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1.
Ferromagnetic metal nanoparticle/graphene nanocomposites are promising as excellent electromagnetic (EM) wave absorption materials. In this work, we used a facile method to synthesize a cobalt nanoparticle–graphene (CoNP–G) nanocomposite. The obtained CoNPs–G exhibited a saturation magnetization (Ms) of 31.3 emu g−1 and a coercivity (HC) of 408.9 Oe at 298.15 K. In particular, the CoNPs–G nanocomposite provided high-performance EM wave absorption with multiband, wide effective absorption bandwidth, which was mainly attributed to the synergy effects generated by the magnetic loss of cobalt and the dielectric loss of graphene. In the range of 2–18 GHz, the sample (55 wt% CoNPs–G) held three effective reflection loss (RL) peaks (frequency ranges of 2.4–3.84, 7.84–11.87 and 13.25–18 GHz, respectively, RL ≤ −10 dB) with the coating thickness of 4.5 mm, and the effective bandwidth reached the maximum of 10.22 GHz, and the minimal RL reached −40.53 dB at 9.50 GHz. Therefore, the CoNPs–G nanocomposite presents a great promising application in the electromagnetic wave absorption field.Ferromagnetic metal nanoparticle/graphene nanocomposites are promising as excellent electromagnetic (EM) wave absorption materials. 相似文献
2.
Jixing Chai Deqing Zhang Junye Cheng Yixuan Jia Xuewei Ba Ya Gao Lei Zhu Hao Wang Maosheng Cao 《RSC advances》2018,8(64):36616
Two-dimensional (2D) MoS2/graphene nanosheet (MoS2/GN) hybrids have been demonstrated to be promising microwave absorption (MA) materials due to their unique chemical and physical properties as well as rich impedance matching. However, the reported strategies for preparing MoS2/GN hybrids have limited their application potential due to the complex, high-cost and inefficient preparation processes. On the other hand, it is of note that the main source of graphene is based on converting insulating graphene oxides (GO) back to conductive reduced graphene oxides (RGO). Thus, the MA performance of obtained MoS2/RGO nanohybrids is greatly affected by the conversion process of GO. In this work, we prepared the MoS2/GN hybrids by a facile hydrothermal method with directly introducing highly pure and electroconductive GNs. It is found that the highest reflection loss value of the sample-wax containing 40% MoS2/GN is −57.31 dB at a thickness of 2.58 mm, and the bandwidth of RL values less than −10 dB can reach up to 12.28 GHz (from 5.72 to 18 GHz) when an appropriate absorber thickness between 1.5 and 4 mm is chosen. The excellent MA performances emanate from effective conjugation of MoS2 with GN (Mo–C bond between the interfaces), which provides the dielectric loss caused by multi-relaxation, conductance, and polarization. Taking into account the facile synthesis route and their excellent MA performance, the MoS2/GNs hybrid nanosheets and those composite materials with similar isomorphic hetero-structures are very promising for a wide range of MA applications.Two-dimensional (2D) MoS2/graphene nanosheet (MoS2/GN) hybrids have been demonstrated to be promising microwave absorption (MA) materials due to their unique chemical and physical properties as well as rich impedance matching. 相似文献
3.
Ni–Fe–P nanoparticles/graphene nanosheet (Ni–Fe–P/GNs) composites were successfully synthesized by a simple one-step hydrothermal method. Specifically, Ni2+ and Fe2+ were reduced by using milder sodium hypophosphite as a reducing agent in aqueous solution. SEM and TEM images show that a large number of Ni–Fe–P nanoscale microspheres are uniformly deposited on graphene nanosheets (GNs). At the thickness of 3.9 mm, the minimum reflection loss (RL) of Ni–Fe–P/GNs reaches −50.5 dB at 5.3 GHz. In addition, Ni–Fe–P/GNs exhibit a maximum absorption bandwidth of 5.0 GHz (13.0–18.0 GHz) at the thickness of 1.6 mm. The significant electromagnetic absorption characteristics of the Ni–Fe–P/GN composites can be attributed to the addition of magnetic particles to tune the dielectric properties of graphene to achieve good impedance matching. Therefore, Ni–Fe–P/GN is expected to be an attractive candidate for an electromagnetic wave absorber.Ni–Fe–P nanoparticle/graphene nanosheet composites synthesized by a one-step hydrothermal method have excellent performance in the field of electromagnetic wave absorption, with a minimum reflection loss of −50.5 dB and a maximum effective absorption bandwidth of 5 GHz. 相似文献
4.
