As-prepared Fe3O4 Research Articles

Constructing carbon-coated Fe3O4 hierarchical microstructures with a porous structure and their excellent Cr(VI) ion removal properties

A facile solvothermal method coupled with an annealing strategy is developed to synthesize Fe3O4/carbon (Fe3O4@C) magnetic composite microstructures with different morphologies, including flower-like, hollow spheres and egg-like. The unique multiporous and hollow structure of the as-prepared hierarchical Fe3O4@C hollow microsphere results in an appealing performance as an absorber of Cr(VI) ions in aqueous solution, delivering a high capacity of ~ 197.2 mg/g. Meanwhile, the magnetic Fe3O4 ‘‘core’’ in the hierarchical microstructures can be easily separated from aqueous systems by magnetic separation. Furthermore, the carbon layers effectively prevent the aggregation of magnetic Fe3O4 nanoparticles. The excellent absorbing ability of Cr(VI) ions and easy separation process strongly suggest that the Fe3O4@C magnetic microstructures would have a great potential as adsorbing materials in the large-scale application in environmental purification.

Water-Dispersible Fe3O4 Nanoparticles Modified with Controlled Numbers of Carboxyl Moieties for Magnetic Induction Heating

Monodisperse Fe3O4 nanoparticles (NPs) with excellent water dispersibility and stability were prepared by the introduction of the carboxyl group (−COOH) on the surface of the as-prepared oleyl-capped Fe3O4 NPs. Controlled introduction of the COOH moieties on the NP surface was carried out by a simple ligand exchange reaction using two types of phosphonic acid ligands with dodecyl moiety and the terminal COOH group. The degree of modification of the COOH group on the particle surface was controlled by tuning the molar ratios of the two phosphonic acids. During the ligand exchange reaction, no change was observed in the crystal structure and morphology of the Fe3O4 NPs. The results of Fourier transform infrared (FT-IR) spectroscopy confirmed that the two ligands were bound to the Fe3O4 NP surface through their phosphoric acid functional groups. The surface coverage and molar ratios of the two ligands were evaluated by thermal gravimetric analysis (TGA) and via proton nuclear magnetic resonance (1H NMR) measurements, respectively. Results obtained from the thermal analyses were consistent with the initial molar ratios of the ligands used in the reaction, which reflect on the efficiency of the developed ligand exchange process. Our COOH-modified Fe3O4 NPs could be dispersed in water by deprotonation for over 6 months and exhibit a typical ferrofluid behavior without the addition of other surfactants and dispersants, showing high dispersion stability. Furthermore, the magnetic induction heating performance of the Fe3O4 NPs in aqueous dispersions was evaluated and the specific absorption rate (SAR) value was estimated to be 38.3 W/g Fe. These results suggest that our COOH-modified Fe3O4 NPs with the desired number of COOH surface moieties can be advantageous for applications such as precise surface design, water-based ferrofluid, and hyperthermia treatment.

18F-Labeled magnetic nanovectors for bimodal cellular imaging.

Surface modification of nanocarriers enables selective attachment to specific molecular targets within a complex biological environment. Besides the enhanced uptake due to specific interactions, the surface ligands can be utilized for radiolabeling applications for bimodal imaging ensured by positron emission topography (PET) and magnetic resonance imaging (MRI) functions in one source. Herein, we describe the surface functionalization of magnetite (Fe3O4) with folic acid as a target vector. Additionally, the magnetic nanocarriers were conjugated with appropriate ligands for subsequent copper-catalyzed azide-alkyne cycloaddition or carbodiimide coupling reactions to successfully achieve radiolabeling with the PET-emitter 18F. The phase composition (XRD) and size analysis (TEM) confirmed the formation of Fe3O4 nanoparticles (6.82 nm ± 0.52 nm). The quantification of various surface functionalities was performed by Fourier-transform infrared spectroscopy (FT-IR) and ultraviolet-visible microscopy (UV-Vis). An innovative magnetic-HPLC method was developed in this work for the determination of the radiochemical yield of the 18F-labeled NPs. The as-prepared Fe3O4 particles demonstrated high radiochemical yields and showed high cellular uptake in a folate receptor overexpressing MCF-7 cell line, validating bimodal imaging chemical design and a magnetic HPLC system. This novel approach, combining folic acid-capped Fe3O4 nanocarriers as a targeting vector with 18F labeling, is promising to apply this probe for bimodal PET/MR-studies.

