Magnetic ordered mesoporous Fe3O4/CeO2 composites with synergy of adsorption and Fenton catalysis

NASA Astrophysics Data System (ADS)

Li, Keyan; Zhao, Yongqin; Song, Chunshan; Guo, Xinwen

2017-12-01

Magnetic Fe3O4/CeO2 composites with highly ordered mesoporous structure and large surface area were synthesized by impregnation-calcination method, and the mesoporous CeO2 as support was synthesized via the hard template approach. The composition, morphology and physicochemical properties of the materials were characterized by XRD, SEM, TEM, XPS, Raman spectra and N2 adsorption/desorption analysis. The mesoporous Fe3O4/CeO2 composite played a dual-function role as both adsorbent and Fenton-like catalyst for removal of organic dye. The methylene blue (MB) removal efficiency of mesoporous Fe3O4/CeO2 was much higher than that of irregular porous Fe3O4/CeO2. The superior adsorption ability of mesoporous materials was attributed to the abundant oxygen vacancies on the surface of CeO2, high surface area and ordered mesoporous channels. The good oxidative degradation resulted from high Ce3+ content and the synergistic effect between Fe and Ce. The mesoporous Fe3O4/CeO2 composite presented low metal leaching (iron 0.22 mg L-1 and cerium 0.63 mg L-1), which could be ascribed to the strong metal-support interactions for dispersion and stabilization of Fe species. In addition, the composite can be easily separated from reaction solution with an external magnetic field due to its magnetic property, which is important to its practical applications.

Three-dimensional Fe3O4-graphene macroscopic composites for arsenic and arsenate removal.

PubMed

Guo, Liangqia; Ye, Peirong; Wang, Jing; Fu, Fengfu; Wu, Zujian

2015-11-15

3D graphene macroscopic gel synthesized via self-assembly of GO nanosheets under basic conditions at low temperature is modified with polydopamine and Fe3O4 nanoparticles. The modification of polydopamine can not only strengthen the 3D graphene-based macroscopic architecture but also enhance the loadage and binding ability of Fe3O4 nanoparticles. The synthesized 3D Fe3O4-graphene macroscopic composites are characterized by SEM, XRD, XPS, BET, Raman and magnetic property and used as a versatile adsorbent for sub-ppm concentration of As(III) and As(V) removal from aqueous solutions. The experimental results suggest that the synthesized 3D Fe3O4-graphene macroscopic composites are promising for treating low concentration of arsenic contaminated water. Copyright © 2015 Elsevier B.V. All rights reserved.

Surface enhanced Raman scattering activity of dual-functional Fe3O4/Au composites

NASA Astrophysics Data System (ADS)

Wang, Li-Ping; Huang, Yu-Bin; Lai, Ying-Huang

2018-03-01

There is a high demand for multifunctional materials that can integrate sample collection and sensing. In this study, magnetic Fe3O4 clusters were fabricated using a simple solvent-thermal method. The effect of the reductant (sodium citrate, SC) on the structure and morphology of Fe3O4 was examined by the variation in the reagent amount. The resulting Fe3O4 clusters were functionalized with 3-aminopropyltriethoxysilane (APTES) to anchor Au nanoparticles to its surface. The fabricated composites were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), and a superconducting quantum interference device (SQUID) magnetometer. Dual-functional Fe3O4/Au clusters were obtained, effectively combining magnetic and plasmonic optical properties. The magnetic Fe3O4 cluster cores permitted the adsorption of the probe molecules, while sample concentration and collection were carried out under an external magnetic field. In addition, 4-nitrothiophenol (4-NTP) was chosen as the probe molecule to examine the analyte concentration ability and surface-enhanced Raman scattering (SERS) activity of the Fe3O4/Au composites. The results indicated that the Fe3O4/Au clusters exhibit a prominent SERS effect. The best 4-NTP detection limit obtained was 1 × 10-8 M, with a corresponding SERS analytical enhancement factor (AEF) exceeding 2 × 105.

An effective approach to study the biocompatibility of Fe3O4 nanoparticles, graphene and their nanohybrid composite

NASA Astrophysics Data System (ADS)

Singh, Ashwani Kumar; Singh, Pallavi; Verma, Rajiv Kumar; Yadav, Suresh; Singh, Kedar; Srivastava, Amit

2018-02-01

The present manuscript describes a simple, facile and effective solvothermal route to synthesize Fe3O4 nanoparticles (Fe3O4 NPs), reduced graphene oxide nanosheets (rGO NSs) and Fe3O4/reduced graphene oxide nanohybrid composite (Fe3O4/rGO nanohybrid composite) and subsequently examines their comparative biocompatibilities. The as-obtained Fe3O4 NPs, rGO NSs and Fe3O4/rGO nanohybrid composite have been characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and Raman spectroscopy. The XRD studies and scanning electron microscope confirmed the proper phase formation and the surface morphology of the as-synthesized products, respectively. The Raman spectra of Fe3O4 NPs show the strongest peak at 673 cm-1 which can be assigned to A1g peak of bare Fe3O4 NPs and it complements the XRD studies. Furthermore, the increment in the I D/I G ratio in the Fe3O4/rGO nanohybrid composite suggests the creation of defects in graphene sheets due to strain caused by Fe3O4 NPs. The biocompatibility of these samples has been tested using Lung cancer cell line H1299 through MTT assay. The MTT assay reveals that the nanohybrid composite endows more biocompatible and effectiveness than rGO NSs and Fe3O4 NPs individually, as anti-proliferative agent for cancer treatment.

Enhanced electromagnetic interference shielding properties of carbon fiber veil/Fe3O4 nanoparticles/epoxy multiscale composites

NASA Astrophysics Data System (ADS)

Chen, Wei; Wang, Jun; Zhang, Bin; Wu, Qilei; Su, Xiaogang

2017-12-01

The multiscale approach has been adapted to enhance the electromagnetic interference shielding properties of carbon fiber (CF) veil epoxy-based composites. The Fe3O4 nanoparticles (NPs) were homogeneously dispersed in the epoxy matrix after surface modification by using silane coupling agent. The CF veil/Fe3O4 NPs/epoxy multiscale composites were manufactured by impregnating the CF veils with Fe3O4 NPs/epoxy mixture to prepare prepreg followed by vacuum bagging process. The electromagnetic interference shielding properties combined with the complex permittivity and complex permeability of the composites were investigated in the X-band (8.2-12.4 GHz) range. The total shielding effectiveness (SET) increases with increasing Fe3O4 NPs loadings and the maximum SET is 51.5 dB at low thickness of 1 mm. The incorporation of Fe3O4 NPs into the composites enhances the complex permittivity and complex permeability thus enhancing the electromagnetic wave absorption capability. The increased SET dominated by absorption loss SEA is attributed to the enhanced magnetic loss and dielectric loss generated by Fe3O4 NPs and multilayer construction of the composites. The microwave conductivity increases and the skin depth decreases with increasing Fe3O4 NPs loadings.

Micro-tube biotemplate synthesis of Fe3O4/C composite as anode material for lithium-ion batteries

NASA Astrophysics Data System (ADS)

Du, Jun; Ding, Yu; Guo, Liangui; Wang, Li; Fu, Zhengbing; Qin, Caiqin; Wang, Feng; Tao, Xinyong

2017-12-01

Kapok fibres were used as micro-tube biotemplate and bio-carbon source to synthesise Fe3O4/C composites, which were then utilised as anode materials. Fe3O4 nanoparticles were grown uniformly onto the external surface and internal channel of kapok carbon fibres. The flexibility, high specific surface area and electronic conduction of kapok fibres can buffer the volume expansion as well as inhibit the aggregation of Fe3O4 nanoparticles. Thus, the electrical integrity and structural of the Fe3O4/C composites electrode during lithiation/delithiation processes. The Fe3O4/C composites electrode delivers a high reversible capacity of 596 mA h g-1 after 100 cycles and an ultra-high coulombic efficiency approaching 100%. The high electrochemical performance of the Fe3O4/C composites can be caused by the synergistic effect of the Fe3O4 nanoparticles and the structure of kapok carbon fibres.

Preparation and characterization of Fe3O4@Au-C225 composite targeted nanoparticles for MRI of human glioma

PubMed Central

Ge, Yaoqi; Zhong, Yuejiao; Ji, Guozhong; Lu, Qianling; Dai, Xinyu; Guo, Zhirui; Zhang, Peng; Peng, Gang; Zhang, Kangzhen; Li, Yuntao

2018-01-01

Objective To study the characterization of Fe3O4@Au-C225 composite targeted MNPs. Methods Fe3O4@Au-C225 was prepared by the absorption method. The immunosorbent assay was used to evaluate its absorption efficiency at C225 Fc. ZETA SIZER3000 laser particle size analyzer, ultraviolet photometer and its characteristics were analyzed by VSM. the targeting effect of Fe3O4@Au-C225 composite targeted MNPs on U251 cells in vitro were detected by 7.0 Tesla Micro-MR; and subcutaneous transplanted human glioma in nude mice were performed the targeting effect in vivo after tail vein injection of Fe3O4@Au-C225 composite targeted MNPs by MRI. Results The self-prepared Fe3O4@Au composite MNPs can adsorb C225 with high efficiency of adsorption so that Fe3O4@Au-C225 composite targeted MNPs were prepared successfully. Fe3O4@Au-C225 composite targeted MNPs favorably targeted human glioma cell line U251 in vitro; Fe3O4@Au-C225 composite targeted MNPs have good targeting ability to xenografted glioma on nude mice in vivo, and can be traced by MRI. Conclusion The Fe3O4@Au-C225 composite targeted MNPs have the potential to be used as a tracer for glioma in vivo. PMID:29652919

Preparation and characterization of Fe3O4@Au-C225 composite targeted nanoparticles for MRI of human glioma.

PubMed

Ge, Yaoqi; Zhong, Yuejiao; Ji, Guozhong; Lu, Qianling; Dai, Xinyu; Guo, Zhirui; Zhang, Peng; Peng, Gang; Zhang, Kangzhen; Li, Yuntao

2018-01-01

To study the characterization of Fe3O4@Au-C225 composite targeted MNPs. Fe3O4@Au-C225 was prepared by the absorption method. The immunosorbent assay was used to evaluate its absorption efficiency at C225 Fc. ZETA SIZER3000 laser particle size analyzer, ultraviolet photometer and its characteristics were analyzed by VSM. the targeting effect of Fe3O4@Au-C225 composite targeted MNPs on U251 cells in vitro were detected by 7.0 Tesla Micro-MR; and subcutaneous transplanted human glioma in nude mice were performed the targeting effect in vivo after tail vein injection of Fe3O4@Au-C225 composite targeted MNPs by MRI. The self-prepared Fe3O4@Au composite MNPs can adsorb C225 with high efficiency of adsorption so that Fe3O4@Au-C225 composite targeted MNPs were prepared successfully. Fe3O4@Au-C225 composite targeted MNPs favorably targeted human glioma cell line U251 in vitro; Fe3O4@Au-C225 composite targeted MNPs have good targeting ability to xenografted glioma on nude mice in vivo, and can be traced by MRI. The Fe3O4@Au-C225 composite targeted MNPs have the potential to be used as a tracer for glioma in vivo.

Magneto electric effects in BaTiO3-CoFe2O4 bulk composites

NASA Astrophysics Data System (ADS)

Agarwal, Shivani; Caltun, O. F.; Sreenivas, K.

2012-11-01

Influence of a static magnetic field (HDC) on the hysteresis and remanence in the longitudinal and transverse magneto electric voltage coefficients (MEVC) observed in [BaTiO3]1-x-[CoFe2O4]x bulk composites are analyzed. Remanence in MEVC at zero bias (HDC=0) is stronger in the transverse configuration over the longitudinal case. The observed hysteretic behavior in MEVC vs. HDC is correlated with the changes observed in the magnetostriction characteristics (λ and dλ/dH) reported for [BaTiO3]1-x-[CoFe2O4]x bulk composites.

Facile preparation of magnetic mesoporous Fe3O4/C/Cu composites as high performance Fenton-like catalysts

NASA Astrophysics Data System (ADS)

Li, Keyan; Zhao, Yongqin; Janik, Michael J.; Song, Chunshan; Guo, Xinwen

2017-02-01

Fe-Cu composites with different compositions and morphologies were synthesized by a hydrothermal method combined with precursor thermal transformation. γ-Fe2O3/CuO and α-Fe2O3/CuO were obtained by calcining the Fe and Cu tartrates under air atmosphere at 350 °C and 500 °C, respectively, while Fe3O4/C/Cu was obtained by calcining the tartrate precursor under N2 atmosphere at 500 °C. The Fe3O4/C/Cu composite possessed mesoporous structure and large surface area up to 133 m2 g-1. The Fenton catalytic performance of Fe3O4/C/Cu composite was closely related to the Fe/Cu molar ratio, and only proper amounts of Fe and Cu exhibited a synergistic enhancement in Fenton catalytic activity. Cu inclusion reduced Fe3+ to Fe2+, which accelerated the Fe3+/Fe2+ cycles and favored H2O2 decomposition to produce more hydroxyl radicals for methylene blue (MB) oxidation. Due to the photo-reduction of Fe3+ and Cu2+, the Fenton catalytic performance was greatly improved when amending with visible light irradiation in the Fe3O4/C/Cu-H2O2 system, and MB (100 mg L-1) was nearly removed within 60 min. The Fe3O4/C/Cu composite showed good recyclability and could be conveniently separated by an applied magnetic field. Compared with conventional methods for mesoporous composite construction, the thermolysis method using mixed metal tartrates as precursors has the advantages of easy preparation and low cost. This strategy provides a facile, cheap and green method for the synthesis of mesoporous composites as excellent Fenton-like catalysts, without any additional reductants or organic surfactants.

One-step solvothermal synthesis of magnetic Fe3O4-graphite composite for Fenton-like degradation of levofloxacin.

PubMed

Wang, Long; Zhao, Qi; Hou, Juan; Yan, Jin; Zhang, Fengshuang; Zhao, Jiahui; Ding, Hong; Li, Yi; Ding, Lan

2016-01-01

A novel Fe3O4-graphite composite was prepared, characterized, and investigated as a heterogeneous Fenton-like catalyst for the degradation of levofloxacin (LEV) in an aqueous solution. The results revealed that the Fe3O4-graphite composite exhibited excellent properties for the degradation and mineralization of LEV, achieving a nearly complete degradation of 50 mg L(-1) LEV in 15 min and 48% of total organic carbon removal in 60 min under optimal conditions. A large electronic conjugation structure exists in graphite, which may lead to the fast production of •OH radical species because of the easy reduction of Fe(III) to Fe(II). In addition, we observed that the graphite can degrade LEV in the presence of H2O2. Therefore, the synergistic results of the graphite structure and Fe3O4 magnetic nanoparticles (MNPs) may contribute to the high catalytic activity of the Fe3O4-graphite composite. Compared with pure Fe3O4 MNPs, lesser iron leaching of the Fe3O4-graphite composite was observed during the degradation of LEV. The degradation efficiency of LEV remained approximately 80% at the fifth recycling run, which indicates that the Fe3O4-graphite composite has potential applications in water treatment for removing organic pollutants.

Magnetic properties of mixed spinel BaTiO{sub 3}-NiFe{sub 2}O{sub 4} composites

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sarkar, Babusona; Dalal, Biswajit; Dev Ashok, Vishal

2014-03-28

Solid solution of nickel ferrite (NiFe{sub 2}O{sub 4}) and barium titanate (BaTiO{sub 3}), (100-x)BaTiO{sub 3}–(x) NiFe{sub 2}O{sub 4} has been prepared by solid state reaction. Compressive strain is developed in NiFe{sub 2}O{sub 4} due to mutual structural interaction across the interface of NiFe{sub 2}O{sub 4} and BaTiO{sub 3} phases. Quantitative analysis of X-ray diffraction and X-ray photo electron spectrum suggest mixed spinel structure of NiFe{sub 2}O{sub 4}. A systematic study of composition dependence of composite indicates BaTiO{sub 3} causes a random distribution of Fe and Ni cations among octahedral and tetrahedral sites during non-equilibrium growth of NiFe{sub 2}O{sub 4}. Themore » degree of inversion decreases monotonically from 0.97 to 0.75 with increase of BaTiO{sub 3} content. Temperature dependence of magnetization has been analyzed by four sublattice model to describe complex magnetic exchange interactions in mixed spinel phase. Curie temperature and saturation magnetization decrease with increase of BaTiO{sub 3} concentration. Enhancement of strain and larger occupancy of Ni{sup 2+} at tetrahedral site increase coercivity up to 200 Oe. Magnetostructual coupling induced by BaTiO{sub 3} improves coercivity in NiFe{sub 2}O{sub 4}. An increase in the demagnetization and homogeneity in magnetization process in NiFe{sub 2}O{sub 4} is observed due to the interaction with diamagnetic BaTiO{sub 3}.« less

Magnetic, local ferroelectricity and magnetodielectric properties of NiFe2O4-poly (vinylidene-fluoride)-BaTiO3 composite film

NASA Astrophysics Data System (ADS)

Kumar, Amit; Yadav, K. L.

2016-04-01

We report the magnetic, dielectric, and magnetoelctric properties of NiFe2O4-poly (vinylidene-fluoride)-BaTiO3 composite film. The coercive field (±2H c ˜ 344 Oe) and remnant magnetization (M r ˜ 6.1 emu g-1) were observed at room temperature. The dielectric permittivity at room temperature (ɛ‧RT ˜ 281) was found to decrease with increase in frequency. The magnetocapacitance was found to be ˜5.9% at an applied dc magnetic field of 8 kOe (frequency = 1 kHz). Magnetoelectric coupling coefficient (α E ˜ 4.1 mV cm-1 Oe-1) measured by dynamic method (at ac magnetic field = 30 Oe) is observed higher (two times) than those reported for some materials. In addition, we have observed the image of ferroelectric domain using piezoelectric force microscopy at room temperature. Large magnetodielectric/magnetoelectric response in this composite is possibly a result of the effective mechanical interaction between NiFe2O4 and BaTiO3 through the polymer matrix.

Mössbauer Studies of Core-Shell FeO/Fe3O4 Nanoparticles

NASA Astrophysics Data System (ADS)

Kamzin, A. S.; Valiullin, A. A.; Khurshid, H.; Nemati, Z.; Srikanth, H.; Phan, M. H.

2018-02-01

FeO/Fe3O4 nanoparticles were synthesized by thermal decomposition. Electron microscopy revealed that these nanoparticles were of the core-shell type and had a spherical shape with an average size of 20 nm. It was found that the obtained FeO/Fe3O4 nanoparticles had exchange coupling. The effect of anisotropy on the efficiency of heating (hyperthermic effect) of FeO/Fe3O4 nanoparticles by an external alternating magnetic field was examined. The specific absorption rate (SAR) of the studied nanoparticles was 135 W/g in the experiment with an external alternating magnetic field with a strength of 600 Oe and a frequency of 310 kHz. These data led to an important insight: the saturation magnetization is not the only factor governing the SAR, and the efficiency of heating of magnetic FeO/Fe3O4 nanoparticles may be increased by enhancing the effective anisotropy. Mössbauer spectroscopy of the phase composition of the synthesized nanoparticles clearly revealed the simultaneous presence of three phases: magnetite Fe3O4, maghemite γ-Fe2O3, and wustite FeO.

Synthesis of magnetic Bi2O2CO3/ZnFe2O4 composite with improved photocatalytic activity and easy recyclability

NASA Astrophysics Data System (ADS)

Liu, Yumin; Ren, Hao; Lv, Hua; Guang, Jing; Cao, Yafei

2018-03-01

Magnetic Bi2O2CO3/ZnFe2O4 heterojunction photocatalysts with varying content of ZnFe2O4 were constructed by modifying Bi2O2CO3 nanosheets with mesoporous ZnFe2O4 nanoparticles. The photoactivity of the products was investigated by decomposing RhodamineB (RhB) and it was found that the photoactivity of Bi2O2CO3/ZnFe2O4 composite was closely related to the loading amount of ZnFe2O4. Under simulant sunlight irradiation, the optimum photoactivity of Bi2O2CO3/ZnFe2O4 composite was almost 2.3 and 2.1 times higher than that by bare ZnFe2O4 and Bi2O2CO3, respectively. The improved photoactivity resulted from the synergistic effect of Bi2O2CO3 and ZnFe2O4, which not only extended the photoabsorption region but also significantly facilitated the interfacial charge transfer. Besides the high photocatalytic performance, Bi2O2CO3/ZnFe2O4 composite also exhibited excellent stable and recycling properties, which enabled it have great potential in a long-term practical use.

A chemiluminescence biosensor based on the adsorption recognition function between Fe3O4@SiO2@GO polymers and DNA for ultrasensitive detection of DNA

NASA Astrophysics Data System (ADS)

Sun, Yuanling; Li, Jianbo; Wang, Yanhui; Ding, Chaofan; Lin, Yanna; Sun, Weiyan; Luo, Chuannan

2017-05-01

In this work, a chemiluminescence (CL) biosensor was prepared for ultrasensitive determination of deoxyribonucleic acid (DNA) based on the adsorption recognition function between core-shell Fe3O4@SiO2 - graphene oxide (Fe3O4@SiO2@GO) polymers and DNA. The Fe3O4@SiO2@GO polymers were composed by GO and magnetite nanoparticles. And the core-shell polymers were confirmed by Scanning Electron Microscope (SEM), X-Ray Powder Diffraction (XRD) and Fourier Transform Infrared (FTIR). Then Fe3O4@SiO2@GO was modified by DNA. Based on the principle of complementary base, Fe3O4@SiO2@GO-DNA was introduced to the CL system and the selectivity, sensitivity of DNA detection was significantly improved. The adsorption properties of Fe3O4@SiO2@GO to DNA were researched through the adsorption equilibrium, adsorption kinetic and thermodynamics. Under optimized CL conditions, DNA could be assayed with the linear concentration range of 5.0 × 10- 12-2.5 × 10- 11 mol/L. The detection limit was 1.7 × 10- 12 mol/L (3δ) and the relative standard deviation (RSD) was 3.1%. The biosensor was finally used for the determination of DNA in laboratory samples and recoveries ranged from 99% to 103%. The satisfactory results revealed the potential application of Fe3O4@SiO2@GO-DNA-CL biosensor in the diagnosis and the treatment of human genetic diseases.

A chemiluminescence biosensor based on the adsorption recognition function between Fe3O4@SiO2@GO polymers and DNA for ultrasensitive detection of DNA.

PubMed

Sun, Yuanling; Li, Jianbo; Wang, Yanhui; Ding, Chaofan; Lin, Yanna; Sun, Weiyan; Luo, Chuannan

2017-05-05

In this work, a chemiluminescence (CL) biosensor was prepared for ultrasensitive determination of deoxyribonucleic acid (DNA) based on the adsorption recognition function between core-shell Fe 3 O 4 @SiO 2 - graphene oxide (Fe 3 O 4 @SiO 2 @GO) polymers and DNA. The Fe 3 O 4 @SiO 2 @GO polymers were composed by GO and magnetite nanoparticles. And the core-shell polymers were confirmed by Scanning Electron Microscope (SEM), X-Ray Powder Diffraction (XRD) and Fourier Transform Infrared (FTIR). Then Fe 3 O 4 @SiO 2 @GO was modified by DNA. Based on the principle of complementary base, Fe 3 O 4 @SiO 2 @GO-DNA was introduced to the CL system and the selectivity, sensitivity of DNA detection was significantly improved. The adsorption properties of Fe 3 O 4 @SiO 2 @GO to DNA were researched through the adsorption equilibrium, adsorption kinetic and thermodynamics. Under optimized CL conditions, DNA could be assayed with the linear concentration range of 5.0×10 -12 -2.5×10 -11 mol/L. The detection limit was 1.7×10 -12 mol/L (3δ) and the relative standard deviation (RSD) was 3.1%. The biosensor was finally used for the determination of DNA in laboratory samples and recoveries ranged from 99% to 103%. The satisfactory results revealed the potential application of Fe 3 O 4 @SiO 2 @GO-DNA-CL biosensor in the diagnosis and the treatment of human genetic diseases. Copyright © 2017 Elsevier B.V. All rights reserved.

Synthesis of Cu-Fe{sub 3}O{sub 4}@graphene composite: A magnetically separable and efficient catalyst for the reduction of 4-nitrophenol

DOE Office of Scientific and Technical Information (OSTI.GOV)

Xu, Ran; Bi, Huiping, E-mail: hpbi@njust.edu.cn; He, Guangyu

2014-09-15

Highlights: • The Cu-Fe{sub 3}O{sub 4}@GE composite was prepared by one-step solvent–thermal method. • The Cu-Fe{sub 3}O{sub 4}@GE composite exhibited the highest catalytic activity with excellent stability. • The Cu-Fe{sub 3}O{sub 4}@GE composite was magnetically separable. - Abstract: In this work, the Cu-Fe{sub 3}O{sub 4}@GE composite was prepared easily by a one-step solvent–thermal method, which achieved the formation of Cu nanoparticles (Cu NPs), Fe{sub 3}O{sub 4} nanoparticles (Fe{sub 3}O{sub 4} NPs) and reduction of GO simultaneously. The morphology and structure of the composite was fully characterized by means of X-ray diffraction (XRD), Fourier transformed infrared (FTIR) spectroscopy, transmission electron microscopymore » (TEM). The time-dependent adsorption spectra of the reaction mixture was measured by UV–vis absorption spectroscopy. The results demonstrated that the Cu NPs and Fe{sub 3}O{sub 4} NPs were densely and evenly deposited on the graphene (GE) sheets. It was found that the Cu-Fe{sub 3}O{sub 4}@GE composite exhibited high catalytic activities on the reduction of p-nitrophenol to p-aminophenol. Furthermore, the composite catalyst can be easily recovered due to its magnetic separability and high stability.« less

Rapid removal of uranium from aqueous solutions using magnetic Fe3O4@SiO2 composite particles.

PubMed

Fan, Fang-Li; Qin, Zhi; Bai, Jing; Rong, Wei-Dong; Fan, Fu-You; Tian, Wei; Wu, Xiao-Lei; Wang, Yang; Zhao, Liang

2012-04-01

Rapid removal of U(VI) from aqueous solutions was investigated using magnetic Fe(3)O(4)@SiO(2) composite particles as the novel adsorbent. Batch experiments were conducted to study the effects of initial pH, amount of adsorbent, shaking time and initial U(VI) concentrations on uranium sorption efficiency as well as the desorbing of U(VI). The sorption of uranium on Fe(3)O(4)@SiO(2) composite particles was pH-dependent, and the optimal pH was 6.0. In kinetics studies, the sorption equilibrium can be reached within 180 min, and the experimental data were well fitted by the pseudo-second-order model, and the equilibrium sorption capacities calculated by the model were almost the same as those determined by experiments. The Langmuir sorption isotherm model correlates well with the uranium sorption equilibrium data for the concentration range of 20-200 mg/L. The maximum uranium sorption capacity onto magnetic Fe(3)O(4)@SiO(2) composite particles was estimated to be about 52 mg/g at 25 °C. The highest values of uranium desorption (98%) was achieved using 0.01 M HCl as the desorbing agent. Fe(3)O(4)@SiO(2) composite particles showed a good selectivity for uranium from aqueous solution with other interfering cation ions. Present study suggested that magnetic Fe(3)O(4)@SiO(2) composite particles can be used as a potential adsorbent for sorption uranium and also provided a simple, fast separation method for removal of heavy metal ion from aqueous solution. Copyright © 2011 Elsevier Ltd. All rights reserved.

Synthesis of Fe3O4/Polyacrylonitrile Composite Electrospun Nanofiber Mat for Effective Adsorption of Tetracycline.