Yuanliang Zhou Javid Muhammad Xuefeng Zhang Dongxing Wang Yuping Duan Xinglong Dong Zhidong Zhang 《RSC advances》2018,8(12):6397
The synthesis of nanometer materials with unique structures and compositions has proven successful towards the attenuation of electromagnetic (EM) waves. However, it is still a challenge to form special nanostructures by integrating magnetic/dielectric loss materials into one particle due to the difficulties in coupling the heterogeneous components. Herein, we present the synthesis of novel nanocapsules (NCs) with Co–TiC twin cores encapsulated inside graphitic shells using an arc-discharge plasma method. The thickness of the graphitic shell could be controlled by quantitatively tuning the carbon source concentration. The optimal reflection loss (RL) values of the prepared NCs was −66.59 dB at 8.76 GHz with a low thickness of 2.56 mm. The bandwidth of RL ≤ −10 dB was up to 14.4 GHz, which almost covered the entire frequency band, namely, the S to Ku band (3.6 GHz to 18 GHz). This superior EM wave absorption was ascribed to the specific double-core shell nanostructures and effective impedance matching between the magnetic loss and dielectric loss originating from the combination of the magnetic Co and dielectric TiC/C.Fabrication of Co–TiC@C nanocapsules via an arc discharge plasma method. Its optimum EM wave absorption was −66.59 dB at 8.76 GHz. 相似文献
5.
In order to realize the characteristics of new types of wave-absorbing materials, such as strong absorption, broad bandwidth, low weight and small thickness, a hollow-structured flower-like Fe3O4@MoS2 composite was successfully prepared by simple solvothermal and hydrothermal methods in this paper. The structural properties were characterized by X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Besides, the microwave properties and magnetic properties were measured using a vector network analyzer and via a hysteresis loop. SEM and TEM images revealed that MoS2 nanosheets grew on the surface of hollow nanospheres. The results showed that the composite exhibited excellent absorbing property. When the molar ratio of Fe3O4 and MoS2 was 1 : 18, the minimum reflection loss value reached −49.6 dB at 13.2 GHz with a thickness of 2.0 mm and the effective absorption bandwidth was 4.24 GHz (11.68–15.92 GHz). Meanwhile, the effective absorption in the entire X-band (8–12 GHz) and part of the C-band (4–8 GHz) and Ku-band (12–18 GHz) could be achieved by designing the sample thickness. In addition, the hollow structure effectively reduced the density of the material, which was in line with the current development trend of absorption materials. It could be predicted that the hollow core–shell structure composite has a potential application prospect in the field of microwave absorption.A hollow-structured flower-like Fe3O4@MoS2 composite was synthesized. The minimum reflection loss value reached −49.6 dB at 13.2 GHz with a thickness of 2.0 mm and the effective absorbing bandwidth was 4.24 GHz (11.68–15.92 GHz). 相似文献
6.
