Dispersion Of Fe3O4 Research Articles

Superhydrophobic Magnetic-Driven Reactor for Microliter Droplet Reaction Interface Visualization.

The development of an efficient, convenient, and cost-effective droplet-driven reactor to observe the reaction microphenomenon is crucial for investigating the chemical reaction and synthesis mechanisms. Herein, an efficient and economical strategy by combining micro-extrusion compression molding (μ-ECM) and surface modification was proposed to fabricate a superhydrophobic magnetic-driven reactor (SMDR) for microliter droplet reaction interface visualization. The wall-like array microstructures with favorable geometric uniformity and the nano-SiO2 coating with uniform dispersion endow the SMDR with robust superhydrophobicity, featuring a contact angle of 159.5 ± 1.0° and a rolling angle of 5.1 ± 0.5°. Due to the uniform dispersion of Fe3O4 in thermoplastic elastomer (TPE), the SMDR possesses sensitive magnetic responsiveness, which can drive droplets to move rapidly, continuously, and losslessly on horizontal and inclined planes, even on a plane with an inclination angle of up to 15°. Interestingly, the SMDR was successfully used to visualize the interface formation and evolution of three simple mixing/reaction processes, which provides a convenient, efficient, and low-cost method for the study of the droplet mixing reaction process and interface visualization.

Highly selective capture of Hg(II) utilizing a MXene-based magnetic cenosphere: Balance on redox sites and magnetism

Hg(II), as a hazardous water pollutant, is attracting increasing attention due to its severe ecological and biological toxicity. Herein, a magnetic composite MXene/Fe3O4/FAC for aqueous Hg(II) uptake was prepared. It appeared fast adsorption kinetics (∼30 min of adsorption equilibrium time), high Hg capacity (924.34 mg/g), broad working pH range (pH=4–12), and high selectivity. Besides, the implanted Fe3O4 empowered the composite with good recycling and reusing characteristics, effectively preventing the release of nanomaterials into the environment. Multiple adsorption models and characterizations revealed the Hg(II) adsorption behaviors and mechanisms and the impact of Fe3O4 on Hg(II) adsorption onto MXene. Specifically, Hg(II) reductive adsorption aroused by the low-valence Ti species (abbreviated as Ti*) is the foremost mode of MXene. With the increasing of Fe3O4 (especially trivalent Fe), Ti* tends to be oxidized and covered by Fe3O4, and less Ti* can be used for Hg(II) reductive adsorption, leading to slower adsorption kinetics and lower adsorption capacity. The introduced inert carrier FAC favors the good dispersion of Fe3O4 and MXene to alleviate the oxidation of MXene, achieving the high utilization of MXene materials. The new insight into the interaction between MXene and Fe3O4 can beneficially guide the synthesis of Hg(II) magnetic adsorbents and MXene-based functional materials.

Impact of composite modes on electrochemical properties of Fe3O4/CNTs for Li-ion storage

Transition metal oxides (TMOs, e.g., Fe3O4) with high theoretical capacity hold tremendous potential in the field of lithium-ion batteries. Unfortunately, TMOs still suffer from the significant volume expansion and low intrinsic electronic conductivity, which results in irreversible structural collapse, uncontrollable particle aggregation, and sluggish electrochemical reaction kinetics, leading to bad rate performance and cycling stability. Combining TMOs with carbon has become the most effective approach to address the aforementioned issues. However, the interaction mechanism between TMOs and carbon influencing on electrochemical properties has not yet been thoroughly explored and widely recognized. Herein, we proposed a simple and controllable method to synthesize a series of Fe3O4 composites, i.e., Fe3O4 combined with carbon nanotubes (CNTs), via different composite modes, i.e., mixing, embedding and encapsulation. The mixing one exhibits the highest initial capacity but the poorest cycling stability. Encapsulating Fe3O4 into the cavities of CNTs effectively mitigates the volume expansion of Fe3O4, thereby achieving satisfactory rate performance. The embedded composite produces ultrafine Fe3O4 particles within the walls of CNTs, which not only enhances the dispersion of Fe3O4, but also provides an efficient pathway for electronic transport. The electrode based on the embedded composite mode demonstrates excellent cycling stability and an acceptable reversible capacity of 683.7 mAh/g at 1 A/g after 100 cycles. The relationship between structure and electrochemical properties of Fe3O4/CNTs composites is elaborated, which provides universal aspect for future design of high-energy–density lithium-ion batteries.

