abdelkader, A.

    2013-05-03

    Co3O4, Fe2O3 and a mixture of the two oxides Co-Fe (molar ratio of Co3O4/Fe 2O3 = 0.67 and atomic ratio of Co/Fe = 1) were prepared by the calcination of cobalt oxalate and/or iron oxalate salts at 500 C for 2 h in static air using water as a solvent/dispersing agent. The catalysts were studied in the steam reforming of ethanol to investigate the effect of the partial substitution of Co3O4 with Fe2O 3 on the catalytic behaviour. The reforming activity over Fe 2O3, while initially high, underwent fast deactivation. In comparison, over the Co-Fe catalyst both the H2 yield and stability were higher than that found over the pure Co3O4 or Fe 2O3 catalysts. DRIFTS-MS studies under the reaction feed highlighted that the Co-Fe catalyst had increased amounts of adsorbed OH/water; similar to Fe2O3. Increasing the amount of reactive species (water/OH species) adsorbed on the Co-Fe catalyst surface is proposed to facilitate the steam reforming reaction rather than decomposition reactions reducing by-product formation and providing a higher H2 yield. © Copyright © 2012, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.

  12. Effect of Fe2O3 Addition in MgO-CaO Refractory on Desulfurization of Liquid Iron

    Institute of Scientific and Technical Information of China (English)

    WEI Yao-wu; LI Nan; CHEN Fang-yu

    2003-01-01

    The effects of Fe2O3 addition in MgO-CaO refractory on desulfurization of liquid iron were studied by SEM, EDA and chemical analysis. Fe2O3 of 1 % and 4 % were added to MgO-CaO refractory as the lining of graphite crucible in which 150 g iron powder with sulfur of 0.15 % was charged. It is found that when the sample is heated at 1 600 ℃ for 40 min, 60 min and 90 min, the addition with Fe2O3 of 1 % improves desulfurization greatly. However, the desulfurization ratio of the refractory with Fe2O3 addition of 4 % is less than that with Fe2O3 addition of 1 %. For the soaking time of 90 min, the desulfurization ratio is less than those of 40 min and 60 min. These phenomena were explained by the contrary roles of O2- and Fe2+ formed by reaction between liquid iron and Fe2O3 on desulfurization.

  13. Preparation and Performaces of ADN/Fe2O3 Nanocomposite Oxidant%ADN/Fe2O3纳米复合氧化剂的制备及性能

    Institute of Scientific and Technical Information of China (English)

    宋肯彭; 宋小兰; 张树海

    2011-01-01

    By using 1,2-epoxypropane as the agent for speeding up the hydrolyzation of Fe(Ⅲ) ions, AND/Fe2O3 composite wet gel was prepared by sol-gel method under a mild and nontoxic condition. Consequently, the AND/ Fe2O3 aerogel was obtained by means of supercritical CO2 fluid extraction. TEM,SEM,EDS,IR,DSC and sensitivity test were employed to characterize the appearance, structure, thermal behaviour and mechanical sensitivity of the samples. The results indicate that the as-prepared AND/Fe2O3 nanoparticles are about 50- 100 nm in diameter. As the decrease of the mass of AND,the nanocomposites become much insensitive to mechanical stimuli. Moreover,the AND/Fe2 O3 nanoparticles decomposes at lower temperature with the disappearance of melting endothermic peak.%采用溶胶-凝胶法,以1,2-环氧丙烷作为Fe(Ⅲ)离子的水解促进剂,在温和无毒的条件下制备了ADN/Fe2O3复合湿凝胶,再将复合湿凝胶进行超临界CO2萃取后,成功获得ADN/Fe2O3气凝胶.用TEM、SEM、EDS、IR DSC和感度试验对上述样品的形貌、结构、热行为和机械感度进行了表征.结果表明,制得的ADN/Fe2O3纳米复合氧化剂的粒径为50~10 nm,撞击感度和摩擦感度均随着其中ADN含量的减小而降低,分解放热峰较原料ADN有所提前,熔化吸热峰消失.

  14. Fe2O3纳米粒子复合纤维素膜降解有机染料亚甲基蓝%Methylene blue degradation by cellulose/Fe2 O3 nanocomposites fibers

    Institute of Scientific and Technical Information of China (English)

    向莹; 钟书华; 何瑜; 宋功武

    2013-01-01

    合成Fe2 O3纳米粒子复合纤维素膜.采用XRD、TEM和磁力线等多种方法对Fe2 O3纳米粒子复合纤维素膜的结构和性能进行表征,并研究Fe2 O3纳米粒子复合纤维素膜对亚甲基蓝的降解作用.结果表明:当溶液中 H2 SO4加量为25.8 mol/L、H2 O2加量为2.4 mol/L时,用5 g/L的复合纤维素膜对1.4×10-5 mol/L的亚甲基蓝溶液进行降解,25 min内降解率达到100%.%The cellulose/Fe2 O3 nanocomposites fibers were prepared by NaOH/urea aqueous solution with cotton linter pulp and FeCl2・4H2 O as reactants .The cellulose/Fe2 O3 nanocomposites fibers were characterized by X-ray diffraction (XRD) ,transmission electron microscopy (TEM ) ,and vibrating sample magnetometer (VSM ) .The degradation of methylene blue(MB) with cellulose/Fe2 O3 nanocomposites fibers was studied .The results showed that the degradation rate of MB could reach 100% in 25 min ,when addition dosage of H2 SO4 ,H2 O2 ,cellulose/Fe2 O3 nanocomposite fibers and MB were 25 .8 mol/L ,2 .40 mol/L ,5 .00 g/L ,1 .40 × 10-5 mol/L ,respectively .

  15. Dual-template ordered mesoporous carbon/Fe2O3 nanowires as lithium-ion battery anodes

    Science.gov (United States)

    Hu, Junkai; Sun, Chuan-Fu; Gillette, Eleanor; Gui, Zhe; Wang, Yuhuang; Lee, Sang Bok

    2016-06-01

    Ordered mesoporous carbons (OMCs) are ideal host materials that can provide the desirable electrical conductivity and ion accessibility for high-capacity oxide electrode materials in lithium-ion batteries (LIBs). To this end, however, it is imperative to establish the correlations among material morphology, pore structure and electrochemical performance. Here, we fabricate an ordered mesoporous carbon nanowire (OMCNW)/Fe2O3 composite utilizing a novel soft-hard dual-template approach. The structure and electrochemical performance of OMCNW/Fe2O3 were systematically compared with single-templated OMC/Fe2O3 and carbon nanowire/Fe2O3 composites. This dual-template strategy presents synergetic effects combining the advantages of both soft and hard single-template methods. The resulting OMCNW/Fe2O3 composite enables a high pore volume, high structural stability, enhanced electrical conductivity and Li+ accessibility. These features collectively enable excellent electrochemical cyclability (1200 cycles) and a reversible Li+ storage capacity as high as 819 mA h g-1 at a current density of 0.5 A g-1. Our findings highlight the synergistic benefits of the dual-template approach to heterogeneous composites for high performance electrochemical energy storage materials.Ordered mesoporous carbons (OMCs) are ideal host materials that can provide the desirable electrical conductivity and ion accessibility for high-capacity oxide electrode materials in lithium-ion batteries (LIBs). To this end, however, it is imperative to establish the correlations among material morphology, pore structure and electrochemical performance. Here, we fabricate an ordered mesoporous carbon nanowire (OMCNW)/Fe2O3 composite utilizing a novel soft-hard dual-template approach. The structure and electrochemical performance of OMCNW/Fe2O3 were systematically compared with single-templated OMC/Fe2O3 and carbon nanowire/Fe2O3 composites. This dual-template strategy presents synergetic effects combining the

  16. Topotaxial growth of α-Fe2O3 nanowires on iron substrate

    Science.gov (United States)

    Srivastava, Himanshu; Srivastava, A. K.; Babu, Mahendra; Rai, S. K.; Ganguli, Tapas

    2016-05-01

    α-Fe2O3 (hematite) nanowires have been grown by simple thermal oxidation of iron foil at 700°C in a moist oxygen flow. It was observed that the growth of nanowires highly depends on the texture of the iron substrate, in particular the presence of [110] oriented iron grains. Cross-sectional Transmission Electron Microscopy (TEM) investigation of as-grown sample revealed that the growth of nanowires has definite orientation relation with the underlying oxide grains Fe3O4 (magnetite) and FeO (wustite), which can be interpreted by the primary orientation relationships of topotaxial growth of iron oxides. The observation can pave the way for patterning of the nanowire growth by controlling the texture of original substrate. Samples were also characterized with Scanning Electron Microscope (SEM) and X-ray diffraction (XRD).

  17. Structural and electrical properties of Ti doped α-Fe2O3

    Directory of Open Access Journals (Sweden)

    Nikolić M.V.

    2013-01-01

    Full Text Available In this work we have analyzed the effects of Ti doping on structural and electrical properties of α-Fe2O3. When the amount of added Ti (5 wt.%TiO2 was within the solubility degree and XRD, SEM and EDS analysis revealed a homogenous hematite structure, with lattice parameters a= 5.03719(3 Å, c=13.7484(1 Å slightly increased due to incorporation of Ti into the rhombohedral hematite lattice. Higher amounts of Ti (10 wt.%TiO2 resulted in the formation of pseudobrookite, besides hematite, confirmed by SEM and EDS analysis. Studies of electric properties in the temperature range 25-225oC at different frequencies (100 - 1Mz showed that Ti doping improved electrical conductivity. Impedance analysis was performed using an equivalent circuit, showing one relaxation process and suggesting dominant grain boundary contribution. [Projekat Ministarstva nauke Republike Srbije, br. III45014 i br. III43008

  18. Neutron study of magnetic excitations in 8-nm -Fe2O3 nanoparticles

    DEFF Research Database (Denmark)

    Kuhn, Luise Theil; Lefmann, Kim; Bahl, Christian Robert Haffenden

    2006-01-01

    By use of inelastic neutron scattering we have studied magnetic fluctuations in 8-nm particles of antiferromagnetic alpha-Fe2O3 (hematite) as a function of temperature and applied magnetic fields. The fluctuations are dominated by uniform excitations. Studies have been performed on both coated...... (noninteracting) and uncoated (interacting) particles. We have estimated the magnetic anisotropy energy and found that the data are in good agreement with the value obtained from Mossbauer spectroscopy. The energy epsilon(0) of the uniform excitations depends strongly on the uncompensated moment, which is caused...... by finite-size effects, and we have estimated the size of this moment from the experimental neutron data. The field dependence of epsilon(0) for the interacting nanoparticles differs strongly from that of the noninteracting nanoparticles, and this is a result of the influence of exchange interaction between...

  19. [In vitro MR imaging of Fe(2)O(3)-PLL labelled rabbit peripheral blood endothelial progenitor cells].

    Science.gov (United States)

    Mai, Xiao-li; Teng, Gao-jun; Ma, Zhan-long; Sun, Jun-hui; Zhang, Yu; Gu, Ning

    2007-09-01

    To perform in vitro magnetic resonance imaging on magnetic iron oxide (Fe(2)O(3)-PLL) labeled rabbit peripheral blood endothelial progenitor cells (EPCs). Fe(2)O(3) was incubated with PLL for 2 hours to form Fe(2)O(3)-PLL. Rabbit peripheral blood mononuclear cells (MNCs) were isolated and EPCs were selected by adherence method, expanded and incubated with Fe(2)O(3)-PLL. Intracellular iron was detected by Prussian blue stain and under electron microscope. MTT assay was used to evaluate cell survival and proliferation of Fe(2)O(3)-PLL labeled EPCs. Flow cytometry was used to analysis cell cycle and apoptosis. The cells underwent in vitro MR imaging with various sequences. Iron-containing intracytoplasmatic vesicles could be observed clearly with Prussian blue staining and electron microscope observation. Survival, life cycle and apoptosis values obtained by MTT and flow cytometry analysis were similar among unlabelled EPCs and EPCs labeled with various concentrations Fe(2)O(3)-PLL. The signal intensity on MRI was significantly decreased in labeled cells compared with that in unlabeled cells. The percentage change in signal intensity (DeltaSI) was most significant on T(2)*WI and DeltaSI was significantly lower in cells labeled for 7 days than that labeled for 1 day. The rabbit peripheral blood EPCs can be labeled with Fe(2)O(3)-PLL without significant change in viability and proliferation. The labeled EPCs can be imaged with standard 1.5 T MR equipment. The degree of MR signal decreasing may indirectly reflect the cells count, growth state and division.

  20. Visible-light-driven photocatalytic inactivation of Escherichia coli by magnetic Fe2O3-AgBr.

    Science.gov (United States)

    Ng, Tsz Wai; Zhang, Lisha; Liu, Jianshe; Huang, Guocheng; Wang, Wei; Wong, Po Keung

    2016-03-01

    Bacterial inactivation by magnetic photocatalyst receives increasing interests for the ease recovery and reuse of photocatalysts. This study investigated bacterial inactivation by a magnetic photocatalysts, Fe2O3-AgBr, under the irradiation of a commercially available light emitting diode lamp. The effects of different factors on the inactivation of Escherichia coli were also evaluated, in term of the efficiency in inactivation. The results showed that Fe2O3-AgBr was able to inactivate both Gram negative (E. coli) and Gram positive (Staphylococcus aureus) bacteria. Bacterial inactivation by Fe2O3-AgBr was more favorable under high temperature and alkaline pH. Presence of Ca(2+) promoted the bacterial inactivation while the presence of [Formula: see text] was inhibitory. The mechanisms of photocatalytic bacterial inactivation were systemically studied and the effects of the presence of various specific reactive species scavengers and argon suggest that Fe2O3-AgBr inactivate bacterial cells by the oxidation of H2O2 generated from the photo-generated electron and direct oxidation of photo-generated hole. The detection of different reactive species further supported the proposed mechanisms. The results provide information for the evaluation of bacterial inactivation performance of Fe2O3-AgBr under different conditions. More importantly, bacterial inactivation for five consecutive cycles demonstrated Fe2O3-AgBr exhibited highly stable bactericidal activity and suggest that the magnetic Fe2O3-AgBr has great potential for water disinfection.

  1. Amphiphile disruption of pathogen attachment at the hematite (α-Fe2O3)-water interface.

    Science.gov (United States)

    Gao, Xiaodong; Chorover, Jon

    2011-05-17

    Prior studies have indicated that the subsurface transport of Cryptosporidium parvum oocysts is diminished in sediments containing iron oxides and that inner-sphere complexation of oocyst surficial carboxylate plays a role in the retardation. However, the impacts of natural organic matter (NOM) remain poorly understood. In this study, we used a model anionic surfactant, sodium dodecyl sulfate (SDS), as a surrogate for amphiphilic NOM components to examine the impacts of amphiphilic components on oocyst adhesion mechanisms. We employed in situ attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy to determine the effects of SDS on the molecular bonds that mediate interactions between oocyst surficial biomolecules and hematite (α-Fe(2)O(3)) surface functional groups over a wide range of solution pH. The results show that the presence of SDS significantly diminishes Fe-carboxylate complexation, as indicated by progressive decreases in intensity of asymmetric and symmetric stretching vibrations of carboxylate [ν(as)(COO(-)) and ν(s)(COO(-))] with reaction time. In addition, one of the ν(s)(COO(-)) bands shifted from 1370 to 1418 cm(-1) upon SDS introduction, suggesting that SDS also changed the complexation mode. The data indicate that competition from the sulfonate groups (OSO(3)(-)) of SDS at α-Fe(2)O(3) surface sites is a primary mechanism resulting in decreased Fe-carboxylate complexation. Sorptive competition from amphiphilic NOM components may therefore increase the mobility of C. parvum oocysts in the environment through disruption of interfacial pathogen-mineral surface bonds.

  2. Dynamic Mechanical Behavior Characterization of Epoxy-Cast Al + Fe2O3 Thermite Mixture Composites

    Science.gov (United States)

    Ferranti, Louis; Thadhani, Naresh N.

    2007-11-01

    The dynamic mechanical behavior characterization of epoxy-cast stoichiometric mixtures of nano- or micron-scale aluminum and hematite (Fe2O3) powders is investigated in this work. Experiments conducted on rod-shaped samples, using instrumented reverse Taylor impact tests employing high-speed imaging and velocity interferometry, show that these composites exhibit viscoelastic deformation and brittle fracture behaviors. Upon impact, the samples display significant elastic and plastic deformation during both the loading and unloading stages, as determined from quantitative high-speed camera measurements of the transient deformation states. Approximately 50 pct elastic recovery of total axial strain was observed to occur rapidly (within tens of microseconds) after impact. A one-dimensional elastic-plastic wave propagation analysis was used for estimating the composite’s dynamic average yield stress and total plastic strain. The results reveal that the nano-Al + Fe2O3-containing epoxy composite is most resilient, has the highest strength, and is more capable of absorbing impact energy. The analysis additionally provides detailed information about elastic and plastic wave interactions for discrete times, up to the final state of the material. Calculations and observations through the coupling of high-speed camera images and velocity interferometry (VISAR) measurements show that the elastic recovery coincides with peak axial strain and the interaction of elastic and plastic waves propagating within the rod-shaped specimen. Hence, such an instrumented Taylor test provides a detailed view of the general wave structure within the material upon impact and, at the same time, enables a complete description of the stress-strain response.

  3. Preparation and Characterization of Novel Fe2O3-Flaky Coated Carbon Fiber by Electrospinning and Hydrothermal Methods

    Directory of Open Access Journals (Sweden)

    Qing-Yun Chen

    2014-01-01

    Full Text Available A novel hierarchical nanostructure of Fe2O3-flaky coated carbon fibers was produced by the electrospinning process followed by a hydrothermal technique. First, electrospinning of a colloidal solution that consisted of ferric nitrate and polyacrylonitrile (PAN was performed to produce PAN nanofibers. Then electrospun nanofiber was stabilized and calcinated in nitrogen at 800°C for 2 h to produce carbon nanofibers (CNFs which were exploited to produce Fe2O3-flaky structure using hydrothermal technique. The as-obtained products were characterized by scanning electron microscopy (SEM and X-ray diffraction (XRD. The results revealed that Fe2O3 flakes were successfully grown on the CNFs substrates, and the coverage of Fe2O3 flakes could be controlled by simply adjusting the hydrothermal pH value and time. Fe2O3-flaky coated carbon fibers displayed high photocatalytic activity toward degradation of methyl orange (MO under visible light irradiation.

  4. Enhanced visible-light-induced photocatalytic activity of α-Fe2O3 adsorbing redox enzymes

    Directory of Open Access Journals (Sweden)

    Kai Kamada

    2015-03-01

    Full Text Available We report fabrication of hybrid photocatalyst composed of an n-type semiconductor (α-Fe2O3 and a redox enzyme (horseradish peroxidase; HRP, and its performance for oxidation of luminol in an aqueous solution. The hybrid photocatalyst is simply formed via physical adsorption of HRP to an α-Fe2O3 sintered body. Under visible light irradiation, the bare α-Fe2O3 with a narrow bandgap photocatalytically oxidizes luminol along with blue emission that can be used as an indicator of the photocatalytic performance. The blue emission is largely strengthened after the adsorption of HRP, demonstrating that the presence of enzyme improves apparent photocatalytic activity of α-Fe2O3. The favorable effect is derived from synergistic oxidation of luminol by the biocatalysts (HRP as well as by the photocatalyst (α-Fe2O3. In this paper, influence of excitation wavelength, adsorption amount of HRP, and reaction temperature on the overall photocatalytic activity are elucidated, and then a reaction mechanism of the proposed novel hybrid photocatalyst is discussed in detail.

  5. Studies on a New Material for Hydrogen Storage and Supply by Modified Fe and Fe2O3 Powder

    Institute of Scientific and Technical Information of China (English)

    WANG, Hui; WANG, Xian-Sheng; WANG, Xin-Zhi; WANG, Xiao-Fang; DONG, Fa-Xin; SHI, Qi-Zhen

    2007-01-01

    Modified iron oxide, a new material for hydrogen storage and supply to polymer electrolyte fuel cell (PEFC),was prepared by impregnating Fe or Fe2O3 powder with an aqueous solution containing metal cation additives (Al,Cr, Ni, Co, Zr and Mo). Hydrogen storage properties of the samples were investigated. The results show that both Fe and Fe2O3 powder with additive Mo presented excellent catalytic activity and cyclic stability, and their hydrogen producing temperature could be surprisingly decreased. The temperature of forming hydrogen for the Fe2O3-Mo at after addition of Mo in the fourth cycle. The cause for it was probably related to preventing the sinter of the sample particles. In addition, hydrogen storage capacity of the Fe2O3-Mo can reach w=4.5% (72 kg H2/m3), close to International Energy Agency (IEA) criterion. These show the value of practical application of the Fe2O3-Mo as the promising hydrogen storage material.

  6. Formation Mechanism of alpha-Fe2O3 Nanotubes via Electrospinning and Their Adsorption Characteristics of BSA and DNA.

    Science.gov (United States)

    Liu, Ruijiang; Wang, Peng; Tao, Yuting; Liu, Yifan; Shen, Xiangqian

    2016-02-01

    The alpha-Fe2O3 nanotubes with diameters of 400-700 nm have been prepared via the sol-gel assisted electrospinning and subsequent one-step heat treatment with ferric nitrate, ethanol and poly(vinyl pyrrolidone) as starting regents. The resultant alpha-Fe2O3 nanotubes were characterized by XRD, SEM, TEM, and VSM techniques. The hollow structure is mainly influenced by the water content in the gel precursor and the heating rate, and the hollow formation mechanism of alpha-Fe2O9 nanotubes is discussed. Adsorption of BSA onto the as-prepared alpha-Fe2O3 nanotubes exhibits a good capacity of 56.5 mg/g with the initial BSA concentration of 1.0 mg/mL, which demonstrates their feasibility in delivery of biomacromolecules. Subsequently, the adsorption characteristics of DNA onto the alpha-Fe2O3 nanotubes were investigated, and the adsorbance of DNA can achieve a maximum value of 4.19 microg/g when the initial DNA concentration is 50 microg/mL. The adsorption process of DNA onto alpha-Fe2O3 nanotubes can be described well by the pseudo-first-order kinetic model at room temperature according to the correlation coefficient R2 = 0.9978.

  7. Preparation and magnetic properties of Fe2O3 microtubules prepared by sol-gel template method

    Institute of Scientific and Technical Information of China (English)

    CHANG Chuanbo; ZHANG Cunrui; WANG Wenyan; LI Qiaoling

    2010-01-01

    Fe(OH)3 precursor sol was prepared by a sol-gel method.The precursor sol was dipped onto the absorbent cotton,and gel was formed on the absorbent cotton template after the volatilization of moisture.Fe2O3 microtubules were synthesized after the process of self-propagation or calcination.The phase,morphology,and particle diameter of the samples were examined by X-ray diffraction(XRD)and scanning electron microscopy(SEM),and the magnetic properties of the samples were measured using a vibrating sample magnetometer(VSM).The external diameters of Fe2O3 microtubules ranged between 8 and 13 μm,and the wall thicknesses ranged between 0.5 and 2 μm The type of the calcination method plays a significant role in developing the Fe2O3 phase and the variation in the magnetic properties in the sol-gel template complexing method.γ-Fe2O3 was synthesized by a self-propagation method.However,α-Fe2O3 was synthesized after calcination at 400℃ for 2 h.The coercivity of the samples synthesized by calcination at 400℃ for 2 h after self-propagation was found to increase significantly,thereby presenting hard magnetic properties.

  8. Fe2O3 nanocubes exposed (012) active facets combination with graphene rendering enhanced lithium storage capability

    Science.gov (United States)

    Zhao, Yongjie; Yan, Dong; Ding, Caihua; Su, Dezhi; Ge, Yiyao; Zhao, Yuzhen; Zhou, Heping; Li, Jingbo; Jin, Haibo

    2016-09-01

    Owing to scientific importance associated with highly reactive surfaces, the research concerning inorganic single crystals with a large percentage of exposed high-index facets has attracted much attention. In current research, α-Fe2O3 nanocubes exposed with (012) active facet was firstly synthesized via a hydrothermal method. And then a freeze-drying approach was utilized to construct nanostructured Fe2O3/graphene composite. The as-obtained composite exhibited s higher BET surface area than that of bare α-Fe2O3 nanocubes. When evaluated for lithium storage properties, the Fe2O3/graphene rendered remarkable electrochemical cycle stability and high rate performance. At the rate of 300 mA g-1, a high reversible discharge capacity of 1136 mAh g-1 was obtained up to 200 cycles. In addition, the excellent rate performance was also achieved. Excellent electrochemical properties are probably ascribed to the synergistic effect of α-Fe2O3 nanocubes and graphene sheets, as a result of smart structure design via a freeze-drying route. This strategy with merits of rational construction and scalable production could establish new perspective for diverse composites towards commercial application.

  9. Calcination-temperature-dependent gas-sensing properties of mesoporous α-Fe2O3 nanowires as ethanol sensors

    Science.gov (United States)

    Li, X. Q.; Li, D. P.; Xu, J. C.; Han, Y. B.; Jin, H. X.; Hong, B.; Ge, H. L.; Wang, X. Q.

    2017-07-01

    The mesoporous α-Fe2O3 nanowires (NWs) were successfully synthesized by changing the calcination temperature from 550 to 750 °C (marked NWs-550, NWs-650 and NWs-750) via using SBA-15 silica as the hard templates with the nanocasting method. The characterization results indicated that the bandgap of the as-prepared samples hardly changed and the high BET surface areas changed a little with the calcination temperature from 550 to 750 °C. Mesoporous α-Fe2O3 NWs had been found to possess the remarkable gas-sensing performance to ethanol gas. The gas-sensing behavior indicated that α-Fe2O3 NWs-650 exhibited the higher response than that of α-Fe2O3 NWs-550 and α-Fe2O3 NWs-750. The calcination-temperature-dependent gas-sensing properties were mainly attributed to the competition of surface defects and body defects by the crystallization temperature. The lower calcination temperature could create more surface defects to improve the gas-sensing response, while the higher temperature would reduce the body defect and make the charge carriers transport easily. As the result, the suitable calcination temperature was desired to optimize the defects of nanostructures to improve the gas sensitivity.

  10. Fe2O3/BiWO6的制备与光催化性能研究%A study on preparation and photocatalytic property of Fe2O3/BiWO6

    Institute of Scientific and Technical Information of China (English)

    付文; 王丽

    2012-01-01

    采用水热法制备了BiWO6催化剂,以Fe2O3对其进行了改性。考察了复合催化剂对罗丹明B溶液的光催化降解性能,对光催化降解动力学进行了研究。%BiWO6 was prepared by hydrothennal method, and modified by Fe2O3. The photocatalytic degradation performance of rhodamine B solution was investigated, the photocatalytic degradation kinetics was studied.

  11. Effect of Nano-Fe2 O3 on Growth of Two Species of Microalgae%纳米Fe2O3对2种微藻生长的影响

    Institute of Scientific and Technical Information of China (English)

    裴峰; 王长海

    2015-01-01

    研究了纳米Fe2 O3颗粒的悬浮液对蛋白核小球藻和斜生栅藻生长的影响。通过生长抑制实验确定了纳米Fe2 O3促进2藻种生长的最佳浓度以及临界浓度范围,通过测定光合特性以及氧化应激水平和酶活性层面确定了纳米Fe2 O3对2藻种生长的内部物质变化的影响,并分析其具体调节机制。结果表明,纳米Fe2 O3颗粒的悬浮液对2藻种生长的最适浓度是6 mg/L,高于此浓度即对藻细胞造成毒性抑制。该实验结果可为工业生产废水的处理排放提供参考。%The effect of Fe2 O3 nanoparticle suspension on the growth of Chlorella pyrenoidosa and Scenedesmus obliquus is studied. The optimal concentration and critical concentration range of nano-Fe2 O3 to promote the growth of the two microalgae are obtained through growth inhibition test. Effect of nano-Fe2 O3 on internal material change of the two microalgae and the corresponding mechanisms are revealed by testing the photosynthetic characteristics, the level of oxidative stress, and the enzyme activity. The results show that optimum concentration of nano-Fe2 O3 on the growth of Chlorella pyrenoidosa and Scenedesmus obliquus is 6 mg/L, and higher concentration will result in cell toxicity inhibition. The results provide a reference for managing industrial waste water.

  12. 浸酸去除SiC微粉中Fe2O3的工艺技术研究%Research on acid pickling to remove Fe2O3 from SiC micropowder

    Institute of Scientific and Technical Information of China (English)

    李亮; 王军

    2012-01-01

    The SiC micropowder prepared by a jet mill was used as starting material to remove Fe2O3 by acid pickling. According to condition experiment, the suitable experimental conditions are: HCI (about 35 mass%) as pickling acid,mass ratio of HCI: SiC micropowder about 4:1,pickling temperature about 70 ℃ and pickling time 4 h. Based on the above results, orthogonal tests were conducted, the final optimal technological parameters are: pickling temperature 60 ℃,mass ratio of HCI: SiC micropowder about 4:1, HCI 35 mass%. Stable experiment shows that the extraction ratio of Fe2O3 is over 80%, and the Fe2O3 removing effect is obvious.%为了去除SiC微粉制备过程中引入的含铁杂质(主要以Fe2O3的形式存在),以气流磨加工所得的SiC微粉为原料,采用浸酸法去除其中的Fe2O3.首先通过条件试验得出大致的浸出试验条件为:浸出酸选择盐酸,其HCl质量分数选择35%左右,浸出酸与微粉质量比选择4∶1左右,浸出温度选择70℃左右,浸出时间选择4h.然后通过正交试验得出用盐酸从SiC微粉中浸出Fe2O3的最佳工艺参数为:浸出温度60℃,浸出酸与微粉质量比4∶1,盐酸的w(HCl) =35%.稳定试验表明:在此工艺下的Fe2O3浸出率达80%以上,除Fe2O3效果较明显.

  13. Magnetic coupling mechanisms in particle/thin film composite systems

    Directory of Open Access Journals (Sweden)

    Giovanni A. Badini Confalonieri

    2010-12-01

    Full Text Available Magnetic γ-Fe2O3 nanoparticles with a mean diameter of 20 nm and size distribution of 7% were chemically synthesized and spin-coated on top of a Si-substrate. As a result, the particles self-assembled into a monolayer with hexagonal close-packed order. Subsequently, the nanoparticle array was coated with a Co layer of 20 nm thickness. The magnetic properties of this composite nanoparticle/thin film system were investigated by magnetometry and related to high-resolution transmission electron microscopy studies. Herein three systems were compared: i.e. a reference sample with only the particle monolayer, a composite system where the particle array was ion-milled prior to the deposition of a thin Co film on top, and a similar composite system but without ion-milling. The nanoparticle array showed a collective super-spin behavior due to dipolar interparticle coupling. In the composite system, we observed a decoupling into two nanoparticle subsystems. In the ion-milled system, the nanoparticle layer served as a magnetic flux guide as observed by magnetic force microscopy. Moreover, an exchange bias effect was found, which is likely to be due to oxygen exchange between the iron oxide and the Co layer, and thus forming of an antiferromagnetic CoO layer at the γ-Fe2O3/Co interface.

  14. Influence of Fe2O3 Impurity on the Crystalline Structure of Cordierite Synthesized from Waste Aluminum Slag

    Institute of Scientific and Technical Information of China (English)

    WU Wei-Qing; RUAN Yu-Zhong; YU Yan

    2005-01-01

    The influence of Fe2O3 impurity on the crystalline structure of cordierite synthesized from waste aluminum slag is discussed. XRD and SEM techniques were employed to characterize the crystalline structure and microstructure of each specimen. Philips X'pert plus software was used to determine the lattice parameters of each specimen. The results show that the Fe2O3 content of 0.8~1.6wt% is beneficial to the formation of cordierite, with the cordierite amount reaching 90wt%. So 0.8~1.6wt% is considered as the allowable Fe2O3 content in the specimens and 0.8wt% is determined to be the best after overall analysis. Plus software analysis shows that the cordierite in each specimen has the same symmetrical hexagonal structure as the single crystal, and the lattice parameters as well as the lattice dimensions change slightly.

  15. A sensitive nonenzymatic hydrogen peroxide sensor based on Fe3O4–Fe2O3 nanocomposites

    Indian Academy of Sciences (India)

    Guang Sheng Cao; Peilong Wang; Xin Li; Yue Wang; Guilong Wang; Junping Li

    2015-02-01

    The Fe3O4–Fe2O3 nanocomposites were prepared by the co-precipitation method and followed by calcination process. The products were synthesized and characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy and energy-dispersive X-ray analysis. The obtained Fe3O4–Fe2O3 nanocomposites were then applied to study the electrocatalytic reduction of hydrogen peroxide (H2O2) in 0.01 M pH 7.0 phosphate buffer medium. Then the Fe3O4–Fe2O3 nanocomposites were used as active electrode material of electrochemical sensors for H2O2 detection The detection sensitivity of the sensor was 20.325 A mM-1, and the detection limit was estimated to be about 0.2 mM.

  16. One-step synthesis and properties of urchin-like PS/α-Fe2O3 composite hollow microspheres

    Science.gov (United States)

    Zhang, Yanping; Chu, Ying; Dong, Lihong

    2007-10-01

    A new progressive hard template method has been developed to synthesize uniform polystyrene (PS)/α-Fe2O3 composite hollow microspheres under hydrothermal conditions. Sulfonated polystyrene (PS) microspheres were used as templates as well as the endothecia of the composite microspheres; Fe2O3 shell was obtained through the reaction of FeSO4 and KClO3 under hydrothermal conditions. Field-emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM) studies showed that the as-obtained products consist of large scale monodisperse urchin-like hollow microspheres. In comparison with the Fe2O3 of other structures, the composite hollow microspheres have good photocatalytic activity, large surface area and a high remanent magnetization. A possible mechanism for the formation of composite hollow microspheres is also proposed in the paper.

  17. Hazardous Doping for Photo-Electrochemical Conversion: The Case of Nb-Doped Fe2O3 from First Principles

    Directory of Open Access Journals (Sweden)

    Natav Yatom

    2015-11-01

    Full Text Available The challenge of improving the efficiency of photo-electrochemical devices is often addressed through doping. However, this strategy could harm performance. Specifically, as demonstrated in a recent experiment, doping one of the most widely used materials for water splitting, iron (III oxide (Fe2O3, with niobium (Nb can still result in limited efficiency. In order to better understand the hazardous effect of doping, we use Density Functional Theory (DFT+U for the case of Nb-doped Fe2O3. We find a direct correlation between the charge of the dopant, the charge on surface of the Fe2O3 material, and the overpotential required for water oxidation reaction. We believe that this work contributes to advancing our understanding of how to select effective dopants for materials.

  18. Characterization and optical properties of Fe2O3-PbO-B2O3 glasses

    Science.gov (United States)

    Sanjay, Kishore, N.; Kundu, R.; Dahiya, S.; Pal, I.; Dhankhar, S.; Punia, R.

    2016-05-01

    Heavy metal-based oxide glasses of compositions xFe2O3.(40-x)PbO.60B2O3 have been synthesized by the standard melt-quenching technique. The amorphous nature of these samples is ascertained by XRD patterns. Scanning Electron Microscope is used to study the microstructure of the samples. The absorption edge (λcut-off) shifts toward longer wavelengths with an increase in Fe2O3 content in the glass matrix. Study of absorption edge signifies the glassy nature of the samples. The values of optical band gap energy for indirect allowed and forbidden transitions have been determined and it is found that it decreases with increasing Fe2O3 content. The Urbach's energy is used to characterize the degree of disorder in the studied samples.

  19. Morphology and magnetic properties of α-Fe2O3 particles prepared by octadecylamine-assisted hydrothermal method

    Institute of Scientific and Technical Information of China (English)

    Zhong Liu; Baoliang Lv; Dong Wu; Yuhan Sun

    2012-01-01

    α-Fe2O3 particles with various morphologies,including micro-doublesphere,tetrakaidecahedron and nanoparticles-aggregated micro-ellipsoid,were successfully synthesized via an octadecylamine-assisted hydrothermal method.The products were characterized by X-ray diffraction (XRD),scanning electron microscopy (SEM) and high-resolution transmission electron microscopy (HRTEM).The results indicate that the presence of octadecylamine played a crucial role in morphology evolution by selective crystal adsorption,The protonated octadecylamine increased the pH value that accelerated nucleation,and the long alkyl groups of octadecylamine acted as an adsorption inhibitor to retard the growth of nanoparticles.The as-prepared α-Fe2O3 particles exhibited higher remanent magnetization and coercivity than other α-Fe2O3 particles of similar size.These properties should be attributed to the superstructure and the shape anisotropy of the synthesized particles.

  20. A Synergistic Effect of Surfactant and ZrO2 Underlayer on Photocurrent Enhancement and Cathodic Shift of Nanoporous Fe2O3 Photoanode.

    Science.gov (United States)

    Shinde, Pravin S; Lee, Su Yong; Choi, Sun Hee; Lee, Hyun Hwi; Ryu, Jungho; Jang, Jum Suk

    2016-08-31

    Augmenting the donor density and nanostructure engineering are the crucial points to improve solar water oxidation performance of hematite (α-Fe2O3). This work addresses the sluggish water oxidation reaction associated with hematite photoanode by tweaking its internal porosity. The porous hematite photoanodes are fabricated by a novel synthetic strategy via pulse reverse electrodeposition (PRED) method that involves incorporation of a cationic CTAB surfactant in a sulfate electrolyte and spin-coated ZrO2 underlayer (UL) on FTO. CTAB is found to be beneficial in promoting the film growth rate during PRED. Incorporation of Zr(4+) ions from ZrO2 UL and Sn(4+) ions from FTO into the Fe2O3 lattice via solid-state diffusion reaction during pertinent annihilation of surfactant molecules at 800 °C produced internally porous hematite films with improved carrier concentration. The porous hematite demonstrated a sustained photocurrent enhancement and a significant cathodic shift of 130 mV relative to the planar hematite under standard illumination conditions (AM 1.5G) in 1 M NaOH electrolyte. The absorption, electrochemical impedance spectroscopy and Mott-Schottky analyses revealed that the ZrO2 UL and CTAB not only increased the carrier density and light harvesting but also accelerated the surface oxidation reaction kinetics, synergistically boosting the performance of internally porous hematite photoanodes.

  1. A Synergistic Effect of Surfactant and ZrO2 Underlayer on Photocurrent Enhancement and Cathodic Shift of Nanoporous Fe2O3 Photoanode

    Science.gov (United States)

    Shinde, Pravin S.; Lee, Su Yong; Choi, Sun Hee; Lee, Hyun Hwi; Ryu, Jungho; Jang, Jum Suk

    2016-08-01

    Augmenting the donor density and nanostructure engineering are the crucial points to improve solar water oxidation performance of hematite (α-Fe2O3). This work addresses the sluggish water oxidation reaction associated with hematite photoanode by tweaking its internal porosity. The porous hematite photoanodes are fabricated by a novel synthetic strategy via pulse reverse electrodeposition (PRED) method that involves incorporation of a cationic CTAB surfactant in a sulfate electrolyte and spin-coated ZrO2 underlayer (UL) on FTO. CTAB is found to be beneficial in promoting the film growth rate during PRED. Incorporation of Zr4+ ions from ZrO2 UL and Sn4+ ions from FTO into the Fe2O3 lattice via solid-state diffusion reaction during pertinent annihilation of surfactant molecules at 800 °C produced internally porous hematite films with improved carrier concentration. The porous hematite demonstrated a sustained photocurrent enhancement and a significant cathodic shift of 130 mV relative to the planar hematite under standard illumination conditions (AM 1.5G) in 1 M NaOH electrolyte. The absorption, electrochemical impedance spectroscopy and Mott-Schottky analyses revealed that the ZrO2 UL and CTAB not only increased the carrier density and light harvesting but also accelerated the surface oxidation reaction kinetics, synergistically boosting the performance of internally porous hematite photoanodes.

  2. Fe@Fe2O3 promoted electrochemical mineralization of atrazine via a triazinon ring opening mechanism.

    Science.gov (United States)

    Ding, Xing; Wang, Shengyao; Shen, Wanqiu; Mu, Yi; Wang, Li; Chen, Hao; Zhang, Lizhi

    2017-04-01

    In this study, an electrochemical/electro-Fenton oxidation (EC/EF) system was designed to degrade atrazine, by utilizing boron-doped diamond (BDD) and Fe@Fe2O3 core-shell nanowires loaded active carbon fiber (Fe@Fe2O3/ACF) as the anode and the cathode, respectively. This EC/EF system exhibited much higher degradation rate, decholorination and mineralization efficiency of atrazine than the electrochemical (EC) and electrochemical/traditional electro-Fenton (EC/TEF) oxidation counterpart systems without Fe@Fe2O3 core-shell nanowires. Active species trapping experiment revealed that Fe@Fe2O3 could activate molecular oxygen to produce more OH through Fenton reaction, which favored the atrazine degradation. High performance liquid chromatography, high performance liquid chromatography-mass spectrometry and gas chromatography-mass spectrometry were applied to probe the decomposition and mineralization of atrazine during this novel EC/EF process, which revealed that two intermediates of triazinons (the isomerization of hydroxylated atrazine) were generated during the electrochemical/electro-Fenton oxidation of atrazine in the presence of Fe@Fe2O3 core-shell nanowires. The experimental and theoretical calculation results suggested that atrazine might be degraded via a triazinon ring opening mechanism, while the presence of Fe@Fe2O3 notably accelerated the decholorination process, and produced more hydroxylated products to promote the generation of trazinons and the subsequent ring cleavage as well as the final complete mineralization. This work provides a deep insight into the triazine ring opening mechanism and the design of efficient electrochemical advanced oxidation technologies (EAOTs) for persistent organic pollutant removal. Copyright © 2017 Elsevier Ltd. All rights reserved.

  3. Radio frequency shielding behaviour of silane treated Fe2O3/E-glass fibre reinforced epoxy hybrid composite

    Science.gov (United States)

    Arun prakash, V. R.; Rajadurai, A.

    2016-10-01

    In this work, radio frequency shielding behaviour of polymer (epoxy) matrixes composed of E-glass fibres and Fe2O3 fillers have been studied. The principal aim of this project is to prepare suitable shielding material for RFID application. When RFID unit is pasted on a metal plate without shielding material, the sensing distance is reduced, resulting in a less than useful RFID system. To improve RF shielding of epoxy, fibres and fillers were utilized. Magnetic behaviour of epoxy polymer composites was measured by hysteresis graphs (B-H) followed by radio frequency identifier setup. Fe2O3 particles of sizes 800, 200 and 100 nm and E-glass fibre woven mat of 600 g/m2 were used to make composites. Particle sizes of 800 nm and 200 nm were prepared by high-energy ball milling, whereas particles of 100 nm were prepared by sol-gel method. To enhance better dispersion of particles within the epoxy matrix, a surface modification process was carried out on fillers by an amino functional coupling agent called 3-Aminopropyltrimethoxysilane (APTMS). Crystalline and functional groups of siliconized Fe2O3 particles were characterized by XRD and FTIR spectroscopy analysis. Variable quantity of E-glass fibre (25, 35, and 45 vol%) was laid down along with 0.5 and 1.0 vol% of 800, 200, and 100 nm size Fe2O3 particles into the matrix, to fabricate the hybrid composites. Scanning electron microscopy and transmission electron microscopy images reveal the shape and size of Fe2O3 particles for different milling times and particle dispersion in the epoxy matrix. The maximum improved sensing distance of 45.2, 39.4 and 43.5 % was observed for low-, high-, and ultra-high radio frequency identifier setup along with shielding composite consist of epoxy, 1 vol% 200 nm Fe2O3 particles and 45 vol% of E-glass fibre.