In this work, NiFe2O4 nanoparticles were successfully supported on cotton-based carbon fibers through a flexible two-step approach consisting of calcination of cotton in a N2 atmosphere and subsequent hydrothermal reaction. The incorporation of the NiFe2O4 nanoparticles into cotton-based carbon fibers resulted in better impedance matching, leading to better microwave absorption performance than cotton-based carbon fibers and NiFe2O4 nanoparticles. For NiFe2O4/carbon fibers, reflection loss (RL) values less than −10 dB were obtained in the frequency range of 11.5–18 GHz with 2.4 mm thickness, which covered the entire Ku-band (from 12 to 18 GHz). Meanwhile, when the matching thickness was 3.2 mm, the RL values less than −10 dB were in the range of 8.0–12.7 GHz, which covered the entire X-band (from 8 to 12 GHz). This excellent and interesting microwave absorption performance can satisfy multiple applications. Owing to the characteristics of a cost-effective synthetic route, low density and excellent microwave absorption, the NiFe2O4/carbon fibers have a promising future in X-band and Ku-band absorption.NiFe2O4 nanoparticles supported on cotton-based carbon fibers exhibited excellent microwave absorption performance in the X-band and Ku-band. 相似文献
7.
The special hollow core–shell structure and excellent dielectric-magnetic loss synergy of composite materials are two crucial factors that have an important influence on the microwave absorption properties. In this study, hollow ZnFe2O4 nanospheres were successfully synthesized by a solvothermal precipitation method firstly; based on this, a C shell precursor phenolic resin was coated on the ZnFe2O4 hollow nanospheres'' surface by an in situ oxidative polymerization method, and then ZnFe2O4@C was obtained by high-temperature calcination. Samples were characterized by SEM, TEM, XRD, XPS, BET, VSM, VNA. The results show that the maximum reflection loss (RLmax) reaches −50.97 dB at 8.0 GHz, and the effective bandwidth (EAB) of hollow core–shell structure ZnFe2O4@C is 3.2 GHz (6.16–9.36 GHz) with a coating thickness of 3.5 mm. This work provides a useful method for the design of lightweight and high-efficiency microwave absorbers.The hollow core–shell structure ZnFe2O4@C in this work has excellent EM absorption performance. 相似文献
8.
One-dimensional K–MnO2 nanorods were prepared by a wet chemical process. Dopamine hydrochloride (PDA) layers with various thicknesses were coated and finally, the composites were filled in a poly(vinylidene fluoride) (PVDF) matrix using the hot-molding procedure. The complex permittivity and permeability of the K–MnO2@PDA/PVDF composites could be adjusted by reactant amount ratios and filler contents. The minimum reflection loss could reach −49.4 dB and an effective absorption bandwidth (<−10 dB) covering 11.12 GHz was achieved with 20% filler content when the reactant amount ratio between K–MnO2 and PDA was 4 : 0.375, which was derived from effective internal polarization processes. It is expected that these novel composites can be used as high-performance microwave absorbers.The microwave absorption properties of K–MnO2@PDA/PVDF composites are greatly enhanced due to appropriate reactant amount ratios and filler contents, which result in an effective internal polarization process. 相似文献
9.
The present study executed iron pentacarbonyl pyrolysis to synthesize one-dimensional structured carbonyl iron fibers (CIFs) via carrier gas induced flow. The obtained CIFs with a diameter of 100–300 nm and length–diameter ratio of more than 20, are actually composed of a large number of nanocrystalline aggregates. We investigated the dependence of the structure, morphology, and static magnetic and electromagnetic properties of the CIFs on the pyrolysis temperatures. CIFs synthesized at 300 °C (denoted as CIF-300) exhibited optimal microwave absorption properties dependent on the fiber structure and well-matched impedance. An optimal reflection loss of −58.1 dB was observed at 13.8 GHz with a matching thickness of 1.43 mm. Furthermore, CIF-300 presented a broad effective absorption bandwidth (RL ≤ −10 dB) of 5.66 GHz with a thickness of 1.44 mm, indicating that it could be applied in practical applications from 3.74 GHz to 18.0 GHz by tuning its thickness from 1.0 mm to 4.0 mm. This paper not only reveals that the CIFs synthesized at 300 °C have great potential application in microwave absorbing materials (MAMs) with thin thicknesses, wide absorption bandwidths, and strong absorption intensities, but also provides a simple approach to prepare metal fibers.Carbonyl iron fibers synthesized at 300 °C exhibit a minimum RL of −58.1 dB and an effective absorption bandwidth of 5.66 GHz. 相似文献
10.