PubMed

Liu, Qing; Zhong, Lu-Bin; Zhao, Quan-Bao; Frear, Craig; Zheng, Yu-Ming

2015-07-15

Novel Fe3O4/polyacrylonitrile (PAN) composite nanofibers (NFs) were prepared by a simple two-step process, an electrospinning and solvothermal method. Characterization by field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM) demonstrated formation of a uniform nanoparticles coating (about 20 nm in thickness) on the PAN nanofiber backbone. The coating was constructed by well-crystallized cubic phase Fe3O4 nanoparticles as examined by X-ray diffraction spectroscopy (XRD). The coating doubled the specific surface area of NFs, from 8.4 to 17.8 m2 g(-1), as confirmed by nitrogen sorption isotherm analysis. To evaluate the feasibility of Fe3O4/PAN composite NFs as a potential adsorbent for antibiotic removal, batch adsorption experiments were conducted using tetracycline (TC) as the model antibiotic molecule. The results showed that Fe3O4/PAN composite NFs were effective in removing TC with no impactful loss of Fe in the pH regime of environmental interest (5-8). The adsorption of TC onto Fe3O4/PAN composite NFs better fitted the pseudo-second-order kinetics model, and the maximum adsorption capacity calculated from Langmuir isotherm model was 257.07 mg g(-1) at pH 6. The composite NFs also exhibited good regenerability over repeated adsorption/desorption cycles. Surface complexation between TC and the composite NFs contributed most to the adsorption as elucidated by X-ray photoelectron spectroscopy (XPS). This highly effective and novel adsorbent can be easily modularized and separated, promising its huge potential in drinking and wastewater treatment for antibiotic removal.

Efficient reduced graphene oxide grafted porous Fe3O4 composite as a high performance anode material for Li-ion batteries.

PubMed

Bhuvaneswari, Subramani; Pratheeksha, Parakandy Muzhikara; Anandan, Srinivasan; Rangappa, Dinesh; Gopalan, Raghavan; Rao, Tata Narasinga

2014-03-21

Here, we report facile fabrication of Fe3O4-reduced graphene oxide (Fe3O4-RGO) composite by a novel approach, i.e., microwave assisted combustion synthesis of porous Fe3O4 particles followed by decoration of Fe3O4 by RGO. The characterization studies of Fe3O4-RGO composite demonstrate formation of face centered cubic hexagonal crystalline Fe3O4, and homogeneous grafting of Fe3O4 particles by RGO. The nitrogen adsorption-desorption isotherm shows presence of a porous structure with a surface area and a pore volume of 81.67 m(2) g(-1), and 0.106 cm(3) g(-1) respectively. Raman spectroscopic studies of Fe3O4-RGO composite confirm the existence of graphitic carbon. Electrochemical studies reveal that the composite exhibits high reversible Li-ion storage capacity with enhanced cycle life and high coulombic efficiency. The Fe3O4-RGO composite showed a reversible capacity ∼612, 543, and ∼446 mA h g(-1) at current rates of 1 C, 3 C and 5 C, respectively, with a coulombic efficiency of 98% after 50 cycles, which is higher than graphite, and Fe3O4-carbon composite. The cyclic voltammetry experiment reveals the irreversible and reversible Li-ion storage in Fe3O4-RGO composite during the starting and subsequent cycles. The results emphasize the importance of our strategy which exhibited promising electrochemical performance in terms of high capacity retention and good cycling stability. The synergistic properties, (i) improved ionic diffusion by porous Fe3O4 particles with a high surface area and pore volume, and (ii) increased electronic conductivity by RGO grafting attributed to the excellent electrochemical performance of Fe3O4, which make this material attractive to use as anode materials for lithium ion storage.

Magnetic quenching of photonic activity in Fe3O4-elastomer composite

NASA Astrophysics Data System (ADS)

Ma, Danhao; Hess, Dustin T.; Shetty, Pralav P.; Adu, Kofi W.; Bell, Richard C.; Terrones, Mauricio

2016-01-01

We report a quenching phenomenon within the visible region of the electromagnetic spectrum in the photonic response of a passive Fe3O4-silicone elastomer composite film due to magnetically aligned Fe3O4 nanoparticles. We performed systematic studies of the polarization dependence, the effect of particle size, and an in- and out-of-plane particle alignment on the optical response of the Fe3O4-silicone elastomer composites using a UV/vis/NIR spectrometer. We observed systematic redshifts in the response of the out-of-plane composite films with increasing particle alignment and weight that are attributed to dipole-induced effects. There were no observable shifts in the spectra of the in-plane films, suggesting the orientation of the magnetic dipole and the induced electric dipole play a crucial role in the optical response. A dramatic suppression to near quenching of the photonic response occurred in films containing moderate concentrations of the aligned nanoparticles. This is attributed to the interplay between the intra- and the interparticle dipoles. This occurred even when low magnetic fields were used during the curing process, suggesting that particle alignment and particle size limitation are critical in the manipulation of the photonic properties. A dipole approximation model is used to explain the quenching phenomenon. An active system of such a composite has a potential application in magneto-optic switches.

Facile One-pot Transformation of Iron Oxides from Fe2O3 Nanoparticles to Nanostructured Fe3O4@C Core-Shell Composites via Combustion Waves

PubMed Central

Shin, Jungho; Lee, Kang Yeol; Yeo, Taehan; Choi, Wonjoon

2016-01-01

The development of a low-cost, fast, and large-scale process for the synthesis and manipulation of nanostructured metal oxides is essential for incorporating materials with diverse practical applications. Herein, we present a facile one-pot synthesis method using combustion waves that simultaneously achieves fast reduction and direct formation of carbon coating layers on metal oxide nanostructures. Hybrid composites of Fe2O3 nanoparticles and nitrocellulose on the cm scale were fabricated by a wet impregnation process. We demonstrated that self-propagating combustion waves along interfacial boundaries between the surface of the metal oxide and the chemical fuels enabled the release of oxygen from Fe2O3. This accelerated reaction directly transformed Fe2O3 into Fe3O4 nanostructures. The distinctive color change from reddish-brown Fe2O3 to dark-gray Fe3O4 confirmed the transition of oxidation states and the change in the fundamental properties of the material. Furthermore, it simultaneously formed carbon layers of 5–20 nm thickness coating the surfaces of the resulting Fe3O4 nanoparticles, which may aid in maintaining the nanostructures and improving the conductivity of the composites. This newly developed use of combustion waves in hybridized nanostructures may permit the precise manipulation of the chemical compositions of other metal oxide nanostructures, as well as the formation of organic/inorganic hybrid nanostructures. PMID:26902260

Low temperature magnetization and anomalous high temperature dielectric behaviour of (1-x) YMnO3/xZnFe2O4 composites

NASA Astrophysics Data System (ADS)

Kumar, Virendra; Gaur, Anurag

2018-04-01

We synthesized YMnO3 and ZnFe2O4 composites, (1-x)YMnO3/x(ZnFe2O4) with x = 0, 0.05, 0.10, and 0.15 by high temperature sintering. X-ray diffraction (XRD) patterns indicate the successful formation of composites. Weak ferromagnetism is manifested below Néel temperature (TN) for pristine YMnO3, according to (M-H) study performed at 10 K. For (1-x)YMnO3/xZnFe2O4 (x = 0.05, 0.10, 0.15) a thin coercivity is observed in all compositions, due to short range magnetic ordering at low temperature after the insertion of ZnFe2O4. For pristine YMnO3 explicit divarication between FC-ZFC curves is observed, with crimps observed in both FC and ZFC curves at 75 K, which is the TN of YMnO3. For 1-x(YMnO3)/x ZnFe2O4 composites (x = 0.05, 0.10, 0.15) crimps are perceived only in ZFC curves at slightly varying values of 39.8, 42.32 and 45.63 K respectively. Anomalous peaks are observed in high temperature dielectric curves above 400 K for 1-x(YMnO3)/xZnFe2O4 (x = 0, 0.05, 0.10, 0.15) composites due to Maxwell-Wagner relaxation effect.

Facile synthesis of Fe3O4/g-C3N4/HKUST-1 composites as a novel biosensor platform for ochratoxin A.

PubMed

Hu, Shuisheng; Ouyang, Wenjun; Guo, Longhua; Lin, Zhenyu; Jiang, Xiaohua; Qiu, Bin; Chen, Guonan

2017-06-15

A fluorescent biosensor for ochratoxin A was fabricated on the basis of a new nanocomposite (Fe 3 O 4 /g-C 3 N 4 /HKUST-1 composites). Fe 3 O 4 /g-C 3 N 4 /HKUST-1 was synthesized in this work for the first time, which combined HKUST-1 with g-C 3 N 4 to improve its chemical stability. Fe 3 O 4 /g-C 3 N 4 /HKUST-1 composites have strong adsorption capacity for dye-labeled aptamer and are able to completely quench the fluorescence of the dye through the photoinduced electron transfer (PET) mechanism. In the presence of ochratoxin A (OTA), it can bind with the aptamer with high affinity, causing the releasing of the dye-labeled aptamer from the Fe 3 O 4 /g-C 3 N 4 /HKUST-1 and therefore results in the recovery of fluorescence. The fluorescence intensity of the biosensor has a linear relationship with the OTA concentration in the range of 5.0-160.0ng/mL. The LOD of sensor is 2.57ng/mL (S/N=3). This fluorescence sensor based on the Fe 3 O 4 /g-C 3 N 4 /HKUST-1 composites has been applied to detect OTA in corn with satisfying results. Copyright © 2016. Published by Elsevier B.V.

Fe3O4@Au composite magnetic nanoparticles modified with cetuximab for targeted magneto-photothermal therapy of glioma cells.

PubMed

Lu, Qianling; Dai, Xinyu; Zhang, Peng; Tan, Xiao; Zhong, Yuejiao; Yao, Cheng; Song, Mei; Song, Guili; Zhang, Zhenghai; Peng, Gang; Guo, Zhirui; Ge, Yaoqi; Zhang, Kangzhen; Li, Yuntao

2018-01-01

Thermoresponsive nanoparticles have become an attractive candidate for designing combined multimodal therapy strategies because of the onset of hyperthermia and their advantages in synergistic cancer treatment. In this paper, novel cetuximab (C225)-encapsulated core-shell Fe 3 O 4 @Au magnetic nanoparticles (Fe 3 O 4 @Au-C225 composite-targeted MNPs) were created and applied as a therapeutic nanocarrier to conduct targeted magneto-photothermal therapy against glioma cells. The core-shell Fe 3 O 4 @Au magnetic nanoparticles (MNPs) were prepared, and then C225 was further absorbed to synthesize Fe 3 O 4 @Au-C225 composite-targeted MNPs. Their morphology, mean particle size, zeta potential, optical property, magnetic property and thermal dynamic profiles were characterized. After that, the glioma-destructive effect of magnetic fluid hyperthermia (MFH) combined with near-infrared (NIR) hyperthermia mediated by Fe 3 O 4 @Au-C225 composite-targeted MNPs was evaluated through in vitro and in vivo experiments. The inhibitory and apoptotic rates of Fe 3 O 4 @Au-C225 composite-targeted MNPs-mediated combined hyperthermia (MFH+NIR) group were significantly higher than other groups in vitro and the marked upregulation of caspase-3, caspase-8, and caspase-9 expression indicated excellent antitumor effect by inducing intrinsic apoptosis. Furthermore, Fe 3 O 4 @Au-C225 composite-targeted MNPs-mediated combined hyperthermia (MFH+NIR) group exhibited significant tumor growth suppression compared with other groups in vivo. Our studies illustrated that Fe 3 O 4 @Au-C225 composite-targeted MNPs have great potential as a promising nanoplatform for human glioma therapy and could be of great value in medical use in the future.

Fe3O4@Au composite magnetic nanoparticles modified with cetuximab for targeted magneto-photothermal therapy of glioma cells

PubMed Central

Tan, Xiao; Zhong, Yuejiao; Yao, Cheng; Song, Mei; Song, Guili; Zhang, Zhenghai; Peng, Gang; Guo, Zhirui; Ge, Yaoqi; Zhang, Kangzhen; Li, Yuntao

2018-01-01

Background Thermoresponsive nanoparticles have become an attractive candidate for designing combined multimodal therapy strategies because of the onset of hyperthermia and their advantages in synergistic cancer treatment. In this paper, novel cetuximab (C225)-encapsulated core-shell Fe3O4@Au magnetic nanoparticles (Fe3O4@Au-C225 composite-targeted MNPs) were created and applied as a therapeutic nanocarrier to conduct targeted magneto-photothermal therapy against glioma cells. Methods The core-shell Fe3O4@Au magnetic nanoparticles (MNPs) were prepared, and then C225 was further absorbed to synthesize Fe3O4@Au-C225 composite-targeted MNPs. Their morphology, mean particle size, zeta potential, optical property, magnetic property and thermal dynamic profiles were characterized. After that, the glioma-destructive effect of magnetic fluid hyperthermia (MFH) combined with near-infrared (NIR) hyperthermia mediated by Fe3O4@Au-C225 composite-targeted MNPs was evaluated through in vitro and in vivo experiments. Results The inhibitory and apoptotic rates of Fe3O4@Au-C225 composite-targeted MNPs-mediated combined hyperthermia (MFH+NIR) group were significantly higher than other groups in vitro and the marked upregulation of caspase-3, caspase-8, and caspase-9 expression indicated excellent antitumor effect by inducing intrinsic apoptosis. Furthermore, Fe3O4@Au-C225 composite-targeted MNPs-mediated combined hyperthermia (MFH+NIR) group exhibited significant tumor growth suppression compared with other groups in vivo. Conclusion Our studies illustrated that Fe3O4@Au-C225 composite-targeted MNPs have great potential as a promising nanoplatform for human glioma therapy and could be of great value in medical use in the future. PMID:29719396

Fe2O3/Reduced Graphene Oxide/Fe3O4 Composite in Situ Grown on Fe Foil for High-Performance Supercapacitors.

PubMed

Zhao, Chongjun; Shao, Xiaoxiao; Zhang, Yuxiao; Qian, Xiuzhen

2016-11-09

A Fe 2 O 3 /reduced graphene oxide (RGO)/Fe 3 O 4 nanocomposite in situ grown on Fe foil was synthesized via a simple one-step hydrothermal growth process, where the iron foil served as support, reductant of graphene oxide, Fe source of Fe 3 O 4 , and also the current collector of the electrode. When it directly acted as the electrode of a supercapacitor, as-synthesized Fe 2 O 3 /RGO/Fe 3 O 4 @Fe exhibited excellent electrochemical performance with a high capability of 337.5 mF/cm 2 at 20 mA/cm 2 and a superior cyclability with 2.3% capacity loss from the 600th to the 2000th cycle.

Efficient removal of arsenic by strategically designed and layer-by-layer assembled PS@+rGO@GO@Fe3O4 composites.

PubMed

Kang, Bong Kyun; Lim, Byeong Seok; Yoon, Yeojoon; Kwag, Sung Hoon; Park, Won Kyu; Song, Young Hyun; Yang, Woo Seok; Ahn, Yong-Tae; Kang, Joon-Wun; Yoon, Dae Ho

2017-10-01

The PS@+rGO@GO@Fe 3 O 4 (PG-Fe 3 O 4 ) hybrid composites for Arsenic removal were successfully fabricated and well dispersed using layer-by-layer assembly and a hydrothermal method. The PG-Fe 3 O 4 hybrid composites were composed of uniformly coated Fe 3 O 4 nanoparticles on graphene oxide layers with water flow space between 3D structures providing many contact area and adsorption sites for Arsenic adsorption. The PG-Fe 3 O 4 hybrid composite has large surface adsorption sites and exhibits high adsorption capacities of 104 mg/g for As (III) and 68 mg/g for As (V) at 25 °C and pH 7 comparison with pure Fe 3 O 4 and P-Fe 3 O 4 samples. Copyright © 2017 Elsevier Ltd. All rights reserved.

Composited reduced graphene oxide into LiFePO4/Li2SiO3 and its electrochemical impedance spectroscopy properties

NASA Astrophysics Data System (ADS)

Arifin, M.; Rus, Y. B.; Aimon, A. H.; Iskandar, F.; Winata, T.; Abdullah, M.; Khairurrijal, K.

2017-03-01

LiFePO4 is commonly used as cathode material for Li-ion batteries due to its stable operational voltage and high specific capacity. However, it suffers from certain disadvantages such as low intrinsic electronic conductivity and low ionic diffusion. This study was conducted to analyse the effect of reduced graphene oxide (rGO) on the electrochemical properties of LiFePO4/Li2SiO3 composite. This composite was synthesized by a hydrothermal method. Fourier transform infrared spectroscopy measurement identified the O-P-O, Fe-O, P-O, and O-Si-O- bands in the LiFePO4/Li2SiO3 composite. X-ray diffraction measurement confirmed the formation of LiFePO4. Meanwhile, Raman spectroscopy confirmed the number of rGO layers. Further, scanning electron microscopy images showed that rGO was distributed around the LiFePO4/Li2SiO3 particles. Finally, the electrochemical impedance spectroscopy results showed that the addition of 1 wt% of rGO to the LiFePO4/Li2SiO3 composite reduced charge transfer resistance. It may be concluded that the addition of 1 wt% rGO to LiFePO4/Li2SiO3 composite can enhance its electrochemical performance as a cathode material.

Enhancement of ferromagnetic properties in composites of BaSnO3 and CoFe2O4

NASA Astrophysics Data System (ADS)

Manju, M. R.; Ajay, K. S.; D'Souza, Noel M.; Hunagund, Shivakumar; Hadimani, R. L.; Dayal, Vijaylakshmi

2018-04-01

In this paper, we report structural and magnetic properties of BaSnO3(BSO)(1-x)-CoFe2O4 (CFO)(x) composite (with x = 0%, 1% (C1), 2% (C2) and 5% (C3) in molar ratio) synthesized using nitrate precursor method. The X-ray diffraction (XRD) pattern of the composite powder confirmed presence of both BaSnO3 with the cubic perovskite structure and CoFe2O4 with the cubic spinel structure. No signature of any other phases in pure BaSnO3, CoFe2O4 and composites have been detected either in XRD or energy dispersive X-ray (EDS) analysis. The temperature dependent zero field cooled (ZFC) & field cooled (FC) magnetization and magnetic field dependence magnetization measurements have been carried at room temperature of the pure BaSnO3. We observe a weak ferromagnetic (FM) behavior at room temperature in pure BaSnO3 even though it is non-magnetic in nature. The room temperature Raman spectroscopy and electron spin resonance measurements of the sample confirm the presence of oxygen vacancy and formation of F-center, which is responsible for the FM behavior. The oxidation state and elemental analysis have been carried out using X-ray photoelectron spectroscopy (XPS). The magnetic field dependence of magnetization of the composite samples reveal increase of saturation magnetization (Ms), remanence magnetization (Mr) and coercivity (Hc) with increase in ferrite content in the composite. Significant enhancement in FM components is observed with lowering of temperature.

Controllable synthesis and enhanced microwave absorbing properties of Fe3O4/NiFe2O4/Ni heterostructure porous rods

NASA Astrophysics Data System (ADS)

Li, Yana; Wu, Tong; Jin, Keying; Qian, Yao; Qian, Naxin; Jiang, Kedan; Wu, Wenhua; Tong, Guoxiu

2016-11-01

We developed a coordinated self-assembly/precipitate transfer/sintering method that allows the controllable synthesis of Fe3O4/NiFe2O4/Ni heterostructure porous rods (HPRs). A series of characterizations confirms that changing [Ni2+] can effectively control the crystal size, internal strain, composition, textural characteristics, and properties of HPRs. Molar percentages of Ni and NiFe2O4 in HPRs increase with [Ni2+] in various Boltzmann function modes. Saturation magnetization Ms and coercivity Hc show U-shaped change trends because of crystal size, composition, and interface magnetic coupling. High magnetic loss is maintained after decorating NiFe2O4 and Ni on the surface of Fe3O4 PRs. Controlling the NiFe2O4 interface layers and Ni content can improve impedance matching and dielectric losses, thereby leading to lighter weight, stronger absorption, and broader absorption band of Fe3O4/NiFe2O4/Ni HPRs than Fe3O4 PRs. An optimum EM wave absorbing property was exhibited by Fe3O4/NiFe2O4/Ni HPRs formed at [Ni2+] = 0.05 M. The maximum reflection loss (RL) reaches -58.4 dB at 13.68 GHz, which corresponds to a 2.1 mm matching thickness. The absorbing bandwidth (RL ≤ -20 dB) reaches 14.4 GHz with the sample thickness at 1.6-2.4 and 2.8-10.0 mm. These excellent properties verify that Fe3O4/NiFe2O4/Ni HPRs are promising candidates for new and effective absorptive materials.

A facile method for preparing porous, optically active, magnetic Fe3 O4 @poly(N-acryloyl-leucine) inverse core/shell composite microspheres.

PubMed

Liu, Dong; Deng, Jianping; Yang, Wantai

2014-01-01

The first synthesis of porous, optically active, magnetic Fe3 O4 @poly(N-acryloyl-leucine) inverse core/shell composite microspheres is reported, in which the core is constructed of chiral polymer and the shell is constructed of Fe3 O4 NPs. The microspheres integrate three significant concepts, "porosity", "chirality", and "magneticity", in one single microspheric entity. The microspheres consist of Fe3 O4 nanoparticles and porous optically active microspheres, and thus combine the advantages of both magnetic nanoparticles and porous optically active microspheres. The pore size and specific surface area of the microspheres are characterized by N2 adsorption, from which it is found that the composite microspheres possess a desirable porous structure. Circular dichroism and UV-vis absorption spectroscopy measurements demonstrate that the microspheres exhibit the expected optical activity. The microspheres also have high saturation magnetization of 14.7 emu g(-1) and rapid magnetic responsivity. After further optimization, these novel microspheres may potentially find applications in areas such as asymmetric catalysis, chiral adsorption, etc. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Bio-Inspired Hierarchical Nanofibrous Fe3O4-TiO2-Carbon Composite as a High-Performance Anode Material for Lithium-Ion Batteries.

PubMed

Li, Shun; Wang, Mengya; Luo, Yan; Huang, Jianguo

2016-07-13

A bioinspired hierarchical nanofibrous Fe3O4-TiO2-carbon composite was fabricated by employing natural cellulose substance (e.g., filter paper) as both the scaffold and the carbon source and showed improved electrochemical performances when it is employed as an anode material for lithium-ion batteries. FeOOH nanoparticles were first grown uniformly onto the surface of the titania thin-layer precoated cellulose nanofibers, and thereafter, the as-prepared FeOOH-TiO2-cellulose composite was calcined and carbonized in argon atmosphere at 500 °C for 6 h to produce the Fe3O4-TiO2-carbon composite. The resultant composite possesses a hierarchical structure that was faithfully inherited from the initial cellulose substance, which was composed of titania-coated carbon fibers with corncob-like shaped Fe3O4 nanoparticles immobilized on the surfaces. The diameter of the composite nanofiber is ca. 100-200 nm, and the diameter of the Fe3O4 nanoparticle is about 30 nm, which is coated with an ultrathin carbon layer with a thickness about 3 nm. This composite displayed superior lithium-ion storage performance. It showed a first-cycle discharge capacity of 1340 mAh/g, delivering a stable reversible capacity of ca. 525 mAh/g after 100 charge-discharge cycles at a current density of 100 mA/g, and the efficiency is as high as ca. 95% of the theoretical value. This is much higher than those of the commercial Fe3O4 powder (160 mAh/g) and the Fe3O4-carbon counter material (310 mAh/g). It was demonstrated that the thin titania precoating layer (thickness ca. 3-5 nm) is necessary for the high content loading of the Fe3O4 nanoparticles onto the carbon nanofibers. Owing to the unique three-dimensional porous network structure of the carbon-fiber scaffold, together with the ultrathin outer carbon-coating layer, the composite showed significantly improved cycling stability and rate capability.

Highly efficient enrichment of low-abundance intact proteins by core-shell structured Fe3O4-chitosan@graphene composites.

PubMed

Zhang, Peng; Fang, Xiaoni; Yan, Guoquan; Gao, Mingxia; Zhang, Xiangmin

2017-11-01

In proteomics research, the screening and monitoring of disease biomarkers is still a major challenge, mainly due to their low concentration in biological samples. However, the universal enrichment of intact proteins has not been further studied. In this work, we developed a Fe 3 O 4 -chitosan@graphene (Fe 3 O 4 -CS@G) core-shell composite to enrich low-abundance proteins from biological samples. Fe 3 O 4 -CS@G composite holds chitosan layer decorated Fe 3 O 4 core, which improves the hydrophilicity of materials greatly. Meanwhile, the graphene nanosheets shell formed via electrostatic assembly endows the composite with huge surface area (178m 2 /g). The good water dispersibility ensures the sufficient contact opportunities between graphene composites and proteins, and the large surface area provides enough adsorption sites for the enrichment of proteins. Using Fe 3 O 4 -CS@G, four standard proteins Cyt-c, BSA, Myo and OVA were enriched with better adsorption capacity and recovery rate, compared with previously reported magnetic graphene composites. Additionally, the mechanism of compared to" is corrected into "compared with". proteins adsorption on Fe 3 O 4 -CS@G was further studied, which indicates that hydrophobic and electrostatic interaction work together to facilitate the universal and efficient enrichment of proteins. Human plasma sample was employed to further evaluate the enrichment performance of Fe 3 O 4 -CS@G. Eventually, 123 proteins were identified from one of SAX fractions of human plasma, which is much better than commercial Sep-pak C18 enrichment column (39 proteins). All these outstanding performances suggest that Fe 3 O 4 -CS@G is an ideal platform for the enrichment of low-abundance intact proteins and thus holds great potential to facilitate the identification of biomarkers from biological samples in proteomics research. Copyright © 2017 Elsevier B.V. All rights reserved.

Arsenic removal from aqueous solutions using Fe3O4-HBC composite: effect of calcination on adsorbents performance.

PubMed

Baig, Shams Ali; Sheng, TianTian; Sun, Chen; Xue, XiaoQin; Tan, LiSha; Xu, XinHua

2014-01-01

The presence of elevated concentration of arsenic in water sources is considered to be health hazard globally. Calcination process is known to change the surface efficacy of the adsorbent. In current study, five adsorbent composites: uncalcined and calcined Fe3O4-HBC prepared at different temperatures (400°C and 1000°C) and environment (air and nitrogen) were investigated for the adsorptive removal of As(V) and As(III) from aqueous solutions determining the influence of solution's pH, contact time, temperature, arsenic concentration and phosphate anions. Characterizations from FTIR, XRD, HT-XRD, BET and SEM analyses revealed that the Fe3O4-HBC composite at higher calcination temperature under nitrogen formed a new product (fayalite, Fe2SiO4) via phase transformation. In aqueous medium, ligand exchange between arsenic and the effective sorbent site ( = FeOOH) was established from the release of hydroxyl group. Langmuir model suggested data of the five adsorbent composites follow the order: Fe3O4-HBC-1000°C(N2)>Fe3O4-HBC (uncalcined)>Fe3O4-HBC-400°C(N2)>Fe3O4-HBC-400°C(air)>Fe3O4-HBC-1000°C(air) and the maximum As(V) and As(III) adsorption capacities were found to be about 3.35 mg g(-1) and 3.07 mg g(-1), respectively. The adsorption of As(V) and As(III) remained stable in a wider pH range (4-10) using Fe3O4-HBC-1000°C(N2). Additionally, adsorption data fitted well in pseudo-second-order (R2>0.99) rather than pseudo-first-order kinetics model. The adsorption of As(V) and As(III) onto adsorbent composites increase with increase in temperatures indicating that it is an endothermic process. Phosphate concentration (0.0l mM or higher) strongly inhibited As(V) and As(III) removal through the mechanism of competitive adsorption. This study suggests that the selective calcination process could be useful to improve the adsorbent efficiency for enhanced arsenic removal from contaminated water.