  4. Hematite (alpha-Fe2O3) with various morphologies: ionic liquid-assisted synthesis, formation mechanism, and properties.

    Science.gov (United States)

    Lian, Jiabiao; Duan, Xiaochuan; Ma, Jianmin; Peng, Peng; Kim, Tongil; Zheng, Wenjun

    2009-11-24

    The alpha-Fe(2)O(3) with various morphologies has been successfully synthesized via an ionic liquid-assisted hydrothermal synthetic method. The samples are characterized by X-ray diffraction, Fourier transform infrared spectroscopy, field emission scanning electron microscope (FE-SEM), transmission electron microscopy, and high-resolution transmission electron microscopy. The results indicate that the as-prepared samples are alpha-Fe(2)O(3) nanoparticles, mesoporous hollow microspheres, microcubes, and porous nanorods. The effects of the ionic liquid 1-n-butyl-3-methylimidazolium chloride ([bmim][Cl]) on the formation of the alpha-Fe(2)O(3) with various morphologies have been investigated systematically. The proposed formation mechanisms have also been investigated on the basis of a series of FE-SEM studies of the products obtained at different durations. Because of the unique porous structure, the potential application in water treatment of the alpha-Fe(2)O(3) porous nanorods was investigated. The UV-vis measurements suggest that the as-synthesized pure alpha-Fe(2)O(3) with various morphologies possess different optical properties depending on the shape and size of the samples. The magnetic hysteresis measurements indicate the interesting magnetic property evolution in the as-prepared alpha-Fe(2)O(3) samples, which is attributed to the superstructure or the shape anisotropy of the samples. This method is expected to be a useful technique for controlling the diverse shapes of crystalline inorganic materials for a variety of applications, such as sensors, gas and heavy metal ion adsorbents, catalytic fields, hydrogen and Li ion storage, and controlled drug delivery, etc.

  5. [Effect of Fe2O3 on photodegradation of gamma-666 in surface soils with low amount of organic substance].

    Science.gov (United States)

    Niu, Junfeng; Quan, Xie; Chen, Jingwen; Zhao, Zhiqiang; Xue, Daming; Yang, Fenglin

    2002-03-01

    The photodegradation of gamma-666 on surface soils with low amount of organic substance was studied. The results showed that photodegradation rate of gamma-666 was fitted for pseudo one-order kinetics. The constants of photodegradation rates increased from 0.0052 h-1 to 0.0340 h-1 with the increase of Fe2O3 contents between 0.40% and 5.40% in soils. These results showed that Fe2O3 in soils with low amount of organic substance had remarkable catalysis on photodegradation of gamma-666.

  6. Measurement of intravenously administered γ-Fe2O3 particle amount in mice tissues using vibrating sample magnetometer.

    Science.gov (United States)

    Kishimoto, Mikio; Miyamoto, Ryoichi; Oda, Tatsuya; Ohara, Yusuke; Yanagihara, Hideto; Ohkohchi, Nobuhiro; Kita, Eiji

    2014-12-01

    Dispersions of platelet γ-Fe2O3 particles 30-50nm in size were intravenously administered to mice and the amount of particles accumulated in each tissue was obtained by magnetization measurement using a vibrating sample magnetometer. Background noise was greatly reduced by measuring dried tissues under a magnetic field of 500 Oe so that the effect of diamagnetism was slight. Remarkable particle accumulation was observed in the liver and spleen. Considerable particle accumulation was observed in the lung when a large quantity of γ-Fe2 O3 particles was administered. There was no significant particle accumulation in the kidney and heart.

  7. Metal-organic framework templated synthesis of Fe2O3/TiO2 nanocomposite for hydrogen production.

    Science.gov (United States)

    deKrafft, Kathryn E; Wang, Cheng; Lin, Wenbin

    2012-04-17

    A new metal-organic framework (MOF)-templated method has been developed for the synthesis of a metal oxide nanocomposite with interesting photophysical properties. Fe-containing nanoscale MOFs are coated with amorphous titania, then calcined to produce crystalline Fe(2)O(3)/TiO(2) composite nanoparticles. This material enables photocatalytic hydrogen production from water using visible light, which cannot be achieved by either Fe(2)O(3) or TiO(2) alone or a mixture of the two. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  8. Formation of a 25 mol% Fe2O3-Al2O3 solid solution prepared by ball milling

    DEFF Research Database (Denmark)

    Jiang, Jianzhong; Mørup, Steen; Linderoth, Søren

    1996-01-01

    The phase transformation process of a 25 mol% Fe2O3-Al2O3 powder mixture during high-energy ball milling has been studied by x-ray diffraction and Mossbauer spectroscopy. A metastable solid solution of 25 mol % Fe2O3 in Al2O3 with corundum structure has successfully been prepared after a milling...... time of 122 h. This demonstrates that the high-energy ball milling technique is able to prepare metastable solid solutions with an extended range of compositions in ceramic/ceramic systems with a positive hear of mixing....

  9. Effect of Fe2O3 Loading Amount on Catalytic Properties of Monolithic Fe2O3/Ce0.67Zr0.33O2-Al2O3 Catalyst for Methane Combustion

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Ce0.67Zr0.33O2-Al2O3 solid solution was prepared by the co-precipitation method. Fe2O3-based catalysts supported on the solid solution were obtained by the impregnation method. The article revealed that the optimal loading amount of Fe2O3 on Ce0.67Zr0.33O2-Al2O3 in our experimental condition for catalytic combustion of methane was 8%( mass fraction). The prepared catalysts were characterized by BET, TPR, XRD analyses, and their catalytic activity was investigated after being calcined at 873 K and after being aged in water gas at 1273 K. When the loading amount of Fe2O3 was 8%( mass fraction), the catalyst held the highest activity, and the best temperature speciality and thermal stability. The complete-conversion temperature of methane for fresh and aged sample was 788 and 838 K, respectively. The range between the light-off temperature and the complete-conversion temperature was only 15 K. The characterization results of XRD indicated that Fe2O3 was well dispersed on the Ce0.67Zr0.33O2-Al2O3 matrix. The results of BET and TPR were in good harmony with the catalytic activity results.

  10. Comparison of hydrogen-storage properties of Mg-14Ni-3Fe2O3-3Ti and Mg-14Ni-2Fe2O3-2Ti-2Fe

    Science.gov (United States)

    Kwak, Young Jun; Park, Hye Ryoung; Song, Myoung Youp

    2013-05-01

    Magnesium with oxides or transition elements prepared by mechanical grinding under H2 (reactive mechanical grinding) showed relatively high hydriding and dehydriding rates when the content of additives was about 20 wt%. Ni, Fe2O3, and Fe were chosen as the oxides or transition elements to be added. Ti was also selected since it was considered to increase the hydriding and dehydriding rates by forming Ti hydride. Samples Mg-14Ni-3Fe2O3-3Ti (Sample A) and Mg-14Ni-2Fe2O3-2Ti-2Fe (Sample B) were prepared by reactive mechanical grinding, and their hydrogen storage properties were compared. The activated Sample A had a little smaller hydriding rate than the activated Sample B, but a higher dehydriding rate than the activated Sample B. Sample A exhibits quite a larger dehydriding rate and quantity of hydrogen desorbed for 60 min than any other Mg-xNi-yFe2O3-zM (M=transition metals) samples. An addition of a relatively larger amount of Ti is considered to lead to quite a high hydriding rate and a high dehydriding rate of Sample A.

  11. Engineering nanofluid electrodes: controlling rheology and electrochemical activity of γ-Fe2O3 nanoparticles

    Science.gov (United States)

    Sen, Sujat; Moazzen, Elahe; Aryal, Shankar; Segre, Carlo U.; Timofeeva, Elena V.

    2015-11-01

    Nanofluid electrodes or nanoelectrofuels have significant potential in the field of flow batteries, as at high loadings of solid battery active nanoparticles, their energy density can be orders of magnitude higher than in traditional redox flow battery electrolytes. Nanofluid electrodes must have a manageable viscosity at high particle concentrations (i.e., easily pumpable) and exhibit good electrochemical activity toward charge and discharge reactions. Engineering of such nanofluid electrodes involves development of new and unique approaches to stabilization of nanoparticle suspensions. In this work, we demonstrate a surface modification approach that allows controlling the viscosity of nanofluids at high solid loading, while simultaneously retaining electrochemical activity of the nanoparticles. A scalable single step procedure for the surface grafting of small organic molecules onto iron (III) oxide nanoparticles (γ-Fe2O3, maghemite, 40-150 nm) is demonstrated. Modified iron oxide nanoparticles reported here have 5 wt% of the grafting moiety on the surface, which helps forming stable dispersions with up to 40 wt% of solid loading in alkali aqueous electrolytes with a maximum viscosity of 12 cP at room temperature. The maximum particle concentration achievable in the same electrolyte with pristine nanoparticles is 15 wt%. Electrochemical testing of the pristine and modified nanomaterials in the form of solid-casted electrodes showed a maximum reversible discharge capacity of 280 and 155 mAh/g, respectively, indicating that electrochemical activity of modified nanoparticles is partially suppressed due to the surface grafted moiety.

  12. The magnetic properties of antiferromagnetic nanoparticles: NiO and -Fe2O3

    DEFF Research Database (Denmark)

    Bahl, Christian Robert Haffenden

    2006-01-01

    Nikkel oxid (NiO) og hematit -Fe2O3) er begge antiferromagneter med magnetiske egenskaber på nanoskala, som er forskellige fra dem i større krystaller. Med hovedvægt på nanopartikler af NiO og sammenligninger med nanopartikler af hematit studeres disse magnetiske egenskaber med en række...... egenskaber. Nanopartiklerne af NiO vises at være pladeformede med (111) planer som flader, en tykkelse på omkring 2.3 nm og en diameter på omkring 13 nm. Den magnetiske struktur er magen til den i større krystaller, med spinene holdt i (111) planerne. Målinger af spindynamikken afslører en værdi af den...... morter med hånden. Nanopartikler af antiferromagnetiske materialer vil have et ukompenseret magnetisk moment, der opstår ved endelige partikelstørrelser på grund af overskydende spin på det ene undergitter. Dette ukompenserede moment kvantiseres i NiO nanopartiklerne og findes at være uafhængigt af...

  13. Synthesis and Characterization of α-Fe_2O_3/C Composite Anode for Lithium Ion Batteries%α-Fe_2O_3/C复合材料的制备及性能研究

    Institute of Scientific and Technical Information of China (English)

    吴超; 庄全超; 徐守冬; 崔永丽; 强颖怀; 孙智

    2012-01-01

    采用高温固相反应法制备α-Fe2O3/C复合材料,运用X射线衍射(XRD)、扫描电子显微镜(SEM)、充放电测试、电化学阻抗谱对其结构和电化学性能进行了表征.充放电测试结果显示,α-Fe2O3/C复合材料循环50周时可逆充电容量为935.3 mAh?g-1,循环性能较商品化α-Fe2O3有显著改善.电化学阻抗谱测试结果显示,α-Fe2O3/C复合材料电极在首次嵌锂过程中分别出现了锂离子通过固体电解质相界面膜(SEI膜)的迁移、材料的电子电导率、电荷传递过程相关的半圆,并详细分析了它们的变化规律.%The α-Fe2O3/C composite was prepared by high-temperature solid-state reaction,its structure and electrochemical performance were characterized by X-ray diffraction(XRD),scanning electron miscro-scopy(SEM),charge/discharge test and electrochemical impedance spectroscopy(EIS).The electrochemical test results indicated that the α-Fe2O3/C composite showed an reversible charge capacity of 935.3 mAh?g-1 after 50 cycles,and had better cycle performance compared with commercial α-Fe2O3.Electrochemical im-pedance spectroscopy test indicated that there appeared three semicircles respectively representing the Li-ion migration in solid electrolyte interface film(SEI film),electrical conductivity and charge transfer in the first lithiation,and their evolutive principles were also investigated.

  14. PENGUJIAN AKTIVITAS KOMPOSIT Fe2O3-SiO2 SEBAGAI FOTOKATALIS PADA FOTODEGRADASI 4-KLOROFENOL (The Activity Test of Fe2O3-SiO2 Composite As Photocatalyst on 4-Chlorophenol Photodegradation

    Directory of Open Access Journals (Sweden)

    Eko Sri Kunarti

    2009-03-01

    Full Text Available ABSTRAK  Pada penelitian ini telah dilakukan pengujian aktivitas komposit Fe2O3-SiO2 sebagai fotokatalis pada fotodegradasi 4-klorofenol. Penelitian diawali dengan preparasi dan karakterisasi fotokatalis Fe2O3-SiO2. Preparasi dilakukan dengan metode sol-gel pada temperatur kamar menggunakan tetraetil ortosilikat (TEOS dan besi (III nitrat sebagai prekursor diikuti dengan perlakuan termal pada temperature 500 oC. Karakterisasi dilakukan dengan metode spektrometri inframerah, difraksi sinar-X dan spektrometri fluoresensi sinar-X. Uji aktivitas komposit untuk fotodegradasi 4-klorofenol dilakukan dalam reaktor tertutup yang dilengkapi dengan lampu UV. Pada uji ini telah dipelajari pengaruh waktu penyinaran dan pH larutan terhadap efektivitas fotodegradasi 4-klorofenol. Hasil penelitian menunjukkan bahwa komposit Fe2O3-SiO2 dapat dipreparasi dengan metode sol-gel pada temperatur kamar diikuti perlakuan termal. Komposit Fe2O3-SiO2 dapat meningkatkan efektivitas fotodegradasi 4-klorofenol dari 11,86 % menjadi 55,38 %. Efektivitas fotodegradasi 4- klorofenol dipengaruhi waktu penyinaran dan pH larutan yang semakin lama waktu penyinaran efektifitas fotodegradasi semakin tinggi, namun waktu penyinaran yang lebih lama dari 4 jam dapat menurunkan efektivitasnya. pH larutan memberikan pengaruh yang berbeda-beda pada efektivitas fotodegradasi 4-klorofenol.   ABSTRACT The activity test of Fe2O3-SiO2 composite as photocatalyst on 4-chlorophenol photodegradation has been studied. The research was initiated by preparation of Fe2O3-SiO2 photocatalyst and followed by characterization. The preparation was conducted by sol-gel method at room temperature using tetraethylorthosilicate (TEOS and iron (III nitrate as precursors followed by thermal treatment at a temperature of 500oC. The characterizations were performed by X-ray Diffraction (XRD, Infrared and X-ray Fluorescence Spectrophotometry. The photocatalytic activity test of composites for 4 chlorophenol

  15. 超级铝热剂Al/Fe2O3对硝化棉热分解特性的影响%Effects of Superthermite Al/Fe2O3 on the Thermal Decomposition Characteristics of Nitrocellulose

    Institute of Scientific and Technical Information of China (English)

    赵宁宁; 马海霞; 安亭; 赵凤起; 胡荣祖

    2016-01-01

    The nano-Fe2O3 was prepared by hydrothermal method, and then combined with Al nanoparticles using ultrasonic dispersion method to prepare superthermite Al/Fe2O3. The physical phase, composition, morphology and structure of the composite were characterized by X-ray powder diffraction (XRD), transmission electron microscopy (TEM) and scanning electron microscope-energy dispersive spectrometer (SEM-EDS). The differential scanning calorimetry (DSC) and the thermogravimetry with Fourier transform infrared analysis (TG-FTIR) were employed to investigate the effects of the superthermite Al/Fe2O3 on the thermal decomposition process of nitrocellulose (NC). The results show that the thermal decomposition reactions of Al/Fe2O3-NC composite and NC follow the same thermal decomposition mechanism with the Avrami-Erofeev equation of f(α)=1.5(1-α)[-ln(1-α)]1/3. The superthermite Al/Fe2O3 can reduce the activation energy of the decomposition reaction, the thermal ignition temperature and the critical temperature of thermal explosion of NC,and it plays a crucial role in promoting the O-NO2 bond cleavage of NC and secondary autocatalytic reactions in condensed phase.%采用水热法制备了纳米Fe2O3,并用超声分散法将其与纳米Al颗粒复合制备了超级铝热剂Al/Fe2O3,利用X-射线粉末衍射(XRD)、透射电子显微镜(TEM)、扫描电镜及能量散射光谱仪(SEM-EDS)对复合物的物相、组成、形貌和结构进行了分析表征,采用差示扫描量热法(DSC)和热红联用技术(TG-FTIR)研究了Al/Fe2O3对硝化棉(NC)热分解过程的影响.结果表明,Al/Fe2O3-NC和NC的热分解过程遵循Avrami-Erofeev 方程f(α)=1.5(1-α)[-ln(1-α)]1/3;超级铝热剂Al/Fe2O3可降低硝化棉的表观活化能、临界点火温度和临界爆炸温度,在促进硝化棉O-NO2键断裂和凝聚相二次自催化反应中起到至关重要的作用.

  16. Phase transformations in thin iron oxide films: Spectromicroscopic study of velocity and shape of the reaction fronts

    Science.gov (United States)

    Genuzio, F.; Sala, A.; Schmidt, Th.; Menzel, D.; Freund, H.-J.

    2016-06-01

    Combining low energy electron microscopy (LEEM) with low energy electron diffraction (LEED) and x-ray photoemission electron microscopy (XPEEM), we studied the phase transformations between Fe3O4, γ-Fe2O3, and α-Fe2O3, grown as 10 nm thin oxide films on Pt(111) and Ag(111) single crystals. These transformations occur as moving reaction fronts in most cases, the shapes and velocities of which show strong dependences on temperature and oxygen pressure, but also on defects like step bunches of the supporting substrate and domain boundaries in the initial oxide film. While the non-uniform moving fronts make quantitative analysis difficult, we have extracted approximate values for the average front velocities. We discuss these as well as the qualitative information on the non-uniform fronts in terms of the known geometric situations and the likely motional steps.

  17. Study of Fe2O3, CuO, ZnO catalyzed efficient Hantzsch reaction under different conditions

    Directory of Open Access Journals (Sweden)

    Mohammad Reza Shushizadeh

    2015-05-01

    Full Text Available 1,4-dihydropyridine derivatives one-pot synthesis under different condition was described. CuO nanoparticle as a catalyst in microwave irradiation (100w gives product with excellent yields (≥87% and short reaction time. No significant difference was observed between the obtained yield by using ZnO and Fe2O3.

  18. Oxygen deficient α-Fe2O3 photoelectrodes: a balance between enhanced electrical properties and trap-mediated losses.

    Science.gov (United States)

    Forster, Mark; Potter, Richard J; Ling, Yichuan; Yang, Yi; Klug, David R; Li, Yat; Cowan, Alexander J

    2015-07-15

    Intrinsic doping of hematite through the inclusion of oxygen vacancies (VO) is being increasingly explored as a simple, low temperature route to preparing active water splitting α-Fe2O3-x photoelectrodes. Whilst it is widely accepted that the introduction of VO leads to improved conductivities, little else is verified regarding the actual mechanism of enhancement. Here we employ transient absorption (TA) spectroscopy to build a comprehensive kinetic model for water oxidation on α-Fe2O3-x . In contrast to previous suggestions, the primary effect of introducing VO is to block very slow (ms) surface hole - bulk electron recombination pathways. In light of our mechanistic research we are also able to identify and address a cause of the high photocurrent onset potential, a common issue with this class of electrodes. Atomic layer deposition (ALD) of Al2O3 is found to be particularly effective with α-Fe2O3-x , leading to the photocurrent onset potential shifting by ca. 200 mV. Significantly TA measurements on these ALD passivated electrodes also provide important insights into the role of passivating layers, that are relevant to the wider development of α-Fe2O3 photoelectrodes.

  19. Antimicrobial Effect of Imipenem-Functionalized Fe2O3 Nanoparticles on Pseudomonas aeruginosa Producing Metallo β-lactamases.

    Science.gov (United States)

    Khataminejad, Mohammad Reza; Mirnejad, Reza; Sharif, Malike; Hashemi, Mojtaba; Sajadi, Nikita; Piranfar, Vahhab

    2015-12-01

    Resistant strains of Pseudomonas aeruginosa to imipenem was medical treatment problem, especially in burnt units of hospitals. This study was conducted to evaluate the antimicrobial effect of Fe2O3 nanoparticles alone and functionalized with imipenem on P. aeruginosa starins producing metallo β-lactamases (MBL). A disk diffusion method was used to isolate a clinical P. aeruginosa producing Metallo β-lactamases with imipenem resistance. The minimum inhibitory concentration (MIC) of Fe2O3 nanoparticles and imipenem were calculated against the bacteria. The antimicrobial effect of nanoparticles functionalized with the antibiotic was determined. Standard strain of P. aeruginosa ATCC: 27853 was used as control. The clinical sample was resistant to imipenem (up to 28 μg.mL(-1)). Similarly, MIC of the nanoparticles against the isolate was 160 μg.mL(-1). Subsequently, the combination of 16 pg.mL(-1) of antibiotic with 80 μg.mL(-1) of Fe2O3 nanoparticles were able to inhibit the growth of the isolate. Fe2O3 nanoparticles functionalized with imipenem can impair antibiotic resistance mechanisms of bacteria as it can make the imipenem resistant the aforementioned bacterium more susceptible to weaker concentrations of antibiotic. It also has its own antibacterial effect in certain concentrations.

  20. Extrusion of Fe2O3/SBA-15 mesoporous material for application as heterogeneous Fenton-like catalyst

    Directory of Open Access Journals (Sweden)

    María Isabel Pariente

    2015-03-01

    Full Text Available The aim of this work has been the extrusion of powder Fe2O3/SBA-15 catalyst in order to be successfully used in continuous catalytic fixed bed reactors as Fenton-like catalyst. The extrusion method was optimised using an amorphous silica material of similar properties than the Fe2O3/SBA-15 catalyst. The main studied variable was the composition of the extrusion paste using bentonite and methylcellulose as inorganic and organic binders, respectively. The organic content displayed a significant influence on the mechanical strength and specific surface area of the final extrudates. In contrast, the inorganic binder content hardly affected the final properties (in the studied range. The extruded Fe2O3/SBA-15 material showed a remarkable mechanical strength as well as the typical mesoporous structure of Fe2O3/SBA-15 with a relevant specific surface area (264 m2/g. The extruded catalyst achieved a high catalytic performance in the catalytic wet peroxide oxidation of phenol with a 60 % of total organic carbon reduction in both batch and continuous processes.

  1. EFFECT OF Fe2O3 ON WELDING TECHNOLOGY AND MECHANICAL PROPERTIES OF WELD METAL DEPOSITED BY SELF-SHIELDED FLUX CORED WIRE

    Institute of Scientific and Technical Information of China (English)

    Yu Ping; Pan Chuan; Xue Jin; Li Zhengbang

    2005-01-01

    Five experimental self-shielded flux cored wires are fabricated with different amount of Fe2O3 in the flux. The effect of Fe2O3 on welding technology and mechanical properties of weld metals deposited by these wires are studied. The results show that with the increase of Fe2O3 in the mix, the melting point of the pretreated mix is increased. LiBaF3 and BaFe12O19, which are very low in inherent moisture, are formed after the pretreatment. The mechanical properties are evaluated to the weld metals. The low temperature notch toughness of the weld metals is increased linearly with the Fe2O3 content in the flux due to the balance between Fe2O3 and residual Al in the weld metal. The optimum Fe2O3 content in flux is 2.5%~3.5 %.

  2. ADSORPSI ION CU(II MENGGUNAKAN PASIR LAUT TERAKTIVASI H2SO4 DAN TERSALUT Fe2O3

    Directory of Open Access Journals (Sweden)

    DS Pambudi

    2014-11-01

    Full Text Available Pasir laut merupakan bahan alam yang melimpah. Selain digunakan sebagai bahan bangunan, pasir dapat dimanfaatkan sebagai penjerap ion logam berat mengingat 30% lebih dari volumenya adalah pori-pori. Tujuan penelitian adalah untuk mengetahui kapasitas adsorpsi ion logam Cu(II menggunakan pasir laut kontrol, pasir laut teraktivasi H2SO4, pasir laut tersalut Fe2O3, serta pasir laut teraktivasi H2SO4 dan tersalut Fe2O3. Ada dua macam pasir laut yang digunakan, yaitu pasir hitam dan pasir putih. Kajian yang dilakukan meliputi optimasi adsorben pada variasi pH, konsentrasi ion logam, dan waktu kontak. Optimasi pH diperoleh pada pH 7, optimasi konsentasi ion logam diperoleh 250 ppm untuk pasir hitam dan 200 ppm untuk pasir putih, dan optimasi waktu diperoleh 60 menit untuk pasir hitam dan 90 menit untuk pasir putih. Kapasitas adsorpsi pasir laut teraktivasi H2SO4 dan tersalut Fe2O3 dalam menyerap ion logam tembaga sebesar 24,8634 mg/g untuk pasir hitam dan 19,8854 mg/g untuk pasir putih. Sebanyak 6,5 g pasir hitam teraktivasi H2SO4 dan tersalut Fe2O3 digunakan untuk menyerap limbah pada konsentrasi Cu(II sebesar 2960,32 ppm dengan persentase teradsorpsi sebesar 94,70%. Sedangkan pada pasir putih teraktivasi H2SO4 dan tersalut Fe2O3, sebanyak 8 g pasir digunakan untuk menyerap limbah dengan konsentrasi Cu(II sebesar 2984,13 ppm, hasilnya menunjukkan 92,56% ion logam Cu(II teradsorp. Sea sand is abundant natural materials. In addition to be used as a building material, sand can be utilized as heavy metal ion adsorbent, because it has quite a lot of pores, i.e 30% more than its volume. The purpose of this study was to determine the adsorption capacity of Cu(II ions using sea sand alone as control, H2SO4-activated sea sand, Fe2O3-coated sea sand, as well as H2SO4-activated and Fe2O3-coated sea sand. Two kinds of sea sand have been used in the research, i.e the black sand and the white sand. Studies were performed to examine the optimization of the

  3. Self-Assembled α-Fe2O3 mesocrystals/graphene nanohybrid for enhanced electrochemical capacitors.

    Science.gov (United States)

    Yang, Shuhua; Song, Xuefeng; Zhang, Peng; Sun, Jing; Gao, Lian

    2014-06-12

    Self-assembled α-Fe2O3 mesocrystals/graphene nanohybrids have been successfully synthesized and have a unique mesocrystal porous structure, a large specific surface area, and high conductivity. Mesocrystal structures have recently attracted unparalleled attention owing to their promising application in energy storage as electrochemical capacitors. However, mesocrystal/graphene nanohybrids and their growth mechanism have not been clearly investigated. Here we show a facile fabrication of short rod-like α-Fe2O3 mesocrystals/graphene nanohybrids by self-assembly of FeOOH nanorods as the primary building blocks on graphene under hydrothermal conditions, accompanied and promoted by concomitant phase transition from FeOOH to α-Fe2O3. A systematic study of the formation mechanism is also presented. The galvanostatic charge/discharge curve shows a superior specific capacitance of the as-prepared α-Fe2O3 mesocrystals/graphene nanohybrid (based on total mass of active materials), which is 306.9 F g(-1) at 3 A g(-1) in the aqueous electrolyte under voltage ranges of up to 1 V. The nanohybrid with unique sufficient porous structure and high electrical conductivity allows for effective ion and charge transport in the whole electrode. Even at a high discharge current density of 10 A g(-1), the enhanced ion and charge transport still yields a higher capacitance (98.2 F g(-1)), exhibiting enhanced rate capability. The α-Fe2O3 mesocrystal/graphene nanohybrid electrode also demonstrates excellent cyclic performance, which is superior to previously reported graphene-based hematite electrode, suggesting it is highly stable as an electrochemical capacitor.

  4. Helium and neon diffusion in pure hematite (α-Fe2O3) crystal lattice

    Science.gov (United States)

    Balout, Hilal; Roques, Jérôme; Gautheron, Cécile; Tassan-Got, Laurent

    2016-04-01

    Hematite (α-Fe2O3) has the corundum-type structure and is relatively present on Earth and Mars surface associated to ore mineral precipitation or as a weathering phase. He and Ne retention in such mineral has been intensively investigated experimentally because of the potential use of (U-Th-Sm)/(He-Ne) chronometer and thermochronometer. Therefore, the He/Ne diffusion in hematite crystal is an important issue for the interpretation of (U-Th)/(He-Ne) thermochronometric ages. For this purpose an accurate investigation of helium and neon diffusion in hematite crystal lattice has been achieved by computational multi-scale approach. Different insertion sites and diffusion pathways are first characterized where the spin polarized density functional theory (sp-DFT) approach coupled to the nudged elastic band (NEB) method is used to determine the migration energies between the insertion sites. Then, a statistical method, based on transition state theory (TST), is used to compute the jump probability between sites. The previous results are used as input data in a 3D random walk simulation, which permits to determine the effective activation energy and diffusion coefficient. Using the He/Ne diffusion coefficients, the closure temperature Tc has been calculated. For typical grain size of 100 microns, Tc will be of 116° C and 297° C for He and Ne atoms, respectively. These results Show that He and Ne atoms are highly retained in the crystal lattice at surface temperature. The obtained diffusion coefficients confirm that He/Ne retentively power in hematite lattice is very important, allowing a large range of different geological applications such the measurement of hematite crystallization ages on Earth and Mars.

  5. Spontaneous Water Oxidation at Hematite (α-Fe2O3) Crystal Faces

    Energy Technology Data Exchange (ETDEWEB)

    Chatman, Shawn ME; Zarzycki, Piotr P.; Rosso, Kevin M.

    2015-01-28

    Hematite (α-Fe2O3) persists as a promising candidate for photoelectrochemical water splitting but a slow oxygen evolution reaction (OER) at its surfaces remains a limitation. Here we extend a series of studies that examine pH-dependent surface potentials and electron transfer properties of effectively perfect low-index crystal faces of hematite in contact with simple electrolyte. Zero resistance amperometry was performed in a two electrode configuration to quantify spontaneous dark current between hematite crystal face pairs (001)/(012), (001)/(113), and (012)/(113) at pH 3. Exponentially decaying currents initially of up to 200 nA were reported between faces over four minute experiments. Fourth order ZRA kinetics indicated rate limitation by the OER for current that flows between (001)/(012) and (001)/(113) face pairs, with the (012) and (113) faces serving as the anodes when paired with (001). The cathodic partner reaction is reductive dissolution of the (001) face, converting surface Fe3+ to solubilized aqueous Fe2+, at a rate maintained by the OER at the anode. In contrast, OER rate limitation does not manifest for the (012)/(113) pair. The uniqueness of the (001) face is established in terms of a faster intrinsic ability to accept the protons required for the reductive dissolution reaction. OER rate limitation inversely may thus arise from sluggish kinetics of hematite surfaces to dispense with the protons that accompany the four-electron OER. The results are explained in terms of semi-quantitative energy band diagrams. The finding may be useful as a consideration for tailoring the design of polycrystalline hematite photoanodes that present multiple terminations to the interface with electrolyte.

  6. High photocatalytic activity of Fe2O3/TiO2 nanocomposites prepared by photodeposition for degradation of 2,4-dichlorophenoxyacetic acid.

    Science.gov (United States)

    Lee, Shu Chin; Lintang, Hendrik O; Yuliati, Leny

    2017-01-01

    Two series of Fe2O3/TiO2 samples were prepared via impregnation and photodeposition methods. The effect of preparation method on the properties and performance of Fe2O3/TiO2 for photocatalytic degradation of 2,4-dichlorophenoxyacetic acid (2,4-D) under UV light irradiation was examined. The Fe2O3/TiO2 nanocomposites prepared by impregnation showed lower activity than the unmodified TiO2, mainly due to lower specific surface area caused by heat treatment. On the other hand, the Fe2O3/TiO2 nanocomposites prepared by photodeposition showed higher photocatalytic activity than the unmodified TiO2. Three times higher photocatalytic activity was obtained on the best photocatalyst, Fe2O3(0.5)/TiO2. The improved activity of TiO2 after photodeposition of Fe2O3 was contributed to the formation of a heterojunction between the Fe2O3 and TiO2 nanoparticles that improved charge transfer and suppressed electron-hole recombination. A further investigation on the role of the active species on Fe2O3/TiO2 confirmed that the crucial active species were both holes and superoxide radicals. The Fe2O3(0.5)/TiO2 sample also showed good stability and reusability, suggesting its potential for water purification applications.

  7. High photocatalytic activity of Fe2O3/TiO2 nanocomposites prepared by photodeposition for degradation of 2,4-dichlorophenoxyacetic acid

    Directory of Open Access Journals (Sweden)

    Shu Chin Lee

    2017-04-01

    Full Text Available Two series of Fe2O3/TiO2 samples were prepared via impregnation and photodeposition methods. The effect of preparation method on the properties and performance of Fe2O3/TiO2 for photocatalytic degradation of 2,4-dichlorophenoxyacetic acid (2,4-D under UV light irradiation was examined. The Fe2O3/TiO2 nanocomposites prepared by impregnation showed lower activity than the unmodified TiO2, mainly due to lower specific surface area caused by heat treatment. On the other hand, the Fe2O3/TiO2 nanocomposites prepared by photodeposition showed higher photocatalytic activity than the unmodified TiO2. Three times higher photocatalytic activity was obtained on the best photocatalyst, Fe2O3(0.5/TiO2. The improved activity of TiO2 after photodeposition of Fe2O3 was contributed to the formation of a heterojunction between the Fe2O3 and TiO2 nanoparticles that improved charge transfer and suppressed electron–hole recombination. A further investigation on the role of the active species on Fe2O3/TiO2 confirmed that the crucial active species were both holes and superoxide radicals. The Fe2O3(0.5/TiO2 sample also showed good stability and reusability, suggesting its potential for water purification applications.

  8. 纳米α-Fe2O3改性聚乙烯醇基蜂蜡复合涂膜材料工艺优化%Technology optimization of nanosizedα-Fe2O3 and beeswax modified polyvinyl alcohol based composite packaging material

    Institute of Scientific and Technical Information of China (English)

    李璨; 王佳媚; 龙门; 刘瑶; 刘桂超; 顾凤兰; 章建浩

    2014-01-01

    Polyvinyl alcohol has been widely used as a packaging substrate, but its water resistance is poor. Improving the water resistance of polyvinyl alcohol is critical. In this study the major modification methods were to add nano-materials, fats or oil substances and crosslinking agents. Functional nanomaterials have small size, large surface area that combine the hydroxyl group with polyvinyl alcohol to reduce the hydrophilic. Beeswax is a composition material by fats and oils. It has higher melting point, acid corrosion, water-blocking performance characteristics. Furthermore it can form a stable emulsion, resulting in long shelf life, high solid content, good dispersion and other fine features. Beeswax is widely used in fruit and vegetable preservation, fruits and vegetables can reduce the water loss rate and respiration. In this experiment a stable emulsion with polyvinyl alcohol (PVA) was formed from hydrophobic of beeswax and the small surface area, high activity of nanosizedα-Fe2O3 to reduce film water vapor transmission rate of packing material of polyvinyl alcohol efficiently. By adding beeswax and nanosizedα-Fe2O3 to polyvinyl alcohol based composite coating material, the impacts of film-forming water vapor transmission rate and its interaction was studied through analyzing the response surface between the two experimental factors. The result showed that the increasing amount of beeswax and then nosizedα-Fe2O3 could reduce the water vapor transmission rate of polyvinyl alcohol composite material effectively. Therefore two materials have mutual impacts (P<0.05). The beeswax dosage was 0.739 g/100mL, and nanosizedα-Fe2O3 was 0.04 g/100mL based on the regression optimization. The water vapor transmission rate reached the lowest point, which was lower than the former Liquid paraffin-polyvinyl alcohol film 73.76% (P<0.05). Meanwhile, nanosizedα-Fe2O3 could be used as a new nano-material. Its narrow band gap generally was 2.2 eV, the maximum absorption

  9. Core-shell structured α-Fe2O3@TiO2 nanocomposites with improved photocatalytic activity in the visible light region.

    Science.gov (United States)

    Xia, Yubing; Yin, Longwei

    2013-11-14

    The core-shell structured Fe2O3@TiO2 nanocomposites prepared via a heteroepitaxial growth route using the Fe2O3 spindle as a hard template display improved photocatalytic degradation activity for Rhodamine B dye under visible light irradiation. The ratio of α-Fe2O3 : TiO2 in the α-Fe2O3@TiO2 core-shell nanocomposites can be tuned by etching the α-Fe2O3 core via controlling the concentration of HCl and etching time. An appropriate concentration of the Fe2O3 core could effectively induce a transition of the optical response from the UV to the visible region and decrease the recombination rate of photogenerated electrons and the holes of the core-shell structured catalyst, greatly contributing to the enhancement of visible light response and visible light photocatalytic activity of the Fe2O3@TiO2 catalysts. It is revealed that the optical response and photocatalytic performance of the core-shell α-Fe2O3@TiO2 nanocomposites can be tuned by adjusting the molar ratio of Fe2O3 : TiO2 of the α-Fe2O3@TiO2 nanocomposites. The α-Fe2O3@TiO2 core-shell nanocomposite with an optimal molar ratio of 7% for Fe2O3 : TiO2 exhibits the best photocatalytic performance under visible light irradiation. It is shown that the Fe2O3/TiO2 heterojunction structure is responsible for the efficient visible-light photocatalytic activity. As the concentration of Fe2O3 is high, Fe(3+) ions will act as recombination centres of the photogenerated electrons and holes. The present core-shell Fe2O3@TiO2 nanoparticles displaying enhanced photodegradation activity could find potential applications as photocatalysts for the abatement of various organic pollutants.

  10. A highly efficient visible-light-driven novel p-n junction Fe2O3/BiOI photocatalyst: Surface decoration of BiOI nanosheets with Fe2O3 nanoparticles

    Science.gov (United States)

    Mehraj, Owais; Pirzada, Bilal M.; Mir, Niyaz A.; Khan, Mohammad Zain; Sabir, Suhail

    2016-11-01

    Novel xFe2O3/yBiOI composites (x/y = 0.25, 0.35, 0.45 molar ratios) with a p-n heterojunction were prepared for the first time through an in situ hydrolysis method under solvothermal conditions. The phase structure, morphology and optical properties of the composites were studied using several characterization tools including X-ray diffraction (XRD), scanning electron microscopy (SEM), high resolution transmission electron microscopy (HRTEM), selected area electron diffraction (SAED), Fourier transform infrared (FTIR), N2 adsorption-desorption isotherms (BET) and UV-vis diffuse reflectance spectroscopy (UV-DRS). The characterization results suggest square shaped nanosheets of BiOI with Fe2O3 nanoparticles well distributed on the surface of BiOI nanosheets. The photodegradation performances of the xFe/yBi samples were investigated using aqueous solution of Rhodamine B (RhB) dye. The xFe/yBi composites displayed much higher photocatalytic efficiencies for RhB degradation than the single BiOI under visible light (λ > 400 nm). Specifically, the degradation rate of xFe/yBi samples at molar ratio of 0.35 is 4.24 times higher than single BiOI. The novel Fe2O3/BiOI heterojunction was found to be highly stable in cyclic experiments. Based on the results of BET, PL and DRS analysis, the enhanced photocatalytic efficiency can be mainly ascribed to the formation of stable p-n heterojunction between Fe2O3 and BiOI, which facilitates the transfer and separation of photogenerated electron-hole pairs.

  11. Synthesis ofα-Fe2 O3 Nonmaterial and Its Application in Light Catalytic%α-Fe2 O3 纳米材料的合成及其在光催化中的应用

    Institute of Scientific and Technical Information of China (English)

    李杰; 李焕莲

    2015-01-01

    In this study, the alpha Fe2O3 nanometer materials have been prepared ,using ferric chloride,glycerol and urea as reactant ,and a very simple experiment synthesis method ,hydrothermal method .The surface morphology and structure of the product have been characterized ,using the X -ray diffraction ( XRD) .The size and morpholo-gy of the particle have been observed by scanning electron microscope (SEM).With methyl orange solution degra-dation as the target , with experimental light source of xenon lamp , light catalytic performance of the product have been studied ,and the light catalytic properties of the alpha Fe 2 O3 nonmaterial prepared have been expounded .Stud-ies have shown that the resulting product for methyl orange has better photocatalytic performance ,and degradation rate can reach 70%after 80 min reaction .%本文以氯化铁、甘油和尿素为反应物,采用一种设备简单、操作便捷的实验合成方法―水热法,制备了α-Fe2 O3 纳米材料,并采用X-ray射线衍射仪( XRD)对所制备产品的晶体结构进行了表征;用扫描电子显微镜(SEM)对所制备α-Fe2O3 粒子的形貌和大小进行了观察;以甲基橙溶液为目标降解物,以氙灯为实验光源对产物的光催化性能进行研究,研究表明所得产物对于甲基橙有较好的光催化性能,反应80min后降解率可以达到70%.

  12. Simultaneous influence of gas mixture composition and process temperature on Fe2O3->FeO reduction kinetics: neural network modeling

    Directory of Open Access Journals (Sweden)

    K. Piotrowski

    2005-09-01

    Full Text Available The kinetics of Fe2O3->FeO reaction was investigated. The thermogravimetric (TGA data covered the reduction of hematite both by pure species (nitrogen diluted CO or H2 and by their mixture. The conventional analysis has indicated that initially the reduction of hematite is a complex, surface controlled process, however once a thin layer of lower oxidation state iron oxides (magnetite, wüstite is formed on the surface, it changes to diffusion control. Artificial Neural Network (ANN has proved to be a convenient tool for modeling of this complex, heterogeneous reaction runs within the both (kinetic and diffusion regions, correctly considering influence of temperature and gas composition effects and their complex interactions. ANN's model shows the capability to mimic some extreme (minimum of the reaction rate within the determined temperature window, while the Arrhenius dependency is of limited use.

  13. Trajectory control of PbSe-γ-Fe2O3 nanoplatforms under viscous flow and an external magnetic field

    Science.gov (United States)

    Etgar, Lioz; Nakhmani, Arie; Tannenbaum, Allen; Lifshitz, Efrat; Tannenbaum, Rina

    2010-04-01

    The flow behavior of nanostructure clusters, consisting of chemically bonded PbSe quantum dots and magnetic γ-Fe2O3 nanoparticles, has been investigated. The clusters are regarded as model nanoplatforms with multiple functionalities, where the γ-Fe2O3 magnets serve as transport vehicles, manipulated by an external magnetic field gradient, and the quantum dots act as fluorescence tags within an optical window in the near-infrared regime. The clusters' flow was characterized by visualizing their trajectories within a viscous fluid (mimicking a blood stream), using an optical imaging method, while the trajectory pictures were analyzed by a specially developed processing package. The trajectories were examined under various flow rates, viscosities and applied magnetic field strengths. The results revealed a control of the trajectories even at low magnetic fields (<1 T), validating the use of similar nanoplatforms as active targeting constituents in personalized medicine.

