Fe3O4 Nanocomposites Research Articles

Graphene oxide: Fe2O3 nanocomposite: synthesis, properties, and applications

Graphene oxide: Fe2O3 nanocomposite: synthesis, properties, and applications

An Alternating Magnetic Field-Controlled Drug Delivery System Based on 4,4′-Azobis (4-cyanovaleric Acid)-Functioned Fe3O4@Chitosan Nanoparticles

Herein, we designed chitosan-coated Fe3O4 nanocomposites for the control release of drugs by an alternating magnetic field (AMF). The chitosan-coated Fe3O4 nanoparticles (Fe3O4@CS) were prepared by a alkaline co-precipitation method, and then, the model drug toluidine blue (TB) was covalently grafted onto the surface of the nanocomposite by a two-step amide reaction with the thermosensitive molecule 4,4'-azobis (4-cyanovaleric acid) (ACVA) as the linker group. The prepared nanocomposites were superparamagnetic and showed high magnetization saturation (about 54.0 emu g-1). In vitro hydrothermal release studies showed that most parts of the TB would be effectively enclosed within the nanocarriers at lower ambient temperatures (23 or 37 °C) due to the molecular bonding of ACVA. The results of kinetic fitting of hydrothermal release data showed that TB released from nanoparticles followed first-order kinetics (R2 > 0.99) and the Korsemeyer-Peppas model (R2 > 0.99, n < 0.5). Most importantly, a single magnetron release experiment demonstrated an approximately linear relationship between the cumulative release of the drug and the duration of action of AMF (R2 = 0.9712). Moreover, the increase in the cumulative release of the drug can be controlled by controlling the switch of the AMF generation device. Therefore, the ACVA-modified Fe3O4@CS nanocarrier designed in this study is a promising model for drug delivery that enables the control of drug release dose by AMF.

Synthesis and characterization of Se doped Fe3O4 nanoparticles for catalytic and biological properties

In this study, Se-doped Fe3O4 with antibacterial properties was synthesized using by a coprecipitation method. The chemistry and morphology of the Se doped Fe3O4 nanocomposite were characterized by energy-dispersive X-ray spectroscopy, field-emission scanning electron microscopy, X-ray diffraction, vibrating sample magnetometry, and Brunauer–Emmett–Teller spectroscopy. The antibacterial activity of the Fe3O4/Se nanocomposite was examined against G+ (Gram-positive) and G− (Gram-negative) bacteria, in the order Staphylococcusaureus, Staphylococcussaprophyticus, Pseudomonasaeruginosa, Klebsiellapneumonia, and Escherichiacoli, which are the most harmful and dangerous bacteria. Fe3O4/Se, as a heterogeneous catalyst, was successfully applied to the synthesis of pyrazolopyridine and its derivatives via a one-pot four-component reaction of ethyl acetoacetate, hydrazine hydrate, ammonium acetate, and various aromatic aldehydes. Fe3O4/Se was easily separated from the bacteria-containing solution using a magnet. Its admissible magnetic properties, crystalline structure, antibacterial activity, mild reaction conditions, and green synthesis are specific features that have led to the recommendation of the use of Fe3O4/Se in the water treatment field and medical applications. Direct Se doping of Fe3O4 was successfully realized without additional complicated procedures.

The solid state synthesis of novel pyrazolyl-5-amino-pyrazole-4-carbonitrile derivatives using Fe3O4@SP@TA nanocomposites as a novel, green, and magnetically separable catalyst

Tannic acid‐functionalized silica‐coated Fe3O4 nanocomposites (Fe3O4@SP@TA) were synthesized and characterized by transmission electron microscope (TEM), field emission scanning electron microscope (FE-SEM), X-ray powder diffraction (XRD), X-ray spectroscopy (EDX), vibrating sample magnetometry (VSM) and Fourier transform infrared spectroscopy (FT-IR). Fe3O4@SP@TA nanocomposite supplies an environmentally friendly procedure for the synthesis of some novel pyrazolyl-5-amino-pyrazole-4-carbonitrile through a three-component mechanochemical reaction of synthetized pyrazolecarbaldehydes, malononitrile, and phenylhydrazine according to green chemistry rules. These compounds were obtained in high yields and short reaction times. The catalyst could be easily recovered and reused for six cycles with almost consistent activity. The structures of the synthesized pyrazolyl-5-amino-pyrazole-4-carbonitrile compounds were confirmed by 1H NMR, 13C NMR, and FTIR spectral data and elemental analyses.

