Magnetic Fe Nanoparticles Research Articles

Highly-improved microwave absorption performance of LaFeO3/Fe@CNTs nanocomposites through in-situ synthesis of Fe@CNTs

In order to enhance the microwave absorption performance, the multi-phase nanocomposites composed of magnetic medium and carbon nanotubes (CNTs) is designed and developed based on impedance matching. In this paper, LaFeO3/Fe@CNTs nanocomposites are prepared in situ using LaFeO3 as catalysts and C2H2 as carbon sources with CVD method, and then the microstructures, magnetic properties and microwave absorption performance are investigated in detail. The specific surface area of LaFeO3/Fe@CNTs nanocomposites increases greatly from 16.39 m3/g for LFC0 to 52.29 m3/g for LFC5 with the increasing CNTs content due to the enhanced heterogeneous interfaces. Ms also increases from 0.68 emu/g for LFC0 to 10.24 emu/g for LFC5 from magnetic Fe nanoparticles. LFC5 exhibits the best microwave absorption properties with the minimum reflection loss of −38.758 dB and a broad effective absorption bandwidth of 2.32 GHz at 2.5 mm. Impedance matching is balanced by permittivity from CNTs and permeability from Fe nanoparticles. Owing to the conductive CNTs with more defects, the dielectric loss and eddy current loss both increases to some extent. The synergistic loss mechanism of magnetic Fe nanoparticles and dielectric CNTs result in impedance matching and outstanding microwave attenuation.

Magnetic bimetallic nanoparticles confined growth for enhancement of electromagnetic loss in void@Fe@SiO2/Co/C particles

The dispersion of diverse magnetic metallic in a single particle plays an important role in microwave absorption; however, its contribution is not clear due to the challenge of controllable synthesis of magnetic bimetallic nanoparticles in one micro/nanostructure. Herein, a series of magnetic bimetallic nanoparticles separately confined growth in a hollow multi-shell microsphere with proper impedance matching characteristic were prepared, which can be used as theoretical models to elucidate magnetic coupling effect between diverse magnetic metallic nanoparticles in a single particle on electromagnetic attenuation. The coupling effect of magnetic Co and Fe nanoparticles dispersed in different shell effectively enhance the microwave absorption performance of void@Fe@SiO2/Co/C particles with minimum reflection loss (RLmin) of −62.3 dB (RL=-20 dB, 99 % absorption) at a thickness of 2.05 mm, provoking the maximum radar cross-section (RCS) reduction value of perfect electric conductor (PEC) 37.37 dBm2. Meanwhile, broad effective bandwidth (EBW, RL≤-10 dB, ≥90 % absorption) response of 7.04 GHz at a thickness of 2.44 mm was achieved. These findings can provide guidance for the designation of novel magnetic broadband microwave absorbing materials (MAMs).

A dual-mode sensing system based on carbon quantum dots and Fe nanozymes for the detection of α-glucosidase and its inhibitors

In this research, a sensitive fluorometric and colorimetric dual-mode sensing platform based on nitrogen-doped carbon quantum dots (NCDs) and magnetic Fe nanoparticles with peroxidase-like activity (Fe nanozymes, Fe NZs) was established, and was further applied for the detection of α-glucosidase (α-glu) and its inhibitors. The ⋅OH that produced by H2O2 catalyzed by Fe NZs can oxidize the colorless diammonium 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonate) (ABTS) to green oxABTS, and a noticeable absorption peak at 417 nm appeared. Simultaneously, oxABTS can quench the fluorescence of NCDs at 402 nm via fluorescence resonance energy transfer (FRET). 2-O-α-D-glucopyranosyl-L-ascorbic acid (AAG) can be decomposed by α-glu to glucose and ascorbic acid (AA), AA can prevent the oxidation of ABTS, resulting in the absorption at 417 nm decreased. Moreover, the quenching effect of oxABTS on NCDs is weakened, and the fluorescence at 402 nm is restored. Therefore, based on the change of absorption at 417 nm and fluorescence at 402 nm, the fluorometric and colorimetric dual-mode sensing method can be used for the determination of acarbose and voglibose that are the inhibitors of α-glu.