CoNi microspheres with different diameters and heterogeneous Co/Ni nanocrystallines were synthesized via changing hydrothermal reaction parameters. The heterogeneous Co/Ni nanocrystallines comprised three kinds of particle morphologies, i.e., nanoflakes, nanospheres and needle-like nanowhiskers. The heterogeneous Co/Ni nanocrystalline sample coating (containing 60 wt% powder) exhibited a maximum reflection loss (RL) of −33 dB at 17.6 GHz and a bandwidth of less than −10 dB covering the 15.04–18.00 GHz range with a coating thickness of 1 mm. The CoNi microsphere sample with diameters in the range of 0.4–2.5 μm exhibited excellent microwave absorption abilities in the C-band (4–8 GHz) and X-band (8–11.5 GHz). However, the sample of chain-like assemblies from CoNi microspheres with a diameter above 2 μm presented poor microwave absorption in the 2–18 GHz range. In contrast, the excellent microwave absorption properties of the heterogeneous Co/Ni nanocrystalline sample in the Ku-band (12–18 GHz) could be attributed to the relatively high permeability (1.63–1.10) and optimal impedance matching between permittivity and permeability.CoNi microspheres with different diameters and heterogeneous Co/Ni nanocrystallines were synthesized via changing hydrothermal reaction parameters. 相似文献
11.
M. A. Almessiere Y. Slimani A. Demir Korkmaz A. Baykal H. Güngüne H. Szeri Sagar E. Shirsath S. Güner S. Akhtar A. Manikandan 《RSC advances》2019,9(53):30671
In the current study, Ni0.4Cu0.2Zn0.4LaxYxFe2−xO4 (x = 0.00 − 0.10) nanospinel ferrites (NSFs) were fabricated via an ultrasonic irradiation route. The creation of single phase of spinel nanoferrites (NSFs) was investigated by X-ray powder diffractometry (XRD) and selected area diffraction pattern (SAED). The cubic morphology of all samples was confirmed by scanning and transmission electron microscopies (SEM and TEM) respectively. The UV-Vis investigations provided the direct optical energy band gap values in a narrow photon energy interval of 1.87–1.92 eV. The 57Fe Mössbauer spectroscopy analysis explained that the hyperfine magnetic fields of Octahedral (Oh) and Tetrahedral (Td) sites decreased with substitution. The paramagnetic properties of NPs decrease with increase of content of doped ions. Investigations of magnetic properties reveal a superparamagnetic nature at 300 K and soft ferromagnetic trait at 10 K. The Ms (saturation magnetization) and Mr (remanence) decrease and the Hc (coercivity) increases slightly with La3+ and Y3+ substitution. The observed magnetic traits are deeply discussed in relation with the morphology, structure, magnetic moments and cation distributions. The microwave characterization of the prepared NSFs showed that, dissipation (i.e., absorption) of incoming microwave energy occurs at a single frequency, for each sample, lying between 7 and 10.5 GHz. The reflection losses (RL) at these frequencies range from −30 to −40 dB and the mechanism of which is explained in the framework of dipolar relaxation and spin rotation. The best microwave properties were obtained with a LaY concentration of x = 0.08 having an RL of −40 dB @ 10.5 GHz and an absorption bandwidth of 8.4 GHz @ −10 dB. With these high values of RL and absorbing bandwidth, LaY doped NiCuZn NSF products would be promising candidates for radar absorbing materials in the X-band.The best microwave properties for the NSFs were obtained with an LaY concentration of x = 0.08, RL of −40 dB @ 10.5 GHz and absorption bandwidth of 8.4 GHz @ −10 dB. The NSF products show promise as radar absorbing materials in the X-band. 相似文献
12.
