Liquid metal assisted dual hydroxide heterostructures of carbonyl iron powder for multifunctional electromagnetic wave absorption

Abstract

Electromagnetic wave (EMW) absorbers for complex environments require appropriate impedance matching, strong absorption, and rapid heat dissipation. Although carbonyl iron powder (CIP) exhibits high magnetic loss, its practical application is hindered by intrinsic oxidation, as well as severe impedance mismatch and low thermal conductivity at low filler loadings. Herein, by applying an ultrasonic cavitation-driven Ga-based liquid metal (LM) encapsulation process, we constructed a core-shell heterostructure (CIP@C@LM), in which an intermediate C shell was introduced to protect the CIP core from severe oxidation and to improve impedance matching. During this process, an oxygen-vacancy rich α-GaOOH outer shell and a small amount of interfacial α-FeOOH form in situ, enabling dielectric-loss dominated attenuation through enhanced polarization relaxation and a secondary magnetic-loss contribution. Consequently, at a filler loading of 60 wt.%, the composite achieves a minimum reflection loss (RL_min) of -52.6 dB at a thickness of 2.31 mm and a maximum effective absorption bandwidth (EAB_max) of 7.56 GHz (10.44-18 GHz) at a thickness of 2.08 mm. The excellent performance significantly outperforms that of the pristine CIP (RL_min = -16.29 dB; EAB_max = 4.17 GHz). Furthermore, the C and dual-hydroxide shells act as a physical barrier and a heat-conducting network, providing strong corrosion resistance and rapid cooling ability (from 96.7 °C to 37.7 °C in 40 s). This work provides new insights into interfacial engineering, offering a viable route toward next-generation multifunctional EMW absorbers.

Keywords

Carbonyl iron powder / dual-hydroxide / oxygen defect / electromagnetic wave absorption / multifunctional

References

[1] Watts CM,Padilla WJ.Metamaterial electromagnetic wave absorbers.Adv Mater2012;24:OP98-120

[2] Cheng J,Ning M.Emerging materials and designs for low- and multi-band electromagnetic wave absorbers: the search for dielectric and magnetic synergy?.Adv Funct Mater2022;32:2200123

[3] Li Y,Chen T,Liu F.An investigation on the electromagnetic wave absorbing performance and corrosion resistance of carbonyl iron powder/epoxy coatings modified by ferrosoferric oxide and basalt fibers.J Colloid Interface Sci2025;683:1-15

[4] Zhang F,Shi J.Recent progress on carbon-based microwave absorption materials for multifunctional applications: a review.Compos Part B Eng2024;283:111646

[5] Rao L,Qian Y.Heterointerface engineering in porous microspheres for magnetic-dielectric balance to boost electromagnetic wave absorption.Chem Eng J2024;488:150955

[6] Zhang Y,Yang S,Dong T.Enhanced anti-corrosion and microwave absorption performance of coating with TiO₂-wrapped carbonyl iron-modified composites.Ceram Int2024;50:25216-27

[7] Li W,Lv J.Electromagnetic and oxidation resistance properties of core-shell structure flaked carbonyl iron powder@SiO₂ nanocomposite.Phys Status Solidi (a)2017;214:1600747

[8] Chen Q,Wang Z,Zhou C.Synthesis and enhanced microwave absorption performance of CIP@SiO₂@Mn_0.6Zn_0.4Fe₂O₄ ferrite composites.J Alloys Compd2019;779:720-7

[9] Gao Q,He E.3D printed fabrication of ultra-structured composites of carbonyl iron powder@carbon@carbon black/polylactic acid for efficient microwave absorption.Polym Compos2024;45:13829-43

[10] Ye X,He E.Graphene/carbonyl iron powder composite microspheres enhance electromagnetic absorption of 3D printing composites.J Alloys Compd2023;937:168443

[11] Lu S,Zhang D.Facile constructing core-shell F-CIP@O/N-SWCNHs composites for high-performance microwave absorption and anti-corrosion.Carbon2024;230:119632

[12] Fan M,Pang H.Microwave absorption enhancement of CIP/PANI composites.Synth Met2013;166:1-6

[13] Zhang Y,Dong T.The synergistic enhancement of microwave absorption performance and corrosion resistance of FeCo by polypyrrole-M16 and TiO₂.J Colloid Interface Sci2025;686:829-43

[14] Li Y,Zhang H.Lightweight carbonyl iron powder-based yolk-shell architectures for integrated electromagnetic wave absorption and thermal protection.Carbon2026;246:120959

[15] Li Y,Zhang H.Lightweight yolk-shell EW@Void@ZrO₂ composites for electromagnetic wave absorption and multifunctional integration.J Alloys Compd2025;1044:184388

[16] Li X,Wu J.Stretchable and leakage-free liquid metal networks for thermal management.Adv Funct Mater2025;35:2420839

