Magnetic Carbon Composites Research Articles

Pyramid-like magnetic carbon composites device toward tunable and adaptive radar-visible compatible properties

Equipped with intelligent adjustable electromagnetic-visible light compatibility characteristics is of significant importance in military stealth fields. In this work, a tunable microwave absorption and visible light change metamaterial based on polylactic acid (PLA) thermal stimulation was fabricated using 4D printing technology with hydroxylated carbon nanotubes (CNTOH) and carbonyl iron powder (CIP) as active ingredients. The printing filament was synthesized, which exhibited excellent absorption performance with a bandwidth of 5.83 GHz and sufficient shape recovery ability. On this basis, a temperature-dominated shape memory variation cone device was also manufactured and the visible light color-changing coating was sprayed. The microwave absorption performance is adjusted according to the petal angle, achieving a bandwidth variation of 5.9–9.8 GHz. This work confirms the potential exploratory value of the designed shape memory polymer in the field of microwave absorption, and provides unlimited possibilities for designing intelligent controlled stealth materials.

Magnetic carbon composites derived from biomass with excellent microwave absorption capacity

It is well known that magnetic iron oxide (Fe3O4) and carbon-based materials are good microwave absorbing materials. However, the frequency bands in which Fe3O4 absorbs electromagnetic waves are usually concentrated in the low-frequency region, whereas carbon materials are in the high-frequency region. Therefore, this study aims to deal with the limitation of the absorption bands of these two substances. In this work, this Fe3O4/C composite with high performance microwave absorption was successfully adoption of hydrothermal-calcination process using mangosteen shells as a biomass carbon material, and with a thickness of 1.97 mm, the optimal reflection loss of the sample can reach −67.49 dB, and the frequency band that can be absorbed is 4.32 GHz. The interface polarization, dipolar polarization and eddy current loss in Fe3O4 and carbon materials produce synergistic effects, and the porous conductive network increases the electromagnetic wave transmission path and generates conductive losses, which results in composites with excellent electromagnetic wave absorption properties. The findings indicated that a composite compound of Fe3O4 and carbon-based material was successfully synthesized by hydrothermal method and obtained a materials with outstanding electromagnetic wave absorption properties and high absorption bandwidth.

Preparation of nitrogen-doped reduced graphene oxide/zinc ferrite@nitrogen-doped carbon composite for broadband and highly efficient electromagnetic wave absorption

Traditionally reduced graphene oxide (RGO)-based electromagnetic wave (EMW) absorbing materials have poor absorption effectiveness due to impedance mismatch caused by skin effect. The introduction of structural defects and the design of heterogeneous interfaces play a crucial role in enhancing the polarization effect of EMW absorbers. In this study, nitrogen-doped reduced graphene oxide/zinc ferrite@nitrogen-doped carbon (NRGO/ZnFe2O4@NC) ternary composite with rich heterogeneous interfaces is constructed by combining solvothermal reaction, in-situ polymerization, annealing treatment with subsequent hydrothermal reaction. The research results have shown that the obtained NRGO/ZnFe2O4@NC ternary composite exhibits a unique core-shell structure and excellent EMW absorption performance. At a thickness of 2.61 mm, the maximum effective absorption bandwidth can reach 7.2 GHz, spanning the entire Ku-band and a portion of the X-band, and the minimum reflection loss is –61.1 dB, which is superior to most reported RGO-based EMW absorbers. The excellent EMW absorbing ability is mainly ascribed to the optimized impedance matching and the enhanced polarization loss caused by the abundant heterogeneous interfaces and structural defects derived from heteroatomic nitrogen doping. Furthermore, the radar cross section in the far field is simulated by a computer simulation technique. This study provides a novel way to prepare core-shell magnetic carbon composites as highly efficient and broadband EMW absorbers.

Exploring the Microstructural Effect of FeCo Alloy on Carbon Microsphere Deposition and Enhanced Electromagnetic Wave Absorption.

