Crystalline Fe3O4 Nanoparticles Research Articles

Polypyrrole Coating via Lemieux-von Rudloff Oxidation on Magnetite Nanoparticles for Highly Efficient Removal of Chromium(VI) from Wastewater.

An alternative way for the coating of polypyrrole (PPy) polymer on hydrophobic magnetite (Fe3O4) nanoparticles is reported here to capture toxic chromium ions, Cr (VI), present in water. Iron oxide magnetic nanoparticles (Fe3O4) were synthesized by the conventional coprecipitation technique using FeCl3·6H2O and FeSO4·7H2O iron precursors and subsequently modified with oleic acid (OA). Then OA-Fe3O4 hydrophobic nanoparticles were oxidized using the Lemieux-von Rudloff reaction to transfer OA into hydrophilic azelaic acid (AA) (HOOC(CH2)7COOH-modified magnetic nanoparticles (AA-Fe3O4). Finally, a PPy polymer coating was formed by a seeded polymerization of pyrrole, using AA-Fe3O4 as seeds. The average size of PPy/Fe3O4 nanocomposites is 12.33 nm and is almost spherical in shape. The surface composition is confirmed by FTIR and thermogravimetry analyses. An X-ray diffraction study confirmed the formation of highly crystalline Fe3O4 nanoparticles, and the crystallinity was retained after the surface modification. The adsorption study suggested that the Cr(VI) ion adsorption is highly pH-dependent and the maximum amount of adsorption is obtained at pH 2.0. The adsorption results revealed that the Langmuir model provided the best fit for the isotherm, with a maximum adsorption capacity reaching approximately 173.22 mg g-1 at 323 K. Spontaneous and endothermic adsorption processes were confirmed by evaluating the thermodynamic parameters obtained in this investigation. The kinetics study showed that the interaction between Cr(VI) ions and magnetic nanocomposites was directed by a pseudo-second-order rate process indicating chemisorption. The prepared PPy/Fe3O4 nanocomposites would be promising adsorbents to purify water by eliminating Cr(VI) metal ions from wastewater.

Synthesis and characterization of ternary nanocomposite based on Ag-Fe3O4/rGO for electrochemical application

In-situ synthesis of a ternary nanocomposite based on Ag-Fe3O4/rGO by utilizing Azadirachta indica leaf extract as a reducing agent has been carried out. The morphological, EDX, and structural analyses confirm the reduction of GO into rGO by forming crystalline Fe3O4 and Ag nanoparticles in the rGO matrix, with a crystalline size of 25.77 nm. Further, the FTIR, UV-Vis, and BET analyses confirmed the effective interaction between Fe3O4 and Ag nanoparticles in the rGO matrix, tunable bandgap, and a higher specific surface area. Various electrochemical techniques such as cyclic voltammetry, galvanostatic charge-discharge, and electrochemical impedance spectroscopy have been performed in a 2 M KOH electrolyte to investigate its electrochemical performance. The synthesized ternary nanocomposite exhibits a specific capacitance of 493 Fg−1 at a current density of 1 Ag−1, with notable capacitive retention of 91.5% even after 10,000 cycles. This nontoxic technique provides a substitute pathway for the formation of graphene-based ternary nanocomposites with exceptional structural, morphological, optical, surface, and electrochemical properties. The ternary nanocomposite synthesized through this procedure displays an outstanding specific capacitance, cyclic stability, and corrosion resistance and hence the possibility of using nanocomposite as a promising electrode material can be explored for energy storage devices.

Malic acid grafted Fe3O4 nanoparticles for controlled drug delivery and efficient heating source for hyperthermia therapy

Tailoring surface features is essential for creating specific functional properties on superparamagnetic Fe3O4 nanoparticles for biomedical applications. In this regard, we explored the use of malic acid as a surface passivating agent for designing biocompatible, highly water-dispersible Fe3O4 magnetic nanocarriers (MMNCs) for high payload of anticancer drug, doxorubicin hydrochloride (DOX). The efficacious grafting of malic acid onto the surface of Fe3O4 was apparent from infrared spectroscopy, dynamic light scattering, zeta-potential and thermogravimetric measurements. XRD and TEM analyses revealed the formation of highly crystalline single-phase Fe3O4 nanoparticles. They showed good aqueous colloidal stability, pH dependent surface charge characteristics and superparamagnetic behavior at room temperature. The electrostatic conjugation of drug onto the surface of MMNCs was optimized by varying the ratio of DOX to MMNCs, and a maximum loading efficiency of 72% was achieved at their 1:10 ratio. The DOX conjugated MMNCs (DOX-MMNCs) exhibited pH dependent controlled release characteristics. These DOX-MMNCs demonstrated dose dependent cellular uptake and retained considerable toxicity of DOX towards breast cancer (MCF-7) cell line. Further, our magnetic hyperthermia studies showed excellent heating efficiency of these MMNCs within the permissible limit of field strength and frequency reported for a safe application of hyperthermia to patients. Specifically, a water-dispersible surface decorated magnetic formulation was developed for pH-responsive controlled release of chemotherapeutic drug and efficient heating source for hyperthermia therapy.

