Amount Of Fe3O4 Research Articles

Nanoparticulate NaA zeolite composites for MRI: Effect of iron oxide content on image contrast

In the current study, Fe3O4/NaA nanocomposites with various amounts of Fe3O4 (3.4, 6.8 & 10.2 wt%) were synthesized and characterized to study the effect of nano iron oxide content on the magnetic resonance (MR) image contrast. The cell viability of the nanocomposites was investigated by MTT assay method. T2 values as well as r2 relaxivities were determined with a 1.5 T MRI scanner. The results of the MTT assay confirmed the nanocomposites cytocompatibility up to 6.8% of the iron oxide content. Although the magnetization saturations and susceptibility values of the nanocomposites were increased as a function of the iron oxide content, their relaxivity was decreased from 921.78 mM−1 s−1 for the nanocomposite with the lowest iron oxide content to 380.16 mM−1 s−1 for the highest one. Therefore, Fe3O4/NaA nanocomposite with 3.4% iron oxide content led to the best MR image contrast. Nano iron oxide content and dispersion in the nanocomposites structure have important role in the nanocomposite r2 relaxivity and the MR image contrast. Aggregation of the iron oxide nanoparticles is a limiting factor in using of the high iron oxide content nanocomposites.

The synthesis and application of the SiO2@Fe3O4@MBT nanocomposite as a new magnetic sorbent for the adsorption of arsenate from aqueous solutions: Modeling, optimization, and adsorption studies

This study was conducted for the purpose of showing that the mercaptobenzothiazole (MBT)-functionalized SiO2@Fe3O4 nanocomposite can be applied as a new adsorbent for the adsorption of As (V) ions from aqueous solutions. SiO2@Fe3O4@MBT synthesized via a two-stage process was characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), the transmission electron microscope (TEM) and Brunauer-Emmett-Teller (BET). The SEM showed good adsorbing capacity for SiO2@ Fe3O4@ MBT due to the average core size 40nm with a vast surface. The appearance of bands attributed to the CH stretch of methylenes of the alkyl chain in FTIR analysis showed SiO2@Fe3O4 was successfully modified by MBT. The XRD spectrum clearly demonstrates the occurrence of two phases of iron oxide/hydroxide and silica oxide, and also the spinal structure of SiO2@ Fe3O4@ MBT reveals the presence of SiO2, by revealing the specific peaks at 2θ=26.62, 39.44, 42.41, 54.83.The TEM micrograph of SiO2@ Fe3O4@ MBT showed the Fe3O4 nanoparticle anchored on SiO2 and formed a large amount of Fe3O4 with different size. Surface area of SiO2@ Fe3O4@ MBT was investigated and determined 58.35m2/g. Response surface methodology (RSM) was employed to model the effects of the operating parameters, such as pH (2–8), adsorbent dosage (10–100mgL−1), initial As (V) concentration (1–10mgL−1), and contact time (2–180min) using the R software. Based on the results obtained from the analysis of variance (ANOVA), the reduced full second-order model demonstrated satisfactory adjustment with the experimental data. The Solver “Add-ins” were applied using the effective parameters to optimize important operating variables. The optimum operating points were established at the initial As (V) concentration of 10mg L−1, the adsorbent dosage of 82.7mg L−1, the time of 169.1min, and the pH of 5.07, corresponding to the maximum predicted As (V) removal percentage of 93.89%. Based on the reported results, the experimental isotherm data best fit the Freundlich model rather than the other isotherms. The maximum adsorption capacities calculated from the Langmuir equation were 10.38, 11.35, and 17.5mg g−1 for 291K, 301K and 311K. The followed kinetic model was the pseudo-first order kinetic model in nature and intraparticle diffusion was the dominant mechanism.