The rational design of magnetic carbon composites, encompassing both their composition and microstructure, holds significant potential for achieving exceptional electromagnetic wave-absorbing materials (EAMs). In this study, FeCo@CM composites were efficiently fabricated through an advanced microwave plasma-assisted reduction chemical vapor deposition (MPARCVD) technique, offering high efficiency, low cost, and energy-saving benefits. By depositing graphitized carbon microspheres, the dielectric properties were significantly enhanced, resulting in improved electromagnetic wave absorption performances through optimized impedance matching and a synergistic effect with magnetic loss. A systematic investigation revealed that the laminar-stacked structure of FeCo exhibited superior properties compared to its spherical counterpart, supplying a higher number of exposed edges and enhanced catalytic activity, which facilitated the deposition of uniform and low-defect graphitized carbon microspheres. Consequently, the dielectric loss performance of the FeCo@CM composites was dramatically improved due to increased electrical conductivity and the formation of abundant heterogeneous interfaces. At a 40 wt% filling amount and a frequency of 7.84 GHz, the FeCo@CM composites achieved a minimum reflection loss value of -58.2 dB with an effective absorption bandwidth (fE) of 5.13 GHz. This study presents an effective strategy for developing high-performance EAMs.

A novel lignin-steel sludge composite for dyes adsorption from water: Surface functionalities and structural alteration mechanisms

The study focuses on fabricating and utilizing a lignin-steel sludge magnetic carbon composite (SLNa) to efficiently remove two dyes from an aqueous medium. The SLNa composite was fabricated through a simple two-step strategy involving the activation and thermal treatment of lignin and steel sludge. The SLNa possessed lignin and steel sludge starring properties, viz. abundant surface functionalities, graphitic carbon matrix, and magnetic characteristics. The synergistic combination of lignin and steel sludge resulted in composite's high adsorption potential for Methylene Blue (MB; 153.92 mg/g) and Acid Orange 7 (AO7; 64.84 mg/g) in batch mode. Additionally, the rapid adsorption kinetics and effective dye removal for MB (> 99 %) and AO7 (72 %) from simulated effluent revealed the potential of fabricated adsorbent for water remediation. Furthermore, the composite's applicability for continuous adsorption was also evaluated through a series of dynamic flow experiments using fixed-bed column systems. The demonstrated efficacy of SLNa, viz., 48.18 and 15.00 mg/g for MB and AO7, respectively, at high adsorbent loading and lower dye concentrations, highlights its potential for scalable water treatment applications. Thus, the versatility and effectiveness of the novel composite underscore its potential for practical application in both batch and continuous water remediation processes.

A simple melamine-assisted cellulose pyrolysis synthesis of magnetic and mesoporous N-doped carbon composites with excellent adsorption of Congo red

A magnetic and mesoporous metal/N-doped carbon composite is prepared using a melamine-assisted pyrolysis method of hydroxypropyl methylcellulose with Fe(NO3)3. The magnetic composite has a 3D hierarchical structure composed of 1D nanostructure interlaced with each other and a large pore volume distributed mainly in mesopores. Meanwhile, its N-doped carbon surface with sp2 hybridized structure is positively charged due to the promotion action of its mixed Fe phase, Fe3C and Fe3N, inducing the production of electron deficient conjugated structures as electron acceptors. Its characteristic microstructure determines that the adsorption of anionic Congo red on its surface is achieved mainly through multiple adsorption mechanisms of electrostatic and π-π interaction. Thus, the magnetic composite has an excellent dye adsorption capacity, even improved dramatically at high pH conditions, and simultaneously, the spent composite is quickly separated from wastewater solution by using its magnetic properties. In contrast, these undoped or N-doped carbon composites prepared in the absence of melamine and Fe salts have very poor or partially improved adsorption efficiencies to the Congo red dyes due to their inactive characteristic microstructures, such as lower pore volume, more microporous structures and negatively charged mesoporous surface.

