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With the accelerating development of electronic technology, how to effectively eliminate electromagnetic radiation pollution has become a critical issue. Electromagnetic wave (EMW) absorption materials have an irreplaceable position in the field of military stealth as well as in the field of electromagnetic pollution control. In order to cope with the complicated electromagnetic environment, the design of multifunctional and multiband high-efficiency EMW absorbers remains a daunting challenge. In this work, a hierarchical porous molybdenum carbide matrix with a three-dimensional porous structure was designed by salt melt synthesis (SMS) strategy. Furthermore, the relationship between the structure and the impedance matching performance was explored by stepwise modification via ultrathin layered MoS2 nanoflakes. Analysis indicates that the extent of modification of hierarchical porous molybdenum carbide by MoS2 nanoflakes modulates the dielectric performance due to differences in morphology and the introduction of heterogeneous structures, along with a dramatic impact on the impedance matching performance. In particular, the prepared MS/MC/PNC-2 composite exhibits a reflection loss (RL) of -55.30 dB at 2.4 mm, and an ultra-broad effective absorption bandwidth (EAB) of 7.60 GHz is obtained at 2.0 mm. The coordination of structure and component enables the absorber to exhibit strong absorption, wide bandwidth, thin thickness, and multi-band absorption characteristics. Noticeably, the effective absorption performance in the broadband for X and Ku is also satisfying, as well as possessing moderate marine anti-corrosion performance. This study contributes to an in-depth understanding of the relationship between impedance matching and EMW absorber performance and provides a reference for the design of multifunctional, multiband microwave absorbing materials. [ABSTRACT FROM AUTHOR]

Texture regulation of metal–organic frameworks (MOFs) is essential for controlling their electromagnetic wave (EMW) absorption properties. This review systematically summarizes the recent advancements in texture regulation strategies for MOFs, including etching and exchange of central ions, etching and exchange of ligands, chemically induced self‐assembly, and MOF‐on‐MOF heterostructure design. Additionally, the EMW absorption mechanisms in approaches based on structure–function dependencies, including nano‐micro topological engineering, defect engineering, interface engineering, and hybrid engineering, are comprehensively explored. Finally, current challenges and future research orientation are proposed. This review aims to provide new perspectives for designing MOF‐derived EMW‐absorption materials to achieve essential breakthroughs in mechanistic investigations in this promising field. [ABSTRACT FROM AUTHOR]

Designing and preparing hollow nanomaterials is one of the most feasible ways to obtain the high-performance electromagnetic wave absorber. To this end, Metal–organic frameworks (MOFs), featuring regular crystalline structures with coordinated metal nodes and organic linkers, have won the widespread attention. Here, the recent progress in the study of MOFs-derived hollow materials for electromagnetic wave absorption are summarized and discussed. Some remarkable examples in the synthesis of hollow structures from MOFs precursors are illustrated in terms of the preparation methods and structural architectures. Thereafter, their characteristics and advantages as electromagnetic wave absorber are analyzed and demonstrated. Finally, it summarizes the current achievements, limitations, and urgent challenges, and provides some views on potential solutions and possible future trends. [ABSTRACT FROM AUTHOR]

The bimetallic solid solution-guided MoS 2 /carbon hybrids derived from FeCu-MPN exhibit tailored and excellent electromagnetic wave absorption performance mainly attributed to the enhanced synergistic effect. [Display omitted] • The bimetallic MoS 2 solid solution-carbon hybrids with designed heterointerfaces are successfully fabricated. • XRD Rietveld refinement is used to investigate the heterointerface structures complementally. • The EAB of 6.48 GHz with RL min of −46.85 dB can be obtained. • The excellent performances are contributed to synergistic effect of various enhanced multiple loss mechanisms. Construction heterointerface of multicomponent hybrid materials is significant and effective to modulate their electromagnetic wave (EMW) absorption performances. Herein, MoS 2 solid solution-carbon hybrids derived from FeCu metal-polyphenolic networks (MPNs) are constructed to investigate the effect of interface manipulation on electromagnetic response. MPNs deposition through bimetal ions exchange dominates the phase contents and interfaces of MoS 2 -based composite by tailoring Fe/Cu ratio. The effects of bimetallic ions exchange on micro-nano structures and morphologies, the relationship between heterointerfaces and absorption performances of these hybrids are investigated systematically. The Cu (Cu2+ and Cu) and Fe (Fe3+ and Fe2+) can intercalate in interlayers of MoS 2 nanosheets and substitute the Mo vacancy, generating abundant point-face typed heterointerfaces. And the introduction of carbon can also form face-face typed heterointerfaces. Profiting from the heterointerfaces constructed by MoS 2 solid solution and carbon, bimetallic MoS 2 solid solution-carbon hybrids (BMSCHs) possess outstanding EMW absorption performances with ultrawide bandwidth. The optimized minimum reflection loss of samples can reach −46.85 dB and the effective absorption bandwidth covers 6.48 GHz at 2.7 mm. Thus, this work can provide significant guidance for the structural design of high-performance EMW absorber based solid solution strategy. [ABSTRACT FROM AUTHOR]