A magnetic Fe3O4 decorated TiO2 nanoparticles application for photocatalytic degradation of methylene blue (MB) under direct sunlight irradiation

Fe3O4 enriched TiO2 nano photocatalyst with various weight percentage (2, 4, and 8 wt%) of Fe3O4 loaded on TiO2 were effectively synthesized by co-precipitation method for removal of methylene blue dye under direct sunlight. The characterizations of the as-prepared product were done by Field emission scanning electronic microscopy (FE-SEM), energy dispersive X-ray analysis spectroscopy (EDAX), transmission electron microscope (TEM), X-ray diffraction (XRD), Raman spectroscopy, UV-Vis diffuse reflectance spectroscopy (DRS), photoluminescence spectroscopy and electrochemical impedance spectroscopy. The photocatalytic degradation of methylene blue was used as a model reaction to evaluate the photocatalytic activity of Fe3O4@TiO2 nanoparticles under visible light irradiation. The influence of the doping amount of Fe3O4 (2, 4, and 8 wt%) on photocatalytic activity of TiO2 was investigated. Results show that the size of Fe3O4@TiO2 particle decreased and their absorption spectra are broadened with increased absorption intensity. The doping can control the conversion of TiO2 from anatase to rutile. The doping amount remarkably affects the activity of the catalyst, and the optimum efficiency occurs at about the doping amount of 8 wt%. The appropriate amount of doping 8 wt% can remarkably increase the catalytic activity of TiO2 for methylene blue (MB) photocatalytic degradation under visible light irradiation.

Correlating the microstructure, growth mechanism and magnetic properties of FeSiAl soft magnetic composites fabricated via HNO3 oxidation

Nitric acid oxidation has been used to fabricate insulation coatings of the FeSiAl soft magnetic composites (SMCs). Growth mechanism of the coatings obtained with varied HNO3 concentration has been systematically studied based on careful analysis of the coating thickness, microstructure and composition. The oxidation process for the powders reacted with 10 wt% HNO3 corresponds to the steady-state passivation, while pitting corrosion occurs with raised HNO3 concentration of 30 wt%. Origin of the pitting corrosion has been analyzed based on the point defect model. Evolution of the coatings has been revealed under different growth conditions and correlated to the magnetic performance of the SMCs. The samples oxidized with 10 wt% HNO3 mainly form a thin and compact oxidation layer with dominating Al2O3, AlO(OH) and a small amount of Fe3O4, while increased HNO3 concentration (30 wt%) gives rise to mixed Al2O3, AlO(OH), Fe2O3 and Fe3O4 in the thicker coating layers. Enhanced magnetic performance of the FeSiAl SMCs can be achieved by optimized thickness and composition of the coatings (μe = 180.4, Pcv = 327.2 mW/cm3 for the SMCs oxidized by 10 wt% HNO3 and μe = 157.3, Pcv = 241.2 mW/cm3 via oxidization by 30 wt% HNO3 for 5 min).

On the magnetic properties of the multiferroic ceramics [formula omitted][formula omitted

Multiferroic ceramics of Bi0.99Y0.01Fe1-xNixO3 with 0.01⩽x⩽0.05 were synthesized by using a modified solid state reaction method. The crystalline structure and the morphology of the samples were investigated by X-ray diffraction (XRD) and by scanning electron microscopy (SEM). The addition of Y and Ni to the bismuth ferrite (BiFeO3) was found to decrease the average grain size. Ac magnetic susceptibility and the zero-field-cooled (ZFC) and field-cooled (FC) magnetizations were measured for temperatures in the range 5⩽T⩽300 K. Hysteresis loops and an irreversible behavior in the temperature dependence of the magnetization not present in pure BiFeO3 were observed in the doped samples. However, the ferromagnetism was found more likely to be due to the presence of small amounts of magnetite. Nevertheless, the determination of the amount of Fe3O4 in these composite materials is important because it influences the magnetoelectric coupling which is important for some technological applications.

Site energy distribution analysis and influence of Fe3O4 nanoparticles on sulfamethoxazole sorption in aqueous solution by magnetic pine sawdust biochar

Magnetisation of carbonaceous adsorbents using iron oxides has been found to be one of the potential solutions for easy recovery of adsorbent after use. We evaluated the effects of Fe3O4 nanoparticle addition on the physico-chemical properties of biochar and its sorption properties. Five adsorbents with varying amount of Fe3O4 per mass of adsorbent (0%, 25%, 50%, 75% and 100%) were used to adsorb sulfamethoxazole (SMX), an emerging micropollutant. Five isotherm models were used to evaluate the sorption behaviour of SMX onto the adsorbents where Redlich-Peterson model was found to best describe the data. Based on this model, the approximate site energy distribution for each adsorbent was determined. Surface area and sorption capacity had strong negative linear relationship with the amount of Fe3O4 per mass of adsorbent while the pore volume and saturation magnetisation of the adsorbent increased with increasing percentage of Fe3O4. The results of the approximate site energy distribution analysis showed that the addition of Fe3O4 on biochar reduced the area under the frequency distribution curve of sorption site energies leading to the lowering of the sorption sites available for SMX. This could be attributed to the blockage of the hydrophobic surface of biochar reducing the hydrophobic interaction between SMX and biochar.

