Wave Absorption Materials Research Articles

Heating induced self-assemble pomegranate-like Fe3C@Graphite magnetic microspheres on amorphous carbon for high-performance microwave absorption

Difficulty of multicomponent regulation and nanostructure design make it challenging to fabricate high-performance electromagnetic wave (EMW) absorption materials. Herein, pomegranate-like Fe3C@graphitic carbon embedded in amorphous carbon matrix (Fe3C@GC/AC) is successfully prepared through a viable heating induced self-assembly strategy. By adjusting carbonization temperature, controllable electromagnetic parameters and impedance matching characteristics of Fe3C@GC/AC nanocomposites could be acquired. Besides, dielectric loss and magnetic loss are offered by GC and Fe3C, while the amorphous carbon not only disperse Fe3C@GC nanoparticles well, but also strengthens interface polarization. The detailed analysis show that Fe3C@GC/AC nanocomposites exhibit excellent EMW absorption performance under the combined function of unique pomegranate-like nanostructure and various loss mechanisms of multi-components. Moreover, the strongest reflection loss value of optimal sample (RCF-700) is up to −96.3 dB (loss of EMW above 99.99999%) with a matching thickness of 2.08 mm, and the effective absorption bandwidth (EAB, RL < −10 dB) covers 6.38 GHz (11.62–18.0 GHz, covering Ku-band). In addition, the EAB can reach 14.08 GHz with the simulated thickness varies from 1.0 to 5.0 mm, covering 88% of the measured frequency range. The deep exploration of the bio-inspired structure of multi-component system provides a creative and effective way for high-performance EMW absorbers.

Flexible electromagnetic wave absorption material: Multiscale synergistic approach to achieve whole X-band absorption and thermal stealth property

Fabric-based electromagnetic wave (EMW) absorption materials are desirable owing to their inherent flexibility, cost-effectiveness, and easily conformable lightweight structures. However, the problems such as high density and susceptibility to abrasion limit their applications and service life. Herein, flexible fabric-based EMW absorption material (FEMWAM) were prepared by a multiscale synergistic approach. At the microscopic scale, CF@NiCo2O4@MnO2 absorbents with enhanced impedance matching and interfacial polarization are prepared by solvent method and hydrothermal process. The influence of heterostructure on the electromagnetic response is also examined. At the macroscopic scale, flexible FEMWAM are prepared by freeze-drying. The electromagnetic parameters of FEMWAM was effectively regulated by altering the amount of the CF@NiCo2O4@MnO2 absorbents, which achieve excellent EMW absorption performance and thermal insulation property while maintaining flexibility. The minimal reflection loss (RLmin) of −27.8 dB can be achieved at a thickness of 2.70 mm, and an EAB covering the complete X-band can be obtained when the thickness is in the range of 3.20–3.26 mm. The large thickness range provides convenience for the control of dimensional accuracy in actual production, so as to better adapt to practical applications. These findings provide effective guidance for the preparation of EMW absorption materials with excellent flexibility, thermal insulation properties and absorption performance.

Construction of hierarchical carbon fiber Aerogel@Hollow Co9S8 polyhedron for high-performance electromagnetic wave absorption at low-frequency

The development of low-frequency electromagnetic wave absorption materials faces considerable obstacles due to intense coupling of wave impedance and electromagnetic dissipation capacity. Herein, a novel hierarchical structure composed of 3D interconnected carbon fibers aerogel loaded with hollow cobalt (Co)-sulfide polyhedrons (CFA@HCS) is designed. Typical 3D interconnected carbon fibers derived from bamboo cellulose fiber aerogel serve as a skeleton to support the Co9S8 with a hollow structure. The electromagnetic parameters of the composite are effectively modified by combining the carbon-based skeleton with the hollow Co9S8. The coupling interaction of the electromagnetic characteristics at low frequency can be significantly improved. Accordingly, the minimum reflection loss (RLmin) of CFA@HCS with 15 wt% filler loading reaches −53.6 dB at 3.36 GHz and its effective absorption bandwidth can cover almost all the S and C bands (3.04–8 GHz). In addition, the minimum reduction of the radar cross section (RCS) reaches –22.6 dB m2 when the incidence theta is −60°. This work demonstrates that low-frequency EMW absorption could be improved by constructing hierarchical composites of carbon fiber/transition metal sulfide.