Xiaoyan Han Ran Li Shengqiang Qiu Xiaofang Zhang Qing Zhang Yingkui Yang 《RSC advances》2019,9(11):5942
SnO2/graphene nanocomposite was successfully synthesized by a facile sonochemical method from SnCl2 and graphene oxide (GO) precursors. In the sonochemical process, the Sn2+ is firstly dispersed homogeneously on the GO surface, then in situ oxidized to SnO2 nanoparticles on both sides of the graphene nanosheets (RGO) obtained by the reduction of GO under continuous ultrasonication. Graphene not only provides a mechanical support to alleviate the volume changes of the SnO2 anode and prevent nanoparticle agglomeration, but also serves as a conductive network to facilitate charge transfer and Li+ diffusion. When used as a lithium ion battery (LIB) anode, the SnO2/graphene nanocomposite exhibits significantly improved specific capacity (1610 mA h g−1 at 100 mA g−1), good cycling stability (retaining 87% after 100 cycles), and competitive rate performance (273 mA h g−1 at 500 mA g−1) compared to those of bare SnO2. This sonochemical method can be also applied to the synthesis of other metal-oxide/graphene composites and this work provides a large-scale preparation route for the practical application of SnO2 in lithium ion batteries.SnO2/graphene nanocomposite was successfully synthesized by a facile sonochemical method from SnCl2 and graphene oxide (GO) precursors. 相似文献
13.
Lin Guo Sheng-Shuai Gao Qing-Da An Zuo-Yi Xiao Shang-Ru Zhai Dong-Jiang Yang Li Cui 《RSC advances》2019,9(2):766
Dopamine-derived cavities/Fe3O4 nanoparticles-encapsulated carbonaceous composites with self-generating three-dimensional (3D) network structure were successfully fabricated by a facile synthetic method, in which sodium alginate provided carbon matrix pores and excellent microwave absorption performance was established. The hollow cavities derived from the core–shell-like CaCO3@polydopamine were creatively introduced into the 3D absorber to significantly improve the absorption performance. The sample calcined at 700 °C exhibited the most outstanding microwave absorption performance, with minimal reflection loss up to −50.80 dB at 17.52 GHz with a rare thickness of only 1.5 mm when filler loading was 35% in paraffin matrix. The effective absorption bandwidth of reflection loss < −10 dB reached 3.52 GHz from 14.48 GHz to 18 GHz, corresponding to the same thickness of 1.5 mm. In contrast, the sample without hollow dopamine-derived cavities showed poor performance due to poor impedance matching, and this highlights the role of hollow cavities brought into the 3D structure, which led to a difference in interfacial polarization, multiple reflections and scattering. The novel dopamine-derived cavities/Fe3O4 nanoparticles-encapsulated carbonaceous composites with 3D network structure can be regarded as a promising candidate for application as a microwave absorber with strong absorption.Hollow dopamine-derived cavities/Fe3O4 nanoparticles-encapsulated carbonaceous composites with self-generating 3D network structure were fabricated for potential application as excellent microwave absorbers. 相似文献
14.
High performance methane gas sensors have become more and more essential in different fields such as coal mining, kitchens and industrial production, which necessitates the design and synthesis of highly sensitive materials. Herein, mesoporous SnO2 hollow spheres with high surface area (>90 m2 g−1) are prepared by a progressive inward crystallization routine, showing a high response of 1.31 to 250 ppm CH4 at a working temperature of 400 °C. Furthermore, loading noble metal Pd onto the surface of SnO2 hollow spheres by an adsorption–calcination process improves the response to 4.88 (250 ppm CH4) at the optimal dosage of 1 wt% Pd. Meanwhile, the working temperature decreases to 300 °C, showing the prominent spillover effect of catalytic Pd and PdO–SnO2 heterostructure sensitization as evidenced by the binding energy shift in the X-ray photoelectron spectroscopy (XPS) analysis. The response/recovery time is as short as 3/7 s and the sensitivity is stable for a test period as long as 15 weeks. All these performances show the promise of the highly porous Pd-loaded SnO2 hollow spheres for high performance methane sensors.This work reports a simple, rapid, effective and reliable CH4 sensor based on Pd-loaded SnO2 hollow spheres with high surface area and porosity, which is of great importance to gas sensing performance. 相似文献
15.