Arsenic Removal from Aqueous Solutions Using Fe3O4-HBC Composite: Effect of Calcination on Adsorbents Performance

PubMed Central

Baig, Shams Ali; Sheng, TianTian; Sun, Chen; Xue, XiaoQin; Tan, LiSha; Xu, XinHua

2014-01-01

The presence of elevated concentration of arsenic in water sources is considered to be health hazard globally. Calcination process is known to change the surface efficacy of the adsorbent. In current study, five adsorbent composites: uncalcined and calcined Fe3O4-HBC prepared at different temperatures (400°C and 1000°C) and environment (air and nitrogen) were investigated for the adsorptive removal of As(V) and As(III) from aqueous solutions determining the influence of solution's pH, contact time, temperature, arsenic concentration and phosphate anions. Characterizations from FTIR, XRD, HT-XRD, BET and SEM analyses revealed that the Fe3O4-HBC composite at higher calcination temperature under nitrogen formed a new product (fayalite, Fe2SiO4) via phase transformation. In aqueous medium, ligand exchange between arsenic and the effective sorbent site ( = FeOOH) was established from the release of hydroxyl group. Langmuir model suggested data of the five adsorbent composites follow the order: Fe3O4-HBC-1000°C(N2)>Fe3O4-HBC (uncalcined)>Fe3O4-HBC-400°C(N2)>Fe3O4-HBC-400°C(air)>Fe3O4-HBC-1000°C(air) and the maximum As(V) and As(III) adsorption capacities were found to be about 3.35 mg g−1 and 3.07 mg g−1, respectively. The adsorption of As(V) and As(III) remained stable in a wider pH range (4–10) using Fe3O4-HBC-1000°C(N2). Additionally, adsorption data fitted well in pseudo-second-order (R 2>0.99) rather than pseudo-first-order kinetics model. The adsorption of As(V) and As(III) onto adsorbent composites increase with increase in temperatures indicating that it is an endothermic process. Phosphate concentration (0.0l mM or higher) strongly inhibited As(V) and As(III) removal through the mechanism of competitive adsorption. This study suggests that the selective calcination process could be useful to improve the adsorbent efficiency for enhanced arsenic removal from contaminated water. PMID:24967645

Thermodynamic Properties of α-Fe 2O 3 and Fe 3O 4 Nanoparticles

DOE PAGES

Spencer, Elinor C.; Ross, Nancy L.; Olsen, Rebecca E.; ...

2015-04-21

Here we comprehansively assessed the thermodynamic properties of hydrated α-Fe 2O 3 (hematite) and Fe 3O 4 (magnetite) nanoparticles. In addition to 9 nm Fe 3O 4, three α-e 2O 3nanoparticles samples of different sizes (11, 14, and 25 nm) and bulk α-e 2O 3 have been evaluated by inelastic neutron scattering methods. The contribution of the two-level magnetic spin flip transition to the heat capacity of the α-e 2O 3 particles has been determined. The isochoric heat capacity of the water confined on the surface of these two types of iron oxide particles have been calculated from their INSmore » spectra, and is affected by the chemical composition of the underlying particle. Furthermore, the heat capacity and dynamics of the particle hydration layers appear to be influenced by a complex array of factors including particle size, water coverage, and possibly the magnetic state of the particle itself.« less

Enhanced microwave absorption property of epoxy nanocomposites based on PANI@Fe3O4@CNFs nanoparticles with three-phase heterostructure

NASA Astrophysics Data System (ADS)

Yang, Lingfeng; Cai, Haopeng; Zhang, Bin; Huo, Siqi; Chen, Xi

2018-02-01

Novel electromagnetic functionalized carbon nanofibers (CNFs) have been synthesized by coating with Fe3O4 magnetite nanoparticles and conducting polymers polyaniline (PANI) on CNFs through a layer by layer assembly. The Fe3O4@CNFs were first prepared by coating nano-Fe3O4 particles on CNFs via co-precipitation method; Then the PANI was coated on Fe3O4@CNFs using an in situ polymerization process to obtain PANI@Fe3O4@CNFs nanoparticles. The prepared PANI@Fe3O4@CNFs nanoparticles were dispersed in the epoxy matrix to fabricate microwave absorbing nanocomposites. Compared with the Fe3O4@CNFs/epoxy nanocomposites, the PANI@Fe3O4@CNFs/epoxy nanocomposites exhibit better microwave absorbing properties. The composite containing 15 wt% of PANI@Fe3O4@CNFs with the thickness of 2 mm showed a minimum reflection loss (RL) value of -23.7 dB with an effective absorption bandwidth which is about 3.7 GHz (11.9-15.6 GHz) in the frequency range of 1-18 GHz, indicating that it is an attractive candidate for efficient microwave absorber. A potential absorption mechanism was proposed for enhancement of the impedance-matching condition and electromagnetic wave-attenuation characteristic of materials. Specifically, the impedance-matching condition was improved by the combination of conductive polymers and magnetic nanoparticles with CNFs. The electromagnetic wave attenuation characteristic was enhanced by multiple reflections, due to the increased propagation paths.

Preparation of MWCNT-Fe3O4 Nanocomposites from Iron Sand Using Sonochemical Route

NASA Astrophysics Data System (ADS)

Rahmawati, R.; Melati, A.; Taufiq, A.; Sunaryono; Diantoro, M.; Yuliarto, B.; Suyatman, S.; Nugraha, N.; Kurniadi, D.

2017-05-01

The composites of multi-walled carbon nanotube (MWCNT) and magnetite (Fe3O4) nanoparticles from iron sand were successfully prepared via the sonochemical route. In this experiment, the MWCNT-Fe3O4 nanocomposites were prepared with different compositions of MWCNT (0.01%, 0.02%, and 0.04%) with the constant composition of Fe3O4 particles. The characterizations were performed by means of X-Ray Diffractometry (XRD), Fourier Transform Infra-Red (FTIR) Spectrometer and Scanning Electron Microscopy (SEM) integrated with Energy Dispersive X-Ray (EDX). The XRD data analysis showed that the Fe3O4 crystallize in spinel structure in nanometric size. Furthermore, the crystallinity of the samples tended to reduce by increasing the MWCNT compositions. The SEM images showed that Fe3O4 tend to agglomerate in nanometric size. The FTIR spectra detected the functional groups of Fe-O bonding that showed the existence of Fe2+ and Fe3+. In the composites, the Fe3O4 nanoparticles were physically mixed with the MWCNTs constructing a unique structure. The as prepared MWCNT-Fe3O4 nanocomposites have the potential for bio-applications.

Synthesis of Fe3O4 cluster microspheres/graphene aerogels composite as anode for high-performance lithium ion battery

NASA Astrophysics Data System (ADS)

Zhou, Shuai; Zhou, Yu; Jiang, Wei; Guo, Huajun; Wang, Zhixing; Li, Xinhai

2018-05-01

Iron oxides are considered as attractive electrode materials because of their capability of lithium storage, but their poor conductivity and large volume expansion lead to unsatisfactory cycling stability. We designed and synthesized a novel Fe3O4 cluster microspheres/Graphene aerogels composite (Fe3O4/GAs), where Fe3O4 nanoparticles were assembled into cluster microspheres and then embedded in 3D graphene aerogels framework. In the spheres, the sufficient free space between Fe3O4 nanoparticles could accommodate the volume change during cycling process. Graphene aerogel works as flexible and conductive matrix, which can not only significantly increase the mechanical stress, but also further improve the storage properties. The Fe3O4/GAs composite as an anode material exhibits high reversible capability and excellent cyclic capacity for lithium ion batteries (LIBs). A reversible capability of 650 mAh g-1 after 500 cycles at a current density of 1 A g-1 can be maintained. The superior storage capabilities of the composites make them potential anode materials for LIBs.

Fabrication of nano-Fe3O4 3D structure on carbon fibers as a microwave absorber and EMI shielding composite by modified EPD method

NASA Astrophysics Data System (ADS)

Gholampoor, Mahdi; Movassagh-Alanagh, Farid; Salimkhani, Hamed

2017-02-01

Recently, electromagnetic interference (EMI) shielding materials have absorbed a lot of attention due to a growing need for application in the area of electronic and wireless devices. In this study, a carbon-based EMI shielding composite was fabricated by electrophoretic deposition of Fe3O4 nano-particles on carbon fibers (CFs) as a 3D structure incorporated with an epoxy resin. Co-precipitation method was employed to synthesize Fe3O4 nano-particles. This as-synthesized Fe3O4 nano-powder was then successfully deposited on CFs using a modified multi-step electrophoretic deposition (EPD) method. The results of structural studies showed that the Fe3O4 nano-particles (25 nm) were successfully and uniformly deposited on CFs. The measured magnetic properties of as-synthesized Fe3O4 nano-powder and nano-Fe3O4/CFs composite showed that the saturation magnetization of bare Fe3O4 was decreased from Ms = 72.3 emu/g to Ms = 33.1 emu/g for nano-Fe3O4/CFs composite and also corecivity of Fe3O4 was increased from Hc = 4.9 Oe to Hc = 168 Oe for composite. The results of microwave absorption tests revealed that the reflection loss (RL) of an epoxy-based nano-Fe3O4/CFs composite are significantly influenced by layer thickness. The maximum RL value of -10.21 dB at 10.12 GHz with an effective absorption bandwidth about 2 GHz was obtained for the sample with the thickness of 2 mm. It also exhibited an EMI shielding performance of -23 dB for whole the frequency range of 8.2-12.4 GHz.

Preparation and study of (1 - x)CuFe2O4-xBaTiO3 (x = 0, 0.1 and 1) composite multiferroics

NASA Astrophysics Data System (ADS)

Murtaza, Tahir; Ali, Javid; Khan, M. S.

2018-07-01

The parent and mixed spinel-perovskite composite of (1 - x)CuFe2O4-xBaTiO3 (x = 0, 0.1 and 1) has been prepared by solid-state reaction method and studied by X-ray diffraction (XRD), scanning electron microscopy (SEM), Mössbauer spectroscopy, magnetometry and P-E lope tracer. The XRD results showed the formation of single phase tetragonal spinel CuFe2O4 and tetragonal perovskite BaTiO3 at room temperature, further XRD of composite 0.1CuFe2O4-0.9BaTiO3 reflects the two crystallographic phases with 1:9 ratio. The SEM micrographs show the homogeneous and uniform formation of the samples. Through EDAX analysis, the chemical composition of the sample is found to be same as the nominal composition. The high field Mossbauer data of CuFe2O4 sample shows the ferrimagnetic ordering in the sample. The observed M-H and P-E loops of the composite 0.1CuFe2O4-0.9BaTiO3 sample show the presence of spontaneous magnetization and spontaneous electric polarization indicating the multiferroic nature of the sample.

A Fe3O4/FeAl2O4 composite coating via plasma electrolytic oxidation on Q235 carbon steel for Fenton-like degradation of phenol.

PubMed

Wang, Jiankang; Yao, Zhongping; Yang, Min; Wang, Yajing; Xia, Qixing; Jiang, Zhaohua

2016-08-01

The Fe3O4/FeAl2O4 composite coatings were successfully fabricated on Q235 carbon steel by plasma electrolytic oxidation technique and used to degrade phenol by Fenton-like system. XRD, SEM, and XPS indicated that Fe3O4 and FeAl2O4 composite coating had a hierarchical porous structure. The effects of various parameters such as pH, phenol concentration, and H2O2 dosage on catalytic activity were investigated. The results indicated that with increasing of pH and phenol content, the phenol degradation efficiency was reduced significantly. However, the degradation rate was improved with the addition of H2O2, but dropped with further increasing of H2O2. Moreover, 100 % removal efficiency with 35 mg/L phenol was obtained within 60 min at 303 K and pH 4.0 with 6.0 mmol/L H2O2 on 6-cm(2) iron oxide coating. The degradation process consisted of induction period and rapid degradation period; both of them followed pseudo-first-order reaction. Hydroxyl radicals were the mainly oxidizing species during phenol degradation by using n-butanol as hydroxyl radical scavenger. Based on Fe leaching and the reaction kinetics, a possible phenol degradation mechanism was proposed. The catalyst exhibited excellent stability.

Fe3O4/C composite with hollow spheres in porous 3D-nanostructure as anode material for the lithium-ion batteries

NASA Astrophysics Data System (ADS)

Yang, Zhao; Su, Danyang; Yang, Jinping; Wang, Jing

2017-09-01

3d transition-metal oxides, especially Fe3O4, as anode materials for the lithium-ion batteries have been attracting intensive attentions in recent years due to their high energy capacity and low toxicity. A new Fe3O4/C composite with hollow spheres in porous three-dimensional (3D) nanostructure, which was synthesized by a facile solvothermal method using FeCl3·6H2O and porous spongy carbon as raw materials. The specific surface area and microstructures of composite were characterized by nitrogen adsorption-desorption isotherm method, FE-SEM and HR-TEM. A homogeneous distribution of hollow Fe3O4 spheres (diameter ranges from 120 nm to 150 nm) in the spongy carbon (pore size > 200 nm) conductive 3D-network significantly reduced the lithium-ion diffusion length and increased the electrochemical reaction area, and further more enhanced the lithium ion battery performance, such as discharge capacity and cycle life. As an anode material for the lithium-ion battery, the title composite exhibit excellent electrochemical properties. The Fe3O4/C composite electrode achieved a relatively high reversible specific capacity of 1450.1 mA h g-1 in the first cycle at 100 mA g-1, and excellent rate capability (69% retention at 1000 mA g-1) with good cycle stability (only 10% loss after 100 cycles).

Ni doped Fe3O4 magnetic nanoparticles.

PubMed

Larumbe, S; Gómez-Polo, C; Pérez-Landazábal, J I; García-Prieto, A; Alonso, J; Fdez-Gubieda, M L; Cordero, D; Gómez, J

2012-03-01

In this work, the effect of nickel doping on the structural and magnetic properties of Fe3O4 nanoparticles is analysed. Ni(x)Fe(3-x)O4 nanoparticles (x = 0, 0.04, 0.06 and 0.11) were obtained by chemical co-precipitation method, starting from a mixture of FeCl2 x 4H2O and Ni(AcO)2 x 4H2O salts. The analysis of the structure and composition of the synthesized nanoparticles confirms their nanometer size (main sizes around 10 nm) and the inclusion of the Ni atoms in the characteristic spinel structure of the magnetite Fe3O4 phase. In order to characterize in detail the structure of the samples, X-ray absorption (XANES) measurements were performed on the Ni and Fe K-edges. The results indicate the oxidation of the Ni atoms to the 2+ state and the location of the Ni2+ cations in the Fe2+ octahedral sites. With respect to the magnetic properties, the samples display the characteristic superparamagnetic behaviour, with anhysteretic magnetic response at room temperature. The estimated magnetic moment confirms the partial substitution of the Fe2+ cations by Ni2+ atoms in the octahedral sites of the spinel structure.

Bi-functional Au/FeS (Au/Co3O4) composite for in situ SERS monitoring and degradation of organic pollutants

NASA Astrophysics Data System (ADS)

Ma, Shuzhen; Cai, Qian; Lu, Kailing; Liao, Fan; Shao, Mingwang

2016-01-01

The bi-functional Au/FeS (Au/Co3O4) composite was fabricated by in situ reducing Au nanoparticles onto the surface of FeS (Co3O4). The as-prepared FeS possessed a multi-structure composed of plenty of nanoplates, which were coated by Au nanoparticles with an average size of 47.5 nm. While the Co3O4 showed a thin hexagonal sheet containing Au nanoparticles on its surface with an average size of 79.0 nm. Both the as-prepared Au/FeS and Au/Co3O4 composites exhibited excellent SERS performance, capable of enhancing the Raman signals of R6G molecules with the enhancement factor up to 1.81 × 106 and 7.60 × 104, respectively. Moreover, Au/FeS (Au/Co3O4) composite also has been verified to have intrinsic peroxidase-like activity, which could decompose H2O2 into hydroxyl radicals and then degrade organic pollutants into small molecules. Therefore, SERS can be used to real-time and in situ monitoring the degradation process of R6G molecules, employing the Au/FeS (Au/Co3O4) composite both as SERS substrate and catalyst.

Preparation, characterization, and antibacterial activity of NiFe2O4/PAMA/Ag-TiO2 nanocomposite

NASA Astrophysics Data System (ADS)

Allafchian, Alireza; Jalali, Seyed Amir Hossein; Bahramian, Hamid; Ahmadvand, Hossein

2016-04-01

We have described a facile fabrication of silver deposited on the TiO2, Poly Acrylonitrile Co Maleic Anhydride (PAMA) polymer and nickel ferrite composite (NiFe2O4/PAMA/Ag-TiO2) through a three-step procedure. A pre-synthesized NiFe2O4 was first coated with PAMA polymer and then Ag-TiO2 was deposited on the surface of PAMA polymer shell. After the characterization of this three-component composite by various techniques, such as FTIR, XRD, FESEM, BET, TEM and VSM, it was impregnated in standard antibiotic discs. The antibacterial activity of NiFe2O4/PAMA/Ag-TiO2 nanocomposite was investigated against some gram positive and gram negative bacteria by employing disc diffusion assay and then compared with that of naked NiFe2O4, NiFe2O4/Ag, AgNPs and NiFe2O4/PAMA. The results demonstrated that the AgNPs, when embedded in TiO2 and combined with NiFe2O4/PAMA, became an excellent antibacterial agent. The NiFe2O4/PAMA/Ag-TiO2 nanocomposite could be readily separated from water solution after the disinfection process by applying an external magnetic field.

Biocompatible polyurethane/thiacalix[4]arenes functionalized Fe3O4 magnetic nanocomposites: Synthesis and properties.

PubMed

Mohammadi, Abbas; Barikani, Mehdi; Lakouraj, Moslem Mansour

2016-09-01

In this study, a series of magnetic polyurethane/Fe3O4 elastomer nanocomposites were prepared by covalently embedding novel thiacalix[4]arenes (TC4As) functionalized Fe3O4 nanoparticles (TC4As-Fe3O4) which contain macrocycles with reactive hydroxyl groups. Surface functionalization of Fe3O4 nanoparticles with TC4As macrocycles as unique reactive surface modifier not only gives specific characteristics to Fe3O4 nanoparticles but also improves the interphase interaction between nanoparticles and the polyurethane matrices through covalent attachment of polymer chains to nanoparticle surfaces. The novel synthesized TC4As-Fe3O4 nanoparticles were characterized by FTIR, XRD, TGA, VSM and SEM analysis. Furthermore, the effect of functionalization of Fe3O4 nanoparticles on the various properties of resulting nanocomposites was studied by XRD, TGA, DMTA, SEM, and a universal tensile tester. It was found that the functionalization of nanoparticles with TC4As affords better mechanical and thermal properties to polyurethane nanocomposites in comparison with unmodified nanoparticles. The SEM analysis showed finer dispersion of TC4As-Fe3O4 nanoparticles than unmodified Fe3O4 nanoparticles within the polyurethane matrices, which arising from formation of covalent bonding between TC4As functionalized Fe3O4 nanoparticles and polyurethane matrices. Moreover, the investigation of in vitro biocompatibility of novel nanocomposites showed that these samples are excellent candidate for biomedical use. Copyright © 2016 Elsevier B.V. All rights reserved.

Fabrication of graphene oxide decorated with Fe3O4@SiO2 for immobilization of cellulase

NASA Astrophysics Data System (ADS)

Li, Yue; Wang, Xiang-Yu; Jiang, Xiao-Ping; Ye, Jing-Jing; Zhang, Ye-Wang; Zhang, Xiao-Yun

2015-01-01

Fe3O4@SiO2-graphene oxide (GO) composites were successfully fabricated by chemical binding of functional Fe3O4@SiO2 and GO and applied to immobilization of cellulase via covalent attachment. The prepared composites were further characterized by transmission electron microscopy and Fourier transform infrared spectroscopy. Fe3O4 nanoparticles (NPs) were monodisperse spheres with a mean diameter of 17 ± 0.2 nm. The thickness of SiO2 layer was calculated as being 6.5 ± 0.2 nm. The size of Fe3O4@SiO2 NPs was 24 ± 0.3 nm, similar to that of Fe3O4@SiO2-NH2. Fe3O4@SiO2-GO composites were synthesized by linking of Fe3O4@SiO2-NH2 NPs to GO with the catalysis of EDC and NHS. The prepared composites were used for immobilization of cellulase. A high immobilization yield and efficiency of above 90 % were obtained after the optimization. The half-life of immobilized cellulase (722 min) was 3.34-fold higher than that of free enzyme (216 min) at 50 °C. Compared with the free cellulase, the optimal temperature of the immobilized enzyme was not changed; but the optimal pH was shifted from 5.0 to 4.0, and the thermal stability was enhanced. The immobilized cellulase could be easily separated and reused under magnetic field. These results strongly indicate that the cellulase immobilized onto the Fe3O4@SiO2-GO composite has potential applications in the production of bioethanol.

Preparation and structure of Na2Ag5Fe3(P2O7)4 -Ag metal composite: Insights on electrochemistry

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, Yiman; Marschilok, Amy C.; Takeuchi, Esther S.

ABSTRACT Ag 7Fe 3(P 2O 7) 4is a 3D structured material which has been recently studied as a possible cathode material for lithium batteries. Notably, Na 7Fe 3(P 2O 7) 4is reported to be a fast-ion conductor, yet poor electrical conductor. Here, partial replacement of Na +for Ag +yielded Na 2Ag 5Fe 3(P 2O 7) 4pyrophosphate framework where the formation of Ag metal is proposed to increase the intrinsic low electrical conductivity of this polyanion electrode. Specifically, the Ag 5Na 2Fe 3(P 2O 7) 4-Ag composite is synthesized via chemical reduction of Ag 7Fe 3(P 2O 7) 4using NaBH 4.more » The occupancy of Ag +and Na +in each site was determined via Rietveld analysis of the diffraction pattern. Electrochemistry of the Ag 5Na 2Fe 3(P 2O 7) 4-Ag metal composite was explored with voltammetry and galvanostatic charge/discharge cycling. The Ag 5Na 2Fe 3(P 2O 7) 4-Ag metal composite electrodes displayed good rate capability assisted by the presence of Ag metal from the chemical reduction and in-situ electrochemical formation of a Ag conductive network.« less

Lightweight reduced graphene oxide-Fe3O4 nanoparticle composite in the quest for an excellent electromagnetic interference shielding material.

PubMed

Singh, Ashwani Kumar; Kumar, Ajit; Haldar, Krishna Kamal; Gupta, Vinay; Singh, Kedar

2018-06-15

This work reports a detailed study of reduced graphene oxide (rGO)-Fe 3 O 4 nanoparticle composite as an excellent electromagnetic (EM) interference shielding material in GHz range. A rGO-Fe 3 O 4 nanoparticle composite was synthesized using a facile, one step, and modified solvothermal method with the reaction of FeCl 3 , ethylenediamine and graphite oxide powder in the presence of ethylene glycol. Various structural, microstructural and optical characterization tools were used to determine its synthesis and various properties. Dielectric, magnetic and EM shielding parameters were also evaluated to estimate its performance as a shielding material for EM waves. X-ray diffraction patterns have provided information about the structural and crystallographic properties of the as-synthesized material. Scanning electron microscopy micrographs revealed the information regarding the exfoliation of graphite into rGO. Well-dispersed Fe 3 O 4 nanoparticles over the surface of the graphene can easily be seen by employing transmission electron microscopy. For comparison, rGO nanosheets and Fe 3 O 4 nanoparticles have also been synthesized and characterized in a similar fashion. A plot of the dielectric and magnetic characterizations provides some useful information related to various losses and the relaxation process. Shielding effectiveness due to reflection (SE R ), shielding effectiveness due to absorption (SE A ), and total shielding effectiveness (SE T ) were also plotted against frequency over a broad range (8-12 GHz). A significant change in all parameters (SE A value from 5 dB to 35 dB for Fe 3 O 4 nanoparticles to rGO-Fe 3 O 4 nanoparticle composite) was found. An actual shielding effectiveness (SE T ) up to 55 dB was found in the rGO-Fe 3 O 4 nanoparticle composite. These graphs give glimpses of how significantly this material shows shielding effectiveness over a broad range of frequency.

Lightweight reduced graphene oxide-Fe3O4 nanoparticle composite in the quest for an excellent electromagnetic interference shielding material

NASA Astrophysics Data System (ADS)

Singh, Ashwani Kumar; Kumar, Ajit; Kamal Haldar, Krishna; Gupta, Vinay; Singh, Kedar

2018-06-01

This work reports a detailed study of reduced graphene oxide (rGO)-Fe3O4 nanoparticle composite as an excellent electromagnetic (EM) interference shielding material in GHz range. A rGO-Fe3O4 nanoparticle composite was synthesized using a facile, one step, and modified solvothermal method with the reaction of FeCl3, ethylenediamine and graphite oxide powder in the presence of ethylene glycol. Various structural, microstructural and optical characterization tools were used to determine its synthesis and various properties. Dielectric, magnetic and EM shielding parameters were also evaluated to estimate its performance as a shielding material for EM waves. X-ray diffraction patterns have provided information about the structural and crystallographic properties of the as-synthesized material. Scanning electron microscopy micrographs revealed the information regarding the exfoliation of graphite into rGO. Well-dispersed Fe3O4 nanoparticles over the surface of the graphene can easily be seen by employing transmission electron microscopy. For comparison, rGO nanosheets and Fe3O4 nanoparticles have also been synthesized and characterized in a similar fashion. A plot of the dielectric and magnetic characterizations provides some useful information related to various losses and the relaxation process. Shielding effectiveness due to reflection (SER), shielding effectiveness due to absorption (SEA), and total shielding effectiveness (SET) were also plotted against frequency over a broad range (8–12 GHz). A significant change in all parameters (SEA value from 5 dB to 35 dB for Fe3O4 nanoparticles to rGO-Fe3O4 nanoparticle composite) was found. An actual shielding effectiveness (SET) up to 55 dB was found in the rGO-Fe3O4 nanoparticle composite. These graphs give glimpses of how significantly this material shows shielding effectiveness over a broad range of frequency.

Synthesis and characterization of SiO2/(PMMA/Fe3O4) magnetic nanocomposites.

PubMed

Wang, Zhifei; Guo, Yafei; Li, Song; Sun, Yueming; He, Nongyue

2008-04-01

Magnetic silica nanocomposites (magnetic nanoparticles core coated by silica shell) have the wide promising applications in the biomedical field and usually been prepared based on the famous Stöber process. However, the flocculation of Fe3O4 nanoparticles easily occurs during the silica coating, which limits the amount of magnetic silica particles produced in the Stöber process. In this paper, PMMA/Fe3O4 nanoparticles were used in the Stöber process instead of the "nude" Fe3O4 nanoparticles. And coating Fe3O4 with PMMA polymer beforehand can prevent magnetic nanoparticles from the aggregation that usually comes from the increasing of ionic strength during the hydrolyzation of tetraethoxysilane (TEOS) by the steric hindrance. The results show that the critical concentration of magnetic nanoparticles can increase from 12 mg/L for "nude" Fe3O4 nanoparticles to 3 g/L for PMMA/Fe3O4 nanoparticles during the Stöber process. And before the deposition of silica shell, the surface of PMMA/FeO4 nanoparticles had to be further modified by hydrolyzing them in CH3OH/NH3 x H2O mixture solution, which provides the carboxyl groups on their surface to react further with the silanol groups of silicic acid.