  14. Applications of nanoparticles of gamma Fe2O3 for hyperthermia in E.coli by Nd:YAG laser

    CERN Document Server

    Kundu, Srikanya; Kulkarni, S D; Pasricha, Renu; Das, A K; Kulkarni, G R; Bhoraskar, S V

    2007-01-01

    The paper explores the use of nanoparticles of gamma Fe2O3 for hyperthermia treatment of living organisms by absorption of 1064 nm radiations from Nd:YAG laser. Escherichia coli cells have been used as the model system for demonstrating the effect wherein lysine is used as an interface between the cell walls and the nanoparticles. Scanning Electron Microscopic observations have, exclusively, proved that attachment of nanoparticles of iron oxide along with lysine alone is responsible for absorption of above radiations. The quantitative estimation has been provided by growth rate measurements and protein assessment of the cells. The nanoparticles of gamma Fe2O3 were synthesized by DC arc plasma assisted gas phase condensation.

  15. Polypyrrole layer coated MnOx/Fe2O3 nanotubes with enhanced electrochemical performance for lithium ion batteries

    Science.gov (United States)

    Jin, Rencheng; Wang, Qingyao; Li, Honghao; Ma, Yuqian; Sun, Yexian; Li, Guihua

    2017-05-01

    MnOx/Fe2O3/polypyrrole nanotubes have been fabricated by a facile method, which involves a hydrothermal method, chemical solution route, annealing process and a subsequent chemical polymerization method. Electrochemical measurement shows that MnOx/Fe2O3/polypyrrole nanotubes display excellent electrochemical properties. A reversible specific capacity of 1060 mA h g-1 is achieved after 100 cycles at the current density of 200 mA g-1. Even at higher current density of 5000 mA g-1, the specific capacity of the electrode can be kept at 630 mA h g-1. The excellent electrochemical performances are ascribed to the synergetic effect of different components and the conductive polypyrrole layer.

  16. Synthesis, characterization, and catalytic applications of hematite (α-Fe2O3) nanoparticles as reusable nanocatalyst

    Science.gov (United States)

    Basavegowda, Nagaraj; Mishra, Kanchan; Rok Lee, Yong

    2017-06-01

    A novel magnetically recoverable hematite nanoparticles (α-Fe2O3 NPs) was fabricated by a simple, one pot, and green method using the rhizome of Cyperus rotundus L., as a reducing and stabilizing agent. The prepared nanoparticles were well characterized by all parameters. TEM showed that the hematite nanoparticles had a rhombohedral shape and ranged in size from 80 to 100 nm. The phase study of the α-Fe2O3 nanoparticles was confirmed by Raman spectroscopy. In addition, the synthesized nanoparticles shows good photocatalytic activity in degradation of highly toxic Congo red dye within 25 min, and the same NPs exhibits higher catalytic activity for the reduction of 4-nitro-o-phenylenediamine (4-NPD) to 1,2,4-benzenetriamine in the presence of NaBH4 within 12 min. After the reaction, the catalyst was recovered and reused three times without significant loss of catalytic activity.

  17. Trajectory control of PbSe-gamma-Fe2O3 nanoplatforms under viscous flow and an external magnetic field.

    Science.gov (United States)

    Etgar, Lioz; Nakhmani, Arie; Tannenbaum, Allen; Lifshitz, Efrat; Tannenbaum, Rina

    2010-04-30

    The flow behavior of nanostructure clusters, consisting of chemically bonded PbSe quantum dots and magnetic gamma-Fe(2)O(3) nanoparticles, has been investigated. The clusters are regarded as model nanoplatforms with multiple functionalities, where the gamma-Fe(2)O(3) magnets serve as transport vehicles, manipulated by an external magnetic field gradient, and the quantum dots act as fluorescence tags within an optical window in the near-infrared regime. The clusters' flow was characterized by visualizing their trajectories within a viscous fluid (mimicking a blood stream), using an optical imaging method, while the trajectory pictures were analyzed by a specially developed processing package. The trajectories were examined under various flow rates, viscosities and applied magnetic field strengths. The results revealed a control of the trajectories even at low magnetic fields (<1 T), validating the use of similar nanoplatforms as active targeting constituents in personalized medicine.

  18. Fe2O3 as indicator of heavy metal enrichment in Zhujiang(Pearl River) estuary sediments

    Institute of Scientific and Technical Information of China (English)

    彭晓彤; 周怀阳; 潘建明; 扈传昱

    2002-01-01

    A part of the heavy metals in estuary and coastal zone occurs naturally in the environment; the other part is due to human activity; so the directly measured concentration of heavy metal does not automatically indicate anthropogenic enrichment. Fe2O3 was used in this study as conservative tracer to distinguish natural components from anthropogenic components of heavy metal sediment concentration in the Zhujiang estuary. Compared with clay and Al2O3, Fe2O3 is more suitable as reference element. The final results showed that two zones in the Zhujiang estuary were seriously contaminated by heavy metals. One nearby the Humen mouth; the other around the west coast of the estuary. The horizontal distribution of heavy metals indicates that Zn, Ni and Cu have wider contaminating areas than TiO2, V and Cr in the estuary.

  19. Synthesis, Charaterization and Electrochemical Sensing Properties of PANI—Cobalt doped α-Fe2O3 Nanocomposites

    Science.gov (United States)

    Suresh, R.; Vijayalakshmi, L.; Stephen, A.; Narayanan, V.

    2011-07-01

    The PANI-NSA/(4%Co)α-Fe2O3 composite was prepared by a template free method in the presence of β-Napthalene sulphonic acid (β-NSA) as a dopant for PANI. The FTIR spectroscopy was used to confirm the formation of the composite. The structural property of the composite was characterized by XRD. The morphological property of the composite was characterized by SEM. The SEM image of composite showed that the particles are homogenous. The electrochemical sensing ability of ascorbic acid (AA) by PANI-NSA and composite modified GCE exhibited higher anodic current response than the bare GCE. Compared with the bare and PANI-NSA modified GCE, PANI-NSA/(4%Co)α-Fe2O3 composite modified GCE showed larger current response with shift towards less positive potential.

  20. Carbon nanotube-wrapped Fe2O3 anode with improved performance for lithium-ion batteries.

    Science.gov (United States)

    Gao, Guoliang; Jin, Yan; Zeng, Qun; Wang, Deyu; Shen, Cai

    2017-01-01

    Metall oxides have been proven to be potential candidates for the anode material of lithium-ion batteries (LIBs) because they offer high theoretical capacities, and are environmentally friendly and widely available. However, the low electronic conductivity and severe irreversible lithium storage have hindered a practical application. Herein, we employed ethanolamine as precursor to prepare Fe2O3/COOH-MWCNT composites through a simple hydrothermal synthesis. When these composites were used as electrode material in lithium-ion batteries, a reversible capacity of 711.2 mAh·g(-1) at a current density of 500 mA·g(-1) after 400 cycles was obtained. The result indicated that Fe2O3/COOH-MWCNT composite is a potential anode material for lithium-ion batteries.

  1. The effects of Fe2O3 nanoparticles on physiology and insecticide activity in non-transgenic and Bt-transgenic cotton

    Directory of Open Access Journals (Sweden)

    Nhan eLe Van

    2016-01-01

    Full Text Available As the demands for nanotechnology and nanoparticle (NP applications in agriculture increase, the ecological risk has drawn more attention because of the unpredictable results of interactions between NPs and transgenic crops. In this study, we investigated the effects of various concentrations of Fe2O3 NPs on Bt-transgenic cotton in comparison with conventional cotton for 10 days. Each treatment was conducted in triplicate, and each experiment was repeated three times. Results demonstrated that Fe2O3 nanoparticles (NPs inhibited the plant height and root length of Bt-transgenic cotton and promoted root hairs and biomass of non-transgenic cotton. Nutrients such as Na and K in Bt-transgenic cotton roots increased, while Zn contents decreased with Fe2O3 NPs. Most hormones in the roots of Bt-transgenic cotton increased at low Fe2O3 NP exposure (100 mg·L−1 but decreased at high concentrations of Fe2O3 NPs (1000 mg·L−1. Fe2O3 NPs increased the Bt-toxin in leaves and roots of Bt-transgenic cotton. Fe2O3 NPs were absorbed into roots, then transported to the shoots of both Bt-transgenic and non-transgenic cottons. The bioaccumulation of Fe2O3 NPs in plants might be a potential risk for agricultural crops and affect the environment and human health.

  2. Nano -propylsulphonated -Fe2O3: A novel magnetically recyclable heterogeneous catalyst for the efficient synthesis of bis(pyrazolyl)methanes in water

    Indian Academy of Sciences (India)

    Sara Sobhani; Zahra Pakdin-Parizi; Razieh Nasseri

    2013-09-01

    Nano -propylsulphonated -Fe2O3 (NPS--Fe2O3) was applied as a new magnetically recyclable heterogeneous catalyst for the efficient one-pot synthesis of bis(pyrazolyl)methanes in water. The catalyst was easily isolated from the reaction mixture by a magnetic bar and reused at least five times without significant degradation in activity.

  3. Nanostructured reduced graphene oxide/Fe2O3 composite as a high-performance anode material for lithium ion batteries.

    Science.gov (United States)

    Zhu, Xianjun; Zhu, Yanwu; Murali, Shanthi; Stoller, Meryl D; Ruoff, Rodney S

    2011-04-26

    Reduced graphene oxide/Fe(2)O(3) composite was prepared using a facile two-step synthesis by homogeneous precipitation and subsequent reduction of the G-O with hydrazine under microwave irradiation to yield reduced graphene oxide (RG-O) platelets decorated with Fe(2)O(3) nanoparticles. As an anode material for Li-ion batteries, the RG-O/Fe(2)O(3) composite exhibited discharge and charge capacities of 1693 and 1227 mAh/g, respectively, normalized to the mass of Fe(2)O(3) in the composite (and ∼1355 and 982 mAh/g, respectively, based on the total mass of the composite), with good cycling performance and rate capability. Characterization shows that the Fe(2)O(3) nanoparticles are uniformly distributed on the surface of the RG-O platelets in the composite. The total specific capacity of RG-O/Fe(2)O(3) is higher than the sum of pure RG-O and nanoparticle Fe(2)O(3), indicating a positive synergistic effect of RG-O and Fe(2)O(3) on the improvement of electrochemical performance. The synthesis approach presents a promising route for a large-scale production of RG-O platelet/metal oxide nanoparticle composites as electrode materials for Li-ion batteries.

  4. Ti-doped hematite thin films for efficient water splitting

    Science.gov (United States)

    Atabaev, Timur Sh.; Ajmal, Muhammad; Hong, Nguyen Hoa; Kim, Hyung-Kook; Hwang, Yoon-Hwae

    2015-03-01

    Uniform Ti-doped hematite thin films were deposited on transparent fluorine-doped tin oxide FTO coated glasses using a pulsed laser deposition method. An influence of dopant concentration on the photoelectrochemical characteristics was examined under water splitting. Photocurrent measurements indicated that 3 mol% of Ti atoms was optimal dopant concentration in hematite films produced by this method. The maximum photocurrent density of un-doped and 3 mol% Ti-doped Fe2O3 photoelectrodes was 0.67 and 1.64 mA/cm2 at 1.23 V versus RHE, respectively. The incorporation of Ti atoms into hematite photoelectrodes was found to drastically enhance the water splitting performance.

  5. SYNTHESIS AND INTERFACIAL STRUCTURE OF NANOPARTICLESγ-Fe2O3 COATED WITH SURFACTANT DBS AND CTAB

    Institute of Scientific and Technical Information of China (English)

    1999-01-01

    The γ-Fe2O3 nanoparticles coated with DBS and CTAB were prepared by the microemulsion method.The coated samples show enhanced nonlinear optical properties compared with their bulk couterpart.The.Moessbauer spectra at room temperature were measured for the coated ferric oxides.The monolayers of the organic molecule are found to have a strong chemical bond with the surface atoms and thus have a significant influence on the electron structure of particle surface.@ 1999 Acta Metallurgica Inc.

  6. Synthesis of Monolithic Fe2O3-Al2O3 Composite Aerogels via Organic Solvent Sublimation Drying

    Directory of Open Access Journals (Sweden)

    Lili Ren

    2016-01-01

    Full Text Available Monolithic Fe2O3-Al2O3 composite aerogels have been prepared successfully via organic solvent sublimation drying method. The results show that a new phase forms when the right amount of ferric oxide is added to the alumina aerogel. From the TEM pictures we can see a shuttle-type structure with the length of about 15 nm forms, which leads to the high surface areas of composited aerogel.

  7. Iron (III oxide fabrication from natural clay with reference to phase transformation γ- → α-Fe2O3

    Directory of Open Access Journals (Sweden)

    Šaponjić Aleksandra

    2017-01-01

    Full Text Available Amorphous iron (III oxide was obtained from clay, using ammonium hydroxide as a precipitating agent. Influence of freeze drying under vacuum, as a drying method, on particle size, chemical composition, and crystallinity of obtained iron (III oxide powder was investigated. After freeze drying, precipitate was annealed in air at 500°C and 900°C. X-ray diffraction, particle size analysis, scanning electron microscopy, energy dispersive spectrometry, Fourier transform infrared spectroscopy, thermogravimetric and differential thermal analysis were used to characterize obtained iron (III oxide powder. All of three powders obtained by freeze drying and annealing, have low crystallinity and particles with irregular layered shape. Narrow particle size distribution was given by an average diameter value of around 50 μm for all observed powders. Iron-bearing materials like α-Fe2O3 and γ- Fe2O3 are obtained. Differential thermal analysis curve of obtained samples showed endothermic reaction at 620°C which could be ascribed to phase transition from cubic form γ- → α- Fe2O3. Thermal transformations of iron (III oxide, obtained from clay as a natural source, is suitable to explore in the framework of materials chemistry, and opens the possibility to synthesize materials based on Fe2O3 with specific magnetic behavior. [Project of the Serbian Ministry of Education, Science and Technological Development, Grant no. III-45012, Grant no. OI-172045, Grant no. III-45015, Grant no. OI-176010, Grant no. OI-172056 and Grant no. III-45007

  8. Hydrophilic Fe2O3 dynamic membrane mitigating fouling of support ceramic membrane in ultrafiltration of oil/water emulsion

    KAUST Repository

    Lu, Dongwei

    2016-03-17

    Oil/water (O/W) emulsion is daily produced and difficult to be treated effectively. Ceramic membrane ultrafiltration is one of reliable processes for the treatment of O/W emulsion, yet still hindered by membrane fouling. In this study, two types of Fe2O3 dynamic membranes (i.e., pre-coated dynamic membrane and self-forming dynamic membrane) were prepared to mitigate the fouling of support ceramic membrane in O/W emulsion treatment. Pre-coated dynamic membrane (DM) significantly reduced the fouling of ceramic membrane (i.e., 10% increase of flux recovery rate), while self-forming dynamic membrane aggravated ceramic membrane fouling (i.e., 8.6% decrease of flux recovery rate) after four filtration cycles. A possible fouling mechanism was proposed to explain this phenomenon, which was then confirmed by optical images of fouled membranes and the analysis of COD rejection. In addition, the cleaning efficiency of composite membranes (i.e., Fe2O3 dynamic membrane and support ceramic membrane) was enhanced by substitution of alkalescent water backwash for deionized water backwash. The possible reason for this enhancement was also explained. Our result suggests that pre-coated Fe2O3 dynamic membrane with alkalescent water backwash can be a promising technology to reduce the fouling of ceramic membrane and enhance membrane cleaning efficiency in the treatment of oily wastewater.

  9. The Dissolution Kinetics of MgO into CaO-MgO-Fe2O3 Slag

    Science.gov (United States)

    Wei, Ruirui; Lv, Xuewei; Yue, Zhiwen; Xiang, Shenglin

    2017-02-01

    Calcium ferrite is the main binding phase for high-basicity sinter. The production and structure of calcium ferrite greatly influence the quality of the sinter. With the change in gangue composition, MgO becomes an important factor in the generation of calcium ferrite. In this study, the rotating cylinder method was used to study the dissolution kinetics of MgO into CaO-MgO-Fe2O3 melt. The experimental variables included the temperature, the initial composition of the melt, the Fe2O3/CaO mass ratio, the rotation time, and the rotation speed. The results indicate that the dissolution rate increases with increasing dissolution time, temperature, and rotation speed but decreases with increasing MgO content and Fe2O3/CaO mass ratio in the initial slag. The dissolution rate was observed to increase and then decrease with the addition of SiO2 in the initial slag. The activation energy and diffusion coefficient for MgO dissolution were found to range from 117.31 to 234.24 kJ mol-1 and from 1.03 × 10-6 to 1.18 × 10-5 cm2 s-1, respectively. The concentration difference between the solid and liquid phases is the main driving force for dissolution, but the viscosity and magnesium ion diffusivity of the melt also affect the process.

  10. Light illuminated α-Fe2O3/Pt nanoparticles as water activation agent for photoelectrochemical water splitting.

    Science.gov (United States)

    Li, Xiaodong; Wang, Zhi; Zhang, Zemin; Chen, Lulu; Cheng, Jianli; Ni, Wei; Wang, Bin; Xie, Erqing

    2015-03-16

    The photoelectrochemical (PEC) water splitting is hampered by strong bonds of H2O molecules and low ionic conductivity of pure water. The photocatalysts dispersed in pure water can serve as a water activation agent, which provides an alternative pathway to overcome such limitations. Here we report that the light illuminated α-Fe2O3/Pt nanoparticles may produce a reservoir of reactive intermediates including H2O2, ·OH, OH(-) and H(+) capable of promoting the pure water reduction/oxidation half-reactions at cathode and highly photocatalytic-active TiO2/In2S3/AgInS2 photoanode, respectively. Remarkable photocurrent enhancement has been obtained with α-Fe2O3/Pt as water activation agent. The use of α-Fe2O3/Pt to promote the reactivity of pure water represents a new paradigm for reproducible hydrogen fuel provision by PEC water splitting, allowing efficient splitting of pure water without adding of corrosive chemicals or sacrificial agent.

  11. Measurement of Monochromatic Emissivity of Cement Clinker with Various Fe2O3 Content at High Temperature

    Institute of Scientific and Technical Information of China (English)

    Z.J.Ye; C.F.Ma; 等

    1996-01-01

    An applicatiopn of the optical pyrometer is studied for measuring monochromatic emissivities of cement clinker with various Fe2O3 contnet.The idsa of using “brightness temperature” is introduced into the eimssivity measurement.In this method,there is no need for measuring an actual temperature of sample surfaces,only with determining both brightness temperatures of a sample and a blackbody can the required emissivity be evaluated according to Wien's radiation law.In practice,the cement clinker is regarded as a greybody,the monochromatic emissivity is approximately equal to the total emissivity,so a single-colour optical pyrometer is applied for this purpose,Test measurements are carried out on 10 kinds of cement clinkers,Experimental data are treated by the least square method.As a result ,the emissivity variation with temperature at a certain Fe2O3 content is quite well represented by εn=a+bT.Furthermore,this work first reported that the eimissivities of cement clinker change consierably with Fe2O3 contents.In multiple cement production this conclusion is very important.

  12. Magnetic α-Fe2O3/MCM-41 nanocomposites: preparation, characterization, and catalytic activity for methylene blue degradation.

    Science.gov (United States)

    Ursachi, Irina; Stancu, Alexandru; Vasile, Aurelia

    2012-07-01

    Catalysts based on nanosized magnetic iron oxide stabilized inside the pore system of ordered mesoporous silica MCM-41 have been prepared. The obtained materials were characterized by powder X-ray diffraction analysis (XRD), scanning electron microscopy (SEM), vibrating sample magnetometer (VSM), and N(2) adsorption-desorption isotherm. XRD analysis showed that the obtained materials consist from the pure hematite crystalline phase (α-Fe(2)O(3)) dispersed within ordered mesoporous silica MCM-41. Magnetic measurements show that the obtained nanocomposites exhibit at room temperature weak ferromagnetic behavior with slender hysteresis. The catalytic activity of the magnetic α-Fe(2)O(3)/MCM-41 nanocomposites was evaluated by the degradation of methylene blue (MB) aqueous solution. For this purpose, an ultrasound-assisted Fenton-like process was used. The effect of solution pH on degradation of MB was investigated. The results indicated that US-H(2)O(2)-α-Fe(2)O(3)/MCM-41 nanocomposite system is effective for the degradation of MB, suggesting its great potential in removal of dyes from wastewater. It was found that the degradation rate of MB increases with decrease in the pH value of the solution.

  13. In-situ preparation of Fe2O3 hierarchical arrays on stainless steel substrate for high efficient catalysis

    Science.gov (United States)

    Yang, Zeheng; Wang, Kun; Shao, Zongming; Tian, Yuan; Chen, Gongde; Wang, Kai; Chen, Zhangxian; Dou, Yan; Zhang, Weixin

    2017-02-01

    Hierarchical array catalysts with micro/nano structures on substrates not only possess high reactivity from large surface area and suitable interface, but intensify mass transfer through shortening the diffusion paths of both reactants and products for high catalytic efficiency. Herein, we first demonstrate fabrication of Fe2O3 hierarchical arrays grown on stainless-steel substrates via in-situ hydrothermal chemical oxidation followed by heat treatment in N2 atmosphere. As a Fenton-like catalyst, Fe2O3 hierarchical arrays exhibit excellent catalytic activity and life cycle performance for methylene blue (MB) dye degradation in aqueous solution in the presence of H2O2. The Fe2O3 catalyst with unique hierarchical structures and efficient transport channels, effectively activates H2O2 to generate large quantity of •OH radicals and highly promotes reaction kinetics between MB and •OH radicals. Immobilization of hierarchical array catalysts on stainless-steel can prevent particles agglomeration, facilitate the recovery and reuse of the catalysts, which is expected promising applications in wastewater remediation.

  14. Electrical Investigation of Nanostructured Fe2O3/p-Si Heterojunction Diode Fabricated Using the Sol-Gel Technique

    Science.gov (United States)

    Mansour, Shehab A.; Ibrahim, Mervat M.

    2017-07-01

    Iron oxide (α-Fe2O3) nanocrystals have been synthesized via the sol-gel technique. The structural and morphological features of these nanocrystals were studied using x-ray diffraction, Fourier transform-infrared spectroscopy and transmission electron microscopy. Colloidal solution of synthesized α-Fe2O3 (hematite) was spin-coated onto a single-crystal p-type silicon (p-Si) wafer to fabricate a heterojunction diode with Mansourconfiguration Ag/Fe2O3/p-Si/Al. This diode was electrically characterized at room temperature using current-voltage (I-V) characteristics in the voltage range from -9 V to +9 V. The fabricated diode showed a good rectification behavior with a rectification factor 1.115 × 102 at 6 V. The junction parameters such as ideality factor, barrier height, series resistance and shunt resistance are determined using conventional I-V characteristics. For low forward voltage, the conduction mechanism is dominated by the defect-assisted tunneling process with conventional electron-hole recombination. However, at higher voltage, I-V ohmic and space charge-limited current conduction was became less effective with the contribution of the trapped-charge-limited current at the highest voltage range.

  15. Hexagonal nanoplates of NiO/CoO/Fe2O3 composite acting as an efficient photocatalytic and electrocatalytic water oxidation catalyst.

    Science.gov (United States)

    Zhao, Yukun; Zhang, Yan; Ding, Yong; Chen, Mindong

    2015-09-21

    A unique hexagonal sheet-shaped NiO/CoO/Fe2O3 composite with irregularly shaped nanoparticles was fabricated for the first time through a simple co-precipitation and hydrothermal method. The NiO/CoO/Fe2O3 composite was characterized by numerous techniques (TEM, HRTEM, PXRD, EDX, ICP-AES, BET, and XPS) to confirm its structure and composition. This structure of the NiO/CoO/Fe2O3 composite may enhance the photocatalytic and electrocatalytic performance for water oxidation. Compared with NiO, CoO and Fe2O3, the NiO/CoO/Fe2O3 composite exhibits a lower overpotential and a much smaller Tafel slope of 49 mV dec(-1) for water oxidation. At the same time, the composite possesses beneficial ferromagnetic properties and superior stability; thus, it can be used repeatedly without any loss in activity.

  16. Core-Shell Nanostructure of α-Fe2O3/Fe3O4: Synthesis and Photocatalysis for Methyl Orange

    Directory of Open Access Journals (Sweden)

    Yang Tian

    2011-01-01

    Full Text Available Fe3O4 nanoparticle was synthesized in the solution involving water and ethanol. Then, α-Fe2O3 shell was produced in situ on the surface of the Fe3O4 nanoparticle by surface oxidation in molten salts, forming α-Fe2O3/Fe3O4 core-shell nanostructure. It was showed that the magnetic properties transformed from ferromagnetism to superparamagnetism after the primary Fe3O4 nanoparticles were oxidized. Furthermore, the obtained α-Fe2O3/Fe3O4 core-shell nanoparticles were used to photocatalyse solution of methyl orange, and the results revealed that α-Fe2O3/Fe3O4 nanoparticles were more efficient than the self-prepared α-Fe2O3 nanoparticles. At the same time, the photocatalyzer was recyclable by applying an appropriate magnetic field.

  17. Synthesis and photocatalytic application of α-Fe2O3/ZnO fine particles prepared by two-step chemical method

    Directory of Open Access Journals (Sweden)

    Patij Shah

    2013-06-01

    Full Text Available Composite iron oxide-Zinc oxide (α-Fe2O3/ZnO was synthesized by two-step method: in the first one step uniform α-Fe2O3 particles were prepared through a hydrolysis process of ferric chloride at 80 °C. In the second step, the ZnO particles were included in the α-Fe2O3 particles by a zinc acetate [Zn(Ac2·2H2O] assisted hydrothermal method at low temperature (90°C±C. The α-Fe2O3 and ZnO phases were identified by XRD, energy dispersive X-ray analysis (EDX. The photoreactivities of α-Fe2O3/ZnO nanoparticles under UV irradiation were quantified by the degradation of formaldehyde.

  18. Morphology, structural and optical properties of iron oxide thin film photoanodes in photoelectrochemical cell: Effect of electrochemical oxidation

    Science.gov (United States)

    Maabong, Kelebogile; Machatine, Augusto G.; Hu, Yelin; Braun, Artur; Nambala, Fred J.; Diale, Mmantsae

    2016-01-01

    Hematite (α-Fe2O3) is a promising semiconductor as photoanode in solar hydrogen production from photoelectrolysis of water due to its appropriate band gap, low cost and high electrochemical stability in aqueous caustic electrolytes. Operation of such photoanode in a biased photoelectrochemical cell constitutes an anodization with consequent redox reactions at the electrode surface. α-Fe2O3 thin film photoanodes were prepared by simple and inexpensive dip coating method on fluorine doped tin oxide (FTO) glass substrate, annealed in air at 500 °C for 2 h, then electrochemically oxidized (anodized) in 1 M KOH at 500 mV for 1 min in dark and light conditions. Changes in structural properties and morphology of α-Fe2O3 nanoparticles films were investigated by XRD, Raman spectroscopy and a high resolution FE-SEM. The average grain size was observed to increase from 57 nm for pristine samples to 73 and 77 nm for anodized samples in dark and light respectively. Broadening and red shift in Raman spectra in anodized samples may be attributed to lattice expansion upon oxidation. The UV-visible measurements revealed enhanced absorption in the photoanodes after the treatment. The findings suggest that the anodization of the photoelectrode in a biased cell causes not only changes of the molecular structure at the surface, but also changes in the crystallographic structure which can be detected with x-ray diffractometry.

  19. Preparation of photocatalytic Fe 2O 3-TiO 2 coatings in one step by metal organic chemical vapor deposition

    Science.gov (United States)

    Zhang, Xingwang; Lei, Lecheng

    2008-02-01

    There are two major difficulties in the TiO 2 liquid-solid photocatalytic system: effective immobilization of the TiO 2 particles; and improving the catalytic activity under visible light. To simultaneously solve these two problems, Fe 2O 3-TiO 2 coatings supported on activated carbon fiber (ACF), have been prepared in one step by a convenient and efficient method—metal organic chemical vapor deposition (MOCVD). XRD results revealed that Fe 2O 3-TiO 2 coatings mainly composed of anatase TiO 2, α-Fe 2O 3 phases and little Fe 2Ti 3O 9. The pore structure of ACF was preserved well after loading with Fe 2O 3-TiO 2 coatings. UV-vis diffuse reflectance spectra showed a slight shift to longer wavelengths and an enhancement of the absorption in the visible region for Fe 2O 3-TiO 2 coatings, compared to the pure TiO 2 sample. A moderate Fe 2O 3-TiO 2 loading (13.7 wt%) was beneficial to mineralizing wastewater because the intermediates could be adsorbed onto the surface of photocatalyst following decomposition. The stable performance revealed that the Fe 2O 3-TiO 2 coatings were strongly adhered to the ACF surface, and the as prepared catalysts could be reused showing potential application for wastewater treatment.

  20. Super-high photocatalytic activity of Fe2O3 nanoparticles anchored on Bi2O2CO3 nanosheets with exposed {0 0 1} active facets

    Science.gov (United States)

    Hu, Dandan; Zhang, Kaiyou; Yang, Qi; Wang, Mingjun; Xi, Yi; Hu, Chenguo

    2014-10-01

    Structure engineering enables us to design novel photocatalysts with high efficiency and stability. Here visible light absorbing Fe2O3 semiconductor is chosen as sensitizer to modify wide band-gap Bi2O2CO3 semiconductor in order to enhance its photocatalytic properties by shifting the UV-driven catalytic activity to visible-light-driven catalytic activity. The Bi2O2CO3@Fe2O3 nanosheets with exposed active {0 0 1} facet were fabricated by a facile one-step modified hydrothermal method. The thermal stability, crystal structure, morphology and optical band gap were characterized. The photocatalytic activities of the Bi2O2CO3 and Bi2O2CO3@Fe2O3 with different molar ratio of Fe2O3 to Bi2O2CO3 were compared. It was found that the Bi2O2CO3@Fe2O3 catalyst can degrade rhodamine-B within 25 min under the simulated sunlight, displaying greatly enhanced photocatalytic activity with respect to the Bi2O2CO3 catalyst. The photocatalyst showed good photostability and recyclability. A mixture of multi-colored dyes including rhodamine-B, methylene blue and methyl orange can be completely degraded by the Bi2O2CO3@Fe2O3 catalyst (5 mol% Fe2O3) within 45 min under the simulated sunlight irradiation. The photocatalytic mechanism was discussed in detail.

  1. Reduction of CO2 to low carbon alcohols on CuO FCs/Fe2O3 NTs catalyst with photoelectric dual catalytic interfaces.

    Science.gov (United States)

    Li, Peiqiang; Wang, Huying; Xu, Jinfeng; Jing, Hua; Zhang, Jun; Han, Haixiang; Lu, Fusui

    2013-12-01

    In this paper, the CuO FCs/Fe2O3 NTs catalyst was obtained after Fe2O3 nanotubes (Fe2O3 NTs) were decorated with CuO flower clusters (CuO FCs) by the pulse electrochemical deposition method. The in situ vertically aligned Fe2O3 NTs were prepared on the ferrous substrate by a potentiostatic anodization method. The SEM result showed the volcano-like Fe2O3 NTs were arranged in order and the CuO FCs constituted of flaky CuO distributed on the Fe2O3 NTs surface uniformly. After CuO FCs were loaded on Fe2O3 NTs, the absorption of visible light was enhanced noticeably, and its band gap narrowed to 1.78 eV from 2.03 eV. The conduction band and valence band locating at -0.73 eV and 1.05 eV, respectively were further obtained. In the PEC reduction of CO2 process, methanol and ethanol were two major products identified by chromatography. Their contents reached 1.00 mmol L(-1) cm(-2) and 107.38 μmol L(-1) cm(-2) after 6 h, respectively. This high-efficiency catalyst with photoelectric dual catalytic interfaces has a great guidance and reference significance for CO2 reduction to liquid carbon fuels.

  2. Evaluation of environmental safety concentrations of DMSA Coated Fe2O3-NPs using different assay systems in nematode Caenorhabditis elegans.

    Directory of Open Access Journals (Sweden)

    Qiuli Wu

    Full Text Available Dimercaptosuccinic acid (DMSA coating improves the uptake efficiency presumably by engendering the Fe(2O(3-NPs. In the present study, we investigated the possible environmental safety concentrations of Fe(2O(3-NPs using different assay systems in nematode Caenorhabditis elegans with lethality, development, reproduction, locomotion behavior, pharyngeal pumping, defecation, intestinal autofluorescence and reactive oxygen species (ROS production as the endpoints. After exposure from L4-larvae for 24-hr, DMSA coated Fe(2O(3-NPs at concentrations more than 50 mg/L exhibited adverse effects on nematodes. After exposure from L1-larvae to adult, DMSA coated Fe(2O(3-NPs at concentrations more than 500 μg/L had adverse effects on nematodes. After exposure from L1-larvae to day-8 adult, DMSA coated Fe(2O(3-NPs at concentrations more than 100 μg/L resulted in the adverse effects on nematodes. Accompanied with the alterations of locomotion behaviors, ROS production was pronouncedly induced by exposure to DMSA coated Fe(2O(3-NPs in the examined three assay systems, and the close associations of ROS production with lethality, growth, reproduction, locomotion behavior, pharyngeal pumping, defecation, or intestinal autofluorescence in nematodes exposed to DMSA coated Fe(2O(3-NPs were confirmed by the linear regression analysis. Moreover, mutations of sod-2 and sod-3 genes, encoding Mn-SODs, showed more susceptible properties than wild-type when they were used for assessing the DMSA coated Fe(2O(3-NPs-induced toxicity, and the safety concentrations for DMSA coated Fe(2O(3-NPs should be defined as concentrations lower than 10 μg/L in sod-2 and sod-3 mutant nematodes.

  3. CdS Nanoparticle-Modified α-Fe2O3/TiO2 Nanorod Array Photoanode for Efficient Photoelectrochemical Water Oxidation

    Science.gov (United States)

    Yin, Ruiyang; Liu, Mingyang; Tang, Rui; Yin, Longwei

    2017-09-01

    In this work, we demonstrate a facile successive ionic layer adsorption and reaction process accompanied by hydrothermal method to synthesize CdS nanoparticle-modified α-Fe2O3/TiO2 nanorod array for efficient photoelectrochemical (PEC) water oxidation. By integrating CdS/α-Fe2O3/TiO2 ternary system, light absorption ability of the photoanode can be effectively improved with an obviously broadened optical-response to visible light region, greatly facilitates the separation of photogenerated carriers, giving rise to the enhancement of PEC water oxidation performance. Importantly, for the designed abnormal type-II heterostructure between Fe2O3/TiO2, the conduction band position of Fe2O3 is higher than that of TiO2, the photogenerated electrons from Fe2O3 will rapidly recombine with the photogenerated holes from TiO2, thus leads to an efficient separation of photogenerated electrons from Fe2O3/holes from TiO2 at the Fe2O3/TiO2 interface, greatly improving the separation efficiency of photogenerated holes within Fe2O3 and enhances the photogenerated electron injection efficiency in TiO2. Working as the photoanodes of PEC water oxidation, CdS/α-Fe2O3/TiO2 heterostucture electrode exhibits improved photocurrent density of 0.62 mA cm- 2 at 1.23 V vs. reversible hydrogen electrode (RHE) in alkaline electrolyte, with an obviously negatively shifted onset potential of 80 mV. This work provides promising methods to enhance the PEC water oxidation performance of the TiO2-based heterostructure photoanodes.

  4. Photocatalytic degradation of industrial pulp and paper mill effluent using synthesized magnetic Fe2O3-TiO2: Treatment efficiency and characterizations of reused photocatalyst.

    Science.gov (United States)

    Subramonian, Wennie; Wu, Ta Yeong; Chai, Siang-Piao

    2017-02-01

    In this work, heterogeneous photocatalysis was used to treat pulp and paper mill effluent (PPME). Magnetically retrievable Fe2O3-TiO2 was fabricated by employing a solvent-free mechanochemical process under ambient conditions. Findings elucidated the successful incorporation of Fe2O3 into the TiO2 lattice. Fe2O3-TiO2 was found to be an irregular and slightly agglomerated surface morphology. In comparison to commercial P25, Fe2O3-TiO2 exhibited higher ferromagnetism and better catalyst properties with improvements in surface area (58.40 m(2)/g), pore volume (0.29 cm(3)/g), pore size (18.52 nm), and band gap (2.95 eV). Besides, reusability study revealed that Fe2O3-TiO2 was chemically stable and could be reused successively (five cycles) without significant changes in its photoactivity and intrinsic properties. Additionally, this study demonstrated the potential recovery of Fe2O3-TiO2 from an aqueous suspension by using an applied magnetic field or sedimentation. Interactive effects of photocatalytic conditions (initial effluent pH, Fe2O3-TiO2 dosage, and air flow-rate), reaction mechanism, and the presence of chemical oxidants (H2O2, BrO3(-), and HOCl) during the treatment process of PPME were also investigated. Under optimal conditions (initial effluent pH = 3.88, [Fe2O3-TiO2] = 1.3 g/L, and air flow-rate = 2.28 L/min), the treatment efficiency of Fe2O3-TiO2 was 98.5% higher than the P25. Based on Langmuir-Hinshelwood kinetic model, apparent rate constants of Fe2O3-TiO2 and P25 were 9.2 × 10(-3) and 2.7 × 10(-3) min(-1), respectively. The present study revealed not only the potential of using magnetic Fe2O3-TiO2 in PPME treatment but also demonstrated high reusability and easy separation of Fe2O3-TiO2 from the wastewater.

  5. Core-Shell Nanostructure of α-Fe2O3/Fe3O4: Synthesis and Photocatalysis for Methyl Orange

    OpenAIRE

    Yang Tian; Di Wu; Xiao Jia; Binbin Yu; Sihui Zhan

    2011-01-01

    Fe3O4 nanoparticle was synthesized in the solution involving water and ethanol. Then, α-Fe2O3 shell was produced in situ on the surface of the Fe3O4 nanoparticle by surface oxidation in molten salts, forming α-Fe2O3/Fe3O4 core-shell nanostructure. It was showed that the magnetic properties transformed from ferromagnetism to superparamagnetism after the primary Fe3O4 nanoparticles were oxidized. Furthermore, the obtained α-Fe2O3/Fe3O4 core-shell nanoparticles were used to photocatalyse solutio...

  6. Thin Films

    Directory of Open Access Journals (Sweden)

    M. Benmouss

    2003-01-01

    the optical absorption are consistent with the film color changes. Finally, the optical and electrochromic properties of the films prepared by this method are compared with those of our sputtered films already studied and with other works.

  7. Preparation and magnetic properties of Co-P thin films

    Institute of Scientific and Technical Information of China (English)

    Haicheng Wang; Zhongmei Du; Lijin Wang; Guanghua Yu; Fengwu Zhu

    2008-01-01

    Magnetic Co-P thin films were prepared by eleetroless deposition. The experiment results show that the film thickness has a significant influence on the coercivity. While the film thickness varied from 300 nm to 5 μm, the coercivity dropped sharply from 45.36 to 22.28 kA/m. As the film thickness increased further, the coercivity varied slowly. When the thickness of the film was 300 nm, the deposited film could realize the coercivity as high as 45.36 kA/m, and the remanent magnetization as high as 800 kA/m .The Co-P films were deposited on the surface of magnetic drums of encoders, whose diameter was 40 mm, and then 512 magnetic poles were recorded, meaning that the magnetizing pitch was 0.245 mm. The testing results indicate that the output signals are perfect, the output waveforms are steady and the pulses account is integral. Compared with the γ-Fe2O3 coating, the Co-P thin film is suitable to be the magnetic recording media for the high resolution magnetic rotary encoder.

  8. Synthesis of magnetic γ-Fe2O3-based nanomaterial for ultrasonic assisted dyes adsorption: Modeling and optimization.

    Science.gov (United States)

    Asfaram, Arash; Ghaedi, Mehrorang; Hajati, Shaaker; Goudarzi, Alireza

    2016-09-01

    γ-Fe2O3 nanoparticles were synthesized and loaded on activated carbon. The prepared nanomaterial was characterized by field emission scanning electron microscopy (FE-SEM), energy-dispersive X-ray spectroscopy (EDX), Fourier transforms infrared spectroscopy (FT-IR) and X-ray diffraction (XRD). The γ-Fe2O3 nanoparticle-loaded activated carbon (γ-Fe2O3-NPs-AC) was used as novel adsorbent for the ultrasonic-assisted removal of methylene blue (MB) and malachite green (MG). Response surface methodology and artificial neural network were applied to model and optimize the adsorption of the MB and MG in their individual and binary solutions followed by the investigation on adsorption isotherm and kinetics. The individual effects of parameters such as pH, mass of adsorbent, ultrasonication time as well as MB and MG concentrations in addition to the effects of their possible interactions on the adsorption process were investigated. The numerical optimization revealed that the optimum adsorption (>99.5% for each dye) is obtained at 0.02g, 15mgL(-1), 4min and 7.0 corresponding to the adsorbent mass, each dye concentration, sonication time and pH, respectively. The Freundlich, Langmuir, Temkin and Dubinin-Radushkevich isotherms were studied. The Langmuir was found to be most applicable isotherm which predicted maximum monolayer adsorption capacities of 195.55 and 207.04mgg(-1) for the adsorption of MB and MG, respectively. The pseudo-second order model was found to be applicable for the adsorption kinetics. Blank experiments (without any adsorbent) were run to investigate the possible degradation of the dyes studied in presence of ultrasonication. No dyes degradation was observed.

  9. Application of Fe2O3/Al2O3 Composite Particles as Oxygen Carrier of Chemical Looping Combustion

    Institute of Scientific and Technical Information of China (English)

    Fang He; Hua Wang; Yongnian Dai

    2007-01-01

    Chemical looping combustion (CLC) of carbonaceous compounds has been proposed, in the past decade, as an efficient method for CO2 capture without cost of extra energy penalties. The technique involves the use of a metal oxide as an oxygen carrier that transfers oxygen from combustion air to fuels.The combustion is carried out in a two-step process: in the fuel reactor, the fuel is oxidized by a metal oxide, and in the air reactor, the reduced metal is oxidized back to the original phase. The use of iron oxide as an oxygen carrier has been investigated in this article. Particles composed of 80 wt% Fe2O3,together with Al2O3 as binder, have been prepared by impregnation methods. X-ray diffraction (XRD) analysis reveals that Fe2O3 does not interact with the Al2O3 binder after multi-cycles. The reactivity of the oxygen carrier particles has been studied in twenty-cycle reduction-oxidation tests in a thermal gravimetrical analysis (TGA) reactor. The components in the outlet gas have been analyzed. It has been observed that about 85% of CH4 converted to CO2 and H2O during most of the reduction periods. The oxygen carrier has kept quite a high reactivity in the twenty-cycle reactions. In the first twenty reaction cycles, the reaction rates became slightly higher with the number of cyclic reactions increasing, which was confirmed by the scanning electron microscopy (SEM) test results. The SEM analysis revealed that the pore size inside the particle had been enlarged by the thermal stress during the reaction, which was favorable for diffusion of the gaseous reactants into the particles. The experimental results suggested that the Fe2O3/Al2O3 oxygen carrier was a promising candidate for a CLC system.