Variable-Temperature Regulation of NiCo2S4/Mn3O4 Nanostructured Composites for High-Performance Microwave Absorption

Currently, transition-metal oxides and sulfides remain widely used in the research on electromagnetic-wave-absorbing materials. In the present work, NiCo2S4/Mn3O4 nanostructured composites were prepared by a series of hydrothermal and annealing processes and a strategy for the preparation of morphologically controllable absorbers was developed. The results show that the nanostructure design of Mn3O4 was achieved by the variable-temperature strategy, and the Mn3O4 shell was about 500 nm when the temperature reached 160 °C, and the composite had a uniform shell–core structure. In addition, the effects of microscopic morphology, lattice defects, and heterogeneous interfaces on electromagnetic parameters are investigated. In conclusion, the multiple loss mechanism and excellent impedance matching ability synergistically enable the NiCo2S4/Mn3O4 nanostructured composite to achieve excellent microwave absorption characteristics, with a minimum reflection loss of −54.4 dB and a maximum effective absorption bandwidth of 5.36 GHz. This work provides a new perspective on the design of wave-absorbing materials for shell–core structures.

Study on electromagnetic wave absorbing properties of nanocrystalline Fe81.5Si3B9P3C1Cu1Ti1.5/Graphene oxide composite

To prevent and control electromagnetic pollution problems, there is an urgent need to develop better wave-absorbing materials. In this study, nanocrystalline alloy/graphene oxide(GO) composite modified powder was obtained on the basis of Fe81.5Si3B9P3C1Cu1Ti1.5 nanocrystalline alloy powder with different weight percentages of GO, which was mechanically mixed by high-energy ball milling treatment, and the microstructure and morphology of the materials and the electromagnetic wave absorption properties were characterized. The results show that the Fe81.5Si3B9P3C1Cu1Ti1.5/GO composite powder has excellent wave absorption performance, and the loss mechanism is magnetic loss including eddy current loss and natural resonance. Defects and groups in GO not only improve the impedance matching characteristics, but also introduce defect polarization relaxation and electron dipole polarization relaxation of the groups, which are beneficial to the penetration and absorption of electromagnetic waves. The minimum reflection loss (RLmin) of the nanocrystalline alloy powder can reach −37.55 dB and the maximum effective absorption bandwidth (ΔfRL<-10dB) can reach 5.95 GHz; the RLmin of the composite powder is as high as −52.55 dB when the GO content is 1.5 wt%, and the widest bandwidth can reach 6.12 GHz at 2.00 mm when the GO content is 0.5 wt%. With the addition of GO, its RLmin increased by 40%. This indicates that the composite material have superior absorption performance compared to a single absorber.

Recent advances of carbon-based electromagnetic wave absorption materials facing the actual situations

In order to protect human safety, ensure the normal operation of precision instruments and improve national defense capabilities, it is necessary to develop electromagnetic waves absorbing materials to solve the issue of electromagnetic pollution. Carbon materials offer the characteristics of abundant species, low density, tunable conductivity, and outstanding mechanical property, enabling them to be used in a wide range of applications, and are of particular interest in the electromagnetic protection technology. In recent years, a large number of carbon-based absorbers have been synthesized and investigated in pursuit of the ideal goal with “thin thickness, light density, wide effective bandwidth and strong absorption” characteristics. In this review, it begins with a detailed description of the electromagnetic waves attenuation mechanisms. Next, a systematic summary of strategies to optimize the electromagnetic protection effect of carbon-based absorbers is provided. Thirdly, the multifunctional requirements of absorbing materials are discussed in depth when faced with practical application situations. Finally, we put forward the challenges and prospects of carbon-based protection materials, which can serve as a reference for the development of high-performance absorbers.

Multiscale structure and interface engineering of Fe/Fe3C in situ encapsulated in nitrogen-doped carbon for stable and efficient multi-band electromagnetic wave absorption

Most reported electromagnetic wave absorption (EWA) materials show significant effective absorption in a certain frequency range, but their performances deteriorate dramatically as the frequency changes. As the range of working frequencies for electronic devices is gradually widening, it is of great interest to explore frequency-insensitive EWA materials that can achieve efficient absorption in every waveband by simply changing the absorption thickness. To this end, a multi-scale absorber (Fe/Fe3C@NC) is rationally synthesized by chemical foaming and in-situ growth strategy. By controlling the growth of carbon nanotubes, the Fe/Fe3C@NC-2 exhibits a well-constructed 3D multi-scale architecture. Thanks to dipole polarization, interface polarization and magnetic-dielectric energy conversion, the Fe/Fe3C@NC-2 overcomes the frequency dispersion behavior and keeps a stable dielectric attenuation capability across the entire frequency range. Consequently, it delivers a superb full-band absorption of -50.1, -59.83, -55.87 and -51.91 dB in the S, C, X and Ku bands, respectively. The maximum radar cross-sectional reduction reaches 35.44 dB m−2 when the incident θ is 20°, testifying its impressive performance. Surprisingly, this EWA material also shows a remarkable resistance to oxidation and corrosion derived from the tightly coated carbon layers. This work provides new insight into the design of multi-band and stable EWA materials for practical application.