The Development of Fe3O4-Monolithic Resorcinol-Formaldehyde Carbon Xerogels Using Ultrasonic-Assisted Synthesis for Arsenic Removal of Drinking Water.

Inorganic arsenic in drinking water from groundwater sources is one of the potential causes of arsenic-contaminated environments, and it is highly toxic to human health even at low concentrations. The purpose of this study was to develop a magnetic adsorbent capable of removing arsenic from water. Fe3O4-monolithic resorcinol-formaldehyde carbon xerogels are a type of porous material that forms when resorcinol and formaldehyde (RF) react to form a polymer network, which is then cross-linked with magnetite. Sonication-assisted direct and indirect methods were investigated for loading Fe3O4 and achieving optimal mixing and dispersion of Fe3O4 in the RF solution. Variations of the molar ratios of the catalyst (R/C = 50, 100, 150, and 200), water (R/W = 0.04 and 0.05), and Fe3O4 (M/R = 0.01, 0.03, 0.05, 0.1, 0.15, and 0.2), and thermal treatment were applied to evaluate their textural properties and adsorption capacities. Magnetic carbon xerogel monoliths (MXRF600) using indirect sonication were pyrolyzed at 600 °C for 6 h with a nitrogen gas flow in the tube furnace. Nanoporous carbon xerogels with a high surface area (292 m2/g) and magnetic properties were obtained. The maximum monolayer adsorption capacity of As(III) and As(V) was 694.3 µg/g and 1720.3 µg/g, respectively. The incorporation of magnetite in the xerogel structure was physical, without participation in the polycondensation reaction, as confirmed by XRD, FTIR, and SEM analysis. Therefore, Fe3O4-monolithic resorcinol-formaldehyde carbon xerogels were developed as a potential adsorbent for the effective removal of arsenic with low and high ranges of As(III) and As(V) concentrations from groundwater.

Preparation of magnetic nitrogen-doped porous carbon by incomplete combustion with solvothermal synthesis for magnetic solid-phase extraction of benzoylurea insecticides from environmental water

In this work, magnetic nitrogen-doped porous carbon (Fe3O4@N-PC) was prepared via incomplete combustion coupled with solvothermal synthesis for extraction of four benzoylureas (BUs) insecticides. Among them, nitrogen-doped porous carbon was produced through incomplete combustion of filter paper loaded with mixture formed by Zn(NO3)2·6H2O and polyethyleneimine solution, and magnetic nanoparticles were further introduced by solvothermal method. Compared with magnetic porous carbon (Fe3O4@PC), the surface hydrophilicity of Fe3O4@N-PC was improved by virtue of the doping of nitrogen atoms, and the dispersion of Fe3O4 was more uniform, which greatly exposed the adsorption site. The characterization of Fe3O4@N-PC were carried out by TEM, XRD, elemental analysis, XPS, BET and magnetic hysteresis curve. Besides, Fe3O4@N-PC was successfully used as magnetic solid-phase extraction (MSPE) adsorbent, which showed excellent enrichment factors and extraction recoveries toward polar BUs insecticides due to the polar surface and introduction of Lewis-basic nitrogen. The optimum amount of Fe3O4@N-PC adsorbent, extraction time, pH value, desorption solvent, desorption time and PEI concentration for BUs insecticides extraction were determined to be 3 mg, 10 min, 8, acetone/acetic acid (19:1, V/V), 6 min and 60 g L−1, respectively. Under this experimental condition, the enrichment factors ranged from 182 to 192 with good intra- and inter-day relative standard deviations (RSDs). The calibration lines were linear over the concentration in the range of 1–800 μg L−1, the limit of detection (LOD) and limit of quantification (LOQ) were 0.3 μg L−1 as well as 1 μg L−1, respectively. The recoveries for spiked sample ranged from 90.7 to 107.3% in spiked Yellow River water with the RSDs less than 7.0%. The results showed that the established MSPE strategy based on Fe3O4@N-PC could be used for the detection of trace BUs in complex samples.

