Hollow Engineering of Core-Shell Fe3O4@MoS2 Microspheres with Controllable Interior toward Optimized Electromagnetic Attenuation

Hollow Engineering of Core-Shell Fe3O4@MoS2 Microspheres with Controllable Interior toward Optimized Electromagnetic Attenuation | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Hollow Engineering of Core-Shell Fe 3 O 4 @MoS 2 Microspheres with Controllable Interior toward Optimized Electromagnetic Attenuation Na Chen, Ru-Yu Wang, Xue-Feng Pan, Bing-Bing Han, Jia-Xin Li, and 5 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-6546742/v1 This work is licensed under a CC BY 4.0 License Status: Published Journal Publication published 11 Jul, 2025 Read the published version in Advanced Composites and Hybrid Materials → Version 1 posted 10 You are reading this latest preprint version Abstract The development of electromagnetic wave absorbing materials with broadband absorption and thin thickness still confronts huge challenges in addressing the aggravating problem of electromagnetic pollution. Herein, hollow core-shell Fe3O4@MoS2 microspheres with controllable interior and tunable shell are constructed to precisely regulate the corresponding electromagnetic attenuation. The results demonstrate that hollow Fe3O4 microspheres exhibit strong absorption in C-X bands owing to their strong ferromagnetic resonance. Upon structural regulation, hollow core-shell Fe3O4@MoS2 microspheres not only ensure outstanding electromagnetic wave absorption intensity at thin thickness, but also endow broadband absorption characteristics. Benefiting from the cooperative merits of manipulated Fe3O4 interior and controllable MoS2 shells, the as-synthesized microspheres display obvious interface polarization, defect/dipole polarization and multiple scatterings, thereby resulting in improved impedance matching and attenuation capability. Especially for Fe3O4@MoS2-2, the strongest reflection loss is -69.01 dB at 2.66 mm and the effective absorption bandwidth reaches 8.40 GHz when the thickness is 3.0 mm. This study systematically investigates the balance relationship between core-shell structures and absorption attenuation, and simultaneously provides a referable strategy to regulate the electromagnetic wave absorption by structural optimization. Hollow engineering core-shell structure polarization resonance impedance matching electromagnetic wave absorption Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Introduction The flourish evolution of electronic technology is propelling the world into a smart era [1-3]. People enjoy the benefit of technological advancement, whereas the incidental electromagnetic pollution poses impacts on people’s health and military safety [4-6]. EMA materials, which have the ability to transform the electromagnetic energy into heat, play a crucial role in dealing with electromagnetic pollution and signal shielding [7-9]. In recent years, substantial studies have implemented structural and compositional engineering to improve the performance of EMA materials [10-12]. Among all the achievements, magnetic-dielectric heterostructure composite (e.g., FeNi 3 /C, Co 7 Fe 3 /SiO 2 , Fe 3 O 4 /C, and CoNi/TiO 2 ) makes tremendous progress in terms of bandwidth expansion and RL enhancement, enabling them highly sought in EMA field [13-19]. However, the challenges of broadband absorbing with thin thickness remain unsolved. The couplings of component/loss mechanism underlying the consumption of electromagnetic wave based on the magnetic-dielectric synergistic structure remain abstruse. Therefore, it still needs further study to construct magnetic-dielectric composites to achieve powerful EMA performances and understand the loss mechanisms. Fe 3 O 4 , as a typical ferrite, is widely applied in electromagnetic wave attenuation, electronic devices, magnetic fluid, energy storage, catalysis, and biomedicine due to its interesting magnetic properties and high chemical stability [20-23]. For electromagnetic wave absorbing purposes, the tunable morphology, suitable saturation magnetization and high permeability, are attractive features to effectively promote electromagnetic wave attenuation [24-26]. Numerous studies have been devoted to construct Fe 3 O 4 -based magnetic-dielectric composites to regulate electromagnetic properties and enhance impedance matching, thereby overcoming its limitations of narrow absorption bandwidth and inferior EMA in S–C bands. For example, He et al . reported a quantitative design approach to enhance the attenuation properties of Fe 3 O 4 @C@Co/N-doped C composite, which endow the composite with high magnetic loss, dielectric loss, and multi-reflections/scatterings, thus resulting in an EAB of 6.49 GHz and a RL of −66.39 dB [27]. Li et al . proposed a component regulation that sandwiching Fe 3 O 4 into rGO, which facilitates the interface polarization and modulates the complex permittivity, thus obtaining an EAB of 5.7 GHz and a RL of −49.9 dB [28]. Wang et al . exploited the multicomponent synergistic effect within magnetic Fe 3 O 4 , Ni–Co and dielectric MnO 2 , effectively boosting impedance matching and attenuation, obtaining an EAB of 7.1 GHz under 2.0 mm [29]. Although these achievements are achieved, the enhancement of absorption bandwidth and EMA performance in S–C bands are insufficient. Meanwhile, this enhancement often requires compromising on some degree of magnetic loss. Therefore, exploring new dielectric materials to fabricate Fe 3 O 4 -based composites is still needed and extremely desirable. Recently, MoS 2 , emerging as a prominent semiconductor material, features with firm polarization effect, strong dielectric loss, and lightweight, making it extremely popular in improving EMA performance as a novel dielectric material [30-32]. Meanwhile, its electromagnetic wave loss capacity could be efficiently adjusted via morphology, size, and defects [33-35]. Therefore, exerting the dielectric properties of MoS 2 to construct Fe 3 O 4 /MoS 2 magnetic-dielectric composites is undoubtedly an effective strategy to modulate the electromagnetic properties and improve the EMA performances of Fe 3 O 4 particles. Apart from the component selection, structural engineering is another effective way to optimize EMA characteristics. Especially the multi-interface structure design, for example hollow, core-shell, and hierarchical structure, not only can promote impedance matching, but also favor multiple reflection behavior to dissipation electromagnetic waves [36-38]. Given that the large density makes Fe 3 O 4 hard to fulfill the lightweight requirements for EMA applications. Researcher implement hollow engineering in Fe 3 O 4 to reduce mass while retaining the strong magnetic loss and achieve multiple reflection absorbing while extremely decreasing the density. For example, Shu et al . designs Fe 3 O 4 hollow spheres with controllable size-morphology, and investigates the relationship of morphologies and properties, achieving an EAB of 4.68 GHz under 3.62 mm and a RL of −56.90 dB at 8.32 GHz [39]. However, the current absorption intensity and EAB is dissatisfactory for high-performance EMA requirement. It is still needed to explore the correlation of microstructure and EMA characteristics, thereby regulating the electromagnetic properties to achieve ideal EMA performance. Furthermore, recent advancements demonstrate that core-shell structure has a great advantage in allying magnetic component with dielectric component to achieve integrated performances [40-43]. Ning et al . designs and fabricates a core-shell structure Fe 3 O 4 @N-doped carbon@MoS 2 , which well-tuned the magnetic and dielectric loss by manipulating the Fe 3 O 4 component, thereby improving the impedance characteristics [44]. Liu et al . anchored MoS 2 nanoflakes on Fe 3 O 4 @C, which not only compensated the inadequate dielectric loss through interface polarization and dipole polarization, but also promoted multiple reflection of electromagnetic wave, resulting in an EAB of 5.4 GHz and a RL of −36.1 dB [45]. Hence, developing Fe 3 O 4 @MoS 2 composites with hollow Fe 3 O 4 as cores and MoS 2 as shells has great potential in widening the absorbing bandwidth and realizing lightweight characteristic. However, few reports have simultaneously adjusted Fe 3 O 4 and MoS 2 components to systematically elucidate the performance improvement mechanism of Fe 3 O 4 −MoS 2 composite. Moreover, no study of hollow core-shell structure based on Fe 3 O 4 @MoS 2 composites has been reported, the correlation of hollow core-shell engineering and electromagnetic loss mechanisms based on Fe 3 O 4 @MoS 2 is lacking sufficient investigation. Inspired by the aforementioned inspirations, this study designs a hollow core-shell strategy to prepare Fe 3 O 4 @MoS 2 composites with controllable interior cavity diameter and MoS 2 contents. As the core, hollow Fe 3 O 4 exhibits exceptional EMA performance from S to X bands with the strongest RL of −70.21 dB at 5.70 GHz, −69.43 dB at 6.22 GHz, and −81.96 dB at 8.01 GHz. Upon rational component modulation, Fe 3 O 4 @MoS 2 −2 presents a minimum RL of −69.01 dB (16.28 GHz) and EAB of 6.8 GHz, spanning from 11.2 to 18.0 GHz, under 2.66 mm. Particularly, a widest EAB of 8.4 GHz, spanning from 9.6 to 18.0 GHz, can be obtained under 3.0 mm, covering the entire Ku band. Such significantly enhanced EMA performances are attributed to the compositional and core-shell engineering improves the impedance matching, enhances interface polarization, triggers dipole polarization, induces mildly conductive loss and promotes multiple reflections and scatterings absorption of electromagnetic wave. This study manipulates structural and componential engineering simultaneously, promoting the understanding of hollow core-shell heterointerface loss mechanism and providing an important reference to tune broadband EMA. Results And Discussion 2.1 Structure and Composition To construct the hollow core-shell structure composites, Fe 3 O 4 hollow microspheres are initially synthesized through a solvothermal process utilizing ethylene glycerol as the solvent, and FeCl 3 ·6H 2 O as the Fe sources. The formation process in Fig. 1a and TEM images in Fig. 1b reveal that the generation of hollow structures involve the generation of solid microsphere, followed by a chemical evolvement to hollow microsphere, which is related to Ostwald ripening mechanism. Typically, Fe 3 O 4 nucleates and coalesces to each other, forming tiny primary Fe 3 O 4 nanoparticles, these particles aggregate into spherical morphology to reduce the surface energy. Thus, the solid microspheres with rough surface are produced. Extending the reaction time from 12 to 16 h, a small number of inner crystals in pristine solid microspheres are dissolved to induce an internal cavity, and thick shell hollow Fe 3 O 4 microspheres are obtained. Further regulating the reaction time to 20 h, a well-defined hollow structure microsphere with the shell thickness of 100 nm is formed. Eventually prolonging time to 24 h, the products can develop into an extremely thin shell hollow microsphere and even damage. Consequently, the TEM results strongly demonstrate that the controlled reaction time gives hollow Fe 3 O 4 microspheres with adjusted interior space. The corresponding products are donated as Fe 3 O 4 −1, Fe 3 O 4 −2, Fe 3 O 4 −3, and Fe 3 O 4 −4. Given that Fe 3 O 4 −3 has the suitable interior space and unbreakable, it is selected as the cores. XRD pattern is conducted to identify the underlying structure of the obtained Fe 3 O 4 −3 hollow microspheres. As exhibited in Fig. 1c, the observed diffraction profiles can be explicitly indexed to fcc -Fe 3 O 4 ( Fd m (227); cell = 8.3873 nm; JCPDS card no. 89−0691), confirming the Fe 3 O 4 is successfully synthesized. To investigate the morphology and size of Fe 3 O 4 microspheres, SEM and TEM characterization are performed. As depicted by a SEM image in Fig. 1d, the resultant specimens are composed of well-dispersed spherical particles with the size distribution of 300−400 nm. At high magnification, a clearly discernible broken microsphere is observed, indicating that the specimens are hollow structure (Fig. 1e). TEM images demonstrate that all microspheres possess a dark colored edge and light colored interior, and the dark edge is approximately 100 nm, unambiguously affirming a hollow microstructure of Fe 3 O 4 with the shell thickness of ~100 nm (Fig. 2f, g). In the hollow microsphere, Fe and O are uniform spatial distributed as demonstrated by the element mapping (Fig. 1g). A high-resolution TEM image and SAED pattern demonstrate the polycrystalline nature of Fe 3 O 4 hollow microspheres. As shown in Fig. 2h, the distinctly defined lattice plane, exhibiting an interplanar distance of 0.481 nm, belongs to (111) plane of Fe 3 O 4 . From the innermost to the outermost, the diffraction rings in Fig. 2i are corresponded to (220), (311), (400), (511), and (440) planes of fcc -Fe 3 O 4 , respectively. All these results match well with the XRD result, confirming the formation of face-centered cubic structure Fe 3 O 4 hollow microspheres. Such a hollow structure can introduce air medium to optimize impedance matching and afford more contact site to promote multiple scatterings and reflecting of incident wave, thus enhancing the EMA. The subsequent procedure is using a solvothermal process coated Fe 3 O 4 microspheres with a shell of MoS 2 nanoflakes to achieve hollow core-shell structure. During this step, Fe 3 O 4 hollow microspheres are grinded with sodium molybdate and thiourea, then MoS 2 nanosheets are grown and accumulated on the surface of Fe 3 O 4 . The corresponding formation process is illustrated in Fig. 2a. Typically, the contents of MoS 2 nanoflakes can be regulated by changing the addition of molybdate from 0.3 g to 0.7 g, then to 1.0 g. And a mass ratio of molybdate to thiourea is fixed to 1:1. The resulting samples are labeled Fe 3 O 4 @MoS 2 −1, Fe 3 O 4 @MoS 2 −2 and Fe 3 O 4 @MoS 2 −3. To analyze the crystalline state of the obtained Fe 3 O 4 @MoS 2 , the XRD patterns are conducted, and the corresponding results are depicted in Fig. 2b. All Fe 3 O 4 @MoS 2 specimens retain the peak profiles of Fe 3 O 4 . Meanwhile, the Fe 3 O 4 @MoS 2 −2 and Fe 3 O 4 @MoS 2 −3 show a border peak profile around 9.4°, indexed to (002) plane of 1T phase MoS 2 . However, no peak indexed to MoS 2 is observed in Fe 3 O 4 @MoS 2 −1 due to the low content of MoS 2 . To further detect the structure information of Fe 3 O 4 @MoS 2 , SEM and TEM characterization are conducted. By observing the SEM results in Fig. 2c, Fig. 2d and Fig. S1, it can be found the three Fe 3 O 4 @MoS 2 samples present similar morphological changes, on one hand, the diameter of core-shell microsphere increases after growing a good deal of MoS 2 nanoflakes. On the other hand, the surface of microsphere transforms from rough particles to densely packed standing nanoflakes. Taken together, the MoS 2 nanoflakes wrap on the surface of Fe 3 O 4 and form thick shells, resulting in a convex and hierarchical configuration of Fe 3 O 4 @MoS 2 . Such surface diversity can enhance the formation of interfaces, meanwhile, these accumulated MoS 2 nanoflakes can extend the surface area, which is contributed to ameliorate the consumption of electromagnetic wave. The microstructure of Fe 3 O 4 @MoS 2 is further explored through TEM analysis. Evidently, the products deliver a hollow core-shell structure, exhibiting plentiful hetero-interfaces and further confirming the successful construction of MoS 2 nanoflakes shell (Fig. 2e). From a high magnification image in Fig. 2f, the MoS 2 nanoflakes anchoring evenly on Fe 3 O 4 microspheres are observed, coinciding with the SEM results. And the thickness of MoS 2 nanoflakes shells is about 20 nm (Fig. 2f). Diverse MoS 2 layers thickness, including 10 and 50 nm, are also obtained (Fig. S2). By observing a HRTEM image, a lattice spacing of 0.94 nm is discerned, which conforms to the (001) plane of 1T−MoS 2 [46]. This observation aligns with the XRD patterns, indicating a crystalline nature of MoS 2 layers. Moreover, the image also reveals a lattice spacing of 0.62 nm, associated with the (002) plane of 2H−MoS 2 , suggesting the as-prepared MoS 2 shells is 1T phase and 2H phase coexistence. Nevertheless, no peak profile for 2H−MoS 2 appears in the XRD patterns, which possibly due to its low intensity. Given that the distinct physical properties of 1T− and 2H−MoS 2 , their coexistence can introduce ample hetero-interfaces, thus boosting the electromagnetic wave dissipation by interface polarization loss [47]. In the HAADF image and relevant elemental maps of Fe 3 O 4 @MoS 2 −2 (Fig. 2h), the distribution of Mo and S elements reflect the positioning of MoS 2 shell, which are absolutely restricted to the exterior of a hollow microsphere made up of uniformly distributed Fe and O elements, demonstrating a hollow core-shell characteristic of Fe 3 O 4 @MoS 2 . Overall, these series of microstructure information manifest that the desired Fe 3 O 4 @MoS 2 with 1T− and 2H−MoS 2 coexistence is successfully constructed. This hollow and core-shell heterogenous structure show the huge advantage of improving the interface polarization and extending the electromagnetic wave dissipation paths of the composite, which is in favor of boosting EMA performances. The XPS spectra are illustrated to further clarify the elemental compositions and chemical states of Fe 3 O 4 @MoS 2 (Fig. 3). The survey spectra reveal that the presence of Fe, O in Fe 3 O 4 and Fe, O, Mo, S elements coexist in Fe 3 O 4 @MoS 2 (Fig. 3a). This finding is in accord with the elemental mapping images, further indicating the successful anchoring of MoS 2 nanoflakes on hollow Fe 3 O 4 microspheres. To explore the phase structure of MoS 2 nanoflakes, the high-resolution XPS spectrum is also conducted. In the high-resolution of Mo 3d spectra (Fig. 3c), four characteristic peaks could be identified. The peaks that appeared at 232.1 eV and 228.5 eV represent the signals of Mo 4+ 3d 3/2 and 3d 5/2 within 1T phase MoS 2 . Conversely, the peaks that appeared at 232.4 and 228.8 eV are derived from 2H phase MoS 2 . Furthermore, the peak that appeared at 235.4 eV is corresponded to Mo 6+ , which is probably because of the partially oxidized of MoS 2 . While the peak that appeared at 225.9 eV is related to the S 2− state of MoS 2 . The high-resolution S 2p spectra present three distinctive binding energies (Fig. 3d). The binding energies of 162.6 eV and 161.5 eV are associated with S 2p 1/2 and S 2p 3/2 orbitals of 1T−MoS 2 . Similarly, the binding energies of 162.3 eV and 161.2 eV are belonging to S 2p 1/2 and S 2p 3/2 orbitals of 2H-MoS 2 , whereas the binding energy of 168.2 eV is associated with sulfur oxides. The Mo/S ratio calculated from the XPS analyses is 1.99, which implies the existence of S vacancies. These vacancies can induce dipole formation, thereby enhancing dipole polarization loss and ultimately improving the EMA. The status of MoS 2 components in Fe 3 O 4 @MoS 2 is further detected via Raman spectroscopy. The weak E 2g and A 1g signals located at 369.5 cm −1 and 403.5 cm −1 is observed in Fig. 3e, which is contributed to the first-order Raman vibration modes of sulfur, agreeing well with the 2H−MoS 2 [48]. Combined with XRD patterns, TEM images, XPS spectra and Raman spectra, we could conclude the hollow core-shell Fe 3 O 4 @MoS 2 composites are successfully fabricated, and the MoS 2 shells are a mixture heterostructure of 1T−2H MoS 2 with abundant defects. Thanks to the plentiful Fe 3 O 4 -MoS 2 core-shell interface and 1T−2H MoS 2 two-phase interface, as well as the numerous S vacancies defect, the additional interface polarization and dipole polarization can be produced, which is contributed to attenuate incidence electromagnetic wave through polarization loss. The hysteresis loop of Fe 3 O 4 and Fe 3 O 4 @MoS 2 is characterized by vibration sample magnetometer (Fig. 3f-h). The saturation magnetization ( M s ) of Fe 3 O 4 is 80.1, 82.8, 81.4 and 78.5 emu/g with coercivity ( H c ) of 37.2, 26.1, 46.2 and 50.5 Oe (Fig. 3f, h). The anchoring of non-magnetic MoS 2 nanoflakes with large shape anisotropy not only leads to the M s of composites gradually reduce, but also makes a gradually increased H c . As depicted in Fig. 3(g, h), a M s and H c of Fe 3 O 4 @MoS 2 −1, Fe 3 O 4 @MoS 2 −2 and Fe 3 O 4 @MoS 2 −3 is 76.6 emu/g and 51.4 Oe, 67.5 emu/g and 55.4 Oe, as well as 54.3 emu/g and 58.4 Oe. Such magnetic properties could produce magnetic loss in Fe 3 O 4 @MoS 2 . Such high coercivity indicates the large magnetic anisotropy, which is in favor of magnetic resonances in high-frequency [49]. 