Graphene oxide:Fe2O3 nanocomposites for photodetector applications: experimental and ab initio density functional theory study.

In this report, a GO:Fe2O3 nanocomposite was synthesized using a one-step covalent attachment approach using a sol-gel technique. The optical absorbance, photoconductive, photo-capacitive, and electrical properties were obtained using spectroscopy, and current-voltage (I-V) measurements. An enhanced optical absorbance with corresponding band gap reduction is observed when Fe2O3 nanoparticles are incorporated in GO. A corresponding enhanced photoconductance in the order of ×101 was observed due to the impact of band gap narrowing. The enhanced photoconductivity and photo-capacitance can be attributed to energy and charge transfer between GO and Fe atoms, leading to the generation of photo-induced excitons. Density function theory calculations indicate increased charge transfer when GO is doped with Fe-O atoms, which is consistent with experimental data. The observed results could potentially enable the use of GO:Fe2O3 nanocomposites for photodetectors and other optoelectronic applications.

Impact of the indium content on structural, magnetic, and electrodynamic properties of nanocomposites based on In-substituted Sr hexaferrite and Ni–Zn spinel ferrite with excellent absorption characteristics

SrInxFe12-xO4/Ni0.5Zn0.5Fe2O4 (0.00 ≤ x ≤ 0.04) nanocomposites (SIFO/NZFO NCs) were synthesized using a one-pot sol-gel auto-combustion technique. The EDX method was used to verify the chemical composition. An X-ray diffractometer (XRD) was used for the structural analysis. Scanning electron microscopy (SEM) was used to study the morphological characteristics. The impact of indium doping on the magnetic properties of the nanocomposites was investigated using magnetization measurements at T = 300. A kink was observed in the M − H curves for lower indium content (x ≤ 0.02), which was suppressed with further increasing indium content until it vanished at a higher content. A single peak at a higher indium content replaced two peaks at a lower indium content (x 0.02), according to the switching field distribution (i.e., dM/dH vs. H). When the indium concentration increased, the saturation, remanence magnetization, and coercive field increased until x = 0.01, and then decreased, according to the analysis of the M − H loops. The obtained results reveal that an exchange interaction at the surface of the SIFO and NZFO nanoparticles (NPs) exists. The degree of intergranular dipolar interactions diminishes with increasing indium content within the hard-soft ferrite SIFO/NZFO NCs and becomes insignificant at higher indium contents. Moreover, the core of the SIFO and NZFO NPs also contains magnetic super-exchange interactions between Fe and O ions. At high frequencies (2–20 GHz), a correlation was found between the hard phase composition (indium content) and electrodynamic characteristics. Analyses were performed on the evolution of essential parameters (real and imaginary permittivity and permeability) in relation to the frequency. In this frequency range, the effect of electromagnetic radiation absorption was observed. A significant level of electromagnetic absorption (>-12 dB) in the frequency range was observed for investigated nanocomposites (NCs). The NCs with lower indium content (0.00 ≤ x ≤ 0.01) have higher reflection looses coefficients (−18 … -36 dB). This opens broad perspectives for the practical application of magnetic media for intensive electromagnetic absorption.

Poly (N-tert-amylacrylamide -co- Acrylamide/ Sodium acrylate) Fe3O4 Nanocomposite Hydrogels as polymer catalyst for the reduction of Methylene Blue Dye

Fe3O4 Nanocomposite Hydrogels were prepared by free radical polymerization using N-tert-amyl acrylamide , Acrylamide and Sodium acrylate monomers at 60OC. Fe3O4 NPs was intercalated via in situ method. The synthesized nanocomposite Hydrogels conformed by FT-IR spectroscopy. Surface morphology of the nanocomposite hydrogels indicated the ferrate nanoparticles are intercalated uniformly throughout the polymer matrix. The XRD pattern of the hydrogel showed the presence of nanoparticles in the matrix with certain crystallinity nature. UV-visible absorption studies reveal the catalytic activity of Methylene Blue dye molecules in the aqueous medium by the Nanocomposite hydrogels.

