Carbon-coated Fe3O4 Nanoparticles Research Articles

Carbon-coated Fe3O4 nanoparticles in situ grown on 3D cross-linked carbon nanosheets as anodic materials for high capacity lithium and sodium-ion batteries

Carbon coated Fe3O4 nanoparticles were grown in situ on 3D cross-linked carbon nanosheets, and exhibited excellent performance for lithium ion batteries.

Peroxidase-like activity of Fe3O4/carbon core-shell nanostructured : effects of carbon shell thickness for application to glucose biosensor

In this study, we present a protocol for synthesis of carbon coated Fe3O4 nanoparticles with core-shell structured nanocomposite (FeC) following a two steps approach. The peroxidase-like acitivity of the synthesized FeC nanocomposite has been evaluated towards replacing of the horseradish peroxidase enzyme (HRP) in hydrogen peroxide enzymatic biosensor. In which, FeC has catalyzed for a redox reaction 5,5'-tetramethylbenzidine (TMB) and H2O2 to produce oxidized state of TMB with as a blue color. Results exhibited that FeC has a high catalytic activity accepting for fabrication of a high selectivity hydrogen peroxide (H2O2) colorimetric sensor with low detection of limit (LoD) of 0.02 mM H2O2. Based on this finding, we have used FeC and combined with glucose oxidase (GOx) enzyme to construct a new colorimetric glucose biosensor with high selectivity.

In-situ plantation of Fe3O4@C nanoparticles on reduced graphene oxide nanosheet as high-performance anode for lithium/sodium-ion batteries

Fe3O4 is considered to be an ideal substitute for graphite anode due to its high lithium (Li) and sodium (Na) storage capacity, however, its sharp volume change after lithiation/sodiumization and poor electrical conductivity have brought huge challenges to the practical application. In this study, a lamellar Fe3O4-based electrode was constructed via an in-situ plantation of carbon-coated Fe3O4 nanoparticles on the surface of the reduced graphene oxide nanosheet. Owing to the ultra-small carbon-coated Fe3O4 nanoparticles (~12.5 nm) and unique two-dimensional lamellar structure, the obtained sample displays excellent cycle and rate performance in lithium/sodium-ion batteries. A high reversible capacity of 849 mA h g−1 is obtained at 500 mA g−1 after 120 cycles for lithium-ion batteries and a discharge capacity up to 429 mA h g−1 is remained at 100 mA g−1 after 300 cycles for sodium-ion batteries.

Accordion-like composite of carbon-coated Fe3O4 nanoparticle decorated Ti3C2 MXene with enhanced electrochemical performance

MXene-based materials are considered to be promising candidates for electrodes in energy storage field owing to their features of two-dimensional layered structure, good conductivity, and chemical stability. Carbon-coated Fe3O4 nanoparticles (C@Fe3O4 NPs)-decorated Ti3C2 MXene composites were synthesized via a facile method for the first time. The prepared C@Fe3O4 NPs/Ti3C2 MXene composite was characterized by various techniques (XRD, SEM, TEM, TGA, and XPS), and the results showed that C@Fe3O4 NPs (diameter: 60 nm, layer thickness: 10 nm) were homogeneously distributed on the surfaces of Ti3C2 MXene interlayers while the accordion-like structure maintained. It is noted that the specific surface areas dramatically increased from 7.8 m2/g to 37.0 m2/g after introducing the nanoparticles. The C@Fe3O4 NPs/Ti3C2 MXene products exhibited a specific capacity of 231.5 mAh g−1 after 200 cycles under 100 mA/g when serving as anode materials for Li-ion batteries, which was markedly higher than that of pure Ti3C2 MXene (107.8 mAh g−1). This study presents and investigates a novel kind of MXene-based composite, which has the potential as electrode materials for energy storage.

Synthesis of carbon coated Fe3O4 grown on graphene as effective sulfur-host materials for advanced lithium/sulfur battery