An Industry Friendly Approach for the Preparation of Magnetic and Electro-Conductive Polyaniline Composite Particles

Recently nano-sized conducting polymers have gained ample attention because of their unique properties and promising potentiality in nanomaterials and nanodevices. Among the conducting polymers, polyaniline (PANi) is the most studied conducting polymers because of its low monomer cost, ease of preparation, high conductivity in doped form, excellent environmental stability, controllable physical and electrochemical properties by oxidation and protonation. In this investigation magnetic PANi composite particles were prepared following a novel approach by using citric acid for the first time as dopant, surfactant and solubilizing agent. As synthesized citric acid doped Fe3O4 (magnetite)/PANi nanocomposites have been characterized by Fourier Transform Infrared Spectroscopy (FTIR), X-ray diffractometer (XRD), Scanning electron microscope (SEM), Thermogravimetry analysis (TGA). Spectroscopic analyses confirmed the modification of Fe3O4 nanoparticles by PANi layer. The Magnetic susceptibility results revealed the paramagnetic behavior of Fe3O4/PANi nanocomposite particles. The electrical conductivities of Fe3O4/PANi nanocomposites increased up to certain amount of Fe3O4 and decreased thereafter.

Preparation and characterization of a biocompatible magnetic scaffold for biomedical engineering

Recently the fabrication of 3D scaffolds with the potential of application as flexible bone graft substitutes has been attracted many researches. In this research, a 3D nanocomposite scaffold composed of gelatin and hydroxyapatite was proposed by employing the freeze-drying methods. Nanoparticles of Fe3O4 were added to the gelatin/hydroxyapatite in order to magnetize the 3D nanocomposite scaffold. Addition of magnetite particles makes the 3D nanocomposites an appropriate drug carrier, which can trigger drug release by an external magnetic field stimulation. Therefore, the scaffold can play the role of bone substitute and drug carrier simultaneously. The microstructure and morphology of these scaffolds were investigated using Fourier transform infrared spectroscopy (FTIR), X-ray diffraction analysis (XRD), scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS). Elastic modulus and compressive strength of the scaffolds were investigated by a tensile test instrument. The magnetization variation of the scaffolds was investigated by a vibrating sample magnetometer at room temperature. Water and phosphate buffer saline (PBS) solution were utilized to determine the in vitro swelling behavior of the scaffolds after 24 h. The MTT assays on L929 cells was used to study the cytotoxicity of the prepared samples.According to the results, the FTIR spectrum confirms the presence of gelatin, hydroxyapatite and magnetite nanoparticles. The XRD patterns show the presence of ceramic crystalline area in the gelatin/hydroxyapatite network and also the Fe3O4 nanoparticles. SEM images of the scaffolds show a highly interconnected porous structure with maximum 85% porosity. The pore size range of the scaffolds is 120–210 μm. The SEM-EDS analyses confirms the presence of Fe element in the structure of composites. Comparing the mechanical properties of the scaffolds with the trabecular bone tissue revealed that the compressive strength of the scaffolds is in the adequate range of 2–4.5 MPa. In addition, the magnetization test revealed that the Fe-4 sample with highest amount of Fe3O4 possess a proper magnetic property. Results suggested that by increasing the percentage of Fe3O4 the swelling of sample decreased for both water and PBS solutions. Cell culture experiments exhibited that the scaffold extracts were not cytotoxic in any concentrations. According to the results, the synthesized 3D nanocomposite scaffolds possess a great potential to be used as bone substitute and drug carrier simultaneously.