Efficient and low-cost mesoporous magnetic carbon composites derived from date palm stones for environmental remediation of hexavalent chromium

This study was performed to achieve two important scientifically challenging goals, environmental remediation of toxic heavy metals and utilization of agricultural lignocellulosic wastes. In this work, a series of mesoporous magnetic carbon (MMC) adsorbents were synthesized by carbothermic reduction at different temperatures employing date palm (Phoenix dactylifera L.) stones as the carbon source. The synthesized adsorbents were characterized by different technquies and the results confirmed the presence of zero-valent iron (ZVI) nanoparticles and other iron oxides as products of the carbothermal reduction. The nature of phases present, crystallite size and the surface properties were found to be dependent on the calcination temperature. The adsorbent MMC700 exhibited the smallest (ZVI) crystallite size 36 nm and the largest SBET 341 m2/g. All adsorbents showed mesoporous structure with mesopore average diameter lower than 6 nm. The performance was evaluated in the removal process of toxic Cr(VI) in an aqueous medium, and the optimum conditions of the process were reported. The removal process was dependant of solution pH where best results was achieved at pH = 2. Complete removal of chromium was achieved in less than 5 min by MMC700. The results were better fitted with pseudo-second-order kinetics and followed the Freundlich model isotherm. The maximum adsorption capacity was found to be 265.25 mg/g for MMC700, suggesting its application as an efficient, low-cost, and easily separable adsorbent for the toxic Cr(VI) removal process. The prepared adsorbents exhibited superior performance in the removal process compared to other agricultural wastes or biomass - derived adsorbents reported in literature.

Magnetically recyclable mesoporous carbon/zirconia composites for highly efficient removal of Cr(III) organic complexes from high salinity water: adsorption behavior and mechanism

ABSTRACT In this study, zirconia-functionalized magnetic core-shell mesoporous carbon composites (Fe3O4@C-ZrO2) were synthesized for the effective removal of Cr(III)-EDTA in high-salinity wastewater. Fe3O4@C-ZrO2 with Fe3O4 as a magnetic core and ZrO2 embedded in a mesoporous carbon skeleton were prepared by the sol-gel method in the nano-casting stage, which can be magnetically separated. The presence of ZrO2 on the adsorbents enhanced the adsorption of Cr(III)-EDTA and the maximum adsorption capacity of Fe3O4@C-ZrO2 was 16.21 mg·g−1 at pH = 3.0, which is remarkably higher than that of Fe3O4@C (3.65 mg·g−1). Fe3O4@C-ZrO2 has a strong anti-interference capability for cations in water, which can exhibit effective adsorption properties in presence of high concentration cations and anions (80 mmol·L−1) and high salt/complexant agent environments. Cr(III)-EDTA removal by adsorption of Fe3O4@C-ZrO2 was mainly through the formation of ternary complexes between ZrO2 in Fe3O4@C-ZrO2 and carboxylic acid groups in Cr(III)-EDTA. The Cr(III)-EDTA saturated Fe3O4@C-ZrO2 can be easily regenerated in 0.1 mol·L−1 NaOH than in 0.1 mol·L−1 HCl and still demonstrated an effective adsorption capacity for Cr(III)-EDTA after three repeated cycles. The results reflect the effective removal of Cr(III)-EDTA by Fe3O4@C-ZrO2 in high-salinity water, providing a new method for removing heavy metals in complex water.

Fabrication of graphene-based magnetic carbon composites derived from iron cobalt metal-organic framework as dual-band electromagnetic wave absorbers

The fabrication of advanced magnetic carbon electromagnetic wave (EMW) absorbers derived from metal-organic framework (MOF) with thin thickness, wide bandwidth, strong absorption strength and low filling ratio remains a huge challenge. In this paper, CoFe2O4/CoFe/C/Graphene composites were prepared by a simple two-step way of solvothermal reaction and carbonization treatment. The results of micromorphology analysis revealed that as the carbonization temperature increased, the obtained carbon frameworks changed from a spindle shape to dodecahedron-like shape and finally to a tile shape, and the carbonization temperature had a notable influence on the electromagnetic parameters and EMW absorption properties of the magnetic carbon composites. It should be noted that the obtained CoFe2O4/CoFe/C/Graphene composites exhibited comprehensive excellent EMW absorption performance when the carbonization temperature was 750.0 ℃ and the filling radio was only 15.0 wt%, namely the effective absorption bandwidth reached up to 4.8 GHz and the optimal minimum reflection loss was −40.2 dB at a thickness of 2.06 mm. A distinct dual-band (C band and Ku band) absorption feature was observed when the thickness exceeded or equaled 4.5 mm. Furthermore, the underlying electromagnetic dissipation mechanisms were also elucidated. Therefore, our results could provide a valuable reference for preparing excellent magnetic carbon EMW absorbers derived from MOF.