  10. Particle orientation distribution in Y-Fe2O3magnetic tapes by Mössbauer and hysteresis loop measurements

    OpenAIRE

    Martínez Benjamin, Joan Josep; Labarta, Amílcar; Obradors, Xavier; Tejada Palacios, Javier

    1987-01-01

    The particle orientation in several Y-Fe2O3magnetic tapes has been quantitatively evaluated by using the data of both Mössbauer and hysteresis loop measurements performed in the three orthogonal directions. A texture function has been obtained as a development of real harmonics. The profile of the texture function gives the quality of the different magnetic tapes. A different degree of particle orientation at the surface of the tape is evidenced by means of conversion electron Mössbauer spect...

  11. Nanocrystalline Fe-Fe2O3 particle-deposited N-doped graphene as an activity-modulated Pt-free electrocatalyst for oxygen reduction reaction

    Science.gov (United States)

    Dhavale, Vishal M.; Singh, Santosh K.; Nadeema, Ayasha; Gaikwad, Sachin S.; Kurungot, Sreekumar

    2015-11-01

    The size-controlled growth of nanocrystalline Fe-Fe2O3 particles (2-3 nm) and their concomitant dispersion on N-doped graphene (Fe-Fe2O3/NGr) could be attained when the mutually assisted redox reaction between NGr and Fe3+ ions could be controlled within the aqueous droplets of a water-in-oil emulsion. The synergistic interaction existing between Fe-Fe2O3 and NGr helped the system to narrow down the overpotential for the oxygen reduction reaction (ORR) by bringing a significant positive shift to the reduction onset potential, which is just 15 mV higher than its Pt-counterpart. In addition, the half-wave potential (E1/2) of Fe-Fe2O3/NGr is found to be improved by a considerable amount of 135 mV in comparison to the system formed by dispersing Fe-Fe2O3 nanoparticles on reduced graphene oxide (Fe-Fe2O3/RGO), which indicates the presence of a higher number of active sites in Fe-Fe2O3/NGr. Despite this, the ORR kinetics of Fe-Fe2O3/NGr are found to be shifted significantly to the preferred 4-electron-transfer pathway compared to NGr and Fe-Fe2O3/RGO. Consequently, the H2O2% was found to be reduced by 78.3% for Fe-Fe2O3/NGr (13.0%) in comparison to Fe-Fe2O3/RGO (51.2%) and NGr (41.0%) at -0.30 V (vs. Hg/HgO). This difference in the yield of H2O2 formed between the systems along with the improvements observed in terms of the oxygen reduction onset and E1/2 in the case of Fe-Fe2O3/NGr reveals the activity modulation achieved for the latter is due to the coexistence of factors such as the presence of the mixed valancies of iron nanoparticles, small size and homogeneous distribution of Fe-Fe2O3 nanoparticles and the electronic modifications induced by the doped nitrogen in NGr. A controlled interplay of these factors looks like worked favorably in the case of Fe-Fe2O3/NGr. As a realistic system level validation, Fe-Fe2O3/NGr was employed as the cathode electrode of a single cell in a solid alkaline electrolyte membrane fuel cell (AEMFC). The system could display an open

  12. Interparticle interactions in composites of nanoparticles of ferrimagnetic (gamma-Fe2O3) and antiferromagnetic (CoO,NiO) materials

    DEFF Research Database (Denmark)

    Frandsen, Cathrine; Ostenfeld, Christopher Worsøe; Xu, M.;

    2004-01-01

    The magnetic properties of mixtures of ferrimagnetic gamma-Fe2O3 (maghemite) and antiferromagnetic NiO or CoO nanoparticles have been studied by use of Fe-57 Mossbauer spectroscopy, neutron powder diffraction and magnetization measurements. The studies showed that the interaction with antiferroma......The magnetic properties of mixtures of ferrimagnetic gamma-Fe2O3 (maghemite) and antiferromagnetic NiO or CoO nanoparticles have been studied by use of Fe-57 Mossbauer spectroscopy, neutron powder diffraction and magnetization measurements. The studies showed that the interaction...... with antiferromagnetic particles has a significant influence on the magnetic properties of the gamma-Fe2O3 nanoparticles. It was found that mixing the gamma-Fe2O3 nanoparticles with NiO nanoparticles resulted in a faster superparamagnetic relaxation and a reduced coercivity compared to a sample consisting solely...

  13. Fe2O3/TiO2 nanocomposite photocatalyst prepared by supercritical fluid combination technique and its application in degradation of acrylic acid

    Science.gov (United States)

    Wei, J.; Zhang, J. C.

    2017-01-01

    Fe2O3/TiO2 nanocomposite photocatalysts were synthesized by supercritical fluid combination technique, consisting of sol-gel method and supercritical fluid drying. The photocatalytic activity of the samples was evaluated by the degradation of acrylic acid. The results indicated that the Fe2O3/TiO2 nanocomposite catalysts prepared by this novel technique showed significant improvement in catalytic activity compared with pure TiO2 or Fe2O3/TiO2 catalysts prepared by traditional drying. Both infrared and ultraviolet spectrum of Fe2O3/TiO2 nanocomposite photocatalysts shift a little to lower wavelength indicating that the absorption threshold of Fe doped nanocomposite photocatalysts shift into the visible light region. This phenomenon was also attested by the photocatalytic degradation test under visible light.

  14. Direct Reduction of Solid Fe_2O_3 in Molten CaCl_2 by Potentially Green Process

    Institute of Scientific and Technical Information of China (English)

    Guoming Li; Dihua Wang; Zhen Chen

    2009-01-01

    Sintered (300℃) porous pellets of Fe_2O_3 were electrolyzed to Fe in molten CaCI2 (800-900℃) under argon at 1.8-3.2 V for 2-20 h. The laboratory scale experiments show that it was a potentially direct green method to produce Fe powder. At lower electrolysis voltage (90%) and smaller energy consumption (~3.0 kWh/kg) can be obtained. When the electrolysis voltage was above 2.4 V, the deposition of metal Ca from the salt lowered the current efficiency and increased the energy consumption. The electrolysis voltage also had effects on the micrographs of the reduced powder. The cubic particles can be seen in the products at the voltage lower than 2.2 V; when the voltage was higher than 2.2 V, it was nodular. The reduction proceeds at the cathode in two steps, i.e., from Fe_2O_3 to FeO and then to Fe. The oxygen emits at the anode. The process is potentially free of carbon emission and produces two useful products at both cathode and anode, promising a zero-emission technology for the extractive metallurgical industry.

  15. Structural and Physical Properties of Fe2O3-B2O3-V2O5 Glasses

    Directory of Open Access Journals (Sweden)

    Virender Kundu

    2008-01-01

    Full Text Available The structural and physical properties of xFe2O3-(40-x B2O3-60V2O5  (0≤x≤20 glass system have been investigated. The samples were prepared by normal melt-quench technique. The structural changes were inferred by means of FTIR by monitoring the infrared (IR spectra in the spectral range 600–4000 cm-1. The absence of boroxol ring (806 cm-1 in the present glass system suggested that these glasses consist of randomly connected BO3 and BO4 units. The conversion of BO3 to BO4 and VO5 to VO4 tetrahedra along with the formation of non-bridging oxygen's (NBOs attached to boron and vanadium takes place in the glasses under investigation. The density and molar volume of the present glass system were found to depend on Fe2O3 content. DC conductivity of the glass system has been determined in the temperature range 310–500 K. It was found that the general behavior of electrical conductivity was similar for all glass compositions and found to increase with increasing iron content. The parameters such as activation energy, average separation between transition metal ions (TMIs, polaron radius, and so forth have been calculated in adiabatic region and are found consistent with Mott's model of phonon-assisted polaronic hopping.

  16. Potentiometric and electrokinetic signatures of iron(II) interactions with (a,y)-Fe2O3

    Energy Technology Data Exchange (ETDEWEB)

    Toczydlowska, Diana; Kedra-Krolik, Karolina; Nejbert, Krzysztof; Preocanin, Tajana; Rosso, Kevin M.; Zarzycki, Piotr P.

    2015-05-29

    The role of surface electrostatics on the reductive dissolution of iron (III) oxides is poorly understood, despite its importance in controlling the amount of mobilized iron. We report the potentiometric titration of the a; y -Fe2O3 oxides exposed to reductants and complexing ligands (Fe(II), ascorbate, oxalate, malonate). We monitored in situ surface and potentials, the ratio of mobilized ferric to ferrous ions, and periodically analyzed nanoparticle crystal structure using X-ray diffraction. We found that addition of Fe2+ ions produces a response consistent with the iron solubilityactivity curve, whereas the presence of ascorbate significantly decreases the amount of mobilized Fe(III) due to reduction to Fe(II). In addition, XRD analysis proved that y-Fe2O3 particles remain structurally unchanged along the titration pathway despite iron cycling between aqueous and solid reservoirs. Our studies, suggest that the surface redoxactivity of iron oxides is primarily governed by the balance between Fe(III) and Fe(II) ions in aqueous phase, which may be easily altered by complexing and reducing agents.

  17. Dissolution Kinetics of SiO2 into CaO-Fe2O3-SiO2 Slag

    Science.gov (United States)

    Yu, Bin; Lv, Xuewei; Xiang, Shenglin; Xu, Jian

    2016-06-01

    High-basicity sinter is the predominant Fe-bearing material used in blast furnace process in East Asia. The dissolution of SiO2 into molten calcium ferrite influences the assimilation process. In this study, a rotating cylinder method was used to explore the dissolution kinetics of SiO2 into CaO-Fe2O3-SiO2 slag. The influencing factors, including temperature, rotating time and speed, and initial composition of the slag, were considered. Results showed that the dissolution rate increased with increasing rotation speed and temperature, whereas the increase in ω(SiO2) or ω(Fe2O3)/ ω(CaO) ratio in the initial slag composition decreased the dissolution rate. The diffusion coefficient and activation energy of SiO2 during the dissolution process ranged from 2.09 × 10-6 to 6.40 × 10-6 cm2 s-1 and 106.62 to 248.20 kJ mol-1, respectively. Concentration difference between the boundary layer and bulk phase was the primary driving force of the dissolution process; however, this process was also influenced by the slag viscosity and ion diffusivity.

  18. Hybrid α-Fe2O3@Ni(OH)2 nanosheet composite for high-rate-performance supercapacitor electrode.

    Science.gov (United States)

    Jiang, Hong; Ma, Haifeng; Jin, Ying; Wang, Lanfang; Gao, Feng; Lu, Qingyi

    2016-08-24

    In this study, we report a facile fabrication of ultrathin two-dimensional (2D) nanosheet hybrid composite, α-Fe2O3 nanosheet@Ni(OH)2 nanosheet, by a two-step hydrothermal method to achieve high specific capacitance and good stability performance at high charging/discharging rates when serving as electrode material of supercapacitors. The α-Fe2O3@Ni(OH)2 hybrid electrode not only has a smooth decrease of the specific capacitance with increasing current density, compared with the sharp decline of single component of Ni(OH)2 electrode, but also presents excellent rate capability with a specific capacitance of 356 F/g at a current density of 16 A/g and excellent cycling stability (a capacity retention of 93.3% after 500 cycles), which are superior to the performances of Ni(OH)2 with a lower specific capacitance of 132 F/g and a lower capacity retention of 81.8% at 16 A/g. The results indicate such hybrid structure would be promising as excellent electrode material for good performances at high current densities in the future.

  19. Temperature-dependent electrochemical capacitive performance of the α-Fe2O3 hollow nanoshuttles as supercapacitor electrodes.

    Science.gov (United States)

    Zheng, Xin; Yan, Xiaoqin; Sun, Yihui; Yu, Yinsheng; Zhang, Guangjie; Shen, Yanwei; Liang, Qijie; Liao, Qingliang; Zhang, Yue

    2016-03-15

    The design and optimization of supercapacitors electrodes nanostructures are critically important since the properties of supercapacitors can be dramatically enhanced by tunable ion transport channels. Herein, we demonstrate high-performance supercapacitor electrodes materials based on α-Fe2O3 by rationally designing the electrode microstructure. The large solid-liquid reaction interfaces induced by hollow nanoshuttle-like structures not only provide more active sites for faradic reactions but also facilitate the diffusion of the electrolyte into electrodes. These result in the optimized electrodes with high capacitance of 249 F g(-1) at a discharging current density of 0.5 A g(-1) as well as good cycle stability. In addition, the relationship between charge storage and the operating temperature has been researched. The specific capacitance has no significant change when the working temperature increased from 20 °C to 60 °C (e.g. 203 F g(-1) and 234 F g(-1) at 20 °C and 60 °C, respectively), manifesting the electrodes can work stably in a wide temperature range. These findings here elucidate the α-Fe2O3 hollow nanoshuttles can be applied as a promising supercapacitor electrode material for the efficient energy storage at various potential temperatures.

  20. A Wireless Electronic Nose System Using a Fe2O3 Gas Sensing Array and Least Squares Support Vector Regression

    Directory of Open Access Journals (Sweden)

    Yingguo Cheng

    2011-01-01

    Full Text Available This paper describes the design and implementation of a wireless electronic nose (WEN system which can online detect the combustible gases methane and hydrogen (CH4/H2 and estimate their concentrations, either singly or in mixtures. The system is composed of two wireless sensor nodes—a slave node and a master node. The former comprises a Fe2O3 gas sensing array for the combustible gas detection, a digital signal processor (DSP system for real-time sampling and processing the sensor array data and a wireless transceiver unit (WTU by which the detection results can be transmitted to the master node connected with a computer. A type of Fe2O3 gas sensor insensitive to humidity is developed for resistance to environmental influences. A threshold-based least square support vector regression (LS-SVR estimator is implemented on a DSP for classification and concentration measurements. Experimental results confirm that LS-SVR produces higher accuracy compared with artificial neural networks (ANNs and a faster convergence rate than the standard support vector regression (SVR. The designed WEN system effectively achieves gas mixture analysis in a real-time process.

  1. One-pot synthesis of novel pyrimido[4,5-]quinolines and pyrido[2,3-:6,5']dipyrimidines using encapsulated--Fe2O3 nanoparticles

    Indian Academy of Sciences (India)

    Moona Mohsenimehr; Manouchehr Mamaghani; Farhad Shirini; Mehdi Sheykhan; Sima Abbaspour; Leila Shafei Sabet

    2015-11-01

    Novel pyrimido[4,5-]quinolines and pyrido[2,3-:6,5-']dipyrimidine derivatives were synthe-sized in one-pot, three-component approach using sulfonic acid supported on hydroxyapatite-encapsulated--Fe2O3 [-Fe2O3 @HAp-SO3H] as magnetically recoverable nanocatalyst. The protocol provided a rapid, useful and green method for the preparation of the products in short reaction times and high yields.

  2. Ultrasmall Fe2O3 nanoparticles/MoS2 nanosheets composite as high-performance anode material for lithium ion batteries

    Science.gov (United States)

    Qu, Bin; Sun, Yue; Liu, Lianlian; Li, Chunyan; Yu, Changjian; Zhang, Xitian; Chen, Yujin

    2017-02-01

    Coupling ultrasmall Fe2O3 particles (~4.0 nm) with the MoS2 nanosheets is achieved by a facile method for high-performance anode material for Li-ion battery. MoS2 nanosheets in the composite can serve as scaffolds, efficiently buffering the large volume change of Fe2O3 during charge/discharge process, whereas the ultrasmall Fe2O3 nanoparticles mainly provide the specific capacity. Due to bigger surface area and larger pore volume as well as strong coupling between Fe2O3 particles and MoS2 nanosheets, the composite exhibits superior electrochemical properties to MoS2, Fe2O3 and the physical mixture Fe2O3+MoS2. Typically, after 140 cycles the reversible capacity of the composite does not decay, but increases from 829 mA h g‑1 to 864 mA h g‑1 at a high current density of 2 A g‑1. Thus, the present facile strategy could open a way for development of cost-efficient anode material with high-performance for large-scale energy conversion and storage systems.

  3. A fluorescent sensor based on methyldopa drug modified γ-Fe2O3 nanoparticles for ultrasensitive detection of calf thymus DNA

    Science.gov (United States)

    Shahabadi, Nahid; Maghsudi, Maryam; Kashanian, Soheila

    2016-03-01

    We reported the study of calf thymus DNA (ct-DNA) adsorption by the polymer of methyldopa (2-amino-3-(3,4-dihydroxyphenyl)-2-methyl acid, propanoic) (PMDP), magnetofluorescent PMDP-γ-Fe2O3 nanocrystal. The method is based on the extraordinarily high quenching efficiency of ct-DNA and the specific interaction between ct-DNA and PMDP-γ-Fe2O3 via guanine base and metal coordination, probably. It was found that the designed magnetic nanoparticles can adsorb ct-DNA in nM levels in the presence of NaCl and KCl. In acetate and phosphate buffers DNA were adsorbed completely. Also, we found that pH plays an important role in DNA adsorption onto PMDP-γ-Fe2O3 nanocrystal. PMDP-γ-Fe2O3 nanocrystal is highly hydrophilic and DNA desorption wasn't observed. We believe this study will further stimulate the application of PMDP-γ-Fe2O3 nanocrystal in bioanalytical chemistry and nanotechnology. PMDP-γ-Fe2O3 nanocrystal possesses the ability to interact with ct-DNA via a partial intercalative binding mechanism, as demonstrated by fluorescence displacement experiments and a significant red shift (ca, 10 nm) in UV-vis spectra.

  4. Preparation of Fe2O3-Clorprenaline/Tetraphenylborate Nanospheres and Their Application as Ion Selective Electrode for Determination of Clorprenaline in Pork

    Science.gov (United States)

    Shao, Xintian; Zhang, Jing; Li, Donghui; Yue, Jingli; Chen, Zhenhua

    2016-04-01

    A novel modified ion selective electrode based on Fe2O3-clorprenaline/tetraphenylborate nanospheres (Fe2O3-CLPT NSs) as electroactive materials for the determination of clorprenaline hydrochloride (CLP) is described. The α-Fe2O3 nanoparticles (NPs) were prepared by hydrothermal synthesis, then self-assembled on CLP/tetraphenylborate (TPB) to form Fe2O3-CLPT NSs, which were used as a potentiometric electrode for analyte determination innovatively. The Fe2O3-CLPT NSs modified electrode exhibited a wider concentration range from 1.0 × 10-7 to 1.0 × 10-1 mol/L and a lower detection limit of 3.7 × 10-8 mol/L compared with unmodified electrodes. The selectivity of the modified electrode was evaluated by fixed interference method. The good performance of the modified electrode such as wide pH range (2.4-6.7), fast response time (15 s), and adequate lifetime (14 weeks) indicate the utility of the modified electrode for evaluation of CLP content in various real samples. Finally, the modified electrode was successfully employed to detect CLP in pork samples with satisfactory results. These results demonstrated the Fe2O3-CLPT NSs modified electrode to be a functional and convenient method to the field of potentiometry determination of CLP in real samples.

  5. Fabrication of α-Fe2O3/TiO2 bi-functional composites with hierarchical and hollow structures and their application in water treatment

    Science.gov (United States)

    Li, Yinhui; Zhang, Na; Chen, Jianxin; Li, Ruijuan; Li, Liang; Li, Kunyu

    2016-02-01

    The α-Fe2O3/TiO2 bi-functional composites with hierarchical and hollow structures are fabricated through a hydrothermal route. The adsorption performance and photocatalytic activity of the composites towards Pb2+ are investigated in this work. Different adsorption kinetics models and equilibrium models are used to explore the adsorption behavior of hierarchical α-Fe2O3/TiO2 hollow spheres. Experimental data show that adsorption kinetics of the hierarchical α-Fe2O3/TiO2 hollow spheres can be fitted well by the pseudo-second-order model, while the isothermal data can be perfectly described by the Langmuir adsorption model. The maximum adsorption capacity of the hierarchical α-Fe2O3/TiO2 hollow spheres is 32.36 mg g-1. Moreover, the hierarchical α-Fe2O3/TiO2 hollow spheres possess photocatalytic oxidation character under simulated solar light irradiation. The results demonstrate that the hierarchical α-Fe2O3/TiO2 hollow spheres, as effective and cheap materials, can be applied to the removal of heavy metal ions from wastewater.

  6. Ultrasmall Fe2O3 nanoparticles/MoS2 nanosheets composite as high-performance anode material for lithium ion batteries

    Science.gov (United States)

    Qu, Bin; Sun, Yue; Liu, Lianlian; Li, Chunyan; Yu, Changjian; Zhang, Xitian; Chen, Yujin

    2017-01-01

    Coupling ultrasmall Fe2O3 particles (~4.0 nm) with the MoS2 nanosheets is achieved by a facile method for high-performance anode material for Li-ion battery. MoS2 nanosheets in the composite can serve as scaffolds, efficiently buffering the large volume change of Fe2O3 during charge/discharge process, whereas the ultrasmall Fe2O3 nanoparticles mainly provide the specific capacity. Due to bigger surface area and larger pore volume as well as strong coupling between Fe2O3 particles and MoS2 nanosheets, the composite exhibits superior electrochemical properties to MoS2, Fe2O3 and the physical mixture Fe2O3+MoS2. Typically, after 140 cycles the reversible capacity of the composite does not decay, but increases from 829 mA h g−1 to 864 mA h g−1 at a high current density of 2 A g−1. Thus, the present facile strategy could open a way for development of cost-efficient anode material with high-performance for large-scale energy conversion and storage systems. PMID:28218313

  7. Synthesis of mesoporous magnetic gamma-Fe2O3 and its application to Cr(VI) removal from contaminated water.

    Science.gov (United States)

    Wang, Peng; Lo, Irene M C

    2009-08-01

    In this study, mesoporous magnetic iron-oxide (gamma-Fe(2)O(3)) was synthesized as an adsorbent for Cr(VI) removal. For material synthesis, mesoporous silica (KIT-6) was used as a hard template and to drive iron precursor into KIT-6, a 'greener', affinity based impregnation method was employed, which involved using a nonpolar solvent (xylene) and led to recycling of the solvent. The results of Cr(VI) removal experiments showed that the synthesized mesoporous gamma-Fe(2)O(3) has a Cr(VI) adsorption capacity comparable with 10nm nonporous gamma-Fe(2)O(3) but simultaneously has a much faster separation than 10nm nonporous gamma-Fe(2)O(3) in the presence of an external magnetic field under the same experimental conditions. Cr(VI) adsorption capacity onto the mesoporous gamma-Fe(2)O(3) increased with decreasing solution pH and could be readily regenerated. Therefore, mesoporous gamma-Fe(2)O(3) presents a reusable adsorbent for a fast, convenient, and highly efficient removal of Cr(VI) from contaminated water.

  8. Design Of A Bi-Functional α-Fe2O3/Zn2SiO4:Mn2+ By Layer-By-Layer Assembly Method

    Directory of Open Access Journals (Sweden)

    Yu Ri

    2015-06-01

    Full Text Available This work describes the design of bi-functional α-Fe2O3/Zn2SiO4:Mn2+ using a two-step coating process. We propose a combination of pigments (α-Fe2O3 and phosphor (Zn2SiO4:Mn2+ glaze which is assembled using a layer-by-layer method. A silica-coated α-Fe2O3 pigment was obtained by a sol-gel method and a Zn2+ precursor was then added to the silica-coated α-Fe2O3 to create a ZnO layer. Finally, the Zn2SiO4:Mn2+ layer was prepared with the addition of Mn2+ ions to serve as a phosphor precursor in the multi-coated α-Fe2O3, followed by annealing at a temperature above 1000°C. Details of the phase structure, color and optical properties of the multi-functional α-Fe2O3/Zn2SiO4:Mn2+ were characterized by transmission electron microscopy and X-ray diffraction analyses.

  9. Vacancy ordered γ-Fe2O3 nanoparticles functionalized with nanohydroxyapatite: XRD, FTIR, TEM, XPS and Mössbauer studies

    Science.gov (United States)

    Ramos Guivar, Juan A.; Sanches, Edgar A.; Bruns, Florian; Sadrollahi, Elaheh; Morales, M. A.; López, Elvis O.; Litterst, F. Jochen

    2016-12-01

    Vacancy ordered maghemite (γ-Fe2O3) nanoparticles functionalized with nanohydroxyapatite (HAp - Ca10(PO4) 6(OH)2) have been successfully synthesized using an inexpensive co-precipitation chemical route. Evidence for the presence of vacancy order in maghemite was shown by the superstructure lines observed in X-ray diffraction. The adsorption of carboxyl groups of citric acid (C6H8O7) onto γ-Fe2O3 nanoparticles was investigated by FTIR, XPS and Mössbauer spectroscopy. From XPS surface analysis, two binding energies related to oxygen were attributed to bindings between C6H8O7/γ- Fe2O3 and C6H8O7/HAp from an interfacial reaction promoted by strongly adsorbed H2O molecules at the surface of these nanomaterials. Le Bail refinement of the XRD patterns showed the formation of well-crystallized pure tetragonal maghemite before and after functionalization with nanoHAp. The temperature dependence of hyperfine parameters of pure and functionalized γ-Fe2O3 nanoparticles was investigated via Mössbauer spectroscopy. TEM revealed the formation of quasi-spherical γ- Fe2O3 nanoparticles with an average diameter of ca. 12 nm and 16 nm before and after functionalization with nanoHAp in agreement with Le Bail refinement. Magnetometry measurements showed a saturation magnetization of 12 emu/g and a blocking temperature of 340 K for the functionalized γ- Fe2O3 nanoparticles.

  10. Enhanced coercivity in Co-doped α-Fe2O3 cubic nanocrystal assemblies prepared via a magnetic field-assisted hydrothermal synthesis

    Directory of Open Access Journals (Sweden)

    Kinjal Gandha

    2017-05-01

    Full Text Available Ferromagnetic Co-doped α-Fe2O3 cubic shaped nanocrystal assemblies (NAs with a high coercivity of 5.5 kOe have been synthesized via a magnetic field (2 kOe assisted hydrothermal process. The X-ray diffraction pattern and Raman spectra of α-Fe2O3 and Co-doped α-Fe2O3 NAs confirms the formation of single-phase α-Fe2O3 with a rhombohedral crystal structure. Electron microscopy analysis depict that the Co-doped α-Fe2O3 NAs synthesized under the influence of the magnetic field are consist of aggregated nanocrystals (∼30 nm and of average assembly size 2 μm. In contrast to the NAs synthesized with no magnetic field, the average NAs size and coercivity of the Co-doped α-Fe2O3 NAs prepared with magnetic field is increased by 1 μm and 1.4 kOe, respectively. The enhanced coercivity could be related to the well-known spin–orbit coupling strength of Co2+ cations and the redistribution of the cations. The size increment indicates that the small ferromagnetic nanocrystals assemble into cubic NAs with increased size in the magnetic field that also lead to the enhanced coercivity.

  11. Photo-Fenton degradation of rhodamine B using Fe2O3-Kaolin as heterogeneous catalyst: characterization, process optimization and mechanism.

    Science.gov (United States)

    Guo, Sheng; Zhang, Gaoke; Wang, Jiquan

    2014-11-01

    An efficient Fe2O3-Kaolin was synthesized as a heterogeneous catalyst for photo-Fenton degradation of organic contaminants. X-ray photoelectron spectroscopy analysis and high-resolution transmission electron microscope analysis confirmed the existence of Fe2O3 nanoparticles in the Fe2O3-Kaolin composite. The specific surface area of the Fe2O3-Kaolin catalyst increased from 19.47 to 39.32m(2)/g compared to kaolin. The catalytic activity of the Fe2O3-Kaolin catalyst was evaluated by the photo-Fenton degradation of rhodamine B (RhB) under visible light irradiation and the results showed that the catalyst was highly effective for the degradation of RhB in a wide pH range of 2.21-10.13. At optimal conditions, 98% discoloration and 66% mineralization of RhB were achieved in 120min. The catalyst was efficient for the degradation of methylene blue as well. Leaching test indicated that the leached iron from the catalyst was negligible and the catalyst still showed high photocatalytic activity after five reaction cycles, which all showed that the Fe2O3-Kaolin catalyst is a promising heterogeneous photocatalyst for the degradation of various dyes in wastewater. Finally, a possible photocatalytic mechanism was proposed based on photoluminescence measurements and a series of operating conditions.

  12. Porous sulfated metal oxide SO4 2-/Fe2O3 as an anode material for Li-ion batteries with enhanced electrochemical performance

    Science.gov (United States)

    Li, Zhen; Lv, Qianqian; Huang, Xiaoxiong; Tan, Yueyue; Tang, Bohejin

    2017-01-01

    Sulfated metal oxide SO4 2-/Fe2O3 was prepared by a novel facile sol-gel method combined with a subsequent heating treatment process. The as-synthesized products were analyzed by XRD, FTIR, and FE-SEM. Compared with the unsulfated Fe2O3, the agglomeration of particles has been alleviated after the incorporation of SO4 2-. Interestingly, the primary particle size of the SO4 2-/Fe2O3 (about 5 nm) is similar to its normal counterparts even after the calcination treatment. More importantly, SO4 2-/Fe2O3 exhibits a porous architecture, which is an intriguing feature for electrode materials. When used as anode materials in Li-ion batteries, SO4 2-/Fe2O3 delivered a higher reversible discharge capacity (992 mAh g-1), with smaller charge transfer resistance, excellent rate performance, and better cycling stability than normal Fe2O3. We believed that the presence of SO4 2- and porous architecture should be responsible for the enhanced electrochemical performance, which could provide more continuous and accessible conductive paths for Li+ and electrons.

  13. Dispersing of Fe2O3 Nano-Particles in Ammonia- Water Suspension%氨水-Fe2O3纳米流体稳定性影响因素分析

    Institute of Scientific and Technical Information of China (English)

    杨柳; 杜垲; 李彦军; 程波

    2011-01-01

    为了将纳米颗粒的强化传热传质作用应用于氨水吸收制冷中,提出了在氨水溶液中添加Fe203纳米颗粒和表面活性剂十二烷基苯磺酸纳(SDBS)的纳米流体的配制方法,并通过沉降试验和吸光度测试方法对其稳定性进行了实验研究。研究了活性剂质量分数、超声分散时间和氨水浓度对稳定性的影响,确定了Fe2O3-氨水纳米流体分散的最佳工艺为:SDBS质量分数为0.8%,超声时间为30min,基液为25%的氨水。最后根据双电层原理分析了活性剂质量分数对悬浮液的稳定性的影响。结果表明在悬浮液的稳定性条件下,活性剂存在最佳质量分数,此结论与实验结果一致。%In this paper, the dispersion stability of Fe2O3 nano-particles in ammonia water was investigated using the sedimentation and the light transmission ratio index methods with different concentration of surfactant, different durations of ultrasonic vibration and different concentrations of ammonia-water basefluid in order to apply nanofluid to the absorption system. Sodium dodecyl benzene sulfonate (SDBS) is used as the surfactants. The results show that the stability of nanofluid was exacerbated firstly, then was improved, and then was exacerbated again with the increase of concentrations of the ionic surfactants. The optimal dispersing condition was 0.8% of SDBS in 25% ammonia water base fluid with 30 minutes of ultrasonic vibration. Finally, based on electric double layer theory, the influence of concentration of surfactant on the stability of nanofluid was analyzed. The reaction of anionic surfactants to the Fe2O3 nano-particles and the existence of the optimal surfactant concentration were explained in accordance with the experimental results.

  14. Preparation of nano-sized Fe2O3-SiO2 composite particles and the O2/N2 separation performance of their PU blend membrane%Fe2O3-SiO2复合粒子的制备及其PU共混膜的氧氮分离性能

    Institute of Scientific and Technical Information of China (English)

    白云翔; 石丽; 张春芳; 顾瑾; 孙余凭

    2013-01-01

    Nano-sized Fe2O3-SiO2 composite particles were prepared by coprecipitation method and mixed method. Further PU blend membrane were prepared by blending composite particles with PU and their O2 and N2 permeation properties were investigated. Results showed that Fe2O3-SiO2 prepared by the co-precipitating method had smaller and more uniform particle size than Fe2O3/SiO2 prepared by blending Fe2O3 with SiO2. Due to the Si/Fe solid solution structure in Fe2O3-SiO2 particle, PU/Fe2O3-SiO2 membrane had better mechanical and oxygen and nitrogen separation properties compared to PU/Fe2O3/SiO2 membrane. Meanwhile, at 10% Fe2O3-SiO2content, the O2 permeability coefficients of PU/Fe2O3-SiO2blend membrane is 13.35 Barrer, the ideal selectivity of O2/N2 is 7.14.%采用共沉淀与复配2种方法制备了Fe2O3-SiO2复合纳米粒子,将其添加到聚氨酯(PU)膜中,研究了粒子复合方式对PU共混膜力学性能和O2、N2分离性能的影响.结果表明,通过共沉淀法制备的Fe2O3-SiO2粒子粒径小且均匀,内部存在硅铁固溶体结构,其PU共混膜的机械强度和氧氮分离性能优于复配法制备的Fe2O3/SiO2粒子;当Fe2O3-SiO2添加量为10%时,PU共混膜的O2渗透系数为13.35 Barrer,O2/N2理论分离因子为7.14.

  15. Magnetic properties of γ-Fe2O3 nanoparticles encapsulated in surface-treated polymer spheres

    Science.gov (United States)

    Coaquira, J. A. H.; Cardoso, C. A.; Soares, F. Q.; Garg, V. K.; Oliveira, A. C.; Rodriguez, A. F. R.; Rabelo, D.; Morais, P. C.

    2010-01-01

    Mössbauer and magnetic characterization of polymer-dispersed γ-Fe2O3 nanoparticles treated under different chemical processes are reported in this work. X-ray powder diffraction analysis provides a mean particle size of D ~ 8.0 nm. Whereas Mössbauer spectroscopy data suggest the presence of only Fe3 + ions, magnetization measurements indicate the occurrence of a freezing phenomenon in agreement with the thermal evolution of Mössbauer spectra. A core-shell model was used to determine a magnetically disordered layer (shell) of d ~ 1.0 nm covering a region of collinear magnetic moments (core). The chemical treatments with H2O2 and Na2S2O8 modify notoriously the magnetic response of the polymer-dispersed nanoparticles.

  16. Magnetic properties of γ-Fe2O3 nanoparticles obtained by vaporization condensation in a solar furnace

    Science.gov (United States)

    Martínez, B.; Roig, A.; Obradors, X.; Molins, E.; Rouanet, A.; Monty, C.

    1996-03-01

    The magnetic properties of γ-Fe2O3 nanoparticles synthesized by vaporization condensation in a solar image furnace have been studied using both magnetic measurements and Mössbauer spectroscopy. The mean size of the particles turns out to be easily controlled by changing the pressure conditions in the growth chamber. The particles exhibit superparamagnetic behavior at room temperature. Magnetic measurements show the appearance of magnetic hysteresis in the low-temperature range and from the evolution with temperature of the ferromagnetic ratio, MR/MS, we have determined the distribution of the blocking temperatures for the smallest particles that is fitted to a log-normal distribution leading to a mean blocking temperature =38±15 K. The size distribution of the magnetic unit is also determined from this fitting, as well as from the Mössbauer spectra, obtaining a mean particle volume of about 3.5×105 Å3.

  17. Estimation of fracture parameters for Al-SiC and Al-Fe2O3 metal matrix composites

    Science.gov (United States)

    Jacob, S.; Sridhar, R.; Irudaya Raja, S. Joseph

    2017-03-01

    In this paper silicon carbide and iron oxide is reinforced with aluminum matrix. The prepared composite provide high strength than the commercial composite. It provides high elastic properties and high service temperature. Since this material have great scope in space application it has been chosen for estimation of fracture toughness. Hence grain size of the samples increased this is due to the effect of reinforcement bonding with aluminum matrix. The CMOD test has been carried out for this Purpose. Microscopic examination has shown that with increase in of reinforcement test confirmed that with increase in reinforcement ratio the fracture toughness also increased. In this work specimens have been preferred with and without addition of SiC and Fe2O3 to compare the influence. The results are compared and it has been studied that Fracture Toughness increased significantly by addition of inclusions.

  18. Adsorption-controlled transition of the electrical properties realized in Hematite (alpha-Fe2O3)nanorods ethanol sensing

    Institute of Scientific and Technical Information of China (English)

    Wang Chong; Wang Fei-Fei; Fu Xing-Qiu; Zhang En-Di; Xu Zhi

    2011-01-01

    Alpha-Fe2O3 nanorods are synthesized through a hydrothermal method with no surfactant introduced and ethanol sensors are fabricated from these nanorods. The device can respond to ethanol vapour in a concentration range from 1to 1500 parts per million and shows both p-type and n-type responding characteristics during the investigation of the ethanol sensing. The sensor displays a p-type characteristic when the ethanol concentration is low and converted into an n-type characteristic as the concentration exceeds a certain value. Such a phenomenon is attributed to the chemisorbed oxygen, which leads to different modifications of the energy band at the surface, namely, depletion layer or inversion layer.

  19. A novel amperometric catechol biosensor based on α-Fe2O3 nanocrystals-modified carbon paste electrode.

    Science.gov (United States)

    Sarika, C; Shivakumar, M S; Shivakumara, C; Krishnamurthy, G; Narasimha Murthy, B; Lekshmi, I C

    2017-05-01

    In this work, we designed an amperometric catechol biosensor based on α-Fe2O3 nanocrystals (NCs) incorporated carbon-paste electrode. Laccase enzyme is then assembled onto the modified electrode surface to form a nanobiocomposite enhancing the electron transfer reactions at the enzyme's active metal centers for catechol oxidation. The biosensor gave good sensitivity with a linear detection response in the range of 8-800 μM with limit of detection 4.28 μM. We successfully employed the sensor for real water sample analysis. The results illustrate that the metal oxide NCs have enormous potential in the construction of biosensors for sensitive determination of phenol derivatives.

  20. The Preparation and Gas-sensing Property of Nanosize γ-Fe2O3/SiO2

    Institute of Scientific and Technical Information of China (English)

    马丽景; 闫涛; 白守礼; 黄小葳; 宋永吉; 陈霭璠; LIUChungChium

    2004-01-01

    Nanostructured γ-Fe2O3/SiO2 complex oxide was prepared by sol-gel method with tetraethoxysilane and iron nitrate as precursors. The particle size distribution, thermal and phase stabilities and gas sensing properties were systematically characterized by TEM, granularity distribution, TG-DTA, XRD and gas sensitivity measurements. The particle size is about 10 nm and size distribution is very narrow. The sensitivity of the sensing element to CO, H2, C2H4, C6H6 and the effects of calcination temperature on the sensitivity and conductance of gases were examined. The combination of excellent thermal stability and tunable gas sensing properties through careful control of the preparation and judicious selection of material compositions gives rise to novel nanocomposites, which is attractive for the sensitive and selective detection of reducing gases and some hydrocarbon gases.

  1. Density functional study on the heterogeneous oxidation of NO over α-Fe2O3 catalyst by H2O2: Effect of oxygen vacancy

    Science.gov (United States)

    Song, Zijian; Wang, Ben; Yu, Jie; Ma, Chuan; Zhou, Changsong; Chen, Tao; Yan, Qianqian; Wang, Ke; Sun, Lushi

    2017-08-01

    Catalytic oxidation with H2O2 is a promising method for NOx emission control in coal-fired power plants. Hematite-based catalysts are attracting increased attention because of their surface redox reactivity. To elucidate the NO oxidation mechanism on α-Fe2O3 surfaces, density functional theory (DFT) calculations were conducted by investigating the adsorption characteristics of nitric oxide (NO) and hydrogen peroxide (H2O2) on perfect and oxygen defect α-Fe2O3 (0 0 1) surfaces. Results show that NO was molecularly adsorbed on two kinds of surfaces. H2O2 adsorption on perfect surface was also in a molecular form; however, H2O2 dissociation occurred on oxygen defect α-Fe2O3 (0 0 1) surface. The adsorption intensities of the two gas molecules in perfect α-Fe2O3 (0 0 1) surface followed the order NO > H2O2, and the opposite was true for the oxygen defect α-Fe2O3 (0 0 1). Oxygen vacancy remarkably enhanced the adsorption intensities of NO and H2O2 and promoted H2O2 decomposition on catalyst surface. As an oxidative product of NO, HNO2 was synthesized when NO and H2O2 co-adsorbed on the oxygen defect α-Fe2O3 (0 0 1) surface. Analyses of Mulliken population, electron density difference, and partial density of states showed that H2O2 decomposition followed the Haber-Weiss mechanism. The trends of equilibrium constants suggested that NO adsorption on α-Fe2O3 (0 0 1) surface was more favorable at low than at high temperatures, whereas H2O2 adsorption was favorable between 375 and 450 K. These calculations results well agreed with the experimental ones and further elucidates the reaction mechanisms.

  2. Whole-Pattern Fitting and Positron Annihilation Studies of Magnetic PVA/α-Fe2O3 Nanocomposites

    Science.gov (United States)

    Prashanth, K. S.; Mahesh, S. S.; Prakash, M. B. Nanda; Ningaraju, S.; Ravikumar, H. B.; Somashekar, R.; Nagabhushana, B. M.

    2016-06-01

    A low-temperature solution combustion method was used to synthesize α-Fe2O3 nanoparticles. Magnetic polyvinyl alcohol (PVA)/α-Fe2O3/NaCl nanocomposites were prepared by solvent cast method. The Fourier transform infrared (FTIR) spectroscopy and scanning electron microscopy (SEM) results are in confirmation with X-ray diffraction (XRD) results indicating the formation of nanocomposites. The microcrystalline parameters, crystallite size ( ), lattice strain ( g in %), stacking faults ( α d ), and twin faults ( β) of prepared polymer nanocomposites were evaluated by whole-pattern fitting technique. The refinement was carried out using the computed microstructural parameters in which the twin faults and stacking faults did not vary much and statistical deviation was less than 5 %. Positron annihilation lifetime spectroscopy (PALS) was used for microstructural characterization. PALS results show that the ortho-positronium (o-Ps) lifetime (τ3) increases gradually as a function of nanoparticle concentration and about 219 ps increase observed from1.50 to1.71 ns at 3 wt%. This indicates the increase of free volume hole size ( V f ) from 54.47 to 72.18 Å3. The o-Ps intensities ( I 3) decrease indicating the inhibition of o-Ps formation upon incorporation of nanoparticles into PVA. The increase in I 2 values suggests the increased annihilation at the interface region. Positron lifetime parameters, viz., o-Ps lifetime, and its intensities indicate the effect of quenching and inhibition upon incorporation of metal oxide nanoparticles and inorganic salt into PVA.