Structural and magnetic characteristics of PVA/CoFe{sub 2}O{sub 4} nano-composites prepared via mechanical alloying method

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rashidi, S.; Ataie, A., E-mail: aataie@ut.ac.ir

Highlights: • Single phase CoFe{sub 2}O{sub 4} nano-particles synthesized in one step by mechanical alloying. • PVA/CoFe{sub 2}O{sub 4} magnetic nano-composites were fabricated via mechanical milling. • FTIR confirmed the interaction between PVA and magnetic CoFe{sub 2}O{sub 4} particles. • Increasing in milling time and PVA amount led to well dispersion of CoFe{sub 2}O{sub 4}. - Abstract: In this research, polyvinyl alcohol/cobalt ferrite nano-composites were successfully synthesized employing a two-step procedure: the spherical single-phase cobalt ferrite of 20 ± 4 nm mean particle size was synthesized via mechanical alloying method and then embedded into polymer matrix by intensive milling. Themore » results revealed that increase in polyvinyl alcohol content and milling time causes cobalt ferrite particles disperse more homogeneously in polymer matrix, while the mean particle size and shape of cobalt ferrite have not been significantly affected. Transmission electron microscope images indicated that polyvinyl alcohol chains have surrounded the cobalt ferrite nano-particles; also, the interaction between polymer and cobalt ferrite particles in nano-composite samples was confirmed. Magnetic properties evaluation showed that saturation magnetization, coercivity and anisotropy constant values decreased in nano-composite samples compared to pure cobalt ferrite. However, the coercivity values of related nano-composite samples enhanced by increasing PVA amount due to domain wall mechanism.« less

Exchange-coupled Fe3O4/CoFe2O4 nanoparticles for advanced magnetic hyperthermia

NASA Astrophysics Data System (ADS)

Glassell, M.; Robles, J.; Das, R.; Phan, M. H.; Srikanth, H.

Iron oxide nanoparticles especially Fe3O4, γ-Fe2O3 have been extensively studied for magnetic hyperthermia because of their tunable magnetic properties and stable suspension in superparamagnetic regime. However, their relatively low heating capacity hindered practical application. Recently, a large improvement in heating efficiency has been reported in exchange-coupled nanoparticles with exchange coupling between soft and hard magnetic phases. Here, we systematically studied the effect of core and shell size on the heating efficiency of the Fe3O4/CoFe2O4 core/shell nanoparticles. The nanoparticles were synthesized using thermal decomposition of organometallic precursors. Transmission electron microscopy (TEM) showed formation of spherical shaped Fe3O4 and Fe3O-/CoFe2O4 nanoparticles. Magnetic measurements showed high magnetization (≅70 emu/g) and superparamagnetic behavior for the nanoparticles at room temperature. Magnetic hyperthermia results showed a large increase in specific absorption rate (SAR) for 8nm Fe3O4/CoFe2O4 compared to Fe3O4 nanoparticles of the same size. The heating efficiency of the Fe3O4/CoFe2O4 with 1 nm CoFe2O4 (shell) increased from 207 to 220 W/g (for 800 Oe) with increase in core size from 6 to 8 nm. The heating efficiency of the Fe3O4/CoFe2O4 with 2 nm CoFe2O4 (shell) and core size of 8 nm increased from 220 to 460 W/g (for 800 Oe). These exchange-coupled Fe3O4/CoFe2O4 core/shell nanoparticles can be a good candidate for advanced hyperthermia application.

Fe3O4 and metal-organic framework MIL-101(Fe) composites catalyze luminol chemiluminescence for sensitively sensing hydrogen peroxide and glucose.

PubMed

Qian Tang, Xue; Dan Zhang, Yi; Wei Jiang, Zhong; Mei Wang, Dong; Zhi Huang, Cheng; Fang Li, Yuan

2018-03-01

In this work, Fe 3 O 4 and metal-organic framework MIL-101(Fe) composites (Fe 3 O 4 /MIL-101(Fe)) was demonstrated to possess excellent catalytic property to directly catalyze luminol chemiluminescence without extra oxidants. We utilized Fe 3 O 4 /MIL-101(Fe) to develop a ultra-sensitive quantitative analytical method for H 2 O 2 and glucose. The possible mechanism of the chemiluminescence reaction had been investigated. Under optimal conditions, the relative chemiluminescence intensity was linearly proportional to the logarithm of H 2 O 2 concentration in the range of 5-150nM with a limit of detection of 3.7nM (signal-to-noise ratio = 3), and glucose could be linearly detected in the range from 5 to 100nM and the detection limit was 4.9nM (signal-to-noise ratio = 3). Furthermore, the present approach was successfully applied to quantitative determination of H 2 O 2 in medical disinfectant and glucose in human serum samples. Copyright © 2017 Elsevier B.V. All rights reserved.

In-situ self-assembly of plant polyphenol-coated Fe3O4 particles for oleaginous microalgae harvesting.

PubMed

Wang, Xiaoyu; Zhao, Yuan; Jiang, Xiaoxue; Liu, Lijun; Li, Xue; Li, Huixian; Liang, Wenyan

2018-05-15

Plant polyphenol (PP), a natural polymer from the Larix gmelinii, was selected as the surfactant to synthesize Fe 3 O 4 . The Fe 3 O 4 -PP composite was prepared by in-situ self-assembly in solvothermal synthesis, and characterized using FE-SEM, TEM, XRD, FTIR, XPS, TGA, and VSM. The harvesting efficiency of Chlorella vulgaris was investigated under different parameters, including algal organic matter, dosage, and pH. The results showed that the core-shell sphere of Fe 3 O 4 -PP (∼150 nm) was coated by ∼50 nm PP with a saturated magnetization of 40.0 emu/g. The Fe 3 O 4 -PP could be directly applied to the culture broth (1.5 g dry cell weight/L, pH = 9.03), achieving 93.0% of harvesting efficiency at 20 g/L. Cells were detached from the harvested aggregates by adjusting pH value to 9.80 and with ultrasonication, which achieved 95.6% of recovery efficiency. The recycled Fe 3 O 4 -PP showed high stabilities in surface properties, maintaining more than 87.5% of harvesting efficiency after five recycles. Copyright © 2018 Elsevier Ltd. All rights reserved.

Facile transformation of FeO/Fe3O4 core-shell nanocubes to Fe3O4 via magnetic stimulation

NASA Astrophysics Data System (ADS)

Lak, Aidin; Niculaes, Dina; Anyfantis, George C.; Bertoni, Giovanni; Barthel, Markus J.; Marras, Sergio; Cassani, Marco; Nitti, Simone; Athanassiou, Athanassia; Giannini, Cinzia; Pellegrino, Teresa

2016-09-01

Here, we propose the use of magnetic hyperthermia as a means to trigger the oxidation of Fe1-xO/Fe3-δO4 core-shell nanocubes to Fe3-δO4 phase. As a first relevant consequence, the specific absorption rate (SAR) of the initial core-shell nanocubes doubles after exposure to 25 cycles of alternating magnetic field stimulation. The improved SAR value was attributed to a gradual transformation of the Fe1-xO core to Fe3-δO4, as evidenced by structural analysis including high resolution electron microscopy and Rietveld analysis of X-ray diffraction patterns. The magnetically oxidized nanocubes, having large and coherent Fe3-δO4 domains, reveal high saturation magnetization and behave superparamagnetically at room temperature. In comparison, the treatment of the same starting core-shell nanocubes by commonly used thermal annealing process renders a transformation to γ-Fe2O3. In contrast to other thermal annealing processes, the method here presented has the advantage of promoting the oxidation at a macroscopic temperature below 37 °C. Using this soft oxidation process, we demonstrate that biotin-functionalized core-shell nanocubes can undergo a mild self-oxidation transformation without losing their functional molecular binding activity.

Structural, dielectric and magnetic properties of ZnFe2O4-Na0.5Bi0.5TiO3 multiferroic composites

NASA Astrophysics Data System (ADS)

Bhasin, Tanvi; Agarwal, Ashish; Sanghi, Sujata; Yadav, Manisha; Tuteja, Muskaan; Singh, Jogender; Rani, Sonia

2018-04-01

Multiferroic xNa0.5Bi0.5TiO3-(1-x)ZnFe2O4 (x=0.10, 0.20) composites were prepared by conventional solid state reaction method. Rietveld analysis of XRD data shows that samples exhibit both cubic (Fd-3m) and rhombohedral (R3c) crystal structure. Structural parameters and unit cell volume of samples vary with composition. The dielectric constant and dielectric loss (tanδ) display dispersion at low frequency due to space charge polarization and inhomogeneity in the composites. Magnetic analysis depicts the antiferromagnetic behavior of composites and magnetization is enhanced with the introduction of ferrite (ZnFe2O4) phase.

Exchange-coupled Fe3O4/CoFe2O4 nanoparticles for advanced magnetic hyperthermia

NASA Astrophysics Data System (ADS)

Robles, J.; Das, R.; Glassell, M.; Phan, M. H.; Srikanth, H.

2018-05-01

We report a systematic study of the effects of core and shell size on the magnetic properties and heating efficiency of exchange-coupled Fe3O4/CoFe2O4 core/shell nanoparticles. The nanoparticles were synthesized using thermal decomposition of organometallic precursors. Transmission electron microscopy (TEM) confirmed the formation of spherical Fe3O4 and Fe3O4/CoFe2O4 nanoparticles. Magnetic measurements showed high saturation magnetization for the nanoparticles at room temperature. Increasing core diameter (6.4±0.7, 7.8±0.1, 9.6±1.2 nm) and/or shell thickness (˜1, 2, 4 nm) increased the coercive field (HC), while an optimal value of saturation magnetization (MS) was achieved for the Fe3O4 (7.8±0.1nm)/CoFe2O4 (2.1±0.1nm) nanoparticles. Magnetic hyperthermia measurements indicated a large increase in specific absorption rate (SAR) for 8.2±1.1 nm Fe3O4/CoFe2O4 compared to Fe3O4 nanoparticles of same size. The SAR of the Fe3O4/CoFe2O4 nanoparticles increased from 199 to 461 W/g for 800 Oe as the thickness of the CoFe2O4 shell was increased from 0.9±0.5 to 2.1±0.1 nm. The SAR enhancement is attributed to a combination of the large MS and the large HC. Therefore, these Fe3O4/CoFe2O4 core/shell nanoparticles can be a good candidate for advanced hyperthermia application.

Effective reduction of p-nitrophenol by silver nanoparticle loaded on magnetic Fe3O4/ATO nano-composite

NASA Astrophysics Data System (ADS)

Karki, Hem Prakash; Ojha, Devi Prashad; Joshi, Mahesh Kumar; Kim, Han Joo

2018-03-01

A silver loaded hematite (Fe3O4) and antimony doped tin oxide (ATO) magnetic nano-composite (Ag-Fe3O4/ATO) was successfully synthesized by in situ one pot green and facile hydrothermal process. The formation of nano-composite, its structure, morphology, and stability were characterized by field emission scanning electron microscopy (FE-SEM), high resolution transmission electron microscopy (HRTEM), electron diffraction spectroscopy (EDS), elemental mapping by high resolution scanning transmission electron microscopy (STEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Fourier transform infra-red spectroscopy (FTIR). UV-vis spectroscopy was used to monitor the catalytic reduction of p-nitrophenol (PNP) into p-aminophenol (PAP) in presence of Ag-Fe3O4/ATO nano-composite with excess of sodium borohydride (NaBH4). The pseudo-first order kinetic equation could describe the reduction of p-nitrophenol with excess of NaBH4. For the first time, ATO surface was used for hydrothermal growth of silver and iron oxide magnetic nanoparticles. The in situ growth of these nanoparticles provided an effective bonding of components of the nano-composite over the surface of ATO nanoparticles. This nano-composite exhibited easy synthesis, high stability, cost effective and rapid separation using external magnet. The excellent catalytic and anti-bacterial activity of as-synthesized silver nano-composite makes it potential nano-catalyst for waste water treatment as well as biomedical application.

Profound Interfacial Effects in CoFe2O4/Fe3O4 and Fe3O4/CoFe2O4 Core/Shell Nanoparticles

NASA Astrophysics Data System (ADS)

Polishchuk, Dmytro; Nedelko, Natalia; Solopan, Sergii; Ślawska-Waniewska, Anna; Zamorskyi, Vladyslav; Tovstolytkin, Alexandr; Belous, Anatolii

2018-03-01

Two sets of core/shell magnetic nanoparticles, CoFe2O4/Fe3O4 and Fe3O4/CoFe2O4, with a fixed diameter of the core ( 4.1 and 6.3 nm for the former and latter sets, respectively) and thickness of shells up to 2.5 nm were synthesized from metal chlorides in a diethylene glycol solution. The nanoparticles were characterized by X-ray diffraction, transmission electron microscopy, and magnetic measurements. The analysis of the results of magnetic measurements shows that coating of magnetic nanoparticles with the shells results in two simultaneous effects: first, it modifies the parameters of the core-shell interface, and second, it makes the particles acquire combined features of the core and the shell. The first effect becomes especially prominent when the parameters of core and shell strongly differ from each other. The results obtained are useful for optimizing and tailoring the parameters of core/shell spinel ferrite magnetic nanoparticles for their use in various technological and biomedical applications.

Fe3O4@NiSx/rGO composites with amounts of heterointerfaces and enhanced electrocatalytic properties for oxygen evolution

NASA Astrophysics Data System (ADS)

Zhu, Guoxing; Xie, Xulan; Liu, Yuanjun; Li, Xiaoyun; Xu, Keqiang; Shen, Xiaoping; Yao, Yinjie; Shah, Sayyar Ali

2018-06-01

The sluggish oxygen evolution kinetics involved in water splitting and various metal-air batteries makes the effective and inexpensive electrocatalysts be highly desirable for oxygen evolution reaction (OER). Herein, an effective and facile two-step route is developed to construct Fe3O4@NiSx composite loaded on reduced graphene oxide (rGO). The morphology and microstructure of the composites were characterized by different characterization techniques. The obtained composites show amounts of heterointerfaces. The shift of binding energy in X-ray photoelectron spectrum demonstrates the existence of interfacial charge transfer effect between Fe3O4 and NiSx. The optimized Fe3O4@NiSx/rGO sample exhibits excellent electrocatalytic performance toward OER in alkaline media, showing 10 mA·cm-2 at η = 330 mV, lower Tafel slope (35.5 mV·dec-1), and good durability, demonstrating a great perspective. The excellent OER performance can be ascribed to the synergetic effect between Fe and Ni species. It is believed that the heterointerfaces between Fe3O4 and NiSx perform as active centers for OER.

A facile synthesis of Fe3O4-charcoal composite for the sorption of a hazardous dye from aquatic environment.

PubMed

Ahmed, Md Juned K; Ahmaruzzaman, M

2015-11-01

Herein, we synthesized Fe3O4-charcoal composite using chemical precipitation technique and utilized it for the sorption of methylene blue from aqueous solution. The synthesized composite was characterized by Infra-red spectroscopy, N2 adsorption-desorption isotherm, X-ray diffraction, selected area electron diffraction, transmission electron microscopy, and vibrating sample magnetometer. The composite depicts absorption bands conforming to Fe-O, -OH, CO, and C-O vibrations. The composite was mesoporous in nature with a surface area of 387.30 m(2) g(-1). The observed diffraction planes correspond to face-centered cubic Fe3O4 and disordered graphitic carbon. The spherical Fe3O4 particles (average diameter ∼13.8 nm) were uniformly distributed in the carbon matrix of the charcoal. The saturation and remanent magnetizations demonstrate its potential for magnetic separation and reuse. The composite showed dye sorption capacities of 97.49 mg g(-1) and 90.85 mg g(-1) in batch and fixed-bed system. Pseudo-second order kinetics and Temkin isotherm best represented the sorption data. The sorption process was endothermic, spontaneous, and administered by electrostatic, π-π dispersive interactions, film, and intraparticle diffusion. Microwave irradiations followed by methanol elution regenerated the dye-loaded composite with nearly no loss in sorption capacity. The recovery of energy and potential utilization of bottom ash enhances the prospective of Fe3O4-charcoal composite for industrial applications. Copyright © 2015 Elsevier Ltd. All rights reserved.

Activated carbon/Fe(3)O(4) nanoparticle composite: fabrication, methyl orange removal and regeneration by hydrogen peroxide.

PubMed

Do, Manh Huy; Phan, Ngoc Hoa; Nguyen, Thi Dung; Pham, Thi Thu Suong; Nguyen, Van Khoa; Vu, Thi Thuy Trang; Nguyen, Thi Kim Phuong

2011-11-01

In the water treatment field, activated carbons (ACs) have wide applications in adsorptions. However, the applications are limited by difficulties encountered in separation and regeneration processes. Here, activated carbon/Fe(3)O(4) nanoparticle composites, which combine the adsorption features of powdered activated carbon (PAC) with the magnetic and excellent catalytic properties of Fe(3)O(4) nanoparticles, were fabricated by a modified impregnation method using HNO(3) as the carbon modifying agent. The obtained composites were characterized by X-ray diffraction, scanning and transmission electron microscopy, nitrogen adsorption isotherms and vibrating sample magnetometer. Their performance for methyl orange (MO) removal by adsorption was evaluated. The regeneration of the composite and PAC-HNO(3) (powdered activated carbon modified by HNO(3)) adsorbed MO by hydrogen peroxide was investigated. The composites had a high specific surface area and porosity and a superparamagnetic property that shows they can be manipulated by an external magnetic field. Adsorption experiments showed that the MO sorption process on the composites followed pseudo-second order kinetic model and the adsorption isotherm date could be simulated with both the Freundlich and Langmuir models. The regeneration indicated that the presence of the Fe(3)O(4) nanoparticles is important for a achieving high regeneration efficiency by hydrogen peroxide. Copyright © 2011 Elsevier Ltd. All rights reserved.

Polyaniline/Fe3O4-RGO Nanocomposites for Microwave Absorption

NASA Astrophysics Data System (ADS)

Mathew, Jithin; Sathishkumar, M.; Kothurkar, Nikhil K.; Senthilkumar, R.; Sabarish Narayanan, B.

2018-02-01

Fe3O4 nanoparticles were synthesized by co-precipitation of ferric chloride (FeCl3) and ferrous chloride (FeCl2). Reduced graphene oxide (RGO) was prepared by reducing the graphene oxide, which was synthesized by Hummer’s method, using hydrazine hydrate. Three nanocomposites based on sodium dodecyl benzene sulphonate (SDBS)-doped polyaniline were synthesized through in situ polymerization in the presence of the fillers (i) Fe3O4, (ii) reduced graphene oxide (RGO) and (iii) Fe3O4-decorated RGO respectively. The synthesized PANI and the composites were characterized by X-ray diffraction, Fourier transform infrared spectroscopy and transmission electron microscopy. Their microstructures, electrical conductivities, and EMI shielding effectiveness were studied. The nanocomposite containing 10 % RGO showed the maximum electrical conductivity and the one with 10 % RGO and 10 % Fe3O4 showed the maximum EMI shielding effectiveness of 7.5 dB for a 1 mm thick sample.

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

NASA Astrophysics Data System (ADS)

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.

Incorporation of Fe3O4/CNTs nanocomposite in an epoxy coating for corrosion protection of carbon steel

NASA Astrophysics Data System (ADS)

Pham, Gia Vu; Truc Trinh, Anh; To, Thi Xuan Hang; Duong Nguyen, Thuy; Trang Nguyen, Thu; Hoan Nguyen, Xuan

2014-09-01

In this study Fe3O4/CNTs composite with magnetic property was prepared by attaching magnetic nanoparticles (Fe3O4) to carbon nanotubes (CNTs) by hydrothermal method. The obtained Fe3O4/CNTs composite was characterized by Fourier transform infrared (FTIR) spectroscopy, powder x-ray diffraction and transmission electron microscopy. The Fe3O4/CNTs composite was then incorporated into an epoxy coating at concentration of 3 wt%. Corrosion protection of epoxy coating containing Fe3O4/CNTs composite was evaluated by electrochemical impedance spectroscopy and adhesion measurement. The impedance measurements show that Fe3O4/CNTs composite enhanced the corrosion protection of epoxy coating. The corrosion resistance of the carbon steel coated by epoxy coating containing Fe3O4/CNTs composite was significantly higher than that of carbon steel coated by clear epoxy coating and epoxy coating containing CNTs. FE-SEM photographs of fracture surface of coatings showed good dispersion of Fe3O4/CNTs composite in the epoxy matrix.

Oxidase-functionalized Fe(3)O(4) nanoparticles for fluorescence sensing of specific substrate.

PubMed

Liu, Cheng-Hao; Tseng, Wei-Lung

2011-10-03

This study reports the development of a reusable, single-step system for the detection of specific substrates using oxidase-functionalized Fe(3)O(4) nanoparticles (NPs) as a bienzyme system and using amplex ultrared (AU) as a fluorogenic substrate. In the presence of H(2)O(2), the reaction pH between Fe(3)O(4) NPs and AU was similar to the reaction of oxidase and the substrate. The catalytic activity of Fe(3)O(4) NPs with AU was nearly unchanged following modification with poly(diallyldimethylammonium chloride) (PDDA). Based on these features, we prepared a composite of PDDA-modified Fe(3)O(4) NPs and oxidase for the quantification of specific substrates through the H(2)O(2)-mediated oxidation of AU. By monitoring fluorescence intensity at 587 nm of oxidized AU, the minimum detectable concentrations of glucose, galactose, and choline were found to be 3, 2, and 20 μM using glucose oxidase-Fe(3)O(4), galactose oxidase-Fe(3)O(4), and choline oxidase-Fe(3)O(4) composites, respectively. The identification of glucose in blood was selected as the model to validate the applicability of this proposed method. Copyright © 2011 Elsevier B.V. All rights reserved.

Uniform Fe3O4 coating on flower-like ZnO nanostructures by atomic layer deposition for electromagnetic wave absorption.

PubMed

Wan, Gengping; Wang, Guizhen; Huang, Xianqin; Zhao, Haonan; Li, Xinyue; Wang, Kan; Yu, Lei; Peng, Xiange; Qin, Yong

2015-11-21

An elegant atomic layer deposition (ALD) method has been employed for controllable preparation of a uniform Fe3O4-coated ZnO (ZnO@Fe3O4) core-shell flower-like nanostructure. The Fe3O4 coating thickness of the ZnO@Fe3O4 nanostructure can be tuned by varying the cycle number of ALD Fe2O3. When serving as additives for microwave absorption, the ZnO@Fe3O4-paraffin composites exhibit a higher absorption capacity than the ZnO-paraffin composites. For ZnO@500-Fe3O4, the effective absorption bandwidth below -10 dB can reach 5.2 GHz and the RL values below -20 dB also cover a wide frequency range of 11.6-14.2 GHz when the coating thickness is 2.3 mm, suggesting its potential application in the treatment of the electromagnetic pollution problem. On the basis of experimental observations, a mechanism has been proposed to understand the enhanced microwave absorption properties of the ZnO@Fe3O4 composites.

Multifunctional Fe3O4/ZnO nanocomposites with magnetic and optical properties.

PubMed

Zou, Peng; Hong, Xia; Chu, Xueying; Li, Yajun; Liu, Yichun

2010-03-01

Multifunctional Fe3O4/ZnO nanocomposites were successfully synthesized through two-step solution-based methods. Fe3O4 nanoparticles were used as seeds for the deposit and growth of ZnO nanocrystals. Transmission electron microscopy (TEM) images, X-ray diffraction (XRD) patterns, and inductively coupled plasma-atomic emission spectroscopy (ICP-AES) were employed to observe the morphology, size, structure, and crystalline phase of the nanocomposites and confirm their chemical composition. The results of magnetization curves, resonant Raman scattering, and photoluminescence spectra revealed that the nanocomposites simultaneously possessed the super-paramagnetism of Fe3O4 and the multiphonon resonant Raman scattering and photoluminescence (PL) properties of ZnO. Compared with that of pure Fe3O4, the saturation magnetization of the Fe3O4 component within the nanocomposites was enhanced. The Raman spectroscopic fingerprint of ZnO component was preserved, and the fluorescent background was efficiently reduced. The interfacial effect was found to play an important role in modulating or improving the properties of the nanocomposites.

Intercalating graphene with clusters of Fe3O4 nanocrystals for electrochemical supercapacitors

NASA Astrophysics Data System (ADS)

Ke, Qingqing; Tang, Chunhua; Liu, Yanqiong; Liu, Huajun; Wang, John

2014-04-01

A hierarchical nanostructure consisting of graphene sheets intercalated by clusters of Fe3O4 nanocystals is developed for high-performance supercapacitor electrode. Here we show that the negatively charged graphene oxide (GO) and positively charged Fe3O4 clusters enable a strong electrostatic interaction, generating a hierarchical 3D nanostructure, which gives rise to the intercalated composites through a rational hydrothermal process. The electrocapacitive behavior of the resultant composites is systematically investigated by cyclic voltammeter and galvanostatic charge-discharge techniques, where a positive synergistic effect between graphene and Fe3O4 clusters is identified. A maximum specific capacitance of 169 F g-1 is achieved in the Fe3O4 clusters decorated with effectively reduced graphene oxide (Fe3O4-rGO-12h), which is much higher than those of rGO (101 F g-1) and Fe3O4 (68 F g-1) at the current density of 1 Ag-1. Moreover, this intercalated hierarchical nanostructure demonstrates a good capacitance retention, retaining over 88% of the initial capacity after 1000 cycles.

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

PubMed Central

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

[Preparation of molecularly imprinted polypyrrole/Fe3O4 composite material and its application in recognition of tryptophan enantiomers].

PubMed

Chen, Zhidong; Shan, Xueling; Kong, Yong

2012-04-01

Ferrosoferric oxide (Fe(3)O(4)) magnetic material was first synthesized, and then the in-situ chemical polymerization of pyrrole was carried out on the surface of Fe(3)O(4) by using pyrole and L-tryptophan (L-Trp) as the functional monomer and templates, respectively. As a result, molecularly imprinted polypyrrole/Fe(3)O(4) composite material was obtained. This composite material was separated from the solution because of its magnetic property. Polypyrrole in the composite was overoxidized in 1 mol/L NaOH solution by applying a potential of 1.0 V, and thus L-Trp templates were de-deoped from the composite. Scanning electron microscopy (SEM), X-ray diffraction (XRD) and electrochemical methods were employed to characterize the composite. The solution containing L- or D-Trp was pumped through a porous ceramic tube packed with the composite, separately. High performance liquid chromatography (HPLC) was adopted for the detection of L- or D-Trp in the eluate, and the results indicated that the enrichment ability of the composite for L-Trp was almost 2 times that of D-Trp. Therefore, the electro-magnetic composite material has potential applications as chromatographic stationary phase for chiral recognition.

Study of AC Magnetic Properties and Core Losses of Fe/Fe3O4-epoxy Resin Soft Magnetic Composite

NASA Astrophysics Data System (ADS)

Laxminarayana, T. A.; Manna, Subhendu Kumar; Fernandes, B. G.; Venkataramani, N.

Soft Magnetic Composites (SMC) were prepared by coating of nanocrystalline Fe3O4 particles, synthesized by co-precipitation method, on atomized iron powder of particle size less than 53 μm in size using epoxy resin as a binder between iron and Fe3O4. Fe3O4 was chosen, for its high electric resistivity and suitable magnetic properties, to keep the coating layer magnetic and seek improvement to the magnetic properties of SMC. SEM images and XRD patterns were recorded in order to investigate the coatings on the surface of iron powder. A toroid was prepared by cold compaction of coated iron powder at 1050 MPa and subsequently cured at 150˚C for 1 hr in argon atmosphere. For comparison of properties, a toroid of uncoated iron powder was also compacted at 1050 MPa and annealed at 600˚C for 2 hr in argon atmosphere. The coated iron powder composite has a resistivity of greater than 200 μΩm, measured by four probe method. A comparison of Magnetic Hysteresis loops and core losses using B-H Loop tracer in the frequency range 0 to 1500 Hz on the coated and uncoated iron powder is reported.