Multifunctional growth of dendritic magnetic nanocarrier for targeted drug delivery

Abstract The multifunctional dendritic magnetic nanocarriers (DMNCs) have been prepared by chemical synthesis method. XRD analysis revealed the formation of highly crystalline single-phase Fe3O4 nanoparticles. From TEM micrographs, it has been found that the DMNCs are roughly spherical in shape and average size about 10 nm. The growth of dendritic shell on Fe3O4 nanoparticles is confirmed from FTIR spectroscopy, zeta-potential, and magnetization measurements. The layer-by-layer conjugation of amino acid (glycine) onto the surface of Fe3O4 nanoparticles provide them functionalized exterior with high densities of carboxyl moiety for binding of anticancer drug, doxorubicin hydrochloride (DOX). The release study showed pH-stimulated release of DOX from drug loaded DMNC in a cell-mimicking environment. Further, they do not exhibit toxicity towards cervical (HeLa) and breast cancer (MCF-7) cell lines even after incubated with 2 mg/mL of particles for 24 h indicating their potential for biomedical applications.

In vitro cytotoxicity study of superparamagnetic iron oxide and silica nanoparticles on pneumocyte organelles

Inhalation is the main route of nanoparticles (NP) exposure during manufacturing. Although many mechanisms of toxicity have been described, the interaction of NP with relevant pneumocytes organelles is not widely understood. Considering that the physicochemical properties of NP influence their toxicological responses, the objective of this study was to evaluate whether exposure to different NP, crystalline Fe3O4 NP and amorphous SiO2 NP could alter pneumocytes organelles in alveolar epithelial cells. To achieve this goal, cell viability, ultrastructural changes, lysosomal damage, mitochondrial membrane potential (MMP), lipid droplets (LD) formation and cytokines production were evaluated by MTT, electron microscopy, lysotracker red staining, JC-1, Oil Red staining and Milliplex® assay respectively. Both NP were observed within lamellar bodies (LB), lysosomes, and cytoplasm causing morphological changes. Exposure to SiO2 NP at 6 h induced lysosomal activation, but not Fe3O4 NP. MMP decreased and LD increased at the highest concentrations after both NP exposure. Pro-inflammatory cytokines were released only after SiO2 NP exposure at 48 h. These results indicate that SiO2 NP have a greater impact than Fe3O4 NP on organelles responsible for energy, secretion, degradation and metabolism in pneumocytes leading to the development of respiratory disorders or the exacerbation of preexisting conditions. Therefore, the established biocompatibility for amorphous NP has to be reconsidered.

Immobilization of protein on Fe3O4 nanoparticles for magnetic hyperthermia application

We report a facile approach for the preparation of protein conjugated glutaric acid functionalized Fe3O4 magnetic nanoparticles (Pro-Glu-MNPs), having improved colloidal stability and heating efficacy. The Pro-Glu-MNPs were prepared by covalent conjugation of BSA protein onto the surface of glutaric acid functionalized Fe3O4 magnetic nanoparticles (Glu-MNPs) obtained through thermal decomposition. XRD and TEM analyses confirmed the formation of crystalline Fe3O4 nanoparticles of average size ~5 nm, whereas the conjugation of BSA protein to them was evident from XPS, FTIR, TGA, DLS and zeta-potential measurements. These Pro-Glu-MNPs showed good colloidal stability in different media (water, phosphate buffer saline, cell culture medium) and exhibited room temperature superparamagnetism with good magnetic field responsivity towards the external magnet. The induction heating studies revealed that the heating efficacy of these Pro-Glu-MNPs was strongly reliant on the particle concentration and their stabilizing media. In addition, they showed enhanced heating efficacy over Glu-MNPs as surface passivation by protein offers colloidal stability to them as well as prevents their aggregation under AC magnetic field. Further, Pro-Glu-MNPs are biocompatible towards normal cells and showed substantial cellular internalization in cancerous cells, suggesting their potential application in hyperthermia therapy.