Ball milling Fe3O4@biochar cathode coupling persulfate for the removal of sulfadiazine from water: Effectiveness and mechanisms

This study used biochar as the substrate of the electrodes, and a simple synthetic process (ball milling) was adopted to prepare the Fe3O4 @biochar cathode enhanced coupled system of electrochemistry-potassium persulfate to achieve the efficient removal of sulfadiazine. Studies showed that the cracking temperature of biochar and the iron-to-carbon mass ratio determined the catalytic performance of cathodes. In addition, ball milling increased the surface functional groups of biochar and promoted the dispersion of Fe3O4 on biochar, leading to increased active sites on the Fe3O4 @biochar cathode surface. It was found that SDZ and TOC removal rates reached 95.3% and 86.9% in the coupled system of electrochemical-persulfate with SDZ concentration of 10 mg/L, initial pH0 of 7, PDS concentration of 4 mM, current density of 30 mA/cm2, and electrode plate spacing of 4 cm. Also, this system showed excellent removal of sulfadiazine in actual water bodies. The quenching experiments and electron paramagnetic resonance spectra revealed that free radicals and non-radicals were involved in removing sulfadiazine, with free radicals (SO4•−) being the dominant pathway. Four main degradation pathways were proposed based on the intermediates of sulfadiazine. In conclusion, Fe3O4 @biochar cathode enhanced coupled system of electrochemical-persulfate could be regarded as an efficient cleaning technology to provide a method for the removal of intractable organic pollutants.

Synthesis and characterization of magnetic polymeric nanocomposites for pH-sensitive controlled release of methotrexate

As one of the well-known anticancer drugs, methotrexate (MTX) has been limited in clinical application due to its side effects on normal tissues. This study focused on the one-step hydrothermal synthesis and in vitro evaluation of Fe3O4/RGO-PEI as MTX carriers for targeted anticancer therapy. In which, the Fe3O4 provided magnetic response properties; RGO acted as a stage for Fe3O4 loading and improved the dispersion of Fe3O4; polyethylenimine (PEI) was used as a surface modifier and a storehouse for MTX. The prepared Fe3O4/RGO-PEI nanocomposites exhibited a suitable size, good stability and magnetic responsibility. And the MTX loading content and loading efficiency were calculated to be 26.6% and 90.5%, respectively. What’s more, due to the diffusion and dissolution of PEI, the Fe3O4/RGO-PEI-MTX exhibited excellent pH-sensitivity, the values of MTX release rate (%) within 48 h at pH 5.8 and 4.0 were 64.3% and 87.4%, respectively. Furthermore, MTT assays in cancer cells (HepG2) and normal cells (HUVEC) demonstrated that Fe3O4/RGO-PEI-MTX exhibited high anticancer activity while low toxicity to normal cells, and also the Fe3O4/RGO-PEI composites were practically non-toxic. Thus, our results revealed that Fe3O4/RGO-PEI-MTX would be a competitive candidate for targeted delivery and controlled release of MTX.

Heat transfer enhancement in stagnation point flow of ferro-copper oxide/water hybrid nanofluid: A special case study

This present work is to investigate the behavior of Fe3O4−CuO/H2O hybrid-type nanofluid flow toward a magnetic field for enhancing the thermal transfer by horizontal stretchable surface. In the base fluid different tiny-sized nanoparticles collides and enhanced the heat transformation in the absence of magnetic field. Here the combinations of Fe3O4−CuO/H2O as hybrid nanofluids and CuO/H2O as nanofluid are implemented. The Ferro and Copper oxide are dispersed in water base fluid. Such Ferro nanomaterials are more fruitful in production technology, protein absorption, catalysis, medical technology and environment. The implementation of Fe3O4 NPs in medical science mainly involves targeted drug/gene delivery, biosensor, magnetic resonance imaging (MRI), contrast improvement and hyperthermia, biophotonics, detection of cancer cells, diagnosis and magnetic field-assisted radiotherapy and tissue engineering. Copper oxide used as a catalyst for increasing the rate of combustion in rocket propellant. It may significantly increase the homogenous propellant burning rate, lower the pressure index, and boost the effectiveness of the AP composite propellant as a catalyst. In additional, the governing coupled dimensional equations are reduced into the ordinary once with associated the suitable similarities. The resultant dimension-less expressions are programmed in the computational MATLAB software via bvp4c solver with shooting scheme. The important outcomes of this investigation are the behavior of numerous good parameters including stretching ratio parameterA∗, magnetic parameterβ, volumetric frictions for nanoparticlesφ, suction/injection parameterfw and thermal radiation parameterRd. The physical behavior of above discussed sundry parameters is described through figures. The dispersion of Fe3O4 and CuO in water-based fluid significantly improved the phenomenon of heat transfer. Results found that the velocity field is escalates when the stretching ratio parameter is enhanced. Furthermore, larger values of the suction/injection parameter causes a reduction in velocity profile for A<1 and A>1. The induced magnetic field is improved with larger estimations of the nanoparticle fraction. Thermal field is escalates by growing thermal radiation parameter and Eckert number. It is further observed that temperature profile is reduces by increasing stretching ratio parameter. From the analysis we noted that skin friction is raises via larger estimations of magnetic parameter.