Bioinspired Dual-Mode Stretchable Strain Sensor Based on Magnetic Nanocomposites for Strain/Magnetic Discrimination.

Recently, flexible stretchable sensors have been gaining attention for their excellent adaptability for electronic skin applications. However, the preparation of stretchable strain sensors that achieve dual-mode sensing while still retaining ultra-low detection limit of strain, high sensitivity, and low cost is a pressing task. Herein, a high-performance dual-mode stretchable strain sensor (DMSSS) based on biomimetic scorpion foot slit microstructures and multi-walled carbon nanotubes (MWCNTs)/graphene (GR)/silicone rubber (SR)/Fe3 O4 nanocomposites is proposed, which can accurately sense strain and magnetic stimuli. The DMSSS exhibits a large strain detection range (≈160%), sensitivity up to 100.56 (130-160%), an ultra-low detection limit of strain (0.16% strain), and superior durability (9000 cycles of stretch/release). The sensor can accurately recognize sign language movement, as well as realize object proximity information perception and whole process information monitoring. Furthermore, human joint movements and micro-expressions can be monitored in real-time. Therefore, the DMSSS of this work opens up promising prospects for applications in sign language pose recognition, non-contact sensing, human-computer interaction, and electronic skin.

Dielectric properties of graphene/nano-Fe2O3 filled poly (vinyl alcohol)/Chitosan blends

Novel nanocomposites based on Poly (vinyl alcohol) (PVA), Chitosan (CS), Graphene quantum dots (GQDs) and iron oxide (Fe2O3) nanoparticles (NPs) have been synthesized by solution casting method. The structural modifications and morphological studies were carried out by Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD) and Scanning electron microscopy/Energy-dispersive X-ray (SEM/EDX) techniques. The results confirm the microscopic interactions and sphere-like morphology of the nanocomposites due to the presence of GQDs and Fe2O3 within the polymer blend. The thermal stability with almost 25% leftover residue for higher nanofillers loading in the nanocomposite was estimated by thermo-gravimetric analysis (TGA). Moreover, the frequency and temperature-dependent dielectric properties were investigated. The dielectric constant and loss tangent values are greatly influenced by reinforcement of GQDs/Fe2O3 and the obtained values were in the range of ∼104 and ∼101, respectively at 150 °C and 50 Hz. The rise in ac conductivity i.e., 9.8 x 10−4 (S/m) with increasing nanofiller loadings suggests the reduction in capacitive reactance and impedance. However, the semi-circular arcs are observed in the cole-cole plot where the fitted impedance data along with the equivalent circuit is also presented. The reduction of bulk resistance and impedance on increasing the nanofiller loadings with enhanced dielectric properties signifies the use of PVA/CS/GQDs/Fe2O3 nanocomposites as a potential material for energy storage applications.

Evaluation of HER and OER electrocatalytic activity over RuO2–Fe2O3 nanocomposite deposited on HrGO nanosheets

Electrochemical water-splitting efficiency is determined by both hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) electrocatalysts. Therefore, designing a bi-functional configuration is essential for an efficient HER and OER catalytic performance under the same experimental conditions. In this study, a novel ionic pentanuclear complex of the type [Ru(dmbpy)3]3[Fe(CN)6]2, where dmbpy = 4,4′-dimethyl-2,2′-bipyridine, has been synthesized and characterized by structural (X-ray), analytical (CHN), and spectral (FT–IR, UV–Vis) methods. Highly reduced graphene oxide nanosheets (HrGO NSs) supported RuO2–Fe2O3 nanocomposite were prepared by an impregnation method using [Ru(dmbpy)3]3[Fe(CN)6]2 as a precursor and HrGO NSs as a support. The RuO2–Fe2O3/HrGO NSs nanocomposite was characterized by means of spectroscopy (XPS, FT–IR, and FT–Raman), surface area (BET/BJH), diffraction (XRD), thermal (TGA), and electron microscopy (TEM and FE–SEM) analyses. The electrocatalytic HER, OER, and overall water-splitting activities of RuO2–Fe2O3/HrGO NSs, RuO2–Fe2O3, RuO2/HrGO, Fe2O3/HrGO, and HrGO in 1 M KOH solution were studied. According to the overpotentials of −239 and 386 mV (vs. RHE) at 10 mA cm−2 current density, the exchange current densities of 0.0641 and 0.389 × 10−4 mA cm−2, the Tafel slopes of 97 and 67 mV dec−1, and the charge-transfer resistance values of 38.57 and 31.5 Ω for HER and OER, respectively, the RuO2–Fe2O3/HrGO NSs nanocomposite possesses bi-functional catalytic capabilities toward both hydrogen and oxygen evolution reactions. The catalytic performance is enhanced by the high surface area, the high number of catalytically active sites, the presence of nanoparticles with different morphologies, and the synergistic interaction between RuO2–Fe2O3 nanoparticles and HrGO nanosheets.