Using a magnetite to accelerate of iron oxidation

Iron is one of the most abundant elements in the Earth’s crust. The metal is found in large quantities in rocks and soil systems around the world. It reaches the water bodies through geogenic sources as well as dumping of industrial effluents and domestic wastes into the water bodies. The surface water receives iron via effluents from iron and steel industries, mining as well as metal corrosion. The groundwater also receives iron through iron bearing rocks and minerals. According to WHO standards, iron content in drinking water is permitted only up to the concentration of 0.3 mg/L. However, the elevated levels of iron in water have been reported in different areas around the world due to increasing water pollution. Iron causes various health issues are linked with elevated levels of iron in water.Different strategies discussed in this article for removing the high iron content from water. Among the conventional strategies used, oxidation-precipitation-filtration process, separation through filter media and electrocoagulation. Methods such as ion exchange, adsorption, wetland treatment, aeration and sequestration were less effective in the removal of iron from the water. In this work, magnetite Fe3O4 as a catalyst used for purification of water from iron ions. As-prepared Fe3O4 nanoparticles were successful for aqueous solution iron removal. Batch experiments investigated the influence of pH, contact time and adsorbate/adsorbent concentration on Fe2+ adsorption. Experimental results suggest that the adsorption capacity of Fe3O4 nanoparticles towards metal ions depends on the from the concentration of magnetite and iron in water. Maximum iron removal occurred at pH≥6. At magnetite dose of 200 mg/ L and an iron concentration of 5 mg/DM3, its complete oxidation was achieved in less than 30 minutes. At magnetite dose of 500 mg/ L, complete iron oxidation was achieved in less than 30 minutes at iron concentrations of 5 and 15 mg/ L. It should be noted that at a magnetite dose of 500 mg/ L, effective iron oxidation also occurred at pH 5.70 - 6.05.The value of the sorption capacity of magnetite increases with an increase in the concentration of iron in the solution and with a decrease in the dose of magnetite with an increase in the mixing time and the degree of iron extraction. This is quite logical and fully corresponds to the ideas about sorption processes, including activated adsorption.In conclusion, it is here demonstrated that the magnetite Fe3O4 nanoparticles can be efficiently used as an effective, convenient and low-cost material for the removal and recovery of iron from water.

Facile sonochemical synthesis of nanoparticle modified Bi-MnOx and Fe3O4 deposited Bi-MnOx Nanocomposites for Sensor and Pollutant Degradation Application

Silver quantum dots particles (Ag QDs) and nanoparticles of Magnetite (Fe3O4) were deposited on nanotubes of Bismuth- insitu doped manganese oxide (Bi-MnOx) with porous morphologies via olymer assisted precipitation processes. The Ag QDs particles of very fine particle size and Fe3O4 nanoparticles were incorporated into the Bi-MnOx polymer composite via high power ultra-sonication deposition technique. Spherical nanoparticles of silver (5–15 nm) were deposited on the porous Bi-MnOx surfaces, whereas, in the case of the Fe3O4 which was deposited on Bi-MnOx nanotube composite in the form of nanorods, iron oxide particles were loaded into the tubular structure of the Bi-MnOx. The formation of nanotubes and the incorporation of nanorods were confirmed by the SEM and HR-TEM images. The diffuse reflectance spectra indicate a decrease in the bandgap of the composite after the incorporation of Fe3O4 nanoparticles into the Bi-MnOx nanotube . The nanoparticle-modified Bi-MnOx composite electrode was further characterized for hydrogen peroxide electrochemical sensor applications. Fast removal of toxic hexavalent chromium degradation reaction was carried out on the as-prepared Fe3O4- and Ag QDs particle-modified Bi-MnOx nanotube composites. An efficient sorption and removal of Cr (VI) (above 90% conversion) was achieved within 60 min of reaction on the Ag nanoparticle modfied Bi-MnOx. The results obtained show that the Ag@Bi-MnOx, and Fe3O4-modified porous Bi-MnOx nanotube composite materials demonstrated effective sensing and hexavalent chromium removal activity.