2.2 Electromagnetic Wave Absorption Mechanism of Hollow Fe 3 O 4 Microspheres To explore the correlation of hollow Fe 3 O 4 structures and EMA performances, the electromagnetic parameters that determining the EMA and reflection are conducted (Fig. 4a and b). The ε′ and ε″ of Fe 3 O 4 −1, Fe 3 O 4 −2, Fe 3 O 4 −3 and Fe 3 O 4 −4 are illustrated in Fig. 4a. Among the four specimens, Fe 3 O 4 −1 with a solid structure shows the lowest ε′ and ε″, whose ɛ′ gradually decreases from 6.25 to 3.81 at 2.0−18.0 GHz, and ε″ elevates from 0.25 (2.0 GHz) to 1.44 (18.0 GHz). From solid Fe 3 O 4 into hollow Fe 3 O 4 , the permittivity improves and continuously increases with the expanded interior space. Specifically, the Fe 3 O 4 −2, Fe 3 O 4 −3 and Fe 3 O 4 −4 harvest the ε′ of ~6.3, ~7.6 and ~8.3. And the ε″ increases from 0.27 to 2.79, 0.37 to 4.07, and 0.35 to 6.22 for Fe 3 O 4 −2, Fe 3 O 4 −3 and Fe 3 O 4 −4. These results demonstrate that the hollow structure indeed favors a higher permittivity, indicating its increasing dielectric property. Additionally, the ɛ′ and ε″ of all Fe 3 O 4 samples displays evident resonance peak from X to Ku bands, indicating multiple polarization relaxation process in these bands [50, 51]. The permeability (μ′, μ″) of Fe 3 O 4 samples within 2.0−18.0 GHz is exhibited in Fig. 4b. It can be found Fe 3 O 4 −1 displays a linearly reduced μ′ from 1.6 to 0.8 (2.0−7.0 GHz) with a small resonant peak at 4.0−5.0 GHz, and then slowly raises to 1.12 (7.0−18 GHz) with a broad resonant peak at 13.5 GHz. The μ″ shows a maximum value of 0.62 at 3.1 GHz, subsequently declining to zero at 10.8 GHz, followed by another peak between 13.0−15.0 GHz, and then turning negative for the remaining frequency range. The negative μ″ implies that some of electric field energies are converted into magnetic energies [52]. Fe 3 O 4 −2, Fe 3 O 4 −3 and Fe 3 O 4 −4 exhibit similar trend and fluctuating behaviors in µ′ and µ″ as that of Fe 3 O 4 −1, but the resonant peaks at 4.0−5.0 GHz and 15.0−17.0 GHz in µ′ as well as the resonant peak at 2.9 GHz in µ″ significantly become stronger. In addition, the resonant peak at 13.5 GHz in µ″ shifts to a higher frequency of 16.0−17.0 GHz. According to the electromagnetic parameters, an EMA performance of Fe 3 O 4 samples is studied using the transmission line theory. RL and EAB (the frequency range of RL ≤ −10 dB) are two key criteria to evaluate the EMA performance. Thus, the dependent RL and EAB of Fe 3 O 4 −1, Fe 3 O 4 −2, Fe 3 O 4 −3 and Fe 3 O 4 −4 on matching thicknesses and frequency are shown in Fig. 4c-i to visually explore the effect of hollow structure on EMA capabilities. From the 2D maps, it is clearly all four specimens show brilliant EMA performance, especially in low frequency range, which can meet <−20.0 dB from 4.0 to 10.0 GHz (Fig. c 1 -f 1 ). For solid Fe 3 O 4 −1, the minimum RL (−46.89 dB) occurs at C band (6.92 GHz) with a 4.34 mm thickness, and the corresponding EAB is 2.3 GHz (5.0−7.3 GHz) (Fig. 4c and h). For hollow Fe 3 O 4 −2 and Fe 3 O 4 −3, the minimum RL (−70.21 dB, −69.43 dB) remains at C band (5.70 GHz, 6.22 GHz) with an extended EAB of 3.4 GHz (4.2−7.6 GHz) and 3.9 GHz (4.4−8.3GHz GHz) at 4.63 mm and 4.01 mm matching thickness (Fig. 4d e and h). As for Fe 3 O 4 −4, the strongest RL can reach up to −81.96 dB under 3.24 mm and shifts to X band (8.01 GHz) (Fig. 4f and h). These results demonstrate that the hollow structure Fe 3 O 4 possess strong absorption characteristic. In terms of EAB, the Fe 3 O 4 −1 exhibits relatively strong but narrow absorption characteristic within 5.0−9.9 GHz with a RL < −20 dB and an EAB ≤ 4.0 GHz at a single thickness (3.5−5.0 mm), covering the C−X bands. However, the EMA capability of Fe 3 O 4 −1 in Ku band is unsatisfied. The RL fails to reach −10 dB within 15.0−18.0 GHz, and the EAB is 0. After forming a hollow structure, the absorption intensities significantly enhance and the EMA in Ku band obvious heightens. Specifically, Fe 3 O 4 −3 shows an effective absorption (< −10.0 dB) of 1.5 GHz under a thin matching thickness of 2.0 mm. More importantly, all RL of Fe 3 O 4 −3 is below −10 dB from 2 to 5 mm, covering from 3.2 to 18.0 GHz, suggesting its best overall EMA performance. These results validate that the fabrication of hollow engineering could adjust electromagnetic properties to ameliorate the EMA performances of Fe 3 O 4 . Upon understanding the EMA performances of Fe 3 O 4 samples, the correlation of enhanced EMA capacities with magnetic and dielectric loss is first elucidated. Compared to Fe 3 O 4 −1, the dielectric loss tangent (tan δε) of Fe 3 O 4 −2, Fe 3 O 4 −3 and Fe 3 O 4 −4 slightly decreases in the whole frequency range (Fig. S3), indicating a slightly declined dielectric loss capability of the hollow structure. Generally, conduction loss and polarization loss are mainly dielectric loss mechanism for EMA [53, 54]. According to the Debye theory, these dielectric loss mechanisms could be visually depicted through Cole−Cole plots, in which a semicircle stands for a polarization process, while a ‘tail’ represents conductivity loss [55]. As depicted in Fig. S4, several distorted and irregular semicircles appear on the curves, indicating multiple relaxation processes [56], which aligns with the ε′ and ε″ curves. These results firmly demonstrate that the dielectric loss capability of Fe 3 O 4 microspheres slightly weakens by implementing hollow engineering, and the polarization loss is predominant mechanism for dielectric loss. Besides dielectric loss, the magnetic loss is another key consumption mechanism for electromagnetic wave absorbing. The magnetic loss tangent (tan δμ) reveals that all three hollow spheres present a prominent improvement in tan δμ within 2.0−12 GHz (Fig. S5), confirming the enhanced magnetic loss ability of the hollow engineering. Typically, the magnetic loss in gigahertz range is primarily attributed to natural resonance, exchange resonance and eddy currents, which could be analyzed by C 0 = μ″ (μ′) −2 f −1 curves [57]. It can be seen the μ″ (μ′) −2 f −1 fluctuates up and down across the whole frequency range (Fig. S6), revealing the magnetic resonances are the primary contributors to magnetic loss. A further comparison of tan δε and tan δμ reveals that in low-frequency, magnetic loss is the predominant mechanism for electromagnetic loss, whereas in high-frequency, the dielectric loss dominates the electromagnetic loss mechanism. Apart from magnetic and dielectric loss, the attenuation ability (𝛼) and impedance matching are essential for evaluating the EMA performances. The analysis of 𝛼 shows that the solid and hollow Fe 3 O 4 microsphere presents the comparable EMA capability (Fig. S7). This may be attributed to a decreased dielectric loss offsets an enhanced magnetic loss. Thus, the outstanding EMA performances of hollow Fe 3 O 4 should be attributed to the improved impedance matching, which is analyzed through impedance matching (Z = |Z in /Z 0 |). Theoretically, Z should be in the range of 0.52–1.92 to guarantee the RL lower than −10 dB [58]. The value is closer to 1, matched impedance is achieved. As exhibited in Fig. S8a, Fe 3 O 4 −1 possess a good impedance matching from C to X band under 3.5−5.0 mm, but in Ku band its impedance matching is poor, resulting in an ungratified EMA in this band. Obviously, the hollow structure not only maintains the good impedance matching in S−X band, but also significantly improves the impedance matching in Ku band (Fig. S8 b-d). Based on the above analysis, the hollow structure improves the impedance match compared with solid counterpart, thereby enhancing the EMA performance. 2.3 Electromagnetic Wave Absorption Mechanism of Hollow Core-Shell Fe 3 O 4 @MoS 2 Microspheres The correlation of hollow core–shell structure based on Fe 3 O 4 @MoS 2 composites and EMA performances is further explored. Firstly, the permittivity (ε′, ε″) is analyzed to elucidate the dielectric loss of Fe 3 O 4 @MoS 2 heterostructures. Compared with Fe 3 O 4 −3, the permittivity of Fe 3 O 4 @MoS 2 significantly changes. Specifically, the ε′ and ε″ of Fe 3 O 4 @MoS 2 shows typical frequency dispersion phenomenon, where the ε′ of Fe 3 O 4 @MoS 2 −1 fluctuation decreases in the 7.02−5.13 range, and the ε″ fluctuates up and down between 2.74 and 1.58 (Fig. 5a, b). By comparison, it is clearly that the ε′ of Fe 3 O 4 @MoS 2 −1 remarkable decrease in 2.0−18.0 GHz, and the ε″ significantly increases from 2.0 to 10.0 GHz. When the MoS 2 nanoflakes forms continuous layer in Fe 3 O 4 @MoS 2 −2 and Fe 3 O 4 @MoS 2 −3, the ε′ ranges from 5.94 to 3.36 (Fe 3 O 4 @MoS 2 −2) and 5.78 to 2.94 (Fe 3 O 4 @MoS 2 −3), showing an obviously decrease with respect to Fe 3 O 4 @MoS 2 −1. Meanwhile, the ε″ varies in the 1.56−2.82 (Fe 3 O 4 @MoS 2 −2) and 1.61−2.80 range (Fe 3 O 4 @MoS 2 −3), showing a slightly increase in comparation to Fe 3 O 4 @MoS 2 −1. The ε′ stands for the capability to store dielectric energies, thus a reduced ε′ suggests the energy storage capability of Fe 3 O 4 @MoS 2 is weaken. Whereas the ε″ stands for the dielectric loss capability, an increased ε″ suggests its dielectric dissipation is enhanced. Besides, the ε″ is intrinsically linked to electrical conductivity based on the free-electron theory [59]. An increased ε″ also implies an ameliorated electrical conductivity in Fe 3 O 4 @MoS 2 , which can produce conduction loss. The tan δε in Fig. 5c shows a similar change to ε″, confirming significantly increased dielectric loss of Fe 3 O 4 @MoS 2 . Furthermore, Fe 3 O 4 @MoS 2 −2 and Fe 3 O 4 @MoS 2 −3 with continuous layer MoS 2 possess a higher tan δε, implying a stronger dielectric loss capability. Cole−Cole semicircle is plotting to clarify the dielectric loss mechanism of Fe 3 O 4 @MoS 2 . Clearly, a plot of Fe 3 O 4 @MoS 2 shows 1 or 2 more semicircle than Fe 3 O 4 (Fig. S9), revealing the increased polarization relaxation processes. This is because the introducing of MoS 2 produces the Fe 3 O 4 −MoS 2 heterointerfaces, promoting interface polarization. Density functional theory (DFT) calculation is conducted to elucidate the polarization effect at heterointerfaces. As illustrated in Fig. 5g, the introduction of MoS 2 induces accumulation and separation of electrons at the coherent interfaces, manifesting the generation of interface polarization. The DOS reveals that the localized carrier concentration near the Fermi level at Fe 3 O 4 @MoS 2 interfaces exceeds that of individual Fe 3 O 4 and MoS 2 , demonstrating a spontaneous electron transfer at the coherent interfaces (Fig. 5h). Additionally, a short tail is found at the end of the Cole−Cole curves, demonstrating conduction loss occurs in Fe 3 O 4 @MoS 2 . Consequently, the integration of MoS 2 to construct hollow core−shell structure, not only adjusts the permittivity by improving the polarization relaxation and enhancing the electronic conductivity, but also induces the conduction loss to enhance the EMA capabilities. More importantly, these dielectric loss characteristics are effectively regulated by tailoring the MoS 2 contents. Fe 3 O 4 @MoS 2 −2 with continuous MoS 2 layer and moderate MoS 2 contents possess the optimal dielectric loss. To clarify the magnetic loss of Fe 3 O 4 @MoS 2 , the permeability (μ′, μ″) is illustrated in Fig. 5d, e. Compared with Fe 3 O 4 , the µ′ has no significant change after the MoS 2 nanoflakes decoration for Fe 3 O 4 @MoS 2 −1 and Fe 3 O 4 @MoS 2 −2, demonstrating the influence of suitable MoS 2 contents on permeability is slight. However, the µ′ of Fe 3 O 4 @MoS 2 −3 clearly decreases across 3.0−18.0 GHz due to a large amount of MoS 2 contents making a significant decrease in M s . Although there is no evident variation in µ′, the µ″ is ameliorated to a certain extent for Fe 3 O 4 @MoS 2 −1 and Fe 3 O 4 @MoS 2 −2. Specifically, the downtrend of µ″ with the increasing frequency is significantly slacken, which is attributed to the shift of resonance frequency towards high frequency. This phenomenon has also been observed in Fe/FeO x @C composites, which helps to promote magnetic loss at high frequency [60]. Fe 3 O 4 @MoS 2 −2 has the slowest downtrend indicates the strongest magnetic loss at high frequency (Fig. 5f). Furthermore, the Fe 3 O 4 @MoS 2 samples exhibit similar resonance peaks in µ″ and tan δμ curves, which is related to the magnetic resonance. This magnetic loss mechanism is demonstrated by C 0 curves, which is fluctuate decreased with the increasing frequency (Fig. S10), suggesting the eddy current is suppressed. These results declare that introducing an appropriate amount of MoS 2 can really ameliorate the µ″ and magnetic loss at high frequency. A consolidated dielectric loss from MoS 2 shells, combined with an inherited magnetic loss from hollow Fe 3 O 4 causes efficient improvement in EMA. As shown in Fig. 5i-l, Fe 3 O 4 @MoS 2 performs excellent EMA in the whole frequency range and its absorption capacity varies with the MoS 2 contents. For Fe 3 O 4 @MoS 2 −1, it shows effective absorption across 5.2−18 GHz with a thickness of 2.0−5.0 mm (Fig. 5i). However, the RL is mainly concentrated between −10 and −20 dB, and the EAB is narrow under 3.0−5.0 mm. At 2.2 mm, the strongest RL of −61.72 dB is obtained at Ku band (16.01 GHz), and the corresponding EAB is 4.9 GHz ranging from 13.1 to 18.0 GHz. Notably, the broadest EAB of Fe 3 O 4 @MoS 2 −1 can reach up to 6.5 GHz (11.5−18.0 GHz) with 2.5 mm, which is covering the whole Ku band. Evidently, Fe 3 O 4 @MoS 2 −1 exhibits broadband absorption characteristics in Ku band with thin thickness. Upon increasing the MoS 2 contents, the minimum RL of Fe 3 O 4 @MoS 2 −2 enhances, and the EAB broadens. For example, Fe 3 O 4 @MoS 2 −2 presents a minimum RL of −69.01 dB (16.28 GHz) and EAB spanning from 11.3 to 18.0 GHz under 2.66 mm (Fig. 5j). Increasing the thickness to 3.5 mm, it still demonstrates a significant RL of −61.68 dB along with a broad EAB of 8.3 GHz. Particularly, under 3.0 mm, a widest EAB of 8.4 GHz, spanning from 9.6 GHz to 18.0 GHz and encompassing the entire Ku band, can be obtained for Fe 3 O 4 @MoS 2 −2. Further increasing the MoS 2 contents, there is no additional improvement in EAB performance. As shown in Fig. 5k, under a distinct increase thickness of 3.83 mm, a slight weakened minimum RL of −63.39 dB is achieved at X band (10.78 GHz). The corresponding EAB spans 7.2 GHz (7.4−14.6 GHz). Even though the EMA performance of Fe 3 O 4 @MoS 2 −3 is decreased in comparison to Fe 3 O 4 @MoS 2 −2, it still possesses a wide EAB of 5.8 GHz (12.2−18 GHz) under 3.0 mm and 7.5 GHz (9.0−16.5 GHz) at 3.5 mm. These results demonstrate a firm correlation of MoS 2 shells modulation engineering and EMA performances. Fig. 5l and Fig. S11 further compares the RL , EAB and matching thickness of Fe 3 O 4 −3 and Fe 3 O 4 @MoS 2 . It can be seen both Fe 3 O 4 and Fe 3 O 4 @MoS 2 possess exceptional minimum RL , but Fe 3 O 4 @MoS 2 exhibits a significant thickness (4.01 mm for Fe 3 O 4 −3, 2.2 mm for Fe 3 O 4 @MoS 2 −1, 2.66 mm for Fe 3 O 4 @MoS 2 −2 and 3.83 mm for Fe 3 O 4 @MoS 2 −3) and broadband advantages (4.2 GHz for Fe 3 O 4 −3, 6.5 GHz for Fe 3 O 4 @MoS 2 −1, 8.4 GHz for Fe 3 O 4 @MoS 2 −2, 7.5 GHz for Fe 3 O 4 @MoS 2 −3). Particularly, the widest EAB greatly improves for Fe 3 O 4 @MoS 2 . Take Fe 3 O 4 @MoS 2 −2 as an example, the widest EAB extends from 4.2 to 8.4 GHz, improving 100% compared to Fe 3 O 4 −3 with a decreased thickness. Consequently, the comparison with RL , EAB and matching thickness results reveal that the hollow core-shell structure shows distinct advantage in RL intensity, EAB bandwidth and thin matching thickness, surely demonstrating an importance of hollow core-shell engineering. The possible EMA mechanisms are illustrated in Fig. 6. First, the anchor of MoS 2 on Fe 3 O 4 not only considerably improves the conductivity of Fe 3 O 4 @MoS 2 , triggering conductivity loss, but also induces plentiful heterointerfaces, increasing the interface polarization loss. Then, the total dielectric loss capability of Fe 3 O 4 @MoS 2 is remarkably strengthened. Second, the Fe 3 O 4 can provide sufficient magnetic loss, including natural resonance and exchange resonance, to consume electromagnetic wave. Third, the integrated MoS 2 greatly decreases the permittivity of Fe 3 O 4 , and fine-tunes the permeability. Such regulation facilitates an effective complementarity to the electromagnetic parameters, and then amplifies the impedance matching, thereby increasing the electromagnetic wave absorbing. Four, a hollow core and hierarchical shell could extend the reflection and scattering areas of electromagnetic wave, leading to multiple reflection/scattering, thus improving the electromagnetic wave dissipation. Notably, the four advantages are also applied to Fe 3 O 4 @MoS 2 −1 and Fe 3 O 4 @MoS 2 −3, while Fe 3 O 4 @MoS 2 −2 has appropriate component, which could produce better impedance matching and the strongest attenuation capability, thereby bringing