Lithium/sulfur battery (LSB) is considered as one of the most promising battery systems due to its high energy density of 2600 Wh kg−1. Nevertheless, the LSB suffers from some inherent problems that impede its practical application. To circumvent these problems, we grow carbon-coated ferroferric oxide (Fe3O4) nanoparticles on graphene (Fe3O4@C-G) as an effective sulfur host for LSB via a facile hydrothermal method followed by calcination. Highly conductive graphene is utilized to homogeneously deposit the carbon-coated Fe3O4 nanoparticles (Fe3O4@C), which enable rapid and steady long-distance electron transport. Moreover, the carbon coated particles of Fe3O4@C exhibit a developed micro-mesoporous structure, which not only provide space for sulfur loading to prepare a composite Sulfur/carbon-coated Fe3O4 nanoparticles on graphene (S/Fe3O4@C-G) cathode, but also provide channels for the interaction between Fe3O4 and lithium polysulfides. Furthermore, a strong chemical affinity of Fe3O4 nanoparticles coated by micro-mesoporous carbon layers towards polysulfides can be strengthened through the polar-polar interaction. Owning these advantages, the S/Fe3O4@C-G composite cathode deliver a high initial capacity of 1425 mAh g−1 at 0.2 C and maintain a capacity of 1102 mAh g−1 after 100 cycles.

Magnetic solid phase extraction with carbon-coated Fe3O4 nanoparticles coupled to HPLC-UV for the simultaneous determination of losartan, carvedilol, and amlodipine besylate in plasma samples

In this paper, a chemical coprecipitation method was used for the synthesis of Fe3O4 magnetic nanoparticles. The Fe3O4 magnetic nanoparticles were then modified by carbon via a simple hydrothermal method by using glucose. The synthesized Fe3O4 and carbon-coated Fe3O4 (C/Fe3O4) magnetic nanoparticles were characterized by diverse techniques such as XRD, FESEM, EDX, FTIR, and BET. The characterization results were confirmed the formation of the uniformly magnetic nanoparticles and a successful modification of them by carbon. The FTIR spectra confirmed the presence of functional groups on the C/Fe3O4 magnetic nanoparticles surface. The magnetic nanoparticles were used for extraction of losartan, carvedilol, and amlodipine besylate from plasma samples based on magnetic solid phase extraction (MSPE) technique. The effective parameters on extraction efficiency were optimized by multivariate optimization. Under the optimized experimental conditions the MSPE method showed wide linear ranges (1–7500 ng mL−1), low detection limits (0.09–0.69 ng mL−1), good extraction recoveries (56.35–66.43%), and low RSD values (1.6–5.8%). Despite high protein binding of the drugs, the analyses of them were done without protein precipitation. The accuracy was studied by analyses of the spiked plasma samples at different concentrations.

Highly dispersible carbon composited Fe3O4 nanoparticles in an aqueous solvent via normal pressure liquid reaction

In this study, a simple fabrication of carbon composited Fe3O4 nanoparticles was carried out under reflux condition using glucose as a carbon precursor. The carbon composited Fe3O4 nanoparticles having a core-shell structure were synthesized in a low-temperature and low-pressure atmosphere instead of in an autoclave. Simple carbonization without inert gas and extra heating was complemented by adding sulfuric acid, which has an important role as a carbonization catalyst. In addition, sulfuric acid also acted as the controller of such surface properties as surface area by an etching effect. The prepared nanoparticles have uniform and continuous carbon layers, which have several functions, such as stable dispersibility and an increase of electron conductivity. carbon composited Fe3O4 nanoparticles were investigated with zeta-potential, particle size distribution, Fourier transform infrared, scanning electron microscopy, transmission electron microscopy, Raman spectroscopy, and a vibrating sample magnetometer. The results provide clear evidence that carbon-coated Fe3O4 nanoparticles are applicable in electrochemical industrial fields.

Enhanced cycle stability of iron(II, III) oxide nanoparticles encapsulated with nitrogen-doped carbon and graphene frameworks for lithium battery anodes

Nitrogen-doped carbon-coated and graphene oxide-wrapped Fe3O4 nanoparticles were prepared using the electrostatic force between polyethyleneimine-functionalized Fe3O4 nanoparticles and graphene oxide layers, followed by annealing in an N2 atmosphere (Fe3O4@NCG). The electrochemical performance of Fe3O4@NCG was superior to that of graphene oxide- or reduced graphene oxide-wrapped Fe3O4 nanoparticles and carbon-coated Fe3O4 nanoparticles. Fe3O4@NCG exhibited stable specific capacity of ∼895 mAh g−1 after 350 cycles over the voltage range 0.001–3.0 V vs. Li/Li+. The superior performance of Fe3O4@NCG was attributed to the presence of a nitrogen-doped carbon layer and networks of reduced graphene oxide. The chemical route-derived Fe3O4@NCG may be a promising anode material for high-performance lithium-ion batteries.