Yuanxin Wan Tianyi Wang Hongyan Lu Xiaoqian Xu Chen Zuo Yong Wang Chao Teng 《RSC advances》2018,8(21):11744
Tin dioxide (SnO2) is a promising anode material for lithium-ion batteries owing to its large theoretical capacity (1494 mA h g−1). However, its practical application is hindered by these problems: the low conductivity, which restricts rate performance of the electrode, and the drastic volume change (400%). In this study, we designed a novel polyacrylamide/SnO2 nanocrystals/graphene gel (PAAm@SnO2NC@GG) structure, in which SnO2 nanocrystals anchored in three-dimensional graphene gel network and the polyacrylamide layers could effectively prevent the agglomeration of SnO2 nanocrystals, presenting excellent cyclability and rate performance. A capacity retention of over 90% after 300 cycles of 376 mA h g−1 was achieved at a current density of 5 A g−1. In addition, a stable capacity of about 989 mA h g−1 at lower current density of 0.2 A g−1 was achieved.Tin dioxide (SnO2) is a promising anode material for lithium-ion batteries owing to its large theoretical capacity (1494 mA h g−1). 相似文献
16.
Reduced graphene oxide (RGO) decorated with octahedral NiS2/NiS nanocrystals were fabricated via a facile synthetic strategy. By appropriate adjustment of the weight ratio of GO and NiS2/NiS nanocrystals, RGO–NiS2/NiS nanocomposites with an excellent microwave absorption performance were achieved. As expected, RGO–NiS2/NiS nanocomposites in a polyvinylidene fluoride (PVDF) matrix with different mass fractions (5, 10, 15, 20 wt%) possess effective absorption in the high frequency range with a thin thickness (1.5 mm) compared with those of octahedral NiS2/NiS nanocrystals. It was revealed that RGO–NiS2/NiS nanocomposites with a GO : NiS2/NiS weight ratio of 1 : 4 exhibited the most prominent microwave absorption property. The optimal effective frequency bandwidth of this sample covers 4.32 GHz at a thin coating layer of 1.5 mm (15 wt%). The corresponding reflection loss value can reach −32.2 dB at 14.32 GHz. Moreover, the fundamental attenuation mechanisms are also discussed in detail.Reduced graphene oxide (RGO) decorated with octahedral NiS2/NiS nanocrystals were fabricated and they possessed an excellent microwave absorption performance in the high frequency range. 相似文献
17.
Here, nickel–cobalt sulphide particles embedded in graphene layers (porous Ni–Co–S@G), were successfully prepared by one-step annealing of metallocene/metal–organic framework (MOF) hybrids involving simultaneous carbonization and sulfidation. Benefiting from the porous structure, highly conductive graphene layers and large loading of super-capacitive Ni–Co–S, the obtained Ni–Co–S@G composites exhibited excellent electrochemical performance with a specific capacitance of 1463 F g−1 at a current density of 1 A g−1. A flexible solid-state asymmetric supercapacitor (ASC), assembled with Ni–Co–S@G and active carbon, demonstrated a high energy density of 51.0 W h kg−1 at a power density of 650.3 W kg−1. It is noteworthy that the ASC offered robust flexibility and excellent performance that was maintained when the devices were bent at various angles. The results indicate that the as-prepared materials could potentially be applied in high-performance electrochemical capacitors.Ni–Co–S@graphene composites, derived from a metallocene/MOF precursor, presents high energy density and excellent cycling stability. 相似文献
18.