Fe3O4 promoted metal organic framework MIL-100(Fe) for the controlled release of doxorubicin hydrochloride

Cancer, an irremediable disease has a less survival rate among the patients in worldwide. Conventional anticancer agents or medicines exhibit poor performance in targeted delivery and causes toxicity in body with doses. Recently, attempts were made to develop different nanocarriers for targeted release of the chemotherapeutic medicines to cancer cells. The important issues with the existing drug carriers lies on their poor loading capacity or premature release of the drug from the external surface. To address this issue, porous metal organic frameworks with greater tunability and high surface area may be more suitable for the drug delivery applications. In this work, a metal organic framework (MOF) MIL-100(Fe) and its composite with Iron oxide nanoparticles Fe3O4@MIL-100 were investigated as delivery agents for anticancer drug doxorubicin hydrochloride (DOX). A series of composites with varying amounts of Fe3O4 were synthesized by adding different amount of Fe3O4 to the solvent mixture used for synthesis of the MOF MIL-100. The composites were characterized by various techniques like BET, TEM, FESEM, VSM and TGA to understand the effect of the nanoparticles in the MOF structure. The MOF and several Fe3O4@MIL-100 composites were then analyzed used to load the drug by equilibrating aqueous solution of DOX with the porous carriers. The highest DOX loading capacity (∼19 mass %) was observed for MIL-100 composites containing about 16 mass % of Fe3O4 particles. The release profiles of the DOX loaded carriers dispersed in phosphate-buffered saline (PBS, pH 7.4, 37 °C) indicate that the kinetics slow down after incorporation of the Fe3O4 nanoparticles.

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

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.

Fast SPE and HPLC–DAD determination of brucine in human urine using multi-walled carbon nanotubes modified with magnetic nanoparticles

A nanomaterial comprising Fe3O4-modified hydroxylated multi-walled carbon nanotubes (Fe3O4–MWCNTs–OH) was prepared by a co-precipitation method. Combined with HPLC-photodiode array detector (DAD), Fe3O4–MWCNTs–OH was used to determine brucine in human urine. Some important parameters that could influence extraction efficiency of brucine were optimized, including the extraction time, amounts of Fe3O4–MWCNTs–OH, pH of sample solutions, desorption solvent and desorption time. Under the optimal conditions, the recoveries of brucine from spiked urine samples were between 93.1 and 104.1%, and the relative standard deviations (RSDs) ranged from 3.1 to 5.7%. The correlation coefficient was 0.9997. The limits of detection and quantification were 6 and 21 ng/mL at a signal-to-noise ratio of 3 and 10, respectively. The results indicated that Fe3O4–MWCNTs–OH combined with HPLC–DAD is a promising solid-phase extraction material for the sample pretreatment in the determination of brucine.

Optimization of ultrasound-assisted magnetic retrieval-linked ionic liquid dispersive liquid–liquid microextraction for the determination of cadmium and lead in water samples by graphite furnace atomic absorption spectrometry

Abstract A simple and efficient method for the determination of Cd and Pb in water samples was developed by ultrasound-assisted magnetic retrieval-linked ionic liquid dispersive liquid–liquid microextraction (UA-MR-IL-DLLME) preconcentration and graphite furnace atomic absorption spectrometry (GFAAS) detection. Ionic liquid (IL) [Hmim] [PF6] was used as the extractant, ammonium pyrrolidine dithiocarbamate (APDC) as the complexing agent and Fe3O4 nanoparticles as the sorbent, while ultrasound was applied to assist the dispersion of the extractant and accelerate the mass transfer process. The effect of different factors on the extraction efficiency including pH, IL volume, APDC amount, ultrasound extraction time, ultrasound desorption time and Fe3O4 amount was studied by a fractional factorial design to screen for the most important factors. Then a central composite design was used to optimize the significant factors. Under the optimal conditions, the method has linear calibration curves over the range of 0.3–20 ng/mL for Cd and 0.5–40 ng/mL for Pb, with correlation coefficients (R) of 0.9990 and 0.9986 for Cd and Pb, respectively. The limits of detection were 0.1 ng/mL and 0.15 ng/mL with relative standard deviations of 3.4% and 2.8% for Cd and Pb, respectively. Finally, the method was successfully applied for the determination of Cd and Pb in the real water samples and satisfactory recoveries were achieved.