Facile synthesis of uniformly loaded Fe3O4–TiO2/RGO ternary hybrids for enhanced photocatalytic activities

Abstract Different from reported core-shell magnetic hybrids, Fe3O4–TiO2/RGO recyclable photocatalysts were synthesized by depositing both TiO2 and Fe3O4 nanoparticles homogeneously onto the graphene sheet through a facile one-pot hydrothermal approach. The unique structure can not only utilize the superior magnetism of Fe3O4 but also allow the photocatalytic property of Fe3O4 to full play, which can offer a synergistic effect with TiO2 and RGO. The characterization results of SEM and TEM demonstrated that Fe3O4 grains without the shell, as well as TiO2 particles, densely anchored onto RGO layers. According to the VSM analysis and cycle experiments, the as-prepared Fe3O4–TiO2/RGO catalyst maintained superior magnetism, stability and recycling performance. In particular, the photo-degradation ability of phenol was significantly affected by the molar ratio of iron to titanium and the optimized composites exhibited 96.6 mg g−1 total removal capacity under UV-light. The ESR spectra revealed that the uniform loaded Fe3O4 nanoparticles may further accelerate the transfer of photo-induced electrons, the designed structure of the ternary components in close contact with each other promotes the synergistic effect and the generation of hydroxyl radicals (·OH) and superoxide anion (O2·-). This work provides a novel facile fabrication of magnetic photocatalyst with uniformly loaded structure and outstanding photocatalytic performance, which has great application prospects in remediating organic contaminated water.

Synthesis of magnetic metal organic framework/covalent organic framework hybrid materials as adsorbents for magnetic solid-phase extraction of four endocrine-disrupting chemicals from milk samples.

Endocrine-disrupting chemicals (EDCs), widespread and easily ingested through the simple food chain, have been suggested to pose potential carcinogenic threats to human health. Considering food safety and public health, it is urgent to establish a sensitive and effective method to enrich and determine EDCs in food samples. Novel hybrid nanocomposites Fe3 O4 @A-TpBD@NH2 -MIL-125(Ti) were synthesized through the formation of amide bonds. The as-prepared Fe3 O4 were innovatively encapsulated with 4-aminobenzoic acid functionalized COF(A-TpBD) to generate bare carboxyl (-COOH), which formed amide bonds with the NH2 -MIL-125(Ti), generating well-defined and hierarchical hybrid materials. The Fe3 O4 @A-TpBD@NH2 -MIL-125(Ti) materials were used as the adsorbents for magnetic solid-phase extraction (MSPE) coupled with high-performance liquid chromatography/tandem mass spectrometry (HPLC/MS/MS) to enrich and determine EDCs (E1, E2, E3 and BPA) from milk samples. Fe3 O4 @A-TpBD@NH2 -MIL-125(Ti) exhibited improved adsorption efficiency and selectivity based on π-π stacking interaction, hydrogen bonding, electrostatic interaction, and the interaction between the hydroxyl group in EDCs and titanium ions (IV, [Ti]4+ ). Under the optimized conditions, Fe3 O4 @A-TpBD@NH2 -MIL-125(Ti)-based MSPE coupled with HPLC/MS/MS showed good linearity with correlation coefficient (R2 ) ≥0.9983 and high sensitivity with limits of detection (LODs) in the range of 0.37-0.85 μg/L. Moreover, the developed method was successfully employed to detect EDCs in milk samples. Fe3 O4 @A-TpBD@NH2 -MIL-125(Ti) possess good adsorption capability and selectivity for EDCs. In addition, the proposed MSPE-HPLC/MS/MS method based on Fe3 O4 @A-TpBD@NH2 -MIL-125(Ti) is effective and sensitive for the determination of EDCs in real samples, which can be used as a robust alternative method to monitor EDCs in complex matrices.