Heterogeneous Interface Engineering of Bi‐Metal MOFs‐derived ZnFe2O4–ZnO‐Fe@C Microspheres via Confined Growth Strategy Toward Superior Electromagnetic Wave Absorption

AbstractHeterogeneous interface regulation plays an important role in tailoring the intrinsic electromagnetic (EM) properties for obtaining excellent EM wave absorption, which still faces huge challenge. In this work, bi‐metal MOFs‐derived ZnFe2O4–ZnO‐Fe@C (ZZFC) microspheres with custom‐built heterogeneous interfaces are successfully fabricated via a confined growth strategy. Bi‐metal Fe–Zn–ZIF with tailored coordination structure and chemical bonding are first selected as the precursor template. After undergoing the annealing process, the metal Fe2+ host is converted into magnetic Fe nanoparticles (NPs). The Zn2+ host is transformed into semiconductor zinc oxide (ZnO) with increasing (101) crystal‐oriented growth. At the same time, metal hosts Fe2+ and Zn2+ are further reacted to synthesize the zinc ferrite (ZnFe2O4). Formed Fe nanoparticles catalyze organic ligands to constitute graphitized carbon layers, which confine the further growth of ZnFe2O4, ZnO, and Fe NPs. Combined with the well impendence and synergy absorption mechanism (magnetic loss, interface polarization, and conduction loss), optimized magnetic–dielectric ZnFe2O4–ZnO‐Fe@C microspheres exhibit outstanding EM wave absorption with the minimum reflection loss −66.5 dB at only 2.0 mm thickness. Bi‐metal MOF‐derived magnetic–dielectric absorption materials with tailored heterogeneous interfaces provide a new sight to design an efficient EM wave absorption system.

Green Synthesis of Magnetic Nanoparticles from Oldenlandia diffusa: Characterization and Therapeutic Activities

This study investigated green synthesis of magnetic nanoparticles (MNP) using Oldenlandia diffusa, its cauterization, and therapeutic propertieson liver cancer cells via an in-vitro approach. Anti-cancer, anti-oxidant, and anti-diabetic properties of MNP were evaluated. Synthesis of MNP was confirmed via UV-visible spectroscopy. Oldenlandia diffusa MNP (20–40 nm) showed absorption peak at 327 nm in UV-visible, XRD, EDX and FTIR spectral analysis. MNP were monoclinic, and rhombohedral with two stretching peaks at 646 cm−1, and 1098 cm−1 confirming Fe–O–Fe mode and Fe = O due to the iron element. IC50 values for MNP (IC50 74 μg/ml & 58 μg/ml) using DPPH and ABTS methods were high as compared to aqueous leaf extract of Oldenlandia diffusa confirming anti-oxidant properties. MNP exhibited α-amylase inhibitory activity with maximum inhibition of 82.17±0.82 μg/ml for α-glucosidase inhibitory action of 84.82±0.89 μg/ml. MNP showed dose-dependant in-vitro tumor suppression activity against HepG2 cells (16.08% at 150 μg/ml and 28.31% at 150 μg/ml). MNP also demonstrated anti-leishmanial activity at 400 g/ml (74.26±0.82 g/ml for promastigotes and 69.40±0.69 μg/ml for amastigotes). Oldenlandia diffusa actively bonded with magnetic Fe-nanoparticles and suppressed the growth of HepG2 cells. It demonstrated anti-cancer, antioxidant, anti-leishmanaland anti-diabetic activities. Thus, Oldenlandia diffusa is a potential anti-cancer therapeutic drug for liver cancer.

Wax appearance temperature study of model waxy oils: influence of nanofluids prepared with iron magnetic nanoparticles

Wax deposition creates many problems in the crude oil production, storage and transportation. The present work is in line with the efforts being made to address wax deposition issues. Nanofluids were prepared with different concentrations of the Fe-magnetic nanoparticles (Fe-MNPs). The same were used to monitor the wax appearance temperature (WAT) of the model waxy oil samples through pour point and differential scanning calorimetry in comparison to the control sample. The effect of increase in the amount of nanofluid and concentration of the Fe-MNPs in the nanofluid had the synergistic effect and the nanofluid prepared with 5% Fe-MNPs exhibited the most positive effect on the reduction of pour point. The results demonstrated that the nanofluid decreased the WAT and increased the flowability and could be used successfully as potential flow improver for real crude oils in industry for controlling the wax deposition issues.