the greatest EMA performances. Consequently, the design and construction of hollow core-shell microstructure with component manipulation could enhance the impedance matching and attenuation capability simultaneously, making for an outstanding broadband absorbing. Conclusion In conclusion, hollow core-shell Fe 3 O 4 @MoS 2 composites with tunable component are successfully prepared via the solvothermal process. The reaction time occupies a significant position in regulation internal space of hollow microspheres. The growth of MoS 2 creates the hollow core-shell microstructure and provides an effect of composition engineering. The obtained results indicate the integration of structural and compositional regulation not only tune the dielectric properties, but also enhance the magnetic loss in high frequency, thereby significantly broadening the EAB and achieving an optimized EMA characteristic. Especially for the composites with the continuous MoS 2 layers of 20 nm, the strongest RL of − 69.01 dB can be obtained at a thin thickness of 2.66 mm, while the broadest EAB could reach up to 8.4 GHz under 3.0 mm. The mechanisms exploration clarifies that interface polarization, dipole polarization, conductivity loss, ferromagnetic resonance, along with multiple reflections and scattering, work in concert for the enhanced attenuation capability. This work offers a strategy to construct magnetic-dielectric absorbers with tunable composition and optional structure for broadband electromagnetic wave absorbing. Declarations Supplementary Information The Experimental results of hollow Fe 3 O 4 microspheres and hollow core-shell Fe 3 O 4 @MoS 2 microspheres. SEM and TEM images of hollow core-shell Fe 3 O 4 @MoS 2 microspheres. The electromagnetic properties, attenuation coefficient and impedance matching of hollow Fe 3 O 4 microspheres. The Cole−Cole curves, C 0 values and EMA performance of hollow core-shell Fe 3 O 4 @MoS 2 microspheres. Funding This work was financially supported by the National Natural Science Foundation of China (52403356, 52373271), the Natural Science Foundation of Liaoning Province (Grant number 2024-MS-128, 2023-MS-235), the Basic Research Project Educational Department of Liaoning Province (JYTQN2023367) and Shenyang University of Chemical and Technology of "Outstanding youth" plan Funds (2022YQ002). References Zhou X, Min P, Liu Y, Jin M, Yu Z-Z, Zhang H-B (2024) Insulating electromagnetic-shielding silicone compound enables direct potting electronics. Science 385:1205–1210. https://doi.org/10.1126/science.adp6581 Yuan M, Li B, Du Y, Liu J, Zhou X, Cui J, Lv H, Che R (2025) Programmable electromagnetic wave absorption via tailored metal single atom-support interactions. Adv Mater 37:2417580. https://doi.org/10.1002/adma.202417580 Zhou L, Hu P, Bai M, Leng N, Cai B, Peng H-L, Zhao P-Y, Guo Y, He M, Wang G-S, Gu J. (2025) Harnessing the Electronic Spin States of Single Atoms for Precise Electromagnetic Modulation. Adv Mater 37:2418321. https://doi.org/10.1002/adma.202418321 Qu N, Yu Z, Zhang J, Han H, Xing R, Geng L, Kong J (2025) Temperature-robust broadband metamaterial absorber via semiconductor MOFs/paraffin hybridization. Small 21:2409874. https://doi.org/10.1002/smll.202409874 Yang X, Wu Z, Pei K, Qian Y, Lv X, Liu M, Zhang R, Yang K, Ying M, Lai Y, Che R (2025) Confining magnetic response by the surface reorganization of buckling permalloy microspheres for boosting microwave absorption. ACS Nano 19:9144–55. https://doi.org/10.1021/acsnano.4c18320 Zhao R, Gao T, Li Y, Sun Z, Zhang Z, Ji L, Hu C, Liu X, Zhang Z, Zhang X, Qin G (2024) Highly anisotropic Fe 3 C microflakes constructed by solid-state phase transformation for efficient microwave absorption. Nat Commun 15:1497. https://doi.org/10.1038/s41467-024-45815-w Cai B, Zhou L, Zhao P-Y, Peng H-L, Hou Z-L, Hu P, Liu L-M, Wang G-S (2024) Interface-induced dual-pinning mechanism enhances low-frequency electromagnetic wave loss. Nat Commun 15:3299. https://doi.org/10.1038/s41467-024-47537-5 Huang W, Song M, Wang S, Wang B, Ma J, Liu T, Zhang Y, Kang Y, Che R (2024) Dual-step redox engineering of 2D CoNi-alloy embedded B, N-doped carbon layers toward tunable electromagnetic wave absorption and light-weight infrared stealth heat insulation devices. Adv Mater 36:2403322. https://doi.org/10.1002/adma.202403322 Zhang Y, Lan D, Hou T, Jia M, Jia Z, Gu J, Wu G (2024) Multifunctional electromagnetic wave absorbing carbon fiber/Ti 3 C 2 TX MXene fabric with ultra-wide absorption band. Carbon 230:119594. https://doi.org/10.1016/j.carbon.2024.119594 Qu N, Sun H, Sun Y, He M, Xing R, Gu J, Kong J (2024) 2D/2D coupled MOF/Fe composite metamaterials enable robust ultra-broadband microwave absorption. Nat Commun 15:5642. https://doi.org/10.1038/s41467-024-49762-4 Liang G, Bi J, Liang S, Che C, Liu L, Bie S, Yang Y (2025) Structural design and simulation of ultra-broadband TiC x N 1-x fibers/Si 3 N 4 high-temperature microwave absorbing composites. Adv Compos Hybrid Mater 8:198. https://doi.org/10.1007/s42114-025-01280-7 Han Y, Guo H, Qiu H, Hu J, He M, Shi X, Zhang Y, Kong J, Gu J. (2025) Multimechanism decoupling for low-frequency microwave absorption hierarchical Fe-doped Co magnetic microchains. Adv Funct Mater 2506803. https://doi.org/10.1002/adfm.202506803 Chen N, Pan X-F, Guan Z-J, Zhang Y-J, Wang K-J, Jiang J-T (2024) Flower-like hierarchical Fe 3 O 4 -based heterostructured microspheres enabling superior electromagnetic wave absorption. Appl Surf Sci 642:158633. https://doi.org/10.1016/j.apsusc.2023.158633 Lei D, Liu C, Wang S, Zhang P, Li Y, Yang D, Jin Y, Liu Z, Dong C (2025) Multiple synergistic effects of structural coupling and dielectric-magnetic loss in promoting microwave absorption of bark-derived absorbers. Adv Compos Hybrid Mater 8:158. https://doi.org/10.1007/s42114-025-01233-0 Liu P, Zhang G, Xu H, Cheng S, Huang Y, Ouyang B, Qian Y, Zhang R, Che R (2023) Synergistic dielectric-magnetic enhancement via phase-evolution engineering and dynamic magnetic resonance. Adv Funct Mater 33:2211298. https://doi.org/10.1002/adfm.202211298 Han Y, He M, Hu J, Liu P, Liu Z, Ma Z, Ju W, Gu J (2023) Hierarchical design of FeCo-based microchains for enhanced microwave absorption in C band. Nano Res. 16:1773–1778. https://doi.org/10.1007/s12274-022-5111-y Liu P, Li Y, Xu H, Shi L, Kong J, Lv X, Zhang J, Che R (2024) Hierarchical Fe-Co@TiO 2 with incoherent heterointerfaces and gradient magnetic domains for electromagnetic wave absorption. ACS Nano 18:560–570. https://doi.org/10.1021/acsnano.3c08569 Wu Z, Cheng H-W, Jin C, Yang B, Xu C, Pei K, Zhang H, Yang Z, Che R (2022) Dimensional Design and Core–Shell Engineering of Nanomaterials for Electromagnetic Wave Absorption. Adv Mater 34:2107538. https://doi.org/10.1002/adma.202107538 Cui M, Wu T, Gao Z, Hui S, Zhang Y, Wei Y, Zhang J, Wu H (2024) Co/C nanocomposites with tunable condensed states induced by conformation-mediated strategy for electromagnetic wave absorption. Small 20:2402078. https://doi.org/10.1002/smll.202402078 Xing Y, Fan Y, Wang J, Wang M, Xuan Q, Ma Z, Guo W, Mai L (2024) In situ induced interface engineering in hierarchical Fe 3 O 4 enhances performance for alkaline solid-state energy storage. ACS Nano 18:18444–18456. https://doi.org/10.1021/acsnano.4c03301 Zhang H, Zhang M, Liu R, He T, Xiang L, Wu X, Piao Z, Jia Y, Zhang C, Li H, Xu F, Zhou G, Mai Y (2024) Fe 3 O 4 -doped mesoporous carbon cathode with a plumber’s nightmare structure for high-performance Li-S batteries. Nat Commun 15:5451. https://doi.org/10.1038/s41467-024-49826-5 Wei Z, Cai Y, Zhan Y, Meng Y, Pan N, Jiang X, Xia H (2024) Ultra-low loading of ultra-small Fe 3 O 4 nanoparticles on nonmodified CNTs to improve green EMI shielding capability of rubber composites. Small 20:2307148. https://doi.org/10.1002/smll.202307148 Xue Y, Liu X, Lu X. (2024) Hierarchically three-dimensional ZrO 2 /Fe 3 O 4 /C nanocomposites with Janus structure for high-efficiency electromagnetic wave absorption. J Mater Sci Technol 195:126–135. https://doi.org/10.1016/j.jmst.2024.02.031 Sun Y, Liu Y, Zou Y, Wang J, Bai F, Yan J, Huang F (2024) Poorly-/well-dispersed Fe 3 O 4 : Abnormal influence on electromagnetic wave absorption behavior of high-mechanical performance polyurea. Chem Eng J 493:152833. https://doi.org/10.1016/j.cej.2024.152833 Wang X, Xing X, Zhu H, Li J, Liu T (2023) State of the art and prospects of Fe 3 O 4 /carbon microwave absorbing composites from the dimension and structure perspective. Adv Colloid Interface Sci 318:102960. https://doi.org/10.1016/j.cis.2023.102960 Dai B, Dong F, Wang H, Qu Y, Ding J, Ma Y, Ma M, Li T (2023) Fabrication of CuS/Fe 3 O 4 @polypyrrole flower-like composites for excellent electromagnetic wave absorption. J Colloid Interface Sci 634:481–494. https://doi.org/10.1016/j.jcis.2022.12.029 He P, Ma W, Xu J, Wang Y, Cui Z-K, Wei J, Zuo P, Liu X, Zhuang Q (2023) Hierarchical and orderly surface conductive networks in yolk-shell Fe 3 O 4 @C@Co/N-doped C microspheres for enhanced microwave absorption. Small 19:2302961. https://doi.org/10.1002/smll.202302961 Li W, Li B, Zhao Y, Wei X, Guo F (2023) Facile synthesis of Fe 3 O 4 nanoparticles/reduced graphene oxide sandwich composites for highly efficient microwave absorption. J Colloid Interface Sci 645:76–85. https://doi.org/10.1016/j.jcis.2023.04.131 Wang H, Qu Q, Gao J, He Y (2023) Enhanced electromagnetic wave absorption of Fe 3 O 4 @MnO 2 @Ni-Co/C composites derived from Prussian blue analogues. Nanoscale 15:8255–8269. https://doi.org/10.1039/D3NR00868A Feng A, Lan D, Liu J, Wu G, Jia Z (2024) Dual strategy of A-site ion substitution and self-assembled MoS 2 wrapping to boost permittivity for reinforced microwave absorption performance. J Mater Sci Technol 180:1–11. https://doi.org/10.1016/j.jmst.2023.08.060 Wang J, Wu Z, Yang C, Chen G, Yuan M, Li B, Lai Y, Che R (2024) Controllable regulation of MoS 2 surface atomic exposure for boosting interfacial polarization and microwave absorption. Adv Funct Mater 2409923. https://doi.org/10.1002/adfm.202409923 Liu Y, Wang F, Wang Y, Hu B, Xu P, Han X, Du Y. (2024) A combined engineering of hollow and core-shell structures for C@MoS 2 microcapsules toward high-efficiency electromagnetic absorption. Composites, Part B Engineering. 273:111244. https://doi.org/10.1016/j.compositesb.2024.111244 He Z, Xu H, Shi L, Ren X, Kong J, Liu P (2024) Hierarchical Co 2 P/CoS 2 @C@MoS 2 composites with hollow cavity and multiple phases toward wideband electromagnetic wave absorption. Small 20:2306253. https://doi.org/10.1002/smll.202306253 Wu F, Ling M, Zhang L, Zhang Q, Zhang B (2024) Phase-incorporation-induced electromagnetic coupling of NFS@1T/2H-MoS 2 for enhanced microwave absorption. Composites, Part B 270:111136. https://doi.org/10.1016/j.compositesb.2023.111136 Gai L, Zhao H, Li X, Wang P, Yu S, Chen Y, Wang C, Lan D, Han F, Du Y. (2024) Shell engineering afforded dielectric polarization prevails and impedance amelioration toward electromagnetic wave absorption enhancement in nested-network carbon architecture. Chem Eng J 501:157556. https://doi.org/10.1016/j.cej.2024.157556 Peng Q, Yu W, Gao C, Geng L, Fatehi P, Wang S, Kong F (2025) The synergistic effect of hybridization-micro/nano-structural design on the Ti 3 C 2 Tx MXene@CoFe-MOF@chitosan heterojunction enhances the absorption of electromagnetic waves. Adv Compos Hybrid Mater 8:232. https://doi.org/10.1007/s42114-025-01305-1 Jia Z, Sun L, Gao Z, Lan D (2024) Modulating magnetic interface layer on porous carbon heterostructures for efficient microwave absorption. Nano Res 17:10099–10108. https://doi.org/10.1007/s12274-024-6939-0 He M, Hu J, Yan H, Zhong X, Zhang Y, Liu P, Kong J, Gu J (2024) Shape anisotropic chain-like CoNi/polydimethylsiloxane composite films with excellent low-frequency microwave absorption and high thermal conductivity. Adv Funct Mater 2316691. https://doi.org/10.1002/adfm.202316691 Shu X, Zhou J, Lian W, Jiang Y, Wang Y, Shu R, Liu Y, Han J, Zhuang Y (2021) Size-morphology control, surface reaction mechanism and excellent electromagnetic wave absorption characteristics of Fe 3 O 4 hollow spheres. J Alloys Compd 854:157087. https://doi.org/10.1016/j.jallcom.2020.157087 Zhong X, He M, Zhang C, Guo Y, Hu J, Gu J (2024) Heterostructured BN@Co-C@C endowing polyester composites excellent thermal conductivity and microwave absorption at C Band. Adv Funct Mater 34:2313544. https://doi.org/10.1002/adfm.202313544 Zhao B, Yan Z, Liu L, Zhang Y, Guan L, Guo X, Li R, Che R, Zhang R (2024) A liquid-metal-assisted competitive galvanic reaction strategy toward indium/oxide core-shell nanoparticles with enhanced microwave absorption. Adv Funct Mater 34:2314008. https://doi.org/10.1002/adfm.202314008 Meng X, Qiao J, Liu J, Wu L, Wang Z, Wang F (2024) Core-shell nanofibers/polyurethane composites obtained through electrospinning for ultra-broadband electromagnetic wave absorption. Adv Compos Hybrid Mater 7:149. https://doi.org/10.1007/s42114-024-00976-6 Gai L, Wang Y, Wan P, Yu S, Chen Y, Han X, Xu P, Du Y. (2024) Compositional and hollow engineering of silicon carbide/carbon microspheres as high-performance microwave absorbing materials with good environmental tolerance. Nano-Micro Lett 16:167. https://doi.org/10.1007/s40820-024-01369-6 Ning M, Lei Z, Tan G, Man Q, Li J, Li R-W (2021) Dumbbell-like Fe 3 O 4 @N-doped carbon@2H/1T-MoS 2 with tailored magnetic and dielectric loss for efficient microwave absorbing. ACS Appl Mater Interfaces 13:47061–47071. https://doi.org/10.1021/acsami.1c13852 Liu Y, Tian C, Wang F, Hu B, Xu P, Han X, Du Y (2023) Dual-pathway optimization on microwave absorption characteristics of core-shell Fe 3 O 4 @C microcapsules: Composition regulation on magnetic core and MoS 2 nanosheets growth on carbon shell. Chem Eng J 461:141867. https://doi.org/10.1016/j.cej.2023.141867 Wang G, Zhang G, Ke X, Chen X, Chen X, Wang Y, Huang G, Dong J, Chu S, Sui M (2022) Direct synthesis of stable 1T-MoS 2 doped with Ni single atoms for water splitting in alkaline media. Small 18:2107238. https://doi.org/10.1002/smll.202107238 Jia Z, Liu J, Gao Z, Zhang C, Wu G (2024) Molecular intercalation-induced two-phase evolution engineering of 1T and 2H-MS 2 (M = Mo, V, W) for interface-polarization-enhanced electromagnetic absorbers. Adv Funct Mater 2405523. https://doi.org/10.1002/adfm.202405523 Yan Y, Zhang K, Qin G, Gao B, Zhang T, Huang X, Zhou Y (2024) Phase engineering on MoS 2 to realize dielectric gene engineering for enhancing microwave absorbing performance. Adv Funct Mater 2316338. https://doi.org/10.1002/adfm.202316338 Xu C, Luo K, Du Y, Zhang H, Lv X, Lv H, Zhang R, Zhang C, Zhang J, Che R (2023) Anisotropic interfaces support the confined growth of magnetic nanometer-sized heterostructures for electromagnetic wave absorption. Adv Funct Mater 33:2307529. https://doi.org/10.1002/adfm.202307529 Li L, Pan F, Guo H, Jiang H, Wang X, Yao K, Yang Y, Yuan B, Abdalla I, Che R, Lu W (2024) Tailored magnetic spatial confinement with enhanced polarization and magnetic response for electromagnetic wave absorption. Small 2402564. https://doi.org/10.1002/smll.202402564 Zhang Y, Yang S-H, Xin Y, Cai B, Hu P-F, Dai H-Y, Liang C-M, Meng Y-T, Su J-H, Zhang X-J, Lu M, Wang G-S (2024) Designing symmetric gradient honeycomb structures with carbon-coated iron-based composites for high-efficiency microwave absorption. Nano-Micro Lett 16:234. https://doi.org/10.1007/s40820-024-01435-z Huang W, Wang W, Su C, Song M, Kang Y, Fei G (2024) Hetero-interface engineering on 9.0 wt% CoO x -doped CeO 2 nanorods as electromagnetic wave absorber and integrated into multifunctional aerogel. Small 20:2311389. https://doi.org/10.1002/smll.202311389 Guo Y, Long H, Wang Z, Luo S, Xu L, Liu C, Shen C, Liu H (2025) Self-catalyzed growth of Co-N codoped carbon nanotubes for advanced multi-heterointerface engineering in hierarchical carbonaceous microwave absorbers. Adv Compos Hybrid Mater 8:207. https://doi.org/10.1007/s42114-024-01209-6 Zhao T, Lan D, Jia Z, Gao Z, Wu G (2024) Hierarchical porous molybdenum carbide synergic morphological engineering towards broad multi-band tunable microwave absorption. Nano Res 17:9845–9856. https://doi.org/10.1007/s12274-024-6938-1 He Q, Tang Q, Yuan Y, Qi J, Sun K, Shi Z, Fan R (2025) Interface decoupling and capacitance modulation in flexible laminated polyetherimide-based nanocomposites via hierarchical incorporation. Adv Compos Hybrid Mater 8:209. https://doi.org/10.1007/s42114-024-01206-9 Zhang X, Tian X, Wu N, Zhao S, Qin Y, Pan F, Yue S, Ma X, Qiao J, Xu W, Liu W, Liu J, Zhao M, Ostrikov K, Zeng Z (2024) Metal-organic frameworks with fine-tuned interlayer spacing for microwave absorption. Sci Adv 10:eadl6498. https://www.science.org/doi/10.1126/sciadv.adl6498 He M, Zhong X, Lu X, Hu J, Ruan K, Guo H, Zhang Y, Guo Y, Gu J (2024) Excellent low-frequency microwave absorption and high thermal conductivity in polydimethylsiloxane composites endowed by hydrangea-like CoNi@BN heterostructure fillers. Adv Mater 2410186. https://doi.org/10.1002/adma.202410186 Deng W, Li T, Li H, Dang A, Liu X, Zhai J, Wu H (2023) Morphology modulated defects engineering from MnO 2 supported on carbon foam toward excellent electromagnetic wave absorption. Carbon 206:192–200. https://doi.org/10.1016/j.carbon.2023.02.039 Zhou Z, Lan D, Ren J, Cheng Y, Jia Z, Wu G, Yin P (2024) Controllable heterogeneous interfaces and dielectric modulation of biomass-derived nanosheet metal-sulfide complexes for high-performance electromagnetic wave absorption. J Mater Sci Technol 185:165–173. https://doi.org/10.1016/j.jmst.2023.11.010 Zhang M, Wang L, Bao S, Song Z, Chen W, Jiang Z, Xie Z, Zheng L (2023) A finite oxidation strategy for customizing heterogeneous interfaces to enhance magnetic loss ability and microwave absorption of Fe-cored carbon microcapsules. Nano Res 16:11084–11095. https://doi.org/10.1007/s12274-023-5511-7 Additional Declarations No competing interests reported. 