High recycling Fe3O4-CdTe nanocomposites for the detection of organophosphorothioate pesticide chlorpyrifos

To alleviate the secondary contamination of our environment when using quantum dots (QDs) to detect the organophosphorothioate pesticides (OPPs), we herein report a strategy to assemble magnetic Fe3O4 nanoparticles and luminescent CdTe quantum dots (QDs) into a composite nanosystem, which possesses both the magnetic property of Fe3O4 nanoparticles and the luminescent character of CdTe QDs, for the detection of chlorpyrifos, one of the typical OPPs. This strategy involves the isolated synthesis of magnetic Fe3O4 nanoparticles with positive charges and luminescent CdTe QDs with negative charges, and their subsequent assembly by electrostatic interaction. The as-prepared Fe3O4–CdTe nanocomposites have a detection limit as low as 10 ppb for chlorpyrifos, and are also selective for the OPPs with a phosphorothioate moiety (PS bond). In specific, the Fe3O4–CdTe nanocomposites can be conveniently harvested by a normal magnet, and the recycling rate for both Cd and Fe determined by inductively coupled plasma atomic emission spectroscopy (ICP-AES) is higher than 96%, showing great potential in alleviating the Cd pollution on the environment.

One-step synthesis of ultra-small Fe2O3 nanoparticles on carbon nanotubes at a low temperature as a high-performance anode for supercapacitors

The composites of Fe2O3 nanoparticles and carbon nanotubes (CNTs) can be applied in many fields including energy storage. The synthesis of Fe2O3/CNTs composite is usually carried out under high temperatures with complicated processes. To solve these problems, we report a novel one-step chemical bath deposition method to synthesize it at a very low temperature in this work. With DMF as a complex agent, ferrous cations can be well combined with the external surface of CNTs to form small Fe2O3 nanoparticles just at 70 °C for 2-h reaction. XRD, SEM, and TEM analyses confirm that as-prepared Fe2O3 nanoparticles are ultra-small, well crystallized, and highly dispersed onto the surface of CNTs. When being used as an electrode material for supercapacitor, the composite has a specific capacitance of 942 F g−1 at 2 A g−1 and 645 F g−1 at 15 A g−1, exhibiting a higher specific capacitance than previously reported Fe2O3/CNTs composites due to its smaller size.

Fabrication of novel magnetic core-shell chelating adsorbent for rapid and highly efficient adsorption of heavy metal ions from aqueous solution

A novel magnetic core-shell Fe3O4@[epichlorohydrin-co-triethylenetetramine]n-graft-CSSNa microspheres (Fe3O4@[ECH-co-TETA]n-g-CSSNa) was successfully fabricated through adhesion and subsequent crosslinking of poly(epichlorohydrin-co-triethylenetetramine) copolymer ([ECH-co-TETA]n) on Fe3O4 microspheres and then grafting with dithiocarbamate (−CSS−). The as-prepared Fe3O4@[ECH-co-TETA]n-g-CSSNa microspheres presented an uniform core-layer architecture with approximately 600 nm of particle sizes and 50 nm of coating layer. The −CSS− content of Fe3O4@[ECH-co-TETA]n-g-CSSNa was 1.9257 mmol g−1, and its measured magnetization saturation value was 50.51 emu g−1. Benefiting from its unique microstructure, the resulting adsorbent exhibited high adsorption efficiencies of 293.85, 256.69, 277.93, and 225.07 mg g−1 for Pb2+, Cd2+, Cu2+, and Zn2+ in the pH range of 5.00–8.00 at 293 K, respectively, and rapid adsorption speed of reaching equilibrium within 10 min. Meanwhile, the resulting adsorbent could be easily regenerated at least five cycles with a little capacity loss and exhibited excellent magnetic separation performance. The adsorption data fitted the Langmuir and pseudo-second-order models well, and the adsorption activation energies for Pb2+, Cd2+, Cu2+, and Zn2+ were 26.6359, 15.6302, 26.5152, and 21.1095 kJ mol−1, respectively. All adsorption were spontaneous endothermic processes featuring an entropy increase, involving electrostatic attraction, physisorption, and chemisorption (especially ion exchange and surface complexing adsorption). In chemisorption, S, N, and O in the active layer of Fe3O4@[ECH-co-TETA]n-g-CSSNa were all involved in the formation of a coordination bond and particularly formed a symmetrical S-coordinated four-membered ring of (–CSS−)2M2+. Our work suggests a promising strategy for the rapid and highly efficient removal of heavy metal ions from wastewater.