Facile utilization of magnetic MnO2@Fe3O4@sulfonated carbon sphere for selective removal of hazardous Pb(II) ion with an excellent capacity: Adsorption behavior/isotherm/kinetic/thermodynamic studies

Magnetic MnO2@Fe3O4@sulfonated carbon sphere (CS-S-Fe-Mn) was used as a magnetic adsorbent for selective removal of Pb2+ ion from aqueous solution via co-creation between electrostatic force along with co-ordinate covalent bond. The CS-S-Fe-Mn was prepared via hydrothermal carbonization/sulfonation and followed by facile precipitation processes. The physical and chemical properties of CS-S-Fe-Mn and other adsorbents were characterized by BET-BJH, XRD, FTIR, VSM, SEM-EDS, pHpzc and Boehm titration techniques. As observed, the CS-S-Fe-Mn exhibited a spherical (petal-like walls) shape with a good dispersion of Fe3O4 and MnO2 particles, which had surface area of 146 m2/g, total acidity-basicity of 7.87 mmol/g and negative surface charge (pH < pHpzc). The paramagnetic properties of CS-S-Fe-Mn was well found with a saturation magnetization value of 21.8 emu/g, resulting in facile separation from water system using an external magnetic field. A maximum adsorption capacity (qmax) of Pb2+ over CS-S-Fe-Mn was 147.76 mg/g which had higher performance than previous references, resulting from synergetic effects of oxygen containing functional groups such as -CO/C-O, -COOH and -SO3H as well as MnO2. Moreover, the adsorption behaviors of Pb2+ onto CS-S-Fe-Mn were in good agreement with rapid monolayer-physisorption (E = 2.93 kJ/mol)/spontaneous-endothermic (ΔH = 49.12 kJ/mol) nature processes as well as intra-particle diffusion via two step mechanisms, supporting by isotherm, kinetic, thermodynamic and Weber-Morris models. This research provided a handy strategy for Pb2+ removal with high adsorption capacity from environmental wastewater.

Synergistically enhanced heterogeneous activation of persulfate for aqueous carbamazepine degradation using Fe3O4@SBA-15

The exploration of low-cost, high-performance and stable catalytic materials for sulfate radical-based advanced oxidation processes (SR-AOPs) is of great importance. This study presents Fe3O4-wrapped SBA-15 mesoporous silica catalyst (Fe3O4@SBA-15) for persulfate (PS) activation. The Fe3O4@SBA-15 with an Fe3O4 to SBA-15 weight ratio of 3:1 exhibited an impressive carbamazepine (CBZ) removal efficiency of ~100% after 30 min of SR-AOP at an initial pH of 3.0, a temperature of 25 °C, an initial PS concentration of 300 mg L−1 and a catalyst concentration of 0.50 g L−1. The primary oxidizing species produced in the system were identified as SO4− and HO by electron paramagnetic resonance spectra and radical quenching experiments. Benefiting from the synergetic effects of improved Fe3O4 dispersion and enhanced adsorption of CBZ and PS by SBA-15, the as-obtained heterogeneous Fe3O4@SBA-15 catalysts offer large numbers of active sites for free radical generation and high surface concentrations of CBZ and PS for SR-AOPs, as verified by physicochemical characterization and Langmuir−Hinshelwood model analysis. In addition, the activity of Fe3O4@SBA-15 was maintained throughout six successive cycling tests. Various inorganic anions, including Cl−, NO3−, HCO3−, and CO32−, as well as organic material in natural water, exert a negative impact on the Fe3O4@SBA-15 catalyzed SR-AOPs and deserve special attention.