Exploration of magnetic media modulation engineering on heterogeneous carbon spheres for optimized electromagnetic wave absorption

Magnetic carbon spheres are promising electromagnetic wave (EMW) absorbing materials due to their strong electromagnetic coupling effect. In the present work, magnetic carbon spheres composed of N-doped carbon spheres (NCSs) with magnetic Fe and Fe3C (Fe-Fe3C) nanoparticles were synthesized and the contents of Fe nanoparticles were adjusted through dilute hydrochloric acid treatment processes. The prepared NCSs/Fe-Fe3C composites dominate excellent EMW absorption performances with an optimal reflection loss value reaching − 63.77 dB at 9.92 GHz under a matching thickness of 2.9 mm, and the effective absorption bandwidth (EAB) reaches 4.88 GHz. The excellent absorption performance can be attributed to the synergistic effect of conductance loss, polarization loss, and magnetic loss arising from the different components of the composites. Moreover, the variation of Fe contents can regulate the dielectric and magnetic permeability characteristics of NCSs/Fe-Fe3C composites, and finally balance the impedance matching and attenuation coefficient. Our results pave the way for the development of high-efficiency EMW absorbing materials and clarify the regulation mechanism of magnetic media on the absorption performances of magnetic carbon spheres.

Lewis acidic molten salts etching route driven construction of double-layered MXene-Fe/carbon nanotube/silicone rubber composites for high-performance microwave absorption

Transition metal carbide/nitride (MXene) materials have triggered intensive research interest in the field of microwave absorption (MA). However, the complicated fabrication process and monotonous loss mechanism of MXene materials seriously hinder their practical applications. Here, we first developed a green and facile synthesis of dielectric-magnetic MXene-Fe nanocomposites via one-step Lewis acidic molten salts etching, which were combined with carbon nanotube (CNT) filler and silicone rubber (SR) matrix to fabricate double-layered MXene-Fe/CNT/SR composites by casting and curing. The in-situ growth magnetic Fe nanoparticles on MXene and unique double-layered structure composed of MXene-Fe/SR as the upper absorption layer and CNT/SR as the bottom reflection layer imparted the composites with excellent MA properties by offering appropriate impedance matching, strengthened internal reflection, polarization, magnetic loss, and conductive loss. Accordingly, the proposed double-layered composites showed superior MA properties compared with other MXene-based composites. The MXene-Fe-45%/CNT-5%/SR sample showed a reflection loss value of −65.9 dB at 12 GHz and an effective absorption bandwidth up to 8.24 GHz at 2.86 mm thickness. The double-layered composites exhibited tunable absorption frequency between the whole Ku-band and X-band by simply regulating the sample thicknesses and filler contents. These features indicate that the developed double-layered MXene-Fe/CNT/SR composites have great potential for high-performance MA applications. This study offers a novel and simple strategy to develop high-efficiency and broadband MA materials.

Adsorption and Microscopic Analysis of Arsenate Uptake by Magnetic Fe Nanoparticles: a Detailed Study on Coexisting Anions Effects

Adsorption and Microscopic Analysis of Arsenate Uptake by Magnetic Fe Nanoparticles: a Detailed Study on Coexisting Anions Effects

Excellent microwave absorption performance of PAN-based Fe/C nanofibers with low loading fillers

Carbon/magnetic metal composites have attracted great interest in the microwave absorption field. Here, polyacrylonitrile (PAN)-based Fe/C nanofibers were fabricated through electrospinning in combination with high-temperature carbonization, which was used as difunctional dielectric and magnetic microwave absorbing materials. The Fe/C nanofibers fabricated were characterized by a high aspect ratio, and magnetic Fe nanoparticles had uniform distribution within dielectric carbon fibers. The Fe/C nanofibers had prominent performance in absorbing microwave because of favorable impedance matching condition, improved capability in attenuating microwave and synergistic influence between dielectric loss of PAN-based carbon materials and magnetic loss of Fe, which was correlated with the carbonization temperature as well as Fe content. The optical Fe content of 5 wt%, carbonization temperature of 1200 ℃, Fe/C/paraffin composites containing 10 wt% fillers had high performance in absorbing microwave, the reflection loss reaching the maximum of |RLmax| = 40.47 dB at 9.36 GHz at 2.5 mm matching thickness, as well as the effective bandwidth (EAB) of 4.64 GHz (13.36–18 GHz), covering 12.88–16.88 GHz at 1.6 mm thin thickness, which nanofibers were easy to obtain and were characterized by strong performance in absorbing microwave, thin thickness and light weight. Thus, the fabricated nanofibers can be recognized as a promising microwave absorber.