One-Step Carbon Coating and Polyacrylamide Functionalization of Fe₃O₄ Nanoparticles for Enhancing Magnetic Adsorptive-Remediation of Heavy Metals.

Magnetic nanoparticles are used in adsorptive removal of heavy metals from polluted wastewater. However, their poor stability in an acidic medium necessitates their protection with a coating layer. Coating magnetic nanoparticles with carbon showed proper protection but the heavy metal removal efficiency was slightly weak. However, to boost the removal efficiencies of surface functionalization, polyacrylamide was applied to carbon-coated Fe3O4 nanoparticles. In this paper, to facilitate the synthesis process, one-step carbon coating and polyacrylamide functionalization were conducted using the hydrothermal technique with the aim of enhancing the adsorptive removal capacity of Fe3O4 nanoparticles towards some heavy metals such as Cu(II), Ni(II), Co(II), and Cd(II). The results showed that the one-step process succeeded in developing a carbon coating layer and polyacrylamide functionality on Fe3O4 nanoparticles. The stability of the magnetic Fe3O4 nanoparticles as an adsorbent in an acidic medium was improved due to its resistance to the dissolution that was gained during carbon coating and surface functionalization with polyacrylamide. The adsorptive removal process was investigated in relation to various parameters such as pH, time of contact, metal ion concentrations, adsorbent dose, and temperature. The polyacrylamide functionalized Fe3O4 showed an improvement in the adsorption capacity as compared with the unfunctionalized one. The conditions for superior adsorption were obtained at pH 6; time of contact, 90 min; metal solution concentration, 200 mg/L; adsorbent dose, 0.3 g/L. The modeling of the adsorption data was found to be consistent with the pseudo-second-order kinetic model, which suggests a fast adsorption process. However, the equilibrium data modeling was consistent with both the Langmuir and Freundlich isotherms. Furthermore, the thermodynamic parameters of the adsorptive removal process, including ΔG°, ΔH°, and ΔS°, indicated a spontaneous and endothermic sorption process. The developed adsorbent can be utilized further for industrial-based applications.

Preparation of carbon coated Fe3O4 nanoparticles for magnetic separation of uranium

Uranium(VI) was removed from aqueous solutions using carbon coated Fe3O4 nanoparticles (Fe3O4@C). Batch experiments were conducted to study the effects of initial pH, shaking time and temperature on uranium sorption efficiency. It was found that the maximum adsorption capacity of the Fe3O4@C toward uranium(VI) was ∼120.20 mg g−1 when the initial uranium(VI) concentration was 100 mg L−1, displaying a high efficiency for the removal of uranium(VI) ions. Kinetics of the uranium(VI) removal is found to follow pseudo-second-order rate equation. In addition, the uranium(VI)-loaded Fe3O4@C nanoparticles can be recovered easily from aqueous solution by magnetic separation and regenerated by acid treatment. Present study suggested that magnetic Fe3O4@C composite particles can be used as an effective and recyclable adsorbent for the removal of uranium(VI) from aqueous solutions.

A novel porous reduced microcrystalline graphene oxide supported Fe3O4@C nanoparticle composite as anode material with excellent lithium storage performances

The competitiveness of reduced graphene oxide (GO) based composite can be significantly improved when the raw material of GO become the low-cost microcrystalline graphite mine. Herein, we first successfully fabricate high-quality microcrystalline graphite GO (MGO) with small size <1μm by a modified pressurized oxidation approach. Subsequently, Fe3O4@C/PrMGO composite is simply constructed by using porous reduced MGO (PrMGO) to support carbon coated Fe3O4 nanoparticles (Fe3O4@C NPs). The Fe3O4@C/PrMGO composite exhibits high reversible capacity and excellent cyclic stability that a high reversible capacity of 1216mAhg−1 is received after 392 cycles at 100mAg−1. Meanwhile, the composite possesses high rate retentions, superior structural and cycling stability, which are further revealed by rate test, SEM and EIS analyses. The significant advantages of Fe3O4@C/PrMGO composite (low cost, facile operation and high electrochemical performances) endow the composite to be practically promising anode material for next-generation LIBs. This research supplies a new strategy to fabricate low-cost and high performances MGO-based anode materials.