Fabrication and photocatalytic property of magnetic NiFe2O4/Cu2O composites

NASA Astrophysics Data System (ADS)

He, Zuming; Xia, Yongmei; Tang, Bin; Su, Jiangbin

2017-09-01

Magnetically separable NiFe2O4/Cu2O composites were successfully synthesized by a two-step method. The samples were characterized by XRD, XPS, SEM and VSM as well as their PL spectra and UV-vis adsorption spectra. The results showed that the NiFe2O4/Cu2O composites were composed of cubic-structured Cu2O and spinel-structured NiFe2O4, were able to absorb a large amount of visible light, exhibited excellent photocatalytic activity under simulated solar light irradiation and could be easily separated by an external magnetic field. The NiFe2O4/Cu2O composites exhibited higher photocatalytic performance than that of a single semiconductor. It was found that the prominently enhanced photocatalytic performance of NiFe2O4/Cu2O composites was ascribed to the effective separation of photo-generated electron-hole pairs and the effective generation of the hydroxyl radical •OH.

The Adsorption Capacity of GONs/CMC/Fe3O4 Magnetic Composite Microspheres and Applications for Purifying Dye Wastewater

PubMed Central

Lv, Shenghua; Zhu, Linlin; Li, Ying; Jia, Chunmao; Sun, Shiyu

2017-01-01

Graphene oxide nanosheets (GONs)/carboxymethyl chitosan (CMC)/Fe3O4 magnetic composite microspheres (MCMs) were prepared by enclosing Fe3O4 particles with CMC and GONs in turn. The microstructures of GONs and GONs/CMC/Fe3O4 MCMs were characterized by FTIR, XRD, TEM, and SEM. The effects of GON content, pH value, and adsorption time on the adsorption capacity of the MCMs were investigated. The results show that the GONs/CMC/Fe3O4 MCMs have a greater specific surface area and a strong adsorption capacity for dye wastewater. Meanwhile, the adsorption mechanism was investigated, and the results accorded with the pseudo-second-order kinetic model and the Freundlich isotherm model. The search results indicate that GONs/CMC/Fe3O4 MCMs can be used to purify dye wastewater and has an important potential use in the practical purification of dye wastewater. PMID:28772419

Degradation of sulfamethazine using Fe3O4-Mn3O4/reduced graphene oxide hybrid as Fenton-like catalyst.

PubMed

Wan, Zhong; Wang, Jianlong

2017-02-15

In this paper, Fe 3 O 4 -Mn 3 O 4 /reduced graphene oxide (RGO) hybrid was synthesized through polyol process and impregnation method and used as heterogeneous Fenton-like catalyst for degradation of sulfamethazine (SMT) in aqueous solution. The hybrid catalyst had higher catalytic efficiency compared with Fe 3 O 4 -Mn 3 O 4 and Mn 3 O 4 as catalyst for degradation of SMT . The effects of pH value, H 2 O 2 concentration, catalyst dosage, initial SMT concentration and temperature on SMT degradation were investigated. The removal efficiency of SMT was about 98% at following optimal conditions: pH=3, T=35°C, Fe 3 O 4 /Mn 3 O 4 -RGO composites=0.5g/L, H 2 O 2 =6mM. The inhibitor experiments indicated that the main active species was hydroxyl radicals (·OH) on catalyst surface. At last, the possible catalytic mechanism was proposed. Copyright © 2016 Elsevier B.V. All rights reserved.

Synthesis of composite magnetic nanoparticles Fe3O4 with alendronate for osteoporosis treatment

PubMed Central

Lee, Ming-Song; Su, Chao-Ming; Yeh, Jih-Chao; Wu, Pei-Ru; Tsai, Tien-Yao; Lou, Shyh-Liang

2016-01-01

Osteoporosis is a result of imbalance between bone formation by osteoblasts and resorption by osteoclasts (OCs). In the present study, we investigated the potential of limiting the aggravation of osteoporosis by reducing the activity of OCs through thermolysis. The proposed method is to synthesize bisphosphonate (Bis)-conjugated iron (II, III) oxide (Fe3O4) nanoparticles and incorporate them into OCs. The cells should be subsequently exposed to radiofrequency (RF) to induce thermolysis. In this study, particles of Fe3O4 were first synthesized by chemical co-precipitation and then coated with dextran (Dex). The Dex/Fe3O4 particles were then conjugated with Bis to form Bis/Dex/Fe3O4. Transmission electron microscopy revealed that the average diameter of the Bis/Dex/Fe3O4 particles was ~20 nm. All three kinds of nanoparticles were found to have cubic inverse spinel structure of Fe3O4 by the X-ray diffraction analysis. Fourier transform infrared spectroscopy confirmed that the Dex/Fe3O4 and Bis/Dex/Fe3O4 nanoparticles possessed their respective Dex and Bis functional groups, while a superconducting quantum interference device magnetometer measured the magnetic moment to be 24.5 emu. In addition, the Bis/Dex/Fe3O4 nanoparticles were fully dispersed in double-distilled water. Osteoblasts and OCs were individually cultured with the nanoparticles, and an MTT assay revealed that they were non-cytotoxic. An RF system (42 kHz and 450 A) was used to raise the temperature of the nanoparticles for 20 minutes, and the thermal effect was found to be sufficient to destroy OCs. Furthermore, in vivo studies verified that nanoparticles were indeed magnetic resonance imaging contrast agents and that they accumulated after being injected into the body of rats. In conclusion, we developed a water-dispersible magnetic nanoparticle that had RF-induced thermogenic properties, and the results indicated that the Bis/Dex/Fe3O4 nanoparticle had the potential for controlling osteoporosis. PMID

A novel flake-ball-like magnetic Fe3O4/γ-MnO2 meso-porous nano-composite: Adsorption of fluorinion and effect of water chemistry.

PubMed

Zhao, Zhiwei; Geng, Cong; Yang, Chun; Cui, Fuyi; Liang, Zhijie

2018-06-15

A novel flake-ball-like magnetic Fe 3 O 4 /γ-MnO 2 meso-porous nano-composite was synthesized and characterized for defluoridation. Adsorption process, characters, and effects of solution chemistry on the adsorption of flourinion in Fe 3 O 4 /γ-MnO 2 were evaluated. The results show that the adsorption of fluorinion in the Fe 3 O 4 /γ-MnO 2 nano-composite is fitted with the Pseudo-first model and the Langmuir model, indicating that the adsorption process of fluorinion in the Fe 3 O 4 /γ-MnO 2 nano-composite was a physical process and not only controlled by the film diffusion but also controlled by the intra-particle diffusion and surface adsorption. It shows that the adsorption of fluorinion sharply decrease with the increase of pH due to the negative changed surface of Fe 3 O 4 /γ-MnO 2 in water and the competition of OH - for the active points. The competition from decreases the adsorption of fluoride in the order of Cl -  < NO 3 -  < SO 4 2- , which relied on the ratio of charge towards radius (z/r) of the anions, and the negatively charged humic acid competed with fluorinion for the adsorption sites. Based on the adsorption results and the XPS analysis, the OMn bond in the raw adsorbent supported the active site (OMnOH) for fluoride adsorption by forming an OMnF bond on the surface of Fe3O4/γ-MnO2. Copyright © 2018 Elsevier Ltd. All rights reserved.

Interaction mechanisms between α-Fe2O3, γ-Fe2O3 and Fe3O4 nanoparticles and Citrus maxima seedlings.

PubMed

Li, Junli; Hu, Jing; Xiao, Lian; Wang, Yunqiang; Wang, Xilong

2018-06-01

The interactions between α-Fe 2 O 3 , γ-Fe 2 O 3 , and Fe 3 O 4 nanoparticles (NPs) and Citrus maxima seedlings were examined so as to better understand possible particle applications as an Fe source for crop plants. NPs toxicity to the exposed plant was investigated as well. The α- and γ-Fe 2 O 3 NPs were accumulated by plant root cells through diapirism and endocytosis, respectively, but translocation to the shoots was negligible. Analysis of malondialdehyde (MDA), soluble protein content, and antioxidant enzyme activity revealed that Fe deficiency induced strong oxidative stress in Citrus maxima seedlings, which followed an order of Fe deficiency>Fe 3+ >α-Fe 2 O 3 , γ-Fe 2 O 3 NPs>Fe 3 O 4 NPs. However, the chlorophyll leaf content of plants exposed to α-Fe 2 O 3 , γ-Fe 2 O 3 , Fe 3 O 4 NPs and Fe 3+ were significantly reduced by 31.1%, 14.8%, 18.8% and 22.0%, respectively, relative to the control. Furthermore, RT-PCR analysis revealed no up-regulation of AHA and Nramp3 genes in Citrus maxima roots; however, the relative FRO2 gene expression upon exposure to iron oxide NPs was 1.4-2.8-fold higher than the control. Ferric reductase activity was consistently enhanced upon iron oxide NPs exposure. These findings advance understanding of the interaction mechanisms between metal oxide NPs and plants, and provide important knowledge need for the possible application of these materials in agriculture. Copyright © 2017 Elsevier B.V. All rights reserved.

Removal of Cs+ from water and soil by ammonium-pillared montmorillonite/Fe3O4 composite.

PubMed

Zheng, Xianming; Dou, Junfeng; Yuan, Jing; Qin, Wei; Hong, Xiaoxi; Ding, Aizhong

2017-06-01

To remove cesium ions from water and soil, a novel adsorbent was synthesized by following a one-step co-precipitation method and using non-toxic raw materials. By combining ammonium-pillared montmorillonite (MMT) and magnetic nanoparticles (Fe 3 O 4 ), an MMT/Fe 3 O 4 composite was prepared and characterized. The adsorbent exhibited high selectivity of Cs + and could be rapidly separated from the mixed solution under an external magnetic field. Above all, the adsorbent had high removal efficiency in cesium-contaminated samples (water and soil) and also showed good recycling performance, indicating that the MMT/Fe 3 O 4 composite could be widely applied to the remediation of cesium-contaminated environments. It was observed that the pH, solid/liquid ratio and initial concentration affected adsorption capacity. In the presence of coexisting ions, the adsorption capacity decreased in the order of Ca 2+ >Mg 2+ >K + >Na + , which is consistent with our theoretical prediction. The adsorption behavior of this new adsorbent could be expressed by the pseudo-second-order model and Freundlich isotherm. In addition, the adsorption mechanism of Cs + was NH 4 + ion exchange and surface hydroxyl group coordination, with the former being more predominant. Copyright © 2016. Published by Elsevier B.V.

Production of nearly monodisperse Fe3O4 and Fe@Fe3O4 nanoparticles in aqueous medium and their surface modification for biomedical applications

NASA Astrophysics Data System (ADS)

Tegafaw, Tirusew; Xu, Wenlong; Lee, Sang Hyup; Chae, Kwon Seok; Chang, Yongmin; Lee, Gang Ho

2017-02-01

Iron (Fe)-based nanoparticles are extremely valuable in biomedical applications owing to their low toxicity and high magnetization values at room temperature. In this study, we synthesized nearly monodisperse iron oxide (Fe3O4) and Fe@Fe3O4 (core: Fe, shell: Fe3O4) nanoparticles in aqueous medium under argon flow and then, coated them with various biocompatible ligands and silica. In this study, eight types of surface-modified nanoparticles were investigated, namely, Fe3O4@PAA (PAA = polyacrylic acid; Mw of PAA = 5100 amu and 15,000 amu), Fe3O4@PAA-FA (FA = folic acid; Mw of PAA = 5100 amu and 15,000 amu), Fe3O4@PEI-fluorescein (PEI = polyethylenimine; Mw of PEI = 1300 amu), Fe@Fe3O4@PEI (Mw of PEI = 10,000 amu), Fe3O4@SiO2 and Fe@Fe3O4@SiO2 nanoparticles. We characterized the prepared surface-modified nanoparticles using high-resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD), Fourier transform infrared (FT-IR) absorption spectroscopy, a superconducting quantum interference device (SQUID), X-ray photoelectron spectroscopy (XPS), photoluminescence (PL) spectroscopy and confocal microscopy. Finally, we measured the cytotoxicity of the samples. The results indicate that the surface-modified nanoparticles are biocompatible and are potential candidates for various biomedical applications.

Magnetoelectricity in CoFe2O4 nanocrystal-P(VDF-HFP) thin films

PubMed Central

2013-01-01

Transition metal ferrites such as CoFe2O4, possessing a large magnetostriction coefficient and high Curie temperature (Tc > 600 K), are excellent candidates for creating magnetic order at the nanoscale and provide a pathway to the fabrication of uniform particle-matrix films with optimized potential for magnetoelectric coupling. Here, a series of 0–3 type nanocomposite thin films composed of ferrimagnetic cobalt ferrite nanocrystals (8 to 18 nm) and a ferroelectric/piezoelectric polymer poly(vinylidene fluoride-co-hexafluoropropene), P(VDF-HFP), were prepared by multiple spin coating and cast coating over a thickness range of 200 nm to 1.6 μm. We describe the synthesis and structural characterization of the nanocrystals and composite films by XRD, TEM, HRTEM, STEM, and SEM, as well as dielectric and magnetic properties, in order to identify evidence of cooperative interactions between the two phases. The CoFe2O4 polymer nanocomposite thin films exhibit composition-dependent effective permittivity, loss tangent, and specific saturation magnetization (Ms). An enhancement of the effective permittivity and saturation magnetization of the CoFe2O4-P(VDF-HFP) films was observed and directly compared with CoFe2O4-polyvinylpyrrolidone, a non-ferroelectric polymer-based nanocomposite prepared by the same method. The comparison provided evidence for the observation of a magnetoelectric effect in the case of CoFe2O4-P(VDF-HFP), attributed to a magnetostrictive/piezoelectric interaction. An enhancement of Ms up to +20.7% was observed at room temperature in the case of the 10 wt.% CoFe2O4-P(VDF-HFP) sample. PMID:24004499

Polylactide-based polyurethane shape memory nanocomposites (Fe3O4/PLAUs) with fast magnetic responsiveness

NASA Astrophysics Data System (ADS)

Gu, Shu-Ying; Jin, Sheng-Peng; Gao, Xie-Feng; Mu, Jian

2016-05-01

Polylactide-based polyurethane shape memory nanocomposites (Fe3O4/PLAUs) with fast magnetic responsiveness are presented. For the purpose of fast response and homogeneous dispersion of magnetic nanoparticles, oleic acid was used to improve the dispersibility of Fe3O4 nanoparticles in a polymer matrix. A homogeneous distribution of Fe3O4 nanoparticles in the polymer matrix was obtained for nanocomposites with low Fe3O4 loading content. A small agglomeration was observed for nanocomposites with 6 wt% and 9 wt% loading content, leading to a small decline in the mechanical properties. PLAU and its nanocomposites have glass transition around 52 °C, which can be used as the triggering temperature. PLAU and its nanocomposites have shape fixity ratios above 99%, shape recovery ratios above 82% for the first cycle and shape recovery ratios above 91% for the second cycle. PLAU and its nanocomposites also exhibit a fast water bath or magnetic responsiveness. The magnetic recovery time decreases with an increase in the loading content of Fe3O4 nanoparticles due to an improvement in heating performance for increased weight percentage of fillers. The nanocomposites have fast responses in an alternating magnetic field and have potential application in biomedical areas such as intravascular stent.

Magnetic properties of (SrFe{sub 12}O{sub 19}){sub x}(CaCu{sub 3}Ti{sub 4}O{sub 12}){sub 1–x} composites

DOE Office of Scientific and Technical Information (OSTI.GOV)

Eremina, R. M., E-mail: REremina@yandex.ru; Sharipov, K. R.; Yatsyk, I. V.

2016-07-15

New composite materials (SrFe{sub 12}O{sub 19}){sub x}(CaCu{sub 3}Ti{sub 4}O{sub 12}){sub 1–x} (x = 0, 0.05, 1) have been synthesized. Their magnetic properties are studied in the temperature range 5–300 K using the magnetic resonance and magnetometry methods. It is found that strontium hexaferrite microinclusions in the (SrFe{sub 12}O{sub 19}){sub 0.05}(CaCu{sub 3}Ti{sub 4}O{sub 12}){sub 0.95} composite “magnetize” CaCu{sub 3}Ti{sub 4}O{sub 12} at temperatures from 300 to 200 K, forming a ferrimagnetic particle near the SrFe{sub 12}O{sub 19} “core.” The magnetic resonance line below 200 K splits into two lines corresponding to SrFe{sub 12}O{sub 19} and CaCu{sub 3}Ti{sub 4}O{sub 12}. The coremore » effect decoration is manifested in the increase in the Curie–Weiss temperature from 25 K in CaCu{sub 3}Ti{sub 4}O{sub 12} without the doping ceramics to 80 K in the composite with 5% of SrFe{sub 12}O{sub 19}.« less

Formation of multiferroic PbTiO3/PbFe12O19 composite by exceeding the solubility limit of Fe in PbTiO3

NASA Astrophysics Data System (ADS)

Jaffari, G. Hassnain; Bilal, M.; Ur Rahman, Jamil; Lee, Soonil

2017-09-01

PbTiO3/PbFe12O19 composites have been synthesized by keeping the Fe concentration (x) in PbFexTi1-xO3 beyond solubility limit, i.e., x > 0.1% and 5% Pb excess. Both these factors have been successfully utilized to extract Fe doped PbTiO3 tetragonal phase which is composited with Magnetoplumbite (PbFe12O19) phase. A systematic evolution of the tetragonality of the former and improved stoichiometry of the later constituent has been observed. As x increases, emergence of additional Raman mode around 650 cm-1 with Fe addition was observed. Systematic increase in the relative intensity of this mode with x, showed that this mode corresponds to the magnetoplumbite phase. In addition to that resultant composite exhibited noticeable systematic decrease in the value of the energy gap as a function of x. Increasing Fe concentration in PbTiO3 constituent, led to monotonic decrease in c/a and increase in strain experienced by PbTiO3. Increase in the value of the saturation polarization was observed up to x = 0.4, which is identified to be associated with the strain induced by the dopant. A comprehensive magnetic characterization revealed monotonic decrease in magnetization with temperature for all compositions. Finally, we found an anomalous temperature dependent trend in the magnetic coercivity which is explained in terms of low temperature decrease in effective magnetic anisotropy by including magneto-electric coupling. Both constituent phases in the composite being ferroelectric and ferromagnetic at room temperature led to formation of better multiferroic properties and exhibited tunable physical properties with x.

Hybrid absorbers composed of Fe3O4 thin film and magnetic composite sheet and enhancement of conduction noise absorption on a microstrip line

NASA Astrophysics Data System (ADS)

Kim, Sung-Soo

2015-05-01

In response to develop wide-band noise absorbers with an improved low-frequency performance, this study investigates hybrid absorbers that are composed of conductive Fe3O4 thin film and magnetic composite sheets. The Fe3O4 films prepared via reactive sputtering exhibit a typical value of electrical resistivity of ≃10-4 Ωm. Rubber composites with flaky Fe-Si-Al particles of a high permeability and high permittivity are used as the magnetic sheet functioning as an electromagnetic shield barrier. Microstrip lines with a characteristic impedance of 50 Ω are used to measure the noise absorbing properties. For the Fe3O4 film with a low surface resistance and covered by the magnetic sheet, approximately 80% power absorption can be obtained at 1 GHz, which is significantly higher than that of the original magnetic sheet or Fe3O4 film. The high power absorption of the hybrid absorber is attributed to the enhanced ohmic loss of the Fe3O4 film through increased electric field strength bounded by the upper magnetic composite sheet. The noise absorption is further enhanced through increasing the electrical conductivity of the film containing more conductive phase (Fe3O4 + Fe), which can be prepared in a reduced oxygen partial pressure during reactive sputtering.

Comparison of Photocatalytic Performance of Different Types of Graphene in Fe3O4/SnO2 Composites

NASA Astrophysics Data System (ADS)

Paramarta, Valentinus; Taufik, Ardiansyah; Saleh, Rosari

2017-03-01

We have reported the role of annealing temperature Fe3O4/SnO2 nanocomposites as a photocatalyst for remove methylene blue (MB) dye from aqueous solution. However, how to enhanced the degradation performance of Fe3O4/SnO2 nanocomposites is important to its photocatalytic application. Therefore, in this work Fe3O4/SnO2 nanocomposites was combined with two different types of graphene materials (NGP and grahene) to improve the photocatalytic performance for remove methylene blue (MB) dye. Fe3O4/SnO2/NGP and Fe3O4/SnO2/graphene have been successfully synthesized by co-precipitation method. The influence of two types graphene on Fe3O4/SnO2 nanocomposites properties were systematically investigated by means of X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy and Thermal gravimetric analysis (TGA). Degradation of methylene Blue (MB) in aqueous solution was studied in detail under photocatalytic process. Effect of catalyst dosage (0.1-0.4 g/L) and scavengers on dye degradation were carried out to check the efficiency of photocatalyst. The results indicated Fe3O4/SnO2/graphene displayed higher photocatalytic activity than other catalyst. The reusability tests have also been done to ensure the stability of the used photocatalyst.

Oxalate enhanced degradation of Orange II in heterogeneous UV-Fenton system catalyzed by Fe3O4@γ-Fe2O3 composite.

PubMed

Dai, Huiwang; Xu, Shuying; Chen, Jianxin; Miao, Xiaozeng; Zhu, Jianxi

2018-05-01

Oxalate enhanced mechanism of Fe 3 O 4 @γ-Fe 2 O 3 was developed to provide novel insight into catalytic process regulation of iron oxide catalysts in heterogeneous UV-Fenton system. And the iron oxide composite of Fe 3 O 4 @γ-Fe 2 O 3 was characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), fourier transform infrared (FTIR) spectroscopy and nitrogen adsorption-desorption isotherms. The results showed that large amount of iron could be leached from catalyst in the presence of oxalate, which promoted the homogeneous UV-Fenton reactions in solution. Orange II degradation could be significantly enhanced with the increase of the ratio of homogeneous UV-Fenton process to heterogeneous UV-Fenton process. The optimum concentration of oxalate determined by experiment was 0.5 mM in oxalate enhanced heterogeneous UV-Fenton system. On this condition, the pseudo-first-order rate constant value of Orange II degradation was 0.314 min -1 , which was 2.3 times as high as that in heterogeneous UV-Fenton system. The removal rates of color and TOC were 100% and 86.6% after 20 min and 120 min treatment, respectively. In addition, the iron ions in solution could be almost completely adsorbed back to the catalyst surface in later degradation stages of Orange II. During the recycle experiments, the results showed that the increase of pH in solution and the sorption of intermediates on the catalyst surface would hinder oxalate enhanced process and lead to a decrease of degradation rate of Orange II in oxalate enhanced heterogeneous UV-Fenton system. Copyright © 2018 Elsevier Ltd. All rights reserved.

Enhanced microwave absorption properties of epoxy composites containing graphite nanosheets@Fe3O4 decorated comb-like MnO2 nanoparticles

NASA Astrophysics Data System (ADS)

Su, Xiaogang; Wang, Jun; Zhang, Bin; Chen, Wei; Wu, Qilei; Dai, Wei; Zou, Yi

2018-05-01

Recently, owing to the radiation and interference from electromagnetic wave (EMW), the requirements of EMW absorbing materials have been increasing. Herein, a novel absorber composed of graphite nanosheets@Fe3O4 composites decorated comb-like MnO2 (GNFM) has been successfully synthesized via a facile two steps, characterized using x-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), x-ray photoelectron spectroscopy (XPS), Raman spectroscopy, vibrating sample magnetometry (VSM) and vector network analyzer (VNA). The ternary composites with enhanced microwave absorption performance are due to the complementary effects of electroconductive material (graphite nanosheets), dielectric materials (MnO2) and magnetic material (Fe3O4 nanospheres). Hence, the maximum reflection loss of GNFM/epoxy composites is up to ‑31.7 dB at 5.85 GHz with absorbing thickness of 4.5 mm, and the efficient frequency bandwidth below ‑10 dB can reach up to 4.47 GHz (11.87–16.34 GHz) at matching thickness of 2 mm. The results demonstrate that GNFM could be regarded as a novel type of microwave absorbing material.

Fe2O3/ZnO/ZnFe2O4 composites for the efficient photocatalytic degradation of organic dyes under visible light

NASA Astrophysics Data System (ADS)

Li, Xiaojuan; Jin, Bo; Huang, Jingwen; Zhang, Qingchun; Peng, Rufang; Chu, Shijin

2018-06-01

In this study, novel ternary Fe2O3/ZnO/ZnFe2O4 (ZFO) composites were successfully prepared through a simple hydrothermal reaction with subsequent thermal treatment. The as-prepared products were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), Brunauer-Emmett-Teller (BET) analysis, Barrett-Joyner-Halenda (BJH) measurement, and UV-vis diffuse reflectance spectroscopy (UV-vis DRS). The photocatalytic degradation of rhodamine B (Rh B) under visible light irradiation indicated that the ZFO composites calcined at 500 °C has the best photocatalytic activity (the photocatalytic degradation efficiency can reach up to 95.7% within 60 min) and can maintain a stable photocatalytic degradation efficiency for at least three cycles. In addition, the photocatalytic activity of ZFO composites toward dye decomposition follows the order cationic Rh B > anionic methyl orange. Finally, using different scavengers, superoxide and hydroxyl radicals were identified as the primary active species during the degradation reaction of Rh B.

Structural and magnetic properties of nanostructured composites (SrFe12O19)x(CaCu3Ti4O12)1-x

NASA Astrophysics Data System (ADS)

Gavrilova, T. P.; Deeva, J. A.; Yatsyk, I. V.; Yagfarova, A. R.; Gilmutdinov, I. F.; Lyadov, N. M.; Milovich, F. O.; Chupakhina, T. I.; Eremina, R. M.

2018-05-01

(SrFe12O19)x(CaCu3Ti4O12)1-x (x = 0.01, 0.03, 0.07, 0.1) composites were synthesized using a solid state method, while the pre-synthesized strontium hexaferrite SrFe12O19 (SFO) was added to the stoichiometric amount of CaO, CuO and TiO oxides to form the CaCu3Ti4O12 (CCTO) structure around SFO microinclusions. The structural and microstructural properties of obtained composites were studied by X-ray diffraction, scanning electron microscopy and transmission electron microscopy techniques. The magnetic properties were studied by electron spin resonance and magnetometry methods. Based on all experimental data we can conclude, that SFOxCCTO1-x nanostructured composites were formed only for concentrations x = 0.03 and x = 0.07, where SFO nanoinclusions are inside CCTO matrix, that leads to the strong mutual influence of the magnetic properties of both component.

Influence of Ga-concentration on the electrical and magnetic properties of magnetoelectric CoGa xFe 2–xO 4/BaTiO 3 composite

DOE PAGES

Ni, Yan; Zhang, Zhen; Nlebedim, Cajetan I.; ...