Effect of OH− concentration on Fe3O4 nanoparticle morphologies supported by first principle calculation

It has been known that morphology and size could affect the properties of crystalline magnetite (Fe3O4). However, specific principle for a simple and predictable way to control them was still absent. Alkali concentration has been demonstrated to be an influential factor on the morphology changes in an ethylene glycol/diethylene glycol (EG/DEG) binary solvothermal system. In this work, crystalline Fe3O4 nanoparticles with a variety of morphologies including clusters, solid spheres, octahedron, truncated-octahedrons, tetrakaidecahedrons and truncated-cubes were prepared in a facile way. Furthermore, first principle calculation based on density functional theory was carried out to calculate the adsorption energies of OH− on different crystal planes of Fe3O4. The calculation results interpreted the crystal morphology changes accordingly, despite of the simplicity of the calculation model. The agreement between the theoretical calculation and the experimental data indicates the promising benefit of using first principle calculation to predict and design crystal morphologies in the future. On the other hand, size of the anisotropic octahedral Fe3O4 nanoparticles could be regulated from 30 nm to 115 nm by changing the volume ratio of EG/DEG with a certain OH− concentration.

Synthesis of single-walled carbon nanotubes in rich hydrogen/air flames

We explore the production of single-walled carbon nanotubes (CNTs) in a stream surrounded by rich premixed laminar H2/air flames using a feedstock containing ethanol and ferrocene. The as-produced nanomaterials were characterised by Raman spectroscopy, transmission electron microscopy, scanning electron microscopy and X-ray diffraction. A formation window of equivalence ratios of 1.00–1.20 was identified, and single-walled CNT bundles with individual CNTs of an average diameter of 1 nm were observed. The formation of CNTs was accompanied by the production of highly crystalline Fe3O4 nanoparticles of a size of 20–100 nm. The investigation of the limiting factors for the CNT synthesis was carried out systematically, assisted by numerical modelling. We conclude that the key factors affecting CNT synthesis are the surrounding flame temperatures, and the concentration of carbon available for CNT nucleation.

Application of Amorphous Nanoparticle Fe-B Magnetic Fluid in Wastewater Treatment

Amorphous magnetic particles demonstrate excellent comprehensive properties and outstanding characteristics for numerous applications. In this report, magnetic crystalline Fe3O4 and amorphous Fe-B nanoparticles were successfully synthesized and introduced to prepare water-based magnetic fluids. The Fe3O4 and Fe-B particles are homogeneous nanoparticles with an average particle size of [Formula: see text][Formula: see text]nm. The shape of Fe-B amorphous nanoparticles is regular. The saturation magnetizations of Fe-B and Fe3O4 particles are 74 emu/g and 69 emu/g. The use of crystalline Fe3O4 magnetic fluid and amorphous Fe-B magnetic fluid in advanced treatment of high concentration organic wastewater was presented. The removal rate of chemical oxygen demand by using the amorphous Fe-B magnetic fluid reached 96%, about 16% higher than that by using the Fe3O4 magnetic fluid. Moreover, compared with Fe3O4 magnetic fluid, the treatment results demonstrate that the decolorizing effect by using the amorphous Fe-B magnetic fluid was 20% higher. It has been found that the nano-size Fe-B particles in magnetic fluid with amorphous structure led to high efficiency of wastewater treatment due to the catalytic activity.

PH-Labile Magnetic Nanocarriers for Intracellular Drug Delivery to Tumor Cells.

We report the development of pH-labile ascorbic acid-coated magnetic nanocarriers (AMNCs) for effective delivery of the anticancer drug doxorubicin hydrochloride (DOX) to tumor cells. The uniqueness of this drug delivery system lies in the covalent conjugation of DOX through carbamate and hydrazone bonds, resulting in a slow and sustained drug release profile at different environmental acidities. X-ray diffraction and transmission electron microscopy analyses reveal the formation of crystalline single-phase Fe3O4 nanoparticles with an average size of 10 nm. The changes in the interfacial characteristics of the nanocarriers and the presence of organic coatings are probed by infrared spectroscopy, dynamic light scattering, zeta potential, and thermogravimetric measurements. AMNCs show high colloidal stability in aqueous and cell culture media and possess good magnetic field responsivity and protein resistance characteristics. The drug-loaded nanocarriers exhibited sustained pH-triggered release of drug molecules in acidic mediums, substantial cellular internalization, and significant toxicity toward the proliferation of mouse skin fibrosarcoma (WEHI-164), human breast cancer (MCF-7), and human lung cancer (A549) cells. However, it showed significantly lower toxicity in human normal lung (WI26VA) cells. Overall, these results suggest a pH-sensitive drug release of nanoformulations, which showed selective toxicity to tumor than normal cells.