Interface engineering to develop heterogeneous spindle-shaped FeS2/NiS2@C nanorods for high-efficient microwave attenuation

With the rapid development of 5G communication technology, the accompanied radiation pollution by electromagnetic waves has become increasingly serious. Therefore, high-performance wave-absorbing materials need to be developed. In this paper, spindle-shaped hierarchical porous composites based on iron metal-organic frameworks (MOFs) coated with hydroxides (Fe3O4/Ni@C, FeS2/NiS2@C, and FeSe2/NiSe2@C) were synthesized. The porous structure with a large specific surface area promotes multiple scattering and reflection of electromagnetic waves, and the unique hierarchical core-shell structure induces interfacial polarization, which is beneficial to improving the absorption of electromagnetic radiation. The doping of heteroatoms can enhance the relaxation process of interfacial polarization and improve the dielectric properties to optimize the impedance-matching characteristics of the composites. In particular, the synergistic effect between the magnetic carbon multicomponent, sulfur doping, and hierarchical porous structure of the FeS2/NiS2@C composite significantly improves the microwave absorption performance of the material, and a minimum reflection loss (RLmin) of −59.4 dB at 3.2 mm with a filler loading of 20 wt% was obtained. This work provides a new way for the development of MOF-derived hierarchical magnetic carbon composites doped with strongly polarized elements.

Embedding Multiple Magnetic Components in Carbon Nanostructures via Metal-Oxo Cluster Precursor for High-Efficiency Low-/Middle-Frequency Electromagnetic Wave Absorption.

With the advent of wireless technology, magnetic-carbon composites with strong electromagnetic wave (EMW) absorption capability in low-/middle-frequency range are highly desirable. However, it remains challenging for rational construction of such absorbers bearing multiple magnetic components that show uniform distribution and favorable magnetic loss. Herein, a facile metal-oxo cluster (MOC) precursor strategy is presented to produce high-efficiency magnetic carbon composites. Nanosized MOC Fe15 shelled with organic ligands is employed as a novel magnetic precursor, thus allowing in situ formation and uniform deposition of multicomponent magnetic Fe/Fe3O4@Fe3C and Fe/Fe3O4 nanoparticles on graphene oxides (GOs) and carbon nanotubes (CNTs), respectively. Owing to the good dispersity and efficient magnetic-dielectric synergy, quaternary Fe/Fe3O4@Fe3C-GO exhibits strong low-frequency absorption with RLmin of -53.5 dB at C-band and absorption bandwidth covering 3.44 GHz, while ultrahigh RLmin of -73.2 dB is achieved at X-band for ternary Fe/Fe3O4-CNT. The high performance for quaternary and ternary composites is further supported by the optimal specific EMW absorption performance (-15.7 dB mm-1 and -31.8 dB mm-1) and radar cross-section reduction (21.72 dB m2 and 34.37 dB m2). This work provides a new avenue for developing lightweight low-/middle-frequency EMW absorbers, and will inspire the investigation of more advanced EMW absorbers with multiple magnetic components and regulated microstructures.

Selective and sensitive GC-MS analysis of carcinogenic N-nitrosodimethylamine in pharmaceuticals using a magnetic coconut carbon composite as a solid-phase extraction sorbent

The aim of the present research was to develop a magnetic coconut carbon composite (Fe2O3/Fe3O4@CNC) as a solid-phase extraction (SPE) sorbent for the analysis of carcinogenic N-nitrosodimethylamine (NDMA) in pharmaceuticals. Coconut composites modified with Fe2O3 and Fe3O4 were prepared and applied as SPE sorbent for the extraction of NDMA in pharmaceuticals. The sorbent was characterized with X-Ray, infrared spectroscopy and nitrogen porosimetry. The best ions for the Gas Chromatography-Mass Spectrometry with Selected Ion Monitoring (GC-MS/SIM) analysis were m/z 74 and 42 for NDMA, and m/z 80 and 46 for NDMA-d6 internal standard. System has offered great method performance in terms of sensitivity limit of quantitation (LOQ) 16 ng kg−1. The developed sorbent has enhanced the sensitivity and speed of analysis. The developed method was applied to authenticate the presence of NDMA in various pharmaceutical samples. Among the analyzed samples, NDMA impurities were relatively identified at high amounts in nizatidine samples. Highlights NDMA was verified in ranitidine, metformin and nizatidine Fe2O3/Fe3O4@CNC composite was used for NDMA identification without pretreatment SPE sorbent enhance sensitivity, reduce analysis time, sustain accuracy & precision High level of NDMA impurity were found in nizatidine pharmaceuticals.