The influence of metal oxides on the separation properties of hybrid alginate membranes

ABSTRACTAlginate membranes filled with different metal oxide particles were prepared and the influence of the presence of different amounts of Fe3O4, ZnO, and Ag2O particles on ethanol and water permeation was discussed. Ethanol and water vapour permeation rates were determined using the measuring cell method, and the mass transport coefficients were evaluated. It was found that the highest transport parameters were obtained for membranes with the highest metal oxide content. Furthermore, the highest flux, equal 8.49 kg·m−2·h−1, was obtained for the alginate membrane filled with 15 wt% of silver oxide particles, while the greatest selectivity coefficients were noted for membranes containing magnetite. In this case, for the alginate membrane with 15 wt% of magnetite content, the selectivity coefficient reached the best value of 108.15.

Fe-MOF-derived highly active catalysts for carbon dioxide hydrogenation to valuable hydrocarbons

Fe-based catalysts were acquired by one-step Fe-MIL-88B pyrolyzation and it showed high catalytic performance on hydrogenated conversion of carbon dioxide to valuable hydrocarbons. The iron compositions and catalytic performance of the catalysts were determined by pyrolysis temperatures according to XRD, SEM, TEM, N2-physisorption, Raman and evaluation results. Magnetite was obtained at 773K while metallic iron was the main phase when the pyrolysis temperature increased to 973K. Different catalytic performances over these catalysts were attributed to the transformation of iron species under the reaction conditions. Olefin-to-paraffin ratio (O/P) over pyrolyzed and K-doped catalysts was 1.3 and 5.5, respectively, and the two samples exhibited CO2 conversion with 46.0% and 43.1%, respectively. Higher catalytic performance was achieved when certain amount of Fe3O4 and χ-Fe5C2 existed in catalysts whereas metallic iron and/or θ-Fe3C had detrimental effects on lower conversion of CO2 and selectivity of valuable hydrocarbons.

Magnetic Fe3O4@silica sulfuric acid nanoparticles promoted regioselective protection/deprotection of alcohols with dihydropyran under solvent-free conditions

Protection (and deprotection) of hydroxyl groups via tetrahydropyranylation was carried out effectively using a catalytic amount of Fe3O4 supported silica sulphuric acid nanoparticles (Fe3O4@SiO2@SO3H) under solvent-free conditions.

Synthesis, characterization, magnetic and catalytic properties of graphene oxide/Fe3O4

In this paper, graphene oxide/Fe3O4 (GO/Fe3O4) nanocomposites were prepared by using co-precipitation method at low temperature. The formation of the GO/Fe3O4 nanocomposites was confirmed by X-ray diffraction (XRD), Energy dispersive X-ray analysis and Fourier transform infrared analysis. The morphology and particle size of the GO/Fe3O4 nanocomposites were investigated by Transmission electron microscopy (TEM) and Scanning electron microscopy. The grain size of the Fe3O4 nanoparticles was estimated about 10–20 nm from XRD. Also, the particle size of the Fe3O4 nanoparticles (according to TEM image) was found to be smaller than 20 nm. Finally magnetite property of the GO/Fe3O4 nanocomposites was studied by vibrating sample magnetometer (VSM) and Mossbauer spectroscopy. The VSM and Mossbauer results were confirmed each other and shown the magnetite property decrease by decreasing the Fe3O4 amount of samples. Also, catalytic activity of the GO/Fe3O4 nanocomposites has been tested for the reduction of methylene blue at room temperature. It was found that the GO/Fe3O4 nanocomposites are highly active and recyclable catalysts and due to the magnetic separability can be recovered and reused several times without marked loss of activity.

Solution and surface chemistry of the Se(IV)-Fe(0) reactions: Effect of initial solution pH

Aspects of solution and solid-phase reactions between selenite (Se(IV)) and nanoscale zero-valent iron (nZVI) were investigated. Experimental results on the effects of initial solution pH, formation and evolution of nZVI corrosion products, and speciation of selenium in nZVI were presented. In general, the rate of Se(IV) removal decreases with increasing initial pH. The observed rate constants of Se(IV) removal decreased from 0.3530 to 0.0364 min−1 as pH increased from 4.0 to 10.0. Composition and morphology of nZVI corrosion products and selenium species were characterized using scanning electron microscopy (SEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). Results confirmed that Se(IV) was reduced to Se(0) and Se(-II) by nZVI. Lower solution pH favored further reduction of Se(0) to Se(-II). Amorphous FeOOH, magnetite/maghemite (Fe3O4/γ-Fe2O3) and ferrous hydroxide (Fe(OH)2) were identified as the main corrosion products. Under alkaline conditions, the corrosion products were mainly of Fe(OH)2 along with small amounts of Fe3O4, while nZVI in acidic solutions was oxidized to mostly Fe3O4 and amorphous FeOOH. Furthermore, these corrosion products acted as intermediates for electron transfer and reactive/sorptive sites for Se(IV) adsorption and reduction, thus played a crucial role in the removal of aqueous Se(IV).