Carbon-coated Fe3O4 nanoparticles with surface amido groups for magnetic solid phase extraction of Cr(III), Co(II), Cd(II), Zn(II) and Pb(II) prior to their quantitation by ICP-MS

A magnetic nanosorbent was prepared from Fe3O4 nanoparticles and polyacrylamide using a solvothermal process. Two functions are achieved simultaneously in this process: The first consists in the formation of a carbon layer around the Fe3O4 nanoparticles, and the second one in the functionalization with an amido group. This combination allows the protection of Fe3O4 nanoparticles from dissolution in acid medium during heavy metal adsorption. The adsorbent was characterized by SEM, TEM, EDS, FTIR, TGA, and in terms of surface area. Results showed the Fe3O4 nanoparticles to be embedded in a sheet of carbon with folded surfaces which is functionalized with amido groups. The nanosorbent was applied to the enrichment of Cr(III), Co(II), Cd(II), Zn(II) and Pb(II) via magnetic solid phase extraction (mag-SPE). The effects of pH value, eluent type and sample volume were optimized. The validation of the procedure was verified by the analysis of a wheat gluten certified reference material (8418). The limits of detection for the above ions range from 1 to 110 ng L−1. The relative standard deviations are <10%. The procedure was successfully applied to the enrichment of Cr(III), Co(II), Cd(II), Zn(II) and Pb(II) from various water and food samples.

Adsorption Behavior of Lysozyme on Carbon-Coated Fe3O4 Nanoparticles

Background: Recently, hydrophilic carbon-coated magnetite (Fe3O4/C) has been prepared and applied in adsorption and separation sciences. Although there have been some works on preparation and application of Fe3O4/C in adsorption and separation sciences, little work has been carried out on protein adsorption and desorption on Fe3O4/C. Herein, the present work investigated the equilibrium and kinetics of protein (lysozyme) adsorption on Fe3O4/C NPs. Keywords: Adsorption, Carbon coated Fe3O4 nanoparticles, Isotherm, Kinetics, Lysozyme, Magnetic separation.

Citrus pectin derived ultrasmall Fe3O4@C nanoparticles as a high-performance adsorbent toward removal of methylene blue

Carbon coated Fe3O4 nanoparticles (Fe3O4@C NPs) were synthesized by using citrus pectin as the carbon source. The as-prepared nanoparticles were spherical with the smallest, uniformly size of 7nm among all reported and large specific surface area. Surprisingly, the Fe3O4@C NPs further demonstrated dramatic ability to remove methylene blue for a maximum adsorption capacity of 141.3mgg−1 and superior recyclability up to 20cycles. Further experimental results revealed that the adsorption kinetic and isotherm fitted well with the pseudo-second-order kinetic and Freundlich isotherm model, respectively. The nanoparticles were further used efficiently to remove methylene blue from spiked environmental water sample. Thus, the synthesized Fe3O4@C NPs hold great potential for dyes removal in the wastewater treatment while opening a new path for efficient utilization of citrus pectin.

Facile solution-free preparation of a carbon coated Fe3O4 nanoparticles/expanded graphite composite with outstanding Li-storage performances

A novel carbon coated Fe3O4 nanoparticles (NPs)/expanded graphite (EG) composite has been prepared by in-situ pyrolysis of ferrecene on the nanosheets (NSs) of EG in an isolated atmosphere. Results indicated that the restack behavior of the NSs of EG which is easy to be induced by solvent removal was effectively avoided by this solution-free route. Well-crystallized Fe3O4-NPs with a dimension of <5nm were observed to be homogeneously anchored on these NSs. The composite as anode material of Li-ion batteries (LIBs) exhibited prominently enhanced reversible capacity and rate capability, meanwhile inherited the superior cycling performance of EG. After 100 cycles at 100mAg−1, the charge capacity still reached 728mAhg−1, which was 283% higher than that of pure EG. The greatly improved electrochemical performances are ascribed to the favorable synergistic effect between carbon coated Fe3O4-NPs and EG, suggesting that the special Fe3O4-NPs/EG composite is promising anode material for high-performance LIBs.