Porous Fe3O4@C core/shell nanorods decorated with reduced graphene oxide (RGO) were fabricated through a facile one-pot method. The microwave absorption properties of the samples can be adjusted by the weight ratio of RGO. The addition of RGO not only effectively reduces the agglomeration of Fe3O4@C, but also has a great effect on impedance matching and dielectric loss, resulting in enhanced microwave absorption abilities. The thickness corresponding to optimum reflection loss (RL) decreases as the weight ratio of RGO increases. For the Fe3O4@C/RGO composite, a maximum RL value of −48.6 dB can be obtained at 13.9 GHz with a thickness of 3.0 mm, and the absorption bandwidth with RL below −10 dB is 7.1 GHz from 10.9 GHz to 18 GHz. These results demonstrate a facile method to prepare a highly efficient microwave absorption material with special microstructure.Porous Fe3O4@C core/shell nanorods decorated with reduced graphene oxide were synthesized by a facile one-pot method, and exhibit high microwave absorption performance: maximum reflection loss reaches −48.6 dB. 相似文献
19.
Activated carbon@Fe3O4 composites with good electromagnetic wave absorption performances in the low frequency range were synthesized via the hydrothermal method. The crystal structure, microstructure, magnetization properties, frequency-dependent electromagnetic properties and microwave absorption properties of the as-prepared composites were characterized via XRD, VSM, SEM, TEM and VNA, respectively. The results indicated that the electromagnetic wave absorption performance of the composites can be adjusted through the addition of activated carbon. A suitable loading content of Fe3O4 NPs on activated carbon can also enhance the microwave absorption performance of the composites. The synergy of dielectric and magnetic loss is the main electromagnetic wave absorption mechanism, and the maximum RL of −10.08 dB at 1.75 GHz with a −5 dB bandwidth over the frequency range of 1.55 GHz (1.07–2.62 GHz) is obtained when the percentage of Fe3O4 NPs and the thickness of the composites are 74 wt% and 5 mm, respectively. Hence, the composite reported in this study can be used as a promising microwave absorbing material in the low frequency range of 0.5–3 GHz.Activated carbon@Fe3O4 composites with good electromagnetic wave absorbing performances in the low frequency range were synthesized via a hydrothermal method. 相似文献
20.
To obtain a low-density material that is capable of absorbing electromagnetic waves over a wide bandwidth, an activated carbon fiber/Fe3O4 composite material (ACF/Fe3O4) was prepared using an in situ reduction method. Scanning electron microscopy images show that Fe3O4 nanoparticles, approximately 10–40 nm in size, were spread uniformly over the surface of the ACF. The resulting composite exhibited superparamagnetic behavior at room temperature. The ability of the ACF and ACF/Fe3O4 composite to absorb electromagnetic waves over a frequency range of 8.2–18 GHz was measured using the arch method. The results showed that the maximum reflectivity of an ACF felt was −12.9 dB at 18 GHz, and the effective microwave-absorbing bandwidth (R < −10 dB) was 1.9 GHz (16.10–18 GHz). The absorption performance of the ACF was greatly enhanced by being loaded with Fe3O4 nanoparticles; the maximum reflectivity of the 2 mm layer of the ACF/Fe3O4 composite was −30.07 dB at 16.45 GHz, and the effective bandwidth (R < −10 dB) increased to 8.62 GHz (9.38–18 GHz). Coating with nano-Fe3O4 magnetic particles can effectively improve the absorption of electromagnetic waves by the ACF, and this technique therefore has great potential for application to the field of electromagnetic shielding.To obtain a low-density material that is capable of absorbing electromagnetic waves over a wide bandwidth, an activated carbon fiber/Fe3O4 composite material (ACF/Fe3O4) was prepared using an in situ reduction method. 相似文献