In situ modification of MXene nanosheets with polyaniline nanorods for lightweight and broadband electromagnetic wave absorption

MXene exhibits excellent electromagnetic (EM) wave attenuation ability, but its high dielectric constant is prone to impedance mismatch. Usually, the introduction of other components can adjust EM parameters and improve the impedance matching of MXene. In this paper, MXene/polyaniline (PANI) composites with lots of heterogeneous interfaces were designed and prepared by electrostatic self-assembly process, and PANI was used as impedance matching modifier of MXene to adjust the impedance matching of the composites and achieve greater reflection loss. The effect of the content of PANI nanorods loaded on MXene nanosheets on the EM properties of the material was discussed in this work. The maximum reflection loss (RLmax) of −60.6 dB corresponds to an effective absorption bandwidth (EAB) of 6.0 GHz for the composite with only 10% PANI loading, while the EAB reaches 8.64 GHz when the sample thickness is 2.3 mm. Moreover, the introduction of PANI balances the impedance matching of MXene while bridging individual MXene nanosheets to form a three-dimensional structure that increases the EM wave propagation path. The rich loss mechanisms such as interfacial polarization and dipole polarization provide effective attenuation of EM waves. This work provides a simple way to develop lightweight and broadband EM wave absorption materials.

Outstanding electromagnetic wave absorption performance of polyacrylonitrile-based ultrahigh modulus carbon fibers decorated with CoZn-bimetallic ZIFs

PAN-based carbon fibers have been widely used in aerospace materials due to high specific strength, high specific modulus and many other outstanding features. As one kind of carbon-based electromagnetic wave (EMW) absorption material, carbon fibers are expected to absorb more EMW due to multiple polarization losses and large specific surface area in which EMW can be reflected many times. However, they also have certain disadvantages when used as EMW absorption material due to their high dielectric constant, low permeability and low reflection loss strength. Herein, a facile hydrothermal synthesis method was used to construct the three-dimensional (3D) bimetal-organic framework compound onto the surfaces of polyacrylonitrile(PAN)-based ultrahigh modulus carbon fibers (UHMCFs). Through the control of key parameters in the synthesis process, 3D bimetallic ZIF particles with different morphologies were assembled on the fiber surfaces, and a further high temperature heat treatment resulted in significantly improved EMW absorption properties. The results showed that three fibrous structures including rod-shaped, threadlike and flower-like morphologies had been formed with the introduction of CoZn-ZIFs. Among them, the uniform structure of rod-shaped sample could be preserved after carbonization and it also showed optimal EMW absorption performance, e.g. its minimum reflection loss (RLmin) and effective absorption bandwidth (EAB) values were − 67.67 dB (EMW loss above 99.9 %) and 4.28 GHz, respectively, with the thickness of 2.00 mm. In the final, the EMW absorption mechanism of CoZn-bimetallic ZIF decorated UHMCFs including interfacial loss, conductive loss, polarization loss, multiple scattering and excellent impedance matching was discussed in detail.

Hollow porous Ni@SiC nanospheres for enhancing electromagnetic wave absorption

Multi-component and a large number of non-homogeneous interface absorbers have been proven to be the preferred choice of electromagnetic wave (EMW) absorption materials. Herein, hollow porous Ni@SiC nanospheres (HPNS) were successfully constructed by combining a carbothermal reduction preparation strategy and subsequent electroless plating process. The heterogeneous dielectric/magnetic multi-component benefit to excellent EMW absorption properties through forming multiple polarizations, dielectric loss, and magnetic loss effects. Particularly, the HPNS at the optimal ratio with a low filler loading of 20 wt% exhibits the minimum reflection loss (RLmin) value of −62.39 dB at 13.28 GHz and the maximum effective absorption bandwidth (EABmax) is up to 5.36 GHz (12.64–18 GHz), and the corresponding thin matching thicknesses are 1.96 mm and 1.80 mm, respectively. Furthermore, the maximum radar cross section (RCS) reduction of HPNS over PEC reaches 26.02 dB m2 (1.96 mm) under far-field conditions, which means that the prepared HPNS is extraordinarily promising for practical applications. This work guides the preparation of high-performance EMW absorbers as well as radar stealth materials.