Synthesis and application of bilayer-surfactant-enveloped Fe3O4 nanoparticles: water-based bilayer-surfactant-enveloped ferrofluids

Superparamagnetic carbon-coated Fe3O4 nanoparticles with high magnetization (85 emu·g-1) and high crystallinity were synthesized using polyethylene glycol-4000 (PEG (4000)) as a carbon source. Fe3O4 water-based bilayer-surfactant-enveloped ferrofluids were subsequently prepared using sodium oleate and PEG (4000) as dispersants. Analyses using X-ray photoelectron spectroscopy, X-ray diffraction, and Fourier-transform infrared spectroscopy indicate that the Fe3O4 nanoparticles with a bilayer surfactant coating retain the inverse spinel-type structure and are successfully coated with sodium oleate and PEG (4000). Transmission electron microscopy, vibrating sample magnetometry, and particle-size analysis results indicate that the coated Fe3O4 nanoparticles also retain the good saturation magnetization of Fe3O4 (79.6 emu·g-1) and that the particle size of the bilayer-surfactant-enveloped Fe3O4 nanoparticles is 42.97 nm, which is substantially smaller than that of the unmodified Fe3O4 nanoparticles (486.2 nm). UV–vis and zeta-potential analyses reveal that the ferrofluids does not agglomerate for 120 h at a concentration of 4 g·L-1, which indicates that the ferrofluids are highly stable.

Extraction of organophosphorus pesticides by carbon-coated Fe3 O4 nanoparticles through response surface experimental design.

In this paper, carbon-coated Fe3 O4 nanoparticles were successfully synthesized and used as a magnetic solid-phase extraction absorbent for the preconcentration and extraction of organophosphorus pesticides in environmental water samples. The carbon-coated Fe3 O4 nanoparticles were characterized by transmission electron microscopy, X-ray powder diffraction, Fourier transform infrared spectroscopy, and vibrating sample magnetometry. The determination of organophosphorus pesticides in water samples with carbon-coated Fe3 O4 nanoparticles was investigated by high-performance liquid chromatography with a diode array detector. Furthermore, the response surface model based on the central composite design was applied to quantitatively investigate the effect of some important variables influencing the extraction efficiency, such as pH, treatment time, amount of nanoparticle sorbents, and amount of salt and to find the optimized conditions providing the highest extraction efficiency. Under optimized conditions, the calibration curve was linear in the range of 0.5-15.0 ng/mL with a regression coefficient of 0.9948, 0.9958, and 0.9931 for fenitrothion, diazinon, and ethion, respectively. The obtained results showed that this analytical method would be useful for the analysis of fenitrothion, diazinon, and ethion in tap water with high precision and accuracy.

Starch as a green source for Fe3O4@carbon core–shell nanoparticles synthesis: a support for 12-tungstophosphoric acid, synthesis, characterization, and application as an efficient catalyst

12-Tungstophosphoric acid (PW) immobilized on carbon-coated Fe3O4 nanoparticles (Fe3O4@C-PW) was prepared through a combination of hydrothermal and chemical co-precipitation. The intermediate carbon layer, which was produced from starch as a green material, protects the magnetic core and also improves the dispersion and catalytic activity of the nanoparticles. Characterization of this catalyst was investigated by high resolution transmission electron microscopy (HRTEM), Fourier transform infrared spectroscopy (FT-IR), vibrating sample magnetometry, and the acidic properties were studied by NH3-temperature programmed desorption and potentiometric titration. The HRTEM image showed that the catalyst had a well-defined core–shell structure with an average particle size of 50 nm. The characterization data derived from FT-IR reveal that basic structure and geometry of the Keggin anion are preserved after synthesis of Fe3O4@C-PW. The as-prepared Fe3O4@C-PW was used as a nanocatalyst for the synthesis of various bis(indolyl)methanes and β-functionalized indoles in water. The catalyst can be recovered simply using an external magnetic field and reused several times without appreciable loss of its catalytic activity.

Synthesis of CNT@Fe3O4-C hybrid nanocables as anode materials with enhanced electrochemical performance for lithium ion batteries

We report a simple method to prepare hierarchical structures of carbon-coated Fe3O4 nanoparticles decorated on conductive multi-walled carbon nanotubes (CNTs) backbone as advanced anode materials for lithium ion batteries. The CNTs backbone serves as a shape template and conducting network to facilitate electron and lithium ion transport, while the carbon coating acts as a buffering layer to maintain the structural integrity of the electrode upon cycling. The prepared CNT@Fe3O4-C hybrid nanocables electrode exhibits excellent electrochemical performance with long-term cycling stability and high specific capacity of ∼1080mAhg−1 after 700 cycles at a current density of 500mAg−1, and good rate capability, which could be attributed to their unique structural features as well as the improved mechanical stability enabled by the outer carbon coating layer.

Graphene/carbon-coated Fe3O4 nanoparticle hybrids for enhanced lithium storage

A novel hierarchical nanostructure composed of carbon coated Fe3O4 nanoparticles with seed-like morphology distributed on graphene (G/Fe3O4@C) is prepared as an advanced anode.