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Technology","correspondingAuthor":false,"prefix":"","firstName":"Ru-Yu","middleName":"","lastName":"Wang","suffix":""},{"id":464810267,"identity":"723f6541-f901-46c3-b137-719ac71426fd","order_by":2,"name":"Xue-Feng Pan","email":"","orcid":"","institution":"Shenyang University of Chemical Technology","correspondingAuthor":false,"prefix":"","firstName":"Xue-Feng","middleName":"","lastName":"Pan","suffix":""},{"id":464810268,"identity":"34bb584a-28e1-4d44-b0cb-aea2c5633e20","order_by":3,"name":"Bing-Bing Han","email":"","orcid":"","institution":"Shenyang University of Chemical Technology","correspondingAuthor":false,"prefix":"","firstName":"Bing-Bing","middleName":"","lastName":"Han","suffix":""},{"id":464810269,"identity":"3b2a6bc0-79a1-4fde-a0e9-6482f7cc29e0","order_by":4,"name":"Jia-Xin Li","email":"","orcid":"","institution":"Shenyang University of Chemical 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Technology","correspondingAuthor":false,"prefix":"","firstName":"Kang-Jun","middleName":"","lastName":"Wang","suffix":""},{"id":464810274,"identity":"049826ab-5813-4028-a5f5-6889bee7d12b","order_by":8,"name":"Xiao-Guang San","email":"","orcid":"","institution":"Shenyang University of Chemical Technology","correspondingAuthor":false,"prefix":"","firstName":"Xiao-Guang","middleName":"","lastName":"San","suffix":""},{"id":464810276,"identity":"38f009fa-f823-4f35-a349-8db2b3b2c72e","order_by":9,"name":"Panbo Liu","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA0klEQVRIiWNgGAWjYBACPmYwdYCBHyrA2EBICxtMi2QD0VoYoFoMDhCthZ3H7MHPHXfkjG/3mD3mYbCR3XCA+dkD/A7jMTfsPfPM2OzOGXNjHoY04w0H2MwNCGgxk+BtO5y47UbuNmkehsOJGw7wsEkQ0iL5F6hl8wywlv/EaZEG2bJBAqzlADFa2MqNZdueGUvcyP9uOMcg2XjmYTYzvFr4+Q9ve/i27Y4c/4y0tAdvKuxk+443P8OrhQEeNWAGKKiYCahH0zIKRsEoGAWjAAsAAML6QrqAnsnBAAAAAElFTkSuQmCC","orcid":"","institution":"Northwestern Polytechnical University","correspondingAuthor":true,"prefix":"","firstName":"Panbo","middleName":"","lastName":"Liu","suffix":""}],"badges":[],"createdAt":"2025-04-28 10:23:08","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-6546742/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-6546742/v1","draftVersion":[],"editorialEvents":[{"content":"https://doi.org/10.1007/s42114-025-01393-z","type":"published","date":"2025-07-11T15:56:59+00:00"}],"editorialNote":"","failedWorkflow":false,"files":[{"id":83786202,"identity":"c64e2877-7518-4e6f-9536-6647096e0eaf","added_by":"auto","created_at":"2025-06-02 17:06:57","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":844700,"visible":true,"origin":"","legend":"\u003cp\u003eThe microstructural characterization of Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e hollow microsphere. \u003cstrong\u003ea\u003c/strong\u003e Schematic illustration of the formation procedure and \u003cstrong\u003eb\u003c/strong\u003e TEM images of time-controlled structure evolution of Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e hollow microsphere, \u003cstrong\u003ec\u003c/strong\u003e XRD pattern, \u003cstrong\u003ed-e\u003c/strong\u003e SEM images, \u003cstrong\u003ef-g\u003c/strong\u003e TEM images and corresponding elemental mapping of Fe and O, \u003cstrong\u003eh\u003c/strong\u003e HRTEM image, \u003cstrong\u003ei \u003c/strong\u003eSAED pattern.\u003c/p\u003e","description":"","filename":"image1.png","url":"https://assets-eu.researchsquare.com/files/rs-6546742/v1/f451e8435aedf2606ec2a8b2.png"},{"id":83786201,"identity":"8e756475-ce7d-4b50-a726-8d1cead96465","added_by":"auto","created_at":"2025-06-02 17:06:57","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":712162,"visible":true,"origin":"","legend":"\u003cp\u003eThe microstructural characterization of Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e@MoS\u003csub\u003e2\u003c/sub\u003e. \u003cstrong\u003ea\u003c/strong\u003e Schematic illustration of the construction of hollow core-shell structure, \u003cstrong\u003eb\u003c/strong\u003e XRD patterns of Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e@MoS\u003csub\u003e2\u003c/sub\u003e, \u003cstrong\u003ec-d\u003c/strong\u003e SEM images, \u003cstrong\u003ee-f\u003c/strong\u003e TEM images and \u003cstrong\u003eg\u003c/strong\u003e HRTEM image of Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e@MoS\u003csub\u003e2\u003c/sub\u003e−2, \u003cstrong\u003eh\u003c/strong\u003e STEM-HAADF and corresponding elemental mapping images of Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e@MoS\u003csub\u003e2\u003c/sub\u003e−2. The scale bar in h is 100 nm.\u003c/p\u003e","description":"","filename":"image2.png","url":"https://assets-eu.researchsquare.com/files/rs-6546742/v1/ec4c2eadd45072a8fc375877.png"},{"id":83786847,"identity":"3011ff40-7d24-4c6a-9184-f85898ef943f","added_by":"auto","created_at":"2025-06-02 17:22:57","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":937428,"visible":true,"origin":"","legend":"\u003cp\u003eThe structure, component, and magnetic properties of Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e and Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e@MoS\u003csub\u003e2\u003c/sub\u003e. \u003cstrong\u003ea\u003c/strong\u003e XPS spectra, \u003cstrong\u003eb\u003c/strong\u003e Fe 2p, \u003cstrong\u003ec\u003c/strong\u003e Mo 3d, \u003cstrong\u003ed\u003c/strong\u003e S 2p, \u003cstrong\u003ee\u003c/strong\u003e Raman spectra, the hysteresis loop of \u003cstrong\u003ef\u003c/strong\u003e Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e and \u003cstrong\u003eg\u003c/strong\u003e Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e@MoS\u003csub\u003e2\u003c/sub\u003e, \u003cstrong\u003eh\u003c/strong\u003e the comparison of \u003cem\u003eM\u003c/em\u003e\u003csub\u003e\u003cem\u003es\u003c/em\u003e\u003c/sub\u003e and \u003cem\u003eH\u003c/em\u003e\u003csub\u003e\u003cem\u003ec\u003c/em\u003e\u003c/sub\u003e.\u003c/p\u003e","description":"","filename":"image3.png","url":"https://assets-eu.researchsquare.com/files/rs-6546742/v1/38ed1df1c8134908c2c79243.png"},{"id":83786656,"identity":"cc9c571d-9bf6-4f6c-a7cc-38966d2ff5ca","added_by":"auto","created_at":"2025-06-02 17:14:57","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":650865,"visible":true,"origin":"","legend":"\u003cp\u003eThe electromagnetic parameters and electromagnetic wave absorption performance of Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e. \u003cstrong\u003ea\u003c/strong\u003e ε′ and ε″, \u003cstrong\u003eb\u003c/strong\u003e µ′ and µ″, \u003cstrong\u003ec−f\u003c/strong\u003e 2D \u003cem\u003eRL\u003c/em\u003e maps and \u003cem\u003eRL\u003c/em\u003e curves for \u003cstrong\u003ec\u003c/strong\u003e Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e−1, \u003cstrong\u003ed\u003c/strong\u003e Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e−2, \u003cstrong\u003ee\u003c/strong\u003e Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e−3, and \u003cstrong\u003ef\u003c/strong\u003e Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e−4. \u003cstrong\u003eg−i\u003c/strong\u003e The comparison of EMA performance of a series of Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e, \u003cstrong\u003eg\u003c/strong\u003e EAB under thickness of 2−5 mm, \u003cstrong\u003eh\u003c/strong\u003e the minimum \u003cem\u003eRL\u003c/em\u003e and \u003cstrong\u003ei\u003c/strong\u003e broadest EAB with corresponding matching thickness.\u003c/p\u003e","description":"","filename":"image4.png","url":"https://assets-eu.researchsquare.com/files/rs-6546742/v1/52a1269d5690de67899edf30.png"},{"id":83786206,"identity":"10410976-9b7f-40e3-974b-c36d70c5f955","added_by":"auto","created_at":"2025-06-02 17:06:57","extension":"png","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":931849,"visible":true,"origin":"","legend":"\u003cp\u003eThe electromagnetic parameters and electromagnetic wave absorption performance of Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e@MoS\u003csub\u003e2\u003c/sub\u003e. \u003cstrong\u003ea\u003c/strong\u003e ε′, \u003cstrong\u003eb\u003c/strong\u003e ε″, \u003cstrong\u003ec\u003c/strong\u003e tan δε, \u003cstrong\u003ed\u003c/strong\u003e μ′, \u003cstrong\u003ee\u003c/strong\u003e μ″, \u003cstrong\u003ef\u003c/strong\u003e tan δμ, \u003cstrong\u003eg\u003c/strong\u003e the charge density difference and \u003cstrong\u003eh\u003c/strong\u003e calculated DOS on the hetero-interfaces; 2D map and \u003cem\u003eRL\u003c/em\u003e curves of \u003cstrong\u003ei\u003c/strong\u003e Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e@MoS\u003csub\u003e2\u003c/sub\u003e−1, \u003cstrong\u003ej\u003c/strong\u003e Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e@MoS\u003csub\u003e2\u003c/sub\u003e−2 and \u003cstrong\u003ek\u003c/strong\u003e Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e@MoS\u003csub\u003e2\u003c/sub\u003e−3, \u003cstrong\u003el\u003c/strong\u003e the comparison of the broadest EAB and corresponding matching thickness for Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e−3 and a series of Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e@MoS\u003csub\u003e2\u003c/sub\u003e.\u003c/p\u003e","description":"","filename":"image5.png","url":"https://assets-eu.researchsquare.com/files/rs-6546742/v1/07c06f904cc49a0447b40a9b.png"},{"id":83786205,"identity":"c5f40a81-f925-4291-b114-6a9341478fb1","added_by":"auto","created_at":"2025-06-02 17:06:57","extension":"png","order_by":6,"title":"Figure 6","display":"","copyAsset":false,"role":"figure","size":281831,"visible":true,"origin":"","legend":"\u003cp\u003eSchematic illustration of the EMA mechanism of Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e@MoS\u003csub\u003e2\u003c/sub\u003e.\u003c/p\u003e","description":"","filename":"image6.png","url":"https://assets-eu.researchsquare.com/files/rs-6546742/v1/afd0751d75432222ef2f488f.png"},{"id":86699251,"identity":"aeb11b57-b28d-4a99-9d85-c0f03e4affba","added_by":"auto","created_at":"2025-07-14 16:05:38","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":5273403,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-6546742/v1/0576073e-c7eb-4572-90f5-dd9e9fe73a2a.pdf"},{"id":83786207,"identity":"57df0df9-91bd-4a9b-828c-b1b8cecb0536","added_by":"auto","created_at":"2025-06-02 17:06:57","extension":"docx","order_by":0,"title":"","display":"","copyAsset":false,"role":"supplement","size":4766362,"visible":true,"origin":"","legend":"","description":"","filename":"Supplementarymaterial.docx","url":"https://assets-eu.researchsquare.com/files/rs-6546742/v1/721f512e8b0c6bad08ee94e0.docx"}],"financialInterests":"No competing interests reported.","formattedTitle":"\u003cp\u003eHollow Engineering of Core-Shell Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e@MoS\u003csub\u003e2\u003c/sub\u003e Microspheres with Controllable Interior toward Optimized Electromagnetic Attenuation\u003c/p\u003e","fulltext":[{"header":"Introduction","content":"\u003cp\u003eThe flourish evolution of electronic technology is propelling the world into a smart era [1-3]. People enjoy the benefit of technological advancement, whereas the incidental electromagnetic pollution poses impacts on people\u0026rsquo;s health and military safety [4-6]. EMA materials, which have the ability to transform the electromagnetic energy into heat, play a crucial role in dealing with electromagnetic pollution and signal shielding [7-9]. In recent years, substantial studies have implemented structural and compositional engineering to improve the performance of EMA materials [10-12]. Among all the achievements, magnetic-dielectric heterostructure composite (e.g., FeNi\u003csub\u003e3\u003c/sub\u003e/C, Co\u003csub\u003e7\u003c/sub\u003eFe\u003csub\u003e3\u003c/sub\u003e/SiO\u003csub\u003e2\u003c/sub\u003e, Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e/C, and CoNi/TiO\u003csub\u003e2\u003c/sub\u003e) makes tremendous progress in terms of bandwidth expansion and\u003cem\u003e\u0026nbsp;RL\u003c/em\u003e enhancement, enabling them highly sought in EMA field [13-19]. However, the challenges of broadband absorbing with thin thickness remain unsolved. The couplings of component/loss mechanism underlying the consumption of electromagnetic wave based on the magnetic-dielectric synergistic structure remain abstruse. Therefore, it still needs further study to construct magnetic-dielectric composites to achieve powerful EMA performances and understand the loss mechanisms.\u003c/p\u003e\n\u003cp\u003eFe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e, as a typical ferrite, is widely applied in electromagnetic wave attenuation, electronic devices, magnetic fluid, energy storage, catalysis, and biomedicine due to its interesting magnetic properties and high chemical stability [20-23]. For electromagnetic wave absorbing purposes, the tunable morphology, suitable saturation magnetization and high permeability, are attractive features to effectively promote electromagnetic wave attenuation [24-26]. Numerous studies have been devoted to construct Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e-based magnetic-dielectric composites to\u0026nbsp;regulate electromagnetic properties and enhance impedance matching, thereby overcoming its limitations of narrow absorption bandwidth and inferior EMA in S\u0026ndash;C bands. For example, He \u003cem\u003eet al\u003c/em\u003e. reported a quantitative design approach to enhance the attenuation properties of Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e@C@Co/N-doped C composite, which endow the composite with high magnetic loss, dielectric loss, and multi-reflections/scatterings, thus resulting in an EAB of 6.49 GHz and a \u003cem\u003eRL\u003c/em\u003e of \u0026minus;66.39 dB [27]. Li \u003cem\u003eet al\u003c/em\u003e. proposed a component regulation that sandwiching Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e into rGO, which facilitates the interface polarization and modulates the complex permittivity, thus obtaining an EAB of 5.7 GHz and a \u003cem\u003eRL\u003c/em\u003e of \u0026minus;49.9 dB [28]. Wang \u003cem\u003eet al\u003c/em\u003e. exploited the multicomponent synergistic effect within magnetic Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e, Ni\u0026ndash;Co and dielectric MnO\u003csub\u003e2\u003c/sub\u003e, effectively boosting impedance matching and attenuation, obtaining an EAB of 7.1 GHz under 2.0 mm [29]. Although these achievements are achieved, the enhancement of absorption bandwidth and EMA performance in S\u0026ndash;C bands are insufficient. Meanwhile, this enhancement often requires compromising on some degree of magnetic loss. Therefore, exploring new dielectric materials to fabricate Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e-based composites is still needed and extremely desirable. Recently, MoS\u003csub\u003e2\u003c/sub\u003e, emerging as a prominent semiconductor material, features with firm polarization effect, strong dielectric loss, and lightweight, making it extremely popular in improving EMA performance as a novel dielectric material [30-32].\u0026nbsp;Meanwhile, its electromagnetic wave loss capacity could be efficiently adjusted via morphology, size, and defects [33-35]. Therefore,\u0026nbsp;exerting the dielectric properties of MoS\u003csub\u003e2\u003c/sub\u003e to\u0026nbsp;construct Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e/MoS\u003csub\u003e2\u003c/sub\u003e magnetic-dielectric composites is undoubtedly an effective strategy to modulate the electromagnetic properties and improve the EMA performances of Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e particles.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eApart from the component selection, structural engineering is another effective way to optimize EMA characteristics.\u0026nbsp;Especially the multi-interface structure design, for example hollow, core-shell, and hierarchical structure, not only can promote impedance matching, but also favor multiple reflection behavior to dissipation electromagnetic waves [36-38]. Given that the large density makes Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e hard to fulfill the lightweight requirements for EMA applications. Researcher implement hollow engineering in Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e to reduce mass while retaining the strong magnetic loss and achieve multiple reflection absorbing while extremely decreasing the density. For example, Shu \u003cem\u003eet al\u003c/em\u003e. designs Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e hollow spheres with controllable size-morphology, and investigates the relationship of morphologies and properties, achieving an EAB of 4.68 GHz under 3.62 mm and a \u003cem\u003eRL\u003c/em\u003e of \u0026minus;56.90 dB at 8.32 GHz [39]. However, the current absorption intensity and EAB is dissatisfactory for high-performance EMA requirement. It is still needed to explore the correlation of microstructure and EMA characteristics, thereby regulating the electromagnetic properties to achieve ideal EMA performance. Furthermore, recent advancements demonstrate that core-shell structure has a great advantage in allying magnetic component with dielectric component to achieve integrated performances [40-43]. Ning \u003cem\u003eet al\u003c/em\u003e. designs and fabricates a core-shell structure Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e@N-doped carbon@MoS\u003csub\u003e2\u003c/sub\u003e, which well-tuned the magnetic and dielectric loss by manipulating the Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e component, thereby improving the impedance characteristics [44]. Liu \u003cem\u003eet al\u003c/em\u003e. anchored MoS\u003csub\u003e2\u003c/sub\u003e nanoflakes on Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e@C, which not only compensated the inadequate dielectric loss through interface polarization and dipole polarization, but also promoted multiple reflection of electromagnetic wave, resulting in an EAB of 5.4 GHz and a \u003cem\u003eRL\u003c/em\u003e of \u0026minus;36.1 dB [45]. Hence, developing Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e@MoS\u003csub\u003e2\u003c/sub\u003e composites with hollow Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e as cores and MoS\u003csub\u003e2\u003c/sub\u003e as shells has great potential in widening the absorbing bandwidth and realizing lightweight characteristic. However, few reports have simultaneously adjusted Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e and MoS\u003csub\u003e2\u003c/sub\u003e components to systematically elucidate the performance improvement mechanism of Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e\u0026minus;MoS\u003csub\u003e2\u003c/sub\u003e composite. Moreover, no study of hollow core-shell structure based on Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e@MoS\u003csub\u003e2\u003c/sub\u003e composites has been reported, the correlation of hollow core-shell engineering and electromagnetic loss mechanisms based on Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e@MoS\u003csub\u003e2\u003c/sub\u003e is lacking sufficient investigation.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eInspired by the aforementioned inspirations, this study designs a hollow core-shell strategy to prepare Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e@MoS\u003csub\u003e2\u003c/sub\u003e composites with controllable interior cavity diameter and MoS\u003csub\u003e2\u003c/sub\u003e contents. As the core, hollow Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e exhibits exceptional EMA performance from S to X bands with the strongest \u003cem\u003eRL\u003c/em\u003e of\u0026nbsp;\u0026minus;70.21 dB at\u0026nbsp;5.70 GHz, \u0026minus;69.43 dB at 6.22 GHz, and \u0026minus;81.96 dB\u0026nbsp;at 8.01 GHz.