Magnetically Enhanced Thermoelectric Performance of Ti0.75NiSb+x mol % Fe (x = 0-5) Nanocomposites.

Ti0.75NiSb is a half-Heusler compound with low lattice thermal conductivity due to a large number of cation vacancies. However, the higher carrier concentration limits the improvement of its thermoelectric performance. In this paper, magnetic Fe nanoparticles with a size of 30 nm are composited into Ti0.75NiSb in the form of the second phase. The charge transfer between Fe nanoparticles and Ti0.75NiSb leads to a decrease in carrier concentration. The strong interaction between the magnetic moment and carriers enhances the electron scattering, so that the scattering factor increases and the mobility decreases. The combined effect results in an increase of about 10% in the Seebeck coefficient and a decrease by about 14% in the electronic thermal conductivity at 873 K for the composite Ti0.75NiSb+2 mol % Fe. Meanwhile, the magnetic Fe nanoparticles provide additional scattering centers, leading to a decrease in lattice thermal conductivity. As a result, a zT value of 0.4 at 873 K is achieved for the composite Ti0.75NiSb+2 mol % Fe, which is 21% higher than that of Ti0.75NiSb. This work demonstrates that the compositing magnetic nanoparticles Fe can enhance the thermoelectric performance of Ti0.75NiSb.

Fe/Fe3O4/biomass carbon derived from agaric to achieve high-performance microwave absorption

Recently, biomass carbon materials as electromagnetic wave-absorbing materials have received widespread attention due to their easy availability, low cost, and environmental friendliness. However, for the vast majority of microwave absorbing materials that possess only dielectric losses, it is difficult for them to achieve satisfactory microwave absorbing performance. This paper proposes a new strategy to prepare a magnetic biomass composite material with tunable high-performance microwave absorption using agaric as the biomass carbon precursor and ferric nitrate as the magnetic precursor. When the carbonization temperature is 800 °C, the Fe/Fe3O4/biomass carbon (Fe/Fe3O4/BC) composite exhibits excellent microwave absorption performance in the X-band. At a thickness of 2.06 mm and a frequency of 9.63 GHz, its minimum reflection loss reaches −30.41 dB, and the effective absorption bandwidth is 2.45 GHz. In the carbonization process, ferric nitrate is transformed into magnetic Fe3O4 and Fe nanoparticles. The magnetic losses generated by Fe/Fe3O4 and the dielectric losses of biomass carbon, interfacial polarization, dipole polarization and multiple reflection synergies improve the impedance matching characteristics of the composite and improve the microwave absorption performance. Therefore, the prepared Fe/Fe3O4/BC composite material has exhibits great potential as a high-efficiency microwave absorber.

Enhanced Thermoelectric Performance of GeTe-Based Composites Incorporated with Fe Nanoparticles.

Incorporated nanoscale phases in thermoelectric (TE) materials can optimize the electronic and thermal transport properties to obtain high-performance TE materials. The rapid spark plasma sintering (SPS) technique is adopted to synthesize Ge0.96Bi0.06Te composites incorporated with soft magnetic Fe nanoparticles (nano-Fe) and their thermoelectric performance is researched in this study. With the phase transition of the Ge0.96Bi0.06Te matrix from the low-temperature rhombohedral phase to the high-temperature cubic one, the interface contact between Ge0.96Bi0.06Te and nano-Fe is transformed from Schottky contact to Ohmic one, which improves its electronic transport performance at high temperatures. At the same time, the additional Fe nanoprecipitation phonon scattering can reduce the lattice thermal conductivity to ∼0.66 W m-1 K-1. These mechanisms result in a high ZT value of 1.65 and a relatively highquality factor B of 1.05 at 785 K for Ge0.96Bi0.06Te/2 mol % Fe. This work suggests that the thermoelectric performance of composite materials can be enhanced by introducing a variable interface band structure.