Controllable Architecture of ZnO/FeNi Composites Derived from Trimetallic ZnFeNi Layered Double Hydroxides for High-Performance Electromagnetic Wave Absorbers.

The optimization design of micro-structure and composition is an important strategy to obtain high-performance metal-based electromagnetic (EM) wave absorption materials. In this work, ZnO/FeNi composites derived from ZnFeNi layered double hydroxides are prepared by a one-step hydrothermal method and subsequent pyrolysis process, and can be employed as an effective alternative for high-performance EM wave absorber. A series of ZnO/FeNi composites with different structures are obtained by varying the molar ratios of Zn2+ /Fe3+ /Ni2+ , and the ZnO/FeNi composites with a Zn2+ /Fe3+ /Ni2+ molar ratio of 6:1:3 show a hierarchical flower-like structure. Owing to the strong synergistic loss mechanism of dielectric-magnetic components and favorable structural features, this hierarchical flower-like ZnO/FeNi sample supplies the optimal EM wave absorption performance with the highest reflection loss of -52.08dB and the widest effective absorption bandwidth of 6.56GHz. The EM simulation further demonstrates that impedance matching plays a determining role in EM wave absorption performance. This work provides a new way for the fabrication of a high-performance metal-based EM wave absorber.

Preparation of magnetic three-dimensional porous Co-rGO aerogel for enhanced microwave absorption

A good electromagnetic wave (EMW) absorption material should possess both favorable impedance matching and superb EMW absorption performances. Apart from this, the characteristics of lightweight, thin matching thickness, strong absorption and broad bandwidth are required. To achieve this, ultralight Co-rGO aerogel materials were prepared through a series of treatments of hydrothermal, freeze-drying and annealing. Through the addition of pvp and under different annealing temperatures, we investigated the effect of pore structure, pore size and magnetism on the absorbing properties of the materials. The magnetic and porous properties are demonstrated by the Vibrating Sample Magnetometer (VSM) and Brunauer Emmett Teller (BET) N2 adsorption-desorption isotherms, respectively. According to the SEM and TEM images, it can be seen that the Co-MOF microspheres growing onto the reduced graphene oxide (rGO) nanosheets. It is worth noting that the 800Co-rGO-pvp composite shows excellent EMW absorption performances with a low filling content of 4 wt%, which achieves strong absorption of −40.57 dB at a thickness of 2.0 mm and broad effective absorption bandwidth (EAB) of 7.12 GHz at a thickness of 2.5 mm, covering the whole Ku band and a quarter of X band. Moreover, a series of absorption mechanisms are elaborated, such as interfacial polarization, dipolar polarization, conduction loss, magnetic resonance and eddy current loss. All in all, the outstanding EMW absorption performances are attributed to the magnetic three-dimensional porous structure of Co-rGO aerogel.

Flexible and Ultrathin Graphene/Aramid Nanofiber Carbonizing Films with Nacre-like Structures for Heat-Conducting Electromagnetic Wave Shielding/Absorption

Electromagnetic interference (EMI) shielding and electromagnetic wave absorption (EWA) materials with good thermal management and flexibility properties are urgently needed to meet the more complex modern service environment, especially in the field of smart wearable electronics. How to balance the relation of electromagnetic performance, thermal management, flexibility, and thickness in material design is a crucial challenge. Herein, graphene nanosheets/aramid nanofiber (C-GNS/ANF) carbonizing films with nacre-like structures were fabricated via the blade-coating/carbonization procedure. The ingenious configuration from highly ordered alignment GNS interactively connected by a carbonized ANF network can effectively improve the thermal/electrical conductivity of a C-GNS/ANF film. Specifically, the ultrathin C-GNS/ANF film with a thickness of 17 μm shows excellent in-plane thermal conductivity (TC) of 79.26 W m-1 K-1 and superior EMI shielding up to 56.30 dB. Moreover, the obtained C-GNS/ANF film can be used as a lightweight microwave absorber, achieving excellent microwave absorption performance with a minimum reflection loss of -56.07 dB at a thickness of 1.5 mm and a maximum effective absorption bandwidth of 5.28 GHz at an addition of only 5 wt %. Furthermore, the C-GNS/ANF films demonstrate good flexibility, outstanding thermal stability, and flame retardant properties. Overall, this work indicates a prospective direction for the development of the next generation of electromagnetic wave absorption/shielding materials with high-performance heat conduction.