\u0026nbsp;Upon rational component modulation, Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e@MoS\u003csub\u003e2\u003c/sub\u003e\u0026minus;2 presents a\u0026nbsp;minimum \u003cem\u003eRL\u003c/em\u003e of \u0026minus;69.01 dB (16.28 GHz) and EAB of 6.8 GHz, spanning from 11.2 to 18.0 GHz, under 2.66 mm. Particularly, a widest EAB of 8.4 GHz, spanning from 9.6 to 18.0 GHz, can be obtained under 3.0 mm, covering the entire Ku band. Such significantly enhanced EMA performances are attributed to the compositional and core-shell engineering improves the impedance matching, enhances interface polarization, triggers dipole polarization, induces mildly conductive loss and promotes multiple reflections and scatterings absorption of electromagnetic wave. This study manipulates structural and componential engineering simultaneously, promoting the understanding of hollow core-shell heterointerface loss mechanism and providing an important reference to tune broadband EMA.\u003c/p\u003e"},{"header":"Results And Discussion","content":"\u003cp\u003e\u003cstrong\u003e2.1 Structure and Composition\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eTo construct the hollow core-shell structure composites, Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e hollow microspheres are initially synthesized through a solvothermal process utilizing ethylene glycerol as the solvent, and FeCl\u003csub\u003e3\u003c/sub\u003e\u0026middot;6H\u003csub\u003e2\u003c/sub\u003eO as the Fe sources. The formation process in Fig. 1a and TEM images in Fig. 1b reveal that the generation of hollow structures involve the generation of solid microsphere, followed by a chemical evolvement to hollow microsphere, which is related to Ostwald ripening mechanism. Typically, Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e nucleates and coalesces to each other, forming tiny primary Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e nanoparticles, these particles aggregate into spherical morphology to reduce the surface energy. Thus, the solid microspheres with rough surface are produced. Extending the reaction time from 12 to 16 h, a small number of inner crystals in pristine solid microspheres are dissolved to induce an internal cavity, and thick shell hollow Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e microspheres are obtained. Further regulating the reaction time to 20 h, a well-defined hollow structure microsphere with the shell thickness of 100 nm is formed. Eventually prolonging time to 24 h, the products can develop into an extremely thin shell hollow microsphere and even damage. Consequently, the TEM results strongly demonstrate that the controlled reaction time gives hollow Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e microspheres with adjusted interior space. The corresponding products are donated as Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e\u0026minus;1, Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e\u0026minus;2, Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e\u0026minus;3, and Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e\u0026minus;4. Given that Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e\u0026minus;3 has the suitable interior space and unbreakable, it is selected as the cores. XRD pattern is conducted to identify the underlying structure of the obtained Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e\u0026minus;3 hollow microspheres. As exhibited in Fig. 1c, the observed diffraction profiles can be explicitly indexed to \u003cem\u003efcc\u003c/em\u003e-Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e (\u003cem\u003eFd\u003c/em\u003e\u003cimg width=\"9\" height=\"19\" src=\"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAAkAAAATCAMAAAB1AtffAAAAAXNSR0IArs4c6QAAAEhQTFRFAAAAAAAAAAA6ADpmADqQOgAAOpC2OpDbZgAAZjo6ZrbbZrb/kDoAkNv/tmYAtmY625A627aQ29u22////7Zm/9uQ//+2///bcqJezwAAAAF0Uk5TAEDm2GYAAAAJcEhZcwAADsQAAA7EAZUrDhsAAAAZdEVYdFNvZnR3YXJlAE1pY3Jvc29mdCBPZmZpY2V/7TVxAAAATklEQVQYV2NgwAvEOBhBgEUYuypxflZGJjagnDgPmzCDACM3VJkoK5QlxMkFFhJhZGTmhUqK8zHBmGIc7FBBMEucB0gIgGUFOZF04HQiAMIVAipX0P4LAAAAAElFTkSuQmCC\" alt=\"image\"\u003e\u003cem\u003em\u003c/em\u003e (227); cell = 8.3873 nm; JCPDS card no. 89\u0026minus;0691), confirming the Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e is successfully synthesized. To investigate the morphology and size of Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e microspheres, SEM and TEM characterization are performed. As depicted by a SEM image in Fig. 1d, the resultant specimens are composed of well-dispersed spherical particles with the size distribution of 300\u0026minus;400 nm. At high magnification, a clearly discernible broken microsphere is observed, indicating that the specimens are hollow structure (Fig. 1e). TEM images demonstrate that all microspheres possess a dark colored edge and light colored interior, and the dark edge is approximately 100 nm, unambiguously affirming a hollow microstructure of Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e with the shell thickness of ~100 nm (Fig. 2f, g). In the hollow microsphere, Fe and O are uniform spatial distributed as demonstrated by the element mapping (Fig. 1g). A high-resolution TEM image and SAED pattern demonstrate the polycrystalline nature of Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e hollow microspheres. As shown in Fig. 2h, the distinctly defined lattice plane, exhibiting an interplanar distance of 0.481 nm, belongs to (111) plane of Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e. From the innermost to the outermost, the diffraction rings in Fig. 2i are corresponded to (220), (311), (400), (511), and (440) planes of \u003cem\u003efcc\u003c/em\u003e-Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e, respectively. All these results match well with the XRD result, confirming the formation of face-centered cubic structure Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e hollow microspheres. Such a hollow structure can introduce air medium to optimize impedance matching and afford more contact site to promote multiple scatterings and reflecting of incident wave, thus enhancing the EMA.\u003c/p\u003e\n\u003cp\u003eThe subsequent procedure is using a solvothermal process coated Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e microspheres with a shell of MoS\u003csub\u003e2\u003c/sub\u003e nanoflakes to achieve hollow core-shell structure. During this step, Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e hollow microspheres are grinded with sodium molybdate and thiourea, then MoS\u003csub\u003e2\u003c/sub\u003e nanosheets are grown and accumulated on the surface of Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e. The corresponding formation process is illustrated in Fig. 2a. Typically, the contents of MoS\u003csub\u003e2\u003c/sub\u003e nanoflakes can be regulated by changing the addition of molybdate from 0.3 g to 0.7 g, then to 1.0 g. And a mass ratio of molybdate to thiourea is fixed to 1:1. The resulting samples are labeled Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e@MoS\u003csub\u003e2\u003c/sub\u003e\u0026minus;1, Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e@MoS\u003csub\u003e2\u003c/sub\u003e\u0026minus;2 and Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e@MoS\u003csub\u003e2\u003c/sub\u003e\u0026minus;3. To analyze the crystalline state of the obtained Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e@MoS\u003csub\u003e2\u003c/sub\u003e, the XRD patterns are conducted, and the corresponding results are depicted in Fig. 2b. All Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e@MoS\u003csub\u003e2\u003c/sub\u003e specimens retain the peak profiles of Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e. Meanwhile, the Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e@MoS\u003csub\u003e2\u003c/sub\u003e\u0026minus;2 and Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e@MoS\u003csub\u003e2\u003c/sub\u003e\u0026minus;3 show a border peak profile around 9.4\u0026deg;, indexed to (002) plane of 1T phase MoS\u003csub\u003e2\u003c/sub\u003e. However, no peak indexed to MoS\u003csub\u003e2\u003c/sub\u003e is observed in Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e@MoS\u003csub\u003e2\u003c/sub\u003e\u0026minus;1 due to the low content of MoS\u003csub\u003e2\u003c/sub\u003e. To further detect the structure information of Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e@MoS\u003csub\u003e2\u003c/sub\u003e, SEM and TEM characterization are conducted. By observing the SEM results in Fig. 2c, Fig. 2d and Fig. S1, it can be found the three Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e@MoS\u003csub\u003e2\u003c/sub\u003e samples present similar morphological changes, on one hand, the diameter of core-shell microsphere increases after growing a good deal of MoS\u003csub\u003e2\u003c/sub\u003e nanoflakes. On the other hand, the surface of microsphere transforms from rough particles to densely packed standing nanoflakes. Taken together, the MoS\u003csub\u003e2\u003c/sub\u003e nanoflakes wrap on the surface of Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e and form thick shells, resulting in a convex and hierarchical configuration of Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e@MoS\u003csub\u003e2\u003c/sub\u003e. Such surface diversity can enhance the formation of interfaces, meanwhile, these accumulated MoS\u003csub\u003e2\u003c/sub\u003e nanoflakes can extend the surface area, which is contributed to ameliorate the consumption of electromagnetic wave. The microstructure of Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e@MoS\u003csub\u003e2\u003c/sub\u003e is further explored through TEM analysis. Evidently, the products deliver a hollow core-shell structure, exhibiting plentiful hetero-interfaces and further confirming the successful construction of MoS\u003csub\u003e2\u003c/sub\u003e nanoflakes shell (Fig. 2e). From a high magnification image in Fig. 2f, the MoS\u003csub\u003e2\u003c/sub\u003e nanoflakes anchoring evenly on Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u0026nbsp;\u003c/sub\u003emicrospheres are observed, coinciding with the SEM results. And the thickness of MoS\u003csub\u003e2\u003c/sub\u003e nanoflakes shells is about 20 nm (Fig. 2f). Diverse MoS\u003csub\u003e2\u003c/sub\u003e layers thickness, including 10 and 50 nm, are also obtained (Fig. S2). By observing a HRTEM image, a lattice spacing of 0.94 nm is discerned, which conforms to the (001) plane of 1T\u0026minus;MoS\u003csub\u003e2\u003c/sub\u003e [46]. This observation aligns with the XRD patterns, indicating a crystalline nature of MoS\u003csub\u003e2\u003c/sub\u003e layers. Moreover, the image also reveals a lattice spacing of 0.62 nm, associated with the (002) plane of 2H\u0026minus;MoS\u003csub\u003e2\u003c/sub\u003e, suggesting the as-prepared MoS\u003csub\u003e2\u003c/sub\u003e shells is 1T phase and 2H phase coexistence. Nevertheless, no peak profile for 2H\u0026minus;MoS\u003csub\u003e2\u003c/sub\u003e appears in the XRD patterns, which possibly due to its low intensity. Given that the distinct physical properties of 1T\u0026minus; and 2H\u0026minus;MoS\u003csub\u003e2\u003c/sub\u003e, their coexistence can introduce ample hetero-interfaces, thus boosting the electromagnetic wave dissipation by interface polarization loss [47]. In the HAADF image and relevant elemental maps of Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e@MoS\u003csub\u003e2\u003c/sub\u003e\u0026minus;2 (Fig. 2h), the distribution of Mo and S elements reflect the positioning of MoS\u003csub\u003e2\u003c/sub\u003e shell, which are absolutely restricted to the exterior of a hollow microsphere made up of uniformly distributed Fe and O elements, demonstrating a hollow core-shell characteristic of Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e@MoS\u003csub\u003e2\u003c/sub\u003e. Overall, these series of microstructure information manifest that the desired Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e@MoS\u003csub\u003e2\u003c/sub\u003e with 1T\u0026minus; and 2H\u0026minus;MoS\u003csub\u003e2\u003c/sub\u003e coexistence is successfully constructed. This hollow and core-shell heterogenous structure show the huge advantage of improving the interface polarization and extending the electromagnetic wave dissipation paths of the composite, which is in favor of boosting EMA performances.\u003c/p\u003e\n\u003cp\u003eThe XPS spectra are illustrated to further clarify the elemental compositions and chemical states of Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e@MoS\u003csub\u003e2\u003c/sub\u003e (Fig. 3). The survey spectra reveal that the presence of Fe, O in Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e and Fe, O, Mo, S elements coexist in Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e@MoS\u003csub\u003e2\u003c/sub\u003e (Fig. 3a). This finding is in accord with the elemental mapping images, further indicating the successful anchoring of MoS\u003csub\u003e2\u003c/sub\u003e nanoflakes on hollow Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e microspheres. To explore the phase structure of MoS\u003csub\u003e2\u003c/sub\u003e nanoflakes, the high-resolution XPS spectrum is also conducted. In the high-resolution of Mo 3d spectra (Fig. 3c), four characteristic peaks could be identified. The peaks that appeared at 232.1 eV and 228.5 eV represent the signals of Mo\u003csup\u003e4+\u003c/sup\u003e 3d\u003csub\u003e3/2\u003c/sub\u003e and 3d\u003csub\u003e5/2\u003c/sub\u003e within 1T phase MoS\u003csub\u003e2\u003c/sub\u003e. Conversely, the peaks that appeared at 232.4 and 228.8 eV are derived from 2H phase MoS\u003csub\u003e2\u003c/sub\u003e. Furthermore, the peak that appeared at 235.4 eV is corresponded to Mo\u003csup\u003e6+\u003c/sup\u003e, which is probably because of the partially oxidized of MoS\u003csub\u003e2\u003c/sub\u003e. While the peak that appeared at 225.9 eV is related to the S\u003csup\u003e2\u0026minus;\u003c/sup\u003e state of MoS\u003csub\u003e2\u003c/sub\u003e.\u0026nbsp;The high-resolution S 2p spectra present three distinctive binding energies (Fig. 3d). The binding energies of 162.6 eV and 161.5 eV are associated with S 2p\u003csub\u003e1/2\u003c/sub\u003e and S 2p\u003csub\u003e3/2\u003c/sub\u003e orbitals of 1T\u0026minus;MoS\u003csub\u003e2\u003c/sub\u003e. Similarly, the binding energies of 162.3 eV and 161.2 eV are belonging to S 2p\u003csub\u003e1/2\u003c/sub\u003e and S 2p\u003csub\u003e3/2\u003c/sub\u003e orbitals of 2H-MoS\u003csub\u003e2\u003c/sub\u003e, whereas the binding energy of 168.2 eV is associated with sulfur oxides.\u0026nbsp;The Mo/S ratio calculated from the XPS analyses is 1.99, which implies the existence of S vacancies. These vacancies can induce dipole formation, thereby enhancing dipole polarization loss and ultimately improving the EMA. The status of MoS\u003csub\u003e2\u003c/sub\u003e components in Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e@MoS\u003csub\u003e2\u003c/sub\u003e is further detected via Raman spectroscopy. The weak E\u003csub\u003e2g\u003c/sub\u003e and A\u003csub\u003e1g\u003c/sub\u003e signals located at 369.5 cm\u003csup\u003e\u0026minus;1\u003c/sup\u003e and 403.5 cm\u003csup\u003e\u0026minus;1\u003c/sup\u003e is observed in Fig. 3e, which is contributed to the first-order Raman vibration modes of sulfur, agreeing well with the 2H\u0026minus;MoS\u003csub\u003e2\u003c/sub\u003e [48]. Combined with XRD patterns, TEM images, XPS spectra and Raman spectra, we could conclude the hollow core-shell Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e@MoS\u003csub\u003e2\u003c/sub\u003e composites are successfully fabricated, and the MoS\u003csub\u003e2\u003c/sub\u003e shells are a mixture heterostructure of 1T\u0026minus;2H MoS\u003csub\u003e2\u003c/sub\u003e with abundant defects. Thanks to the plentiful Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e-MoS\u003csub\u003e2\u003c/sub\u003e core-shell interface and 1T\u0026minus;2H MoS\u003csub\u003e2\u003c/sub\u003e two-phase interface, as well as the numerous S vacancies defect, the additional interface polarization and dipole polarization can be produced, which is contributed to attenuate incidence electromagnetic wave through polarization loss. The hysteresis loop of Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e and Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e@MoS\u003csub\u003e2\u003c/sub\u003e is characterized by vibration sample magnetometer (Fig. 3f-h). The saturation magnetization (\u003cem\u003eM\u003csub\u003es\u003c/sub\u003e\u003c/em\u003e) of\u0026nbsp;Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e is 80.1, 82.8, 81.4 and 78.5 emu/g with coercivity (\u003cem\u003eH\u003c/em\u003e\u003csub\u003ec\u003c/sub\u003e) of 37.2, 26.1, 46.2 and 50.5 Oe (Fig. 3f, h). The anchoring of non-magnetic\u0026nbsp;MoS\u003csub\u003e2\u003c/sub\u003e nanoflakes with large shape anisotropy not only leads to the \u003cem\u003eM\u003csub\u003es\u003c/sub\u003e\u003c/em\u003e of composites gradually reduce, but also makes a gradually increased\u003cem\u003e\u0026nbsp;H\u003c/em\u003e\u003csub\u003ec\u003c/sub\u003e. As depicted in Fig. 3(g, h), a \u003cem\u003eM\u003csub\u003es\u003c/sub\u003e\u003c/em\u003e and \u003cem\u003eH\u003c/em\u003e\u003csub\u003ec\u003c/sub\u003e of Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e@MoS\u003csub\u003e2\u003c/sub\u003e\u0026minus;1, Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e@MoS\u003csub\u003e2\u003c/sub\u003e\u0026minus;2\u0026nbsp;and\u0026nbsp;Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e@MoS\u003csub\u003e2\u003c/sub\u003e\u0026minus;3 is\u0026nbsp;76.6 emu/g and 51.4 Oe, 67.5 emu/g and 55.4 Oe, as well as 54.3 emu/g and 58.4 Oe. Such magnetic properties could produce magnetic loss in\u0026nbsp;Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e@MoS\u003csub\u003e2\u003c/sub\u003e. Such high coercivity indicates the large magnetic anisotropy, which is in favor of magnetic resonances in high-frequency [49].