[17] Daeneke T,Mahmood N.Liquid metals: fundamentals and applications in chemistry.Chem Soc Rev2018;47:4073-111

[18] Bo G,Xu X,Dou S.Recent progress on liquid metals and their applications.Adv Phys X2018;3:1446359

[19] Lin Y,Dickey MD.Attributes, fabrication, and applications of gallium-based liquid metal particles.Adv Sci2020;7:2000192

[20] Zhao B,Lv H.Self-healing liquid metal magnetic hydrogels for smart feedback sensors and high-performance electromagnetic shielding.NanoMicro Lett2023;15:79

[21] Tian H,Zhang W.Recent advances for core-shell gallium-based liquid metal particles: properties, fabrication, modification, and applications.Nanoscale2025;17:11934-59

[22] Jung W,Kwon K.Giant decrease in interfacial energy of liquid metals by native oxides.Adv Mater2024;36:e2406783 PMCID:PMC11602690

[23] Zhao KY,Huang ML,Wang M.Constructing multi-layer heterogeneous interfaces in liquid metal graphite hybrid powder: towards microwave absorption enhancement.J Colloid Interface Sci2025;677:79-89

[24] Guan G.A synergistic strategy of liquid metal and FeCoNi alloy for high-performance and corrosion-resistant microwave absorbers.Appl Surf Sci2026;721:165502

[25] Xie K,Chen F.Largely enhanced electromagnetic wave absorption via surface coating of carbonyl iron particles with liquid metal.J Mater Chem A2025;13:1887-96

[26] Zhao B,Lv H.Liquid-metal-assisted programmed galvanic engineering of core-shell nanohybrids for microwave absorption.Adv Funct Mater2023;33:2302172

[27] Hwang H,Baek J,Kim Y.Engineering liquid metal particles: design rules for sonication-based methods.Nano Lett2025;25:9881-90 PMCID:PMC12203638

[28] Zhang T,Deng L.Friction-assisted liquid metal-driven anchoring of low redox potential metal ions for enhanced electromagnetic wave absorption.Adv Sci2025;12:e11810

[29] Eskin DG,Wang F.Fundamental studies of ultrasonic melt processing.Ultrason Sonochem2019;52:455-67

[30] Khan MR,Bowden EF.Giant and switchable surface activity of liquid metal via surface oxidation.Proc Natl Acad Sci U S A2014;111:14047-51 PMCID:PMC4191764

[31] Chen G,Zhang L,Chen Q.Dual relaxation behaviors driven by a homogeneous and stable dual-interface charge layer based on an EGaIn absorber.Mater Horiz2025;12:1629-39

[32] Gan T,Shang W.GaOOH crystallite growth on liquid metal microdroplets in water: influence of the local environment.Langmuir2022;38:14475-84

[33] Miao Y,Wang C.Regulating oxygen vacancies to enhance dipole and interface polarization for highly efficient electromagnetic wave absorption in SiC@MnO₂ nanocomposites.Adv Funct Mater2025;35:2503394

[34] Wang T,Miao Y.Enhancing defect-induced dipole polarization strategy of SiC@MoO₃ nanocomposite towards electromagnetic wave absorption.NanoMicro Lett2024;16:273 PMCID:PMC11327238

[35] Su Z,Lu J.Oxygen-vacancy-rich Fe₃O₄/carbon nanosheets enabling high-attenuation and broadband microwave absorption through the integration of interfacial polarization and charge-separation polarization.J Mater Chem A2022;10:8479-90

[36] Sinha G,Zaldivar MH.Synthesis of α-GaO(OH) nanorods and their optical properties.J Nanosci Nanotechnol2010;10:1982-8

[37] Feng J,Fang L.Uniform gallium oxyhydroxide nanorod anodes with superior lithium-ion storage.RSC Adv2019;9:34896-901 PMCID:PMC9074124

[38] Kim JH,Dickey MD,Koo HJ.Interface of gallium-based liquid metals: oxide skin, wetting, and applications.Nanoscale Horiz2024;9:1099-119

[39] Zhang S,Jiang M,Zhou Z.Single-step synthesis of magnetic activated carbon from peanut shell.Mater Lett2015;157:281-4

[40] Gatsi N,Moloto N.Hierarchically-ordered nanorods of Ga₂O₃ derived from microwave-assisted hydrothermal approach: Investigation of calcination-induced structural evolution and optical behavior.Mater Today Commun2022;33:104808

[41] Ishikawa T,Kandori K.Transformation of γ-FeOOH to α-FeOOH in acidic solutions containing metal ions.Colloids Surf A Physicochem Eng Asp2005;266:155-9