2,4-Dichlorophenoxyacetic acid (2,4-D) adsorptive removal by algal magnetic activated carbon nanocomposite

In the present study, ferric oxide nanoparticles impregnated with activated carbon from Ulva prolifera biomass (UPAC−Fe2O3) were prepared and employed to remove 2,4-Dichlorophenoxyacetic acid (2,4-D) by adsorption. The UPAC−Fe2O3 nanocomposite was characterized for its structural and functional properties by a variety of techniques. The nanocomposite had a jagged, irregular surface with pores due to uneven scattering of Fe2O3 nanoparticles, whereas elemental analysis portrayed the incidence of carbon, oxygen, and iron. XRD analysis established the crystalline and amorphous planes corresponding to the iron oxide and carbon phase respectively. FT-IR analyzed the functional groups that confirmed the integration of Fe2O3 nanoparticles onto nanocomposite surfaces. VSM and XPS studies uncovered the superparamagnetic nature and presence of carbon and Fe2O3, respectively, in the UPAC−Fe2O3 nanocomposite. While the surface area was 292.51 m2/g, the size and volume of the pores were at 2.61 nm and 0.1906 cm3/g, respectively, indicating the mesoporous nature and suitability of the nanocomposites that could be used as adsorbents. Adsorptive removal of 2,4-D by nanocomposite for variations in process parameters like pH, dosage, agitation speed, adsorption time, and 2,4-D concentration was studied. The adsorption of 2,4-D by UPAC−Fe2O3 nanocomposite was monolayer chemisorption owing to Langmuir isotherm behavior along with a pseudo-second-order kinetic model. The maximum adsorption capacity and second order rate constant values were 60.61 mg/g and 0.0405 g/mg min respectively. Thermodynamic analysis revealed the spontaneous and feasible endothermic adsorption process. These findings confirm the suitability of the synthesized UPAC−Fe2O3 nanocomposite to be used as an adsorbent for toxic herbicide waste streams.

Encapsulating hollow Fe3O4 in intertwined N-doped carbon nanofibers for high-performance supercapacitors and sodium-ion batteries

As a promising electrode for energy storage, Fe3O4 has many intriguing advantages, such as a high specific capacity, low cost, low toxicity, wide potential window and environmental benignity. However, the multi-phase changes of iron oxide during the charge and discharge process can give rise to a sharp decrease in its capacity. In addition, the low conductivity of Fe3O4 may hinder the charge transfer and ion diffusion during redox process. In order to solve the above issues, this study mainly attempts to design a nanocomposite of Fe3O4 encapsulated in intertwined N-doped carbon nanofibers (CNFs) via using electrospinning and high-temperature calcination. The sealed structure can efficiently relieve the volume effect of Fe3O4 and raise the stability of electrodes. While a 3-dimensional interconnected conductive network composed of CNFs can increase the electroconductibility of electrodes. At the same time, the N-doping increases active sites on the surface of CNFs, providing more space for ions and charges storage. Herein, different amounts of Fe3O4 are encapsulated in N-doped CNFs (Fe3O4-CNFs). Fe3O4-CNFs with 40 % content of Fe3O4 (4Fe3O4-CNFs) deliver splendid electrochemical performances for all-solid-state supercapacitors and sodium-ion batteries. The specific capacitance of 4Fe3O4-CNFs supercapacitor is 184.5 F g−1 and maintains 86.2 % of initial capacity at 2 A g−1 after 5000 times. Furthermore, 4Fe3O4-CNFs as the anode for the half cell vs. Na+/Na demonstrate a splendid specific capacity of 628.1 mAh g−1 at 0.02 A g−1 and can maintain 358.1 mA h g−1 after cycling for 200 laps at 500 mA g−1. Therefore, 4Fe3O4-CNFs can be widely used in energy storage.