Fabrication of high-performance magnetic elastomers by using natural polymer as auxiliary dispersant of Fe3O4 nanoparticles

Achieving fillers well-distributed in the polymeric matrix via a green and eco-friendly method is critical for composites preparation to gain considerable comprehensive properties. In this work, we describe Fe3O4-based magnetic elastomer composites with superior mechanical, thermal and magnetic properties via a latex film-forming approach by using carboxylic styrene butadiene rubber (XSBR) as rubber matrix and carboxymethyl chitosan (CMCS) as a dispersant for Fe3O4. It was found that CMCS promoted the dispersion of Fe3O4 remarkably and improved the interfacial compatibility between Fe3O4 and XSBR matrix. Simultaneously, the XSBR/CMCS/Fe3O4 composite with 25 wt% Fe3O4 displayed a higher tensile strength was about 2.5 times of the neat XSBR. And the saturation magnetization of the XSBR/CMCS/Fe3O4 composite was about 1.2 times that of XSBR/Fe3O4 at the same filler content. Therefore, this report provided a new solution to uniformly disperse Fe3O4 in rubber composites by latex film-forming method without any dispersion guarantee measures.

Preparation of Fe3O4–HNTs Hybrid Material and Its Effect on Epoxy Coating Properties

The halloysite-iron oxide (Fe3O4–HNTs) hybrid material is prepared using a halloysite nanotube as precursor, and the Fe3O4 is immobilized on the halloysite with subsequent modification using 3-aminopropyltriethoxysilane. The influence of pH, urea hydrolysis, and the concentration of ferric chloride, polyvinyl alcohol on the synthesis of Fe3O4–HNTs hybrid materials were investigated. FT-IR was used to understand the modification of surface functionality, while the surface morphology and surface heteroatom were investigated through SEM and XPS, respectively. The phase purity of the hybrid material was studied using XRD pattern. The investigation demonstrated that the dispersion of Fe3O4–HNTs composite in epoxy resin is better than HNTs, and a significance improvement in corrosion resistance of epoxy coatings (EP) was observed. Moreover, an attempt was made to understand the mechanism of Fe3O4–HNTs/epoxy coating.

Facile preparation of lightweight PE/PVDF/Fe3O4/CNTs nanocomposite foams with high conductivity for efficient electromagnetic interference shielding

Light-weight Polyethylene/Poly(vinylidene fluoride)/Fe3O4/Carbon nanotubes (PE/PVDF/Fe3O4/CNTs) nanocomposite foams with efficient electromagnetic interference (EMI) shielding performance were prepared using green processing methods of melt blending and supercritical CO2 foaming. The microwave- absorbing ability of the PE/PVDF/Fe3O4/CNTs nanocomposite foams were significantly improved. Moreover, due to the selective dispersion of Fe3O4 and CNTs in the PVDF and PE matrix, respectively, CNTs directionally arranged in the cell wall during the foaming, leading to a high electric conductivity to improve the electromagnetic interference shielding effectiveness (EMI SE) through dielectric loss and polarization loss. The produced PE/PVDF/Fe3O4-10CNTs foam with a density of 0.9 g/cm3 and a thickness of 2.6 mm, exhibited a higher electrical conductivity of 0.25 S/cm. The outstanding total EMI SE of 26 dB (the corresponding specific EMI SE was 110 dB cm2/g), measured across the Ku-band frequency region, was obtained. This forming strategy has potential industrial application and large-scale EMI shielding materials producing guidance.