2015-03-20

Multiferroic materials exhibit magnetoelectric (ME) coupling and promise new device applications including magnetic sensors, generators, and filters. An effective method for developing ME materials with enhanced ME effect is achieved by the coupling through the interfacial strain between piezoelectric and magnetostrictive materials. In this study, the electrical and magnetic properties of Ga doped magnetoelectric CoGa xFe 2–xO 4/BaTiO 3 composite are studied systematically. It is found that Ga doping improves the sensitivity of magnetoelastic response and stabilizes the magnetic phase of the composites. More importantly, Ga doping reduces the electrical conductivity of composite, as well as the dielectric loss. Anmore » enhancement of the electrostrain with doping Ga is also observed. Quantitative estimation indicates that magnetoelectric coupling is enhanced for Ga-doped CoGa xFe 2–xO 4/BaTiO 3 composites. As a result, the present work is beneficial to the practical application of composite CoFe 2O 4/BaTiO 3-based multiferroic materials.« less

Non-aqueous synthesis of water-dispersible Fe3O4-Ca3(PO4)2 core-shell nanoparticles

NASA Astrophysics Data System (ADS)

Liu, HongLing; Wu, JunHua; Min, Ji Hyun; Hou, Peng; Song, Ah-Young; Kim, Young Keun

2011-02-01

The Fe3O4-Ca3(PO4)2 core-shell nanoparticles were prepared by one-pot non-aqueous nanoemulsion with the assistance of a biocompatible triblock copolymer, poly(ethylene glycol)-block-poly(propylene glycol)-block-poly(ethylene glycol) (PEO-PPO-PEO), integrating the magnetic properties of Fe3O4 and the bioactive functions of Ca3(PO4)2 into single entities. The Fe3O4 nanoparticles were pre-formed first by thermal reduction of Fe(acac)3 and then the Ca3(PO4)2 layer was coated by simultaneous deposition of Ca2 + and PO43 - . The characterization shows that the combination of the two materials into a core-shell nanostructure retains the magnetic properties and the Ca3(PO4)2 shell forms an hcp phase (a = 7.490 Å, c = 9.534 Å) on the Fe3O4 surface. The magnetic hysteresis curves of the nanoparticles were further elucidated by the Langevin equation, giving an estimation of the effective magnetic dimension of the nanoparticles and reflecting the enhanced susceptibility response as a result of the surface covering. Fourier transform infrared (FTIR) analysis provides the characteristic vibrations of Ca3(PO4)2 and the presence of the polymer surfactant on the nanoparticle surface. Moreover, the nanoparticles could be directly transferred to water and the aqueous dispersion-collection process of the nanoparticles was demonstrated for application readiness of such core-shell nanostructures in an aqueous medium. Thus, the construction of Fe3O4 and Ca3(PO4)2 in the core-shell nanostructure has conspicuously led to enhanced performance and multi-functionalities, offering various possible applications of the nanoparticles.

High Energy Density Asymmetric Supercapacitor Based on NiOOH/Ni3S2/3D Graphene and Fe3O4/Graphene Composite Electrodes

PubMed Central

Lin, Tsung-Wu; Dai, Chao-Shuan; Hung, Kuan-Chung

2014-01-01

The application of the composite of Ni3S2 nanoparticles and 3D graphene as a novel cathode material for supercapacitors is systematically investigated in this study. It is found that the electrode capacitance increases by up to 111% after the composite electrode is activated by the consecutive cyclic voltammetry scanning in 1 M KOH. Due to the synergistic effect, the capacitance and the diffusion coefficient of electrolyte ions of the activated composite electrode are ca. 3.7 and 6.5 times higher than those of the Ni3S2 electrode, respectively. Furthermore, the activated composite electrode exhibits an ultrahigh specific capacitance of 3296 F/g and great cycling stability at a current density of 16 A/g. To obtain the reasonable matching of cathode/anode electrodes, the composite of Fe3O4 nanoparticles and chemically reduced graphene oxide (Fe3O4/rGO) is synthesized as the anode material. The Fe3O4/rGO electrode exhibits the specific capacitance of 661 F/g at 1 A/g and excellent rate capability. More importantly, an asymmetric supercapacitor fabricated by two different composite electrodes can be operated reversibly between 0 and 1.6 V and obtain a high specific capacitance of 233 F/g at 5 mV/s, which delivers a maximum energy density of 82.5 Wh/kg at a power density of 930 W/kg. PMID:25449978

Solvothermal synthesis of Au@Fe3O4 nanoparticles for antibacterial applications

NASA Astrophysics Data System (ADS)

Kelgenbaeva, Zhazgul; Abdullaeva, Zhypargul; Murzubraimov, Bektemir

2018-04-01

We present Au@Fe3O4 nanoparticles obtained from Fe nanoparticles and HAuCl4 using a simple solvothermal method. Trisodium citrate (C6H5Na3O7*2H2O) served as a reducing agent for Au. X-ray diffraction analysis, electronic microscopes and energy-dispersive X-ray spectroscopy revealed cubic structure, elemental composition (Au, Fe and O) and spherical shape of nanoparticles. Antibacterial activity of the sample was tested against E. coli bacteria and obtained results were discussed.

The synthesis and the magnetic properties of Gd 3+-doped Fe xCo 1-x/Co yFe 3-yO 4 micro-octahedrons composites

NASA Astrophysics Data System (ADS)

Wang, Qin; Li, Shuiming; Wu, Aibing; Yang, Hua

2009-09-01

Gd 3+-substituted micro-octahedron composites (Fe xCo 1-x/Co yGd zFe 3-y-zO 4) in which the Fe-Co alloy has either a bcc or fcc structure and the oxide is a spinel phase were fabricated by the hydrothermal method. The X-ray diffraction (XRD) patterns indicate that the as-synthesized Gd 3+-substituted micro-octahedron composites are well crystallized. Scanning electron microscopy (SEM) images show that the final product consists of larger numbers of micro-octahedrons with the size ranging from 1.3 to 5 μm, and the size of products are increased with increasing the concentration of KOH. The effect of the Co 2+/Fe 2+ ratio (0⩽Co 2+/Fe 2+⩽1) and substitution Fe 3+ ions by Gd 3+ ions on structure, magnetic properties of the micro-octahedrons composites were investigated, and a possible growth mechanism is suggested to explain the formation of micro-octahedrons composites. The magnetic properties of the structure show the maximal saturation magnetization (107 emu/g) and the maximal coercivity (1192 Oe) detected by a vibrating sample magnetometer.

Use of hydroxypropyl-β-cyclodextrin/polyethylene glycol 400, modified Fe3O4 nanoparticles for congo red removal.

PubMed

Yu, Lan; Xue, Weihua; Cui, Lei; Xing, Wen; Cao, Xinli; Li, Hongyu

2014-03-01

Fe3O4 nanoparticles were modified with Hydroxypropyl-β-cyclodextrin (HP-β-CD) and Polyethylene glycol 400 (PEG400) by a facile one-pot homogeneous precipitation method, and were used as a novel nano-adsorbent for the removal of congo red (CR) from aqueous solutions. The polymer-modified composites were characterized by FTIR, TEM, TGA, XRD and VSM, and showed excellent adsorption efficiency for CR. The value of the maximum adsorption capacity calculated according to the Langmuir isotherm model were 1.895g/g, which are much high and about 19 times that of Fe3O4 nanoparticles. Desorption study further indicates the good regeneration ability of the nanocomposites. The results suggest that the HP-β-CD/PEG400-modified Fe3O4 nanoparticles is a promising adsorbent for CR removal from aqueous solutions, and it is easily recycled owing to its large specific surface area and unique magnetic responsiveness. Crown Copyright © 2013. Published by Elsevier B.V. All rights reserved.

Phase-pure eutectic CoFe2O4-Ba1-xSrxTiO3 composites prepared by floating zone melting

NASA Astrophysics Data System (ADS)

Breitenbach, Martin; Ebbinghaus, Stefan G.

2018-02-01

Composites consisting of ferrimagnetic CoFe2O4 and ferroelectric Ba1-xSrxTiO3 were grown by the floating zone technique. The influence of Sr substitution, growth rate and atmosphere during the floating zone process were investigated. The formation of the non-ferroelectric, hexagonal modification of BaTiO3 was avoided by a slight Sr substitution of 3 mol% and the formation of BaFe12O19 was suppressed using pure nitrogen as atmosphere during the floating zone melting. These synthesis parameters led to phase-pure, but electrically conductive CoFe2O4-Ba1-xSrxTiO3 composites. A thermal treatment at 973 K in air resulted in a strong increase of the electric resistivity accompanied by a decrease of the unit-cell parameters of both components indicating the healing of oxygen defects. SEM investigations revealed a variety of different geometric structures and crack-free interfaces between both phases. The low porosities observed in the micrographs correspond with densities above 90%. Magnetoelectric (ME) measurements confirmed a coupling between the ferroic orders of both phases with a hysteresis and maximum αME of 1.3 mV Oe-1 cm-1.

Fabrication by Electrophoretic Deposition of Nano-Fe3O4 and Fe3O4@SiO2 3D Structure on Carbon Fibers as Supercapacitor Materials

NASA Astrophysics Data System (ADS)

Hajalilou, Abdollah; Abouzari-Lotf, Ebrahim; Etemadifar, Reza; Abbasi-Chianeh, Vahid; Kianvash, Abbas

2018-05-01

Core-shell nanostructured magnetic Fe3O4@SiO2 with particle size ranging from 3 nm to 40 nm has been synthesized via a facile precipitation method. Tetraethyl orthosilicate was employed as surfactant to prepare core-shell structures from Fe3O4 nanoparticles synthesized from pomegranate peel extract using a green method. X-ray diffraction analysis, Fourier-transform infrared and ultraviolet-visible (UV-Vis) spectroscopies, transmission electron microscopy, and scanning electron microscopy with energy-dispersive spectroscopy were employed to characterize the samples. The prepared Fe3O4 nanoparticles were approximately 12 nm in size, and the thickness of the SiO2 shell was 4 nm. Evaluation of the magnetic properties indicated lower saturation magnetization for Fe3O4@SiO2 powder ( 11.26 emu/g) compared with Fe3O4 powder ( 13.30 emu/g), supporting successful wrapping of the Fe3O4 nanoparticles by SiO2. As-prepared powders were deposited on carbon fibers (CFs) using electrophoretic deposition and their electrochemical behavior investigated. The rectangular-shaped cyclic voltagrams of Fe3O4@CF and Fe3O4@C@CF samples indicated electrochemical double-layer capacitor (EDLC) behavior. The higher specific capacitance of 477 F/g for Fe3O4@C@CF (at scan rate of 0.05 V/s in the potential range of - 1.13 to 0.45 V) compared with 205 F/g for Fe3O4@CF (at the same scan rate in the potential range of - 1.04 to 0.24 V) makes the former a superior candidate for use in energy storage applications.

Synthesis of hierarchical Mg-doped Fe3O4 micro/nano materials for the decomposition of hexachlorobenzene.

PubMed

Su, Guijin; Liu, Yexuan; Huang, Linyan; Lu, Huijie; Liu, Sha; Li, Liewu; Zheng, Minghui

2014-03-01

An ethylene-glycol (EG) mediated self-assembly process was firstly developed to synthesize micrometer-sized nanostructured Mg-doped Fe3O4 composite oxides to decompose hexachlorobenzene (HCB) at 300°C. The synthesized samples were characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, energy dispersive X-ray spectroscopy and inductively coupled plasma optical emission spectrometer. The morphology and composition of the composite oxide precursor were regulated by the molar ratio of the magnesium acetate and ferric nitrate as the reactants. Calcination of the precursor particles, prepared with different molar ratio of the metal salts, under a reducing nitrogen atmosphere, generated three kinds of Mg doped Fe3O4 composite oxide micro/nano materials. Their reactivity toward HCB decomposition was likely influenced by the material morphology and content of Mg dopants. Ball-like MgFe2O4-Fe3O4 composite oxide micro/nano material showed superior HCB dechlorination efficiencies when compared with pure Fe3O4 micro/nano material, prepared under similar experimental conditions, thus highlighting the benefits of doping Mg into Fe3O4 matrices. Copyright © 2013 Elsevier Ltd. All rights reserved.

The Electrochemistry of Fe 3 O 4 /Polypyrrole Composite Electrodes in Lithium-Ion Cells: The Role of Polypyrrole in Capacity Retention

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bruck, Andrea M.; Gannett, Cara N.; Bock, David C.

In two series of magnetite (Fe 3O4) composite electrodes, one group with and one group without added carbon, containing varying quantities of polypyrrole (PPy), and a non-conductive polyvinylidene difluoride (PVDF) binder were constructed and then analyzed using electrochemical and spectroscopic techniques. Galvanostatic cycling and alternating current (AC) impedance measurements were used in tandem to measure delivered capacity, capacity retention, and the related impedance at various stages of discharge and charge. Further, the reversibility of Fe 3O 4 to iron metal (Fe0) conversion observed during discharge was quantitatively assessed ex-situ using X-ray Absorption Spectroscopy (XAS). The Fe 3O 4 composite containingmore » the largest weight fraction of PPy (20 wt%) with added carbon demonstrated reduced irreversible capacity on initial cycles and improved cycling stability over 50 cycles, attributed to decreased reaction with the electrolyte in the presence of PPy. Our study illustrated the beneficial role of PPy addition to Fe 3O 4 based electrodes was not strongly related to improved electrical conductivity, but rather to improved ion transport related to the formation of a more favorable surface electrolyte interphase (SEI).« less

The Electrochemistry of Fe 3 O 4 /Polypyrrole Composite Electrodes in Lithium-Ion Cells: The Role of Polypyrrole in Capacity Retention

DOE PAGES

Bruck, Andrea M.; Gannett, Cara N.; Bock, David C.; ...

2016-12-15

In two series of magnetite (Fe 3O4) composite electrodes, one group with and one group without added carbon, containing varying quantities of polypyrrole (PPy), and a non-conductive polyvinylidene difluoride (PVDF) binder were constructed and then analyzed using electrochemical and spectroscopic techniques. Galvanostatic cycling and alternating current (AC) impedance measurements were used in tandem to measure delivered capacity, capacity retention, and the related impedance at various stages of discharge and charge. Further, the reversibility of Fe 3O 4 to iron metal (Fe0) conversion observed during discharge was quantitatively assessed ex-situ using X-ray Absorption Spectroscopy (XAS). The Fe 3O 4 composite containingmore » the largest weight fraction of PPy (20 wt%) with added carbon demonstrated reduced irreversible capacity on initial cycles and improved cycling stability over 50 cycles, attributed to decreased reaction with the electrolyte in the presence of PPy. Our study illustrated the beneficial role of PPy addition to Fe 3O 4 based electrodes was not strongly related to improved electrical conductivity, but rather to improved ion transport related to the formation of a more favorable surface electrolyte interphase (SEI).« less

Synthesis and characterization of magnetic opal/Fe3O4 colloidal crystal

NASA Astrophysics Data System (ADS)

Carmona-Carmona, A. J.; Palomino-Ovando, M. A.; Hernández-Cristobal, Orlando; Sánchez-Mora, E.; Toledo-Solano, M.

2017-03-01

We report an experimental study of colloidal crystals based on SiO2 artificial opals, infiltrated with 1.34(M1), 2.03(M2) and 24.4(M3) wt% Fe3O4 nanoparticles, using the co-assembly method. Scanning electron microscopy (SEM), X-ray diffraction (XRD), Raman spectroscopy and Vibration sample magnetometer (VSM) were used to study the structural, magnetic and optical properties of the samples. At 300 K all the samples exhibit superparamagnetic behavior due to the magnetic coupling of Fe3O4 nanoparticles infiltrated into opal. However, for higher concentration of nanoparticles this strong coupling distorts the opal network. The UV-vis diffuse reflectance spectroscopy and Kubelka-Munk theory were applied to determine that the energy band gap of the opal-magnetite composites can be adjusted by varying the concentration of Fe3O4 nanoparticles. This values are between the energy band gap of SiO2 and Fe3O4.

Sodium citrate functionalized reusable Fe3O4@TiO2 photocatalyst for water purification

NASA Astrophysics Data System (ADS)

Li, Wenyu; Wu, Haoyi

2017-10-01

Easy-recycle photocatalysts are new materials for water treatment technologies. In order to improve the recyclable ability, we employed Fe3O4 particles, which were functionalized by sodium citrate, to serve as a substrate core to attract the deposition of a shell of TiO2 particles. When compared to the calcining process for preparing the composite, the TiO2 distributed homogeneously on the sodium citrate treated Fe3O4, forming a mesoporous shell layer. Due to the mesoporous structure, this Fe3O4@TiO2 exhibited high photocatalytic degradation activity to Rhodamine B, and it was easily recycled using a magnetic field to recover the catalyst from solution.

Incorporation of the Fe3O4 and SiO2 nanoparticles in epoxy-modified silicone resin as the coating for soft magnetic composites with enhanced performance

NASA Astrophysics Data System (ADS)

Luo, Dahao; Wu, Chen; Yan, Mi

2018-04-01

Three inorganic-organic hybrids have been designed by incorporating epoxy-modified silicone resin (ESR) with SiO2, Fe3O4 and their mixture in the application as the coating of Fe soft magnetic composites (SMCs). The introduced SiO2 nanoparticles are well dispersed in the ESR, while the Fe3O4 tends to agglomerate or even separate from the ESR. Simultaneous addition of the SiO2 and Fe3O4 gives rise to satisfactory distribution of both nanoparticles and optimized magnetic performance of the SMCs with high permeability (124.6) and low loss (807.8 mW/cm3). On one hand, introduction of the ferromagnetic Fe3O4 reduces the magnetic dilution effect, which is beneficial for improved magnetization and permeability. On the other hand, SiO2 incorporation prevents the agglomeration of the Fe3O4 nanoparticles and gives rise to increased electrical resistivity for reduced core loss as well as enhanced mechanical strength of the SMCs.

Carbon-coated CoFe-CoFe2O4 composite particles with high and dual-band electromagnetic wave absorbing properties.

PubMed

Guan, Zhen-Jie; Jiang, Jian-Tang; Chen, Na; Gong, Yuan-Xun; Zhen, Liang

2018-07-27

SiO 2 and TiO 2 , as conventional dielectric shells of ferromagnetic/dielectric composite particles, can protect ferromagnetic particles from aggregation and oxidation, but contribute little to electromagnetic loss. In this work, we designed nano-assembled CoFe-CoFe 2 O 4 @C composite particles, in which ferrites with high permeability were dielectric elements and carbon was introduced as protective layers, aiming for high-efficiency microwave absorption. These assembled particles with different CoFe contents were prepared through solvothermal methods and subsequent hydrogen-thermal reduction. CoFe nanoparticles were dispersed on a CoFe 2 O 4 matrix via an in situ reduction transformation from CoFe 2 O 4 to CoFe. The microstructure evolution of composite particles and corresponding electromagnetic properties tailoring were investigated. The content and size of CoFe as well as the porosity of composite particles increase gradually as the annealing temperature increases. A maximum reflection loss (RL max ) of -71.73 dB is observed at 4.78 GHz in 3.4 mm thick coating using particles annealed at 500 °C as fillers. The coating presents double-band absorbing characteristics, as broad effective absorption bandwidth with RL > 5 (ERL 5 ) and high RL max are observed in both S-C and X-K u bands. The tunability as well as the assembled characteristic of the electromagnetic property that endued from the composite structure contributes to the excellent electromagnetic wave absorbing performances.

Fe{sub 3}O{sub 4}/CuO/ZnO/Nano graphene platelets (Fe{sub 3}O{sub 4}/CuO/ZnO/NGP) composites prepared by sol-gel method with enhanced sonocatalytic activity for the removal of dye

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hendry, Tju; Taufik, Ardiansyah; Saleh, Rosari, E-mail: rosari.saleh@gmail.com, E-mail: rosari.saleh@ui.ac.id

2016-04-19

In this study, an attempt has been made to synthesize nanographene platelets coupled with Fe3O4/CuO/ZnO (Fe3O4/CuO/ZnO/NGP) with various ZnO loadings using a two step methods, sol-gel followed by hydrothermal method. Characterization was carried out by X-ray diffraction, energy-dispersive X-ray spectroscopy and vibrating sample magnetometer. The sonocatalytic performance was evaluated by degradation of methylene blue under ultrasonic irradiation.The Fe3O4/CuO/ZnO/NGP showed superior sonocatalytic activity than the Fe3O4/CuO/ZnO materials. They also showed high stability and can be easily separated from the reaction system for recycling process.

Preparation of surface plasmon resonance biosensor based on magnetic core/shell Fe3O4/SiO2 and Fe3O4/Ag/SiO2 nanoparticles.

PubMed

Wang, Liying; Sun, Ying; Wang, Jing; Wang, Jian; Yu, Aimin; Zhang, Hanqi; Song, Daqian

2011-06-01

In this paper, surface plasmon resonance biosensors based on magnetic core/shell Fe(3)O(4)/SiO(2) and Fe(3)O(4)/Ag/SiO(2) nanoparticles were developed for immunoassay. With Fe(3)O(4) and Fe(3)O(4)/Ag nanoparticles being used as seeding materials, Fe(3)O(4)/SiO(2) and Fe(3)O(4)/Ag/SiO(2) nanoparticles were formed by hydrolysis of tetraethyl orthosilicate. The aldehyde group functionalized magnetic nanoparticles provide organic functionality for bioconjugation. The products were characterized by scanning electronic microscopy (SEM), transmission electronic microscopy (TEM), FTIR and UV-vis absorption spectrometry. The magnetic nanoparticles possess the unique superparamagnetism property, exceptional optical properties and good compatibilities, and could be used as immobilization matrix for goat anti-rabbit IgG. The magnetic nanoparticles can be easily immobilized on the surface of SPR biosensor chip by a magnetic pillar. The effects of Fe(3)O(4)/SiO(2) and Fe(3)O(4)/Ag/SiO(2) nanoparticles on the sensitivity of SPR biosensors were also investigated. As a result, the SPR biosensors based on Fe(3)O(4)/SiO(2) nanoparticles and Fe(3)O(4)/Ag/SiO(2) nanoparticles exhibit a response for rabbit IgG in the concentration range of 1.25-20.00 μg ml(-1) and 0.30-20.00 μg ml(-1), respectively. Copyright © 2011 Elsevier B.V. All rights reserved.

Preparation of High Mechanical Performance Nano-Fe3O4/Wood Fiber Binderless Composite Boards for Electromagnetic Absorption via a Facile and Green Method

PubMed Central

Dang, Baokang; Chen, Yipeng; Wang, Hanwei; Chen, Bo; Jin, Chunde; Sun, Qingfeng

2018-01-01

Fe3O4/wood fiber composites are prepared with a green mechanical method using only distilled water as a solvent without any chemical agents, and then a binderless composite board with high mechanical properties is obtained via a hot-press for electromagnetic (EM) absorption. The fibers are connected by hydrogen bonds after being mechanically pretreated, and Fe3O4 nanoparticles (NPs) are attached to the fiber surface through physical adsorption. The composite board is bonded by an adhesive, which is provided by the reaction of fiber composition under high temperature and pressure. The Nano-Fe3O4/Fiber (NFF) binderless composite board shows remarkable microwave absorption properties and high mechanical strength. The optional reflection loss (RL) of the as-prepared binderless composite board is −31.90 dB. The bending strength of the NFF binderless composite board is 36.36 MPa with the addition of 6% nano-Fe3O4, the modulus of elasticity (MOE) is 6842.16 MPa, and the internal bond (IB) strength is 0.81 MPa. These results demonstrate that magnetic nanoparticles are deposited in binderless composite board by hot pressing, which is the easiest way to produce high mechanical strength and EM absorbers. PMID:29361726

Zn0-CNTs-Fe3O4 catalytic in situ generation of H2O2 for heterogeneous Fenton degradation of 4-chlorophenol.

PubMed

Yang, Zhao; Gong, Xiao-Bo; Peng, Lin; Yang, Dan; Liu, Yong

2018-06-04

A novel Zn 0 -CNTs-Fe 3 O 4 composite was synthesized by the chemical co-precipitation combined with high sintering process at nitrogen atmosphere. The as-prepared composite was characterized by SEM, EDS, XRD, XPS, VSM and N 2 adsorption/desorption experiments. A novel heterogeneous Fenton-like system, composed of Zn 0 -CNTs-Fe 3 O 4 composite and dissolved oxygen (O 2 ) in solution, which can in situ generate H 2 O 2 and OH, was used for the degradation of 4-chlorophenol (4-CP). The influences of various operational parameters, including the initial pH, dosage of Zn 0 -CNTs-Fe 3 O 4 and initial concentration of 4-CP on the removal of 4-CP were investigated. The removal efficiencies of 4-CP and total organic carbon (TOC) were 99% and 57%, respectively, at the initial pH of 1.5, Zn 0 -CNTs-Fe 3 O 4 dosage of 2 g/L, 4-CP initial concentration of 50 mg/L and oxygen flow rate of 400 mL/min. Based on the results of the radical scavenger effect study, the hydroxyl radical was considered as the main reactive oxidants in Zn 0 -CNTs-Fe 3 O 4 /O 2 system and a possible degradation pathway of 4-CP was proposed. Copyright © 2018. Published by Elsevier Ltd.

Facile synthesis of nanorod-type graphitic carbon nitride/Fe{sub 2}O{sub 3} composite with enhanced photocatalytic performance

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Jiangpeng; Li, Changqing; Cong, Jingkun

2016-06-15

Here we report a facile synthesis of nanorod-type graphitic carbon nitride/Fe{sub 2}O{sub 3} composite (Fe{sub 2}O{sub 3}-g-C{sub 3}N{sub 4}) by using Fe-melamine supramolecular framework as precursor. The chemical and optical properties of the nanocomposites are well-characterized. The Fe{sub 2}O{sub 3}-g-C{sub 3}N{sub 4} nanocomposite demonstrated excellent photocatalytic activities under visible light due to the efficient utilization of sunlight and the construction of Z-scheme electron transfer pathway. The results indicated that it could be a promising approach for the preparation of efficient g-C{sub 3}N{sub 4} nanocomposites photocatalysts by using metal-melamine supramolecular framework as precursors. - Graphical abstract: Nanorod-type graphitic carbon nitride/Fe{sub 2}O{submore » 3} composite (Fe{sub 2}O{sub 3}-g-C{sub 3}N{sub 4}) was synthesized by using Fe-melamine supramolecular framework as precursor. The Fe{sub 2}O{sub 3}-g-C{sub 3}N{sub 4} nanocomposite demonstrated excellent photocatalytic activities under visible light. Display Omitted - Highlights: • Nanorod-type graphitic carbon nitride/Fe{sub 2}O{sub 3} composite (Fe{sub 2}O{sub 3}-g-C{sub 3}N{sub 4}) was synthesized. • Fe{sub 2}O{sub 3}-g-C{sub 3}N{sub 4} showed strong optical absorption in the visible-light region. • The Fe{sub 2}O{sub 3}-g-C{sub 3}N{sub 4} nanocomposite demonstrated excellent photocatalytic activities.« less

Novel ZnO/MgO/Fe2O3 composite optomagnetic nanoparticles.

PubMed

Kamińska, I; Sikora, B; Fronc, K; Dziawa, P; Sobczak, K; Minikayev, R; Paszkowicz, W; Elbaum, D

2013-05-15

A facile sol-gel synthesis of novel ZnO/MgO/Fe2O3 nanoparticles (NPs) is reported and their performance is compared to that of ZnO/MgO. Powder x-ray diffraction (XRD) patterns reveal the crystal structure of the prepared samples. The average particle size of the sample was found to be 4.8 nm. The optical properties were determined by UV-vis absorption and fluorescence measurements. The NPs are stable in biologically relevant solutions (phosphate buffered saline (PBS), 20 mM, pH = 7.0) contrary to ZnO/MgO NPs which degrade in the presence of inorganic phosphate. Superparamagnetic properties were determined with a superconducting quantum interference device (SQUID). Biocompatible and stable in PBS ZnO/MgO/Fe2O3 core/shell composite nanocrystals show luminescent and magnetic properties confined to a single NP at room temperature (19-24 ° C), which may render the material to be potentially useful for biomedical applications.