Fabrication and performance of magnetite (Fe3O4) modified carbon paste electrode for the electrochemical detection of chlorite ions in aqueous medium

The magnetite nanoparticles (Fe3O4), synthesized by surfactant aided hydrolysis of the stoichiometric amounts of ferrous (Fe2+) and ferric (Fe3+) ions, were dispersed in carbon paste (CP) to fabricate magnetite modified carbon paste electrode (Fe3O4/CPE). The field emission scanning electron microscopy (FESEM) was used to evaluate the morphology of the synthesized powder in the pure phase and its distribution in the CP that revealed the well-dispersed Fe3O4 nanoparticles in the graphite sheet with a mean size of 10nm. The microstructure analysis of the synthesized magnetite was performed by high-resolution transmission electron microscopy (HRTEM). The phase purity of the synthesized magnetite was evaluated by x-ray diffraction (XRD) analysis. After initial assessment of charge transport in the fabricated electrode by electrochemical impedance spectroscopy (EIS) that exhibited a substantial decrease of 87% in the charge transfer resistance, the suitability of the Fe3O4/CPE was assessed for the detection and determination of chlorite ion (ClO2−) in the aqueous medium. The modified CPE loaded with the optimized amount of Fe3O4 showed considerably enhanced oxidation current as compared to pure CPE for the oxidation of ClO2− and exhibited a near-reversible peak at ∼+0.73V in 0.1M pH 7 phosphate buffers, at a scan rate of 50mV/s. The optimum analytical conditions for the nanomolar detection of ClO2− by square wave voltammetry (SWV) were established. Likely interferences influencing the detection of ClO2− were also investigated. The excellent performance of the fabricated electrode was also established for the real tap and bottled water samples.

Fine Tuning the Composition and Nanostructure of Fe‐Based Core–Shell Nanocatalyst for Efficient CO2 Hydrogenation

AbstractHydrogenation of CO2 to hydrocarbons is one of the crucial technologies to address the energy deficit and increasing environmental pollution. In this work, we have synthesized and systematically studied the influence of composition and nanostructure of a Fe‐based, carbon‐coated core–shell nanocatalyst. The synthesis method offered good control over the thickness of the carbon coating in the core–shell catalyst, which in turn controlled the chemical composition of the core. The results emphasized an optimal amount of Fe3O4, Fe5C2 in the core and partially graphitized carbon in the shell for a high catalytic activity in the conversion of CO2 at atmospheric pressure with higher selectivity to C2‐C4 olefins.

High performance porous iron oxide-carbon nanotube nanocomposite as an anode material for lithium-ion batteries

Here, we showed that relatively high content of Fe3O4 nanoparticles (up to 83wt. %) can be homogeneously dispersed into carbon nanotubes (CNTs) conductive networks using non-aqueous media by refluxing method. Three different Fe3O4-CNTs composites were prepared, i.e., Fe3O4-CNTs-50, Fe3O4-CNTs-80 and Fe3O4-CNTs-90 that contain increasing amount of Fe3O4 from 50wt. % to 83wt. % and to 89wt. %. These composites have higher surface area and higher pore volume than Fe3O4 component due to CNTs content. The best composite, i.e., Fe3O4-CNTs-80 demonstrated negligible capacity loss up to 100 cycles and high discharge capacity of 930mA h g−1 at 100th cycle and 100mAg−1 current discharge rate. This composite also exhibited excellent rate capability where up to the 78.8% of original capacity can be retained at high current discharge rate of 1000mAg−1. These performances were enabled by a unique porous architecture based on homogenous dispersion of Fe3O4 nanoparticles into CNTs networks that leads to short Li+ diffusion path, high electric conductivity and buffering space to accommodate large volume change of Fe3O4 component during the charge-discharge processes.