Electro-oxidation of heavy metals contaminated water using banana waste-derived activated carbon and Fe3O4 nanocomposites

The main objective of this study was to banana waste-derived activated carbon (BWAC) make a high pore surface area was prepared and composited with Fe3O4 via a facile hydrothermal method. Various physiochemical characteristics of the prepared samples were evaluated using XRD, FTIR, FESEM, Raman Spectroscopy and XPS analysis. In addition, cyclic voltammetry and electrochemical impedance spectroscopy analyses were performed to determine the electrochemical properties of the prepared samples. The Fe3O4/BWAC sample showed a higher capacitance (285 F g−1) than BWAC at the same scan rate of 10 mV s−1. The capacitive deionization (CDI) cell configuration was varied, and its electro-sorption and defluoridization efficiencies were analyzed during the lead (Pb2+) removal 90%. An asymmetric combination of electrodes in the CDI cell exhibited better heavy metal removal performance, possibly due to the synergistic effect of the high surface area and the balance between the active adsorption site and the overlapping effect of the EDL. As a result, Fe3O4/BWAC could be a potential resource for supercapacitors and CDI electrodes, and the novel Fe3O4/BWAC nanocomposites outstanding performance suggests that they could be helpful for future energy storage and environmental applications.

Synergistic engineering for adsorption assisted photodegradation of 2,4 dichlorophenol using easily recoverable ɑ-MnO2/Fe3O4 nanocomposite

Herein, a highly effective ɑ-MnO2/Fe3O4 nanocomposite was synthesized employing a hydrothermal process and characterized by scanning electron microscopy, energy dispersive X-ray analysis, X-ray diffraction, vibrating sample magnetometer (VSM), Fourier transform infrared spectroscopy (FTIR), and UV–visible spectroscopy. The ɑ-MnO2/Fe3O4 photocatalyst flaunts two phases: magnetic magnetite (Fe3O4) nanoparticles of 22±5 nm agglomerated on ɑ-MnO2 1-D nanowire of ∼1.5 µm length and 50±10 nm in diameter. The results exhibited ∼100% photocatalytic degradation of 2,4-DCP under UV-visible irradiation within 80 min at pH 9. The photocatalytic experimental values were fitted linearly with first-order reaction exhibiting k = 0.065 min−1, t1/2 = 10.45 min, and R2 = 0.98 for UV-visible light and k = 0.028 min−1, t1/2 = 34 min and R2 = 0.97 for reaction under sunlight. Additionally, the nanocomposite photocatalyst was easily recoverable using an external magnetic field at room temperature with high stability. Therefore, a simple synthesis method, a synergistic effect between ɑ-MnO2 and Fe3O4, an excellent adsorption-induced photocatalytic activity, easy magnetic recovery, and robustness for reusability make the nanocomposite an outstanding material for environmental sustainability and solar energy harvesting.

Fabrication of TiO2 Spheres and a Visible Light Active α-Fe2O3/TiO2-Rutile/TiO2-Anatase Heterogeneous Photocatalyst from Natural Ilmenite.

High-purity (98.8%, TiO2) rutile nanoparticles were successfully synthesized using ilmenite sand as the initial titanium source. This novel synthesis method was cost-effective and straightforward due to the absence of the traditional gravity, magnetic, electrostatic separation, ball milling, and smelting processes. Synthesized TiO2 nanoparticles were 99% pure. Also, highly corrosive environmentally hazardous acid leachate generated during the leaching process of ilmenite sand was effectively converted into a highly efficient visible light active photocatalyst. The prepared photocatalyst system consists of anatase-TiO2/rutile-TiO2/Fe2O3 (TF-800), rutile-TiO2/Fe2TiO5 (TFTO-800), and anatase-TiO2/Fe3O4 (TF-450) nanocomposites, respectively. The pseudo-second-order adsorption rate of the TF-800 ternary nanocomposite was 0.126 g mg–1 min–1 in dark conditions, and a 0.044 min–1 visible light initial photodegradation rate was exhibited. The TFTO-800 binary nanocomposite adsorbed methylene blue (MB) following pseudo-second-order adsorption (0.224 g mg–1 min–1) in the dark, and the rate constant for photodegradation of MB in visible light was 0.006 min–1. The prepared TF-450 nanocomposite did not display excellent adsorptive and photocatalytic performances throughout the experiment period. The synthesized TF-800 and TFTO-800 were able to degrade 93.1 and 49.8% of a 100 mL, 10 ppm MB dye solution within 180 min, respectively.