  3. A Density Functional Theory Study of the Adsorption of Benzene on Hematite (α-Fe2O3 Surfaces

    Directory of Open Access Journals (Sweden)

    Nelson Y. Dzade

    2014-02-01

    Full Text Available The reactivity of mineral surfaces in the fundamental processes of adsorption, dissolution or growth, and electron transfer is directly tied to their atomic structure. However, unraveling the relationship between the atomic surface structure and other physical and chemical properties of complex metal oxides is challenging due to the mixed ionic and covalent bonding that can occur in these minerals. Nonetheless, with the rapid increase in computer processing speed and memory, computer simulations using different theoretical techniques can now probe the nature of matter at both the atomic and sub-atomic levels and are rapidly becoming an effective and quantitatively accurate method for successfully predicting structures, properties and processes occurring at mineral surfaces. In this study, we have used Density Functional Theory calculations to study the adsorption of benzene on hematite (α-Fe2O3 surfaces. The strong electron correlation effects of the Fe 3d-electrons in α-Fe2O3 were described by a Hubbard-type on-site Coulomb repulsion (the DFT+U approach, which was found to provide an accurate description of the electronic and magnetic properties of hematite. For the adsorption of benzene on the hematite surfaces, we show that the adsorption geometries parallel to the surface are energetically more stable than the vertical ones. The benzene molecule interacts with the hematite surfaces through π-bonding in the parallel adsorption geometries and through weak hydrogen bonds in the vertical geometries. Van der Waals interactions are found to play a significant role in stabilizing the absorbed benzene molecule. Analyses of the electronic structures reveal that upon benzene adsorption, the conduction band edge of the surface atoms is shifted towards the valence bands, thereby considerably reducing the band gap and the magnetic moments of the surface Fe atoms.

  4. Synergistic effect of Fe2O3/Ho2O3 Co-modified 2D-titanate heterojunctions on enhanced photocatalytic degradation

    Science.gov (United States)

    Zhao, Xiaona; Liu, Xinzhao; Lu, Dingze; Wu, Pei; Yan, Qiuyang; Liu, Min; Fang, Pengfei

    2017-01-01

    TiO2-based nanosheets (TNSs) co-modified by Fe2O3 and Ho2O3 were synthesized by one-pot hydrothermal method using Fe(NO3)3 and Ho(NO3)3 as precursors compositing with TiO2. The Fe2O3/Ho2O3-TNSs heterojunctions possessed a thickness of approximately 3-4 nm, large specific surface area of 210-310 cm2/g, with Fe2O3 and Ho2O3 nanoparticles highly dispersed over the surface of the nanosheets. The crystallization of the samples gradually increased with the amount of Fe2O3 nanoparticles, which was confirmed by the XRD, BET and Raman spectra, indicating that Ho2O3 and Fe2O3 influenced the crystallinity and structure evolution of the TNSs, besides, led to an improved the visible-light absorption. Surface photocurrent and fluorescence spectral studies revealed that the photo-generated charge carrier separation efficiency could be efficiently improved by an appropriate amount of modification. The Fe2O3/Ho2O3-TNSs exhibited synergistic effect on photocatalytic degradation of RhB as well as MO under visible light. The highest efficiency was obtained by 0.05%-Fe2O3/Ho2O3-TNSs (Fe:Ho:Ti = 0.05:1:100), which was 8.86 and 6.72 times than that of individual 1.0%-Ho2O3-TNSs (Ho:Ti = 1:100) and 0.05%-Fe2O3-TNSs (Fe:Ti = 0.05:100), respectively. The possible mechanism for enhanced visible-light-induced photocatalytic activity was proposed. Ho2O3 introduced in the photocatalysts may act as the hole capture while Fe2O3 may share the same Fermi levels with TNSs and serve as the electron capture center in the n-n-p system, which reduced the recombination rate of photo-induced electron-hole pairs.

  5. Preparation, characterization, and cytotoxicity of CPT/Fe2O3-embedded PLGA ultrafine composite fibers: a synergistic approach to develop promising anticancer material

    Directory of Open Access Journals (Sweden)

    Amna T

    2012-03-01

    Full Text Available Touseef Amna1, M Shamshi Hassan2, Ki-Taek Nam2, Yang You Bing3, Nasser AM Barakat2, Myung-Seob Khil2, Hak Yong Kim1,21Center for Healthcare Technology Development, 2Department of Organic Materials and Fiber Engineering, Chonbuk National University, Jeonju, Korea; 3Animal Science and Technology College, Henan University of Science and Technology, Luoyang, ChinaAbstract: The aim of this study was to fabricate camptothecin/iron(III oxide (CPT/Fe2O3-loaded poly(D,L-lactide-co-glycolide (PLGA composite mats to modulate the CPT release and to improve the structural integrity and antitumor activity of the released drug. The CPT/ Fe2O3-loaded PLGA ultrafine fibers were prepared for the first time by electrospinning a composite solution of CPT/Fe2O3 and neat PLGA (4 weight percent. The physicochemical characterization of the electrospun composite mat was carried out by scanning electron microscopy, energy dispersive X-ray spectroscopy, electron probe microanalysis, thermogravimetry, transmission electron microscopy, ultraviolet-visible spectroscopy, and X-ray diffraction pattern. The medicated composite fibers were evaluated for their cytotoxicity on C2C12 cells using Cell Counting Kit-8 assay (Sigma-Aldrich Corporation, St Louis, MO. The in vitro studies indicated a slow and prolonged release over a period of 96 hours with mild initial burst. Scanning electron microscopy, thermogravimetry, and X-ray diffraction studies confirmed the interaction of CPT/Fe2O3 with the PLGA matrix and showed that the crystallinity of CPT decreased after loading. Incorporation of CPT in the polymer media affected both the morphology and the size of the CPT/Fe2O3-loaded PLGA composite fibers. Electron probe microanalysis and energy dispersive X-ray spectroscopy results confirmed well-oriented composite ultrafine fibers with good incorporation of CPT/Fe2O3. The cytotoxicity results illustrate that the pristine PLGA did not exhibit noteworthy cytotoxicity; conversely, the CPT/Fe

  6. Understanding Structure-Function Relationship in Hybrid Co3O4-Fe2O3/C Lithium-Ion Battery Electrodes.

    Science.gov (United States)

    Sultana, Irin; Rahman, Md Mokhlesur; Ramireddy, Thrinathreddy; Sharma, Neeraj; Poddar, Debasis; Khalid, Abbas; Zhang, Hongzhou; Chen, Ying; Glushenkov, Alexey M

    2015-09-23

    A range of high-capacity Li-ion anode materials (conversion reactions with lithium) suffer from poor cycling stability and limited high-rate performance. These issues can be addressed through hybridization of multiple nanostructured components in an electrode. Using a Co3O4-Fe2O3/C system as an example, we demonstrate that the cycling stability and rate performance are improved in a hybrid electrode. The hybrid Co3O4-Fe2O3/C electrode exhibits long-term cycling stability (300 cycles) at a moderate current rate with a retained capacity of approximately 700 mAh g(-1). The reversible capacity of the Co3O4-Fe2O3/C electrode is still about 400 mAh g(-1) (above the theoretical capacity of graphite) at a high current rate of ca. 3 A g(-1), whereas Co3O4-Fe2O3, Fe2O3/C, and Co3O4/C electrodes (used as controls) are unable to operate as effectively under identical testing conditions. To understand the structure-function relationship in the hybrid electrode and the reasons for the enhanced cycling stability, we employed a combination of ex situ and in situ techniques. Our results indicate that the improvements in the hybrid electrode originate from the combination of sequential electrochemical activity of the transition metal oxides with an enhanced electronic conductivity provided by percolating carbon chains.

  7. One-dimensional Fe2O3/TiO2 photoelectrode and investigation of its photoelectric properties in photoelectrochemical cell

    Science.gov (United States)

    Song, Xi-Ming; Zhou, Xin; Yuan, Chunxue; Zhang, Yu; Tong, Qiang; Li, Ying; Cui, Luxia; Liu, Daliang; Zhang, Wei

    2017-03-01

    We reported a novel Fe2O3/rutile TiO2 nanorod (NR) arrays with the heterogeneous structure for photoelectrochemical (PEC) cells, which were fabricated on fluorine-doped tin oxide glass (FTO) substrates that serve as model architecture via a hydrothermal method. Fe2O3 was revealed as an inexpensive and eco-friendly semiconductor sensitizer to make TiO2 respond to visible light. By using this photoanode, the photoelectric conversion and water splitting properties of PEC cells based on the one-dimensional (1D) Fe2O3/TiO2 heterostructures were investigated in detail under simulated sunlight. Meanwhile, the optimization of photovoltaic performance was also achieved by regulating the amount of Fe2O3. The open circuit voltage and short circuit current of the Fe2O3/TiO2 solar cell can reach 0.435 V and 1.840 mA/cm2, respectively. In addition, theoretical analysis of the photoelectric effect is preliminarily explored on the basis of the flat band potential results.

  8. Facile fabrication of carbon microspheres decorated with B(OH) 3 and α-Fe 2 O 3 nanoparticles: superior microwave absorption

    KAUST Repository

    Zhong, Bo

    2017-06-02

    We demonstrate that novel three-dimensional (3D) B(OH)3 and α-Fe2O3 nanoparticles decorated carbon microspheres (B(OH)3/α-Fe2O3-CMSs) can be fabricated via a facile thermal treatment process. The carbon microspheres with diameter of 1 to 3 μm and decorated B(OH)3 and α-Fe2O3 nanoparticles with diameters of several to tens of nanometers are successfully fabricated. These novel 3D B(OH)3/α-Fe2O3-CMS composites exhibit enhanced microwave absorption with tunable strong absorption wavebands in the frequency range of 2–18 GHz. They have a minimum reflection loss (RL) value of -52.69 dB at a thickness of 3.0 mm, and the effective absorption bandwidth for RL less than -10 dB is as large as 5.64 GHz. The enhanced microwave absorption performance arises from the synergy of the impedance matching caused by the B(OH)3 nanoparticles, dielectric loss as well as the enhancement of multiple reflection among 3D α-Fe2O3 nanocrystals. These results provide a new strategy to tune electromagnetic properties and enhance the capacity of high-efficient microwave absorbers.

  9. Investigation of Thermoelectric Properties with Dispersion of Fe2O3 and Fe-85Ni Nanospheres in Bi0.5Sb1.5Te3 Matrix

    Science.gov (United States)

    Yoon, Sang Min; Dharmaiah, Peyala; Kim, Hyo-Seob; Lee, Chul Hee; Hong, Soon-Jik; Koo, Jar Myung

    2016-09-01

    In this work, we fabricated Bi0.5Sb1.5Te3 thermoelectric alloys using the mass-production technique, and subsequently Fe2O3 and Fe-85Ni alloy nanoparticles were dispersed in the matrix by high energy ball milling and consolidated using spark plasma sintering technique. The influence of Fe2O3 and Fe-85Ni alloy spherical nanoparticles in Bi0.5Sb1.5Te3 (BST) matrix on thermoelectric transport properties has been investigated. The x-ray diffraction and scanning electron microscopy results show that the nanoparticles were dispersed in the matrix. The spark plasma sintered bulk BST/Fe2O3 composite sample exhibited high Seebeck coefficient which was 39% higher than the bare BST due to low carrier concentration and a significant reduction in the thermal conductivity (38%) owing to enhanced carrier scattering by the dispersed nanoparticles compared to that of the bare BST sample. As a result, the maximum ZT values for the BST, BST/Fe2O3, and BST/Fe-85Ni samples were found as 1.17, 0.98, and 0.88 at 375 K, respectively. Micro Vickers hardness of BST/Fe2O3 and BST/Fe-85Ni composite samples was significantly enhanced compared to bare Bi0.5Sb1.5Te3 sample.

  10. Comparison of reduction behavior of Fe2O3,ZnO and ZnFe2O4 by TPR technique

    Institute of Scientific and Technical Information of China (English)

    Meisheng Liang; Wenkai Kang; Keehang Xie

    2009-01-01

    Advanced integrated gasification combined cycle (IGCC) power generation systems require the development of high-temperature,regenerable,desulfurization sorbents capable of removing hydrogen sulfide from coal gasifier gas to very low levels.As a sort of effective desufurizer,such as Fe2O3,ZnO and ZnFe2O4,it will endure strong reducing atmosphere in desulfurization process.The reduced degree of desufurizer can have an effect on its desulfurization reactivity.In this paper,Fe2O3,ZnO and ZnFe2O4 were synthesized by precipitation or co-precipitation at constant pH.After aging,washing and drying,the solids were calcined at 800℃.The reduction behaviors of sample were characterized by temperature-programmed reduction (TPR).It is found that there are two reduction peaks for Fe203 in TPR,and whereas no reduction peaks for ZnO are found.The reduction process of ZnFe2O4 prepared by co-precipitation is different from that of Fe2O3.ZnFe2O4 is easier to be reduced than Fe2O3.The activation energy of reduction process for Fe2O3 and ZnFe2O4 is obtained at different reduction periods.

  11. Evaluating the Effects of Chemical Composition on Induction Heating Ability of Fe2O3-CaO-SiO2 Glass Ceramics

    Directory of Open Access Journals (Sweden)

    Y. Y. Wang

    2016-01-01

    Full Text Available In order to investigate the relationship between induction heating ability of Fe2O3-CaO-SiO2 glass ceramics and chemical composition, a series of glass ceramic samples with different chemical compositions were prepared by the sol-gel method. The structural, textural, and magnetic properties of the samples were analyzed and correlated with the Fe2O3 content. This is the first time work of its kind that evaluates the relationships between induction heating ability and chemical composition of Fe2O3-CaO-SiO2 glass ceramics. The results showed that induction heating ability of Fe2O3-CaO-SiO2 glass ceramics increased gradually with increasing magnetite content. Also, the induction heating ability became considerably better when a small amount of phosphorus was introduced. This study thus reveals a methodology to control the induction heating ability of Fe2O3-CaO-SiO2 glass ceramics through modifying the chemical composition.

  12. Photocatalytic remediation of γ-HCH contaminated soil induced by α-Fe2O3 and TiO2

    Institute of Scientific and Technical Information of China (English)

    ZHAO Xu; QUAN Xie; ZHAO Ya-zhi; ZHAO Hui-min; CHEN Shuo; CHEN Jing-wen

    2004-01-01

    Heterogeneous photocatalytic degradation of γ-HCH on soil surfaces was carried out to evaluate the photocatalytic effectiveness of α-Fe2O3 and TiO2 toward degrading γ-HCH on soil surfaces. After being spiked with γ-HCH, soil samples were loaded with α-Fe2O3 or TiO2 and exposed to UV-light irradiation. Different catalyst loads(0%, 2%, 5%, 7%, and 10% (wt). α-Fe2O3; 0%, 0.5%, 1%, 2% wt. TiO2) were tested for up to 7 d irradiation. The effects of soil thickness, acidity, and humic substances were also investigated. The obtained results indicated that the γ-HCH photodegradation follows the pseudo-first-order kinetics. The addition of α-Fe2O3 or TiO2 accelerates the photodegradation of γ-HCH, while the photodegradation rate decreases when the content of α-Fe2O3 exceeds 7%(wt.). The degradation rate increases with the soil pH value. Humic substances inhibit the photocatalytic degradation of γ-HCH. Pentachlorocyclohexene, tetrachlorocyclohexene, and trichlorobenzene are detected as photodegradation intermediates, which are gradually degraded with the photodegradation evolution.

  13. Spinous α-Fe2O3 hierarchical structures anchored on Ni foam for supercapacitor electrodes and visible light driven photocatalysts.

    Science.gov (United States)

    Zheng, Xin; Han, Zhicheng; Yao, Shunyu; Xiao, Huanhao; Chai, Fang; Qu, Fengyu; Wu, Xiang

    2016-04-28

    Spinous α-Fe2O3 hierarchical structures grown on a Ni foam substrate have been successfully obtained by a facile one-step hydrothermal method. The prepared products are functionalized as supercapacitor electrodes without adding any ancillary materials such as carbon black or binders. Their electrochemical properties show a high discharge areal capacitance (681 mF cm(-2) at 1 mA cm(-2)), good rate performance (495 mF cm(-2) at 5 mA cm(-2)) and long-term cycling stability (23.9% loss after 6000 repetitive cycles at 1 mA cm(-2)). Such excellent supercapacitive characteristics could be mainly attributed to their unique spatial structures which provide many active sites and enhance the combination between the electrode and Ni foam to support fast ion and electron transfer. In addition, the prepared α-Fe2O3 product is also used as a photocatalyst for the photocatalytic degradation of several harmful organic dyes under visible light illumination. By comparing the photocatalytic performance towards Congo red dye with other photocatalysts, it was observed that the prepared spinous α-Fe2O3 hierarchical structure exhibited superior photocatalytic performance. Finally, photocatalytic recycle tests showed the superiority of the prepared α-Fe2O3 product. This demonstrates that spinous α-Fe2O3 structures could be promising candidate materials for high-capacity, low-cost supercapacitor electrodes and environmentally friendly photocatalysts.

  14. Preparation and properties of magnetic alumina microspheres with a γ-Fe2O3/SiO2 core and Al2O3 shell

    Institute of Scientific and Technical Information of China (English)

    Qingtao Fu; Tingting He; Lianqing Yu; Yongming Chai; Chenguang Liu

    2011-01-01

    Magnetic alumina composite microspheres with γ-Fe2O3 core/Al2O3 shell structure were prepared by the oil column method.A dense silica layer was deposited on the surface of γ-Fe2O3 particles(denoted as γ-Fe2O3/SiO2)with a desired thickness to protect the iron oxide core against acidic or high temperature conditions.γ-Fe2O3/SiO2/Al2O3 particles with about 85 wt% Al2O3 were obtained and showed to be suitable for practical applications as a magnetic catalyst or catalyst support due to their magnetic properties and pore structure.The products were characterized with scanning electron microscope(SEM)and transmission electron microscope(TEM),nitrogen adsorption-desorption,and vibrating sample magnetometer(VSM).The specific surface area and pore volume of the γ-Fe2O3/SiO2/Al2O3 composite microspheres calcined at 500 ℃ were 200 m2/g and 0.77 cm3/g,respectively.

  15. Facile hybridization of Ni@Fe2O3 superparticles with functionalized reduced graphene oxide and its application as anode material in lithium-ion batteries.

    Science.gov (United States)

    Backert, Gregor; Oschmann, Bernd; Tahir, Muhammad Nawaz; Mueller, Franziska; Lieberwirth, Ingo; Balke, Benjamin; Tremel, Wolfgang; Passerini, Stefano; Zentel, Rudolf

    2016-09-15

    In our present work we developed a novel graphene wrapping approach of Ni@Fe2O3 superparticles, which can be extended as a concept approach for other nanomaterials as well. It uses sulfonated reduced graphene oxide, but avoids thermal treatments and use of toxic agents like hydrazine for its reduction. The modification of graphene oxide is achieved by the introduction of sulfate groups accompanied with reduction and elimination reactions, due to the treatment with oleum. The successful wrapping of nanoparticles is proven by energy dispersive X-ray spectroscopy, high-resolution transmission electron microscopy and Raman spectroscopy. The developed composite material shows strongly improved performance as anode material in lithium-ion batteries (compared to unwrapped Ni@Fe2O3) as it offers a reversible capacity of 1051mAhg(-1) after 40 cycles at C/20, compared with 460mAhg(-1) for unwrapped Ni@Fe2O3. The C rate capability is also improved by the wrapping approach, as specific capacities for wrapped particles are about twice of those offered by unwrapped particles. Additionally, the benefit for the use of the advanced superparticle morphology is demonstrated by comparing wrapped Ni@Fe2O3 particles with wrapped Fe2O3 nanorice.

  16. Porous γ-Fe2O3 spheres coated with N-doped carbon from polydopamine as Li-ion battery anode materials

    Science.gov (United States)

    Liang, Jin; Xiao, Chunhui; Chen, Xu; Gao, Ruixia; Ding, Shujiang

    2016-05-01

    Nitrogen doping has been demonstrated to play a crucial role in controlling the electronic properties of carbon-based composites. In this paper, nitrogen-doped carbon coated γ-Fe2O3 (NC@γ-Fe2O3) composite was successfully fabricated through a facile and high-yield strategy, including a hydrothermal reaction process for porous γ-Fe2O3 and a subsequent coating of nitrogen-doped carbon by using dopamine as precursor. The resulting composite combines the superior properties of porous Fe2O3 and heteroatom-doped conductive carbon layer derived from polydopamine. When used as the anode material of the lithium-ion battery, the as-prepared NC@γ-Fe2O3 composite exhibits excellent lithium storage properties in terms of high capacity, stable cycling performance (869.6 mAh g-1 at the current density of 0.5 A g-1 after 150 cycles) and excellent rate capability.

  17. Preparation, characterization and photocatalytic activity of Fe2O3/ZnO and Fe3O4/ZnO

    Directory of Open Access Journals (Sweden)

    Patij Shah

    2014-03-01

    Full Text Available Composite Iron oxide-Zinc oxide (α-Fe2O3/ZnO and Fe3O4/ZnO was synthesized by two step method. In the first step, uniform α-Fe2O3 and Fe3O4 particles were prepared through a hydrolysis process of ferric chloride at 80°C. In the second step, the ZnO particles were included in the α-Fe2O3 and Fe3O4 particles by a zinc acetate [Zn(Ac2·2H2O] assisted hydrothermal method at low temperature (90 °C. X-ray Powder Diffraction (XRD, Scanning Electron microscopy (SEM, Energy-dispersive X-ray spectroscopy (EDAX was used to study its structural properties. The α-Fe2O3 and ZnO phases were identified by XRD, energy dispersive X-ray analysis (EDAX. The photoactivities of α-Fe2O3/ZnO and Fe3O4/ZnO nanoparticles under UV irradiation were quantified by the degradation of formaldehyde. The determination of magnetic property was also carried out by Gouy balance method.

  18. Electrochemical synthesis and photoelectrochemical properties of grass-like nanostructured α-Fe2O3 photoanodes for use in solar water oxidation

    Science.gov (United States)

    Hanedar, Yesim; Demir, Umit; Oznuluer, Tuba

    2016-10-01

    Grass-like nanostructured α-Fe2O3 photoelectrodes were prepared for the first time through a simple cathodic electrodeposition method from an oxygenated aqueous solution of Fe3+ at room temperature without using surfactant, capping agents or any other additives. The α-Fe2O3 electrodeposits were characterized by X-ray photoelectron spectroscopy (XPS), energy dispersive spectroscopy (EDS), scanning electron microscopy (SEM), X-ray diffraction (XRD), UV-vis absorption and photoelectrochemical (PEC) techniques. The SEM and XRD results indicated that the as-deposited α-Fe2O3 are composed of single crystalline nanoleaves. The formation mechanisms of α-Fe2O3 have also been proposed based on a series of cyclic voltammetric and XPS studies. This new electrochemical method is expected to be a useful technique for the fabrication of single crystalline and photoactive α-Fe2O3 nanostructures directly onto the electrode surface, which is required in most applications, such as energy conversion and storage and sensors.

  19. Porous γ-Fe2O3 spheres coated with N-doped carbon from polydopamine as Li-ion battery anode materials.

    Science.gov (United States)

    Liang, Jin; Xiao, Chunhui; Chen, Xu; Gao, Ruixia; Ding, Shujiang

    2016-05-27

    Nitrogen doping has been demonstrated to play a crucial role in controlling the electronic properties of carbon-based composites. In this paper, nitrogen-doped carbon coated γ-Fe2O3 (NC@γ-Fe2O3) composite was successfully fabricated through a facile and high-yield strategy, including a hydrothermal reaction process for porous γ-Fe2O3 and a subsequent coating of nitrogen-doped carbon by using dopamine as precursor. The resulting composite combines the superior properties of porous Fe2O3 and heteroatom-doped conductive carbon layer derived from polydopamine. When used as the anode material of the lithium-ion battery, the as-prepared NC@γ-Fe2O3 composite exhibits excellent lithium storage properties in terms of high capacity, stable cycling performance (869.6 mAh g(-1) at the current density of 0.5 A g(-1) after 150 cycles) and excellent rate capability.

  20. Thin film processes II

    CERN Document Server

    Kern, Werner

    1991-01-01

    This sequel to the 1978 classic, Thin Film Processes, gives a clear, practical exposition of important thin film deposition and etching processes that have not yet been adequately reviewed. It discusses selected processes in tutorial overviews with implementation guide lines and an introduction to the literature. Though edited to stand alone, when taken together, Thin Film Processes II and its predecessor present a thorough grounding in modern thin film techniques.Key Features* Provides an all-new sequel to the 1978 classic, Thin Film Processes* Introduces new topics, and sever

  1. Pyrolyzed thin film carbon

    Science.gov (United States)

    Tai, Yu-Chong (Inventor); Liger, Matthieu (Inventor); Harder, Theodore (Inventor); Konishi, Satoshi (Inventor); Miserendino, Scott (Inventor)

    2010-01-01

    A method of making carbon thin films comprises depositing a catalyst on a substrate, depositing a hydrocarbon in contact with the catalyst and pyrolyzing the hydrocarbon. A method of controlling a carbon thin film density comprises etching a cavity into a substrate, depositing a hydrocarbon into the cavity, and pyrolyzing the hydrocarbon while in the cavity to form a carbon thin film. Controlling a carbon thin film density is achieved by changing the volume of the cavity. Methods of making carbon containing patterned structures are also provided. Carbon thin films and carbon containing patterned structures can be used in NEMS, MEMS, liquid chromatography, and sensor devices.

  2. Solid state reaction of the Fe2 O3-TiO2 system in argon%氩气下Fe2 O3--TiO2体系的固相反应

    Institute of Scientific and Technical Information of China (English)

    任中山; 胡晓军; 薛向欣; 周国治

    2014-01-01

    在氩气气氛下,采用扩散偶法研究了1323~1473 K下的Fe2 O3-TiO2体系的固相反应.使用电子探针对扩散偶的微观形貌进行观察,并对Fe、Ti离子的扩散摩尔分数曲线进行定量分析.动力学分析表明,氩气下体系的固相反应受铁、钛和氧离子的扩散控制.用Boltzmann-Matano法计算了体系的互扩散系数,其数量级在10-13~10-10 cm2·s-1范围内,并随着温度和Ti离子摩尔分数的增大而升高.氩气气氛下体系的扩散活化能约为356.06 kJ·mol-1,远比空气下的大,表明外界气氛中氧分压对体系的反应机理有重要影响.%ABSTRACT The diffusion couple method was used to study the solid-state reaction of the Fe2 O3-TiO2 system in the temperature range of 1323 K to 1473 K in argon. The microstructure of the diffusion couple and the diffusion concentration profiles of Fe and Ti were determined by electron probe microanalysis ( EPMA) . According to kinetic analysis, this solid-state reaction is controlled by the diffu-sion of Fe, Ti and O ions. The inter-diffusion coefficient, which increases with the increasing temperature and concentration of Ti ions, was calculated by the Boltzmann-Matano method, and its order of magnitude is in the range of 10 -13 to 10 -10 cm2·s-1 . The diffusion activation energy ( about 356.06 kJ·mol-1 ) of the system in argon is much bigger than that in air, which indicates that the partial pres-sure of oxygen in atmosphere has important effect on the reaction mechanism of the system.

  3. Synthesis of higher alcohols from CO2 hydrogenation over a PtRu/Fe2O3 catalyst under supercritical condition.

    Science.gov (United States)

    He, Zhenhong; Qian, Qingli; Zhang, Zhaofu; Meng, Qinglei; Zhou, Huacong; Jiang, Zhiwei; Han, Buxing

    2015-12-28

    Hydrogenation of CO(2) to alcohols is of great importance, especially when producing higher alcohols. In this work, we synthesized heterogeneous PtRu/Fe(2)O(3), in which the Pt and Ru bimetallic catalysts were supported on Fe(2)O(3). The catalyst was used to catalyse CO(2) hydrogenation to alcohols. It was demonstrated that the activity and selectivity could be tuned by the bimetallic composition, and the catalyst with a Pt to Ru molar ratio of 1:2 (Pt(1)Ru(2)/Fe(2)O(3)) had high activity and selectivity at 200°C, which is very low for heterogeneous hydrogenation of CO(2) to produce higher alcohols. The conversion and the selectivity increased with increasing pressures of CO(2) and/or H(2). The catalyst could be reused at least five times without any obvious change in activity or selectivity.

  4. Preparation and Photocatalytic Activity of ZnO/Fe2O3 Nanorod Arrays and ZnO/NiO Nanotube Arrays

    Institute of Scientific and Technical Information of China (English)

    CUI Yin-Fang; WANG Cong; WU Su-Juan; LIU Yu; WANG Tian-Min

    2012-01-01

    ZnO/Fe2O3 nanorod arrays (NRs) and ZnO/NiO nanotube arrays (NTs) are synthesized on Si substrates by using a facile two-step growth method.The absorption spectrum of the ZnO/Fe2O3 NRs shows significant absorption in the visible light region.Their photocatalytic properties are evaluated by the degradation of methylene blue (MB).It is found that the ZnO/Fe2O3 NRs display higher photocatalytic activity than the ZnO/NiO nanotube arrays under UV-vis light irradiation.This is most likely attributed to an effective separation of photoelectrons and holes.

  5. Study on preparation of S2O82-/Fe2O3-SiO2 solid acid and its catalytic activity

    Institute of Scientific and Technical Information of China (English)

    Wu Donghui; Jin Ruidi; Wang Xin

    2006-01-01

    The precursors of Fe2O3-SiO2 mixed oxides prepared through co-precipitation method were modified by microwave hydrothermal treatment for the first time.S2O82-/Fe2O3-SiO2 solid acids were formed after being impregnated by (NH4)2S2O8 solution and calcined at high temperature.The samples were characterized by XRD,TEM,N2 adsorption/desorption methods.It was found that the presence of SiO2 obviously retarded the formation and growth of Fe2O3 crystals.Catalyst with appropriate specific surface area and narrow pore size distribution was obtained.The catalytic activities of the solid acids were evaluated by esterification of acetic acid and butanol and the results were compared with those catalysts prepared at normal conditions.The results showed that catalytic activity was extensively improved by microwave hydrothermal treatment.

  6. Imidazolium ionic liquid induced one-step synthesis of -Fe2O3 nanorods and nanorod assemblies for lithium-ion battery

    Directory of Open Access Journals (Sweden)

    Shuting Xie

    2016-12-01

    Full Text Available α-Fe2O3 nanorods and nanorod assemblies are prepared via a facile one-step method with the assistance of imidazolium-based ionic liquid. The aspect ratio of synthesized nanorods is determined by the alkyl chain length of [Cnmim]+. The inter-molecular π−π interaction and intra-molecular dipole-dipole interaction among imidazole rings of [C4mim]+[PhCOO]− play critical roles in both nucleation and assembly processes of α-Fe2O3 nanorods. The α-Fe2O3 nanorod assemblies show an excellent performance in lithium-ion batteries with a reversible capacity of 1007.3 mA h g−1 at the rate of 500 mA g−1 after 150 cycles.

  7. Characterization of nanostructured alpha-Fe2O3-SnO2 solid solutions prepared by high energy ball milling

    DEFF Research Database (Denmark)

    Jiang, Jianzhong; Lin, R.; Mørup, Steen

    1998-01-01

    Solid solutions of SnO2 in alpha-Fe2O3 with SnO2 contents up to 20+-4 mol% have been prepared by mechanical alloying of alpha-Fe2O3 and SnO2 powder blends. X-ray diffraction and Mossbauer spectroscopy investigations show that the mechanical milling results in alloying on an atomic scale...... and that true solid solution formation occurs. We suggest that the high defect concentration and the chemical enthalpy of Fe3+ -O2- -Sn4+ interfaces between nanostructured alpha-Fe2O3 and SnO2 regions may serve as a driving force for the formation of a solid solution in the immiscible ceramic system....

  8. Characterization of nanostructured alpha-Fe2O3-SnO2 solid solutions prepared by high energy ball milling

    DEFF Research Database (Denmark)

    Jiang, Jianzhong; Lin, R.; Mørup, Steen

    1998-01-01

    Solid solutions of SnO2 in alpha-Fe2O3 with SnO2 contents up to 20+-4 mol% have been prepared by mechanical alloying of alpha-Fe2O3 and SnO2 powder blends. X-ray diffraction and Mossbauer spectroscopy investigations show that the mechanical milling results in alloying on an atomic scale...... and that true solid solution formation occurs. We suggest that the high defect concentration and the chemical enthalpy of Fe3+ -O2- -Sn4+ interfaces between nanostructured alpha-Fe2O3 and SnO2 regions may serve as a driving force for the formation of a solid solution in the immiscible ceramic system....

  9. α-Fe2O3 nanoparticles on Bi2MoO6 nanofibers: One-dimensional heterostructures synergistic system with enhanced photocatalytic activity

    Science.gov (United States)

    Zhao, Jie; Lu, Qifang; Wang, Qinyu; Ma, Quanshan

    2016-03-01

    The one-dimenional (1D) α-Fe2O3/Bi2MoO6 heterostructures with α-Fe2O3 nanoparticles grown on Bi2MoO6 nanofibers were fabricated by combining the electrospinning with solvothermal method. The obtained 1D heterostructures were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), raman spectroscopic technique, brunauer-emmett-teller (BET) analysis, UV-vis diffuse reflectance spectrum (UV-vis DRS) and photoluminescence (PL) spectrum. The photocatalytic studies revealed that the heterostructures exhibited the extraordinary photocatalytic activity under simulated sunlight irradiation, which might put down to the effective separation of photo-induced carriers at the α-Fe2O3/Bi2MoO6 heterojunction interfaces and higher specific surface area.

  10. Efficient one-pot synthesis of hierarchical flower-like α-Fe2O3 hollow spheres with excellent adsorption performance for water treatment

    Science.gov (United States)

    Zhu, Daozheng; Zhang, Jian; Song, Jiming; Wang, Haisheng; Yu, Zheng; Shen, Yuhua; Xie, Anjian

    2013-11-01

    A simple one-step method has been developed for the controllable synthesis of hierarchical flower-like α-Fe2O3 hollow spheres in a glycerol-ethanol system. It is found that the volume ratio of glycerol/ethanol and reaction time have a significant effect on the morphology of the products. The growth process of α-Fe2O3 hollow spheres has been investigated and a possible mechanism is proposed. The α-Fe2O3 hollow spheres have a high surface area of 98 m2 g-1 and a total pore volume of 0.32 cm3 g-1, which exhibit outstanding water treatment performance with high removal capacities toward organic dyes and heavy metal ions. The as-obtained products may have potential applications in water treatment and other related micro- or nanoscale devices.

  11. Crystal structure transformation of TiO2 in presence of Fe2O3 and NiO in air atmosphere

    Indian Academy of Sciences (India)

    S Riyas; V Ahmed Yasir; P N Mohan Das

    2002-08-01

    TiO2 is produced and marketed in two main grades viz. anatase and rutile. Both anatase and rutile have their own pigmentry properties and hence cannot be substituted by each other. Pure anatase on heating at higher temperatures undergoes crystallographic rearrangement to form rutile. This transformation in presence of NiO and Fe2O3 under air atmosphere was studied using XRD and SEM. The transformation temperature was found to be reduced much in presence of NiO and Fe2O3 and the extent of lowering was higher for NiO than Fe2O3. The activation energy for this transformation was also calculated. The method of preparation had major influence on the transformation.

  12. Surface modification of Fe2O3 nanoparticles with 3-aminopropyltrimethoxysilane (APTMS): An attempt to investigate surface treatment on surface chemistry and mechanical properties of polyurethane/Fe2O3 nanocomposites

    Science.gov (United States)

    Palimi, M. J.; Rostami, M.; Mahdavian, M.; Ramezanzadeh, B.

    2014-11-01

    Fe2O3 nanoparticles were modified with various amounts of 3-amino propyl trimethoxy silane (APTMS). Modified and unmodified nanoparticles were introduced into the polyurethane matrix at different concentrations. Fourier transform infrared radiation (FT-IR) and X-ray photoelectron spectrophotometer (XPS) were employed in order to investigate the APTMS grafting on the nanoparticles field emission-scanning electron microscope (FE-SEM) was utilized in order to investigate nanoparticles dispersion in the polyurethane coating matrix as well as the fracture behavior of the nanocomposites. The mechanical properties of the nanocomposites were investigated by dynamic mechanical thermal analysis (DMTA) and tensile test. The FTIR spectra and XPS analysis clearly showed that APTMS was grafted on the surface of nanoparticles successfully and formed chemical bonds with the surface. Also, surface treatment of the nanoparticles by silane resulted in the significant improvement of the mechanical properties of the polyurethane coating. The improvement was most pronounced when the nanoparticles were modified with 3 gr silane/5 g nanoparticles.

  13. Adsorption of uranium ( Ⅵ ) by immobilized nano-α - Fe2O3 micro-beads%纳米α - Fe2O3微球对U(Ⅵ)的吸附特性研究

    Institute of Scientific and Technical Information of China (English)

    李银; 谢水波; 刘迎九; 李仕友; 荣丽杉; 凌辉

    2012-01-01

    将海藻酸钠与纳米α-Fe2O3制成微球,用于吸附U(Ⅵ).探讨了纳米α - Fe2O3含量、交联时间、pH值、投加量、浓度、温度等对吸附的影响.结果表明,pH值对U(Ⅵ)的吸附过程影响显著,适宜pH值为3.U(Ⅵ)在微球上的吸附量随着吸附时间的增加而增大,初始阶段(1.5 h)反应进行得很快,9h时达到吸附平衡.当U(Ⅵ)初始质量浓度为10mg/L时,其饱和吸附量为2.64mg/g.准二级动力方程很好地拟合了吸附动力学数据,且R2> 0.99.吸附率与温度呈正相关,Langmuir与Freundlich吸附等温方程均能较好地拟合固定化微球对U(Ⅵ)的吸附过程(R2> 0.99),但Freundlich等温线效果更好.吸附反应中ΔG<0,ΔH>0且小于40 kJ/mol,ΔS>0,这表明吸附过程能自发进行,为吸热反应.%The given paper is to present our experimental results on the adsorption of uranium(VI) in the solution by nnno-α - Fe2O3 micro-beads immobilized into sodium alginate (SA) , which we have investigated in a batch experiment. As is known, nuclear energy, on the one hand, has brought about huge economic benefits lo the world, on the other hand, it is inevitable for nuclear fuel production to generate low-level radiation waste, such as uranium and other radioactive heavy metals which are detrimental to us humans in many aspects. Therefore, strong demand has been existing to find and apply some kind of powerful adsorbent to reduce and eliminate such harmful nuclear waste to protect our environment. It is just from this need we would like to assume the task to study and analyze the effects of nano-α - Fe2O3 powders content in the particles, cross-linking time, solution pH value, adsorbent dose, initial U ( VI) concentration, temperature and contact time for U(VI) adsorption. The results of our study indicate that the adsorption capacity is strongly affected by the pH value of solution with the optimal pH value being 3. Besides, we have also found that the adsorption process can

  14. A magnetically separable photocatalyst based on nest-like γ-Fe2O3/ZnO double-shelled hollow structures with enhanced photocatalytic activity

    Science.gov (United States)

    Liu, Yu; Yu, Le; Hu, Yong; Guo, Changfa; Zhang, Fumin; Wen (David) Lou, Xiong

    2011-12-01

    Magnetic nest-like γ-Fe2O3/ZnO double-shelled hollow nanostructures have been successfully synthesized via a multi-step process. The materials have been thoroughly characterized by different techniques. These interesting nest-like hollow nanostructures are composed of ZnO nanoflakes grown on the surface of γ-Fe2O3 hollow spheres. Importantly, these magnetic hollow nanostructures show very high visible-light photocatalytic activity for the degradation of different organic dyes including methylene blue (MB), Rhodamine-B (RhB), and methyl orange (MO). It is further demonstrated that these γ-Fe2O3/ZnO hybrid photocatalysts are highly stable and can be used repeatedly.Magnetic nest-like γ-Fe2O3/ZnO double-shelled hollow nanostructures have been successfully synthesized via a multi-step process. The materials have been thoroughly characterized by different techniques. These interesting nest-like hollow nanostructures are composed of ZnO nanoflakes grown on the surface of γ-Fe2O3 hollow spheres. Importantly, these magnetic hollow nanostructures show very high visible-light photocatalytic activity for the degradation of different organic dyes including methylene blue (MB), Rhodamine-B (RhB), and methyl orange (MO). It is further demonstrated that these γ-Fe2O3/ZnO hybrid photocatalysts are highly stable and can be used repeatedly. Electronic supplementary information (ESI) available: XRD/TEM/schematic illustration of charge transfer. See DOI: 10.1039/c1nr11114k

  15. Hierarchical Assembly of α-Fe2O3 Nanorods on Multiwall Carbon Nanotubes as a High-Performance Sensing Material for Gas Sensors.

    Science.gov (United States)

    Dai, Mingjun; Zhao, Liupeng; Gao, Hongyu; Sun, Peng; Liu, Fengmin; Zhang, Sean; Shimanoe, Kengo; Yamazoe, Noboru; Lu, Geyu

    2017-03-15

    This paper presents a facile hydrolysis reaction and annealing for preparing a novel hierarchical nanoheterostructure via assembly of α-Fe2O3 nanorods onto multiwall carbon nanotubes (MWCNTs) backbones. The as-synthesized nanocomposites were characterized using XRD (X-ray diffraction), FESEM (Field emission scanning electron microscopy), TEM (Transmission electron microscopy), XPS (X-ray photoelectron spectroscopy) and BET (Surface Area and Porosity System). The observations showed uniform α-Fe2O3 nanorods approximately 100-200 nm in length and 50-100 nm in diameter that were hierarchically assembled onto the surface of the MWCNTs. The formation of the heterostructure was investigated by observing the evolution of the microstructure of the products at different reaction times. The X-ray photoelectron spectra (XPS) showed that the ability of the absorbing oxygen was enhanced by the formation of the heterostructure composites. Moreover, as a proof-of-concept presentation, the novel CNTs@α-Fe2O3 hierarchical heterostructure acted as a gas sensitive material. Significantly, the composites exhibited excellent sensing properties for acetone with high sensitivity, exceptional selectivity and good reproducibility. The response of the CNTs@α-Fe2O3 sensor to 100 ppm acetones at 225 °C was nearly 35, which was superior to the single α-Fe2O3 nanorods with a response of 16, and the detection limit of the sensor was 500 ppb. The enhanced properties were mainly attributed to the unique structure and p-n heterojunction between the CNTs and the α-Fe2O3 nanorods.

  16. Preparation of Fe2O3-TiO2 composite from Sukabumi iron sand through magnetic separation, pyrometallurgy, and hydrometallurgy

    Science.gov (United States)

    Wahyuningsih, S.; Ramelan, A. H.; Pranata, H. P.; Hanif, Q. A.; Ismoyo, Y. A.; Ichsan, K. F.