[42] Sharma A,Saraswat H.Nano-structured phases of gallium oxide (GaOOH, α-Ga₂O₃, β-Ga₂O₃, γ-Ga₂O₃, δ-Ga₂O₃, and ε-Ga₂O₃): fabrication, structural, and electronic structure investigations.Int Nano Lett2020;10:71-9

[43] Abrashev MV,Stefanov BS,Rosell J.Raman spectroscopy of alpha-FeOOH (goethite) near antiferromagnetic to paramagnetic phase transition.J Appl Phys2020;127:205108

[44] Vequizo J,Ichimura M.Fabrication of Cu₂O/Fe-O heterojunction solar cells by electrodeposition.Thin Solid Films2015;597:83-7

[45] Endo M,Karaki T.Structural analysis of the B-doped mesophase pitch-based graphite fibers by Raman spectroscopy.Phys Rev B1998;58:8991-6

[46] Yan X,Chen G,Liu H.Study of structure, tribological properties and growth mechanism of DLC and nitrogen-doped DLC films deposited by electrochemical technique.Appl Surf Sci2004;236:328-35

[47] Zhou Z,Gu L.SiC-based AlN buffer layer and band alignment in Ga₂O₃/AlN/SiC heterojunctions.J Alloys Compd2026;1055:186268

[48] Ni S,Liu J.New insights into the Li-storage mechanism in α-Ga₂O₃ anode and the optimized electrode design.J Power Sources2019;433:126681

[49] Liu R,Dun L.Oxygen vacancy-mediated high-entropy oxide electrocatalysts for efficient oxygen evolution reaction.Mater Today Catal2025;8:100086

[50] Quan B,Ji G.Dielectric polarization in electromagnetic wave absorption: review and perspective.J Alloys Compd2017;728:1065-75

[51] Liu Y,Wang H.Synthesis and application of core-shell liquid metal particles: a perspective of surface engineering.Mater Horiz2021;8:56-77

[52] Kumar VB,Porat Z.Sonochemistry of molten gallium.Ultrason Sonochem2023;95:106364 PMCID:PMC10457574

[53] Morris RV,Lawson CA.Spectral and other physicochemical properties of submicron powders of hematite (α-Fe₂O₃), maghemite (γ-Fe₂O₃), magnetite (Fe₃O₄), goethite (α-FeOOH), and lepidocrocite (γ-FeOOH).J Geophys Res Solid Earth1985;90:3126-44

[54] Cheng H,Wang X.Ni flower/MXene-melamine foam derived 3D magnetic/conductive networks for ultra-efficient microwave absorption and infrared stealth.NanoMicro Lett2022;14:63 PMCID:PMC8861240

[55] Wang T,Zhu J,Zhang L.Deep understanding of impedance matching and quarter wavelength theory in electromagnetic wave absorption.J Colloid Interface Sci2021;595:1-5

[56] Liang Q,Zhong-lei M.Analyzing bandwidth on the microwave absorber by the interface reflection model.Chinese Phys Lett2016;33:027502

[57] Xie P,Feng M.Hierarchically porous Co/C nanocomposites for ultralight high-performance microwave absorption.Adv Compos Hybrid Mater2021;4:173-85

[58] Wu N,Zhao C,Xia A.Effects of particle size on the magnetic and microwave absorption properties of carbon-coated nickel nanocapsules.J Alloys Compd2016;656:628-34

[59] Kiwi M.Exchange bias theory.J Magn Magn Mater2001;234:584-95

[60] Yu M,Liu X.Magnetic exchange coupling via constructing hard/soft magnetic interface for stable microwave absorption.Mater Lett2024;359:135902

[61] Cai B,Zhao PY.Interface-induced dual-pinning mechanism enhances low-frequency electromagnetic wave loss.Nat Commun2024;15:3299 PMCID:PMC11024160

[62] Golchinvafa S,Jazirehpour M.Magnetic and microwave absorption properties of FeCo/CoFe₂O₄ composite powders.J Alloys Compd2019;809:151746

[63] Samet M,Boiteux G,Kallel A.Electrode polarization vs. Maxwell-Wagner-Sillars interfacial polarization in dielectric spectra of materials: characteristic frequencies and scaling laws.J Chem Phys2015;142:194703

[64] Yu H,Wen B.Graphene/polyaniline nanorod arrays: synthesis and excellent electromagnetic absorption properties.J Mater Chem2012;22:21679

[65] Knott EF,Tulley MT. Radar cross section, 2th ed.; SciTech Publishing, 2004. https://www.amazon.com/Radar-Cross-Section-Electromagnetics/dp/1891121251 (accessed 2026-07-13).

[66] Jiang Q,Duan J,Jiang J.Achieving RCS reduction via scattering and absorption mechanisms using a chessboard structured composite.Compos Part B Eng2024;275:111312

[67] Mccafferty E.Validation of corrosion rates measured by the Tafel extrapolation method.Corros Sci2005;47:3202-15