Impact of sonication time on the structural and magnetic features of CoFe2O4/Ni0.8Cu0.1Zn0.1Fe2O4 hard-soft nanocomposites

Hard/soft (H/S) CoFe2O4/Ni0.8Cu0.1Zn0.1Fe2O4 nanocomposites (NCs) were prepared via ultrasonic irradiation method under different ultrasonication durations (10, 20, 30, 40, 50, and 60 min). The structure and morphology of these nanocomposites were analyzed through XRD, FT-IR, SEM, TEM, and EDX techniques, which confirmed the successful preparation of the desired nanocomposites. The crystallites/particles size was found to reduce with increasing ultrasonication duration. The magnetic properties of H/S CoFe2O4/Ni0.8Cu0.1Zn0.1Fe2O4 NCs prepared via ultrasonication method under different ultrasonication durations (10, 20, 30, 40, 50, and 60 min) were investigated through measurements of magnetization against the magnetic field (M-H) at 10 and 300 K. The soft character of the prepared NCs at room temperature depicted their superparamagnetic behaviors. At extremely low temperatures (T = 10 K), all H/S ferrite NCs revealed opened M-H hysteresis loops, indicating their ferrimagnetic behavior at low temperatures. All H/S NCs do not reveal any kind of anomalies in their M-H curves. Additionally, the SFD (switching field distribution) analysis pointed out a single peak in dM/dH against H curves. It was found that the intergranular exchange coupling interactions are more dominant than the intergranular dipolar interactions. Such a result indicates that the current synthesis method is useful to produce good exchange-coupled hard/soft ferrite NCs. It was also observed that the Ms and Mr values at both 10 and 300 K are decreasing with rising the ultrasonication duration. However, the Hc value was found to increase with rising ultrasonication duration, reaching a maximum value under an ultrasonication duration of 30 min, then, the Hc value decreases with further rising the ultrasonication duration. The plausible reasons for the variations in magnetic parameters were discussed.

Enhanced antibacterial activity of a novel protein-arginine deiminase type-4 (PADI4) inhibitor after conjugation with a biocompatible nanocarrier

The present study reveals a simple and cost-effective method to enhance the antibacterial activity of a model antibiotic drug azithromycin which can also be used as an inhibitor of protein-arginine deiminase type-4 (PADI4). At first, molecular docking has been used for obtaining binding modes and binding affinities of this drug to prove its role as an effective inhibitor for protein-arginine deiminase type-4 (PADI4). In the next step, a biocompatible nanocarrier has been synthesized for successful targeting of the drug azithromycin to enhance its efficiency to a greater extent. For the formation of the nanocarrier, Cu–Ag–Fe2O3 nanocomposite has been synthesized by mechanical alloying the Cu, Ag and Fe2O3 powder for 3 h. After the successful formation of the nanocomposite, 10 wt% of the drug has been conjugated with the nanocomposite by further milling for 1 h under the same experimental condition. The nanocomposite (NC) and drug conjugated nanocomposite (NC-DC) samples are well-characterized by the Rietveld refinement of the XRD pattern of the NC-DC sample, analyzing FTIR, EDS spectra, and FESEM images. It has been observed that both the samples are non-toxic to human normal lung fibroblast WI38 cells. The antibacterial activity of the drug conjugated nanocomposite sample has been enhanced significantly compared to the pure drug azithromycin. These investigations have been made by agar cup assay and minimum inhibitory concentrations (MIC) studies. As a minimal amount of drug is required for the conjugation, side effects and the cost of an expensive drug can be minimized to a great extent following the proposed synthesis route. The enhancement of the antibacterial activity of azithromycin conjugated nanocomposite gives a possibility that drug conjugated nanocomposite may have enhanced activity in the inhibition of PADI4. It may cure the harmful effects of COVID-19 or inhibit the growth of tumour cells more efficiently by improving the cell membrane penetration power of the drug due to its conjugation with the nanocomposite.