Nitrogen/chlorine-doped carbon nanodisk-encapsulated hematite nanoparticles for high-performance lithium-ion storage

Iron oxide (Fe2O3) is an intriguing anode material of electrochemical energy storage systems such as rechargeable batteries. The rational design of its nanostructure at mild condition to cope with the issues of low reversible capacity and sluggish kinetics is required. Herein, an efficient, facile, and potentially large-scale synthesis approach using the precursor of laminated iron oxychloride@polyaniline heterostructure and mild annealing is developed, yielding unique Fe2O3@carbon nanocomposites with hematite nanoparticles (∼20 nm) that embedded in nitrogen/chlorine-doped carbon nanodisk (N/Cl–C). Given the benefit of abundant active sites, good chemical contact between carbon and Fe2O3, and robust composite structure, the as-prepared Fe2O3@N/Cl–C anode material delivers competent lithium-ion storage properties, including high reversible capacity of 1010 mAh g−1 (based on the mass of the as-prepared nanocomposite) at 0.1 A g−1, decent rate performance upon a rigorous current change, and superior cycling stability with 955 mAh g−1 after 180 cycles as well as a sustained Coulombic efficiency of about 99%. This structural design may provide a new avenue for achieving efficient iron oxide-based materials in chemical and electrochemical applications such as catalysis, lithium-ion batteries, and sodium-ion batteries.

A lightweight and flexible CNT/Fe3O4 composite with high electromagnetic interference shielding performance

Lightweight and flexible electromagnetic interference (EMI) shielding materials are in great demand for wearable EMI device. In the present work, lightweight and flexible carbon nanotube (CNT)/ferroferric oxide (Fe3O4) composite film was made through a feasible chemical vapor deposition process for CNT film synthesis, followed by a hydrothermal reduction process for Fe3O4 coating. In the as-prepared composite, CNT film and Fe3O4 particles work as conductive skeleton and strong magnetic particle, respectively. The as-prepared composite film shows a novel EMI shielding effectiveness (SE) of 91 dB in the X-band, a small thickness of 0.09 mm and a low density of 0.86 g/cm3, which is superior to most of the carbon-based EMI materials.

Quasi-amorphous and Hierarchical Fe2O3 Supraparticles: Active T1-Weighted Magnetic Resonance Imaging in Vivo and Renal Clearance.

The exploration of magnetic resonance imaging (MRI) agents possessing excellent performances and high biosafety is of great importance for both fundamental science research and biomedical applications. In this study, we present that monodisperse Fe2O3 supraparticles (SPs) can act as T1-weighted MRI agents, which not only possess a distinct off-on MRI switch in the tumor microenvironment but also are readily excreted from living bodies due to its quasi-amorphous structure and hierarchical topology design. First, the Fe2O3 SPs have a surface-to-volume ratio obviously smaller than that of their building blocks by means of self-assembly processes, which, on the one hand, causes a rather low r1 relaxivity (0.19 mM-1 s-1) and, on the other hand, can effectively prevent their aggregation after intravenous injection. Second, the Fe2O3 SPs have a dramatic disassembly/degradation-induced active T1-weighted signal readout (more than 6 times the r1 value enhancement and about 20 times the r2/r1 ratio decrease) in the tumor microenvironment, resulting in a high signal-to-noise ratio for imaging performances. Therefore, they possess excellent in vivo imaging capacity, even with a tumor size as small as 5 mm3. Third, the disassembled/decomposed behaviors of the Fe2O3 SPs facilitate their timely clearance/excretion from living bodies. In particular, they exhibit distinct renal clearance behavior without any kidney damage with the right dosage. Fourth, the favorable biodegradability of the as-prepared Fe2O3 SPs can further relieve the concerns about the unclear biological effects, particularly on nanomaterials, in general.