Preparation of Fe3O4/PVP magnetic nanofibers via in situ method with electrospinning

Ferroferric oxide (Fe3O4) magnetic nanoparticles are easily agglomerated due to their large specific surface area, and cannot be uniformly dispersed in polymer fiber matrix fabricated from electrospinning solution. In order to obtain uniform dispersion of Fe3O4 in composite nanofibers, a new method is used by mixing organic precursor of ferroferric oxide iron acetylacetonate (Fe (acac)3) and organic polymer polyvinylpyrrolidone (PVP), then subjected nanofibers through electrospinning and formed ferric oxide/polyvinylpyrrolidone (Fe3O4/PVP) fibers via in-situ calcination at low temperature. The morphology of the fibers and the dispersion of Fe3O4 particles in the fibers were characterized by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The crystallization of the magnetic fibers was characterized by X-ray diffraction (XRD). The vibrating sample magnetometer (VSM) was used. The magnetic measurement of the fiber shows that the magnetic nanofibers have better superparamagnetism, which are expected to be used as a drug-loaded magnetic cloth in the field of biomedicine.

Thin film flow of the water‐based carbon nanotubes hybrid nanofluid under the magnetic effects

AbstractIn this article, the effects of magnetic field versus the thin liquid film water‐based ferrum oxide (Fe3O4) and carbon nanotubes (CNTs) nanofluids have been studied through stretching cylinder. The iron oxide and CNTs (single‐wall [SWCNTs] or multi‐wall [MWCNTs]) have been used as nanoparticles in carrier fluid water (H2O). To the flow field, magnetic effects are applied vertically. The modeled system of partial differential equations are transformed to nonlinear ordinary differential equations by selecting variables. The analytic solution has been obtained through homotopy analysis method. The obtained results are further compared with the numerical ND‐solve method. The embedded constraints impacts are focused on pressure distribution, velocity profile, heat transfer, Nusselt number, and Skin friction through graphical illustration and tables. The dispersion of Fe3O4 and CNTs in base fluid significantly enhanced the mechanism of heat transfer. Moreover, from the results, it has been observed that the MWCNTs have a greater impact on heat transfer, velocity, and pressure profile.

Analysis of Spectroscopic, Optical and Magnetic Behaviour of PVDF/PMMA Blend Embedded by Magnetite (Fe&amp;lt;sub&amp;gt;3&amp;lt;/sub&amp;gt;O&amp;lt;sub&amp;gt;4&amp;lt;/sub&amp;gt;) Nanoparticles

In the present work, magnetite (Fe3O4) nanoparticles have been prepared by a simple chemical method. Polymer nanocomposites based on the blend between poly vinylamine fluoride (PVDF) and (methyl methacrylate) (PMMA) doped with different concentrations of Fe3O4 nanoparticles have been prepared. The structural, optical, and magnetization properties of the nanocomposite samples were studied using suitable techniques. The X-ray study reflected that the cubic spinal structure of pure Fe3O4 crystal. No small peaks or ripples were found in the X-ray spectra, conforming to good dispersion of Fe3O4 within PVDF/PMMA matrices. The FT-IR analysis demonstrated the miscibility between the PVDF and PMMA blend with the interaction between the polymer blend and Fe3O4. The values of the band gap from UV-Vis study were decreased up to 4.21 eV, 3.01 eV for direct and indirect measurements, respectively. The magnetization was measured as a function of the applied magnetic field in the range of −2000 - 2000 Oersted. The curves of the magnetization indicated a paramagnetic behavior of pure Fe3O4 nanoparticles and PVDF/PMMA-Fe3O4 nanocomposites. The values of saturation magnetization for pure Fe3O4 are nearly 75 emu/g, exhibiting a paramagnetic behavior, and it is decreased with the increase of Fe3O4 content.

Deliberate Modification of Fe3O4 Anode Surface Chemistry: Impact on Electrochemistry.