    2016-11-01

    Preparation of Fe2O3/TiO2 composite from Sukabumi iron sand by magnetic separation, roasting, leaching and precipitation treatment has been carried out. Magnetic separation can separate magnetic particles and non-magnetic particles of iron sand content, while the non-magnetic particles (wustite (FeO), hematite (α-Fe2O3), maghemite (γ-Fe2O3) and magnetite (Fe3O4)) was washing with oxalic acid 1 M. The result product then was roasted at 800 °C treated by sodium carbonate (Na2CO3) addition of 1:1; 2:1 and 1:2 (w/w) of iron sand to Na2CO3 weight ratio, respectively. The X-Ray Fluorescence (XRF) analysis result shown that Sukabumi iron sand have hematite (Fe2O3) and titanium dioxide (TiO2) content about 72.17% dan 14.42%. XRD analysis of roasted iron sand shown the rutile (TiO2), Hematite (Fe2O3), NaFeO2, FeO, and Na2TiO3. Leaching of roasted iron sand using sulphuric acid (H2SO4) have influenced by concentrations of the H2SO4 solution. The optimum iron sand dissolution occurred in H2SO4 9 M, which condensation product of the leachant have a weight ratio of Fe:Ti = 1:1 (w/w). Meanwhile, the settling back-filtrate result of second condensation was obtained a ratio of Fe2O3: TiO2 of 3: 1 (w/w).

  17. Controlled synthesis of Fe2O3 modified Ag-010BiVO4 heterostructures with enhanced photoelectrochemical activity toward the dye degradation

    Science.gov (United States)

    Li, Junqi; Zhou, Jian; Hao, Hongjuan; Li, Weijie

    2017-03-01

    Crystal facet dependence is an important approach for optimizing the performance of photocatalyst. In consideration that there is a close correlation between the photoelectric conversion efficiencies and crystal facet, the monoclinic bismuth vanadate (m-BiVO4) with (010) and (110) crystal facets has drawn attention. We designed the Ag nanoparticles modified the (010) facet of the BiVO4 (Ag-010BiVO4) and then the Ag-010BiVO4 heterogeneous nanostructure was modified by the Fe2O3 nanoparticles. In the Fe2O3 modified Ag-010BiVO4, the (110) facet of the BiVO4 was only modified by the Fe2O3 nano-particles to construct the n-n heterojunction structure. Simultaneously, the Z-scheme system was fabricated on the (010) facet of the BiVO4, where was modified by the Ag and Fe2O3 nano-particles. We investigated its photoelectrochemical (PEC) and photocatalytic activities by the measurement of the electrochemical performance and degradation of methyl orange (MO). The Ag species in the system is only treated as the solid state electron mediator. As was expected, the Fe2O3 modified Ag-010BiVO4 heterojunction structure exhibited the highest photocurrent density and the smallest impedance. Besides, the Fe2O3 modified Ag-010BiVO4 heterojunction structure exhibited excellent redox ability and the MO could be degraded 92% after 150 min. It is worth noting that the outstanding performance should be attributed to the synergistic effect of n-n and Z-scheme system in the different facets, which facilitated the separation of holes and electrons in the opposite direction.

  18. γ-Fe2O3 and Fe3O4 magnetic hierarchically nanostructured hollow microspheres: preparation, formation mechanism, magnetic property, and application in water treatment.

    Science.gov (United States)

    Xu, Jing-San; Zhu, Ying-Jie

    2012-11-01

    In this paper, we report the preparation of γ-Fe(2)O(3) and Fe(3)O(4) magnetic hierarchically nanostructured hollow microspheres by a solvothermal combined with precursor thermal conversion method. These γ-Fe(2)O(3) and Fe(3)O(4) magnetic hierarchically nanostructured hollow microspheres were constructed by three-dimensional self-assembly of nanosheets, forming porous nanostructures. The effects of experimental parameters including molar ratio of reactants and reaction temperature on the precursors were studied. The time-dependent experiments indicated that the Ostwald ripening was responsible for the formation of the hierarchically nanostructured hollow microspheres of the precursors. γ-Fe(2)O(3) and Fe(3)O(4) magnetic hierarchically nanostructured hollow microspheres were obtained by the thermal transformation of the precursor hollow microspheres. Both γ-Fe(2)O(3) and Fe(3)O(4) hierarchically nanostructured hollow microspheres exhibited a superparamagnetic property at room temperature and had the saturation magnetization of 44.2 and 55.4 emu/g, respectively, in the applied magnetic field of 20 KOe. Several kinds of organic pollutants including salicylic acid (SA), methylene blue (MB), and basic fuchsin (BF) were chosen as the model water pollutants to evaluate the removal abilities of γ-Fe(2)O(3) and Fe(3)O(4) magnetic hierarchically nanostructured hollow microspheres. It was found that γ-Fe(2)O(3) hierarchically nanostructured hollow microspheres showed a better adsorption ability over SA than MB and BF. However, Fe(3)O(4) hierarchically nanostructured hollow microspheres had the best performance for adsorbing MB. Copyright © 2012 Elsevier Inc. All rights reserved.

  19. Fe2O3对污泥与底泥制备轻质陶粒性能的影响%Effect of Fe2O3 on the characteristics of lightweight aggregate made from sewage sludge and river sediment

    Institute of Scientific and Technical Information of China (English)

    刘明伟; 许国仁; 李圭白

    2012-01-01

    The aim of this article is to investigate the effect of Fe2O3 contents on the characteristics of lightweight aggregate that is made from sewage sludge and river sediment.The physical characteristics,compressive strength,morphological structures and crystalline phases of lightweight aggregate were studied,and the results showed that the lightweight aggregate with higher bulk density,higher apparent density,and lower water absorption could be obtained at Fe2O3 contents between 3.5%-7%.The SEM analysis points out that the surface of lightweight aggregate exhibits more vitrification phenomenon as the Fe2O3 contents increase,the dense surface of lightweight aggregate with evenly distributed micro porous can be found at Fe2O3 contents=5%.The lightweight aggregate with stronger compressive strength(more than 14 MPa) can be obtained when Fe2O3 contents are between 3.5%-7%.The XRD analysis implies that the main crystal phase in the lightweight aggregate are quartz,albite-anorthite,kyanite and hematite,and the silicate crystals with stable structure are the main crystal in the internal of lightweight aggregate.As the Fe2O3 contents increase,more Fe2O3 will transform to hematite with crystal structure.The results indicate that the Fe2O3 contents between 3.5%-7% are appropriate in the process of making lightweight aggregate from sewage sludge and river sediment.%为研究在以污水污泥和河道底泥为主要原料制取轻质陶粒过程中,Fe2O3质量分数对陶粒性能的影响,对陶粒的物理性能、表面形态、抗压强度和晶体构成进行研究,结果表明,Fe2O3质量分数在3.5%~7%时,可取得松散容重和表观密度较高、吸水率比较小、抗压强度较高的陶粒.扫描电子显微镜(SEM)分析表明,随着Fe2O3质量分数的增加,陶粒表面玻璃化效果明显.在Fe2O3质量分数为5%时,可得到致密性较好、表面微孔分布均匀的陶粒.Fe2O3质量分数在3.5%~7%时,陶粒的抗压性能良好(14 MPa以上

  20. Fe2O3对阿利特-硫铝酸盐水泥熟料矿物形成影响的研究%Study on the effect of Fe2O3 on the formation of minerals in alite- sulfoaluminate clinker

    Institute of Scientific and Technical Information of China (English)

    李艳君; 刘晓存; 曾贤成

    2000-01-01

    以纯化学试剂配料,研究了Fe2O3对阿利特-硫铝酸盐水泥熟料矿物形成的影响.结果表明,低温下煅烧,Fe2O3不利于系统中fCaO的吸收;高温下煅烧,一定量的Fe2O3可促进C3S及C4A3矿物的形成,有利于其在熟料中的共存;而当Fe2O3含量较高时,将会阻碍C3S的形成及降低C4A3的含量.

  1. Pd-isatin Schiff base complex immobilized onγ-Fe2O3 as a magnetically recyclable catalyst for the Heck and Suzuki cross-coupling reactions

    Institute of Scientific and Technical Information of China (English)

    Sara Sobhani; Farzaneh Zarifi

    2015-01-01

    A Pd‐isatin Schiff base complex immobilized onγ‐Fe2O3 (Pd‐isatin Schiff base‐γ‐Fe2O3) was synthe‐sized and characterized by Fourier transform infrared, scanning electron microscopy, high resolu‐tion transmission electron microscopy, X‐ray diffraction, thermogravimetric gravimetric analysis, inductively‐coupled plasma, X‐ray photoelectron spectroscopy, and elemental analysis. It was used as a magnetically reusable Pd catalyst for the Heck and Suzuki cross‐coupling reactions.

  2. EMR searching of quantum behavior of magnetic γ-Fe2O3 nanoparticles encapsulated into poly(propylene imine dendrimer

    Directory of Open Access Journals (Sweden)

    Vorobeva V.E., Domracheva N.E., Gruzdev M.S.

    2016-12-01

    Full Text Available The superparamagnetic γ-Fe2O3 nanoparticles (average diameter of 2.5 nm encapsulated in poly(propylene imine dendrimer have been investigated by electron magnetic resonance (EMR. EMR measurements have been recorded in perpendicular and parallel configurations in the wide temperature range (4.2-300 K. It has been shown that the model based on the spin value S = 30, corresponding to the total magnetic moment of the nanoparticle, can be used to interpret the experimental results and the proof of the quantum behavior of γ-Fe2O3 nanoparticles.

  3. Enhanced photoelectrochemical performance of Ti-doped hematite thin films prepared by the sol-gel method

    Science.gov (United States)

    Lian, Xiaojuan; Yang, Xin; Liu, Shangjun; Xu, Ying; Jiang, Chunping; Chen, Jinwei; Wang, Ruilin

    2012-01-01

    Ti-doped α-Fe2O3 thin films were successfully prepared on FTO substrates by the sol-gel route. Hematite film was characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and energy dispersive spectrometer (EDS). The XRD data showed α-Fe2O3 had a preferred (1 1 0) orientation which belonged to the rhombohedral system. Interestingly, the grains turned into worm-like shape after annealed at high temperature. The IPCE could reach 32.6% at 400 nm without any additional potential vs. SCE. Titanium in the lattice can affect the photo electro chemical performance positively by increasing the conductivity of the thin film. So the excited electrons and holes could live longer, rather than recombining with each other rapidly as undoped hematite. And the efficient carrier density on the Ti-doped anode surface was higher than the undoped anode, which contribute to the well PEC performance.

  4. Enhanced Removal of Arsenic and Antimony in the Mining Site by Calcined γ-Fe2O3/Layered Double Hydroxide Nanocomposite

    Science.gov (United States)

    Lee, Sang-Ho; Choi, Heechul; Kim, Kyoung-Woong

    2016-04-01

    Arsenic (As) and Antimony (Sb) have been recognized as harmful contaminants in aquatic environment due to its high toxicity and carcinogenicity. Especially, the contamination of arsenic in the mining areas is considered as a serious emerging environmental issue in Korea. Due to the hazardous effect of arsenic, the United States Environmental Protection Agency (US EPA) regulated maximum contamination level of arsenic to 10 μg/L in drinking water. The harmful effect on human health by excessive intake of antimony was also reported by previous studies, and severe contamination level (100 - 7,000 μg/L) of antimony reported in surface and groundwater of abandoned mining area in China and Slovakia. Therefore, US EPA regulated maximum contaminants level of antimony in drinking water to 6 μg/L. In order to remove anionic contaminants in drinking water, various type of nanomaterials have been developed. Layered double hydroxide (LDH) is the artificial anionic clay that is based on the layered structure of positively charged brucite-like layers with interlayers of anions. The LDH is one of the promising nanomaterials for the removal of anionic contaminants because it has high selectivity for arsenic, phosphate, chromium and antimony. However, the biggest problem of LDH for wastewater treatment is that the particles cannot be easily separated after the removal of contaminants. In this study, magnetic nanoparticles (γ-Fe2O3) supported LDH nanocomposite (γ-Fe2O3/LDH) was investigated to enhance magnetic particle recovery and removal efficiency for arsenic and antimony. The calcined γ-Fe2O3/LDH nanocomposites synthesized by co-precipitation method, and the crystallographic properties of maghemite (γ-Fe2O3) and layered structure of LDH were confirmed by X-ray diffraction. The nano-sized γ-Fe2O3 (30 to 50 nm) was stably attached on the surface of LDH (100 to 150 nm) and O1s spectrum by X-ray photoelectron spectroscopy (XPS) explained that there are both physical and

  5. α-Fe2O3 supported Bi2WO6 for photocatalytic degradation of gaseous benzene

    Science.gov (United States)

    Chen, Rong; Lu, Jun; Xiao, Jun; Zhu, Chengzhu; Peng, Shuchuan; Chen, Tianhu

    2017-09-01

    The Bi2WO6/α-Fe2O3 composite photocatalyst was synthesized by using goethite as a precursor through hydrothermal-calcination method and characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), UV-Vis reflection spectrometer (DRS), X-ray photoelectron spectroscopy (XPS) and N2 adsorption-desorption measurement (BET). These results indicated that the self-made composite photocatalysts had excellent catalytic performance of degradation of gaseous benzene. When benzene initial concentration at 50 mg/m3, over the α-FeOOH/Bi2WO6 with molar mass of 0.8:1, calcined at 350 °C for 2 h and the pH of precursor solution was 3, the benzene degradation rate reached 71.9% and the mineralization efficiency reached 67.7% after 220 min UV irradiation, respectively. The h+ and rad O2- generated in the photocatalytic system should be played a pivotal role for the enhanced photodegradation performance of gaseous benzene.

  6. Characterization of bidisperse magnetorheological fluids utilizing maghemite (γ-Fe2O3) nanoparticles synthetized by flame spray pyrolysis

    Science.gov (United States)

    Jönkkäri, I.; Sorvali, M.; Huhtinen, H.; Sarlin, E.; Salminen, T.; Haapanen, J.; Mäkelä, J. M.; Vuorinen, J.

    2017-09-01

    In this study we have used liquid flame spray (LFS) process to synthetize γ-Fe2O3 nanoparticles of two different average sizes. Different sized nanoparticles were generated with two different liquid precursor feed rates in the spray process, higher feed rate resulting in larger nanoparticles with higher saturation magnetization. The nanoparticles were used in bidisperse magnetorheological fluids to substitute 5% of the micron sized carbonyl iron particles. To our knowledge this is the first time particles synthetized by the LFS method have been used in magnetorheological fluids. The bidisperse fluids showed significantly improved sedimentation stability compared to a monodisperse suspension with the same solid concentration. The tradeoff was an increased viscosity without magnetic field. The effect of the nanoparticles on the rheological properties under external magnetic field was modest. Finally, the dynamic oscillatory testing was used to evaluate the structural changes in the fluids under magnetic field. The addition of nanoparticles decreased the elastic portion of the deformation and increased the viscous portion.

  7. Excitation-wavelength-dependent small polaron trapping of photoexcited carriers in α-Fe2O3

    Science.gov (United States)

    Carneiro, Lucas M.; Cushing, Scott K.; Liu, Chong; Su, Yude; Yang, Peidong; Alivisatos, A. Paul; Leone, Stephen R.

    2017-08-01

    Small polaron formation is known to limit ground-state mobilities in metal oxide photocatalysts. However, the role of small polaron formation in the photoexcited state and how this affects the photoconversion efficiency has yet to be determined. Here, transient femtosecond extreme-ultraviolet measurements suggest that small polaron localization is responsible for the ultrafast trapping of photoexcited carriers in haematite (α-Fe2O3). Small polaron formation is evidenced by a sub-100 fs splitting of the Fe 3p core orbitals in the Fe M2,3 edge. The small polaron formation kinetics reproduces the triple-exponential relaxation frequently attributed to trap states. However, the measured spectral signature resembles only the spectral predictions of a small polaron and not the pre-edge features expected for mid-gap trap states. The small polaron formation probability, hopping radius and lifetime varies with excitation wavelength, decreasing with increasing energy in the t2g conduction band. The excitation-wavelength-dependent localization of carriers by small polaron formation is potentially a limiting factor in haematite's photoconversion efficiency.

  8. Anti-corrosion mechanism of epoxy-resin and different content Fe2O3 coatings on magnesium alloy

    Science.gov (United States)

    Jin, Tao; Kong, Fan-mei; Bai, Rui-qin; Zhang, Ru-liang

    2016-10-01

    In this study, anti-corrosion coatings were prepared and coated successfully on magnesium alloy substrates by mixing nanopowders, solvent, curing agent with epoxy resin. The effect of the amount of iron trioxide (Fe2O3) on the adhesion strength and corrosion resistance on magnesium alloy was investigated with standard protocols, and electrochemical measurements were also made in 3.5 wt.% NaCl solutions. The surface morphology and corrosion mechanism after corrosion tests was characterized using FESEM analysis. Nanoparticles in matrix acted as filler, and interstitial cross-linked spaces and other coating artifacts regions (micro cracks and voids) would all affect the anti-corrosion properties of coating. The results showed the proper powder content not only provided adhesion strength to these coatings but also improved obviously their anticorrosion. Hydrogen bound to the amine nitrogen (1N) could take part in the curing process rather than hydrogen of the amide site due to the smaller ΔG and the more stable configuration.

  9. Synthesis and characterization of biocatalytic γ-Fe2O3@SiO2 particles as recoverable bioreactors.

    Science.gov (United States)

    Vaz, A M; Serrano-Ruiz, D; Laurenti, M; Alonso-Cristobal, P; Lopez-Cabarcos, E; Rubio-Retama, J

    2014-02-01

    In this work, we present a suitable methodology to produce magnetically recoverable bioreactors based on enzymes, which are covalently attached on the surface of iron oxide@silica nanoparticles. In order to produce this system, iron oxide clusters with a mean diameter of 68 nm were covered with silica. This strategy yields spherical γ-Fe2O3@SiO2 cluster@shell nanoparticles with a mean diameter of 200 nm which present magnetic responsiveness and enhanced stability. The surface of these nanoparticles was modified into two steps with the aim to obtain carboxylic functional groups, which were activated to react with the enzyme glucose oxidase (GOx) that was thus immobilized on the surface of the nanoparticles. The objective of this chemistry at the nanoparticles interface is to produce magnetic-responsive bioreactors. The enzymatic activity was evaluated by using the recoverable bioreactors as part of an amperometric biosensor. These measurements allowed determining the stability, catalytic activity and the amount of enzyme immobilized on the surface of the nanoparticles. Furthermore, the functionalized nanoparticles can be recovered by applying an external magnetic field, which allows them to be employed in chemical processes where the recovery of the biocatalyst is important.

  10. Highly magnetic Fe2O3 nanoparticles synthesized by laser pyrolysis used for biological and heat transfer applications

    Science.gov (United States)

    Dumitrache, F.; Morjan, I.; Fleaca, C.; Badoi, A.; Manda, G.; Pop, S.; Marta, D. S.; Huminic, G.; Huminic, A.; Vekas, L.; Daia, C.; Marinica, O.; Luculescu, C.; Niculescu, A.-M.

    2015-05-01

    γFe2O3-based nanoparticles were synthesized by laser pyrolysis using various optimized Fe(CO)5, O2 and C2H4 flow ratios in the reactive mixture, and different laser power values. Depending on particular conditions, two different iron oxide-based nanoparticles (MNPs) were synthesized, with a hydrophilic or hydrophobic behavior, both presenting a high magnetization saturation (around 70 emu/g). TEM, EDX, XRD and magnetic analyses were performed for a comprehensive characterization. The raw powders were successfully dispersed in aqueous media using L-DOPA as stabilizing agent. Dispersed samples, with or without stabilization agents, have been tested and DLS measurements proved their good stability, with the hydrodynamic diameter varying between 70 and 150 nm when the stabilizing agent was used. Thermal conductivity and viscosity tests on L-DOPA-functionalized MNPs suspensions reveal the increasing (up to 40%) of their thermal conductivity, accompanied by a viscosity increase of only 5%, validating them as thermal transfer fluids. Water-based nanoparticle dispersions and also those stabilized with L-DOPA proved a good biocompatibility, as demonstrated by a preliminary in vitro study on mouse primary leukocytes and human breast carcinoma cell line MCF-7; although ingested by the investigated cells, MNPs do not decrease cellular viability and proliferation.

  11. A new model and gas sensitivity of non-equilibrium xSnO2-(1-x)alpha-Fe2O3 nanopowders prepared by mechanical alloying

    DEFF Research Database (Denmark)

    Zhu, W.; Tan, O.K.; Jiang, Jianzhong

    1998-01-01

    )alpha-Fe2O3 materials. This model can explain non only the lattice expansion of the milled samples, but also takes into account the charge balance by adding oxygen dangling bonds at the particle surfaces, which can be visualized in the nano-sized powders. The thich film gas sensors made by such mechanically......Nano-sized xSnO2-(1-x)alpha-Fe2O3 materials have been prepared using the high energy ball milling technique and their structural and gas sensing properties have been characterized. Based on experimental results, we propose a new structure model, xxx, forthese non-equilibrium, nano-sized xSnO2-(1-x...... alloyed materials have high ethanol gas sensitivity values of 289 in air and 1016 in nitrogen at 1000 p.p.m. and very good gas selectivity to ethanol over CO and H2 gases. It is believed that the high ethanol gas sensitivity of these materials is related to the enormous defects such as O- and O2- dangling...

  12. Influence of magnetoplasmonic γ-Fe2O3/Au core/shell nanoparticles on low-field nuclear magnetic resonance

    Science.gov (United States)

    Chen, Kuen-Lin; Yeh, Yao-Wei; Chen, Jian-Ming; Hong, Yu-Jie; Huang, Tsung-Lin; Deng, Zu-Yin; Wu, Chiu-Hsien; Liao, Su-Hsien; Wang, Li-Min

    2016-01-01

    Magnetoplasmonic nanoparticles, composed of a plasmonic layer and a magnetic core, have been widely shown as promising contrast agents for magnetic resonance imaging (MRI) applications. However, their application in low-field nuclear magnetic resonance (LFNMR) research remains scarce. Here we synthesised γ-Fe2O3/Au core/shell (γ-Fe2O3@Au) nanoparticles and subsequently used them in a homemade, high-Tc, superconducting quantum interference device (SQUID) LFNMR system. Remarkably, we found that both the proton spin–lattice relaxation time (T1) and proton spin–spin relaxation time (T2) were influenced by the presence of γ-Fe2O3@Au nanoparticles. Unlike the spin–spin relaxation rate (1/T2), the spin–lattice relaxation rate (1/T1) was found to be further enhanced upon exposing the γ-Fe2O3@Au nanoparticles to 532 nm light during NMR measurements. We showed that the photothermal effect of the plasmonic gold layer after absorbing light energy was responsible for the observed change in T1. This result reveals a promising method to actively control the contrast of T1 and T2 in low-field (LF) MRI applications. PMID:27752101

  13. High performance of nanoscaled Fe2O3 catalyzing UV-Fenton under neutral condition with a low stoichiometry of H2O2: Kinetic study and mechanism

    DEFF Research Database (Denmark)

    Wang, Yong; Sun, Yunkai; Li, Weiguang

    2015-01-01

    Kinetics and mechanism of nano-Fe2O3 catalyzing UV-Fenton were investigated in this study with catechol as model pollutant. This type of heterogeneous UV-Fenton was proven to be characteristic of a wide pH range from mildly acidic to slightly alkaline and low H2O2 requirement accompanied with H2O...

  14. Effect of Fe2O3 on the crystallization behavior of glass-ceramics produced from naturally cooled yellow phosphorus furnace slag

    Science.gov (United States)

    Liu, Hong-pan; Huang, Xiao-feng; Ma, Li-ping; Chen, Dan-li; Shang, Zhi-biao; Jiang, Ming

    2017-03-01

    CaO-Al2O3-SiO2 (CAS) glass-ceramics were prepared via a melting method using naturally cooled yellow phosphorus furnace slag as the main raw material. The effects of the addition of Fe2O3 on the crystallization behavior and properties of the prepared glass-ceramics were studied by differential thermal analysis, X-ray diffraction, and scanning electron microscopy. The crystallization activation energy was calculated using the modified Johnson-Mehl-Avrami equation. The results show that the intrinsic nucleating agent in the yellow phosphorus furnace slag could effectively promote the crystallization of CAS. The crystallization activation energy first increased and then decreased with increasing amount of added Fe2O3. At 4wt% of added Fe2O3, the crystallization activation energy reached a maximum of 676.374 kJ·mol-1. The type of the main crystalline phase did not change with the amount of added Fe2O3. The primary and secondary crystalline phases were identified as wollastonite (CaSiO3) and hedenbergite (CaFe(Si2O6)), respectively.

  15. A general approach to fabricate diverse noble-metal (Au, Pt, Ag, Pt/Au)/Fe2O3 hybrid nanomaterials.

    Science.gov (United States)

    Zhang, Jun; Liu, Xianghong; Guo, Xianzhi; Wu, Shihua; Wang, Shurong

    2010-07-19

    A novel, facile, and general one-pot strategy is explored for the synthesis of diverse noble-metal (Au, Pt, Ag, or Pt/Au)/Fe(2)O(3) hybrid nanoparticles with the assistance of lysine (which is a nontoxic, user friendly amino acid that is compatible with organisms) and without using any other functionalization reagents. Control experiments show that lysine, which contains both amino and carboxylic groups, plays dual and crucial roles as both linker and capping agents in attaching noble metals with a small size and uniform distribution onto an Fe(2)O(3) support. Considering the perfect compatibility of lysine with organism, this approach may find potentials in biochemistry and biological applications. Furthermore, this novel route is also an attractive alternative and supplement to the current methods using a silane coupling agent or polyelectrolyte for preparing hybrid nanomaterials. To demonstrate the usage of such hybrid nanomaterials, a chemical gas sensor has been fabricated from the as-synthesized Au/Fe(2)O(3) nanoparticles and investigated for ethanol detection. Results show that the hybrid sensor exhibits significantly improved sensor performances in terms of high sensitivity, low detection limit, better selectivity, and good reproducibility in comparison with pristine Fe(2)O(3). Most importantly, this general approach can be further employed to fabricate other hybrid nanomaterials based on different support materials.

  16. Removal of methylene blue and mechanism on magnetic γ-Fe2O3/SiO2 nanocomposite from aqueous solution

    Directory of Open Access Journals (Sweden)

    Dong Chen

    2016-09-01

    Full Text Available Magnetic γ-Fe2O3/SiO2 (M-γFS nanocomposite was prepared using γ-Fe2O3 as the magnetic carriers. M-γFS was characterized by transmission electron microscope (TEM, X-ray diffraction (XRD, and Fourier Transform infrared spectroscopy (FTIR. The characterizations of M-γFS exhibit the irregular core-shell structure, and SiO2 has been successfully coated on the surface of γ-Fe2O3. M-γFS has much higher adsorption capacity 116.09 mg/g calculated by coated SiO2 on M-γFS than γ-Fe2O3 and SiO2, and the alkaline conditions are beneficial to the adsorption of MB. Coexisting cations, ionic strength and humic acid can influence the adsorption capacity. Meanwhile, adsorption kinetics data for M-γFS show good fit to the pseudo-second-order kinetics model, and the Langmuir equation is more appropriate to describe the adsorption behavior of MB on M-γFS. Moreover, after recycling four times, M-γFS washed by ethanol can still keep high adsorption capacity for MB adsorption.

  17. [Single Fe(2)O(3)-PLL labeled mouse spleen-derived endothelial progenitor cell detection by 7.0T MR system].

    Science.gov (United States)

    Jia, Zhen-Yu; Chen, Jun; Teng, Gao-Jun

    2010-02-01

    To explore the feasibility of Single Fe(2)O(3)-PLL labeled mouse spleen-derived endothelial progenitor cells (EPCs) detection by 7.0T MR system. Mononuclear cells (MNCs) were isolated from mouse spleen by density gradient centrifugation and EPCs were obtained by the different adherence of cells.Immunocytochemistry and fluorescent staining were performed to identify EPCs. The EPCs were labeled with Fe(2)O(3)-PLL and the intracellular iron was identified with prussian blue staining. MTT assay was assessed to evaluate proliferation of Fe(2)O(3)-PLL labeled EPCs. The cells underwent MR imaging with different sequences. Cultured in vitro, mouse spleen-derived MNCs resulted in EC-like morphology. These cells expressed EPCs-specific antigens, such as CD31, CD34 and vWF, and had the ability to incorporate ac-LDL and bind UEA-1. Between Fe(2)O(3)-PLL labeled EPCs and unlabeled cells, MTT value of light absorption had no statistical significant difference (day4 t = 2.81, day5 t = -1.87, day6 t = -0.298, day7 t = -0.115, all P > 0.05). The signal void induced by labeled single cell is 20.2 pixels in MSME sequence, and 20.2 pixels in 3D-FLASH sequence (t = 15.2, P PLL efficiently. The labeled EPCs can be imaged as dispersed single cells.

  18. Preparation and Application of a Nano α-Fe2O3/SAPO-34 Photocatalyst for Removal of the Anti-cancer Drug Doxorubicin using the Taguchi Approach

    Directory of Open Access Journals (Sweden)

    Bigtan Mohammad Hosein

    2016-01-01

    Full Text Available The synthesis of α-Fe2O3/SAPO-34 nano photocatalyst was the first step of this study. The α-Fe2O3 nanocatalyst was synthesized applying forced hydrolysis and reflux condensation followed by solid-state dispersion that was used for supporting α-Fe2O3 on SAPO-34. The next step was a characterization of the catalyst that was performed using X-ray diffraction (XRD, scanning electron microscopy (SEM and Fourier Transform Infrared Spectroscopy (FT-IR. Then, for optimizing the operational parameters in Doxorubicin’s degradation process the effect of Doxorubicin concentration, the amount of α-Fe2O3/SAPO-34 nano photocatalyst, the pH, and H2O2 concentration was studied via the Taguchi method. The AL9 orthogonal array was adjusted and nine crucial runs were conducted. For calculating Signal/Noise ratio, each run was repeated three times. As the results showed, the concentration of Doxorubicin is the most effective parameter. Optimized conditions for removing the anti-cancer drug (based on Signal/Noise ratio were Doxorubicin concentration (20 ppm, H2O2 concentration (3 mol/L, catalyst amount (50 mg/L and pH = 8.

  19. Preparation of Hollow Fe2O3 Nanorods and Nanospheres by Nanoscale Kirkendall Diffusion, and Their Electrochemical Properties for Use in Lithium-Ion Batteries

    Science.gov (United States)

    Cho, Jung Sang; Park, Jin-Sung; Kang, Yun Chan

    2016-12-01

    A novel process for the preparation of aggregate-free metal oxide nanopowders with spherical (0D) and non-spherical (1D) hollow nanostructures was introduced. Carbon nanofibers embedded with iron selenide (FeSe) nanopowders with various nanostructures are prepared via the selenization of electrospun nanofibers. Ostwald ripening occurs during the selenization process, resulting in the formation of a FeSe-C composite nanofiber exhibiting a hierarchical structure. These nanofibers transform into aggregate-free hollow Fe2O3 powders via the complete oxidation of FeSe and combustion of carbon. Indeed, the zero- (0D) and one-dimensional (1D) FeSe nanocrystals transform into the hollow-structured Fe2O3 nanopowders via a nanoscale Kirkendall diffusion process, thus conserving their overall morphology. The discharge capacities for the 1000th cycle of the hollow-structured Fe2O3 nanopowders obtained from the FeSe-C composite nanofibers prepared at selenization temperatures of 500, 800, and 1000 °C at a current density of 1 A g‑1 are 932, 767, and 544 mA h g‑1, respectively; and their capacity retentions from the second cycle are 88, 92, and 78%, respectively. The high structural stabilities of these hollow Fe2O3 nanopowders during repeated lithium insertion/desertion processes result in superior lithium-ion storage performances.

  20. In Situ Grown Fe2O3 Single Crystallites on Reduced Graphene Oxide Nanosheets as High Performance Conversion Anode for Sodium-Ion Batteries.

    Science.gov (United States)

    Li, Ting; Qin, Aiqiong; Yang, Lanlan; Chen, Jie; Wang, Qiufan; Zhang, Daohong; Yang, Hanxi

    2017-06-14

    Electrochemical conversion reactions of metal oxides provide a new avenue to build high capacity anodes for sodium-ion batteries. However, the poor rate performance and cyclability of these conversion anodes remain a significant challenge for Na-ion battery applications because most of the conversion anodes suffer from sluggish kinetics and irreversible structural change during cycles. In this paper, we report an Fe2O3 single crystallites/reduced graphene oxide composite (Fe2O3/rGO), where the Fe2O3 single crystallites with a particle size of ∼300 nm were uniformly anchored on the rGO nanosheets, which provide a highly conductive framework to facilitate electron transport and a flexible matrix to buffer the volume change of the material during cycling. This Fe2O3/rGO composite anode shows a very high reversible capacity of 610 mAh g(-1) at 50 mA g(-1), a high Coulombic efficiency of 71% at the first cycle, and a strong cyclability with 82% capacity retention after 100 cycles, suggesting a potential feasibility for sodium-ion batteries. More significantly, the present work clearly illustrates that an electrochemical conversion anode can be made with high capacity utilization, strong rate capability, and stable cyclability through appropriately tailoring the lattice structure, particle size, and electronic conduction channels for a simple transition-metal oxide, thus offering abundant selections for development of low-cost and high-performance Na-storage electrodes.

  1. Nanostructure and Volatile Organic Compounds Sensing Properties of α-Fe2O3/Reduced Graphene Oxide Nanocomposite Derived by Spray Method

    Science.gov (United States)

    Zolghadr, S.; Kimiagar, S.; Khojier, K.

    2017-08-01

    This paper investigates the α-Fe2O3/reduced graphene oxide (rGO) nanocomposite as a volatile organic compounds (VOCs) sensor. The α-Fe2O3/reduced graphene oxide nanocomposites of about 370 nm thickness were synthesized by a spray method with different rGO contents (3%, 4%, and 5%) on SiO2/Si substrates. The samples were structurally and morphologically characterized by x-ray diffraction, and field emission scanning electron microscopy. These analyses showed that an increase in rGO content decreases the crystallinity of the samples. In order to study the VOCs sensing properties, the sensitivity and selectivity of the samples were tested with different VOCs vapors including ethanol, methanol, toluene, benzene, and formic acid in the temperature range of 200-400°C. The results show that the α-Fe2O3/rGO nanocomposites are more selective to ethanol than the other vapors, while an increase in rGO content decreases the sensitivity of the samples. The α-Fe2O3/rGO (3%)-based ethanol sensor also shows a good stability with respect to relative humidity in the range of 20-50% with a 1-ppm detection limit at the operating temperature of 280°C.

  2. Porous Fe2O3 Nanoframeworks Encapsulated within Three-Dimensional Graphene as High-Performance Flexible Anode for Lithium-Ion Battery.

    Science.gov (United States)

    Jiang, Tiancai; Bu, Fanxing; Feng, Xiaoxiang; Shakir, Imran; Hao, Guolin; Xu, Yuxi

    2017-05-23

    Integrating nanoscale porous metal oxides into three-dimensional graphene (3DG) with encapsulated structure is a promising route but remains challenging to develop high-performance electrodes for lithium-ion battery. Herein, we design 3DG/metal organic framework composite by an excessive metal-ion-induced combination and spatially confined Ostwald ripening strategy, which can be transformed into 3DG/Fe2O3 aerogel with porous Fe2O3 nanoframeworks well encapsulated within graphene. The hierarchical structure offers highly interpenetrated porous conductive network and intimate contact between graphene and porous Fe2O3 as well as abundant stress buffer nanospace for effective charge transport and robust structural stability during electrochemical processes. The obtained free-standing 3DG/Fe2O3 aerogel was directly used as highly flexible anode upon mechanical pressing for lithium-ion battery and showed an ultrahigh capacity of 1129 mAh/g at 0.2 A/g after 130 cycles and outstanding cycling stability with a capacity retention of 98% after 1200 cycles at 5 A/g, which is the best results that have been reported so far. This study offers a promising route to greatly enhance the electrochemical properties of metal oxides and provides suggestive insights for developing high-performance electrode materials for electrochemical energy storage.

  3. Chitosan-mediated synthesis of mesoporous α-Fe2O3 nanoparticles and their applications in catalyzing selective oxidation of cyclohexane

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    This paper reports the chitosan-mediated synthesis of porous hematite nanoparticles with FeCl3 as the precursor via a hydrothermal approach at 160℃.A series of porous chitosan/iron oxide hybrid nanoparticles were obtained via changing the ratio of chitosan to FeCl3,FeCl3 concentration and pH value of the reaction solution,and producing porous iron oxide nanoparticles after calcination.The as-prepared samples were characterized by means of X-ray diffraction,transmission electron microscopy,thermal gravimetric analysis,Fourier transform infrared,and N2 sorption.The particle sizes of these metal oxides were less than 100 nm,and the pore sizes were in the range of 2-16 nm.It was demonstrated that chitosan played a key role in the formation of the porous structures.The resultant α-Fe2O3 nanoparticles were used as the support to immobilize Au or Pd nanoparticles,producing Au/α-Fe2O3 or Pd/α-Fe2O3 nanoparticles.The as-prepared α-Fe2O3 nanocatalyst exhibited high selectivity towards cyclohexanone and cyclohexanol for catalyzing cyclohexane oxidation with O2 at 150℃.

  4. Controllable Synthesis of TiO2@Fe2O3 Core-Shell Nanotube Arrays with Double-Wall Coating as Superb Lithium-Ion Battery Anodes

    Science.gov (United States)

    Zhong, Yan; Ma, Yifan; Guo, Qiubo; Liu, Jiaqi; Wang, Yadong; Yang, Mei; Xia, Hui

    2017-01-01

    Highlighted by the safe operation and stable performances, titanium oxides (TiO2) are deemed as promising candidates for next generation lithium-ion batteries (LIBs). However, the pervasively low capacity is casting shadow on desirable electrochemical behaviors and obscuring their practical applications. In this work, we reported a unique template-assisted and two-step atomic layer deposition (ALD) method to achieve TiO2@Fe2O3 core-shell nanotube arrays with hollow interior and double-wall coating. The as-prepared architecture combines both merits of the high specific capacity of Fe2O3 and structural stability of TiO2 backbone. Owing to the nanotubular structural advantages integrating facile strain relaxation as well as rapid ion and electron transport, the TiO2@Fe2O3 nanotube arrays with a high mass loading of Fe2O3 attained desirable capacity of ~520 mA h g‑1, exhibiting both good rate capability under uprated current density of 10 A g‑1 and especially enhanced cycle stability (~450 mA h g‑1 after 600 cycles), outclassing most reported TiO2@metal oxide composites. The results not only provide a new avenue for hybrid core-shell nanotube formation, but also offer an insight for rational design of advanced electrode materials for LIBs.

  5. High Efficient Photo-Fenton Catalyst of α-Fe2O3/MoS2 Hierarchical Nanoheterostructures: Reutilization for Supercapacitors

    Science.gov (United States)

    Yang, Xijia; Sun, Haiming; Zhang, Lishu; Zhao, Lijun; Lian, Jianshe; Jiang, Qing

    2016-08-01

    A novel three-dimensional (3D) α-Fe2O3/MoS2 hierarchical nanoheterostructure is effectively synthesized via a facile hydrothermal method. The zero-dimensional (0D) Fe2O3 nanoparticles guide the growth of two-dimensional (2D) MoS2 nanosheets and formed 3D flower-like structures, while MoS2 facilitates the good dispersion of porous Fe2O3 with abundant oxygen vacancies. This charming 3D-structure with perfect match of non-equal dimension exhibits high recyclable photo-Fenton catalytic activity for Methyl orange pollutant and nice specific capacity in reusing as supercapacitor after catalysis. The synergistic effect between Fe2O3 and MoS2, the intermediate nanointerfaces, the 3D porous structures, and the abundant oxygen vacancies both contribute to highly active catalysis, nice electrochemical performance and stable cycling. This strategy is simple, cheap, and feasible for maximizing the value of the materials, as well as eliminating the secondary pollution.

  6. Controllable Synthesis of TiO2@Fe2O3 Core-Shell Nanotube Arrays with Double-Wall Coating as Superb Lithium-Ion Battery Anodes

    Science.gov (United States)

    Zhong, Yan; Ma, Yifan; Guo, Qiubo; Liu, Jiaqi; Wang, Yadong; Yang, Mei; Xia, Hui

    2017-01-01

    Highlighted by the safe operation and stable performances, titanium oxides (TiO2) are deemed as promising candidates for next generation lithium-ion batteries (LIBs). However, the pervasively low capacity is casting shadow on desirable electrochemical behaviors and obscuring their practical applications. In this work, we reported a unique template-assisted and two-step atomic layer deposition (ALD) method to achieve TiO2@Fe2O3 core-shell nanotube arrays with hollow interior and double-wall coating. The as-prepared architecture combines both merits of the high specific capacity of Fe2O3 and structural stability of TiO2 backbone. Owing to the nanotubular structural advantages integrating facile strain relaxation as well as rapid ion and electron transport, the TiO2@Fe2O3 nanotube arrays with a high mass loading of Fe2O3 attained desirable capacity of ~520 mA h g−1, exhibiting both good rate capability under uprated current density of 10 A g−1 and especially enhanced cycle stability (~450 mA h g−1 after 600 cycles), outclassing most reported TiO2@metal oxide composites. The results not only provide a new avenue for hybrid core-shell nanotube formation, but also offer an insight for rational design of advanced electrode materials for LIBs. PMID:28098237

  7. Ex situ synthesis of G/$\\alpha$-Fe$_2$O$_3$ nanocomposite and its catalytic effect on the thermal decomposition of ammonium perchlorate

    Indian Academy of Sciences (India)

    MERIEM AMINA FERTASSI; QI LIU; RUNZE LI; PINGAN LIU; JINGYUAN LIU; RONG-RONG CHEN; LIANHE LIU; JUN WANG

    2017-08-01

    $\\alpha$-Fe$_2$O$_3$ nanoparticles were prepared by a facile hydrothermal method using ferric chloride hexahydrate(FeCl$_3$·6H$_2$O) as a precursor. Graphene oxide (GO) was synthesized using a modified Hummers method and graphenenanosheets (G) were successfully obtained by thermal reduction of GO. G/$\\alpha$-Fe$_2$O$_3$ nanocomposite was prepared using ex situ synthesis in the presence of $\\alpha$-Fe$_2$O$_3$ nanoparticles and GO solution. The characterization of the as-prepared materialswas performed using X-ray diffraction analyses and Fourier transform infrared spectroscopy; their morphology wasinvestigated by scanning electron microscopy and transmission electron microscopy; the specific surface area (SBET) wasdetermined by nitrogen adsorption; their catalytic activity on the thermal decomposition of ammonium perchlorate (AP) wasinvestigated by differential thermal analysis (DTA). The results of DTA indicated that the obtained nanomaterials contributein ameliorating the thermal decomposition of AP; specifically, the high decomposition temperature of AP decreases from432 to 380$^{\\circ}$C. A significant decrease in the activation energy was also achieved in the presence of these nanomaterials, and the mixture of ammonium perchlorate with G/$\\alpha$-Fe$_2$O$_3$ showed the lowest value (from 129 to 80.33 kJ mol$^{−1}$).

  8. Structural and photoelectrochemical properties of porous TiO2 nanofibers decorated with Fe2O3 by sol-flame

    Science.gov (United States)

    Sobti, N.; Bensouici, A.; Coloma, F.; Untiedt, C.; Achour, S.