Eco-friendly and magnetic sucrose-derived Fe-containing mesoporous carbon composites for high-efficiency Congo red adsorption and supercapacitor applications

In this study, eco-friendly and magnetic sucrose-derived Fe-containing mesoporous carbon (Fe-MC) composites have been prepared by carbothermal reduction. The Fe-MC3-1000 prepared from sucrose and FeSO4 with a mass ratio of 1:1 at 1000 °C has a uniform mesoporous structure with a BET surface area of 184 m2/g. The carbothermal reduction of Fe2O3 had dual effects of the pore-forming and the loading. Batch adsorption experiments and electrochemical measurements show that the Fe-MC3-1000 has the optimum performance in both adsorption and supercapacitor applications. For adsorption, the maximum adsorption capacity for Congo red (CR) arrived at 972.1 mg g−1 with a removal percentage of 97.2 %. The adsorption process has good agreement with Langmuir isotherm and Elovich kinetic models. Besides, the Fe-MC3-1000 exhibits good recyclability after five adsorption-desorption cycles. For supercapacitor, the Fe-MC3-1000 electrode has a capacitance value of 179.23 F g−1 and a capacitance retention of 92.8 % at 10 A g−1 after 2000 cycles. The outstanding adsorption and electrochemical performances suggest that the Fe-MC3-1000 is a competitive bi-functional material for adsorption and supercapacitor.

One-step synthesis of cobalt nanosheets depositing with carbon microsphere by microwave plasma assisted reduction chemical vapor deposition technique against electromagnetic pollution

The rational design of magnetic carbon composites in both composition and microstructure has significant potential for acquiring excellent electromagnetic wave absorbing materials (EAMs). In this study, Co@carbon magnetic composites were prepared by employing a novel microwave plasma assisted reduction chemical vapor deposition (MPARCVD) technique, which was highly efficient, low-cost, and energy-saving. The depositing of graphitized carbon microspheres on the surface of Co nanosheets could enrich the available loss mechanisms. Furthermore, the lamelliform morphology with a large aspect ratio of the composites was beneficial to subtly improve the dielectric properties under a low filler content. As a consequence, the minimum RL reached up to −65.7 dB and the radar cross-sectional area reduction attained to 22.3 dBm 2 with only 20 wt% loading content. The MARCVD technology opened a novel strategy and avenue for acquiring magnetic carbon composites as candidates for lightweight and high-performance EAMs.

Preparation of size-tunable Fe3O4 magnetic nanoporous carbon composites by MOF pyrolysis regulation for magnetic resonance sensing of aflatoxin B1 with excellent anti-matrix effect

Magnetic nanoporous materials represent a new emerging category of magnetic materials for construction of magnetic resonance sensors. In this study, we adopted the metal–organic framework materials, MIL-101(Fe), as the precursor to prepare series nanoporous-carbon-Fe3O4 (NPC-Fe3O4) composites. Results showed that Fe3O4 were uniformly distributed in MIL-101(Fe) and the size of MNP was precisely tuned at different pyrolysis temperatures, conferring the optimal NPC-Fe3O4-450 °C composite with dramatically improved T2 relaxivity. The NPC-Fe3O4-450 °C composite was modified with antibodies and antigens, respectively, for detection of aflatoxin B1 in various food samples with complicated matrix. Range from 0.010 ng mL−1 to 2.0 ng mL−1, extreme low detection limit of 5.0 pg mL−1, and satisfied recoveries were successfully achieved, indicating excellent anti-matrix effect. These findings offer a new dimension to engineer novel magnetic materials with improved relaxivity for simple and easy sensing of food hazards in complicated food matrix without any purification or separation procedures.