The Low Temperature Synthesis of Very Small and Non‐Crystalline Iron‐Based Nanoparticles: Application in Alkene Hydrosilylation

AbstractThis work describes the synthesis of very small non‐crystalline and non‐metallic iron‐based nanoparticles in solution from easily accessible commercial products in mild conditions. These colloidal suspensions were further used to generate well‐defined solids containing metallic iron or iron oxide NPs. While classical magnetic and crystalline Fe nanoparticles are inactive in alkene hydrosilylation, such original NPs were active in 1‐octene hydrosilylation with 1,1,1,2,3,3,3‐heptamethyltrisiloxane (MD'M) showing that the non‐crystallinity and the organometallic character of the starting Fe NPs are an asset to generate a specific catalytic activity.

Ultra-fast colorimetric detection of glutathione by magnetic Fe NPs with peroxidase-like activity

The nanozymes-based sensing platforms have been attracted in recent years due to their outstanding performances in the practical applications. In this work, the magnetic Fe nanoparticles (NPs) with peroxidase-like activity was developed for the fast detection of glutathione (GSH). The Fe NPs were facilely prepared through the reduction of iron trichlorrde hexahydrate (FeCl3‧6H2O) by sodium borohydride (NaBH4) at room temperature, exhibiting a merit of simplicity. Significantly, the achieved Fe NPs have high peroxidase-like catalytic activity. At the room temperature, the colorimetric substrates such as 3,3′,5,5′-tetramethylbenzidine (TMB) and 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) can be rapidly oxidized by Fe NPs with the help of H2O2. After incubated for just 30 s, the catalytic system could achieve a colored solution. Thus, the Fe NPs-based sensing systems can be employed in the development of the colorimetric biosensors with the naked-eye detection.

Decolorizing brilliant green by mesoporous Pd–Fe magnetic nanoparticles immobilized on reduced graphene oxide: artificial neural network modeling

The mesoporous Pd–Fe magnetic nanoparticles immobilized on the reduced graphene oxide were employed in the present work for the decolorization of toxic brilliant green in aqueous phase. The decolorization process was modeled using backpropagation artificial neural network and optimized by genetic algorithm and particle swarm optimization. These magnetic nanocomposites were synthesized by the two-step reaction in aqueous phase method and then characterized with various methods. According to response surface methodology, the effect of operating parameters on the decolorization of brilliant green in aqueous solution was studied through batch experiments. On the basis of these experiments, the prediction ability of response surface methodology and backpropagation neural network method was assessed. The decolorization process follows Freundlich isotherm and pseudo-second-order kinetics. Furthermore, thermodynamics studies demonstrate that the adsorption of brilliant green onto the nanocomposites was endothermic and spontaneous. Overall, these mesoporous nanomaterials have the advantages of strong adsorption capacity and fast decolorization for brilliant green, and modeling of the removal process with artificial neural network was successful.

Advanced characterization of biomineralization at plaque layer and inside rice roots amended with iron- and silica-enhanced biochar

Application of iron (Fe)- and silica (Si)-enhanced biochar compound fertilisers (BCF) stimulates rice yield by increasing plant uptake of mineral nutrients. With alterations of the nutrient status in roots, element homeostasis (e.g., Fe) in the biochar-treated rice root was related to the formation of biominerals on the plaque layer and in the cortex of roots. However, the in situ characteristics of formed biominerals at the micron and sub-micron scale remain unknown. In this study, rice seedlings (Oryza sativa L.) were grown in paddy soil treated with BCF and conventional fertilizer, respectively, for 30 days. The biochar-induced changes in nutrient accumulation in roots, and the elemental composition, distribution and speciation of the biomineral composites formed in the biochar-treated roots at the micron and sub-micron scale, were investigated by a range of techniques. Results of laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) showed that biochar treatment significantly increased concentrations of nutrients (e.g., Fe, Si, and P) inside the root. Raman mapping and vibrating sample magnetometry identified biochar particles and magnetic Fe nanoparticles associated with the roots. With Fe plaque formation, higher concentrations of FeOx− and FeOxH− anions on the root surface than the interior were detected by time-of-flight secondary ionization mass spectrometry (ToF-SIMS). Analysis of data from scanning electron microscopy energy-dispersive spectroscopy (SEM-EDS), and from scanning transmission electron microscopy (STEM) coupled with EDS or energy electron loss spectroscopy (EELS), determined that Fe(III) oxide nanoparticles were accumulated in the crystalline fraction of the plaque and were co-localized with Si and P on the root surface. Iron-rich nanoparticles (Fe–Si nanocomposites with mixed oxidation states of Fe and ferritin) in the root cortex were identified by using aberration-corrected STEM and in situ EELS analysis, confirming the biomineralization and storage of Fe in the rice root. The findings from this study highlight that the deposition of Fe-rich nanocomposites occurs with contrasting chemical speciation in the Fe plaque and cortex of the rice root. This provides an improved understanding of the element homeostasis in rice with biochar-mineral fertilization.