Fe3O4 nanoparticles (NPs) with an average size of 8-10 nm have been successfully functionalized with various surface-treatment agents to serve as model systems for probing surface chemistry-dependent electrochemistry of the resulting electrodes. The surface-treatment agents used for the functionalization of Fe3O4 anode materials were systematically varied to include aromatic or aliphatic structures: 4-mercaptobenzoic acid, benzoic acid (BA), 3-mercaptopropionic acid, and propionic acid (PA). Both structural and electrochemical characterizations have been used to systematically correlate the electrode functionality with the corresponding surface chemistry. Surface treatment with ligands led to better Fe3O4 dispersion, especially with the aromatic ligands. Electrochemistry was impacted where the PA- and BA-treated Fe3O4 systems without the -SH group demonstrated a higher rate capability than their thiol-containing counterparts and the pristine Fe3O4. Specifically, the PA system delivered the highest capacity and cycling stability among all samples tested. Notably, the aromatic BA system outperformed the aliphatic PA counterpart during extended cycling under high current density, due to the improved charge transfer and ion transport kinetics as well as better dispersion of Fe3O4 NPs, induced by the conjugated system. Our surface engineering of the Fe3O4 electrode presented herein, highlights the importance of modifying the structure and chemistry of surface-treatment agents as a plausible means of enhancing the interfacial charge transfer within metal oxide composite electrodes without hampering the resulting tap density of the resulting electrode.

Preparation of magnetic nanocomposite materials based on chitosan/Fe3O4

Magnetic nanocomposite materials based on chitosan/ Fe3O4 were prepared by two different methods. The magnetic iron oxide nanoparticles were synthesized by co-precipitation method of solution containing Fe2+ and Fe3+ ions in NH4OH solution. The reaction temperature was kept at 70 °C for 2 hours under nitrogen atmosphere. The dispersion of Fe3O4 was subsequently dropped in chitosan solution 1 % w/v and stirred for one hour to afford magnetic nanocomposite (CS-ex). The magnetic nanocomposite was also synthesized by simple, one-pot in-situ co-precipitation method (CS-in). In this procedure, the ferrous and ferric salt were dissolved directly in chitosan solution and followed by the co-precipitation in NH4OH solution at 70 °C in nitrogen atmosphere. The samples were collected by a magnet and washed with deionized water and dried in vacuum at 50 °C. The results showed that the magnetic nanocomposite synthesized by in-situ coprecipitation exhibited the advantages in comparison with the CS-ex. CS-in contained 41 % of chitosan and had the nanosized scale of 11– 15 nm, saturation magnetization of 41,82 emu/g and was thermally stable than CS-ex.

Enhanced electromagnetic interference shielding of carbon fiber/cement composites by adding ferroferric oxide nanoparticles

Ferroferric oxide (Fe3O4) nanoparticles were introduced into carbon fiber (CF)/cement composites to enhance the electromagnetic interference (EMI) shielding effectiveness (SE) in X-band (8.2–12.4GHz). The spherical Fe3O4 nanoparticles were synthesized through solvothermal method, whose average diameter was about 30–50nm. It was observed that incorporation of Fe3O4 nanoparticles (5wt%) along with 0.4wt% CF in the cement matrix led to a shielding effectiveness of 29.8dB, which had 34.4% increase than that of CF/cement composite. The excellent EMI shielding property was attributed to the synergistic effect between CF and Fe3O4 nanoparticles. SEM revealed the homogeneous dispersion of Fe3O4 and CF in the cement matrix. The CF/Fe3O4/cement composite is believed to be a promising material for high EMI shielding.

Dispersion of Nanocrystalline Fe3O4 within Composite Electrodes: Insights on Battery-Related Electrochemistry.

Aggregation of nanosized materials in composite lithium-ion-battery electrodes can be a significant factor influencing electrochemical behavior. In this study, aggregation was controlled in magnetite, Fe3O4, composite electrodes via oleic acid capping and subsequent dispersion in a carbon black matrix. A heat treatment process was effective in the removal of the oleic acid capping agent while preserving a high degree of Fe3O4 dispersion. Electrochemical testing showed that Fe3O4 dispersion is initially beneficial in delivering a higher functional capacity, in agreement with continuum model simulations. However, increased capacity fade upon extended cycling was observed for the dispersed Fe3O4 composites relative to the aggregated Fe3O4 composites. X-ray absorption spectroscopy measurements of electrodes post cycling indicated that the dispersed Fe3O4 electrodes are more oxidized in the discharged state, consistent with reduced reversibility compared with the aggregated sample. Higher charge-transfer resistance for the dispersed sample after cycling suggests increased surface-film formation on the dispersed, high-surface-area nanocrystalline Fe3O4 compared to the aggregated materials. This study provides insight into the specific effects of aggregation on electrochemistry through a multiscale view of mechanisms for magnetite composite electrodes.