\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e2.2 Electromagnetic Wave Absorption Mechanism of Hollow\u0026nbsp;\u003c/strong\u003e\u003cstrong\u003eFe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e\u003c/strong\u003e\u003cstrong\u003e\u0026nbsp;Microspheres\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eTo explore the correlation of hollow Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e structures and EMA performances, the electromagnetic parameters that determining the EMA and reflection are conducted (Fig. 4a and b). The \u0026epsilon;\u0026prime; and \u0026epsilon;\u0026Prime; of Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e\u0026minus;1, Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e\u0026minus;2, Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e\u0026minus;3 and Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e\u0026minus;4\u0026nbsp;are illustrated in Fig. 4a. Among the four specimens,\u0026nbsp;Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e\u0026minus;1\u0026nbsp;with a solid structure shows the lowest \u0026epsilon;\u0026prime; and \u0026epsilon;\u0026Prime;, whose ɛ\u0026prime; gradually decreases from 6.25 to 3.81 at 2.0\u0026minus;18.0 GHz, and \u0026epsilon;\u0026Prime; elevates from 0.25 (2.0 GHz) to 1.44 (18.0 GHz). From solid\u0026nbsp;Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e into hollow Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e, the permittivity improves and continuously increases with the expanded interior space. Specifically, the\u0026nbsp;Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e\u0026minus;2, Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e\u0026minus;3 and Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e\u0026minus;4\u0026nbsp;harvest the \u0026epsilon;\u0026prime; of ~6.3, ~7.6 and ~8.3. And the \u0026epsilon;\u0026Prime; increases from 0.27 to 2.79, 0.37 to 4.07,\u0026nbsp;and 0.35 to 6.22 for\u0026nbsp;Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e\u0026minus;2, Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e\u0026minus;3 and Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e\u0026minus;4. These results demonstrate that the hollow structure indeed favors a higher permittivity, indicating its increasing dielectric property. Additionally, the ɛ\u0026prime; and \u0026epsilon;\u0026Prime; of all\u0026nbsp;Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e samples displays evident resonance peak from X to Ku bands, indicating multiple polarization relaxation process in these bands [50, 51]. The permeability (\u0026mu;\u0026prime;, \u0026mu;\u0026Prime;) of Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e samples within 2.0\u0026minus;18.0 GHz is exhibited in Fig. 4b. It can be found Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e\u0026minus;1 displays a linearly reduced \u0026mu;\u0026prime; from 1.6 to 0.8 (2.0\u0026minus;7.0 GHz) with a small resonant peak at 4.0\u0026minus;5.0 GHz,\u0026nbsp;and then slowly raises to 1.12 (7.0\u0026minus;18 GHz) with a broad resonant peak at 13.5 GHz. The \u0026mu;\u0026Prime;\u0026nbsp;shows a maximum value of 0.62 at 3.1 GHz, subsequently declining to zero at 10.8 GHz, followed by another peak between 13.0\u0026minus;15.0 GHz, and then turning negative for the remaining frequency range. The negative \u0026mu;\u0026Prime; implies that some of electric field energies are converted into magnetic energies [52].\u0026nbsp;Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e\u0026minus;2, Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e\u0026minus;3 and Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e\u0026minus;4\u0026nbsp;exhibit similar trend and fluctuating behaviors in \u0026micro;\u0026prime; and \u0026micro;\u0026Prime; as that of\u0026nbsp;Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e\u0026minus;1, but the resonant peaks at 4.0\u0026minus;5.0 GHz and 15.0\u0026minus;17.0 GHz in \u0026micro;\u0026prime; as well as the resonant peak at 2.9 GHz in \u0026micro;\u0026Prime; significantly become stronger. In addition, the resonant peak at 13.5 GHz in \u0026micro;\u0026Prime; shifts to a higher frequency of 16.0\u0026minus;17.0 GHz.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eAccording to the\u0026nbsp;electromagnetic parameters, an EMA performance of Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e samples is studied using the transmission line theory. \u003cem\u003eRL\u003c/em\u003e and EAB (the frequency range of \u003cem\u003eRL\u003c/em\u003e \u0026le; \u0026minus;10 dB) are two key criteria to evaluate the EMA performance. Thus, the dependent \u003cem\u003eRL\u003c/em\u003e and EAB of Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e\u0026minus;1, Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e\u0026minus;2, Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e\u0026minus;3 and Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e\u0026minus;4 on matching thicknesses and frequency are shown in Fig. 4c-i to visually explore the effect of hollow structure on EMA capabilities. From the 2D maps, it is clearly all four specimens show brilliant EMA performance, especially in low frequency range, which can meet \u0026lt;\u0026minus;20.0\u0026nbsp;dB from 4.0 to 10.0\u0026nbsp;GHz (Fig. c\u003csub\u003e1\u003c/sub\u003e-f\u003csub\u003e1\u003c/sub\u003e). For solid Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e\u0026minus;1, the minimum \u003cem\u003eRL\u003c/em\u003e (\u0026minus;46.89 dB) occurs at C band (6.92 GHz) with a 4.34 mm thickness, and the corresponding EAB is 2.3 GHz (5.0\u0026minus;7.3 GHz) (Fig. 4c and\u003csub\u003e\u0026nbsp;\u003c/sub\u003eh). For hollow Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e\u0026minus;2 and Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e\u0026minus;3, the minimum \u003cem\u003eRL\u003c/em\u003e (\u0026minus;70.21 dB, \u0026minus;69.43 dB) remains at C band (5.70 GHz, 6.22 GHz) with an extended EAB of 3.4 GHz (4.2\u0026minus;7.6 GHz) and 3.9 GHz (4.4\u0026minus;8.3GHz GHz) at 4.63 mm and 4.01 mm matching thickness (Fig. 4d e and\u003csub\u003e\u0026nbsp;\u003c/sub\u003eh). As for Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e\u0026minus;4, the strongest \u003cem\u003eRL\u003c/em\u003e can reach up to \u0026minus;81.96 dB under 3.24 mm and shifts to X band (8.01 GHz) (Fig. 4f and\u003csub\u003e\u0026nbsp;\u003c/sub\u003eh). These results demonstrate that the hollow structure Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e possess strong absorption characteristic. In terms of EAB, the Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e\u0026minus;1 exhibits relatively strong but narrow absorption characteristic within 5.0\u0026minus;9.9 GHz with a \u003cem\u003eRL\u003c/em\u003e \u0026lt; \u0026minus;20 dB and an EAB \u0026le; 4.0 GHz at a single thickness (3.5\u0026minus;5.0 mm), covering the C\u0026minus;X bands. However, the EMA capability of Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e\u0026minus;1 in Ku band is unsatisfied. The \u003cem\u003eRL\u003c/em\u003e fails to reach \u0026minus;10 dB within 15.0\u0026minus;18.0 GHz, and the EAB is 0. After forming a hollow structure, the absorption intensities significantly enhance and the EMA in Ku band obvious heightens. Specifically, Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e\u0026minus;3 shows an effective absorption (\u0026lt; \u0026minus;10.0 dB) of 1.5 GHz under a thin matching thickness of 2.0 mm. More importantly, all \u003cem\u003eRL\u003c/em\u003e of Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e\u0026minus;3 is below \u0026minus;10 dB from 2\u0026nbsp;to\u0026nbsp;5 mm, covering from 3.2 to 18.0 GHz, suggesting its best overall EMA performance. These results validate that the fabrication of hollow engineering could\u0026nbsp;adjust electromagnetic properties to ameliorate\u0026nbsp;the EMA performances of Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eUpon understanding the EMA performances of\u0026nbsp;Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e samples, the correlation of enhanced EMA capacities with magnetic and dielectric loss is first elucidated. Compared to Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e\u0026minus;1, the dielectric loss tangent (tan\u0026nbsp;\u0026delta;\u0026epsilon;) of\u0026nbsp;Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e\u0026minus;2, Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e\u0026minus;3 and Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e\u0026minus;4\u0026nbsp;slightly decreases in the whole frequency range (Fig. S3), indicating a slightly declined dielectric loss\u0026nbsp;capability\u0026nbsp;of the hollow structure. Generally, conduction loss and polarization loss are mainly dielectric loss mechanism for EMA [53, 54]. According to the Debye theory, these dielectric loss mechanisms could be visually depicted through Cole\u0026minus;Cole plots, in which a semicircle stands for a polarization process, while a \u0026lsquo;tail\u0026rsquo; represents conductivity loss [55]. As depicted in Fig. S4, several distorted and irregular semicircles appear on the curves, indicating multiple relaxation processes [56], which aligns with the \u0026epsilon;\u0026prime; and \u0026epsilon;\u0026Prime; curves. These results\u0026nbsp;firmly demonstrate that\u0026nbsp;the dielectric loss\u0026nbsp;capability\u0026nbsp;of\u0026nbsp;Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e microspheres slightly weakens by implementing hollow engineering, and the polarization loss is predominant mechanism for dielectric loss. Besides dielectric loss, the magnetic loss is another key consumption mechanism for electromagnetic wave absorbing. The magnetic loss tangent (tan \u0026delta;\u0026mu;) reveals that all three hollow spheres present a prominent improvement in tan \u0026delta;\u0026mu; within 2.0\u0026minus;12 GHz (Fig. S5), confirming the enhanced magnetic loss ability of the hollow engineering. Typically, the magnetic loss in gigahertz range is primarily attributed to natural resonance, exchange resonance and eddy currents, which could be analyzed by C\u003csub\u003e0\u0026nbsp;\u003c/sub\u003e= \u0026mu;\u0026Prime; (\u0026mu;\u0026prime;)\u003csup\u003e\u0026minus;2\u003c/sup\u003e\u003cem\u003ef\u003c/em\u003e \u003csup\u003e\u0026minus;1\u003c/sup\u003e curves [57]. It can be seen the \u0026mu;\u0026Prime; (\u0026mu;\u0026prime;)\u003csup\u003e\u0026minus;2\u003c/sup\u003e\u003cem\u003ef\u003c/em\u003e\u003csup\u003e\u0026minus;1\u003c/sup\u003e fluctuates up and down across the whole frequency range (Fig. S6), revealing the magnetic resonances are the primary contributors to magnetic loss. A further comparison of tan \u0026delta;\u0026epsilon; and tan \u0026delta;\u0026mu; reveals that in low-frequency, magnetic loss is the predominant mechanism for electromagnetic loss, whereas in high-frequency, the dielectric loss dominates the electromagnetic loss mechanism. Apart from magnetic and dielectric loss, the attenuation ability (𝛼) and impedance matching are essential for evaluating the EMA performances. The analysis of 𝛼 shows that the solid and hollow Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e microsphere presents the comparable EMA capability (Fig. S7). This may be attributed to a decreased dielectric loss offsets an enhanced magnetic loss. Thus, the outstanding EMA performances of hollow Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e should be attributed to the improved impedance matching, which is analyzed through impedance matching (Z = |Z\u003csub\u003ein\u003c/sub\u003e/Z\u003csub\u003e0\u003c/sub\u003e|). Theoretically, Z should be in the range of 0.52\u0026ndash;1.92 to guarantee the \u003cem\u003eRL\u003c/em\u003e lower than \u0026minus;10 dB [58]. The value is closer to 1, matched impedance is achieved. As exhibited in Fig. S8a, Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e\u0026minus;1\u0026nbsp;possess a good impedance matching from C to X band under 3.5\u0026minus;5.0 mm, but in Ku band its impedance matching is poor, resulting in an ungratified EMA in this band. Obviously, the hollow structure not only maintains the good impedance matching in S\u0026minus;X band, but also significantly improves the impedance matching in Ku band (Fig. S8 b-d). Based on the above analysis, the hollow structure improves the impedance match compared with solid counterpart, thereby enhancing the EMA performance.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e2.3 Electromagnetic Wave Absorption Mechanism of Hollow Core-Shell\u0026nbsp;\u003c/strong\u003e\u003cstrong\u003eFe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e@MoS\u003csub\u003e2\u003c/sub\u003e\u003c/strong\u003e\u003cstrong\u003e\u0026nbsp;Microspheres\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe correlation of hollow core\u0026ndash;shell structure based on Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e@MoS\u003csub\u003e2\u003c/sub\u003e composites and EMA performances is further explored. Firstly, the permittivity (\u0026epsilon;\u0026prime;, \u0026epsilon;\u0026Prime;) is analyzed to elucidate the dielectric loss of Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e@MoS\u003csub\u003e2\u003c/sub\u003e heterostructures. Compared with Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e\u0026minus;3,\u0026nbsp;the permittivity of\u0026nbsp;Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e@MoS\u003csub\u003e2\u003c/sub\u003e significantly changes. Specifically, the \u0026epsilon;\u0026prime; and \u0026epsilon;\u0026Prime; of Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e@MoS\u003csub\u003e2\u0026nbsp;\u003c/sub\u003eshows typical frequency dispersion phenomenon, where the \u0026epsilon;\u0026prime; of\u0026nbsp;Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e@MoS\u003csub\u003e2\u003c/sub\u003e\u0026minus;1\u0026nbsp;fluctuation decreases in the 7.02\u0026minus;5.13 range, and the\u0026nbsp;\u0026epsilon;\u0026Prime; fluctuates up and down between\u0026nbsp;2.74 and 1.58\u0026nbsp;(Fig. 5a, b). By comparison, it is clearly that\u0026nbsp;the \u0026epsilon;\u0026prime;\u0026nbsp;of\u0026nbsp;Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e@MoS\u003csub\u003e2\u003c/sub\u003e\u0026minus;1 remarkable decrease in 2.0\u0026minus;18.0 GHz, and the\u0026nbsp;\u0026epsilon;\u0026Prime; significantly increases from 2.0 to 10.0 GHz.\u0026nbsp;When the MoS\u003csub\u003e2\u003c/sub\u003e nanoflakes forms continuous layer in Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e@MoS\u003csub\u003e2\u003c/sub\u003e\u0026minus;2 and Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e@MoS\u003csub\u003e2\u003c/sub\u003e\u0026minus;3,\u0026nbsp;the \u0026epsilon;\u0026prime; ranges from 5.94 to 3.36 (Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e@MoS\u003csub\u003e2\u003c/sub\u003e\u0026minus;2) and 5.78 to 2.94 (Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e@MoS\u003csub\u003e2\u003c/sub\u003e\u0026minus;3), showing an obviously decrease with respect to\u0026nbsp;Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e@MoS\u003csub\u003e2\u003c/sub\u003e\u0026minus;1. Meanwhile, the\u0026nbsp;\u0026epsilon;\u0026Prime; varies in the 1.56\u0026minus;2.82 (Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e@MoS\u003csub\u003e2\u003c/sub\u003e\u0026minus;2) and 1.61\u0026minus;2.80\u0026nbsp;range\u0026nbsp;(Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e@MoS\u003csub\u003e2\u003c/sub\u003e\u0026minus;3), showing a slightly increase in comparation to\u0026nbsp;Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e@MoS\u003csub\u003e2\u003c/sub\u003e\u0026minus;1. The \u0026epsilon;\u0026prime; stands for the capability to store dielectric energies, thus a reduced \u0026epsilon;\u0026prime; suggests the energy storage capability of\u0026nbsp;Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e@MoS\u003csub\u003e2\u003c/sub\u003e is weaken. Whereas the \u0026epsilon;\u0026Prime; stands for the dielectric loss capability, an increased \u0026epsilon;\u0026Prime; suggests its dielectric dissipation is enhanced. Besides, the \u0026epsilon;\u0026Prime; is intrinsically linked to electrical conductivity based on the free-electron theory [59]. An increased \u0026epsilon;\u0026Prime; also implies an ameliorated electrical conductivity in Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e@MoS\u003csub\u003e2\u003c/sub\u003e, which can produce conduction loss. The tan \u0026delta;\u0026epsilon; in Fig. 5c shows a similar change to \u0026epsilon;\u0026Prime;, confirming significantly increased dielectric loss of Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e@MoS\u003csub\u003e2\u003c/sub\u003e. Furthermore, Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e@MoS\u003csub\u003e2\u003c/sub\u003e\u0026minus;2 and Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e@MoS\u003csub\u003e2\u003c/sub\u003e\u0026minus;3 with continuous layer MoS\u003csub\u003e2\u003c/sub\u003e possess a higher tan \u0026delta;\u0026epsilon;, implying a stronger dielectric loss capability. Cole\u0026minus;Cole semicircle is plotting to clarify the dielectric loss mechanism of Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e@MoS\u003csub\u003e2\u003c/sub\u003e.\u0026nbsp;Clearly, a plot of\u0026nbsp;Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e@MoS\u003csub\u003e2\u003c/sub\u003e shows 1 or 2 more semicircle than Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e (Fig. S9), revealing the increased polarization relaxation processes. This is because the introducing of MoS\u003csub\u003e2\u003c/sub\u003e produces the Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e\u0026minus;MoS\u003csub\u003e2\u003c/sub\u003e heterointerfaces, promoting interface polarization. Density functional theory (DFT) calculation is conducted to elucidate the polarization effect at heterointerfaces. As illustrated in Fig. 5g, the introduction of MoS\u003csub\u003e2\u003c/sub\u003e induces accumulation and separation of electrons at the coherent interfaces, manifesting the generation of interface polarization. The DOS reveals that the localized carrier concentration near the Fermi level at Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e@MoS\u003csub\u003e2\u003c/sub\u003e interfaces exceeds that of individual Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e and MoS\u003csub\u003e2\u003c/sub\u003e, demonstrating a spontaneous electron transfer at the coherent interfaces (Fig. 5h). Additionally, a short tail\u0026nbsp;is\u0026nbsp;found at the end of the\u0026nbsp;Cole\u0026minus;Cole\u0026nbsp;curves, demonstrating conduction loss occurs in\u0026nbsp;Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e@MoS\u003csub\u003e2\u003c/sub\u003e.\u0026nbsp;Consequently, the integration of MoS\u003csub\u003e2\u003c/sub\u003e to construct hollow core\u0026minus;shell structure, not only adjusts the permittivity by improving the polarization relaxation and enhancing the electronic conductivity, but also induces the conduction loss to enhance the EMA capabilities. More importantly, these dielectric loss characteristics are effectively regulated by tailoring the MoS\u003csub\u003e2\u003c/sub\u003e contents. Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e@MoS\u003csub\u003e2\u003c/sub\u003e\u0026minus;2 with continuous\u0026nbsp;MoS\u003csub\u003e2\u003c/sub\u003e layer and moderate MoS\u003csub\u003e2\u003c/sub\u003e contents possess the optimal dielectric loss.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eTo clarify the magnetic loss of Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e@MoS\u003csub\u003e2\u003c/sub\u003e, the\u0026nbsp;permeability (\u0026mu;\u0026prime;, \u0026mu;\u0026Prime;) is illustrated in Fig. 5d, e.