Monodisperse NixFe3-xO4 nanospheres: Metal-ion-steered size/composition control mechanism, static magnetic and enhanced microwave absorbing properties

NASA Astrophysics Data System (ADS)

Jiang, Kedan; Liu, Yun; Pan, Yefei; Wang, Ru; Hu, Panbing; He, Rujia; Zhang, Lingli; Tong, Guoxiu

2017-05-01

An easy metal-ion-steered solvothermal method was developed for the one-step synthesis of monodisperse, uniform NixFe3-xO4 polycrystalline nanospheres with tunable sphere diameter (40-400 nm) and composition (0 ≤ x ≤ 0.245) via changing just Ni2+/Fe3+ molar ratio (γ). With g increased from 0:1 to 2:1, sphere diameter gradually decreased and crystal size exhibited an inversed U-shaped change tendency, followed by increased Ni/Fe atom ratio from 0% to 0.0888%. An in situ-reduction, coordination-precipitation transformation mechanism was proposed to interpret the metal-ion-steered growth. Size- and composition-dependent static magnetic and microwave absorbing properties were systematically investigated. Saturation magnetization declines with g in a Boltzmann model due to the changes of crystal size, sphere diameter, and Ni content. The coercivity reaches a maximum at γ = 0.75:1 because of the critical size of Fe3O4 single domain (25 nm). Studies on microwave absorption reveal that 150-400 nm Fe3O4 nanospheres mainly obey the quarter-wavelength cancellation model with the single-band absorption; 40-135 nm NixFe3-xO4 nanospheres (0 ≤ x ≤ 0.245) obey the one and three quarter-wavelength cancellation model with the multi-band absorption. 150 nm Fe3O4 nanospheres exhibit the optimal EM wave-absorbing property with an absorbing band of 8.94 GHz and the maximum RL of -50.11 dB.

Electrophoretically-Deposited Nano-Fe3O4@carbon 3D Structure on Carbon Fiber as High-Performance Supercapacitors

NASA Astrophysics Data System (ADS)

Hajalilou, Abdollah; Etemadifar, Reza; Abbasi-Chianeh, Vahid; Abouzari-Lotf, Ebrahim

2018-05-01

Structural and electrochemical behaviors of electrophortically-deposited Fe3O4 and Fe3O4@C nanoparticles on carbon fiber (CF) were investigated. The nanoparticles were synthesized via a green-assisted hydrothermal route. The as-prepared samples were characterized by x-ray diffraction, transmission and scanning electron microscopies, Fourier transform infrared and UV-visible spectroscopies as well as by a vibration sample magnetometer. Surprisingly, the saturation magnetization (M s) of the Fe3O4@C ( 26.99 emu/g) was about 20% higher than that of Fe3O4 nanoparticles. A rather rectangular CV curve for both the elecrophortically-deposited Fe3O4 and Fe3O4@C on CF indicated the double-layer supercapacitor behavior of the samples. The synergistic effects of double shells improved the electrochemical behavior of Fe3O4@CF. The Fe3O4@C@CF composite exhibited a higher specific capacitance of 412 F g-1 at scan rate of 0.05 V/s compared to the Fe3O4@CF with a value of 193 F g-1. The superb electrochemical properties of Fe3O4@C@CF confirm their potential for applications as supercapacitors in the energy storage field.

Conformal Fe3O4 sheath on aligned carbon nanotube scaffolds as high-performance anodes for lithium ion batteries.

PubMed

Wu, Yang; Wei, Yang; Wang, Jiaping; Jiang, Kaili; Fan, Shoushan

2013-02-13

A uniform Fe(3)O(4) sheath is magnetron sputtered onto aligned carbon nanotube (CNT) scaffolds that are directly drawn from CNT arrays. The Fe(3)O(4)-CNT composite electrode, with the size of Fe(3)O(4) confined to 5-7 nm, exhibits a high reversible capacity over 800 mAh g(-1) based on the total electrode mass, remarkable capacity retention, as well as high rate capability. The excellent performance is attributable to the superior electrical conductivity of CNTs, the uniform loading of Fe(3)O(4) sheath, and the structural retention of the composite anode on cycling. As Fe(3)O(4) is inexpensive and environmentally friendly, and the synthesis of Fe(3)O(4)-CNT is free of chemical wastes, this composite anode material holds considerable promise for high-performance lithium ion batteries.

Synthesis of ZnFe2O4/SiO2 composites derived from a diatomite template.

PubMed

Liu, Zhaoting; Fan, Tongxiang; Zhou, Han; Zhang, Di; Gong, Xiaolu; Guo, Qixin; Ogawa, Hiroshi

2007-03-01

A novel porous ZnFe2O4/SiO2 composite product has been generated with a template-directed assembly method from porous diatomite under different synthesis conditions, such as precursor concentrations (metallic nitrates), calcination temperature and diatomite type. The phase composition and morphology of all the materials were examined by x-ray diffraction (XRD), field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM). The results indicated that an inherited hierarchical porous structure from the diatomite template can be obtained, and the synthesis conditions were found to have clear effects on the formation of the ZnFe2O4/SiO2 composite. The ideal composite of ZnFe2O4/SiO2 can be obtained through optimization of diatomite template type, precursor solution and calcination temperature. Furthermore, the adsorption abilities of two types of diatomites were analyzed in detail using FTIR spectra and nitrogen adsorption measurements etc, which proved that A-diatomite (Shengzhou-diatomite) is better than B-diatomite (Changbai-diatomite) on the aspect of adsorbing Zn and Fe ions, and of forming the ZnFe2O4.

Synthesis, structure and magnetic properties of porous magnetic composite, based on MCM-41 molecular sieve with Fe{sub 3}O{sub 4} nanoparticles

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kolotilov, Sergey V.; Shvets, Oleksiy; Cador, Olivier

2006-08-15

Porous magnetic composites were prepared by the synthesis of molecular sieve MCM-41 in the presence of Fe{sub 3}O{sub 4} nanoparticles with average diameter of 15 nm. Nanoparticles were captured by porous silica matrix MCM-41, which resulted in their incorporation, as it was confirmed by TEM, SEM and X-ray diffraction. The materials possessed high surface area (392-666 m{sup 2} g{sup -1}), high pore volume (0.39-0.73 cm{sup 3} g{sup -1}) along with high magnetic response (M {sub S} up to 28.4 emu g{sup -1} at 300 K). Calcination of samples resulted in partial oxidation of Fe{sub 3}O{sub 4} to {alpha}-Fe{sub 2}O{sub 3}.more » The influence of nanoparticles content on sorption and magnetic properties of the composites was shown. No hysteresis was found for the samples at 300 K; at 5 K, H {sub C} was in the range 370-385 G for non-calcinated samples and 350-356 G for calcinated ones. - Graphical abstract: Schematic presentation of MCM-41/Fe{sub 3}O{sub 4} composite.« less

Nano-sized Fe2O3/Fe3O4 facilitate anaerobic transformation of hexavalent chromium in soil-water systems.

PubMed

Zhang, Yaxian; Li, Hua; Gong, Libo; Dong, Guowen; Shen, Liang; Wang, Yuanpeng; Li, Qingbiao

2017-07-01

The purpose of this study is to investigate the effects of nano-sized or submicro Fe 2 O 3 /Fe 3 O 4 on the bioreduction of hexavalent chromium (Cr(VI)) and to evaluate the effects of nano-sized Fe 2 O 3 /Fe 3 O 4 on the microbial communities from the anaerobic flooding soil. The results indicated that the net decreases upon Cr(VI) concentration from biotic soil samples amended with nano-sized Fe 2 O 3 (317.1±2.1mg/L) and Fe 3 O 4 (324.0±22.2mg/L) within 21days, which were approximately 2-fold of Cr(VI) concentration released from blank control assays (117.1±5.6mg/L). Furthermore, the results of denaturing gradient gel electrophoresis (DGGE) and high-throughput sequencing indicated a greater variety of microbes within the microbial community in amendments with nano-sized Fe 2 O 3 /Fe 3 O 4 than the control assays. Especially, Proteobacteria occupied a predominant status on the phylum level within the indigenous microbial communities from chromium-contaminated soils. Besides, some partial decrease of soluble Cr(VI) in abiotic nano-sized Fe 2 O 3 /Fe 3 O 4 amendments was responsible for the adsorption of nano-sized Fe 2 O 3 /Fe 3 O 4 to soluble Cr(VI). Hence, the presence of nano-sized Fe 2 O 3 /Fe 3 O 4 could largely facilitate the mobilization and biotransformation of Cr(VI) from flooding soils by adsorption and bio-mediated processes. Copyright © 2017. Published by Elsevier B.V.

Electromagnetic interference shielding and microwave absorption properties of cobalt ferrite CoFe2O4/polyaniline composite

NASA Astrophysics Data System (ADS)

Ismail, Mukhils M.; Rafeeq, Sewench N.; Sulaiman, Jameel M. A.; Mandal, Avinandan

2018-05-01

Improvement of microwave-absorbing materials (MAMs) is the most important research area in various applications, such as in communication, radiation medical exposure, electronic warfare, air defense, and different civilian applications. Conducting polymer, polyaniline doped with para toluene sulphonic acid (PANI-PTSA) as well as cobalt ferrite (CoFe2O4) is synthesized by sol-gel method and intensely blends in different ratios. The characterization of the composite materials, CoFe2O4/PANI-PTSA (CFP1, CFP2, CFP3 and CFP4), was performed by X-ray diffraction (XRD), atomic force microscopy (AFM) and vibrating sample magnetometry (VSM). The microwave-absorbing properties' reflection loss (dB) and important parameters, such as complex relative permittivity ( ɛ r '- jɛ r ″) and complex relative permeability ( µ r '- jµ r ″) were measured in different microwave frequencies in the X-band (8.2-12.4 GHz) region. The composite material CFP3 showed a wider absorption frequency range and maximum reflection loss of - 28.4 dB (99.8% power absorption) at 8.1 GHz and - 9.6 dB (> 90% power absorption) at 11.2 GHz, and so the composite can be used as a microwave absorber; however, it can be more suitable for application in daily life for making cell phones above 9 GHz. Also the results showed that the thicker composites like CFP3 (4 mm) exhibit obviously better EMI SE as compared with the thinner ones (0.19, 0.19, 0.3 mm); this may be related to the low transmission of the EM wave from the composites.

A Scalable Strategy To Develop Advanced Anode for Sodium-Ion Batteries: Commercial Fe3O4-Derived Fe3O4@FeS with Superior Full-Cell Performance.

PubMed

Hou, Bao-Hua; Wang, Ying-Ying; Guo, Jin-Zhi; Zhang, Yu; Ning, Qiu-Li; Yang, Yang; Li, Wen-Hao; Zhang, Jing-Ping; Wang, Xin-Long; Wu, Xing-Long

2018-01-31

A novel core-shell Fe 3 O 4 @FeS composed of Fe 3 O 4 core and FeS shell with the morphology of regular octahedra has been prepared via a facile and scalable strategy via employing commercial Fe 3 O 4 as the precursor. When used as anode material for sodium-ion batteries (SIBs), the prepared Fe 3 O 4 @FeS combines the merits of FeS and Fe 3 O 4 with high Na-storage capacity and superior cycling stability, respectively. The optimized Fe 3 O 4 @FeS electrode shows ultralong cycle life and outstanding rate capability. For instance, it remains a capacity retention of 90.8% with a reversible capacity of 169 mAh g -1 after 750 cycles at 0.2 A g -1 and 151 mAh g -1 at a high current density of 2 A g -1 , which is about 7.5 times in comparison to the Na-storage capacity of commercial Fe 3 O 4 . More importantly, the prepared Fe 3 O 4 @FeS also exhibits excellent full-cell performance. The assembled Fe 3 O 4 @FeS//Na 3 V 2 (PO 4 ) 2 O 2 F sodium-ion full battery gives a reversible capacity of 157 mAh g -1 after 50 cycles at 0.5 A g -1 with a capacity retention of 92.3% and the Coulombic efficiency of around 100%, demonstrating its applicability for sodium-ion full batteries as a promising anode. Furthermore, it is also disclosed that such superior electrochemical properties can be attributed to the pseudocapacitive behavior of FeS shell as demonstrated by the kinetics studies as well as the core-shell structure. In view of the large-scale availability of commercial precursor and ease of preparation, this study provide a scalable strategy to develop advanced anode materials for SIBs.

Preparation of Fe 3O 4/poly(styrene-butyl acrylate-[2-(methacryloxy)ethyl]trimethylammonium chloride) by emulsifier-free emulsion polymerization and its interaction with DNA

NASA Astrophysics Data System (ADS)

Li, Xiaolong; Liu, Guoqiang; Yan, Wei; Chu, Paul K.; Yeung, Kelvin W. K.; Wu, Shuilin; Yi, Changfeng; Xu, Zushun

2012-04-01

Cationic magnetic polymer particles Fe3O4/poly(styrene-butyl acrylate-[2-(methacryloxy)ethyl]trimethylammonium chloride), a type of potential gene carrier, were prepared by emulsifier-free emulsion polymerization with oleic acid modified magnetite Fe3O4, styrene, butyl acrylate and [2-(methacryloxy)ethyl]trimethylammonium chloride) (METAC). The morphology of the particles was characterized by transmission electron microscopy and the composites of particles were characterized by FT-IR spectroscopy, X-ray diffraction. These results showed that magnetic particles were well dispersed in polymers with the content of about 15%(wt/wt). The composites exhibited superparamagnetism and possessed a certain level of magnetic response. The interactions between the particles with calf-thymus DNA (ct DNA) were confirmed by zeta potential measurement, UV-vis spectroscopy and fluorescence spectroscopy. The DNA-binding capacity determined by the agarose gel electrophoresis showed good binding capacity of the emulsion to DNA. These results suggested the potential of the cationic magnetic polymer emulsion as gene target delivery carrier.

Composition dependence of spin transition in (Mg,Fe)SiO 3 bridgmanite

DOE PAGES

Dorfman, Susannah M.; Badro, James; Rueff, Jean -Pascal; ...

2015-10-01

Spin transitions in (Mg,Fe)SiO 3 bridgmanite have important implications for the chemistry and dynamics of Earth’s lower mantle, but have been complex to characterize in experiments. We examine the spin state of Fe in highly Fe-enriched bridgmanite synthesized from enstatites with measured compositions (Mg 0.61Fe 0.38Ca 0.01)SiO 3 and (Mg 0.25Fe 0.74Ca 0.01)SiO 3. Bridgmanite was synthesized at 78-88 GPa and 1800-2400 K and X-ray emission spectra were measured on decompression to 1 bar (both compositions) and compression to 126 GPa ((Mg 0.61Fe 0.38Ca 0.01)SiO 3 only) without additional laser heating. Observed spectra confirm that Fe in these bridgmanites ismore » dominantly high spin in the lower mantle. However, the total spin moment begins to decrease at ~50 GPa in the 74% FeSiO 3 composition. Lastly, these results support density functional theory predictions of a lower spin transition pressure in highly Fe-enriched bridgmanite and potentially explain the high solubility of FeSiO 3 in bridgmanite at pressures corresponding to Earth’s deep lower mantle.« less

Impact of Ti Incorporation on Hydroxylation and Wetting of Fe 3 O 4

DOE Office of Scientific and Technical Information (OSTI.GOV)

Stoerzinger, Kelsey A.; Pearce, Carolyn I.; Droubay, Timothy C.

2017-08-24

Understanding the interaction of water with compositionally tuned metal oxides is central to exploiting their unique catalytic and magnetic properties. However, processes such as hydroxylation, wetting, and resulting changes in electronic structure at ambient conditions are challenging to probe in situ. Here, we examine the hydroxylation and wetting of Fe(3-x)TixO4 epitaxial films directly using ambient pressure X-ray photoelectron spectroscopy under controlled relative humidity. Fe2+ formation promoted by Ti4+ substitution for Fe3+ increases with hydroxylation, commensurate with a decrease in the surface work function or change in the surface dipole. The incorporation of small amounts of Ti (x=0.25) as a bulkmore » dopant dramatically impacts hydroxylation, in part due to surface segregation, leading to coverages closer to that of TiO2 than Fe3O4. However, the Fe(3-x)TixO4 compositional series shows a similar affinity for water physisorption, which begins at notably lower relative humidity than on TiO2. The findings suggest that relative humidity rather than surface hydroxyl density controls wettability. Studies of this kind directly relate to rational design of doped magnetite into more active catalysts for UV/Fenton degradation, the adsorption of contaminants, and the development of spin filters.« less

Fe3O4–Silicone Mixture as Flexible Actuator

PubMed Central

Song, Kahye

2018-01-01

In this study, we introduce Fe3O4-silicone flexible composite actuators fabricated by combining silicone and iron oxide particles. The actuators exploit the flexibility of silicone and the electric conductivity of iron oxide particles. These actuators are activated by electrostatic force using the properties of the metal particles. Herein, we investigate the characteristic changes in actuation performance by increasing the concentration of iron oxide from 1% to 20%. The developed flexible actuators exhibit a resonant frequency near 3 Hz and their actuation amplitudes increase with increasing input voltage. We found that the actuator can move well at metal particle concentrations >2.5%. We also studied the changes in actuation behavior, depending on the portion of the Fe3O4-silicone in the length. Overall, we experimentally analyzed the characteristics of the newly proposed metal particle-silicone composite actuators. PMID:29738466

High Performance Lithium-Ion Hybrid Capacitors Employing Fe3O4-Graphene Composite Anode and Activated Carbon Cathode.

PubMed

Zhang, Shijia; Li, Chen; Zhang, Xiong; Sun, Xianzhong; Wang, Kai; Ma, Yanwei

2017-05-24

Lithium-ion capacitors (LICs) are considered as promising energy storage devices to realize excellent electrochemical performance, with high energy-power output. In this work, we employed a simple method to synthesize a composite electrode material consisting of Fe 3 O 4 nanocrystallites mechanically anchored among the layers of three-dimensional arrays of graphene (Fe 3 O 4 -G), which exhibits several advantages compared with other traditional electrode materials, such as high Li storage capacity (820 mAh g -1 at 0.1 A g -1 ), high electrical conductivity, and improved electrochemical stability. Furthermore, on the basis of the appropriated charge balance between cathode and anode, we successfully fabricated Fe 3 O 4 -G//activated carbon (AC) soft-packaging LICs with a high energy density of 120.0 Wh kg -1 , an outstanding power density of 45.4 kW kg -1 (achieved at 60.5 Wh kg -1 ), and an excellent capacity retention of up to 94.1% after 1000 cycles and 81.4% after 10 000 cycles. The energy density of the Fe 3 O 4 -G//AC hybrid device is comparable with Ni-metal hydride batteries, and its capacitive power capability and cycle life is on par with supercapacitors (SCs). Therefore, this lithium-ion hybrid capacitor is expected to bridge the gap between Li-ion battery and SCs and gain bright prospects in next-generation energy storage fields.

Epoxy composites coating with Fe3O4 decorated graphene oxide: Modified bio-inspired surface chemistry, synergistic effect and improved anti-corrosion performance

NASA Astrophysics Data System (ADS)

Zhan, Yingqing; Zhang, Jieming; Wan, Xinyi; Long, Zhihang; He, Shuangjiang; He, Yi

2018-04-01

To obtain graphene or graphene derivatives based epoxy composite coatings with high anti-corrosion performance, the morphology of nanostructures, dispersion, and interfacial adhesion are key factors that need to be considered. We here demonstrated the bio-inspired co-modification of graphene oxide/Fe3O4 hybrid (GO-Fe3O4@ poly (DA+KH550)) and its synergistic effect on the anti-corrosion performance of epoxy coating. For this purpose, graphene oxide/Fe3O4 hybrid obtained from hydrothermal route was modified by self-polymerization between dopamine and secondary functional monomer (KH550), which led to the modified bio-inspired surface functionalization. This novel modified bio-inspired functionalization was quite distinct from conventional surface modification or decoration. Namely, abundant amino groups were introduced by modified bio-inspired functionalization, which allowed the graphene oxide/Fe3O4 hybrid to disperse well in epoxy resin and enhanced the interfacial adhesion between modified nanofiller and epoxy resin through chemical crosslinking reaction. The electrochemical impedance spectroscopy (EIS) test revealed that anti-corrosive performance of epoxy coatings was significantly enhanced by addition of 0.5 wt% modified bio-inspired functionalized GO-Fe3O4 hybrid compared with neat epoxy and other nanofillers/epoxy composite coatings. Moreover, the micro-hardness of epoxy coating was enhanced by 71.8% compared with pure epoxy coating at the same loading content. In addition, the anticorrosion mechanism of GO-Fe3O4@poly (DA+KH550) was tentatively discussed.

Fabrication and Electromagnetic Properties of Conjugated NH2-CuPc@Fe3O4

NASA Astrophysics Data System (ADS)

Yan, Liang; Pu, Zejun; Xu, Mingzhen; Wei, Renbo; Liu, Xiaobo

2017-10-01

Conjugated amino-phthalocyanine copper containing carboxyl groups/magnetite (NH2-CuPc@Fe3O4) has been fabricated from FeCl3·6H2O and NH2-CuPc via a simple solvothermal method and its electromagnetic properties investigated. Scanning electron microscopy and transmission electron microscopy revealed that the NH2-CuPc@Fe3O4 was a waxberry-like nanomaterial with NH2-CuPc molecules effectively embedded in the interior of Fe3O4 particles in the form of beads. Introduction of NH2-CuPc effectively improved the complementarity between the dielectric and magnetic losses of the system, resulting in excellent electromagnetic performance. The minimum reflection loss of the as-prepared composite reached -33.4 dB at 7.0 GHz for coating layer thickness of 4.0 mm and bandwidth below -10.0 dB (90% absorption) of up to 3.8 GHz. These results indicate that introduction of NH2-CuPc results in a composite with potential for use as an electromagnetic microwave absorption material.

Synergistic operation of photocatalytic degradation and Fenton process by magnetic Fe3O4 loaded TiO2

NASA Astrophysics Data System (ADS)

Sun, Qiong; Hong, Yong; Liu, Qiuhong; Dong, Lifeng

2018-02-01

The magnetic Fe3O4 loaded anatase TiO2 photocatalysts with different mass ratios were successfully synthesized by a one-step convenient calcining method. The morphology and structure analysis revealed that Fe3O4 was formed in TiO2 with very fine-grained particles. After a small amount of Fe3O4 loaded onto TiO2, the photocatalytic property enhanced obviously for the degradation of organic dye. Furthermore, the photo-Fenton-like catalysis of the iron-containing samples could also be induced after the addition of hydrogen peroxide. The apparent kinetic constant of the reaction that catalyzed by Fe-TiO2 was about 5.3 and 8.3 times of that catalyzed by TiO2 or Fe3O4 only, respectively, proving an effective synergistic contribution of the photocatalysis and Fenton reaction in the composite. Compared with Fe3O4 or free Fe3+ ions, only 13% of iron in TiO2 dissolved into acidic solution (25% for Fe3O4 and 100% for Fe3+) after the reaction, which confirmed the iron had been well immobilized onto TiO2. In addition, the extremely stable photocatalytic activity in cycling experiments proved the immobilized iron had been tightly attached onto TiO2, indicating the great potential of the catalyst for practical applications.

Tailoring the nickel nanoparticles anchored on the surface of Fe3O4@SiO2 spheres for nanocatalysis.

PubMed

Ding, Lei; Zhang, Min; Zhang, Yanwei; Yang, Jinbo; Zheng, Jing; Hayat, Tasawar; Alharbi, Njud S; Xu, Jingli

2017-08-25

Herein, we report an efficient and universal strategy for synthesizing a unique triple-shell structured Fe 3 O 4 @SiO 2 @C-Ni hybrid composite. Firstly, the Fe 3 O 4 cores were synthesized by hydrothermal reaction, and sequentially coated with SiO 2 and a thin layer of nickel-ion-doped resin-formaldehyde (RF-Ni 2+ ) using an extended Stöber method. This was followed by carbonization to produce the Fe 3 O 4 @SiO 2 @C-Ni nanocomposites with metallic nickel nanoparticles embedded in an RF-derived thin graphic carbon layer. Interestingly, the thin SiO 2 spacer layer between RF-Ni 2+ and Fe 3 O 4 plays a critical role on adjusting the size and density of the nickel nanoparticles on the surface of Fe 3 O 4 @SiO 2 nanospheres. The detailed tailoring mechanism is explicitly discussed, and it is shown that the iron oxide core can react with the nickel nanoparticles without the SiO 2 spacer layer, and the size and density of the nickel nanoparticles can be effectively controlled when the SiO 2 layer exits. The multifunctional composites exhibit a significantly enhanced catalytic performance in the reduction of 4-nitrophenol (4-NP).

Fabricate BC/Fe3O4@PPy 3D nanofiber film as flexible electrode for supercapacitor application

NASA Astrophysics Data System (ADS)

Lv, Xvdan; Li, Guohui; Pang, Zengyuan; Li, Dawei; Lei, Luo; Lv, Pengfei; Mushtaq, Muhammad; Wei, Qufu

2018-05-01

For flexible film supercapacitor, high areal capacitance is a main evaluating indicator. In this paper, bacterial cellulose (BC) with special three-dimensional structure was used as the natural flexible base material. Fe3O4 nanoparticles with average diameter of 20 nm were synthesized on the surface of BC fibers. The conductive path polypyrrole (PPy) was introduced as shell of BC/Fe3O4 fibers to further improve the pseudo capacitance in 1 mol/L H2SO4 solution. Besides, the BC/Fe3O4@PPy was used for supercapacitor application in acid electrolyte, and delivered higher areal capacitance compared to other Fe3O4 composites in previous reports. The obtained BC/Fe3O4@PPy film showed excellent mechanical strength (tensile strength reached 11 MPa), high areal specific capacitance (5.4 F cm-2 at active mass of 8.4 mg cm-2), and long cycle life (1.95 F cm-2 over 3500 cycles).

Dielectric and phonon spectroscopy of Nb-doped Pb(Zr1-yTiy)O3-CoFe2O4 composites

NASA Astrophysics Data System (ADS)

Sakanas, Aurimas; Nuzhnyy, Dmitry; Grigalaitis, Robertas; Banys, Juras; Borodavka, Fedir; Kamba, Stanislav; Ciomaga, Cristina Elena; Mitoseriu, Liliana

2017-06-01

Broad-band dielectric and phonon response of Nb-doped (1-x)Pb(Zr1-yTiy)O3-xCoFe2O4 composites with x = 10%-30% was investigated between 0.1 MHz and 100 THz. At room temperature, a broad distribution of relaxation times causes a constant dielectric loss below 1 GHz. Above room temperature, a strong Maxwell-Wagner relaxation process dominates below 1 GHz due to the conductivity of CoFe2O4 (CF). Two additional relaxation processes are seen between 1 GHz and 1 THz. The lower-frequency one, coming from domain wall motion, disappears above TC ≈ 650 K. The higher-frequency component slows down on heating towards TC, because it is the central mode, which drives the ferroelectric phase transition. Time-domain THz transmission and infrared reflectivity spectra reveal a mixture of polar phonons from both ferroelectric Nb-doped Pb(Zr,Ti)O3 (PZTN) and magnetic CoFe2O4 (CF) components, while the micro-Raman scattering spectra allow to study phonons from both components separately. Similar temperature behavior of phonons as in the pure PZTN and CF was observed. While in CoFe2O4 the Raman-active phonons gradually reduce their intensities on heating due to increasing conductivity and related reduced Raman-scattering volume, some phonons in PZTN disappear above TC due to change of selection rules in the paraelectric phase. Like in the pure Pb(Zr,Ti)O3, the soft phonon and central modes were also observed.

Facile preparation of magnetic mesoporous MnFe2O4@SiO2-CTAB composites for Cr(VI) adsorption and reduction.