    2014-08-01

    The hybrid structure of Fe2O3 nanoparticles/TiO2 nanofibers (NFs), combines the merits of large surface areas of TiO2 NFs and absorption in ultraviolet light-visible light range. This structure can be used for many applications such as photoelectrochemical water splitting and photo-catalysis. Here, a sol-flame method is used for depositing Fe2O3 on TiO2 NFs that were prepared by hydrothermal on Ti sheets. The obtained materials were characterized by XRD, SEM, UV/Vis diffuse reflectance, Raman, and XPS. The results revealed the formation of rutile and anatase crystalline phases together with Fe2O3. This process moves the absorption threshold of TiO2 NFs support into visible spectrum range and enhances the photocurrent in comparison to bare TiO2 NFs, although no hole scavenger was used. The impedance measurement at low and high frequencies revealed an increase in series resistance and a decrease in resistance of charge transfer with sol-flame treatment time. A mechanism for explaining the charge transfer in these TiO2 NFs decorated with Fe2O3 nanoparticles was proposed.

  9. High saturation magnetization of γ-Fe2O3 nano-particles by a facile one-step synthesis approach

    Science.gov (United States)

    Cao, Derang; Li, Hao; Pan, Lining; Li, Jianan; Wang, Xicheng; Jing, Panpan; Cheng, Xiaohong; Wang, Wenjie; Wang, Jianbo; Liu, Qingfang

    2016-09-01

    We have demonstrated the synthesis of γ-Fe2O3 nano-particles through a facile and novel calcination process in the air. There is no pH regulation, gas atmosphere, additive, centrifugation or other complicated procedures during the preparing process. A detailed formation process of the nano-particles is proposed, and DMF as a polar solvent may slower the reaction process of calcination. The structures, morphologies, and magnetic properties of γ-Fe2O3 nano-particles were investigated systematically, and the pure γ-Fe2O3 nano-particles obtained at 200 °C display uniform morphology good magnetic property. The saturation magnetization of obtained pure γ-Fe2O3 is about 74 emu/g, which is comparable with bulk material (76 emu/g) and larger than other results. In addition, the photocatalytic activity for degradation of methylene blue is also studied, which shows proper photocatalytic activity.

  10. X-Ray Magnetic Dichroism of Antiferromagnet Fe2O3 : The Orientation of Magnetic Moments Observed by Fe 2p X-Ray Absorption Spectroscopy

    NARCIS (Netherlands)

    Kuiper, Pieter; Searle, Barry G.; Rudolf, Petra; Tjeng, L.H.; Chen, C.T.

    1993-01-01

    We report strong magnetic linear dichroism at the Fe L2,3 edge of the antiferromagnet Fe2O3 (hematite). The relative difference in absorption for light polarized parallel and perpendicular to the magnetic moment is as high as 40% at the Fe L2 edge. The spectra are in excellent agreement with

  11. A multi-layered Fe2O3/graphene composite with mesopores as a catalyst for rechargeable aprotic lithium-oxygen batteries

    Science.gov (United States)

    Feng, Ningning; Mu, Xiaowei; Zheng, Mingbo; Wang, Chaoqiang; Lin, Zixia; Zhang, Xueping; Shi, Yi; He, Ping; Zhou, Haoshen

    2016-09-01

    Aprotic Li-O2 batteries have attracted a huge amount of interest in the past decade owing to their extremely high energy density. However, identifying a desirable cathodic catalyst for this promising battery system is one of the biggest challenges at present. In this work, a multi-layered Fe2O3/graphene nanosheets (Fe2O3/GNS) composite with sandwich structure was synthesized using an easy thermal casting method, and served as a cathodic catalyst for aprotic Li-O2 batteries. The aprotic Li-O2 cell with the Fe2O3/GNS catalyst demonstrated a better reversibility, lower overpotential for oxygen evolution, and a higher Coulombic efficiency (close to 100%) than those of pure GNS. An excellent rate performance and good cycle stability were also confirmed. The results, characterized by ex and in situ methods, revealed that the dominant discharge product Li2O2 was decomposed below 4.35 V. This superior electrochemical performance is mainly attributed to the unique sandwich structure of the Fe2O3/GNS catalyst with mesopores, which can provide substantially more catalytic sites and prevent direct contact between carbon and Li2O2.

  12. Field emission from α-Fe2O3 nanoflakes: Effect of vacuum pressure, gas adsorption and in-situ thermal treatment

    Science.gov (United States)

    Wu, J. Q.; Deng, S. Z.; Xu, N. S.; Chen, Jun

    2014-02-01

    The effects of vacuum pressure and gas adsorption on field emission current of α-Fe2O3 nanoflakes were studied. It was found that field emission current of α-Fe2O3 nanoflakes decreased with increasing pressure. The field emission current decreased when N2 or O2 was introduced into chamber, while no obvious change was observed for H2 gas. An in-situ thermal treatment was carried out to eradicate the effect of absorbed gas. After the in-situ thermal treatment, the field emission current density was largely enhanced from 60 to 500 μA/cm2 under applied electrical field of 10 MV/m and the turn on field (Eturn-on) decreased from 7.6 to 5.2 MV/m. The lowered turn-on field was attributed to the decrease of surface work function induced by surface gas desorption and reduction of α-Fe2O3 nanoflakes. Moreover, the improvement of field emission performance can be retained in high vacuum condition, which indicates the in-situ thermal treatment is an efficient method to improve field emission properties of α-Fe2O3 nanoflakes.

  13. Adsorption Performance of Methyl Violet via α-Fe2O3@Porous Hollow Carbonaceous Microspheres and Its Effective Regeneration through a Fenton-Like Reaction

    Directory of Open Access Journals (Sweden)

    Zhiqing Tong

    2016-04-01

    Full Text Available α-Fe2O3@porous hollow carbonaceous microspheres (α-Fe2O3@PHCMs were prepared through a combination of hydrothermal and calcination method. The novel α-Fe2O3@PHCMs integrated the adsorptive and catalytic performances and served as an inexpensive adsorbent to rapidly remove cationic dye (methyl violet (MV from aqueous solution. Equilibrium studies indicated that the dye molecules obeyed Langmuir type of adsorption with the calculated maximum adsorption capacity of 539.8 mg∙g−1 at 313.15 K. Kinetic data were better described by pseudo-second-order model and the thermodynamic studies illustrated that MV adsorption onto the composite was spontaneous, endothermic and occurred by physisorption. The Fenton-like process was found to be effective for the regeneration of the spent α-Fe2O3@PHCMs. The regeneration efficiency, as high as 88.0%, was still maintained after three consecutive adsorption-regeneration cycles. FTIR and XRD characterizations of the composite before and after adsorption-regeneration treatment showed that the Fenton-like process did not cause serious damage to the structure of composites.

  14. Fabrication of γ-Fe2O3 Nanoparticles by Solid-State Thermolysis of a Metal-Organic Framework, MIL-100(Fe, for Heavy Metal Ions Removal

    Directory of Open Access Journals (Sweden)

    Shengtao Hei

    2014-01-01

    Full Text Available Porous γ-Fe2O3 nanoparticles were prepared via a solid-state conversion process of a mesoporous iron(III carboxylate crystal, MIL-100(Fe. First, the MIL-100(Fe crystal that served as the template of the metal oxide was synthesized by a low-temperature (<100°C synthesis route. Subsequently, the porous γ-Fe2O3 nanoparticles were fabricated by facile thermolysis of the MIL-100(Fe powders via a two-step calcination treatment. The obtained γ-Fe2O3 was characterized by X-ray diffraction (XRD, N2 adsorption, X-ray photoelectron spectroscopy (XPS, and scanning electron microscopy (SEM techniques, and then used as an adsorbent for heavy metal ions removal in water treatment. This study illustrates that the metal-organic frameworks may be suitable precursors for the fabrication of metal oxides nanomaterials with large specific surface area, and the prepared porous γ-Fe2O3 exhibits a superior adsorption performance for As(V and As(III ions removal in water treatment.

  15. Three-dimensional core-shell Fe2O3 @ carbon/carbon cloth as binder-free anode for the high-performance lithium-ion batteries

    Science.gov (United States)

    Wang, Xiaohua; Zhang, Miao; Liu, Enzuo; He, Fang; Shi, Chunsheng; He, Chunnian; Li, Jiajun; Zhao, Naiqin

    2016-12-01

    A facile and scalable strategy is developed to fabricate three dimensional core-shell Fe2O3 @ carbon/carbon cloth structure by simple hydrothermal route as binder-free lithium-ion battery anode. In the unique structure, carbon coated Fe2O3 nanorods uniformly disperse on carbon cloth which forms the conductive carbon network. The hierarchical porous Fe2O3 nanorods in situ grown on the carbon cloth can effectively shorten the transfer paths of lithium ions and reduce the contact resistance. The carbon coating significantly inhibits pulverization of active materials during the repeated Li-ion insertion/extraction, as well as the direct exposure of Fe2O3 to the electrolyte. Benefiting from the structural integrity and flexibility, the nanocomposites used as binder-free anode for lithium-ion batteries, demonstrate high reversible capacity and excellent cyclability. Moreover, this kind of material represents an alternative promising candidate for flexible, cost-effective, and binder-free energy storage devices.

  16. Electrochemical performance and structure evolution of core-shell nano-ring α-Fe2O3@Carbon anodes for lithium-ion batteries

    Science.gov (United States)

    Sun, Yan-Hui; Liu, Shan; Zhou, Feng-Chen; Nan, Jun-Min

    2016-12-01

    Core-shell nano-ring α-Fe2O3@Carbon (CSNR) composites with different carbon content (CSNR-5%C and CSNR-13%C) are synthesized using a hydrothermal method by controlling different amounts of glucose and α-Fe2O3 nano-rings with further annealing. The CSNR electrodes exhibit much improved specific capacity, cycling stability and rate capability compared with that of bare nano-ring α-Fe2O3 (BNR), which is attributed to the core-shell nano-ring structure of CSNR. The carbon shell in the inner and outer surface of CSNR composite can increase electron conductivity of the electrode and inhibit the volume change of α-Fe2O3 during discharge/charge processes, and the nano-ring structure of CSNR can buffer the volume change too. The CSNR-5%C electrode shows super high initial discharge/charge capacities of 1570/1220 mAh g-1 and retains 920/897 mAh g-1 after 200 cycles at 500 mA g-1 (0.5C). Even at 2000 mA g-1 (2C), the electrode delivers the initial capacities of 1400/900 mAh g-1, and still maintains 630/610 mAh g-1 after 200 cycles. The core-shell nano-rings opened during cycling and rebuilt a new flower-like structure consisting of α-Fe2O3@Carbon nano-sheets. The space among the nano-sheet networks can further buffer the volume expansion of α-Fe2O3 and facilitate the transportation of electrons and Li+ ions during the charge/discharge processes, which increases the capacity and rate capability of the electrode. It is the first time that the evolution of core-shell α-Fe2O3@Carbon changing to flower-like networks during lithiation/de-lithiation has been reported.

  17. Ceramic Composite Thin Films

    Science.gov (United States)

    Ruoff, Rodney S. (Inventor); Stankovich, Sasha (Inventor); Dikin, Dmitriy A. (Inventor); Nguyen, SonBinh T. (Inventor)

    2013-01-01

    A ceramic composite thin film or layer includes individual graphene oxide and/or electrically conductive graphene sheets dispersed in a ceramic (e.g. silica) matrix. The thin film or layer can be electrically conductive film or layer depending the amount of graphene sheets present. The composite films or layers are transparent, chemically inert and compatible with both glass and hydrophilic SiOx/silicon substrates. The composite film or layer can be produced by making a suspension of graphene oxide sheet fragments, introducing a silica-precursor or silica to the suspension to form a sol, depositing the sol on a substrate as thin film or layer, at least partially reducing the graphene oxide sheets to conductive graphene sheets, and thermally consolidating the thin film or layer to form a silica matrix in which the graphene oxide and/or graphene sheets are dispersed.

  18. The magneto-optical behaviors modulated by unaggregated system for γ-Fe2O3–ZnFe2O4 binary ferrofluids

    Directory of Open Access Journals (Sweden)

    Jian Li

    2012-12-01

    Full Text Available Under an external magnetic field, when circularly polarized light was transmitted through binary ferrofluids based on strongly magnetic γ-Fe2O3 and weakly magnetic ZnFe2O4 nanoparticles, the birefringence Δn and dichroism Δk arising from the chains of γ-Fe2O3 particles system were modulated and decreased by the unchained ZnFe2O4 particles. In our experiments, we used two types of ZnFe2O4 nanoparticles: one consisted of ZnFe2O4(1 particles with higher moments, and the other consisted of ZnFe2O4(2 particles with lower moments. Comparing the birefringence and dichroism of the γ-Fe2O3–ZnFe2O4(1 and γ-Fe2O3–ZnFe2O4(2 binary ferrofluids, it was found that the modulating action of the ZnFe2O4(2 particle system with lower moments was larger than that of the ZnFe2O4(1 particle system with higher moments. Using a model for a bi-dispersed system based on chained and unchained particles, the behavior of the modulating action was explained by an additional effective relative magnetic permeability, which depends on the background of the unchained ZnFe2O4 particles for the chained γ-Fe2O3 particles and a field-induced demixing phase transition. These results showed that for binary ferrofluids based on both strong and weak magnetic nanoparticles, the power of the modulation of the magneto-optical effects depends on the difference in magnetization between the particles.

  19. Relationship between lymphocyte DNA fragmentation and dose of iron oxide (Fe2O3) and silicon oxide (SiO2) nanoparticles.

    Science.gov (United States)

    Jiménez-Villarreal, J; Rivas-Armendáriz, D I; Arellano Pérez-Vertti, R D; Olivas Calderón, E; García-Garza, R; Betancourt-Martínez, N D; Serrano-Gallardo, L B; Morán-Martínez, J

    2017-02-08

    At present, the use of nanoparticles is a controversial topic, especially when analyzing their effects in human tissues. Nanoparticles (NPs) can cause oxidative stress by increasing membrane lipids peroxidation and reactive oxygen species, and decreasing intracellular glutathione. Oxidative stress plays an important role in cell signaling and inflammatory responses. It can result in genotoxicity, affect cell proliferation, and induce DNA damage. The objective of this study is to evaluate the genotoxic potential of NPs in lymphocyte DNA. Wistar female rats (N = 45) were sorted in three randomized groups as follows: Group 1 (N = 20); Group 2 (N = 20) and a control group (N = 5). A single dose of iron oxide (Fe2O3) and silicon oxide (SiO2) NPs dissolved in saline solution were administered orally to the rats. Cardiac puncture was performed to extract peripheral blood for genotoxic analysis. DNA fragmentation for lymphocytes was performed. Control rats showed a fragmentation percentage of 11.20 ± 2.16%. Rats exposed to SiO2 and Fe2O3 NPs for 24 h showed statistically significant differences in DNA fragmentation percentages as compared with that of the control group. A lineal dose-response correlation between genotoxic damage and exposure to SiO2 and Fe2O3 NPs was found (r(2) = 0.99 and 0.98 for SiO2 and Fe2O3, respectively). In conclusion, we found that exposure to Fe2O3 and SiO2 NPs can cause DNA fragmentation in lymphocytes in a dose-dependent manner.

  20. Magnetic Fe2O3-polystyrene/PPy core/shell particles: bioreactivity and self-assembly.

    Science.gov (United States)

    Mangeney, Claire; Fertani, Meriem; Bousalem, Smain; Zhicai, Ma; Ammar, Souad; Herbst, Fréderic; Beaunier, Patricia; Elaissari, Abdelhamid; Chehimi, Mohamed M

    2007-10-23

    This paper describes the synthesis of new magnetic, reactive polystyrene/polypyrrole core/shell latex particles. The core consists of a polystyrene microsphere containing gamma-Fe2O3 superparamagnetic nanoparticles (PSmag), and the shell is made of reactive N-carboxylic acid-functionalized polypyrrole (PPyCOOH). These PSmag-PPyCOOH latex particles, average diameter 220 nm, were prepared by copolymerization of pyrrole (Py) and the active carboxyl-functionalized pyrrole (PyCOOH) in the presence of PSmag particles. PNVP was used as a steric stabilizer. The functionalized polypyrrole-coated PSmag particles were characterized in terms of their particle size, surface morphology, chemical composition, and electrochemical and magnetic properties using transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), cyclic voltammetry, and SQUID magnetometry. Activation of the particle surface carboxyl groups was achieved using 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide (EDC) and N-hydroxysuccinimide (NHS), which helps transform the carboxyl groups into activated ester groups (NSE). The activated particles, PSmag-PPyNSE, were further evaluated as bioadsorbents of biotin used as a model biomolecule. It was shown that biotin was immobilized at the surface of the PSmag-PPyNSE particles by forming interfacial amide groups. The assemblies of PSmag-PPyCOOH particles on glass plates were further investigated. When no magnetic field is applied, the particles assemble into 3D colloidal crystals. In contrast, under a magnetic field, one-particle-thick chains gathered in hedgehog-like architectures are obtained. Furthermore, PSmag-PPyCOOH coated ITO electrodes were shown to be electroactive and electrochemically stable, thus offering potentialities for creating novel high-specific-area materials for biosensing devices where the conducting polymer component would act as the transducer through its conductive properties.

  1. Study on preparation of hollow α-Fe2 O3 magnetic nanofibers%α-Fe2O3中空磁性纳米纤维的制备研究

    Institute of Scientific and Technical Information of China (English)

    王新月; 高强; 高春霞; 葛明桥; 冯古雨

    2015-01-01

    磁性铁氧化物纳米材料是近几十年发展起来的一种具有磁靶向性的纳米材料。其中磁性纳米纤维由于具有独特的形状各向异性和磁晶各向异性,可以突破各向同性的磁性粉体材料对电磁性能的限制而引起研究者的广泛关注。通过静电纺丝、水热合成以及高温煅烧相结合的方法成功制备了新型 Fe2 O 3中空磁性纳米纤维。采用扫描电子显微镜(SEM)、红外光谱分析仪(FT-IR)、差热扫描量热仪(DSC)、热重分析仪(TG)及 X 射线衍射仪(XRD)对煅烧产物进行测试表征,结果表明煅烧产生的磁性纳米纤维非织造布具有新颖的中空结构,对甲基橙有快速吸附。%In recent decades,magnetic iron oxide material has developed into a kind of nanomaterial with the property of magnetic targeting.Magnetic nanoscale fibers have aroused extensive concern of researchers because of the unique shape anisotropy and magnetocrystalline anisotropy which can break through the isotropic magnet-ic powder materials on the properties of electromagnetic limit.Electrospinning,hydrothermal synthesis and high-temperature calcination were combined successfully to prepare novel magnetic nanofibers.Scanning elec-tron microscopy (SEM),fourier transform infrared spectroscopy (FT-IR),thermal gravimetric analysis (TG) and X-ray diffraction (XRD)were employed to test and represent the calcination.The results indicated that the magnetic nanofiber after calcination has a novel structure of the hollow porous microstructure which shows quick and effective adsorption of methyl orange.

  2. Thin Film & Deposition Systems (Windows)

    Data.gov (United States)

    Federal Laboratory Consortium — Coating Lab: Contains chambers for growing thin film window coatings. Plasma Applications Coating Lab: Contains chambers for growing thin film window coatings. Solar...

  3. Thin Film & Deposition Systems (Windows)

    Data.gov (United States)

    Federal Laboratory Consortium — Coating Lab: Contains chambers for growing thin film window coatings. Plasma Applications Coating Lab: Contains chambers for growing thin film window coatings. Solar...

  4. 一步溶剂热法制备石墨烯/Fe2 O3复合材料及电容性能研究%Studies on the preparation of rGO/Fe2 O3 nanocomposite by one-step solvothermal method and their supercapacitive performance

    Institute of Scientific and Technical Information of China (English)

    梁斌; 丁肖怡; 罗民

    2016-01-01

    In this study,rGO/α-Fe2 O3 nanocomposites were prepared using a facial one-step solvothermal method. The characteriza-tion of the nanocomposite shows that theα-Fe2 O3 nanocubes with diameter of 50~100 nm are uniformly distributed on the surface of the reduced graphene oxide nanosheets, which hinders the self-aggregation of grapheme and α-Fe2 O3 nanocubes. The electro-chemical measurement demonstrated that rGO/α-Fe2 O3 exhibits a specific capacitance as high as 799 F g-1 at a discharge current density of 2 A g-1 in the aqueous electrolyte of 6 M KOH,indicating an positive synergistic effect of rGO and Fe2 O3 on the improve-ment of electrochemical performance. The capacity retention is 78. 2%at the current density of 10 A g-1 . Furthermore,the cycling performance of rGO/α-Fe2 O3 nanocomposite is clearly much better than that of pure Fe2 O3 sample,and 42%of the initial capaci-tance can be maintained after 100 cycles of charge-discharge.%以氧化石墨烯为前驱物,硝酸铁为铁源,N,N-二甲基甲酰胺为溶剂,通过一步溶剂热法制备了粒径50 nm左右、均匀地分布在石墨烯表面的石墨烯/α-Fe2 O3( rGO/Fe2 O3)复合材料。复合材料中的α-Fe2 O3均匀地分布在石墨烯片层上,有效的减少了氧化铁纳米颗粒和石墨烯的团聚,实现了氧化铁与石墨烯片之间高效的组装。通过电容性能测试表明,在6 M KOH 溶液中,α-Fe2 O3、rGO和rGO/α-Fe2 O3复合电极材料2 A/g的电流密度下比电容分别为70 F/g、167 F/g、799 F/g,复合材料的比电容比纯Fe2 O3有明显提高,倍率特性和循环稳定性能也得到了改善,循环充放电100次后的电容保持率为42%。

  5. Influence of Fe2O3 Doping on Morphology and Photocatalytic Activity of TiO2 Prepared by Adsorption Phase Synthesis%掺杂Fe2O3对吸附相反应技术制备TiO2的形貌和光催化性能的影响

    Institute of Scientific and Technical Information of China (English)

    王挺; 吴礼光; 蒋新

    2011-01-01

    利用吸附相反应技术制备得到了掺杂不同浓度的Fe2O3的TiO2复合光催化剂.通过透射电子显微镜(TEM)、紫外可见光谱和X射线衍射(XRD)研究不同掺杂浓度对TiO2形貌和结晶过程的影响,并利用3种波长光源下的甲基橙光降解实验考评了各个复合光催化剂的催化活性.结果表明,掺杂后复合光催化剂中Fe2O3分散性较好较均匀.在TiO2紫外可见吸收光谱中由于Fe2O3的掺杂而出现了红移,而且随着掺杂浓度增加红移越来越明显,复合光催化剂的禁带宽度也越来越小.在焙烧过程中无定形Fe2O3或Fe3+进入了TiO2的晶格结构,从而抑制了TiO2的结晶过程.半导体禁带宽度的减少以及TiO2结晶过程的抑制作用,都导致紫外光下复合光催化剂催化活性的降低.但Fe2O3的掺杂也使得复合光催化剂在可见光区出现了一定的光催化活性.%TiO2 photocatalysts doped with Fe2O3 were prepared by adsorption phase synthesis (APS). The influence of Fe2O3 concentration on morphology and crystallization of TiO2 was explored by TEM, UV-Vis and XRD. The activities of these photocatalysts were evaluated by photodegradation of methyl-orange irradiated under three wavelengths of light. The results suggest that the distribution of Fe2O3 in composite photocatalysts is homogeneous. Red shifts appear in UV-Vis absorpion of TiO2 after Fe2O3 doping and the red shift becomes obvious with increasing, in concentration of Fe2O3 , thus leading to decrease in the band gap of composite photocatalysts. Due to the entry of amorphous Fe2O3 or Fe3+ into lattice structure of TiO2, the crystallization of TiO2 is restricted. Both the decrease of band gap and the restriction on TiO2 doped with Fe2O3 would depress the activity of photocatalysts when irradiated at two wavelengths of UV light. However, Fe2O3 doping also leads to a certain activity of photocatalysts under visible light.

  6. 水热合成Fe2O3/石墨烯纳米复合材料及其电化学性能研究%Hydrothermal Synthesis and Lithium Storage Properties of Fe2O3/Graphene Nanocomposites

    Institute of Scientific and Technical Information of China (English)

    季红梅; 于湧涛; 王露; 王静; 杨刚

    2012-01-01

      Fe2O3 nanoparticles on reduced grapheme oxide (RGO) sheets were successfully synthesized via hydro⁃thermal route for lithium ion battery applications. Selective growth of Fe2O3 nanoparticles on RGO sheets allowed for the electrically insulating Fe2O3 nanoparticles to be wired up to a current collector through the underlying conducting graphene network. The Fe2O3 nano-particles formed on RGO at 180 ℃ show good rate capability and cycling stability. During the charge and discharge process with different current density, the initial discharge ca⁃pacity was 1023.6 mAh/g (current density: 40 mA/g). When the current density increased to 800 mA/g, the dis⁃charge capacity still retained at 406.6 mAh/g, higher than the theory capacity of grapheme~372 mAh/g, and the capacity retained stable in other relative high current density. The Fe2O3/RGO hybrid could be a promising can⁃didate material for a high-capacity, low-cost, and environmentally friendly anode for lithium ion batteries.%  利用水热法成功合成了Fe2O3/石墨烯(RGO)锂离子电池负极材料.导电性能良好的石墨烯网络起到连接导电性能极差的Fe2O3和集流体的作用.电化学性能测试表明,180℃下得到的Fe2O3/RGO具有良好的比容量和循环稳定性.在不同倍率充放电过程中,初始放电比容量为1023.6 mAh/g(电流密度为40 mA/g),电流密度增加到800 mA/g 时,放电比容量维持在406.6 mAh/g,大于石墨的理论放电比容量~372 mAh/g.在其他较高的电流密度下比容量均保持基本不变.该Fe2O3/RGO有望成为高容量、低成本、低毒性的新一代锂离子电池负极材料.

  7. Preparation of α- Fe2O3 - TiO2 on Glass Substrates and its Photo-Catalyst Properties%α- Fe2O3-TiO2复合晶膜的制备及光催化特性的研究

    Institute of Scientific and Technical Information of China (English)

    郑晓虹; 陈力勤; 陈日耀; 郑曦; 吴春山; 陈震

    2003-01-01

    α- Fe2O3和TiO2均为n型半导体, 在紫外光照射下可使亚甲基蓝发生氧化还原反应, 使之降解. α-Fe2O3禁带宽度(2.2 eV)比TiO2的禁带宽度(3.1 eV)小, 而其吸收光子的效率大于TiO2, 在催化降解亚甲基蓝时表现出比TiO2 更高的活性. α-Fe2O3-TiO2复合晶体的光吸收强度要比单一α-Fe2O3晶体的光吸收强度明显增强. 在α-Fe2O3中掺入少量TiO2后, 在紫外光照射下对亚甲基蓝的降解显示出更高的活性.

  8. Metal-organic framework derived Fe2O3@NiCo2O4 porous nanocages as anode materials for Li-ion batteries

    Science.gov (United States)

    Huang, Gang; Zhang, Leilei; Zhang, Feifei; Wang, Limin

    2014-04-01

    Metal-organic frameworks (MOFs) with high surface areas and uniform microporous structures have shown potential application in many fields. Here we report a facial strategy to synthesize Fe2O3@NiCo2O4 porous nanocages by annealing core-shell Co3[Fe(CN)6]2@Ni3[Co(CN)6]2 nanocubes in air. The obtained samples have been systematically characterized by XRD, SEM, TEM and N2 adsorption-desorption analysis. The results show that the Fe2O3@NiCo2O4 porous nanocages have an average diameter of 213 nm and a shell thickness of about 30 nm. As anode materials for Li-ion batteries, the Fe2O3@NiCo2O4 porous nanocages exhibit a high initial discharge capacity of 1311.4 mA h g-1 at a current density of 100 mA g-1 (about 0.1 C). The capacity is retained at 1079.6 mA h g-1 after 100 cycles. The synergistic effect of the different components and the porous hollow structure contributes to the outstanding performance of the composite electrode.Metal-organic frameworks (MOFs) with high surface areas and uniform microporous structures have shown potential application in many fields. Here we report a facial strategy to synthesize Fe2O3@NiCo2O4 porous nanocages by annealing core-shell Co3[Fe(CN)6]2@Ni3[Co(CN)6]2 nanocubes in air. The obtained samples have been systematically characterized by XRD, SEM, TEM and N2 adsorption-desorption analysis. The results show that the Fe2O3@NiCo2O4 porous nanocages have an average diameter of 213 nm and a shell thickness of about 30 nm. As anode materials for Li-ion batteries, the Fe2O3@NiCo2O4 porous nanocages exhibit a high initial discharge capacity of 1311.4 mA h g-1 at a current density of 100 mA g-1 (about 0.1 C). The capacity is retained at 1079.6 mA h g-1 after 100 cycles. The synergistic effect of the different components and the porous hollow structure contributes to the outstanding performance of the composite electrode. Electronic supplementary information (ESI) available: Detailed supplementary figures. See DOI: 10.1039/c3nr06041a

  9. Evaluation of tumorigenic potential of CeO2 and Fe2O3 engineered nanoparticles by a human cell in vitro screening model.

    Science.gov (United States)

    Stueckle, Todd A; Davidson, Donna C; Derk, Raymond; Kornberg, Tiffany G; Schwegler-Berry, Diane; Pirela, Sandra V; Deloid, Glen; Demokritou, Philip; Luanpitpong, Sudjit; Rojanasakul, Yon; Wang, Liying

    2017-04-01

    With rapid development of novel nanotechnologies that incorporate engineered nanomaterials (ENMs) into manufactured products, long-term, low dose ENM exposures in occupational settings is forecasted to occur with potential adverse outcomes to human health. Few ENM human health risk assessment efforts have evaluated tumorigenic potential of ENMs. Two widely used nano-scaled metal oxides (NMOs), cerium oxide (nCeO2) and ferric oxide (nFe2O3) were screened in the current study using a sub-chronic exposure to human primary small airway epithelial cells (pSAECs). Multi-walled carbon nanotubes (MWCNT), a known ENM tumor promoter, was used as a positive control. Advanced dosimetry modeling was employed to ascertain delivered vs. administered dose in all experimental conditions. Cells were continuously exposed in vitro to deposited doses of 0.18 μg/cm(2) or 0.06 μg/cm(2) of each NMO or MWCNT, respectively, over 6 and 10 weeks, while saline- and dispersant-only exposed cells served as passage controls. Cells were evaluated for changes in several cancer hallmarks, as evidence for neoplastic transformation. At 10 weeks, nFe2O3- and MWCNT-exposed cells displayed a neoplastic-like transformation phenotype with significant increased proliferation, invasion and soft agar colony formation ability compared to controls. nCeO2-exposed cells showed increased proliferative capacity only. Isolated nFe2O3 and MWCNT clones from soft agar colonies retained their respective neoplastic-like phenotypes. Interestingly, nFe2O3-exposed cells, but not MWCNT cells, exhibited immortalization and retention of the neoplastic phenotype after repeated passaging (12 - 30 passages) and after cryofreeze and thawing. High content screening and protein expression analyses in acute exposure ENM studies vs. immortalized nFe2O3 cells, and isolated ENM clones, suggested that long-term exposure to the tested ENMs resulted in iron homeostasis disruption, an increased labile ferrous iron pool, and subsequent

  10. Synthesis of ZnO@γ-Fe2O3 core-shell nanocomposites by a facile thermal decomposition approach and their application in photocatalytic degradation of congo red

    Science.gov (United States)

    Yadav, Sudheer Kumar; Jeevanandam, P.

    2016-07-01

    ZnO@γ-Fe2O3 core-shell nanocomposites were synthesized by a facile thermal decomposition approach. ZnO nanorods were first synthesized by calcination of zinc acetate at 300 °C, in air. γ-Fe2O3 nanoparticles were then deposited on the surface of ZnO nanorods by the thermal decomposition of iron acetylacetonate at 200 °C in diphenyl ether. The structure, composition, optical and magnetic properties of the nanocomposites were studied using an array of techniques. XRD results suggest the presence of γ-Fe2O3 nanoparticles and ZnO, and FE-SEM images indicate formation of shell of iron oxide on the ZnO nanorods. Transmission electron microscopy studies clearly show that ZnO possesses rod morphology (length = 1.1 ± 0.1 μm, diameter = 40.1 ± 7 nm) and TEM images of the ZnO@γ-Fe2O3 nanocomposites show uniform shell of γ-Fe2O3 coated on the ZnO nanorods and thickness of the γ-Fe2O3 shell varies from 10 to 20 nm. Diffuse reflectance spectra of ZnO@γ-Fe2O3 nanocomposites reveal extended optical absorption in the visible range (400-600 nm) and photoluminescence spectra indicate that the ZnO@γ-Fe2O3 nanocomposites exhibit enhanced defect emission. The ZnO@γ-Fe2O3 core-shell nanocomposites show superparamagnetic behaviour at room temperature. The core-shell nanocomposites exhibit enhanced visible-light driven photocatalytic degradation of congo red in an aqueous solution as compared to pure ZnO nanorods and γ-Fe2O3 nanoparticles. The enhanced photocatalytic activity is attributed to good visible-light absorption and effective charge separation at the interface of ZnO@γ-Fe2O3 core-shell nanocomposites.

  11. Studies of preparation and conductivity of γ-Fe2O3/polythiophene nanocomposites%γ-Fe2O3/聚噻吩纳米复合材料的制备及其导电性能研究

    Institute of Scientific and Technical Information of China (English)

    殷华茹; 姜继森

    2005-01-01

    采用单体聚合法以FeCl3为引发剂进行噻吩的聚合反应,得到了导电性好的γ-Fe2O3/聚噻吩纳米复合材料.红外、透射电镜、穆斯堡尔谱等研究表明γ-Fe2O3与聚噻吩之间有着一定的相互作用.复合材料的导电性明显高于纯的聚噻吩样品,随着γ-Fe2O3含量的增加,复合材料的导电性呈增大趋势.

  12. Synergistic Catalysis of Fe2O3 and TiF3 Additives on the LiBH4-MgH2 Composite%Fe2O3与TiF3添加剂对LiBH4-MgH2复合氢化物体系的协同催化作用

    Institute of Scientific and Technical Information of China (English)

    张慧; 焦成丽; 王爽; 李志宝; 刘双; 李芬; 周奕汐; 孙立贤; 曹忠; 徐芬; 刘淑生; 张箭; 宋莉芳; 司晓亮

    2012-01-01

    通过球磨方法制备出2LiBH4-MgH2,2LiBH4-MgH2-10% Fe2O3,2LiBH4 -MgH2-10% TiF3,2LiBH4 -MgH2 -5% Fe2O3-5% TiF3和2LiBH4 -MgH2-10% Fe2O3-10% TiF35个复合氢化物体系,用热重(TG)、差示扫描量热( DSC)、X射线衍射(XRD)、傅里叶变换红外光谱(FTIR)和压力-组成-温度仪(PCT)等对所制备体系进行表征.结果表明,Fe2O3和TiF3的掺杂均能够有效地改善2LiBH4-MgH2复合体系的放氢性能,尤其是两者共掺杂的2LiBH4-MgH2-10% Fe2O3-10% TiF3体系,初始放氢温度为110℃,总放氢量达到约9.6%.对2LiBH4-MgH2-5% Fe2O3-5%TiF3体系的PCT表征结果表明,在400℃时,10 min内放氢量达到了8.6%,放氢热力学和放氢动力学均优于单一相的掺杂,体现了两相掺杂的协同催化作用.%Five systems (2LiBH4-MgH2, 2LiBH4-MgH2-10% Fe2O3, 2LiBH4-MgH2-10% TiF3, 2LiBH4-MgH2-5%Fe20,-5%TiF3 and 2LiBH4-MgH2-10% Fe2O3-10%TiF3) were prepared by ball milling. They were investigated through thermogravimeteric analysis (TG) , diffraction scanning calorimetric ( DSC ) , powder X-ray diffraction (XRD), Fourier transformed infrared spectrometer (FTIR) and pressure-content-temperature (PCT). The addition of Fe2O3 and TiF3 improved the hydrogen release property of the LiBH4-MgH2 complex system effectively. Especially, the codoped system (2LiBH4-MgH2-10% Fe2O3-10% TiF3) starts to release hydrogen at around 110 °C and can release as much as 9.6%. Besides, the results of PCT show that the codoped system (2LiBH4-MgH2-5% Fe2O3-5% TiF3 ) can release about 8.6% hydrogen within 10 min at 400 ℃. The properties of the codoped system are better than the other two single doped systems, which partly incarnated the synergistic catalysis of Fe2O3 and TiF3.

  13. Biomimetic thin film synthesis

    Energy Technology Data Exchange (ETDEWEB)

    Graff, G.L.; Campbell, A.A.; Gordon, N.R.

    1995-05-01

    The purpose of this program is to develop a new process for forming thin film coatings and to demonstrate that the biomimetic thin film technology developed at PNL is useful for industrial applications. In the biomimetic process, mineral deposition from aqueous solution is controlled by organic functional groups attached to the underlying substrate surface. The coatings process is simple, benign, inexpensive, energy efficient, and particularly suited for temperature sensitive substrate materials (such as polymers). In addition, biomimetic thin films can be deposited uniformly on complex shaped and porous substrates providing a unique capability over more traditional line-of-sight methods.

  14. 负载NiO-Fe2O3的凹凸棒石对生物油模型物催化重整制氢性能的影响%Hydrogen production via catalytic steam reforming of bio-oil model compounds over NiO-Fe2 O3-loaded palygouskite

    Institute of Scientific and Technical Information of China (English)

    王一双; 陈明强; 刘少敏; 杨忠连; 沈朝萍; 刘珂

    2015-01-01

    A series of NiO-Fe2 O3 catalysts loaded on palygouskite were prepared by co-precipitation method and used in the catalytic steam reforming to produce hydrogen in a self-made three-stage fixed bed reactor. The loading of NiO-Fe2 O3 , reaction temperature and ratio of steam to carbon ( S/C) on hydrogen production were investigated, with a water-soluble mixture of acetic acid, ethanol and phenol as the bio-oil model compounds. The results indicated that under the optimum conditions, viz. , 650 ° C, an S/C ratio of 8 ~10 and 50%NiO-50%Fe2 O3/PG as the catalyst, the relative content of H2 reaches 66. 15% in the gaseous product.%利用共沉淀法,制备一系列在凹凸棒土上负载不同含量的NiO-Fe2O3 催化剂. 以乙酸、乙醇和苯酚的水溶性溶液为生物油模型物,在自制的三段式固定床反应器中,考察了NiO-Fe2 O3 的负载量、反应温度、水碳比( S/C)对生物油模型物重整制氢的影响. 结果表明,所获得的氢气产率最高的工艺条件为,在650℃条件下,以水碳比8~10的生物油模型为实验原料,使用自制的50%NiO-50%Fe2 O3/PG型催化剂,可使气体产物中H2 的相对含量达到最大66. 15%.

  15. Facile synthesis of Fe3O4 nanoparticles by reduction phase transformation from gamma-Fe2O3 nanoparticles in organic solvent.

    Science.gov (United States)

    Hai, Hoang Tri; Kura, Hiroaki; Takahashi, Migaku; Ogawa, Tomoyuki

    2010-01-01

    A phase transformation induced by the reduction of as-synthesized gamma-maghemite (gamma-Fe(2)O(3)) nanoparticles was performed in solution by exploiting the reservoir of reduction gas (CO) generated from the incomplete combustion reaction of organic substances in the reactor. Results from X-ray diffraction, color indicator, and magnetic analysis using a SQUID strongly support this phase transformation. Based on this route, monodisperse magnetite (Fe(3)O(4)) nanoparticles were simply produced in the range from 260 to 300 degrees C. Almost all aspects of the original gamma-Fe(2)O(3) nanoparticles, such as shape, size, and monodispersity, were maintained in the produced Fe(3)O(4) nanoparticles.

  16. Transmission electron microscopy studies of mechanical alloying in the immiscible a-Fe2O3-SnO2 system

    DEFF Research Database (Denmark)

    Rickerby, D.G.; Jiang, Jianzhong; Lin, R.;

    1998-01-01

    Microstructural development and nanoscale compositional variations in mechanically alloyed Fe2O3-SnO2 powders have been examined by transmission electron microscopy and energy dispersive X-ray spectrometry. The mean grain size was found to stabilize around 10 nm after 19 h milling time, in close...... in relation to precious measurements in the same system by X-ray diffraction and Mossbauer spectroscopy, which suggested that alloying on the atomic scale occurred after 110 h milling. The present studies confirm that the amount of Sn dissolved in the Fe2O3 hematite lattice increases with longer milling times......, indicating that a supersaturated solid solution is formed, but that mixing may be locally inhomogeneous at the atomic level. Similar conclusions have been reported for studies of mechanical alloying in immiscible metallic systems. The tendency for SnO2 grains above a certain critical size to remain...

  17. Drastic Dependence of the pH Sensitivity of Fe2O3-Bi2O3-B2O3 Hydrophobic Glasses with Composition

    Directory of Open Access Journals (Sweden)

    Tadanori Hashimoto

    2015-12-01

    Full Text Available Fe2O3-Bi2O3-B2O3 (FeBiB glasses were developed as novel pH responsive hydrophobic glasses. The influence of the glass composition on the pH sensitivity of FeBiB glasses was investigated. The pH sensitivity drastically decreased with decreasing B2O3 content. A moderate amount of Fe2O3 and a small amount of B2O3 respectively produces bulk electronic conduction and a pH response on glass surfaces. Because the remaining components of the glass can be selected freely, this discovery could prove very useful in developing novel pH glass electrodes that are self-cleaning and resist fouling.

  18. Preparation of γ-Fe2O3/Ni2O3/FeCl3(FeCl2 Composite Nanoparticles by Hydrothermal Process Useful for Ferrofluids

    Directory of Open Access Journals (Sweden)

    Qingmei Zhang

    2011-01-01

    Full Text Available Using a hydrothermal process in FeCl2 solution, γ-Fe2O3/Ni2O3/FeCl3(FeCl2 composite nanoparticles were obtained from the FeOOH/Ni(OH2 precursor prepared by coprecipitation. The precursor and the as-prepared nanoparticles were investigated by vibrating sample magnetometer (VSM, X-ray diffraction (XRD, energy disperse X-ray spectroscopy (EDX, X-ray photoelectron spectroscopy (XPS, and transmission electron microscopy (TEM. The experimental results showed that the paramagnetic amorphous precursor, in which Ni(OH2 is formed outside FeOOH, is transformed to ferrimagnetic γ-Fe2O3/Ni2O3 composite when it is processed in FeCl2 solution (0.25, 0.50, 1.00 M in an autoclave at 100°C for 1 hr. In addition, the dismutation reaction of FeCl2 produces FeCl3 and Fe. Some FeCl3 and little FeCl2 can be absorbed to form γ-Fe2O3/Ni2O3/FeCl3(FeCl2 composite nanoparticles in which Ni2O3 forms outside the γ-Fe2O3 core and the outermost layer is FeCl3 (FeCl2. The content of FeCl3 (FeCl2 in the particles increased, and the magnetization of the particles decreased with the concentration of FeCl2 solution increasing in the hydrothermal process. The FeCl3 (FeCl2 surface is chemically passive and nonmagnetic (paramagnetic. Accordingly, the composite nanoparticles are chemically stable, and their aggregation is prevented. The specific saturation magnetization of such composite nanoparticles can get to 57.4–62.2 emu/g and could be very suitable for synthesizing ferrofluids.