Carbon-coated Fe3O4 nanocomposites anchored on Ti3C2 nanosheets for enhanced Li-storage

Fe3O4 is a promising anode material for high-power rechargeable lithium-ion batteries (LIBs) benefiting from its high reversible capacity, rich natural resources, and easy preparation. However, the rate capability and the cyclability of the Fe3O4 electrode are still unsatisfactory limited by its poor electronic conductivity and tremendous volume variation during Li+ insertion/desertion progress. To tackle these difficulties, carbon-coated Fe3O4 nanocomposites anchored on few-layered Ti3C2 nanosheets (Fe3O4 @C/Ti3C2) were prepared by a facile and scalable citric acid-assisted sol-gel process. As an anode material for LIBs, the Fe3O4 @C/Ti3C2 electrode delivers a high reversible capacity of 1285 mAh g−1 at 100 mA g−1 and a high rate capacity of 405 mAh g−1 at 5 A g−1. Moreover, the Fe3O4 @C/Ti3C2 electrode presents a steady cyclability for more than 1000 cycles at 5 A g−1. The enhanced Li-ion storage performance of the Fe3O4 @C/Ti3C2 electrode could be attributed to the high electrical conductivity and the mechanical robustness of the Ti3C2 nanosheets.

Fast and Eco‐Friendly Determination of Nitrite in Water Using Deep Eutectic Solvent‐Based Magnetic Bucky Gels

In this study, a novel magnetic bucky gel (MBG) was synthesized and coupled with dispersive magnetic solid-phase extraction for preconcentration and determination of trace levels of nitrite in various water samples. The MBG was prepared by dispersing magnetic graphitic carbon nitride nanocomposite (g-C3N4@Fe3O4) in a choline chloride-urea deep eutectic solvent (1:2, molar ratio). The deep eutectic solvent (DES) acts as a disperser and surface modifier for g-C3N4/Fe3O4 nanocomposites simultaneously and led to superior uptake of the analyte in a shorter time. The sorbent was characterized by Fourier transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD), and field emission scanning electron microscopy (FESEM). The NO2− determination was carried out by UV-vis spectrophotometry. Variable factors on preconcentration of NO2− including pH, composition of MBG, contact time, sample volume, eluent type, eluent volume, and elution time were optimized. Under optimum condition, the limit of detection (LOD) was 1.56 μg L−1, the linear dynamic range extended from 5.14 to 900.00 μg L−1, the relative standard deviation (n = 5) and the preconcentration factor were 2.7% and 100, respectively. The method was successfully used for the preconcentration of NO2− ions in different water samples and gave recoveries between 89 and 103%. This article is protected by copyright. All rights reserved

Structure and magnetic investigation of hard/soft Ba0.5Sr0.5Fe12O19/x(Ni0.5Zn0.5)Fe2O4 nanocomposite

In this work, magnetic nanocomposites Ba0.5Sr0.5Fe12O19/x(Ni0.5Zn0.5)Fe2O4 with the compositions x = 10, 20, 30, and 50 wt%, arising from nickel-zinc ferrite added to barium strontium hexaferrite were prepared and characterized. The samples were synthesized using co-precipitation and ball milling methods. X-ray powder diffraction measurements validated the synthesis of nanocomposite with high purity and crystallinity. A transmission electron microscope was also used to analyze the morphology of the nanocomposites that demonstrated hexagonal platelet-like and spherical-like shapes for hard and soft phases, respectively. Also, multiple shapes of different grain sizes were formed, and their grain size decreased upon the addition of the soft phase. Besides, the elemental compositions and the oxidation states of (Ba2+, Sr2+, Ni2+, Ni3+, Zn2+, Fe2+, Fe3+and O2-) constituting the nanocomposites were investigated, using X-ray photoelectron spectroscopy. Additionally, the magnetic properties were examined using a vibrating sample magnetometer. According to Henkel plots, the existence of a weak exchange coupling interaction and the dominance of dipolar interactions were visible upon the addition of Ni0.5Zn0.5Fe2O4. Furthermore, the maximum energy product, (BH)max, is the energy density that a hard ferrite can store with low magnetic anisotropy. (BH)max of the nanocomposite containing 10 wt% of soft phase increased by 10% when compared to pure hard phase, reaching the highest value of (BH)max equal to 22.89 kJ/m3.