Sol–gel–xerogel transformations in the thin layer at the salt solution–gaseous reagent interface and the synthesis of new materials with microtubular morphology

In this report, we consider the peculiarities of sol–gel–xerogel transformations, which occurs in the thin layer at the FeCl2/FeCl3 water solution and gaseous NH3 interface. A thin layer consisting of nanoparticles of Fe(OH)3 and Fe3O4 is formed as a result of interfacial reaction. Depending on the time of treatment with gaseous ammonia, it was possible to obtain either a freestanding layer with a thickness of 1 μm or microtubular structures (scrolls). Synthetic conditions, under which a large number of preferentially oriented microtubes are formed with diameters of about 10 and up to 200-μm long, were determined. The synthesized structures consisted of crystalline Fe3O4 nanoparticles with an average diameter of about 5–10 nm incorporated in an amorphous matrix. Layers and tubes were characterized by X-ray diffraction analysis, scanning and transmission electron microscopy (SEM and TEM), and X-ray photoelectron spectroscopy. The model, concerning sol–gel–xerogel transformations in the thin layer, formed after interaction at the salt solution–gaseous reagent interface, was suggested. The magnetic properties of the products were studied.

A novel electrochemical modification combined with one-step pyrolysis for preparation of sustainable thorn-like iron-based biochar composites

A novel method incorporating electrochemical (EC) modification and one-step pyrolysis is developed to prepare sustainable Fe3O4-based magnetic adsorbent (EC-Fe3O4/BC) via pyrolysis of FeCl3-pretreated corn straw-derived biochar under an electric field generated by graphite electrode. Morphological characterization revealed a uniform dispersion of rod-like crystalline Fe3O4 nanoparticles in the inner and outer structure of biochar. The EC modification also introduced more oxygen-containing functional groups, which contributed to an outstanding Pb adsorption capacity (113 mg g−1) and fast kinetics (0.054 g mg−1 h−1). Therefore, the EC modification is a simple and time-saving method to effectively fabricate magnetic biochar adsorbent for high-performance wastewater treatment.

Fabrication of magnetic iron Oxide@Graphene composites for adsorption of copper ions from aqueous solutions

Liquid-phase adsorption of Cu2+ ions onto magnetic Fe3O4@graphene oxide (GO) composites, prepared by a co-precipitation approach, has been investigated. This synthesis method is capable of depositing highly crystalline Fe3O4 nanoparticles onto GO sheets. The adsorption temperature and the weight ratio of Fe3O4 nanoparticles to GO sheets are found to be crucial factors affecting the adsorption performance. The pH value of the aqueous solution has a strong influence on the adsorption capacity of Cu2+ ions. The Langmuir, Freundlich, and Dubinin-Radushkevich (D-R) adsorption models were adopted to fit the adsorption isotherms. The deposition of magnetite enhances the equilibrium rate constant (Langmuir model) and the adsorption energy (D-R model). The analysis of thermodynamic parameters reveals that the adsorption of Cu2+ ions is a favorable and spontaneous process. However, a moderate density of magnetite onto GO substrate is essential for the design of Fe3O4@GO adsorbents for efficient removal of metal ions from an aqueous solution.

Microwave-assisted rapid synthesis of Fe3O4/poly(styrene-divinylbenzene-acrylic acid) polymeric magnetic composites and investigation of their structural and magnetic properties