Green preparation of Fe3O4 coral-like nanomaterials with outstanding magnetic and OER properties

Abstract Developing multifunctional of a material is a good alternative for optimizing their use in many fields. In this study, a series of Fe3O4 coral-like nanomaterials with excellent magnetic and electrocatalytic oxygen evolution reaction (OER) properties were greenly prepared by a facile template-assisted dipping/adsorbing-calcining two-steps method and characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscopy (TEM), Fourier transform infrared (FT-IR) spectroscopy and BET techniques. Meanwhile, the effect of calcination temperature on the properties of the as-prepared samples was investigated. The results display that the magnetic and electrocatalytic OER properties of as-prepared Fe3O4 nanomaterials are affected by calcining temperature. For example, their magnetic intensity increases with increasing the temperature while the OER activity is best at 450 °C, an overpotential of 234 mV@10 mA cm−2 with a Tafel slope of 100 mV dec−1. It is believed that the excellent electrocatalytic OER property of as-prepared sample at a proper calcining temperature should give the credit to its special morphology, which endows large surface area and special pore structure/size and proper structural defect, bringing about efficient adsorption and activation and fast migration of the reactant molecules, and offering the smooth path of elctron transfer for promoting the OER activity. It is worthy mentioned that this preparation strategy is low-cost, simple, environmentally friendly, and can make full use of the wasted resources.

Facile synthesis of porous carbon/Fe3O4 composites derived from waste cellulose acetate by one-step carbothermal method as a recyclable adsorbent for dyes

The porous carbon/Fe3O4 composites have been used to adsorb the dyes recently, however, most carbon sources are not preferable for the environment protection. In this paper, the porous carbon/Fe3O4 composites were synthesized by a simple step carbonization method using the waste cigarette butts and the ferric nitrate as carbon source and oxidizer, respectively. Notably, the obtained products can be reused. The results show that the crystallite size of as-prepared Fe3O4 will increase at high treating temperature. In addition, the sample of C-Fe3O4-1000 possesses the highest saturation magnetization of 92.2 emu g−1, and the sample of C-Fe3O4-600 has the highest specific surface area of 90.23 m2 g−1 and the maximum adsorption of 102.04 mg g−1 for methyl orange. Furthermore, the adsorbent can maintain an excellent adsorption capacity for the dye after 4 cycles. Therefore, as-prepared porous carbon/Fe3O4 composite is an excellent candidate for recyclable dye adsorbent, and the waste can be converted into products for reducing the environment pollution.

Ultrasensitive aptamer-based protein assays based on one-dimensional core-shell nanozymes

In enzyme-based immunoassys, the use of natural enzyme has been remarkably restricted by the inconvenience in preparation and storage, especially for point-of-care testing. Nanozymes, which can mimic the functions of natural enzymes, have been regarded as promising alternatives due to their robust stability and convenience in fabrication. Here we fabricated one-dimensional Fe3O4@C core-shell nanostructures via a solvent-thermal method. Thus prepared nanocomposites showed excellent peroxidase-like activity, capable of catalyzing chromogenic substrates into colored products in the presence of H2O2. We then developed a nanozyme-linked aptamer sorbent assay (NLASA) in a sandwich format, in which the as-prepared Fe3O4@C nanowires were employed as catalytic labels for colorimetric detection by naked eyes. In the detection of platelet-derived growth factor BB (PDGF-BB), this assay reliably exhibited detection limits as low as 10 fM, with a working range from 10 fM to 100 nM. By incorporating G-quadruplex-hemin DNAzyme with Fe3O4@C nanowires, the detection limit could be further lowered to 50 aM. The detection limit of PDGF-BB in 50% human serum was 100 fM. This ultrasensitive, cost-effective and easy-to-operate sensing platform offers new opportunities for protein detection in clinical diagnosis.