  19. Correlation of gas sensitivite properties with microstructure of Fe2O3-SnO2 ceramics prepared by high energy ball milling

    DEFF Research Database (Denmark)

    Jiang, Jianzhong; Lu, S.W.; Zhou, Y.X.;

    1997-01-01

    A remarkable gas sensitivity to ethnaol gas has been observed in nanostructured Fe2O3-SnO2 materials with a composition of 6.4 mol% SnO2 prepared by high energy ball milling. The microstructure of the materials has been examined by x-ray diffraction (XRD) and Mossbauer spectroscopy. It was found...... that tin in the hematite phase plays an important role in high gas sensitivity....

  20. Study on the water durability of zinc boro-phosphate glasses doped with MgO, Fe2O3, and TiO2

    Science.gov (United States)

    Hwang, Moon Kyung; Ryu, Bong Ki

    2016-07-01

    The water durability of zinc boro-phosphate (PZB) glasses with the composition 60P2O5-20ZnO-20B2O3- xMeO ( x = 0, 2, 4, 6 and MeO = MgO, Fe2O3, or TiO2) (mol%) was measured, and PZB glass was studied in terms of its thermal properties, density, and FTIR characteristics. The surface conditions and corrosion byproducts were analyzed using scanning electron microscopy. When MgO, Fe2O3, and TiO2 were doped into the PZB glass, Q2 was decreased and Q1 was increased in the phosphate structure, while the number of BO4 structures increased with increasing MeO content. The density of the PZB glass was increased by the addition of Fe2O3 and TiO2, while the glass transition temperature ( T g ) and dilatometric softening temperature ( T d ) were increased when additional MgO, Fe2O3, and TiO2 were added. From the weight loss analysis (95 ◦ C, 96 h), TiO2 doped glass showed the lowest weight loss (1.70 × 10 -3 g/cm2) while MgO doped glass showed the highest value (2.44 × 10 -3 g/cm2), compared with PZB glass (3.07 × 10 -3 g/cm2). These results were discussed in terms of the Me n+ ions in the glass structure, and their different coordination numbers and bonding strengths.

  1. Optical and magnetic properties of Fe2O3 nanoparticles synthesized by laser ablation/fragmentation technique in different liquid media

    Science.gov (United States)

    Pandey, B. K.; Shahi, A. K.; Shah, Jyoti; Kotnala, R. K.; Gopal, Ram

    2014-01-01

    Iron oxide (Fe2O3) bulk powder have been ablated/fragmented in different liquid medium by Nd:YAG laser beam using 1064 nm wavelength. Sodium dodecyl sulfate (SDS), cetyltrimethyl ammonium bromide (CTAB) and double distilled water (DDW) are used as liquid medium. Crystalline size, lattice strain, phase and structure of ablated particles have been investigated using synchrotron X-ray diffraction. Optical band gap energy of as purchased Fe2O3 found 1.92 eV that increased to 2.03 eV after ablation in CTAB determined by UV-vis absorption spectroscopy. Magnetic properties have been analyzed by hysteresis loops using vibrating sample magnetometer (VSM). Crystalline sizes have been found in the range of 29.23-16.54 nm and coercivity tailored in the range of 206.91-298.36 Oe using laser ablation. Saturation magnetization and remanence have been found in the range of 0.013-3.41 emu/g and 0.0023-.0.51 emu/g respectively. Particle shape and size have been examined by scanning electron microscopy (SEM). CTAB (cationic) and SDS (anionic) surfactants are used as capping agent. CTAB produces phase transformation in ablated iron oxide (Fe2O3). Crystallinity and crystalline size of ablated particles in DDW increased due to presence of rich oxygen in it due to oxidation. Ablated Fe2O3 nanoparticles have been widely used experimentally for numerous in vivo applications such as MRI contrast enhancement agent, tissue repair, immunoassay, detoxification of biological fluids, hyperthermia, drug delivery and cell separation.

  2. Ewald methods for polarizable surfaces with application to hydroxylation and hydrogen bonding on the (012) and (001) surfaces of alpha-Fe2O3

    OpenAIRE

    Wasserman, E.; Rustad, J. R.; Felmy, A. R.; HAY, B.P.; Halley, J. W.

    1997-01-01

    We present a clear and rigorous derivation of the Ewald-like method for calculation of the electrostatic energy of the systems infinitely periodic in two-dimensions and of finite size in the third dimension (slabs) which is significantly faster than existing methods. Molecular dynamics simulations using the transferable/polarizable model by Rustad et al. were applied to study the surface relaxation of the nonhydroxylated, hydroxylated, and solvated surfaces of alpha-Fe2O3 (hematite). We find ...

  3. Thin film device applications

    CERN Document Server

    Kaur, Inderjeet

    1983-01-01

    Two-dimensional materials created ab initio by the process of condensation of atoms, molecules, or ions, called thin films, have unique properties significantly different from the corresponding bulk materials as a result of their physical dimensions, geometry, nonequilibrium microstructure, and metallurgy. Further, these characteristic features of thin films can be drasti­ cally modified and tailored to obtain the desired and required physical characteristics. These features form the basis of development of a host of extraordinary active and passive thin film device applications in the last two decades. On the one extreme, these applications are in the submicron dimensions in such areas as very large scale integration (VLSI), Josephson junction quantum interference devices, magnetic bubbles, and integrated optics. On the other extreme, large-area thin films are being used as selective coatings for solar thermal conversion, solar cells for photovoltaic conver­ sion, and protection and passivating layers. Ind...

  4. Phosphate Shifted Oxygen Reduction Pathway on Fe@Fe2O3 Core-Shell Nanowires for Enhanced Reactive Oxygen Species Generation and Aerobic 4-Chlorophenol Degradation.

    Science.gov (United States)

    Mu, Yi; Ai, Zhihui; Zhang, Lizhi

    2017-07-18

    Phosphate ions widely exist in the environment. Previous studies revealed that the adsorption of phosphate ions on nanoscale zerovalent iron would generate a passivating oxide shell to block reactive sites and thus decrease the direct pollutant reduction reactivity of zerovalent iron. Given that molecular oxygen activation process is different from direct pollutant reduction with nanoscale zerovalent iron, it is still unclear how phosphate ions will affect molecular oxygen activation and reactive oxygen species generation with nanoscale zerovalent iron. In this study, we systematically studied the effect of phosphate ions on molecular oxygen activation with Fe@Fe2O3 nanowires, a special nanoscale zerovalent iron, taking advantages of rotating ring disk electrochemical analysis. It was interesting to find that the oxygen reduction pathway on Fe@Fe2O3 nanowires was gradually shifted from a four-electron reduction pathway to a sequential one-electron reduction one, along with increasing the phosphate ions concentration from 0 to 10 mmol·L(-1). This oxygen reduction pathway change greatly enhanced the molecular oxygen activation and reactive oxygen species generation performances of Fe@Fe2O3 nanowires, and thus increased their aerobic 4-chlorophenol degradation rate by 10 times. These findings shed insight into the possible roles of widely existed phosphate ions in molecular oxygen activation and organic pollutants degradation with nanoscale zerovalent iron.

  5. Development of highly porous biodegradable γ-Fe2O3/polyvinyl alcohol nanofiber mats using electrospinning process for biomedical application.

    Science.gov (United States)

    Ngadiman, Nor Hasrul Akhmal; Yusof, Noordin Mohd; Idris, Ani; Misran, Effaliza; Kurniawan, Denni

    2017-01-01

    The use of electrospinning process in fabricating tissue engineering scaffolds has received great attention in recent years due to its simplicity. The nanofibers produced via electrospinning possessed morphological characteristics similar to extracellular matrix of most tissue components. Porosity plays a vital role in developing tissue engineering scaffolds because it influences the biocompatibility performance of the scaffolds. In this study, maghemite (γ-Fe2O3) was mixed with polyvinyl alcohol (PVA) and subsequently electrospun to produce nanofibers. Five factors; nanoparticles content, voltage, flow rate, spinning distance, and rotating speed were varied to produce the electrospun nanofibrous mats with high porosity value. Empirical model was developed using response surface methodology to analyze the effect of these factors to the porosity. The results revealed that the optimum porosity (90.85%) was obtained using 5% w/v nanoparticle content, 35kV of voltage, 1.1ml/h volume flow rate of solution, 8cm spinning distance and 2455rpm of rotating speed. The empirical model was verified successfully by performing confirmation experiments. The properties of optimum PVA/γ-Fe2O3 nanofiber mats such as fiber diameter, mechanical properties, and contact angle were investigated. In addition, cytocompatibility test, in vitro degradation rate, and MTT assay were also performed. Results revealed that high porosity biodegradable γ-Fe2O3/polyvinyl alcohol nanofiber mats have low mechanical properties but good degradation rates and cytocompatibility properties. Thus, they are suitable for low load bearing biomedical application or soft tissue engineering scaffold.

  6. Hydrothermal synthesis and characterization of Fe2O3nanocrystals%氧化铁纳米晶的水热合成及表征

    Institute of Scientific and Technical Information of China (English)

    郭权; 金盈; 吴友吉; 姜亮; 季军胜

    2015-01-01

    Iron oxide nanocrystals was successfully synthesized using iron nitrate as iron source and sodium hydroxide solution as precipitant by hydrothermal method. Several techniques including XRD and SEM were used to characterize the products. The results showed that,it was still further beneficial to gain smaller size and uniform distribution of the hexagonal Fe2O3 with pH=7 at 180℃ for 24h.%以硝酸铁为铁源,氢氧化钠溶液为沉淀剂,通过水热法合成了氧化铁纳米晶.利用X射线粉末衍射仪(XRD)和扫描电子显微镜(SEM)对Fe2O3纳米晶的结构及形貌进行了表征分析.结果表明,pH=7时,在180℃下反应24 h更有利于颗粒粒径的细化,并使其粒径分布均匀,所得样品为六方晶系的Fe2O3

  7. Investigation of structural and magnetic properties of co-precipitated Mn-Ni ferrite nanoparticles in the presence of α-Fe2O3 phase

    Science.gov (United States)

    Tirupanyam, B. V.; Srinivas, Ch.; Meena, S. S.; Yusuf, S. M.; Satish Kumar, A.; Sastry, D. L.; Seshubai, V.

    2015-10-01

    A systematic study on structural and magnetic properties of co-precipitated MnxNi1-xFe2O4 (x=0.5, 0.6, 0.7) ferrite nanoparticles annealed at 800 °C was carried out using XRD, FE-SEM, VSM and MÖSSBAUER techniques. Anti-ferromagnetic α-Fe2O3 phase was observed along with the magnetic spinel phase in the XRD patterns. It is observed that both lattice parameter and crystallite size of spinel phase increase with increase in concentration of Mn2+ along with the amount of α-Fe2O3 phase. The saturation magnetization (Ms) decreases while coercivity (Hc) increases with increase of Mn2+ ion concentration. Mössbauer spectra indicate that iron ions present in A and B sites are in the Fe3+ state and Fe2+ is absent. The results are interpreted in terms of observed anti-ferromagnetic α-Fe2O3 phase, core-shell interactions and cation redistribution.

  8. Removal of cadmium(II) ions from aqueous solution using Ni (15 wt.%)-doped α-Fe2O3 nanocrystals: equilibrium, thermodynamic, and kinetic studies.

    Science.gov (United States)

    OuldM'hamed, Mohamed; Khezami, L; Alshammari, Abdulrahman G; Ould-Mame, S M; Ghiloufi, I; Lemine, O M

    2015-01-01

    The present publication investigates the performance of nanocrystalline Ni (15 wt.%)-doped α-Fe2O3 as an effective nanomaterial for the removal of Cd(II) ions from aqueous solutions. The nanocrystalline Ni-doped α-Fe2O3 powders were prepared by mechanical alloying, and characterized by X-ray diffraction and a vibrating sample magnetometer. Batch-mode experiments were realized to determine the adsorption equilibrium, kinetics, and thermodynamic parameters of toxic heavy metal ions by Ni (15 wt.%)-doped α-Fe2O3. The adsorption isotherms data were found to be in good agreement with the Langmuir model. The adsorption capacity of Cd(II) ion reached a maximum value of about 90.91 mg g(-1) at 328 K and pH 7. The adsorption process kinetics was found to comply with pseudo-second-order rate law. Thermodynamic parameters related to the adsorption reaction, free energy change, enthalpy change and entropy change, were evaluated. The found values of free energy and enthalpy revealed a spontaneous endothermic adsorption-process. Moreover, the positive entropy suggests an increase of randomness during the process of heavy metal removal at the adsorbent-solution interface.

  9. The Semi-Quantitative Study of Magnetization Process on Milling and Reannealing of Barium Hexaferrite (BaO.6Fe2O3

    Directory of Open Access Journals (Sweden)

    Ridwan

    2009-07-01

    Full Text Available Barium hexaferrite (BaO.6Fe2O3 is as a hard magnetic material with good chemical stability which has been intensively used as permanent magnet components. Many works have been done in order to improve their magnetic properties either through chemical process or powders metallurgy technique. In this work, commercial BaO.6Fe2O3 was milled using high-energy milling machine for 10, 20 and 30 hours and followed by reannealing for 3 hours at 1000⁰C in air. X-ray diffraction pattern indicate no phase decomposition occurred caused the mill processing, annealing of milled powders recovered the crystal system and promoted crystallite growth. The magnetic hysteresis curve measured by vibrating sample magnetometer (VSM shows the coercivity of annealed BaO.6Fe2O3 increases to two times higher than the original one. By using Jiles-Atherton model, all the hysteresis parameters Ms, k, α, a and c, have been determined adopted to the Genetic Algorithm (GA. The analyzed hysteretic parameters obtained from this work is congruent to the change of magnetic properties of as-milled and annealed powders of barium hexaferrite.

  10. Microstructure and Magnetic Properties of Highly Ordered SBA-15 Nanocomposites Modified with Fe2O3 and Co3O4 Nanoparticles

    Directory of Open Access Journals (Sweden)

    P. F. Wang

    2012-01-01

    Full Text Available Owing to the unique order mesopores, mesoporous SBA-15 could be used as the carrier of the magnetic nanoparticles. The magnetic nanoparticles in the frame and the mesopores lead to the exchange-coupling interaction or other interactions, which could improve the magnetic properties of SBA-15 nanocomposites. Mesoporous Fe/SBA-15 had been prepared via in situ anchoring Fe2O3 into the frame and the micropores of SBA-15 using the sol-gel and hydrothermal processes. Co3O4 nanoparticles had been impregnated into the mesopores of Fe/SBA-15 to form mesoporous Fe/SBA-15-Co3O4 nanocomposites. XRD, HRTEM, VSM, and N2 physisorption isotherms were used to characterize the mesostructure and magnetic properties of the SBA-15 nanocomposites, and all results indicated that the Fe2O3 nanoparticles presented into the frame and micropores, while the Co3O4 nanoparticles existed inside the mesopores of Fe/SBA-15. Furthermore, the magnetic properties of SBA-15 could be conveniently adjusted by the Fe2O3 and Co3O4 magnetic nanoparticles. Fe/SBA-15 exhibited ferromagnetic properties, while the impregnation of Co3O4 nanoparticles greatly improved the coercivity with a value of 1424.6 Oe, which was much higher than that of Fe/SBA-15.

  11. A Core-Shell Fe/Fe2 O3 Nanowire as a High-Performance Anode Material for Lithium-Ion Batteries.

    Science.gov (United States)

    Na, Zhaolin; Huang, Gang; Liang, Fei; Yin, Dongming; Wang, Limin

    2016-08-16

    The preparation of novel one-dimensional core-shell Fe/Fe2 O3 nanowires as anodes for high-performance lithium-ion batteries (LIBs) is reported. The nanowires are prepared in a facile synthetic process in aqueous solution under ambient conditions with subsequent annealing treatment that could tune the capacity for lithium storage. When this hybrid is used as an anode material for LIBs, the outer Fe2 O3 shell can act as an electrochemically active material to store and release lithium ions, whereas the highly conductive and inactive Fe core functions as nothing more than an efficient electrical conducting pathway and a remarkable buffer to tolerate volume changes of the electrode materials during the insertion and extraction of lithium ions. The core-shell Fe/Fe2 O3 nanowire maintains an excellent reversible capacity of over 767 mA h g(-1) at 500 mA g(-1) after 200 cycles with a high average Coulombic efficiency of 98.6 %. Even at 2000 mA g(-1) , a stable capacity as high as 538 mA h g(-1) could be obtained. The unique composition and nanostructure of this electrode material contribute to this enhanced electrochemical performance. Due to the ease of large-scale fabrication and superior electrochemical performance, these hybrid nanowires are promising anode materials for the next generation of high-performance LIBs.

  12. Controlled synthesis of alpha-Fe2O3 nanorods and its size-dependent optical absorption, electrochemical, and magnetic properties.

    Science.gov (United States)

    Zeng, Suyuan; Tang, Kaibin; Li, Tanwei

    2007-08-15

    Uniform alpha-Fe(2)O(3) nanorods with diameter of about 30 nm and length up to 500 nm were synthesized by a template-free hydrothermal method and a following calcination of the intermediate product in the air at 500 degrees C for 2 h. By carefully tuning the concentration of the reactants, a series of alpha-Fe(2)O(3) nanorods with gradient in aspect ratios can be obtained. The effect of the solvent was also evaluated. Based on the experimental facts, the formation mechanism of this one-dimensional structure was proposed. The size-dependent properties of the as-obtained alpha-Fe(2)O(3) nanorods were investigated. The optical absorption properties of the samples showed that the band gaps of the samples decreased in the sequence in which the size increased. The electrochemical performance of the samples showed that the discharge capacity decreased as the size of the sample increased, which may result from the high surface area and small size. The magnetic hysteresis measurements taken at 5 K showed that the coercivities of the samples were related to the aspect ratios of the samples, which may result from the larger shape anisotropy. However, the temperature-dependent field cooling magnetization showed that there was no Morin transition in the as-prepared samples, which may result from the surface effect.

  13. Enhanced Fe2O3 Reducibility via Surface Modification with Pd: Characterizing the Synergy within Pd/Fe Catalysts for Hydrodeoxygenation Reactions

    Energy Technology Data Exchange (ETDEWEB)

    Hensley, Alyssa; Hong, Yongchun; Zhang, Renqin; Zhang, He; Sun, Junming; Wang, Yong; McEwen, Jean-Sabin

    2014-10-03

    The synergistic catalysis in the hydrodeoxygenation of phenolic compounds over a Pd/Fe bimetallic surface has been well established. However, the nature of this synergy is still in part a mystery. In this work, we used a combined experimental and theoretical approach to understand a potential function of the surface Pd in the reduction of Pd/Fe2O3. This function of Pd was investigated via the comparison of the reduction properties as well as other physicochemical properties of samples synthesized by the reduction of Fe2O3 nanoparticles with and without surface Pd. Temperature-programmed reduction studies demonstrated the remarkable facilitation of reduction by addition of Pd, evidenced by a 150 degrees C shift toward lower temperature of the reduction peak of Fe3+. From X-ray photoelectron spectroscopy and theoretical calculation results, the interaction between Pd and the Fe2O3 surface occurs through the exchange of electrons with both the surface Fe and O atoms. This bonding between the Pd and surface oxide elements causes the Pd to partially donate electrons to the oxide surface, making the surface electrons more delocalized. This electron delocalization stabilizes the reduced oxide surfaces, as suggested by the TPR results and theoretical prediction. Therefore, the stabilization of the reduced Fe surface as well as the facilitated water formation by introduction of Pd is expected to significantly contribute to the Pd-Fe synergy in hydrodeoxygenation catalysis.

  14. Ceramsite obtained from water and wastewater sludge and its characteristics affected by Fe2O3, CaO, and MgO.

    Science.gov (United States)

    Zou, J L; Xu, G R; Li, G B

    2009-06-15

    To solve the disposal problems of residual sludges, wastewater treatment sludge (WWTS) and drinking-water treatment sludge (DWTS) were tested as components for producing ceramsite. Fe(2)O(3), CaO, and MgO were the major basic oxides in WWTS and DWTS, so their effect on characteristics of ceramsite was also investigated to optimize the process. Results show that WWTS and DWTS can be utilized for producing ceramsite with optimal contents of Fe(2)O(3), CaO, and MgO ranging 5-8%, 2.75-7%, and 1.6-4%, respectively. Ceramsite within the optimal Fe(2)O(3), CaO, and MgO contents ranges was characterized using thermal analysis, X-ray diffraction (XRD), morphological structures analyses, and compressive strength measurements. Higher strength ceramsite with more complex crystalline phases and fewer pores can be obtained at 6%needed ions for producing electrical neutrality of silicate networks. Ceramsite characteristics are not dramatically influenced by MgO because Mg(2+) cannot destroy the unity of crystalline structures. This revolutionary technology of utilization of WWTS and DWTS can produce high performance ceramsite thus reducing costs of sludge disposal, in accordance with the concept of sustainable development.

  15. Tuning exchange bias in Fe/γ-Fe2O3 core-shell nanoparticles: Impacts of interface and surface spins

    Science.gov (United States)

    Khurshid, Hafsa; Phan, Manh-Huong; Mukherjee, Pritish; Srikanth, Hariharan

    2014-02-01

    A comparative study has been performed of the exchange bias (EB) effect in Fe/γ-Fe2O3 core-shell nanoparticles with the same thickness of the γ-Fe2O3 shell (˜2 nm) and the diameter of the Fe core varying from 4 nm to 11 nm. Transmission electron microscopy (TEM) and high-resolution TEM confirmed the high quality of the core-shell nanostructures. A systematic analysis of magnetization versus magnetic field measurements under zero-field-cooled and field-cooled regimes using the Meiklejohn-Bean model and deconvoluting superparamagnetic and paramagnetic contribution to the total magnetic moment Langevin function shows that there exists a critical particle size (˜10 nm), above which the spins at the interface between Fe and γ-Fe2O3 contribute primarily to the EB, but below which the surface spin effect is dominant. Our finding yields deeper insight into the collective contributions of interface and surface spins to the EB in core-shell nanoparticle systems, knowledge of which is the key to manipulating EB in magnetic nanostructures for spintronics applications.

  16. Multifunctional thin film surface

    Energy Technology Data Exchange (ETDEWEB)

    Brozik, Susan M.; Harper, Jason C.; Polsky, Ronen; Wheeler, David R.; Arango, Dulce C.; Dirk, Shawn M.

    2015-10-13

    A thin film with multiple binding functionality can be prepared on an electrode surface via consecutive electroreduction of two or more aryl-onium salts with different functional groups. This versatile and simple method for forming multifunctional surfaces provides an effective means for immobilization of diverse molecules at close proximities. The multifunctional thin film has applications in bioelectronics, molecular electronics, clinical diagnostics, and chemical and biological sensing.

  17. Effect of CeO2 doping on catalytic activity of Fe2O3/gamma-Al2O(3) catalyst for catalytic wet peroxide oxidation of azo dyes.

    Science.gov (United States)

    Liu, Yan; Sun, Dezhi

    2007-05-08

    In order to find a catalyst with high activity and stability for catalytic wet peroxide oxidation (CWPO) process under normal condition, with Fe(2)O(3)/gamma-Al(2)O(3) and Fe(2)O(3)-CeO(2)/gamma-Al(2)O(3) catalysts prepared by impregnation method, the effect of CeO(2) doping on the structure and catalytic activity of Fe(2)O(3)/gamma-Al(2)O(3) for catalytic wet peroxide oxidation of azo dyes at 25 degrees C and atmospheric pressure is evaluated using BET, SEM, XRF, XRD, XPS and chemical analysis techniques, and test results show that, better dispersion and smaller size of Fe(2)O(3) crystal can be achieved by adding CeO(2), and the content of chemisorbed oxygen can also be increased on the surface of catalyst. CWPO experimental results indicate that azo dyes in simulated wastewater can be efficiently mineralized and the catalytic activity of Fe(2)O(3)-CeO(2)/gamma-Al(2)O(3) can be increased by about 10% compared with that of Fe(2)O(3)/gamma-Al(2)O(3) because of the promotion of the structural and redox properties of the ferric oxide by ceria doped. Leaching tests indicate that Fe(2)O(3)/gamma-Al(2)O(3) and Fe(2)O(3)-CeO(2)/gamma-Al(2)O(3) are stable with a negligible amount of irons found in the aqueous solution after reaction for 2h. It can therefore be concluded from results and discussion that in comparison with Fe(2)O(3)/gamma-Al(2)O(3), Fe(2)O(3)-CeO(2)/gamma-Al(2)O(3) is a suitable catalyst, which can effectively degrade contaminants at normal temperature and atmospheric pressure.

  18. 磁载光催化剂Ag-TiO2/ZnO/γ-Fe2O3的制备及其光催化性能%Preparation and Photocatalytic Activity of Ag-TiO2/ZnO/γ-Fe2O3 Magnetic Photocatalyst

    Institute of Scientific and Technical Information of China (English)

    侯林瑞; 原长洲; 彭秧

    2006-01-01

    采用溶胶-凝胶法在表面包覆了ZnO的磁基体γ-Fe2O3上负载TiO2,光催化还原法在其表面沉积Ag,得到了易于磁性固液分离的磁载Ag-TiO2/ZnO/γ-Fe2O3复合光催化剂. 通过XRD、EDX和TEM等测试技术对该复合催化剂进行了表征. 以可溶性染料亚甲基兰为降解对象,研究了ZnO的存在和Ag不同含量对复合光催化剂催化活性的影响及催化剂回收再利用的可行性. 结果表明,0.5%(质量分数)Ag-TiO2/ZnO/γ-Fe2O3(其中m (TiO2):m(ZnO):m(γ-Fe2O3)=14:3:3)的复合光催化剂具有最高的光催化活性,在3次循环使用后仍能保持较好的光催化性能.

  19. Study on preparation of solid superacid SO2-4/Fe2O3 and photocatalytic degradation of methyl orange%SO2-4/Fe2O3固体超强酸的制备及光催化降解甲基橙的研究

    Institute of Scientific and Technical Information of China (English)

    王占领

    2011-01-01

    The SO 4 /Fe2O3 solid superacid catalyst was prepared by chemical precipitating and soaking method, and the effect of photocatalytic degradation to methyl orange was studied with the single-factor experiment method. The results showed that when the catalyst quantity is 2g·L-1, Ph value is 6, the first concentration of methyl orange is 10mg·L-1 and reactive time is 90min, the degradation ratio of methyl orange is over 90%.%采用沉淀-浸渍法制备SO2-4/Fe2O3固体超强酸催化剂.通过单因素实验考察了SO2-4/Fe2O3光降解甲基橙的效果.结果表明,固体超强酸SO2-4/Fe2O3光催化降解甲基橙的最优反应条件是:溶液pH值为6,催化用量2g·L-1,甲基橙溶液初始浓度10mg·L-1,反应时间90min.在最优反应条件下,甲基橙的降解率可达90%以上.

  20. Influences of Fe2O3 Doping Concentration on Structure and Photorefractive Properties of Zn∶Fe∶LiNbO3 Crystals Grown by TSSG Method%Fe2O3的掺杂对TSSG法生长Zn:Fe:LiNbO3 晶体的结构和光折变性能的影响

    Institute of Scientific and Technical Information of China (English)

    孙志洁; 鲁玺丽; 李洪涛; 赵连城

    2007-01-01

    LiNbO3 crystals doped with the same concentration of ZnO and with the different concentration of Fe2O3 have been grown by a top-seeded-solution-growth (TSSG) method. The IR transmittance spectra, UV-Vis absorption spectra, lattice constants, and Curie temperature were measured. In two-wave coupling experiments, writing and erasure curves were measured, and writing time constants,erasure time constants, and maximum diffraction efficiency of the crystals were obtained from the curves. The influences of Fe2O3 doping concentration on photorefractive properties were studied.%本文利用TSSG方法生长了不同掺Fe2O3浓度的Zn∶Fe∶LiNbO3晶体,并对晶体进行了红外光谱、紫外光谱、晶格常数和居里温度的测试和分析.利用二波耦合实验测得的写入和擦除曲线,计算了晶体的写入时间常数、擦除时间常数和最大衍射效率.并讨论了Fe2O3的掺杂对材料结构和光折变性能的影响机制.

  1. 核壳结构γ-Fe2O3/SiO2纳米复合材料的合成与分析%Synthesis and study of core-shell γ-Fe2O3/SiO2 nano composite particles

    Institute of Scientific and Technical Information of China (English)

    陈磊; 景宜

    2013-01-01

    采用溶胶-凝胶法,以正硅酸乙酯(TEOS)为硅源,通过TEOS的水解和缩合制备核壳结构γ-Fe2O3/SiO2的纳米复合材料.利用正交试验与单因素实验,研究了γ-Fe2O3、TEOS、氨水的用量、醇水比、反应时间、反应温度和搅拌速率对纳米复合材料合成的影响,并且对合成产品进行TEM、XRD、DSC、FTIR、粒径分析仪等表征分析.结果发现,对纳米复合材料合成效果影响最大的因素是TEOS的用量,最佳工艺方案为γ-Fe2O3用量为0.06 g、TEOS 0.5 mL、氨水2 mL、醇水体积比为5∶1、反应时间为8h、反应温度为30 ℃、搅拌速率为150r/min;以最佳合成方案合成的核壳结构γ-Fe2O3/SiO2与y-Fe2O3相比,平均粒径减少34.1%,颗粒尺寸分布较为均匀,具有较好的分散性.%Core-shell structural γ-Fe2O3/SiO2 nano composite particles were prepared via hydrolysis and condensation by sol-gel method using TEOS as silica precursor.Orthogonal design and single factor experiment were utilized to study effect of seven factors on the synthesis of nano composite particles,such as the dosage of γ-Fe2O3,Ammonia water,TEOS,the ratio of alcohol to water,reaction time,reaction temperature and stirring speed.The synthesized products were characterized by transmission electron microscope (TEM),X-ray diffraction (XRD),infrared spectrometer (FTIR),differential scanning calorimetry (DSC) and particle size analyzer.The results showed that the dosage of TEOS had the most influence on the synthesis of core-shell structural γ-Fe2O3/SiO2 nanocomposite particles.The optimum conditions were as follows:γ-Fe2O30.06 g,TEOS 0.5 mL,ammonia 2 mL,the ratio of alcohol to water 5 ∶ 1,reaction time 8 h,reaction temperature 30 ℃ and stirring speed 150 r/min.Compared core-shell structural γ-Fe2O3/SiO2 with γ-Fe2O3,the average particle size was reduced by 34.1% and particle size distribution was more uniform,with good dispersion.

  2. e-HTiNbO5@Fe2 O3纳米复合材料的制备与结构特征%Preparation and Structural Characteristics of e-HTiNbO5@Fe2 O 3 Nanocomposite

    Institute of Scientific and Technical Information of China (English)

    王宁宁; 董锐; 王元; 何杰

    2014-01-01

    层状KTiNbO 5因具有离子可交换、层间结构均一可控等优点而引起了广泛的关注。采用高温固相法制备的KTiNbO 5为前驱体,经H +交换、剥离改性制备出 HTiNbO5纳米片并以其作为基体材料与Fe2 O3纳米粒子复合制备出e-HTiNbO5@Fe2 O3纳米复合材料。采用XRD、Raman、BET、HRTEM、TG-DSC和UV-vis DRS对样品的结构和光响应特征进行表征。结果表明,e-HTiNbO5@Fe2 O3保留了主体纳米片聚集体的孔隙结构特征,客体材料分散于主体材料表面,并与主体纳米片上的活性官能团之间发生相互作用,导致主体纳米片的热稳定性增加。另外,e-HTiNbO 5@Fe 2O 3的BET表面积明显增加的同时,其在可见光区有明显的吸收,禁带宽度为2.08 eV,该纳米复合材料在自然光辐射下可将乙硫醇光催化氧化为磺酸盐。%The nanocomposite e -HTiNbO5@Fe2 O3 was assembled from HTiNbO 5 nanosheet ( e -HTiNbO5 ) which was prepared by exfoliating HTiNbO 5 and Fe2O3 nanoparticles.The precursor HTiNbO5 was obtained by KTiNbO5 via a proton-exchange route .The as-prepared samples were characterized by means of XRD , LRS, BET, HRTEM, TG-DSC and UV-vis DRS.The results showed that the guest material (Fe 2O 3) was dispersed on e-HTiNbO 5.A significative interaction between Fe 2O 3 and the active groups on e-HTiNbO 5 was observed , and it results to a better thermal stability of the nanocomposite .e-HTiNbO 5@Fe 2O 3 has a higher BET surface area and the similar pore structure feature with the matrix e-HTiNbO5 .In addition, e-HTiNbO5@Fe2 O3 has an obvious absorbance for the visible light and a gap -energy of 2.08 eV.And it can oxidize EM to sulfonate un-der natural light irradiation .

  3. Structure and denitrification behaviors of Fe2O3-Cr2O3/TiO2 catalysts%Fe2O3-Cr2O3/TiO2系列催化剂的结构和脱硝性能

    Institute of Scientific and Technical Information of China (English)

    任晓光; 任超; 李富霞; 李鹏; 宋永吉

    2012-01-01

    研究以纳米TiO2为载体,浸渍负载过渡金属氧化物,以CO为还原剂的脱硝催化剂的脱硝性能。实验中以计算量的Ni(NO3)2和Fe(NO3)3混合溶液浸渍纳米TiO2粉末,室温下搅拌30 min至混合均匀,放入旋转蒸发器中,70℃下至水分蒸干为止;所得粉末在550℃下、空气气氛中焙烧4 h即得所需催化剂。用以上方法分别制备2%Fe2O3-10%Cr2O3/TiO2、4%Fe2O3-8%Cr2O3/TiO2、6%Fe2O3-6%Cr2O3/TiO2、8%Fe2O3-4%Cr2O3/TiO2与10%Fe2O3-2%Cr2O3/TiO2等5种催化剂样品。实验结果表明,制备的催化剂具有较好的结构,分散较为均匀。对于CO+NO反应,Fe2O3-Cr2O3/TiO2系列催化剂具有较好的催化活性,NO的转化率都达到了100%。其中,10%Fe2O3-2%Cr2O3/TiO2样品具有最好的低温活性,H2-TPR结果表明,这是由于10%Fe2O3-2%Cr2O3/TiO2催化剂更易于被CO预还原。%This work aimed to investigate the performance of a denitration catalyst,which uses nanometer TiO2 as support,transition metal oxides as active component and CO as reducer.Nanometer TiO2 powder was dipped by the mixture of Fe(NO3)3 and Cr(NO3)3,kept stirring for 30 min until well mixed at room temperature,and then it was evaporated to dryness in rotary evaporator at 70℃.The samples obtained with this process were calcined at 550℃ for 4 h in air atmosphere to prepare the catalysts.In this experiment,five catalysts produced by this method,2%Fe2O3-10%Cr2O3/TiO2,4%Fe2O3-8%Cr2O3/TiO2,6%Fe2O3-6%Cr2O3/TiO2,8%Fe2O3-4%Cr2O3/TiO2 and 10%Fe2O3-2%Cr2O3/TiO2,were investigated.Experimental results indicate that the Fe2O3-Cr2O3/TiO2 catalysts series,with excellent structure and dispersity,have great catalytic activity to the reaction NO+ CO and the conversion of NO reaches 100%.Of all the prepared catalysts,10%Fe2O3-2%Cr2O3/TiO2 catalyst shows the best activity at lower temperature,due to fact that it could more easily be pre-reduced by CO,which is proved by the H2-TPR results.

  4. Three-dimensional nanoporous Fe₂O₃/Fe₃C-graphene heterogeneous thin films for lithium-ion batteries.

    Science.gov (United States)

    Yang, Yang; Fan, Xiujun; Casillas, Gilberto; Peng, Zhiwei; Ruan, Gedeng; Wang, Gunuk; Yacaman, Miguel Jose; Tour, James M

    2014-04-22

    Three-dimensional self-organized nanoporous thin films integrated into a heterogeneous Fe2O3/Fe3C-graphene structure were fabricated using chemical vapor deposition. Few-layer graphene coated on the nanoporous thin film was used as a conductive passivation layer, and Fe3C was introduced to improve capacity retention and stability of the nanoporous layer. A possible interfacial lithium storage effect was anticipated to provide additional charge storage in the electrode. These nanoporous layers, when used as an anode in lithium-ion batteries, deliver greatly enhanced cyclability and rate capacity compared with pristine Fe2O3: a specific capacity of 356 μAh cm(-2) μm(-1) (3560 mAh cm(-3) or ∼1118 mAh g(-1)) obtained at a discharge current density of 50 μA cm(-2) (∼0.17 C) with 88% retention after 100 cycles and 165 μAh cm(-2) μm(-1) (1650 mAh cm(-3) or ∼518 mAh g(-1)) obtained at a discharge current density of 1000 μA cm(-2) (∼6.6 C) for 1000 cycles were achieved. Meanwhile an energy density of 294 μWh cm(-2) μm(-1) (2.94 Wh cm(-3) or ∼924 Wh kg(-1)) and power density of 584 μW cm(-2) μm(-1) (5.84 W cm(-3) or ∼1834 W kg(-1)) were also obtained, which may make these thin film anodes promising as a power supply for micro- or even nanosized portable electronic devices.

  5. Thin film superfluid optomechanics

    CERN Document Server

    Baker, Christopher G; McAuslan, David L; Sachkou, Yauhen; He, Xin; Bowen, Warwick P

    2016-01-01

    Excitations in superfluid helium represent attractive mechanical degrees of freedom for cavity optomechanics schemes. Here we numerically and analytically investigate the properties of optomechanical resonators formed by thin films of superfluid $^4$He covering micrometer-scale whispering gallery mode cavities. We predict that through proper optimization of the interaction between film and optical field, large optomechanical coupling rates $g_0>2\\pi \\times 100$ kHz and single photon cooperativities $C_0>10$ are achievable. Our analytical model reveals the unconventional behaviour of these thin films, such as thicker and heavier films exhibiting smaller effective mass and larger zero point motion. The optomechanical system outlined here provides access to unusual regimes such as $g_0>\\Omega_M$ and opens the prospect of laser cooling a liquid into its quantum ground state.

  6. Thin film ceramic thermocouples

    Science.gov (United States)

    Gregory, Otto (Inventor); Fralick, Gustave (Inventor); Wrbanek, John (Inventor); You, Tao (Inventor)

    2011-01-01

    A thin film ceramic thermocouple (10) having two ceramic thermocouple (12, 14) that are in contact with each other in at least on point to form a junction, and wherein each element was prepared in a different oxygen/nitrogen/argon plasma. Since each element is prepared under different plasma conditions, they have different electrical conductivity and different charge carrier concentration. The thin film thermocouple (10) can be transparent. A versatile ceramic sensor system having an RTD heat flux sensor can be combined with a thermocouple and a strain sensor to yield a multifunctional ceramic sensor array. The transparent ceramic temperature sensor that could ultimately be used for calibration of optical sensors.

  7. Biomimetic thin film deposition

    Science.gov (United States)

    Rieke, P. C.; Campbell, A. A.; Tarasevich, B. J.; Fryxell, G. E.; Bentjen, S. B.

    1991-04-01

    Surfaces derivatized with organic functional groups were used to promote the deposition of thin films of inorganic minerals. These derivatized surfaces were designed to mimic the nucleation proteins that control mineral deposition during formation of bone, shell, and other hard tissues in living organisms. By the use of derivatized substrates control was obtained over the phase of mineral deposited, the orientation of the crystal lattice and the location of deposition. These features are of considerable importance in many technically important thin films, coatings, and composite materials. Methods of derivatizing surfaces are considered and examples of controlled mineral deposition are presented.

  8. Superparamagnetic gamma-Fe2O3@SiO2 nanoparticles: a novel support for the immobilization of [VO(acac)2].

    Science.gov (United States)

    Pereira, Clara; Pereira, André M; Quaresma, Pedro; Tavares, Pedro B; Pereira, Eulália; Araújo, João P; Freire, Cristina

    2010-03-21

    This work reports a detailed investigation about the physicochemical properties of superparamagnetic gamma-Fe(2)O(3) nanomaterial synthesized by the co-precipitation method and coated with two silica shells, and its application as support for the immobilization of oxovanadium(IV) acetylacetonate ([VO(acac)(2)]). The influence of the silica coatings on the surface composition and physicochemical interactions of the core-shell nanocomposites is discussed based on the combination of several techniques: electron microscopy techniques (SEM and TEM with EDS), DLS, powder XRD, XPS, FTIR and magnetic characterization. The identity of the iron oxide, gamma-Fe(2)O(3), was confirmed by XPS, FTIR and by the Rietveld refinement of the PXRD pattern. The results obtained by electron microscopy techniques, XRD and magnetization indicated that the gamma-Fe(2)O(3) nanoparticles are superparamagnetic and present an average size of approximately 6.5 nm. The first silica coating leads to a core-shell nanomaterial with an average particle size of 21 nm and upon the second coating, the average size increases to 240 nm. Magnetic measurements revealed that the silica-coated nanomaterials maintain the superparamagnetic state at room temperature, although with an expected reduction of the magnetization saturation due to the increase of the silica shell thickness. Furthermore, a numerical fit of the temperature dependence of magnetization was performed to determine the core size distribution and the effect of the silica coatings on the dipolar magnetic interactions. [VO(acac)(2)] was covalently immobilized on the surface of the silica-coated magnetic nanoparticles functionalized with amine groups, as confirmed by chemical analysis and XPS. In a proof-of-principle experiment, we demonstrated the catalytic performance of the novel magnetic hybrid nanomaterial in the epoxidation of geraniol, which presented high selectivity towards the 2,3-epoxygeraniol product and easy recovery by magnetic

  9. Arsenite removal from aqueous solutions by γ-Fe2O3-TiO2 magnetic nanoparticles through simultaneous photocatalytic oxidation and adsorption.

    Science.gov (United States)

    Yu, Lian; Peng, Xianjia; Ni, Fan; Li, Jin; Wang, Dongsheng; Luan, Zhaokun

    2013-02-15

    A novel Fe-Ti binary oxide magnetic nanoparticles which combined the photocatalytic oxidation property of TiO(2) and the high adsorption capacity and magnetic property of γ-Fe(2)O(3) have been synthesized using a coprecipitation and simultaneous oxidation method. The as-prepared samples were characterized by powder XRD, TEM, TG-DTA, VSM and BET methods. Photocatalytic oxidation of arsenite, the effect of solution pH values and initial As(III) concentration on arsenite removal were investigated in laboratory experiments. Batch experimental results showed that under UV light, As(III) can be efficiently oxidized to As(V) by dissolved O(2) in γ-Fe(2)O(3)-TiO(2) nanoparticle suspensions at various pH values. At the same time, As(V) was effectively removed by adsorption onto the surface of nanoparticles. The maximum removal capability of the nano-material for arsenite was 33.03 mg/g at pH 7.0. Among all the common coexisting ions investigated, phosphate was the greatest competitor with arsenic f