We report a facile method for rapid synthesis of highly crystalline superparamagnetic Fe3O4 nanoparticles with crystallite size in the range of 25–33 nm via microwave synthesizer. The Fe3O4 stabilized with PVP was used to synthesize strong magnetized spherical polymeric magnetic composites (PMCs) in the range 0.3–1.5 µm via microwave irradiated emulsion polymerization using vinyl monomers. The influence of reaction time and the amount of reactive reagents on the structure, morphology, thermal stability and magnetic property of synthesized PMCs were examined. HR-TEM revealed the incorporation of superparamagnetic Fe3O4 nanoparticles in the cross-linked polymeric matrix of poly(styrene-divinylbenzene-acrylic acid). The synthesized Fe3O4 nanoparticles exhibit superparamagnetic behavior at 300 K with a high saturation magnetization 67.5 emu/g for MNP-3. Interestingly, the as-synthesized magnetically responsive PMCs [Fe3O4/P(St-DVB-AA)] exhibit ferromagnetic properties with enhanced saturation magnetization in the measured temperature interval of 10–350 K, which is in contrast with the superparamagnetic behavior of synthesized Fe3O4 nanoparticles. An excellent saturation magnetization 22.5 emu/g was noted for the composite PMC-10 loaded with ∼24% magnetic nanoparticles. Further, the as-synthesized Fe3O4 nanoparticles and polymer magnetic composites exhibit the charge ordering (Verwey transition) at low temperature in the range 30–41 K and 23–25 K, respectively.

Correlation between particle size/domain structure and magnetic properties of highly crystalline Fe3O4 nanoparticles

Highly crystalline single-domain magnetite Fe3O4 nanoparticles (NPs) are important, not only for fundamental understanding of magnetic behaviour, but also for their considerable potential applications in biomedicine and industry. Fe3O4 NPs with sizes of 10–300 nm were systematically investigated to reveal the fundamental relationship between the crystal domain structure and the magnetic properties. The examined Fe3O4 NPs were prepared under well-controlled crystal growth conditions using a large-scale liquid precipitation method. The crystallite size of cube-like NPs estimated from X-ray diffraction pattern increased linearly as the particle size (estimated by transmission electron microscopy) increased from 10 to 64.7 nm, which indicates that the NPs have a single-domain structure. This was further confirmed by the uniform lattice fringes. The critical size of approximately 76 nm was obtained by correlating particle size with both crystallite size and magnetic coercivity; this was reported for the first time in this study. The coercivity of cube-like Fe3O4 NPs increased to a maximum of 190 Oe at the critical size, which suggests strong exchange interactions during spin alignment. Compared with cube-like NPs, sphere-like NPs have lower magnetic coercivity and remanence values, which is caused by the different orientations of their polycrystalline structure.

Synthesis of amorphous Fe2O3/RGO composite and its application to photoinduced hydrogen evolution

A new composite with amorphous Fe2O3 ultrafine particles and distinctively reduced graphene oxide partially (Am-Fe2O3/RGO) was synthesized by photoreaction of graphene oxide and iron pentacarbonyl (Fe(CO)5) at an ambient temperature. The composite was characterized by SEM, TEM, XRD, IR, XPS, and Mössbauer spectroscopies. They demonstrate that Fe2O3 in the composite is populated in an amorphous state with ultrafine particle sizes, being distributed stably, uniformly, and widely on/in the RGO. Thus produced Am-Fe2O3 did not show any coagulation in acidic media at pH 2 and in the solid state at 80 °C for more than two months, although they converted to crystalline Fe3O4 nanoparticles under electron beam irradiation. They also showed conversion to crystalline Fe under visible light irradiation with the presence of reducing agents. The Am-Fe2O3/RGO composite was applied to photochemical reduction of H+ to form H2 as a heterogeneous catalyst together with fluorescein as the photosensitizer and triethylamine as the electron donor. We observed, for the first time, the evolution of H2 using the amorphous Fe2O3 composite, although the catalytic reaction rate is still not high enough (TOF ca. 2.5/h, TON more than 320).

Preparation and Characterization of a Tumor-Targeting Dual-Image System Based on Iron Oxide Nanoparticles Functionalized with Folic Acid and Rhodamine

Cancer is one of the diseases with most deaths worldwide, around 8.2 million annually. For this reason, several treatments and diagnostic tools have been investigated and developed over the past decades. Among them, a dual-image system has been developed to achieve and enhance the detection of cancer, which has not been done with systems currently available. The present study describes the preparation of a dual-image targeting system composed of magnetic iron oxide nanoparticles functionalized with folic acid and rhodamine; nanoparticles synthesis was achieved by a coprecipitation method; the functionalization was carried out by a carbodiimide with folic acid and/or the rhodamine isothiocyanate; conjugates were characterized by spectrometric techniques; toxicity was measured by cell proliferation assay on HeLa cells using progressive concentrations of functionalized nanoparticles. Cellular uptake assay was carried out by competitive assay on HeLa cells. Iron oxide magnetite nanoparticles, modified with folic acid and rhodamine, were successfully synthetized with a particle size lower than 20 nm (TEM), EDS, HRTEM, and XDR showed highly crystalline Fe3O4 nanoparticles. Folic acid and rhodamine were conjugated with high efficiency. A significant selectivity and uptake, facilitated by surface modification of iron oxide nanoparticles with folic acid, were demonstrated. The multifunctional system showed suitable physicochemical and biological properties for cell targeting through folate receptors.