Ag‐deposited carbon‐coated Fe 3 O 4 magnetic microparticles as highly efficient and recyclable catalysts

In this work, Ag nanoparticles (AgNPs) with average sizes of 20 nm were well-dispersed on the surfaces of magnetic carbon-coated Fe3O4 (Fe3O4@C) microparticles through a simple in situ growth process. The catalytic efficiency of the as-prepared AgNPs-decorated Fe3O4@C particles was evaluated using a model reaction based on the reduction of 4-nitrophenol (4-NP) by an excess of NaBH4. The kinetic data of the reduction reaction could be explained by the assumption of a pseudo-first-order reaction with regard to 4-NP. Also the particles are catalytically more active due to their extremely high-density AgNPs immobilised on the surfaces of Fe3O4@C particles. Significantly, the Fe3O4@C@Ag catalysts can be easily separated from the reaction media by applying an external magnet, and can be reused for several cycles.

Green synthesis of magnetite nanoparticles using Brassica napus flower extract: an efficient and highly recyclable catalyst for the one-pot synthesis of some new N, Nˉ- Bis [(p-cresol-2-yl) substituted phenyl methyl]-4, 4ˉ - oxydianilines

For the first time, magnetite (Fe3O4) nanoparticle was green synthesized using the extract of the Brassica napus flower-extract as a new adsorbent nanocatalyst. The characterizations have been done using XRD, UV-vis, SEM-EDX, FT-IR, and ED-XRF. As-prepared Fe3O4 nanoparticles were successful for the preparation of Bis-Betti bases via one-pot three component reactions of para cresol, primary diamine and substituted aromatic aldehydes to provide N, Nˉ- Bis-[(p-cresol-2-yl)-substituted phenyl-methyl]-4, 4ˉ - oxydianiline derivatives. These reactions were also studied under different conditions without any catalyst by employing conventional method, ultrasonic technique and microwave irradiation. The synthesized products have been characterized by melting point, FT-IR, 1HNMR, 13C NMR, Mass spectral data. In fact, the prepared magnetite is quite effective nanocatalyst and stable for these reactions; facile, clean with high yield products. Moreover, the magnetite nanocatalyst was recovered and reused several times without considerable loss of its catalytic activity.

One-step thermal decomposition of C4H4FeO6 to Fe3O4@carbon nano-composite for high-performance lithium-ion batteries

The applications of Fe3O4 in lithium-ion batteries are greatly restricted due to the low electrical conductivity, and poor cycling stability that is owing to the large volume expansion. To overcome these drawbacks, Fe3O4@C nano-composite was designed and synthesized via a one-step thermal decomposition of C4H4FeO6 served as the precursor for both Fe3O4 and carbon. As an anode material for lithium-ion batteries, the Fe3O4@C composite exhibits a reversible capacity of 680 mAh/g at a current density of 0.2 A/g, and after 600 times, the discharge capacity of the as-prepared Fe3O4@C networks is determined to be 590 mAh/g, showing superior cycling stability. The simple synthetic procedure and excellent performances makes Fe3O4@C a promising candidate as the potential anode material for lithium-ion batteries.

Hierarchical sandwiched Fe3O4@C/Graphene composite as anode material for lithium-ion batteries

A three-dimensional hierarchical sandwich structured Fe3O4@C/Graphene nanocomposite was synthesized with a facile hydrothermal method, followed by carbonization process. The Fe3O4@C/Graphene nanocomposite consists of well-dispersed carbon enwrapped Fe3O4 nanoparticles anchored on graphene layers. The three-dimensional sandwich structure and the wrapping carbon effectively improve the mechanical stability and conductivity of encapsulated Fe3O4. The as-prepared Fe3O4@C/Graphene composite delivers a specific capacity of 1253.3mAhg−1 at the first cycle and 901.5mAhg−1 after 200cycles at 200mAg−1. Even at 1500mAg−1, the Fe3O4@C/Graphene nanocomposite is able to deliver a discharge capacity of 592.3mAhg−1. The good cycle and rate performance of Fe3O4@C/Graphene anode can be attributed to its micro−/mesoporous structure with large specific surface area, which not only provides more transmission paths and active sites, but also reduces the diffusion impedance in electrolyte to realize fast transport of Li ions.