PubMed

Li, Na; Fu, Fenglian; Lu, Jianwei; Ding, Zecong; Tang, Bing; Pang, Jiabin

2017-01-01

Chromium-contaminated water is regarded as one of the biggest threats to human health. In this study, a novel magnetic mesoporous MnFe 2 O 4 @SiO 2 -CTAB composite was prepared by a facile one-step modification method and applied to remove Cr(VI). X-ray diffraction, scanning electron microscopy, transmission electron microscopy, specific surface area, and vibrating sample magnetometer were used to characterize MnFe 2 O 4 @SiO 2 -CTAB composites. The morphology analysis showed that the composites displayed a core-shell structure. The outer shell was mesoporous silica with CTAB and the core was MnFe 2 O 4 nanoparticles, which ensured the easy separation by an external magnetic field. The performance of MnFe 2 O 4 @SiO 2 -CTAB composites in Cr(VI) removal was far better than that of bare MnFe 2 O 4 nanoparticles. There were two reasons for the effective removal of Cr(VI) by MnFe 2 O 4 @SiO 2 -CTAB composites: (1) mesoporous silica shell with abundant CTA + significantly enhanced the Cr(VI) adsorption capacity of the composites; (2) a portion of Cr(VI) was reduced to less toxic Cr(III) by MnFe 2 O 4 , followed by Cr(III) immobilized on MnFe 2 O 4 @SiO 2 -CTAB composites, which had been demonstrated by X-ray photoelectron spectroscopy results. The adsorption of Cr(VI) onto MnFe 2 O 4 @SiO 2 -CTAB followed the Freundlich isotherm model and pseudo-second-order model. Tests on the regeneration and reuse of the composites were performed. The removal efficiency of Cr(VI) still retained 92.4% in the sixth cycle. MnFe 2 O 4 @SiO 2 -CTAB composites exhibited a great potential for the removal of Cr(VI) from water. Copyright © 2016 Elsevier Ltd. All rights reserved.

Giant flexoelectricity in Ba0.6Sr0.4TiO3/Ni0.8Zn0.2Fe2O4 composite

NASA Astrophysics Data System (ADS)

Li, Yong; Shu, Longlong; Huang, Wenbin; Jiang, Xiaoning; Wang, Hong

2014-10-01

Enhanced flexoelectricity in perovskite ceramics and single crystals has been reported before. In this letter, 3-3 ceramic-ceramic Ba0.6Sr0.4TiO3/Ni0.8Zn0.2Fe2O4 composite with a colossal permittivity was employed in the conventional pure bending experiment in order to examine the transverse flexoelectric response. The measured flexoelectric coefficient at 30 Hz is 128 μC/m and varies to 16 μC/m with the frequency increasing from 30 Hz to 120 Hz, mainly due to the inverse correlation between the permittivity and the frequency. This result reveals the permittivity dependence of flexoelectric coefficient in the frequency dispersion materials, suggesting that the giant permittivity composites can be good flexoelectric materials.

Fabrication of Fe3O4@CuO core-shell from MOF based materials and its antibacterial activity

NASA Astrophysics Data System (ADS)

Rajabi, S. K.; Sohrabnezhad, Sh.; Ghafourian, S.

2016-12-01

Magnetic Fe3O4@CuO nanocomposite with a core/shell structure was successfully synthesized via direct calcinations of magnetic Fe3O4@HKUST-1 in air atmosphere. The morphology, structure, magnetic and porous properties of the as-synthesized nano composites were characterized by using scanning electron microscope (SEM), transmission electron microscopy (TEM), powder X-ray diffraction (PXRD), and vibration sample magnetometer (VSM). The results showed that the nanocomposite material included a Fe3O4 core and a CuO shell. The Fe3O4@CuO core-shell can be separated easily from the medium by a small magnet. The antibacterial activity of Fe3O4-CuO core-shell was investigated against gram-positive and gram-negative bacteria. A new mechanism was proposed for inactivation of bacteria over the prepared sample. It was demonstrated that the core-shell exhibit recyclable antibacterial activity, acting as an ideal long-acting antibacterial agent.

Enhanced magnetization in morphologically and magnetically distinct BiFeO3 and La0.7Sr0.3MnO3 composites

NASA Astrophysics Data System (ADS)

Pillai, Shreeja; Reshi, Hilal Ahmad; Bagwaiya, Toshi; Banerjee, Alok; Shelke, Vilas

2017-09-01

Nanomaterials exhibit properties different from those of their bulk counterparts. The modified magnetic characteristics of manganite nanoparticles were exploited to improve magnetization in multiferroic BiFeO3 compound. We studied the composite of two morphologically and magnetically distinct compounds BiFeO3 (BFO) and La0.7Sr0.3MnO3 (LSMO). The microcrystalline BiFeO3 sample was prepared by solid state reaction method and the nanocrystalline La0.7Sr0.3MnO3 by sol-gel method. Composites with nominal compositions (1-x)BiFeO3-(x)La0.7Sr0.3MnO3 were prepared by modified solid state reaction method. The phase purity and crystal structures were checked by using X-ray diffraction. The formation of composites with phase separated BFO and LSMO was confirmed using Raman and Fourier Transform Infrared spectroscopy studies. The composite samples showed relatively high value of magnetization with finite coercivity. This improvement in magnetic behavior is ascribed to the coexistence of multiple magnetic orderings in composite samples. We scrutinized the possibility of oxygen vacancy or Fe mixed valency formation in the samples using X-ray photoelectron spectroscopy technique.

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

NASA Astrophysics Data System (ADS)

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

2017-06-01

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.

Polyethylenimine functionalized Fe3O4/steam-exploded rice straw composite as an efficient adsorbent for Cr(VI) removal

NASA Astrophysics Data System (ADS)

Zhang, Shengli; Wang, Zhikai; Chen, Haoyu; Kai, Chengcheng; Jiang, Man; Wang, Qun; Zhou, Zuowan

2018-05-01

Polyethyleneimine functionalized Fe3O4/steam-exploded rice straw composite (Fe3O4-PEI-SERS), which combines magnetic separation with adsorption of PEI functionalized biosorbent, was successfully prepared via a simple glutaraldehyde crosslinking method. Its adsorption potential for the removal of Cr(VI) was systematically studied in batch mode. Results showed that Cr(VI) adsorption on Fe3O4-PEI-SESERS was highly pH-dependent, and the optimum pH was 2.0. The time to reach equilibrium was related to initial Cr(VI) concentration and was 1 and 6 h for 200 and 300 mg/L of Cr(VI), respectively. The adsorption system followed pseudo-second-order kinetic model and Langmuir isotherm. Its maximum adsorption capacity was 280.11, 317.46 and 338.98 mg/g at 25, 35 and 45 °C, respectively. The competitive uptake from coexisting ions (K+, Na+, Cu2+, Cl- and NO3-) was insignificant except SO42-. After six adsorption/desorption cycles, the adsorbent retained good adsorption capacity. The Cr(VI) removal involved its partial reduction into Cr(III). Due to the properties of high adsorption capacity, strong magnetic responsiveness, good reusability and Cr(VI) detoxification, the Fe3O4-PEI-SESERS has a potential application in Cr(VI) removal from wastewater.

Preparation of carbon coated Fe3O4 nanoparticles for magnetic separation of uranium

NASA Astrophysics Data System (ADS)

Zhang, Xiaofei; Wang, Jun

2018-01-01

Uranium(VI) was removed from aqueous solutions using carbon coated Fe3O4 nanoparticles (Fe3O4@C). Batch experiments were conducted to study the effects of initial pH, shaking time and temperature on uranium sorption efficiency. It was found that the maximum adsorption capacity of the Fe3O4@C toward uranium(VI) was ∼120.20 mg g-1 when the initial uranium(VI) concentration was 100 mg L-1, displaying a high efficiency for the removal of uranium(VI) ions. Kinetics of the uranium(VI) removal is found to follow pseudo-second-order rate equation. In addition, the uranium(VI)-loaded Fe3O4@C nanoparticles can be recovered easily from aqueous solution by magnetic separation and regenerated by acid treatment. Present study suggested that magnetic Fe3O4@C composite particles can be used as an effective and recyclable adsorbent for the removal of uranium(VI) from aqueous solutions.

Fabrication, characterization, and photocatalytic property of α-Fe2O3/graphene oxide composite

NASA Astrophysics Data System (ADS)

Li, Hong; Zhao, Qidong; Li, Xinyong; Zhu, Zhengru; Tade, Moses; Liu, Shaomin

2013-06-01

Spindle-shaped microstructure of α-Fe2O3 was successfully synthesized by a simple hydrothermal method. The α-Fe2O3/graphene oxide (GO) composites was prepared using a modified Hummers' strategy. The properties of the samples were systematically investigated by X-ray powder diffraction (XRD), UV-Vis diffuse reflectance spectrophotometer, transmission electron microscope, atomic force microscope, X-ray photoelectron spectroscopy, and Raman spectroscopy (Raman) techniques. GO nanosheets act as supporting materials for anchoring the α-Fe2O3 particles. The average crystallite sizes of the α-Fe2O3 and α-Fe2O3/GO samples are ca. 27 and 24 nm, respectively. The possible growth of α-Fe2O3 onto GO layers led to a higher absorbance capacity for visible light by α-Fe2O3/GO than α-Fe2O3 composite. The photocatalytic degradation of toluene over the α-Fe2O3 and α-Fe2O3/GO samples under xenon-lamp irradiation was comparatively studied by in situ FTIR technique. The results indicate that the α-Fe2O3/GO sample synthesized exhibited a higher capacity for the degradation of toluene. The composite of α-Fe2O3/GO could be promisingly applied in photo-driven air purification.

The dynamic magnetoviscoelastic properties of biomineralized (Fe3O4) PVP-CMC hydrogel

NASA Astrophysics Data System (ADS)

Ray, Ayan; Saha, Nabanita; Saha, Petr

2017-05-01

The Polyvinylpyrrolidone (PVP) and carboxymethylcellulose (CMC) based polymer matrix was used as a template for the preparation of magnetic hydrogel. This freshly prepared PVP-CMC hydrogel template was successfully mineralized by in situ synthesis of magnetic nanoparticles (Fe3O4) via chemical co-precipitation reaction using liquid diffusion method. The present study emphasizes on the rheological behavior of non-mineralized and mineralized PVP-CMC hydrogels. Scanning Electron Microscopy (SEM), transmission electron microscopy (TEM), X-ray Diffraction (XRD) pattern, Fourier transform infrared spectroscopy (FT-TR), Vibrating sample magnetometer (VSM) and dynamic magneto rheometer were used to study the morphological, physical, chemical and magnetic properties of nanoparticle (Fe3O4) filled PVP-CMC hydrogel respectively in order to monitor how Fe3O4 magnetic nanoparticles affects the mechanical properties of the hydrogel network. The storage (G') and loss (G") moduli with a complex viscosity of the system was measured using a parallel plate rheometer. Frequency and amplitude sweep with temperature variation was performed to determine the frequency and amplitude dependent magneto viscoelastic moduli for both hydrogel samples. A strong shear thinning effect was observed in both (non-mineralized and mineralized) PVP-CMC hydrogels, which confirm that Fe3O4 filled magnetic hydrogels, are pseudoplastic in nature. This Fe3O4 filled PVP-CMC hydrogel can be considered as stimuli-responsive soft matter that may be used as an actuator in medical devices.

Development of Fe3O4/ZrO2 Composite Powered by Nanographene Platelets (NGP) for Degradation of Water Pollutants via Photo- and Sonocatalysis

NASA Astrophysics Data System (ADS)

Kristianto, Yogi; Taufik, Ardiansyah; Saleh, Rosari

2017-03-01

In this study, a series of Fe3O4/ZrO2/nanographene platelets (NGP) composite, with various weight percent (wt%) of NGP (5%, 10% and 15%), were prepared successfully using ultrasonic-assisted followed by simple hydrothermal method. Their physicochemical properties were fairly characterized by X-ray diffraction, fourier transform infrared and thermal gravimetric analysis. Furthermore, their catalytic activities were investigated toward anionic congo red (CR) and cationic methylene blue (MB) as models of organic pollutant under ultraviolet (UV) and ultrasonic (US) irradiation, respectively. The experimental results showed that the incorporation of NGP in Fe3O4/ZrO2 composite improved its efficiency in degrading CR and MB and became maximum at 10wt% of NGP. In addition, the role of active radicals involved in catalytic activities were discussed.

A Polycarboxyl-Decorated FeIII -Based Xerogel-Derived Multifunctional Composite (Fe3 O4 /Fe/C) as an Efficient Electrode Material towards Oxygen Reduction Reaction and Supercapacitor Application.

PubMed

Devi, Bandhana; Venkateswarulu, Mangili; Kushwaha, Himmat Singh; Halder, Aditi; Koner, Rik Rani

2018-05-02

Low cost, non-noble metal catalysts with a good oxygen reduction reaction (ORR) activity comparable to that of platinum and also having good energy storage properties are highly desirable but challenging. Several challenges are associated with the development of such materials. Herein, we demonstrate a new polycarboxyl-functionalised Fe III -based gel material, synthesised following a solvothermal method and the development of its composite (Fe 3 O 4 /Fe/C) by annealing at optimised temperature. The developed composite displayed excellent electrocatalytic activity for the oxygen reduction reaction with an onset potential of 0.87 V (vs. RHE) and a current density value of -5 mA cm -2 , which are comparable with commercial 20 wt % Pt/C. In addition, as one of the most desirable properties, the composite exhibits a better methanol tolerance and greater durability than Pt/C. The same material was explored as an energy storage material for supercapacitors, which showed a specific capacitance of 245 F g -1 at a current density of 1 A g -1 . It is expected that this Fe 3 O 4 /Fe/C composite with a disordered graphitised carbon matrix will pave a horizon for developing energy conversion and energy storage devices. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Synthesis, Characterization, and Study of In Vitro Cytotoxicity of ZnO-Fe3O4 Magnetic Composite Nanoparticles in Human Breast Cancer Cell Line (MDA-MB-231) and Mouse Fibroblast (NIH 3T3).

PubMed

Bisht, Gunjan; Rayamajhi, Sagar; Kc, Biplab; Paudel, Siddhi Nath; Karna, Deepak; Shrestha, Bhupal G

2016-12-01

Novel magnetic composite nanoparticles (MCPs) were successfully synthesized by ex situ conjugation of synthesized ZnO nanoparticles (ZnO NPs) and Fe 3 O 4 NPs using trisodium citrate as linker with an aim to retain key properties of both NPs viz. inherent selectivity towards cancerous cell and superparamagnetic nature, respectively, on a single system. Successful characterization of synthesized nanoparticles was done by XRD, TEM, FTIR, and VSM analyses. VSM analysis showed similar magnetic profile of thus obtained MCPs as that of naked Fe 3 O 4 NPs with reduction in saturation magnetization to 16.63 emu/g. Also, cell viability inferred from MTT assay showed that MCPs have no significant toxicity towards noncancerous NIH 3T3 cells but impart significant toxicity at similar concentration to breast cancer cell MDA-MB-231. The EC50 value of MCPs on MDA-MB-231 is less than that of naked ZnO NPs on MDA-MB-231, but its toxicity on NIH 3T3 was significantly reduced compared to ZnO NPs. Our hypothesis for this prominent difference in cytotoxicity imparted by MCPs is the synergy of selective cytotoxicity of ZnO nanoparticles via reactive oxygen species (ROS) and exhausting scavenging activity of cancerous cells, which further enhance the cytotoxicity of Fe 3 O 4 NPs on cancer cells. This dramatic difference in cytotoxicity shown by the conjugation of magnetic Fe 3 O 4 NPs with ZnO NPs should be further studied that might hold great promise for the development of selective and site-specific nanoparticles. Schematic representation of the conjugation, characterization and cytotoxicity analysis of Fe 3 O 4 -ZnO magnetic composite particles (MCPs).

New Polymorph of Fe3O4 Stable at Core-Mantle Boundary Conditions

NASA Astrophysics Data System (ADS)

Greenberg, E.; Prakapenka, V. B.

2017-12-01

Magnetite Fe3O4 (and its high-pressure polymorphs) is one of the most studied iron bearing minerals. One reason for the interest in magnetite is that it contains both Fe2+ and Fe3+, which is especially important for understanding the physical and chemical properties of Earth's deep interior. Early studies on magnetite debated the nature of the structural phase transition at 35 GPa [1-4]. This high-pressure structure was shown to be of the CaTi2O4-type [5], but with Fe3+ occupying multiple sites. Furthermore, at pressures above 65 GPa a second structural transition to a Pmma space group was shown to take place [5], similar to that in Fe3-xTixO4 solid solution [6]. Other studies have focused on the P-T stability of Fe3O4. Early studies by Lazor et al. [7] predicted that Fe3O4 might disproportionate into FeO and h-Fe2O3 at 50 GPa. Other studies suggested that the high-pressure phase should be stable up to 100 GPa [3]. A more recent experimental study by Ricolleau and Fei [8] revealed that Fe3O4 is stable at least up to 103 GPa. Thus far, structural studies of Fe3O4 have been limited to pressures below 105 GPa. We have studied Fe3O4 up to pressures of 175 GPa and temperatures above 4000K, using diamond anvil cells in combination with synchrotron x-ray diffraction and an online pulsed laser-heating system to study the stability of Fe3O4 at relevant pressure-temperature conditions. Our results show that Fe3O4 is stable up to at least 176 GPa and 4200 K. We have discovered a new polymorph of Fe3O4 at these high P-T conditions. This new phase is stable in the pressure range of at least 100Fe3O4, EOS, structure and its properties across lower mantle - core conditions will be discussed in terms of impact on composition and evolution of Earth's deep interior. [1] Fei et al. American Mineralogist 84, 203 (1999). [2] Haavik et al. American Mineralogist 85, 514 (2000). [3] Dubrovinsky et al. Journal of

Controllable construction of flower-like FeS/Fe2O3 composite for lithium storage

NASA Astrophysics Data System (ADS)

Wang, Jie; He, Huan; Wu, Zexing; Liang, Jianing; Han, Lili; Xin, Huolin L.; Guo, Xuyun; Zhu, Ye; Wang, Deli

2018-07-01

Transitions metal sulfides/oxides have been considered as promising anode candidates for next generation lithium-ion batteries (LIBs) due to high theoretical capacities. However, the large volume change during lithiation/delithiation process and poor electronic conductivity often result in a poor charging/discharging performance. Herein, we design a flower-like FeS/Fe2O3 composite via a simple "solvothermal-oxidation" method, in which the Fe2O3 is most distributed on the surface of the flower. The unique porous structure and synergistic effect between FeS and Fe2O3 not only accommodate the large volume expansion, but also facilitate Li ion and electron transport. The Fe2O3 shell effectively reduce the dissolution of Li2Sx during discharge/charge process. When serving as the anode material in lithium ion battery, FeS/Fe2O3 exhibits superior specific capacity, rate capacity and cycling stability compared with pure FeS and Fe2O3.

Monodisperse magnetite (Fe3O4) nanoparticles modified with water soluble polymers for the diagnosis of breast cancer by MRI method

NASA Astrophysics Data System (ADS)

Rezayan, Ali Hossein; Mousavi, Majid; Kheirjou, Somayyeh; Amoabediny, Ghasem; Ardestani, Mehdi Shafiee; Mohammadnejad, Javad

2016-12-01

In this study, magnetic nanoparticles (MNPs) were synthesized via co-precipitation method. To enhance the biocompatibility and colloidal stability of the synthesized nanoparticles, they were modified with carboxyl functionalized PEG via dopamine (DPA) linker. Both modified and unmodified Fe3O4 nanoparticles exhibited super paramagnetic behavior (particle size below 20 nm). The saturation magnetization (Ms) of PEGdiacid-modified Fe3O4 was 45 emu/g, which was less than the unmodified Fe3O4 nanoparticles (70 emu/g). This difference indicated that PEGdiacid polymer was immobilized on the surface of Fe3O4 nanoparticles successfully. To evaluate the efficiency of the resulting nanoparticles as contrast agents for magnetic resonance imaging (MRI), different concentration of MNPs and different value of echo time TE were investigated. The results showed that by increasing the concentration of the nanoparticles, transverse relaxation time (T2) decreased, which subsequently resulted in MR signal enhancement. T2-weighted MR images of the different concentration of MNPs in different value of echo time TE indicated that MR signal intensity increased with increase in TE value up to 66 and then remained constant. The cytotoxicity effect of the modified and unmodified nanoparticles was evaluated in three different concentrations (12, 60 and 312 mg l-1) on MDA-MB-231 cancer cells for 24 and 48 h. In both tested time (24 and 48 h) for all three samples, the modified nanoparticles had long life time than unmodified nanoparticles. Cellular uptake of modified MNPs was 80% and reduced to 9% by the unmodified MNPs.

Magnetoelectric coupling in multiferroic BaTiO3-CoFe2O4 composite nanofibers via electrospinning

NASA Astrophysics Data System (ADS)

Fu, Bi; Lu, Ruie; Gao, Kun; Yang, Yaodong; Wang, Yaping

2015-07-01

Magnetoelectric (ME) coupling in Pb-based multiferroic composites has been widely investigated due to the excellent piezoelectric property of lead zirconate titanate (PZT). In this letter, we report a strategy to create a hybrid Pb-free ferroelectric and ferromagnetic material and detect its ME coupling at the nanoscale. Hybrid Pb-free multiferroic BaTiO3-CoFe2O4 (BTO-CFO) composite nanofibers (NFs) were generated by sol-gel electrospinning. The perovskite structure of BTO and the spinel structure of CFO nanograins were homogenously distributed in the composite NFs and verified by bright-field transmission electron microscopy observations along the perovskite [111] zone axis. Multiferroicity was confirmed by amplitude-voltage butterfly curves and magnetic hysteresis loops. ME coupling was observed in terms of a singularity on a dM/dT curve at the ferroelectric Curie temperature (TC) of BaTiO3. The lateral ME coefficient was investigated by the evolution of the piezoresponse under an external magnetic field of 1000 Oe and was estimated to be α31 =0.78× 104 \\text{mV cm}-1 \\text{Oe}-1 . These findings could enable the creation of nanoscale Pb-free multiferroic composite devices.

Magnetization-induced enhancement of photoluminescence in core-shell CoFe{sub 2}O{sub 4}@YVO{sub 4}:Eu{sup 3+} composite

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jia, Yanmin, E-mail: ymjia@zjnu.edu.cn, E-mail: wuzheng@zjnu.cn; Zhou, Zhihua; Wei, Yongbin

2013-12-07

After the core-shell CoFe{sub 2}O{sub 4}@YVO{sub 4}:Eu{sup 3+} composite synthesized through a facile sol-gel method was magnetized under an external magnetic field of 0.25 T for 4 h, an enhancement of ∼56% in photoluminescence intensity was observed. The remanent magnetization of the CoFe{sub 2}O{sub 4} core increases the intensity of the excited charge transfer transition of VO{sub 4}{sup 3−} group in YVO{sub 4}:Eu{sup 3+} shell, which may enhance the probability related to the Eu{sup 3+} radiative transition {sup 5}D{sub 0}-{sup 7}F{sub 2}, yielding to a high photoluminescence. The obvious remanent-magnetization-induced enhancement in photoluminescence is helpful in developing excellent magnetic/luminescent material for themore » practical display devices.« less

Preparation and characterization of chain-like and peanut-like Fe3O4@SiO2 core-shell structure.

PubMed

Shi, Haowei; Huang, Yan; Cheng, Chao; Ji, Guoyuan; Yang, Yuxiang; Yuan, Hongming

2013-10-01

The size- and shape-controlled Fe3O4@SiO2 nanocomposites were successfully synthesized via the sol-gel method. The results showed that the size, shape, and property of the products were directly influenced by the amount of TEOS, and the concentration of water-based magnetic fluid in the coating process. The morphology and properties of the products were characterized by TEM, SEM, X-ray powder diffraction, IR and EDS. The Fe3O4@SiO2 composites with easily-controlled size arranged from 58 to 835 nm could be synthesized by adjusting the experimental parameters. When TEOS amount is 1 mL and the concentration of magnetic fluid were 30.0 and 10.0 mg/mL respectively, chain-like and peanuts-like well-dispersed Fe3O4@SiO2 particles with clear core-shell structure were obtained. These size- and shape-controlled Fe3O4@SiO2 composites may have potential application in the field of targeted drug delivery and MRI contrast agent.

Monodisperse Fe3O4 and γ-Fe2O3 magnetic mesoporous microspheres as anode materials for lithium-ion batteries.

PubMed

Xu, Jing-San; Zhu, Ying-Jie

2012-09-26

Monodisperse Fe(3)O(4) and γ-Fe(2)O(3) magnetic mesoporous microspheres are prepared via a surfactant-free solvothermal combined with precursor thermal transformation method. The as-prepared Fe(3)O(4) and γ-Fe(2)O(3) magnetic mesoporous microspheres have a relatively high specific surface area of 122.3 and 138.6 m(2)/g, respectively. The Fe(3)O(4) and γ-Fe(2)O(3) magnetic mesoporous microspheres are explored as the anode materials for lithium-ion batteries, and they have a high initial discharge capacity of 1307 and 1453 mA h/g, respectively, and a good reversible performance (450 mA h/g for Fe(3)O(4) and 697 mA h/g for γ-Fe(2)O(3) after 110 cycles) at the current density of 0.2C.

Evidence of spin phonon coupling in magnetoelectric NiFe{sub 2}O{sub 4}/PMN-PT composite

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ahlawat, Anju; Satapathy, S., E-mail: srinu73@rrcat.gov.in, E-mail: srinusatapathy@gmail.com; Gupta, P. K.

2013-12-16

The coupling of phonon with spin in strain coupled magnetoelectric NiFe{sub 2}O{sub 4} (NFO)/0.65Pb(Mg{sub 1/3}Nb{sub 2/3})O{sub 3}–0.35PbTiO{sub 3} (PMN-PT) composite was investigated by temperature-dependent Raman spectroscopy and magnetic measurements in the range 30–350 °C. Pure NFO shows usual ferromagnetic behaviour in this temperature range while NFO/PMN-PT composite show dramatic change in magnetic moment across ferroelectric transition temperature (T{sub c} ∼ 180 °C) of PMN-PT. The temperature evolution of the Raman spectra for the composite shows significant phonon anomalies in T-site (Fe-O) and O-site (Ni/Fe-O) phonon modes at ferroelectric transition temperature is attributed to spin phonon coupling in NFO/PMN-PT composite. The strain mediated magnetoelectric couplingmore » mechanism in this composite is apparent from the observed spin phonon interaction.« less

1D Magnetic Materials of Fe3O4 and Fe with High Performance of Microwave Absorption Fabricated by Electrospinning Method

PubMed Central

Han, Rui; Li, Wei; Pan, Weiwei; Zhu, Minggang; Zhou, Dong; Li, Fa-shen

2014-01-01

Fe3O4 and Fe nanowires are successfully fabricated by electrospinning method and reduction process. Wiry microstructures were achieved with the phase transformation from α-Fe2O3 to Fe3O4 and Fe by partial and full reduction, while still preserving the wire morphology. The diameters of the Fe3O4 and Fe nanowires are approximately 50–60 nm and 30–40 nm, respectively. The investigation of microwave absorption reveals that the Fe3O4 nanowires exhibit excellent microwave absorbing properties. For paraffin-based composite containing 50% weight concentration of Fe3O4 nanowires, the minimum reflection loss reaches −17.2 dB at 6.2 GHz with the matching thickness of 5.5 mm. Furthermore, the calculation shows that the modulus of the ratio between the complex permittivity and permeability |ε/μ| is far away from unity at the minimum reflection loss point, which is quite different from the traditional opinions. PMID:25510415