Green synthesis of magnetic nanoparticles via Cinnamomum verum bark extract for biological application

The green synthesis of magnetic Fe nanoparticles (NPs) was prepared via Cinnamomum Verum bark extract. The UV–vis analysis explained the formation of Fe NPs with SPR band at 288 nm. The powder X-ray diffraction analysis (XRD) explicated the mean crystallite size was at 36 nm. The Fourier Transform Infra-Red analysis (FTIR) revealed the functional groups in the prepared Fe NPs. The Scanning Electron Microscope (SEM) and High-Resolution Transmission Electron Microscope (HR-TEM) analyses notified the circular and spherical shaped Fe NPs with the size at 20−50 nm. The Energy dispersive X-ray spectroscopy (EDS) and mapping analyses validated the formation of Fe NPs with purity. The Vibrating Sample Magnetometer (VSM) revealed the paramagnetic behavior of prepared Fe NPs. The phytochemical analysis described the phytochemicals compounds which present in Cinnamomum Verum bark extract. The Antibacterial assay described the much higher inhibition zone of prepared Fe NPs upon human pathogenic bacteria. The Antioxidant (DPPH) assay described the efficient scavenging behavior of Fe NPs with 89 % at 80 μg/mL concentration. The Anti-inflammatory assay explicated the potential protein denaturation behavior of Fe NPs with 87 % at 500 μg/mL concentration. The Anti-diabetic assay reported the much higher potential efficiency of prepared Fe NPs with 84 % at 500 μg/mL concentration.

Magnetic Fe nanoparticle to decorate N dotted C as an exceptionally absorption-dominate electromagnetic shielding material

Conversional electromagnetic shielding material with strong reflection coefficient are becoming insufficient for today's application, since the serious 2nd electromagnetic pollution. Herein, we demonstrate a magnetic carbon based shielding material constructed by magnetic Fe nanoparticles (NPs) and N dotted amorphous carbon nanosphere (~200 nm). The structure, morphology, chemical composition of the samples have been studied in depth. It is observed that the average sizes of Fe NPs is ~8.0 nm and can be loaded well on the surface of N dotted amorphous spheres. The electromagnetic shielding performance has been investigated. Significantly, the as-prepared samples show excellent electromagnetic shielding performance. The maximum shielding effectiveness can up to 30 dB under a thickness of 1.2 mm. More importantly, the reflection coefficient can be reduced to 2.3 dB, presenting excellent absorptiondominate shielding performance. The desirable shielding mechanism with less reflection are attributed to the boosted loss ability and matched impedance matching behavior, which originate from N doping and magnetic component. This work which integrates magnetic component with N dotted amorphous carbon has been demonstrated as a useful strategy for the development of absorption dominate EM shielding material.

Highly enhanced electromagnetic wave absorption bandwidth based on reduced graphene oxide-Fe aerogel composites

In order to achieve large electromagnetic (EM) wave absorption bandwidth, reduced graphene oxide (rGO)-Fe aerogel composites were fabricated by hydrothermal method and subsequently heat treated under reduced atmosphere. The effects of Fe2+ content on the microstructures and EM wave absorbing properties of the aerogel composites have been studied. The Fe nanoparticles in the size of 50–100 nm deposited on the graphene sheets were responsible for the improvement in magnetic properties of the rGO aerogel composites. The absorbing performance could be tailored by varying the concentrations of Fe2+, and when the content of Fe2+ was 0.125 mmol, the absorption bandwidth reached 6.1 GHz with the thickness of 2.7 mm. The broad absorption bandwidth of rGO-Fe aerogel composites was ascribed to the synergistic effect of magnetic Fe nanoparticles, high dielectric loss of rGO, and the unique porous aerogel microstructures.