CrN attached multi-component carbon nanotube composites with superior electromagnetic wave absorption performance

Compared with the other absorption materials, multicomponent of CNTs composite materials have become increasingly significant in the preparation of high-performance electromagnetic wave absorption materials due to their unique dielectric-magnetic advantages. In this paper, we use the heating and disintegration of organic amine salt to achieve the restoration of oxides while derivating carbon nanotubes, preparing an excellent performance of Co/Cu/CrN/CNTs composite materials. Due to annealing, slim -shaped CrN evenly attached to the surface of carbon nanotubes. The material forms a rich interface and good impedance matching characteristics, thereby realizing the excellent electromagnetic wave absorption performance of the material. The maximum bandwidth of 7.2 GHz was obtained at 2.62 mm and the minimum reflection loss was – 53.58 dB. The composite material design provides a new way for the development of high-performance electromagnetic wave absorption materials.

Bimetallic MOF-derived composites with broad electromagnetic wave absorption and strong corrosion resistance

With widespread requirements of electromagnetic wave absorption in 5G era, the advanced wave-absorbing materials with corrosion resistance are urgently required. Herein we have synthesized a bimetallic NiZn-MOF-derived composite with broad electromagnetic wave absorption and strong excellent corrosion resistance using a facile hydrothermal method. Based on the composition modulation of the produced Ni/Ni3ZnC0.7 particles, dense and continuous carbon shell can be formed and eventually encapsulate the particles. The resulting composite has an optimum reflection loss of −56.8 dB at 2.40 mm and an effective absorption bandwidth of 5.9 GHz at 2.34 mm. Besides, it remains stable after 6-month immersion in the corrosive mediums, suggesting its long-term corrosion resistance. This work provides a way to prepare MOF-derived wave absorbing materials with anti-corrosion function.

In situ construction of complex spinel ferrimagnet in multi-elemental alloy for modulating natural resonance and highly efficient electromagnetic absorption

The contradiction between the demand for highly efficient low-frequency electromagnetic wave (EMW) absorption materials and the relatively poor permeability of existing absorbers has become increasingly prominent. However, the intrinsic natural resonance in magnetic material hinders the modulation and enhancement of permeability. Herein, (FeCoNiCu)xCr3−xO4 complex spinel ferrimagnets (CSFMs) are constructed in situ in multi-elemental alloy powders (MEAs) for the first time, via annealing treatment. The microstructure and composition of the CSFMs are regulated by adjusting the annealing temperature, aiming to modulate the natural resonance frequency and achieve highly efficient megahertz (MHz) electromagnetic absorption. Simultaneously, annealing treatment improves the crystal integrity, which is conducive to enhancing intergranular magnetic coupling to elevate permeability temperature stability and the Curie temperature. The minimum reflection loss value of the MEAs/CSFMs composites is less than −7 dB at 3 mm and the effective EMW absorption bandwidth maintains between 425 and 470 MHz at 5 mm from −50 to 150 °C. In addition, the MEAs/CSFMs composites also exhibit excellent oxidation resistance and corrosion resistance due to the oxide layer on the surface. This work offers a new and tunable strategy toward modulating the natural resonance frequency for efficient temperature-stable broadband EMW absorption at specific frequency bands.

In situ construction of ZIF-67 derived Mo2C@cobalt/carbon composites toward excellent electromagnetic wave absorption properties

Electromagnetic wave (EM) absorption materials with multi-loss mechanisms and optimized impedance matching have attracted considerable attention as a means to combat the ever-increasing electromagnetic pollution. Molybdenum carbide (Mo2C) with outstanding environmental stability and high conductivity is becoming popular as EM absorption materials. Herein, the CoMoO4@ZIF-67 precursor was synthesized by an in situ sacrificial template method, followed by calcining to synthesize porous Mo2C@cobalt/carbon (Mo2C@Co/C) composites. The homogeneously dispersed Mo2C and Co nanoparticles as well as the porous structures resulted from the novel in situ fabrication strategy could generate abundant interfaces and induce effective multi-loss mechanisms including polarization loss, conductivity loss, magnetic loss, and so on. The as-prepared optimal composite (Mo2C@Co/C-10) demonstrates superior electromagnetic (EM) wave absorption performance with a maximum reflection loss value of −37.9 dB at the matching thickness of 2.3 mm, and the effective absorption bandwidth (EAB) of 5.52 GHz was realized at 1.9 mm. The excellent EM wave absorption properties can be attributed to the good impedance matching, synergistic effects among different loss mechanisms, multiple reflection and scattering. This work not only developed an effective ternary EM absorption materials of Mo2C@Co/C, but also propose a facile in situ strategy to fabricate more highly- dispersed mecarbide-basedased materials.