Bioinspired 2D-Carbon Flakes and Fe3O4 Nanoparticles Composite for Arsenite Removal.

Development of carbon-based materials has received tremendous attention owing to their multifunctional properties. Biomaterials often serve as an inspiration for the preparation of new carbon materials. Herein, we present a facile synthesis of a new bioinspired graphene oxide-like 2D-carbon flake (CF) using a natural resource, waste onion sheathing (Allium cepa). The 2D-CF was further decorated with crystalline Fe3O4 nanoparticles for applications. Superparamagnetic Fe3O4 nanoparticles (7 nm) were well-dispersed on the surface of the 2D-CF, which was characterized by X-ray diffractometry, X-ray photoelectron spectroscopy, Raman spectrometry, and transmission electron microscopy. Batch As(III) adsorption experiments showed that aqueous arsenic ions strongly adsorbed to the Fe3O4@2D-CF composite. The adsorption capacity of the Fe3O4@2D-CF composite for As(III) was 57.47 mg g(-1). The synergetic effect of both graphene oxide-like 2D-CF and Fe3O4 nanoparticles aided in excellent As(III) adsorption. An As(III) ion adsorption kinetics study showed that adsorption was very fast at the initial stage, and equilibrium was reached within 60 min following a pseudo-second-order rate model. Owing to the excellent superparamagnetic properties (52.6 emu g(-1)), the Fe3O4@2D-CF composite exhibited superb reusability with the shortest recovery time (28 s) among reported materials. This study indicated that Fe3O4@2D-CF composites can be used for practical applications as a global economic material for future generations.

Graphene anchored with Fe3O4 nanoparticles as anode for enhanced Li-ion storage

Magnetite (Fe3O4) nanoparticles anchored graphene nanocomposites with different weight ratios of Fe3O4 and graphene nanosheets (GNSs) were prepared using hydrothermal method. The X-ray diffraction (XRD) pattern of the prepared nanocomposite reveals the presence of face centered cubic hexagonal crystalline Fe3O4 nanoparticles. Raman spectroscopic studies of the nanocomposites confirm the co-existence of Fe3O4 and graphene. The electron microscopy images of the nanocomposites revealed the formation of homogeneous nanocrystalline Fe3O4 particles on GNS surface. Among the three studied weight ratios (28:72, 40:60 and 60:40), the charge–discharge profile of the nanocomposite electrodes indicates that nanocomposite with 40:60 wt% of Fe3O4 and GNS as high capacity (930 mAh g−1) electrode for the lithium-ion (Li-ion) storage. And, the Li-ion storage capacity of the above nanocomposite is much higher than the pure GNS and Fe3O4 nanoparticle electrodes. The charge–discharge cycling study indicates that the Fe3O4/GNS (40:60) nanocomposite electrode has very high reversible capacity of 675 mAh g−1 with columbic efficiency of 97% after 50 cycles. The rate performance of the Fe3O4/GNS (40:60) nanocomposite electrode shows high reversible capacities at high rates due to the high conductive GNS support. The cyclic voltammetry experiment reveals the irreversible and reversible Li-ion storage in Fe3O4/GNS during the first and subsequent cycles.

Water-soluble, mesoporous Fe3O4: Synthesis, characterization, and properties

Water-soluble, mesoporous Fe3O4 nanopowder is successfully prepared by one-step thermal decomposition of an iron-urea complex ([Fe(NH2CONH2)6](NO3)3) in triethylene glycol (TEG). The formation of Fe3O4 is confirmed from X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and selected area electron diffraction (SAED) measurements. The morphological and structural properties of the Fe3O4 nanopowder are characterized by transmission electron microscopy (TEM), nitrogen adsorption–desorption, and thermogravimetric analysis (TGA). Monodisperse, nearly spherical and highly crystalline Fe3O4 nanoparticles are obtained by this method. The Fe3O4 nanopowder is well dispersed in water and ethanol with a mesoporous structure, average pore size of 3.6nm, and Brunauner–Emmett–Teller (BET) surface area of 122m2/g. The room temperature magnetization hysteresis curve exhibits barely measurable values for coercivity and remanence, suggesting that the Fe3O4 nanopowder possesses superparamagnetic characteristics.