\u0026nbsp;Compared with Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e,\u0026nbsp;the \u0026micro;\u0026prime; has no significant change after the\u0026nbsp;MoS\u003csub\u003e2\u003c/sub\u003e nanoflakes decoration for Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e@MoS\u003csub\u003e2\u003c/sub\u003e\u0026minus;1 and Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e@MoS\u003csub\u003e2\u003c/sub\u003e\u0026minus;2, demonstrating the influence\u0026nbsp;of suitable MoS\u003csub\u003e2\u003c/sub\u003e contents on permeability is slight. However, the \u0026micro;\u0026prime; of Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e@MoS\u003csub\u003e2\u003c/sub\u003e\u0026minus;3\u0026nbsp;clearly decreases across 3.0\u0026minus;18.0 GHz due to a large amount of\u0026nbsp;MoS\u003csub\u003e2\u003c/sub\u003e contents making a significant decrease in \u003cem\u003eM\u003csub\u003es\u003c/sub\u003e\u003c/em\u003e. Although there is no evident variation in \u0026micro;\u0026prime;, the \u0026micro;\u0026Prime; is ameliorated to a certain extent for\u0026nbsp;Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e@MoS\u003csub\u003e2\u003c/sub\u003e\u0026minus;1 and Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e@MoS\u003csub\u003e2\u003c/sub\u003e\u0026minus;2. Specifically,\u0026nbsp;the downtrend of \u0026micro;\u0026Prime; with the increasing frequency is significantly slacken, which is attributed to the shift of resonance frequency towards high frequency. This phenomenon has also been observed in\u0026nbsp;Fe/FeO\u003cem\u003e\u003csub\u003ex\u003c/sub\u003e\u003c/em\u003e@C composites, which helps to promote magnetic loss at high frequency [60].\u0026nbsp;Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e@MoS\u003csub\u003e2\u003c/sub\u003e\u0026minus;2 has the slowest downtrend indicates the strongest magnetic loss at high frequency\u0026nbsp;(Fig. 5f).\u0026nbsp;Furthermore,\u0026nbsp;the\u0026nbsp;Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e@MoS\u003csub\u003e2\u003c/sub\u003e samples exhibit similar resonance peaks in \u0026micro;\u0026Prime; and tan \u0026delta;\u0026mu; curves, which is related to the magnetic resonance. This magnetic loss mechanism is demonstrated by C\u003csub\u003e0\u003c/sub\u003e curves, which is fluctuate decreased with the increasing frequency (Fig. S10), suggesting the eddy current is suppressed. These results declare that introducing an appropriate amount of MoS\u003csub\u003e2\u003c/sub\u003e can really ameliorate the \u0026micro;\u0026Prime; and magnetic loss at high frequency.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eA consolidated dielectric loss from\u0026nbsp;MoS\u003csub\u003e2\u003c/sub\u003e shells, combined with an inherited magnetic loss from hollow Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e causes efficient improvement in EMA. As shown in Fig. 5i-l, Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e@MoS\u003csub\u003e2\u003c/sub\u003e performs excellent EMA in the whole frequency range and its absorption capacity varies with the MoS\u003csub\u003e2\u003c/sub\u003e contents. For Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e@MoS\u003csub\u003e2\u003c/sub\u003e\u0026minus;1, it shows effective absorption across 5.2\u0026minus;18 GHz with a thickness of 2.0\u0026minus;5.0 mm (Fig. 5i). However, the \u003cem\u003eRL\u003c/em\u003e is mainly concentrated between \u0026minus;10 and \u0026minus;20 dB, and the EAB is narrow under 3.0\u0026minus;5.0 mm. At 2.2 mm, the strongest \u003cem\u003eRL\u003c/em\u003e of \u0026minus;61.72 dB is obtained at Ku band (16.01 GHz), and the corresponding EAB is 4.9 GHz ranging from 13.1 to 18.0 GHz. Notably, the broadest EAB of Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e@MoS\u003csub\u003e2\u003c/sub\u003e\u0026minus;1 can reach up to 6.5 GHz (11.5\u0026minus;18.0 GHz) with 2.5 mm, which is covering the whole Ku band. Evidently, Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e@MoS\u003csub\u003e2\u003c/sub\u003e\u0026minus;1 exhibits broadband absorption characteristics in Ku band with thin thickness. Upon increasing the MoS\u003csub\u003e2\u003c/sub\u003e contents, the minimum \u003cem\u003eRL\u003c/em\u003e of Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e@MoS\u003csub\u003e2\u003c/sub\u003e\u0026minus;2 enhances, and the EAB broadens. For example, Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e@MoS\u003csub\u003e2\u003c/sub\u003e\u0026minus;2 presents a minimum \u003cem\u003eRL\u003c/em\u003e of \u0026minus;69.01 dB (16.28 GHz) and EAB spanning from 11.3 to 18.0 GHz under 2.66 mm (Fig. 5j). Increasing the thickness to 3.5 mm, it still demonstrates a significant \u003cem\u003eRL\u003c/em\u003e of \u0026minus;61.68 dB along with a broad EAB of 8.3 GHz. Particularly, under 3.0 mm, a widest EAB of 8.4 GHz, spanning from 9.6 GHz to 18.0 GHz and encompassing the entire Ku band, can be obtained for Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e@MoS\u003csub\u003e2\u003c/sub\u003e\u0026minus;2.\u0026nbsp;Further increasing the MoS\u003csub\u003e2\u003c/sub\u003e contents, there is no additional improvement in EAB performance. As shown in Fig. 5k, under a distinct increase thickness of 3.83 mm, a slight weakened minimum \u003cem\u003eRL\u003c/em\u003e of \u0026minus;63.39 dB is achieved at X band (10.78 GHz). The corresponding EAB spans 7.2 GHz (7.4\u0026minus;14.6 GHz). Even though the EMA performance of Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e@MoS\u003csub\u003e2\u003c/sub\u003e\u0026minus;3\u0026nbsp;is decreased in comparison to\u0026nbsp;Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e@MoS\u003csub\u003e2\u003c/sub\u003e\u0026minus;2,\u0026nbsp;it still possesses a wide EAB of 5.8 GHz (12.2\u0026minus;18 GHz) under 3.0 mm and 7.5 GHz (9.0\u0026minus;16.5 GHz) at 3.5 mm. These results\u0026nbsp;demonstrate a firm correlation of\u0026nbsp;MoS\u003csub\u003e2\u003c/sub\u003e shells modulation engineering and EMA performances.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eFig. 5l and Fig. S11 further compares the \u003cem\u003eRL\u003c/em\u003e, EAB and matching thickness of\u0026nbsp;Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e\u0026minus;3 and Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e@MoS\u003csub\u003e2\u003c/sub\u003e. It can be seen both\u0026nbsp;Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e and Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e@MoS\u003csub\u003e2\u003c/sub\u003e possess exceptional minimum \u003cem\u003eRL\u003c/em\u003e, but\u0026nbsp;Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e@MoS\u003csub\u003e2\u003c/sub\u003e exhibits a significant thickness (4.01 mm for Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e\u0026minus;3,\u0026nbsp;2.2 mm for\u0026nbsp;Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e@MoS\u003csub\u003e2\u003c/sub\u003e\u0026minus;1,\u0026nbsp;2.66 mm for\u0026nbsp;Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e@MoS\u003csub\u003e2\u003c/sub\u003e\u0026minus;2 and\u0026nbsp;3.83 mm for\u0026nbsp;Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e@MoS\u003csub\u003e2\u003c/sub\u003e\u0026minus;3)\u0026nbsp;and broadband advantages (4.2 GHz for\u0026nbsp;Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e\u0026minus;3,\u0026nbsp;6.5 GHz for\u0026nbsp;Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e@MoS\u003csub\u003e2\u003c/sub\u003e\u0026minus;1, 8.4 GHz for\u0026nbsp;Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e@MoS\u003csub\u003e2\u003c/sub\u003e\u0026minus;2, 7.5 GHz for\u0026nbsp;Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e@MoS\u003csub\u003e2\u003c/sub\u003e\u0026minus;3). Particularly, the widest EAB greatly improves for\u0026nbsp;Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e@MoS\u003csub\u003e2\u003c/sub\u003e. Take Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e@MoS\u003csub\u003e2\u003c/sub\u003e\u0026minus;2 as an example, the\u0026nbsp;widest EAB extends from 4.2 to 8.4 GHz, improving 100% compared to\u0026nbsp;Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e\u0026minus;3 with a decreased thickness. Consequently, the comparison with \u003cem\u003eRL\u003c/em\u003e, EAB and matching thickness results reveal that the hollow core-shell structure shows distinct advantage in \u003cem\u003eRL\u0026nbsp;\u003c/em\u003eintensity, EAB bandwidth and thin matching thickness, surely demonstrating an importance of hollow core-shell engineering.\u003c/p\u003e\n\u003cp\u003eThe possible EMA mechanisms are illustrated in Fig. 6. First,\u0026nbsp;the anchor of\u0026nbsp;MoS\u003csub\u003e2\u003c/sub\u003e on Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e not only considerably improves the conductivity of Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e@MoS\u003csub\u003e2\u003c/sub\u003e, triggering conductivity loss, but also\u0026nbsp;induces plentiful heterointerfaces, increasing the interface polarization loss. Then, the total dielectric loss capability of\u0026nbsp;Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e@MoS\u003csub\u003e2\u003c/sub\u003e is remarkably strengthened. Second, the Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e can provide sufficient magnetic loss, including natural resonance and exchange resonance, to consume electromagnetic wave. Third, the integrated MoS\u003csub\u003e2\u003c/sub\u003e greatly decreases the permittivity of Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e, and fine-tunes the permeability. Such regulation facilitates an effective complementarity to the\u0026nbsp;electromagnetic parameters, and then amplifies the impedance matching, thereby increasing the electromagnetic wave absorbing.\u0026nbsp;Four, a hollow core and hierarchical shell could extend the reflection and scattering areas of electromagnetic wave, leading to multiple reflection/scattering, thus improving the electromagnetic wave dissipation. Notably, the four advantages are also applied to\u0026nbsp;Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e@MoS\u003csub\u003e2\u003c/sub\u003e\u0026minus;1 and Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e@MoS\u003csub\u003e2\u003c/sub\u003e\u0026minus;3, while\u0026nbsp;Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e@MoS\u003csub\u003e2\u003c/sub\u003e\u0026minus;2 has appropriate component, which could produce better impedance matching and the strongest attenuation capability, thereby bringing the greatest EMA performances. Consequently, the design and construction of hollow core-shell microstructure with component manipulation could enhance the impedance matching and attenuation capability simultaneously, making for an outstanding broadband absorbing.\u0026nbsp;\u003c/p\u003e"},{"header":"Conclusion","content":"\u003cp\u003eIn conclusion, hollow core-shell\u0026nbsp;Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e@MoS\u003csub\u003e2\u003c/sub\u003e composites with tunable component are successfully prepared via the solvothermal process. The reaction time occupies a significant position in regulation internal space of hollow microspheres. The growth of MoS\u003csub\u003e2\u003c/sub\u003e creates the hollow core-shell microstructure and provides an effect of composition engineering. The obtained results indicate the integration of structural and compositional regulation not only tune the dielectric properties, but also enhance the magnetic loss in high frequency, thereby significantly broadening the EAB and achieving an optimized EMA characteristic. Especially for the composites with the continuous MoS\u003csub\u003e2\u003c/sub\u003e layers of 20 nm, the strongest \u003cem\u003eRL\u003c/em\u003e of \u0026minus; 69.01 dB can be obtained at a thin thickness of 2.66 mm, while the broadest EAB could reach up to 8.4 GHz under 3.0 mm. The mechanisms exploration clarifies that interface polarization, dipole polarization, conductivity loss, ferromagnetic resonance, along with multiple reflections and scattering, work in concert for the enhanced attenuation capability. This work offers a strategy to construct magnetic-dielectric absorbers with tunable composition and optional structure for broadband electromagnetic wave absorbing.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eSupplementary Information\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe Experimental results of hollow Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e microspheres\u0026nbsp;and hollow core-shell\u0026nbsp;Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e@MoS\u003csub\u003e2\u003c/sub\u003e microspheres. SEM and TEM images of hollow core-shell\u0026nbsp;Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e@MoS\u003csub\u003e2\u003c/sub\u003e microspheres. The electromagnetic properties, attenuation coefficient and impedance matching of hollow Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e microspheres. The\u003cstrong\u003e\u0026nbsp;\u003c/strong\u003eCole\u0026minus;Cole curves, C\u003csub\u003e0\u003c/sub\u003e values and EMA performance of\u0026nbsp;hollow core-shell\u0026nbsp;Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e@MoS\u003csub\u003e2\u003c/sub\u003e microspheres.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis work was financially supported by the National Natural Science Foundation of China (52403356, 52373271), the Natural Science Foundation of Liaoning Province (Grant number 2024-MS-128, 2023-MS-235), the Basic Research Project Educational Department of Liaoning Province (JYTQN2023367) and Shenyang University of Chemical and Technology of \u0026quot;Outstanding youth\u0026quot; plan Funds (2022YQ002).\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eZhou X, Min P, Liu Y, Jin M, Yu Z-Z, Zhang H-B (2024) Insulating electromagnetic-shielding silicone compound enables direct potting electronics. Science 385:1205\u0026ndash;1210. https://doi.org/10.1126/science.adp6581\u003c/li\u003e\n\u003cli\u003eYuan M, Li B, Du Y, Liu J, Zhou X, Cui J, Lv H, Che R (2025) Programmable electromagnetic wave absorption via tailored metal single atom-support interactions. Adv Mater 37:2417580. https://doi.org/10.1002/adma.202417580 \u003c/li\u003e\n\u003cli\u003eZhou L, Hu P, Bai M, Leng N, Cai B, Peng H-L, Zhao P-Y, Guo Y, He M, Wang G-S, Gu J. (2025) Harnessing the Electronic Spin States of Single Atoms for Precise Electromagnetic Modulation. Adv Mater 37:2418321. https://doi.org/10.1002/adma.202418321\u003c/li\u003e\n\u003cli\u003eQu N, Yu Z, Zhang J, Han H, Xing R, Geng L, Kong J (2025) Temperature-robust broadband metamaterial absorber via semiconductor MOFs/paraffin hybridization. Small 21:2409874. https://doi.org/10.1002/smll.202409874\u003c/li\u003e\n\u003cli\u003eYang X, Wu Z, Pei K, Qian Y, Lv X, Liu M, Zhang R, Yang K, Ying M, Lai Y, Che R (2025) Confining magnetic response by the surface reorganization of buckling permalloy microspheres for boosting microwave absorption. ACS Nano 19:9144\u0026ndash;55. https://doi.org/10.1021/acsnano.4c18320\u003c/li\u003e\n\u003cli\u003eZhao R, Gao T, Li Y, Sun Z, Zhang Z, Ji L, Hu C, Liu X, Zhang Z, Zhang X, Qin G (2024) Highly anisotropic Fe\u003csub\u003e3\u003c/sub\u003eC microflakes constructed by solid-state phase transformation for efficient microwave absorption. Nat Commun 15:1497. https://doi.org/10.1038/s41467-024-45815-w\u003c/li\u003e\n\u003cli\u003eCai B, Zhou L, Zhao P-Y, Peng H-L, Hou Z-L, Hu P, Liu L-M, Wang G-S (2024) Interface-induced dual-pinning mechanism enhances low-frequency electromagnetic wave loss. Nat Commun 15:3299. https://doi.org/10.1038/s41467-024-47537-5\u003c/li\u003e\n\u003cli\u003eHuang W, Song M, Wang S, Wang B, Ma J, Liu T, Zhang Y, Kang Y, Che R (2024) Dual-step redox engineering of 2D CoNi-alloy embedded B, N-doped carbon layers toward tunable electromagnetic wave absorption and light-weight infrared stealth heat insulation devices. Adv Mater 36:2403322. https://doi.org/10.1002/adma.202403322\u003c/li\u003e\n\u003cli\u003eZhang Y, Lan D, Hou T, Jia M, Jia Z, Gu J, Wu G (2024) Multifunctional electromagnetic wave absorbing carbon fiber/Ti\u003csub\u003e3\u003c/sub\u003eC\u003csub\u003e2\u003c/sub\u003eTX MXene fabric with ultra-wide absorption band. Carbon 230:119594. https://doi.org/10.1016/j.carbon.2024.119594\u003c/li\u003e\n\u003cli\u003eQu N, Sun H, Sun Y, He M, Xing R, Gu J, Kong J (2024) 2D/2D coupled MOF/Fe composite metamaterials enable robust ultra-broadband microwave absorption. Nat Commun 15:5642. https://doi.org/10.1038/s41467-024-49762-4\u003c/li\u003e\n\u003cli\u003eLiang G, Bi J, Liang S, Che C, Liu L, Bie S, Yang Y (2025) Structural design and simulation of ultra-broadband TiC\u003cem\u003e\u003csub\u003ex\u003c/sub\u003e\u003c/em\u003eN\u003cem\u003e\u003csub\u003e1-x\u003c/sub\u003e\u003c/em\u003e fibers/Si\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e high-temperature microwave absorbing composites. Adv Compos Hybrid Mater 8:198. https://doi.org/10.1007/s42114-025-01280-7\u003c/li\u003e\n\u003cli\u003eHan Y, Guo H, Qiu H, Hu J, He M, Shi X, Zhang Y, Kong J, Gu J. (2025) Multimechanism decoupling for low-frequency microwave absorption hierarchical Fe-doped Co magnetic microchains. Adv Funct Mater 2506803. https://doi.org/10.1002/adfm.202506803\u003c/li\u003e\n\u003cli\u003eChen N, Pan X-F, Guan Z-J, Zhang Y-J, Wang K-J, Jiang J-T (2024) Flower-like hierarchical Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e-based heterostructured microspheres enabling superior electromagnetic wave absorption. Appl Surf Sci 642:158633. https://doi.org/10.1016/j.apsusc.2023.158633\u003c/li\u003e\n\u003cli\u003eLei D, Liu C, Wang S, Zhang P, Li Y, Yang D, Jin Y, Liu Z, Dong C (2025) Multiple synergistic effects of structural coupling and dielectric-magnetic loss in promoting microwave absorption of bark-derived absorbers. Adv Compos Hybrid Mater 8:158. https://doi.org/10.1007/s42114-025-01233-0\u003c/li\u003e\n\u003cli\u003eLiu P, Zhang G, Xu H, Cheng S, Huang Y, Ouyang B, Qian Y, Zhang R, Che R (2023) Synergistic dielectric-magnetic enhancement via phase-evolution engineering and dynamic magnetic resonance. Adv Funct Mater 33:2211298. https://doi.org/10.1002/adfm.202211298\u003c/li\u003e\n\u003cli\u003eHan Y, He M, Hu J, Liu P, Liu Z, Ma Z, Ju W, Gu J (2023) Hierarchical design of FeCo-based microchains for enhanced microwave absorption in C band. Nano Res. 16:1773\u0026ndash;1778. https://doi.org/10.1007/s12274-022-5111-y\u003c/li\u003e\n\u003cli\u003eLiu P, Li Y, Xu H, Shi L, Kong J, Lv X, Zhang J, Che R (2024) Hierarchical Fe-Co@TiO\u003csub\u003e2\u003c/sub\u003e with incoherent heterointerfaces and gradient magnetic domains for electromagnetic wave absorption. ACS Nano 