Synergistically enhanced flexibility, mechanical strength and microwave absorption performances of TPE-based hybrid films via thermally assisted homogeneous separation technology

With the ever-growing electromagnetic (EM) wave pollution and the rising demand of flexible absorbing materials pasted onto the surfaces of different geometric surfaces, it is urgent to develop high-efficiency EM wave absorption films with good flexibility and mechanical strength. Traditional processing methods endow the film superior features that can be adapted to targeted geometric surfaces and complex conditions, however, the durability is not satisfactory. Confronted with the tough problem, in this work, optimized thermally assisted homogeneous separation technology was proposed to fabricate the thermoplastic elastomer-based magnetic/dielectric two-phase mixed EM wave absorption films, which can achieve good flexibility, machinability, mechanical strength, as well as excellent EM wave absorption performances due to the uniform filling of elastoplastic skeletons and chain-bridge effect between chains and particles. Benefitting from these merits, the as-prepared films exhibit good flexibility and fine mechanical properties, like good deformability (300% of the deformation compared to its original length) and low elastic coefficient (323.8 Pa). Moreover, good EM wave absorption performances can also be balanced, for example, broad effective bandwidth (>14 GHz) and tunable frequency response from high frequency to low frequency. In all, this work opens up a new pathway to realize the integration of strong EM response, good flexibility, and fine mechanical properties, and the obtained films exhibit great potentials as flexible EM wave absorption materials that can be pasted on or peeled off the targeted surfaces at any time.

3D integrated hollow lightweight E-glass fiber reinforced epoxy composites with excellent electromagnetic wave absorption and thermal insulation

Electromagnetic parameters regulation is still a formidable task in developing lightweight, wide bandwidth, and high-efficiency electromagnetic wave (EMW) absorption materials. Here, a facile technique has been proposed by taking full advantage of 3D integrated hollow E-glass fabric, which is characterized by the typical spatial characteristic forms (U-shaped hollow structures at the level of the centimeter) to regulate EM parameters, optimizes impedance matching and enhances the absorption ability of graphene nanosheets (GNs). The minimum reflection loss (RL) of the 3D integrated hollow GN/resin composites reached −49.3 dB with an effective absorption bandwidth (RL < −10 dB) of 12.4 GHz. Comparing the density of the novel composites to that of conventional EMW absorption materials, it is lowered by an order of magnitude (0.31 g cm−3). Moreover, a good temperature drop of 100 °C was observed under an infrared thermal imager. The results indicate that the composites not only effectively alter the propagation path of EMW, increase the EM energy losses in the transmission process, but also block thermal convection and show excellent thermal insulation properties. This study provides an aggressive strategy and effective method for the development of lightweight ultra-broadband absorbing and excellent thermal insulation composites.

Morphology modulated defects engineering from MnO2 supported on carbon foam toward excellent electromagnetic wave absorption

Defect engineering exerts a crucial impact on polarization loss and thereby enhances electromagnetic (EM) wave absorption ability. The EM loss mechanism beneath of morphology conversion is usually vaguely considered as the synergism of multiple mechanisms. Morphology induced defects and its dominated polarization loss mechanisms are little focus on. In this work, MnO2/Carbon foam (MCF) composites with tunable morphology were prepared via facile hydrothermal and annealing process. Morphological conversion of MnO2 and its induced defects were achieved by KMnO4 concentration, which contributes to the reduction of conductive loss, optimization of impedance matching, increase of polarization loss and multiple scattering. Therefore, the minimum reflection loss of MCF composite harvests −65.18 dB at 3.19 mm and the broad effective absorption bandwidth covers the entire X band. Despite multiple dissipation mechanisms, the excellent performance is dominated by morphology modulated defects in MCF composites. Besides, the optimal MCF composite displays a high compressive strength of 14.647 MPa. According to the results of computer simulation technology, the MCF composite can attenuate EM energy in the actual condition. This work is expected to offer an inspired understanding of morphology modulated defects toward high-performance of EM wave absorption materials.