Vacancy engineering presents an appealing method for modifying the electronic structure of spinel architectures. However, based on well-defined vacancy concentrations, how to design anionic vacancies to modulate electromagnetic parameters as well as electromagnetic wave absorption (EMA) properties is less studied. Here, NiCo 2 Se 4 spinel structures were prepared using different selenization methods, and the Se vacancy defect concentration was controlled by changing the annealing temperature, thus regulating the EMA properties. Among them, the design of the hollow structure effectively enhanced the EMA performance. Moreover, the increase of Se vacancy concentration increases the conductivity loss while regulating the electronic structure, and also acts as an unsaturated site to induce the formation of dipoles to optimize the polarization loss. The effective absorption bandwidth (EAB) of NiCo 2 Se 4 -130 reaches 8.48 GHz at 2.4 mm at the highest Se vacancy concentration. This work establishes a direct relationship between vacancy concentration and the electromagnetic wave dissipation capability, offering valuable insights for the development of advanced EMA materials. [ABSTRACT FROM AUTHOR]

Given the remarkable performances of metal frame works (MOFs) and ferrocene containing polymers (FCPs) in electronic devices, the research on integration of structure and function for collaborative optimization of electromagnetic wave (EMW) absorption are still missing. Herein, surface grafting and main chain polymerization methods have been employed on the FCPs modifying zeolitic imidazolate framework-67 (ZIF-67) respectively. Polydopamine-coated ZIF-67 was precursor for grafting type products (ZIF-67@PDA-Fc), while poly (vinyl ferrocene) was for main-chain type products (ZIF-67@PVF). Furthermore, the calcined products, polyhedron capsules structured Co 3 O 4 @C@α-Fe 2 O 3 and Co 3 O 4 /α-Fe 2 O 3 @C microwave absorbers were obtained from ZIF-67@PDA-Fc and ZIF-67@PVF for higher performance EMW absorption. The crystal, morphological and chemical structure was detected via XRD, SEM, TEM, FTIR, Raman, XPS techniques. The EMW absorbability was calculated according to transmission line theory. In particular, the minimum reflection loss (RL min) of Co 3 O 4 @C@α-Fe 2 O 3 reached −52.2 dB at the thickness of 3.7 mm with effective absorption band (f E) 4.4 GHz. It is worth emphasized that the broadest f E was 6.6 GHz obtained at 2.5 mm with RL min reaching −38.4 dB. Additionally, the EMW absorption mechanism was also studied based on the dielectric and magnetic properties. This investigation will push forward further research and practical application of metal organic compounds-based composites. Image 1 • Two metal organic compounds derived composites with ZIF-67 and FCPs (PDA, PVF) were synthesized. • There structural, chemical, and electromagnetic properties were studied in detail. • The f E of ZIF-67@PVF-C reached 6.6 GHz at 2.5 mm with RL min = -52.2 dB. • The excellent EMW absorption performance was contributed to both dielectric and magnetic loss. [ABSTRACT FROM AUTHOR]

[Display omitted] Hollow materials have many advantages when acting as electromagnetic wave (EMW) absorber, such as excellent impedance matching properties, rich micro-interfaces and light weight. In this work, a novel hollow particle with double-shell composed with CuS and Mn(OH) 2 is synthesized by coordination etching, precipitation and sulfuration using tetrakaidecahedral Cu 2 O as template. These hollow particles are expected to be used as improved EMW absorption property at an ultra-wide band. In this hollow particle, tetrakaidecaheral CuS acts as inner shell and Mn(OH) 2 acted as outer shell, thus having rich heterogeneous interfaces which induce strong interfacial polarization. Moreover, the lower electrical conductivity and loose structure of the Mn(OH) 2 shell facilitates the entry of EMW into the absorbers, and the hollow structure in this particle is beneficial to improve the impedance matching according to Maxwell-Garnett (MG) theory. Therefore, hollow CuS@Mn(OH) 2 particles with double-shell exhibit excellent EMW absorption performance. The effective absorption bandwidth (reflection loss (RL) ≤ −10 dB) is 6.88 GHz (from 11.12 GHz to 18 GHz) at 2.3 mm thickness of sample. [ABSTRACT FROM AUTHOR]

Metal-organic frameworks (MOFs) with tunable nano-micro structures ikhas been widely employed on developing electromagnetic wave (EMW) absorption materials (MAMs). However, the electromagnetic (EM) response and EMW absorption mechanism of heterogeneous metallic MOFs derivatives have not been systematically studied. In this work, a series of Ag/ZnO@C hybrid materials with metal-semiconductor heterostructures were prepared by using ZIF-L with adjustable cation exchange. As Zn2+ is replaced by Ag+, the structure of ZIF-L changes gradually, which determined the crystal and structure of Ag/ZnO@C hybrid materials. Finally, the minimum reflection loss (RL min) of the product obtained at 60 ℃ reached − 37.13 dB at 3.0 mm, and the maximum absorption bandwidth (f E) reached 6.8 GHz at 4.0 mm (loading content = 33 wt%). Therefore, this work can provide guidance for the design of hybrid structural MAMs by phase transformation MOFs. [Display omitted] • Ag/ZnO@C hybrid EMAs were fabricated by cation ligand exchange method on Zn-ZIF. • Phase inversion increased polarization loss while decreased conductive loss. • The f E of S3 reached 6.8 GHz, the RL min of S3 reached − 37.13 dB. [ABSTRACT FROM AUTHOR]