18:560\u0026ndash;570. https://doi.org/10.1021/acsnano.3c08569\u003c/li\u003e\n\u003cli\u003eWu Z, Cheng H-W, Jin C, Yang B, Xu C, Pei K, Zhang H, Yang Z, Che R (2022) Dimensional Design and Core\u0026ndash;Shell Engineering of Nanomaterials for Electromagnetic Wave Absorption. Adv Mater 34:2107538. https://doi.org/10.1002/adma.202107538\u003c/li\u003e\n\u003cli\u003eCui M, Wu T, Gao Z, Hui S, Zhang Y, Wei Y, Zhang J, Wu H (2024) Co/C nanocomposites with tunable condensed states induced by conformation-mediated strategy for electromagnetic wave absorption. Small 20:2402078. https://doi.org/10.1002/smll.202402078\u003c/li\u003e\n\u003cli\u003eXing Y, Fan Y, Wang J, Wang M, Xuan Q, Ma Z, Guo W, Mai L (2024) In situ induced interface engineering in hierarchical Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e enhances performance for alkaline solid-state energy storage. ACS Nano 18:18444\u0026ndash;18456. https://doi.org/10.1021/acsnano.4c03301\u003c/li\u003e\n\u003cli\u003eZhang H, Zhang M, Liu R, He T, Xiang L, Wu X, Piao Z, Jia Y, Zhang C, Li H, Xu F, Zhou G, Mai Y (2024) Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e-doped mesoporous carbon cathode with a plumber\u0026rsquo;s nightmare structure for high-performance Li-S batteries. Nat Commun 15:5451. https://doi.org/10.1038/s41467-024-49826-5\u003c/li\u003e\n\u003cli\u003eWei Z, Cai Y, Zhan Y, Meng Y, Pan N, Jiang X, Xia H (2024) Ultra-low loading of ultra-small Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e nanoparticles on nonmodified CNTs to improve green EMI shielding capability of rubber composites. Small 20:2307148. https://doi.org/10.1002/smll.202307148\u003c/li\u003e\n\u003cli\u003eXue Y, Liu X, Lu X. (2024) Hierarchically three-dimensional ZrO\u003csub\u003e2\u003c/sub\u003e/Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e/C nanocomposites with Janus structure for high-efficiency electromagnetic wave absorption. J Mater Sci Technol 195:126\u0026ndash;135. https://doi.org/10.1016/j.jmst.2024.02.031\u003c/li\u003e\n\u003cli\u003eSun Y, Liu Y, Zou Y, Wang J, Bai F, Yan J, Huang F (2024) Poorly-/well-dispersed Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e: Abnormal influence on electromagnetic wave absorption behavior of high-mechanical performance polyurea. Chem Eng J 493:152833. https://doi.org/10.1016/j.cej.2024.152833\u003c/li\u003e\n\u003cli\u003eWang X, Xing X, Zhu H, Li J, Liu T (2023) State of the art and prospects of Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e/carbon microwave absorbing composites from the dimension and structure perspective. Adv Colloid Interface Sci 318:102960. https://doi.org/10.1016/j.cis.2023.102960\u003c/li\u003e\n\u003cli\u003eDai B, Dong F, Wang H, Qu Y, Ding J, Ma Y, Ma M, Li T (2023) Fabrication of CuS/Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e@polypyrrole flower-like composites for excellent electromagnetic wave absorption. J Colloid Interface Sci 634:481\u0026ndash;494. https://doi.org/10.1016/j.jcis.2022.12.029\u003c/li\u003e\n\u003cli\u003eHe P, Ma W, Xu J, Wang Y, Cui Z-K, Wei J, Zuo P, Liu X, Zhuang Q (2023) Hierarchical and orderly surface conductive networks in yolk-shell Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e@C@Co/N-doped C microspheres for enhanced microwave absorption. Small 19:2302961. https://doi.org/10.1002/smll.202302961\u003c/li\u003e\n\u003cli\u003eLi W, Li B, Zhao Y, Wei X, Guo F (2023) Facile synthesis of Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e nanoparticles/reduced graphene oxide sandwich composites for highly efficient microwave absorption. J Colloid Interface Sci 645:76\u0026ndash;85. https://doi.org/10.1016/j.jcis.2023.04.131\u003c/li\u003e\n\u003cli\u003eWang H, Qu Q, Gao J, He Y (2023) Enhanced electromagnetic wave absorption of Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e@MnO\u003csub\u003e2\u003c/sub\u003e@Ni-Co/C composites derived from Prussian blue analogues. Nanoscale 15:8255\u0026ndash;8269. https://doi.org/10.1039/D3NR00868A\u003c/li\u003e\n\u003cli\u003eFeng A, Lan D, Liu J, Wu G, Jia Z (2024) Dual strategy of A-site ion substitution and self-assembled MoS\u003csub\u003e2\u003c/sub\u003e wrapping to boost permittivity for reinforced microwave absorption performance. J Mater Sci Technol 180:1\u0026ndash;11. https://doi.org/10.1016/j.jmst.2023.08.060\u003c/li\u003e\n\u003cli\u003eWang J, Wu Z, Yang C, Chen G, Yuan M, Li B, Lai Y, Che R (2024) Controllable regulation of MoS\u003csub\u003e2\u003c/sub\u003e surface atomic exposure for boosting interfacial polarization and microwave absorption. Adv Funct Mater 2409923. https://doi.org/10.1002/adfm.202409923\u003c/li\u003e\n\u003cli\u003eLiu Y, Wang F, Wang Y, Hu B, Xu P, Han X, Du Y. (2024) A combined engineering of hollow and core-shell structures for C@MoS\u003csub\u003e2\u003c/sub\u003e microcapsules toward high-efficiency electromagnetic absorption. Composites, Part B Engineering. 273:111244. https://doi.org/10.1016/j.compositesb.2024.111244\u003c/li\u003e\n\u003cli\u003eHe Z, Xu H, Shi L, Ren X, Kong J, Liu P (2024) Hierarchical Co\u003csub\u003e2\u003c/sub\u003eP/CoS\u003csub\u003e2\u003c/sub\u003e@C@MoS\u003csub\u003e2\u003c/sub\u003e composites with hollow cavity and multiple phases toward wideband electromagnetic wave absorption. Small 20:2306253. https://doi.org/10.1002/smll.202306253\u003c/li\u003e\n\u003cli\u003eWu F, Ling M, Zhang L, Zhang Q, Zhang B (2024) Phase-incorporation-induced electromagnetic coupling of NFS@1T/2H-MoS\u003csub\u003e2\u003c/sub\u003e for enhanced microwave absorption. Composites, Part B 270:111136. https://doi.org/10.1016/j.compositesb.2023.111136\u003c/li\u003e\n\u003cli\u003eGai L, Zhao H, Li X, Wang P, Yu S, Chen Y, Wang C, Lan D, Han F, Du Y. (2024) Shell engineering afforded dielectric polarization prevails and impedance amelioration toward electromagnetic wave absorption enhancement in nested-network carbon architecture. Chem Eng J 501:157556. https://doi.org/10.1016/j.cej.2024.157556\u003c/li\u003e\n\u003cli\u003ePeng Q, Yu W, Gao C, Geng L, Fatehi P, Wang S, Kong F (2025) The synergistic effect of hybridization-micro/nano-structural design on the Ti\u003csub\u003e3\u003c/sub\u003eC\u003csub\u003e2\u003c/sub\u003eTx MXene@CoFe-MOF@chitosan heterojunction enhances the absorption of electromagnetic waves. Adv Compos Hybrid Mater 8:232. https://doi.org/10.1007/s42114-025-01305-1\u003c/li\u003e\n\u003cli\u003eJia Z, Sun L, Gao Z, Lan D (2024) Modulating magnetic interface layer on porous carbon heterostructures for efficient microwave absorption. Nano Res 17:10099\u0026ndash;10108. https://doi.org/10.1007/s12274-024-6939-0\u003c/li\u003e\n\u003cli\u003eHe M, Hu J, Yan H, Zhong X, Zhang Y, Liu P, Kong J, Gu J (2024) Shape anisotropic chain-like CoNi/polydimethylsiloxane composite films with excellent low-frequency microwave absorption and high thermal conductivity. Adv Funct Mater 2316691. https://doi.org/10.1002/adfm.202316691\u003c/li\u003e\n\u003cli\u003eShu X, Zhou J, Lian W, Jiang Y, Wang Y, Shu R, Liu Y, Han J, Zhuang Y (2021) Size-morphology control, surface reaction mechanism and excellent electromagnetic wave absorption characteristics of Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e hollow spheres. J Alloys Compd 854:157087. https://doi.org/10.1016/j.jallcom.2020.157087\u003c/li\u003e\n\u003cli\u003eZhong X, He M, Zhang C, Guo Y, Hu J, Gu J (2024) Heterostructured BN@Co-C@C endowing polyester composites excellent thermal conductivity and microwave absorption at C Band. Adv Funct Mater 34:2313544. https://doi.org/10.1002/adfm.202313544\u003c/li\u003e\n\u003cli\u003eZhao B, Yan Z, Liu L, Zhang Y, Guan L, Guo X, Li R, Che R, Zhang R (2024) A liquid-metal-assisted competitive galvanic reaction strategy toward indium/oxide core-shell nanoparticles with enhanced microwave absorption. Adv Funct Mater 34:2314008. https://doi.org/10.1002/adfm.202314008\u003c/li\u003e\n\u003cli\u003eMeng X, Qiao J, Liu J, Wu L, Wang Z, Wang F (2024) Core-shell nanofibers/polyurethane composites obtained through electrospinning for ultra-broadband electromagnetic wave absorption. Adv Compos Hybrid Mater 7:149. https://doi.org/10.1007/s42114-024-00976-6\u003c/li\u003e\n\u003cli\u003eGai L, Wang Y, Wan P, Yu S, Chen Y, Han X, Xu P, Du Y. (2024) Compositional and hollow engineering of silicon carbide/carbon microspheres as high-performance microwave absorbing materials with good environmental tolerance. Nano-Micro Lett 16:167. https://doi.org/10.1007/s40820-024-01369-6\u003c/li\u003e\n\u003cli\u003eNing M, Lei Z, Tan G, Man Q, Li J, Li R-W (2021) Dumbbell-like Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e@N-doped carbon@2H/1T-MoS\u003csub\u003e2\u003c/sub\u003e with tailored magnetic and dielectric loss for efficient microwave absorbing. ACS Appl Mater Interfaces 13:47061\u0026ndash;47071. https://doi.org/10.1021/acsami.1c13852\u003c/li\u003e\n\u003cli\u003eLiu Y, Tian C, Wang F, Hu B, Xu P, Han X, Du Y (2023) Dual-pathway optimization on microwave absorption characteristics of core-shell Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e@C microcapsules: Composition regulation on magnetic core and MoS\u003csub\u003e2\u003c/sub\u003e nanosheets growth on carbon shell. Chem Eng J 461:141867. https://doi.org/10.1016/j.cej.2023.141867\u003c/li\u003e\n\u003cli\u003eWang G, Zhang G, Ke X, Chen X, Chen X, Wang Y, Huang G, Dong J, Chu S, Sui M (2022) Direct synthesis of stable 1T-MoS\u003csub\u003e2\u003c/sub\u003e doped with Ni single atoms for water splitting in alkaline media. Small 18:2107238. https://doi.org/10.1002/smll.202107238\u003c/li\u003e\n\u003cli\u003eJia Z, Liu J, Gao Z, Zhang C, Wu G (2024) Molecular intercalation-induced two-phase evolution engineering of 1T and 2H-MS\u003csub\u003e2\u003c/sub\u003e (M = Mo, V, W) for interface-polarization-enhanced electromagnetic absorbers. Adv Funct Mater 2405523. https://doi.org/10.1002/adfm.202405523\u003c/li\u003e\n\u003cli\u003eYan Y, Zhang K, Qin G, Gao B, Zhang T, Huang X, Zhou Y (2024) Phase engineering on MoS\u003csub\u003e2\u003c/sub\u003e to realize dielectric gene engineering for enhancing microwave absorbing performance. Adv Funct Mater 2316338. https://doi.org/10.1002/adfm.202316338\u003c/li\u003e\n\u003cli\u003eXu C, Luo K, Du Y, Zhang H, Lv X, Lv H, Zhang R, Zhang C, Zhang J, Che R (2023) Anisotropic interfaces support the confined growth of magnetic nanometer-sized heterostructures for electromagnetic wave absorption. Adv Funct Mater 33:2307529. https://doi.org/10.1002/adfm.202307529\u003c/li\u003e\n\u003cli\u003eLi L, Pan F, Guo H, Jiang H, Wang X, Yao K, Yang Y, Yuan B, Abdalla I, Che R, Lu W (2024) Tailored magnetic spatial confinement with enhanced polarization and magnetic response for electromagnetic wave absorption. Small 2402564. https://doi.org/10.1002/smll.202402564 \u003c/li\u003e\n\u003cli\u003eZhang Y, Yang S-H, Xin Y, Cai B, Hu P-F, Dai H-Y, Liang C-M, Meng Y-T, Su J-H, Zhang X-J, Lu M, Wang G-S (2024) Designing symmetric gradient honeycomb structures with carbon-coated iron-based composites for high-efficiency microwave absorption. Nano-Micro Lett 16:234. https://doi.org/10.1007/s40820-024-01435-z\u003c/li\u003e\n\u003cli\u003eHuang W, Wang W, Su C, Song M, Kang Y, Fei G (2024) Hetero-interface engineering on 9.0 wt% CoO\u003cem\u003e\u003csub\u003ex\u003c/sub\u003e\u003c/em\u003e-doped CeO\u003csub\u003e2\u003c/sub\u003e nanorods as electromagnetic wave absorber and integrated into multifunctional aerogel. Small 20:2311389. https://doi.org/10.1002/smll.202311389\u003c/li\u003e\n\u003cli\u003eGuo Y, Long H, Wang Z, Luo S, Xu L, Liu C, Shen C, Liu H (2025) Self-catalyzed growth of Co-N codoped carbon nanotubes for advanced multi-heterointerface engineering in hierarchical carbonaceous microwave absorbers. Adv Compos Hybrid Mater 8:207. https://doi.org/10.1007/s42114-024-01209-6\u003c/li\u003e\n\u003cli\u003eZhao T, Lan D, Jia Z, Gao Z, Wu G (2024) Hierarchical porous molybdenum carbide synergic morphological engineering towards broad multi-band tunable microwave absorption. Nano Res 17:9845\u0026ndash;9856. https://doi.org/10.1007/s12274-024-6938-1\u003c/li\u003e\n\u003cli\u003eHe Q, Tang Q, Yuan Y, Qi J, Sun K, Shi Z, Fan R (2025) Interface decoupling and capacitance modulation in flexible laminated polyetherimide-based nanocomposites via hierarchical incorporation. Adv Compos Hybrid Mater 8:209. https://doi.org/10.1007/s42114-024-01206-9\u003c/li\u003e\n\u003cli\u003eZhang X, Tian X, Wu N, Zhao S, Qin Y, Pan F, Yue S, Ma X, Qiao J, Xu W, Liu W, Liu J, Zhao M, Ostrikov K, Zeng Z (2024) Metal-organic frameworks with fine-tuned interlayer spacing for microwave absorption. Sci Adv 10:eadl6498. https://www.science.org/doi/10.1126/sciadv.adl6498\u003c/li\u003e\n\u003cli\u003eHe M, Zhong X, Lu X, Hu J, Ruan K, Guo H, Zhang Y, Guo Y, Gu J (2024) Excellent low-frequency microwave absorption and high thermal conductivity in polydimethylsiloxane composites endowed by hydrangea-like CoNi@BN heterostructure fillers. Adv Mater 2410186. https://doi.org/10.1002/adma.202410186\u003c/li\u003e\n\u003cli\u003eDeng W, Li T, Li H, Dang A, Liu X, Zhai J, Wu H (2023) Morphology modulated defects engineering from MnO\u003csub\u003e2\u003c/sub\u003e supported on carbon foam toward excellent electromagnetic wave absorption. Carbon 206:192\u0026ndash;200. https://doi.org/10.1016/j.carbon.2023.02.039\u003c/li\u003e\n\u003cli\u003eZhou Z, Lan D, Ren J, Cheng Y, Jia Z, Wu G, Yin P (2024) Controllable heterogeneous interfaces and dielectric modulation of biomass-derived nanosheet metal-sulfide complexes for high-performance electromagnetic wave absorption. J Mater Sci Technol 185:165\u0026ndash;173. https://doi.org/10.1016/j.jmst.2023.11.010\u003c/li\u003e\n\u003cli\u003eZhang M, Wang L, Bao S, Song Z, Chen W, Jiang Z, Xie Z, Zheng L (2023) A finite oxidation strategy for customizing heterogeneous interfaces to enhance magnetic loss ability and microwave absorption of Fe-cored carbon microcapsules. Nano Res 16:11084\u0026ndash;11095. https://doi.org/10.1007/s12274-023-5511-7\u003c/li\u003e\n\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":true,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"advanced-composites-and-hybrid-materials","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"achm","sideBox":"Learn more about [Advanced Composites and Hybrid Materials](https://link.springer.com/journal/42114)","snPcode":"42114","submissionUrl":"https://submission.nature.com/new-submission/42114/3","title":"Advanced Composites and Hybrid Materials","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false},"keywords":"Hollow engineering, core-shell structure, polarization resonance, impedance matching, electromagnetic wave absorption","lastPublishedDoi":"10.21203/rs.3.rs-6546742/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-6546742/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"The development of electromagnetic wave absorbing materials with broadband absorption and thin thickness still confronts huge challenges in addressing the aggravating problem of electromagnetic pollution. Herein, hollow core-shell Fe3O4@MoS2 microspheres with controllable interior and tunable shell are constructed to precisely regulate the corresponding electromagnetic attenuation. The results demonstrate that hollow Fe3O4 microspheres exhibit strong absorption in C-X bands owing to their strong ferromagnetic resonance. Upon structural regulation, hollow core-shell Fe3O4@MoS2 microspheres not only ensure outstanding electromagnetic wave absorption intensity at thin thickness, but also endow broadband absorption characteristics. Benefiting from the cooperative merits of manipulated Fe3O4 interior and controllable MoS2 shells, the as-synthesized microspheres display obvious interface polarization, defect/dipole polarization and multiple scatterings, thereby resulting in improved impedance matching and attenuation capability. Especially for Fe3O4@MoS2-2, the strongest reflection loss is -69.01 dB at 2.66 mm and the effective absorption bandwidth reaches 8.40 GHz when the thickness is 3.0 mm. This study systematically investigates the balance relationship between core-shell structures and absorption attenuation, and simultaneously provides a referable strategy to regulate the electromagnetic wave absorption by structural optimization.","manuscriptTitle":"Hollow Engineering of Core-Shell Fe3O4@MoS2 Microspheres with Controllable Interior toward Optimized Electromagnetic Attenuation","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-06-02 17:06:52","doi":"10.21203/rs.3.rs-6546742/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2025-06-09T12:06:45+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-06-09T07:15:48+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"309737199476239662732692720277183223416","date":"2025-06-03T07:45:14+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-06-02T08:43:23+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"276255482433555773167512298611156877689","date":"2025-05-30T15:14:56+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"222211729495685050760486503873345926715","date":"2025-05-30T11:20:45+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2025-05-30T10:50:24+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2025-05-30T10:48:03+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2025-05-01T03:56:55+00:00","index":"","fulltext":""},{"type":"submitted","content":"Advanced Composites and Hybrid Materials","date":"2025-04-28T10:08:18+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"advanced-composites-and-hybrid-materials","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"achm","sideBox":"Learn more about [Advanced Composites and Hybrid Materials](https://link.springer.com/journal/42114)","snPcode":"42114","submissionUrl":"https://submission.nature.com/new-submission/42114/3","title":"Advanced Composites and Hybrid Materials","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false}}],"origin":"","ownerIdentity":"ac9587b1-050b-4bbe-bc7c-10be4d981137","owner":[],"postedDate":"June 2nd, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"published-in-journal","subjectAreas":[],"tags":[],"updatedAt":"2025-07-14T15:58:59+00:00","versionOfRecord":{"articleIdentity":"rs-6546742","link":"https://doi.org/10.1007/s42114-025-01393-z","journal":{"identity":"advanced-composites-and-hybrid-materials","isVorOnly":false,"title":"Advanced Composites and Hybrid Materials"},"publishedOn":"2025-07-11 15:56:59","publishedOnDateReadable":"July 11th, 2025"},"versionCreatedAt":"2025-06-02 17:06:52","video":"","vorDoi":"10.1007/s42114-025-01393-z","vorDoiUrl":"https://doi.org/10.1007/s42114-025-01393-z","workflowStages":[]},"version":"v1","identity":"rs-6546742","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-6546742","identity":"rs-6546742","version":["v1"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}