Magnetic Nitrogen-Doped Carbon Composites Decorated with Carbon Nanotubes for Adsorption of Malachite Green

Magnetic Nitrogen-Doped Carbon Composites Decorated with Carbon Nanotubes for Adsorption of Malachite Green

Magnetic Carbon Nanocomposites: Preparation from Cellulose via Chemical Activation with FeCl3 and Characterization

We have studied the preparation of magnetic graphitic carbon composites, which combine the adsorption properties of activated carbon with magnetic properties and properties intrinsic to graphite. The preparation method is efficient; it comprises modifying flax shive cellulose with citric acid to enhance the chelating ability of the flax shive cellulose matrix, impregnating the modified cellulose with iron chloride, and pyrolysis in an inert atmosphere to control the composition, morphology, specific surface, and porosity of hybrid carbon materials. The scenario of cellulose matrix pyrolysis was suggested using thermogravimetry. X-ray structural analysis was used to characterize the graphitic composites. The citric acid modification of cellulose helps to prepare a high-graphite (74%) carbon composite where the graphitization level of the graphite structure approaches the graphitization level of commercially available graphite at 700°С. Low-temperature N2 adsorption–desorption and ζ-potential measurements helped to suggest the adsorption mechanism for environmentally hazardous dyes. The greatest equilibrium adsorption of Methylene Blue (MB) and Methyl Orange (MO) dyes was 127.4 and 23.7 mg/g, respectively. The prepared composites can be used as adsorbents and fillers in polymer composite materials.

Synthesis of magnetic carbon composite by diesel engine and its application to dye removal

We report a one-step and efficient method to synthesize magnetic diesel particles (MDPs) and their application toward dye removal. The MDPs were obtained by the combustion of ferrocene-doped diesel fuel using an internal combustion engine. The diesel particles combined with ferrocene as a metal source were collected by an electrostatic precipitator. The thermogravimetric analysis confirmed the ferrocene-based catalyst and thermal stability of MDPs. FE-SEM showed irregular and aggregated morphologies, and the presence of iron oxide phases (Fe4O3 and γ-Fe2O3) was confirmed by X-ray diffraction analysis. The characteristics of MDPs as an adsorbent for organic pollutants were evaluated by methylene blue (MB) adsorption experiments. Langmuir isotherm and pseudo-second-order models best interpret the adsorption process and kinetics, respectively, with a maximum adsorption capacity of 40.81 mg/g of MB adsorbed on the surface of magnetic diesel particles.

Research progress of novel magnetic two-dimensional carbon composites in photocatalytic degradation of pollutants: a review.

With the improvement of economic level and the development of science and technology, the problem of water pollution needs to be solved now. Various water pollutants have a negative impact on nature and restrict its development. In recent years, photocatalysis is considered to be a promising wastewater treatment method. Two-dimensional carbon materials have become the hotspot of photocatalytic degradation of pollutants because of their excellent conductivity, large specific surface area, and good hydrophilicity. Nevertheless, it is very hard for these photocatalysts based on carbon materials to separate and recover from the system. For solving such a problem, the composition with magnetic components is an effective way which can facilitate separation and keep the catalytic activity of the samples. In this review, the main roles of magnetic carbon-based composites in the field of pollutant degradation are introduced, and their synthesis technology, classification, and application are summarized. In the end, the current challenges and prospects in this field are involved, aiming to provide useful insights and enlightments into the fields of pollutant treatment and photocatalytic degradation.

Magnetic Cu/Co nanoparticles supported on nitrogen‐doped porous carbon derived from Cu/Co@aZIF: Investigation of catalytic activity and structural properties

By calcining copper‐doped amorphous zeolitic imidazolate framework (Cu/Co@aZIF), a novel magnetic nanoporous carbon composite (Cu/Co@NPC) material was produced, characterized by different spectroscopic techniques, and used for the first time as an efficient catalyst for the azide‐alkyne cycloaddition (AAC) reaction and the reduction reaction of nitrophenol (RRN) under air in water. With this catalyst, the AAC and RRN reactions were conducted in aqueous solutions, and good to excellent yields of related products were synthesized in a short reaction time. The potential of the magnetic Cu/Co@NPC nanocatalyst for targeting RRN and AAC reactions was uncovered by studying specific substrates for RRN and AAC reactions. The Cu/Co@NPC magnetic nanocatalyst is recyclable at least five times, with just a drop of 6% and 22% in catalytic efficiency in RRN and AAC, respectively.